ARTICLE | doi:10.20944/preprints202112.0020.v1
Subject: Engineering, Other Keywords: copper; gold; mineralogy; tailings; flotation; value recovery; modelling
Online: 1 December 2021 (16:27:57 CET)
Mining and processing tailings often contain significant amounts of valuable metals, that can represent valuable sources of secondary raw materials. Especially this is case in early-stage operations, in which the head grades were higher, and the tailings were higher grade. These tailings can also present a substantial risk to the environment. Serbia has copper deposits which have been exploited since ancient times, and these operations have generated large amounts of mineral processing tailings. The main objective of this study is to show how valuables can be recovered from chemically and mineralogically challenging tailings. After detailed chemical and mineralogical characterization, the laboratory scale flotation tests focused on evaluating the effect of particle size, different types of collectors, pH, and pulp potential. Based on the test work, copper and gold can be recovered effectively into pyrite concentrate
REVIEW | doi:10.20944/preprints202103.0523.v1
Subject: Keywords: basic copper(II) formate; ‘Black Spots’; chalconatronite; copper(II) hydroxide; copper sulfide; curly malachite; namuwite; sodium copper(II) formate; verdigris
Online: 22 March 2021 (11:50:06 CET)
Information taken from David A. Scott’s book “Copper and Bronze in Art” was crucial for research on copper corrosion products in Stuttgart. Examples discussed are the nature and variability of ‘Black Spots’ (aka ‘Brown Fuzzies’); cupric hydroxide by cleaning, patination, and pigment synthesis; the wondrous phenomenon of curly malachite; chalconatronite formed by contact to soda glass; the formation of copper formates by glass-induced metal corrosion; and synthesis and X-ray diffraction of basic copper acetates (‘verdigris’).
ARTICLE | doi:10.20944/preprints202111.0173.v1
Subject: Life Sciences, Biotechnology Keywords: Multi-copper oxidase; copper-transporter; nutrient-sufficient conditions, white-rot fungus
Online: 9 November 2021 (13:39:50 CET)
This research aimed to establish the relationship between carbon-nitrogen nutritional factors and copper sulfate on laccase activity (LA) by Pleurotus ostreatus. Culture media composition was tested to choose the nitrogen source. Yeast extract (YE) was selected as a better nitrogen source than ammonium sulfate. Then, the effect of glucose and YE concentrations on biomass production and LA as response variables was evaluated using central composite experimental designs with and without copper. The results showed that the best culture medium composition was glucose 45 gL-1 and YE 15 gL-1, simultaneously optimizing these two response variables. The fungal transcriptome was obtained in this medium with or without copper, and the differentially expressed genes were found. Main up-regulated transcripts included three laccase genes (lacc2, lacc6, and lacc10) regulated by copper, whereas the principal down-regulated transcripts included a copper transporter (ctr1) and a regulator of nitrogen metabolism (nmr1). These results suggest that Ctr1, which facilitates the entry of copper in the cell, is regulated by nutrient-sufficiency conditions. Once inside, copper induces transcription of laccase genes. This finding could explain why a 10 to 20-fold increase in LA occurs with copper compared to cultures without copper when using the optimal concentration of YE as nitrogen sources.
ARTICLE | doi:10.20944/preprints201807.0175.v1
Online: 10 July 2018 (11:54:41 CEST)
Computational investigations on the BPE-ligated Cu-catalysed enantioselective addition of enynes to ketones were performed with DFT method. Two BPE-CuMes catalysts, BPE-CuMes and (S,S)-Ph-BPE–CuMes, were employed to probe the reaction mechanism with the emphasis on stereoselectivity. The calculations on the BPE-CuMes system indicate that the actvie metallized enyne intermediate acts as the catalyst for the catalytic cycle. The catalytic cycle involves two steps: 1) the ketone addition to the alkene moiety of the metallized enyne; 2) the metallization of enyne followed by the release of product with the recovery of the active metallized enyne intermediate. The first step accounts for the distribution of the products, and therefore is the stereo-controlling step in chiral systems. In the chiral (S,S)-Ph-BPE–CuMes system, the steric hindrance is vital for the distribution of products and responsible for the stereoselectivity of this reaction. The steric hindrance between the phenyl ring of the two substrates and groups at the chiral centers in the ligand skeleton is identified as the original of the stereoselectivity for the titled reaction.
ARTICLE | doi:10.20944/preprints201811.0279.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: copper importers CTR1 and DMT1; CRICPR-Cas9; cisplatin; silver; signaling; copper homeodynamics
Online: 12 November 2018 (10:05:01 CET)
Copper, the highly toxicity micronutrient, plays two essential roles: it is a catalytic and structural cofactor for Cu-dependent enzymes, and it acts as a secondary messenger. In the cells, copper is imported by CTR1, a transmembrane high-affinity copper importer, and DMT1 (divalent metal transporter). In cytosol, enzyme-specific chaperones receive copper from CTR1 C-terminus and deliver it to their apoenzymes. DMT1 cannot be a donor of catalytic copper because it does not have cytosol domain which is required for copper transfer to the Cu-chaperons and following to cuproenzymes. Here we assume that DMT1 can mediate copper way required for regulatory copper pool. To verify this thought, we used CRISPR/Cas9 to generate H1299 cell line with CTR1 or DMT1 single knockout (KO) and CTR1/DMT1 double knockout (DKO). To confirm KOs of the genes qRT-PCR were used. Two independent clones for each gene were selected for further studies. In CTR1-KO cells, expression of the DMT1 gene was significantly increased. In subcellular compartments, copper concentration decreased dramatically in DKO cells. CTR1-KO cells, but not DMT1-KO, demonstrated reduced sensitivity to cisplatin and silver ions, agents that enter the cell through CTR1. The expression of genes, whose protein products require copper: HIF1α, XIAP, COMMD1, CCS, Cp, but not SOD1 and NF-kB, changed their level. Perhaps these data will help to understand how the disturbances of copper homeodynamics lead to the development of neurodegenerative and oncological disorders. Possibility of using CTR1 KO and DMT1 KO cells to study homeodynamics of catalytic and signaling copper selectively is discussed.
Subject: Engineering, General Engineering Keywords: Copper smelter dust; electrostatic precipitators of copper; removal of arsenic; sulphidisation; roasting process.
Online: 20 August 2020 (09:55:21 CEST)
This paper, the second in a series of two, describes the experimental results for removing arsenic from the dust collected in the electrostatic precipitators of a fluidized bed roasting oven (RP dust). The RP dust produced is discharged as a toxic waste, although its copper content is close to 20% by weight. This work aims to process the RP dust; until obtained a material with a low concentration of arsenic, which could be recirculated in smelting operations and recover the valuable metals. Based on the successful experience obtained in the first document with FS dust, this work proposes to use the reduction-sulphidation-volatilization processes to carry out the volatilization of arsenic from RP dust. A set of experiments was realized in the roasting different ratios of the mixture of copper concentrate / RP dust, sulfur / RP dust varying temperature and roasting time; to reach an arsenic concentration <0.5% by weight. The RP dust was characterized using different techniques, that confirmed more than 20% by weight of copper and describing its structure as a small particle agglomerate (<5 µm), with a complex sulfoxide morphology. The main results indicated: that for a 75/25 mixture of the copper concentrate / PR dust under 700 ° C, 15 minutes roasting time with air atmosphere, the arsenic volatilization was 96% by weight. Meanwhile, for a 5/95 mixture of sulfur / RP dust, at 650 ° C, the volatilization of arsenic was 67% by weight.
Subject: Engineering, General Engineering Keywords: copper smelter dust; electrostatic precipitators of copper; removal of arsenic; sulphidation; roasting process
Online: 18 August 2020 (07:39:38 CEST)
This paper (the first of a series of two) seeks to describe the experimental results of removing arsenic from dust collected in electrostatic precipitators of copper into the pyro-metallurgy gas cleaning systems. The first work corresponds to the treatment of dust contained in gas off generated in the copper Flash Smelting Furnace process (FS dust), while the second focuses on the treatment of dust generated from a Fluidized Bed Roasting Furnace (RP dust). The dust is complex sulphur-oxide-metals with concentrations of copper above 10 wt % and relatively high concentrations of silver. Due to the dust has an arsenic’s concentration above 5 wt %, makes it difficult to recover valuable metals through hydro-metallurgical processes or by direct recirculation of the dust into a smelting furnace. Thus, the development of pyrometallurgical processes aimed to reduce the concentration of arsenic in dust is the main purpose of this study, particularly the production of a material suitable for recirculation in smelting operations. The works conducted provide a detailed characterization of the dust, including Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN), Scanning electron microscope-Energy Dispersive X-ray analysis (SEM/EDS), X-ray diffraction (XR-D), elemental chemical analysis using Atomic Adsorption (A. A.) and X-Ray Fluorescence (X-RF). By considering that arsenic volatilization requires a process of reduction-sulphidation-volatilization, the works explore the roasting of mixtures of copper concentrate/dust, sulphur/dust and pyrrhotite/dust. The degree of volatilization was determined by elemental chemical analysis of arsenic in the mixture after and before the roasting process. The results indicated the effect of parameters such as temperature, gas flow, gas composition and the ratio of mixtures (concentrate, sulphur or pyrrhotite)/dust on the volatilization of arsenic. The findings indicate that the concentration of arsenic in the FS dust can be reduced to a relatively low level (<0.5 wt %), allowing to the material to be recirculated into smelting processes.
ARTICLE | doi:10.20944/preprints202110.0040.v1
Online: 4 October 2021 (10:28:57 CEST)
Impure and pure casts have collected reasonable attentions over all the world. In this paper, Aluminum (Al) and Copper (Cu) cast alloys are considered to be studied. Multiple impure and pure Al-Cu cast alloys are established under the condition of very high temperatures. Then, all of the established alloys are examined by applying mechanical tests. More specifically, tests of hardness are exploited. Moreover, different quenching conditions are employed and analyzed. These are the water, air and oil. Consistent results are separately obtained for the impure and pure materials.
ARTICLE | doi:10.20944/preprints202209.0064.v2
Subject: Biology, Physiology Keywords: Antarctica; antioxidants; cadmium; copper; fish; metallothioneins
Online: 6 October 2022 (09:57:16 CEST)
Metal bioaccumulation and metallothionein (MT) expression were investigated in gills and liver of the red-blooded Antarctic teleost Trematomus hansoni with the aim to evaluate the possibility for this species to face, with adequate physiological responses, an increase of copper or cadmium concentrations in the environment. Specimens of this Antarctic fish were collected from Terra Nova Bay (Ross Sea) and used for a metal exposure experiment in controlled laboratory condi-tions. The two treatments lead to a significant accumulation of both metals and an increase of gene transcription only for the MT-1. The biosynthesis of MTs was verified especially in speci-mens exposed to Cd, but the majority of these proteins were soon oxidized, probably because they were involved in cell protection against the risk of oxidative stress, by reactive oxygen spe-cies scavenging. The obtained data highlighted the phenotypic plasticity of T. hansoni, a species evolved in an environment characterized by natural high concentrations of Cu and Cd, and maybe the possibility for the Antarctic fish to face the challenges of a world that is becoming every day more toxic.
ARTICLE | doi:10.20944/preprints202204.0133.v1
Subject: Materials Science, Metallurgy Keywords: Copper recovery; Thermodynamic equilibrium; Reduction experiment
Online: 14 April 2022 (12:12:46 CEST)
This work discussed the advantages of reducing copper in molten copper slag with low S content. FactSage calculated the distribution of copper at equilibrium under different sulfur content. The effect of sulfur content on copper recovery under different oxygen partial pressures was pointed out. The effect of sulfur content on copper recovery in the actual reduction process was explored through experimental research. Under the condition of low sulfur, the Recovery of copper and the stability of the experiment have an ideal results.
REVIEW | doi:10.20944/preprints202010.0353.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: Copper homeostasis; Cancer; Prognostic; Diagnostic; Therapy
Online: 16 October 2020 (14:32:16 CEST)
In the human body, Copper (Cu) is a major and essential player in a large number of cellular mechanisms and signaling pathways. The involvement of Cu in oxidation-reduction reactions requires close regulation of copper metabolism in order to avoid toxic effects. In many types of cancer, variations in copper protein levels have been demonstrated. These variations result in increased concentrations of intra-tumoral Cu and alterations in the systemic distribution of copper. Such alterations in Cu homeostasis may promote tumor growth or invasiveness, or even confer resistance to treatments. Once characterized, the dysregulated Cu metabolism is pinpointing several promising biomarkers for clinical use, with prognostic or predictive capabilities. The altered Cu metabolism in cancer cells and the different responses of tumor cells to Cu are strongly supporting the development of treatments to disrupt, deplete or increase Cu levels in tumors. The metallic nature of Cu, as a chemical element, is key for the development of anticancer agents via the synthesis of nanoparticles or copper-based complexes with antineoplastic properties for therapy. Finally, some of these new therapeutic strategies such as chelators or ionophores have shown promising results in a preclinical setting, while others are already in the clinic.
ARTICLE | doi:10.20944/preprints202008.0139.v1
Subject: Engineering, Industrial & Manufacturing Engineering Keywords: copper price; prediction; support vector regression
Online: 6 August 2020 (08:26:35 CEST)
Predicting copper price is essential for making decisions that can affect companies and governments dependent on the copper mining industry. Copper prices follow a time series that is non-linear, non-stationary, and which have periods that change as a result of potential growth, cyclical fluctuation and errors. Sometimes the trend and cyclical components together are referred to as a trend-cycle. In order to make predictions, it is necessary to consider the different characteristics of trend-cycle. In this paper, we study a copper price prediction method using Support Vector Regression. This work explores the potential of the Support Vector Regression with external recurrences to make predictions at 5, 10, 15, 20 and 30 days into the future in the copper closing price at the London Metal Exchanges. The best model for each forecast interval is performed using a grid search and balanced cross-validation. In experiments on real data-sets, our results obtained indicate that the parameters (C, ε, γ) of the model Support Vector Regression do not differ between the different prediction intervals. Additionally, the amount of preceding values used to make the estimates does not vary according to the predicted interval. Results show that the support vector regression model has a lower prediction error and is more robust. Our results show that the presented model is able to predict copper price volatilities near reality, being the RMSE equal or less than the 2.2% for prediction periods of 5 and 10 days.
ARTICLE | doi:10.20944/preprints202003.0253.v1
Online: 16 March 2020 (01:16:25 CET)
Surface Plasmon Resonance (SPR) is an attracting property of certain transition metals when they are synthesized in nano-range giving rise to promising optical applications. However, most SPR and associated applications are limited to the noble metal nanoparticles, which limits their potential due to high production cost. We report surface plasmon resonance in copper-copper oxide core-shell quantum dots synthesized via chemical route studied by using UV-Visible spectrophotometry. Tuning of the plasmonic resonance with respect to the particle diameter is achieved by an inexpensive all chemical route. Photoluminescence measurements also support the data. This size reduction leads to remarkable changes in its optical response as compared to the bulk metal. The results point towards applications of these materials in tunable SPR based biosensors.
ARTICLE | doi:10.20944/preprints202001.0057.v1
Subject: Earth Sciences, Environmental Sciences Keywords: biosorption; copper; algae; tailings; mine waste
Online: 8 January 2020 (03:06:34 CET)
Mining is one of the main economic activities of several developing countries as Chile. Due to the progressive fall of the ore grades and the increasingly refractory composition of minerals, concentrating plants have increased that has led to an increase in the generation of tailings. Tailings, especially those obtained in the past, have remaining copper and other valuable species in quantities that can potentially be recovered, such as gold, silver, vanadium and rare earth elements. This transforms this abundant waste into a potential source of precious or strategic metals for secondary mining. One of the techniques of solid-liquid separation that allows the processing of solutions with low concentrations of metals corresponds to the adsorption, and more recently the biosorption, which is based on the use of biological matrices that do not constitute an environmental liability after application. Biosorption occurs as a consequence of the wide variety of active functional groups present in the different types of biomass. Bacterial, fungal, plant and algal biomasses have been described as biosorbents, mainly for the treatment of diluted and simple solutions. This work aims to recover copper from leached tailings using biomass of the red algae Gracilaria chilensis as a biosorbent. The tailing samples were taken from an abandoned deposit in the north of Chile and after an acid leaching copper was biosorbed, for which the kinetics of adsorption and the equilibrium isotherms were studied, applying the Freundlich and Langmuir models. Operational parameters such as adsorbent dose, pH and initial metal concentration were studied.
