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Showing records 3082 to 3106 of 4208. [First] Page: 1 121 122 123 124 125 126 127 128 129 Last
Development of a Contactless Conductivity Sensor in Flowing Micro Systems for Cerium Nitrate
Martin Zürn, Thomas Hanemann
February 23, 2023 (v1)
Subject: Materials
Keywords: C4D-Sensor, cerium nitrate, constant flow, contactless concentration measurement, contactless conductivity measurement
Impedance spectroscopy has a high potential to detect chemical reactions in flowing systems. In this work, the approach using impedance spectroscopy as a possible analytical tool for a continuous hydrothermal syntheses (CHTS) is presented. With the CHTS-process, it is possible to produce metalloxide nanoparticles with a close particle size distribution and specific surface properties. For this, it is necessary to evaluate the electrode geometry, frequency and other factors influencing the impedance with respect to concentration measurements. In case of frequency-sweep measurements possible electrode geometries for C4D-Sensors (capacitively coupled contactless conductivity detection) are evaluated. Then distinguishability and reproducibility are tested applying titration measurements to show the ability for concentration detection in constant flow systems. The possibility to measure concentration changes in flowing systems in a reproducible and fast manner as well as with high distingui... [more]
Fast Degradation of Tetracycline and Ciprofloxacin in Municipal Water under Hydrodynamic Cavitation/Plasma with CeO2 Nanocatalyst
Vladimir Abramov, Anna Abramova, Vadim Bayazitov, Svetlana Kameneva, Varvara Veselova, Daniil Kozlov, Madina Sozarukova, Alexander Baranchikov, Igor Fedulov, Roman Nikonov, Giancarlo Cravotto
February 23, 2023 (v1)
Subject: Materials
Keywords: active radicals, advanced oxidation process, antibiotic, catalytic oxidation, ceria, chemiluminescence, drug residue contamination, osmosis, retentate, sonoplasma
Although water contamination with drug residues is a threat to public health, there are currently barely any effective methods of purifying water from pharmaceutical substances. In this study, continuous-flow sonoplasma treatment was used for the complete degradation of tetracycline and ciprofloxacin in polluted municipal water. The addition of CeO2 nanoparticles as catalysts significantly increased the degradation rate of the antibiotics, and a degradation degree of 70% was achieved. The presence of reactive oxygen species in the CeO2-nanoparticle-containing sonoplasma-treated system was experimentally proven for the first time using the chemiluminescence technique.
Hydrogen Production in Catalytic Membrane Reactors Based on Porous Ceramic Converters
A. S. Fedotov, M. V. Tsodikov, A. B. Yaroslavtsev
February 23, 2023 (v1)
Subject: Materials
Keywords: catalytic converters, Fuel Cells, heterogeneous catalysis, hydrocarbons, Hydrogen, porous ceramics, reforming, self-propagating high-temperature synthesis, synthesis gas
This article presents the results of the development of membrane-catalytic methods for obtaining purified hydrogen of various degrees of purity required for feeding high-, medium-, and low-temperature fuel cells. In order to conduct this, porous ceramic catalytic converters were obtained using self-propagating high-temperature synthesis. These converters are suitable for high-speed processes for producing synthesis gas with different carbon monoxide content (0.08−0.1 vol. %), which can be used to feed fuel cells of various types. Using a hybrid catalytic membrane reactor, in which the stage of catalytic conversion of organic substrates was combined with the stage of selective extraction of ultrapure hydrogen (content of H2 was not less than 99.9999 vol. %) from the reaction zone, combined carbon dioxide and steam reforming of organic substrates of various origins were carried out. The result of the work was the creation of a prototype of a small-sized electric generator plant in which... [more]
