酸洗污泥与煤共燃烧过程中重金属的迁移分布研究

采用高温管式炉系统进行酸洗污泥与煤共燃烧实验。对共燃烧后As、Cr、Ni、Cd、Cu、Mn、Pb、Zn、Sb、Se重金属元素在烟气、飞灰及炉渣中的分配率进行分析。结果表明,Cd、Se、Zn是易挥发重金属,主要分布在烟气和飞灰中。Cd在烟气中的最大分配率为61%;Se在烟气中的分配率为38.58%~94.612%;Zn在低、高温段分别主要分布在烟气和飞灰中。As、Cu、Pb、Sb是半挥发重金属,Pb在炉渣中的分配率较稳定,分配率为42.67%~64.76%,在烟气和飞灰中的分配率波动较大,其分配率分别是14.176%~45.79%和9.78%~32.55%;Sb在烟气中的最大分配率为37.64%;温度升高反而会抑制As、Cu挥发,这与高温下As、Cu易与矿物质反应生成络合物有关。Ni、Cr、Mn属于难挥发重金属,绝大部分残留在炉渣中,且分配率对温度变化不敏感。赋存于炉渣中的Cr、Ni分别超过95%和97%;随着温度升高,Mn在炉渣中的分配率由71.46%增加到96.89%。     

Basic Principles of Protease-Catalyzed Peptide Bond Formation

The stereospecific formation of peptide bonds under mild conditions and without side reactions is still a formidable task in peptide synthesis. One approach that springs to mind, namely the use of the naturally occurring catalyst involved in the biosynthesis of proteins, the ribosomal peptidyl transferase, cannot be realized in practice. The fact, however, that the natural cleavage of proteins is carried out by other enzymes, namely the proteases, together with the reversibility of these cleavage reactions in principle, has led to an interesting synthetic concept. Proteases normally catalyze the enzymatic degradation of proteins and peptides by hydrolytic cleavage of the peptide bond in an exergonic reaction. The use of physicochemical principles in order to influence the equilibrium, the concentration of products, and the kinetic parameters of the reaction results in the successful application of the catalytic properties of proteases to peptide synthesis. The purpose of this review is to describe and summarize the methods used in such approaches and to attempt a systematic categorization. The principles are applied to the synthesis of such practically relevant products as aspartame and human insulin.     

Enthalpies of solvation of alkylated uracils in water,nonaqueous and mixed solvents

The enthalpies of solution of uracil and its alkylated derivatives in water, methanol, N,N-dimethylformamide (DMF) and water+DMF mixtures were measured at 25°C. The enthalpies of solvation were determined. The enthalpies of cavity formation, corresponding to the enthalpies of solvent-solvent interactions were calculated and the enthalpies of solute-solvent interactions were obtained. The presence of the alkyl groups was found to have different effects on the enthalpy of interaction depending on the position and size of the substitution. The effect of alkylation at the nonpolar side of the uracil ring was found to arise mostly from the enhancement of the van der Waals interactions. The alkyl substitutions at the polar side resulted also in the removal of the solvent molecules interacting specifically with the polar groups of uracil. The enthalpy of those specific interactions was determined and found to be stronger in methanol and DMF than in water. Enthalpies of solvation in the binary water+DMF solvent were found to depend in a nonlinear way on the solvent composition. The nonlinearities in the water-rich region were found to arise from the decay of the hydrophobic hydration of the solutes with the increasing DMF content. The substitution of two methyl groups caused the uracil molecule to bahave as a predominantly hydrophobic solute. The nonlinearities in the DMF-rich region were found only for those solutes which can form hydrogen bonds with DMF.     

Catalytic carbophilic activation: catalysis by platinum and gold pi acids

The ability of platinum and gold catalysts to effect powerful atom-economic transformations has led to a marked increase in their utilization. The quite remarkable correlation of their catalytic behavior with the available structural data, coordination chemistry, and organometallic reactivity patterns, including relativistic effects, allows the underlying principles of catalytic carbophilic activation by pi acids to be formulated. The spectrum of reactivity extends beyond their utility as catalytic and benign alternatives to conventional stoichiometric pi acids. The resulting reactivity profile allows this entire field of catalysis to be rationalized, and brings together the apparently disparate electrophilic metal carbene and nonclassical carbocation explanations. The advances in coupling, cycloisomerization, and structural reorganization--from the design of new transformations to the improvement to known reactions--are highlighted in this Review. The application of platinum- and gold-catalyzed transformations in natural product synthesis is also discussed.     

