Mechanism and dynamic study of reactive red X-3B dye degradation by ultrasonic-assisted ozone oxidation process

The effectiveness of ozone combined with ultrasound techniques in degrading reactive red X-3B is evaluated. A comparison among ozone (O₃), ultrasonic (US), ozone/ultrasonic (O₃/US) for degradation of reactive red X-3B has been performed. Results show that O₃/US system was the most effective and the optimally synergetic factor reaches to 1.42 in O₃/US system. The cavitation of ultrasound plays an important role during the degradation process. It is found that 99.2% of dye is degraded within 6 min of reaction at the initial concentration of 100 mg·L⁻¹, pH of 6.52, ozone flux of 40 L·h⁻¹ and ultrasonic intensity of 200 W·L⁻¹. Ozonation reactions in conjunction with sonolysis indicate that the decomposition followed pseudo-first-order reaction kinetics but the degradation efficiencies are affected by operating conditions, particularly initial pH and ultrasonic intensity. A kinetic model is established based on the reaction corresponding to operational parameters. In addition, the main reaction intermediates, such as p-benzoquinone, catechol, hydroquinone, phthalic anhydride and phthalic acid, are separated and identified using GC/MS and a possible degradation pathway is proposed during the O₃/US process.     

NO dissociation pathways on Rh(1 0 0), (1 1 0), and (1 1 1) surfaces: A comparative density functional theory study

The chemisorption and dissociation pathways of NO on the Rh(1 0 0), (1 1 0), and (1 1 1) surfaces are studied by the plane-wave density functional theory (DFT) with CASTEP program. In addition, the electronic and geometrical effects that affect the NO dissociation reactions have been investigated in detail. The calculation results are presented as following: The effective activation energies of the best NO dissociation pathways on the Rh(1 0 0), the Rh(1 1 0), and the Rh(1 1 1) are 0.63, 0.66 and 1.77 eV, respectively. The activity of the Rh planes for NO dissociation is in the order of Rh(1 0 0) ≈ Rh(1 1 0) > Rh(1 1 1). The low dissociation barrier for Rh(1 0 0) and Rh(1 1 0) is associated with the existence of a lying-down NO structure which acts as a precursor for dissociation. By Mulliken population analysis and structure analysis, both electronic and geometrical effects are found to affect the NO dissociation reactions, but the geometrical effect exceed the electronic. The energy decomposition scheme has been used to provide further insight into the NO dissociation reactions. Based on the calculations, the interaction energy between N and O in the transition state on the Rh(1 1 1) is found much larger than that on the Rh(1 0 0) and the Rh(1 1 0). The major differences of should originate from the variation of the bonding competition effect.     

蛋白质空间结构的实验技术和理论方法

文章主要介绍几种蛋白质空间结构的实验测定方法，在现代生物学研究中，最常用的方法包括X射线晶体学、二维核磁共振（2D-NMR）和低温冷冻电镜，近几年发展起来的单分子技术在生物大分子动态结构的研究中应用越来越多，这些方法都有它们特定的时间和空间分辨率，所测定的结构及其动力学受环境热运动涨落的影响也非常不同，文章对这些问题作了较详细的分析，在蛋白质结构的理论方法方面，介绍了一个新的折叠理论及其与现有折叠模型的关系．讨论了模拟计算在研究蛋白质构象变化和动力学方面的应用，同时强调了分子动力学和蒙特卡罗方法．指出粗粒化模型是研究的热点之一，对生物学中经常遇到的多长度多时问尺度问题提供了一个可行的解决方案。     

大鼠脑组织含磷代谢物随年龄变化的NMR研究

随着人口老龄化的不断加剧,衰老相关疾病已成为全球关注的问题.神经系统功能的退行性改变居于衰老相关疾病的首位,其机制尚不明了.该文旨在通过核磁共振磷谱(~(31)P NMR)检测不同月龄大鼠脑组织中小分子物质的改变,明确能量相关的含磷化合物随大鼠年龄增长的变化,从而揭示脑组织中年龄相关代谢物的变化规律.该研究萃取了不同年龄(幼年、中年及老年)Sprague-Dawley(SD)大鼠脑组织中的小分子物质,进行了~(31)P NMR检测分析.结果显示:老年大鼠脑组织中能量代谢相关物质——磷酸肌酸的含量显著升高,而磷脂酰胆碱及磷酸肌醇含量显著降低,并且出现了磷酸化葡萄糖.这一发现有助于理解衰老相关的脑结构和功能下调,为神经退行性疾病的发生提供依据.     

NO(3+1)共振增强的多光子离化谱

用皮秒脉冲高功率Nd∶YAG激光器抽运的光学参量发生/放大器作激发源,获得了NO分子在420～500 nm波长范围内的多光子离化谱,光谱图呈现分离谱的特征,表明在该波长区间NO分子以多光子共振方式离化。离化信号随激光强度的近四次方变化关系表明,在420～500 nm波长范围内NO分子吸收4个光子而离化。通过对谱线的标识,首次分离出NO分子以E 2Σ激发电子态为中间共振态的(3+1)多光子离化光谱序列,由谱线序列峰值波长得到NO分子E 2Σ电子态的振动常数,从而实现了采用多光子离化技术对该态能级结构的实验研究。     

