The microstructure, texture and mechanical properties evolution of the extruded fine-grained Mg-(1, 5) Y (wt%) alloy sheets were investigated during annealing. The as-extruded sheets exhibited a ...fully dynamic recrystallized (DRXed) microstructure consisting of uniform and fine equiaxed grains (5.7–8.7 µm) and a small amount of YH2 second phase particles. Both sheets exhibited significant thermal stability at 300 °C annealing and remarkable grain growth at temperatures higher than 400 °C. The measured grain growth activation energy (Q) of Mg-1Y at all temperatures tested was 91 ± 3 kJ/mol, suggesting that the growth was controlled by grain boundary diffusion. Meanwhile, for Mg-5Y alloy at lower temperatures (300–400 °C), the Q value (59 kJ/mol) indicated that the grain growth was controlled by grain boundary diffusion while the Q value (175 kJ/mol) at higher temperatures (400–450 °C) implied that lattice self-diffusion controlled the process. A representative rare-earth texture was present for both sheets in the as-extruded condition, and remarkable basal texture weakening was observed with the grain growth during each isothermal annealing process. The texture weakening can be ascribed to the preferential growth of non-basal oriented grains based on the EBSD analysis, which was likely related to the segregation of Y atoms at grain boundaries. The microhardness and grain size relationship can be described well by the Hall-Petch relation for all the annealed sheets, while the yield stress was not the case indicating that the macroscopic strength was more sensitive to the texture than the localized microhardness.
Background
The mixed dentition is an important transition period from primary teeth to permanent teeth. However, the caries prevalence of first permanent molar in mixed dentitions was about 30%, ...which almost represent the caries rate of permanent teeth in this period of time. Therefore, we assessed the oral bacterial profiles in young children (age 6–8) with mixed dentition with or without first molar caries for providing the research basis of caries etiology.
Methods
We collected samples of supragingival plaque and saliva from the children living in Guizhou, a rural isolated province in China. Then, we performed DNA extraction and purification followed by 454 pyrosequencing of the V1–V3 hypervariable regions of the 16S rRNA and compared our results with those of previous research.
Results
(i) We analyzed 48,320 unique sequences that represented 18 phyla, 29 classes, 44 orders, 74 families, 129 genera, 15,003 species‐level OUT in plaque and saliva samples; (ii) longitudinally, there was the “healthy core microbiome” between healthy deciduous dentition and early mixed dentition, for example, Neisseria, Porphyromonas, Selenomonas etc.; (iii) horizontally, there also existed the “healthy core microbiome” in early mixed dentition, for example, Neisseria, Streptococcus, Prevotella etc.; (iv) the dominant bacteria detected by Lefse in caries group including Actinomycetaceae, Streptobacillus (p < 0.05) and those in caries‐free group including Gammaproteobacteria, Pasteurellaceae, Aggregatibacter, Chloroflexi, (p < 0.05).
Conclusions
The oral cavity is a highly heterogeneous ecosystem with the “healthy core microbiome” in children, although microbial composition shifts along with aging. In addition, the abundance and diversity of microbiota vary between caries and caries‐free groups verify the ecological plaque hypothesis.
Abstract The aims of this study were to investigate the epidemiological and clinical characteristics of epithelial salivary gland tumours in a northern Chinese population and to evaluate the current ...TNM classification system. A demographic and descriptive analysis of 7190 epithelial salivary gland tumours was performed. There were 4654 benign tumours and 2536 malignant tumours. The percentage of tumours located in the parotid, submandibular, sublingual, and minor salivary glands was 62.66%, 9.92%, 2.57%, and 24.85%, respectively; 22.26%, 35.76%, 92.97%, and 61.89% of the tumours, respectively, were malignant. Over 90% in the tongue and maxillary sinus were malignant. Warthin tumour, salivary duct carcinoma, and squamous cell carcinoma were predominant in males, while basal cell adenoma, myoepithelioma, and pleomorphic adenoma were predominant in females. Further, 2.55% of the tumours were in children and adolescents: 44.81% of the tumours were malignant, as opposed to 35.02% in adults. According to the 7th TNM classification, the percentages of T3 and stage III tumours were approximately 10%. Salivary gland tumours show distribution patterns according to histological type, location, and patient age and sex. The limitations of the current TNM classification of salivary gland carcinoma should be considered and revisions made.
The plastic anisotropy in terms of tensile mechanical property, Lankford coefficient (r), and microstructure evolution of as-extruded Mg-1Y (wt%) and Mg-5Y (wt%) sheets along the extrusion direction ...(ED), transverse direction (TD), and diagonal direction (DD) were investigated in detail at temperatures between 25℃ (RT) and 300℃. The sheets exhibited anisotropic deformation behavior at lower temperatures, and nearly isotropic for Mg-5Y at 300℃ in these three directions. For both sheets, the ultimate tensile strength anisotropy (UA) and elongation anisotropy (EA) was not sensitive to the temperature, while the yield strength anisotropy (YA) decreased significantly from 49.1% (Mg-1Y) and 40.2% (Mg-5Y) at RT to 7.2% and 2.7% at 300℃, respectively. The r values of Mg-1Y in all directions first increased from 0.66-1.4 (RT) to 0.81–1.98 (200℃) then decreased to 0.67–1.56 (300℃), while those of Mg-5Y decreased from 1.04-2.05 (RT) to 1.18–1.35 (300℃) with increasing temperature. Few twins were observed in Mg-5Y after tension at RT while large amounts of twins occurred in Mg-1Y. The huge reduction of twins and the weakened basal texture are believed to increase the r value from 0.66 (Mg-1Y) to 1.04 (Mg-5Y) at RT. At 300℃, dynamic recrystallized (DRX) grains appeared in Mg-1Y while only a few DRX grains showed up in the vicinity of grain boundaries in Mg-5Y, which may be closely related to grain boundary segregation of the yttrium atoms.
For the first time, we report a complete control of crystal structure in InAs1–x Sb x NWs by tuning the antimony (Sb) composition. This claim is substantiated by high-resolution transmission electron ...microscopy combined with photoluminescence spectroscopy. The pure InAs nanowires generally show a mixture of wurtzite (WZ) and zinc-blende (ZB) phases, where addition of a small amount of Sb (∼2–4%) led to quasi-pure WZ InAsSb NWs, while further increase of Sb (∼10%) resulted in quasi-pure ZB InAsSb NWs. This phase transition is further evidenced by photoluminescence (PL) studies, where a dominant emission associated with the coexistence of WZ and ZB phases is present in the pure InAs NWs but absent in the PL spectrum of InAs0.96Sb0.04 NWs that instead shows a band-to-band emission. We also demonstrate that the Sb addition significantly reduces the stacking fault density in the NWs. This study provides new insights on the role of Sb addition for effective control of nanowire crystal structure.
CREB is an ubiquitous transcription factor regulating diverse cellular responses. Its phosphorylation at S133 is an essential event for its activation in both nervous and visual systems. The ...activated CREB is implicated in the regulation of development, protection, learning, memory and plasticity in the nerve system. Moreover, sumoylation, an important post-translational modification of protein, plays a key role in sustaining CREB activation in the rat hippocampus in order to enhance the long-term memory and other aspects. In the visual system, although the CREB activation by phosphorylation at S133 is similar to that as observed in the nervous system, the role of CREB sumoylation remains to be explored. This review will discuss the aspects of CREB functions and their regulation by phosphorylation and sumoylation in both systems.
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