Investigation on Impact Strength of Friction Stud Welded AA6061-B4C Composite/AISI 1030 Steel Joints in Inert Gas Atmosphere
Navasingh Rajesh Jesudoss Hynes, Selvaraj Raja, Ramakrishnan Tharmaraj, Michael Brykov, Antoaneta Ene
February 23, 2023 (v1)
Subject: Materials
Keywords: dissimilar materials, friction stud welding, inert atmospheric condition, mechanical properties, scanning electron microscope
A more contemporary variation of the friction welding procedure, friction stud welding, is promising for military, space, automotive and naval applications. The joining of steel/aluminium matrix composite joints has been crucial in many of these contemporary applications. In all of these applications, the strength of the dissimilar joint is a critical consideration. Heat-affected zones arise because of the heterogeneous temperature distribution and change in thermal characteristics, which weaken the strength of the joints between different materials. The presence of oxygen in the weld interfacial region of the dissimilar joint is detrimental to its strength and integrity. Hence, a new method that can strengthen the dissimilar joint is adopted in the current work. In the friction stud-welding machine, an additional set up is integrated for providing an inert atmospheric condition during the welding process. Microstructural analysis shows that an inert atmosphere is helpful to get rid of... [more]
Antibacterial, Antifungal, and Antibiotic Adsorption Properties of Graphene-Modified Nonwoven Materials for Application in Wastewater Treatment Plants
Igor Kogut, Friederike Armbruster, Daniel Polak, Sandeep Kaur, Stephan Hussy, Tobias Thiem, Anja Gerhardts, Maciej Szwast
February 23, 2023 (v1)
Subject: Materials
Keywords: Adsorption, antibacterial, antifungal, graphene, nonwovens
The utilization of adsorptive nonwovens as a pretreatment unit may lead to novel, cost-efficient wastewater treatment technologies with remarkable properties for environmental protection, such as efficient adsorption of antibiotics. This paper uses graphene-modified nonwoven (GMN) to examine (i) how the adsorption of tetracycline (TCY)—especially since this antibiotic is frequently detected in the environment—takes place on an environmentally relevant concentration scale, and (ii) what factors influence the antibacterial and antifungal properties profile of this material class. This study demonstrates that combining graphene particles with commercial textile auxiliaries clearly enhances the antibacterial and antifungal properties of the modified nonwoven materials. The enzyme-linked immunosorbent assay (ELISA) was used to detect the TCY residues at ng/mL scale. The adsorption results follow Henry and Redlich−Peterson isotherms and emphasize the adsorption process at low concentration l... [more]
Hazardous Waste Advanced Management in a Selected Region of Poland
Przydatek Grzegorz, Moșneguțu Emilian, Cabała Adrian, Irimia Oana
February 23, 2023 (v1)
Subject: Materials
Keywords: disposal, generation, hazardous waste, installation, recovery
This article presents a study on hazardous waste management in the Malopolskie region of Poland. The study was based on the information obtained during three years from 2016 to 2018, and following analysis, it was found that in 2016 there was the highest amount of 24,872.13 tons of hazardous waste produced, of which only a three-fold lower amount was disposed of. In this study, various types of hazardous waste were analyzed, including the waste from construction materials and asbestos. The predominant share of 50% of the mass of analyzed hazardous waste was felt on the generated one. Waste recovered in installations had a lower share of 43%, with a significant and favorable increase of over 5000.00 tons. In the context of the correctness of environmental aspects, it was considered an advisable solution that would optimize treatment conditions, and at the same time minimize the costs of hazardous waste management.
