Heats of Combustion and Formation of Trimethylborane,Triethylborane, and Tri-n-butylborane

The heats of combustion at 25 °C of trimethylborane (liquid), triethylborane (liquid), and tri-n-butylborane (liquid), to form crystalline boric acid, liquid water, and gaseous carbon dioxide have been determined to be −2989.4 ±22.4 kj/mole (−714.48 ±5.36 kcal/mole), −4975.6 ±15.1 kj/mole (−1189.2 ±3.6 kcal/mole), and −8901.0 ±10.2 kj/mole (−2127.4 ±2.4 kcal/mole), respectively. These data, combined with the heats of formation of boric acid, carbon dioxide, and water give −34.79 ±5.40, −47.2 ±3.7, and −83.2 ±2.5 kcal/mole at 25 °C for the standard heats of formation of trimethylborane, triethylborane, and tri-n-butylborane, respectively. The data of other investigators are discussed briefly.     

Heats of Hydrolysis and Formation of Dimethoxychloroborane

The heat of hydrolysis of dimethoxychloroborane has been measured; for the reaction, (CH3O)2BCl(liq)+3H2O(liq)=H3BO3(c)+2CH3OH(liq)+HCl(g)ΔH(25°C)=−26.6±0.8kj/mole=−6.4±0.2kcal/mole.From this, we have calculated the heat of formation of dimethoxychloroborane: for the liquid, ΔHf° (25 °C) = −782.1 ± 1.8 kj/mole (−186.9±0.4 kcal/mole), and for the gas, ΔHf° (25 °C) = −747.9 ±2.2 kj/mole (−178.8±0.5 kcal/mole).     

Heats of Hydrolysis and Formation of Potassium Borohydride

The heat of reaction of potassium borohydride with 0.060 molal HCl has been measured by solution calorimetry. The heat of solution of the hydrolysis products has also been measured and combined with certain literature values to calculate the process: KBH4(c)+HCl(g)+3H2O(liq)→KCl(c)+H3BO3(c)+4H2(g),ΔH°(25°C)=−354.06±1.84kj/mole(−84.62±0.44kcal/mole).A combination of this value with literature values for the heats of formation of HCl(g), H₂O(liq), KCl(c), and H₃BO₃(c) gives for KBH₄(c): ΔHf°(25°C) = ?228.86 ± 2.30 kj/mole(?54.70 ± 0.55 kcal/mole).Other data on the heats of formation of the alkali-metal borohydrides are discussed briefly.     

Heats of Formation of Lithium Perchlorate,Ammonium Perchlorate,and Sodium Perchlorate

Calorimetric measurements of the heats of solution of LiClO₄(c), NH₄ClO₄(e), and NaClO₄(c) have been made. The results have been combined with the heats of formation of KClO₄(c), KCl(c), LiCl(c), NH₄Cl(c), and NaCl(c), to obtain the following heats of formation: LiClO4(c),ΔHf°(25°C)=−380.27±1.21kj/mole=−90.89±0.29kcal/mole,NH4ClO4(c),=−295.98±1.35kj/mole=−70.74±0.32kcal/mole,NaClO4(c),=−382.75±0.93kj/mole=−91.48±0.22kcal/mole.A brief summary of other recent data has been included.     

Local Dissipation Phenomena in Crystalline Forms of Boron

A classification is proposed for dissipation (in particular, relaxation) processes in crystalline systems and inorganic materials. The concepts of modifying and aggregation subsystems are defined. Relations are derived for determining the temperature dependences of the local quasi-viscous dissipation parameter r _iand the local quasi-elastic parameter K _ifor each relaxation transition in the tan (T) spectrum.     

Closed-Space Thermolysis of Hydrous Crystalline Polyantimonic Acid

Unlike the air calcination of Sb₂O₅ · 2H₂O and Sb₂O₅ · 0.2H₂O, which gives only pyrochlore phases up to 840°C, the thermolysis of these hydrates in an autoclave at 400–500°C, under elevated pressures of gaseous products (oxygen and water vapor), yields Sb₆O₁₃ and anhydrous antimony pentoxide with a hexagonal structure (a = 1.342 nm, c= 0.671 nm), which is stable in air up to 710°C.     

Ketorolac Tromethamine Bioavailability Via Tablet, Capsule, and Oral Solution Dosage Forms

