Heats of formation and stress-strain relationship of Fe-Cr solid solutions from a constructed Fe-Cr potential

A new Fe-Cr interatomic potential is constructed under the framework of the embedded-atom method and has better performances in predicting heats of formation and stress-strain relationship of Fe-Cr solid solutions than the Fe-Cr potentials already published in the literature. Based on the constructed Fe-Cr potential, molecular dynamics simulation reveals that the heats of formation of BCC Fe-Cr solid solutions at 1600 K are positive within the entire composition range, and the calculated values are in good agreement with corresponding experimental measurements in the literature. In addition, it is also found that the tensile strengths of BCC Fe-Cr solid solutions increase with the increase of the Cr composition, and that BCC Fe-Cr solid solutions are less ductile with smaller critical strains than both Fe and Cr. The simulated results are discussed and compared with the corresponding experimental and calculated evidence in the literature to validate the relevance of the newly constructed Fe-Cr potential.

Atomistic modelling of the immiscible Fe-Bi system from a constructed bond order potential

An analytical bond-order potential (BOP) of Fe-Bi has been constructed and has been validated to have a better performance than the Fe-Bi potentials already published in the literature. Molecular dynamics simulations based on this BOP has been then conducted to investigate the ground-state properties of Bi, structural stability of the Fe-Bi binary system, and the effect of Bi on mechanical properties of BCC Fe. It is found that the present BOP could accurately predict the ground-state A7 structure of Bi and its structural parameters, and that a uniform amorphous structure of Fe_100-xBi_xcould be formed when Bi is located in the composition range of 26 ⩽x< 70. In addition, simulations also reveal that the addition of a very small percentage of Bi would cause a considerable decrease of tensile strength and critical strain of BCC Fe upon uniaxial tensile loading. The obtained results are in nice agreement with similar experimental observations in the literature.

Whole-genome resequencing reveals genetic structure and introgression in Pudong White pigs

Pudong White (PDW) pigs, historically originating from Shanghai, are the only Chinese indigenous pigs characterised by their completely white coats, with the exception of Rongchang pigs. However, there is limited information concerning their overall genetic structure or relationship with other breeds, especially the East Chinese (ECN) and European pigs. To uncover the genetic structure, selection signatures, and potential exotic introgression in PDW pigs, we sampled 15 PDW pigs using whole-genome sequencing (~20×). We then conducted in-depth population genetic analyses in 320 pigs from 27 global pig groups, namely, European wild boars, Chinese wild boars, and outgroup. Neighbour-joining tree and principal component analysis confirmed that PDW pigs belonged to the ecotype of ECN pigs. Both f3, D-statistics, and structure analysis showed that PDW pigs shared apparent alleles with Large White (LW) pigs. Three statistics, rIBD, a haplotype heat map and copy number variation, further indicated that PDW pigs shared apparent alleles with LW pigs at the KIT Proto-Oncogene, Receptor Tyrosine Kinase (KIT) and PARG-MARCHF8 loci, suggesting that the lineage of European pigs in PDW originated from LW pigs. After further detecting the KIT mutations in different pig breeds, PDW was confirmed to have the same duplication region 1, duplication region 2, and the splicing mutation on intron 17 of KIT as LW pigs that determine the white coat colour phenotype in European white pigs. We hypothesised that LW pigs were imported to China ∼110-160 years ago according to the admixture time estimate and then crossed with ECN pigs, resulting in the introgression of the KIT alleles that produce the white coat colour phenotype in the PDW pig breed. To our knowledge, this study presents the first thorough description of the genetic structure of PDW pigs via whole-genome resequencing data; moreover, the results provide a basis for the national project for the conservation of this unique Chinese local population.

[Application and thinking of health standards related to medical care and health information in prevention and control of COVID-19]

Objective: To compare the technical elements of health standards for nosocomial infection control, health protection, health information, and health emergency and biosafety in the context of the prevention and control of COVID-19, and provide support for the further optimization of the epidemic prevention and control guidelines. Methods: Above mentioned health standards used in COVID-19 prevention and control were collected for a systematic comparison with "Guidelines for Prevention and Control of COVID-19 in Medical Institutions" (the 1(st) Edition) from the perspective of technical elements. Results: The application scope and technical elements of the current health standards basically meet the needs for the prevention and control of COVID-19 epidemic. Conclusions: The implementation of the current health standards can provide strong technical support for the prevention and control of COVID-19 epidemic. The experience obtained in the epidemic prevention and control can also contribute to the further revision and improvement of the health standards.

Raman fingerprint for semi-metal WTe2 evolving from bulk to monolayer

Tungsten ditelluride (WTe₂), a layered transition-metal dichalcogenide (TMD), has recently demonstrated an extremely large magnetoresistance effect, which is unique among TMDs. This fascinating feature seems to be correlated with its special electronic structure. Here, we report the observation of 6 Raman peaks corresponding to the , , , , and phonons, from the 33 Raman-active modes predicted for WTe₂. This provides direct evidence to distinguish the space group of WTe₂ from those of other TMDs. Moreover, the Raman evolution of WTe₂ from bulk to monolayer is clearly revealed. It is interesting to find that the mode, centered at ~109.8 cm⁻¹, is forbidden in a monolayer, which may be attributable to the transition of the point group from C_2v (bulk) to C_2h (monolayer). Our work characterizes all observed Raman peaks in the bulk and few-layer samples and provides a route to study the physical properties of two-dimensional WTe₂.

