Analysis Of Surface Potential Research Articles

Using Hybrid PDI-Fe3O4 Nanoparticles for Capturing Aliphatic Alcohols: Halogen Bonding vs. Lone Pair-π Interactions.

In this study, Fe3O4 nanoparticles (FeNPs) decorated with halogenated perylene diimides (PDIs) have been used for capturing VOCs (volatile organic compounds) through noncovalent binding. Concretely, we have used tetrachlorinated/brominated PDIs as well as a nonhalogenated PDI as a reference system. On the other hand, methanol, ethanol, propanol, and butanol were used as VOCs. Experimental studies along with theoretical calculations (the BP86-D3/def2-TZVPP level of theory) pointed to two possible and likely competitive binding modes (lone pair-π through the π-acidic surface of the PDI and a halogen bond via the σ-holes at the Cl/Br atoms). More in detail, thermal desorption (TD) experiments showed an increase in the VOC retention capacity upon increasing the length of the alkyl chain, suggesting a preference for the interaction with the PDI aromatic surface. In addition, the tetrachlorinated derivative showed larger VOC retention times compared to the tetrabrominated analog. These results were complemented by several state-of-the-art computational tools, such as the electrostatic surface potential analysis, the Quantum Theory of Atoms in Molecules (QTAIM), as well as the noncovalent interaction plot (NCIplot) visual index, which were helpful to rationalize the role of each interaction in the VOC···PDI recognition phenomena.

A Novel Mechano-Synthesized Zeolitic Tetrazolate Framework for a High-Performance Triboelectric Nanogenerator and Self-Powered Selective Neurochemical Detection.

Designing a high-performing triboelectric novel material with eco-friendly, rapid, and cost-effective synthesis is the future of material research in triboelectric nanogenerators (TENG). We report a mechanochemical ball mill synthesis of a zeolitic tetrazolate framework (ZTF-8) that is isostructural with the well-known zeolitic imidazolate framework ZIF-8. ZTF-8 is extremely stable in water, 0.1 M aqueous acid/base solutions for 75 days at 25 °C, and boiling water (100 °C) for 7 days. Kelvin probe force microscopy and molecular electrostatic surface potential computational analysis exhibited that ZTF-8 has a very high positive surface potential. Atomic force microscopy and three-dimensional digital microscopy studies reveal the high roughness profile in the ZTF-8 film. The unique structure, exceptional acid/base stability, good dielectric property, and high roughness profile combined with the extremely electropositive nature of ZTF-8 make it a suitable candidate as a polymer-free triboelectric positive material in TENG with outstanding performance (power density of 720 mW/m2). High triboelectric output was further validated using the COMSOL Multiphysics simulation tool. Simple mechanical hand tapping of the ZTF-based TENG (ZTF-TENG) device generates high electric output, which was practically used to power numerous low-powered devices like tally counter, clinical thermometer, and digital clock and also illuminates 125 light-emitting diodes. In addition, the efficiency of ZTF-TENG was utilized as a self-powered device for a selective dopamine (DA) sensor with good sensitivity (377.76 mV/μM/cm2), wide range linearity (5-120 μM), and excellent limit of detection (0.42 μM).

Structural homology-based identification of BEN domain proteins in Poxviruses

BEND family transcription factors directly interact with DNA through BEN domains and have been found across metazoan species. Interestingly, certain insect and mammalian viruses have also hijacked Bend genes into their genome. However, the phylogenetic classification and evolution of these viral BEN domains remain unclear. Building on our previous finding that in silico method accurately determine the 3D model of BEN domains, we used AlphaFold2 to predict the tertiary structures of poxviral BEN domains for comprehensive homologous comparison.We revealed that the majority of poxviral BEN modules exhibit characteristics of type II BEN. Additionally, electrostatic surface potential analysis found various poxviral BEN domains, including the first BEN of OPG067 in Orthopoxvirus, the third BEN of OPG067 in Yatapoxvirus and the third BEN of MC036R in MCV, have positively charged protein surfaces, indicating a structural basis for DNA loading. Notably, MC036R shares structural resemblance with human BEND3, as they both contain four BEN domains and an intrinsically disordered region. In summary, our discoveries provide deeper insights into the functional roles of BEN proteins within poxviruses.

