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1
Du, Chao, Yali Zhao, and Yong Li. "Theoretical Derivation of the Effect of Bonding Current on the Bonding Interface during Anodic Bonding of PEG-Based Encapsulation Materials and Aluminum." Polymers 15, no. 4 (February 11, 2023): 913. http://dx.doi.org/10.3390/polym15040913.
Анотація:
This study analyzed the mechanism underlying the effect of the bonding current on the bonding interface during anodic bonding on the basis of the anodic bonding of PEG (polyethylene glycol)-based encapsulation materials and Al. By establishing an equivalent electrical model, the effects of various electrical parameters on the dynamic performance of the bonding current were evaluated, and the change law of the bonding current transfer function was analyzed. By examining the gap deformation model, the conditions for contact between the interface gaps and the bonding current pair were determined, and the influence law of the gap deformation of the bonding interface was derived. By assessing the effect of the bonding current on the ionic behavior, we found that the larger the bonding current, the greater the number of activated mobile ions in the bonding material and the higher the field strength in the cation depletion area. From the anodic bonding experiments, it was found that increasing the bonding voltage can increase the peak current and improve the bonding efficiency. The SEM image after bonding shows that the bonding interface had no obvious defects; the higher bonding voltage can result in a thicker bonding layer.
2
Guadagno, Liberata, Luigi Vertuccio, Carlo Naddeo, Elisa Calabrese, Giuseppina Barra, Marialuigia Raimondo, Andrea Sorrentino, Wolfgang H. Binder, Philipp Michael, and Sravendra Rana. "Development of aeronautical epoxy nanocomposites having an integrated selfhealing ability." MATEC Web of Conferences 233 (2018): 00021. http://dx.doi.org/10.1051/matecconf/201823300021.
Анотація:
Functionalized multi-wall carbon nanotubes (MWCNTs) have been embedded in a rubber-toughened epoxy formulation in order to explore the possibility to impart an auto-repair function to the epoxy matrix. The nanofiller has been covalently functionalized with hydrogen bonding moieties able to act as donor and acceptor of hydrogen bondings. Healing efficiencies have been evaluated for nano charged epoxy formulations at a loading of 0.5% wt/wt of functionalized MWCNTs bearing barbituric acid and thymine-based ligands. For both the performed functionalizations, a self-healing efficiency higher than 50% has been found. Dynamic Mechanical Analysis (DMA) highlights that the inclusion of nanofiller increases the storage moduli. Furthermore, DMA analysis evidences the presence of a phase characterized by a greater mobility of the epoxy chains, which promotes the activation of self-healing mechanisms.
3
Li, Zhao Qian, Bo Hua Nan, Teng Feng He, and Guan Xiang Feng. "Study of Bonding Technology and Property of Foam-Sandwich Co-Bulkhead of Cryogenic Tank on Launch Vehicle." Materials Science Forum 817 (April 2015): 639–44. http://dx.doi.org/10.4028/www.scientific.net/msf.817.639.
Анотація:
As an ideal layout scheme for launch vehicle, bearing co-bulkhead tank can improve the slenderness ratio of launch vehicle, reduce structure weight and increase structure efficiency. In this paper, a novel cryogenic tank co-bulkhead was fabricated by vacuum assisted resin transfer molding (VARTM) process. Consisting of LD10 alloy and polymethacrylimide (PMI) foam-sandwich, the new cryogenic tank co-bulkhead was designed with variable-thickness, hemi-ellipsoid structure, thermal insulation and bearing function. Fundamental temperature distribution, thermal stress and low-temperature load sensitivity of the foam-sandwich co-bulkhead were also assessed by finite element analysis and environment tests in simulated service environment. The results showed that the analog values highly agreed with the test results, and thermal insulation and bearing function of the foam-sandwich co-bulkhead could satisfy the design requirement, which proved the reliability of bonding quality and feasibility of the bonding technique.
4
Mankodi, Hireni. "Geocomposite Manufactured from PP Nonwoven/HDPE Geonet." Advanced Materials Research 622-623 (December 2012): 1310–13. http://dx.doi.org/10.4028/www.scientific.net/amr.622-623.1310.
Анотація:
Geogrids are used as reinforcement materials for soil foundation structure in the geotechnical applications. Also, geogrids have the excellent tensile strength and modulus and therefore, geogrids can show the good reinforcement function within the soil foundation structure that the loads are concentrated. However, geogrids don't have the excellent efficiency to control the migration and loss of fine soil particles to be passed due to the large apertures (opening size).The new concept of reinforced geotextile composites, which can show both functions of reinforcement and separation/drainage and was manufactured by combining nonwoven geotextiiles and geogrid or geonetusing adhesive or thermal bonding process. Geotextile-Geonet Composites compose of geotextile-geonet-geotextilesandwich use for separation and filtration functions. Hence the objective of this study is to manufacture geocomposite for easy installation and better stability of sandwich material in soil condition. This geocomposites are evaluated for its performance.
5
Shen, Jiacong, Junqi Sun, and Xi Zhang. "Polymeric nanostructured composite films." Pure and Applied Chemistry 72, no. 1-2 (January 1, 2000): 147–55. http://dx.doi.org/10.1351/pac200072010147.
Анотація:
This research news describes the construction of polymeric nanostructured composite film based on a variety of interactions, such as hydrophobic–hydrophilic effect, electrostatic interaction, hydrogen bonding, etc. The work focused on developing strategies to solve the basic problems in the area of ultrathin film research, such as stability, improving the interface quality, creating patterned interface, and techniques to construct nanolayered structure. With in-depth study of the relationship between the microscopic layered architecture and macroscopic function of supramolecular assemblies, it is anticipated that one could obtain miniature devices or machines of high efficiency through integration of the assembling process and device fabrication.
6
Su, Ye, Ye Yutang, Xie Yu, Yi Maoli, Zhang Jing, Luo Ying, and Du Chunlei. "Swift perspective shape matching algorithm based on Phong’s model for FPC stiffener bonding systems." Circuit World 40, no. 4 (October 28, 2014): 141–49. http://dx.doi.org/10.1108/cw-06-2014-0023.
Анотація:
Purpose – This paper aims to solve the issue of target positioning in auto stiffener bonder (ASB) systems for flexible printed circuits. Design/methodology/approach – The proposed approach uses Phong’s bidirectional reflectance distribution function (BRDF) model to simulate the reflection of light off a target in ASB systems to predict the current pose of the target based on image brightness, update the template, decrease the initial errors in the template and narrow down the search range. Findings – The experimental results indicate that the proposed approach can predict the inclination angle of the target with precision, presenting angle prediction errors of less than three degrees. Furthermore, with larger inclined angles, the overall matching errors were less than 1.5 pixels. Comparisons with the unmodified matching algorithm revealed that the proposed approach resulted in 65 per cent less calculation time for the algorithm and 14 per cent higher overall work efficiency in the ASB system. Originality/value – The edge-based perspective shape matching algorithm was modified using the Phong BRDF model and enhanced algorithm efficiency with the target pose prediction method while ensuring the precision and robustness of the system. The proposed approach has high potential value and can be expanded to recognition systems for objects with varying inclination angles and highly reflective surfaces.
7
Di Pumpo, Antonietta, Mark Weller, Sax Mason, and Marie-Hélène Lemée-Cailleau. "Hydrogen bonding structure and polymorphism in agrochemicals." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C540. http://dx.doi.org/10.1107/s2053273314094595.
Анотація:
Polymorphism of crystals, crystal habit and crystal growth are important factors that must be controlled for any commercial crystallization process. Pharmaceuticals and agrochemicals are two of the most industrially-important, active-molecule systems for which the physical properties are strongly correlated to their crystal structure. While pharmaceuticals have attracted more academic interest to date, the market for agrochemicals is also very considerable, amounting to $15 bn annually. Given the potential significant toxicity of some agrochemicals, the ability to control physical properties such as solubility and dissolution rates, which depend on the crystal structure of the agrochemical itself, represents a way of optimizing the ratio between the amount of product used and its efficiency, improving its function and reducing its environmental impact. Hydrogen bonds play a crucial role in the spatial arrangement of the active molecules and the crystallization process. However, high accuracy and precision of the hydrogen atom positions can only be achieved through single crystal neutron diffraction (SND). SND experiments have been performed on three herbicides - isoproturon (IPU), pendimethalin (PDM), and diflufenican (DFF) - and the fungicide cyprodinil (CYP) [1][2]. All four structure refinements show a ten-time improvement in precision in the hydrogen atom positions compared to SXD with accurately determined nuclear positions. For cyprodinil, which crystallises as two polymorphs, A and B, differences in the hydrogen bonding network have been determined. Form A is governed by single, linear hydrogen bonds between two molecules, while the B form is characterized by the presence of dimers linked through pairs of hydrogen bonds, leading to a stable 8-membered ring. These differences in structure are reflected in the physical properties of the two polymorphs such as melting point and the observed slow inter-conversion that takes place during storage.
8
Pearson, Heidi C. "Unravelling the function of dolphin leaps using the dusky dolphin (Lagenorhynchus obscurus) as a model species." Behaviour 154, no. 5 (2017): 563–81. http://dx.doi.org/10.1163/1568539x-00003434.
Анотація:
The prevalence of leaping across delphinids indicates it has an adaptive benefit. I examined leaping behaviour in dusky dolphins (Lagenorhynchus obscurus) according to signalling, social facilitation, and prey capture hypotheses. I quantified the effect of leaping on group behaviour and fission-fusion and the behavioural context of leaping. I observed dolphins in Admiralty Bay, New Zealand during 171 focal follows totalling 157 h. Data were analysed using generalized estimating equations. Clean leaping had a positive effect on party fission () and foraging behaviour (). Coordinated leaping caused a short-term wane in foraging behaviour () and had a positive effect on party fusion (). Noisy leaping had a negative effect on perpetuating resting and traveling cessation (both ). The signalling hypothesis was the most strongly supported. The social facilitation and prey capture hypotheses were moderately supported. Leaping may provide adaptive benefits such as reduced scramble competition, increased foraging efficiency, and social bonding.
9
Wang, Ce, Shuai Guan, Md Sabbrojjaman, and T. Tafsirojjaman. "Bond Performance of CFRP Strands to Grouting Admixture for Prestressed Structure and Development of Their Bond–Slip Constitutive Models." Polymers 15, no. 13 (June 30, 2023): 2906. http://dx.doi.org/10.3390/polym15132906.
