ARTICLE | doi:10.20944/preprints202004.0169.v1
Subject: Chemistry, Electrochemistry Keywords: black Si; antireﬂection; photo-anode; water splitting9
Online: 10 April 2020 (07:51:31 CEST)
The fabrication and characterisation of photo-anodes based on black-Si (b-Si) are presented using a photo-electrochemical cell in NaOH solution. Black-Si was fabricated by maskless dry plasma etching and was conformally coated by tens-of-nm of TiO2 using atomic layer deposition (ALD) with a top layer of CoOx cocatalyst deposited by pulsed laser deposition (PLD). Low reﬂectivity R < % of Black-Si over the entire visible and near-IR (λ < 2 µm) spectral range is favourable in better absorption of light while an increased surface area facilities larger current densities. Photoelectrochemical performance of the heterostructured photoanode is discussed in terms of n-n junction between b-Si and TiO2.
TECHNICAL NOTE | doi:10.20944/preprints202301.0113.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: Li-ion battery LIB; Lithium Cobalt Oxide LCO; electrolyte; graphite anode; and lithium anode
Online: 6 January 2023 (03:59:35 CET)
Lithium-ion (Li-ion) batteries are becoming more common in portable electronic devices due to their high energy density, lack of memory effect, and high charge and discharge rate capabilities. Li-ion batteries are a relatively new technology, first marketed in the early 1990s, and research and development work are ongoing to improve safety and increase capacity, charge/discharge rate, and lifetime . In this paper, we review the types and characteristics of Li-ion batteries and summarize charging methods and safety considerations. Following, we design and fabricate Li-ion battery and highlight the steps of fabrication that ensure fast charge/discharge rates that give the battery more reliability and high energy density
REVIEW | doi:10.20944/preprints202006.0152.v1
Subject: Engineering, Energy & Fuel Technology Keywords: Perovskite; Electrooxidation; Fuel flexibility; Renewables; Anode
Online: 12 June 2020 (12:33:14 CEST)
Exsolved perovskites can be obtained from lanthanum ferrites, such as La0.6Sr0.4Fe0.8Co0.2O3, as result of Ni doping and thermal treatments. Ni can be simply added to the perovskite by an incipient wetness method. Thermal treatments include calcination in air (e.g., 500 °C) and subsequent reduction in diluted H2 at 800 °C to favor the exsolution process. The chemistry of the nanoparticles exsoluted on the substrate surface can be further modulated by a post treatment in air. These processes allow to produce a two-phase material consisting of a Ruddlesden-Popper type structure and a solid oxide solution e.g. α-Fe100-y-zCoyNizOx oxide. The formed electro-catalyst shows sufficient electronic conductivity under reducing environment at the SOFC anode. Outstanding catalytic properties are observed for the direct oxidation of dry fuels in SOFCs, including H2, methane, syngas, methanol, glycerol and propane. This anode electrocatalyst can be combined with full density electrolyte based on Gadolinia-doped Ceria or with La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM) or BaCe0.9Y0.1O3-δ (BYCO) to form a complete perovskite structure-based cell. Moreover, the exsolved perovskite can be used as a coating layer or catalytic pre-layer of a conventional Ni-YSZ anode. Beside the excellent catalytic activity, this material also shows proper durability and tolerance to sulphur poisoning. In this mini review, preparation methods, physico-chemical characteristics, surface properties of exsoluted and core-shell nanoparticles encapsulated on the metal-depleted perovskite substrate surface, electrochemical properties for the direct oxidation of dry fuels and related electrooxidation mechanisms are examined and discussed.
TECHNICAL NOTE | doi:10.20944/preprints201808.0100.v1
Online: 6 August 2018 (08:14:51 CEST)
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.
ARTICLE | doi:10.20944/preprints201612.0133.v1
Subject: Materials Science, General Materials Science Keywords: MoS2; carbon nanofibers; electrospinning; anode material
Online: 28 December 2016 (10:49:33 CET)
The one-dimensional MoS2/carbon nanofibers (1D MoS2/CNFs) are synthesized by electrospinning using exfoliated MoS2 nanosheets and polyacrylonitrile as raw materials. The exfoliated MoS2 nanosheets with size of about 150 nm are encapsulated in carbon nanofibers, and the free-standing MoS2/CNFs can be easily cut into flexible tablet and directly used as binder-free anode for lithium storage. The resultant 1D MoS2/CNFs exhibit a very high reversible capacity of 700 mAh g-1 at 100 mA g-1 after 50 cycles, high rate capacity (450 mAh g-1 at 1000 mA g-1 after 200 cycles) and good cycle stability.
ARTICLE | doi:10.20944/preprints202003.0376.v2
Subject: Mathematics & Computer Science, Information Technology & Data Management Keywords: Photo-taking Behavior; photo capturing and sharing; bystanders; human behavior analysis; identity protection
Online: 13 September 2020 (11:16:17 CEST)
Nowadays, with smartphones people can easily take photos, post photos to any social networks and use the photos for some purposes. This leads to a social problem that unintended appearance in photos may threaten the privacy of photographed person. Some solutions to protect facial privacy in photos have already been proposed. However, most of them rely on different techniques to de-identify photos which can be done only by photographers, giving no choice to photographed person. To deal with that, we propose an approach that allows photographed person to proactively detect whether someone is intentionally/unintentionally trying to take pictures of him/her. Thereby, he/she can have appropriate reaction to protect the privacy. In this approach, we assume that the photographed person uses a wearable camera to record the surrounding environment in real-time. The skeleton information of likely photographers who are captured in the monitoring video is then extracted to be put into the calculation of dynamic programming score which is eventually compared with a threshold for recognition of photo-taking behavior. Experimental results demonstrate that by using the proposed approach, the photo-taking behavior is precisely recognized with high accuracy of 92.5%.
ARTICLE | doi:10.20944/preprints201701.0089.v1
Subject: Materials Science, Nanotechnology Keywords: MoS2; composite; anode; low cost; Li-ion battery
Online: 19 January 2017 (11:08:29 CET)
A low-cost bio-mass-derived carbon substrate has been employed to synthesize MoS2@carbon composites through a hydrothermal method. Carbon fibers derived from natural cotton provide a three-dimensional and open framework for the uniform growth of MoS2 nanosheets, thus constructing hierarchically coaxial architecture. The unique structure could synergistically benefit fast Li-ion and electron transport from the conductive carbon scaffold and porous MoS2 nanostructures. As a result, the MoS2@carbon composites, when served as anodes for Li-ion batteries, exhibit a high reversible specific capacity of 820 mAh g-1, high-rate capability (457 mAh g-1 at 2 A g-1), and excellent cycling stability. The superior electrochemical performance makes the MoS2@carbon composites to be low-cost and promising anode materials for Li-ion batteries.
BRIEF REPORT | doi:10.20944/preprints202011.0320.v1
Online: 10 November 2020 (15:05:24 CET)
This study evaluates the production of biohydrogen from agro industrial waste. The worldwide energy demand is increasing exponentially and the reserves of fossil fuels are depleting, the combustion of fossil fuels has the effect on environment because of CO2 emission. Hydrogen generation market size is forecast to cross 180 billion by 2024, according to a new research report by global market. For the production of biohydrogen. we had chosen groundnut shell as our source, using Tween80 as a surfactant we had undergone pre-treatment studies for (10min,20min,30min,40min,50min) we had estimated the content of cellulose, protein, carbohydrates at (1%,2%,3%,4%,5%) and obtained the optimum value in the form of graph. The production of hydrogen is done by using the rumen fluid of the cow and the quantity of the hydrogen produced by this process is identified by using the analytical instrument Gas Chromatography.