Adsorption of NH3 and NO2 Molecules on Sn-Doped and Undoped ZnO (101) Surfaces Using Density Functional Theory
Ratshilumela S. Dima, David Magolego Tshwane, Katekani Shingange, Rosinah Modiba, Nnditshedzeni E. Maluta, Rapela R. Maphanga
February 23, 2023 (v1)
Subject: Materials
Keywords: adsorption energy, density functional theory, doped ZnO, gas sensors
The adsorption and interaction mechanisms of gaseous molecules on ZnO surfaces have received considerable attention because of their technological applications in gas sensing. The adsorption behavior of NH3 and NO2 molecules on undoped and Sn-doped ZnO (101) surfaces was investigated using density functional theory. The current findings revealed that both molecules adsorb via chemisorption rather than physisorption, with all the adsorption energy values found to be negative. The calculated adsorption energy revealed that the adsorption of the NH3 molecule on the bare ZnO surface is more energetically favorable than the adsorption of the NO2 molecule. However, a stable adsorption configuration was discovered for the NO2 molecule on the surface of the Sn-doped ZnO surface. Furthermore, the adsorption on the undoped surface increased the work function, while the adsorption on the doped surface decreased. The charge density redistribution showed charge accumulation and depletion on both ad... [more]
Enhancing the Liquefied Petroleum Gas Sensing Sensitivity of Mn-Ferrite with Vanadium Doping
Omar H. Abd-Elkader, Abdullah M. Al-Enizi, Shoyebmohamad F. Shaikh, Mohd Ubaidullah, Mohamed O. Abdelkader, Nasser Y. Mostafa
February 23, 2023 (v1)
Subject: Materials
Keywords: LPG sensing, magnetic properties, magnetic properties, MnFe2O4, V-doping
Mn-Ferrite with a nanostructure is a highly valuable material in various technological fields, such as electronics, catalysis, and sensors. The proposed article presents the hydrothermal synthesis of Mn-ferrite doped with V (V) ions. The range of the doping level was from 0.0 to x to 0.20. The fluctuation in tetrahedral and octahedral site occupancies with Fe (III), Mn (II), and V (V) ions was coupled to the variation in unit cell dimensions, saturation magnetization, and LPG sensing sensitivity. The total magnetic moment shows a slow decrease with V-doping up to x = 0.1 (Ms = 51.034 emu/g), then sharply decreases with x = 0.2 (Ms = 34.789 emu/g). The dimension of the unit cell increases as x goes up to x = 0.1, then lowers to x = 0.2. As the level of V (V) ion substitution increases, the microstrain (ε) also begins to rise. The ε of a pure MnFe2O4 sample is 3.4 × 10−5, whereas for MnFe2−1.67 xVxO4 (x = 0.2) it increases to 28.5 × 10−5. The differential in ionic sizes between V (V) and... [more]
Physical and Chemical Regularities of Phosphorus and Beryllium Recovery by the Sorbents Based on Acrylic Fiber Impregnated by Iron Hydroxide (III)
Nikolay A. Bezhin, Mariya A. Frolova, Ol’ga N. Kozlovskaia, Evgeniy V. Slizchenko, Iuliia G. Shibetskaia, Ivan G. Tananaev
February 23, 2023 (v1)
Subject: Materials
Keywords: aluminum oxide, beryllium, Fe(OH)3 fiber, isotherm, kinetics, marine radiochemistry, phosphorus, sorption
The paper investigates the physicochemical regularities (kinetics and isotherm) of phosphorus and beryllium recovery by sorbents based on polyacrylonitrile (PAN) fiber and Fe(OH)3 obtained by various methods: PAN or pre-hydrolyzed PAN with precipitation of FeCl3 with ammonia, using ready-made or electrochemically generated Na2FeO4, pre-hydrolyzed PAN treated with an alkaline solution of Na2FeO4, as well as their comparison with granular aluminum oxide. The Langmuir, Freudlich and Dubinin−Radushkevich models show high performance of materials for sorption of stable P and Be used as tracers for the release of 7Be, 32P, and 33P from seawater. The obtained kinetic data are processed using kinetic models of intraparticle diffusion and the pseudo-first-order, pseudo-second-order, and Elovich models. Optimal conditions for obtaining sorbents are established, namely, the effect of NaOH concentration at the stages of preparation on the properties of sorbents based on the PAN fiber and Fe(OH)3 o... [more]
Effects of Calcium Sulfate and Chitosan on Textural Modification and Microstructure of Tofu Made from Lentils (Lens culinaris)
Cheng-Hsun Jao, Chieh-Yi Lin, Chao-Jung Chen, Jung-Feng Hsieh
February 23, 2023 (v1)