ARTICLE | doi:10.20944/preprints201909.0185.v1
Subject: Materials Science, Metallurgy Keywords: activated carbon; adsorption; copper; winemaking wastes
Online: 17 September 2019 (11:44:45 CEST)
This article presents the copper ions adsorption process using an activated carbon from winemaking wastes. The pH, temperature, activated carbon amount and initial copper concentration were varied based on a full factorial 2k experimental design. Kinetic and thermodynamic studies were also carried out. The adsorption kinetics was found follow a pseudo-second-order model. The adsorption data fit better to the Langmuir isotherm. The ANOVA demonstrated that both pH of the solution and activated carbon dosage had the greatest influence on copper adsorption. The activation energy was -32 kJ·mol-1 suggesting that the copper adsorption is a physic-sorption process. The best fit to a linear correlation was the moving boundary equation that controls the kinetics for the adsorption copper ions onto the activated carbon. The X-ray photoelectron spectroscopy (XPS) results reveal the existence of different copper species (Cu2+, Cu+ and or Cu0) on the surface of the carbonaceous adsorbent after the adsorption, which could suggest a simultaneous reduction process.
ARTICLE | doi:10.20944/preprints201808.0310.v1
Subject: Earth Sciences, Geochemistry & Petrology Keywords: Svalbard, Sigurd, copper, silver, gold, geochemistry
Online: 17 August 2018 (13:05:11 CEST)
One of the largest in the archipelago silver-copper mineralisation at Mount Sigurdf′ellet in West Spitsbergen Island was found in 1990 by Russian geologists. Firstly genesis was caused exclusively with hydrothermal ore migration of a substance from the enclosing sandstone and siltstone of the Devonian age. But subsequent work on the ore and nearest rocks of the basement gave a new factual material on the geochemical characteristics of potential sources of metals and found new for this mineral occurrence - gold mineralization. Similarity of geochemical associations of Sigurd ore occurrence with nearby upper Proterozoic marble as the first likely source of ore substance and the second - caused by carbonate-containing streaks in Low Devonian sediments. Ore-formation, probably due to repeated hydrothermal processes and was completed in a period of tectono-magmatic activity in Jurassic-Cretaceous time.
ARTICLE | doi:10.20944/preprints201905.0129.v1
Subject: Materials Science, Other Keywords: Alkaline copper quat (ACQ); Boric acid (BA); Micronized copper quat (MCQ); Nano boron (NB); Corrosion test
Online: 10 May 2019 (14:36:07 CEST)
In this study, the corrosion performances of ammonium copper quat (ACQ) and boric acid (BA) wood preservatives were investigated, with micronized copper quat (MCQ) and nano boron (NB) used as reference materials. In the study, Scots pine (Pinus sylvestris L.) wood samples were impregnated according to the full-cell process method with ACQ at 2.4% concentration, BA at 4% and MCQ and NB at 1%. The ACQ- and BA-impregnated samples were then impregnated for a second time using five different water-repellent materials: tall oil, linseed oil, sodium silicate, methyl hydrogen silicone and N'-N- (1, 8-Naphthalyl) hydroxylamine. Polyethylene glycol (PEG) 600 and aluminum sulfate were introduced as single impregnations in the form of homogeneous mixtures with the ACQ and BA. The corrosion properties of the impregnated and control samples, including metal weight loss (MWL) and corrosion depth, were examined. As a result, the MWL values of the ACQ-impregnated samples showed an increase compared to the control group. The MWL values of the MCQ-impregnated samples were lower than those of the samples impregnated with ACQ, whilst the MWL values of the BA-impregnated samples were higher than those of the samples impregnated with NB.
CASE REPORT | doi:10.20944/preprints202205.0111.v1
Subject: Medicine & Pharmacology, Obstetrics & Gynaecology Keywords: Intrauterine device; cervical perforation; hysteroscopy; copper; strings
Online: 9 May 2022 (10:00:28 CEST)
Abstract Purpose Since their introduction, intrauterine devices (IUDs) have been associated with various complications. Avery rare complication is the perforation of the cervix by the strings of the IUD. Purpose of the current study is to present a novel case of cervical perforation by the strings of a copper IUD and to perform a systematic review of the literature. Materials and Methods The patient a 43-year-old attended the gynecology clinic in order to remove her copper IUD. Speculum examination revealed that both the strings of the IUD perforated the anterior lip of the cervix. Management options were offered, the patient opted for a hysteroscopic removal. We searched the electronic databases: MEDLINE, Cochrane Library,Google Scholar,EBSCO for similar cases. Results Electronic search yielded 1821 articles; 8 were selected for inclusion. Mean age of the women was 35,37±7,781, range (26-47) years. One woman (12.5%) was nulligravida;3 women were multigravida (37,5%). Seven women (87,5%) were asymptomatic. Three IUDs (37,5%) were LNG-IUS; 5 IUDs (62,5%) contained copper. Conclusions Cervical perforation by the strings of IUD is an extremely rare clinical entity. It is asymptomatic in general and in most cases the strings of the IUD may be returned back to the endocervical canal after surgical maneuvers.
ARTICLE | doi:10.20944/preprints202204.0269.v1
Subject: Biology, Ecology Keywords: Antarctic strain; copper stress; adaption responses; metabolomics
Online: 28 April 2022 (03:59:23 CEST)
Copper toxicity has been a selective pressure on the sea-ice bacteria due to its widespread occur-rence in Antarctica. Here, with a combined biochemical and metabolomic approach, the Cu2+ ad-aptation mechanisms of Antarctic bacteria were analyzed. Heavy metal resistance pattern of Pb2+ > Cu2+ > Cd2+ > Hg2+ > Zn2+ was observed. Copper treatment did increase the activity of antioxidants and enzymes, maintaining cellular redox state balance and normal cell division and growth. Metabolomics analysis demonstrated that fatty acids, amino acids, and carbohydrates played dominant roles in copper stress adaptation. The results indicated that the adaptation mechanisms of strain O5 to copper stress included protein synthesis and repair, accumulation of organic per-meable substances, up-regulation of energy metabolism, and formation of fatty acids. This study increases the resistance mechanism understanding of Antarctic strains to heavy metals in extreme environments.
ARTICLE | doi:10.20944/preprints202201.0356.v1
Subject: Materials Science, General Materials Science Keywords: Clinoptilolite zeolite; Nanospecies; Bimetallic system; Copper; Silver
Online: 24 January 2022 (12:58:16 CET)
Long-term changes in nanoparticles of copper-silver bimetallic systems on natural clinoptilolite obtained by ion exchange of Cu2+ and Ag+, and then reduced at different temperatures, have been studied. Even after storage under ambient conditions, XRD and UV-Vis diffuse reflectance spectra indicate the presence of nanospecies of reduced copper and silver. Scanning Electron Microscopy of aged bimetallic samples, reduced at the highest temperature (450oC) and the primary samples for their preparation, also aged, showed the presence of silver nanoparticles with a size of about 100 nm. They are formed in the initial ion-exchanged sample (without reduction) due to the degradation of Ag+ ions. The nanoparticles in the reduced sample are larger; in both samples they are evenly distributed over the surface. The presence of silver affects the stability and the mechanism of decomposition/oxidation of reduced copper nanospecies, and this stability is higher in bimetallic systems. The decomposition pattern of recently reduced species includes the formation of smaller nanoparticles and few-atomic clusters. This can occur, preceding the complete oxidation of Cu to ions. Quasi-colloidal silver, which is present in fresh bimetallic samples reduced at lower temperatures, transforms after aging into Ag8 clusters, which indicates the stability of these nanospecies on natural clinoptilolite.
ARTICLE | doi:10.20944/preprints202005.0131.v1
Subject: Materials Science, Biomaterials Keywords: Saqez; Copper; Physical properties; Biological resistance; Performance
Online: 7 May 2020 (15:08:51 CEST)
There is an increasing interest in applying environmentally-friendly materials in wood protection technology. This include the use of less toxic active ingredients, as well as better fixation. This study investigates the formulation based on the combination of copper and Saqez resin on the physical and biological resistance properties of poplar wood. Samples were treated by either copper-ethanolamine (Cu/MEA) and/or Saqez resin at various treatment levels. A vacuum pressure procedure was applied. The retention, weight percent gain, water absorption, volumetric swelling, and decay resistance of the samples were then determined. The highest retention and weight percent gain were obtained at the samples treated with the combination of copper-based system and Saqez resin. Additionally, the combination of the copper and Saqez improved the physical properties and decay-resistance against white-rot fungus Trametes versicolor.
ARTICLE | doi:10.20944/preprints202001.0177.v1
Online: 17 January 2020 (04:32:53 CET)
Copper smelting slag is a solution of molten oxides created during the copper smelting and refining process, and about 1.5 million tons of copper slag is generated annually in Korea. Oxides in copper smelting slag include ferrous (FeO), ferric oxide (Fe2O3), silica (SiO2 from flux), alumina (AI2O3), calcia (CaO) and magnesia (MgO). Main oxides in copper slag, which iron oxide and silica, exist in the form of fayalite (2FeO·SiO2). Since the copper smelting slag contains high content of iron, and copper and zinc. Common applications of copper smelting slag are the value added products such as abrasive tools, roofing granules, road-base construction, railroad ballast, fine aggregate in concrete, etc., as well as the some studies have attempted to recover metal values from copper slag. This research was intended to recovery Fe-Cu alloy, raw material of zinc and produce reformed slag like a blast furnace slag for blast furnace slag cement from copper slag. As a results, it was confirmed that reduction smelting by carbon at temperatures above 1400°С is possible to recover pig iron containing copper from copper smelting slag, and CaO additives in the reduction smelting assist to reduce iron oxide in the fayalite and change the chemical and mineralogical composition of the slag. Copper oxide in the slag can be easily reduced and dissolved in the molten pig iron, and zinc oxide is also reduced to a volatile zinc, which is removed from the furnace as the fumes, by carbon during reduction process. When CaO addition is above 5wt.%, acid slag has been completely transformed to calcium silicate slag and observed like blast furnace slag.
ARTICLE | doi:10.20944/preprints201909.0252.v1
Subject: Medicine & Pharmacology, Obstetrics & Gynaecology Keywords: copper; endoglin; preeclampsia; VEGF-A; sVEGF-R1
Online: 21 September 2019 (09:51:28 CEST)
Preeclampsia (PE) is characterized by a series of clinical features such as hypertension and proteinuria associated with endothelial dysfunction and the impairment of placenta vascular endothelial integrity. This study aimed to investigate the effect of serum copper (Cu) level on some angiogenesis-related factors including vascular endothelial growth factor-A (VEGF-A), soluble Fms-like tyrosine kinase-1 (sVEGF-R1), soluble endoglin (sEng) and cerruloplasmin (Cp) in Iraqi women with preeclampsia (PE) and control pregnant women. Therefore, 60 women with PE in addition to 30 healthy pregnant women were enrolled in the study. Serum concentration of sEng, VEGF-A, sVEGF-R1, and Cu in PE group significantly increased (p<0.05) in the PE group compared with that in the control group. Increased production of antiangiogenic factors, soluble VEGF-A and sEng contribute to the pathophysiology of PE, indicating the involvement of these parameters in the angiogenic balance in patients with PE. Tests for between-subject effects showed that the circulating angiogenesis factors and Cu were significantly associated with the presence of PE. Serum Cu level was significantly correlated with VEGF- A and VEGF-R1 levels but not with sEng. Multiple regression analysis revealed that only Cp and BP can significantly predict the complications in women with PE. In conclusion, serum Cu has a role in the angiogenesis in women with PE and may be a new drug target in the prevention or treatment of PE.
ARTICLE | doi:10.20944/preprints201807.0344.v1
Subject: Materials Science, General Materials Science Keywords: brazing; alumina dispersion-strengthened copper; mechanical test
Online: 19 July 2018 (05:18:58 CEST)
Alumina dispersion-strengthened copper, Glidcop, is used widely in high-heat-load ultra-high-vacuum components for synchrotron light sources (absorbers), accelerator components (beam intercepting devices) and in nuclear power plants. Glidcop has similar thermal and electrical properties to OFE (oxygen free electrical) copper, but has superior mechanical properties, thus making it a feasible structural material; its yield and ultimate strength are equivalent to those of mild-carbon steel. The purpose of this work has been to develop a brazing technique to join Glidcop to Mo, using a commercial Cu-based alloy. The effects of the excessive diffusion of the braze along the grain boundaries on the interfacial chemistry and joint microstructure, as well as on the mechanical performance of the brazed joints, has been investigated. In order to prevent the diffusion of the braze into the Glidcop alloy, a copper barrier layer has been deposited on Glidcop by means of RF-sputtering.
ARTICLE | doi:10.20944/preprints201803.0023.v1
Online: 2 March 2018 (12:47:16 CET)
The article discusses the validation process of a certain method of balancing gas contained in the pore space of rocks. The validation was based upon juxtaposition of the examination of rocks' porosity and the effects of comminution in terms of assessing the possibility of opening the pore space. The tests were carried out for six dolomite samples taken from different areas of the 'Polkowice-Sieroszowice’ copper mine in Poland. Before the rock material was ground, it was examined using the porosimetric method and subsequently subjected to the SEM analysis. After grinding, the research material was subjected to the granulometric analysis. Prior to the grinding process, the rocks' porosity fell in the range of 0.3-14.8%, while the volume of the open pores was included in the 0.01-0.06 cm3/g range. The research material was also characterized by inhomogeneous distribution of the pore volume. The grinding process was performed using an original device – the GPR analyzer. The ground samples were characterized by similar particle size distribution and mean diameters D_3.2 of about 4.0-4.5 µm. The SEM analysis revealed pores of various size and shape on the surface of the rock cores, while at the same time demonstrating lack of pores following the grinding process. The grain size distribution curves were compared with the cumulative pore volume curves of the cores before grinding. The resulting intersection points of both curves were seen as testifying to the presence of openings in the rock pores and release of the accumulated gas. The opening percentage of the pore space was associated with the coordinates of the curves' intersections. In order to confirm the argument put forward in this paper – i.e. that comminution of a rock to grains of a size comparable with the size of the rock's pores results in the release of gas contained in the pore space – the amount of gas released as a result of the comminution process was studied. The results of gas balancing demonstrated that the pore space of the investigated dolomites was filled with gas in amounts from 3.19 cm3/kg to 45.86 cm3/kg. The obtained results of the rock material comminution to grains comparable – in terms of size – to the size of the pores of investigated rocks, along with asserting the presence of gas in the pore space of the studied dolomites, were regarded as a proof that the method of balancing gas in rocks via rock comminution is correct.
ARTICLE | doi:10.20944/preprints201801.0228.v2
Subject: Materials Science, Metallurgy Keywords: sustainable development, recycling, spent catalysts, zinc, copper
Online: 22 February 2018 (15:46:53 CET)
CuO-ZnO-Al2O3 catalysts are designed for the low-temperature shift conversion in the process of hydrogen and ammonia synthesis gas production. The paper presents the results of research on recovery of copper and zinc from spent catalysts using pyrometallurgical and hydrometallurgical methods. Under reducing conditions, at high temperature, having appropriately selected the composition of the slag, more than 66% of copper in metallic form and about 70% of zinc in the form of ZnO can be extracted from this material. Hydrometallurgical processing of the catalysts was carried out using two leaching solutions: alkaline and acidic. Almost 62% of the zinc contained in the catalysts has been leached to the alkaline solution and about 98% of copper has been leached to the acidic solution. After the hydrometallurgical treatment of the catalysts, insoluble residue was also obtained in the form of pure ZnAl2O4. This compound can be reused to produce catalysts, or it can be processed under reducing conditions at high temperature to recover zinc. The recovery of zinc and copper from such a material is consistent with the policy of sustainable development and helps to reduce the environmental load of stored wastes.
