RNA interference reveals chloride channel 7 gene helps short-term hypersalinity stress resistance in Hong Kong oyster Crassostrea hongkongensis

The chloride channel 7 gene(CLC 7)of the Hong Kong oyster Crassostrea hongkongensis was cloned and named ChCLC 7.The cDNA was 2572 bp in length,with a 5′non-coding region containing 25 bp,a 3′non-coding region containing 327 bp,and an open reading frame of 2298 bp.ChCLC 7 has 96.8%and 92.1%homology with CLC 7 of Crassostrea gigas and Crassostrea virginica,respectively,and it was clustered with CLC 7 of C.gigas and C.virginica.QRT-PCR showed that ChCLC 7 was expressed in all eight tissues,with the highest in adductor muscle and second in gill.The ChCLC 7 expression pattern in gill was altered significantly under high salinity stress with an overall upward and then downward trend.After RNA interference,the expression of ChCLC 7 and survival rate of oyster under high salinity stress was reduced significantly,and so did the concentration of hemolymph chloride ion in 48-96 h after RNA interference.We believed that ChCLC 7 could play an important role in osmoregulation of C.hongkongensis by regulating Cl^(-)transport.This study provided data for the analysis of molecular mechanism against oyster salinity stress.

Roasting oxidation behaviors of ReS_2 and MoS_2 in powdery rhenium-bearing, low-grade molybdenum concentrate

The oxidation roasting process of molybdenum concentrate has significant advantages in industrial applications.However,utilization of low-grade mineral has many problems because it is more complex than the standard concentrate.In this study,the oxidation behaviors of powdery rhenium-bearing low-grade molybdenum concentrate were investigated through thermodynamic calculation,roasting experiments,thermogravimetric analysis,and phase analysis.The results obtained show that oxidation of MoS2 begins at 450℃,and MoO3 reacts with metal-oxide forming molybdate at 600℃.Finally,MoO3 can be dissolved in ammonia with a maximum content of approximately 80%.The volatile speed of Re was considerably slower than the oxidation speed of MoS2 because the nonvolatile products ReO2 and ReO3 were generated in reactions among MoS2,SO2,and Re2O7.The final volatilization rate of Re was almost 70%.This study determined the problems related to the roasting of low-grade molybdenum concentrate,which lays the scientific foundations for subsequent enhancement of molybdenum and rhenium extraction.

Layer thickness dependent plastic deformation mechanism in Ti/TiCu dual-phase nano-laminates

Crystalline/amorphous nanolaminate is an effective strategy to improve the mechanical properties of metallic materials,but the underlying deformation mechanism is still under the way of exploring.Here,the mechanical properties and plastic deformation mechanism of Ti/TiCu dual-phase nanolaminates(DPNLs)with different layer thicknesses are investigated using molecular dynamics simulations.The results indicate that the influence of the layer thickness on the plastic deformation mechanism in crystalline layer is negligible,while it affects the plastic deformation mechanism of amorphous layers distinctly.The crystallization of amorphous TiCu is exhibited in amorphous parts of the Ti/TiCu DPNLs,which is inversely proportional to the layer thickness.It is observed that the crystallization of the amorphous TiCu is a process driven by stress and heat.Young's moduli for the Ti/TiCu DPNLs are higher than those of composite material due to the amorphous/crystalline interfaces.Furthermore,the main plastic deformation mechanism in crystalline part:grain reorientation,transformation from hexagonal-close-packed-Ti to face-centered cubic-Ti and body-centered cubic-Ti,has also been displayed in the present work.The results may provide a guideline for design of high-performance Ti and its alloy.