Nanofluid-Guided Janus Membrane for High-Efficiency Electricity Generation from Water Evaporation.

Harvesting electricity from widespread water evaporation provides an alternative route to cleaner power generation technology. However, current evaporation power generation (EPG) mainly depends on the dissociation process of certain functional groups (e.g., SO3 H) in water, which suffers from low power density and short-term output. Herein, the Janus membrane is prepared by combining nanofluid and water-grabbing material for EPG, where the nanoconfined ionic liquids (NCILs) serve as ion sources instead of the functional groups. Benefiting from the selective and fast transport of anions in NCILs, such EPG demonstrates excellent power performance with a voltage of 0.63V, a short-circuit current of 140µA, and a maximum power density of 16.55 µW cm-2 while operating for at least 180 h consistently. Molecular dynamics (MD) simulation and surface potential analysis reveal the molecular mechanism, that is, the diffusion of Cl- anions during evaporation is much faster than that of cations, generating the voltage and current across the membrane. Furthermore, the device performs well in varying environmental conditions, including different water temperatures and sources of evaporating water, showcasing its adaptability and integrability. Overall, the nanofluid-guided Janus membrane can efficiently transform low-grade thermal energy in evaporation into electricity, showing a competitive advantage over other sustainable applied approaches.

Susceptibility of bovine to SARS-CoV-2 variants of concern: insights from ACE2, AXL, and NRP1 receptors

The possibilities of cross-species transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) between humans and important livestock species are not yet known. Herein, we used the structural and genetic alignment and surface potential analysis of the amino acid (aa) in angiotensin-converting enzyme 2 (ACE2), tyrosine kinase receptor UFO (AXL), and neuropilin 1 (NRP1) in different species with substantial public health importance. The residues interfacing with the N-terminal domain (NTD) or receptor-binding domain (RBD) of S were aligned to screen the critical aa sites that determined the susceptibility of the SARS-CoV-2 to the host. We found that AXL and NRP1 proteins might be used as the receptors of SARS-CoV-2 in bovines. However, ACE2 protein may not be considered to be involved in the cross-species transmission of SARS-CoV-2 VOCs in cattle because the key residues of the ACE2-S-binding interface were different from those in known susceptible species. This study indicated that emerging SARS-CoV-2 variants potentially expand species tropism to bovines through AXL and NRP1 proteins.

Integrated Three-Dimensional Microdevice with a Modified Surface for Enhanced DNA Separation from Biological Samples.

Functional interfaces and devices for rapid adsorption and immobilization of nucleic acids (NAs) are significant for relevant bioengineering applications. Herein, a microdevice with poly(acrylic acid) (PAA) photosensitive resin was integrated by three-dimensional (3D) printing, named DPAA for short. Precise microscale structures and abundant surface carboxyl functional groups were fabricated for fast and high-throughput deoxyribonucleic acid (DNA) separation. Surface modification was then done using polydopamine (PDA) and poly(ethylene glycol) (PEG) to obtain modified poly(acrylic acid) (PAA)-based devices DPDA-PAA and DPEG-PAA rich in amino and hydroxyl groups, respectively. The fabricated device DPAA possessed superior printing accuracy (40-50 μm). Functionalization of amino and hydroxyl was successful, and the modified devices DPDA-PAA and DPEG-PAA maintained a high thermal stability like DPAA. Surface potential analysis and molecular dynamics simulation indicated that the affinity for DNA was in the order of DPDA-PAA > DPEG-PAA > DPAA. Further DNA separation experiments confirmed the high throughput and high selectivity of DNA separation performance, consistent with the predicted affinity results. DPDA-PAA showed relatively the highest DNA extraction yield, while DPEG-PAA was the worst. An acidic binding system is more favorable for DNA separation and recovery. DPDA-PAA showed significantly better DNA extraction performance than DPAA in a weakly acidic environment (pH 5.0-7.0), and the average DNA yield of the first elution was 2.16 times that of DPAA. This work validates the possibility of modification on integrated 3D microdevices to improve their DNA separation efficiency effectively. It also provides a new direction for the rational design and functionalization of bioengineering separators based on nonmagnetic methods. It may pave a new path for the highly efficient polymerase chain reaction diagnosis.