Анотація:
Prestressed concrete structures have witnessed widespread use in building and infrastructure applications during the last two decades due to their high stiffness and strength indices. However, structural failures caused by the corrosion of steel reinforcing bars or strands have proliferated, opening the door for carbon fibre-reinforced polymer (CFRP) strands as an excellent alternative with high corrosion resistance. The bonding interaction between the CFRP strands and concrete is the fundamental parameter in shaping the structural behaviour of CFRP prestressed concrete structures. In this paper, the bonding behaviour between CFRP strands and concrete with grouting admixture is experimentally investigated based on three groups of standard pull-out tests. The bond strength of CFRP strands was systematically studied and compared against steel strands. The untreated CFRP strands exhibited an inefficient bonding strength with the grouting admixture, equivalent to only 5% compared to steel strands of the same diameter. Surface coating with epoxy quartz sand can significantly improve the anchoring efficiency of CFRP strands up to 14 times compared to the untreated strands, which is approximately as efficient as steel strands. Moreover, the bond–slip curves between CFRP strands and concrete were analysed and were found to be different compared to steel strands. Finally, this study proposed bond–slip constitutive models of CFRP strands with better applicability, using an exponentially damped sine function to fit the residual segment of the curve.
10
Nobbs, T. J., A. Cortés, J. L. Gelpi, J. J. Holbrook, T. Atkinson, M. D. Scawen, and D. J. Nicholls. "Contribution of a buried aspartate residue towards the catalytic efficiency and structural stability of Bacillus stearothermophilus lactate dehydrogenase." Biochemical Journal 300, no. 2 (June 1, 1994): 491–99. http://dx.doi.org/10.1042/bj3000491.
Анотація:
The X-ray structure of lactate dehydrogenase (LDH) shows the side-chain carboxylate group of Asp-143 to be buried in the hydrophobic interior of the enzyme, where it makes hydrogen-bonding interactions with both the side-chain hydroxyl group of Ser-273 and the main-chain amide group of His-195. This is an unusual environment for a carboxylate side-chain as hydrogen bonding normally occurs with water molecules at the surface of the protein. A charged hydrogen-bonding interaction in the interior of a protein would be expected to be much stronger than a similar interaction on the solvent-exposed exterior. In this respect the side-chain carboxylate group of Asp-143 appears to be important for maintaining tertiary structure by providing a common linkage point between three discontinuous elements of the secondary structure, alpha 1F, beta K and the beta-turn joining beta G and beta H. The contribution of the Asp-143 side-chain to the structure and function of Bacillus stearothermophilus LDH was assessed by creating a mutant enzyme containing Asn-143. The decreased thermal stability of both unactivated and fructose-1,6-diphosphate (Fru-1,6-P2)-activated forms of the mutant enzyme support a structural role for Asp-143. Furthermore, the difference in stability of the wild-type and mutant enzymes in guanidinium chloride suggested that the carboxylate group of Asp-143 contributes at least 22 kJ/mol to the conformational stability of the wild-type enzyme. However, there was no alteration in the amount of accessible tryptophan fluorescence in the mutant enzyme, indicating that the mutation caused a structural weakness rather than a gross conformational change. Comparison of the wild-type and mutant enzyme steady-state parameters for various 2-keto acid substrates showed the mutation to have a general effect on catalysis, with an average difference in binding energy of 11 kJ/mol for the transition-state complexes. The different effects of pH and Fru-1,6-P2 on the wild-type and mutant enzymes also confirmed a perturbation of the catalytic centre in the mutant enzyme. As the side-chain of Asp-143 is not sufficiently close to the active site to be directly involved in catalysis or substrate binding it is proposed that the effects on catalysis shown by the mutant enzyme are induced either by a structural change or by charge imbalance at the active site.(ABSTRACT TRUNCATED AT 400 WORDS)
11
Du, Xin-Kun, Ya-Li Zhang, and Sheng-Hu Ding. "Exact solutions of interfacial cracking problem of elliptic inclusion in thermoelectric material." E3S Web of Conferences 261 (2021): 02089. http://dx.doi.org/10.1051/e3sconf/202126102089.
Анотація:
In the present work, the problem for elliptical inclusion with interfacial crack in thermoelectric material is studied. The inclusion and matrix are assumed to be imperfect bonding, which is subjected to uniform heat flux and energy flux at infinity. The interfacial cracking problem of elliptic inclusion in thermoelectric material is investigated by using conformal mapping and complex function method. The complex expressions of temperature field and electric field in inclusion and matrix are obtained. The energy release rate of thermoelectric material under the influence of inclusion is given. The effects of elliptic inclusion with interfacial crack on temperature field and electric potential also are compared by numerical examples. The results show that inclusion reduces the conversion efficiency of thermoelectric material.
12
Parkin, Sean, Xiang Hao, and Carolyn Pratt Brock. "2-Biphenylol revisited." Acta Crystallographica Section B Structural Science 60, no. 2 (March 18, 2004): 197–203. http://dx.doi.org/10.1107/s0108768104003696.
Анотація:
The substantially disordered structure of 2-biphenylol [Perrin et al. (1987). Acta Cryst. C43, 980–982; Kapon & Reisner (1988). Acta Cryst. C44, 2039] has been reinvestigated as a function of temperature. The structure was determined at 305, 294, 145 and 90 K; crystals were taken to the lowest temperature both rapidly and slowly (0.1 K min−1). The results of the previous room-temperature study were confirmed and no important structural change was found down to 90 K. Comparisons with structures known for other simple 2- and 2,2′-substituted biphenyl derivatives suggest that the molecular stacks found for 2-biphenylol are probable for related molecules. The disorder in 2-biphenylol allows the formation of some O—H...O bonds, but packing efficiency is a more important factor in this structure than is hydrogen bonding.
13
Laye, Victoria J., Ram Karan, Jong-Myoung Kim, Wolf T. Pecher, Priya DasSarma та Shiladitya DasSarma. "Key amino acid residues conferring enhanced enzyme activity at cold temperatures in an Antarctic polyextremophilic β-galactosidase". Proceedings of the National Academy of Sciences 114, № 47 (6 листопада 2017): 12530–35. http://dx.doi.org/10.1073/pnas.1711542114.
Анотація:
The Antarctic microorganism Halorubrum lacusprofundi harbors a model polyextremophilic β-galactosidase that functions in cold, hypersaline conditions. Six amino acid residues potentially important for cold activity were identified by comparative genomics and substituted with evolutionarily conserved residues (N251D, A263S, I299L, F387L, I476V, and V482L) in closely related homologs from mesophilic haloarchaea. Using a homology model, four residues (N251, A263, I299, and F387) were located in the TIM barrel around the active site in domain A, and two residues (I476 and V482) were within coiled or β-sheet regions in domain B distant to the active site. Site-directed mutagenesis was performed by partial gene synthesis, and enzymes were overproduced from the cold-inducible cspD2 promoter in the genetically tractable Haloarchaeon, Halobacterium sp. NRC-1. Purified enzymes were characterized by steady-state kinetic analysis at temperatures from 0 to 25 °C using the chromogenic substrate o-nitrophenyl-β-galactoside. All substitutions resulted in altered temperature activity profiles compared with wild type, with five of the six clearly exhibiting reduced catalytic efficiency (kcat/Km) at colder temperatures and/or higher efficiency at warmer temperatures. These results could be accounted for by temperature-dependent changes in both Km and kcat (three substitutions) or either Km or kcat (one substitution each). The effects were correlated with perturbation of charge, hydrogen bonding, or packing, likely affecting the temperature-dependent flexibility and function of the enzyme. Our interdisciplinary approach, incorporating comparative genomics, mutagenesis, enzyme kinetics, and modeling, has shown that divergence of a very small number of amino acid residues can account for the cold temperature function of a polyextremophilic enzyme.
14
Carvalho, Quinn, Rylee Marks, and Kelsey A. Stoerzinger. "(Digital Presentation) Role of Electronic Structure on Nitrate Reduction to Ammonium: A Periodic Journey." ECS Meeting Abstracts MA2022-01, no. 40 (July 7, 2022): 1801. http://dx.doi.org/10.1149/ma2022-01401801mtgabs.
Анотація:
The perturbation of the nitrogen cycle via fertilizer amendment and fossil-fuel combustion has resulted in alarmingly increased nitrate concentrations in groundwater and coastal areas, with global human-health threatening consequences. Denitrification of drinking water, municipal cooling tower waste water, and industrial waste streams is a growing area of energy consumption, though still outpaced by the carbon-intensive Haber-Bosch production of ammonia from nitrogen for fertilizer production. Electrocatalytic nitrate reduction offers a competitive, distributable, and cyclic alternative to conventional fertilizer-production approaches, using electrons as a reducing agent without the need for added chemicals or elevated temperatures and pressures. However, nitrate reduction Faradaic efficiency to desired products (e.g. ammonium) is limited by two primary factors: (1) competition with the process of water reduction (i.e. reducing protons to form hydrogen gas); and (2) a complex reduction pathway where nitric oxide (NO) plays a critical role in determining selectivity. Here we investigate nitrate reduction in neutral pH phosphate buffer over a series of 3d (Cu, Ni, Ni0.68Cu0.32, Co, Fe, Ti) and 4d 10 (Ag) transition metals (TMs), identifying properties of bulk resting electronic structure (e.g. work function [Φ] and d-band center energy [Ed ]) as descriptors for nitrate reduction Faradaic efficiency and selectivity to ammonium. We frame our discussion of these results within theoretical and empirical literature on hydrogen evolution and nitric oxide adsorption, finding Φ dictates total nitrate reduction Faradaic efficiency while Ed determines selectivity towards ammonium. Nitrate reduction FE trends with work function, in-line with well-established trends between HER activity and work function. Selectivity towards ammonium increases as Ed approaches and overcomes the Fermi level, increasing the adsorption energy of nitrate reduction intermediates (such as NO) by decreasing occupation of anti-bonding states.
15
Ghasia, S., R. Regar, and H. S. Bhandari. "Micelle Sensitized Physicochemical Studies on Erbium(III) Complexes with Hypoglycemic Sulfonylurea Drugs." Research Journal of Chemistry and Environment 27, no. 3 (February 15, 2023): 64–73. http://dx.doi.org/10.25303/2703rjce064073.
Анотація:
Hypoglycemic sulfonylurea derivatives ligands viz. glimepiride, glibenclamide, gliclazide and glipizide show interaction with lanthanide metal Er (III) in non-micellar and micellar medium. Anionic, cationic and non-ionic surfactant micellar media show great variation in oscillator strength of Er (III) with hypoglycemic sulfonylurea drugs as reflected in UVVisible absorption spectra. Interpretation of UVVisible absorption spectra produced that 4G11/2 ← 4I15/2 and 2H11/2 ← 4I15/2 electronic transition bands show different behavior on account of oscillator strength (P) compared to other electronic f-f transitions, depicted as hypersensitive peaks which are characterized as ratio of Pmicellar / PDMF. Exploitation of different parameters viz: oscillator strength (P), Judd-Ofelt parameter Tλ, nephelauxetic effect 𝛽 and bonding parameter b1/2 from absorption spectra supports the covalency characters in metal ligand Er (III)-drugs doped systems to a greater extent. Thermodynamic exploits of hypersensitive transition correlate the spectroscopic data via Work function A, Thermodynamic efficiency of transition TET and Partition function Q. Thermodynamic parameters notify the microscopic behaviour of Er (III)- sulfonylurea drugs.