Detection of Vibrational Spectroscopic Biomarkers of the Effect of Gold Nanoparticles on Wheat Seedlings Using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy

The aim of this study is to evaluate the biochemical changes in the leaves of wheat seedlings exposed to gold nanoparticles (AuNPs) nondestructively and rapidly using attenuated total reflectance Fourier transform infrared spectroscopy and laser-induced fluorescence. The 18?nm size gold nanoparticles are synthesized by citrate reduction. For analyzing the effect of gold nanoparticles on wheat seedlings, the treatment of gold nanoparticles was applied to the seedlings through roots and following the spectroscopic measurement of biochemical signatures. The laser-induced fluorescence measurement has been performed to access the effect of gold nanoparticles on the chlorophyll concentration of wheat seedlings. The decrease in the fluorescence intensity and the fluorescence intensity ratio on the treatment of gold nanoparticles indicates increase in the concentration of chlorophyll in the leaves of wheat seedlings. The attenuated total reflectance Fourier transform infrarred spectroscopy in combination with principal component analysis has been used to visualize the biochemical changes in the cellulose, hemicellulose, pectin, lignin, amino acids, proteins, and lipid of the leaves of wheat seedlings by recording infrared spectra in the region from 4000 to 400?cm^?1. Principal component analysis applied to the preprocessed infrared data clearly distinguishes the spectral variability between control and gold nanoparticle treated seedlings. The study shows that exposure of gold nanoparticles increases the concentrations of cellulose, hemicelluloses, pectin, and lignin in the leaves of wheat seedlings. The increase in these chemicals indicates the modulation of cell walls of the wheat seedlings by the gold nanoparticle treatment. The exposure to gold nanoparticles also enhances the expression of lipid and proteins in the leaves of wheat seedlings.     

Self-Healing Molecular Biology for Microbial Concrete: A Review

The most extensively utilized material in construction is concrete, decreasing life of structure pointing toward loses in structural health. The crack is the major problem faced in the concrete construction. This causes the corrosion in the steel reinforcement. The structure gets deteriorated with the developing cracks; therefore need the proper attention toward this problem. The present work consists of the different self-healing techniques used by the researchers to inhibit the crack and prevent further deterioration in the structure. The self-healing mechanism proves advantageous in use of natural fibers to inhibit the corrosion process, to increase compressive strength, and to decrease water absorption is present in this study. The maximum strength increased and the width of crack get healed with the help of these techniques is also mentioned in the study.     

两种产地的沉香药材及水煎液中6种矿物质元素的分布特征比较

采用火焰原子吸收光谱法(FAAS)测定了两产地(海南、云南)沉香药材中的Zn、Fe、Cu、Mn、Ca和Mg6种矿物质元素的含量。根据样品中矿物质的含量计算矿物质在日服用量下的"中国营养素参考值百分比"(矿物质NRV%),然后绘制日服用量下矿物质NRV标准化分布模式图。结果表明,海南产和云南产沉香中各矿物质元素的含量及矿物质NRV标准化分布模式图都有明显差异。海南产沉香中Ca、Mg、Mn的含量分别约是云南产沉香中Ca、Mg、Mn的2倍,而云南产沉香中Fe的含量约是海南产沉香的4.6倍。海南沉香的原药和水煎液中均以Mn的NRV%最高;云南沉香原药以Fe的NRV%最高,水煎液以Mn的NRV%最高。     

The uncertainty in the calculation of the amount of blocked and reactive lysine in milk products,as determined by the furosine method

The measurement uncertainty in the calculation of the amount of blocked and reactive lysine (as determined by the furosine method) was evaluated according to the procedure described in the Eurachem/CITAC guide. The analytical method involves the chromatographic determination of lysine and furosine after acid hydrolysis. The calculation of blocked and reactive lysine in the initial protein is based on known conversion factors. The estimation of the uncertainty was performed in two steps: (1) determination of the uncertainty in the chromatographic determination of lysine and furosine, and (2) determination of the uncertainty in the calculation of blocked and reactive lysine. The individual contributions to the final uncertainty were identified, quantified, and combined in uncertainty budgets. The largest contribution to the calculation of blocked lysine came from estimating the conversion factor of blocked lysine into furosine during acid hydrolysis. For the calculation of reactive lysine, the main contribution came from the chromatographic determination of lysine. The uncertainty estimates were compared to available validation data (in-house and collaborative standard deviations of reproducibility).     

