Experimental study of double tearing mode on EAST tokamak

The double tearing mode(DTM)in a high βN(βN>1.5)discharge with internal transport barrier on EAST was investigated.A 15 kHz tearing mode(TM)(m≥3,n=3)appears at outer q=2 surface at first,which is stable in the highβN phase.Then a 2 kHz TM(m=2,n=1)occurs at inner q=2 surface.Soon after,high βN collapsed with the crash of ELM,and DTM formed during the collapse of βN.The positions of the two islands of the DTM are consistent with the q=2 surface.The temperature fluctuations are the strongest between the two magnetic islands.A statistical analysis of high βN discharges operating with the reversed magnetic shear configuration in the EAST 2015-2018 campaign revealed the existence of the DTM in many discharges.During the DTM phase,all βN are reduced by 10%-30% within 0.1 s.However,there are two different βN behaviors thereafter-with and without βN recovery.Studying the physical mechanism of βN recovery during the DTM phase will benefit steady-state operation with reversed shear configurations in the future.

Research and Breeding Application Progress of the Technique of Producing Double Haploid of Wheat by Wide Hybridization between Wheat and Maize

The technique of producing doublehaploid of wheat by distant hybridization between wheat and maize has characterized with better inducing effect, shorter in- ducing period, easy operation, and so on. At present, it is the most efficient and has great potential of application in breeding of wheat. This article reviewed princi- ple and production process of the technique, research situation of the three key in- dicators of the technology（embryo rate, seedling rate and success rate of doubling）in recent years, and application of the technology in breeding, genetics, germplasm improvement of wheat. At last, both the achievements and the direction of further improvement and development of the technology in our program were discussed.

Disposal of wastewater containing Congo Red by synthesizing layer double hydroxide in-situ

Based on the principle of synthesis, a new method was put forward to dispose Congo Red anion-containing dyestuff from wastewater and its feasibility was also examined. The principle of the method is described as follows: Mg2+ and Al3+ are hydrolyzed to form Mg/Al-LDH by adding Mg2+, Al3+ and NaOH in wastewater containing anion dyestuff, which is selectively intercalated with the interlayer of LDH in order to balance positive structural charge. While Mg2+ and Al3+ are co-precipitated to form LDH, the anion dyestuff in wastewater will be removed by LDH synthesized in-situ, as is confirmed by X-ray diffraction analysis of settlings and chemical analysis of aqueous samples. In this work, we studied the influence of Mg/Al mole ratio, pH value, time and temperature of reaction on the removal of anion dyestuff and the use of Mg and Al. The experimental results showed the maximum removal efficiency of anion dyestuff could be attained when pH value was 9.0, and Mg/Al mol ratio was 2∶1, reaction duration was 2 hours, and the effect of temperature was not remarkable, and the removal efficiency could reach 100%. Meanwhile, the Mg and Al added could be made good use of. This technology has the advantage of extraordinary efficiency of wastewater disposal.

Comparison between Double Crystals X-ray Diffraction and Micro-Raman Measurement on Composition Determination of High Ge Content Si_(1-x)Ge_(x) Layer Epitaxied on Si Substrate

It is important to acquire the composition of Si1-xGex layer, especially that with high Ge content, epitaxied on Si substrate. Two nondestructive examination methods, double crystals X-ray diffraction （DCXRD） and micro-Raman measurement, were introduced comparatively to determine x value in Si1-xGex layer, which show that while the two methods are consistent with each other when x is low, the results obtained from double crystals X-ray diffraction are not credible due to the large strain relaxation occurring in Si1-xGex layers when Ge content is higher than about 20%. Micro-Raman measurement is more appropriate for determining high Ge content than DCXRD.

EFFECT OF GEAR WIDTH AND HELIX ANGLE ON FACTOR OF DYNAMIC LOAD OF DOUBLE CIRCULAR ARC HELICAL GEARING

Based on theory of mechanical dynamics, meshing characteristic as well as thedynamic model of double circular arc helical gearing, an analysis approach and a computer programhave been developed for studying the state of dynamic load and factor of dynamic load of thegearing, the changing situation of dynamic load and dynamic load factor vs some affecting factorssuch as gear width, helix angle and accuracy grade etc are investigated. A series of conclusions areobtained: ①With the increasing in the values of gear width, the dynamic load factor appears slowdecreasing tendency in most region of gear width. ②When the accuracy grades of the gearing areimproved, the values of dynamic load factor decrease. ③The value of dynamic load factor appears adecreasing tendency with the increasing of value of helix angle at the same ratio of criticalrotational speed.

