Ultrasonic absorption studies in some solutions of carboxylic-acids in dioxan

Ultrasonic absorption studies are carried out in carboxylic acid-dioxan mixtures for various concentrations at 30±0.1°C. The measured absorption is much higher than the classical absorption. The excess absorption initially increases with increase of carboxylic acid concentration, attains a maximum and then decreases with further increase in concentration. The related parameters such as volume viscosity, relaxation time and free energy difference between the two states (ΔF) have also been calculated. The results can be explained satisfactorily using Hall’s two-state model.     

金溶胶中邻羟基苯甲酸吸附行为的密度泛函理论与实验研究

研究了邻羟基苯甲酸(OHBA)的常规拉曼散射(NRS)光谱以及其吸附在Au纳米颗粒上的表面增强拉曼散射(SERS)光谱。以氯金酸为原料,柠檬酸三钠为还原剂,用化学还原法制备了球形的金纳米粒子溶胶,采用激光显微拉曼光谱仪(激发波长为785 nm),测定OHBA分子的NRS光谱及其吸附在Au纳米颗粒上的SERS光谱。同时,应用密度泛函理论(DFT),在B3LYP/6-31+G**(C,H,O)/LANL2DZ(Au)水平上,对OHBA分子进行了结构优化,在此基础上计算了OHBA分子的NRS光谱以及其吸附在Au纳米颗粒上两种不同吸附构型下的SERS光谱,并和实验值进行比较。结果表明,OHBA分子通过羧基吸附构型的计算值比通过羟基吸附构型的计算值与实验值符合的更好。最后,利用GaussView可视化软件对其振动模式进行了全面归属。通过对邻羟基苯甲酸分子拉曼谱峰的详细指认能够得出：Au溶胶中的邻羟基苯甲酸分子,是通过羧基倾斜地吸附在Au纳米颗粒表面的。可视化软件直观形象地展示出了该分子的结构特征和分子基团振动情况,对其振动峰位的归属提供了重要依据。本文工作对推进邻羟基苯甲酸在生物医药等领域进一步的应用具有重要作用。     

Dielectric relaxation of benzophenone and some of its derivatives in the liquid state part II: Benzophenone, 2,4-dihydroxybenzophenone and p-rosolic acid in DMSO or acetone solution

The dynamic dielectric properties of the title solutions have been measured between 20 MHz and 36 GHz at 20 °C. In addition to spectral components due to the relaxation of solute and solvent as found in similar manner for other binary polar-polar systems, a low frequency feature is observed which is weak for benzophenone but intense for both the derivatives. It can be ascribed to solvent molecules forming a loose salvation shell, where their tumbling motion is slowed down.     

Oxidizing effects of high temperature annealing in reducing atmosphere in Ca-doped YIG films

The existence of an oxidation mechanism is reported in Ca-doped YIG films, when high temperature annealing is carried out in N₂ atmosphere. The annealing were performed at successively increasing temperatures, and optical absorption, lattice parameter and thermoelectric power were measured at each step. Optical absorption was observed going down to a minimum (T = 450°C in one cycle of annealing, T = 400°C in a different cycle) and then rise again. The minimum in absorption corresponds to a maximum of the lattice parameter, while the thermoelectric power is always p-type. Analysis of the data leads to the conclusion that we are observing a reoxidation process, triggered both by temperature and oxygen vacancy concentration. This process is subject to exhaustion. Previous annealing experiments are analyzed in the light of these results.     

