Effect of Preparation Method on Surface Area and Crystalline Form of CeO_2-ZrO_2 Solid Solution

The CeO_2-ZrO_2 solid solutions were prepared by a reverse microemulsion method. The effect of preparation parameters on the surface area and crystalline form of the solid solutions were studied by the BET surface area and XRD analysis. The studies indicate that the separation of the microemulsion phase during the preparation procedure can decrease the specific surface area of sample, adding hydrogen peroxide in the matrix solution can increase the specific surface area and stability of sample. The surface area of sample calcined at 550 ℃ for 5 h is 149 m^2·g^(-1), and that calcined at 900 ℃ for 6 h is 88 m^2·g^(-1). The sample with tetragonal symmetry Ce_(0.5)Zr_(0.5)O_2 phase has a higher stability.

Effects of Pore-forming Agents on Properties of Silicon Carbide Porous Ceramics Prepared from Crystalline Silicon Cutting Waste

SiC powder was rapidly synthesized in an induction furnace with crystalline silicon cutting waste and active carbon as raw materials,and then SiC porous ceramics were prepared at 1600 t for 4 h with carbon embedded using the powder as raw material,the starch and the graphite as pore-forming agents.Effects of additions of different pore-forming agents on the phase composition,microstructures,physical properties,and cold crushing strength of the porous ceramics were investigated.The results show that the main crystalline phases of the synthetic powder areα-S iC(6H-SiC)andβ-SiC(3C-SiC).The phase composition of the porous ceramics includesα-S iC(6H-SiC),β-SiC(3C-SiC),FeSi,quartz and Si2N20.The apparent porosity and closed porosity of the porous ceramics prepared by adding starch are higher,and the cold compressive strength of the porous ceramics added with graphite is higher.As increasing the additions of the starch,the apparent porosity,closed porosity and linear shrinkage ratio of the porous ceramics increase,and the bulk density decreases correspondingly.When 20 mass%starch is added,the apparent porosity,closed porosity,linear shrinkage ratio and cold compressive strength are 57.05%,2.03%,5.10%and 10.20 MPa,respectively.

Unveiling the planar deformation mechanisms for improved formability in pre-twinned AZ31 Mg alloy sheet at warm temperature

To investigate the role of pre-twins in Mg alloy sheets during warm planar deformation, the stretch forming is conducted at 200 ℃. Results suggest the formability of the pre-twinned AZ31 Mg alloy sheet is enhanced to 11.30 mm. The mechanisms for the improved formability and the deformation behaviors during the planar stretch forming are systematically investigated based on the planar stress states. The Schmid factor for deformation mechanisms are calculated, the results reveal that planar stress states extremely affect the Schmid factor for {10-12}twinning. The detwinning is activated and the prismatic slip is enhanced in the pre-twinned sheet, especially under the planar extension stress state in the outer region. Consequently, the thickness-direction strain is accommodated better. The dynamic recrystallization(DRX) type is continuous DRX(CDRX) regardless of the planar stress state. However, the CDRX degree is greater under the planar extension stress state.Some twin lattices deviate from the perfect {10-12} twinning relation due to the planar compression stress state and the CDRX. The basal texture is weakened when the planar stress state tends to change the texture components.

PREPARATION AND MORPHOLOGY OF ISOTACTIC POLYPROPYLENE WITH HIGH CONTENT OF β CRYSTALLINE FORM

Isotactic polypropylene (iPP) with high content of ~ crystalline form was prepared by adding a series of new p form nucleators. The spherulites and morphology of//farm iPP (//-iPP) were investigated by wide-angle X-ray diffraction(WAXD), polarizing microscope (PLM), scanning electron microscope (SEM) and small-angle light scattering (SALS). WAXD experimental results indicate that the amount of p form in iPP (K_x) increases with increasing /~ nucleator content from zero to 0.07 wt% or crystallization temperature T_c from 20 to 120℃ and that the highest K_x value is up to 0.95. PLM observations suggest that p spherulites exhibit bright color and that their Maltese Crosses display some concentric banding of a rather spiky, jagged character. Their !amellae are smooth and relaxed layer-plate like structure by SEM and their SALS H_v patterns arc four-petalled.