Simultaneous quantification of five biogenic amines based on LC–MS/MS and its application in honeybee venom from different subspecies

The use of honeybee venom in traditional medicine is increasing due to its unexpected beneficial effects in the treatment of diseases. In this study, a simple and environmentally friendly sample preparation procedure was developed to quantify five biogenic amines—histamine, 5-hydroxytryptamine, dopamine, adrenaline, and noradrenaline—in honeybee venom using high-performance liquid chromatography tandem mass spectrometry. The instrument and sample preparation method were optimized to achieve stable, sensitive, and accurate quantification of the five biogenic amines. The peak purities of five biogenic amines in bee venom were examined using a diode array detector to ensure that endogenous impurities will not interfere with biogenic amines during the chromatographic separation procedure. The correlation coefficient of each compound was higher than 0.998 in the range of 0.5–1000 ng/mL. The limits of detection and quantification of the developed method ranged between 0.09 and 0.17, and 0.3 and 0.59 μg/g, respectively. The average recoveries of spiked biogenic amines with different concentrations were higher than 70.95%, and the intra- and intermediate-day precisions were lower than 7.51% and 10.17%, respectively. The carry-over between each injection and the stability of the target analytes were also evaluated to ensure the effectiveness of this method. The data obtained are presented in various formats, including boxplot, heat map, and principal component analysis diagram, to visualize the differences in the biogenic amine contents of the honeybee venoms from different subspecies. This method hopes to provide the opportunity to distinguish the bee venom produced by different subspecies.     

小波包分析用于重叠分析化学信号的处理

对小波包分析的算法进行了改进,并将此算法成功地应用于多组分重叠色谱信号的解析.结果表明,本文提出的算法解决了MRSD算法的不足,更适合处理分析化学信号,用于重叠信号的解析时不需重构(逆变换),简化了数据处理步骤,加快了数据解析速度,具有较强的解析能力.对于重叠色谱信号的解析,小波包分析比小波分析具有更强的解析能力.     

Improvement of extraction capability of magnetic molecularly imprinted polymer beads in aqueous media via dual-phase solvent system

In this study, a novel and simple dual-phase solvent system for the improvement of extraction capability of magnetic molecularly imprinted polymer (MIP) beads in aqueous sample was proposed. The method integrated MIP extraction and micro-liquid-liquid extraction (micro-LLE) into only one step. A magnetic MIP beads using atrazine as template was synthesized, and was applied to aqueous media by adding micro-volume of n-hexane to form a co-extraction system. The magnetic MIP beads preferred to suspend in the organic phase, which shielded them from the disturbance of water molecule. The target analytes in the water sample was extracted into the organic phase by micro-LLE and then further bound to the solid-phase of magnetic MIP beads. The beads specificity was significantly improved with the imprinting efficiency of template increasing from 0.5 to 4.4, as compared with that in pure aqueous media. The extraction capacity, equilibration process and cross-selectivity of the MIP dual-phase solvent extraction system were investigated.The proposed method coupled with high-performance liquid chromatography was applied to the analysis of atrazine, simazine, propazine, simetryn, prometryne, ametryn and terbutryn in complicated sample such as tomato, strawberry juice and milk. The method is selective, sensitive and low organic solvent-consuming, and has potential to broaden the range of MIP application in biological and environmental sample.     