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Kean Ping, Loh, Mohd Ambri Mohamed, Abhay Kumar Mondal, Mohamad Fariz Mohamad Taib, Mohd Hazrie Samat, Dilla Duryha Berhanuddin, P. Susthitha Menon та Raihana Bahru. "First-Principles Studies for Electronic Structure and Optical Properties of Strontium Doped β-Ga2O3". Micromachines 12, № 4 (24 березня 2021): 348. http://dx.doi.org/10.3390/mi12040348.
Анотація:
The crystal structure, electron charge density, band structure, density of states, and optical properties of pure and strontium (Sr)-doped β-Ga2O3 were studied using the first-principles calculation based on the density functional theory (DFT) within the generalized-gradient approximation (GGA) with the Perdew–Burke–Ernzerhof (PBE). The reason for choosing strontium as a dopant is due to its p-type doping behavior, which is expected to boost the material’s electrical and optical properties and maximize the devices’ efficiency. The structural parameter for pure β-Ga2O3 crystal structure is in the monoclinic space group (C2/m), which shows good agreement with the previous studies from experimental work. Bandgap energy from both pure and Sr-doped β-Ga2O3 is lower than the experimental bandgap value due to the limitation of DFT, which will ignore the calculation of exchange-correlation potential. To counterbalance the current incompatibilities, the better way to complete the theoretical calculations is to refine the theoretical predictions using the scissor operator’s working principle, according to literature published in the past and present. Therefore, the scissor operator was used to overcome the limitation of DFT. The density of states (DOS) shows the hybridization state of Ga 3d, O 2p, and Sr 5s orbital. The bonding population analysis exhibits the bonding characteristics for both pure and Sr-doped β-Ga2O3. The calculated optical properties for the absorption coefficient in Sr doping causes red-shift of the absorption spectrum, thus, strengthening visible light absorption. The reflectivity, refractive index, dielectric function, and loss function were obtained to understand further this novel work on Sr-doped β-Ga2O3 from the first-principles calculation.
17
Wang, Jingyao, Yicong Xu, Xujian Wang, Jiahuang Li, and Zichun Hua. "Mechanism of Mutation-Induced Effects on the Catalytic Function of TEV Protease: A Molecular Dynamics Study." Molecules 29, no. 5 (February 29, 2024): 1071. http://dx.doi.org/10.3390/molecules29051071.
Анотація:
Tobacco etch virus protease (TEVp) is wildly exploited for various biotechnological applications. These applications take advantage of TEVp’s ability to cleave specific substrate sequences to study protein function and interactions. A major limitation of this enzyme is its relatively slow catalytic rate. In this study, MD simulations were conducted on TEV enzymes and known highly active mutants (eTEV and uTEV3) to explore the relationship between mutation, conformation, and catalytic function. The results suggest that mutations distant from the active site can influence the substrate-binding pocket through interaction networks. MD analysis of eTEV demonstrates that, by stabilizing the orientation of the substrate at the catalytic site, mutations that appropriately enlarge the substrate-binding pocket will be beneficial for Kcat, enhancing the catalytic efficiency of the enzyme. On the contrary, mutations in uTEV3 reduced the flexibility of the active pocket and increased the hydrogen bonding between the substrate and enzyme, resulting in higher affinity. At the same time, the MD simulation demonstrates that mutations outside of the active site residues could affect the dynamic movement of the binding pocket by altering residue networks and communication pathways, thereby having a profound impact on reactivity. These findings not only provide a molecular mechanistic explanation for the excellent mutants, but also serve as a guiding framework for rational computational design.
18
Hailu, Alem Gebrelibanos Gebrelibanos, and Fu-Ming Wang. "Investigation and Characterization of in-Situ Polymer Brush SEI Core Shell Layer Effects on Si Anode Material and Its Battery Performance." ECS Meeting Abstracts MA2022-01, no. 2 (July 7, 2022): 403. http://dx.doi.org/10.1149/ma2022-012403mtgabs.
Анотація:
Silicon is a promising material for lithium-ion batteries due to its super high capacity.1 However, the volume expansion and the pulverization of Si limit its perforamce.2 This study investigates the effect of a polymer brush core-shell structure of Si as an anode material. The polymer brush is designed through Si-C covalent bond of vinyl monomers by thermal hydrosilylation reaction. According to the results, the PBCS structure provides three significant functions on Si particles because of the intramolecular effect of hydrogen bonding with PBCS and binder delivers a good dispersion in the slurry, a mechanical protection during cycling, and excellent ionic conductivity for high-rate tests. Compared with the unmodified electrode (SiNP), the modified electrodes (SiNP-M1 and SiNP-M2) incorporating the PBCS provides better initial columbic efficiency of 87.1% with the first discharge capacity of 1988.9 mAh g-1. The TEM and operando TXM results display that the PBCS structure significantly protects the nano Si from cracking owing to the high elastic function and intramolecular hydrogen bonding effect of the PBCS. Operando X-ray diffraction is also used to provide the phase information of the Si electrodes. With this novel PBCS-Si material, a high energy density lithium-ion battery contains pure Si can be expected. Reference Li, C.; Shi, T.; Li, D.; Yoshitake, H.; Wang, H., Effect of surface modification on electrochemical performance of nano-sized Si as an anode material for Li-ion batteries. RSC Advances 2016, 6 (41), 34715-34723. Gao, Y.; Yi, R.; Li, Y. C.; Song, J.; Chen, S.; Huang, Q.; Mallouk, T. E.; Wang, D., General Method of Manipulating Formation, Composition, and Morphology of Solid-Electrolyte Interphases for Stable Li-Alloy Anodes. J Am Chem Soc 2017, 139 (48), 17359-17367. Figure 1
19
Huang, Dan, Guangda Lu, and Yiming Liu. "Nonlocal Peridynamic Modeling and Simulation on Crack Propagation in Concrete Structures." Mathematical Problems in Engineering 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/858723.
Анотація:
An extended peridynamic approach for crack propagation analysis in concrete structures was proposed. In the peridynamic constitutive model, concrete material was described as a series of interacting particles, and the short-range repulsive force and anisotropic behavior of concrete were taken into account in the expression of the interactive bonding force, which was given in terms of classical elastic constants and peridynamic horizon. The damage of material was defined locally at the level of pairwise bond, and the critical stretch of material bond was described as a function of fracture strength in the classical concrete failure theory. The efficiency and accuracy of the proposed model and algorithms were validated by simulating the propagation of mode I and I-II mixed mode cracks in concrete slabs. Furthermore, crack propagation in a double-edge notched concrete beam subjected to four-point load was simulated, in which the experimental observations are captured naturally as a consequence of the solution.
20
Rosentreter, Jeffrey J., John Malamakal, Kelli Barnes, and Matt Alexander. "Solvent selection for fatty acid residue analysis of archeologicial artifacts." Sample Preparation 3, no. 1 (January 27, 2017): 1–10. http://dx.doi.org/10.1515/sampre-2017-0001.
Анотація:
AbstractResidue analysis has rapidly become one of the most useful techniques for determining an artifact function and revealing insight into paleodiets. The success of analytical residue analysis often lies with the first preparatory step, where the residue is extracted from the object. Detection of a residue requires effective solvation of the material, and there is a large range of potential solvents. One purpose of this study is to determine the efficiency of various solvents for the extraction of fatty acids from charcoal, a material that is ubiquitous, easily identified, remarkably stable in the archaeological record but, most importantly for this research, retains fats extremely well. This investigation examines the removal efficiency of model fatty acids from carbonized wood samples. The strong affinity of lipids to charcoal makes carbonized wood ideal for retaining them, but also makes their extraction extremely challenging and thus an ideal benchmark for solvent extraction characterization. Several solvents (benzene, chloroform, hexane, methanol and water) are used to determine the quantitative extraction efficiency of tripalmitin. While benzene and chloroform perform best for some wood types, neither solvent is better for all carbonized wood. Correlations between the chemical properties of the solvents and the effectiveness of the extraction provide guidance for solvents. Findings indicate solvent characteristics including dipole moment, dielectric constant, hydrogen bonding, and molecular weight all play an important role in extraction of fat from a charcoal matrix. Results presented should provide guidelines to allow for more effective residue extration and more accurate lipid analysis.
21
Liu, Feifei, Haoyu Jia, Yuxue Chen, Xiaoai Luo, Meidong Huang, Meng Wang, and Xinping Zhang. "Dual-Function Meta-Grating Based on Tunable Fano Resonance for Reflective Filter and Sensor Applications." Sensors 23, no. 14 (July 17, 2023): 6462. http://dx.doi.org/10.3390/s23146462.
Анотація:
Localized surface plasmon resonance (LSPR)-based sensors exhibit enormous potential in the areas of medical diagnosis, food safety regulation and environmental monitoring. However, the broadband spectral lineshape of LSPR hampers the observation of wavelength shifts in sensing processes, thus preventing its widespread applications in sensors. Here, we describe an improved plasmonic sensor based on Fano resonances between LSPR and the Rayleigh anomaly (RA) in a metal–insulator–metal (MIM) meta-grating, which is composed of silver nanoshell array, an isolation grating mask and a continuous gold film. The MIM configuration offers more freedom to control the optical properties of LSPR, RA and the Fano resonance between them. Strong couplings between LSPR and RA formed a series of narrowband reflection peaks (with a linewidth of ~20 nm in full width at half maximum (FWHM) and a reflectivity nearing 100%) within an LSPR-based broadband extinction window in the experiment, making the meta-grating promising for applications of high-efficiency reflective filters. A Fano resonance that is well optimized between LSPR and RA by carefully adjusting the angles of incident light can switch such a nano-device to an improved biological/chemical sensor with a figure of merit (FOM) larger than 57 and capability of detecting the local refractive index changes caused by the bonding of target molecules on the surface of the nano-device. The figure of merit of the hybrid sensor in the detection of target molecules is 6 and 15 times higher than that of the simple RA- and LSPR-based sensors, respectively.