The single-dose mean pharmacokinetic characteristics and relative bioavailability of 10-mg ketorolac tromethamine tablet, capsule, and oral solution dosage forms were evaluated in 12 healthy volunteers in a randomized study of Latin square design. The tablet and the capsule formulations used were shown to have similar in vitro dissolution profiles. Ketorolac tromethamine was rapidly absorbed from all three dosage forms. The tablet and capsule were not significantly different with respect to any of the mean pharmacokinetic parameters: time to maximum plasma concentration (T_max) (35 and 42 min for the tablet and capsule, respectively), peak plasma concentration (C_max) (0.865 and 0.809 μg/ml for the tablet and capsule, respectively), area under the curve (AUC) (3.50 and 3.43 μg/ml × hr for the tablet and capsule, respectively), and half-life (t1/2) (5.2 and 4.8 hr for the tablet and capsule, respectively). Ninety-five percent fiducial (confidence) limits supported the equivalence of all of the tablet and capsule pharmacokinetic characteristics except for T^max, because of the higher variability of this parameter. The solution was absorbed significantly faster than the tablet (the time to maximum plasma concentration was 23 min for the solution versus 35 min for the tablet), but was not significantly different from the tablet in any other pharmacokinetic aspect. The fiducial intervals supported these tablet versus solution findings. Therefore, when functional or anatomical abnormality make tablet administration inadvisable, the solution or capsule formulations employed in this study may be used as alternatives to the commercially marketed tablet without adversely impacting the absorption profile of the drug substance.     

晶型及化学成分对SiC粉体氧化性能的影响

研究粒度标号为W2.5和W10、晶型为3C和6H的3C-W2.5、3CW10、6H-W2.5、6H-W10这4种SiC粉体的氧化性能,通过同步热分析仪讨论4种粉体在30~1 400℃时的非等温氧化特性,采用X射线衍射和扫描电子显微镜对氧化前、后粉体的物相和表面性质进行表征。结果表明:起始氧化温度从高到低的SiC粉体依次为3C-W10、6H-W2.5、6H-W10、3CW2.5,与其化学成分中SiO2相对含量由大到小的关系相一致;在相同实验条件下,高温氧化后同一晶型的粉体粒度标号为W2.5的质量变化大于W10的,粒度相同时,3C-SiC的质量变化小于6H-SiC的;加热至1 400℃后,SiC晶体表面有玻璃状SiO2生成。     

三种有机物对LY12CZ铝合金在酸性溶液中的缓蚀行为研究

本工作选取了2-巯基苯并噻唑(MBIH)、苯并三氮唑(BTA)和8-羟基喹啉(8Q)等几种典型的缓蚀剂,研究了其对LY12CZ铝合金在酸性溶液中的缓蚀效果及机理.通过腐蚀失重法研究了三种缓蚀剂对LY12CZ铝合金在酸性溶液中腐蚀动力学的影响.利用光学显微镜(OM)、场发射扫描电子显微镜(FE-SEM)及能谱(EDS)等...     

晶态过渡金属氧化物介孔材料的合成进展

过渡金属氧化物介孔材料是继介孔氧化硅之后引起广泛关注的研究热点,而晶态时过渡金属氧化物介孔材料的性质及广泛应用起着决定性的作用.从合成角度综述了硬模板和软模板法制备有序晶态过渡金属氧化物介孔材料的研究进展,并且展望了介孔材料的发展趋势.硬模板法制备的介孔材料比软模板法有更好的有序性,而软模板法合成过程简便,有更好的工业应用前景,但需解决材料的有序介孔结构热稳定性差的难题.     

Single‐Crystalline Nanobelts Composed of Transition Metal Ditellurides

Following the celebrated discovery of graphene, considerable attention has been directed toward the rich spectrum of properties offered by van der Waals crystals. However, studies have been largely limited to their 2D properties due to lack of 1D structures. Here, the growth of high‐yield, single‐crystalline 1D nanobelts composed of transition metal ditellurides at low temperatures (T ≤ 500 °C) and in short reaction times (t ≤ 10 min) via the use of tellurium‐rich eutectic metal alloys is reported. The synthesized semimetallic 1D products are highly pure, stoichiometric, structurally uniform, and free of defects, resulting in high electrical performances. Furthermore, complete compositional tuning of the ternary ditelluride nanobelts is achieved with suppressed phase separation, applicable to the creation of unprecedented low‐dimensional materials/devices. This approach may inspire new growth/fabrication strategies of 1D layered nanostructures, which may offer unique properties that are not available in other materials.     

对当代标志形式的3种未稳定状态的探讨

目的 探讨关系美学的未稳定形式状态对当代标志设计的影响,从而对当代标志设计形式理论作出积极的探索和尝试.方法 采用文献调查法、案例分析法、对比分析法、认知示意等研究方法.结果 从关系美学角度对典型的艺术作品分析入手,探讨了未稳定状态的三种典型形式特征:多元化形式、间歇性表达、模糊化认知.通过分析当代艺术作品的典型形式,解读了当代标志设计的形式特征,并根据探讨的理论作出了相应的设计实践.结论 将关系美学的未稳定状态理论从抽象的美学领域迁移到商业设计领域,从理论上是对当代标志设计理论的积极探索,设计师可以利用关系美学中未稳定状态的理论分析标志设计的表现形式,也可以合理制造各种良性的关系形式,更加有效地进行视觉表达.     