Subject: Materials
Keywords: calcium sulfate, chitosan, gel properties, lentil, lentil-based tofu
This study investigated calcium sulfate and chitosan on the textural modification and microstructure of tofu made from lentils. The addition of varying amounts of calcium sulfate (0−12 mM) and chitosan (0−1.0%) into lentil milk could affect the gel properties of lentil-based tofu. The gel properties, including the hardness and cohesiveness, of lentil-based tofu significantly increased with the addition of 12 mM calcium sulfate, exhibiting a slightly discontinuous network structure and a slightly regular pore network. However, the gel properties including hardness and cohesiveness significantly decreased with the addition of 1.0% chitosan, presenting a slightly continuous network structure with pores. Sodium dodecyl sulfate−polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that the aggregation of the vicilin, legumin acidic unit and legumin basic unit proteins in lentil milk was induced both by 12 mM calcium sulfate and 1.0% chitosan. Our results suggested that calcium sulfa... [more]
Custom-Shaped Carbon Xerogel Materials by 3D Printing
Cédric Wolfs, Stéphanie D. Lambert, Alexandre F. Léonard, Julien G. Mahy
February 23, 2023 (v1)
Subject: Materials
Keywords: 3D printing, Carbon, material processing, polymer, sol–gel material
Sol−gel-based carbon xerogels possess very promising properties for pollution abatement, using processes that associate adsorption and on-site electrochemical oxidation. However, combining a high exterior surface area (for efficient diffusion) and a monolithic shape (necessary for electrochemical processes) poses challenges. In this work, the shape of monolithic carbon xerogels was contrived by the use of 3D-printed molds. Several parameters were optimized: the choice of mold design, the choice of plastic, the 3D printer parameters, the solvent, and the process of dissolving the plastic. A design combining fine sticks and plates made of ABS was printed; a sol−gel carbon xerogel monolith was synthesized in it, and the mold was removed by using a combination of acetone and pyrolysis. Dissolving the plastic could be carried out by placing the material on a metallic net and leaving the dissolved ABS to settle. The resulting carbon material exhibits a high exterior surface area and good str... [more]
Chemical Vapor Deposition of Longitudinal Homogeneous Parylene Thin-Films inside Narrow Tubes
David Redka, Milan Buttberg, Gerhard Franz
February 23, 2023 (v1)
Subject: Materials
Keywords: chemical vapor deposition, constant film thickness, deposition model, parylene, sticking coefficient, temperature gradient
The effect of quasi-exponentially decreasing film thicknesses of thin poly-para-xylylene (PPX-N) coatings inside narrow tubes or micro scaled gaps is well known and has been discussed by many authors since the late 1970s. However, for technical applications it is often necessary to provide a longitudinal homogeneous film thickness to ensure the constant properties that are required. In a previous work, it was shown, in principle and for the first time, that a temperature gradient along the tube will effectively counteract the longitudinal decreasing film thickness of the PPX-N coating of the interior wall of a capillary. Therefore, this effect is discussed in theory and the provided model is verified by experiments. Our prediction of a required sticking coefficient curve yields experimentally measured homogeneous film thicknesses and shows a good agreement with the given prognosis. Further, it is shown in theory that there is a maximum achievable homogeneous film thickness in the tube... [more]
Preliminary Study on Size Effect of Fractured Rock Mass with Sand Powder 3D Printing
Wenhai Wang, Yang Zhao, Lishuai Jiang, Jiacheng Zuo, Guangsheng Liu, Hani S. Mitri
February 23, 2023 (v1)
Subject: Materials
Keywords: failure characteristics, fractured rock mass, mechanical properties, mechanism analysis, sand powder 3D printing, size effect