22
Kumar, Kasi Vinoth, Luminita Andronic, Elbruz Murat Baba, Dargie Deribew, Jeyanthinath Mayandi, Ellen Moons, and Smagul Zh Karazhanov. "Experimental and Theoretical Investigation of Gadolinium Oxyhydride (GdHO) Thin Films: Optical, Photocatalytic, and Electronic Properties." Nanomaterials 13, no. 24 (December 7, 2023): 3093. http://dx.doi.org/10.3390/nano13243093.
Анотація:
Oxyhydrides of rare-earth metals (REMOHs) exhibit notable photochromic behaviors. Among these, yttrium oxyhydride (YHO) stands out for its impressive transparency and swift UV-responsive color change, positioning it as an optimal material for self-cleaning window applications. Although semiconductor photocatalysis holds potential solutions for critical environmental issues, optimizing the photocatalytic efficacy of photochromic substances has not been adequately addressed. This research advances the study of REMOHs, focusing on the properties of gadolinium oxyhydride (GdHO) both theoretically and experimentally. The electronic and structural characteristics of GdHO, vital for ceramic technology, are thoroughly examined. Explicitly determined work functions for GdH2, GdHO, and Gd2O3 stand at 3.4 eV, 3.0 eV, and 4.3 eV, respectively. Bader charge analysis showcases GdHO’s intricate bonding attributes, whereas its electron localization function majorly presents an ionic nature. The charge neutrality level is situated about 0.33 eV below the top valence band, highlighting these materials’ inclination for acceptor-dominant electrical conductivity. Remarkably, this research unveils GdHO films’ photocatalytic capabilities for the first time. Even with their restricted surface due to thinness, these films follow the Langmuir–Hinshelwood degradation kinetics, ensuring total degradation of methylene blue in a day. It was observed that GdHO’s work function diminishes with reduced deposition pressure, and UV exposure further decreases it by 0.2 eV—a change that reverts post-UV exposure. The persistent stability of GdHO films, hinting at feasible recyclability, enhances their potential efficiency, underlining their viability in practical applications. Overall, this study accentuates GdHO’s pivotal role in electronics and photocatalysis, representing a landmark advancement in the domain.
23
Bedon, Chiara, Filipe A. Santos, and Marco Fasan. "Mechanical Analysis of the Quasi-Static and Dynamic Composite Action in PV Modules with Viscoelastic Encapsulant." Materials 17, no. 6 (March 13, 2024): 1317. http://dx.doi.org/10.3390/ma17061317.
Анотація:
The mechanical analysis of photovoltaics and building integrated photovoltaics is a key step for their optimal design and certification, and requires careful consideration, alongside solar power, durability and functionality issues. The solar cells are encapsulated in thin interlayers that are usually composed of a viscoelastic Ethylene–Vinyl Acetate compound, and protected by thin glass and/or plastic layers. This paper investigates the out-of-plane bending response of a full-scale commercial PV module and focuses attention on the shear bonding efficiency of the thin encapsulant for quasi-static and dynamic mechanical considerations. The parametric analytical analysis, carried out in this study for a laminated glass plate, highlights the possible consequences of the viscoelastic shear coupling on the cross-section load-bearing demand in the covers. As a direct effect of severe operational conditions (i.e., ageing, non-uniform/cyclic thermal gradients, humidity, extreme mechanical/thermal loads, etc.) the shear rigidity and adhesion of these films can suffer from repeated/progressive modification and even degradation, and thus induce major stress and deflection effects in the out-of-plane mechanical response of the PV module components. The minimum shear bond efficiency required to prevent mechanical issues is calculated for various configurations of technical interest. Accordingly, it is shown how the quasi-static and dynamic mechanical performance of the system modifies as a function of a more rigid or weak shear coupling.
24
Ezran Zainal Abdullah, Muhamad, and Khair Aidil Azlin Abd Rahman. "Ergo-aesthetic approach through senses and behavioral assessment." International Journal of Engineering & Technology 7, no. 3.28 (August 17, 2018): 1. http://dx.doi.org/10.14419/ijet.v7i3.28.20953.
Анотація:
In general, the concept of ergo-aesthetic discloses the equilibrium of human behavioral character with form, shape, and symbolism inside a designed product. In fact, this harmony synthesis can be achieved throughout responses of behavior and senses inside a design process. Through the adaptation of ergo-aesthetic, humans will be able to achieve greater satisfaction with the designed product as they will positively interact and respond proportionally to it. In this context, ergo-aesthetic principles will replace the traditional method of evaluating and adapting ergonomic and aesthetic into the design process to achieve a better output product. Essentially, ergonomic and aesthetic are fundamental components that need to be considered throughout the design process procedures. The synergy between these two aspects may facilitate in optimizing the efficiency of the design process which will contribute to a higher output quality. Additionally, behavior and culture are also significant as they function as bonding agents for ergonomic and aesthetic to merge harmonically. Thus, implementing ergo-aesthetic principles into design process through behavior and cultural perspectives may lead to the enhancement of the output quality of a product.
25
Gul, W., A. Khan, and A. Shakoor. "Impact of Hot Pressing Temperature on Medium Density Fiberboard (MDF) Performance." Advances in Materials Science and Engineering 2017 (2017): 1–6. http://dx.doi.org/10.1155/2017/4056360.
Анотація:
Hot pressing temperature is determined according to the performance of boards, type of glue, and production efficiency of hot press. During hot pressing, the thermal energy has enhanced the plasticity of the fiber and created conditions for the integration of different bonds. The thermal energy will cause the moisture in raw board to vaporize. Temporary heating will expedite the solidification of hot set resin for decreased friction and increased fluidity. The hot pressing temperature usually refers to the temperature of hot pressing plate, but what plays function in actual use is the temperature inside the raw board. This research investigates the performance of MDF with respect to hot pressing temperature. The strength and water resistance of the product are improved with the increase of hot pressing temperature from 140°C to 160°C, the Modulus of Rupture (MOR) is increased by 9.8%, the Internal Bonding (IB) is increased by 33.6%, the water absorption (Wt) is decreased by 38.2%, and the thickness expansion rate (Ts) is decreased by 15.2%.
26
Shahzad, Adnan, Ezzat Khan, Muhammad Said, Gul Shazada Khan, Mian Gul Syed, Awal Noor, Muhammad Zahoor, Riaz Ullah, and Ahmed Bari. "Complexes of 1,3-Diisobutyl Thiourea with Copper(I), Zinc(II) and Mercury(II): Their Antioxidant and Antibacterial Evaluation." Crystals 11, no. 8 (August 20, 2021): 989. http://dx.doi.org/10.3390/cryst11080989.
Анотація:
The reaction of 1,3-Diisobutyl thiourea (Tu) with metal salts, {[CuX (X = Cl, I)], [ZnCl2] and [HgI2] in an appropriate stoichiometric ratio afforded the corresponding metal complexes [Tu2CuCl] (1), [Tu3CuI] (2), [Tu2ZnCl2] (3) and [Tu2HgI2] (4) in good yields. The FT-IR data show typically broad signals (3278–3288 cm−1) attributed to the involvement of NH bonds in extensive hydrogen bonding. The structures of complexes were proposed based on a spectroscopic data set. Compounds 1 and 2 were additionally characterized by single-crystal X-ray analysis. Complexes 1–4 were tested for their free radical scavenging efficiency using 2,2-diphenyl-1-picrylhydrazyl free radical (hereafter abbreviated as DPPH). The free radical scavenging activity was a function of decrease in the resultant absorption of DPPH solution after the mixing of an appropriate concentration of the respective complex. The activity of complexes was determined to be dose dependent and increased concentration of the complex resulted in improved antioxidant activity. Compound 1 was found to be the most efficient, with 79.9% free radical scavenging activity. Complexes were also tested for their efficiency against selected strains of bacteria (E. coli, S. flexneri, S. typhi, and P. aeruginosa) and the activities were compared to commercially available standard drug cephradine. Compound 1 was more active against P.aeruginosa (ZI 13.25), while compound 4 was found to be more active against E. coli (ZI 11.0), S. flexneri (ZI 11.2), and S. typhi (ZI 10.5).
27
Salahat, Angham, Othman Hamed, Abdalhadi Deghles, Khalil Azzaoui, Hisham Qrareya, Mohyeddin Assali, Waseem Mansour, et al. "Olive Industry Solid Waste-Based Biosorbent: Synthesis and Application in Wastewater Purification." Polymers 15, no. 4 (February 4, 2023): 797. http://dx.doi.org/10.3390/polym15040797.
Анотація:
In this work, we present a process for converting olive industry solid waste (OISW) into a value-added material with ionic receptors for use in the removal of toxic metal ions from wastewater. This 3D polymer is a promising adsorbent for large-scale application, since it is a low-cost material made from agricultural waste and showed exceptional performance. The synthesis of the network polymer involved the carboxymethylation of OISW and curing of the carboxymethylated OISW at an elevated temperature to promote the formation of ester linkages between OISW’s components. FT-IR, atomic force microscopy, and thermal analysis were performed on the crosslinked product. The adsorption efficiency of the crosslinked carboxymethylated OISW toward Pb(II), Cu(II), and other toxic metal ions present in sewage was evaluated as a function of adsorbent dose, temperature, pH, time, and initial metal ion. The percentage removal of about 20 metal ions present in a sewage sample collected from a sewer plant located in the Palestinian Territories was determined. The adsorption efficiency did not drop even after six cycles of use. The kinetic study showed that the adsorption process follows the Langmuir isotherm model and the second-order adsorption rate. The experimental Qe values of 13.91 and 13.71 mg/g were obtained for Pb(II) and Cu(II) removal, respectively. The thermodynamic results confirm the spontaneous metal bonding to the receptor sites of the crosslinked carboxymethylated OISW.
28
Sun, Qifan, Xin Gao, Hongna Bi, Yingbo Xie, and Lin Tang. "Assessment of Binding Interaction between Bovine Lactoferrin and Tetracycline Hydrochloride: Multi-Spectroscopic Analyses and Molecular Modeling." Molecules 23, no. 8 (July 30, 2018): 1900. http://dx.doi.org/10.3390/molecules23081900.
Анотація:
In this paper, the interaction between bovine lactoferrin (bLf) and tetracycline hydrochloride (TCH) was researched by microscale thermophoresis (MST), multi-spectroscopic methods, and molecular docking techniques. Normal fluorescence results showed that TCH effectively quenched the intrinsic fluorescence of bLf via static quenching. Moreover, MST confirmed that the combination force between bLf and TCH was very strong. Thermodynamic parameters and molecular docking further revealed that electrostatic forces, van der Waals, and hydrogen bonding forces played vital roles in the interaction between bLf and TCH. The binding distance and energy transfer efficiency between TCH and bLf were 2.81 nm and 0.053, respectively. Moreover, the results of circular dichroism spectra (CD), ultraviolet visible (UV-vis) absorption spectra, fluorescence Excitation-Emission Matrix (EEM) spectra, and molecular docking verified bLf indeed combined with TCH, and caused the changes of conformation of bLf. The influence of TCH on the functional changes of the protein was studied through the analysis of the change of the bLf surface hydrophobicity and research of the binding forces between bLf and iron ion. These results indicated that change in the structure and function of bLf were due to the interaction between bLf and TCH.