Effect of Co content on the microstructure, mechanical properties and corrosion behavior of Zr alloys

The microstructure, mechanical properties and corrosion properties of Zr-xCo (x = 0, 2, 4, 6, 8, 10 at.%) binary alloys have been systematically studied. The microstructure of the alloy was analyzed by optical microscope, X-ray diffractometer, scanning electron microscope, transmission electron microscope and electron probe, and the existence of Zr3Co phase was found. The mechanical properties of the alloy were analyzed by compressive stress-strain test and Vickers hardness test. It was found that the addition of Co improved the strength of the alloy, and the ductility of the alloy was the best when the content of Co reached 6 at.%. Through electrochemical experiments, the corrosion properties of the alloy were analyzed, and it was found that the addition of Co had an active influence on the corrosion resistance of the alloy, which made the passivation film formed by the sample denser, and effectively alleviated the corrosion behavior of the alloy. Surface potential analysis was performed with atomic force microscope. Through X-ray photoelectron spectroscopy analysis of passive film, it is revealed that passive film mainly consists of ZrO2, Co3O4, Co(OH)2 and Zr2O3.

A thorough investigation of the adsorption of metal ions in seawater on d-glucose and its analogues: A theoretical study

d-glucose and its analogues have been studied as potential adsorbents for the removal of Na+, K+, Mg2+ and Ca2+ ions in adsorption desalination studies. Density Functional Theory calculations have been employed to examine the preferential adsorption of these ions at all the available sites of the three chosen substrates. Structure, energy, frontier molecular orbital and natural bond order analyses revealed the nature and strength of the non-bonded interactions between the adsorbate and the adsorbent. Divalent metal ions formed stronger interactions with the substrates than the monovalent metal ions. Molecular electrostatic surface potential analysis helped to understand the charge separation after the metal ion (Mn+) adsorption at the available sites on the substrate. The stability of the studied Mn+-substrate complexes is attributed to non-bonded interactions between the polar heteroatoms on the carbon backbone of the substrate with the positively charged Mn+ ions through electronic charge transfer. These findings can significantly impact the design of new adsorbents for adsorption desalination technology based on naturally available substrates that can be used effectively at ambient temperature.

High-Performance Artificial Synapse Based on CVD-Grown WSe2 Flakes with Intrinsic Defects

High-performance artificial synaptic devices with rich functions are highly desired for the development of an advanced brain-like neuromorphic system. Here, we prepare synaptic devices based on a CVD-grown WSe2 flake, which has an unusual morphology of nested triangles. The WSe2 transistor exhibits robust synaptic behaviors such as excitatory postsynaptic current, paired-pulse facilitation, short-time plasticity, and long-time plasticity. Furthermore, due to its high sensitivity to light illumination, the WSe2 transistor exhibits excellent light-dosage-dependent and light wavelength-dependent plasticity, which endow the synaptic device with more intelligent learning and memory functions. In addition, WSe2 optoelectronic synapses can mimic "learning experience" behavior and associative learning behavior like the brain. An artificial neural network is simulated for pattern recognition of hand-written digital images in the MNIST data set and the best recognition accuracy could reach 92.9% based on weight updating training of our WSe2 device. Detailed surface potential analysis and PL characterization reveal that the intrinsic defects generated in growth are dominantly responsible for the controllable synaptic plasticity. Our work suggests that the CVD-grown WSe2 flake with intrinsic defects capable of robust trapping/de-trapping charges holds great application prospects in future high-performance neuromorphic computation.

