High sintering and dielectric performance:The improved(Mg,Zn)_(3)B_(2)O_(6) ceramics with the help of the DFT calculation

With the help of the first principle calculation,the solid-state reaction experiment was conducted to investigate the alteration in the sintering and the microwave dielectric properties of Mg_(3)B_(2)O_(6)ceramic with many Zn^(2+)substitutions.These properties were characterized using the scanning electron microscopy,network analyzer,X-ray diffraction,Raman spectroscopy,energy-dispersive spectroscopy,and thermomechanical and differential-thermal analyses.The coexistence of Mg_(3)B_(2)O_(6),Mg_(2)B_(2)O_(5)and ZnO ceramics could be observed with increasing Zn^(2+)addition,and the lattice distortion occurred in the Mg_(2)B_(2)O_(5)and Mg_(3)B_(2)O_(6)ceramics due to the substitution of Mg^(2+)with Zn^(2+).The electron density and the bond property of the MgO_(6)octahedron changed,and a quantitative method was used to discuss the variation in sintering,substitution and phase formation properties.The densification window was decreased to 1100℃,and the dielectric properties improved with the formation of a three-phase borate solid solution(dielectric constant=6.73,quality factor=112,000 GHz at 16 GHz(Q=7000),temperature coefficient of resonant frequency=-61.2 ppm℃^(-1),and relative density=97.0%).

声波激励的超小型纳机电系统磁电天线

当前的小型天线依赖于电磁波的谐振,因此天线的尺寸与电磁波波长相关。典型的天线尺寸大于波长的1/10,而进一步缩小天线尺寸在近十年来都是一个公开的挑战。介绍一种通过悬浮铁氧/压电薄膜异质结构的声波激励纳机械磁电天线。这种磁电天线通过其在声波谐振频率处的磁电效应接收和发射电磁波。磁电天线中的体声波激发铁磁薄膜的磁化振荡,产生电磁波的辐射;反之,天线感应电磁波的磁场,得到压电电压输出。这种磁电天线(尺寸仅为波长的千分之一)比现有小型天线的尺寸小1到2个数量级,但性能却没有降低,在便携式无线通信系统中具有很大的应用潜力。

Study on the Effect of "Glimmer" on Cadmium Absorption and Yield of Rice

[Objectives]The effects of"Glimmer"treatment on dry matter accumulation,yield and cadmium accumulation in different types of rice varieties were investigated,in order to provide a theoretical basis for the regulation of low cadmium accumulation in rice grains.[Methods]Under the treatment of cadmium contaminated soil with a concentration of 0.58 mg/kg,the effects of"Glimmer"treatment on dry matter accumulation,yield and cadmium content of different rice varieties were studied by pot experiment.[Results]Spraying"Glimmer"can increase the biological yield of rice,and the different types of rice showed the order of conventional rice>two-line hybrid rice>three-line hybrid rice.Among the conventional rice,most significant increase was observed in Huanghuazhan,and in two-line hybrid rice,C Liangyou 651 increased the most.The"Glimmer"treatment had an obvious yield increasing effect on conventional rice,among which such two varieties as Xiangwanxian 13 and Huanghuazhan had the largest increases,followed by the two-line hybrid rice,and a little effect was observed on the three-line hybrid rice.The"Glimmer"treatment resulted in a significant reduction in cadmium content in different types of rice,which decreased by 13.33%-26.09%,and seven varieties showed a reduction over 21.74%.[Conclusions]The"Glimmer"treatment can significantly reduce the cadmium content in rice,and generally promote the dry matter accumulation and yield increase of rice,of which conventional rice performed better.

一种实现单层MoS_(2)光致发光显著增强的有效缺陷工程策略

二维过渡金属硫族化合物(TMDCs)材料被认为是拓展摩尔定律的极具前景的候选材料.然而,该材料的低光致发光效率严重限制了其实际应用,其本质源于材料制备中不可避免引入的缺陷.在本文中,我们报道了一种Sr掺杂单层MoS_(2)的有效缺陷工程策略,该策略在实验上通过简便的化学气相沉积(CVD)一步法成功实现.所制备的具有亚毫米(~324μm)级的大尺寸样品的光致发光可实现高达两个数量级的增强,并伴随着载流子寿命的显著增强.这一现象主要归因于Sr掺杂后MoS_(2)体系中其三激子向激子转换.与此同时,掺杂样品的辐射质量和稳定性也显著提升.第一性原理计算进一步阐明了其调控机制,即在MoS_(2)中引入适当互补缺陷能级与其自身的缺陷能级协同,从而可调节其载流子组分,以实现光致发光的显著增强.此外,我们的缺陷工程策略也适用于其他掺杂剂,如钙掺杂剂.我们的工作报告了一种可以显著提升单层MoS_(2)的荧光性能的有效缺陷工程策略,这为设计和调控二维TMDCs的光电特性提供一种极具前途的方法.

