Molecular dynamics (MD) simulation has been used to study the martensitic transformation in iron at the atomic scale. The paper reviews the available interatomic interaction potentials for iron, ...which describe the properties of different phases present in that system. Cases on the fcc-to-bcc transformation in iron by MD simulations were included in the present paper. Factors affecting the fcc-to-bcc transformation in iron were analysed: (a) structural factors, such as grain/phase boundaries, grain sizes and stacking faults; (b) simulation conditions, such as the presence of free surfaces, external stress/strain and studied temperatures; (c) the interatomic interaction potential. The main emphasis of the present paper is on results giving insight on the mechanisms of the nucleation and growth of bcc phase in iron.
This review was submitted as part of the 2016 Materials Literature Review Prize of the Institute of Materials, Minerals and Mining run by the Editorial Board of MST. Sponsorship of the prize by TWI Ltd is gratefully acknowledged.
Chiral 1‐phenyl‐1,2‐ethanediol (PED) performs vital effect for the preparation of pharmaceuticals, agrochemicals and cosmetics. In the study, a newly isolated strain Kurthia gibsoniiSC0312 with the ...ability to selectively oxidize racemic PED to achieve (S)‐PED was evaluated in the aqueous reaction system. The strain showed excellent catalytic performances within the range of pH 5·5–8·5, temperature 25–45°C and the amount of cell 15 mg ml−1 to 30 mg ml−1. Besides, 2‐hydroxyacetophenone (HAP) as the oxidation product displayed a stronger inhibition to the catalytic activity of cell, only remaining <63% of catalytic activity after incubation at 40 mmol l−1 HAP for 6 h. For various metal ions, Cu2+ can obviously improve 1·7 times of the catalytic activity of cell at the concentration of 0·2 mmol l−1. Acetone can stimulate the catalytic capacity of cell to improve the optical purity of (S)‐PED at the PED concentration of 80 mmol l−1, up to appropriately 94% from 85·4%; compared to the resting cell, growing cell exerted no positive effect in the yield and optical purity. Finally, a highly effective kinetic resolution system of racemic PED by the new strain was obtained, with the (S)‐PED yield of 41% and optical purity of 94%.
Significance and Impact of the Study
Biocatalyst is a vital component in the process of biotransformation. There are a growing number of studies of biocatalyst reporting the preparation of enantiomer of 1‐phenyl‐1,2‐ethanediol. And the performance of this preparation reaction is also gradually improving. This study is the first to demonstrate that Kurthia gibsonii can efficiently and selectively oxidize racemic 1‐phenyl‐1,2‐ethanediol, and we assess the effect of various factors on the catalytic performance of the strain. The work adds to a growing body of evidence for using biocatalytic method in the synthesis of chiral 1‐phenyl‐1,2‐ethanediol and provides a probable approach to mine excellent properties of enzymes.
Significance and Impact of the Study: Biocatalyst is a vital component in the process of biotransformation. There are a growing number of studies of biocatalyst reporting the preparation of enantiomer of 1‐phenyl‐1,2‐ethanediol. And the performance of this preparation reaction is also gradually improving. This study is the first to demonstrate that Kurthia gibsonii can efficiently and selectively oxidize racemic 1‐phenyl‐1,2‐ethanediol, and we assess the effect of various factors on the catalytic performance of the strain. The work adds to a growing body of evidence for using biocatalytic method in the synthesis of chiral 1‐phenyl‐1,2‐ethanediol and provides a probable approach to mine excellent properties of enzymes.
