非等温等蒸气压法及其在Pt-Zn相关系研究中的应用

非等温等蒸气压法具有集样品制备、活度测定和相关系研究为一体的特点,本文简要阐述了非等温等蒸气压法的实验原理,分析了活度实验测定的误差以及非等温等蒸气压法在合金热力学和相关系研究中的应用,并讨论了相图十分不完善的Pt-Zn二元系的相关系.     

A cyclopenta-fused dibenzo[b,d]thiophene-co-phenanthrene macrocyclic tetraradicaloid

A cyclopenta-fused macrocyclic tetraradicaloid, MC4-S, containing alternating phenanthrene (Phen) and dibenzo[b,d]thiophene (DBTh) units was synthesized and isolated in single-crystal form. Compared with its all-carbon isoelectronic structure, CPTP-M, the incorporation of two sulfur atoms leads to a smaller radical character and a larger singlet–triplet energy gap. X-ray crystallographic analysis reveals that the spin–spin coupling through the DBTh unit is stronger than that through the Phen moiety. In addition, the electron-rich sulfur atoms also raise the energies of both the HOMO and LUMO in MC4-S, but the overall optical and electronic energy gaps are close to that of the CPTP-M. MC4-S displays global anti-aromaticity according to the NMR measurements and theoretical calculations (NICS, ACID and 2D ICSS), with a 36π ring current circuit along the all-carbon periphery excluding the two sulphur atoms. Its dication becomes globally aromatic due to the existence of a dominant 34π-conjugation pathway. This study sheds some light on the effect of heteroatoms on the electronic properties of open-shell polyradicaloids.

The first member of sulfur-heterocycloarene neutral tetraradicaloids, MC4-S, was synthesized in crystalline form, which displays strong global anti-aromaticity and unique properties.     

Effect of magnetic field on electroosmotic flow of viscoelastic fluids in a microchannel

Electroosmotic flow is an efficient transportation technology driven by applying an external electric field across the microchannel, which has a great potential for future application. This work is presented to study the unsteady electroosmotic flow of viscoelastic fluids combined with a constant pressure gradient and a vertical magnetic field through a parallel plate microchannel. For the reason that the upper and bottom walls of the parallel plate microchannel in microfluidic devices can be made of different materials, this leads to different hydrophobic properties, asymmetric zeta wall potentials, and different slip boundary conditions. The Navier slip model with different slip coefficients at walls is considered. The generalized Maxwell fluid with fractional derivative is adopted for the constitutive equation of the fluid. The analytical and numerical solutions of velocity are derived by employing the integral transform method and finite difference method, respectively. Excellent agreement is found between the numerical solutions and analytical solutions. Finally, the effects of fractional parameter , relaxation time , slip coefficients and , the ratio of wall zeta potentials , Hartmann number , and electrical field strength parameter on velocity profiles are interpreted graphically in detail.     

Oxidation of Cyclohexene Catalyzed by PAMAM—SA—M Dendrimers

Oxidation of cyclohexene under 1 atmospheric pressure of molecular oxygen at 70℃ in the absence of solvent catalyzed by PAMAM-SA-M(Where PAMAM=polyamidoamine;SA=salicyaldehyde;M=metal ions Fe^3 ,Co^2 ,Ni^2 ,Mn^2 ,Cu^2 ,Zn^2 ,respectively) dendrimers, afforded 2-cyclohexen-1-ol 1,2-cyclohexen-1-one 2,7-oxabicyclo [4,1,0] heptane 3 and 7-oxabicyl [4,1,0] heptan-2-one 4 as the major products. The factors that affect this reaction are also discussed.     

具有包藏结构的三元聚丙烯纳米复合材料结构与性能关系的研究

制备了一种新型聚丙烯 丁苯橡胶 纳米碳酸钙三元纳米复合材料 .研究结果显示 ,复合材料中的大多数纳米碳酸钙粒子被包藏在丁苯橡胶中 ,并与之共同形成分散于聚丙烯树脂中的分散相 ,这种聚丙烯纳米复合材料具有高刚性、高韧性、高耐热性和高的结晶速率 .系统研究了成核剂苯甲酸钠的加入和纳米碳酸钙的用量对该类纳米复合材料相态结构、结晶形态和结晶动力学的影响 ,以及具有包藏结构的分散相粒径和PP中β晶含量对材料性能的影响 .结果表明 ,苯甲酸钠的加入和纳米碳酸钙用量的提高均可使体系中分散相粒径减小 ,结晶速率加快 ,进而使材料的韧性、刚性和耐热性提高 .     