The effect of dose on light-sensitivity of radicals in alanine EPR dosimeters

In this work we present a study of light-induced effects on free radicals and their transformations in gamma-irradiated pure L-alanine and in commercially available alanine detectors: rods, pellets and films. Samples irradiated to doses from 2 Gy to 4000 kGy were exposed to light from a fluorescent lamp and to ordinary daylight. The observed changes in EPR spectra of the samples were analyzed with regard to their intensity and shape. The shape analysis was based on numerical decomposition of the measured spectra into model spectra reflecting contributions of R1, R2 and R3 radical populations in the samples. The illumination of alanine dosimeters resulted in significant decrease of the central EPR line and was accompanied by distinct variations in the shape of EPR spectra. The rate of light-induced decay in spectra amplitude was found to be dependent on dose of ionizing radiation--the sensitivity to light was decreasing with increase in dose in all detectors in the 2-5x10(5) Gy dose range. The exposure of gamma-irradiated (to 300 Gy) alanine to normal, diffused daylight resulted in decay of the signal amplitude at rate about 0.5% per week. It was shown that decay in the R1 component was responsible for the observed reduction of the spectra amplitude. The observed increase in R2 contributions in samples exposed to light confirmed a hypothesis of R-->R2 radical transformations promoted by visible light. The reported effects indicate a necessity of protection of irradiated dosimeters from their prolonged exposure to light.     

Chemical and thermal analysis of the biopolymers in thyme (Thymus vulgaris)

Thyme (Thymus vulgaris) has been known, long time ago, for its aromatic properties. It contains essential oils and polymers such as cellulose (mixture of hemicellulose and cellulose) and lignin. The thyme, studied in this work, was gathered from the same place, in the period from November 1999 to October 2000. The chemical analysis (water, total ash, essential oils, extractive substances, cellulose, holocellulose and lignin) can be used roughly in the characterisation of the four periods that correspond to the four seasons of the year. The cellulose level was found to be more than lignin level in the wet periods (growth of the plant). The opposite was found in the dry periods. The total ash and essential oil levels were found to be high during the period of high pluviometry. The thermal decomposition of cellulose and holocellulose was found to fit well with the first-order kinetics. The activation energy, under air flow, was 185 and 196 kJ mol⁻¹ for cellulose and holocellulose, respectively. The maximum decomposition rate and thermal analysis heating rate of lignin were found to have a direct linear relationship.     

Explicit finite difference simulations for accelerating cross diffusion flow over a perpendicular shield with parabolic motion

The heat transfer phenomenon subject to thermos-diffusion effects convey important applications in the heating processes, extrusion systems, chemical processes and various engineering systems. The objective of current work is to observe the contribution of Soret and Dufour effects in oscillating shield for cross diffusion flow. The perpendicular shield with oscillating motion induced the flow. The magnitude of oscillations is assumed to be small so that laminar flow due to oscillating shield has been resulted. The motivations for addressing the thermos-diffusion phenomenon due to oscillating of shield are due to applications in oscillatory pumps, moving surface, metal detectors, power systems etc. The dimensionless problem is obtained via introducing the appropriate set of variables. The numerical outcomes are suggested by using the most interesting explicit finite difference scheme. The physical illustration for flow parameters is presented. Moreover, the aspect of physical quantities involving the flow are graphically reported.     

Study of the degradation of a new PLA braided biomaterial in buffer phosphate saline,basic and acid media,intended for the regeneration of tendons and ligaments

The purpose of this study was to evaluate the effects of hydrolytic degradation on the properties of a PLA hollow braid designed as a new concept of biodegradable prosthesis for the regeneration of tendons and ligaments. The main function of the braided material is to bear mechanical loads while it is being replaced by the newly-generated tissue. The kinetics of braided material degradation is thus an important factor in determining the success of the product. In order to study this mechanism, PLA braid was subjected to a 12-month degradation process at 37 °C in PBS at pH 7.4 (to simulate the human physiological medium) and to accelerated degradation for one month in pH 12 and pH 3 solutions. Degradation of the braid subjected to hydrolysis was evaluated by weight loss, molecular weight distribution, mechanical properties, and calorimetric and morphologic analyses. The weight loss in a basic medium reached 21%, versus no significant change in the other media. Average molecular weight was reduced by approximately 50% in the three media, with loss of mechanical properties in all cases. The morphological changes were more evident in the PLA degraded in the basic medium. The crystallinity of the material increased at the first stages of degradation, regardless of the medium used.     