Supramolecular structural control and characteristics of p-hydroxybenzoate intercalated hydrotalcite

p-Hydroxybenzoate pillared layered double hydroxides with different Zn/Al mole ratios have been prepared by three different methods: rehydration of calcined LDH precursor, coprecipitation and anion exchange. The products have been characterized by several experimental techniques: PXRD, FT-IR, TG-DTA and UV-vis. PXRD patterns show that the interlayer distance of p-hydroxybenzoic acid (PHBA)-Zn/Al-LDH varies with ratio Zn/Al, from 14.8 to 15.3 Å, indicating that altering Zn/Al ratios can change the arrangement of the intercalated PHBA anions. Not only do infrared spectra display the characteristic absorption of both the PHBA anion and the Zn/Al layer, but also provide further evidence of the interaction between these two parts. Thermal analysis confirms that the intercalation can make PHBA stable up to 434 °C, which is 213 °C higher than that for pure PHBA. By UV-vis it is found that such a product can control blocking of UV radiation in a wider range of wavelength.     

低密度溶液中溶剂的重组织性质

分析了溶液的微观结构 ,结果表明 ,单个溶质粒子影响其周围的溶剂的结构 ,溶质粒子间的相互作用也将影响溶剂的结构 ,溶质对溶剂结构的影响称作溶剂的重组织 .提出了二阶重组织能及二阶重组织熵等概念 ,可以描述在两个溶质粒子发生碰撞时对其周围溶剂结构的影响 .利用二元系的集团展开理论 ,给出了溶剂的一阶、二阶重组织能和重组织熵的表达式 .统计热力学分析给出了溶剂 溶剂径向分布函数与溶质和溶剂化学势之间的关系 ,给出了无限稀溶液模型是否成立的宏观判据 .提出的理论可用于低密度的二元溶液 .     

Effect of Zn substitution for Co on the transport properties of Y BaCo4O7

Electrical resistivity and Seebeck coefficients of Y BaCo_4−xZn_xO₇ (x=0.0,0.5,1.0,2.0) were investigated in the temperature range 350-1000 K. It was found that the electrical resistivity and activation energy increase with increasing Zn concentration, while Seebeck coefficients do not increase but decrease when electrical resistivity increases. We explained the increase of electrical resistivity and the drop of Seebeck coefficients for Zn-substituted samples by the decrease of carrier mobility, rather than of carrier concentration. The effect of oxygen absorption and desorption on the electrical resistivity and Seebeck coefficients was also investigated. An abrupt change of transport properties happens at about 650 K for x=0.0 and 0.5 samples measured in oxygen. For x=1.0 and 2.0 samples, however, such change disappears and the transport behavior in oxygen is almost same as that in nitrogen due to the significant suppression of oxygen diffusion caused by the higher Zn concentration in these samples.     

Ultrasonic spectroscopy in bovine serum albumin solutions

Ultrasonic absorption and velocity spectra in bovine serum albumin (BSA) aqueous solutions have been measured at 20 degrees C over the broad frequency range 0.1-1600 MHz in the pH range 1.5-13.2. Five different techniques were used: the plano-concave resonator, plano-plano resonator, pulse-echo overlap, Bragg reflection, and high-resolution Bragg reflection methods. The absorption spectrum at neutral pH was well fitted to the relaxation curve assuming a distribution of relaxation frequency with a high-frequency cutoff and long low-frequency tail. The relaxation behavior was interpreted in terms of various degrees of hydration of BSA molecules. At acid pH's, excess absorption over that at pH 7 was explained by double relaxation. The pH dependences of the relaxation frequency and maximum absorption per wavelength showed that the relaxation at about 200 kHz was related to the expansion of molecules and that at 2 MHz resulted from the proton transfer reaction of carboxyl group. At alkaline pH's, the excess absorption was explained by triple relaxation. The relaxation at about 200 kHz was associated with a helix-coil transition, and the two relaxations at 2 and 15 MHz were attributed to the proton transfer reactions of phenolic and amino groups, respectively. The rate constants and volume changes associated with these processes were estimated.     