Double-Mesopore V-MSU-X Silica and its Pure Siliceous Derivative Prepared by One Synthesis System

Non-ionically templated organo-modified MSU-2 mesoporous silicas have been prepared in neutral medium by co-condensation TEOS and vinyltriexoylsiloxane (VTES) and exhibit highly symmetric bimodal mesopore systems. A bromination reaction of V-MSU-2 provides evidence for attachment of most vinyl groups to the accessible surface within the channels. Further, siliceous MSU-2 materials with double pore size have been obtained from calcination of so-produced organo-modified MSU-2 and demonstrate the immense flexibility of the non-ionic templating system.

Jahn–Teller Effect, Crystal Structure and High Temperature Raman Spectroscopy Studies of Ba_2-xSr_xCuWO₆(0 ≤x≤2) Double Perovskite Oxide.

The following article has been retracted due to the investigation of complaints received against it. The Editorial Board found that there are conflicts of interests among the authors. The scientific community takes a very strong view on this matter, and the Advances in Materials Physics and Chemistry treats all unethical behaviors seriously. This paper published in Vol. 4 No. 4 61-74, 2014 has been removed from this site. Title: Jahn–Teller Effect, Crystal Structure and High Temperature Raman Spectroscopy Studies of Ba2-xSrxCuWO6 (0 ≤ x≤ 2) Double Perovskite Oxide. Authors: Amine Ezzahi, Abdellah

利用改良的CRISPR/Cas9n double nick系统构建DPF2基因敲除的人胰腺癌PANC-1细胞株

目的利用改良的CRISPR/Cas9n double nick系统构建DPF2基因敲除的PANC-1人胰腺癌细胞模型。方法设计两对靶向DPF2基因第四外显子上下游的单链向导RNA(single guide RNA,sgRNA),化学合成sgRNA寡核苷酸序列,并克隆至pGL3-U6-sgRNA-PGK-puromycin真核表达质粒中。将克隆正确的DPF2-sgRNA重组真核表达质粒与Cas9真核表达载体pST1374-N-NLS-flag-linker-Cas9共转染至PANC-1细胞中,通过嘌呤霉素和杀稻瘟菌素筛选阳性转染细胞,进一步通过有限稀释法筛选获得单克隆细胞株。提取细胞基因组DNA对敲除位点进行聚合酶链反应(PCR)鉴定和测序鉴定。Western blot检测细胞中DPF2蛋白表达情况。结果sgRNA成功插入pGL3-U6-sgRNA-PGK-puromycin中且序列正确。PCR扩增鉴定和测序结果表明,PANC-1细胞中一段包括完整第四外显子在内的长度为401 bp的DPF2基因片段被敲除。Western blot检测结果表明,DPF2基因敲除细胞中的DPF2蛋白表达缺失。结论通过改良的CRISPR/Cas9n double nick基因编辑系统成功构建DPF2基因敲除PANC-1稳定细胞株。

Non-leguminous winter cover crop and nitrogen rate in relation to double rice grain yield and nitrogen uptake in Dongting Lake Plain, Hunan Province, China

Annual ryegrass（Lolium multiflorum Lam.）, a non-leguminous winter cover crop, has been adopted to absorb soil native N to minimize N loss from an intensive double rice cropping system in southern China, but a little is known about its effects on rice grain yield and rice N use efficiency. In this study, effects of ryegrass on double rice yield, N uptake and use efficiency were measured under different fertilizer N rates. A 3-year（2009–2011） field experiment arranged in a split-plot design was undertaken. Main plots were ryegrass（RG） as a winter cover crop and winter fallow（WF） without weed. Subplots were three N treatments for each rice season： 0（N_0）, 100（N_（100）） and 200 kg N ha–1（N_（200））. In the 3-year experiment, RG reduced grain yield and plant N uptake for early rice（0.4–1.7 t ha–1 for grain yield and 4.6–20.3 kg ha–1 for N uptake） and double rice（0.6–2.0 t ha–1 for grain yield and 6.3–27.0 kg ha–1 for N uptake） when compared with WF among different N rates. Yield and N uptake decrease due to RG was smaller in N_（100） and N_（200） plots than in N_0 plots. The reduction in early rice grain yield in RG plots was associated with decrease number of panicles. Agronomic N use efficiency and fertilizer N recovery efficiency were higher in RG plots than winter fallow for early rice and double rice among different N rates and experimental years. RG tended to have little effect on grain yield, N uptake, agronomic N use efficiency, and fertilizer N recovery efficiency in the late rice season. These results suggest that ryegrass may reduce grain yield while it improves rice N use efficiency in a double rice cropping system.