ARTICLE | doi:10.20944/preprints202301.0119.v1
Subject: Earth Sciences, Geoinformatics Keywords: sphalerite; first principle; indium enrichment mechanism; copper; silver
Online: 6 January 2023 (06:54:27 CET)
Sphalerite has been recognized as the most important carrier of critical metal of Indium (In) due to that In mainly exists in the sphalerite lattice by isomorphic substitution. There are two significant replacing schemes for In entry into sphalerite, these are, Ag++In3+→2Zn2+ and Cu++In3+→2Zn2+. In order to understand the reaction process and constraints of the two substitution schemes, this paper uses first-principles methods to calculate In and Ag, Cu replacing Zn in sphalerite. According to the substitution schemes of Ag++In3+→2Zn2+ and Cu++In3+→2Zn2+, two doped sphalerite systems of Zn30InAgS32 and Zn30InCuS32 were constructed using 2×2×2 supercell model of sphalerite. Firstly, the pressure is controlled to 30MPa, and the temperature is set from 20-40MPa to simulate the response of the two doped sphalerite systems to temperature; Then, the control temperature was unchanged to 600K, and the pressure was set from 20-40MPa to investigate the pressure control of the two doped sphalerite systems. The lattice parameters, substitution energy, electronic structure, and population analysis of the designed models before and after replacement have been critically compared. The main conclusions can be drawn that it is more stable for In to enter sphalerite via the coupled substitution scheme Cu++In3+→2Zn2+, and the conditions that the two substitution schemes most likely to occur are 650K and 40MPa. This study not only reveals the physical and chemical properties of In-rich sphalerite formed by the two reaction processes of Ag++In3+→2Zn2+ and Cu++In3+→2Zn2+, but also has a certain enlightenment effect on the search for indium in sphalerite, and promotes the application of first principles in mineralization analysis.
ARTICLE | doi:10.20944/preprints202206.0001.v2
Subject: Engineering, Mechanical Engineering Keywords: copper aluminum oxide; sintering; electrical conductivity; activation energy
Online: 21 July 2022 (02:53:40 CEST)
The current study aimed to evaluate the influence of different sintering temperatures on the properties of copper aluminum oxide (CuAlO2) pellets synthesized from copper oxide (CuO) and aluminum hydroxide (Al(OH)3) for application in smart infrastructure systems. The pellets were sintered at 400 K, 1000 K, and 1300 K, in the presence of nitrogen gas flow to reduce the amount of oxygen availability. The CuAlO2 sintered nanoparticles were chemically analyzed by X-ray diffractometry, and the nanostructure of the materials was studied by scanning electron microscopy. The transmittance of the sintered materials was examined by ultraviolet/visible (UV/Vis) spectrophotometry, and 88% transparency was observed for the pellets sintered at 1300 K. Electrical conductivity was measured at 0.905 mS/cm, indicating a semiconducting behavior.
Subject: Materials Science, Biomaterials Keywords: micromechanics; crystal plasticity; micromorphic; Hall-Petch; copper alloys
Online: 12 July 2021 (11:16:58 CEST)
Doped copper overpacks are planned to be utilized in the spent nuclear fuel repositories in Finland and in Sweden. The assessment of long-term integrity of the material is a matter of importance. Grain structure variations, segregation and any possible manufacturing defects in microstructure are relevant in terms of susceptibility to creep and damage from the loading evolution imposed by its operating environment. This work focuses on studying the microstructure level length-scale dependent deformation behavior of the material, of particular significance with respect to accumulation of plasticity over the extensive operational period of the overpacks. Reduced micromorphic crystal plasticity model, which is similar to strain gradient models, is used in this investigation. Firstly, the model’s size dependent plasticity effects are evaluated. Secondly, different microstructural aggregates presenting overpack sections are analyzed. Grain size dependent hardening responses, i.e., Hall-Petch like behavior, can be achieved with the enhanced hardening associated with the micromorphic model at polycrystalline level. It was found that the nominally large grain size in the base material of the overpack shows lower strain hardening potential than the fine grained region of the welded microstructure with stronger strain gradient related hardening effects. Size dependent regularization of strain localization networks is indicated as a desired characteristics of the model. The findings can be utilized to provide an improved basis for modeling the viscoplastic deformation behavior of the studied copper alloy and assess the microstructural origins of any integrity concerns explicitly by way of full field modeling.
ARTICLE | doi:10.20944/preprints202104.0727.v1
Subject: Materials Science, Biomaterials Keywords: Copper alloy; friction stir alloying; macrostructure; material properties
Online: 27 April 2021 (14:25:31 CEST)
Friction stir alloying (FSA) of commercially pure Cu with Ni, Zn, and Mg is implemented in the current study. The successfully fabricated alloy structure has been scrutinized in terms of mechanical and micro-structural standpoints. Energy-dispersive X-ray spectroscopy revealed a uniform distribution of alloying elements and coalescence at the atomic level. The compositional and grain size heterogeneity is managed in the stir zone, which pave way for microstructural control using FSA. Thus, the present study carries significance for the development of novel materials whose fabrication requires temperature far below the melting point of base metals. Ultra-refinement of grains is found to accompany the alloying process, with ~ 440 nm being the smallest grain size. Maximum and average micro-hardness enhancement of 18.4 % and 6 % is observed for the fabricated alloy. Tensile properties have also been investigated and co-related with the micro-structural morphology. The shift towards grain bimodality has also been reported, which is a highly sought property in the present day, especially to overcome the strength-ductility trade-off.
COMMUNICATION | doi:10.20944/preprints202008.0701.v1
Subject: Chemistry, Chemical Engineering Keywords: carbon dioxide; molybdenum carbide; methanol; copper; alkali; dopant
Online: 31 August 2020 (05:03:06 CEST)
Mitigation of Anthropogenic CO2 emissions possess a major global challenge for modern societies. Herein catalytic solutions are meant to play a key role. Among the different catalysts for CO2 conversion Cu supported on molybdenum carbide is receiving increasing attention. Hence, in the present communication we show the activity, selectivity and stability of fresh-prepared -Mo2C catalysts and compare the results with those of Cu/Mo2C, Cs/Mo2C and Cu/Cs/Mo2C in CO2 hydrogenation reactions. The results showed that all the catalysts were active and the main reaction product was methanol. The results showed that copper-cesium and molybdenum effectively interact and that cesium promoted the formation of metallic Mo. While, the incorporation of copper is positive to improve the activity and selectivity to methanol, the presence of Mo0 phase was detrimental for the conversion and selectivity. Moreover, the catalysts promoted by cesium underwent redox surface transformations during the reaction that diminished their catalytic performance. The molybdenum phase in Cu/Mo2C changes during reaction leading to metallic molybdenum and tuning the catalytic activity.
REVIEW | doi:10.20944/preprints201809.0161.v1
Subject: Life Sciences, Biochemistry Keywords: embryonic type copper metabolism; milk ceruloplasmin; baby formula
Online: 10 September 2018 (09:43:22 CEST)
Copper, which can potentially be a highly toxic agent, is an essential nutrient due to its role as a co-factor for cuproenzymes and participation in signaling pathways. In mammals, the liver is a central organ that controls copper turnover throughout the body: copper absorption, distribution, and excretion. In ontogenesis, there are two types of copper metabolism: embryonic and adult, which maintain the balance of copper in each of these periods, respectively. In the liver cells, these types are characterized by specific expression patterns and activity levels of the genes encoding ceruloplasmin, which is the main extracellular ferroxidase and copper transporter and proteins mediating ceruloplasmin metalation. In newborns, the molecular-genetic mechanisms responsible for copper homeostasis and the ontogenetic switch from embryonic to adult copper metabolism are highly adapted to milk ceruloplasmin as a dietary source of copper. In the mammary gland cells, the level of ceruloplasmin gene expression and the alternative splicing of its pre-mRNA govern the amount of ceruloplasmin in milk, and thus, the amount of copper absorbed by the newborn is controlled. In the newborns, absorption, distribution, and accumulation copper are adapted to milk ceruloplasmin. In the newborns, which are not breast-fed at the early stages of postnatal development, the control for alimentary copper balance is absent. We tried to focus on the neonatal consequences of a violation of the balance of copper in the mother / newborn system. Although there is still much to be learned, the time to pay attention to this problem came because the neonatal misbalance of copper may provoke the development of copper related disorders for future life.
ARTICLE | doi:10.20944/preprints201806.0215.v1
Subject: Chemistry, Electrochemistry Keywords: Copper; Phosphoric acid; 3D Nanostructures; 1-dodecanethiol SAMs
Online: 13 June 2018 (15:33:35 CEST)
A novel and simple method to improve the corrosion resistance of copper by constructing a 3D 1-dodecanethiol self-assembled monolayers (SAMs) in 3.5% NaCl solution is reported in this study. Several drops of 1% H3PO4 solution are thinly and uniformly distributed on copper surface to form a 3D nanostructure constituted by Cu3(PO4)2 nanoflowers. The anticorrosion properties of 1-dodecanethiol SAMs on copper surface and on copper surface treated with H3PO4 solution were evaluated. Results demonstrated that 1-dodecanethiol SAMs on bare copper surface exhibit good protection capacity, whereas a copper surface pretreated with H3PO4 solution can substantially enhance the corrosion resistance of 1-dodecanethiol SAMs.
ARTICLE | doi:10.20944/preprints201803.0198.v1
Subject: Chemistry, Analytical Chemistry Keywords: copper detection; magnetic nanoparticle; rhodamine B derivative; removal
Online: 23 March 2018 (10:28:53 CET)
Pollution caused by copper is one of the key factors of environment contamination. As one of heavy metals, copper is hard to decompose in nature, the biological enrichment of which may lead to severe damage to health. Cu2+ detection, thus, possesses a bright application prospect both in environment protection and in human health. In this paper, a dual-functional fluorescence-magnetic composite nano-platform has been designed to sensitively detect, meanwhile capture and remove Cu2+ in the solution of water and ethanol (1:1, v/v). The core-shell structure nanoparticle synthesized by using Fe3O4 as core and SiO2 as shell, is covalently bonded with rhodamine derivatives on the silica layer to construct the nano-platform. The emission is increased upon the addition of Cu2+, showing fluorescence turn on effect for the detection, and the limit of detection which was as low as 1.68 nM. Meanwhile, Cu2+ ions are captured by the coordination with rhodamine derivatives, and can be removable with the help of magnetic field.
ARTICLE | doi:10.20944/preprints201803.0091.v1
Subject: Materials Science, General Materials Science Keywords: water purification, oligodynamic metal, moringa oleifera seed, copper
Online: 12 March 2018 (15:20:37 CET)
A simple, efficient and stand-alone method for purification of river water using moringa seed powder and copper is discussed. Coagulant property of the seed powder clears turbid raw water and the oligodynamic activity of copper completely destroys E.coli bacteria. Both raw and treated water samples were tested for contaminants to verify the efficacy of the system. Treated water has turbidity in the range 3 NTU - 5 NTU and non-detected (< 1 MPN/100 mL) E.coli count making it suitable for drinking. The technique is very cost effective and can be practiced anywhere using locally available materials. It does not require a power source or any technical assistance. Being a stand-alone system the technique exceptionally useful in providing drinking water as an immediate solution in disaster areas affected by cyclone or floods.
ARTICLE | doi:10.20944/preprints202211.0334.v1
Subject: Chemistry, General & Theoretical Chemistry Keywords: CO2 reduction; copper catalysts; metal doping; density functional calculations
Online: 17 November 2022 (10:00:37 CET)
The electrochemical CO2 reduction reaction can lead to high value-added molecules production while helping decrease anthropogenic CO2 emissions. Copper can reduce CO2 to more than thirty different hydrocarbons and oxygenates, but it lacks the required selectivity. We present a computational investigation of the role of nano-structuring and alloying in Cu-based catalysts on the activity and selectivity of CO2 reduction to one-carbon products: carbon monoxide, formic acid, formaldehyde, methanol, and methane. The adsorption, activation, and conversion of CO2 were computed on monometallic and bimetallic (decorated and core-shell) 55-atom Cu-based clusters. The dopant metals considered were Ag, Cd, Pd, Pt, and Zn, located at different coordination sites. The relative binding strength of the intermediates at different applied potentials were used to identify the optimal catalyst for the selective CO2 conversion to one carbon products. It was discovered that single atom doping with Cd and Zn is optimal for the CO2 to carbon monoxide conversion. The core-shell models with Ag, Pd, and Pt provided higher selectivity for formic acid and formaldehyde. The Cu-Pt and Cu-Pd showed lowest overpotential for methane formation.
ARTICLE | doi:10.20944/preprints202210.0113.v1
Subject: Chemistry, General & Theoretical Chemistry Keywords: coupling reactions; copper; transmetalation; DFT; Reaction Mechanism; cyclic voltammetry
Online: 10 October 2022 (03:14:04 CEST)
Controlling and understanding Cu-catalyzed homocoupling reaction is crucial to prompt the development of efficient Cu-catalyzed cross-coupling reactions. The presence of a coordinating base (hydroxide, methoxide) enables the B-to-Cu(II) transmetalation from aryl boronic acid to CuIICl2 in methanol, through formation of a mixed Cu-(μ-OH)-B intermediates. A second B-to-Cu transmetalation to form bis-aryl Cu(II) complexes is disfavored. Instead, organocopper(II) dimers undergo a coupled transmetalation-electron-transfer (TET) allowing the formation of a bis-organocopper(III) complexes readily promoting reductive elimination. Based on this mechanism some guidelines are suggested to control the undesired formation of homocoupling product in Cu-catalyzed cross-coupling reactions.
ARTICLE | doi:10.20944/preprints202210.0061.v1
Subject: Materials Science, Metallurgy Keywords: printed circuit boards; gold; copper; electrochemical leaching; alternating current
Online: 6 October 2022 (09:59:38 CEST)
Modern technologies for recycling electronic waste (e-waste) impose high economic efficiency and environmental safety requirements. Among existing technologies, hydrometallurgy is considered the most promising technology for e-waste recycling. Increasing attention to the chlorination method is associated with the complex recycling of low-grade ores containing noble metals and secondary polymetallic raw materials. In this paper, we propose a new scheme for leaching metals from computer printed circuits (PCBs) pre-crushed in a disintegrator: the processes of chlorine production and hydrochlorination are implemented in one reactor under the action of alternating current (AC) of industrial frequency (50 Hz). It was found that complete leaching of gold is achieved from fine fractions of raw materials containing 0.03% and 0.01% of the gold at an experiment duration of 2 hours, a current density of 0.66 A·cm-2, and a solid/liquid ratio of 8.6 g·L-1. Under the same conditions of the electrochemical leaching process from the fraction of raw material with a gold content of 0.08%, the degree of metal leaching is 80.5%. At the same time, with an increase in the copper content in the raw material from 1.40% to 6.13%, an increase in the degree of its leaching from 84.6% to 95.2%, respectively, is observed. These results will serve as a foundation for developing a complex technology for recovering valuable metals from PCBs.
ARTICLE | doi:10.20944/preprints202006.0001.v1
Subject: Medicine & Pharmacology, General Medical Research Keywords: Copper; transfusion-dependent thalassemia; zinc; oxidative stress; antioxidants; biomarkers
Online: 2 June 2020 (09:21:13 CEST)
Measurements of copper and zinc in transfusion-dependent thalassemia (TDT) show contradictory results.Aim of the study: To examine serum levels of these minerals in TDT in relation to iron overload indices and erythron variables. Methods: This study recruited 60 children with TDT and 30 healthy children aged 3-12 years old.Results: Zinc was significantly higher in TDT children than in control children, whilst copper and the copper to zinc ratio were significantly lowered in TDT. Serum zinc was significantly associated with the number of blood transfusions and iron overload variables (including serum iron and TS%) and negatively with erythron variables (including hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin). Serum copper was significantly and negatively associated with the same iron overload and erythron variables. The copper to zinc ratio was significantly correlated with iron, TS%, ferritin, hemoglobin, mean corpuscular volume, and mean corpuscular hemoglobin. Albumin levels were significantly higher in TDT children than in control children. Conclusion: Our results suggest that the increase in zinc in children with TDT may be explained by iron loading anemia and hemolysis and the consequent shedding of high amounts of intracellular zinc into the plasma. Increased albumin levels and treatment with Desferral may further contribute towards higher zinc levels in TDT. We suggest that the elevations in zinc in TDT are a compensatory mechanism protecting against infection, inflammation, and oxidative stress. Previous proposals for prophylactic use of zinc supplements in TDT may not be warranted.