Comparative investigation of carbon nanotubes dispersion using surfactants: A molecular dynamics simulation and experimental study

Poor dispersion is a major obstacle limiting the practical application of carbon nanotubes (CNTs) in composites. A comparative analysis of the dispersion ability of six representative surfactants for CNTs was conducted using both molecular dynamics (MD) simulations and experimental investigations. The dispersion stability of the surfactant-assisted CNTs was characterised via ultraviolet–visible spectroscopy, surface potential analysis, and transmission electron microscope. The chemical structures of the surfactants and CNTs-surfactant ratios directly affected the adsorption behaviours of surfactants on CNTs surface, thus exerting significant impacts on the final dispersion effect. The interaction energy analysis showed that Triton X-100 and sodium dodecyl benzenesulfonate (SDBS) exhibited the strongest interaction with CNTs with respect to other surfactants, whereas sodium dodecyl sulfate (SDS) displayed the weakest interaction. The van der Waals forces were the main driving forces of this adsorption process. Several structural factors, such as the presence of benzene rings and long alkyl chains, were important and favourable in enhancing the adsorption efficiency of surfactants on CNTs surface. The MD simulation results also revealed that different concentrations of surfactants in the system led to different adsorption behaviours, as low amounts of surfactants tended to exhibit random adsorption without a particular orientation on CNTs surface. Based on the experimental results, Triton X-100 and SDBS showed the strongest dispersion ability, which was consistent with the MD calculation results. Notably, excess amounts of surfactants above the optimum amount caused the entanglement and agglomeration of CNTs owing to the interaction between unfavourable micelles. This study provides an effective guidance for the selection of optimal surfactants for CNTs dispersion.

Electrostatic Surface Potential as a Key Parameter in Virus Transmission and Evolution: How to Manage Future Virus Pandemics in the Post-COVID-19 Era.

Virus-cell interactions involve fundamental parameters that need to be considered in strategies implemented to control viral outbreaks. Among these, the surface electrostatic potential can give valuable information to deal with new epidemics. In this article, we describe the role of this key parameter in the hemagglutination of red blood cells and in the co-evolution of synaptic receptors and neurotransmitters. We then establish the functional link between lipid rafts and the electrostatic potential of viruses, with special emphasis on gangliosides, which are sialic-acid-containing, electronegatively charged plasma membrane components. We describe the common features of ganglioside binding domains, which include a wide variety of structures with little sequence homology but that possess key amino acids controlling ganglioside recognition. We analyze the role of the electrostatic potential in the transmission and intra-individual evolution of HIV-1 infections, including gatekeeper and co-receptor switch mechanisms. We show how to organize the epidemic surveillance of influenza viruses by focusing on mutations affecting the hemagglutinin surface potential. We demonstrate that the electrostatic surface potential, by modulating spike-ganglioside interactions, controls the hemagglutination properties of coronaviruses (SARS-CoV-1, MERS-CoV, and SARS-CoV-2) as well as the structural dynamics of SARS-CoV-2 evolution. We relate the broad-spectrum antiviral activity of repositioned molecules to their ability to disrupt virus-raft interactions, challenging the old concept that an antibiotic or anti-parasitic cannot also be an antiviral. We propose a new concept based on the analysis of the electrostatic surface potential to develop, in real time, therapeutic and vaccine strategies adapted to each new viral epidemic.

Nucleation of water vapor on nanodimpled surfaces: Effects of curvature radius and surface wettability