3种合金在80℃H2SO4和H2SO4-HNO3溶液中的腐蚀行为

化工装置常用316L合金、804合金和Hastelloy C合金制造,使用过程中常接触65%～85%H2SO4溶液和65%～85%H2SO4与少量HNO3的混合液。采用静态挂片试验和电化学方法研究了这3种合金在80℃,72%H2SO4溶液和80℃,72%H2SO4+0.1%HNO3混合溶液中的腐蚀行为。结果表明:在80℃,72%H2SO4溶液中,804合金的耐蚀性优于Hastelloy C合金,316L的耐蚀性最差;在80℃,72%H2SO4+0.1%HNO3溶液中,804合金的耐蚀性优于316L,Hastelloy C合金的耐蚀性最差。     

低温化学法合成单晶氧化锌纳米带

用低温化学溶液法在100℃制备了非层状结构的单晶ZnO纳米带。在反应初期先形成层状结构的碱式醋酸锌(Zn(OH)_(2-x)(CH_3COO)_x nH_2O)前驱体,然后在水热条件下使其转化成单晶ZnO纳米带。用透射电子显微镜(TEM)、场发射扫描电子显微镜(FESEM)、X射线衍射(XRD)、高分辨透射电子显微镜(HRTEM)和荧光光谱(PL)对ZnO纳米带的形态、结构和光学性质进行了表征.结果表明,在上述反应中醋酸根阴离子和弱有机碱六次甲基四胺(HMT)对前驱体和ZnO纳米带的形成起了关键作用。     

Formation and Characterization of Ceramic Nanocomposite Crystalline Coatings on Aluminium by Anodization

Ceramic nanocomposite coatings have been synthesized on aluminium by using lithium sulphate electrolyte with zirconium silicate additive by anodization.The effects of current density(CD) on microhardness,structure, composition and surface topography of the oxide layer formed at various CDs(0.1-0.25 A/cm~2) have been studied.Crystalline coatings formed at 0.25 A/cm~2 have been(width 95 nm) observed with a relatively uniform distribution confirmed by scanning electron microscopy.Additionally,the average microhardness value of ceramic nanocomposite coatings fabricated from lithium sulphate—zirconium silicate bath is approximately 8.5 times higher than that of the as-received aluminium.The surface statistics of the coatings is discussed in detail to explain the roughness and related parameters for better understanding.These observations demonstrate the importance of surface statistics in controlling the morphology of the coatings and its properties.From the X-ray diffraction investigations,it can be concluded that the formed nanocomposite coatings are crystalline in nature and that the crystallinity of the coatings decreases with increasing applied current density.     

含羧酸与胆甾基元的硅氧烷类聚合物的液晶性能

合成了液晶单体4-烯丙氧基苯甲酸胆甾醇酯(Mch)和单体4-十一烯酸苯甲酸(Mc),通过硅氢加成反应得到了系列侧链液晶聚合物P0~P5。通过差示扫描量热(DSC)、偏光显微镜(POM)、旋光分析等手段对聚合物的液晶性能和相行为进行了表征,结果表明,含羧基的单体Mc(P1~P5)与不含羧基的单体Mc(P0)的聚合物相比,玻璃化转变温度(Tg)、比旋光度和清亮点(Ti)均明显降低,但是没有改变原聚合物的胆甾相类型;随Mc在液晶聚合物中摩尔百分数的增加,Tg继续降低,而Ti升高。Mc的引入拓宽了液晶聚合物的介晶区间。     

含酒石酸基元的液晶单体及其聚合物的合成与表征

合成了一种以酒石酸为中心的新型工字型液晶单体2,3-二乙酰氧基-1,4-丁二酸对烯丙氧基苯甲酸对苯二酚酯(M1),将其与手性液晶单体4-烯丙氧基苯甲酸胆甾醇酯(M2)共聚,得到侧链液晶聚合物P1～P8。通过红外光谱(FT-IR)、核磁共振(1H-NMR)、偏光显微镜(POM)、差示扫描量热分析(DSC)和X射线衍射(XRD)等手段对所获单体及聚合物的结构和液晶相行为进行了表征。结果表明,液晶单体M1具有近晶相扇形、纹影织构,手性单体M2具有胆甾相油丝织构。聚合物P1～P8出现胆甾相的Grandjean织构,随着单体M1含量的增加,聚合物P1～P8的Tg呈上升趋势,液晶区间变窄。     

Particle Formation from Solution and Slurry Sprays

ABSTRACT

The initial morphology of particles formed by spray drying or spray pyrolsis of solutions, sols or slurries, is determined by the relative velocity between the atomized droplet and the ambient gas in the furnace. A1 high relative velocities, the droplet can be disintegrated or flattened, whereas at low relative velocities the droplet remains spherical throughout the drying process. The time for respheroidization depends on the liquid properties and the solid content of the drying droplet. When the droplet reaches the percolation limit, the higher viscosity inhibits respheroidization, and the morphology of the deformed droplet is fixed. A new model based on the Weber number, percolation criteria, and the drying kinetics, is presented to predict particle morphology for various drying conditions. In addition, the effects of segregation during drying will be discussed in regard to its effect on particle formation during spray formulation. We will show how physical and chemical segregation processes occur in drying droplets, and how these segregation processes can be controlled to yield particles of designed morphology and internal phase distribution.