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Nanotechnology Jul 2024This study employs cold-wall chemical vapor deposition to achieve the growth of MoTethin films on 4-inch sapphire substrates. A two-step growth process is utilized,...
This study employs cold-wall chemical vapor deposition to achieve the growth of MoTethin films on 4-inch sapphire substrates. A two-step growth process is utilized, incorporating MoOand Te powder sources under low-pressure conditions to synthesize MoTe2. The resultant MoTethin films exhibit a dominant 1T' phase, as evidenced by a prominent Raman peak at 161 cm. This preferential 1T' phase formation is attributed to controlled manipulation of the second-step growth temperature, essentially the reaction stage between Te vapor and the pre-deposited MoOx layer. Under these optimized growth conditions, the thickness of the continuous 1T'-MoTefilms can be precisely tailored within the range of 3.5 - 5.7 nm (equivalent to 5 - 8 layers), as determined by atomic force microscopy depth profiling. Hall-effect measurements unveil a typical hole concentration and mobility of 0.2 cm/V-s and 7.9 × 10cm, respectively, for the synthesized few-layered 1T'-MoTe2 films. Furthermore, Ti/Al bilayer metal contacts deposited on the few-layered 1T'-MoTefilms exhibit low specific contact resistances of approximately 1.0 × 10Ω-cmestimated by the transfer length model. This finding suggests a viable approach for achieving low ohmic contact resistance using the 1T'-MoTeintermediate layer between metallic electrodes and two-dimensional semiconductors.
PubMed: 38958023
DOI: 10.1088/1361-6528/ad5db7 -
Journal of the Science of Food and... Jul 2024The transesterification of butteroil has been shown to alter its lipid chemistry and thus alter the crystallization of the fat. The reaction kinetics and resulting...
BACKGROUND
The transesterification of butteroil has been shown to alter its lipid chemistry and thus alter the crystallization of the fat. The reaction kinetics and resulting crystallization of the butteroil differ depending on the nature of the catalyst used. Modeling the reaction with vegetable oils is a simpler method for the analysis of resulting products to understand the chemical and physiochemical changes that occur based on catalyst selection. The objective of this work is to perform a chemical transesterification of coconut and corn oil using monovalent and divalent catalysts to investigate the chemical and crystal changes that occur.
RESULTS
Coconut and corn oil were subjected to chemical transesterification using both Ca(OH) and KOH as catalysts. In both the coconut and corn oil samples, transesterification caused monoglycerides (MAGs) and diacylglycerides (DAGs) to form from the most abundant fatty acid found in each sample. Coconut oil's melting temperature, solid fat content (SFC), and storage modulus decreased as a result of the transesterification, and crystals began to form in the corn oil causing melting thermograms to be evident, higher SFC, and a more viscous oil as a result. Using Ca(OH) as a catalyst resulted in more MAG formation, and a higher SFC and melting temperature than when KOH was used as a catalyst.
CONCLUSION
The results demonstrate that the chemical changes that result from transesterification of plant-based oils change the crystallization behavior of the oils and can therefore be used for different applications in the food industry. © 2024 The Author(s). Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
PubMed: 38957971
DOI: 10.1002/jsfa.13706 -
Angewandte Chemie (International Ed. in... Jul 2024Hydrogen spillover in metal-supported catalysts can largely enhance electrocatalytic hydrogenation performance and reduce energy consumption. However, its fundamental...
Hydrogen spillover in metal-supported catalysts can largely enhance electrocatalytic hydrogenation performance and reduce energy consumption. However, its fundamental mechanism, especially at the metal-metal interface, remains further explored, impeding relevant catalyst design. Here, we theoretically profile that a large free energy difference in hydrogen adsorption on two different metals (|ΔGH-metal(i) - ΔGH-metal(ii)|) induces a high kinetic barrier to hydrogen spillover between the metals. Minimizing the difference in their d-band centers (Δεd) should reduce |ΔGH-metal(i) - ΔGH-metal(ii)|, lowering the kinetic barrier to hydrogen spillover for improved electrocatalytic hydrogenation. We demonstrated this concept using copper-supported ruthenium-platinum alloys with the smallest Δεd, which delivered record high electrocatalytic nitrate hydrogenation performance, with ammonia production rate of 3.45±0.12 mmol h-1 cm-2 and Faraday efficiency of 99.8±0.2 %, at low energy consumption of 21.4 kWh kgamm-1. Using these catalysts, we further achieve continuous ammonia and formic acid production with a record high-profit space.
PubMed: 38957933
DOI: 10.1002/anie.202407810 -
Journal of the American Chemical Society Jul 2024Single-molecule junctions, formed by a single molecule bridging a gap between two metal electrodes, are attracting attention as basic models of ultrasmall electronic...