The size effect has a significant effect on the mechanical behavior of rock, thereby fundamentally influencing the stability of rock excavations. The main challenge associated with the experimental research on the size effect of fractured rock mass lies in the difficulty of specimen preparation to represent the influence of size and fracture on the mechanical behavior of the rock material. In order to preliminarily explore the feasibility of 3D printing technology in the field of rock mechanics, fractured rock specimens of different sizes and different fracture characteristics were produced using sand powder 3D printing technology. The uniaxial compression test was combined with the digital image correlation method (DIC) technology to study the influence of the size effect on the mechanical properties and deformation and failure of different fractured specimens. The research finds that: (1) The elastoplastic mechanical characteristics of the sand powder 3D printed specimens are similar... [more]
Recent Advances in the Bioconversion of Waste Straw Biomass with Steam Explosion Technique: A Comprehensive Review
Baige Zhang, Hongzhao Li, Limei Chen, Tianhong Fu, Bingbing Tang, Yongzhou Hao, Jing Li, Zheng Li, Bangxi Zhang, Qing Chen, Chengrong Nie, Zi-Yi You, Chung-Yu Guan, Yutao Peng
February 23, 2023 (v1)
Subject: Materials
Keywords: bioconversion, organic waste valorization, steam explosion, straw biomass
Waste straw biomass is an abundant renewable bioresource raw material on Earth. Its stubborn wooden cellulose structure limits straw lignocellulose bioconversion into value-added products (e.g., biofuel, chemicals, and agricultural products). Compared to physicochemical and other preprocessing techniques, the steam explosion method, as a kind of hydrothermal method, was considered as a practical, eco-friendly, and cost-effective method to overcome the above-mentioned barriers during straw lignocellulose bioconversion. Steam explosion pretreatment of straw lignocellulose can effectively improve the conversion efficiency of producing biofuels and value-added chemicals and is expected to replace fossil fuels and partially replace traditional chemical fertilizers. Although the principles of steam explosion destruction of lignocellulosic structures for bioconversion to liquid fuels and producing solid biofuel were well known, applications of steam explosion in productions of value-added che... [more]
Excellent Antimicrobial, Antioxidant, and Catalytic Activities of Medicinal Plant Aqueous Leaf Extract Derived Silver Nanoparticles
Amna Nisar Khan, Najla Nader Ali Aldowairy, Hajer Saed Saad Alorfi, Mohammad Aslam, Wafa AbuBaker Bawazir, Abdul Hameed, Muhammad Tahir Soomro
February 23, 2023 (v1)
Subject: Materials
Keywords: antibacterial activity, antifungal activity, aqueous extract, Cascabela thevetia, catalytic activity, silver nanoparticles
Antimicrobial resistance is one of the crucial public health challenges that we need to combat. Thus, in concern over public health and the economy, controlling the emergence of infectious diseases is critical worldwide. One of the ways to overcome the influences of antimicrobial resistance is by developing new, efficient, and improved antimicrobial agents. Medicinal plant-derived silver nanoparticles (AgNPs) are under intensive examination for a variety of therapeutic purposes and targeted applications in nanomedicine and nanotechnology. Plants belonging to the genus Thevetia [Syn. Casabela], which is known for its medicinal uses and has rarely been applied for the synthesis of AgNPs, is an attractive alternative as they have a high content of secondary metabolites. Herein, using aqueous leaf extract of Cascabela thevetia, which was locally found in the Makkah region, Saudi Arabia, green synthesis of AgNPs is reported. Active components of Cascabela thevetia aqueous leaf extract were... [more]
The Efficacy of Plant Enzymes Bromelain and Papain as a Tool for Reducing Gluten Immunogenicity from Wheat Bran
Vijole Bradauskiene, Lina Vaiciulyte-Funk, Darius Cernauskas, Reda Dzingeleviciene, Joao P. M. Lima, Aida Bradauskaite, Mihaela Adriana Tita
February 23, 2023 (v1)
Subject: Materials
Keywords: bromelain, hydrolysis, immunogenicity, papain, wheat bran