ARTICLE | doi:10.20944/preprints202002.0157.v1
Subject: Physical Sciences, Applied Physics Keywords: impedance; photo-electrochemical cell; reaction centers
Online: 12 February 2020 (12:15:48 CET)
Bio-devices are designed to allow biological matter to perform in vitro almost the same functions it performs in vivo. Therefore, they can benefit from the specificities of such materials and are expected to perform better than traditional devices. On the other hand, the integration of biological material with electronic/electrochemical instrumentation requires careful attention and can produce unconventional results. In this paper, we describe the impedance response of an electrochemical cell that converts sunlight into electrical power. It uses the photosynthetic system known as Reaction Center, which is the core of photosynthesis in several living beings. Under illumination, an abrupt transformation drives the cell electrical response from insulator to conductor and a photocurrent is observed. The impedance spectrum shows a peculiar shape which significantly modifies with the protein activation. It has been analyzed by means of a graphical/analytical/ numerical procedure. The modelling identifies an analogue electrical circuit, whose parameters give quantitative information about the underlying process. Finally, an appropriate normalization of data is proposed which validates data in dark and light and can be useful as a fast screening of measurements.
ARTICLE | doi:10.20944/preprints201909.0064.v1
Online: 5 September 2019 (15:44:49 CEST)
In this paper, first the Self-Written Waveguide (SWW) process in wet photopolymer media (liquid solutions), are examined for three examples: single-, counter-, and co-fibers exposure. Then the SWWs formed inside solid material are examined including the effects of manipulating the alignment of the fibers. In all cases high precision measurements are used to position the fiber optic cables (FOCs) before exposure using a microscope. The self-writing process is indirectly monitored by observing (imaging) the light emerging from the side of the material sample during SWW formation. In this way the optical waveguide trajectories formed in an Acrylamide/Polyvinyl Alcohol (AA/PVA) a photopolymer material (sensitized at 532 nm) are examined. First the transmission of light by this material is characterized. Then the bending and merging of the waveguides which occur are investigated. The predictions of our model are shown to qualitatively agree with the observed trajectories. The largest index changes taking place at any time during the exposure, i.e. during SWW formation, are shown to take place at the positions where the largest exposure light intensity is present. Typically, such maxima exist close to the input face and the first maximum is referred to as the location of the Primary Eye. Other local maxima also appear further along the SWW and are referred to as Secondary Eyes, i.e. deeper within the material.
ARTICLE | doi:10.20944/preprints201809.0036.v1
Subject: Chemistry, Applied Chemistry Keywords: Photo-sensitization; nitrate; sulfite, 1,4-dioxane, groundwater
Online: 3 September 2018 (13:45:12 CEST)
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
ARTICLE | doi:10.20944/preprints201804.0174.v1
Subject: Chemistry, Electrochemistry Keywords: Perovskite materials; energy; band-gap; photo-efficiency.
Online: 13 April 2018 (06:41:48 CEST)
In a world where conventional sources of energy are fast depleting, the quest for alternative energy sources may hold the key for the survival of humanity. In the present work, emphasis has been given to the idea of producing energy from perovskite based solar cells. In order to bring this idea into fruition, a unique and novel nano structured perovskite material n-propyl ammonium lead chloride (C3H7NH3+PbCl3⁻) was prepared through a unique co-precipitation route using n-propyl amine (n-C3H7NH2) and hydrochloric acid as the starting precursors with aqueous solution of Pb(CH3COO)23H2O. Finally acetic acid was added to the solution and this solution was allowed to concentrate and then gradually cooled down to room temperature. After math, the synthesized material was spin-coated on TiO2 film to fabricate the solar cell. The device was then undergone systematic analysis using XRD, SEM, UV and Photo Conversion to get a transparent idea regarding its structural, electrical and optical properties. When experimentally applied, this perovskite-based solar cell has shown energy conversion efficiency (η) of around 6.01 % which is noticeably good. Thus it can be concluded that this material is promising for fabrication of vastly efficient solar cells. This technology can be tried in large scale as an alternative of conventional energy in the near future.
REVIEW | doi:10.20944/preprints202011.0398.v1
Subject: Chemistry, Electrochemistry Keywords: bioelectrocatalysis; nanostructured electrodes; protein engineering; bioelectrosynthesis; photo-bioelectrocatalysis
Online: 16 November 2020 (08:32:45 CET)
Bioelectrocatalysis has become one of important research fields in electrochemistry and provided a firm base for an important technology for application to various bioelectrochemical devices such as biosensors, biofuel cells, and biosupercapacitors. The understanding and technology in bioelectrocatalysis have been greatly improved by introducing nanostructured electrode materials and protein-engineering methods over the last few decades. Recently, the electro-enzymatic production of renewable energy resources and useful organic compounds (bioelectrosynthesis) also attracts worldwide attention. In this review, we summarize recent progress in applications of enzymatic bioelectrocatalysis.
ARTICLE | doi:10.20944/preprints201909.0152.v1
Subject: Chemistry, Medicinal Chemistry Keywords: chlorophyll; carotenoids; methanol; photo-protection; phytoextraction; Portulaca oleracea
Online: 15 September 2019 (15:04:55 CEST)
The chlorophyll is one of the most important natural pigments used extensively in the food industry. Two important factors for the production of chlorophyll are the use of plants rich in chlorophyll and efficiency of extraction method. Present investigation was performed to compare the extraction of photosynthetic pigments by using solvents of different chemical nature. The purslane plants with different growth behavior viz. Scrollable and standing were grown under shade and sunshine stress condition. Different solvents including diethyl ether, 5% ethanol, pure acetone, 20% acetone, pure methanol and 10% methanol were used to extract chlorophyll and carotenoids from the purslane plant. The results indicated that stress, growth type and different solvents had a significant effect on the extraction of chlorophyll and carotenoids. Different trend was observed in extraction rate for chlorophylls and carotenoids. Among the solvents, pure methanol was the best for extraction of chl a. Methanol and acetone were appropriate solvents to achieve the highest amount of chlorophyll from plant tissues. Among different solvents, pure methanol for chl a, pure acetone and methanol for carotenoids were best solvent for purslane plant with a growing type scrollable of under shade.
ARTICLE | doi:10.20944/preprints202110.0053.v1
Subject: Materials Science, General Materials Science Keywords: lithium-ion battery; anode battery; lithium-ion thermodynamics; solid-state synthesis
Online: 4 October 2021 (11:54:45 CEST)
Li3FeN2 material was synthesized by two-step solid-state method from Li3N (adiabatic camera) and FeN2 (tube furnace) powders. Phase investigation of Li3N, FeN2 and Li3FeN2 were carried out. Discharge capacity of Li3FeN2 is 343 mAh g-1, that is about 44.7% of theoretic capacity. The molar heat capacity of Li3FeN2 at constant pressure in the temperature range 298-900 K should be calculated as Cp,m = 77,831 + 0,130 × T – 6,289 × T-2, where T is absolute temperature, . Thermodynamic characteristics of Li3FeN2 were determined as next: entropy S0298 = 116.2 J mol-1 K-1, molar enthalpy of dissolution ΔdHLFN = ˗ 206,537 ± 2,8 kJ mol−1, the standard enthalpy of formation ΔfH0 = ˗ 291.331 ± 5.7 kJ mol−1, entropy S0298 = 113.2 J mol-1 K-1 (Neumann-Kopp rule) and 116.2 J mol-1 K-1 (W.Herz rule), the standard Gibbs free energy of formation ∆f G0298 = ˗276,7 kJ mol-1.
ARTICLE | doi:10.20944/preprints202206.0291.v1
Subject: Physical Sciences, Optics Keywords: 2D materials; integrated optics; photo-thermal changes; graphene oxide
Online: 21 June 2022 (08:06:34 CEST)
We experimentally investigate power-sensitive photo-thermal tuning (PTT) of two-dimensional (2D) graphene oxide (GO) films coated on integrated optical waveguides. We measure the light power thresholds for reversible and permanent GO reduction in silicon nitride (SiN) waveguides integrated with 1 and 2 layers of GO. Raman spectra at different positions of a hybrid waveguide with permanently reduced GO are characterized, verifying the inhomogeneous GO reduction along the direction of light propagation through the waveguide. The differences between the PTT induced by a continuous-wave laser and a pulsed laser are also compared, confirming that the PTT mainly depend on the average input power. These results reveal interesting features for 2D GO films coated on integrated optical waveguides, which are of fundamental importance for the control and engineering of GO’s properties in hybrid integrated photonic devices.