Performance improvement of AlGaN-based deep ultraviolet light-emitting diodes with double electron blocking layers

The AlGaN-based deep ultraviolet light-emitting diodes（LED） with double electron blocking layers（d-EBLs） on both sides of the active region are investigated theoretically. They possess many excellent performances compared with the conventional structure with only a single electron blocking layer, such as a higher recombination rate, improved light output power and internal quantum efficiency（IQE）. The reasons can be concluded as follows. On the one hand, the weakened electrostatic field within the quantum wells（QWs） enhances the electron–hole spatial overlap in QWs, and therefore increases the probability of radioactive recombination. On the other hand, the added n-AlGaN layer can not only prevent holes from overflowing into the n-side region but also act as another electron source, providing more electrons.

Injection modulation of p^+-n emitter junction in 4H-SiC light triggered thyristor by double-deck thin n-base

To overcome hole-injection limitation of p^＋-n emitter junction in 4H-SiC light triggered thyristor, a novel high- voltage 4H-SiC light triggered thyristor with double-deck thin n-base structure is proposed and demonstrated by two- dimensional numerical simulations. In this new structure, the conventional thin n-base is split to double-deck. The hole- injection of p^＋-n emitter junction is modulated by modulating the doping concentration and thickness of upper-deck thin n- base. With double-deck thin n-base, the current gain coefficient of the top pnp transistor in 4H-SiC light triggered thyristor is enhanced. As a result, the triggering light intensity and the turn-on delay time of 4H-SiC light triggered thyristor are both reduced. The simulation results show that the proposed 10-kV 4H-SiC light triggered thyristor is able to be triggered on by 500-mW/cm^2 ultraviolet light pulse. Meanwhile, the turn-on delay time of the proposed thyristor is reduced to 337 ns.

Study on Chromosome Doubling for Haploid Produced by Wheat×Maize Crossing

There is no spontaneous chromosome doubling in haploid plants produced by wheat X maize crossing. In order to obtain doubled haploid, two chromosome doubling methods were used. Results showed that: After adding colchicine solution directly into a medium for young embryos that had been cultured 7 days, frequencies of embryo germination in colchicine concentrations of 50mg/L, 100mg/L and 200mg/L were 32.1% , 26.4% and 16.3% , respectively, and frequencies of chromosome doubling were 85.3% , 100% and 50.0% , respectively. But in the control without colchicine, the frequency of embryo germination was 67.4% and no seed was setting. As the time of colchicine treatment increased from 24 to 72 hours, the frequency of embryo germination was reduced, and 24 hours had better results. After soaking seeding crowns and roots with colchicine solution of 500mg/L, 750mg/L and 1 000mg/L for 5 hours, the frequencies of doubling were 89.6%, 76.0% and 73.3%, respectively. By soaking crowns and roots of strong seedings with 500mg/L colchicine solution, the frequency and efficiency of doubling were 98.2% and 93.2% , respectively.

Study on Pollen Chromosome Doubling in Zenjimaru Persimmon

The factors influencing pollen chromosome doubling in Zenjimaru persimmon were studied, based on the knowledge of meiosis process of pollen mother cells. The results showed: (1) the suitable concentration of colchicine was 0.3-0. 5%; (2) the best doubling effect could be obtained during the period from the diplotene stage to the diakinasis stage, and the highest proportion was up to 40.6%; (3) considering giant pollen ratio and proportion of staminate-flower collection, the better treating frequency was 3 times; (4) giant pollen, which formed mainly from dyad and had bigger cell nucleus volume, was unreduced and hexaploid.

On Turán type inequality with doubling weights and A weights

Let Hn be the set of real algebraic polynomials of degree n, whose zeros all lie in the interval [-1,1]. The well known Turán type inequalities tell us that forf（x）∈Hn, it holds ‖f＇‖≥C√n‖f‖. This note deals with the weighted Turán type inequalities with the weights having inner singularities under L^p norm for 0〈p≤∞. Our results essentially extend the result of Wang and Zhou （2002）, and the method used in this paper is simpler and more direct than that of Wang and Zhou （2002）. The results and methods have their own values in approximation theory and computation.

