聚乙二醇支载四分枝琥珀酰亚胺的合成

以分子量3 400的双羟基聚乙二醇(PEG)作为可溶性载体,与甲基磺酰氯反应得PEG支载的甲基磺酸酯,在碳酸铯的作用下,与5-羟基间苯二甲酸甲酯反应并在氢化铝锂作用下还原得PEG支载的四分枝羟基化合物,继续与丁二酸酐反应得到PEG支载的四分枝羧基化合物,在N-羟基琥珀酰亚胺作用下,制备结构新颖的功能基为琥珀酰亚胺的PE...     

聚乙二醇负载二醋酸碘苯试剂的制备及其参与“一锅法”合成2,5-二取代唑衍生物的研究

聚乙二醇(MW=4000)与3-碘苯甲酸在4-二甲胺基吡啶(DMAP)和N,N′-二环己基碳二亚胺(DCC)存在下于二氯甲烷溶剂中反应得到聚乙二醇负载3-碘苯甲酸酯,继而在醋酸介质中与四水过硼酸钠作用制得聚乙二醇负载的二醋酸碘苯试剂.在该试剂及三氟甲磺酸作用下,α-甲基芳酮和腈能以优良的产率一锅法生成2,5-二取代唑衍生物.同时,聚乙二醇支撑的二醋酸碘苯试剂在此反应中显示出较好的反应活性,反应条件温和,并且可循环使用,对环境友好.     

CFD simulation of fluidization quality in the three-dimensional fluidized bed

Multiphase computational fluid dynamics （CFD） has become an alternative method to experimental investigation for predicting the fluid dynamics in gas-solid fluidized beds. The model of Brandani and Zhang, which contains additional terms in both the gas- and solidphase momentum equations, is employed to explore homogeneous fluidization of Geldart type A particles and bubbling fluidization of Geldart type B particles in three-dimensional gas-fluidized beds. In this model, only a correlation for drag force is necessary to close the governing equations. Two kinds of solids, i.e., fine alumina powder （dp= 60 μm and pp = 1500 kg/m^3） and sand （dp = 610 μm and pp = 2500 kg/m^3）, are numerically simulated in a rectangular duct of 0.2 m （long） × 0.2 m （wide）× 0.5 m （high） size. The results show good agreement with the classic theory of Geldart.     

Effect of excessive Internet use on the time-frequency characteristic of EEG

We examined the effect of excessive Internet use on the time–frequency characteristic of the electroencephalogram by wavelet transformed and non-negative matrix factorization (NMF). The event-related potentials (ERP) of normal subjects and excessive Internet users were acquired using the oddball paradigm experiment. We applied the wavelet transformed and event-related spectral perturbation to ERP in order to extract the time–frequency values. The F-test statistics of time–frequency values were then decomposed into two components by NMF. Excessive Internet use resulted in a significant decrease in the P300 amplitudes (P < 0.05) and a significant increase in the P300 latency (P < 0.05) in all electrodes. The major effect of excessive Internet use on gamma oscillation occurred at 300 ms after stimuli at 40–50 Hz on the parietal central region. Thus, these data suggest that excessive Internet use affects information coding and integration in the brain.     

储量信息可视化技术研究与实现

储量信息是油气勘探、开发工作的重要成果,综合展示这些成果对地质综合研究人员有重要的指导作用。本文从探明储量的数据模型出发,用边界表示模型的方法,设计了多边形柱状模型来体现储量数据,并用Qt和C++结合Open Inventor三维可视化开发工具对上述模型进行了程序实现,实现了储量信息的人机交互以及三维展示功能,使地质研究人员和决策人员能够直观掌握区块的储量上报、动用等信息。     

Kinetic analysis and strain-compensated constitutive models of Ti-42.9Al-4.6Nb–2Cr during isothermal compression