Spectroscopic Investigation on the Synergistic Effects of Ultrasound and Dioxopromethazine Hydrochloride on Protein

The bovine serum albumin (BSA) was selected as a target molecule, the sonodynamic damage to protein in the presence of dioxopromethazine hydrochloride (DPZ) and its mechanism were studied by means of absorption and fluorescence spectra. The results of hyperchromic effect of absorption spectra and quenching of intrinsic fluorescence spectra indicated that the synergistic effects of ultrasound and DPZ could induce the damage of BSA molecules. The damage degree of BSA molecules increased with the increase of ultrasonic irradiation time and DPZ concentration. The results of synchronous fluorescence and three-dimensional fluorescence spectra further confirmed that the synergistic effects of ultrasound and DPZ induced the damage of BSA molecules. The results of oxidation-extraction photometry with several reactive oxygen species (ROS) scavengers indicated that the damage of BSA molecules could be mainly due to the generation of ROS, in which both ¹O₂ and ·OH were the important mediators of the ultrasound-inducing BSA molecules damage in the presence of DPZ.     

Ultrasound absorption studies in the critical region of lithium-ammonia solutions

Measurement of the absorption of ultrasound in the critical region of lithium-ammonia solutions as a function of concentration, frequency, and temperature are presented. The absorption reaches a maximum at 4.2 mole percent lithium and is a function of the frequency. The frequency dependence can be explained either by a single relaxation at around 20 MHz or by using Fixman's theory with a correlation length of 51.3 Å.     

Microwave absorption of oxygen measured with a Fabry-Perot spectrometer

A Fabry-Perot interferometer in the semiconfocal configuration has been used as a microwave spectrometer by the method of Q-reduction. The Q can be determined with conventional laboratory equipment to within 2% accuracy, corresponding to 0.3 dB/km at 58.82 GHz. Absolute of pure oxygen and dry air at fixed frequencies has been measured as a function of pressure from 0 to 1 atm at room temperature. The measured absorption of dry air can be explained if the overlap of the oxygen lines is properly taken into account.     

WMS的玻璃药瓶内氧气含量检测及其标定方法改进

应用激光波长调制光谱(WMS)技术,建立了一种开放光路短光程检测玻璃药瓶内氧气含量的方法。选择氧气分子位于760.885(13 142.58 cm-1)的吸收谱线,通过多次调试优化了系统相关参数,给出了实时扣背景及实时谱线校正等数据处理的方法和步骤。采集七种不同氧气含量的玻璃药瓶样本,获取相应的二次谐波信号,分别建立二次谐波峰值、半高谱峰面积与浓度的线性回归方程进行定量预测。实验结果表明,其拟合系数分别为0.996 6和0.997 8,后者相比前者的标定方法提高了0.12%。采用完全交互验证的方法来评价两个模型的预测精度,其预测的均方根误差(RMSEP)分别是0.003 1和0.002 0,后者相比前者降低了37.69%。对浓度是4%的气体样品,比较不同时间的20次测量结果,标准差分别为0.002 2和0.001 6,后者相比前者降低了27.3%,同时其测量灵敏度分别为0.198%和0.097%,后者相比前者的灵敏度提高了约51%。证明了该系统及数据处理方法对玻璃药瓶内氧气含量检测是可行的,且利用半高谱峰面积更丰富的幅值信息来反演气体浓度可以降低波峰失真影响,检测精度更高,稳定性更好。     

Spectroscopic investigation on the sonodynamic damage to proteins in the presence of berberine in vitro

In this paper, bovine serum albumin (BSA) was selected as a target molecule, and the sonodynamic damage to proteins in the presence of berberine (BER) and its mechanism were studied by means of absorption and fluorescence spectra. The results of hyperchromic effect of absorption spectra, and quenching of intrinsic fluorescence spectra indicated that the ultrasound-induced BSA molecules damage was enhanced by BER. The damage degree of BSA molecules increased with the increase in ultrasonic irradiation time and BER concentration. The results of synchronous fluorescence and three-dimensional fluorescence spectra confirmed that the synergistic effects of ultrasound and BER induced the damage of BSA molecules. The results of oxidation-extraction photometry with several reactive oxygen species (ROS) scavengers indicated that the damage of BSA molecules could be mainly due to the generation of ROS, and ¹O₂ was the major mediator of the ultrasound-induced BSA molecules damage in the presence of BER.     