Gluten-free products made from naturally gluten-free raw materials have an inferior taste and can cause deficiencies in various nutrients, especially non-starch polysaccharides. To address this problem, scientists are searching for new strategies to eliminate harmful gluten from wheat, rye, and barley and to produce balanced products with good organoleptic properties. This study evaluated the possibility of hydrolysing gluten in wheat bran, a by-product obtained after the dry fractionation of wheat, using plant enzymes. The gluten content of wheat bran after treatment with papain, bromelain, and their combination under different hydrolysis conditions was investigated. The amount of gluten was determined using an enzyme-linked immunosorbent assay ELISA R5 and the reduction in immunogenic gliadins was analysed using high-performance reverse phase liquid chromatography. The results of the study showed that 4 h hydrolysis with bromelain and papain reduced the levels of gluten immunogenic c... [more]
Catalytic Oxidation of NO by Ozone over Mn-Ce/Al2O3/TiO2 Catalyst
Hong Shen, Zijun Tang, Xiang Xiao, Haiwen Wu, Hang Zhou, Ping Fang, Dingfang Zhu, Jianhua Ge
February 23, 2023 (v1)
Subject: Materials
Keywords: catalytic oxidation of NO, Mn-Ce-based catalyst, process analysis
In this study, Mn-Ce/Al2O3/TiO2 catalyst prepared by impregnation method was used for synergistic O3 oxidation NO. The catalyst prepared by impregnating Al2O3/TiO2 at a Mn:Ce molar ratio of 4:1 showed the best catalytic activity. The catalyst performance showed that when the molar ratio of Mn:Ce was 4:1 and the volume ratio of O3:NO was 1:4, the removal rate of NO could reach 63%, which could increase the removal rate by 40% compared with that of NO oxidized by O3 alone. BET, XRD, and TEM characterization results showed that when the molar ratio of Mn:Ce was 4:1, the catalyst specific surface area, and pore capacity were the largest. A large amount of MnOx and CeOx were distributed on the catalyst surface. The XPS analysis showed that the oxidation-reduction and oxygen vacancy of Mn (IV)/Mn (III)/Mn (II) and Ce (IV)/Ce (III), had a synergistic effect on the decomposition of O3 into reactive oxygen species(O*), thus improving the catalytic capacity of Mn-Ce/Al2O3/TiO2 catalyst for O3. T... [more]
Synthesis, Characterization and Gas Adsorption of Unfunctionalized and TEPA-Functionalized MSU-2
Xin Ying Lee, Vinosha Viriya, Thiam Leng Chew, Pei Ching Oh, Yit Thai Ong, Chii-Dong Ho, Zeinab Abbas Jawad
February 23, 2023 (v1)
Subject: Materials
Keywords: Adsorption, Carbon Dioxide Capture, functionalization, MSU-2, tetraethylenepentamine
Michigan State University-2 (MSU-2) is notable potential adsorbent for carbon dioxide (CO2) due to its intrinsic properties, which include its highly interconnected three-dimensional (3D) wormhole-like framework structure, high specific surface area, and its large total pore volume, as well as its large amount of surface silanol hydroxyl groups, which facilitate the amine functionalization process. In this study, unfunctionalized MSU-2 was synthesized via a fluoride-assisted two-step process via the solution precipitation method, using Triton X-100 as the surfactant and tetraethylorthosilicate (TEOS) as the silica precursor. Then, the synthesized MSU-2 was functionalized using varying tetraethylenepentamine (TEPA) loadings of 20−60 wt%. The effect of different TEPA loadings on the properties and CO2 adsorption capacity of the MSU samples was investigated. Studies of the CO2 adsorption of the unfunctionalized and TEPA-functionalized MSU-2 samples was conducted at 40 °C and 1 bar of pres... [more]
Degradation of Polyvinyl Chloride (PVC) Waste with Supercritical Water
Maja Čolnik, Petra Kotnik, Željko Knez, Mojca Škerget
February 23, 2023 (v1)
Subject: Materials
Keywords: chemical recycling, plastic waste, polyvinyl chloride, supercritical water
The chemical degradation of PVC waste in SCW between 400 and 425 °C and reaction times from 30 to 60 min was studied. The PVC waste in SCW decomposed into the gas, oil, water soluble, and solid phases. The highest yield of the gas and oil phases was achieved at the temperature of 425 °C after 60 min. By increasing the reaction time at 400 °C, the yield of chloride ions in the aqueous phase increased and reached the maximum at 60 min. The gas and oil phases contained many valuable compounds similar to crude oil. Alkanes and chloroalkanes; alkenes, alicyclic, and aromatic hydrocarbons; as well as alcohols were the main groups of hydrocarbons in the oil phase, while the gas phase contained only light hydrocarbons (C1−C6), CO2, and small amounts of H2. This confirmed that the largest chlorine content remains in the aqueous phase and does not pass into the gas phase. It can be concluded that SCW presents effective decomposition media for plastic waste.