REVIEW | doi:10.20944/preprints201905.0256.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: electric field screen; pest management; photo-selective nets; whiteflies
Online: 21 May 2019 (09:08:24 CEST)
Applied electrostatic engineering can be used to construct greenhouses that prevent entry of insect pests. Two types of electric field screen were used to exclude pests from the greenhouse: single- and double-charged dipolar electric field screens (S- and D-screen, respectively). The S-screen consisted of iron insulated conductor wires (ICWs) arrayed in parallel (ICW-layer), a grounded metal net on either side of the ICW-layer, and a direct current voltage generator. S-screens were attached to the side windows of the greenhouse to repel whiteflies (Bemisia tabaci) that approached the nets. The D-screen was installed in a small anteroom at the greenhouse entrance to capture whiteflies entering through it. The ICW-layers of the D-screen were oppositely charged with equal voltages and arrayed alternately, and an insulator board or grounded metal net was placed on one side of the ICW-layer. The ICW-layers captured whiteflies entering the electric field of the double-charged dipolar electric field. Three screens equipped with yellow or gray boards or a grounded metal net were installed in the anteroom based on the airflow inside the room, as most whiteflies were brought in by air when the door was opened. Two D-screens with boards were useful for directing the airflow toward the wall with the netted D-screen. This screen eliminated the insects and the pest-free air was circulated inside the greenhouse. The D-screen with the yellow board attracted the whiteflies and was effective for trapping them when there was no wind. Our method kept the greenhouse pest-free throughout the entire period of tomato (Solanum lycopersicum) cultivation.
ARTICLE | doi:10.20944/preprints201809.0447.v1
Subject: Chemistry, Applied Chemistry Keywords: ZnO; photo-oxidation; 4-chlorophenol; CuxO-ZnO catalyst; photodeposition
Online: 22 September 2018 (23:38:14 CEST)
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.
REVIEW | doi:10.20944/preprints201809.0072.v1
Subject: Engineering, Mechanical Engineering Keywords: photo-catalysis, suspension plasma spray, thermal plasma, titanium oxide
Online: 4 September 2018 (15:08:47 CEST)
As a photo-catalytic titanium oxide film deposition process, thermal spray is hoped to be utilized practically on the condition that it is relatively easy to deposit anatase rich films. However, because of its high equipment and feedstock powder costs, it is very difficult to introduce thermal spray equipment into small companies. In this study, to develop a low cost thermal spray system, low power atmospheric suspension plasma spray equipment with titanium hydroxide suspension created by hydrolysis of titanium tetra iso butoxide using Ar, N2 as working gases. For avoiding sedimentation of the hydroxide particles in the suspension, mechanical milling of the suspension was conducted to create colloidal suspension before using it as feedstock. Moreover, an Ultrasonic wave container was used to keep the suspension particles moving while the spray process was conducted. After the film deposition, with As for the coating, anatase rich TiO2 ﬁlm could be obtained. For characterization of the film, microstructure observation by optical microscope and X-ray diffraction was carried out. Consequently, by creation of colloidal suspension, deposition could be conducted without sedimentation of the hydroxide particle in the suspension during operation. Besides, it was proved the film had enough photo-catalytic property to decolor methylene-blue droplet
ARTICLE | doi:10.20944/preprints202106.0411.v1
Subject: Chemistry, Analytical Chemistry Keywords: lithium-ion battery; silicon nanoparticles; nitrogen-doped graphene; carbon nanofibers; anode material
Online: 15 June 2021 (14:48:47 CEST)
We report a self-assembly synthesis of silicon nanoparticles/nitrogen-doped reduced graphene oxide/ carbon nanofiber (Si@N-doped rGO/CNF) composites as potential high-performance anodes for rechargeable lithium-ion batteries (LIB) through the electrostatic attraction between amino and carboxyl groups. Nitrogen atoms generate a large number of vacancies or defects on the graphite plane, providing additional transmission channels for the diffusion of lithium ions, and improving the conductivity of the electrode. Carbon nanofiber (CNF) can help maintain the stability of the electrode structure and prevent silicon nanoparticles from falling off the electrode, prevent silicon nanoparticles from being directly exposed to the electrolyte, and can form a stable solid electrolyte interface (SEI) film. The three-dimensional conductive structure composed of Si, nitrogen atom-doped reduced graphene oxide (N-doped rGO), and CNF can effectively buffer the volume changes of silicon nanoparticles, shorten the transmission distance of lithium ions (Li+) and electrons, and make the electrode have good conductivity and stability in mechanical properties. In addition, compared with the Si@N-doped rGO and Si/rGO/CNF composite electrode, the Si@N-doped rGO/CNF composite electrode shows good cycle performance and rate capability, and its reversible specific capacity can reach 1418.8 mAh/g. The capacity retention rate is 64.7%, and the coulomb efficiency is 95%.
ARTICLE | doi:10.20944/preprints202102.0565.v1
Subject: Engineering, Automotive Engineering Keywords: Anode Baking Furnaces; κ −turbulence flow model; mesh generation; Computational Fluid Dynamics
Online: 25 February 2021 (07:41:46 CET)
Turbulent flow is the first and fundamental physical phenomena to evaluate when optimising cost and reducing emissions from an Anode Baking Furnace (ABF). Gas flow patterns, velocity field, pressure drop, shear stress, and turbulent dissipation rate variables are the main operational parameters to be optimised, considering a specific geometry. Computational Fluid Dynamics (CFD) allows simulating physical phenomena using numerical methods with computer resources. In particular, the finite element method is one of the most used methods to solve the flow equations. This method requires a discretisation of the geometry of the ABF, called mesh. Hence, mesh is the main input to the finite element method. A suitable mesh for applying a discretisation method determines whether the problem can be simulated or not. Generating an appropriate mesh remains a challenge to perform accurate simulations. In this work, a comparison between meshes generated using two mesh generation tools is presented. Results of different study cases are included.
ARTICLE | doi:10.20944/preprints201705.0094.v1
Subject: Materials Science, Nanotechnology Keywords: lithium-ion batteries; anode materials; MnO; co-precipitation; T-shaped microchannel reactor
Online: 11 May 2017 (07:49:10 CEST)
Porous MnO/C microspheres have been successfully fabricated by a fast co-precipitation method in a T-shaped microchannel reactor. The structures, compositions and electrochemical performances of the obtained MnO/C microspheres are characterized by X-ray diffraction, emission scanning electron microscopy, transmission electron microscopy (HRTEM), Brunauer–Emmett–Teller analysis, charge-discharge testing, cyclic voltammograms, and electrochemical impedance spectra. Experimental results reveal that the as-prepared MnO/C, with a specific surface area of 96.66 m2·g–1 and average pore size of 24.37 nm, exhibits excellent electrochemical performance, with a discharge capacity of 655.4 mAh·g–1 after cycling 50 times at 1 C and capacities of 808.3, 743.7, 642.6, 450.1, and 803.1 mAh·g–1 at 0.2, 0.5, 1, 2, and 0.2 C, respectively. Moreover, the controlled method of using a micro-channel reactor, which can produce larger specific surface area porous MnO/C with improved cycling performance by shortening lithium-ion diffusion distances, can be easily applied in real production on a large-scale.