Single-molecule junctions, formed by a single molecule bridging a gap between two metal electrodes, are attracting attention as basic models of ultrasmall electronic devices. Although charge transport through π-conjugated molecules with π-delocalized system has been widely studied for a number of molecular junctions, there has been almost no research on charge transport through molecular junctions with a σ-delocalized orbital system. Compounds with hexa-selenium-substituted benzene form a σ-delocalized orbital system on the periphery of the benzene ring. In this study, we fabricated single-molecule junctions with the σ-delocalized orbital systems arising from lone-pair interactions of selenium atoms and clarified their electronic properties using the break-junction method. The single-molecule junctions with the σ-orbital systems show efficient charge transport properties and can be one of the alternatives to those with conventional π-orbital systems as minute electronic conductors.
PubMed: 38957924
DOI: 10.1021/jacs.4c06732 -
Journal of the Indian Society of... Apr 2024Many practitioners have questioned whether the construction method of pediatric zirconia crowns impacts the periodontal health and clinical performance of severely... (Comparative Study)
Comparative Study Randomized Controlled Trial
BACKGROUND
Many practitioners have questioned whether the construction method of pediatric zirconia crowns impacts the periodontal health and clinical performance of severely decayed primary molars. The objective of this study was to compare the periodontal health and clinical performance of primary molars restored with custom-made zirconia crowns (CZCs) and prefabricated zirconia crowns.
METHODS
Twenty primary molars indicated for crown restorations were selected from ten patients (5-9 years old) randomly. Each patient received two pediatric zirconia crowns constructed by two different methods: one custom-made and one prefabricated. The primary molars were divided into two groups: Group 1: primary molars received CZCs and Group 2: primary molars received prefabricated zirconia crowns (PZCs).
RESULTS
After a 12-month follow-up, there was no statistically significant difference between the periodontal health of primary molars restored with custom-made and prefabricated zirconia crowns. The clinical performance of primary molars restored with CZCs was statistically significantly higher than those restored with PZCs in terms of retention and fracture resistance (P ≤ 0.05).
CONCLUSIONS
The construction method of pediatric zirconia crowns does not significantly affect the periodontal health of primary molars; however, clinical performance is significantly affected in terms of retention and fracture resistance.
CLINICAL SIGNIFICANCE
A CZC is an excellent alternative option, especially for primary molars whose permanent successors still have a long time to erupt. The PZC is a quick and easy restoration, but the technique is sensitive.
Topics: Humans; Zirconium; Crowns; Molar; Tooth, Deciduous; Follow-Up Studies; Child, Preschool; Child; Dental Prosthesis Design; Male; Female; Dental Caries
PubMed: 38957914
DOI: 10.4103/jisppd.jisppd_39_24 -
Organic & Biomolecular Chemistry Jul 2024Phosphatidic acid and phosphatidylserine are anionic phospholipids with emerging signalling roles in cells. Determination of how phosphatidic acid and phosphatidylserine...
Phosphatidic acid and phosphatidylserine are anionic phospholipids with emerging signalling roles in cells. Determination of how phosphatidic acid and phosphatidylserine change location and quantity in cells over time requires selective fluorescent sensors that can distinguish these two anionic phospholipids. However, the design of such synthetic sensors that can selectively bind and respond to a single phospholipid within the complex membrane milieu remains challenging. In this work, we present a simple and robust strategy to control the selectivity of synthetic sensors for phosphatidic acid and phosphatidylserine. By changing the coordination metal of a dipicolylamine (DPA) ligand from Zn(II) to Ni(II) on the same synthetic sensor with a peptide backbone, we achieve a complete switch in selectivity from phosphatidic acid to phosphatidylserine in model lipid membranes. Furthermore, this strategy was largely unaffected by the choice and the position of the fluorophores. We envision that this strategy will provide a platform for the rational design of targeted synthetic phospholipid sensors to probe plasma and intracellular membranes.
PubMed: 38957899
DOI: 10.1039/d4ob00418c -
Physical Chemistry Chemical Physics :... Jul 2024Uranium is considered as a very important nuclear energy material because of the huge amount of energy it releases. As the main product of the spontaneous decay of...
Uranium is considered as a very important nuclear energy material because of the huge amount of energy it releases. As the main product of the spontaneous decay of uranium, it is difficult for helium to react with uranium because of its chemical inertness. Therefore, bubbles will be formed inside uranium, which could greatly reduce the performance of uranium or cause safety problems. Additionally, nuclear materials are usually operated in an environment of high-temperature and high-pressure, so it is necessary to figure out the exact state of helium inside uranium under extreme conditions. Here, we explored the structural stability of the U-He system under high pressure and high temperature by using density functional theory calculations. Two metastable phases are found between 50 and 400 GPa: UHe with space group and UHe with space group 1̄. Both are metallic and adopt layered structures. Electron localization function calculation combined with charge density difference analysis indicates that there are covalent bonds between U and U atoms in both -UHe and 1̄-UHe. Regarding the elastic modulus of α-U, the addition of helium has certain influence on the mechanical properties of uranium. Besides, first-principles molecular dynamics simulations were carried out to study the dynamical behavior of -UHe and 1̄-UHe at high-temperature. It was found that -UHe and 1̄-UHe undergo one-dimensional superionic phase transitions at 150 GPa. Our study revealed the exotic structure of U-He compounds beyond the formation of bubbles under high-pressure and high-temperature, which might be relevant to the performance and safety issues of nuclear materials under extreme conditions.