Subject: Materials Science, General Materials Science Keywords: glycine-nitrate process; copper oxide nanopowders; heterogeneous catalysis; NP9EO
Online: 10 December 2019 (15:20:25 CET)
Copper-based nanoparticles were synthesized using the glycine–nitrate process (GNP) by using copper nitrate trihydrate [Cu(NO3)2‧3H2O] as the main starting material and glycine [C2H5NO2] as the complexing and incendiary agent. The as-prepared powders were characterized through X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis, X-ray photoelectron spectroscopy, and scanning electron microscopy. Using Cu(NO3)2.3H2O as the oxidizer (N) and glycine as fuel (G), we obtained CuO, mixed-valence copper oxides (CuO + Cu2O, G/N = 0.3–0.5), and metallic Cu (G/N = 0.7). The XRD and BET results indicated that increasing the glycine concentration (G/N = 0.7) and reducing particle surface area increased the yield of metallic Cu. The effects of varying reaction parameters such as catalyst activity, catalyst dose, and H2O2 concentration on nonylphenol-9-polyethoxylate (NP9EO) degradation were assessed. With a copper‐based catalyst in a heterogeneous system, the NP9EO and total organic carbon removal efficiencies were 83.1% and 70.6%, respectively, under optimum operating conditions (pH, 6.0; catalyst dose, 0.3 g/L; H2O2 concentration, 0.05 mM). The results suggested that removal efficiency increased with an increase in H2O2 concentration but decreased when the H2O2 concentration exceeded 0.0.5 mM. Furthermore, the trend of photocatalytic activity was as follows: G/N = 0.5 > G/N = 0.7 > G/N = 0.3. The G/N = 0.5 catalysts showed the highest photocatalytic activity and resulted in 94.6% NP9EO degradation in 600 min.
ARTICLE | doi:10.3390/sci1020055
Online: 18 September 2019 (00:00:00 CEST)
Sickle cell disease (SCD) is an inherited disorder of major health challenge in Nigeria. Micronutrients deficiencies often associated with the disorder may cause inflammation and abnormal metabolisms in the body. The copper-to-zinc ratio is a more important assessment than the concentrations of either of the metals in clinical practice. This study seeks to evaluate serum levels of c-reactive protein (CRP), copper, zinc and copper-to-zinc ratio and to correlate copper-to-zinc ratio with CRP in adult subjects with SCD. Serum copper, zinc, CRP and plasma fibrinogen were assayed in 100 confirmed SCD patients in steady clinical state and 100 age and sex matched subjects with normal haemoglobin. Serum copper and zinc were assayed by colorimetric method using reagents supplied by Centronic, Germany while CRP and fibrinogen were assayed using reagents supplied by Sigma (St. Louis, MO, USA) and Anogen (Ontario, Canada), respectively. The copper to zinc ratio was calculated from serum levels of copper and zinc. The measured parameters were compared between the groups using Students t-test and Pearson correlation coefficient was used to relate CRP with the other parameters. Serum copper, CRP, fibrinogen and copper-to-zinc ratio were significantly higher (p < 0.001) while zinc level was lower in SCD patients than controls. Serum CRP concentration correlated with copper (r = 0.10; p < 0.02), zinc (r = −0.199; p < 0.05) and Copper-to-zinc ratio (r = 0.312; p < 0.002) but the correlation between CRP and fibrinogen was not significant. Inflammatory condition may modulate copper and zinc homeostasis and copper-to-zinc ratio may be used as marker of nutritional deficiency and inflammation in SCD patients.
ARTICLE | doi:10.20944/preprints201810.0045.v1
Subject: Life Sciences, Other Keywords: Copper nanoparticles, nano-fertilizer, soil, nitrification, nitrification kinetics, toxicity
Online: 3 October 2018 (12:46:58 CEST)
The potential agricultural use of metal nanoparticles (NPs) for slow-release micronutrient fertilizers is beginning to be investigated by both industry and regulatory agencies. However, the impact of such NPs on soil biogeochemical cycles is not clearly understood. In this study, impacts of a commercially-available copper NPs on the soil nitrification kinetics was investigated via batch experiments. The X-ray absorption near edge structure spectroscopy analysis showed that the NPs readily oxidized to Cu(II) and strongly retained in soils with minimum dissolution (<1% of total mass). The Cu2+ (aq) at 1mg/L showed the beneficial effect on the nitrification, an increase in the rate of nitrification kinetics (Vmax). However Vmax was negatively impacted by ionic Cu at 10-100mg/L and CuNP at 1-100 mg/L. The trace metal toxicity of soil nitrifiers seems to be critical in the soil nitrification processes. Among CuNPs, the suppressed nitrification kinetics was concentration dependent at >10mg/L. The reaction products of surface oxidation such as the release of ionic Cu seem to play an important role in suppressing the nitrification process. Considering the potential use of copper NPs as a slow-release micronutrient fertilizer, further studies are needed in heterogeneous soil systems.
ARTICLE | doi:10.20944/preprints201807.0112.v1
Subject: Materials Science, Surfaces, Coatings & Films Keywords: membrane distillation; polyvinylidene fluoride; copper oxide nanoparticles; membrane morphology
Online: 6 July 2018 (09:03:09 CEST)
Membrane distillation techniques appear as one of the most promise alternative to guarantee the availability of potable water in time of scarce of this essential resource. For membrane preparation, polyvinylidene fluoride (PVDF) is preferred due to the easier synthesis procedures with respect to other fluorine based polymers. In this work, copper oxide nanoparticles (CuONPs) at different weight percent (wt.%), embedded in PVDF membranes supported on non-woven polyester fabric (NWPET) were prepared by the phase-inversion method, and characterized by spectroscopy (ATR-FTIR, Raman) and electron microscopy techniques (SEM). The PVDF deposited onto the NWPET was highly composed by its polar -phase (F()= 53 %) which was determined from the ATR-FTIR spectrum. The F() value was kept constant, in the whole range of CuONPs studied (2-10 wt.%) as was determined from the ATR-FTIR spectrum. The absence of signals corresponding to CuONPs in the ATR-FTIR spectra and the appearance of peaks at 297, 360 and 630 cm-1 in the Raman spectra of the membranes suggested that the CuONPs are preferably located in the inner of the membrane but not on its surface. The membrane morphologies were characterized by SEM. From the obtained SEM micrographs, a decrease and increase in the amount of micropores and nanopores, respectively, near to the surface and intercalated in the finger-like layer were observed. As result of the CuONPs addition, the nanopores in the sponge-like layer decrease in size. The values of water contact angle (WCA) measurements showed a trend to decrease from 94° to 80° upon the addition of CuONPs (2-10 wt.%) indicating a diminish in the hydrophobicity degree of the membranes. Apparently, the increase in the amount of nanopores near to the surface decreased the membrane roughness becoming less hydrophobic.
ARTICLE | doi:10.20944/preprints201711.0161.v1
Subject: Chemistry, Electrochemistry Keywords: copper; carbonous nanomaterial; composite coating; heat-dissipation material; nanodiamond
Online: 24 November 2017 (16:18:35 CET)
Carbonous nanomaterials are promising additives for composite coatings for heat-dissipation materials because of their excellent thermal conductivity. Here, copper/carbonous nanomaterial composite coatings were prepared using nanodiamond (ND) as the carbonous nanomaterial. The copper/ND composite coatings were electrically deposited onto copper substrates from a continuously stirred copper sulfate coating bath containing NDs. NDs were dispersed by ultrasonic treatment, and the initial bath pH was adjusted by adding sodium hydroxide solution or sulfuric acid solution before electrodeposition. The effects of various coating conditions—the initial ND concentration, initial bath pH, stirring speed, electrical current density, and the amount of electricity—on the ND content of the coatings were investigated. Furthermore, the surface of the NDs was modified by hydrothermal treatment to improve ND incorporation. A higher initial ND concentration and a higher stirring speed increased the ND content of the coatings, whereas a higher initial bath pH and a greater amount of electricity decreased it. The electrical current density showed a minimum ND content at approximately 5 A/dm2. Hydrothermal treatment, which introduced carboxyl groups onto the ND surface, improved the ND content of the coatings. A copper/ND composite coating with a maximum of 3.85 mass% ND was obtained.
ARTICLE | doi:10.20944/preprints201703.0231.v1
Subject: Materials Science, General Materials Science Keywords: copper resources; demand forecasting; system dynamics model; sustainability development
Online: 31 March 2017 (10:50:56 CEST)
Copper demand for a country's copper industry has a greater pull effect. China's copper consumption in 2015 has accounted for 50% of the world. The scientific forecast of China's copper demands trend is also an important basis for analyzing its future environmental impact. This paper assumes that China's economy will be developing high, medium and low scenarios, and forecasts economic and social indicators such as total GDP, population and per capita GDP in China from 2016 to 2030. Then, predicted the demand of copper resources in China from 2016 to 2030 by the combination of system dynamics model, vector autoregressive moving average model and inverted U-type empirical model. The results show that: (1) in 2020, 2025 and 2030, China's refined copper demand will be 13 Mt, 15 Mt and 15.5 Mt. (2) China's copper demand growth slowed down significantly from 2016-2030. (3) 2025-2030, China's copper resource demand is stable, into the platform of demand growth, the highest peak value in 2027 will be 15.5 Mt. (4) 2030 years later, China's copper resource demand will enter a slow decline.
ARTICLE | doi:10.20944/preprints202301.0002.v1
Subject: Materials Science, Other Keywords: Graphene; copper oxide nanoparticles; nanohybrid; trichloroethylene; Rhodamine B; water remediation.
Online: 3 January 2023 (04:30:54 CET)
In this work Cu2O nanoparticles (NPs) were created in-situ on graphene functionalized with Thermomyces lanuginosus lipase (G@TLL) where site-oriented supported TLL acted as template and binder in the presence of copper salt by tailorable synthesis under mild conditions, producing a heterogeneous catalyst. Cu2O NPs was confirmed by XRD and XPS. The TEM microscopy showed that the nanoparticles were homogeneously distributed over the G@TLL surface with sizes of 53 nm and 165nm. This G@TLL-Cu2O hybrid was successfully used in the degradation of toxic organic compounds such as trichloroethylene (TCE) and Rhodamine B (RhB). In the case of TCE, the hybrid presented a high catalytic capacity, degrading 60 ppm of product in 60 min in aqueous solution and room temperature without the formation of other toxic subproducts. In addition, a TOF value of 7.5 times higher than the unsupported counterpart (TLL-Cu2O) was obtained, demonstrating the improved catalytic efficiency of the system in the solid-phase. The hybrid also presented an excellent catalytic performance for the degradation of Rhodamine B (RhB) obtaining a complete degradation (48ppm) in 50 min in in aqueous solution and room temperature and with the presence of a green oxidant as H2O2.
ARTICLE | doi:10.20944/preprints202112.0359.v1
Subject: Materials Science, Surfaces, Coatings & Films Keywords: 6H-SiC; the first principles; copper matrix composites; electronic properties
Online: 22 December 2021 (12:06:53 CET)
The interfacial mechanics and electrical properties of the SiC reinforced copper matrix composites were studied via the first principles method. The work of adhesion (Wad) and the interfacial energies were calculated to evaluate the stabilities of the SiC/Cu interfacial models. The carbon terminated (CT)-SiC/Cu interfaces were predicted more stable than those of the silicon terminated (ST)-SiC/Cu from the results of the Wad and interfacial energies. The interfacial electron properties of SiC/Cu were studied via the charge density distribution, charge density difference, electron localized functions and partial density of the state. The covalent C-Cu bonds were formed based on the results of the electron properties, which further explained the fact that the interfaces of the CT-SiC/Cu are stable than those of the ST-SiC/Cu. The interfacial mechanics of the SiC/Cu were investigated via the interfacial fracture toughness and ultimate tensile stress, and the results indicate that both CT- and ST-SiC/Cu interfaces are hard to fracture. The ultimate tensile stress of the CT-SiC/Cu is nearly 23GPa, which is smaller than those of the ST-SiC/Cu of 25 GPa. The strains corresponding to their ultimate tensile stresses of the CT- and ST-SiC/Cu are about 0.28 and 0.26, respectively. The higher strains of CT-SiC/Cu indicate their stronger plastic properties on the interfaces of the composites.
ARTICLE | doi:10.20944/preprints202106.0582.v1
Subject: Chemistry, Analytical Chemistry Keywords: polymerization kinetics; free radical, cationic polymerization, copper complex, photoredox catalyst.
Online: 23 June 2021 (12:37:02 CEST)
. This article presents, for the first time, the kinetics and the general conversion features of a 3-component system (A/B/N), based on proposed mechanism of Mau et al, for both free radical polymerization (FRP) of acrylates and the free radical promoted cationic polymerization (CP) of epoxides using various new copper complex (G2) as the initiator. Higher FRP and CP conversion can be achieved by co-additive of [B] and N, via the dual function of (i) regeneration [A], and (ii) generation of extra radicals. The FRP and CP conversion efficacy (CE) are proportional to the nonlinear power of bI[A][B], where b and I are the effective absorption coefficient and the light intensity, respectively. In the interpenetrated polymer network (IPN) capable of initiating both FRP and CP in a blend of TMPTA and EPOX, (as the monomer for FRP and CP, respectively), the synergic effects due to CP include:: (i) CP can increase viscosity limiting the diffusional oxygen replenishment, such that oxygen inhibition effects are reduced; (ii) the cationic monomer also acts as a diluting agent for the IPN network , and (iii) the exothermic property of the CP. Many new findings are explored via our analytical formuals include: (i) the CE of FRP is about twice of the CE of CP, due to the extra radicals involved in FRP; (ii) the catalytic cycle enhancing the efficacy is mainly due to the regenaration of the initiator, and (iii) the nonlinear dependence of light intensity of the CE (in both FRP and CP). For the first time, the catalytic cycle, synergic effects, and the oxygen inhibition are theoretically confirmed to support the experimental hypothesis. The measured results of Mau et al are well analyzed and matching the predicted features of our modeling. .
Subject: Life Sciences, Biochemistry Keywords: copper; amyloid-β peptides; Alzheimer’s disease; oxidative stress; dopamine; neurodegeneration.
Online: 26 April 2021 (13:23:52 CEST)
The redox chemistry of copper(II) is strongly modulated by the coordination to amyloid-β peptides and by the stability of the resulting complexes. Amino terminal copper and nickel binding motifs (ATCUN) identified in truncated Aβ sequences starting with Phe4 show very high affinity for copper(II) ions. Herein, we study the oxidase activity of [Cu-Aβ4-x] and [Cu-Aβ1-x] complexes toward dopamine and other catechols. The results show that the CuII-ATCUN site is not redox-inert, the reduction of the metal is induced by coordination of catechol to the metal and occurs through an inner sphere reaction. The generation of a ternary [CuII-Aβ-catechol] species determines the efficiency of the oxidation, although the reaction rate is ruled by re-oxidation of the CuI complex. In addition to the N-terminal coordination site, the two vicinal histidines, His13 and His14, provide a second Cu-binding motif. Catechol oxidation studies together with structural insight from the mixed dinuclear complexes Ni/Cu-Aβ4-x reveal that the His-tandem is able to bind CuII ions independently of the ATCUN site, but the N-terminal metal complexation reduces the conformational mobility of the peptide chain, preventing the binding and oxidative reactivity toward catechol of CuII bound to the secondary site.
ARTICLE | doi:10.20944/preprints202102.0113.v1
Subject: Materials Science, Surfaces, Coatings & Films Keywords: ion beam; copper oxide; chromatic change; photoemission spectrum; beam viewer
Online: 3 February 2021 (10:38:45 CET)
The color of a thin copper oxide layer formed on a copper plate was transformed from reddish-brown into blue-purple by irradiation with 5 keV Ar+ ions to a fluence as low as 1 1015 Ar+ cm–2. In the unirradiated copper oxide layer, the copper valence state of Cu2+ as well as Cu+ and/or Cu0 was included as indicated by the presence of a shake-up satellite line in a photoemission spectrum. While for the irradiated one, the satellite line decreased in intensity, indicating that irradiation resulted in the reduction from Cu2+ to Cu+ and/or Cu0. Furthermore, nuclear reaction analysis using a 16O(d, p)17O reaction with 0.85 MeV deuterons revealed a significant loss of oxygen (51015 O atoms cm–2) in the irradiated layer. Thus, the chromatic change observed in the present work originated in the irradiation-induced reduction of a copper oxide.