Photodegradation and Mineralization of Phenol Using TiO2Coated γ-Al2O3: Effect of Thermic Treatment
Claudia Martinez-Gómez, Israel Rangel-Vazquez, Ramon Zarraga, Gloria del Ángel, Beatriz Ruíz-Camacho, Francisco Tzompantzi, Esmeralda Vidal-Robles, Alejandro Perez-Larios
February 23, 2023 (v1)
Subject: Materials
Keywords: acidity, phenol, photodegradation, γ-Al2O3-TiO2
It is well-known that γ-Al2O3 possesses large, specific areas and high thermal, chemical, and mechanical resistance. Due to this, it is the most-used support for catalysts, in this case TiO2, as it enables it to achieve better dispersion and improves the activity in catalytic photodegradation reactions. In a previous work, it was observed that the optimal content of TiO2 in γ-Al2O3 was around 15% since the degradation of phenol results were maximized and a synergistic effect was generated by the interaction of both oxides. In addition, an increase in acidity crystal size and the generation of localized, oxygen-vacant, electronic states in the forbidden band of γ-Al2O3, were observed. This study focuses on the effect of the calcination temperature on a γ-Al2O3-TiO2 catalyst (15% w/w of TiO2) and its impact on photocatalytic activity. The catalysts prepared here were characterized by X-ray diffraction, N2 adsorption−desorption, FTIR-pyridine adsorption, MAS-NMR, HRTEM-FFT, UV-vis, and fl... [more]
A Mini Review on Thin Film Superconductors
David Sibanda, Sunday Temitope Oyinbo, Tien-Chien Jen, Ayotunde Idris Ibitoye
February 23, 2023 (v1)
Subject: Materials
Keywords: atomic layer deposition, Meissner effect, pulsed laser deposition, thin film superconductors, thin-film technology
Thin superconducting films have been a significant part of superconductivity research for more than six decades. They have had a significant impact on the existing consensus on the microscopic and macroscopic nature of the superconducting state. Thin-film superconductors have properties that are very different and superior to bulk material. Amongst the various classification criteria, thin-film superconductors can be classified into Fe based thin-film superconductors, layered titanium compound thin-film superconductors, intercalation compounds of layered and cage-like structures, and other thin-film superconductors that do not fall into these groups. There are various techniques of manufacturing thin films, which include atomic layer deposition (ALD), chemical vapour deposition (CVD), physical vapour deposition (PVD), molecular beam epitaxy (MBE), sputtering, electron beam evaporation, laser ablation, cathodic arc, and pulsed laser deposition (PLD). Thin film technology offers a lucrat... [more]
The Seal Performance of Compliant Foil Gas Seal Based on Multi-Scale Analysis
Xueliang Wang, Meihong Liu
February 23, 2023 (v1)
Subject: Materials
Keywords: compliant foil gas seal, multi-scale analysis, seal performance, T groove
Compliant foil gas seal is a non-contact and high-efficiency sealing technology. The dynamic performance of compliant foil gas seal with different structure parameters was analyzed in this paper. These parameters include the seal diameter, gas film thickness and the ratio of groove. Compared with the rigid film, the advantage of compliant film is analyzed. The stability performance and dynamic performance with the different structures are obtained. The results show that the larger diameter is a disadvantage for the stability performance. However, the increase of seal length can decrease the leakage. Otherwise, the increase of gas thickness improves the dynamic characteristics with the leakage rising and gas force dramatically decreasing. While the groove length ratio is around 0.6, the seal performance and dynamic characteristics are best. The compliant structure benefits the improvement of the sealing performance.
