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Chemistry, Organic Chemistry; heptamethine cyanine; protein labeling; thiol labeling; cancer targeting; vimentin
Online: 22 October 2018 (05:54:24 CEST)
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Convenient labeling of proteins is important for observing its function under physiological conditions. In tissues particularly, heptamethine cyanine dyes (Cy-7) are valuable because they absorb in near infrared (NIR) region (750 – 900 nm) where light penetration is maximal. In this work, we found Cy-7 dyes with a meso-Cl functionality covalently binding to proteins with free Cys residues under physiological conditions (aqueous environments, at near neutral pH, and 37 °C). It transpired that the meso-Cl of the dye was displaced by free thiols in protein, while nucleophilic side-chains from amino acids like Tyr, Lys, and Ser did not react. This finding shows a new possibility for convenient and selective labeling of proteins with near-IR fluorescent probes.
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Chemistry, Other; platinum iodido complexes; cytotoxicity; photoactivation
Online: 19 October 2018 (14:15:28 CEST)
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Trans platinum complexes have been the landmark in unconventional drugs prompting the development of innovative structures that might exhibit chemical and biological profiles different to cisplatin. Iodido complexes made a new turning point in the platinum drug design field since their cytotoxicity was reevaluated and reported. In this new study, we have synthesized and evaluated diodido complexes bearing aliphatic amines and pyridines in trans configuration. X-ray diffraction support the structural characterization. Their cytotoxicity has been evaluated in tumor cell lines such as SAOS-2, A375, T-47D and HCT116. Moreover, we report their solution behavior and reactivity with biological models. UVA irradiation induces an increase in their reactivity towards model nucleobase 5´-GMP in early stages, and promotes the release of the pyridine ligand (spectator ligand) at longer reaction times. Density Functional calculations have been performed and the results are compared with our previous studies with other iodido derivatives.
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Chemistry, Physical Chemistry; pKa; hydrogen bond; σ–hole
Online: 19 October 2018 (05:29:19 CEST)
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Theoretical approaches to calculate pKa values for Brønsted acids is a challenging task that, most of the time, involves sophisticated and time-consuming methods. Therefore, heuristic approaches are efficient and appealing methodologies to approximate these values. Herein, by considering the electrostatic potential on acidic hydrogen atoms in a similar fashion that a σ–hole is defined, we calculated the maximum surface potential, VS,max, and used it as a descriptor to correlate it with experimental acidity constants. These values were calculated using the CPCM implicit solvent model (water) with six different methods: five density functionals and the Møller–Plesset second order perturbation theory. Six different basis sets were combined with each method in order to benchmark a total of thirty-six levels of theory. Overall, 1080 calculations were performed and found to correlate with experimental data. The ωB97X-D/6-31+G(d,p) level of theory stands as the best one for consistently reproduce the reported pKa values.
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Chemistry, Analytical Chemistry; Tea; Salvia officinalis; Rosmarinus officinalis; Total phenolic; Antioxidant
Online: 18 October 2018 (12:52:37 CEST)
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Vitamin B2, also known as riboflavin (RF) is an essential micronutrient for human health and must be obtained from dietary sources. Plants biosynthesize riboflavin and are important dietary sources of vitamin B2 for humans. Our present study reports sensitive detection of Vitamin B2 in widely consumed for tea infusions, namely black, green, sage and rosemary tea infusions, by a capillary electrophoresis method combined with laser induced fluorescence detection. Moreover, the correlation between Vitamin B2 contents of tea plants with their total phenolics (TPs) and antioxidant capacity are evaluated in this study. Whereas green teas have the highest TPs and antioxidant capacity, the highest RF contents are in sage infusions. The RF contents range between 0.34 and 10.36 µg/g for all tea samples studied. Comparing RF contents of tea samples found in this study to the RF contents of known RF sources, tea infusions are proposed as important dietary sources of Vitamin B2.
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Chemistry, Other; Salvia pachyphylla; plant extracts; antioxidant; antimicrobial; antiproliferative; enzyme inhibitory
Online: 18 October 2018 (09:56:26 CEST)
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The antioxidant, antimicrobial, antiproliferative, and enzyme inhibitory properties of five extracts from aerial parts of Salvia pachyphylla were examined to assess the prospective of this plant as a source of natural products with therapeutic potential. Those properties were analyzed performing a set of standard assays. The extract obtained with dichloromethane showed the most variety of components, as yielded promising results in all completed assays. Furthermore, the extract obtained with ethyl acetate exhibited that greatest antioxidant activity as well as the best xanthine oxidase inhibitory activity. Remarkably, both extracts obtained with n-hexane or dichloromethane revealed significant antimicrobial activity against the Gram-positive bacteria; also, they showed greater antiproliferative activity against three representative cell lines of the most common types of cancers in women worldwide, and against a cell line that exemplifies cancers that typically develop drug resistance. Despite that other extracts were less active, such as the methanolic or aqueous, their results are promising for the isolation and identification of novel bioactive molecules.
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Chemistry, Analytical Chemistry; platinum; DNA; IR
Online: 18 October 2018 (07:54:20 CEST)
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Platinum(II) complexes have been found to be effective against cancer cells. Cisplatin curbs cell replication by interacting with the deoxyribonucleic acid (DNA), eventually leading to cell death and reducing cell proliferation. In order to investigate the ability of platinum complexes to affect cancer cells, two examples from the class of polyflurophenylorganoamidoplatinum(II) complexes were synthesised and tested on isolated DNA. The two compounds trans-[N,N’-bis(1,2,3,5,6-pentafluorophenyl)ethane-1,2-diaminato(1-)](2,3,4,5,6-pentafluorobenzoato)(pyridine)platinum(II) (PFB), and trans-[N,N’-bis(1,2,3,5,6-pentafluorophenyl)ethane-1,2-diaminato(1-)](2,4,6-trimethylbenzoato)(pyridine)platinum(II) (TMB) were compared with cisplatin through their reaction with DNA. Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy was applied to analyse the interaction of the Pt(II) complexes with DNA in the hydrated, dehydrated and rehydrated state. These were compared with control DNA in acetone/water (PFB, TMB) and isotonic saline (cisplatin) under the same conditions. Principle Component Analysis (PCA) was applied to compare the ATR-FTIR spectra of the untreated control DNA with spectra of PFB and TMB treated DNA samples. Disruptions in the conformation of DNA treated with the Pt(II) complexes upon rehydration were mainly observed by monitoring the position of the IR-band around 1711 cm-1 assigned to the DNA base-stacking vibration. Furthermore, other intensity changes in the phosphodiester bands of DNA at ~1234 cm-1 and 1225 cm-1 and shifts in the dianionic phosphodiester vibration at 966 cm-1 were observed. The isolated double stranded DNA (dsDNA) or single stranded DNA (ssDNA) showed different structural changes when incubated with the studied compounds. PCA confirmed PFB had the most dramatic effect by denaturing both dsDNA and ssDNA. Both compounds, along with cisplatin, induced changes in DNA bands at 1711, 1088, 1051 and 966 cm-1 indicative of DNA conformation changes. The ability to monitor conformational change with infrared spectroscopy paves the way for a sensor to screen for new anticancer therapeutic agents.
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Chemistry, Food Chemistry; craft beer; polyphenols; bitterness; preference; sensory attributes
Online: 18 October 2018 (05:09:01 CEST)
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The craft beers are outlined as a distinctively flavored, brewed and distributed regionally, using top-fermenting (ale) yeast, bottom-fermenting (lager) yeast or spontaneously fermentation. Craft beers are largely consumed and produced in Brazil and presents great level of polyphenols, which would affect the consumer’s preference. In this way, we analyzed the relation between polyphenols, bitterness and composition of main different styles of craft beers and the consumer´s preference. Six different styles were analyzed according its polyphenol content, bitterness, chemical composition, sensory profile and preference. For preference, a panel with 62 non-trained assessors was used. For sensory profile, the quantitative descriptive analysis was performed, using expert assessors (n = 8). The preferred style was Classic American Pilsner and the style less preferred was Standard American Lager. The craft beer more preferred showed a decreased bitterness (9.52), polyphenol content (0.61 mg EAG/mL), total solids (6.75 ºBrix) and turbidity (7.27 NTU). This beer exhibited reduced sensory notes of malty, fruity, smoked, hoppy and phenolic, but a higher perception of floral, sweet and yeast notes. The bitter attribute has a reduced perception. This study advances understanding the sensory profile and complexity of craft beers styles from Southern Brazilian.
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Chemistry, Electrochemistry; sodium rechargeable battery; polymer electrolyte; Nafion; cycle stability; electrochemical stability
Online: 18 October 2018 (04:16:01 CEST)
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The possibilities of manufacturing batteries with Nafion 117 membranes in the Na+-form intercalated by mixtures of non-aqueous organic solvents used both as electrolyte, separator and binder were investigated. Electrochemical stability of various organic solvent mixtures based on N,N-dimethylacetamide, ethylene carbonate, propylene carbonate, tetrahydrofuran was characterized. It was shown that sodium battery based on Nafion-Na membrane intercalated by mixture of ethylene carbonate ‑ propylene carbonate with Na3V1.9Fe0.1(PO4)3/C positive electrode is characterized by a discharge capacity of ca. 110 mAh g-1 (C/10) at room temperature and shows the ability to cycle for a long time. Batteries with Nafion membrane electrolytes, containing N,N-dimethylacetamide were characterized by capacity fading during cycling, which is due to the interaction of N,N-dimethylacetamide and a negative sodium electrode.
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Chemistry, Medicinal Chemistry; Biginelli reaction; dihydropyrimidin-2-thiones; synthesis, virtual screening, drug design; LaSOM 282
Online: 17 October 2018 (09:34:06 CEST)
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The Biginelli reaction is a highly versatile reaction, which leads to dihydropyrimidinones/thiones. This scaffold is reported as being a privileged structure due to its ability to interact with biological targets. Synthesis of ethyl 4-(2-fluorophenyl)-6-methyl-2-thioxo-1-(p-tolyl)-1,2,3,4-tetrahydropyrimidine-5-carboxylate was achieved through the Biginelli reaction using a functionalized thiourea. In silico studies demonstrated that the compound title showed good potential for interacting with ecto-5’-nucleotidase, which has been considered as a target in designs for anti-cancer drugs.
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Chemistry, Medicinal Chemistry; endophytic fungi; sesterterpene; cytotoxic activity; pancreatic cancer
Online: 17 October 2018 (06:39:51 CEST)
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As a part of our ongoing research on endophytic fungi, we have isolated a sesterterpene mycotoxin, fusaproliferin (FUS), from Fusarium solani strain associated with the plant Aglaonema hookerianum Schott. FUS showed rapid and sub-micromolar IC50 against pancreatic cancer cell lines. Time dependent survival analysis and microscopy imaging showed rapid morphological changes in cancer cell lines 4 hours after incubation with FUS. This provides a new chemical scaffold that can be further developed to obtain more potent synthetic agents against pancreatic cancer.
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Chemistry, Medicinal Chemistry; Molecular Dynamics, CoSolvent Molecular Dynamics, Drug design, Fragment Screening, Docking
Online: 16 October 2018 (12:15:17 CEST)
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Molecular dynamics(MD) simulations are playing an increasingly important role in structure-based drug discovery (SBDD). Here we review the use of MD for proteins in aqueous solvation, organic/aqueous mixed solvents (MDmix) and with small ligands, to the classic SBDD problems: binding mode and binding free energy predictions. The simulation of proteins in their condensed state reveals the solvent structure and preferential interaction sites (hot spots) on the protein surface. This information is largely transferable across all classes of protein ligands (from water to drugs) and can be used very effectively to understand ligand recognition and improve the predictive capability of well-established methods such as molecular docking. MD simulations for protein and drug or drug-like compounds are now being used but are still computationally expensive and can only be applied to specific cases. On the other hand, MDmix simulations can now be used in SBDD and we will describe the latest developments and implementations. We expect to see an increase in the application of these techniques to a plethora of protein targets to identify new drug candidates with the advent of new tools and faster computers.
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Chemistry, Medicinal Chemistry; assay; diarrhea; isolate; hydrolysis; proteins; inhibition zone
Online: 16 October 2018 (11:26:59 CEST)
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The study compared antibacterial potential of hydrolysates of casein and alpha-lactalbumin from cow and goat milk on diarrhea-causing Escherichia coli and Staphylococcus aureus. Milk samples were aseptically obtained from lactating cows and goats. The samples were skimmed; casein was isolated using acetic acid and alpha-lactalbumin by filtrate thermoprecipitation at 75 °C. 50% of each isolate was reconstituted in a buffer and hydrolyzed with papain at 55 °C for 2 hours. The hydrolysates were heated to 75 °C to inactivate papain, cooled and their antibacterial activity determined by disc diffusion method. Results showed alpha-lactalbumins had higher degrees of hydrolysis and antibacterial activity than caseins; goat alpha-lactalbumin had the highest antibacterial activity with mean inhibition zones of 19.60 mm and 19.50 mm on E. coli and S. aureus. Cow alpha-lactalbumin inhibited E. coli more than S. aureus with inhibition zones of 16.80 mm and 12.50 mm. Cow and goat milk casein hydrolysates inhibited E. coli with mean inhibition zones of 8.00 mm and 10.90 mm and inhibited S. aureus with inhibition zones of 4.13 mm and 1.90 mm respectively. The research showed that the milk hydrolysates can be a source of antibiotics for diarrhea treatment. Research should be done to establish the peptide fractions associated with the observed bioactivity.
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Chemistry, Organic Chemistry; Ionic liquid; synergistic activation; aminoethanol; 2-oxazolidinone; atmospheric CO2; sustainable catalysis
Online: 16 October 2018 (10:48:43 CEST)
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To circumvent the thermodynamic limitation of the synthesis of oxazolidinones starting from 2-aminoethanols and CO2 and realize incorporation CO2 under atmospheric pressure, a protic ionic liquid-facilitated three-component reaction of propargyl alcohols, CO2 and 2-aminoethanols was developed to produce 2-oxazolidinones along with equal amount of α-hydroxyl ketones. The ionic liquid structure, reaction temperature and reaction time were in detail investigated. And 15 mol% [TBDH][TFE] (1,5,7-triazabicylo[4.4.0]dec-5-ene trifluoroethanol) was found to be able to synergistically activate the substrate and CO2, thus catalyzing this cascade reaction under atmospheric CO2 pressure. By employing this task-specific ionic liquid as sustainable catalyst, 2-aminoethanols with different substituents were successfully transformed to 2-oxazolidinones with moderate to excellent yield after 12 h at 80 oC. This three-component reaction running under atmospheric pressure proves to be a clever detour to avoid the thermodynamic issue in the synthesis of 2-oxazolidinones starting from 2-aminoethanols and CO2.