ARTICLE | doi:10.20944/preprints202204.0240.v1
Subject: Engineering, Civil Engineering Keywords: Deep Learning; Aerial photo; Typhoon Faxai; roof damage; detection; classification
Online: 26 April 2022 (10:58:36 CEST)
Following the occurrence of a typhoon, quick damage assessment related to residents can facilitate quick dispatch of house repair and disaster insurance works. Employing a deep learning method, this study used aerial photos of the Chiba prefecture obtained following the Typhoon Faxai in 2019 to automatically detect and evaluate the roof damage. This study comprised three parts: training deep learning model, detecting the roof damage using trained model, and classifying the level of roof damage. The detection object comprised roof outline, blue tarps, and roof completely destroyed. The roofs were divided into three categories: roof without damage, roof with blue tarps and roof completely destroyed. the F value obtained using the proposed method was higher than those obtained using other methods. In addition, it can be further divided into 5 levels from level 0 to 4. Finally, the spatial distribution of the roof damage was analyzed using ArcGIS tools. The proposed method is expected to provide certain reference for the real-time detection of the roof damage after the occurrence of a typhoon.
ARTICLE | doi:10.20944/preprints202107.0274.v1
Subject: Chemistry, Analytical Chemistry Keywords: polymerization kinetics; photoinitiator; free radical polymerization; photo-oxidation; 3D printing.
Online: 12 July 2021 (22:22:54 CEST)
This article presents, for the first time, the kinetics and the general conversion features of free radical polymerization (FRP) in a 3-component system (A/B/N), with [A] being the initiator, and [B] and [N] are additives, based on the proposed mechanism of Rahal et al. Higher FRP can be achieved by additives [B] and [N], via the dual function of (i) regeneration [A], and (ii) generation of extra radicals (R) via the radicals (S' and S) produced by N.The initiator (coumarin) shows a dual photo-oxidation and photo-reduction character for high efficacy. The FRP conversion efficacy (CE) depends not only on the property of the initiator [A], the additives [B] and [N}, but also the types of monomers. For example, when [A]=CoumC, [A]/NPG is more efficient than [A]/Iod, but revserse trend occurs in some monomers. However, 2-component systems (with CE=0% to 80%) are always less efficient than that of 3-component systems (with CE=70% to 86%, in TMPTA). Specific systems with [A]=coumarins, [B]=Iodonium salt, and N=NPG are analyzed. Analytical formulas for the role of each component concentration, light intensity and coupling rates on the conversion efficacy are derived.
COMMUNICATION | doi:10.20944/preprints201906.0278.v1
Subject: Life Sciences, Biophysics Keywords: photosystem II; redox potential; electron transfer; charge separation; photo-inhibition
Online: 27 June 2019 (05:54:13 CEST)
Structural perturbations in the Mn4CaO5 cluster site, an oxygen-evolving complex of photosystem II, such as those induced by Ca2+/Sr2+ exchanges or Ca/Mn-removal have been known to induce long-range positive shifts (+30 mV to +150 mV) in the redox potential of the primary quinone electron acceptor plastoquinone A (QA) located 40 Å distant from the OEC. Here, we reanalyzed the crystal structure of Sr-PSII solved at 2.1 Å and compare it with the native Ca-PSII of 1.9 Å with focus on the acceptor site and report on the possible long-range interactions between the donor, Mn4Ca(Sr)O5 cluster, and acceptor sites.
ARTICLE | doi:10.20944/preprints201811.0285.v1
Subject: Chemistry, Electrochemistry Keywords: proton exchange membrane water electrolysis; anode catalyst; oxygen evolution reaction; iridium; tin oxide
Online: 12 November 2018 (11:03:24 CET)
We have developed IrOx/M-SnO2 (M = Nb, Ta, and Sb) anode catalysts, IrOx nanoparticles uniformly dispersed on M-SnO2 supports with fused-aggregate structures, which make it possible to evolve oxygen efficiently, even with a reduced amount of noble metal (Ir) in proton exchange membrane water electrolysis. Polarization properties of IrOx/M-SnO2 catalysts for the oxygen evolution reaction (OER) were examined at 80 °C in both 0.1 M HClO4 solution (half cell) and a single cell with a Nafion® membrane (thickness = 50 μm). While all catalysts exhibited similar OER activities in the half cell, the cell potential (Ecell) of the single cell was found to decrease with the increasing apparent conductivities (σapp, catalyst) of these catalysts: an Ecell of 1.61 V (voltage efficiency of 92%) at 1 A cm-2 was achieved in a single cell by the use of an IrOx/Sb-SnO2 anode (highest σapp, catalyst) with a low Ir-metal loading of 0.11 mgIr cm-2 and Pt supported on graphitized carbon black (Pt/GCB) as the cathode, with 0.35 mgPt cm−2. In addition to the reduction of the ohmic loss in the anode catalyst layer, the increased electronic conductivity contributed to decreasing the OER overpotential due to the effective utilization of the IrOx nanocatalysts on the M-SnO2 supports, which is an essential factor in improving the performance with low noble metal loadings.
Subject: Social Sciences, Geography Keywords: land degradation; participatory methods; photo elicitation; Sahel; local knowledge; remote sensing
Online: 15 April 2019 (12:45:49 CEST)
Land degradation monitoring and assessment in the Sahel zone has relied substantially on temporal trends of remote sensing-based vegetation indices, which are proxies for the bioproductivity of the land. However, prior studies have shown that negative or positive trends in bioproductivity are not necessarily associated with degradation or improvement of land condition. In this short communication, while acknowledging the contributions of remote sensing-based indices and global-scale datasets to dismantling an outdated desertification narrative, we argue that local land users have much to contribute to our understanding of land degradation, and particularly to ensuring that scientific assessments of degradation capture variables relevant to them. We used the participatory photo elicitation method in three sites in the Senegalese Ferlo in order to elicit local pastoralists’ perspectives on land degradation and identify the indicators that they use to characterize pasture quality, while empowering them to lead the discussion. The discussion revealed indicators far beyond bioproductivity, including livestock performance as well as composition and quality of the herbaceous and woody vegetative cover, invasive species, soil quality and water availability. We found that the pastoralists’ knowledge and interest in the issue could potentially be harnessed more systematically, and at larger scales, in order to build a spatially explicit field-based knowledge base of land degradation complementary to remote sensing-based maps of trends in bioproductivity. Such a dataset could serve as a standalone product or as a reference dataset for development and validation of remote sensing-based indicators.
ARTICLE | doi:10.20944/preprints201805.0472.v1
Subject: Materials Science, Polymers & Plastics Keywords: polymerization theory; photo polymerization kinetic; photoinitiation rate; polymerization efficacy; photodynamic therapy.
Online: 31 May 2018 (11:25:02 CEST)
The kinetics and optimal efficacy conditions of photoinitiated polymerization are theoretically presented. Analytic formulas are derived for the crosslink time, crosslink depth and efficacy function. The roles of photosensitizer (PS) concentration, diffusion depth and light intensity on the polymerization spatial and temporal profiles, for both uniform and non-uniform cases, are presented . For optimal efficacy, a strategy via controlled PS concentration is proposed, where re-supply of PS in high light intensity may achieve a combined-efficacy similar to low light intensity, but has a much faster procedure. A new criterion of efficacy based on the polymerization (crosslink) [strength] and [depth] is introduced.
REVIEW | doi:10.20944/preprints201805.0430.v1
Subject: Chemistry, Organic Chemistry Keywords: stimuli-responsive polymers; synthetic polypeptide; photo-sensitive; self-assembly; morphological transformation
Online: 30 May 2018 (04:52:30 CEST)
Stimuli-responsive polymeric materials have attracted significant attentions in a variety of high-value-added and industrial applications during the past decade. Among various stimuli, light is of particular interest as a stimulus due to its unique advantages such as precisely spatiotemporal control, mild conditions, ease of use, and tunability. In recent years, a lot of effort toward synthesis of biocompatible and biodegradable polypeptide has resulted in many examples of photo-responsive nanoparticles. Depending on the specific photochemistry, those polypeptide derived nano-assemblies are capable of crosslinking, disassembling, or morphing into other shapes upon light irradiation. In this mini-review, we aim to assess the current state of photo-responsive polypeptide based nanomaterials. First, those “smart” nanomaterials will be categorized by their photo-triggered events (i.e., crosslinking, degradation, and isomerization) which are inherently governed by photo-sensitive functionalities including o-nitrobenzyl, coumarin, azobenzene, cinnamyl, and spiropyran. In addition, the properties and applications of those polypeptide nanomaterials will be highlighted as well. Finally, the current challenges and future directions of this subject will be evaluated.
