Principles Study Research Articles

A first principles study of convection cells to shear flow instability in 2D Yukawa liquids driven by Reynolds stress

The stability of kinetic-level convection cells (wherein the magnitude of macroscopic and microscopic velocities are of same order) is studied in a two-dimensional Yukawa liquid under the effect of microscopic velocity perturbations. Our numerical experiments demonstrate that for a given system aspect ratio viz., the ratio of system length to its height and number of convective rolls initiated , the fate of the convective cells is decided by . For , Reynolds stress is found to be self-consistently generated and sustained, which results in tilting of convection cells, eventually leading to shear flow generation, whereas for , parallel shear flow is found to be untenable. An unambiguous quantitative connection between Reynolds stress and the onset of shear flow using particle-level data is established without free parameters. The growth rate of the instability, the role of frictional forces, generalization of our findings and the possibility of realizing the same in experiments are also discussed.

First principle study of electronic, magnetic and optical properties of X-doped (X=Fe, Co and Cu) boron nitride nanotubes and its applications

First principle study of electronic, magnetic and optical properties of X-doped (X=Fe, Co and Cu) boron nitride nanotubes and its applications

First Principles Studies on Structural, Elastic, Electronic, Optical Properties of MgSrPb and MgSrSi Half Heusler Alloys

First Principles Studies on Structural, Elastic, Electronic, Optical Properties of MgSrPb and MgSrSi Half Heusler Alloys

First principles study on monolayer GeTe as an anode material for multivalent ion batteries.

Finding suitable anode materials for multivalent ion batteries (MuIBs) is the key to improving theoretical capacity, reducing development costs and enhancing the safety of energy storage batteries. In recent years, monolayer GeTe has been reported as an anode material in monovalent ion batteries, but it has not received much attention in MuIBs. This article uses first principles methods based on density functional theory (DFT) to explore the application prospects of monolayer GeTe with a unique serrated wrinkled layer structure as an anode material for multivalent metal ion (Al3+/Mg2+/Ca2+) batteries. The research results show that Al3+, Mg2+ and Ca2+ have low diffusion barriers (0.47, 0.35 and 0.61 eV) on monolayer GeTe, indicating its excellent diffusion ability and fast charge discharge rate during the charging and discharging process. Reasonable open circuit voltages (0.62, 0.85 and 0.64 V) and theoretical specific capacities higher than those of commercial graphite anode materials (624.6, 446.1 and 446.1 mA h g-1) indicate that monolayer GeTe has the ability to store Al3+/Mg2+/Ca2+. Finally, molecular dynamics simulations (MD) are used to calculate the adsorption energy and density field of ions during their movement on the surface of monolayer GeTe, demonstrating the stable adsorption ability of monolayer GeTe and the strong interaction between the two. This article reveals that monolayer GeTe can be used as a promising candidate anode material for MuIBs.

Janus monolayer Bi8M2O16XY (M = Nb, Ta; X/Y = Cl, Br, I; X ≠ Y) for photocatalytic overall water splitting with high carrier mobility: A first principles study

Janus monolayer Bi8M2O16XY (M = Nb, Ta; X/Y = Cl, Br, I; X ≠ Y) for photocatalytic overall water splitting with high carrier mobility: A first principles study

Efficacy of Acupuncture in Postoperative Pain-Relieving: A Systematic Review and Meta-Analysis.

This study aimed to assess the efficacy of acupuncture in relieving postoperative pain. Systematic review and meta-analysis. The search strategy was designed according to the PICOS principle (population, intervention, comparison, outcome, and study). PubMed, Web of Science, Cochrane Library, and Embase were searched from the inception of databases to August 25th, 2022 to collect studies on acupuncture in the management of postoperative pain. Two researchers independently screened the searched studies using the EndNote X9 software. Relevant data were extracted, and the risk of bias in included studies was assessed. RevMan 5.4 software was used for data analysis, and the Grading of Recommendations, Assessment, Development, and Evaluation was used to assess the quality of evidence. A total of 25 studies were included. This meta-analysis showed statistically significant differences in the pain scores (SMD=-0.38, 95 %CI [-0.69, -0.07], p = .02) and the dosage of analgesics (SMD = -0.53, 95% CI [-0.99, -0.06], I2 = 90 %, p < .00001] between the acupuncture group and the control group. Acupuncture is effective for alleviating postoperative pain and reducing the dosage of analgesics. More well-designed, and large-scale prospective studies are needed to further validate the efficacy of acupuncture in relieving postoperative pain. Acupuncture is an acceptable choice for relieving postoperative pain since it is convenient, effective, and acceptable. Nurses can provide tailored guidance for patients to enhance their recovery and satisfaction.