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Andrea LA Wong,
Xiaoqiang Xiang,
Pei Shi Ong,
Qin Ying Mitchell Ee,
Nicholas Syn,
Wee Ian,
Alan Prem Kumar,
Wei Peng Yong,
Gautam Sethi,
Boon Cher Goh,
Paul Chi-Lui Ho,
Lingzhi Wang
Chemistry, Analytical Chemistry; LC-MS/MS, Rapid, Quantification, Oncology Drugs
Online: 15 October 2018 (16:57:44 CEST)
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In the last decade, the tremendous improvement in the sensitivity and also affordability of Liquid Chromatography-tandem Mass Spectrometry (LC-MS/MS) have revolutionized its application in pharmaceutical analysis, resulting in wide-spread of employing LC-MS/MS for determining pharmaceutical compounds including anticancer drugs in pharmaceutical research and also industries. Currently, LC-MS/MS has been widely used to quantify small molecule oncology drugs in various biological matrices to support preclinical and clinical Pharmacokinetic studies in R & D of oncology drugs. This mini-review article will describe the state-of-the art LC-MS/MS and its application in rapid quantification of small molecule anticancer drugs. In addition, efforts have also been made in this review to address several key aspects in the development of rapid LC-MS/MS methods, including sample preparation, chromatographic separation and matrix effect evaluation.
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Chemistry, Organic Chemistry; Controlled Polymerization; Reversible Polymerization; Sustainable Polymers
Online: 15 October 2018 (16:19:19 CEST)
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The field of controlled polymerization is growing and evolving at unprecedented rates, facilitating polymer scientists to engineer the structure and property of polymer materials for a variety of applications. However, the lack of degradability, particularly in vinyl polymers, is a general concern for not only environmental sustainability but also biomedical applications. In recent years, there has been a significant effort to develop reversible polymerization approaches in those well-established controlled polymerization systems. Reversible polymerization typically involves two steps including (i) forward polymerization which converts small monomers into macromolecules, and (ii) depolymerization capable of regenerating original monomers. Furthermore, recycled monomers can be repolymerized into new polymers. In this perspective, we highlight recent developments of reversible polymerization in those controlled polymerization systems and offer insight into the promise and utility of reversible polymerization systems. More importantly, the current challenges and future directions to solve those problems are discussed. We hope this perspective can serve as an “initiator” to promote continuing innovations in this fairly new area.
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Chemistry, Organic Chemistry; cyclic nucleotide monophosphate; bio-reversible protection; acyloxybenzyl phosphate ester
Online: 12 October 2018 (11:32:45 CEST)
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Adenine nucleotide (AN) 2nd messengers such as 3’,5’-cyclic adenosine monophosphate (cAMP) are central elements of intracellular signaling, but many details of underlying processes remain still elusive. Like all nucleotides, cyclic nucleotide monophosphates (cNMPs) are net-negatively charged at physiologic pH which limits their applicability in cell-based settings. Thus, many cellular assays rely on sophisticated techniques like microinjection or electroporation. This setup is not feasible for medium- to high-throughput formats, and the mechanic stress that cells are exposed to raises the probability of interfering artefacts or false-positives. Here, we present a short and flexible chemical route yielding membrane-permeable, bio-reversibly masked cNMPs for which we employed the octanoyloxybenzyl (OB) group. We further show hydrolysis studies on chemical stability and enzymatic activation, and present results of real-time assays, where we used cAMP and Ca2+ live cell imaging to demonstrate high permeability and prompt intracellular conversion of some selected masked cNMPs. Consequently, our novel OB-masked cNMPs constitute valuable precursor-tools for non-invasive studies on intracellular signaling.
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Chemistry, Organic Chemistry; palladium oxide; bentonite; Friedel-Craft; acetophenone; catalyst
Online: 12 October 2018 (03:32:54 CEST)
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Catalyst material plays a pivotal role in the pharmaceutical industry process. Among them, Friedel-Craft acylation reaction is a well-known reaction to synthesis acetophenone derivatives. However, Friedel-Craft acylation mostly used acetyl chloride as starting material with Lewis acid as homogeneous catalyst, which is nonenvironmental friendly process. In this work, a simple and efficient Friedel-Craft acylation reaction is reported by using the palladium oxide doped on activated bentonite (PdOAB) as the heterogeneous catalyst. The PdOAB catalyst material was characterized with scanning electron microscopy-energy dispersive X-ray (SEM-EDX), nitrogen isotherm adsorption, Fourier transform infrared (FTIR), X-ray powder diffraction (XRD), and thermogravimetric-differential thermal analysis (TG-DTA). The acetophenone derivatives with R = -H, -Cl, -CH3, -OCH3, -OH and -NH2 at para position were successfully synthesized from its corresponding aromatic compounds with glacial acetic acid in 86.6, 7.9, 91.7, 86.6, 82.7, and 78.9% yield, respectively. Therefore, a green method was established because the byproduct is water and the catalyst material can be recovered. Furthermore, the substituent (σ) constants were obtained by using Hammet equation, and the catalysis mechanism has been proposed.
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Chemistry, Applied Chemistry; thin films; WO3; photocatalysis
Online: 11 October 2018 (04:10:57 CEST)
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Highly macroporous thin films of WO3 were fabricated on transparent conductive substrates by application of a polymeric organic paste loaded with an amine/tungstate complex. After spin-coating and annealing at 550oC, the resulting yellow films are found to be comprised of channeled array of clustered nanoparticles. These channels are confirmed by scanning electron microscopy to extend through the entire length of the coating. The high porosity of the material enables the insertion of a co-catalyst into the internal structure of the film. These internally functionalized composites demonstrate good photosensitivity and stability in neutral electrolyte.
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Chemistry, Food Chemistry; pounded yam; cocoyam; machine; panelist; texture; Yorubas; Nigeria
Online: 10 October 2018 (03:38:37 CEST)
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Pounded yam eaten with any type of soup is a delicacy eaten by Nigerians. It is manually prepared by pounding yam, cocoyam or combination with mortar and pestle. Preparation takes 30-45 mins. Researches on the improvements have taken place to reduce the heavy burden on the pounded yam preparation. One of the efforts made is the fabrication of pounding machine from the Department of Engineering, Federal College of Agriculture, Akure, Nigeria. The aim of this study is to carry out the organoleptic analysis of pounded yam produced from the fabricated machine. A ten-man panelist was used to determine the organoleptic analysis of the pounded yam in terms of the appearance, taste, colour, odour and texture. The panelists were scored with a class of quality grading: 22.6-25.0 (excellent), 20.2-22.5 (good), 18.2-20.1 (satisfactory), 16.2-18.1 (less satisfactory), and <15.2 (unsatisfactory). Also, sensory attributes were scored as 1= unsatisfactory, 2= less satisfactory, 3= satisfactory, 4=good, and 5= excellent. The results were statistically analysed. From the results it was found that the mean results of appearance, colour, odour, taste, and texture were 4.55, 4.43, 4.15, 4.32, and 4.08 respectively. Coefficients of variation (%) were 16.89, 17.80, 21.65, 15.67, and 24.40. The Skewness of the parameters was in negative, while only odour has its Kurtosis in negative form (-0.37). All the panelists rated the appearance (19-24%) of all the samples high above all other parameters. The Pearson Coefficient of Correlation and Principal Component Analysis showed elements of relationships between the parameters. In conclusion, the machine pounded yam was scored above satisfactory, which means the fabricated machine was efficient.
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Chemistry, Physical Chemistry; Biomarkers, Dye , Fluorescence, acetate detection, FLIM
Online: 9 October 2018 (15:39:16 CEST)
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Development of biomarkers of analytes with interest in clinic is an important field of study. In this work, we synthesized and analyzed the new fluorescent acetate-biomarker, Iso-PG. The mechanism of detection is the acetate buffer mediated proton transfer reaction. The rate constants involved were obtained, and we measured the change in the fluorescence lifetime produced as a consequence of the presence of acetate in the medium. Finally, we checked its potential use as acetate biomarker in synthetic serum
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Chemistry, Other; Mars; minerals; biomarkers; catalysis; preservation; ionizing radiations
Online: 9 October 2018 (10:01:26 CEST)
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Minerals might have played critical roles for the origin and evolution of possible life forms on Mars. The study of the interactions between “building blocks of life” and minerals relevant to Mars mineralogy under conditions mimicking the harsh Martian environment may provide key insight into possible prebiotic processes. Therefore, this contribution aims at reviewing the most important investigations carried out so far about the catalytic/protective properties of Martian minerals toward molecular biosignatures under Martian-like conditions. Overall, it turns out that the fate of molecular biosignatures on Mars depends on a delicate balance between multiple preservation and degradation mechanisms often regulated by minerals, which may take place simultaneously. Such a complexity requires more efforts in simulating realistically the Martian environment in order to better inspect plausible prebiotic pathways and shed light on the nature of the organic compounds detected both in meteorites and on the surface of Mars through in situ analysis.
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Chemistry, Analytical Chemistry; biosensors; enzyme-based systems; receptor-based systems; toxins; food analysis; environmental monitoring; nanotechnology
Online: 9 October 2018 (05:59:30 CEST)
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The exploitation of lipid membranes in biosensors has provided the ability to reconstitute a considerable part of their functionality to detect trace of food toxicants and environmental pollutants. Nanotechnology enabled sensor miniaturization and extended the range of biological moieties that could be immobilized within a lipid bilayer device. This chapter reviews recent progress in biosensor technologies based on lipid membranes suitable for environmental applications and food quality monitoring. Numerous biosensing applications are presented, putting emphasis on novel systems, new sensing techniques and nanotechnology-based transduction schemes. The range of analytes that can be currently detected include, insecticides, pesticides, herbicides, metals, toxins, antibiotics, microorganisms, hormones, dioxins, etc. Technology limitations and future prospects are discussed, focused on the evaluation/ validation and eventually commercialization of the proposed sensors.
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Chemistry, Applied Chemistry; phytosterols; mesocarp; oilseed; maturity; pod-blast; α-tocopherol; oil bodies; campesterol; stigmasterol; β-sitosterol
Online: 9 October 2018 (04:02:35 CEST)
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The seeds of cultivated peanut, Arachis hypogaea, are an agronomically important crop produced for human nutrition, oilseed and feed stock. Peanut seed is the single most expensive variable input cost and thus producers require seed with excellence performance in terms of germination efficiency. During the maturation process, triglycerides are stored in oil bodies as an energy resource during germination and seedling development. The stability of oil body membranes is essential for nutrient mobilization during germination. This study focused on evaluating the phytosterol composition in seed components including the kernel, embryo (heart), and seed coat or skin. Samples of different maturity classes were analyzed for macronutrient and phytosterol content. The three most abundant phytosterols, β-sitosterol, campesterol, and stigmasterol, comprised 82.29%, 86.39%, and 94.25% of seed hearts, kernels, and seed coats, respectively. Stigmasterol concentration was highest in the seed kernel providing an excellent source of this sterol known to have beneficial effects on human health. Peanut hearts contained the highest concentration of sterols by mass potentially providing protection and resources for the developing seedling. The amount of α-tocopherol increases in peanut hearts during the maturation process providing protection from temperature stress and stability required for seedling vigor. These results suggest that phytosterols may play a significant role in the performance of seeds and provides a possible explanation for the poor germination efficiency of immature seeds.
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Chemistry, Other; Antitumoral activity; platinum; N-heterocyclic carbene; polyethyleneimine.
Online: 8 October 2018 (16:05:07 CEST)
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The high interest in N-heterocyclic platinum carbene complexes in cancer research stems from their high cytotoxicity to human cancer cells, their stability, as well as their ease of functionalization. However, the development of these new molecules as anticancer agents still faces multiple challenges, in particular solubility in aqueous media. Here, we synthesized platinum-NHC bioconjugates that combine water-solubility and cytotoxicity by using polyethyleneimine as polymer carrier. We showed that the activity of these conjugates is modulated by the size of the polymer and the overall density of metal ions onto polymer chains. They displayed an effective activity after only 45 minutes of exposure in vitro correlated with a quick uptake by the cells as shown by the use of various fluorescent-tagged derivatives.
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Chemistry, Analytical Chemistry; recycled diatomaceous earth; solid phase microextraction; polycyclic aromatic hydrocarbons; gas chromatography-mass spectrometry
Online: 8 October 2018 (15:54:40 CEST)
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In this study, the use of recycled diatomaceous earth as the extraction phase in a the solid phase microextraction (SPME) technique for the determination of polycyclic aromatic hydrocarbons (PAHs) in river water samples, with separation/detection performed by gas chromatography-mass spectrometry (GC-MS), is proposed. The optimized extraction conditions are extraction time 70 min at 80 ºC with no addition of salt. The limits of quantification were close to 0.5 μg L-1 with RSD values lower than 25% (n = 3). The linear working range was 0.5 μg L-1 to 25 μg L-1 for all analytes. The method was applied to samples collected from the Itajaí River (Santa Catarina, Brazil) and the RSD values for repeatability and reproducibility were lower than 15% and 17%, respectively. The efficiency of the recycled diatomaceous earth fiber was compared with that of commercial fibers and good results were obtained, confirming that this is a promising option for use as the extraction phase in SPME.
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Chemistry, Analytical Chemistry; Chirality; Chiroptical Responses; Exciton Chirality; Selection Rules; Symmetry.
Online: 8 October 2018 (15:37:56 CEST)
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The high sensitivity of chiroptical responses to conformational changes and supramolecular interactions has prompted an increasing interest in the development of chiroptical applications. However, prediction and understanding the chiroptical responses of the necessary large systems may not be affordable for calculations at high levels of theory. In order to facilitate the development of chiroptical applications, methodologies capable of evaluating the chiroptical responses of large systems are necessary. Exciton chirality method has been extensively used for the interaction between two independent chromophores through the Davydov model. For systems presenting C2 or D2 symmetry one can get to the same results by applying the selection rules. In the present article, analysis of the selection rules for systems with symmetries Cn and Dn with n = 3 and 4 is used to uncover the origin of their chiroptical responses. We hope that the use of the chiroptical symmetry analysis (CSA) for systems presenting the symmetries explored herein as well as for systems presenting higher symmetries will serve as a useful tool for the development of chiroptical applications.
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Chemistry, Physical Chemistry; anoxic iron oxidation; abiogenic ferric iron; high-subcritical water; alkaline; ferric oxides; ferric silicates; amorphous silica; origin of life; fluid inclusions; geobiotropy
Online: 8 October 2018 (10:42:53 CEST)
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The expression "Follow the water" is used in order to recognize inside the universe, life as it exists on Earth. It is shown here that the expression "Follow the water in its high-subcritical state" can be used in order to recognize the components of life which form prior to the emergence of life. This specific state of water leaves signatures inside the minerals which are produced during high-subcritical water/rock interaction.