ARTICLE | doi:10.20944/preprints201909.0080.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: photo-voltaic; monocrystalline; energy efficiency; hot-arid climate; smart cities; MATLAB simulations
Online: 7 September 2019 (00:40:23 CEST)
Due to an increase of the monocrystalline PV systems installations, for a drive towards the sustainable smart cities in the hot arid developing country such as Pakistan, pose challenges of the performance and degradation issues. Monocrystalline PV module efficiencies are declining and damaging under the continuous exposure to higher surface day-time temperatures in the different parts of the country. A MATLAB simulations were performed based on the validated mathematical approach. This paper investigates the hot arid surface temperature impacts on the performance of PV modules during the summer and winter seasons in Pakistan. The investigations are performed examining the power generating efficiency of the PV system. This paper also investigates the influence of installations of PV-system in the North, South, East and West regions of Pakistan. It was examined that the northern areas of Pakistan are more suitable for maintaining the long-term durability of the PV system. Investigations are performed for the peak summer and peak winter days. During summer months, cooling strategies have to be implemented to overcome the heating effects whilst reducing degradation effect on installed PV-system.
CONCEPT PAPER | doi:10.20944/preprints201610.0076.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: bio aerosol; Photo Catalytic Oxidation (PCO); hydroxyl; hydrogen peroxide; SPICE; surface sanitizer
Online: 19 October 2016 (10:02:08 CEST)
In this research paper a novel Ultra Violet Photo Catalyst Oxidation (UVPCO) sensor for air and surface sanitization using Common Source (CS) amplifier is presented. The ultra violet photo catalysis is the process in which the highly reactive radicals like H+, OH-and peroxides ions are produced from air in the presence of the ultra violet radiation and photo catalyst. In this process, the free radicals outbreaks the bio aerosols like bacteria, fungus and volatile organic compounds (VOCs) and destroy them. The proposed system is relies on the fast operation of PCS which operates under sub-threshold conditions and reduced computation time. The properties of common source amplifier like very high voltage gain and input output resistance increased the sensitivity as well as stability of the circuit. The system is more user friendly and the outcomes of simulation are fairly in agreement with the theoretical estimation. Keywords: bio aerosol, Photo Catalytic Oxidation (PCO), hydroxyl, hydrogen peroxide, SPICE, surface sanitizer.
ARTICLE | doi:10.20944/preprints202006.0209.v1
Subject: Engineering, Energy & Fuel Technology Keywords: anode maturation time; microbial fuel cell (MFC); linear sweep voltammetry (LSV) polarization; cyclic voltammetry (CV)
Online: 17 June 2020 (08:10:59 CEST)
To obtain an accurate and reproducible experimental results in microbial fuel cell (MFC), it is important to know ‘anode maturation biofilm’ to produce a stable and maximum performance. For this purpose, four single chamber MFCs were tested in this study. The linear sweep voltammetry (LSV) polarization tests illustrated that maximum power densities of three MFCs became stable after 9 weeks. Although there were variations afterwards, such variations were negligible. Average maximum power densities from the 9th to the 17th week were 2,990 mW/m2 (MFC-4), 2,983 mW/m2 (MFC-2), 2,368 mW/m2 (MFC-3) and 837 mW/m2 (MFC-1). Polarization resistance shows that MFC-1 had much larger anode resistance (36.6-85.4 Ω) than the other MFCs (1.7-11.6 Ω). Anodic cyclic voltammetry (CV) shows that current production increased over time and MFC-1 had much smaller current production (24.4 mA) than the other MFCs (31.0-34.9 mA) at 17th week. The increased current production indicates anode biofilm became more mature over time, but overall cell performance did not increased accordingly. Possibly due to the bad inoculation, MFC-1 showed the lowest performance. However, its performance was restored to the initial performance and anode resistance was reduced by 47% at 17th week. This study shows that the optimum anode maturation time is 9 weeks and that bioanode performance is a key factor for MFC performance. This study also shows than LSV polarization and CV tests are accurate and non-destructive measurement methods for diagnosing anode performance.
ARTICLE | doi:10.20944/preprints201808.0168.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: CubeSat; transient luminous events (TLEs); multi-anode photon-multiplier tube (MaPMT); system-on-chip (SoC)
Online: 8 August 2018 (12:31:56 CEST)
The VisionCube is a 2-unit CubeSat developed in-house, of which the primary mission is aimed at detecting the occurrence of transient luminous events in the upper atmosphere and obtaining corresponding images from the low Earth orbit. An on-board TLE observation system of the VisionCube cubesat is designed and developed by incorporating a photon-sensitive MaPMT and a CMOS image sensor. Also, a distinctive TLE observation software which enables detecting the TLEs and capturing images in a timely manner is devised. By taking into account the limited resources of a small CubeSat in size and power, the on-board observation system is developed employing a system-on-chip design architecture by which both hardware and software can be integrated seamlessly. The purpose of this study is to investigate the functionality of the hardware and the validity of the software algorithm to show the on-board system will operate properly with no human intervention during the space operation. To this end, a ground simulation facility is constructed to emulate the space environment of the TLE occurrence using a set of UV LEDs inside a darkbox. Based on the analysis of the spectral and temporal properties of the TLEs, the randomly generated UV LED pulses are opted for verification scenarios for the TLE observation system. The validation results show that the hardware and the software algorithm of the on-board observation system can effectively detect the TLEs and obtain the images during the on-orbit operation.
REVIEW | doi:10.20944/preprints202205.0303.v1
Subject: Chemistry, Electrochemistry Keywords: boron; lithium battery; lithium-ion batteries; cathode; anode; electrolyte; battery thermal management system (BTMS); battery performance
Online: 23 May 2022 (10:57:06 CEST)
Lithium batteries and an increasing focus on CO2 reduction have become an integral part of daily life and business for many people. Boron and boron compounds have been widely studied together in the history and development of lithium batteries. With a broad examination of battery components and systems but a boron-centric approach to raw materials, this review seeks to summarize past and recent studies on the following: which boron compounds are studied in lithium battery, in which parts of lithium batteries, what improvements are offered for battery performance, and what improvement mechanisms can be explained. The uniqueness of boron and its extensive application beyond batteries contextualizes the interesting similarity with studies on batteries. The paper predominantly focuses on lithium-ion batteries (LIBs) but also mentions other lithium batteries. At the end, the article aims to predict prospective trends for future studies that may lead to the successful and extensive use of boron compounds on a commercial scale.
ARTICLE | doi:10.20944/preprints202103.0393.v1
Subject: Engineering, Automotive Engineering Keywords: Carbon anode production; Crack generation; Discrete element method; Failure analysis; Second-order work criterion; Strain localization
Online: 15 March 2021 (13:53:17 CET)
An in-depth study of the failure of granular materials, which is known as a mechanism to generate defects, can reveal the facts about the origin of the imperfections such as cracks in the carbon anodes. The initiation and propagation of the cracks in the carbon anode, especially the horizontal cracks below the stub-holes, reduce the anode efficiency during the electrolysis process. In order to avoid the formation of cracks in the carbon anodes, the failure analysis of coke aggregates can be employed to determine the appropriate recipe and operating conditions. In this paper, it will be shown that a particular failure mode can be responsible for the crack generation in the carbon anodes. The second-order work criterion is employed to analyze the failure of the coke aggregate specimens and the relationships between the second-order work, the kinetic energy, and the instability of the granular material are investigated. In addition, the coke aggregates are modeled by exploiting the discrete element method (DEM) to reveal the micro-mechanical behavior of the dry coke aggregates during the compaction process. The optimal number of particles required for the failure analysis in the DEM simulations is determined. The effects of the confining pressure and the strain rate as two important compaction process parameters on the failure are studied. The results reveal that increasing the confining pressure enhances the probability of the diffusing mode of the failure in the specimen. On the other hand, the increase of strain rate augments the chance of the strain localization mode of the failure in the specimen.