MOLECULAR CHAIN STRUCTURE AND CRYSTALLINE STRUCTURE OF PB-ET COPOLYESTER

The molecular chain structure and crystalline structure of PB-ET copolyester made by con-densation polymerization are studied by means of 13C nuclear magnetic resonance spectroscopy(13C NMR),dynamic mechanical analysis （DMA）,wide angle X-ray scattering （WAXS）,depolarized light intensity （DLI） and stress-strain measurement（S-S）.It is shown that PB-ETcopolyester is a random copolymer.Because of different ratios of EG（ethylene glycol）to BD（butane diol）in the copolyester,its crystalline forms and mechanical properties vary remarkably.With the increasing amount of BD,its crystallization kinetic parameters n,k and t1/2-1 increaserapidly.When EG/BD equals 25/75 （mole ratio）,the copolyester has αβ transition as PBTdoes.

The Protective Effects of Flavonoids from Scutellaria Baicalensis Georgi Stems and Leaves on Oligodendrocyte Damage Induced by Aβ1-42

Aim: This study aimed to investigate the protective effects of flavonoids from the stem and leaves of Scutellaria baicalensis Georgi (SSFs) against Aβ1-42-induced oligodendrocytes (OL) damage. Methods: Immunofluorescence was used for the detection of myelin-associated glycoprotein (MAG), a characteristic protein of rat oligodendrocytes (OLN-93 cells). To evaluate the potential protective effects of SSFs on OLN-93 cells injured by Aβ1-42, an injury model was established by subjecting OLN-93 cells to Aβ1-42 exposed. Cell morphology was examined using an inverted microscope, while cell viability was assessed using the colorimetric method of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Additionally, lactate dehydrogenase (LDH) was measured using the pyruvic acid reduction assay. The Ginkgo biloba leaf extract (GBE) injection was used as a positive control. Results: A total of >95% of the MAG immunofluorescence-positive cells were identified as oligodendrocytes. Gradually increasing concentrations of SSFs impaired the cells, and the maximum nondetrimental dose for OLN-93 cells was 75 mg/L. This study assessed the effects of SSFs on OLN-93 cells damaged by Aβ1-42. The results indicated that SSFs significantly improved OLN-93 cell morphological abnormal changes, increased the OLN-93 cell survival rate, and reduced LDH release. Conclusion: SSFs can alleviate Aβ1-42-induced damage of OL.

Preparation of SiC Porous Ceramics by Crystalline Silicon Cutting Waste

SiC porous ceramics were prepared at 1 400 ℃ for4 h with crystalline silicon cutting waste and activated carbon as main starting materials and NH4HCO3 as the pore-forming agent. Effects of NH4HCO3 additions( 0,20%,30%,40%,by mass) on the phase composition,microstructure,sintering properties,cold compressive strength and thermal shock resistance of as-prepared Si C porous ceramics were investigated. The results show that:( 1) addition of NH4HCO3 remarkably influences the apparent porosity and cold compressive strength of specimens. The apparent porosity achieves its maximum value( 63. 40%) when 40% NH4HCO3 is added,while the minimum cold compressive strength is 4. 77 MPa;( 2) the specimen with 40% NH4HCO3 has the best thermal shock resistance. The thermal cycling times between1 000 ℃ to room temperature reach 62;( 3) the addition of NH4HCO3 does not remarkably affect the phase composition of the specimens;( 4) the specimens include a large number of SiC particles and a small amount of SiC whiskers.

Superplastic Forming and Diffusion Bonding for Sandwich Structure of Ti-6Al-4V Alloy

Superplastic forming and diffusion bonding (SPF/DB) is a well-established process for the manufacture of components almost exclusively from Ti-6AI-4V sheet material. The sandwich structure of Ti-6AI-4V alloy is investigated. The effects of the microstructure on the SPF/DB process were discussed. The microstructure at the interfaces and the distribution of thickness were researched.