Theoretical kinetic study on the decomposition of 1,5‐diaminotetrazole

1,5‐Daminotetrazole (DAT) is of much interest because of the practical significance and the diversity of characteristics. The study on the decomposition pathway and the kinetics of DAT has been performed based on the quantum chemistry theory. The minimum energy path (MEP) calculation has shown that NH₂N₃ and NH₂CN are the initially detected products of DAT. And the structures of reactant, products and transition state were optimized with MP2 methods using 6‐311G** basis sets, and the energies were refined using CCSD(T)/6‐311G** levels of theory. The calculated rate constants were obtained using the conventional transition‐state theory (TST) and the canonical variational transition‐state theory (CVT) methods. The calculation results indicated that the energy barrier of decomposition reaction is 47.98 kcal mol^?1 and the variational effect is small. In addition, the rate constants and the Arrhenius experience formula of DAT decomposition have been obtained between 200 and 2500 K temperature regions. The fitted three‐parameter expressions calculated using the TST and CVT methods are (TST) and (CVT). This work may provide the theoretical support for further experimental synthesis and testing. Copyright © 2015 John Wiley & Sons, Ltd.     

超光滑加工的后置处理算法研究

为了精确控制超光滑加工过程中磨头的运动轨迹,从而实现光学元件材料去除的均匀稳定,研究了超光滑加工的后置处理算法。分析了超光滑加工工艺的特点和相应的超光滑机床的机械结构,建立了机床的坐标系统,构造了机床的运动学模型。对于光学元件母线为任意平面曲线的情况,研究了磨头运动轨迹的等误差直线逼近算法。在曲率半径为290mm,相对口径为1∶2.9的凹球面上进行了超光滑加工实验。结果表明,利用所述算法可以精确地控制磨头的运动轨迹,从而保证材料去除的稳定性。     

Bio-energetic impairment in human calf muscle in thyroid disorders: a P MRS study

Mitochondrial metabolism particularly oxidative phosphorylation is greatly influenced by thyroid hormones. Earlier studies have described neuromuscular symptoms as well as impaired muscle metabolism in hypothyroid and hyperthyroid patients. In this study, we intend to look in to the muscle bioenergetics including phosphocreatine recovery kinetics based oxidative metabolism in thyroid dysfunction using in vivo ³¹P nuclear magnetic resonance spectroscopy (MRS). ³¹P MRS was carried out at resting state on 32 hypothyroid, 10 hyperthyroid patients and 25 control subjects. Nine out of 32 hypothyroid patients and 17 out of 25 control subjects under went exercise protocol for oxidative metabolism study and performed plantar flexion exercise while lying supine in 1.5 T magnetic resonance scanner using custom built exercise device. MRS measurements of inorganic phosphate (Pi), phosphocreatine (PCr), phosphodiesters (PDE) and adenosine triphosphate (ATP) of the calf muscle were acquired during rest, exercise and recovery phase. PCr recovery rate constant (k_PCr) and oxidative capacity were calculated by monoexponential fit of PCr versus time (t) at the beginning of recovery. During resting condition in hypothyroid patients, PCr/Pi ratio was reduced whereas PDE/ATP and Pi/ATP were increased. However, in case of hyperthyroidism, an increased PCr/Pi ratio and reduced PDE/ATP and Pi/ATP were observed. The results confirmed differential energy status of the muscle due to increased or decreased levels of thyroid hormone. Our results also demonstrate reduced oxidative metabolism in hypothyroid patients based on PCr recovery kinetics. PCr recovery kinetics study after exercise revealed decreased PCr recovery rate constant (k_PCr) in hypothyroid patients compared to controls that resulted in decrease in oxidative capacity of muscle by 50% in hypothyroids. These findings are consistent with a defect of high energy phosphate mitochondrial metabolism in thyroid dysfunction.     

Use of hyperpolarized [1-C]pyruvate and [2-C]pyruvate to probe the effects of the anticancer agent dichloroacetate on mitochondrial metabolism in vivo in the normal rat

Development of hyperpolarized technology utilizing dynamic nuclear polarization has enabled the measurement of ¹³C metabolism in vivo at very high signal-to-noise ratio (SNR). In vivo mitochondrial metabolism can, in principle, be monitored with pyruvate, which is catalyzed to acetyl-CoA via pyruvate dehydrogenase (PDH). The purpose of this work was to determine whether the compound sodium dichloroacetate (DCA) could aid the study of mitochondrial metabolism with hyperpolarized pyruvate. DCA stimulates PDH by inhibiting its inhibitor, pyruvate dehydrogenase kinase. In this work, hyperpolarized [1-¹³C]pyruvate and [2-¹³C]pyruvate were used to probe mitochondrial metabolism in normal rats. Increased conversion to bicarbonate (+ 181±69%, P=.025) was measured when [1-¹³C]pyruvate was injected after DCA administration, and increased glutamate (+ 74±23%, P=.004), acetoacetate (+ 504±281%, P=.009) and acetylcarnitine (+ 377±157%, P=.003) were detected when [2-¹³C]pyruvate was used.     

Data for scaling-up hydrothermal waste water treatment process

Abstract

Hydrothermal oxidation of wastes is developed as an alternative technique in order to limit the toxic end-product formation, the waste volume and the energy supply. We are now working on the transfer of this technology, and so on the determination of data for scaling-up the hydrothermal oxidation process. The main data concern the knowledge of reactive pathway, the determination of reaction kinetic and thermal parameter. Kinetic and thermal data have been determined for the hydrothermal oxidation of acetic acid as well as the reactive pathway of hydrothermal oxidation of a C, H, O, N compound, the fenuron (C₆H₅-NH-CO-N(CH₃)₂).