ARTICLE | doi:10.3390/sci1020039
Subject: Keywords: hydrothermal reaction; nanoparticles; Li<sub>2</sub>TiO<sub>3</sub>; anode; ionic transport; lithium batteries
Online: 10 July 2019 (00:00:00 CEST)
Li2TiO3 nanopowders were synthesized by hydrothermal process using anatase TiO2 and LiOH H2O as raw materials. Li2TiO3 crystallizes in the layered monoclinic structure (space group C2/c) with average crystallite size of 34 nm. Morphology, elemental composition and local structure of products were carried out using HRTEM, FESEM, EDS, Raman and FTIR spectroscopy. Transport properties investigated by d.c. (4-probe measurements) and a.c. (complex impedance spectroscopy) show the activation energy of 0.71 and 0.65 eV, respectively. The ionic transport properties of Li+ ions in nanocrystalline Li2TiO3 characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) validate the good electrochemical properties of this anode material for lithium-ion batteries.
ARTICLE | doi:10.20944/preprints201802.0180.v1
Subject: Materials Science, General Materials Science Keywords: lithium-ion batteries, water-based binders; styrene-butadiene rubber (SBR); carboxymethyl cellulose (CMC); silicon; graphite; anode
Online: 27 February 2018 (11:07:11 CET)
Cycling reliability is crucial for Si-based materials due to severe volume change during cycles that results in the fast capacity fading. Though the binder only occupies a very low amount of the total mass of anodes, it is proved to perform a key parameter to improve the cycle performance of Si-based anodes. Because they are eco-friendly and cost saving, water-based binders styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC) are regarded as the better binder to substitute Poly (vinylidene difluoride) (PVDF) as the binder for Si-based anode. In this study, the anodes are fabricated by simply mixing the active materials (naso Si, graphite and conductive additive) together and using the mixture of SBR and CMC as a binder. The results showed that the retention capacities of the anodes are more than 440 mAh/g after 400 cycles. It indicates that it is an easy and simple way to make high performance anodes.
ARTICLE | doi:10.20944/preprints201907.0160.v1
Subject: Chemistry, Chemical Engineering Keywords: solar thermal systems; phase change materials; thermoplastic elastomer; mechanical property; photo-thermal performance
Online: 11 July 2019 (11:54:58 CEST)
Traditional phase change composites usually suffer poor mechanical property and easy collapsing in the phase changing process. Herein, a highly flexible phase change composite is fabricated using thermoplastic elastomer as the basic gel and the expanded graphite/paraffin as the filler. This new phase change composite shows a tensile strength of 2.1 MPa and a breaking elongation of 220%. It has a melting enthalpy of 145.4 J•g-1 and a thermal conductivity of 2.2 W•m-1•K-1 with 70% of expanded graphite/paraffin. The thermoplastic elastomer based phase change composite exhibits great reversible property after 200 heating/cooling cycles. This flexible phase change composite demonstrates good photo-thermal energy charging/discharging property and shows great potential to be applied in the solar thermal energy systems.
Subject: Chemistry, Analytical Chemistry Keywords: Verteporfin; Photosensitizer; Photo Dynamic Therapy; PDT; Photofragments; Photofragmentation channels; Mass Spectrometry; Laser Spectroscopy; Photolysis
Online: 16 October 2020 (14:39:28 CEST)
Verteporfin, a free base benzoporphyrin derivative monoacid ring A, is a photosensitizing drug for photodynamic therapy (PDT) used in the treatment of the wet form of macular degeneration and activated by red light of 689 nm. Here, we present the first direct study of its photofragmentation channels in the gas-phase, conducted using a laser interfaced mass spectrometer across a broad photoexcitation range from 250-790 nm. The photofragmentation channels are compared with the collision-induced dissociation (CID) products revealing similar dissociation pathways characterized by the loss of the carboxyl and ester groups. Complementary solution-phase photolysis experiments indicate that photobleaching occurs in verteporfin in acetonitrile; a notable conclusion, as photoinduced activity in Verteporfin was not thought to occur in homogenous solvent conditions. These results provide unique new information on the thermal break-down products and photoproducts of this light-triggered drug.
ARTICLE | doi:10.20944/preprints201911.0087.v1
Subject: Engineering, Mechanical Engineering Keywords: fluorescence recovery after photo bleaching (FRAP); diffusion coefficient; electric charge; Poly-DADMAC; 3D hydrogel
Online: 8 November 2019 (04:16:49 CET)
The diffusion coefficients of ions are measured in a microchip filled with a cationic charged 3D hydrogel in order to study the effect of cationic charged 3D hydrogel on the diffusivity of ions. In this study, poly-diallyl-dimethyl-ammoniumchloride (poly-DADMAC) is used to produce a 3D hydrogel. Four different fluorophores are used in the 3D hydrogel rhodamine 6G, rhodamine-BSA, fluorescein isothio-cyanate (FITC) and FITC-BSA. The rhodamine 6G and rhodamine-BSA are positively charged (cations), while fluorescein isothio-cyanate (FITC) and FITC-BSA are negatively charged (anions). Two widely used techniques which are short time diffusivity measurement technique and long time diffusivity measurement techniques are used to measure the diffusion coefficients. For the short time measurement, Fluorescence recovery after photo-bleaching (FRAP) is used by a 3D confocal microscope. For the long time measurement, fluorescence images are taken for 11 days to observe a pure diffusivity without any convective movement. As a result, the diffusivity of the cations was found to be lower than that of the anions in the cationic charged hydrogel.
REVIEW | doi:10.20944/preprints201811.0262.v1
Subject: Materials Science, Nanotechnology Keywords: carbon nanotubes; gas sensors; bio-sensors; photo-sensors; photodetectors; pressure sensors; field effect transistor
Online: 12 November 2018 (04:44:28 CET)
Carbon nanotubes have been attracting considerable interest among material scientists, physicists, chemists and engineers for almost 30 years. Owing to their high aspect ratio, coupled with remarkable mechanical, electronic and thermal properties, carbon nanotubes have found application in diverse fields. In this review, we will cover the work on carbon nanotubes used for sensing applications. In particular, we will see examples where carbon nanotubes act as main players in devices sensing biomolecules, gas, light or pressure changes. Furthermore, we will discuss how to improve the performance of carbon nanotube-based sensors after proper modification.
ARTICLE | doi:10.20944/preprints202201.0446.v2
Subject: Chemistry, Applied Chemistry Keywords: photo-polymerization kinetics; monomer conversion; metal composited; enhancement effects; curing depth; 3D printing; addative manufacturing
Online: 7 February 2022 (12:52:53 CET)
This article presents, for the first time, the efficacy and curing depth analysis of photo-thermal dual polymerization in metal (Fe) polymer composites for 3D printing of a 3-component (A/B/M) system based on the proposed mechanism of our group, in which the co initiators A and B are Irgacure-369, and charge-transfer complexes (CTC), respectively; and the monomer M is filled by Fe. Our formulas show the depth of curing (Zc) is an increasing function of the light intensity, but a decreasing function of the Fe and photoinitiator concentrations. Zc is enhanced by the additive [B] which produces extra thermal radical for polymerization under high temperature. The heat (or temperature) increase in the system has two components : (i) due to the light absorption of Fe filler, and (ii) heat released from the exothermic photopolymerization of the monomer. The heat is transported to the additive (or co-initiator) [B] to produce extra radical R' and enhance the monomer conversion function (CF). The Fe filler leads to temperature increase, but also limits the light penetration leading to lower CF and Zc, which could be overcome by the additive initiator [B] in thick polymers. Optimal Fe for maximal CF and Zc are explored theoretically.