• The effects of dimple curvature radius and wettability on nucleation are studied. • Surface potential energy analysis confirms nucleation sites. • Increasing dimple curvature radius worsens nucleation. • More dimples increase vapor nucleation probability at lower surface subcooling. • The coupling effect of the surface structure affects the nucleation. The mechanisms of vapor nucleation on nanostructured surfaces, whose geometrical characteristic sizes are comparable to those of nuclei, remain unsatisfactorily explored. This study investigates the correlations among the wettability, dimple curvature radius, and nucleation characteristics of vapor molecules on nanodimpled surfaces through molecular dynamics simulations. The surface potential energy analysis demonstrates that nucleation sites are located in the interior of dimples. With an increase in surface hydrophobicity or dimple curvature radius, a higher nucleation energy barrier would render nucleation more difficult. The critical sizes of nuclei obtained from MD simulation are larger than the results estimated by the classical nucleation theory. The discrepancy is attributed to the fact that the formed nucleus in simulations deviates from the spherical cap assumption. The formation of nuclei is not observed at all dimples, indicating that the coupling effects of surface structure would affect nucleation. Additionally, the comparisons of coalescence phenomena noted for different dimple numbers reveal the benefits of increasing the dimple number, which can be attributed to the fact that more high-energy nucleation sites increase the nucleation probability of vapor molecules at reduced surface subcooling. Therefore, an enhanced condensation performance can be achieved by artificially controlling the dimple number.

Amyotrophic lateral sclerosis disease-related mutations disrupt the dimerization of superoxide dismutase 1 - A comparative molecular dynamics simulation study

More than 150 genes are involved in amyotrophic lateral sclerosis (ALS), with superoxide dismutase 1 (SOD1) being one of the most studied. Mutations in SOD1 gene, which encodes the enzyme SOD1 is the second most prevalent and studied cause of familial ALS. SOD1 is a ubiquitous, homodimeric metalloenzyme that forms a critical component of the cellular defense against reactive oxygen species. Several mutations in the SOD1 enzyme cause misfolding, dimerization instability, and increased aggregate formation in ALS. However, there is a lack of information on the dimerization of SOD1 monomers and the mechanistic underpinnings on how the pathogenic mutations disrupt the dimerization mechanism. Here, we presented microsecond-scale molecular dynamics (MD) simulations to unravel how interface-based mutations compromise SOD1 dimerization and provide mechanistic understanding into the corresponding process using WT and three interface-based mutant systems (A4V, T54R, and I113T). Structural stability analysis showed that the mutant systems displayed disparate variations in the catalytic sites which may directly alter the stability and activity of the SOD1 enzyme. Based on the dynamic network analysis and principal component analysis, it has been identified that the mutations weakened the correlated motions along the dimer interface and altered the protein conformational behavior, thus weakening the stability of dimer formation. Moreover, the simulation results identified crucial residues such as G51, D52, G114, I151, and Q153 in establishing the dimerization interaction network, which were weakened or absent in the presence of interfacial mutants. Surface potential analysis on mutant systems also displayed changes in the dimerization potential, thus showing the unfavorable dimer formation. Furthermore, network analysis identified the hotspot residues necessary for SOD1 signal transduction which were surprisingly found in the catalytic sites rather than the anticipated dimerization interface.

Intrinsic bitunable magnetism/polarity behavior in 2D Janus Cr2I3Y3 (Y = F, Cl, or Br) systems

Two-dimensional (2D) magnetoelectric (ME) materials with spontaneous magnetism and polarity have drawn a lot of research interest due to their potentially valuable physics and spintronic applications. One of the obstacles in the current study of 2D ME materials is to achieve flexible magnetism/polarity switches because of a fundamental contradiction between magnetism and polarity. In this work, we propose an intrinsic magnetism/polarity switchable 2D Janus structure Cr2I3Y3 (Y = F, Cl, or Br) with mechanical and thermodynamic stability. Janus Cr2I3Y3 monolayers show indirect-gap semiconductors with ferromagnetic ordering. Intrinsic vertical electric polarity (EP) in Janus Cr2I3Y3 structures is investigated by surface potential difference analysis and dipole calculations. We discover that there is an obvious ME coupling between magnetic anisotropy energy (MAE) and EP. MAE can be obviously tuned by rotating the orientations of spins within yz and zx vertical planes, and the easily distinguishable MAE on vertical planes has strong inherent relevance with vertical EP. Simultaneously, magnetic phase transition and magnetic moments can be manipulated by introducing vertical strain, which directly corresponds to the linear response of the EP strength. Our work provides a promising candidate for realizing the spintronic devices with multiple functionalities.