29
Ferjani, Hela, Youssef Ben Smida, and Yarub Al-Douri. "First-Principles Calculations to Investigate the Effect of Van der Waals Interactions on the Crystal and Electronic Structures of Tin-Based 0D Hybrid Perovskites." Inorganics 10, no. 10 (September 26, 2022): 155. http://dx.doi.org/10.3390/inorganics10100155.
Анотація:
The electronic structures of four tin-based 0D hybrid perovskites ((NH3(CH2)2C6H5)2[SnCl6], (C6H10N2)[SnCl6], (C9H14N)2[SnCl6], and (C8H12N)2[SnCl6]) were determined by the DFT method employing the pseudopotential plane wave as implemented in the CASTEP code, and the first transition in each compound has been investigated based on the partial density states and dielectric function. According to the structural properties, incorporating organic cations with the appropriate structure, shape, and strong H-bonding functionality into hybrid perovskite crystals is very beneficial for preventing ion migration and thus enhances the efficiency of hybrid perovskite-based devices. Based on those properties employing the DFT+D method for the dispersion force, the effect of Van der Waals interaction on electronic structure was explained based on the nature of the first electronic transition. The similarity between the experimental and optimized structure was investigated by using a Bilbao crystallographic server. The study of optical properties shows that the Van der Waals interactions have a slight effect on the energy level of the curves. However, the profiles of curves are conserved. The absorption curves of the researched compounds are elaborated.
30
Stepanov, V. V., and Nail F. Timerbaev. "Composite Railroad Ties Obtained by the Energy Efficient Recycle of Wooden Railroad Ties." Solid State Phenomena 284 (October 2018): 981–85. http://dx.doi.org/10.4028/www.scientific.net/ssp.284.981.
Анотація:
The article presents the result of research in the field of processing wooden railroad ties and thermoplastic polymer household waste with obtaining composite railroad ties under conditions of energy efficiency of technological processes. The wood of the used wooden ties contains a significant proportion of chemical compounds based on creosote. As a result of the thermal and mechanical action, the creosote compounds in the wood form hydrophobic surfaces, thereby fulfilling the function of the bonding additives. Under the above-mentioned conditions, hydrogen bonds are formed between the components of the wood composite, that, in its turn, allows achieving the task of creating a functional composite, which varies in the compound of elements and the modes of production processes. Experimental studies were held on the nature of justification and correction of theoretical studies. The experimental stand of composite production is realized on the principle of energy efficient cooling cycles of the obtained composite with heat transfer for heating the initial components. The obtained results of experimental studies exceed the regulation values by every measure. The comparison justifies the quality of the experimental samples obtained with respect to these values.
31
Lu, Zhang, Yan, Li, Yu, Chen, Wang, Xie, and Chen. "Resonant Pressure Micro Sensors Based on Dual Double Ended Tuning Fork Resonators." Micromachines 10, no. 9 (August 23, 2019): 560. http://dx.doi.org/10.3390/mi10090560.
Анотація:
This paper presents resonant pressure micro sensors based on dual double ended tuning fork (DETF) resonators, which are electrostatically excited and piezoresistively detected. In operation, the barometric pressure under measurement bends the pressure sensitive diaphragm functioning as the anchor of DETF resonators and therefore produces eigenfrequency shifts of the resonators. Theoretical analyses and finite element analyses (FEA) were conducted to optimize the key geometries of the DETF resonators with enhanced signal to noise ratios (SNRs). In fabrications, key steps including deep reactive ion etching (DRIE) and anodic bonding were used, where sleeve holes were adopted to form electrical connections, leading to high-efficiency structure layout. Experimental results indicate that the presented micro sensors produced SNRs of 63.70 ± 3.46 dB in the open-loop characterizations and differential sensitivities of 101.3 ± 1.2 Hz/kPa, in the closed-loop characterizations. In addition, pressure cycling tests with a pressure range of 5 to 155 kPa were conducted, revealing that the developed micro sensors demonstrated pressure shifts of 83 ± 2 ppm, pressure hysteresis of 67 ± 3 ppm, and repeatability errors of 39 ± 2 ppm. Thus, the developed resonant pressure micro sensors may potentially function as an enabling tool for barometric pressure measurements.
32
Sun, Chang-hai, Jing-hua Hou, Shi-yuan Sun, Yu Zhang, Xin-ran Zhang, and Li-ting Mu. "Green Separation and Extraction of Isofraxidin from Acanthopanax senticosus Using Deep Eutectic Solvent Synthesized from Choline Chloride and Citric Acid." Processes 11, no. 3 (March 20, 2023): 943. http://dx.doi.org/10.3390/pr11030943.
Анотація:
Acanthopanax senticosus (Rupr. Maxim.; AS) is a medicinal plant used in the clinical treatment of cerebrovascular diseases and central nervous system disorders, and it significantly improves blood lipid levels and endothelial cell function in patients with acute cerebral infarction. Isofraxidin, one of the active ingredients of AS, is the core of the plant’s medical effects, and its extraction depends on organic solvents. Deep eutectic solvents (DESs) are new green solvents synthesized by intermolecular hydrogen bonding between hydrogen bond donors (HBD) and hydrogen bond acceptors (HBA) which are non-toxic, have a high separation and extraction efficiency, and are environmentally friendly compared to traditional organic solvents. In this paper, DES was used for the extraction of isofraxidin from AS. The primary findings demonstrated that the DES had a viscosity higher than that of ethanol, and even adding a small amount of water (approximately 10%) would trigger solvent redistribution, leading to a considerable reduction in solvent viscosity. In comparison to ethanol, the extraction rate of isofraxidin by DES was 2–3 times higher. Thus, this work developed a new technique for using green extraction of isofraxidin that has some practical implications.
33
Mateo-Alonso, Aurelio. "(Invited) Making Stacks of Nitrogenated Polycyclic Aromatic Hydrocarbons with Hydrogen Bonds." ECS Meeting Abstracts MA2023-01, no. 11 (August 28, 2023): 1244. http://dx.doi.org/10.1149/ma2023-01111244mtgabs.
Анотація:
Architectures constituted of stacked aromatics play a crucial role in the development of function in biomacromolecules. Recreating this feature on synthetic systems would not only allow understanding and reproducing biological functions but also developing new functions. For instance, the performance of organic field-effect transistors, light-emitting diodes, and solar cells critically depends on the charge transport efficiency of stacks of organic semiconductors. Among different packing configurations, lamellar π-stacking has been identified as an optimal configuration for electronic transport, because of the efficient intermolecular electronic coupling. Nitrogenated polycyclic aromatic hydrocarbons and nanographenes have attracted considerable attention in recent years. Besides the effect of nitrogen doping on the electronic structure, sp2 nitrogens can be engaged in hydrogen bonding interactions as acceptors. We have developed the synthesis of novel architectures constituted of stacked nitrogenated polycyclic aromatic hydrocarbons held together by hydrogen bonds, which include new families of pseudorotaxanes, rotaxanes, foldamers and supramolecular polymers. The synthesis and self-assembling properties of these systems will be discussed together with their charge transporting properties. References [1] A. Riaño, M. Carini, M. Melle-Franco and A. Mateo-Alonso, J. Am. Chem. Soc. 2020, 142, 48, 20481-20488. [2] M. Carini, M. Marongiu, K. Strutyński, A. Saeki, M. Melle-Franco, and A. Mateo-Alonso, Angew. Chem. Int. Ed. 2019, 58, 15788-15792. [3] C. Gozalvez, J. L. Zafra, A. Saeki, M. Melle-Franco, J. Casado and A. Mateo-Alonso, Chem. Sci., 2019, 10, 2743-2749. [4] M. Carini, M. P. Ruiz, I. Usabiaga, J. A. Fernández, E. Cocinero, M. Melle-Franco, I. Diez-Perez, and A. Mateo-Alonso, Nat. Commun., 2017, 8, 15195. Figure 1
34
Zhou, Zengjia, Xiaomeng Sun, Jianjun Cheng, Qingfeng Ban, and Mingruo Guo. "Physicochemical, Digestive, and Sensory Properties of Panax Notoginseng Saponins Encapsulated by Polymerized Whey Protein." Foods 10, no. 12 (November 30, 2021): 2942. http://dx.doi.org/10.3390/foods10122942.
Анотація:
Panax Notoginseng Saponins (PNS) may be beneficial to human health due to their bioactive function. The application of PNS in functional foods was limited due to the bitter taste and low oral bioavailability. PNS were encapsulated by polymerized whey protein (PWP) nanoparticles. The physicochemical, digestive, and sensory properties of the nanoparticles were investigated. Results showed that the nanoparticles had a particle size of 55 nm, the zeta potential of −28 mV, and high PNS encapsulation efficiency (92.94%) when the mass ratio of PNS to PWP was 1:30. Differential Scanning Calorimetry (DSC) results revealed that PNS were successfully encapsulated by PWP. The mainly intermolecular forces between PNS and PWP were hydrogen bonding and electrostatic attraction confirmed by Fourier Transform Infrared Spectroscopy (FTIR). Results of simulated gastrointestinal digestion indicated that the PNS-PWP (1:30) nanoparticles had smaller average particle size (36 nm) after treatment with gastric fluids and increased particle size (75 nm) after treatment with intestinal fluids. Transmission Electron Microscopy (TEM) micrographs reflected that the nanoparticles had irregular spherical structures. The encapsulated PNS exhibited significantly (p < 0.05) decreased bitterness compared to the non-encapsulated PNS confirmed by the electronic tongue. The results indicated that encapsulation of PNS with PWP could facilitate their application in functional foods.
35
Lazzarini, Andrea, Alessia Marino, Roberta Colaiezzi, Oreste De Luca, Giuseppe Conte, Alfonso Policicchio, Alfredo Aloise, and Marcello Crucianelli. "Boronation of Biomass-Derived Materials for Hydrogen Storage." Compounds 3, no. 1 (March 14, 2023): 244–79. http://dx.doi.org/10.3390/compounds3010020.