The hot deformation behavior of Ti-42.9Al-4.6Nb–2Cr (at. %) was investigated by isothermal compression tests at the deformation temperature range of 1373–1573 K, strain rate range of 0.001–1.0 s⁻¹, up to the strain of 0.69. The flow stress test results of Ti-42.9Al-4.6Nb–2Cr showed negative temperature and positive strain rate sensitivity. Besides, strain had a great effect on the hot deformation behavior of Ti-42.9Al-4.6Nb–2Cr. Kinetic analysis was adopted to assess the hot workability of Ti-42.9Al-4.6Nb–2Cr via apparent activation energy (Q) of hot deformation, strain-rate sensitivity index (m) and strain hardening index (n). The Q value varied from 607.1 ± 0.7 kJ·mol⁻¹ to 512.6 ± 10.8 kJ mol⁻¹ with the increasing of strain from 0.1 to 0.6. The effect of strain on the Q value at the deformation temperatures below 1473 K was mainly related to dynamic recrystallization of γ phase and kinking of γ lamellae, while the Q value at the deformation temperature above 1473 K might be linked to γ→α phase transformation and DRV of α phase. Based on the kinetic analysis, strain-compensated Arrhenius model and Hensel-Spittel model were successfully established to predict the hot workability (flow stress). Average absolute relative errors of established strain-compensated Arrhenius model and Hensel-Spittel model were 7.52% and 11.95%, respectively. Moreover, both established constitutive models can be extrapolated for predicting the flow stress of Ti-42.9Al-4.6Nb–2Cr to larger strain levels.     

Mangosteen peel-derived activated carbon for supercapacitors

This work reports the effects of activation temperatures on the porous development and electrochemical performance of activated carbons. Herein, activated carbons were prepared from the biowaste of mangosteen peel by using KOH activation at temperatures of 400, 600, and 800 ?°C. The results demonstrate that the specific surface area increases with increasing the activation temperatures in which the well-developed porous structure after KOH activation at 800 ?°C provides the highest specific surface area of 1039 ?m² ?g^?1. At 600 ?°C, the activated carbon delivers the highest specific capacitance value of 182 ?F ?g^?1 ?at a current density of 0.5 ?A ?g^?1 in 3 ?M KOH aqueous electrolyte. This is correlated well with its high micropore fractions (99%). Moreover, it was found that the activation temperature changes the major contribution of oxygen-containing functional group on surface of activated carbon, which is beneficial for the enhancement of the specific capacitance value of activated carbon at the temperature of 600 ?°C. This work suggests that the activation temperature is a key to optimizing the electrochemical performance of activated carbons. Overall, our activated carbons can be considered as a strong candidate for use as electrode materials in supercapacitors.     

NADH诱导的牛心肌线粒体的脂质过氧化

在ＡＤＰ－Ｆｅ３＋存在下，ＮＡＤＨ可诱导牛心肌线粒体发生脂质过氧化作用．以丙二醛的生成量来衡量脂质过氧化水平，研究ＮＡＤＨ，ＡＤＰ，Ｆｅ３＋及反应时间对线粒体脂质过氧化的影响     

基于正交多项式密度函数的CT图像分割方法

通过构建面向CT图像数据的非参数正交多项式密度模型, 解决了带有先验性质的参数化方法不能对复杂医学图像做出合适地描述, 从而导致实际物理模型与假设模型间存在较大差异的问题, 即模型不匹配的问题. 在形成的多峰函数基础上采用改进的粒子群优化算法, 依据启发式优化搜索策略实现多峰优化, 先寻找多个局部最优解, 再以局部最优解为聚类中心实现图像分割. 通过模拟数据和真实CT图像数据的仿真, 证明了基于正交多项式密度函数图像分割算法的有效性.     

Sulfoalkyl ether β-cyclodextrin derivatives synthesized by a single step method as pharmaceutical biomaterials

We report a simple ＂one pot＂ single step method to synthesize sulfoalkyl ether β-cyclodextrin （β-CD） derivatives in aqueous solution, which avoids the limitations associated with commonly used organic synthesis of such derivatives including multi-step reactions, use of expensive, toxic, and often environmentally hazardous organic solvents and/or reagents. Using this method, we obtained sulfopropyl and sulfobutyl ethyl β-CDs. We characterized these two derivatives and evaluated their ability to enhance solubility of fluconazole, a commonly used antifungal drug with poor water solubility. Experimental results indicate that these derivatives are structurally analogous to some of the commercially available β-CD derivatives. More importantly, when they formed supramolecular inclusion complexes with fluconazole, they demonstrated similar, if not better, capacity to enhance fluconazole solubility compared with commercially available β-CD derivatives, suggesting that the simple ＂one pot＂ single step synthesis may provide an effective alternative approach to produce large quantity of β-CD derivatives as pharmaceutical biomaterials for medicinal applications.     