Simultaneous determination of trace arsenic(III), antimony(III), total arsenic and antimony in Chinese medicinal herbs by hydride generation-double channel atomic fluorescence spectrometry

A new method was developed for simultaneous determination of trace arsenic and antimony in Chinese herbal medicines by hydride generation-double channel atomic fluorescence spectrometry with a Soxhlet extraction system and an n-octanol-water extraction system, respectively. The effects of analytical conditions on the fluorescence intensity were investigated and optimized. A water-dissolving and methanol-water-dissolving capability were compared. The contents of different species in five Chinese herbal medicines and their decoctions were analyzed. The concentration ratios of n-octanol-soluble As or Sb to water-soluble As or Sb were related to the kinds of medicine and the acidity of the decoction. Soxhlet extraction was found to be an effective method for plants pretreatment for determination of arsenic and antimony species in Chinese herbs; the interferences of coexisting ions were evaluated. The proposed method has the advantages of simple operation, high sensitivity and high speed, with 3σ detection limits of 0.094 μg g⁻¹ for As(III), 0.056 μg g⁻¹ for total As, 0.063 μg g⁻¹ for Sb(III) and 0.019 μg g⁻¹ for total Sb in a 1.0 g of the sample.     

Hydrothermal synthesis of hierarchical SnO2 nanomaterials for high-efficiency detection of pesticide residue

Acephate pesticide contamination in agricultural production has caused serious human health problems. Metal oxide semiconductor (MOS) gas sensor can be used as a portable and promising alternative tool for efficiently detection of acephate. In this study, hierarchical assembled SnO₂ nanosphere, SnO₂ hollow nanosphere and SnO₂ nanoflower were synthesized respectively as high efficiency sensing materials to build rapid and selective acephate pesticide residues sensors. The morphologies of different SnO₂ 3D nanostructures were characterized by various material characterization technology. The sensitive performance test results of the 3D SnO₂ nanomaterials towards acephate show that hollow nanosphere SnO₂ based sensor displayed preferable sensitivity, selectivity, and rapid response (9 s) properties toward acephate at the optimal working temperature (300 °C). This SnO₂ hollow nanosphere based gas sensor represents a useful tool for simple and highly effective monitoring of acephate pesticide residues in food and environment. According to the characterization results, particularly Brunauer-Emmett-Teller (BET) and Ultraviolet-Visible Spectroscopy (UV–vis), the obvious and fast response can be attributed to the mesoporous hollow nanosphere structure and appropriate band gap of SnO₂ hollow nanosphere.     

About the special topic of mechanics and biomimetics of biomaterials and animal locomotion

Scientists have increasingly been turning their attentions to searching for inspirations from the splendid living world in order to solve various challenging problems of technologically importance. Rapid advances in observation techniques and computational ability will make it a reality to understand, at different time and space scales, the functions,     

The effect of non-Kolmogorov turbulence on the propagation of cosh-Gaussian beam

The propagation of cosh-Gaussian beam in turbulence with different power spectral density of refractive index is investigated. By using the expansion of mutual coherence function in Taylor series, analytical expression for the average intensity is presented. With the help of this expression, the intensity profiles with different parameters are analyzed. Relative errors of the analytical expression are studied, and the effects of power spectral density on beam spreading and evolvement are discussed in details. It shows that the analytical expression should provide reasonable approximations to study the propagation of cosh-Gaussian in non-Obukhov-Kolmogorov turbulence.     

超声辅助提取-液相色谱-串联质谱法同时测定油料作物中6种新型乙酰乳酸合成酶抑制剂类除草剂残留

将超声辅助提取与液相色谱-质谱联用技术相结合,建立了油料作物中6种新型乙酰乳酸合成酶（ALS）抑制剂类除草剂（甲基二磺隆、氯吡嘧磺、双草醚、嘧草醚、嘧苯胺磺隆和乙氧嘧磺隆）的痕量多残留检测技术。比较了超声辅助提取和QuEChERS提取2种方法对6种除草剂的提取回收率,并根据净化效果和吸附作用对十八烷基键合硅胶吸附剂（C18）、乙二胺-N-丙基硅烷（PSA）、石墨化炭黑（GCB）、弗罗里硅土（Florisil）和增强型基质去除吸附剂（EMR）5种吸附材料进行优化。结果表明,超声辅助提取可使6种化合物的提取回收率在90.0%以上,EMR对6种化合物的吸附作用较小,且可有效去除油脂干扰,减小基质效应。6种除草剂在0.05~500.0 μg/L范围内具有良好的线性,相关系数均大于0.9984。该方法检出限和定量限分别为0.08~0.8 μg/kg和0.25~2.5 μg/kg。6种化合物在油菜籽、大豆、花生米和葵花籽4种基质中3个加标水平下的加标回收率为70.7%~103.8%,相对标准偏差为0.8%~9.2%,可应用于油料作物中6种ALS抑制剂类除草剂的同时测定。