The microstructure evolution of hydrogen-implanted 6H-SiC at different temperatures and fluences is investigated by using various experimental techniques. In H-implanted samples with relatively low ...fluence at RT, dense blister cavities are observed after annealing at 1100 °C, while no visible blister cavities appear after annealing at 1100 °C in the sample implanted at RT with high fluence. The absence of blister cavities is due to the loss of elastic energy during the crystalline-to-amorphous transition. With a further increase of implantation temperature to 450 and 900 °C, amorphization did not occur and H-containing microcracks grew laterally below the surface. Thus, blisters appeared on the surface of the samples implanted at 900 °C even without annealing. The results are compared to the microstructural evolution of He-implanted 6H-SiC which was explored in our previous work. The behavior of hydrogen and helium ions in 6H-SiC lattice was rather different. For He implantation, regardless of the fluence and implantation temperature, blisters did not form. The mechanism of migration and coalescence of nanoscale bubbles that are responsible for blistering were studied via density functional theory calculations, which well-supported the presented results. We found that both mechanisms (migration and coalescence) are energetically cheaper in the case of H compared to He.
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Structural evolution during simultaneous (SB) and sequential rubbery state biaxial stretching (SEQ) of polylactic acid (PLA) films from cast amorphous precursors was investigated. Simultaneous ...biaxial stretching always leads to films with in-plane isotropy and poor crystalline order. In the first stage of sequential biaxial stretching, oriented crystallization gradually develops while transverse isotropy is maintained. Application of transverse stretching to these films possessing semicrystalline structure gradually destroys the crystalline structure oriented in MD during this realignment while establishing a second population of oriented but poorly ordered crystallites in TD. This destruction is caused primarily by splaying action under transverse stretching as evidenced by the decrease of crystallite sizes in MD.
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Delayed pollination is widely used to overcome pre‐fertilization incompatibility, but its regulatory mechanisms are unclear. When Nicotiana tabacum was cross‐pollinated with pollen of N. alata, the ...incompatibility occurring in the basal 1/4 region of the style (pollinated at anthesis: 0‐day‐old pistil) was overcome by delayed pollination (of 6‐day‐old pistil), and the morphological changes and corresponding physiological basis are explored here.
The structure and ultrastructure of the pistil were observed under fluorescence microscopy and transmission electron microscopy. Differentially expressed proteins were screened with a monoclonal antibody chip for Nicotiana, and protein expression and distribution were analysed by immunofluorescence. Cellulase and pectinase activities were tested using enzyme‐linked immunosorbent assay kits.
The style of Nicotiana is solid in the basal region and pollen tubes grow in the extracellular spaces (ECM) of the transmitting tissue (TTS) cells. Seven of the 22 identified proteins were cell wall‐associated proteins and were expressed at higher levels during pistil senescence. Cellulase and pectinase activities increased. The TTS cells in the basal 1/4 region of the 0‐day‐old style were polygonal and tightly arranged, with narrow ECM, but these were oval or partially dissolved in the 6‐day‐old pistil, leading to wider ECM and richer secretions.
The increased expression of cell wall proteins and enhanced enzyme activity during pistil senescence might partially be responsible for the cells becoming oval and the ECM enlarged, providing the morphological basis for delayed pollination overcoming the pre‐fertilization incompatibility between N. tabacum and N. alata.
The transmitting tissue cells becoming oval and the extracellular spaces enlarged in senescent pistils and play a role in overcoming pollen‐pistil incompatibility via delayed pollination.
Cytosine methylation is responsive to various biotic- and abiotic-stresses, which may produce heritable epialleles. Nitrogen (N)-deficiency is an abiotic stress being repeatedly experienced by ...plants. To address possible epigenetic consequences of N-deficiency-stress, we investigated the stability of cytosine methylation in rice (
Oryza sativa L.) subsequent to a chronic (a whole-generation) N-deficiency at two levels, moderate (20
mg/L) and severe (10
mg/L), under hydroponic culture. MSAP analysis revealed that locus-specific methylation alteration occurred in leaf-tissue of the stressed plants (S
0) experiencing either level of N-deficiency, which was validated by gel-blotting. Analysis on three non-stressed self-fed progenies (S
1, S
2 and S
3) by gel-blotting indicated that
ca. 50% of the altered methylation patterns in somatic cells (leaf) of the stressed S
0 plants were recaptured in S
1, which were then stably inherited to S
2 and S
3. Bisulfite sequencing of two variant MSAP loci with homology to low-copy retrotransposons on one stressed plant (S
0) and its non-stressed progenies (S
1 and S
2) showed that whereas one locus exhibited limited and non-heritable CHH methylation alteration, the other locus manifested dramatic heritable hypermethylation at nearly all cytosine sites within the assayed region. Intriguingly, when two groups of S
2 plants descended from the same N-deficiency-stressed S
0 plant were re-subjected to the stress, the group inheriting the modified methylation patterns showed enhanced tolerance to the N-deficiency-stress compared with the group bearing the original patterns. Our results thus demonstrate heritability of an acquired adaptive trait in rice, which was accompanied by epigenetic inheritance of modified cytosine methylation patterns, implicating an epigenetic basis underlying the inheritance of an acquired trait in plants.