First principles study of oxidation resistance of amorphous Si-(B)-C-N materials, and experimental verification

First principles study of oxidation resistance of amorphous Si-(B)-C-N materials, and experimental verification

First Principles Study of Electronic, Vibrational, Elastic, and Thermodynamic Properties of Sc‐X (X = P, S, Se) Compounds

First Principles Study of Electronic, Vibrational, Elastic, and Thermodynamic Properties of Sc‐X (X = P, S, Se) Compounds

First Principles Study of Undoped and Halogen Doped ZnO Monolayer

This study reports the structural, electronic, and magnetic properties of undoped and halogen (F, Cl, and Br) doped ZnO monolayers (3 × 3 × 1) by replacing one Zn-atom. Using spin polarized Density Functional Theory (DFT) in VASP code and a projected augmented wave basis set, we employed GGA-PBE and PBE+U exchange correlation functionals. The band gap of pristine ZnO was measured to be 1.67 eV and 2.61 eV for PBE and PBE+U, respectively, whereas band gap decreased significantly upon addition of halogen atom. Likewise, doped ZnO shows semimetallic behavior, whereas undoped ZnO exhibits semiconducting behaviour. Further, the magnetic moments of about 1 µB for Cl and Br-doped ZnO, and 1.02 µB &amp; 2.98 µB for F-ZnO utilizing PBE and PBE+U functionals, respectively were observed. These findings suggest that halogen-doped ZnO might carry huge potential for next-generation spintronic nanodevices.

Neural sensitivity in adults with autism spectrum disorder to an oxytocin trial: A proof of principle study

Neural sensitivity in adults with autism spectrum disorder to an oxytocin trial: A proof of principle study

Impact of Neglect on the Relationship Between Upper Limb Motor Function and Upper Limb Performance in the (Hyper)acute Poststroke Phase.

Visuospatial neglect (VSN) is a negative, strong, and independent predictor of poor outcome after stroke, and is associated with poorer upper limb (UL) motor recovery in terms of function or capacity (ie, in standardized, lab-based testing). Although the main aim of stroke rehabilitation is to re-establish optimal functioning in daily life, the impact of VSN on UL performance (ie, in unstructured, everyday environments) is largely unknown. In this proof of principle study, the impact of VSN on the strength of the association between UL motor function (Jamar Hand Dynamometer) and UL performance (Upper Limb Lucerne ICF-based Multidisciplinary Observation Scale) was investigated in 65 (hyper)acute first-ever stroke patients. In a moderator analysis, the interaction term was negative and significant, showing that VSN suppresses the use of UL motor function in daily life (ie, performance). This finding suggests that, when considering UL performance in the (hyper)acute phase after stroke, interventions aimed to reduce deficits in both UL motor function and visuospatial function should already be started in the acute stroke unit setting.

On the structural, electronic, and thermoelectric properties of EuMg2X2 (X = P, As, Sb, Bi) zintl phase; A first principles investigations

Abstract The key solution to the now-a-days energy crisis is the conversion of waste heat into useful electrical energy. In this work, the structural, electronic, and thermoelectric characteristics of EuMg2X2 (X = P, As, Sb, Bi) zintl materials have been investigated comprehensively through first principles studies. Structural analysis shows that our measured values fit well with the previous available experimental data. Three potential functionals, PBE GGA, TB-mBJ, and hybrid functional (YS-PBE0), have been used to study the electronic behavior of the titled compounds. EuMg2X2 (X = P, As, Sb, Bi) reveal band gaps of 0.83 eV, 0.72 eV, 0.34 eV, and 0.41 eV, respectively, through hybrid functional (YS-PBE0). Density of states (DOS) and partial density of states (PDOS) studies reveals the role offered by different atomic orbitals in the formation of electronic band structures of the samples. Similarly, thermoelectric tone of the said compounds is calculated by virtue of BoltzTraP2 computational code. The ultralow thermal conductivity and optimum level of carriers’ concentration encompass these materials to be good thermoelectrics with better and reasonable thermoelectric efficiency (ZTe).

Atomic adsorption mechanism and initial growth of 2D GaN on graphene, h-BN and MoS2: A first principles study

Van der Waals epitaxial growth strategy on two-dimensional substrates presents a promising way for synthesizing hexagonal gallium nitride (h-GaN). This study investigates the most stable adsorption configurations of gallium (Ga) and nitrogen (N) atoms on graphene, h-BN, and MoS2 surfaces and further study the initial formation of GaN islands using the first-principles method. The interaction modes between Ga and N atoms with the substrates are analyzed using the Electron Localization Function (ELF), revealing the microscopic adsorption mechanism. Furthermore, diffusion behaviors of Ga and N atoms on the three substrates are evaluated via Climbing Image Nudged Elastic Band (CI-NEB) calculations, which shows that Ga diffuses via a sliding mechanism, while N diffusion involves bond-breaking and re-bonding events. N atom diffusion in the z-direction on these substrates are identified for the first time and the corresponding energy barriers are determined. Additionally, the growth morphology of 2D GaN on MoS2 is predicted by analyzing the competition between adatom-substrate and adatom-adatom interactions, and the possible morphology of initial 2D GaN islands is investigated. Our findings reveal that MoS2 is a favorable substrate for the growth of 2D h-GaN, providing theoretical insights to guide future experimental efforts.