Design and Performance Investigation of a Source Pocket-Based Charge Plasma TFET with Gate Underlap Technique

This paper presents a source pocket-based charge plasma tunnel field-effect transistor with gate-drain underlap engineering (SP-GDUCPTFET) intending to maximize the ION/IAmb current switching ratio. Introducing a low bandgap Si0.6Ge0.4 pocket in the source region enhances the ON-state current (ION) thanks to the lower tunneling distance at the proximity of the source interface. Similarly, the device with underlap technique provides an 8-decades reduced ambipolar current (IAmb) with a lower subthreshold swing (SS). The proposed structure provides a maximum ION/IAmb current ratio of 1.88 × 1013 μA μA−1 and ION/IOFF ratio of 1.04 × 1014 μA μA−1. Further, the suggested device’s DC and analog/RF performance with underlap length (Lund) of 15 nm is investigated extensively. DC performances such as drain current characteristics, energy band diagram, surface potential analysis, band-to-band tunneling (BTBT) rate, lateral electric field, current ratios, the concentration of charges, and output characteristics have been discussed. In addition, the radio frequency (RF) analysis and the key figure of merits have been analyzed thoroughly to exhibit its superiority in high-frequency applications.

Hirshfeld surface and electrostatic potential surface analysis of clozapine and its solubility and molecular interactions in aqueous blends

Solubility and relevant thermodynamic properties as well as molecular interactions of clozapine in aqueous systems of protic cosolvent, e.g. isopropanol, and aprotic cosolvents such as acetonitrile, dimethyl sulfoxide (DMSO) and N-methyl-2-pyrrolidinone (NMP) are focus of this paper. The intermolecular interactions and overall charge distribution of clozapine were respectively investigated by using Hirshfeld surface analysis and molecular electrostatic potential surface. All experimentations were executed using a shake-flask approach under p = 101.2 kPa (local pressure) from 278.15 (293.15) to 323.15 (333.15) K. The minimum solubility data of clozapine appeared in neat water for each aqueous system at 278.15 K; and the maximum one, in neat cosolvent at 328.15 K. Correlation of the solubility data (mole fraction) through Jouyban–Acree and MRS models acquired acceptable results with relative average deviations (RAD) of no>9.15 %. The solvent descriptors of hydrogen-bonding basicity, solubility parameter and dipolarity-polarizability predominantly controlled the clozapine solubility variation through the quantitative analysis of linear solvation energy relationships in terms of the solubility data at 298.15 K. The extended Hildebrand solubility approach was also employed here to correlate the solubility and study the solvation behavior of solutions. Quantitatively analysis of preferential solvation of clozapine by solvent species in solutions was conducted by the method of inverse Kirkwood–Buff integrals. In the solutions with middle and cosolvent-rich compositions, the parameters of preferential solvation for DMSO, NMP, acetonitrile or isopropanol were positive, which specified that preferential solvation of clozapine was made by co-solvent. In addition, the thermodynamic properties of dissolution of clozapine along with enthalpy–entropy compensation were derived and deeply discussed.

Impact of DBDS and Silver Sulfide on the Performance of Thermally Aged Mineral oil Impregnated Pressboard Material

The corrosive sulfur compounds present in the mineral oil causes the formation of dibenzyl disulfide (DBDS) complex and it can also erode the on-load tap changing selector contacts leading to generation of silver sulfide (AgS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ).The present work reports the effect of DBDS and Ag <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S concentrations in mineral oil on thermally aged pressboard material. The results demonstrate that surface discharge inception voltage (SDIV) is higher for the aged pressboard specimen. The higher concentrations of DBDS showed a reduction of more than 50% in the magnitude of SDIV compared to its effect with the addition of Ag <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S. The surface potential analysis indicates a higher initial potential for the aged specimens with an increased half lifetime. In addition, only deep traps observed on the aged specimens with a slight right shift in its trap energy level. The mechanical strength of aged pressboard specimens with DBDS and Ag <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S is understood using tensile testing and simultaneous analysis is captured using Digital Image Correlation (DIC) technique to understand its strain percentage at different areas on the pressboard material during its elongation. The laser induced breakdown spectroscopy (LIBS) analysis is performed to identify the elements responsible for thermal ageing such as carbon, copper and sulfur on the surface of pressboard material. The plasma temperature calculated from sulfur peaks is higher for DBDS aged specimen compared to AgS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and a linear correlation is observed on the LIBS intensity with ageing duration. Further, the Principal Component Analysis (PCA) is used for its classification on the degradation of pressboard due to the diffusion of both copper and silver sulfide from the mineral oil. The two principal components (PC1 and PC2) provided a higher variance of 99.8% with a clear classification observed between the unaged and aged pressboard specimens due to the addition of both DBDS and Ag <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S in mineral oil.