Subject: Chemistry, Analytical Chemistry Keywords: Carbon dioxide chemistry; Copper catalysis; Synthetic methods; Multicomponent reaction; Cyclization
Online: 18 January 2021 (12:40:17 CET)
With the aim of profitable conversion of carbon dioxide (CO2) in an efficient, economical and sustainable manner, we developed a CuBr/ionic liquid (1-butyl-3-methylimidazolium acetate) catalytic system which could efficiently catalyze the three-component reactions of propargylic alcohols, 2-aminoethanols, and CO2 to produce 2-oxazolidinones and α-hydroxy ketones. Remarkably, this catalytic system employed lower metal loading (0.0125-0.5 mol%) but exhibited the highest turnover number (2960) ever reported, demonstrating its excellent activity and sustainability. Moreover, our catalytic system could efficiently work under 1 atm of CO2 pressure and recycle among the metal-catalyzed systems.
ARTICLE | doi:10.20944/preprints201911.0305.v1
Subject: Life Sciences, Microbiology Keywords: Moringa oleifera; copper nanoparticles; polyphenolics; anti-bacterial; anti-fungal; antioxidant
Online: 26 November 2019 (03:45:52 CET)
The synthesis of metal nanoparticles using plant extracts is a very promising method in green synthesis. The medicinal value of Moringa oleifera leaves and the anti-microbial activity of metallic copper were combined in the present study to synthesize copper nanoparticles having a desirable added-value inorganic material. The use of a hydroalcoholic extract of M. oleifera leaves for the green synthesis of copper nanoparticles is an attractive method as it leads to the production of harmless chemicals and reduces waste. The total phenolic content in the M. oleifera leaves extract was 23.0 ± 0.3 mg gallic acid equivalent/g of dried M. oleifera leaves powder. The M. oleifera leaves extract was treated with a copper sulphate solution. A color change from brown to black indicates the formation of copper nanoparticles. Characterization of the synthesized copper nanoparticles was performed using UV-Vis spectrophotometer, FT-IR spectrometer, TEM, SEM, and XRD. The synthesized copper nanoparticles have an amorphous nature and particle size of 35.8-49.2 nm. We demonstrate that the M. oleifera leaves extract and the synthesized copper nanoparticles display considerable antioxidant activity. Moreover, the M. oleifera leaves extract and the synthesized copper nanoparticles exert potent anti-bacterial activity against Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecalis (MIC values for the extract: 500, 250, 250, and 250 μg/mL; MIC values for the cooper nanoparticles: 500, 500, 500, and 250 μg/mL, respectively). Similarly, the M. oleifera leaves extract and the synthesized copper nanoparticles exert relatively more potent anti-fungal activity against Aspergillus niger, Aspergillus flavus, Candida albicans, and Candida glabrata (MIC values for the extract: 62.5, 62.5, 125, and 250 μg/mL; MIC values for the cooper nanoparticles: 125, 125, 62.5, and 31.2 μg/mL, respectively). Our study reveals that the green synthesis of copper nanoparticles using a hydroalcoholic extract of M. oleifera leaves was successful. In addition, the synthesized copper nanoparticles can be potentially employed in the treatment of various microbial infections due to their potent antioxidant, anti-bacterial, and anti-fungal activities.
ARTICLE | doi:10.20944/preprints201812.0258.v1
Subject: Materials Science, Surfaces, Coatings & Films Keywords: copper; polymer coatings; polyvinyl alcohol; silver nanoparticles; deep learning; CNN
Online: 21 December 2018 (07:51:06 CET)
In order to design effective protective coatings against corrosion, the polyvinyl alcohol (PVA) as compound and composite with silver nanoparticles (nAg/PVA) were electrodeposited on copper surface employing electrochemical techniques such as linear potentiometry and cyclic voltammetry. A new paradigm was used to distinguish the features of coatings, i.e., a Deep Convolutional Neural Network (CNN) was implemented to automatically and hierarchically extract the discriminative characteristics from the information given by optical microscopy images. The main arguments that invoke a CNN implementation in the surface science of materials are the following: artificial intelligence techniques can be successfully applied to learn differences between surface coatings; based on their popularity for image processing, CNN can model images related to the problem of coatings; deep learning is able to extract the features that are distinguishable between material surfaces. To provide an overview of the copper surface, CNN was applied on microscope slides (CNN@microscopy) and inherently learnt distinctive characteristics for each class of surface morphology. The material surface morphology controlled by CNN without the interference of the human factor was successfully conducted, in our study, to extract the similarities/differences between unprotected and protected surfaces to establish the PVA and nAg/PVA performance to retard the copper corrosion.
ARTICLE | doi:10.20944/preprints201812.0020.v1
Subject: Chemistry, Inorganic & Nuclear Chemistry Keywords: coordination compounds; coordination polymers; copper; thiocyanate; crystal Structure; DFT calculations
Online: 3 December 2018 (10:02:16 CET)
A series of Cu(II)-thiocyanato complexes derived from sterically hindered N-donors diamines were synthesized and characterized: catena-[Cu(Me3en)(μ-NCS)(NCS)] (1), catena-[Cu(NEt2Meen)(μ-NCS)(NCS)] (2), catena-[Cu(N,N,2,2-Me4pn)(μ-NCS)(NCS)] (3), the dimeric: [Cu2(N,N′-isp2en)2(μ-NCS)2(NCS)2] (4) and the monomeric complex [Cu(N,N′-t-Bu2en)(NCS)2] (5), where Me3en = N,N,N′-Trimethylethylenediamine, NEt2Meen = N,N-diethyl-N′-methylethylenediamine, N,N,2,2-Me4pn = N,N,2,2-tetramethylpropylenediamine, N,N′-isp2en = N,N′-diisopropylethylenediamine and N,N′-t-Bu2en = N,N′-di(tert-butyl)ethylenediamine. The complexes were characterized by elemental microanalyse, IR and UV-Vis spectroscopy and single crystal X-ray crystallography. Density Functional Theory was used to evaluate the role of steric effects in compounds 4 and 5 and how this may affect the adaption of a specific geometry, NCS-bonding mode and the dimensionality of the resulting complex.
ARTICLE | doi:10.20944/preprints201811.0209.v1
Subject: Materials Science, Metallurgy Keywords: blister copper, flash smelting slag, citric acid, lead recovery, leaching
Online: 8 November 2018 (11:10:10 CET)
Direct-to-blister copper flash smelting slag contains up to 14% of copper and 2-4% of lead. Considering this fact, this material is subjected to the high-temperature reduction process. After this, converting process is performed on the Cu-Pb-Fe alloy being the product of decopperization process in electric furnace. An alternative to the presently used processing of flash smelting slag would be its hydrometallurgical treatment and selective recovery of Pb and Cu. This paper presents the results of laboratory tests on flash smelting slag leaching with citric acid solutions. The experiments performed allowed to determine the process parameters at which the Pb concentration in the post-leaching sediment reached the value of 0.41-0.6% while the Pb content in flash smelting slag was 3.05%. Analogous values for copper were 11.5-11.8% (after leaching) and 12.44% (before). Material after leaching in citric acid solutions can be processed, in the second step, using sulfuric acid solutions, and it could lead to the recovery of almost all copper contained in it.
ARTICLE | doi:10.20944/preprints201806.0167.v1
Subject: Materials Science, Surfaces, Coatings & Films Keywords: surface removal; nanoscale process; copper thin film; ultrathin water film
Online: 12 June 2018 (06:11:36 CEST)
The surface planarity and asperity removal behaviors of atomic scale under the ultrathin water environment was studied for the nanoscale process by molecular dynamics simulation. The monolayer atomic removal was achieved under the noncontact and monoatomic layer contact conditions with different water film thickness, and the newly formed surface is relatively smooth and no deformed layer and plastic defects exist. The nanoscale processing is governed by the interatomic adhering action during which the water film transmits the loading forces to Cu surface and thereby result in the migration and removal of surface atoms. With scratching depth ≥ 0.5 nm, the abrasive particle squeezed out the water film from scratching region and scratched Cu surface directly, leading to the surface quality deterioration mainly governed by the plowing action. This study brings the goals of “0 nm planarity, 0 residual defects and 0 polishing pressure” closer to us in the nanoscale process for the development of ultra-precision manufacture technology.
REVIEW | doi:10.20944/preprints202206.0253.v1
Subject: Life Sciences, Biophysics Keywords: Bioinorganic chemistry; metal-binding; structural biology; zinc; iron; copper; transition metals
Online: 17 June 2022 (09:30:07 CEST)
All living organisms require some metal ions for their energy production as well as metabolic and biosynthetic processes. Within cells, metal ions are involved in the formation of adducts interact with metabolites and macromolecules (proteins and nucleic acids). The proteins that require binding to one or more metal ions to be able to carry out their physiological function are called metalloproteins. About one third of all protein structures in the Protein Data Bank involve metalloproteins. Over the past few years there has been a tremendous progress in the number of computational tools and techniques making use of 3D structural information to support the investigation of metalloproteins. This trend has been boosted also by the successful applications of neural networks and deep learning approaches in molecular and structural biology at large. In this review, we discuss recent advances in the development and availability of resources dealing with metalloproteins from a structure-based perspective. We start by addressing tools for the prediction of metal-binding sites (MBSs) using structural information on apo-proteins. Then, we provide an overview of methods for and lessons learned from the structural comparison of MBSs in a fold-independent manner. We then move to describing databases of metalloprotein/MBS structures. Finally, we summarize recent DL applications enhancing the functional interpretation of metalloprotein structures.
Subject: Chemistry, Analytical Chemistry Keywords: polymerization kinetics; photoinitiator; free radical, cationic polymerization, copper complex, photoredox catalyst.
Online: 25 May 2021 (09:50:35 CEST)
This article presents, for the first time, the kinetics and the general conversion features of a 3-initiator system (A/B/N), based on proposed mechanism of Mokbel et al, for both free radical polymerization (FRP) of acrylates and the free radical promoted cationic polymerization (CP) of epoxides using copper complex as the initiator. Higher FRP and CP conversion can be achieved by co-initiators concentration [B] and [N], via the dual function of (i) regeneration [A], and (ii) generation of extra radicals S' and S. The FRP and CP conversion is proportional to, respectively, the nonlinear and linear power of bI[A][B], where b and I are the absorption coefficient and the light intensity, respectively. System in air has lower conversion than in laminate due to the oxygen inhibition effects. For thick samples (with thickness z), there is an optimal concentration [A*] which is inverse proportional (bzI), in contrast with very thin sample, in which the conversion is an increasing function of [A] and [B]. The unique feature of dark polymerization in CP conversion enables the polymerization to continue in living mode, in contrasts with that of the radical-mediated pathway in most conventional FRP. The measured results of Mokbel et al are well analyzed and matching the predicted features of our modeling.
Subject: Engineering, Civil Engineering Keywords: concrete performance; concrete durability; eipi method; copper slag waste; natural radioactivity
Online: 11 October 2019 (03:42:37 CEST)
The aim of the research was a comprehensive evaluation of concrete using the EIPI method. In the evaluation the compressive strength of concrete and its durability properties represented by sorptivity and air permeability were taken into account. Since copper slag waste with increased natural radioactivity was used in the assessed concrete, additional evaluation was carried out taking into account the influence of natural radioactivity within the performance index. Also the reference concrete, which was made without the use of copper slag waste, was evaluated for comparative purposes. In order to make the evaluation as comprehensive as possible, the concrete made with the use of three types of cement was subjected to the assessment: CEM I, CEM II and CEM III. The results show that in both approaches the best result was achieved by concrete with CEM III cement. If natural radioactivity is not taken into account in the evaluation, the best result is obtained by concrete made with copper slag waste, and if radioactivity is considered, the best result is obtained with concrete without addition of the waste. It follows from the above that although natural radioactivity has a significant impact on the EIPI evaluation result, the decisive factor is still the type of cement.
ARTICLE | doi:10.20944/preprints201908.0124.v1
Subject: Chemistry, Medicinal Chemistry Keywords: plasmonics; nanomedicine; theranostics; copper; VEGF; glioblastoma; differentiated neuroblastoma; peptidomimetics; qPCR; actin.
Online: 11 August 2019 (07:13:00 CEST)
Angiogenin (ANG), an endogenous protein that plays a key role in cell growth and survival, has been scrutinised here as promising nanomedicine tool for the modulation of pro-/ anti-angiogenic processes in brain cancer therapy. Specifically, peptide fragments from the putative cell membrane binding domain (residues 60-68) of the protein were used in this study to obtain peptide-functionalised spherical gold nanoparticles (AuNPs) of about 10 nm and 30 nm in optical and hydrodynamic size, respectively. Different hybrid biointerfaces were fabricated by peptide physical adsorption (Ang60-68) or chemisorption (the cysteine analogous Ang60-68Cys) at the metal nanoparticle surface, and the cellular assays were performed in the comparison with ANG-functionalised AuNPs. Cellular treatments were performed both in basal and in copper-supplemented cell culture medium, to scrutinise the synergic effect of the metal, which is another known angiogenic factor. Two brain cell lines were investigated in parallel, namely tumour glioblastoma (A172) and neuron-like differentiated neuroblastoma (d-SH-SY5Y). Results on cell viability/proliferation, cytoskeleton actin, angiogenin translocation and VEGF release pointed to the promising potentialities of the developed systems as anti-angiogenic tunable nanoplaftforms in cancer cells treatment.
ARTICLE | doi:10.20944/preprints201709.0118.v1
Subject: Materials Science, General Materials Science Keywords: copper mine tailings; mechanical activation; thermal activation; alkaline roasting; alkali leaching
Online: 25 September 2017 (08:41:24 CEST)
Copper mine tailings are the residual products after the purification of precious copper from copper ores, and their storage can create numerous environmental problems. Many researchers have used copper mine tailings for preparation of geopolymer. This paper studies the enhancement of the cementitious activity of copper mine tailings in geopolymer system. First, copper mine tailings are activated through a mechanical grinding activation. Afterward, the mechanically activated copper mine tailings are further processed through thermal activation and alkaline roasting activating. The cementitious activity index of copper mine tailings is characterized through the degree of concentration of alkali leaching silicon and aluminum. It was observed that the Si and Al alkali leaching concentration of mechanical activated tailings was increased by 26.03% and 93.33%, respectively. The concentration of Si and Al was increased by 54.19% and 119.92%, respectively. For alkaline roasting activating, roasting time, temperature and (C/N ratio) were evaluated through the orthogonal test, and the best condition was activation for 120 min at 600℃ with C/N ratio is 5:1. In this study, the SEM, XRD and IR analysis show that mechanically activation, thermal activation and alkaline roasting activating can improve the cementitious activity index of copper mine tailings.
REVIEW | doi:10.20944/preprints202108.0088.v1
Subject: Life Sciences, Other Keywords: Minerals, Trace elements, Fish, Copper, Iron, Selenium, Manganese, Zinc, Calcium, Phosphous, Magnesium
Online: 3 August 2021 (14:57:19 CEST)
Aquatic animals have unique physiological mechanisms to absorb and retain minerals from their diets and water. Research and development in the area of mineral nutrition of farmed fish and crustaceans have been relatively slow and major gaps exist in the knowledge of trace element requirements, physiological functions and bioavailability from feed ingredients. Quantitative dietary requirements have been reported for three macroelements (calcium, phosphorus and magnesium) and six trace minerals (zinc, iron, copper, manganese, iodine and selenium) for selected fish species. Mineral deficiency signs in fish include reduced bone mineralization, anorexia, lens cataracts (zinc), skeletal deformities (phosphorus, magnesium, zinc), fin erosion (copper, zinc), nephrocalcinosis (magnesium deficiency, selenium toxicity), thyroid hyperplasia (iodine), muscular dystrophy (selenium) and hypochromic microcytic anaemia (iron). An excessive intake of minerals from either diet or gill uptake causes toxicity and therefore a fine balance between mineral deficiency and toxicity is vital for aquatic organisms to maintain their homeostasis either through increased absorption or excretion. Release of minerals from uneaten or undigested feed and from urinary excretion can cause eutrophication of natural waters, which requires additional consideration in feed formulation. The current knowledge in mineral nutrition of fish is briefly reviewed.