Diamond surface nano-structures in an oxidizing atmosphere: A first principles study

Diamond surface nano-structures in an oxidizing atmosphere: A first principles study

First principles study on physical properties of novel 211 MAX phase Sc2AC (A=Ga, In)

First principles study on physical properties of novel 211 MAX phase Sc2AC (A=Ga, In)

Synthesis, GC-MS, Spectroscopic, chemical absorption nature in various solvent, chemical reactivity, topology analyses and Molecular docking evaluation of 2(4H)-Benzofuranone, 5,6,7,7a-tetrahydro-4,4,7a-trimethyl-, (R): A first principle study

Synthesis, GC-MS, Spectroscopic, chemical absorption nature in various solvent, chemical reactivity, topology analyses and Molecular docking evaluation of 2(4H)-Benzofuranone, 5,6,7,7a-tetrahydro-4,4,7a-trimethyl-, (R): A first principle study

Investigations for hydrogen storage applications of XPtH3 (X = Cs, Fr) hydrides: A first principles study

Investigations for hydrogen storage applications of XPtH3 (X = Cs, Fr) hydrides: A first principles study

A first principle study of Nitrogen/Carbon replacement in a set of β-aminoacrolein/β-thioaminoacrolein derivatives

A first principle study of Nitrogen/Carbon replacement in a set of β-aminoacrolein/β-thioaminoacrolein derivatives

Manure odor profiling for flock-level monitoring on commercial layer pullet farms: Vaccination events as a model stressor.

Continuous, non-invasive, and objective methods to detect flock-level responses to stressors, including intestinal health deviations, are currently lacking in poultry. This proof of principle study investigated the potential of manure odor profiling in monitoring stress responses in Lohmann Brown Classic, Lohmann LSL Classic and Lohmann LSL Lite layer pullets. Stressors were represented by a Salmonella vaccination given to the pullets at wk 3 of age (Dataset 1 and Dataset 2) and wk 16 of age (Dataset 4) and a viral/bacterial vaccine cocktail given at wk 12 of age (Dataset 3). Fresh manure was sampled daily, from 2 days before vaccination to 4 days after vaccination, with 4 pooled manure samples per day per dataset. Manure volatiles were concentrated into stainless steel sorbent tubes and analyzed by a thermal desorption system coupled with gas chromatography-mass spectrometry. Dataset, breed and sample location did not affect the manure volatile profiles before vaccination. Age did affect the manure volatile profiles, with beta-camphor, (Z)-6-Tridecene and serinol peak intensities elevated in young pullets and carbonyl sulfide and trimethylamine elevated in older pullets. Salmonella vaccination at wk 3 of age led to the most consistent changes in volatile peak intensities. (Z)-6-Tridecene was decreased in Dataset 1, Dataset 3, and Dataset 4 after either the Salmonella vaccination or the viral/bacterial vaccine cocktail, despite differences in hen age and house. The injected viral/bacterial vaccine cocktail created a more clear time-dependent shift in the manure volatile profile than the orally-provided Salmonella vaccination in older pullets at resp. wk 12 and 16 of age. No overlapping trends in upregulated or downregulated volatiles were found between all datasets. To conclude, volatile profiles of rearing hen manure are affected by vaccinations as a proxy for stressors, and the magnitude and direction of the response depends on the age of the pullets at vaccination, the vaccination method, and the pathogenic properties of the vaccine. The reduced peak intensities of volatiles after vaccination in 3 out of 4 flocks suggests the potential of manure odor profiling in monitoring stress responses in layer pullets.

First principles methodology for studying magnetotransport in narrow gap semiconductors with ZrTe5 example

The origin of resistivity peak and sign reversal of Hall resistivity in ZrTe5 has long been debated. Despite various theories proposed to explain these unique transport properties, there’s a lack of comprehensive first principles studies. In this work, we employ first principles calculations and Boltzmann transport theory to explore transport properties of narrow-gap semiconductors across varying temperatures and doping levels within the relaxation time approximation. We simulate the temperature-sensitive chemical potential and relaxation time in semiconductors through proper approximations, then extensively analyze ZrTe5’s transport behaviors with and without an applied magnetic field. Our results reproduce crucial experimental observations such as the zero-field resistivity anomaly, nonlinear Hall resistivity with sign reversal, and non-saturating magnetoresistance at high temperatures, without introducing topological phases and/or correlation interactions. Our approach provides a systematic understanding based on multi-carrier contributions and Fermi surface geometry, and could be extended to other narrow-gap semiconductors to explore novel transport properties.