Genome-wide DNA methylation landscape of four Chinese populations and epigenetic variation linked to Tibetan high-altitude adaptation

DNA methylation(DNAm)is one of the major epigenetic mechanisms in humans and is important in diverse cellular processes.The variation of DNAm in the human population is related to both genetic and environmental factors.However,the DNAm profiles have not been investigated in the Chinese population of diverse ethnicities.Here,we performed double-strand bisulfite sequencing(DSBS)for 32 Chinese individuals representing four major ethnic groups including Han Chinese,Tibetan,Zhuang,and Mongolian.We identified a total of 604,649 SNPs and quantified DNAm at more than 14 million Cp Gs in the population.We found global DNAm-based epigenetic structure is different from the genetic structure of the population,and ethnic difference only partially explains the variation of DNAm.Surprisingly,non-ethnic-specific DNAm variations showed stronger correlation with the global genetic divergence than these ethnic-specific DNAm.Differentially methylated regions(DMRs)among these ethnic groups were found around genes in diverse biological processes.Especially,these DMR-genes between Tibetan and nonTibetans were enriched around high-altitude genes including EPAS1 and EGLN1,suggesting DNAm alteration plays an important role in high-altitude adaptation.Our results provide the first batch of epigenetic maps for Chinese populations and the first evidence of the association of epigenetic changes with Tibetans'high-altitude adaptation.

高ρ不变量两个定义的等价性

对于紧定向光滑流形之间的保定向同伦等价,可定义与其相关的高ρ不变量.目前文献中,对于这个不变量存在两种不同的定义.本文论证了这两种定义互相等价.

The N^6-adenine methylation in yeast genome profiled by single-molecule technology

The most common and abundant DNA modification is 5-methylcytosine（5mC）,which has been well-established as an epigenetic mark regulating gene expression in eukaryotes（Jones,2012）.Another DNA modification N^6-methyldeoxyadenosine（6mA）,previously reported as a widespread DNA methylation in prokaryotes.

Generation and characterisation of rabbit monoclonal antibodies against the native cell surface antigens of embryonic stem cells

Embryonic stem （ES） cells are potent resources for cell therapy,and monoclonal antibodies （mAbs） against native cell surface markers of ES cells could be useful tools for therapeutic applications.Here,we report the development of a feasible approach,which could be used in mass production,for experimentally producing rabbit mAbs against native cell surface antigens on the cell surface.Two of the 14 mAbs,which were selected at random,could be bound to the cell surface antigens of mES cells.The immunocytochemistry （ICC） and Western blot results showed that mAb 39 recognises conformational epitopes.The target antigen of mAb 39 was then successfully purified using an improved immunoprecipitation approach in which mAb was bounded to intact mES cells before the cells were lysed.The LC-LTQ mass spectrum analysis showed that the target antigen of mAb 39 was Glut3.This result was further confirmed by Western blot using commercially available antibodies against Glut3.Further experiments showed that mAb 39 exhibited an antiproliferative effect on mES cells.We also found that Glut3 was differentially expressed among the mES cell population as detected by flow cytometry.

Geometric Property(T)

This paper discusses "geometric property(T)". This is a property of metric spaces introduced in earlier works of the authors for its applications to K-theory. Geometric property(T) is a strong form of "expansion property", in particular, for a sequence(Xn)of bounded degree finite graphs, it is strictly stronger than(Xn) being an expander in the sense that the Cheeger constants h(Xn) are bounded below.In this paper, the authors show that geometric property(T) is a coarse invariant,i.e., it depends only on the large-scale geometry of a metric space X. The authors also discuss how geometric property(T) interacts with amenability, property(T) for groups,and coarse geometric notions of a-T-menability. In particular, it is shown that property(T) for a residually finite group is characterised by geometric property(T) for its finite quotients.

Amelioration of sintering and multi-frequency dielectric properties of Mg_(3)B_(2)O_(6):A mechanism study of nickel substitution using DFT calculation

With the support of density functional theory(DFT)calculation,the amelioration of sintering and dielectric properties of the Mg_(3)B_(2)O_(6)(MBO)ceramic was realized through the substitution of magnesium with nickel.The TE-mode cylindrical cavity method was used to measure the dielectric properties at different frequencies.The thermo-mechanical analysis and simultaneous thermal analysis were used to characterize the chemical and mechanical properties.The phase composition was determined through the X-ray diffraction(XRD)and Raman spectrum.The microstructure was investigated using the scanning electron microscopy(SEM).Magnesium substitution with nickel(4 mol%)could ionize the B-0 bond of BO3,modify the vibration mode,improve the order degree,densify the microstmcture,decrease the intrinsic densification temperature,and ameliorate the dielectric properties of the MBO ceramics.The maximum values were achieved for the ceramics with 4 mol%nickel and sintered at 1175℃,that is,97.2%for relative density,72,600 GHz(10 GHz),75,600 GHz(11.4 GHz),and 92,200 GHz(15 GHz)for Q×f,7.1(10 GHz),7.01(11.4 GHz),and 6.91(15 GHz)for£r,and-56.3 ppm/℃ for if.