Orientation independent heat transport characteristics of diamond/copper interface with ion beam bombardment

Owing to high thermal conductivity (k) and appropriate coefficient of thermal expansion (CTE), Diamond/copper (Dia/Cu) composites have attracted extensive attention as advanced thermal management materials, but also suffered with low thermal boundary conductance (G). This is because complex energy carrier behaviors at metal/nonmetal interfaces. Although conventional carbide forming interlayers may serve as acoustic matching bridge, crystallographic orientation is still critical to influence heat transport characteristics of Dia/Cu interface. In this work, both theoretical calculations and time-domain thermoreflectance (TDTR) results revealed two distinct G of (100) and (111) Dia/Cu interfaces. We then applied an easy-controlled ion-beam bombardment technique to reduce the orientation dependent G, and two different trends are observed with ion-bombardment time (t): (1) when t < 30 min, G increases with increasing t; (2) when t > 30 min, G decreases with increasing t. Our microstructural and surface potential analysis suggests sp3-to-sp2 hybridization and formation of nanoscale amorphous carbon (a–C) layer at the diamond surface. The coupling between electrons in Cu and a–C provides an additional heat transport pathway, however, the interfacial defect scattering becomes dominant when continuously increasing ion-bombardment time. The present findings may provide more insight to understand the orientation dependent heat transport mechanisms at metal/nonmetal interfaces.

Structural dynamics of SARS-CoV-2 variants: A health monitoring strategy for anticipating Covid-19 outbreaks

Objectivesthe Covid-19 pandemic has been marked by sudden outbreaks of SARS-CoV-2 variants harboring mutations in both the N-terminal (NTD) and receptor binding (RBD) domains of the spike protein. The goal of this study was to predict the transmissibility of SARS-CoV-2 variants from genomic sequence data. Methodswe used a target-based molecular modeling strategy combined with surface potential analysis of the NTD and RBD. Resultswe observed that both domains act synergistically to ensure optimal virus adhesion, which explains why most variants exhibit concomitant mutations in the RBD and in the NTD. Some mutation patterns affect the affinity of the spike protein for ACE-2. However, other patterns increase the electropositive surface of the spike, with determinant effects on the kinetics of virus adhesion to lipid raft gangliosides. Based on this new view of the structural dynamics of SARS-CoV-2 variants, we defined an index of transmissibility (T-index) calculated from kinetic and affinity parameters of coronavirus binding to host cells. The T-index is characteristic of each variant and predictive of its dissemination in animal and human populations. Conclusionsthe T-index can be used as a health monitoring strategy to anticipate future Covid-19 outbreaks due to the emergence of variants of concern.

Analytical Modeling and Performance Analysis of Surface Potential for Junctionless MOSFET

The advancement in semiconductor technology requires small devices with low power consumption. This paper presents an analytical modeling of surface potential for junctionless MOSFET. Parabolic approximation is utilized to find out the surface potential. The effect of device parameter variation on surface potential and electric field has been studied. The variation in gate work function has been investigated for surface potential. Moreover, the consequence of variations in device parameters like drain bias, gate length ratio, radius of silicon pillar and doping concentration are also inspected. It is found that present device shows an excellent behaviour for future VLSI chips. The analytical results are matched with the TCAD results which validates the model.