The Effect of pH Solution in the Sol−Gel Process on the Structure and Properties of Thin SnO2 Films
Danatbek Murzalinov, Elena Dmitriyeva, Igor Lebedev, Ekaterina A. Bondar, Anastasiya I. Fedosimova, Ainagul Kemelbekova
February 23, 2023 (v1)
Subject: Materials
Keywords: pH, sol–gel, the activation energy of donor levels, thin films, tin oxide, transmission spectra
The synthesis of surface-active structures is important for creating many applications. The structural formation of SnO2 thin films in the range from 1.4 to 1.53 pH is studied in this work. This process occurs on the surface of the sample in the range of 1.4 to 1.49 and in the volume in the range of 1.51 to 1.53. SnO2 is formed after annealing at 400 ∘C, according to XRD. Doping NH4OH to solution stimulates particle coagulation and gel formation. All of these have an impact on the transparency of samples investigated by spectrophotometric methods. By increasing the pH, the resistance raises at room temperature. The Eg calculation along the fundamental absorption edge shows that it is greater than 3.6 eV’ for SnO2 films. According to the Burstein−Moss effect, a change of the bandgap is related to the increased concentration of the free charge carriers. Elemental analysis has shown that chlorine ions are considered to be additional sources of charge carriers. The value pH = 1.49 is criti... [more]
Reduction of Sulfoxides in Multigram Scale, an Alternative to the Use of Chlorinated Solvents
Laura Adarve-Cardona, Diego Gamba-Sánchez
February 23, 2023 (v1)
Subject: Materials
Keywords: reduction, sulfides, sulfonium salts, sulfoxides
In this manuscript, we describe the use of ethyl vinyl ether/oxalyl chloride as the reducing mixture for sulfoxides. The reaction is based on the high electrophilic character of chlorosulfonium salts, formed in situ by the reaction of oxalyl chloride and the sulfoxide. Thereafter, the nucleophilic vinyl ether acts as a chlorine scavenger, affording the corresponding sulfide. The method is applicable on a big scale and may be applied to highly functionalized sulfoxides. Chromatographic purification is only needed in exceptional cases of unstable substrates, and the final sulfide or the corresponding salt is usually obtained after simple evaporation of volatiles. The sole contaminants of this method are carbon dioxide, carbon monoxide and small (five-carbon maximum) aldol products, which are formed during the reaction process.
Pore Size Distribution Characterization by Joint Interpretation of MICP and NMR: A Case Study of Chang 7 Tight Sandstone in the Ordos Basin
Chaozheng Li, Xiangbai Liu, Fuliang You, Peng Wang, Xinluo Feng, Zhazha Hu
February 23, 2023 (v1)
Subject: Materials
Keywords: MICP, NMR, Ordos Basin, pore network model, pore size distribution, tight sandstone
Pore size distribution characterization of unconventional tight reservoirs is extremely significant for an optimized extraction of petroleum from such reservoirs. In the present study, mercury injection capillary pressure (MICP) and low-field nuclear magnetic resonance (NMR) are integrated to evaluate the pore size distribution of the Chang 7 tight sandstone reservoir. The results show that the Chang 7 tight sandstones are characterized by high clay mineral content and fine grain size. They feature complex micro-nano-pore network system, mainly composed of regular primary intergranular pores, dissolved pores, inter-crystalline pores, and micro-fractures. Compared to the porosity obtained from MICP, the NMR porosity is closer to the gas-measured porosity (core analysis), and thus can more accurately describe the total pore space of the tight sandstone reservoirs. The pore throat distribution (PTD) from MICP presents a centralized distribution with high amplitude, while the pore size dis... [more]
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