土地利用变化对阜平流域的径流影响研究

选取不同年份Landsat遥感卫星图像,分析了阜平流域土地利用变化;以SWAT模型为工具,利用1968-2010年的水文气象资料,针对土地利用情况研究土地利用变化对流域径流的影响。结果表明,近几十年来,多年降水量变化不显著,而径流量呈显著下降趋势;流域林地增加(草地转林地)是径流减少的主要原因,从1993年的926 km2增加到2004年的1 119 km2,径流量减少6.46%;不同情景下模拟的多年平均流量总体呈现减少的趋势;林地的增加和草地的减少能够导致径流的减少;林地和草地的变化通过影响蒸散发量影响水文循环;径流量的变化趋势与蒸散发量相反。     

烟酰胺辅酶NADH新型模型物的合成与表征

烟酰胺辅酶NADH的新型模型物BNAH和9-苯基占吨(9-PhXnH)在药物的绿色合成中显示越来越重要.本文分别以烟酰胺和9-苯基占吨醇为原料合成了辅酶NADH重要模型物BNAH和9-苯基占吨,该合成路线原料易得,反应条件温和,操作简单,产率高,产品纯度高,并通过核磁共振氢谱、元素分析、紫外等分析手段,对BNAH和9-苯基占吨进行了结构表征.     

Effects of heat treatment on microstructure and mechanical properties of SLMed Sc-modified AlSi10Mg alloy

The influence of heat treatments on the microstructures and mechanical properties of the selective laser melting manufactured AlSi10Mg alloy modified with Sc was systematically investigated. The results showed that the addition of Sc element introduced primary Al₃ Sc, which increased the heterogeneous nucleation during the solidification of AlSi10Mg alloy, and then the ultrafine network eutectic structure was obtained, and hence the tensile strength was improved significantly(nearly 2...     

Extraction of methyl red from industrial wastewater using xylene as an extractant

A laboratory study on the liquid–liquid extraction system has been carried out for the removal and recovery of methyl red from aqueous solutions using xylene as an extractant. The concentration of methyl red has been studied in the range of 1.72 × 10⁻⁴ to 1.72 × 10⁻³ mol L⁻¹. The efficiency of dye extraction increased with increasing time of extraction. Distribution ratio is reasonably high (D = 49) even in the presence of inorganic salts. Extracted dye in the organic phase has been stripped into sodium hydroxide solution. The organic solvent is reused for reextraction of the dye from aqueous solution. The efficiency of reused organic solvent was maintained up to 10 runs. Loading capacity of dye has been found to be 14.32 mg. Under optimized conditions, real textile wastewater has been studied and the results are satisfactory.     

Highly stable N-containing polymer-based Fe/Nx/C electrocatalyst for alkaline anion exchange membrane fuel cell applications

A cost-effective electrocatalyst with high activity and stability was developed. The Fe-Nx and pyridinic-N active sites were embedded in nitrogen-doped mesoporous carbon nanomaterial by carbonization at high temperature. The electrocatalyst exhibited excellent electrochemical performance for the oxygen reduction reaction, with high onset potential and half-wave potential values (E_onset = 1.10 ?V and E_1/2 ?= ?0.944 ?V) than 20 ?wt % Pt/C catalyst (1.04 and 0.910 ?V). The mass activity of the Schiff base network (SNW) based SNW-Fe/N/C@800° electrocatalyst (0.64 ?mA ?mg^?1 @ 1 ?V) reached about half of the commercial Pt/C electrocatalyst (1.35 ?mA ?mg^?1 @ 1 ?V). The electrocatalyst followed the 4-electron transfer mechanism due to very low hydrogen peroxide yield (H₂O₂ ?< ?1.5%) was obtained. In addition, this electrocatalyst with dual active sites showed high stability during cyclic voltammetry and chronoamperometry measurements. More importantly, the electrocatalyst also demonstrated the power density of 266 ?mW ?cm^?2 in the alkaline anions exchange membrane fuel cell (AEMFC) test, indicating its prospective application for fuel cells.     