Plastic deformation mechanism transition of Ti/Ni nanolaminate with pre-existing crack:Molecular dynamics study

Tensile behaviors of Ti/Ni nanolaminate with model-I crack are investigated by molecular dynamics simulations.The Ti/Ni nanolaminates with center crack either in Ti layer or in Ni layer under different loading directions are utilized to systematically study the mechanical performance of the cracked material.The results indicate that pre-existing crack dramatically changes the plastic deformation mechanism of the Ti/Ni nanolaminate.Unlike the initial plastic deformation originating from the interface or weak Ti layer of the crack-free samples,the plastic behavior of cracked Ti/Ni nanolaminate first occurs at the crack tip due to the local stress concentration.Subsequent plastic deformation is dominated by the interaction between the crack and interface.The Ti/Ni interface not only impedes the movement of the initial plastic deformation carriers(dislocation,slip band,and deformation twinning)from the crack tip,but also promotes the movement of interfacial dislocations in the tension process.Microstructure evolution analysis further confirms that the plastic deformation mechanism transition is ascribed to the orientation-dependent tensile behavior at the crack tip,which is intrinsically attributed to the anisotropy of the certain crystal structure and loading direction of the cracked Ti/Ni nanolaminate.In addition,by analyzing the effects of different plastic deformation carriers on crack propagation in specific crystal,it can be discovered that the interfacial dislocations moving towards the crack tip can further promote the crack growth.

Anisotropic plasticity of nanocrystalline Ti:A molecular dynamics simulation

Using molecular dynamics simulations,the plastic deformation behavior of nanocrytalline Ti has been investigated under tension and compression normal to the{0001},{1010},and{1210}planes.The results indicate that the plastic deformation strongly depends on crystal orientation and loading directions.Under tension normal to basal plane,the deformation mechanism is mainly the grain reorientation and the subsequent deformation twinning.Under compression,the transformation of hexagonal-close packed(HCP)-Ti to face-centered cubic(FCC)-Ti dominates the deformation.When loading is normal to the prismatic planes(both{1010}and{1210}),the deformation mechanism is primarily the phase transformation among HCP,body-centered cubic(BCC),and FCC structures,regardless of loading mode.The orientation relations(OR)of{0001}HCP||{111}FCC and<1210>HCP||<110>FCC,and{1010}HCP||{110}FCC and<0001>HCP||<010>FCC between the HCP and FCC phases have been observed in the present work.For the transformation of HCP→BCC→HCP,the OR is{0001}α1||{110}β||{1010}α2(HCP phase before the critical strain is defined as α1-Ti,BCC phase is defined as β-Ti,and the HCP phase after the critical strain is defined as α2-Ti).Energy evolution during the various loading processes further shows the plastic anisotropy of nanocrystalline Ti is determined by the stacking order of the atoms.The results in the present work will promote the in-depth study of the plastic deformation mechanism of HCP materials.

Molecular dynamics study of coupled layer thickness and strain rate effect on tensile behaviors of Ti/Ni multilayered nanowires

Novel properties and applications of multilayered nanowires(MNWs)urge researchers to understand their mechanical behaviors comprehensively.Using the molecular dynamic simulation,tensile behaviors of Ti/Ni MNWs are investigated under a series of layer thickness values(1.31,2.34,and 7.17 nm)and strain rates(1.0×10^(8)s^(-1)≤ε≤5.0×10^(10)s^(-1)).The results demonstrate that deformation mechanisms of isopachous Ti/Ni MNWs are determined by the layer thickness and strain rate.Four distinct strain rate regions in the tensile process can be discovered,which are small,intermediate,critical,and large strain rate regions.As the strain rate increases,the initial plastic behaviors transform from interface shear(the shortest sample)and grain reorientation(the longest sample)in small strain rate region to amorphization of crystalline structures(all samples)in large strain rate region.Microstructure evolutions reveal that the disparate tensile behaviors are ascribed to the atomic fractions of different structures in small strain rate region,and only related to collapse of crystalline atoms in high strain rate region.A layer thickness-strain rate-dependent mechanism diagram is given to illustrate the couple effect on the plastic deformation mechanisms of the isopachous nanowires.The results also indicate that the modulation ratio significantly affects the tensile properties of unequal Ti/Ni MNWs,but barely affect the plastic deformation mechanisms of the materials.The observations from this work will promote theoretical researches and practical applications of Ti/Ni MNWs.