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Chemistry, Organic Chemistry; amide resonance; anomeric effect; HERON reaction; pyramidal amides; physical organic chemistry; reaction mechanism
Online: 8 October 2018 (05:45:12 CEST)
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This review describes how resonance in amides is greatly affected upon substitution at nitrogen by two electronegative atoms. Nitrogen becomes strongly pyramidal and resonance stabilisation, evaluated computationally, can be reduced to as little as 50% that of N,N-dimethylacetamide. However, this occurs without significant twisting about the amide bond, which is borne out both experimentally and theoretically. In certain configurations, reduced resonance and pronounced anomeric effects between heteroatom substituents are instrumental in driving the HERON (Heteroatom Rearrangement On Nitrogen)† reaction, in which the more electronegative atom migrates from nitrogen to the carbonyl carbon in concert with heterolysis of the amide bond, to generate acyl derivatives and heteroatom-substituted nitrenes. In other cases the anomeric effect facilitates SN1 and SN2 reactivity at the amide nitrogen.
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Chemistry, Food Chemistry; Sea Squirts; Metabolites; GC-MS; Anti-bacterial; Zika vector; larvicidal
Online: 6 October 2018 (11:18:31 CEST)
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In this present study, we conducted untargeted metabolic profiling using Gas Chromatography-Mass Spectrometry (GC-MS) analysis of ascidian Didemnum bistratum to assess the chemical constituents by searching in NIST library with promising biological properties against anti-bacterial and Zika virus vector mosquitocidal Properties. Metabolites, steroids and fatty acids are abundant in crude compounds of ascidian D. bistratum and showed potential zone growth inhibition against bacterial strains Kluyvera ascorbate (10 mm). The active crude compounds of D. bistratum exhibited prominent larvicidal activity against the Zika vector mosquitoes of Aedes aegypti and Cluex quinquefasciatus (LC50 values of 0.4436 to 2.23 mg/mL). The findings of this study provide a first evidence of the biological properties exhibited by D. bistratum extracts, thus increasing the knowledge about the Zika virus vector mosquitocidal properties of ascidian. Overall, ascidian D. bistratum are promising and biocontrol or eco-friendly tool against A. aegypti and C. quinquefasciatus with prospective toxicity against non-target organisms.
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Chemistry, Chemical Engineering; gallium nitride; gallium; LED waste; LED recycling; leaching
Online: 3 October 2018 (17:16:07 CEST)
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In recent years, with the increasing research and development of the LED industry which contains GaN, it is expected that there will be a large amount of related wastes in the future. Especially the gallium has extremely high value of economic, therefore, it is necessary to establish the recycling system of the GaN waste. However, GaN is a direct-gap semiconductor and with high energy gap, high hardness, and high melting point make it difficult to recycle. Therefore, this study will analyze the physical characteristics of LED wastes containing GaN and carry out various leaching method to leach the valuable metals from the waste optimally. Different acids are used to find out the best reagent for leaching the gallium. Different experimental parameters are discussed such as the effect of the different acid agents , concentration, pressure, solid-liquid mass ratio, temperature, and time which influence the leaching efficiency of the gallium. In this study, various leaching methods which effect the leaching efficiency of the gallium are compared and the advantages and disadvantages are discussed. Finally, pressurized acid leaching method is preferred to leach the GaN waste, and hydrochloric acid is used as the leaching solution because of its better leaching efficiency of gallium. Eventually, the leaching efficiency of the gallium can reach to 98%.
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Chemistry, Inorganic & Nuclear Chemistry; lithium titanium oxide; mechanochemistry; high energy ball milling; X-ray diffraction; Rietveld refinement; 6Li SPE MAS NMR; impedance spectroscopy
Online: 1 October 2018 (14:20:29 CEST)
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Lithium titanates are used in various applications, such as anode materials for lithium intercalation (Li4Ti5O12) or breeding materials in fusion reactors (Li2TiO3). Here, we report the formation of nano-crystalline lithium titanates by a mechanochemical approach and present a deeper insight into their structural characteristics by PXRD and solid-state NMR spectroscopy. The compounds were synthesized in a high energy planetary ball mill with varying milling parameters and different grinding tools. NaCl type Li2TiO3 (α-Li2TiO3) was formed by dry milling of lithium hydroxide with titania (rutile or anatase) and by a milling induced structure transformation of monoclinic β Li2TiO3 or spinel type Li4Ti5O12. Heating of mechanochemical prepared α Li2TiO3 induces a phase transformation to the monoclinic phase similar to hydrothermal reaction products, but a higher thermal stability was observed for the mechanochemical formed product. Microstructure and crystallographic structure were characterized by PXRD via Rietveld analysis. Detailed phase analysis shows the formation of the cubic phase from the various educts. A set of two lattice parameters for α Li2TiO3 was refined, depending on the presence of OH- during the milling process. An average crystallite size of less than 15 nm was observed for the mechanochemical generated products. The local Li environment detected by 6Li SPE MAS NMR revealed Li defects in the form of tetrahedral instead of octahedral site occupation. Subsequent adjustment of the structural model for Rietveld refinement leads to better fits, supporting this interpretation.
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Chemistry, Applied Chemistry; Roasted Fish Skin, PAHs mutagenicity risk, Limonene
Online: 30 September 2018 (10:03:24 CEST)
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Traditional edible barbecue products use with lemon juice not only make the barbecue more delicious but also reduce the risk of PAHs in the barbecue products. One of the major economics crops in Taiwan, the waste from citrus fruits was very tremendous mass. However, the peelings of citrus fruits are rich in essential oil, especially, the limonene is the major. Whether the anti-carcinogenesis activities of terpene, such as limonene, in citrus fruits essential oil extraction. This study to demonstrate the PAHs content in fish skin increased markedly after being roasted at 210℃ for 20 minutes and greater mutagenicity risk of roasted fish skin was observed by Ame's test. The reduction of mutagenicity risk of roasted fish skin, which the antimutagenic abilities of substances in descending order were limonene > cold pressure oil > lemon >grapefruit. The antimutagenicity rate and ability of the three extracts were limonene: 18–23%; cold-pressed lemon oil: 18–22%; and steam distilled lemon essential oil: 8–16%. The obvious anti- mutagenicity effects against the PAHs mutagenicity of roasted fish skins can be found in citrus fruits essential oil extraction.
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Chemistry, Chemical Engineering; melanin like nanoparticles; sodium periodate; enzymatic activity; layer-by-layer films
Online: 29 September 2018 (04:16:12 CEST)
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Polydopamine (PDA) deposition, obtained from the oxidation of dopamine and other catecholamines is an universal way to coat all known materials with a conformal coating which can subsequently be functionalyzed at will. The structural analogies between polydopamine and eumelanin, the black-brown pigment of the skin, incited to produce stable polydopamine nanoparticles in solution instead of amorphous precipitates obtained from the oxidation of dopamine. Herein, we demonstrate that size controlled and colloidally stable PDA based nanoparticles can be obtained in acidic conditions, where spontaneous auto-oxidation of dopamine is suppressed, using sodium periodate as the oxidant and a protein like alkaline phosphatase as a templating agent. The size of the
[email protected] nanoparticles depends on the dopamine/enzyme ratio and the obtained particles display the enzymatic activity of alkaline phosphatase with an activity extending up to two weeks after particle synthesis. The
[email protected] alkaline phosphatase (Alp) nanoparticles can be engineered in polyelectrolyte multilayered films to potentially design model biosensors.
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Chemistry, Organic Chemistry; essential oils; VOCs; GC-MS SPME; electronic nose; nanowire gas sensors; ANOVA.
Online: 28 September 2018 (13:22:44 CEST)
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Essential oils are mixtures of compounds obtained from plants, including flowers, roots, bark, leaves, seeds,peel, fruits, wood, that have risen up in the last decades thanks to their beneficial properties as antibacterial, antifungal and anti-inflammatory agents. The aim of this study was to characterize and analyze 13 different commercial essential oils with two different techniques. The first is GC-MS, coupled with SPME, thanks to which 204 different VOCs have been identified. The results show that a total of 95 compounds was found only in one oil, while the others were found with different frequencies in many of them. The most represented class is that of terpenes, as widely reported in literature. The second technique is based on an array of chemical gas sensors. This system was used to investigate whether sensors are able to identify these products. It turned out that basil, cinnamon and carnation are the most identifiable oils with different number and typology of sensors, especially tin oxide and copper oxide nanowires, while cayeput and thyme are more mistakable samples. Thanks to this detailed study, it has been possible to reach and obtain novel insights for the future development of this type of research.
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Chemistry, Medicinal Chemistry; Pritimerin; target fishing; druggability; network pharmacology
Online: 28 September 2018 (11:54:58 CEST)
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Pristimerin (PM) is a naturally occurring quinonemethide triterpenoid compound that isolated from the Celastraceae and Hippocrateaceae families. Its anticancer effects have attracted a great deal of attention, but the mechanisms of action remain obscure. In this study, we screened for the active compounds of Pristimerin using a drug-likeness approach. Potential protein targets of Pristimerin were predicted by PharmMapper and Coremine database. Candidate protein targets were then uploaded to GeneMANIA and GO pathway analysis. Finally, compound-target, target-pathway, and compound-target-pathway networks were constructed using Cytoscape 3.3. The results showed that Pristimerin had good drug ability and identified 13 putative protein targets. Network analysis revealed that these targets are associated with cancer, inflammation and other physiological processes. In summary, Pristimerin is predicted to target a variety of proteins and pathways to form a network that exerts systemic pharmacological effects.
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Chemistry, Analytical Chemistry; screen-printed electrode; Sb-film electrode; SPE; SbFE; stripping analysis; EIS
Online: 28 September 2018 (06:18:11 CEST)
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In this work, unmodified screen-printed electrode (bare SPE) and Sb-film modified SPE (SbFSPE) sensors were employed for the analysis of trace amounts of Pb(II) in non-deaerated water solutions. The modified electrode was performed in situ in 0.5 mg/L Sb(III) and 0.01 M HCl. The methodology was validated for an accumulation potential of –1.1 V vs. Ag/AgCl and an accumulation time of 60 s. A comparative analysis of bare SPE and SbFSPE showed that the detection and quantification limits decrease for the bare SPE. The method with the bare SPE showed a linear response in the 69.8–368.4 µg/L concentration range, whereas linearity for the SbFSPE was in the 24.0–319.1 µg/L concentration range. This work also reports the reason why the multiple standard addition method instead of a linear calibration curve for Pb(II) analysis should be employed. Furthermore, the analytical method employing SbFSPE was found to be more accurate and precise compared to the use of bare SPE when sensors were employed for the first time, however this performance changed significantly when these sensors were reused in the same manner. Furthermore, electrochemical impedance spectroscopy was used for the first time to analyse the electrochemical response of sensors after being used for multiple successive analyses. Surface characterisation before and after multiple successive uses of bare SPE and SbFSPE sensors, with atomic force microscopy and field emission scanning electron microscopy, showed sensor degradation. The interference effect of Cd(II), Zn(II), As(III), Fe(II), Na(I), K(I), Ca(II), Mg(II), NO3– Bi(III), Cu(II), Sn(II), and Hg(II) on the Pb(II) stripping signal was also studied. Finally, the application of SbFSPE was tested on a real water sample (from a local river), which showed high precision (RSD = 8.1%, n = 5) and accurate results.
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Chemistry, Applied Chemistry; Colliguaya integerrima; Colliguaja salicifolia; vegetable oil; bio-polyol; renewable resources
Online: 28 September 2018 (04:44:48 CEST)
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In this study we investigated the potential of two non-edible oil extracts from seeds of Colliguaya Integerrima (CIO) and Colliguaja Salicifolia (CSO) to use as a renewable source for polyols and eventually polyurethane foams or biodiesel. For this purpose, two novel polyols from the aforementioned oils were obtained in a one-single step reaction using a mixture of hydrogen peroxide and acetic acid. The polyol derivatives obtained from the two studied oils were characterized by spectral (FT-IR, 1H NMR and 13C NMR), physico-chemical (e.g. chromatographic analysis, acid value, oxidizability values, iodine value, peroxide value, saponification number, kinematic viscosity, theorical molecular weights, density, hydroxyl number and hydroxyl functionality) and thermal (TGA) analyses according to standard methods. Physico-chemical results revealed that all parameters, with the exception of the iodine value, were higher for bio-polyols (CSP and CIP polyols) compared to the starting oils. The NMR, TGA and FT-IR analyses demonstrated the formation of polyols. Finally, the OH functionality values for CIP and CSP polyols were 4.50 and 5.00, respectively. This result indicated the possible used of CIP and CSP polyols as a raw material for the preparation of polyurethane rigid foams.
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Chemistry, Physical Chemistry; ice X; vibrational spectrum; first-principles DFT; Raman scattering; IR absorption
Online: 27 September 2018 (13:25:06 CEST)
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A typical vibrational spectrum in the ice phase has four separate bands: translation, libration, bending and stretching. Ice X, the final ice phase under high pressure, shows an exotic vibrational spectrum. Theoretically, an ideal crystal of ice X only has one peak at 998 cm-1 for Raman scattering and two peaks at 450 cm-1 and 1507 cm-1 for infrared absorption in this work. These three characteristic peaks are indicators of the phase transition between ice VII/VIII and ice X. Despite much experimental and theoretical work on ice X, only this study has clearly indicated these characteristic peaks in the region of the IR band. The phonon density of states shows quite different features than ice VIII, which could be verified by inelastic neutron scattering in the future. The dynamic processes of 15 vibrational normal modes are discussed and the typical hydrogen bonds are missing.
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Chemistry, Electrochemistry; metal doping; nickel-based catalyst; transition metals; synthesis; hydrogen oxidation reaction; exchange current density; alkaline medium; DFT; hydrogen binding energy; hydroxide binding energy
Online: 27 September 2018 (04:59:46 CEST)
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Carbon supported nanoparticles of monometallic Ni catalyst and binary Ni-Transition Metal (Ni-TM/C) electrocatalytic composites were synthesized via chemical reduction method, where TM stands for the doping elements Fe, Co, and Cu. The chemical composition, structure and morphology of the Ni-TM/C materials were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffractometry (XRD), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy (EDS). The electrochemical properties towards hydrogen oxidation reaction in alkaline medium were studied using the rotating disc electrode and cycling voltammetry methods. A significant role of the TM dopant in the promotion of the hydrogen electrooxidation kinetics of the binary Ni-TM/C materials were revealed. A record-high in exchange current density value of 0.060 mA cm2Ni was measured for Ni3Fe1/C, whereas the monometallic Ni/C counterpart has only shown 0.039 mA cm2Ni. In order to predict the feasibility of the electrocatalysts for hydrogen chemisorption, density functional theory was applied to calculate the hydrogen binding energy and hydroxide binding energy values for bare Ni and Ni3TM1.