ARTICLE | doi:10.20944/preprints202105.0724.v1
Subject: Chemistry, Analytical Chemistry Keywords: BODIPY-based photosensitizers; functionalized silica nanoparticles; folic acid; PEG; photodynamic therapy; HeLa cells; (photo) toxicity
Online: 31 May 2021 (09:58:40 CEST)
BODIPY dyes have recently raised attention as potential photosensitizers. In this work, commercial and novel photosensitizers (PSs) based on BODIPY chromophores (haloBODIPYs and orthogonal dimers strategically designed with intense bands in the blue, green or red region of the Visible spectra and high singlet oxygen production) were covalently linked to mesoporous silica nanoparticles (MSNs) further functionalized with PEG and folic acid (FA). MSNs of approximately 50 nm in size with different functional groups were synthesized to allow multiple alternatives of PS-PEG-FA decoration of their external surface. Different combinations varying the type of PS (commercial Rose Bengal, Thionine and Chlorine e6 or custom-made BODIPY-based), the linkage design and the length of PEG are detailed. All the nanosystems were physicochemically characterized (morphology, diameter, size distribution and PS loaded amount) and photophysically studied (absorption capacity, fluorescence efficiency, and singlet oxygen production) in suspension. For the most promising PS-PEG-FA silica nanoplatforms, the biocompatibility in dark conditions and the phototoxicity under suitable irradiation wavelengths (blue, green, or red) at regulated light doses (10-15 J/cm2) were compared with PSs free in solution in HeLa cells in vitro.
REVIEW | doi:10.20944/preprints202102.0088.v1
Subject: Biology, Anatomy & Morphology Keywords: Microbiome; sound exposure; noise pollution; microalgae; artificial light; bioacoustics; ecosystem health; light pollution; photo-sonic restoration hypothesis
Online: 2 February 2021 (13:12:10 CET)
Globally, anthropogenic sound and artificial light pollution have increased to alarming levels. Evidence suggests that these can disrupt critical processes that impact ecosystems and human health. However, limited focus has been given to the potential effects of sound and artificial light pollution on microbiomes. Microbial communities are the foundations of our ecosystems. They are essential for human health and provide myriad ecosystem services. Therefore, disruption to microbiomes by anthropogenic sound and artificial light could have important ecological and human health implications. In this mini-review, we provide a critical appraisal of available scientific literature on the effects of anthropogenic sound and light exposure on microorganisms and discuss the potential ecological and human health implications. Our mini-review shows that a limited number of studies have been carried out to investigate the effects of anthropogenic sound and light pollution on microbiomes. However, based on these studies, it is evident that anthropogenic sound and light pollution have the potential to significantly influence ecosystems and human health via microbial interactions. Many of the studies suffered from modest sample sizes, suboptimal experiments designs, and some of the bioinformatics approaches used are now outdated. These factors should be improved in future studies. This is an emerging and severely underexplored area of research that could have important implications for global ecosystems and public health. Finally, we also propose the photo-sonic restoration hypothesis: does restoring natural levels of light and sound help to restore microbiomes and ecosystem stability?
DATA DESCRIPTOR | doi:10.20944/preprints201908.0232.v1
Subject: Earth Sciences, Environmental Sciences Keywords: citizen science; crowdsourced data; ecotourism; natural Resource management; social media; photo-elicitation; photovoice; wildlife conservation; wildlife tourism
Online: 22 August 2019 (11:32:08 CEST)
This data descriptor summarizes the process applied and data gathered from 50 publications/papers reporting on the use of photography generated by tourists, tour operators and members of the public, with a particular focus on the crowdsourcing of photographs through online platforms and social networking sites (SNSs) as a method of research for wildlife conservation and ecotourism. The papers were collected in a systematic literature review to inform a pilot study of the feasibility of using SNSs to crowdsource georeferenced photographs of endangered Bornean Pygmy Elephants (Elephas maximus borneensis) taken by ecotourists along the Lower Kinabatangan River region of Sabah, Malaysia. Papers were sourced using the Murdoch University Findit online-search tool to search over 100 databases, including Proquest, Scopus and Web of Science. The criteria for a paper to be included in the review (and shared via the dataset attached to this this data descriptor) were that it was peer-reviewed, published in English, between 1997 and the 31 December 2017, had the full text accessible online and reported on a study or studies that utilized photographs that tourists, tour operators and/or members of the public generated and shared via SNSs or online platforms.
ARTICLE | doi:10.20944/preprints201908.0226.v1
Subject: Earth Sciences, Environmental Sciences Keywords: crowdsourcing; citizen science; ecotourism; Facebook; Flickr; photo-elicitation; Instagram; photovoice; social media; social networking sites; Twitter; wildlife conservation
Online: 21 August 2019 (10:34:58 CEST)
The first two decades of the 21st-century have seen the emergence of the modern citizen science movement, increased demand for niche eco and wildlife tourism experiences, and the willingness of people to voluntarily share information and photographs online. To varying extents, the rapid growth of these three phenomena has been driven by the availability of portable smart devices, access to the Web 2.0 internet from almost anywhere on the planet, and the development of applications and services, including social media/networking sites (SNSs). In addition, the number of peer-reviewed publications that explore how text and images shared on SNSs can be data-mined for academic research has surged in recent years. This systematic quantitative review has two goals. The first goal is to provide an oversight of how the photographs that ecotourists share online are contributing to wildlife tourism research. The second goal is to promote the emerging photovoice technique as a theoretical context for social research based on the photographs and comments that ecotourists share on SNSs. From the perspectives of community benefits, conservation behaviours, and environmental education, there are many similarities between authentic ecotourism experiences and quality ecological citizen science programs. Much of the literature regarding the theory and practice of citizen science reports on the difficulties of attracting, training, motivating and retaining community members. The synthesis of this review is that crowdsourcing wildlife and tourism data from comments and photographs that ecotourists share on SNSs is a credible method of research that provides a self-replenishing pool of citizen scientists.
ARTICLE | doi:10.20944/preprints201701.0095.v1
Subject: Chemistry, Applied Chemistry Keywords: polymeric composite; surface initiated atom transfer radical polymerization; photo-induced; living radical polymerization; metal-free atom transfer radical polymerization
Online: 22 January 2017 (04:56:44 CET)
Surface initiated atom transfer radical polymerization (SI-ATRP) is one of the most versatile technique to modify the surface properties of material. Recent developed metal free SI-ATRP makes such technique more widely applicable. Herein photo-induced metal-free SI-ATRP of methacrylates, such as methyl methacrylate, N-isopropanyl acrylamide, and N,N- dimethylaminoethyl methacrylate, on the surface of SBA-15 was reported to fabricate organic-inorganic hybrid materials. SBA-15 based polymeric composite with adjustable graft ratio was obtained. The structure evolution during the SI-ATRP modification of SBA-15 was monitored and verified by FT-IR, XPS, TGA, BET, and TEM. The obtained polymeric composite showed enhanced adsorption ability for the model compound toluene in aqueous. This procedure provides a low cost, ready availability, and facile modification way to synthesize the polymeric composites without the contamination of metal.