ARTICLE | doi:10.20944/preprints202106.0424.v1
Subject: Chemistry, Analytical Chemistry Keywords: polymerization kinetics; photoinitiator; free radical polymerization; copper complex; photoredox catalyst; nanogold particles
Online: 16 June 2021 (08:37:27 CEST)
. This article presents, for the first time, the kinetics and the general features of a photopolymerization system (under visible light) G1/ Iodonium/ TEA/gold chloride (or A/B/N/G), having initial concentrations of A0, B0, N0 and G0, based on the proposed mechanism of Tar et al. Analytic formulas are developed to explore the new features including: (i) both FRP efficacy and the production of nanogold (NG) are proportional to the relative concentration ratios of (A0+B0+N0)/G0, which may be optimized for maximum efficacy; (ii) the two competing procedure of NG production and efficacy of free radical photopolymerization (FRP) can be tailored for optimal system with nanogold in the polymer matrix;(ii) the FRP efficacy is contributed by 3 components: the coupling of the excited state of copper complex (T) with the radicals (R and S) produced by the iodonium and the amine; (iii) the production of NG is contributed by 2 components: the coupling of T and radical (S) with gold ion; (iv) NG production has a transient state value which is an increasing function of light intensity and the combined concentration ratio [(A0/G0)+(N0/(K'M0). whereas it has a steady-state independent to the light intensity.
Subject: Materials Science, Biomaterials Keywords: ZnO thin films; SILAR; IPA dispersant; copper oxide; post-annealing; CuxO/ZnO
Online: 15 December 2020 (10:25:15 CET)
Here we report the effect of substrate, sonication process, and post-annealing on the structural, morphological, and optical properties of ZnO thin films grown in the presence of isopropyl alcohol (IPA) at temperature 30 – 65 ℃ by successive ionic layer adsorption and reaction (SILAR) method on both soda lime glass (SLG) and Cu foil. The X-ray diffraction (XRD) patterns confirmed the preferential growth thin films along (002) and (101) plane of wurtzite ZnO structure while grown on SLG and Cu foil substrate respectively. Both XRD and Raman spectra confirmed the ZnO and Cu-oxide phases of the deposited films. Scanning electron microscope (SEM) image of the deposited films shows compact and uniformly distributed grains for samples grown without sonication while using IPA at temperature 50 and 65 ℃. The post-annealing treatment improves the crystallinity of the films, further evident by XRD and transmission and reflection results. The estimated optical bandgaps are in the range of 3.37-3.48 eV for as-grown samples. Results revealed that high-quality ZnO thin films could be grown without sonication using IPA dispersant at 50 ℃, which is much lower than the reported results using the SILAR method. This study suggests that in the presence of IPA, the SLG substrate results in better c-axis oriented ZnO thin films than that of DI water, ethylene glycol, propylene glycol at the optimum temperature of 50 ℃. Air-annealing of the samples grown on Cu foils induced the formation of CuxO/ZnO junctions which is evident from the characteristic I-V curve including the structural and optical data.
ARTICLE | doi:10.20944/preprints202009.0642.v1
Subject: Life Sciences, Biochemistry Keywords: copper; mercury; cadmium; oxidative stress; protein carbonylation; translation factors; oxidative stress biomarkers
Online: 26 September 2020 (14:46:39 CEST)
The impact of metals bioaccumulation on marine organisms is under investigation. This study was designed to determine the association of oxidative stress in mussels Mytilus galloprovincialis induced by seawater enriched with trace metals with protein synthesis. Mussels were exposed to 40 μg/L Cu, 30 μg/L Hg, or 100 μg/L Cd for 5 and 15 days, and the pollution effect was evaluated by measuring established oxidative biomarkers. The results showed damage on the protein synthesis machine integrity and specifically, on translation factors and ribosomal proteins expression and modifications. Exposure of mussels to all metals caused oxidative damage that was milder in the cases of Cu and Hg, and more pronounced for Cd. However, after prolonged exposure of mussels to Cd (15 days), the effects receded. These changes that perturb protein biosynthesis can serve as a great tool for elucidating the mechanisms of toxicity and could be integrated in biomonitoring programs.
ARTICLE | doi:10.20944/preprints201812.0039.v1
Subject: Materials Science, Metallurgy Keywords: friction stir-welding; aluminum-copper; SKP; corrosion test; electrochemical; tool travel speed
Online: 4 December 2018 (02:57:09 CET)
The aim of this work is to assess the influence of Friction Stir Welding (FSW), process parameters, optimized tool traveling speed, and corrosion resistance of the 0.95 Mg-Al-alloy and pure copper weldment. Samples of aluminum-copper with and without deformation were characterized to investigate the metallurgical effects created during the welding deformation process. Effect of process parameters on microstructure and corrosion rate have been investigated for all the samples. All the electrochemical and polarization tests were done in 3.5 wt.% NaCl solution. Scanning Kelvin Probe (SKP) was done to detect the localized corrosion on the surface. Optical micrography observation indicated that the primary α-Al phase, which was formed during solidification can effectively limit the growth of Cu9Al4 phase. Finer acicular α-Al precipitates were observed in CuAl matrix during joining process that tends to coarser with the increase in tools travel speed. The electrochemical and polarization results showed that among all the tool travelling speed the specimen joined at tool travelling speed of 40 mm/min shows the best non-corrosive property.
ARTICLE | doi:10.20944/preprints202110.0137.v1
Subject: Medicine & Pharmacology, Pathology & Pathobiology Keywords: Wilson disease; ATPase copper transporting beta; autophagosome-lysosome fusion; HepG2; LC3 interaction region
Online: 8 October 2021 (11:06:51 CEST)
Macroautophagy/autophagy plays an important role in cellular copper clearance. The means by which the copper metabolism and autophagy pathways interact mechanistically is vastly unexplored. Dysfunctional ATP7B, a copper-transporting ATPase, is involved in the development of monogenic Wilson disease, a disorder characterized by disturbed copper transport. Using in silico prediction, we found that ATP7B contains a number of potential binding sites for LC3, a central protein in autophagy pathway, so-called LC3 interaction regions (LIRs). The conserved LIR3, located at the C-terminal end of ATP7B, was found to directly interact with LC3B in vitro. Replacing the two conserved hydrophobic residues W1452 and L1455 of LIR3 significantly reduced interaction. Furthermore, autophagy was induced in normal human hepatocellular carcinoma cells (HepG2) leading to enhanced colocalization of ATP7B and LC3B on the autophagosome membranes. By contrast, HepG2 cells deficient of ATP7B (HepG2 ATP7B-/-) showed autophagy deficiency at elevated copper condition. This phenotype was complemented by heterologous ATP7B expression. These findings suggest a cooperative role of ATP7B and LC3B in autophagy-mediated copper clearance.
ARTICLE | doi:10.20944/preprints202106.0601.v1
Subject: Materials Science, Biomaterials Keywords: bactericidal; biocompatibility; copper; human fibroblast; physical vapor deposition (PVD); silver; titanium; thin films
Online: 24 June 2021 (11:04:43 CEST)
Mechanical robustness, biocompatibility, and antibacterial performances are key features for materials suitable to be used in tissue engineering applications. In this work, we investigated the link existing between structural and functional properties of TiCu(Ag) thin films deposited by physical vapor deposition magnetron sputtering on Si substrates. The thin films were characterized by X-ray diffraction (XRD), nanoindentation, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The TiCu(Ag) thin films showed complete amorphous structure and improved mechanical properties in comparison with pure Ti films. However, for contents in excess of 20% Ag, we observed the appearance of nanometric Ag crystallite. The TiCu(Ag) thin films displayed excellent biocompatibility properties, allowing adhesion and proliferation of the human fibroblasts MRC-5 cell line. Moreover, all the investigated TiCu(Ag) alloy display bactericidal properties, preventing the growth of both Pseudomonas aeruginosa and Staphylococcus aureus. Results obtained from biological tests have been correlated to the surface structure and microstructure of films. The excellent biocompatibility and bactericidal properties of these multifunctional thin films opens to their use in tissue engineering applications.
Subject: Chemistry, Applied Chemistry Keywords: electrocatalyst; oxygen evolution reaction; dithiooxamide; chelate polymers; copper oxides; metal-air batteries; alkaline
Online: 21 January 2020 (09:04:30 CET)
Efficient oxygen evolution reaction (OER) electrocatalysts are highly desired in the field of water electrolysis and rechargeable metal-air batteries. In this study, a chelate polymer, composed of copper (II) and dithiooxamide, was used to derive an efficient catalytic system for OER. Upon potential sweep in 1M KOH, copper (II) centers of the chelate polymer were transformed to CuO and Cu(OH)2. The carbon-dispersed CuO nanostructures formed a nanocomposite which exhibits an enhanced catalytic activity for OER in alkaline media. The nanocomposite catalyst has overpotential of 280 mV (at 1 mA/cm2) and a Tafel slope of 81 mV/dec in 1M KOH solution. It has a seven-fold higher current than IrO2/C electrode, per metal loading. A catalytic cycle is proposed, in which, CuO undergoes electrooxidation to Cu2O3 that further decomposes to CuO with releasing oxygen. This work reveals a new method to produce an active nanocomposite catalyst for OER in alkaline media using a non-noble metal chelate polymer and a porous carbon. This method can be applied to the synthesis of transition metal oxide nanoparticles used in the preparation of composite electrodes for water electrolyzers and can be used to derive cathode materials for aqueous-type metal-air batteries.
Subject: Physical Sciences, Condensed Matter Physics Keywords: high temperature copper-oxide superconductors; time-dependent density functional theory; electron-pairing medium
Online: 10 July 2019 (10:29:23 CEST)
Real-time evolution of the electron densities under excitations in La2CuO4 was calculated by the time-dependent density functional theory (TDDFT). The author found, for the first time, under excitations, the electron cloud of Cu2+ changes obviously and the characteristic frequencies are 83 meV and 36 meV, respectively, for two different modes. The results are unexpected and close to that of lattice vibrations. The results show that the electron cloud of Cu2+ (just like the lattice) can be the electron-pairing medium in high temperature copper oxide superconductors.
ARTICLE | doi:10.20944/preprints201810.0123.v4
Subject: Chemistry, Applied Chemistry Keywords: chitosan-copper NPs; quinolone derivatives; ultrasonic irradiation; one- pot synthesis; green-sustainable perspectives
Online: 19 December 2018 (03:25:20 CET)
Chitosan decorated copper nanoparticles (CS/CuNPs) catalysts were synthesized via reduction methods utilizing green protocol. The CS/CuNPs hybrid catalysts were tested for the synthesis of quinoline derivatives utilizing one-pot multicomponent reaction (MCR) under ultrasonic irradiation. The best catalyst (CS/CuNPs) that provided good conversion reaction yield and high turnover frequency (TOF) was characterized using Fourier transform infrared (FTIR), Thermogravimetric analyses (TGA), X-ray diffraction (XRD), , scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) techniques. Generalization of the scope of the proposed catalytic process was studied using different aldehydes. Excellent products yield and high TOF in even shorter reaction time (~5 min) was attained. Recyclability performance of the catalyst over five times re-use without detectable loss in product yield was recorded. The current method is green process utilizing environmentally benign catalyst and considered to be promising sustainable protocol for the synthesis of fine chemicals.
ARTICLE | doi:10.20944/preprints201812.0107.v1
Subject: Chemistry, Physical Chemistry Keywords: clay; diazonium salt; ion imprinted polymers; radical photopolymerization; visible light; adsorption; copper ions
Online: 10 December 2018 (14:27:52 CET)
There is an urgent demand worldwide for the development of highly selective adsorbents and sensors of heavy metal ions and other organic pollutants. Within these environmental and public health frameworks, we are combining the salient features of clays and chelatant polymers to design selective metal ion adsorbents. Towards this end, the ion imprinting approach has been used to develop a novel nanohybrid material for the selective separation of Cu2+ ions in aqueous solution. The Cu2+-imprinted polymer/ montmorillonite nanocomposite (IIP/Mt) and non-imprinted polymer/montmorillonite nanocomposite (NIP/Mt) were prepared by radical photopolymerization process in the visible light. Ion imprinting was indeed important as the recognition of copper ions by IIP/Mt was significantly superior to that of NIP/Mt that is the nanocomposite synthesized in the same way but in the absence of Cu2+ ions. The adsorption process as batch study was investigated under the experimental condition affecting same parameters such as contact time, concentration of ions metals and pH. The adsorption capacity of Cu2+ ions is maximized at pH 5. Removal of Cu2+ ion achieved equilibrium within 15 minutes; the results obtained were found to be fitted by the pseudo-second order kinetics model. The equilibrium process was well described by the Langmuir isothermal model and the maximum adsorption capacity was found to be 23.6 mg/g.
ARTICLE | doi:10.20944/preprints201804.0244.v1
Subject: Earth Sciences, Other Keywords: oyonite; lillianite homologous series; sulfosalt; copper; antimony; arsenic; Oyon district; Lima department; Peru
Online: 18 April 2018 (16:09:50 CEST)
The new mineral species oyonite, ideally Ag3Mn2Pb4Sb7As4S24, has been discovered in the Uchucchacua polymetallic deposit, Oyon district, Catajambo, Lima Department, Peru, as very rare black metallic subhedral to anhedral crystals, up to 100 μm in length, associated with orpiment, tennantite/tetrahedrite, menchettiite, and other unnamed minerals of the system Pb-Ag-Sb-Mn-As-S, in calcite matrix. Its Vickers hardness (VHN100) is 137 kg/mm2 (range 132–147). In reflected light, oyonite is weakly to moderately bireflectant and weakly pleochroic from dark grey to a dark green. Internal reflections are absent. Reflectance values for the four COM wavelengths (Rmin, Rmax (%) (λ in nm)) are: 33.9, 40.2 (471.1); 32.5, 38.9 (548.3), 31.6, 38.0 (586.6); and 29.8, 36.5 (652.3). Electron microprobe analysis gave (in wt %, average of 5 spot analyses): Cu 0.76 (2), Ag 8.39 (10), Mn 3.02 (7), Pb 24.70 (25), As 9.54 (12), Sb 28.87 (21), S 24.30 (18), total 99.58 (23). On the basis of 20 cations per formula unit, the chemical formula of oyonite is Cu0.38Ag2.48Mn1.75Pb3.79Sb7.55As4.05S24.12. The main diffraction lines are (d in Å, hkl and relative intensity): 3.34 (-312; 40), 3.29 (-520; 100), 2.920 (-132; 40), 2.821 (-232; 70), 2.045 (004; 50). The crystal structure study revealed oyonite to be monoclinic, space group P21/n, with unit-cell parameters a = 19.1806 (18), b = 12.7755 (14), c = 8.1789 (10) Å, β = 90.471 (11)°, V = 2004.1 (4) Å3, Z = 2. The crystal structure was refined to a final R1 = 0.032 for 6272 independent reflections. Oyonite belongs to the Sb-rich members of the andorite homeotypic sub-series within the lillianite homologous series. The name oyonite is after the Oyon district, Lima Department, Peru, the district where the type locality (Uchucchacua mine) is located.
ARTICLE | doi:10.20944/preprints201910.0011.v1
Subject: Arts & Humanities, Archaeology Keywords: copper slag; sulphide; chalcocite; сovellite; bornite; LA-ICP-MS; South Ural; Kazakhstan; Bronze Age
Online: 2 October 2019 (03:32:26 CEST)
In the paper, the results of an investigation into trace elements found in slag sulphides from 14 archaeological Bronze Age settlements of the Cis-Urals, Trans-Urals and North and Central Kazakhstan are presented. The study used Cu-(Fe)-sulphides as indicator minerals. Cu-(Fe)-S minerals in slags are primarily represented by covellite and chalcocite, as well as by rarer bornite and single chalcopyrite grains. Slag sulphides formed relic clasts and neogenic droplets of different shapes and sizes. Supergenic ores in the Bronze Age in Urals and Kazakhstan played a significant role in the mineralogical raw material base. In sulphides, the main indicator elements Fe, Co, Ni, As, Se, Te, Sb, Ag, Pb, and Bi are important markers of copper deposit types. Sulphides from olivine Cr-rich spinel containing slags of Ustye, Turganik, and Kuzminkovskoe 2 are characterised by As-Co-Ni assemblages and confined to copper deposits in ultramafic rocks. Olivine sulphide-containing slags from Kamenny Ambar, Konoplyanka and Sarlybay 3 are characterised by Co-Se-Te assemblage and confined to mafic rocks. Glassy sulphide-containing slags from Katzbakh 6, Turganik, Ordynsky Ovrag, Ivanovskoe, Tokskoe, Bulanovskoe 2, Pokrovskoe, Rodnikovoe, and Taldysay are characterised by Ag-Pb-(Ba)-(Bi) assemblage and confined to cupriferous sandstone deposits. High As, Sb, Sn and Ba contents found in slags can be seen as indicators of alloying or flux components in primary copper smelting. These include samples from Ustye, Katzbakh 6, Rodnikovoe, and Taldysay sites, where high Ba and As slag contents are identified. The compilation of a database with a broad sample of sulphide compositions from Bronze Age slags and mines in the Urals and Kazakhstan will permit the further identification of ore types and raw materials associated with a particular deposit.