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Chemistry, Chemical Engineering; adsorption; lead; biocomposite; alginate; Ficus carica L.
Online: 27 September 2018 (04:39:26 CEST)
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In this study, fig leaves, zeolite and alginate were used to prepare a biocomposite for the adsorption of Pb(II) ions from aqueous solutions. Effects of various parameters on the biosorption process such as pH, temperature, initial lead concentration and contact time have been investigated. Maximum uptake of Pb(II) ions (85%) has been achieved at pH 6, with 25 mg/L of initial concentration and at a temperature of 288.15 K. Among the applied models, the data correlated well with Freundlich and D-R models and it was established that the biosorption was physical in nature. The amount of adsorbed lead per gram of sorbent was found to be 150.3 mg/g. Thermodynamic parameters showed the exothermic heat of biosorption and the feasibility of the process. Results have suggested that the prepared biosorbent possesses promising biosorption potential.
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Chemistry, Physical Chemistry; polyoxometalates; hexatantalate; tantalum; countercations; ion-pairing; calorimetry; solubility
Online: 26 September 2018 (05:24:51 CEST)
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Ion association is an important process in aqueous dissolution, precipitation, and~crystallization of ionic inorganic, organic, and biological materials. Polyoxometalates (POMs) are good model compounds for understanding the complex relationships between lattice energy, ion-pairing in solution, and salt solubility. Here we perform calorimetric measurements to elucidate trends in cluster stability, lattice energy, and ion-pairing behavior studies of simple hexatantalate salts in neat water, parent hydroxide solutions, and molybdate melts, extending previous studies on the isostructural hexaniobates. High temperature calorimetry of alkali salts of hexatantalate reveals that the enthalpies of formation from oxides of the K, Rb, and Cs salts are more similar to each other than they are for their niobate analogues and that the tantalate cluster is energetically less stable than hexaniobate. Aqueous dissolution calorimetry reveals that the cesium salt of hexatantalate has a similar concentration dependence on its dissolution enthalpy to that of hexaniobate. However, unlike~rubidium hexaniobate, rubidium hexatantalate also exhibits increased concentration dependence, indicating that hextantalate can undergo increased ion-pairing with alkali salts other than cesium, despite the dilute environments studied. Dissolution enthalpies of POM salts in the parent alkali hydroxides shows that protonation of clusters stabilizes lattices even more than the strongly associating heavy alkali cations do. Additionally, neither weak nor strong lattice ion associations necessarily correlates with respectively high or low aqueous solubility. These studies illuminate the importance of considering ion-pairing among the interrelated processes in the aqueous dissolution of ionic salts that can be extended to serving as a model of cation association to metal oxide surfaces.
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Chemistry, Chemical Engineering; algaecides; dirt; humidity; resilience; temperature; time
Online: 25 September 2018 (03:45:11 CEST)
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Algaecides are chemicals that cause serious health problems. Conventional paints contain algaecides to improve the algae resistance on the paint film. Present research has suggested an environmental friendly paint formulation that focuses on developing algae resistance without having algaecides. In this research, Algae growth on newly developed paint is modeled by incorporating dirt resistance of paint and natural phenomena including humidity, temperature and time respectively. The fitted Model revealed explained variation of 59.65% in the average algae growth, of which, Dirt Resistance, Humidity and temperature and some of their interactions play significant role in this variation. Model suggests that the proposed newly developed paint without algaecides is more resilient to algae growth and significantly decreased the average algae growth rate by 0.53% as compared to conventional paints. Keeping the effect of all other factors constant, if dirt resistance of paint (Dc value) increases by one percent, average algae growth decreases by 12.98%; when temperature increases by 1oC, average algae growth decreases by 22.4%; a positive unit change in the joint linear effect dirt resistance, temperature and humidity caused a decrease in average algae growth by 0.0031%. It was also observed that the individual effect of humidity variable was inversely related with average algae growth. However the combination of humidity and temperature, humidity and dirt resistance, humidity and time, and the quadratic effect of humidity were found to increase the average algae growth rate. The cubic effect of temperature variable by one degree centigrade resulted in decrease of average algae growth by 0.000907%.
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Chemistry, Physical Chemistry; glass transitions, universality, Bell-Evans-Polanyi principle
Online: 24 September 2018 (12:44:06 CEST)
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The Vogel-Fulcher-Tammann equation is exposed as a particular example of the mean field theory. It is generalized by taking into account an arbitrary critical exponent of susceptibility, discriminating between different classes of universality. The Bell-Evans-Polanyi principle is employed to estimate the difference between the activation energies of flows in crystals and glasses, which appears to coincide with the excess Gibbs energy of the glass compared to the crystal.
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Chemistry, Applied Chemistry; ZnO; photo-oxidation; 4-chlorophenol; CuxO-ZnO catalyst; photodeposition
Online: 22 September 2018 (23:38:14 CEST)
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In this work, the solar light-induced redox photoactivity of the ZnO semiconductor material was used to prepare at room temperature CuxO-ZnO composite catalysts with a control of the chemical state of the copper oxide phase. The preparation of Cu2(I)O-ZnO and Cu(II)O-ZnO composite catalysts was achieved by using Cu(acac)2 in THF-water and Cu(NO3)2 in water as metallic precursor, respectively. Prior to the implementation of the photo-assisted synthesis method, the most efficient photoactive ZnO material was selected among different ZnO materials prepared by the low temperature polyol method and through the precipitation method with carbonates and carbamates as precipitation agent, by taking the photocatalytic degradation of the 4-chlorophenol compound in water under simulated solar light as model reaction. The ZnO support materials were characterized by XRD, BET, TGA, SEM and TEM, and the synthesis method was strongly influencing their photoactivity in terms of 4-chlorophenol degradation and of total organic carbon removal. The most photoactive ZnO material was prepared by precipitation with carbonates and calcined at 300°C, and was taking advantage of a high specific surface area and a small mean crystallite size for achieving a complete 4-chlorophenol mineralization within 70 min of reaction, with a minimum Zn2+ released to the solution due to surface photocorrosion. Beside thermal catalysis applications, this work opened a new route for the facile synthesis of Cu2O-ZnO heterojunction photocatalysts, that could take advantage under solar light of the heterojunction built between the p-type semi-conductor Cu2O with direct visible light band gap and the ZnO semiconductor phase.
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Chemistry, Organic Chemistry; biocompatibility; GPC/SEC; keratinocyte cells; NMR; polyurethane; renewable sources
Online: 22 September 2018 (23:23:18 CEST)
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The synthesis of four samples of new polyurethanes was evaluated by changing the ratio of the diol monomers used, poly(propylene glycol) (PPG) and D-isosorbide, in the presence of aliphatic isocyanates such as the isophorone diisocyanate (IPDI) and 4,4′-methylenebis(cyclohexyl isocyanate) (HMDI). The thermal properties of the four polymers obtained were determined by DSC, exhibiting Tg values in the range 55-70 ºC, and their molecular structure characterized by FTIR, 1H and 13C NMR spectroscopies. The diffusion coefficients of these polymers in solution were measured by the Pulse Gradient Spin Echo (PGSE) NMR method, enabling the calculation of the corresponding hydrodynamic radii in diluted solution (1.62–2.65 nm). The molecular weights were determined by GPC/SEC and compared with the values determined by quantitative 13C NMR analysis. Finally, the biocompatibility of the polyurethanes was assessed using the HaCaT keratinocyte cell line by the MTT reduction assay method showing values superior to 70% cell viability.
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Chemistry, Food Chemistry; infrared spectroscopy; diffuse reflectance infrared Fourier transform spectroscopy; ion-exchange resin; drinking water
Online: 21 September 2018 (08:29:11 CEST)
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Infrared spectroscopy is an effective method for the determination of compositions and concentrations of liquids, with advantages of fast response, no-sampling, flexible in use and is able for on-line monitoring. However, for trace substances in drinking water, such as nitrates and heavy metals, infrared spectroscopy is not sensitive enough for the quantitative and qualitative measurement. In this study, we improved the sensitivity of infrared spectroscopy for nitrite determination by developing an ion-exchange-enhanced diffuse reflectance spectroscopy, which consist of an accessory based on ion-exchange resin for enrichment and a FTIR spectrometer for measurement. Using this method, the limit of detection for nitrate is 1.7 mg/L, which is enough for drinking water sensing. We also verified the quantitative measurement ability of the method. Furthermore, the limit of detection and quantitative measuring range could be adjusted by changing the mass of resin and adsorption time. This study demonstrated the method can be used to detect trace nitrites in drinking water, can be applied in the field, and is sensitive, rapid, and inexpensive with a wide dynamic range.
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Chemistry, Food Chemistry; LDL-oxidation; DNA-damage; antioxidant vitamins; oxidative stress
Online: 20 September 2018 (16:53:42 CEST)
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Radical oxygen species formed in human tissue cells by many endogenous and exogenous pathways, cause extensive oxidative damage, which has been linked to various human diseases. This review paper provides an overview of lipid peroxidation and focuses on the free-radicals initiated processes of LDL oxidative modification and DNA oxidative damage, which are widely associated to the initiation and development of atherosclerosis and carcinogenesis, respectively. The article subsequently provides an overview of the recent human trials or even in vitro investigations on the potential of natural antioxidant compounds (such as carotenoids, vitamins C and E) to monitor LDL and DNA oxidative changes.
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Chemistry, Food Chemistry; Sweet cherry; Anthocyanins; Non-coloured phenolics; Antioxidant activity; Erythrocytes protection; Caco-2 cells.
Online: 20 September 2018 (14:23:18 CEST)
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This study aimed to compare three different extracts of Saco sweet cherry, namely non-coloured fraction, coloured fraction and total extract concerning phenolic composition, antioxidant and antidiabetic potential, erythrocytes’ protection and effects on Caco-2 cells. A total of 22 phenolic compounds were identified by LC-DAD. Hydroxycinnamic acids were the most predominant in both non-coloured fraction and total extract, while cyanidin-3-O-rutinoside was the main anthocyanin found in the coloured fraction. The total extract was the most effective against DPPH, nitric oxide and superoxide radicals, and in the inhibition of α-glucosidase enzyme. Finally, the protective effect of the extracts to prevent oxidative damage in human erythrocytes was assessed. The coloured fraction revealed the best activity against hemoglobin oxidation and hemolysis. Regarding to Caco-2 cells, the coloured extract exhibited the most cytotoxic effects, while the total extract was the most efficient in protecting these cells against oxidative damage induced by t-BHP.
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Chemistry, Applied Chemistry; methylene blue; water treatment; magnetic nanomaterials; cryogel; nanocomposites
Online: 20 September 2018 (06:33:48 CEST)
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Inorganic nanoparticles based on magnetite improve the mechanical, thermal, and magnetic properties of microporous cryogel polymer composites. Here we report the synthesis of microporous cryogel based on the crosslinked sodium vinyl sulfonate (Na-VS) and 2-acrylamido-2-methylpropane sulfonic acid sodium salt (Na-AMPS). The magnetite nanoparticles were inserted into Na-VS/Na-AMPS cryogel either during its crosslinking polymerization or by in-situ technique after its crosslinking. The morphology, particle sizes, thermal stability and magnetite contents of Na-VS/Na-AMPS cryogel and its magnetite composites were investigated. The prepared Na-VS/Na-AMPS cryogel and its magnetite composites were used as adsorbents for methylene blue (MB) cationic dye using optimum conditions. The magnetite Na-VS/Na-AMPS cryogel composite prepared by in-situ technique achieved the best adsorption MB removal capacity for 7 cycles among the other adsorbents via chemical adsorption mechanism at room temperature.
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Chemistry, Food Chemistry; menaquinone-7, stability, purity, food supplement
Online: 19 September 2018 (13:59:33 CEST)
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Menaquinone-7 is a member of the vitamin K family whose interest has considerably increased over the last decade due to its beneficial role in human health mainly in respect to bone and cardiovascular health leading to a growing use in different nutritional supplement. Menaquinone-7 can be produced by synthesis or fermentation and its purity profile can differ depending on methodologies and extraction procedures. Finished formulation show a large heterogeneity of purity profiles as well as frequent discrepancies in the nominal content compared to the actual title. In the present study we compared purity profiles of different raw material and we related them to stability assay in normal (12months/25°C/60%RH) and accelerated conditions (6 months/40°C/75% RH) in order to test their performance in presence of different common excipients. Results show that higher purity profile correlates with enhanced stability and this could explain title discrepancies found in finished products found on the market worldwide.
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Chemistry, Other; antibacterial; channel catfish; columnaris disease; Flavobacterium columnare; stilbenes; muscadine; pyranoanthocyanin
Online: 19 September 2018 (08:32:39 CEST)
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Enteric septicemia of catfish, columnaris disease, and streptococcosis, caused by Edwardsiella ictaluri, Flavobacterium columnare, and Streptococcus iniae, respectively, are the most common bacterial diseases of economic significance for the pond-raised channel catfish Ictalurus punctatus industry. Several management practices are used by catfish farmers to prevent large financial losses from these diseases such as the use of commercial antibiotics and other chemicals. In order to discover environmentally benign alternatives, using a rapid bioassay, we evaluated a crude extract from the roots of muscadine Vitis rotundifolia against these fish pathogenic bacteria and determined that the extract was most active against F. columnare. Subsequently, several isolated compounds from the root extract were further evaluated against F. columnare. Among these isolated compounds, (+)-hopeaphenol (2) and (+)-vitisin A (3) were found to be the most active against F. columnare, with 24-h 50% inhibition concentrations of 4.0±0.7 and 7.7±0.6 mg/L, respectively, and minimum inhibitory concentrations of 9.1±0 mg/L for each compound. Efficacy testing of 2 and 3 is necessary to further evaluate the potential for these compounds to be used as antibacterial agents for managing columnaris disease.
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Chemistry, Analytical Chemistry; solid-phase microextraction; air sampling; air analysis; volatile organic compounds; COMSOL; time-weighted average
Online: 19 September 2018 (04:08:14 CEST)
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Determination of time-weighted average (TWA) concentrations of volatile organic compounds (VOCs) in air using solid-phase microextraction (SPME) is advantageous over other sampling techniques, but is often characterized by insufficient accuracies, particularly at longer sampling times. Experimental investigation of this issue and disclosing the origin of the problem is problematic and often not practically feasible due to high uncertainties. This research is aimed at developing the model of TWA extraction process and optimization of TWA air sampling by SPME using finite element analysis software (COMSOL Multiphysics). It was established that sampling by porous SPME coatings with high affinity to analytes is affected by slow diffusion of analytes inside the coating, an increase of analytes concentrations in the air near the fiber tip due to equilibration, and eventual lower sampling rate. The increase of a fiber retraction depth (Z) resulted in better recoveries. Sampling of studied VOCs using 23-ga Car/PDMS assembly at maximum possible Z (40 mm) was proven to provide more accurate results. Alternative sampling configuration based on 78.5 x 0.75 mm i.d. SPME liner was proven to provide similar accuracy at improved detection limits. Its modification with the decreased internal diameter from the sampling side should provide even better recoveries. The developed model offers new insight into optimization of air and gas sampling using SPME.