Balancing strength and plasticity of dual-phase amorphous/crystalline nanostructured Mg alloys

The dual-phase amorphous/crystalline nanostructured model proves to be an effective method to improve the plasticity of Mg alloys.The purpose of this paper is to explore an approach to improving the ductility and strength of Mg alloys at the same time.Here,the effect of amorphous phase strength,crystalline phase strength,and amorphous boundary(AB)spacing on the mechanical properties of dual-phase Mg alloys(DPMAs)under tensile loading are investigated by the molecular dynamics simulation method.The results confirm that the strength of DPMA can be significantly improved while its excellent plasticity is maintained by adjusting the strength of the amorphous phase or crystalline phase and optimizing the AB spacing.For the DPMA,when the amorphous phase(or crystalline phase)is strengthened to enhance its strength,the AB spacing should be increased(or reduced)to obtain superior plasticity at the same time.The results also indicate that the DPMA containing high strength amorphous phase exhibits three different deformation modes during plastic deformation with the increase of AB spacing.The research results will present a theoretical basis and early guidance for designing and developing the high-performance dual-phase hexagonal close-packed nanostructured metals.

Molecular dynamics study on mechanical behaviors of Ti/Ni nanolaminate with a pre-existing void

Metallic nanolaminated materials possess excellent mechanical properties due to their unique modulation structures and interfacial properties.However,how microdefects affect their mechanical properties is still uncertain.To evaluate the influences of void location(in the crystalline layer and the Ti/Ni interface),void diameter(d)and thickness of the intermediate layer(h)on overall tensile behaviors,various types of defective Ti/Ni nanolaminates with pre-existing void are established by the molecular dynamics method in this work.The results indicate that the strength and plastic deformation mechanisms are strongly dependent on those determinants.Yield stresses of Ti/Ni nanolaminates decrease distinctly with increasing void diameter,while peak stresses with a void in the crystalline layer decrease with increasing d/h.Different void locations lead eventually to disparate initial plastic deformation carriers around the void,and various evolutions in the microstructure of the defective Ti/Ni nanolaminates.The Ti/Ni interface plays a significant role in the tensile process.The semi-coherent interface impedes new grains and lattice dislocations from passing across the interface,while the incoherent interface facilitates dislocations generating and sliding along the interface,and absorbs the dislocations moving to the interface.The results also indicate that the strain rate significantly affects the evolution of the microstructure and the tensile properties of defective Ti/Ni nanolaminates.

单细胞RNA测序技术探究CCN2基因在特纳综合征胎儿颈部淋巴水囊瘤中的关键作用

目的应用单细胞RNA测序技术(scRNA-seq)探讨细胞通讯网络因子2(CCN2,也称为CTGF)在特纳综合征(TS)胎儿颈部淋巴水囊瘤(CH)的潜在发生机制。方法收集2020年1月至2020年12月于广州市妇女儿童医疗中心产前诊断中心就诊,孕11~13^(+6)周经腹部超声检查诊断为CH而终止妊娠及相同孕周因社会因素终止妊娠病例,产前未行遗传学检测者,需同时取引产胎儿胎盘绒毛组织或骨骼肌,按照标准的操作流程进行遗传学检测。全部病例应用遗传学检测确定染色体异常类型后,CH病例中选择遗传学结果为45,X0的胎儿作为实验组,无CH病例中选择遗传学结果为46,XN的胎儿作为对照组。本研究共纳入6例样本,实验组3例,对照组3例。所有入组病例在终止妊娠后立即取颈后皮肤组织,一部分样本应用HE染色进行病理分析,一部分应用scRNA-seq分析颈后皮肤组织细胞类型并建立差异基因表达谱,并进一步应用RT-qPCR检测细胞中基因表达水平及Western blot检测相关蛋白表达情况以明确单细胞测序结果的可靠性。实验组与对照组采用独立样本t检验进行统计学分析。结果病理结果提示实验组表现为淋巴管增生和扩张,淋巴结增多坏死,血管减少,间质纤维丝束增多、变长,并出现大量细胞浸润组织间隙。应用scRNA-seq分析CH病例,共捕获细胞54488个,26个聚类,其中成纤维细胞占23.1%。同时发现基质细胞蛋白CCN2高表达。进一步定位分析显示实验组中CCN2主要高表达在成纤维细胞、内皮细胞、组织干细胞和间充质干细胞。同时Western blot验证CCN2蛋白在实验组中高表达(2.47±0.49比1.00±0.08,P<0.05)。结论病理结果表明淋巴管增生扩张和淋巴结增多坏死等淋巴管发育异常是TS胎儿CH的病理生理学基础。scRNA-seq结果表明基质细胞蛋白CCN2异常高表达可能导致TS胎儿CH。