Анотація:
In spite of the widespread range of hydrogen applications as one of the greenest energy vectors, its transportation and storage still remain among the main concerns to be solved in order to definitively kickstart a rapid takeoff of a sustainable H2 economy. The quest for a simple, efficient, and highly reversible release storage technique is a very compelling target. Many studies have been undertaken to increase H2 storage efficiency by exploiting either chemisorption or physisorption processes, or through entrapment on different porous solid materials as sorbent systems. Among these, biomass-derived carbons represent a category of robust, efficient, and low-cost materials. One question that is still open-ended concerns the correlation of H2 uptake with the kind and number of heteroatoms as dopant of the carbonaceous sorbent matrix, such as boron, aiming to increase whenever possible bonding interactions with H2. Furthermore, the preferred choice is a function of the type of hydrogen use, which may involve a short- or long-term storage option. In this article, after a brief overview of the main hydrogen storage methods currently in use, all the currently available techniques for the boronation of activated carbonaceous matrices derived from recycled biomass or agricultural waste are discussed, highlighting the advantages and drawbacks of each of them.
36
Fevery, S., H. Hallez, D. Vandepitte, and S. Debruyne. "Measuring moisture absorption in structural adhesive joints with fibre Bragg grating sensors." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 234, no. 5 (April 22, 2020): 477–87. http://dx.doi.org/10.1177/0954408920920486.
Анотація:
The increased joint efficiency, distribution of loads and decrease in stress concentrations have led to the increased use of adhesives for structural bonding. However, there are a limited number of techniques for verifying and monitoring the integrity and durability of adhesive bonds. This article studies the potential of estimating the curing and ageing of adhesive bulk samples with embedded fibre Bragg grating sensors through measuring the strain associated with hygroscopic expansion. This is achieved by relating the output of a fibre Bragg grating sensor to the deformation of the structure in which it is embedded. This work considers the possibility of mapping the changing structural resistance to mechanical loading (stiffness) of adhesive bonds as a function of time, under the influence of temperature and moisture as environmental factors. The goal is to map the influence of these environmental factors separately on the one hand, and their combined effect on adhesive bonds, on the other hand. This study subjects several bulk specimens to various environmental ageing loads. The swelling, associated to moisture absorption and that results in mechanical strain, is measured with fibre Bragg grating sensors. The moisture absorption behaviour at different temperatures and environmental relative humidity conditions determined in this way is verified using classical test methods (e.g. differential scanning calorimetry, gravimetric) on multiple fibreless specimens.
37
O’Connor, Cathal, Kate O’Halloran, Alan D. Irvine, Deirdre Murray, Jonathan Hourihane, Michelle Murphy, and Geraldine Boylan. "PA25 Sleep disruption in caregivers of infants with atopic dermatitis." British Journal of Dermatology 191, Supplement_1 (June 28, 2024): i133. http://dx.doi.org/10.1093/bjd/ljae090.280.
Анотація:
Abstract Atopic dermatitis (AD) commonly presents in infancy and is characterized by dermatitis, itch and sleep disturbance. The burdens of disease and treatment in AD are very high. Caregivers of infants with AD are loaded with provision of medical care, emotional distress and sleep disruption. The aim of this study was to assess the sleep of parents of infants with AD in the first year of life by comparing them with parents of healthy age-matched control infants, using both quantitative and qualitative measures. Parental sleep and infant sleep were quantitatively assessed using the Pittsburgh Sleep Quality Index and Brief Infant Sleep Questionnaire at 6, 9 and 12 months. Data on infant AD severity and infant itch were collected using the Eczema Area and Severity Index and a numerical rating scale. Detailed interviews were conducted at 12 months with 10 parents of infants with AD. There were 31 cases and 32 controls. Mothers of cases slept less than mothers of control infants at all timepoints: 6.3, 6.8 and 6.7 h at 6, 9 and 12 months (vs. 7.1, 7.3 and 7.5 h). Sleep onset latency was longer for mothers of infants with AD at 6 months (27.1 vs. 12.8 min, P < 0.05) and 12 months (20.8 vs. 12.6 min, P < 0.05). Sleep efficiency was worse for cases at all timepoints. Fathers had longer sleep onset latency and worse sleep efficiency than controls at 9 months. Themes regarding parental sleep disruption included the relationships between AD severity, itch and sleep disruption; bedtime routine; daytime loss of function; impact on parental relationship, infant bonding and family planning; sleep futility; and strategies to cope with sleep disruption. Mothers, but not fathers, of infants with AD experience significant sleep disruption in the first year of life. Factors that affect parental sleep include infant AD severity and itch.
38
Sommer, J. M., Q. L. Cheng, G. A. Keller, and C. C. Wang. "In vivo import of firefly luciferase into the glycosomes of Trypanosoma brucei and mutational analysis of the C-terminal targeting signal." Molecular Biology of the Cell 3, no. 7 (July 1992): 749–59. http://dx.doi.org/10.1091/mbc.3.7.749.
Анотація:
The compartmentalization of glycolytic enzymes into specialized organelles, the glycosomes, allows the bloodstream form of Trypanosoma brucei to rely solely on glycolysis for its energy production. The biogenesis of glycosomes in these parasites has been studied intensively as a potential target for chemotherapy. We have adapted the recently developed methods for stable transformation of T. brucei to the in vivo analysis of glycosomal protein import. Firefly luciferase, a peroxisomal protein in the lantern of the insect, was expressed in stable transformants of the procyclic form of T. brucei, where it was found to accumulate inside the glycosomes. Mutational analysis of the peroxisomal targeting signal serine-lysine-leucine (SKL) located at the C-terminus of luciferase showed that replacement of the serine residue (Serine548) with a small neutral amino acid (A, C, G, H, N, P, T) still resulted in an import efficiency of 50-100% of the wild-type luciferase. Lysine549 could be substituted with an amino acid capable of hydrogen bonding (H, M, N, Q, R, S), whereas the C-terminal leucine550 could be replaced with a subset of hydrophobic amino acids (I, M, Y). Thus, a peroxisome-like C-terminal SKL-dependent targeting mechanism may function in T. brucei to import luciferase into the glycosomes. However, a few significant differences exist between the glycosomal targeting signals identified here and the tripeptide sequences that direct proteins to mammalian or yeast peroxisomes.
39
Rao, Shengqi, Caochen Jia, Xiangning Lu, Yisheng Yu, Zhirong Wang, and Zhenquan Yang. "Acid–Heat-Induced Fabrication of Nisin-Loaded Egg White Protein Nanoparticles: Enhanced Structural and Antibacterial Stability." Foods 13, no. 11 (June 1, 2024): 1741. http://dx.doi.org/10.3390/foods13111741.
Анотація:
As a natural cationic peptide, Nisin is capable of widely inhibiting the growth of Gram-positive bacteria. However, it also has drawbacks such as its antimicrobial activity being susceptible to environmental factors. Nano-encapsulation can improve the defects of nisin in food applications. In this study, nisin-loaded egg white protein nanoparticles (AH-NEn) were prepared in fixed ultrasound-mediated under pH 3.0 and 90 °C. Compared with the controls, AH-NEn exhibited smaller particle size (112.5 ± 2.85 nm), smaller PDI (0.25 ± 0.01), larger Zeta potential (24 ± 1.18 mV), and higher encapsulation efficiency (91.82%) and loading capacity (45.91%). The turbidity and Fourier transform infrared spectroscopy (FTIR) results indicated that there are other non-covalent bonding interactions between the molecules of AH-NEn besides the electrostatic forces, which accounts for the fact that it is structurally more stable than the controls. In addition, by the results of fluorescence intensity, differential scanning calorimetry (DSC), and X-ray diffraction (XRD), it was shown that thermal induction could improve the solubility, heat resistance, and encapsulation of nisin in the samples. In terms of antimicrobial function, acid–heat induction did not recede the antimicrobial activity of nisin encapsulated in egg white protein (EWP). Compared with free nisin, the loss rate of bactericidal activity of AH-NEn was reduced by 75.0% and 14.0% following treatment with trypsin or a thermal treatment at 90 °C for 30 min, respectively.
40
Hussein Mohamed Ali, Ali, and Aboalmaali Alamin Mohamed. "Review of Punching Shear Strengthening Methods [Case Study: Application of Post Installed Shear Bolt Papers]." FES Journal of Engineering Sciences 9, no. 1 (February 22, 2021): 13–19. http://dx.doi.org/10.52981/fjes.v9i1.657.
Анотація:
Flats slabs became a common solution for buildings because they are easy and fast to build. In the last few years, some building that constructed using flat slab system required strengthening for column to slab junction due to either some imperfections during design, construction or due to increase of the design load in case of change of the building function. The common strengthen methods against punching shear (column heads, drop panels) leave an obvious trace which in most cases conflicts with some extensions parts and may reduce the height of the story considered, thus it can’t be applied in such cases. A relatively new technique was studied, it consists of high tensile steel bolts installed vertically through the slabs by drilling and bonding with high-performance epoxy adhesive and mechanically anchored to the slab surface. Many studies validated the efficiency of the technique in strengthen against punching shear and also in enhancing the ductility of the slab-column connection and the results shows that the method can be applied in practice. In this paper, the post-installed bolts technique is presented and applied in a practical case study. The capacity of the slab enhanced by 53% and it was easy to design and construct. Also, it took not more than few hours for its application. In addition, the building extension utilities (Heating ventilation and air conditioning, communications...etc.) was not harmed because the slab surface remains clear. Those advantages make the technique a favorable option for owners and engineers when strengthening against punching shear.
41
Kotsakis, Stathis D., Vivi Miriagou, Eva Tzelepi та Leonidas S. Tzouvelekis. "Comparative Biochemical and Computational Study of the Role of Naturally Occurring Mutations at Ambler Positions 104 and 170 in GES β-Lactamases". Antimicrobial Agents and Chemotherapy 54, № 11 (9 серпня 2010): 4864–71. http://dx.doi.org/10.1128/aac.00771-10.