Cell Toxicity Effect of Cadmium on Yeast Cells by Detecting NADH Autofluorescence

The cytotoxic effect of cadmium is studied by detecting intracellular nicotinamide adenine dinucleotidea（NADH） autofluorescence in this work. NADH autofluorescence in processes of cadmium-induced apoptosis, necrosis and reversible injury are recorded timely. The relativity between time course of NADH autofluorescence and cadmium toxicity is established. The cell toxicity effect of Cadmium on yeast cells is studied by detecting the time courses of intracellular reduced NADH autofluorescence in this work. The relativity between time courses of NADH autofluorescence and Cadmium toxicity is established.     

Physical quantity synergy in laminar flow field of convective heat transfer and analysis of heat transfer enhancement

Based on the principle of field synergy for heat transfer enhancement, the concept of physical quantity synergy in the laminar flow field is proposed in the present study according to the physical mechanism of convective heat transfer between fluid and tube wall. The synergy regulation among physical quantities of fluid particle is revealed by establishing formulas reflecting the relation between synergy angles and heat transfer enhancement. The physical nature of enhancing heat transfer and reducing flow resistance, which is directly associated with synergy angles α,β,γ,φ,θ and ψ; is also explained. Besides, the principle of synergy among physical quantities is numerically verified by the calculation of heat transfer and flow in a thin cylinder-interpolated tube, which may guide the optimum design for better heat transfer unit and high-efficiency heat exchanger.     

Near-microscopic grain boundary facilitates fatigue crack propagation in a polycrystalline Al–Zn–Mg–Cu alloy

In present study, grain characteristics with sizes within 10–30 μm were fabricated from a same Al–Zn–Mg–Cu alloy, FCP behaviors of the alloys with small grain(SG alloy), medium grain(MG alloy) and large grain(LG alloy)were investigated and related fatigue fracture morphology was analyzed. With the enhancement of stress intensity factor range(ΔK), the alloy with larger grains possessed faster FCP rate, which were successively arranged as SG alloy > MG alloy > LG alloy at initial stage while...     

Effect of Zr addition on the stability of precipitated Laves phase and mechanical properties of Fe–Cr–Al-based alloys at high temperatures

The effect of a small amount of Zr addition on the temperature-dependent stability of Laves phase particles and mechanical properties of Fe-13.5Cr-4.73Al-2.07Mo-(0.34–0.5)Nb-(0.65–0.98)Ta-(0–0.33)Zr (wt. %) ferritic alloys was investigated in the present study. The designed alloy ingots were hot-rolled, aged at 1073 ?K for 24 ?h, and then re-treated at 1273 ?K, 1323 ?K, 1373 ?K, and 1473 ?K for 1 ?h, respectively. It was found that the Zr addition could not only stabilize the Fe₂M Laves phase (M ?= ?Mo,Nb,Ta,Zr) to a much higher temperature, but also induce the formation of stable Fe₂₃Zr₆ phase. The high-temperature (HT) microstructural stability of the alloys significantly was improved, as evidenced by the fact that a certain amount (0.66–1.19%) of precipitates (Fe₂M, Fe₂₃Zr₆, and core(Fe₂₃Zr₆)-shell(Fe₂M)-structured particles) with an appropriate size (～1.0 ?μm) uniformly distributed in the ferritic matrix even after being re-treated at 1473 ?K. Particularly, the formation of core-shell-structured particles at HTs was studied from the viewpoint of both solid solubility and diffusion coefficient of M in the matrix. All these aged alloys exhibited prominent mechanical properties at both room and elevated temperatures, showing high yield strength with σ_YS ?= ?490–560 ?MPa at room-temperature and σ_YS ?= ?80–85 ?MPa at 1073 ?K. The strengthening effect was further discussed in light of various strengthening mechanisms, and the calculated strength are in good agreement with the experimental results.