The Evolutionary History of Ore-forming Processes of Metallic Ore Deposits in Northern Guangxi

The northern Guangxi region is an important rare metal, rare earth metal and polymetallic metallogenic province. In the region there exist five metallogenic series and two metallogenic subseries, whose metallogenesis shows features of polycyclic spiral evolution throughout the geological history. As far as various cycles are concerned, mantle-derived ore substances were reduced while crust-derived ore substances increased from early to late timesfin the whole geological evolutionary history, mantle-derived substances decreased gradually while crust-derived ones increased. Meanwhile ore element associations became more and more varied. In terms of space, mineralization migrated from the old basement outwards, i.e. from west to east during the Precambrian, and from north to south during the Phanerozoic, and again from east to west during the Yanshanian.

The Forming Conditions of and Ore-searching Direction for B, Mg,Pb, Zn and Au Deposits in the Liaoji Proterozoic Rift

The Liaoji Proterozoic rift is an inter-intracontinenatl rift developed from Archean granite-greenstone tectonic regime and contains many important mineral deposits of U, B, magnesite, Pb-Zn, Au, Ag, Co and P. These deposits were formed as the result of late mobilization, transportation and concentfation of the previously enriched ore-forming mate- rials in several ore-bearing formations formed during the rift stage. So the metallogeny of these deposits in the rift shows both inheritance and new generation of the ore-forming materials. In future ore-searching practice, attentions should be paid on the studies of the ore-bearing formations in the rift, on the multiple stages of metallogeny and and on multiple derivations of the ore-forming materials.

P(VDF-TrFE)共聚物结晶性能研究进展

P(VDF-TrFE)凭借其柔性好、频率响应大、化学性能稳定和自发极化强度高,在柔性有机器件中具有广阔应用前景。聚合物的结晶性能直接决定其压电、铁电性能的强弱,本文综述了单体共聚比例、薄膜制备工艺条件及共混物类型与含量等因素对P(VDF-TrFE)共聚物结晶性能的影响,并简要阐述了各种因素对P(VDF-TrFE)结晶性能的影响机理。

卤水表面附近盐岩结晶特征研究

【目的】为了弥补现代盐湖沉积考察中丢失的信息,获取盐岩动态结晶过程,指导古盐湖沉积研究。【方法】借助室内石盐蒸发实验,观察卤水蒸发过程中氯化钠结晶特征,分析石盐结晶与沉积环境之间的关系,为盐湖沉积模式建立提供参考。【结果与结论】石盐沉积位置受结晶习性影响,晶体可以在卤水界面之上沉积,其形成的动力除了蒸发泵作用外,还受空气湿度和石盐潮解共同控制;人字晶一般形成于漏斗晶基础之上,在发育空间受限时,绕不同漏斗晶核生长的纹层斜交后形成人字晶纹,两种晶型可以同时沉积于水面之上;盐湖干涸之前,可能经历岩层封锁水面的现象,并可能对临层的碎屑沉积物产生影响。

β型成核剂在聚丙烯中的应用 Ⅰ.NA-BW引导聚丙烯结晶行为及力学性能

通过酰胺化合物(NA-BW)引导等规聚丙烯(iPP)制备高水平β晶型聚丙烯(β-iPP),借助广角X射线衍射(WAXD),差示扫描量热仪(DSC)及偏光显微镜(POM)研究其结晶形态及结晶行为,并研究了β型成核剂对iPP力学性能的影响。结果表明:加入β型成核剂NA-BW后,iPP的晶型和球晶形态均发生变化;等温结晶研究表明聚丙烯的半结晶时间(t1/2)明显降低,即结晶速度加快,非等温结晶研究表明iPP的结晶温度提高;iPP的冲击强度大大提高,拉伸和弯曲性能却略有下降。当成核剂用量为3 m g/g时,悬臂梁缺口冲击强度达到最大值,提高达3.5倍,由49.35J/m提高到176.23 J/m。热稳定性实验表明β型成核剂对聚丙烯成核效果的热稳定性良好。