Анотація:
ABSTRACT In GES-type β-lactamases, positions 104 and 170 are occupied by Glu or Lys and by Gly, Asn, or Ser, respectively. Previous studies have indicated an important role of these amino acids in the interaction with β-lactams, although their precise role, especially that of residue 104, remains uncertain. In this study, we constructed GES-1 (Glu104, Gly170), GES-2 (Glu104, Asn170), GES-5 (Glu104, Ser170), GES-6 (Lys104, Ser170), GES-7 (Lys104, Gly170), and GES-13 (Lys104, Asn170) by site-specific mutagenesis and compared their hydrolytic properties. Isogenic comparisons of β-lactam resistance levels conferred by these GES variants were also performed. Data indicated the following patterns: (i) Lys104-containing enzymes exhibited enhanced hydrolysis of oxyimino-cephalosporins and reduced efficiency against imipenem in relation to enzymes possessing Glu104, (ii) Asn170-containing enzymes showed reduced hydrolysis rates of penicillins and older cephalosporins, (iii) Ser170 enabled GES to hydrolyze cefoxitin efficiently, and (iv) Asn170 and Ser170 increased the carbapenemase character of GES enzymes but reduced their activity against ceftazidime. Molecular dynamic simulations of GES apoenzyme models, as well as construction of GES structures complexed with cefoxitin and an achiral ceftazidime-like boronic acid, provided insights into the catalytic behavior of the studied mutants. There were indications that an increased stability of the hydrogen bonding network of Glu166-Lys73-Ser70 and an altered positioning of Trp105 correlated with the substrate spectra, especially with acylation of GES by imipenem. Furthermore, likely effects of Ser170 on GES interactions with cefoxitin and of Lys104 on interactions with oxyimino-cephalosporins were revealed. Overall, the data unveiled the importance of residues 104 and 170 in the function of GES enzymes.
42
MOLENDA, J. "MATERIAL PROBLEMS AND PROSPECTS OF Li-ION BATTERIES FOR VEHICLES APPLICATIONS." Functional Materials Letters 04, no. 02 (June 2011): 107–12. http://dx.doi.org/10.1142/s1793604711001816.
Анотація:
This paper reviews material issues of development of Li -ion batteries for vehicles application. The most important of them is safety, which is related to application of nonflammable electrolyte with large electrochemical window and possibility of forming protective SEI (solid/electrolyte interface) to prevent plating of lithium on carbon anode during fast charge of the batteries. The amount of electrical energy, which a battery is able to deliver, depend on the electromotive power of the cell as well as on its capacity — both these factors are related to the chemistry of electrode materials. Nanotechnology applied to electrode materials may be a breakthrough for Li -batteries performance due to extreme reactivity of nanoparticles in relation to lithium. The electrode-electrolyte interface phenomena are decisive for a cell lifetime. Review of physicochemical properties of intercalated transition metal compounds with layered, spinel or olivine-type structure is provided in order to correlate their microscopic electronic properties, i.e. the nature of electronic states, with the efficiency of lithium intercalation process, which is controlled by the chemical diffusion coefficient of lithium. Data concerning cell voltage and character of discharge curves for various materials are correlated with the nature of chemical bonding and electronic structure. Proposed electronic model of the intercalation process allow for prediction and design of operational properties of intercalated electrode materials. Proposed method of measuring the Li x M a X b potential on the basis of the measurement of the electromotive force of the Li / Li +/ Li x M a X b electrochemical cell is a powerful tool of solid state physics allowing for direct observation of the Fermi level changes in such systems as a function of lithium content.
43
Zhang, Na, Jue Kou, and Chunbao Sun. "Investigation on Gold–Ligand Interaction for Complexes from Gold Leaching: A DFT Study." Molecules 28, no. 3 (February 3, 2023): 1508. http://dx.doi.org/10.3390/molecules28031508.
Анотація:
Gold leaching is an important process to extract gold from ore. Conventional alkaline cyanide process and alternative nontoxic lixiviants including thiosulfate, thiourea, thiocyanate, and halogen have been widely investigated. However, density functional theory (DFT) study on the gold complexes Au(CN)2−, Au(S2O3)23−, Au[SC(NH2)2]2+, Au(SCN)2−, and AuCl2− required for discovering and designing new highly efficient and environmentally friendly gold leaching reagents is lacking, which is expected to support constructive information for the discovery and designation of new high-efficiency and environmentally friendly gold leaching reagents. In this study, the structure information, electron-transferring properties, orbital interaction, and chemical bond composition for complexes Au(CN)2−, Au(S2O3)23−, Au[SC(NH2)2]2+, Au(SCN)2−, and AuCl2− depending on charge decomposition analysis (CDA), natural bond orbital (NBO), natural resonance theory (NRT), electron localization function (ELF), and energy decomposition analysis (EDA) were performed based on DFT calculation. The results indicate that there is not only σ-donation from ligand to Au+, but also electron backdonation from Au+ to ligands, which strengthens the coordinate bond between them. Compared with Cl−, ligands CN−, S2O32−, SC(NH2)2, and SCN− have very large covalent contribution to the coordinate bond with Au+, which explains the special stability of Au-CN and Au-S bonds. The degree of covalency and bond energy in Au–ligand bonding decreases from Au(CN)2−, Au(S2O3)23−, Au[SC(NH2)2]2+, Au(SCN)2−, to AuCl2−, which interprets the stability of the five complexes: Au(CN)2− > Au(S2O3)23− > Au[SC(NH2)2]2+ > Au(SCN)2− > AuCl2−.
44
Berarma, Khadidja, Saber Sâad Essaoud, Ahmad A. Mousa, Said M. Azar, and Anas Y. Al-Reyahi. "Opto-electronic, thermodynamic and charge carriers transport properties of Ta2FeNiSn2 and Nb2FeNiSn2 double half-Heusler alloys." Semiconductor Science and Technology 37, no. 5 (April 8, 2022): 055013. http://dx.doi.org/10.1088/1361-6641/ac612b.
Анотація:
Abstract A computational research study of the structural, electronic, and optical characteristics of double half-Heusler alloys Ta2FeNiSn2 and Nb2FeNiSn2 is presented by performing ab initio calculations. The density functional theory framework employs the full-potential linearized augmented plane wave method to solve Kohn–Sham equation as implemented in the Wien2k code. The exchange-correlation potential is processed by using the local density approximation and the generalized gradient approximation–Perdew, Burke, and Ernzerhof approximations to calculate the total energy and other physical properties. The obtained results showed that both alloys possess high cohesive energies, where Nb2FeNiSn2 (7.213 eV atom−1) is more consistent than Ta2FeNiSn2 (6.249 eV atom−1), these remarkable results support the structural stability for both alloys. Also, the thermodynamic stability of both compounds was confirmed through calculating the formation energy as the obtained results were close to the results obtained in as well as given the Open Quantum Materials Database. Electronic characteristics and chemical bonding are illustrated and discussed by computing the electron charge density, density of states, and band structure. Both alloys show semiconductor behavior with (∼0.5 eV) indirect energy bandgap. Also, we have calculated and analyzed the complex dielectric function, absorption coefficient, as well as, reflectivity spectra for both compounds. The semi local Boltzmann transport theory has been employed to treat temperature effect on thermoelectric properties of Ta2FeNiSn2 and Nb2FeNiSn2 compounds where the obtained results appears that both compounds have high coefficient at the normal condition, and they also have a good power factor at the Fermi level, which emphasizes that the thermoelectric efficiency of the two compounds is good and does not require doping. Also, depending on quasi-harmonic model was used for estimating the heat capacity, the lattice thermal conductivity, the thermal expansion and the Debye temperature under the pressure effects.
45
Hathwar, Venkatesha, Mads Jørgensen, Mattia Sist, Jacob Overgaard, Bo Iversen, Xiaoping Wang, Christina Hoffmann, and Alejandro Briseno. "Material Design Inputs from Charge Density Analysis in Organic Semiconductors." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1552. http://dx.doi.org/10.1107/s2053273314084472.
Анотація:
In recent years, semiconducting organic materials have attracted a considerable amount of interest to develop all-organic or hybrid organic-inorganic electronic devices such as organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), or photovoltaic cells. Rubrene (5,6,11,12-tetraphenyltetracene, RUB) is one of the most explored compound in this area as it has nearly 100% fluorescence quantum efficiency in solution. Additionally, the OFET fabricated by vacuum-deposited using orthorhombic rubrene single crystals show p-type characteristics with high mobility up to 20cm2/Vs (Podzorov et al., 2004). The large charge-carrier mobilities measured have been attributed to the packing motif (Fig a) which provides enough spatial overlap of the π-conjugated tetracene backbone. In the same time, RUB undergoes an oxidation in the presence of light to form rubrene endoperoxide (RUB-OX) (Fumagalli et al., 2011). RUB-OX molecules show electronic and structural properties strikingly different from those of RUB, mainly due to the disruption in the conjugate stacking of tetracene moieties. The significant semiconducting property of RUB is not clear yet. In this context, high resolution single crystal X-ray data of RUB (Fig b) and RUB-OX have been collected at 100K. Owing to the presence of weak aromatic stacking and quadrupolar interactions, the neutron single crystal data is also collected at 100K. The C-H bond distances and scaled anisotropic displacement parameters (ADP) of hydrogens from the neutron experiment are used in the multipolar refinements of electron density. The chemical bonding features (Fig c), the topology of electron density and strength of weak interaction are calculated by the Atoms in Molecules (AIM) theory (Bader, 1990). It is further supported by the source function description and mapping of non-covalent interactions based on the electron density. The detailed comparison of two organic semiconductors, RUB and RUB-OX will be discussed.
46
Kratzer, Regina, Stefan Leitgeb, David K. Wilson, and Bernd Nidetzky. "Probing the substrate binding site of Candida tenuis xylose reductase (AKR2B5) with site-directed mutagenesis." Biochemical Journal 393, no. 1 (December 12, 2005): 51–58. http://dx.doi.org/10.1042/bj20050831.
Анотація:
Little is known about how substrates bind to CtXR (Candida tenuis xylose reductase; AKR2B5) and other members of the AKR (aldo–keto reductase) protein superfamily. Modelling of xylose into the active site of CtXR suggested that Trp23, Asp50 and Asn309 are the main components of pentose-specific substrate-binding recognition. Kinetic consequences of site-directed substitutions of these residues are reported. The mutants W23F and W23Y catalysed NADH-dependent reduction of xylose with only 4 and 1% of the wild-type efficiency (kcat/Km) respectively, but improved the wild-type selectivity for utilization of ketones, relative to xylose, by factors of 156 and 471 respectively. Comparison of multiple sequence alignment with reported specificities of AKR members emphasizes a conserved role of Trp23 in determining aldehyde-versus-ketone substrate selectivity. D50A showed 31 and 18% of the wild-type catalytic-centre activities for xylose reduction and xylitol oxidation respectively, consistent with a decrease in the rates of the chemical steps caused by the mutation, but no change in the apparent substrate binding constants and the pattern of substrate specificities. The 30-fold preference of the wild-type for D-galactose compared with 2-deoxy-D-galactose was lost completely in N309A and N309D mutants. Comparison of the 2.4 Å (1 Å=0.1 nm) X-ray crystal structure of mutant N309D bound to NAD+ with the previous structure of the wild-type holoenzyme reveals no major structural perturbations. The results suggest that replacement of Asn309 with alanine or aspartic acid disrupts the function of the original side chain in donating a hydrogen atom for bonding with the substrate C-2(R) hydroxy group, thus causing a loss of transition-state stabilization energy of 8–9 kJ/mol.