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Chemistry, Organic Chemistry; coumarin; one-pot synthesis; catalysis; Wells–Dawson heteropolyacid
Online: 18 September 2018 (11:53:28 CEST)
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The development of a method to produce coumarins unsubstituted on the pyranic nucleus catalyzed from Wells–Dawson heteropolyacid (H6P2W18O62), phenol derivatives and ethyl 3,3-diethoxypropionate using Pechmann condensation under solvent-free conditions is described. This catalytic method was also applied successfully to synthesize various substituted coumarins, including the corresponding phenols and ethyl 3,3-diethoxypropionate. This work provides a novel, cheaper and safer way to syhthesize coumarins unsubstituted on the pyranic nucleus.
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Chemistry, Food Chemistry; Ocimum spp.; essential oil; aromatic profiles; Thai food
Online: 18 September 2018 (09:47:32 CEST)
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The research objectives of this study are to analyse the volatile compositions of different basil types available in Thai markets and to descriptively determine their aromatic qualities. Essential oils were hydro-distillated from fresh leaves of 2 Holy basil (Ocimum sanctum) varieties namely, white and red and other basil species, including Tree basil (O. gratissimum), Sweet basil (O. basilicum var. thyrsiflorum) and Lemon basil (O. citriodorum). Oil physicochemical characteristics and volatile chromatograms from Gas Chromatography-Mass Spectrometry (GC-MS) were used to qualitatively and quantitatively describe the chemical compositions. Methyl eugenol, estragole and eugenol were among the major chemicals found in the essential oils of these basil types. Classification by Principal Component Analysis (PCA) advised that these Ocimum spp. samples are grouped based on either the distinctive anise, citrus aroma (estragole, geranial and neral) or spice-like aroma (β-methyl eugenol, caryophyllene and α-cubebene). The essential oil was also used for descriptive sensorial determination by five trained panelists, using the following developed terms: anisic, citrus, herb, spice, sweet and woody. The panelists were able to differentiate essential oil of white Holy basil from red Holy basil based on the intensity of the anisic attribute, while the anise and citrus scents were detected as dominant in the Lemon basil, Tree basil and Sweet basil essential oils. The overall benefit from this research was the elucidation of aromatic qualities from Thai common Ocimum species in order to assess their potential as the raw materials for future food research and development.
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Chemistry, Organic Chemistry; antibacterial; arsenical; calculated NMR spectrum; density functional theory; natural products; NMR spectroscopy; structure elucidation; sulfur metabolite
Online: 17 September 2018 (11:49:07 CEST)
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Isolated from a New Caledonian collection of the poecilosclerid sponge Echinochalina bargibanti, arsenicin A (C3H6As4O3) was described as the first natural organic polyarsenic compound. Continuing on bioassay guided fractionation of the organic extracts of this sponge, we describe here the isolation and structural elucidation of the first sulfur-containing organic polyarsenicals ever found in nature. The novel metabolites, called arsenicin B and arsenicin C, are built on a noradamantane type framework and they further distinguish from the adamantane type framework of arsenicin A by a different heteroatom composition and by the presence of an unusual As-As bonding. Extensive 1D and 2D-NMR measurements, in combination with tandem APCI mass spectra, allowed to establish the structure of arsenicin B (C3H6As4S2) as 2. The scarcity of arsenicin C and and its intrinsic chemical instability, only allowed to collect partial spectral data which prevented the full structural definition. After extensive computational testing of several putative structures, structure 3 for arsenicin C (C3H6As4OS) was inferred by comparing experimental with DFT-calculated 1H and 13C NMR spectra. Finally, the absolute configuration of 2 and 3 were determined with a combined use of experimental and TD-DFT calculated ECD spectra and observed specific rotations. These findings pose great challenges for both the biosynthesis of these metabolites and the cycle of Arsenic in nature. Arsenicin B and arsenicin C showed strong antifungal and antibacterial activities, especially against S. aureus comparable to the antibiotic gentamycin.
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Chemistry, Food Chemistry; Amazonian fruit; funtional food; PCA; person
Online: 17 September 2018 (10:35:49 CEST)
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In this work, nine fruits cultivated in the northern Amazon were studied: abiu, acerola, araçá, bacupari, biribá, caçarí, fruta-do-conde, graviola and taperebá, with the objective of carrying out a bromatological and nutritional study of the pulps of fruits studied. Of all of them, are the pulps of graviola (76.83 ± 0.02 kcal 100 g-1) bacupari (76.83 ± 0.02 kcal 100 g-1) and fruta-do-conde (46.66 ± 0.02 kcal 100 g-1). Among the macronutrients, the high concentration of potassium stands out, especially in the graviola (541.16 ± 0.24 mg 100 g-1) and the biribá (468.21 ± 0.13 mg 100 g-1). Among the micronutrients, iron concentrations are representative for araçá pulp (3.04 ± 0.02 mg 100g-1), abiu is rich in zinc (3.71 ± 0.02 mg 100 g-1) and manganese (6.61 ± 0.11 mg 100 g-1). The presence of cobalt at the level of traces in some of the pulps studied stands out. The Pearson correlation coefficient was evaluated, as well as the statistical treatment by multivariate analysis PCA to establish the correlation between the variables studied.
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Chemistry, Electrochemistry; silicon nanowire (SiNW), hydrogen evolution reaction (HER), reduced graphene oxide
Online: 17 September 2018 (10:09:06 CEST)
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Silicon-based photoelectrochemical (PEC) conversion system has recently gained attention with its ability to provide cost-efficient and superior photoresponsive behavior in regard to other various semiconductor photoelectrodes. Carbon-based co-catalysts have always shared the spotlight for being rendered as alternative metal-free electrocatalysts intended for hydrogen evolution reaction (HER). In particular, a representative carbon-derived material, reduced Graphene Oxide (rGO) has attracted much attention as a non-metal catalyst for efficient and durable HER. Herein, we have deposited rGO on silicon nanowire (SiNW) structure which shows the highest reduction in the overpotential for HER up to date. This could be attributed to the synergistic effects of rGO and SiNW with unique anisotropic morphology, facile tuning capabilities, and scalable fabrication methods. Combined with nanostructured photocathode, rGO deposited SiNW showed better applied bias photon to current conversion efficiency of 3.16%, which is 158 times higher than that of bare planar Si system. In regard to this development we believe that rGO-SiNW photoelectrodes would pave the way for state-of-the-art highly efficient non-metal catalysts for energy conversion technologies.
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Chemistry, Food Chemistry; rice bran; rice genes; rice cultivars; metabolic pathway; metabolomics
Online: 15 September 2018 (19:34:43 CEST)
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Rice (Oryza sativa L.) processing yields ~60 million metric tons of bran annually. Rice genes producing bran metabolites of nutritional and human health importance were assessed across 17 diverse cultivars from seven countries using non-targeted metabolomics and resulted in 378-430 metabolites. Gambiaka cultivar had the highest number and Njavara had the lowest number of metabolites. The 71 rice bran compounds of significant variation by cultivar included 21 amino acids, seven carbohydrates, two metabolites from cofactors and vitamins, 33 lipids, six nucleotides, and two secondary metabolites. Tryptophan, -ketoglutarate, γ-tocopherol/β-tocopherol and γ-tocotrienol are example bran metabolites with extensive cultivar variation and genetic information. 34 rice bran components that varied between cultivars linked to 535 putative biosynthetic genes using to the OryzaCyc 4.0, Plant Metabolic Network database. Rice genes responsible for bran composition with animal and human health importance is available for rice breeding programs to utilize in crop improvement.
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Chemistry, Applied Chemistry; antioxidant activity, biomass, Folin-Ciocalteu assay, lignin, lignocellulose feedstock, organosolv, total phenol content
Online: 14 September 2018 (13:29:47 CEST)
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Antioxidant activity is an essential feature required for oxygen-sensitive merchandise and goods, such as food and corresponding packaging as well as materials used in cosmetics and biomedicine. For example, vanillin, one of the most prominent antioxidants, is fabricated from lignin, the second most abundant natural polymer in the world. Antioxidant potential is primarily related to the termination of oxidation propagation reactions through hydrogen transfer. The application of technical lignin as a natural antioxidant has not yet been implemented in the industrial sector, mainly due to the complex heterogeneous structure and polydispersity of lignin. Thus, current research focuses on various isolation and purification strategies to improve the compatibility of lignin material with substrates and enhancing its stabilizing effect. This contribution presents antioxidant capacity studies of various lignins depending on purification degree of the raw material. In detail, the antioxidant potential of lignin-based compounds is studied using the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. The purification procedure was monitored by thin layer chromatography (TLC) and showed that double-fold selective extraction is the most efficient purification procedure (confirmed by UV-Vis, FTIR, HSQC and 31P NMR spectroscopy, SEC and XRD analysis). Results are discussed regarding the dependency of antioxidant activity on lignin structure and biomass source. Thus, lignins obtained from industrial black liquor are compared with beech wood samples. In addition, the influence of lignin isolation (kraft versus organosolv) is discussed. Values of the antioxidant activity (DPPH inhibition) of kraft lignin fractions were 62-68% while beech and spruce/pine-mixed lignins showed values between 26, 64 and 42%, respectively. TPC values of the different isolated kraft lignin fractions varied between 26-35%, while beech, spruce/pine lignins were 34, 30 and 34%, respectively. Storage decreased the TPC values and increased the DPPH inhibition.
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Chemistry, Analytical Chemistry; dried fish; Puntius sophore; organochlorine pesticide residues; gas chromatography; microbiological quality
Online: 14 September 2018 (04:51:38 CEST)
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The present study was carried out at the north-eastern part of Bangladesh to investigate organochlorine pesticide (OCP) residues and microbiological quality of dried barb (Puntius sophore). Samples were collected from both producers and retailers from December 2016 to April 2017. A control sample was also prepared with the same raw fish used by the producers in the laboratory to compare the result. Gas Chromatography with Electron Capture Detector (GC-ECD) was used to detect and quantify OCP residues. Around 22 % (6) samples out of 27 were found contaminated with OCP residues. Among these six adulterated samples, four were from retailers and two from producers. Only Aldrin was detected in four samples and rest two samples were detected with both Aldrin + Dieldrin and Aldrin + Endrin. Aldrin was found between 0.332 to 0.967 ppm, Dieldrin 0.762 ppm, and Endrin 0.828 ppm. All these values were much higher than the Maximum Residual Limit (MRL) 0.1 ppm. Aerobic Plate Count (APC) of producer samples were ranged between log5.3 ± 0.02 to log5.4 ± 0.03, log6.2 ± 0.02 to log6.4 ± 0.02 for retailer samples and log5.0 ± 0.03 to log5.2 ± 0.04 for control samples. While fungal count was ranged between log3.2 ± 0.04 to log3.5 ± 0.04, log3.4 ± 0.04 to log3.6 ± 0.03 and log2.2 ± 0.05 to log2.5 ± 0.03 for producer, retailer and control samples respectively. All the producer and retailer samples and one-third of the control samples were found contaminated with Escherichia coli. Whereas, Salmonella sp. was detected as 13.3% in producer samples, 20% in retailer samples except for the control. In case of Vibrio sp., maximum count was found for retailer samples (13.3%), whereas, producer and control samples showed no detection. The finding of the present study revealed the presence of pesticides and poor microbiological quality of dried barb are alarming for the consumers of Bangladesh and which may cause chronic disease and potential long-term risk for human health.
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Chemistry, Chemical Engineering; Phospholipid assembly; Bicelle; Membrane fluidity; Membrane polarity; Phase behavior
Online: 13 September 2018 (14:45:35 CEST)
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Self-assembly membranes, composed of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC), were characterized at the total lipid concentration below 20 mM. The sizes of the assemblies varied depending on the molar ratio of DMPC and DHPC (q = [DMPC]/[DHPC]). The small assemblies with diameter of ca. 10 nm were formed at q ≤ 2.0 at 20 ºC (below phase transition temperature of DMPC). The physicochemical membrane properties were then studied using fluorescence probes, 1,6-diphenyl-1,3,5-hexatriene and 6-dodecanoyl-N,N-dimethyl-2-naphthylamine, upon the dilution. DHPC micelle showed a higher membrane fluidity, while the DMPC/DHPC membranes at q ≥ 0.5 showed lower membrane fluidities as well as DMPC vesicle in gel (ordered) phase. Upon dilution, the ordered membrane properties were maintained while the solution turbidities increased, implying the morphological change of the self-assembly, bicelle to the vesicle in gel phase. Based on the obtained results, a phase diagram of DMPC/DHPC binary system (at 20 ºC) is described: (i) the bicelle suspension is transparent and the membrane is in ordered state, (ii) the micelle suspension is transparent and the membrane is in disordered state, (iii) the vesicle suspension is turbid and the membrane is in ordered state.
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Chemistry, Physical Chemistry; carbon bond; three centre-two electron bond; protonated methane
Online: 13 September 2018 (05:01:54 CEST)
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Atoms in Molecules (AIM), Natural Bond Orbital (NBO), and normal coordinate analysis have been carried out at the global minimum structures of TH5+ (T = C/Si/Ge). All these analyses lead to a consistent structure for these three protonated TH4 molecules. The CH5+ has a structure with three short and two long C-H covalent bonds and no H-H bond. Hence, the popular characterization of protonated methane as a weakly bound CH3+ and H2 is inconsistent with these results. However, SiH5+ and GeH5+ are both indeed a complex formed between TH3+ and H2 stabilized by a tetrel bond, with the H2 being the tetrel bond acceptor. The three-center-two-electron bond (3c-2e) in CH5+ has an open structure, which can be characterized as a V-type 3c-2e bond and that found in SiH5+ and GeH5+ is a T-type 3c-2e bond. This difference could be understood based on the typical C-H, Si-H, Ge-H and H-H bond energies. Moreover, this structural difference observed in TH5+ can explain the trend in proton affinity of TH4. Carbon is selective in forming a ‘tetrel bond’ and when it does, it might be worthwhile to highlight it as a ‘carbon bond’.