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: blood-brain barrier; copper/iron homeostasis; neurodegenerative (Alzheimers, Parkinsons, Prion) disease; North Ronaldsay sheep
Online: 27 May 2019 (12:27:10 CEST)
The neurodegenerative diseases (Alzheimers, Parkinsons, amyotrophic lateral sclerosis, Huntingdons) and the prion disorders, have in common a dysregulation of metalloprotein chemistry involving redox metals (Cu,Fe,Mn). The consequent oxidative stress gives rise to protein plaques and neuronal cell death. An equilibrium exists between the functional requirement of the brain for Cu and Fe and their destructive potential with the production of reactive oxygen species. The importance of the brain barrier is highlighted in regulating the import of these metals. Upregulation of key transporters occurs in foetal and neonatal life when brain metal requirement is high and is down-regulated in adult life when need is minimal. By contrast a neonatal mode of CTR1 upregulation persists in feral N.Ronaldsay sheep. This has led to the premise that metal regulation may return to the default setting in ageing with implications for neurodegenerative disease.
ARTICLE | doi:10.20944/preprints201904.0319.v1
Subject: Life Sciences, Biotechnology Keywords: Gymnema sylvestre; cell suspension cultures; copper oxide nanoparticles; gymnemic acid; phenolic compounds; pharmacological activity
Online: 28 April 2019 (12:09:11 CEST)
Gymnema sylvestre is a pharmacological plant which has a rich source of bioactive compounds specifically gymnemic acid (GA) and phenolic compounds (PC) that used for pharmaceutical industries. Sources for naturally occurring bioactive compounds are limited, due to geographical and seasonal variations; on the other hand, it is commercially in demand. Biosynthesis of G. sylvestre phytochemicals through in vitro culture often enhanced by elicitation. The use of cell suspension cultures (CSC) has interested serious attention on the production of essential phytochemicals. The current study is aimed at improving the contents of GA and PC in G. sylvestre CSC using the copper oxide nanoparticles (CuO NPs). Callus was obtained on MS medium with 2.0 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D), 0.1 mg/L kinetin (KIN), phytoagar (8.0 g/L), and sucrose (30 g/L). The above medium devoid of agar was used for the initiation of CSC. The CSC was treated with three levels of CuO NPs (1, 3 or 5 mg/L) to enhance the production of GA and PC. The greatest amount of GA (89.25 mg/g dry cell mass, DCM), total phenolic (245.10 mg/g), and flavonoid (4.57 mg/g) in CSC were achieved when G. sylvestre cells were treated for 48 h with 3 mg/L CuO NPs. Also, the biomedical potential (antioxidant, antidiabetic, anti-inflammatory, antibacterial, antifungal and anticancer activities) were also high in the CuO NPs (3 mg/L) treated CSC extracts of G. sylvestre. CuO NPs elicitation of CSC significantly increased production of GA (9-fold), and PC than non-elicited CSC in G. sylvestre.
ARTICLE | doi:10.20944/preprints201807.0014.v1
Subject: Life Sciences, Biotechnology Keywords: beans; iron, zinc and copper bioaccessibility; myo-inositol phosphates; anti-nutrients; polyphenols; household processing
Online: 2 July 2018 (13:19:42 CEST)
Micronutrient deficiencies are a major public health problem. Beans are an important plant-based source of iron, zinc and copper, but their absorption is reduced in the presence of anti-nutrients such as phytates, polyphenols and tannins. Soaking and discarding the soaking water before cooking is unanimously recommended, but this can result in mineral loss. Data on the consequences for mineral bioaccessibility is still limited. This study aimed to evaluate iron, zinc and copper bioaccessibility in black beans cooked (regular pan, pressure cooker) with and without the soaking water. Minerals were quantified by ICP-MS, myo-inositol phosphates (InsP5, InsP6) by HPLC ion-pair chromatography, total polyphenols using Folin-Denis reagent and condensed tannins using Vanillin assay. Mineral bioaccessibility was determined by in vitro digestion and dialysis. All treatments resulted in a statistically significant reduction of total polyphenols (30%) and condensed tannins (20%). Only when discarding the soaking water a loss of iron (6%) and copper (30%) was observed, and InsP6 was slightly decreased (7%) in one treatment. Bioaccessibility of iron and zinc were low (about 0.2% iron and 35% zinc), but copper presented high bioaccessibility (about 70%). Cooking beans under pressure without discarding the soaking water resulted in the highest bioaccessibility levels among all household procedures. Discarding the soaking water before cooking did not improve the nutritional quality of the beans.
ARTICLE | doi:10.20944/preprints201705.0213.v2
Subject: Social Sciences, Business And Administrative Sciences Keywords: copper; in-use stock; average age; average use life method; fixed assets depreciation method
Online: 2 June 2017 (07:36:06 CEST)
With the increasing of copper consumption, the in-use stock of copper tends to increase. This paper used the “average use life method” to quantify the amount of copper in-use stock, and calculated the average age of in-use stock. It was indicated that the total in-use stock had an overall smooth trends, and reached its peak in 2007 was about 68.9 Mt (million tons), in addition, in-use stock per capita reached its peak ,234 kg/capita in 2001. The results demonstrated that during the period 1992-2002, the average age of copper in-use stock was continually decreased, but gradually increased since the year 2003. The fixed assets depreciation method used in this paper is applied to analyze depreciated copper in-use stock, and to analyze the relationship with economic indicator (GDP). It is demonstrated that it was inconsistent with the theory of Environmental Kuznets Curve (EKC) before 2000, this might be the demand for copper in the service sector is greater than the reduced strength of alternatives. Finally, scenario analysis of future copper in-use stock and depreciated copper in-use stock per capita in the U.S. were presented. The corresponding average age of the in-use stock will have a slight rise in the next decade.
REVIEW | doi:10.20944/preprints202102.0345.v1
Subject: Keywords: Copper indium gallium selenide layers; Solar cell efficiency; Self-cleaning; Superhydrophobic coatings; Vapour deposition technique
Online: 17 February 2021 (08:23:49 CET)
Solar cell layers technology has achieved global standing in the solar cell layers deposition process, and it covers the innovative methods and techniques in significant applications. Recent solar cell layers technology has an advanced interest in a refined approach to enhance performance and highlights the importance of recent proficient procedures for manufacturing. For example, the application is used to search for novel materials for solar cells' layers to clarify the current energy crisis. The technological process and various types of solar cells depend on climate change. Among them, layers of solar cells and silicon wafer solar cells are very encouraging. Solar cell layers technology has led to solar cells being a more reasonable active option in design and production. The productivities facilitated by new solar cells still need to be enhanced for the various processes involved in the additional enhancement from Copper Indium Gallium Selenide (CIGS) microfilms to solar cell crystal structure dye-sensitized solar cells. The hydrophobic coating works as an anti-dust coating, enhancing efficiency and decreasing the cost of cleaning solar cells. In Saudi Arabia Majmaah City, most solar projects are in dry regions, where the dusty weather reduces solar cell efficiency. Therefore, combining these two properties and applying an anti-reflective and superhydrophobic coating will increase solar cell efficiency by 20%. Solar cells' crystal structure results are substituted with layers or new materials to balance environmental impact and toxic nature.
ARTICLE | doi:10.20944/preprints201807.0267.v1
Subject: Chemistry, Food Chemistry Keywords: Filuferru; spirit; distillation; grape marc; volatile compounds; copper; trace elements; GC-MS; ICP-MS; PCA
Online: 16 July 2018 (09:23:20 CEST)
Traditional Filuferru is an ancient spirit from Sardinia, Italy, usually obtained from the distillation of wine or grape marc. In this contribution, the results of the first chemical characterization of a wide number of craft Filuferru samples has been accomplished in terms of evaluation of the alcoholic strength, qualitative and quantitative GC-MS analysis of the volatile composition of the distillate, and its trace element composition by means a ICP-MS method. Both instrumental methods have been validated and applied on 21 craft samples of Filuferru, whereas one sample of commercial distillate has been analyzed for comparison purposes. Alcoholic strength ranged between 41.0 and 62.4% (v/v). Sixty volatile compounds were identified and ten of them have been quantified. Analogies and differences with Grappa (i.e. the Italian distilled spirit most close to Filuferru) have been highlighted in the qualitative and quantitative profile of this matrix. Often meaningful amounts of acetaldehyde, ethyl acetate, dietyl acetal and acetic acid were measured. Elemental analysis, performed on toxic, non-toxic elements and oligoelements, 18 in total, revealed a wide variability of concentrations in both analytes and samples. High concentrations of Cu are sometimes evidenced, likely caused by losses from the distillation apparatus. The principal components analysis (PCA) allowed the differentiation of the ten volatile compounds quantified in two groups: the former, described mainly by PC1, constituted by acetic acid, ethyl acetate, dietyl acetal and acetaldehyde, and the second, described by PC2, constituted by 1-propanol, 2-methyl-1-propanol, the two coeluiting isomers 2-methyl-1-butanol and 3-methyl-1-butanol,1-hexanol, 2-phenylethanol and 2,3-butanediol. Data obtained may be useful in order to establish a regulation for the production of high-quality traditional Filuferru from Sardinia.
ARTICLE | doi:10.20944/preprints202205.0286.v1
Subject: Medicine & Pharmacology, Dentistry Keywords: bioglass; ion release; hydroxyapatite deposition; bone tissue regeneration; macrophages; vascularization; copper doping; strontium doping; 45S5; ICIE16
Online: 23 May 2022 (05:24:12 CEST)
Bioglasses are highly adoptable bone substitute materials, which can be combined with so-called therapeutic ions. These ions have shown to influence underlying molecular processes of the bone regeneration cascade. Moreover, it is known that bone substitutes induce an immune reaction within their implantation area involving macrophages and their pro- and anti-inflammatory subtypes dependent on their chemical composition. However, only poor knowledge exists regarding the influence of therapeutic ions onto the immune reactions and the associated bone healing. Thus, the aim of this work was to investigate the influence of strontium- and copper-doped bioglasses on the induction of M1- and M2-macrophages as well as the implant bed vascularization. (2) Methods: For this study, two alkali glasses were produced on basis of ICIE-16 bioglass via the melt-quench route with the addition of 5 wt% copper or strontium (ICIE16-Cu and ICIE16-Sr). Pure ICIE16 and 45S5 bioglasses were used as control materials. The bioactivity (ion release), chemical composition and the surface pattern were investigated, as well as an in vivo experiment was performed using the subcutaneous implantation model in rats. (3) Results: SEM imaging showed different formations of hydroxyapatite on the surfaces of the bioglass systems after submersion in simulated body fluid. EDX analysis confirmed the doping process by showing the release kinetics. Copper-doped bioglass exhibited a higher ion release than strontium-doped bioglass. Copper induced both a low immune cell migration and triggered a low number of M1- and M2-macrophages but also of blood vessels. The strontium-containing bioactive glass induced higher numbers of M1-macrophages after 30 days. Both copper- and strontium-doped bioglasses induced comparable numbers of M2-macrophages as found in the control groups. (4) Conclusions: Bioglass doping with copper and strontium did not exhibit significant influence on the foreign body response or the implantation bed vascularization in vivo. However, the prepared bioglass systems seemed to be biocompatible.
ARTICLE | doi:10.20944/preprints202002.0249.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: Fungal diversity; Saccharomyces; genetic diversity; glyphosate-based herbicides; copper-based fungicides; RoundUp Ready™ corn; phylogenetics
Online: 17 February 2020 (15:37:11 CET)
Saccharomyces cerevisiae are a phenotypically diverse species that adapt to a wide variety of environments by exploiting standing genetic diversity and selecting for advantageous mutations. Glyphosate and copper-based herbicides/ fungicides affect non-target organisms, these incidental exposures can impact microbial populations. In this study, glyphosate resistance was found in the historical collection of yeast which was collected over the last century, but only in yeast isolated after the introduction of glyphosate. The highest glyphosate-resistant yeasts were isolated from agricultural sites. However, herbicide application at these sites was not recorded. In an effort to assess glyphosate resistance and impact on non-target microorganisms, yeast were harvested from 15 areas with known herbicidal histories, including an organic farm, conventional farm, remediated coal mine, suburban locations, state park, and a national forest. Yeast representing 23 genera were isolated from 237 samples of plant, soil, spontaneous fermentation, nut, flower, fruit, feces, and tree material samples. Saccharomyces, Candida, Metschnikowia, Klyveromyces, Hanseniaspora, and Pichia were other genera commonly found across our sampled environments. Managed areas had less species diversity and at the brewery, only Saccharomyces and Pichia were isolated. A conventional farm growing RoundUp Ready™ corn had the lowest phylogenetic diversity and the highest glyphosate resistance. The mine was sprayed with multiple herbicides including a commercial formulation of glyphosate; however, the yeast did not have elevated glyphosate resistance. In contrast to the conventional farm, the mine was exposed to glyphosate only one year prior to sample isolation. Glyphosate resistance is an example of the anthropogenic selection of nontarget organisms.
REVIEW | doi:10.20944/preprints201810.0429.v1
Subject: Medicine & Pharmacology, Gastroenterology Keywords: Copper; fructose; Kupffer cell (KC); iron; non-alcoholic fatty liver disease (NAFLD); metabolic syndrome; gut microbiota
Online: 18 October 2018 (16:57:06 CEST)
Compelling epidemiologic data support the critical role of dietary fructose in the epidemic of obesity, metabolic syndrome and nonalcoholic fatty liver disease (NAFLD). The metabolic effects of fructose on the development of metabolic syndrome and NAFLD are not completely understood. High fructose intake impairs copper status, and copper-fructose interactions have been well documented in rats. Altered copper-fructose metabolism leads to exacerbated experimental metabolic syndrome and NAFLD. A growing body of evidence has demonstrated that copper levels are low in NAFLD patients. Moreover, hepatic and serum copper levels are inversely correlated with the severity of NAFLD. Thus, high fructose consumption and low copper availability are considered two important risk factors in NAFLD. However, the causal effect of copper-fructose interactions as well as the effects of fructose intake on copper status remain to be evaluated in humans. The aim of this review is to summarize the role of copper-fructose interactions in the pathogenesis of the metabolic syndrome and discuss the potential underlying mechanisms. This review will shed light on the role of copper homeostasis and high fructose intake and point to copper-fructose interactions as novel mechanisms in the fructose induced NAFLD.
REVIEW | doi:10.20944/preprints202205.0009.v1
Subject: Engineering, Other Keywords: mineral waste; bio-base waste; natural fiber; biomass; sulfur waste; copper flotation; fly ash; biochar; sustainable construction
Online: 4 May 2022 (13:12:11 CEST)
The new climate law introduces a policy of sustainable construction, the assumption of which is the reduction of CO2 by the construction industry and the use of environmentally friendly materials, such as agricultural, mineral, and recycled waste, while limiting the consumption of natural resources. The article is a literature review that analyzes selected waste materials from various sectors of the economy that can be used as additives or partial substitutes for natural resources in the production of cement and in and cement building materials, the production of which reduces CO2 emissions, producing materials with high mechanical strength and environmentally friendly.
ARTICLE | doi:10.20944/preprints202105.0719.v1
Subject: Chemistry, Analytical Chemistry Keywords: C-H activation; imidazoles; Fujiwara-Moritani reaction; dehydrogenative coupling; oxidative Heck coupling; styrenes; palladium catalysis; copper salts
Online: 31 May 2021 (09:14:12 CEST)
The construction of carbon-carbon bonds by direct involvement of two unactivated carbon-hydrogen bonds, without any directing group, ensures an high atom economy of the entire process. Here it is described a simple protocol for the Pd(II)/Cu(II)-promoted intermolecular cross-dehydrogenative coupling (CDC) of 5-arylimidazoles, benzimidazoles, benzoxazole and 4,5-diphenylimidazole at their C-2 position with functionalized styrenes. This specific CDC, known as Fujiwara-Moritani reaction or oxidative Heck coupling, allowed also the C-4 alkenylation of the imidazole nucleus when both 2 and 5 positions are occupied.