Bioconvective Homann flow of tangent hyperbolic nanofluid due to spiraling disk with convective and zero mas flux constraints

The phenomenon of bioconvection in nanomaterials presents novel applications in the biotechnology, biofuels, enzymes, biomedical engineering and energy systems. Current exploration explores the applications of bioconvection in Homann flow of nanofluid due to spiraling of disk theoretically. The generalized model namely tangent hyperbolic fluid is used to predicts the rheological and thermal impact. The stability of nanofluid is ensured with interaction of motile microorganisms. The Boungrino nanofluid model with thermophoresis and Brownian motion features is used to perform the analysis The thermal distribution of nanofluids is proceeded by utilizing the zero mass thermal constraints. The similarity variables are introduced in order to estimating the dimensionless formulation. The Keller Box method with higher efficiency is imposed with implicit finite difference numerical algorithm. The main observations reveal that with enhancing the radial velocity and azimuthal velocity decreases with increasing sparling angle. For highly viscous case, a decrement in the azimuthal velocity has been observed.     

Ion transport across a bilayer lipid membrane facilitated by valinomycin

The facilitated ion transport from one aqueous phase, W1, to another, W2, across a bilayer lipid membrane, BLM, containing valinomycin, Val, as an ionophore was investigated by voltammetry. Cyclic voltammograms for the ion transfer were symmetrical about the origin (0 V, 0 A) and the magnitude of the ion transfer current increased with an increase in the absolute value of the applied potential. The magnitude of the ion transfer current at a definite potential in the voltammograms depended on the cation species added to W1 and W2 and was proportional to the concentration of Val in the BLM. The magnitude of the ion transfer current at a definite potential also varied in proportion to the hydrophobicity of the counter anion in W1 and W2. Taking into account the conjugated ion transfers at the W1|BLM and BLM|W2 interfaces, the positive current that flowed from W1 to W2 across the BLM was attributable to both the transfer of the complex-forming cation from W1 to the BLM and the transfer of the anion, which was distributed in the BLM as the counter ion from W2 to W1. The transfer from the BLM to W1 occurred at the W1|BLM interface and both the transfer of the cation from the BLM to W2 and the transfer of the anion from W2 to the BLM at the BLM|W2 interface. The negative current was then attributed to the opposite reaction. The voltammograms were asymmetrical with the origin when the ion components in W1 and W2 were different.     

Simultaneous determination of pyrethroids from pesticide residues in porcine muscle and pasteurized milk using GC

The principal goal of this work was to develop an efficient method for the simultaneous determination of four pyrethroid (PYR) insecticides, cyfluthrin, cyhalothrin, cypermethrin, and deltamethrin, in porcine muscle and pasteurized milk using liquid–liquid extraction (LLE). Sample extraction was carried out with and without additional column cleanup procedures, and the final determination was made using GC with electron‐capture detector (ECD). The pesticide identity was confirmed using GC‐MS in the SIM mode. Since there were minor differences between the extraction procedures, extraction without the additional cleanup procedure was used throughout the work. The method was validated by fortifying blank samples with half, two, and four times the maximum residue limit (MRL) of each PYR. The average recoveries (n = 6) ranged from 83.5 to 99.2% and 82.9 to 109% in porcine muscle and pasteurized milk, respectively. The repeatability of measurements expressed as RSDs, was in the range of 1.7–11.9 and 1.5–10.3% in porcine muscle and pasteurized milk, respectively. The LODs ranged from 3.3 to 9 and 3 to 8.1 ppm, whereas the LOQs ranged from 10 to 27.4 and 9 to 24.6 ppm, in porcine muscle and pasteurized milk, respectively. The applicability of the method was demonstrated by analyzing real samples collected from major cities in the Republic of Korea. No residues of the selected pesticides were detected in any of the samples.     

基于罗丹明类衍生物荧光增强的水体中Hg^2＋检测

利用一种罗丹明衍生物荧光探针的开环效应检测Hg2＋.在pH 7.0的Tris-HCl缓冲液中,Hg2＋与荧光探针结合导致罗丹明类衍生物开环,溶液颜色由无色变成粉红色,并且发射强的荧光.荧光强度与Hg2＋浓度在20~200 ng/L范围内呈良好的线性关系,检出限为4 ng/mL.实验考察了荧光探针的选择性以及温度、pH、荧光试剂浓度和盐度对Hg2＋检测的影响.结果表明该方法具有反应试剂水溶性好、选择性好和可常温检测等优点.方法应用于自来水、河水和湖水等水体中Hg2＋的检测,获得较好的回收率.