REVIEW | doi:10.20944/preprints201811.0077.v2
Subject: Materials Science, General Materials Science Keywords: polymer exchange membrane; electrocatalysts; noble metals; earth abundant elements; water splitting; acidic environment; oxygen evolution reaction; hydrogen evolution reaction; anode and cathode electrodes
Online: 12 November 2018 (06:55:56 CET)
Water electrolysis provides efficient and cost-effective production of hydrogen from renewable energy. Currently, the oxidation half-cell reaction relies on noble-metal catalysts, impeding widespread application. In order to adopt water electrolyzers as the main hydrogen production systems, it is critical to develop inexpensive and earth-abundant catalysts. This review discusses the proton exchange membrane (PEM) water electrolysis (WE) and the progress in replacing the noble-metal catalysts with earth-abundant ones. Researchers within this field are aiming to improve the efficiency and stability of earth-abundant catalysts (EACs), as well as to discover new ones. The latter is particularly important for the oxygen evolution reaction (OER) under acidic media, where the only stable and efficient catalysts are noble-metal oxides, such as IrOx and RuOx. On the other hand, there is significant progress on EACs for the hydrogen evolution reaction (HER) in acidic conditions, but how many of these EACs have been used in PEM WEs and tested under realistic conditions? What is the current status on the development of EACs for the OER? These are the two main questions this review addresses.
ARTICLE | doi:10.20944/preprints202108.0362.v1
Subject: Physical Sciences, Condensed Matter Physics Keywords: silicon; nanogranular; nanoparticle; porous; void; thin film; laser heating; photo-thermal; temperature; Raman; phonons; heat conduction; phase transition; finite element modeling
Online: 17 August 2021 (10:45:12 CEST)
We present the results on photothermal (PT) and heat conductive properties of nanogranular silicon (Si) films synthesized by evaporation of colloidal droplets (drop-casting) of 100 ± 50 nm sized crystalline Si nanoparticles (NP) deposited on glass substrates. Finite difference time domain (FDTD) and finite element mesh (FEM) modeling of absorbed light intensity and photo-induced spatial temperature distribution across the Si NP films were well correlated with the local temperatures measured by micro-Raman spectroscopy and used for determination of heat conductivities in the films of various thicknesses. Cubic-to-hexagonal phase transition in these films caused by laser heating was found to be heavily influenced by the film thickness and heat conductive properties of glass substrate, on which the films were deposited. Heat conductivities across the drop-casted Si nanogranular films were found to be in the range of lowest heat conductivities of other types of nanostructurely voided Si films due to enhanced phonon scattering across inherently voided topology, weak NP-NP and NP-substrate interface bonding within nanogranular Si films.
ARTICLE | doi:10.20944/preprints202207.0386.v1
Subject: Engineering, Control & Systems Engineering Keywords: Maximum Power Point Tracking (MPPT); Improved Particle Swarm Optimization (IPSO); photo-voltaic (PV); Neural Network and Perturb & Observe method (NN-P&O)
Online: 26 July 2022 (05:41:24 CEST)
This article analyzes and compares the integration of two different maximum power point tracking (MPPT) control methods, which are tested under partial shading and fast ramp conditions. These MPPT methods are designed by Improved Particle Swarm Optimization (IPSO) and a combination technique between Neural Network and Perturb & Observe method (NN_P&O). These two methods are implemented and simulated for photovoltaic systems (PV), where various system responses, such as: voltage and power are obtained. The MPPT techniques were simulated using Matlab/Simulink environment. A comparison of the performance of IPSO and NN_P&O algorithms is carried out to confirm the best accomplishment of the two methods in terms of speed, accuracy and simplicity.
ARTICLE | doi:10.20944/preprints202208.0409.v1
Subject: Physical Sciences, General & Theoretical Physics Keywords: Black Hole has no hair; Electromagnetic field of a charged black hole, Electromagnetic field of a supported charge in gravitational field; electric fields follow photo trajectories in gravitational field
Online: 24 August 2022 (04:49:54 CEST)
Using the principle of equivalence, it has recently been shown that the electrostatic field lines of a charge, stationary in the gravitational field, bend exactly like the trajectories of photons emitted isotropically from a source at the charge location and that the fraction of electric flux crossing a surface `below' or `above' the charge is exactly similar to the fraction of photon trajectories intersecting these surfaces, with more flux in the downward direction than upward. As one goes much deeper in the gravitational field, all electric field lines increasingly point in the vertically downward direction as is also the case for a stream of photons. Since photon trajectories as well as electric field lines, at any location in the gravitational field, are affected by the local space-time curvature an inference can be drawn that this parallel between the photon trajectories and the electric field lines is a general result. We could then apply these results in the external gravitational field of a black hole, where the trajectories of photons in the gravitational field are already well-known and the behaviour of electric field lines of a stationary charge could be inferred therefrom. Accordingly, we show that the electric field through an external spherical surface surrounding the black hole steadily reduces as the charge location approaches the event horizon (Schwarzschild radius), and like photons from a source inside the Schwarzschild radius cannot escape outside, the electric field lines of a charge within the black hole too remain trapped inside the event horizon. From this one arrives at a conclusion that, contrary to the conventional wisdom, the electric charge contained inside a static black hole cannot be detected or inferred by an external observer. A black hole, said to have no hair with the only external identifying characteristics being mass, electric charge, and angular momentum, is therefore all the more `hairless', as even its charge cannot be ascertained. The derivation of the Reissner-Nordström metric, supposedly describing the gravitational field of a static charged black hole, presumes an external stress-energy tensor of the electrostatic field, as per Gauss law, even for the charges contained within the black hole. However, the absence of electric flux external to a static charged black hole implies that such a charged black hole is not described correctly by the Reissner-Nordström metric and the consequential peculiarities of the space-time geometry, leading in specific cases to the idea of a naked intrinsic singularity and a need for the ``cosmic censorship'' hypothesis, also do not arise here.
HYPOTHESIS | doi:10.20944/preprints202003.0419.v9
Subject: Life Sciences, Molecular Biology Keywords: ATP hypothesis; origin of genetic code; life’s building block; probiotic “soup”; coevolution; biochemical system; missing “matchmaker”; energy transformation; informatization; structuralization; precellular selection; photo- chemical origin of life; virus; anti-life form; 2019-nCoV
Online: 11 September 2020 (08:39:39 CEST)
A plenty of theories on the origin of genetic codes have been proposed so far, yet all ignored the energetic driving force, its relation to the biochemical system, and most importantly, the missing “matchmaker” between proteins and nucleic acids. Here, a new hypothesis is proposed, according to which ATP is at the origin of the primordial genetic code by driving the coevolution of the genetic code with the pristine biochemical system. This hypothesis aims to show how the genetic code was produced e.g. by photochemical reactions in a protocell that derived from a lipid vesicle enclosing various life’s building blocks (e.g. nucleotides and peptides). At extant cell, ATP is the only energetic product of photosynthesis, and is at the energetic heart of the biochemical systems. ATP could energetically form and elongate chains of both polynucleotides and polypeptides, thus acting a “matchmaker” between these two bio-polymers and eventually mediating precellular biochemical innovation from energy transformation to informatization. ATP was not the only one that could drive the formation of polynucleotides and polypeptides, but favored by precellular selection. The protocell innovated a photosynthesis system to produce ATP efficiently and regularly with the aids of proteins and RNA/DNA. The completion of permanently recording the genetic information by DNA marked the dawn of cellular life operated by Darwinian evolution. The ATP hypothesis assumes or supports the photochemical origin of life, shedding light on the origins of both photosynthetic and biochemical systems, which remains largely unknown thus far. Based on ATP hypothesis, virus (like the new coronavirus) could not be the earliest life on Earth, as it has neither biochemical systems nor lipid bilayer membrane that provided relatively isolated environment for the development of protobiochemical reactions, although it owns the genetic code of a cellular life. Virus could not be a bridge between life and non-life, but is an anti-life substance, as it depletes cellular material for its own replication, and then spreads by destroying the host cells. It can be imagined that if cellular life are completely wiped out by the virus, the complete destruction of life on Earth would be inevitable.