ARTICLE | doi:10.20944/preprints201906.0020.v1
Subject: Earth Sciences, Geochemistry & Petrology Keywords: REE distribution pattern; REE fluid-melt partition coefficient; granite; intrusion-related gold system; porphyry copper (gold) system
Online: 3 June 2019 (12:16:38 CEST)
A practical method is presented to estimate rare earth elements (REE) concentrations in magmatic vapour phase (MVP) in equilibrium with water-saturated granitic melts based on empirical fluid-melt partition coefficients of REE (k_P^REE). The values of k_P^REEcan be calculated from a set of new polynomial equations linking to the chlorine molality (m_Cl^v) of the MVP associated with granitic melts, which are established via a statistical analysis on the existing experimental dataset. These equations may be applied to the entire pressure range (0.1 to 10.0 kb) within the continental crust, suggesting that light REEs behave differently in magmatic fluids, i.e. either being fluid compatible with higher m_Cl^v or fluid incompatible with lower m_Cl^v values. In contrast, heavy REEs are exclusively fluid incompatible and partition favourably into granitic melts. Consequently, magmatic fluids tend to be rich in LREE relative to HREE, leading to REE fractionation during the evolution of magmatic hydrothermal systems. Maximum k_P^REEvalue for each element is predicted and presented in a REE distribution diagram constrained by the threshold of m_Cl^v. REE contents of the granitic melt is approximated by whole-rock analysis, so that REE concentrations in the associated MVP would be estimated from the value of k_P^REE given chemical equilibrium retains. Two examples are provided respectively, to show the use of this method as a REE tracer to fingerprint the source of ore-fluids responsible for the Lake George intrusion-related Au-Sb deposit in New Brunswick (Canada), and for the Bakircay Cu-Au (-Mo) porphyry systems in northern Turkey.
ARTICLE | doi:10.20944/preprints201708.0096.v1
Subject: Life Sciences, Biotechnology Keywords: CTR1 metal-binding extracellular domain cloning; copper/silver chelation; E. coli filamentous growth; secondary silver nanoparticles formation
Online: 27 August 2017 (11:56:08 CEST)
There is much interest in effective copper chelators to correct copper dyshomeostasis in neurodegenerative and oncological diseases. In this study, a recombinant fusion protein for expression in E. coli cells was constructed from glutathione-S-transferase (GST) and the N-terminal domain (ectodomain) of human high affinity copper transporter CTR1 (hNdCTR1), which has three metal-bound motifs. Several biological properties of the GST-hNdCTR1 fusion protein were assessed. It was demonstrated that in cells, the protein was prone to oligomerization, formed inclusion bodies and displayed no toxicity. Treatment of E. coli cells with copper and silver ions reduced cell viability in a dose- and time-dependent manner. Cells expressing GST-hNdCTR1 protein demonstrated resistance to the metal treatments. These cells accumulated silver ions and formed nanoparticles that contained AgCl and Ag0. In this bacterial population, filamentous bacteria with length about 10 μm were often observed. The possibility for the fusion protein carrying extracellular metal binding motifs to integrate into the cell’s copper metabolism and its chelating properties are discussed.
ARTICLE | doi:10.20944/preprints202107.0119.v1
Subject: Materials Science, General Materials Science Keywords: Keywords: electrochemical corrosion, metallic coatings, electrolysis, diffusion, intermetallic compounds, phases formation kinetics, copper, aluminium, iron, Kirkendall-Frenkel porosity, Kirkendall sh
Online: 5 July 2021 (16:24:31 CEST)
Our investigations show that electrochemical corrosion of copper is faster than electrochemical corrosion of aluminium at temperatures below 100oC. Literature data analysis shows that the Al atoms diffuse faster than the Cu atoms at temperatures higher than 475oC, Al rich intermetallic compounds (IMCs) are formed faster in the Cu-Al system, and the Kirkendall plane shifts toward Al side. Electrochemical corrosion occurs due to electric current and due to diffusion. An electronic devise working time, for example, depends on initial copper cover thickness on aluminium wire, connected to the electronic devise, temperature, and volume and dislocation pipe diffusion coefficients, so copper, iron, and aluminium electrochemical corrosion rates are investigated experimentally at room temperature and at temperature 100oC. Intrinsic diffusivities ratios of copper and aluminium at different temperatures and diffusion activation energies in the Cu-Al system are calculated by proposed here methods using literature experimental data. Dislocation pipe and volume diffusion activation energies of pure iron are calculated separately by earlier proposed method using literature experimental data. Aluminium dissolved into NaCl solution as the Al3+ ions at room temperature and at temperature 100oC, iron dissolved into NaCl solution as the Fe2+ (not Fe3+) ions at room temperature and at temperature 100oC, copper dissolved into NaCl solution as the Cu+ ions at room temperature and as the Cu+ and the Cu2+ ions at temperature 100oC. It is founded experimentally that copper corrosion is higher than aluminium corrosion, and ratio of electrochemical corrosion rates, kCu/kAl>1, decreases with temperature increasing, although iron electrochemical corrosion rate doesn’t depend on temperature below 100oC. It is obvious, because melting point of iron is more higher then melting point of copper or aluminium. It is calculated that copper electrochemical corrosion rate is approximately equal to aluminium electrochemical corrosion at temperature about 300oC, so copper can dissolve into NaCl solution mostly as the Cu2+ ions at temperature about 300oC. Ratio of intrinsic diffusivities, DCu/DAl <1, increases with temperature increasing, and intrinsic diffusivity of aluminium could be approximately equal to intrinsic diffusivity of copper at temperature about 460oC.
ARTICLE | doi:10.20944/preprints202009.0171.v1
Subject: Biology, Physiology Keywords: protein-protein interaction network; GPx; glutathione peroxidases genes; ciliate protists; copper; metals; antioxidant system; free-radicals; ROS; reactive oxygen species
Online: 8 September 2020 (04:59:18 CEST)
Glutathione peroxidases (GPxs) form a broad family of antioxidant proteins essential for maintaining redox homeostasis in eukaryotic cells. In this study, we used an integrative approach that combines bioinformatics, molecular biology, and biochemistry to investigate the role of GPxs in reactive oxygen species detoxification in the unicellular eukaryotic model organism Tetrahymena thermophila. Both phylogenetic and mechanistic empirical model analyses provided indications about the evolutionary relationships among the GPXs of Tetrahymena and the orthologous enzymes of phylogenetically related species. In-silico gene characterization and text mining were used to predict the functional relationships between GPxs and other physiologically-relevant processes. The GPx genes contain conserved transcriptional regulatory elements in the promoter region, which suggest that transcription is under tight control of specialized signaling pathways. The bioinformatic findings were next experimentally validated by studying the time course of copper (Cu)-dependent regulation of gene transcription and enzymatic activity. Results emphasize the role of GPxs in the detoxification pathways that, by complex regulation of Cu-dependent GPx gene expression, enables Tetrahymena to survive in high Cu concentrations and the associated redox environment.
ARTICLE | doi:10.20944/preprints201812.0208.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: flux switching machine; modular rotor; non-overlap winding; magnetic flux analysis; iron losses; copper loss; stress analysis; finite element method
Online: 18 December 2018 (03:41:08 CET)
In recent years, numerous topologies of single phase and three phase Field Excited Flux-Switching Machine (FEFSM) have been developed for several applications. Comparative study of three types of single-phase low-priced Field Excited Flux-Switching Machine (FEFSM) is presented in this paper. Both the conventional 8S/4P sub-part rotor design and 6S/3P salient rotor design have an overlapped winding arrangements between armature coil and field excitation coil that depicts high copper losses as well as results in increased size of motor. Additionally, FEFSM with salient structure of the rotor have high flux strength in the stator-core that has much impact on high iron losses. Copper consumption and iron loss being a crucial proportion in total machine losses. Therefore a novel topology of single phase modular rotor field excited FSM with 8S/6P configuration is proposed, which enable non-overlap arrangement between armature coil and FEC winding that facilitates devaluation in the copper losses. The proposed modular rotor design acquires reduced iron losses as well as reduced active rotor mass comparatively to conventional rotor design. It is very persuasive to analyze the best range of speed for these rotors to avoid cracks and deformation, the maximum tensile strength (can be measured with principal stress in research) of the rotor analysis is conducted using JMAG. A deterministic optimization technique is used to enhance the performance of 8S/6P modular rotor design. The electromagnetic performance of conventional sub-part rotor design, F1-A3-3P design and proposed novel-modular rotor design are analyzed by 3D-Finite Element Analysis (3D-FEA), includes flux linkage, flux distribution, flux strength, back-EMF, cogging torque, torque characteristics, iron losses and efficiency.
ARTICLE | doi:10.20944/preprints201806.0232.v1
Subject: Life Sciences, Biochemistry Keywords: hepcidin-25; copper; nickel; ATCUN motif; metal complex; MS; NMR structure; metal peptide, metalloprotein; metallopeptide, isomerization, racemization, purity, reference material
Online: 14 June 2018 (11:33:21 CEST)
Hepcidin-25 was identified as the main iron regulator in the human body by binding to the sole iron-exporter ferroportin. Studies showed that the N-terminus of hepcidin is responsible for this interaction, the same N-terminus that encompasses a small copper(II)-binding site known as ATCUN (amino terminal Cu(II)- and Ni(II)- binding) motif. Interestingly, this copper-binding property is largely ignored in most papers dealing with hepcidin-25. In this context, detailed investigations of the formed complex of hepcidin-25 with copper could reveal insights into its biological role. The present work is mainly focused on the study of the metal-bound form of hepcidin-25, which could be considered the biologically active form. The first part is devoted to the reversed-phase chromatographic separation of copper-bound and copper-free hepcidin-25, which was achieved by applying basic mobile phases containing 0.1% ammonia. Further, mass spectrometry (tandem mass spectrometry MS/MS, high resolution mass spectrometry HRMS) and nuclear magnetic resonance (NMR) spectroscopy were employed to characterize the copper-peptide. Lastly, a 3D model of hepcidin-25 with bound copper(II) is presented. The identification of metal complexes and potential isoforms and isomers, from which the latter usually are left undetected by mass spectrometry, led to the conclusion that complementary analytical methods are needed to characterize a peptide calibrant or reference material comprehensively. Quantitative nuclear magnetic resonance (qNMR), inductively-coupled plasma mass spectrometry (ICP-MS), ion-mobility spectrometry (IMS) and chiral amino acid analysis (AAA) should be considered among others.
ARTICLE | doi:10.20944/preprints202101.0607.v1
Subject: Materials Science, Polymers & Plastics Keywords: Organic-Inorganic Blends; Poly Methyl-Meth-Acrylate (PMMA); Poly-vinyl-alcohol (PVA); Copper oxide nanoparticles (CuONPs); Optical Characterization; Thermal stability; Surface Morphology.
Online: 29 January 2021 (09:03:22 CET)
We report the synthesis and characterization of Poly Methyl-Meth-Acrylate (PMMA)/Poly vinylalcohol (PVA) polymeric blend doped with different concentrations of Copper oxide (CuO) nanoparticles (NPs). The (PMMA-PVA)/CuO nanocomposite hybrid thin films (wt. % = 0%, 2%, 4%, 8%, and 16%) of CuO NPs are deposited on glass substrates via dip-coating technique. The transmittance (T%), reflectance (R%), the absorption coefficient (α), the optical constants [refractive index (n), extinction coefficient (k)], optical dielectric functions [ɛ',ɛ''] are investigated and interpreted. Tauc, Urbach, Spitzer-Fan, and Drude models are employed to calculate the optical bandgap energy (Eg) and the optoelectronic parameters of the nanocomposite thin films. The refractive index and optical bandgap energy of of (PMMA-PVA) polymeric thin film are found to be (1.5 to 1.85) and 4.101 eV, respectively. Incorporation of specific concentrations of CuO-NPs in (PMMA-PVA) polymeric thin films leads to a noticeable decrease in the optical bandgap energy and to an increase of the refractive index. Moreover, Fourier Transform Infrared Spectroscopy (FTIR) transmittance spectra are measured and analyzed for undoped and doped polymeric thin films to pinpoint the major vibrational modes in the spectral range (500 and 4000 cm-1), as well as, the nature of network bonding in both systems. Thermal stability of thin films is investigated by performing thermogravimetric analysis (TGA). The TGA thermograms confirm that both doped polymeric thin films are thermally stable at temperatures below 110°C which enables them to be attractive for a wide range of optical and optoelectronic applications. Our results indicate that optical, vibrational and thermal properties of both polymeric thin films can be tuned for specific applications by the appropriate corporation of particular concentrations of CuO-NPs.
ARTICLE | doi:10.3390/sci2020046
Subject: Keywords: portable X-ray fluorescence spectrometer (pXRF); Potential Toxic Elements (PTE); lead (Pb), zinc (Zn); copper (Cu); topsoil; sustainable urban drainage systems; SuDS; LID; BMPs; WSUD; GI; SCMs
Online: 13 June 2020 (00:00:00 CEST)
Sustainable urban drainage systems (SuDS) such as swales are designed to collect, store and infiltrate a large amount of surface runoff water during heavy rainfall. Stormwater is known to transport pollutants, such as particle-bound Potential Toxic Elements (PTE), which are known to often accumulate in the topsoil. A portable XRF instrument (pXRF) is used to provide in situ spatial characterization of soil pollutants, specifically lead (Pb), zink (Zn) and copper (Cu). The method uses pXRF measurements of PTE along profiles with set intervals (1 meter) to cover the swale with cross-sections, across the inlet, the deepest point and the outlet. Soil samples are collected, and the In-Situ measurements are verified by the results from laboratory analyses. Stormwater is here shown to be the transporting media for the pollutants, so it is of importance to investigate areas most prone to flooding and infiltration. This quick scan method is time and cost-efficient, easy to execute and the results are comparable to any known (inter)national threshold criteria for polluted soils. The results are of great importance for all stakeholders in cities that are involved in climate adaptation and implementing green infrastructure in urban areas. However, too little is still known about the long-term functioning of the soil-based SuDS facilities.
ARTICLE | doi:10.20944/preprints202104.0294.v1
Subject: Chemistry, Analytical Chemistry Keywords: Dimeric copper(I) complexes; PN phosphine ligands; X-ray structures; Combined thermally activated delayed fluorescence (TADF) and phosphorescence; Combined singlet and triplet harvesting; High emission quantum yields; Tunability of photophysical properties; Zero-field splitting (ZFS), Spin-lattice relaxation (SLR); Triplet substate decay components.
Online: 12 April 2021 (12:41:01 CEST)
We present an overview over eight brightly luminescent Cu(I) dimers of the type Cu2X2(PN)3 with X = Cl, Br, I and P^N = 2-diphenylphosphino-pyridine (Ph2Ppy), 2-diphenylphosphino-pyrimidine (Ph2Ppym), 1-diphenylphosphino-isoquinoline (Ph2Piqn) including three new crystal structures (Cu2Br2(Ph2Ppy)3, 1-Br, Cu2I2(Ph2Ppym)3, 2-I, and Cu2I2(Ph2Piqn)3, 3-I). However, we mainly focus on their photo-luminescence properties. All compounds exhibit combined thermally activated delayed fluorescence (TADF) and phosphorescence at ambient temperature. Emission color, decay time, and quantum yield varies over large ranges. For deeper characterization, we select Cu2I2(Ph2Ppy)3, 1-I, showing a quantum yield of 81 %. DFT and SOC-TDDFT calculations provide insight into the electronic structures of the singlet S1 and triplet T1 states. Both stem from metal+iodide-to-ligand charge transfer transitions. Evaluation of the emission decay dynamics, measured from 1.2 ≤ T ≤ 300 K, gives ∆E(S1-T1) = 380 cm-1 (47 meV), a transition rate of k(S1→S0) = 2.25×106 s-1 (445 ns), T1 zero-field splittings, transition rates from the triplet substates, and spin-lattice relaxation times. We also discuss the interplay of S1-TADF and T1-phosphorescence. The combined emission paths shorten the overall decay time. For OLED applications, utilization of both singlet and triplet harvesting can be highly favorable for improvement of the device performance.