•In China, knowledge is shared through interactive systems.•Guanxi elements drive knowledge sharing (KS) behavior and enhance KS outcomes.•Individual preference for communication context moderates ...knowledge sharing behavior.
Based on the communicative ecology framework and theories related to guanxi and communication context in China, we investigate the moderating effects of individual preference for communication context (IPCC) on knowledge sharing via interactive systems (KSIS) behavior. Drawing on survey data from a hotel chain's employees, we explore how guanxi elements drive knowledge sharing (KS) behavior and enhance KS outcomes. Our data demonstrate that IPCC significantly moderates the effect that KSIS has on KS outcomes, but the IPCC has a direct and negative impact on KS outcomes. We explain these seemingly contradictory findings and their implications for research and practice.
Objectives
Talaromycosis is an invasive mycosis endemic to Southeast Asia. This study aimed to investigate the epidemiology, clinical features and prognostic factors of HIV‐associated talaromycosis ...in Guangdong, China.
Methods
We retrospectively evaluated HIV patients hospitalized with histopathology‐ or culture‐confirmed talaromycosis between 2011 and 2017. Factors associated with poor prognosis were identified using logistic regression.
Results
Overall, 1079 patients with HIV‐associated talaromycosis were evaluated. Both the number and prevalence of talaromycosis among HIV admissions increased from 125 and 15.7% in 2011 to 253 and 18.8% in 2017, respectively, reflecting the increase in HIV admissions. Annual admissions peaked during the rainy season between March and August. Common clinical manifestations included fever (85.6%), peripheral lymphadenopathy (72.3%), respiratory symptoms (60.8%), weight loss (49.8%), skin lesions (44.5%) and gastrointestinal symptoms (44.3%). Common laboratory abnormalities were hypoalbuminaemia (98.6%), anaemia (95.6%), elevated aspartate aminotransferase level (AST) (76.9%), elevated alkaline phosphatase level (55.8%) and thrombocytopenia (53.7%). The median CD4 count was 9 cells/μL. Talaromyces marneffei was isolated from blood and bone marrow cultures of 66.6% and 74.5% of patients, respectively. The rate increased to 86.6% when both cultures were performed concurrently. At discharge, 14% of patients showed worsening conditions or died. Leucocytosis, thrombocytopenia, elevated AST, total bilirubin, creatinine and azole monotherapy independently predicted poor prognosis.
Conclusions
The incidence of HIV‐associated talaromycosis has increased in Guangdong with the high HIV burden in China. Skin lesions were seen in less than half of patients. Induction therapy with azole alone is associated with higher mortality. Findings from this study should help to improve treatment of the disease.
The knowledge management (KM) literature largely focuses on the explicit and formal representation of knowledge in computer‐based KM systems. Informal KM practices are widespread, but less is known ...about them. This paper aims to redress this imbalance by exploring the use of interactive information technology (IT) applications for informal knowledge sharing (KS). We develop theoretical propositions to highlight the key facets of informal KS processes, and illustrate them through an interpretive case‐study analysis of KS in two public relations firms in China. We then discuss the implications of our findings for practice in both China and beyond. Finally, we recommend a research agenda to further investigate informal, relationship‐based knowledge sharing.
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