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Chemistry, Chemical Engineering; heterogeneous catalytic oxidation, gas-solid, liquid-solid, partial and total oxidation, biomass based raw materials, activation methods
Online: 13 September 2018 (02:17:55 CEST)
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In this short review paper we have assembled the main characteristics of partial oxidation reactions (oxidative dehydrogenation and selective oxidation to olefins or oxygenates, as aldehydes and carboxylic acids and nitriles), as well as total oxidation, particularly for depollution, environmental issues and wastewater treatments. Both gas-solid and liquid-solid media have been considered with recent and representative examples within these fields. We have also discussed about their potential and prospective industrial applications. Particular attention has been brought to new raw materials stemming from biomass and to liquid-solid catalysts cases. This review paper also summarizes the progresses made in the use of unconventional activation methods for performing oxidation reactions, highlighting the synergy of these technologies with heterogeneous catalysis. Focus has been centered on usual catalysts activation methods but also on less usual ones, such as the use of ultrasounds, microwaves, grinding (mechanochemistry) and photo-activated processes, as well as their combined use.
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Chemistry, Applied Chemistry; chirality induction; helical chirality; bioorganometallic conjugate; dipeptide; nucleobase; ferrocene; organogold(I); self-assembly; hydrogen bond; Au(I)-Au(I) interaction
Online: 12 September 2018 (11:25:32 CEST)
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Considerable attention has been given to the research field of bioorganometallic chemistry, which is a hybrid chemistry field between biology and organometallic chemistry. The introduction of biomolecules, which have hydrogen bonding sites and chiral centers, into organometallic compounds is considered to be a promising strategy to construct chirality-organized bioorganometallic conjugates. This feature paper sketches an outline of induction of helical chirality into bioorganometallic conjugates. Topics covered include control of the helical chirality of 1,n’-disubstituted ferrocene moieties in ferrocene-dipeptide conjugates and the chirality induction of the Au(I)–Au(I) axis in the dinuclear organogold(I)-uracil conjugates.
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Chemistry, Electrochemistry; origins of life; prebiotic chemistry; mineral catalysis; sulfide minerals; mineral diversity; density functional theory; electrocatalysis
Online: 11 September 2018 (08:39:51 CEST)
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Prebiotic organic synthesis reactions catalyzed by Earth-abundant metal sulfides are key processes for understanding the evolution of biochemistry from inorganic molecules, yet the catalytic functions of sulfides have remained poorly explored in the context of the origins of life. Past studies on prebiotic chemistry have mostly focused on a few types of metal sulfide catalysts, such as FeS or NiS, which form limited types of products with inferior activity and selectivity. To explore the potential of metal sulfides on catalyzing prebiotic chemical reactions, here, the chemical diversity (variations in chemical composition and phase structure) of 304 natural metal sulfide minerals in a mineralogy database was surveyed and approaches to rationally predict the catalytic functions of metal sulfides are discussed based on advanced theories and analytical tools of electrocatalysis such as proton-coupled electron transfer, structural comparisons between enzymes and minerals, and in-situ spectroscopy. To this end, we introduce a model of geo-electrochemistry driven prebiotic synthesis for chemical evolution, as it helps us to predict kinetics and selectivity of targeted prebiotic chemistry under “chemically messy conditions”. We expect that combining the data-mining of mineral databases with experimental methods and theories developed in the field of electrocatalysis will facilitate the prediction and verification of catalytic performance under a wide range of pH and Eh conditions, and aid in the rational screening of mineral catalysts involved in the origins of life.
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Chemistry, Physical Chemistry; formamide; silica; IR-spectroscopy; DFT
Online: 10 September 2018 (14:36:02 CEST)
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Mineral surfaces have been demonstrated to play a central role in prebiotic reaction, which are supposed to be at the basis of the origin of life. Among the various molecules proposed as precursors for these reactions, one of the most interesting is formamide. Formamide has been shown to be a pluripotent molecule, generating a wide distribution of relevant pre-biotic products. In particular, the outcomes of its reactivity are strongly related to the presence of mineral phases, acting as catalysts toward specific reaction pathways. Even if the mineral-products relationship has been deeply studied for a large pool of materials, the fundamental description of the formamide reactivity over the mineral surface at a microscopic level is missing in the literature. In particular, a key step of formamide chemistry at surfaces is its adsorption on the available interaction sites. This report aims to investigate the adsorption of formamide over a well-defined amorphous silica, chosen as model mineral surface. An experimental IR investigation of formamide adsorption has been carried out and its outcomes have been interpreted on the basis of first principles simulation of the process adopting a realistic model of the amorphous silica.
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Chemistry, Organic Chemistry; spatial; age-related; phytochemical; bamboo; rhizome; GC-MS
Online: 7 September 2018 (03:01:53 CEST)
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This study was designed to assess variation of possible phytochemical compounds in the ethanolic extracts of Gigantochloa scortechinii rhizome. Destructive sampling was done by using selective random sampling method on four consecutive rhizomes from healthy clumps and was conducted at two natural forests and one secondary forest (planted). Homogenized sample were extracted using solvent extraction (70% ethanol) method. Ethanolic extracts of G. scortechinii rhizome were qualitatively analyzed using GC/MS GC2010 Plus, Shimadzu to determine the composition of phytochemical compounds and identified using FFNSC 1.3, NIST11, PMW_tox2, and Wiley229 spectral library. A qualitative variation was observed with a total of 56 compounds were identified and differentiated between study site and rhizome age. Results revealed that G. scortechinii rhizome contains various phytochemical compounds with potential as a plant of phytopharmaceutical importance. This is the first finding on the spatial and age-related effects of phytochemical compounds in a consecutive rhizome and of G. scortechinii rhizome specifically.
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Chemistry, Analytical Chemistry; Astragali Radix; Sulfur-fumigation duration; quantification; synthesis.
Online: 5 September 2018 (11:58:25 CEST)
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In this study, an improved UPLC-MS method for simultaneously quantifying twelve major components belonging to two chemical types was developed and validated, and was applied to quantitatively compare the quality of Astragali Radix sulfur-fumigated with different durations and the fresh reference sample. The results showed that the contents of triterpenes Astragaloside III and Astragaloside IV decreased moderately, while the flavonoids calycosin, formononetin, and 7,2'-dihydroxy-3',4'-dimethoxyisoflavane decreased significantly, and its corresponding flavonoid glycosides increased accordingly, which indicatied that the happening of chemical transformation of flavonoids and glycosides in the sulfur-fumigated process. These transformations were further confirmed by the the synthesis of flavonoid glycosides under the simulated sulphur-fumigation circumstances. Furthermore, the sulfur-fumigated duration had a proportional relationship with the contents of compounds 7, 11, and 12. All these results suggested that the established method was precise, accurate and sensitive enough for the global quality evaluation of sulfur-fumigated Astragali Radix, and sulfur-fumigation can not only change the proportions of bioactive components, but also cause the chemical transformation in the Astragali Radix.
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Chemistry, Chemical Engineering; nanostructures; thin films; 3D-coating
Online: 4 September 2018 (15:02:50 CEST)
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We demonstrated a new approach to the production of three-dimensional-coated patterns using liquid route. Metallic perovskite oxides were coated onto three-dimensional (3D) microstructured substrates with different aspect ratios. The success of the method relies on the solution viscosity monitored by adding viscous liquid. The process of oxide thin films consists in three steps: preparing the precursor solution, coating the solution by spin-coating process onto three-dimensional-Si substrates and post-annealing. The chemical solution 3D-coating is conformal.
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Chemistry, Organic Chemistry; Single-atom catalysis; heterogeneous catalysis; chemical innovation; low atomicity
Online: 4 September 2018 (14:55:10 CEST)
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Recent advances in single-atom catalysis resulted in readily accessible materials whose application in most catalytic reactions mediated by conventional nanoparticle-based catalysts often results in higher activity and selectivity. Can we expect catalysis by atomically dispersed atoms to find practical applications? Which are the hurdles to be overcome prior to widespread uptake of atomically dispersed metals in industrial synthetic processes and in hydrogen fuel cells?
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Chemistry, Electrochemistry; Nernst voltage; activation overvoltage; concentration loss; equilibrium potential; exchange current density; net current density
Online: 4 September 2018 (11:56:23 CEST)
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Normally, the Nernst voltage calculated from the concentration of the reaction gas in the flow channel is considered to be the ideal voltage (reversible voltage) of the oxyhydrogen fuel cell, but actually it will cause a concentration gradient when the reaction gas flows from the flow channel through the gas diffusion layer to the catalyst layer. The Nernst voltage loss in fuel cells in most of the current literature is thought to be due to the difference in concentration of reaction gas in the flow channel and concentration of reaction gas on the catalyst layer at the time when the high net current density is generated. Based on the Butler-Volmer equation in oxyhydrogen fuel cell, this paper demonstrates that the Nernst voltage loss is caused by the concentration difference of reaction gas in flow channel and on the catalytic layer at the time when equilibrium potential (Galvanic potential) of each electrode is generated.
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Chemistry, Medicinal Chemistry; pretargeting; Fusarinine C; rituximab; click chemistry; multimerization; PET; gallium-68
Online: 3 September 2018 (15:55:44 CEST)
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Among extensive studies on click chemistry the inverse electron-demand Diels-Alder reaction between 1,2,4,5-tetrazine (Tz) and trans-cyclooct-2-en (TCO) has gained increasing attraction due to its exceptionally fast reaction kinetics and high selectivity for in vivo pretargeting applications including PET imaging. The facile two-step approach utilizing TCO-modified antibodies as targeting structures has not made it into clinic though as the increase in blood volume from mice to human seems to be the major limitation. This study aimed to show if the design of multimeric Tz-ligands by chelator scaffolding can improve the binding capacity and may lead to enhanced PET imaging with gallium-68. For this purpose we utilized the macrocyclic siderophore Fusarinine C (FSC) which allows to conjugate up to three Tz-residues due to three primary amines available for site specific modification. The resulting mono- di- and trimeric conjugates were radiolabelled with gallium-68 and characterized in vitro (logD, protein binding, stability, binding towards TCO modified rituximab (RTX)) and in vivo (biodistribution- and imaging studies in normal BALB/c mice using a simplified RTX-TCO tumour surrogate). The 68Ga-labelled FSC-based Tz-ligands showed suitable hydrophilicity, high stability, high targeting specificity and the binding capacity to RTX-TCO was increased by the grade of multimerization. Corresponding in vivo studies showed a multimerization typical profile but generally suitable pharmacokinetics with low accumulation in non-targeted tissue. Imaging studies in RTX-TCO tumour surrogate bearing BALB/c mice confirmed this trend and revealed improved targeting by multimerization as increased accumulation in RTX-TCO positive tissue was observed.
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Chemistry, Food Chemistry; bottle color, shelf life, Vitis vinifera L., quality control
Online: 3 September 2018 (15:25:23 CEST)
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The objective of this study was to evaluate the evolution of the Syrah red and sparkling Moscatel wines stored for 12 months in green, amber and clear bottles. The phenolic compounds profile and antioxidant activity in vitro were determined. Commercial wines were bottled in an automatic filling machine, stored and analyzed every three months for one year. Several phenolic compound families were quantified through reversed-phase high performance liquid chromatography (RP-HPLC) coupled to diode-array detection (DAD) and fluorescence detection (FD). The different bottle colors studied did not influence the evolution of the sparkling Moscatel and Syrah red wines, since the main variations obtained were related to storage time. The main changes were observed in the Syrah wine, where storage time was associated with an increase in hue (h*), decrease in catechins, increase in procyanidins and, most notably, a decrease in the anthocyanin malvidin 3-glucoside. In general, the wines showed good stability in relation to the antioxidant activity in vitro.
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Chemistry, Applied Chemistry; Photo-sensitization; nitrate; sulfite, 1,4-dioxane, groundwater
Online: 3 September 2018 (13:45:12 CEST)
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Groundwater contamination by nitrate and organic chemicals (e.g. 1,4-dioxane) is a growing worldwide concern. This work presents a new approach for simultaneously treating nitrate and 1,4-dioxane, which is based on UV sensitization of nitrate and sulfite, and the production of reactive species. Specifically, water contaminated with nitrate and 1,4-dioxane is irradiated by a UV source (< 250 nm) at relatively high doses, to sensitize in-situ nitrate and generate HO•. This leads to the oxidation of 1,4-dioxane (and other organics), and the (undesired) production of nitrite as an intermediate. Subsequently, sulfite is added at an optimized time-point, and its UV sensitization produces hydrated electrons which reacts and reduces nitrite. Our results confirmed the effectivity of the proposed treatment: UV irradiation of nitrate (at > 5 mg N/L) efficiently degraded 1,4-dioxane, while producing nitrite at levels higher than 1 mg N/L (its MCL in drinking water). Adding sulfite to the process after 10 minutes of irradiation reduced the concentration of nitrite, without affecting the degradation rate of 1,4-dioxane. The treated water contained elevated levels of sulfate; albeit at much lower concentration than its MCL. Treating water contaminated with nitrate and organic chemicals (often detected concomitantly) typically requires several (expensive) treatment processes. The proposed approach may present a cost-effective alternative, employing a single system for the treatment of nitrate and organic contaminants
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Chemistry, Analytical Chemistry; surface plasmon resonance; urinary tract infection; surface relief gratings; crossed surface relief gratings; nano-plasmonics; biosensing; uropathogenic E. coli
Online: 1 September 2018 (17:29:04 CEST)
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Given the rise in the number of cases and their recurrences, Urinary Tract Infections (UTI) are one of the major burdens on public healthcare worldwide. Rapid, inexpensive and selective detection of Uropathogenic E. coli (UPEC), a major contributor to UTIs, is the need of the hour for effective treatment, given the rise of antibiotic-resistant bacteria due to improper diagnosis. Here we present a rapid, real-time, selective and label-free detection of UPEC using an integrated sensing platform based on Crossed Surface Relief Gratings (CSRGs) as nanoplasmonic sensors. Detection is achieved due to the unique Surface Plasmon Resonance (SPR)-based light energy exchange attributed to the CSRGs, allowing real-time sensing in a very narrow bandwidth of the incident light to pass where the SPR energy conversion occurs. The sensing ability of the platform is experimentally demonstrated by the detection of bulk Refractive Index (RI) changes, with a bulk sensitivity of 382.2 nm/RIU and a resolution in the order of 10-6 RIU. We demonstrate selective capture and detection of clinical concentration of UPEC, as opposed to other gram-negative bacteria, in real-time, a first for CSRGs. This work is particularly important for effective treatment of UTIs, allowing point-of-care diagnosis for economically disadvantaged regions around the world.