Strain-induced photoconductivity in thin films of Co doped amorphous carbon

Traditionally, strain effect was mainly considered in the materials with periodic lattice structure, and was thought to be very weak in amorphous semiconductors. Here, we investigate the effects of strain in films of cobalt-doped amorphous carbon (Co-C) grown on 0.7PbMg_1/3Nb_2/3O₃-0.3PbTiO₃ (PMN-PT) substrates. The electric transport properties of the Co-C films were effectively modulated by the piezoelectric substrates. Moreover, we observed, for the first time, strain-induced photoconductivity in such an amorphous semiconductor. Without strain, no photoconductivity was observed. When subjected to strain, the Co-C films exhibited significant photoconductivity under illumination by a 532-nm monochromatic light. A strain-modified photoconductivity theory was developed to elucidate the possible mechanism of this remarkable phenomenon. The good agreement between the theoretical and experimental results indicates that strain-induced photoconductivity may derive from modulation of the band structure via the strain effect.

Synthesis and characterization of fluorinated metal arsenates with a layer structure: (C4H12N2)(1.5)[M3F5(HAsO4)2(AsO4)] (M = Fe, Ga)

Two fluorinated metal arsenates, (C(4)H(12)N(2))(1.5)[M(3)F(5)(HAsO(4))(2)(AsO(4))] (M = Fe, Ga), have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, magnetic susceptibility, Mössbauer spectroscopy, and (71)Ga NMR spectroscopy. The two compounds are isostructural and crystallize in the monoclinic space group P2(1)/c (No. 14) with a = 8.394(1) A, b = 21.992(3) A, c = 10.847(1) A, beta = 96.188(2) degrees, and Z = 4 for the Fe compound, and a = 8.398(1) A, b = 21.730(3) A, c = 10.679(1) A, beta = 95.318(2) degrees, and Z = 4 for the Ga compound. The structure consists of infinite chains of corner-sharing MX(6) (X = O, F) octahedra and dimers of edge-sharing MO(3)F(3) octahedra, which are linked into two-dimensional sheets through arsenate tetrahedra with diprotonated piperazinium cations between the sheets. Magnetic susceptibility and Mössbauer spectroscopy confirm the presence of Fe(III). The (71)Ga MAS NMR spectrum clearly shows a line shape consisting of three components, corresponding to three crystallographically distinct Ga sites.

Central CGRP inhibits pancreatic enzyme secretion by modulation of vagal parasympathetic outflow

Calcitonin gene-related peptide (CGRP) is a potent inhibitor of pancreatic enzyme secretion in vivo. Recent studies have shown that CGRP exerts its inhibitory action at a central vagal site. The present study investigates the mechanism responsible for the central action of CGRP. Rats were fitted with lateral cerebroventricular cannulas, using stereotaxic instruments, 4 days before pancreatic secretion studies. In anesthetized rats, administration of 2-deoxy-D-glucose (2-DG) (75 mg/kg iv) or CCK-8 (40 pmol. kg-1. h-1) produced a 100 and 75% increase in protein secretion, respectively, which was completely blocked by atropine. Intracerebroventricular (ICV) administration of CGRP (0.03-0.6 nmol/h) resulted in a dose-related inhibition of pancreatic protein secretion evoked by 2-DG or CCK-8. CGRP administered by the ICV route was 10-40 times more potent than CGRP given by the intravenous route. In contrast, ICV administration of CGRP had no significant effect on pancreatic protein secretion evoked by electrical vagal stimulation or bethanechol, which directly activates the pancreatic muscarinic receptor. Chemical sympathectomy induced by pretreatment with guanethedine (20 mg/kg ip, 2 days) or alpha-adrenergic receptor blockade with phentolamine did not alter the inhibitory effects of CGRP. We recently demonstrated that CCK stimulated the enteropancreatic neural pathways to mediate pancreatic secretion in rats with a chronic vagotomy. ICV-administered CGRP did not affect CCK-stimulated pancreatic secretion in rats with a chronic vagotomy. In conclusion, CGRP in the central nervous system inhibits pancreatic enzyme secretion stimulated by 2-DG and CCK-8, which act through vagal pathways. The inhibitory action of CGRP is not mediated by the sympathetic nervous system but appears to depend on intact vagus nerves.

[Studies on the mutagenicity of amrinone and milrinone]

The mutagenicity of domestic new drugs amrinone and milrinone were studied by Ames test, micronucleus test of mouse bone marrow and chromosome aberration assay in CHO cells. The results were as follows: neither amrinone nor milrinone was mutagenic in the Ames test; in chromosome aberration assay, both gave positive results; in mouse micronucleus test, amrinone gave a positive result when mice were exposed to 0.8 LD50 dose, but milrinone gave a negative result. These results suggested that amrinone and milrinone did not induce gene mutation, but amrinone induced chromosome damage both in vitro and in vivo, while the chromosome-damaging activity of milrinone in vitro may be minimized by biodetoxication in vivo.