Effect of Biochar as Reductant on Magnetizing-roasting Behavior of Pyrite Cinder

The effect of biochar substituted for anthracite as reductant on magnetizing-roasting pyrite cinder was in- vestigated. The key of magnetizing-roasting is the gasification reaction between reductants and CO2. Since biochar could react with CO2 more rapidly at lower temperature, the reactivity of biochar is better than that of anthracite. The gasification of biochar could produce reducing condition of φco/（φco--φco2 ） about 10 %- 20 % between 700-- 800 ℃, which is in accord with the atmosphere and temperature of Fe2 O3 reduction. So it is beneficial to the reduc- tion of iron mineral of pyrite cinder. Compared with anthracite, bioehar could decrease the roasting temperature from 825 to 750 ℃ and roasting time from 20 to 15 min, which shows that a better effect of magnetization could be ob- tained in the condition of lower temperature and shorter time. Using biochar as reductant, iron concentrate extracted from pyrite cinder as about 64% iron grade could be produced, and the recovery is over 90% under the condition of above 90% grinding particle less than 0. 045 mm and magnetic intensity of 0. 124--0. 194 T.

孤儿核受体HNF4α在肾透明细胞癌中的表达及意义

目的基于数据挖掘分析孤儿核受体HNF4α在肾透明细胞癌(ccRCC)中的表达及意义。方法UALCAN分析HNF4α在肾透明细胞癌组织中的表达及其与患者总生存率的关系,分析与HNF4α表达具有相关性的基因群。TNMplot分析HNF4α基因mRNA在肿瘤、正常和转移组织中的表达。Kaplan-Meier Plotter分析HNF4α表达与肿瘤生存率的关系。STRING分析HNF4α蛋白质-蛋白质相互作用网络。结果HNF4α在肾透明细胞癌细胞中显著下调(P=0.002);在转移性肾透明细胞癌中表达水平进一步下调(P<0.001);HNF4α表达水平在肿瘤分级4级显著低于1级(P=0.007),在4级显著低于3级(P<0.001)。HNF4α表达水平与肿瘤预后呈负相关(P=0.017)。HNF4α低表达组总生存率显著低于高表达组(P<0.001)。Pearson相关系数>0.5的HNF4α表达正相关的基因有27个,其中ERBB3、CUBN、HNF1A、CES2与HNF4α表达相关系数最高。HNF4α与HNF1A、EP300、LEF1、SMAD3、SMAD4、NCOA1、HIF1A、FOXO1以及PPARGC1A均存在相互作用,其相互作用网络节点为11,蛋白-蛋白相互作用富集P值为3.44e-08。结论HNF4α在肾透明细胞癌中表达显著下调,并与肿瘤预后呈负相关,HNF4α及其相互作用关键因子可能在肾透明细胞癌发生、发展过程中扮演重要角色,具体作用及分子机制需进一步研究。

Real-time damage analysis of 2D C/SiC composite based on spectral characters of acoustic emission signals using pattern recognition

In this study,unsupervised and supervised pattern recognition were implemented in combination to achieve real-time health monitoring.Unsupervised recognition(k-means++)was used to label the spectral characteristics of acoustic emission(AE)signals after completing the tensile tests at ambient temperature.Using in-plane tensile at 800 and 1000°C as implementing examples,supervised recognition(K-nearest neighbor(KNN))was used to identify damage mode in real time.According to the damage identification results,four main tensile damage modes of 2D C/SiC composites were identified:matrix cracking(122.6–201 kHz),interfacial debonding(201–294.4 kHz),interfacial sliding(20.6–122.6 kHz)and fiber breaking(294.4–1000 kHz).Additionally,the damage evolution mechanisms for the 2D C/SiC composites were analyzed based on the characteristics of AE energy accumulation curve during the in-plane tensile loading at ambient and elevated temperature with oxidation.Meanwhile,the energy of various damage modes was accurately calculated by harmonic wavelet packet and the damage degree of modes could be analyzed.The identification results show that compared with previous studies,using the AE analysis method,the method has higher sensitivity and accuracy.