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Chemistry, Analytical Chemistry; Breeding population, internal standards, matrix effects, plant volatiles, SPME, odorant analysis
Online: 30 August 2018 (21:22:47 CEST)
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Headspace solid phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry is widely employed for volatile analyses of plants, including mapping populations used in plant breeding research. Studies often employ a single internal surrogate standard, even when multiple analytes are measured, with the assumption that any relative changes in matrix effects among individuals would be similar for all compounds, i.e. matrix effects do not show Compound × Individual interactions. We tested this assumption using individuals from two plant populations, an interspecific grape (Vitis spp.) mapping population (n = 140) and a tomato (Solanum spp.) recombinant inbred line (RIL) population (n = 148). Individual plants from the two populations were spiked with a cocktail of internal standards (n = 6, 9, respectively) prior to HS-SPME-GC-MS. Variation in the relative responses of internal standards indicated that Compound × Individual interactions exist but were different between the two populations. For the grape population, relative responses among pairs of internal standards varied considerably among individuals, with a maximum of 249% relative standard deviation (RSD) for the pair of [U13C]hexanal and [U13C]hexanol. However, in the tomato population, relative responses of internal standard pairs varied much less, with pairwise RSDs ranged from 8% to 56%. The approach described in this paper could be used to evaluate the suitability of using surrogate standards for HS-SPME-GC-MS studies in other plant populations.
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Chemistry, General & Theoretical Chemistry; MDR transporters; MATE family; NorM; MD simulation; loops; sodium ions
Online: 30 August 2018 (14:43:53 CEST)
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The multidrug resistance transporter NorM is an important drug resistance pump and plays a critical role in multidrug resistance in bacteria and mammals. In this study we carried out molecular dynamics simulation to study the mechanism of Na+ binding and dynamical structures of two long loops in the substrate-releasing process in substrate binding NorM. Our simulation study identified several key residues (D41, E261 D377) along the Na+ binding pathway and a multi-state ion-binding mechanism is proposed based on the simulation study. In this proposed model, the transport of Na+ is a multi-stage process with D41 being the first station for binding to Na+, followed by Na+ binding to the second station E262 and finally to the cation-binding site of E262 and D377. During the transport of Na+, the transmembrane components TM1, TM7 and TM2 are rearranged to facilitate the ion transport as well conformational changes of NorM to a closed state. Further, substrate-bound simulation revealed that Loop3-4 and Loop9-10 control the substrate-releasing process.
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Chemistry, Analytical Chemistry; metabolomics; γ-Hydroxybutyric acid; polyamine profiling analysis, gas chromatography-mass spectrometry; star pattern recognition analysis; multivariate analysis
Online: 30 August 2018 (08:14:55 CEST)
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1) Background: Recently, illegal abuse of γ-hydroxybutyric acid (GHB) has increased in drug-facilitated crimes, but determination of GHB exposure and intoxication is difficult due to rapid metabolism of GHB. Its biochemical mechanism has not been completely investigated. And metabolomic study by polyamine profile and pattern analyses was not performed in rat urinefollowing intraperitoneal injection with GHB. 2) Methods: Polyamine profiling analysis by gas chromatography-mass spectrometry combined with star pattern recognition analysis was performed in this study. Multivariate statistical analysis was used to evaluate discrimination between control and GHB administration groups. 3) Results: Six polyamines were determined in control, single and multiple GHB administration groups. Star pattern showed distorted hexagonal shapes with characteristic and readily distinguishable patterns for each group. N1-Acetylspermine (p < 0.001), putrescine (p <0.006), N1-acetylspermidine (p <0.009), and spermine (p < 0.027) were significantly increased in single administration group but were significantly lower in the multiple administration group than in the control group. N1-Acetylspermine was the main polyamine for discrimination between control, single and multiple administration groups. Spermine showed similar levels in single and multiple administration groups. 4) Conclusions: The polyamine metabolic pattern was monitored in GHB administration groups. N1-Acetylspermine and spermine were evaluated as potential biomarkers of GHB exposure and addiction.
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Chemistry, Medicinal Chemistry; ALK5 inhibitor; TGF-β; kinase assay; selectivity; docking
Online: 30 August 2018 (05:52:08 CEST)
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The transforming growth factor-β (TGF-β), in which overexpression have been associated with various diseases, has become an attractive molecular target for the treatment of cancers. Three series of 3-substituted-4-(quinoxalin-6-yl) pyrazoles 14a–h, 15a–h, 16a–h, 22a, 22b, 22d, 23a, 23b, 23d, 24b, and 24d were synthesized and evaluated for their activin receptor-like kinase 5 (ALK5) and p38α mitogen activated protein (MAP) kinase inhibitory activity in an enzymatic assays. Among these compounds, the most active compound 16f inhibited ALK5 phosphorylation with an IC50 value of 0.28 µM, with 98% inhibition at 10 µM. Compound 16f also had good selectivity index of >35 against p38α MAP kinase, with 9.0-fold more selective than clinical candidate, compound 3 (LY-2157299). Molecular docking study was performed to identify the mechanism of action of the synthesized compounds and their good binding interactions were observed. ADMET prediction of good active compounds showed that these ones possess good pharmacokinetics and drug-likeness behavior.
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Chemistry, Organic Chemistry; ruthenium (Ru); N-heterocyclic carbenes (NHCs); homogeneous catalysis; in situ; amide bonds; synthesis.
Online: 29 August 2018 (11:48:42 CEST)
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Transition-metal-catalyzed amide bond formation from alcohols and amines is an atom-economic and eco-friendly route. Herein, we identified a highly active in situ N-heterocyclic carbene (NHC)/ruthenium (Ru) catalytic system for this amide synthesis. Various substrates, including sterically hindered ones, could be directly transformed into the corresponding amides with the catalyst loading as low as 0.25 mol%. In this system, we replaced the p-cymene ligand of the Ru source with a relatively labile cyclooctadiene (cod) ligand so as to more efficiently obtain the corresponding poly-carbene Ru species. Expectedly, the weaker cod ligand could be more easily substituted with multiple mono-NHC ligands. Further HR-MS analyses revealed that two tetra-carbene complexes were probably generated from the in situ catalytic system.
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Chemistry, Medicinal Chemistry; Sarcophyton; Sinularia; Lobophytum; new compounds; anti-microbial; anti-inflammatory; anti-tumoral
Online: 29 August 2018 (09:03:48 CEST)
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Work reviews the new isolated isolated cembranoid diterpene derivatives from species belonging to the family Alcyoniidae, which comprises the genera Sarcophyton, Sinularia, and Lobophytum as well as their biological properties, during 2016–2017. The compilation permitted to conclude that much more new cembranoid diterpenes were found in the soft corals of the genus Sarcophyton sp. (33 new compounds) than in those belonging to the genera Lobophytum (17) or Sinularia (8). Several methods have been used for identifying these new compounds, after extraction with organic solvents and fractionation. The fractions obtained, in some cases, were followed by TLC, and again subjected to chromatographic procedures, including semi-preparative HPLC. Beyond the chemical composition, the biological properties were also evaluated, namely anti-microbial against several Gram-positive and Gram-negative bacteria and fungi, anti-inflammatory and anti-tumoral against several types of cancer cells. Although the biological activities detected in almost all samples, they were not outstanding ones.
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Chemistry, Inorganic & Nuclear Chemistry; Hydrogenase biomimetics; dithiolate; proton-reduction; dppn; redox-active
Online: 28 August 2018 (15:50:13 CEST)
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Addition of the bulky redox-active diphosphine 1,8-bis(diphenylphosphino)naphthalene (dppn) to [Fe2(CO)6(-edt)] (1) (edt = 1,2-ethanedithiolate) affords [Fe2(CO)4(2-dppn)(-edt)] (3) as the major product, together with small amounts of a P-C bond cleavage product [Fe2(CO)5{1-PPh2(1-C10H7)}(-edt)] (2). The redox properties of 3 have been examined by cyclic voltammetry and it has been tested as a proton-reduction catalyst. It undergoes a reversible reduction at E1/2 = –2.18 V and exhibits two overlapping reversible oxidations at E1/2 = –0.08 V and E1/2 = 0.04 V. DFT calculations show that while the HOMO is metal-centred (Fe-Fe -bonding), the LUMO is primarily ligand-based but also contains an antibonding Fe-Fe contribution, highlighting the redox-active nature of the diphosphine. It is readily protonated upon addition of strong acids to afford two isomeric hydride complexes and catalyzes the electrochemical reduction of protons at Ep = –2.00 V in the presence of CF3CO2H. The catalytic current indicates that it is one of the most efficient diiron electrocatalysts for the reduction of protons, albeit operating at quite negative potential.
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Majda Batool,
Affifa Tajammal,
Firdous Farhat,
Francis Verpoort,
Zafar A. K. Khattak,
Mehr-un- Nisa,
Muhammad Shahid,
Hafiz Adnan Ahmed,
Munawar Ali Munawar,
Muhammad Zia ur. Rahman,
Muhammad Asim Raza Basra
Chemistry, Medicinal Chemistry; Factor Xa ( F-Xa), Cardiovascular diseases (CD), Coronary heart disease (CHD), Tissue plasminogen activator (t-PA), Urokinase (UK), Streptokinase (SK), N,N-Dimethyl formamide (DMF)
Online: 27 August 2018 (14:54:10 CEST)
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A new series of 1,3,4-oxadiazoles derivatives was synthesized, characterized and evaluated for their in vitro and in vivo anti-thrombotic activity. Compounds (3a-3i) exhibited significant clot lysis with respect to negative control and reference drug streptokinase (30,000 IU) while enhanced clotting time (CT) values were observed (130-342 sec) for these tested compounds than the standard drug heparin (110 sec.). High affinity towards 1NFY with greater docking score was observed for the compounds (3a, 3i, 3e, 3d and 3h) than the control ligand RPR200095. In addition, very good inhibitory potential against factor Xa (F-Xa) was observed with higher docking scores (5612-6270) with ACE values (–189.68 to –352.28 kcal/mol) than the control ligand RPR200095 (Docking score 5192; ACE –197.81 kcal/mol. In vitro, in vivo and in silico results proposed that these newly synthesized compounds can be used as anti-coagulant agents.
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Chemistry, Analytical Chemistry; bone marrow oil; unsaturated fatty acid; urea inclusion; low temperature crystallization; GC/MS
Online: 27 August 2018 (11:02:38 CEST)
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In this study, four kinds of animal bone marrow powders were extracted with n-hexane using the Soxhlet extraction method. Polyunsaturated fatty acids were enriched by urea inclusion and low temperature crystallization method, then were further evaluated antioxidant and antibacterial activities. These results showed that the oil composition of the n-hexane extracts of four kinds of animal bone marrow primarily consisted of palmitic acid (18.57–31.01%), stearic acid (3.6–20.95%), and oleic acid (40.22–58.69%). The ratios of saturated fatty acids (SFA)/unsaturated fatty acids (UFA) were 1/1.417, 1/1.327, 1/2.140, and 1.285/1 for sheep, bovine, horse, and camel bone marrow oil, respectively. The SFA/UFA ratios determined by the urea inclusion method were 1/1.518, 1/1.390, 1/2.037, and 1.216/1, respectively. The SFA/UFA ratios according to the low temperature crystallization method with acetone were 1/1.920, 1/2.141, 1/2.360, and 1/1.157 for sheep, bovine, horse, and camel bone marrow oil, respectively. These enrichment methods effected the concentrations of UFAs from the camel bone marrow oil. Among the methods, the low temperature crystallization method effectively enriched the UFAs. All four bone marrow oils exhibited strong antioxidant and antimicrobial activities. The horse bone marrow oil showed the strongest antioxidant activity. Both antioxidant and antimicrobial activity improved after enrichment of the UFAs. These results lay a theoretical basis for application bone marrow oil resources in food and medicine.
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Chemistry, Applied Chemistry; antibiotic residues; aquatic environment; ciprofloxacin; Fe doped ZnO nanoparticles; photocatalysis; sunlight
Online: 27 August 2018 (09:01:34 CEST)
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Antibiotic residues in aquatic environment have the possibility to induce resistance in environmental bacteria, which ultimately might get transferred to pathogens making treatment of diseases difficultand poses a serious threat to public health. If antibiotic residues in the environment can be eliminated or reduced, it has the possibility to contribute antibiotic resistance. Towards this objective, water containing ciprofloxacin was treated with sunlight assisted photocatalysis using Fe doped ZnOnanoparticles for assessing the degradation potential of this system.Parameters like pH, temperature, catalytic dosage were assessed for the optimum performance of the system. To evaluate degradation of ciprofloxacin,both spectrophotometricas well as microbiological (loss of antibiotic activity)methods were employed. 100 mg/L Fe doped ZnO nanoparticle catalyst and sunlight intensity of 120,000–135,000 lux system gave optimum performance at pH 9 at 30 °C and 40 °C. At these conditions spectrophotometric analysis showed complete degradation of ciprofloxacin (10mg/L) by 210 min. Microbiological studies showed loss of antibacterial activity of the photocatalytically treated ciprofloxacin containingwater against Staphylococcus aureus (108 CFU) in 60 min and for Escherichia coli (108 CFU) in 75 min. Thedeveloped system, thus possess a potential for treatment of antibiotic contaminated waters for eliminating/reducing antibiotic residues from environment.
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Chemistry, Analytical Chemistry; metabolomics; direct mass spectrometry; Alzheimer’s disease; pathogenesis; biomarkers
Online: 23 August 2018 (10:10:47 CEST)
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Direct mass spectrometry-based metabolomics has been widely employed in the last years to characterize metabolic alterations underlying to Alzheimer’s disease development and progression. This high-throughput approach presents a great potential for fast and simultaneous fingerprinting of a vast number of metabolites, which can be applied to multiple biological samples such as serum/plasma, urine, cerebrospinal fluid and tissues. In this review article we present the main advantages and drawbacks of metabolomics based on direct mass spectrometry compared with conventional analytical techniques, and provide a comprehensive revision of the literature on the application of these tools in Alzheimer’s disease research.
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Chemistry, Analytical Chemistry; soil; PAHs; diboll; fluoranthene; pyrene; gas chromatography-mass spectrometry
Online: 23 August 2018 (04:18:17 CEST)
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Concentrations of six polycyclic aromatic hydrocarbons (benzanthrone, benz[a]anthracene, chrysene, fluoranthene, pyrene, and triphenylene) of soil samples from Diboll, an East Texas city (USA), were analyzed with gas chromatography-mass spectrometry (GC-MS). Samples were collected from five sites; Old Orchard Park, two heavy traffic intersections (Judd Street and Lumberjack Drive), an industrial site (West Borden Drive), and a truck stop. Acetone and dichloromethane extracts in all samples showed the presence of fluoranthene and pyrene. The sum of fluoranthene and pyrene concentrations in sites followed the order West Borden Drive > Judd Street > Lumberjack Drive > Old Orchard Park > truck stop. Concentrations of fluoranthene and pyrene were in the range 12.3 – 396.5 μg kg-1 (ppb) and 13.6 – 209.8 μg kg-1 (in dry soil), respectively. Benzanthrone, benz[a]anthracene, chrysene, and triphenylene concentrations were < 2 ppb levels. The higher concentrations in soils were associated with sites close to heavy traffic and vehicular emissions.