PubMed: 38957898
DOI: 10.1039/d4cp02037e -
ACS Sustainable Resource Management Jun 2024The need for sustainable agriculture amid a growing population and challenging climatic conditions is hindered by the environmental repercussions of widespread...
The need for sustainable agriculture amid a growing population and challenging climatic conditions is hindered by the environmental repercussions of widespread fertilizer use, resulting in the accumulation of metal ions and the loss of micronutrients. The present study provides an approach to improve the efficiency of nanofertilizers by controlling the release of copper (Cu) ions from copper oxide (CuO) nanofertilizers through bioionic liquids based on plant growth regulators (PGR-ILs). A 7-day study was conducted to understand the kinetics of Cu ion release in aqueous solution of five different PGR-ILs, with choline ascorbate ([Cho][Asc]) or choline salicylate ([Cho][Sal]) leading to 200- to 700-fold higher dissolution of Cu ions in comparison to choline indole-3-acetate ([Cho][IAA]), choline indole-3-butyrate ([Cho][IBA]), and choline gibberellate ([Cho][GA]). The tunable diffusion of Cu ions from CuO nanofertilizers using PGR-ILs is then applied in a foliar spray study, evaluating its impact on the growth phenotype, photosynthetic parameters, and carbon dioxide (CO) sequestration in in a greenhouse. The results indicate that nanoformulations with lower concentrations of Cu ions in PGR-IL solutions exhibit superior outcomes in terms of plant length, net photosynthetic rate, dry biomass yield, and CO sequestration, emphasizing the critical role of dissolution kinetics in determining the effectiveness of PGR-IL-based nanoformulations for sustainable agriculture.
PubMed: 38957680
DOI: 10.1021/acssusresmgt.4c00041 -
RSC Advances Jun 2024A W/ZSM-5 zeolite was successfully prepared by incorporating tungsten transition metal into a zeolite structure using a conventional impregnation method. The as-obtained...
Cascade reaction for bio-polyol synthesis from sunflower oil over a W/ZSM-5 zeolite catalyst for the fabrication of a bio-polyurethane-based porous biocomposite with high oil uptake.
A W/ZSM-5 zeolite was successfully prepared by incorporating tungsten transition metal into a zeolite structure using a conventional impregnation method. The as-obtained W/ZSM-5 zeolite was characterized using several characterization techniques such as XRD, IR and SEM-EDS. The catalyst was then applied to a cascade, single-batch reaction to synthesize bio-polyol from sunflower oils using HO in isopropanol solvent. The obtained results indicated that the W/ZSM-5 zeolite had high catalytic efficiency in the epoxidation of the double bond of vegetable oil and the epoxy ring opening reaction to form bio-polyol. The effect of different reaction conditions on bio-polyol synthesis, such as the dosage of the catalyst and reaction time, were investigated. Bio-polyol was obtained from sunflower oil with a hydroxyl number of 160 mg KOH per g and functionality of 2.9 OH groups per mol. The as-synthesized sunflower oil-based polyol was used to replace fossil-based polyol in the fabrication of a bio-polyurethane-based composite with high oil uptake capacity. The oil adsorption capacity of the porous polyurethane-corn stalk composite was relatively high, up to 15.07 g g. In comparison with neat polyurethane and lignocellulosic materials, the new porous bio-composite had higher oil uptake capacity.
PubMed: 38957584
DOI: 10.1039/d4ra03671a -
RSC Advances Jun 2024Various visible-light-driven photocatalysts have been studied for practical applications in photocatalytic wastewater treatment solar irradiation. Among them, g-CN has...
Various visible-light-driven photocatalysts have been studied for practical applications in photocatalytic wastewater treatment solar irradiation. Among them, g-CN has attractive features, including its metal-free and environmentally friendly nature; however, it is prone to charge recombination and has low photocatalytic activity. To solve these problems, isotype heterojunction g-CN was recently developed; however, the methods employed for synthesis suffered from limited reproducibility and efficiency. In this study, isotype heterojunction g-CN was synthesized from various combinations of precursor materials using a planetary ball mill. The isotype heterojunction g-CN synthesized from urea and thiourea showed the highest photocatalytic activity and completely decolorized Rhodamine B (RhB; 10 ppm) in 15 min under visible-light irradiation. Furthermore, to improve recyclability, isotype heterojunction g-CN was immobilized in alginate hydrogel spheres. The isotype heterojunction g-CN/alginate hydrogel beads were used in 10 repeated RhB degradation experiments and were able to maintain their initial photocatalytic activity and mechanical strength. These achievements represent an advance towards practical, sustainable photocatalytic wastewater treatment.
PubMed: 38957583
DOI: 10.1039/d4ra02876g