低负荷下运行氧量对锅炉燃烧及NO_(x)生成特性的影响研究

为探究低负荷工况下运行氧量对双切圆锅炉燃烧效率及NO_(x)生成特性的影响,结合实际案例,对某1000 MW双切圆锅炉开展了低负荷工况下运行氧量(5.6%、6.0%、6.4%)对燃烧效率及NO_(x)生成特性影响的模拟与试验研究。模拟结果表明:低负荷工况下,运行氧量从5.6%增加到6.0%时,锅炉燃烧飞灰含碳量显著降低,NO_(x)浓度有所增加;进一步增加运行氧量到6.4%,锅炉燃烧飞灰含碳量降低幅度相对较小,NO_(x)有轻微增加。现场试验结果表明:运行氧量控制在6.0%左右,锅炉燃烧飞灰含碳量较低且燃烧效率较高,汽温可维持在相对较好的水平。综合考虑,在低负荷运行条件下,建议将锅炉燃烧的运行氧量控制在6.0%左右,可达到高效低NO_(x)的燃烧目的。

Mg_xZn_(1-x)O单晶薄膜的结构和光学性质

用等离子辅助分子束外延 (P MBE)的方法 ,在蓝宝石c平面上外延生长了MgxZn1 xO合金薄膜。在0≤x≤ 0 2范围内薄膜保持着ZnO的纤锌矿结构不变。X射线双晶衍射谱的结果表明生长的样品是单晶薄膜。据布喇格衍射公式计算得到 ,随着Mg含量的增加 ,薄膜的晶格常数c由 0 5 2 0 5nm减小到 0 5 1 85nm。室温光致发光谱出现很强的紫外近带发射 (NBE)峰 ,没有观察到深能级 (DL)发射 ,且随着Mg的掺入量的增加 ,紫外发射峰有明显的蓝移。透射光谱的结果表明 ,合金薄膜的吸收边随着Mg离子的掺入逐渐向高能侧移动 ,这与室温下光致发光的结果是相吻合的 ,并计算出随着x值增加 ,带隙宽度从 3 338eV逐渐展宽到3 6 82eV。通过研究Mg0 1 2 Zn0 88O样品的变温光谱 ,将紫外发射归结为束缚在施主能级上的束缚激子发射。并详细地研究了在整个温度变化过程中 ,束缚激子的两个不同的猝灭过程以及谱线的半峰全宽与温度变化的关系。

X射线辐照诱导人神经胶质瘤细胞DNA双链损伤研究

采用免疫荧光染色法检测X射线诱导M059K细胞磷酸化组蛋白H2AX(γH2AX)和磷酸化的毛细血管扩张性共济失调症突变基因(pATM)焦点的形成;流式细胞仪分析M059K细胞γH2AX和pATM表达的周期依赖性。免疫荧光染色检测结果显示,γH2AX和pATM焦点阳性细胞分别以照射后0.5、4 h表达最高,照射后24h,高剂量组焦点阳性细胞达100%。流式细胞仪分析结果显示,γH2AX和pATM的表达具有细胞周期依赖性。照射后0.5、4 h,γH2AX和pATM在细胞各期的表达均明显增加,并以G0/G1期为著;照射后24 h,γH2AX和pATM在G0/G1和S期表达降低,而G2/M期细胞表达明显增加。细胞呈现明显的G2/M期阻滞。结果提示,γH2AX和ATM信号通路参与X射线诱导的M059K细胞DNA双链断裂。

高增益的类Ne锗软X光激光实验

采用新颖的“双靶对接”设计,利用强度约12×10^(13)W/cm^2,波长1.05μm,脉宽约1ns的两路激光线聚焦辐照平面厚锗双靶,观察到了波长为19.6、23.2、23.6、24.7和28.6nm的五根类Ne锗3p-3s跃迁谱线的放大。波长为23.2和23.6nm的谱线,增益-长度乘积GL的值约13。利用软X光扫描相机观测了四根软X光谱线的时间特性。

红外非线性晶体材料AgGa_(1-x)In_xSe_2的生长和性能表征

AgGa1-xInxSe2是近几年来研制的新型红外非线性光学晶体材料,其主要特点是借着Ga和In含量,即x值的变化,改变材料的折射率、双折射,实现三波共线非线性作用的非临界(90°)相位匹配。我们用垂直布里奇曼法生长单晶,获得了35mm×50mm的AgGa1 xInxSe2单晶棒。对生长出晶体棒In的浓度分布进行了测试。晶体元件用红外观察镜和分光光度计分别进行了观察和测试,晶体透光率良好。用一台TEACO2激光泵浦一块5×6×16mm3 的AgGa1 xInxSe2(x=0.3234)晶体元件,成功地实现了10.6μm非临界相位匹配倍频,输出5.3μm的中红外激光。

用X双晶衍射法研究InGaAs／GaAs量子阱结构

用X射线双晶衍射方法对MBE方法生长的InGaAs／GaAs量子阱结构卡才料进行了测试分析。结果表明,在材料生长过程中,深能级的引入严重影响了材料的光学特性及界面完整性。通过改变衬底温度、Ⅴ／Ⅲ速流比等实验条件,得到了质量较好的材料。同时对实验样品的双晶衍射回摆曲线中干涉条纹及峰的劈裂现缘进行了理论分析。