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Chemistry, Applied Chemistry; application; organochlorine; pesticides; metabolites; homesteads; soils
Online: 18 August 2018 (07:53:56 CEST)
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The continued application of organochlorine pesticides (OCPs) in indoor residual spraying has posed significant threat to human health in Northern part of South Africa, despite its ban. In this study, we investigated the occurrence and spatial distribution of DDTs and its metabolites in surface soil (30 samples) collected in and around the spray homesteads; demarcated into three concentric zones A, B, C in Tshilamusi Vhembe district, South Africa. DDTs were the most abundant of all the OCPs chemicals found in soil samples. The concentrations of DDT range from 12.19 to 65.69 µg/kg, with the highest occurring at zone A which is the zone of application. DDTs and all its metabolites considered in this study were found in appreciable concentrations in soil of Zones B and C, far from spray sites. The results showed a strong correlation between distance and concentration levels of DDTs and its metabolites. However, there is a need for proper monitoring of OCPs chemicals in other environmental matrices as well as relevant agencies enforcing strict adherence to regulations on consumption of OCPs.
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Chemistry, Food Chemistry; malolactic fermentation; coinoculation; diacetyl; esters; aromatic compounds; grape wine
Online: 18 August 2018 (06:00:30 CEST)
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We examined the effects of different malolactic bacteria fermentation techniques, including a spontaneous process – a variant with a high risk of undesirable metabolites – on the bioconversion of aromatic compounds in cool-climate grape wines. During three wine seasons, red and white grape wines were produced by three different methods of malolactic fermentation induction: coinoculation, sequential inoculation, and spontaneous malolactic fermentation. Volatiles (diacetyl and the products of its metabolism, as well as selected ethyl fatty acids esters) were extracted by solid phase microextraction. Compounds were identified with multidimensional gas chromatograph GCxGC-ToFMS with ZOEX cryogenic (N2) modulator. Sensory evaluation of the wines was also performed. We found, that the fermentation-derived metabolites examined in this study were affected by the malolactic bacteria inoculation regime. Quantitatively, ethyl lactate, diethyl succinate and ethyl acetate dominated as esters with the largest increase in the concentration. The total concentration of ethyl esters was highest for the coinoculation scenario. Whereas the highest concentration of diacetyl was noted for the spontaneous processes. A controlled malolactic fermentation, especially using the coinoculation technique, can be proposed as a safe and efficient enological practice for producing quality, cool-climate grape wines enriched with fruity, fresh and floral aromas.
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Chemistry, Physical Chemistry; bentonite, N2 physisorption, BET, thermogravimetry, clay
Online: 10 August 2018 (09:51:31 CEST)
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The employment of clays in industry and on laboratory scale is still of interest, despite their long history. The chemical-physical characteristics of such material are strongly related to their geographical origin and the availability of proper characterization techniques is of great importance in order to gain as more information about their behavior when utilized as filling materials. In the present contribute a physical characterization by meaning of Thermogravimetry and N2 physisorption, including a thermal stability evaluation, of samples of Sardinian bentonite collected from the Alghero area (Italy) is reported.
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Chemistry, Organic Chemistry; FTIR; Heterocyclic amines; NMR; Oxadiazole; Polyphosphoric acid
Online: 9 August 2018 (13:08:08 CEST)
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1-[5-(4-methylphenyl)-1,3,4-oxadiazol-2-yl]methanamine compound has been successfully synthesized by reacting p-Toluic hydrazide and glycine via polyphosphoric acid condensation route. The course of the reaction was found to be high yielding and the title compound was spectroscopically characterized by FT-IR, DSC, 13C/1H-NMR and Mass spectrometric techniques.
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Chemistry, Food Chemistry; hot foods; temperature; esophageal cancer; thermosensing; sensory thresholds; methodological study
Online: 9 August 2018 (12:50:40 CEST)
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Epidemiological studies indicate an increased risk of cancer from the consumption of very hot foods and beverages. The International Agency for Research on Cancer (IARC) has already recommended threshold values for the maximum drinking temperature of very hot beverages. The contact time and the contact temperature are decisive for the risk of injury when hot media come into contact with human skin. However, measuring the contact temperature is not easily possible in practice. In the present study, a numerical simulation based on the solution of the heat conduction equation was initially used to investigate whether and for what period of time a constant contact temperature is to be expected under oral conditions. For small circular 3-cm food samples (e.g., cooked potatoes) with 2.5 mm thickness in contact with the tongue, the simulation results in a constant contact temperature of 10 s before cooling. With a thickness of 0.5 mm, the contact temperature is only maintained 1 s. Hot beverages, which spread as a thin film and thereby increase their surface area, can therefore be consumed at higher temperatures than solid foods. Furthermore, a simple test technique with a "measuring spoon" was developed. A hot sample is placed on the tongue. Orientating measurements were used to determine which contact temperature was considered to be just comfortable for any period > 10 s and for which period of less than 10 s it was still just bearable. The contact temperature, which was still perceived as tolerable for periods > 10 s, was 46.5 °C. The time spans for the higher contact temperature 48 °C were between 2 and 4 s and for 49 °C between 1 and 2 s. The course of the contact temperatures determined in the experiment over time allows to calculate the corresponding threshold values of consumption temperatures for various foods. Consumption temperatures of about 56 °C for potatoes and 60 °C for cheese are still perceived as tolerable. In view of the fact that the contact temperature is obviously the determining factor for the risk of injury from burns in the oral cavity in addition to the contact time, it makes sense to reference threshold values to the contact temperature rather than to the surface or consumption temperature of a food product, which is current customary practice. If this contact temperature is defined as a threshold value, the surface or consumption temperature for any other food can be calculated.
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Chemistry, Physical Chemistry; Ferrocenium conformers, electron structure of organometallic complexes, excess orbital energy spectrum (EOES), α- and β-electrons of Fc+, energy decomposition analysis (EDA).
Online: 8 August 2018 (11:16:59 CEST)
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Ferrocenium (Fc+) inherits a number of molecular/electronic properties from the neutral counterparts’ ferrocene (Fc) including the high symmetry. Both Fc+ and Fc prefer the eclipsed structure (D5h) over the staggered structure (D5d) by an energy of 0.36 kcal·mol-1. The present study using the recently developed excess orbital energy spectrum (EOES) shows that the open shell Fc+ cation exhibits similar conformer dependent configurational changes to the neutral Fc conformer pair. A further energy decomposition analysis (EDA) discloses that the reasons for the preferred structures are different between Fc+ and Fc. The dominant differentiating energy between the Fc+ conformers is the electrostatic energy (EEstat), whereas in neutral Fc, it is the quantum mechanical Pauli repulsive energy (EPauli). Within the D5h conformer of Fc+, the EOES reveals that the -electrons of Fc+ experience more substantial conformer dependent energy changes than the -electrons (assumed the hole is in a β orbital).
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Chemistry, Analytical Chemistry; 4-benzoyl pyrazolone; fluorescence sensing; functionalized gold nanoparticles; detection Al3+ ion
Online: 8 August 2018 (03:53:55 CEST)
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A new type of gold nanoparticles was synthesized by using benzoyl pyrazolone as a capping agent. The synthesized AuNPs exhibited a spherical shape and a monodisperse and fluorescence emission characteristic peak at 650 nm. The AuNPs –BMPBP was demonstrated as sensitive and selective fluorescent chemosensor for detection of Al 3+ ion. In the presence of Al 3+ ion, the fluorescent emission of BMPBP-AuNPs at 650 nm, increased with an increasing concentration of Al 3+ ion with a low detection limit (2 µM), the proposed method provided to apply determination of Al 3+ ion of tap water with satisfactory results.
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Chemistry, Other; master Valentim’s fountain; gneiss; lioz limestone; conservation and restoration
Online: 7 August 2018 (05:18:42 CEST)
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Master Valentim’s fountain became an important historical patrimony for Brazil, being portrayed by famous artists among them Jean-Baptiste Debret. In 1938, it was registered as cultural heritage by the Brazilian National Historical and Artistic Heritage Institute (IPHAN), and in 1990 it was subjected to excavation and restoration works. The fountain was built in Gneiss and Lioz limestone, with metallic plates and mortar connecting the Gneiss blocks. Currently, deteriorations in the fountain stones can be observed such as light stains and some aesthetic modifications caused by inadequate restorations. Petrography, XRF, XRD, Physical Properties, Colorimetry, Electrical Conductivity, ICP-OES, SEM-EDX, and TGA were performed in order to characterize the Gneiss blocks, the metallic plates, the stones used in previous restorations, as well as light stains observed on the Gneiss blocks. The petrography and XRD analyses inferred that light stains may have been caused by the formation of an insoluble salt as a result of the association of the lead from the plates with other elements. The XRD analysis on the light staining area indicated presence of cerussite (PbCO3), and anglesite (PbSO4), which are the probable cause of the light stains. The SEM-EDX results suggested that sulfur is the main element associated to lead.
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Chemistry, Other; HCT-116, WS1, water dispersive QDs, aqueous synthesis, cytotoxicity of QDs.
Online: 6 August 2018 (13:56:16 CEST)
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Semiconductor nanocrystals or quantum dots (QDs), have unique optical and physical properties that make them potential imaging tools in biological and medical applications. However, concerns such as the aqueous dispersivity, toxicity to cells and stability in biological environments may limit the use of QDs in bioapplications. Here, we report an investigation into the cytotoxicity of aqueously dispersed CdSe(S) and CdSe(S)/ZnO core/shell QDs in the presence of human colorectal carcinoma cells (HCT-116) and a human skin fibroblast cell line (WS-1). The cytotoxicity of the precursor solutions used in the synthesis of the CdSe(S) QDs was also determined in the presence of HCT-116 cells and compared to that of the heat-shock protein (Hsp90) inhibitor, 17-AAG. CdSe(S) QDs were found to have a low toxicity at concentrations up to 100 µg/ml, with a decreased cell viability at higher concentrations, indicating a highly dose-dependent response. Meanwhile, CdSe(S)/ZnO core/shell QDs exhibited lower toxicity than uncoated QDs at higher concentrations. Confocal microscopy images of HCT-116 cells after incubation with CdSe(S) and CdSe(S)/ZnO QDs showed that the cells were stable in aqueous concentrations of 100 µg of QDs per ml, with no sign of cell necrosis, confirming the cytotoxicity data. Key words: HCT-116, WS1, water dispersive QDs, aqueous synthesis, cytotoxicity of QDs.
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Chemistry, Food Chemistry; enabling technologies; pilot reactors; ultrasound; hydrodynamic cavitation; polyphenols; grape pomace; olive leaves.
Online: 6 August 2018 (10:18:35 CEST)
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We herein provide an overview of the most recent multidisciplinary process advances that have occurred in the food industry as a result of changes in consumer lifestyle and expectations. The demand for fresher and more natural foods is driving the development of new technologies that may efficiently operate at room temperature. Moreover, the huge amount of material discarded by the agro-food production chain lays down a significant challenge for emerging technologies that can provide new opportunities by recovering valuable by-products and creating new applications. Aiming to design industrial processes, there is a need of pilot scale plants such as the “green technologies development platform” that was established by the authors. The platform is made up of a series of multifunctional laboratories that are equipped with non-conventional pilot reactors developed in direct collaboration with partner companies in order to bridge the enormous gap between academia and industry via the large-scale exploitation of relevant research achievements. Selected key, enabling technologies for process intensification make this scale-up feasible. We make use of two selected examples, the grape and olive production chains, to show how cavitational reactors, which are based on high-intensity ultrasound and rotational hydrodynamic units, can assist food processing and the sustainable recovery of waste to produce valuable nutraceuticals as well as colouring and food-beverage additives.
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Chemistry, Chemical Engineering; Li-ion batteries; anode; cobalt recycling
Online: 6 August 2018 (08:14:51 CEST)
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In this paper, a new anode environmentally friendly for hydrogen production was developed based on 430 stainless steel with an electrodeposited cobalt layer. The novelty of this work is the cobalt source once the electrodeposition bath was obtained from recycling of spent Li-ion batteries cathode with composition LiCoO2. The electrodeposited cobalt behaves as supercapacitor in KOH 1M. In the linear voltammetry in KOH 1M, when the overpotential reaches 370 mV, the anodic density current for 430 SS/Co is 19 mA cm−2. Thus, the anode developed in this paper achieves the double of density current with half of production cost if compared with 316SS. Moreover the anode construction described in this paper is an excellent option for Li- ion battery recycling.
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Chemistry, Chemical Engineering; recycling; Li-ion, methylene blue; LiCoO2
Online: 6 August 2018 (06:25:05 CEST)
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In this paper the application of recycled Li-ion batteries spent cathode (LIB-SC) combined with NaHCO3/H2O2 system is presented for the first time in the literature as an alternative for degradation of potentially toxic organic molecules. The model pollutant choice was methylene blue molecule. The spent cathode composition corresponds to LiCoO2, which was proved by the XRD and EDX. Regarding the decolorization of methylene blue solution, the addition of NaHCO3 in comparison with only H2O2 reduces the complete decolorization time in 96%. This reduction occurs because the radical CO3 is more stable than OH. In this way, the application the system proposed in this article is aimed at solving two major global problems: the disposal of cell phone batteries and the pollution of liquid effluents.
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Chemistry, Applied Chemistry; bimetallic nanoparticles, solvent free hydrogenation, nitrobenzene and chloronitrobenzene.
Online: 5 August 2018 (23:00:14 CEST)
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Selective hydrogenation of nitrobenzene was carried out under solvent-free conditions using supported AuPd nanoparticles catalyst, prepared by modified impregnation method (MIm), as efficient catalyst. >99% yield of aniline (AN) was obtained after 15 hours at 90 °C, 3 bar H2 that can be used without any further purification or separation, therefore reducing cost and energy input. Supported AuPd nanoparticles catalyst, prepared by MIm, was found to be active and stable even after 4 recycle experiments whereas the same catalyst prepared by SIm deactivated during the recycle experiments. The most effective catalyst was tested for the chemoselective hydrogenation of 4-chloronitrobenzene (CNB) to 4-chloroaniline (CAN). The activation energy of CNB to CAN was found to be 25 kJ mol-1, while that of CNB to AN was found to be 31 kJ mol-1. Based on this, the yield of CAN was maximized (92%) by lowering the reaction temperature to 25 °C.