47
Ali, Israt, Muhammad Faraz Ud Din, Daniele T. Cuzzupè, Azhar Fakharuddin, Hitler Louis, Ghulam Nabi, and Zhi-Gang Gu. "Ti3C2Tx-Modified PEDOT:PSS Hole-Transport Layer for Inverted Perovskite Solar Cells." Molecules 27, no. 21 (November 2, 2022): 7452. http://dx.doi.org/10.3390/molecules27217452.
Анотація:
PEDOT:PSS is a commonly used hole-transport layer (HTL) in inverted perovskite solar cells (PSCs) due to its compatibility with low-temperature solution processing. However, it possesses lower conductivity than other conductive polymers and metal oxides, along with surface defects, limiting its photovoltaic performance. In this study, we introduced two-dimensional Ti3C2Tx (MXene) as an additive in the PEDOT:PSS HTL with varying doping concentrations (i.e., 0, 0.03, 0.05, and 0.1 wt.%) to tune the electrical conductivity of PEDOT:PSS and to modify the properties of the perovskite film atop it. We noted that the grain size of the CH3NH3PbI3 (MAPI3) perovskite layer grown over an optimal concentration of MXene (0.03 wt.%)-doped PEDOT:PSS increased from 250 nm to 400 nm, reducing charge recombination due to fewer grain boundaries. Ultraviolet photoelectron spectroscopy (UPS) revealed increased work function (WF) from 4.43 eV to 4.99 eV with 0.03 wt.% MXene doping, making the extraction of holes easier due to a more favorable energy level alignment with the perovskite. Quantum chemical investigations based on density functional theory (DFT) were conducted at the ωB97XD/6-311++G(d,p) level of theory to provide more insight into the stability, bonding nature, and optoelectronic properties of the PEDOT:PSS–MXene system. The theoretical investigations revealed that the doping of PEDOT:PSS with Ti3C2Tx could cause a significant effect on the electronic properties of the HTL, as experimentally demonstrated by an increase in the electrical conductivity. Finally, the inverted PSCs employing 0.03 wt.% MXene-doped PEDOT:PSS showed an average power conversion efficiency (PCE) of 15.1%, up from 12.5% for a reference PSC employing a pristine PEDOT:PSS HTL. The champion device with a 0.03 wt.% MXene–PEDOT:PSS HTL achieved 15.5% PCE.
48
Tellechea, Edurne, Aaron C. Asensio, Paula Ciaurriz, Javier Buezo, Pedro López-Gómez, Marina Urra, and Jose F. Moran. "A Study of the Interface of Gold Nanoparticles Conjugated to Cowpea Fe-Superoxide Dismutase." Antioxidants 11, no. 11 (October 22, 2022): 2082. http://dx.doi.org/10.3390/antiox11112082.
Анотація:
The iron superoxide dismutase (FeSOD) is a first barrier to defend photosynthetic organisms from superoxide radicals. Although it is broadly present in plants and bacteria, FeSODs are absent in animals. They belong to the same phylogenic family as Mn-containing SODs, which are also highly efficient at detoxifying superoxide radicals. In addition, SODs can react with peroxynitrite, and FeSOD enzyme has already been used to evaluate the anti-nitrative capacity of plant antioxidants. Gold nanoparticles (AuNPs) have been shown to significantly improve the functionality and the efficiency of ligands, providing they are properly assembled. In this work, the characteristics of the recombinant cowpea (Vigna unguiculata) FeSOD (rVuFeSOD) immobilized onto AuNPs were investigated as a function of (1) NP surface chemistry and (2) biofunctionalization methods, either physical adsorption or covalent bonding. The NP surface chemistry was studied by varying the concentration of the ligand molecule 11-mercaptoundecanoic acid (MUA) on the NP surface. The coverage and activity of the protein on AuNPs was determined and correlated to the surface chemistry and the two biofunctionalization methods. rVuFeSOD–AuNPs conjugate stability was monitored through absorption measurements, agarose gel electrophoresis and DLS, enzymatic activity by a colorimetric assay and by in-gel activity assay, and coverage was measured by colorimetric assay. When using physical adsorption, the NP is the most perturbing agent for the activity of the enzyme. In contrast, only the NP coverage was affected by MUA ligand concentration. However, during covalent attachment, both the NP and the concentration of MUA on the surface influenced the enzyme activity, while the coverage of the NP remained constant. The results evidence the importance of the biomolecule and AuNP interaction for the functionality of the hybrid. These strategies can be used to develop electrochemical biosensors for O2•− and for peroxynitrite in biomedical applications.
49
Zachman, Michael J., Haoran Yu, Shengwen Liu, Yachao Zeng, Yi Li, Gang Wu, and David A. Cullen. "Advanced Electron Microscopy Techniques for PGM-Free Catalyst Characterization." ECS Meeting Abstracts MA2022-02, no. 39 (October 9, 2022): 1447. http://dx.doi.org/10.1149/ma2022-02391447mtgabs.
Анотація:
Hydrogen fuel cells currently rely on expensive platinum group metal nanoparticle catalysts [1]. For green hydrogen production and utilization to become widely commercially viable, the cost of the devices that produce and utilize hydrogen must be significantly reduced. Platinum group metal-free (PGM-free) catalysts have the potential to greatly reduce this cost, and materials consisting of single transition metal atoms embedded in a nitrogen-doped graphitic carbon structure have shown particular promise for use as fuel cell cathodes [2]. A better understanding of the active site properties in these materials is still needed, however, to improve their stability and design new active site structures with enhanced properties [3]. Due to the atomic-scale nature of the active sites in these materials, scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS) have proven invaluable for demonstrating their atomically dispersed nature and composition [4]. Conventional STEM techniques have limited ability to correlate the local bonding environment and oxidation state of the metal atoms, for example, or track changes in the catalyst structure both during synthesis and as a result of cycling, which would provide a deeper understanding of the relationship between active site and catalyst properties. Here, we demonstrate advanced electron microscopy techniques that provide both enhanced and previously inaccessible information about PGM-free catalysts and their active sites. We show developments in automated identification of metal atom positions, which we use both to generate statistics about interatomic distances and to automatically position the STEM probe on individual atoms for EELS data acquisition. The former allows information about the presence of dual-metal site structures to be extracted, for example, and the latter allows compositional information with improved SNR to be obtained. Rapid automatic probe positioning also presents the opportunity for measuring the effect of local bonding environment on metal atom oxidation state, which cannot be obtained manually since these sites are typically unstable under the beam. In addition, we will show identical-location STEM (IL-STEM) techniques that allow the evolution of catalyst morphology and properties to be tracked at high resolution across synthesis steps and accelerated stress tests [5]. In particular, we use IL-STEM imaging and EELS to track deposition of graphitic material on the surface of a PGM-free catalyst that significantly improves the material’s durability, as well as track the change in the nanoscale graphitic carbon structure of the material as a function of electrochemical cycling. By providing access to enhanced compositional and bonding state information, as well as the ability to track properties as a material evolves, these techniques will advance our knowledge of PGM-free catalysts and enable better control over their properties in the future, accelerating wide-spread use of hydrogen fuel cells [6]. References: [1] D.A. Cullen et al., Nat. Energy 6, 462 (2021). [2] G. Wu, Front. Energy 11, 286 (2017). [3] U. Martinez et al., Adv. Mater. 31, 1806545 (2019). [4] H.T. Chung et al., Science 357, 479 (2017). [5] H. Yu et al., ACS Appl. Mater. Interfaces (2022). [6] This work was supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office under the Electrocatalysis (ElectroCat) consortium. Electron microscopy research was supported by the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory.
50
Lin, Zhiqun. "(Invited) Tailoring Crystal Morphology and Interfacial Charge Transfer in Perovskite Solar Cells." ECS Meeting Abstracts MA2022-01, no. 13 (July 7, 2022): 916. http://dx.doi.org/10.1149/ma2022-0113916mtgabs.
Анотація:
The past decade has witnessed tremendous advances in organometal halide perovskite solar cells (PSCs) due largely to the stellar set of optoelectronic properties of perovskites such as high absorption coefficient, long carrier diffusion length, and low electron-hole recombination. Notably, organolead halide PSC has reached a certified champion power conversion efficiency (PCE) of 25.5%. In this talk, first, I will discuss a meniscus-assisted solution printing (MASP) strategy to yield large-grained dense perovskite film with good crystallization and preferred orientation. The growth kinetics of perovskite crystals is scrutinized by in-situ optical microscopy tracking to understand the crystallization mechanism. The perovskite film produced by MASP exhibits excellent optoelectronic properties for high-efficiency PSCs. We also MASP cross-aligned conductive nanowires for biodegradable flexible PSCs. Second, I will present a simple yet robust acid-treatment strategy to judiciously create an amorphous TiO2 buffer layer intimately situated on the anatase TiO2 surface as electron transport layer (ETL) for efficient electron transport. The facile acid treatment is capable of weakening the bonding of zigzag octahedral chains in anatase TiO2, thereby shortening staggered octahedron chains to form an amorphous buffer layer on the anatase TiO2 surface. Such amorphous TiO2-coated ETL possesses an increased electron density due to the presence of oxygen vacancies, leading to efficient electron transfer from perovskite to TiO2. Compared to pristine TiO2-based devices, the perovskite solar cells (PSCs) with acid-treated TiO2 ETL exhibit enhanced short circuit current and PCE. Notably, we also tailor carrier dynamics in PSCs via precise dimension and architecture control and interfacial positioning of plasmonic nanoparticles in TiO2 ETL. Third, I will demonstrate synergistic cascade carrier extraction via dual interfacial positioning of ambipolar black phosphorene (BP) for high-efficiency PSCs. Concurrently enhanced carrier extraction at both electron transport layer/perovskite and perovskite/hole transport layer interfaces is achieved through judicious design and position of BP with tailored thickness as dual-functional nanomaterials. Fourth, I will introduce a robust route that simultaneously allows defect passivation and reduced energy difference between perovskite and hole transport layer (HTL) via the judicious placement of polar chlorine-terminated silane molecules at the interface. An integrated experimental and density functional theory study demonstrates that the dipole layer formed by the silane molecules decreases the perovskite work function, imparting an Ohmic character to the perovskite/HTL contact. The corresponding PSCs manifest a nearly 20% increase in PCE over pristine devices and a markedly enhanced device stability. Finally, I will show the spatial poling-initiated perovskite self-healing for defects passivation. The spatial poling significantly enhances the ion migration recovery after removing electric field. Particularly, the ion recovery tends to form a perfect lattice structure, leading to decreased defects in the perovskite layer with enhanced stability.