纤维素在N-甲基吗啉-N-氧化物/水溶液中的溶胀与溶解性能

研究了纤维素在N-甲基吗啉-N-氧化物(NMMO)/水体系中的溶胀、溶解过程对纤维素溶液性能的影响,为纤维素在NMMO/水体系中纺丝成形提供理论依据。利用X-射线衍射(XRD)探索了纤维素溶胀后的结晶结构变化,利用旋转流变仪探讨了纤维素浓度、聚合度等对纤维素溶液流变性能的影响。结果表明:经溶胀后的纤维素,非晶区被部分破坏,使其结晶度下降,从而更易被均匀、快速地溶解;纤维素的聚合度越大,含量越高,其大分子链的解缠及伸展越困难,分子间作用越大,纤维素溶液的流动性越差,越不利于纤维素的纺丝成形。

激光Raman光谱研究2,4己二炔-1,6二醇的双苯异氰酸酯的聚合——晶型对固相聚合活性的影响

用激光Raman光谱研究了三种不同晶型的2,4-已二炔-1,6二醇的双苯异氰酸酯(HDPU)的聚合,发现不同晶型的HDPU的聚合活性与其C=C伸缩振动频率的频移之间存在内在联系。这说明单体晶格与聚合物晶格的匹配是HDPU具有高的聚合活性的必要条件。

如何申领和使用原产地证书Form E

在2010年10月29日越南河内举行的第十三次中国-东盟领导人会议上,我国商务部陈德铭部长与东盟各国经贸部长共同签署了《〈中国-东盟全面经济合作框架协议货物贸易协议〉第二议定书》（以下简称《第二议定书》）。该议定书于2011年1月1日起生效实施，

40Cr13环件径-轴向环轧工艺参数优化

结合客户订单中40Cr13环件的实际规格及技术要求,建立三维模型,在之前方式设置参数的基础上选取了环件初始轧制温度、驱动辊摩擦系数和驱动辊转速三个轧制工艺参数,通过数值模拟,并利用单一变量对其进行优化。实际验证结果表明:成品环件的精度和机械性能均比未优化参数下环轧的环件高。

自组装单层调控DL-天冬氨酸化合物晶体的晶型

降温时,外消旋的溶液中结晶析出DL天冬氨酸化合物晶体A。在L-半胱氨酸自组装单层(SAMs)模板诱导下,则可以获得DL-天冬氨酸化合物晶体B。在SAMs诱导作用下,不仅晶体的晶型发生了改变,晶体的形貌也从原来A型晶体的双锥柱状变成B型晶体的扁平双锥体。通过模拟L-半胱氨酸分子与DL-天冬氨酸晶面的相互作用,发现DL-天冬氨酸(001)面和(011)面与L-半胱氨酸分子的吸附能增加,降低了这两个面的聚集速度,从而提高其在晶体形貌中所占的比例。晶体晶型的改变也是因为在SAMs的作用下使沿着a轴方向的C_3-H_4键缩短造成晶胞参数a的减小导致晶型的改变。

New Crystalline Forms of Mebendazole with n-Alkyl Carboxylic Acids Neutral and Ionic Status

Structural information on the crystalline forms of mebendazole, an anti-parasitic drug, is limited, although three polymorphic forms of this drug have been reported. The present work investigates the structures and properties of different crystalline forms of mebendazole with a series of n-alkyl carboxylic acids, including trifluroacetic acid （1）, formic acid （2）, acetic acid （3）, propanoic acid （4）, butanoic acid （5）, valeric acid （6） and hexanoic acid （7）. These compounds were characterized by thermogravimetric analysis, IR spectra, as well as powder and single-crystal X-ray diffraction analysis. The R22（8） structural motif was detected in all the seven products, which was formed by a pair of N--H…O/O--H…N hydrogen bonds between mebendazole and carboxylic acid. Forms 3--7 were found to be neutral solvate, while in forms 1 and 2, proton transfer was observed from carboxylic acid to mebendazole.

DIENE POLYMERIZATION ACTIVE Nd-AI BIMETALLIC COMPLEX IN SINGLE CRYSTALLINE FORM

Since the discovery of Ziegler-Natta catalyst in the early 1950s, studies on its active centre structure has aroused much interest. The isolation of active species from homo-