Exchange bias effect in multiferroic Eu0.75Y0.25MnO3

The exchange bias phenomenon has been investigated in multiferroic Eu_0.75Y_0.25MnO₃. The material shows a weak ferromagnetism with cone spin configuration induced by external magnetic field below 30 K. Consequently, the electric polarization coming from the cycloid spin order below 30 K can be suppressed by external magnetic fields. The magnetic hysteresis loops after cooling in a magnetic field exhibit characteristics of exchange bias below the spin glassy freezing temperature (T_g)∼16 K. The exchange bias field, coercivity field, and remanent magnetization increase with increasing cooling magnetic field. The exchange bias effect is ascribed to the frozen uncompensated spins at the antiferromagnetism/weak ferromagnetism interfaces in the spin-glass like phase.     

热屏优化对大直径单晶硅生长影响的数值模拟

通过对28英寸热场生长300 mm硅单晶过程中结晶速率、固液界面形状、晶体中热应力及晶体中氧含量的数值计算提出了在该热场条件下热屏的优化方案。数值计算结果表明:对热屏底端与晶体表面和熔体自由液面的距离以及热屏材料(优化前热屏使用单一石墨材料,优化后采用辐射率较高的内壁材料结合反射率较高的外壁材料组成复合式热屏)的优化可以减少主加热器对晶体的热辐射使得固液界面更加平坦,藉此增加结晶速率,减小晶体内热应力和熔体中氧含量。     

HEM11 mode magnetically insulated transmission line oscillator： Simulation and experiment

A novel magnetically insulated transmission line oscillator （MILO） in which a modified HEM11 mode is taken as its main interaction mode （HEM11 mode MILO） is simulated and experimented in this paper. The excitation of the oscillation mode is made possible by carefully adjusting the arrangement of each resonant cavity in a two-dimensional slow wave structure. The special feature of such a device is that in the slow-wave-structure region, the interaction mode is HEM11 mode which is a TM-like one that could interact with electron beams effectively; and in the coaxial output region, the microwave mode is TE11 mode which has a favourable field density pattern to be directly radiated. Employing an electron beam of about 441 kV and 39.7 kA, the HEM11 mode MILO generates a high power microwave output of about 1.47 GW at 1.45 GHz in particle-in-cell simulation. The power conversion efficiency is about 8.4 % and the generated microwave is in a TEll-like circular polarization mode. In a preliminary experiment investigation, high power microwave is detected from the device with a frequency of 1.46 GHz, an output energy of 43 J 47 J, and a pulse duration of 44 ns-49 ns when the input voltage is 430 kV450 kV, and the diode current is 37 kA-39 kA.     

α1-酸性糖蛋白柱拆分马来酸曲美布汀对映体

以α1-AGP为固定相,建立了马来酸曲美布汀的HPLC对映体拆分方法.考察了流动相pH、缓冲盐溶液的浓度、有机改性剂种类和浓度、流速、柱温等对对映体分离的影响.优化后的色谱条件为Chiral-AGP(100 mm×4.0 mm,5 μm)色谱柱,流动相为10 mmol/L醋酸铵缓冲液(pH 3.8);流速为0.4 mL/min;柱温为35℃.马来酸曲美布汀对映体的保留时间分别为7.4 min和9.8 min;分离度为1.59.     

某些碱性吩嗪染料与肝素相互作用的共振瑞利散射光谱研究

在pH为6．6—7．2,6．0—7．0和5．2—6．4的介质中,中性红(NR)、藏红T(ST)和酚藏花红(PS)等碱性吩嗪染料与肝素反应形成复合物,使溶液共振瑞利散射(RRS)增强,并出现新的RRS光谱。其最大散射峰分别位于600nm(NR体系)、568nm(ST体系)和560nm(PS体系),其中以NR体系灵敏度最高。它对肝素的检出限(3σ)为0．80μg/L。研究了适宜的反应条件和影响因素,并以中性红体系为例,考察了共存物质的影响,表明方法有较好的选择性,用于肝素钠注射液效价的测定,结果较好。     

二苄基一氯化锡氨荒酸酯的合成与表征

合成了13个新的二苄基氯化锡氨荒酸酯化合物(PhCH_2)_2Sn(Cl)S_2CNRR＇。利用元素分析、UV.IR.H NMR谱和TG-DTA表征了它们的结构 初步生物活性研究表明,有些化合物表现出体外抑制白细胞P_(388)生长的活性。     

SYNTHESIS AND CHARACTERIZATION OF NOVEL CHIRAL SMECTIC C(Sc*) PHASE SHISH-KEBAB TYPE LIQUID CRYSTALLINE BLOCK COPOLYMERS*

A new series of chiral shish-kebab type liquid crystal block copolymers that form the smecticC(Sc~*) phase was synthesized by solution polycondensation. The copolymers were characterized by GPC.DSC. TG, POM. X-ray diffraction and polarimeter. The copolymers 7 entered into liquid crystal phase whenthey were heated to their melting temperatures (T_m) and the copolymers 8 were in liquid crystal phase at roomtemperature with low viscosities. The smectic sanded texture or focal-conic texture were observed on POM.All the chiral block copolymers showed high optical activity. No racemization has happened. Temperature-variable X-ray diffraction study together with POM and polarimetric analysis realized that they are chiralsmectic C(Sc~*) phase. Thus we offer in this report the first example of shish-kebab type liquid crystal blockcopolymers that form a chiral smectic C(Sc~*) phase. The variation of melting and isotropization temperatureswith molecular structure was also discussed.     

COMPOSITIONAL HETEROGENEITY OF ETHYLENE OXIDE-BUTYLENE TEREPHTHALATE SEGMENTED COPOLYMER*

A series of ethylene oxide-butylene terephthalate (EOBT) segmented copolymers with differentsoft segment length and hard segment content were synthesized. The compositional heterogeneity was studiedby solvent extraction. The results show that the compositional heterogeneity increases when soft segmentlength and hard segment content increase. The compositional heterogeneity is also reflected in thecrystallization behavior and morphology of soft and hard segment in EOBT segmented copolymer. The morecompositional heterogeneous the EOBT segmented copolymer is, the more different the morphology and thecrystallization behavior between separated fractions. Compared with ethylene oxide-ethylene terephthalate(EOET) segmented copolymer, compositional heterogeneity in EOBT segmented copolymer is weaker. Butthe compositional heterogeneity in EOBT segmented copolymer with long soft segment and high hardsegment content is still obvious.     

Synthesis,Structure,Characterization and Electrochemistry of a New Dinuclear W(0)-complex 〔Et_4N〕_2〔W_2(CO)_8(SCH_2COOMe)_2〕

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On the positive radial solutions of a class of singular semilinear elliptic equations

In this paper, we consider the following elliptic equation(0.1)$\mathit{div}\left(A\right(|x|\left)\mathrm{?}u\right)+B(|x|)u^p=0\text{in}{\mathbb{R}}^n,$ where $p>1$, $n?3$, $A(|x|)>0$ is differentiable in ${\mathbb{R}}^n?\{0\}$ and $B(|x|)$ is a given nonnegative Hölder continuous function in ${\mathbb{R}}^n?\{0\}$. The asymptotic behavior at infinity and structure of separation property of positive radial solutions with different initial data for (0.1) are discussed. Moreover, the existence and separation property of infinitely many positive solutions for Hardy equation and an equation related to Caffarelli–Kohn–Nirenberg inequality are obtained respectively, as special cases.