Absorption spectra of photosensitized human fat tissue

We study experimentally the optical characteristics of adipose tissue in vitro in its dye sensitization—by indocyanin green and brilliant green. We conducted experiments on a PerkinElmer Lambda 950 spectrophotometer in the spectral range of 250–900 nm. From an analysis of the measured absorption spectra, we determine the shifts in the maximum of the absorption band for the studied photosensitizers in adipose tissue in comparison to their spectra in solutions. These shifts are explained by the bonding of photosensitizer molecules with the protein matrix of adipose tissue. We find the relative monomer and dimer concentrations of dye molecules in solutions and stained samples.     

Solute-solvent interaction in liquids

The infrared absorption spectra of HCl and DCl in dilute CCl₄ have been recorded over a range of temperatures. The band shapes have been analysed using the method of moments, allowing both the rms torque and rms force acting on the solute to be determined as functions of temperature. It is shown that rotation-translation coupling makes a significant contribution to the dynamics of these polar molecules in solution.     

Thermodynamic and statistical studies of supersaturated ternary solutions

The influence of chromium ions Cr3+ on properties of supersaturated aqueous solution of ammonium sulfate (NH4)2SO4 has been studied employing containerless electrodynamic levitation of single microdroplets of this solution with known concentration of Cr3+ ions. The water activity versus solute concentration was measured in three different sets of experiments corresponding to different initial concentrations of Cr3+ ions. Theoretical treatment of the experimental results obtained is developed employing the theory of supersaturated electrolyte solutions [Phys. Rev. E 52, 1325 (1995)]. This treatment has allowed the following two conclusions. First, spinodal concentration is a decreasing function of Cr3+ concentration. Second, solute clusters formed in the presence of Cr3+ ions demonstrate complex behavior with respect to binding water molecules: (a) at low and moderate supersaturations, they bind more water molecules than clusters formed in the absence of an impurity; and (b) at high supersaturations, they bind less water molecules than clusters formed in the absence of an impurity.     

光度法研究溴酚蓝与牛血清白蛋白的结合反应

用分光光度法研究了溴酚蓝(BPB)与牛血清白蛋白(BSA)在酸性条件下结合反应的吸收光谱,探讨了结合反应机理、结合模型以及影响结合参数的一些因素。认为溴酚蓝和牛血清白蛋白主要通过静电引力作用,结合反应符合Pesavento提出的相分配模型。并探讨了溶液的酸度、染料浓度、离子强度、表面活性剂对结合反应的影响。     

塑料闪烁体基质到溶质的能量传递

本文研究了以聚苯乙烯为基质,添加具有不同光谱荧光性质溶质的二元塑料闪烁体的发光.测量了闪烁体的激发光谱,荧光光谱,γ射线,X射线和紫外线激发的相对发光强度及其与溶质浓度的关系,测量了聚苯乙烯吸收波长和溶质吸收波长激发下的发光衰减及其与溶质浓度的关系.讨论了基质到溶质的能量传递机制.     

Luminescence of multicomponent phosphate glasses with manganese

The emission spectra both of fluorescence at room temperature and at 520 K and of thermostimulated luminescence (TSL) of multicomponent alumino-phosphate glasses with various Mn concentration (0·2–20mol%) has been measured. The colour of fluorescence and TSL changes from orange to yellow with increasing temperature at constant concentration of Mn and from yellow to red with increasing concentration at constant temperature. The colour shift with temperature can be explained by means of decreasing field strength, Dq with increasing distance Mn-O. The intensity of orange fluorescence at R.T. increases with increasing concentration up to about 5% Mn and then decreases in consequence of concentration quenching. On the contrary, the TSL intensity reaches its maximum at concentraction of about one order of magnitude smaller. The different behaviour of fluorescence and TSL intensity in dependence on Mn is probably due to their different elementar mechanisms.