改性壳聚糖的制备及对Cu2+Pb2+的吸附研究

用巯基乙酸作为巯基化剂,对壳聚糖进行改性,选择了巯基化的条件.实验表明,在浓度为188mg/L的铜溶液中,CTS-SH的最大吸附率达90.3%以上,吸附容量为27.76mg/g,在浓度为203mg/L的铅溶液中,对铅的最大吸附率达到99%以上,在浓度为1.015g/L的铅溶液中,最大吸附率达95.5%.此时的吸附容量为97.4mg/g,吸附容量大于147.2mg/g时的吸附率为36.3%.经XRD及EMS图片的分析,可以看出,改性壳聚糖在吸附前后,结构发生了改变.     

Rhodium-catalyzed [2 + 2 + 2] cyclotrimerization in an aqueous-organic biphasic system

Macrocyclization via rhodium-catalyzed intramolecular [2 + 2 + 2] annulation of triynes has been explored in an aqueous-organic biphasic system. The biphasic system controls the concentration of hydrophobic substrates in the aqueous reaction phase and offers diluted reaction conditions without the use of a slow addition technique. The system also achieves selective cross-annulation between hydrophobic diynes and hydrophilic alkynes.     

Na+-Ca2+ exchanger modulates Ca2+ content in intracellular Ca2+ stores in rat osteoblasts

Na+-Ca2+ exchanger (NCX) transports Ca2+ coupled with Na+ across the plasma membrane in a bi-directional mode. Ca2+ flux via NCX mediates osteogenic processes, such as formation of extracellular matrix proteins and bone nodules. However, it is not clearly understood how the NCX regulates cellular Ca2+ movements in osteogenic processes. In this study, the role of NCX in modulating Ca2+ content of intracellular stores ([Ca2+]ER) was investigated by measuring intracellular Ca2+ activity in isolated rat osteoblasts. Removal of extracellular Na+ elicited a transient increase of intracellular Ca2+ concentration ([Ca2+]i). Pretreatment of antisense oligodeoxynucleotide (AS) against NCX depressed this transient Ca2+ rise and raised the basal level of [Ca2+]i. In AS-pretreated cells, the expression and activity of alkaline phosphatase (ALP), an osteogenic marker, were decreased. However, the cell viability was not affected by AS-pretreatment. Suppression of NCX activity by the AS-pretreatment decreased ATP-activated Ca2+ release from intracellular stores and significantly enhanced Ca2+ influx via store operated calcium influx (SOCI), compared to those of S-pretreated or control cells. These results strongly suggest that NCX has a regulatory role in cellular Ca2+ pathways in osteoblasts by modulating intracellular Ca2+ content.     

The solvent extraction of UO 2 2+ and Th4+ with petroleum sulfoxide

The influence of the concentration of nitric, hydrochloric and phosphoric acids, petroleum sulfoxides (PSO), salting-out agent, kind of diluent and temperature on the distribution ratio of U(VI) and Th(IV) has been systematically studied. It is found that the extraction regularity of PSO is similar to that of TBP. The distribution ratio in phosphoric acid is lower, but it increases with the increase of hydrochloric acid concentration and reaches a high value. The U(VI) exhibits the maximum distribution ratio at 3–4 mol/l HNO₃. The distribution ratio of U(VI) and Th(IV) increases rapidly in the presence of a salting out agent. The extracted compounds are determined to be UO₂(NO₃)₂2PSO and Th(NO₃)₄2PSO. The extraction enthalpies of U(VI) and Th(IV) with PSO were also calculated.     

Rhodium-catalyzed [2+2+1+1] cyclocarbonylative coupling of alkynes with carbon monoxide affording tetrasubstituted p-benzoquinones

In this strategy, the tetrasubstituted benzoquinones have been prepared directly by a [2+2+1+1] cyclocarbonylative coupling reaction of internal alkynes with CO in the presence of [RhCl(CO)2]2. The low concentration of CO in the reaction is the crucial point for the chemoselective formation of tetrasubstituted benzoquinones in good to high yields. Functional groups such as chloro, methoxy, cyano, vinyl, fluoro, and carboxylate are tolerated under the reaction conditions.     

A study on the phase behavior of the system CO2 + CO + H2 + 1-hexene + heptanal

The phase behavior of a system of importance for the hydroformylation reaction of 1-hexene in supercritical CO₂ has been studied in the range of 303.2–348.2 K with different CO₂ mole fractions. The conversion of 1-hexene varies from 0 to 1. The density of the reaction mixture at different conditions are also determined. It is demonstrated that the phase behavior changes with conversion of 1-hexene. At zero conversion, the phase separation pressure increases with increasing concentration of the reactants in the reaction system and decreases slightly with the increase of temperature. At other conversions, the phase separation pressure increases as temperature rises. The density of the reaction mixture at phase separation point is higher at the larger conversions.     

La^3＋,Co^2＋,Cu^2＋,Zn^2＋与X沸石的微波加热离子交换

用微波加热法研究了水溶液中金属阳离子Ｌａ＾３＋,Ｃｏ＾２＋,Ｃｕ＾２＋,Ｚｎ＾２＋与沸石分子筛ＮａＸ之间的离子交换反应。考察了溶液浓度、加热时间、苏州地交换度的影响并运用正交实验做了直观分析优化。对比实验及Ｘ射线粉末衍射结果表明,在相同的工艺条件下,微波加热法比传统加热法快约６０倍,微波加热对分子筛晶体结构没有破坏作用。     

Electrophoretic studies on the mixed nitrilotriacetate-penicillamine complexes of Pb2+ and UO 2 2+

A technique involving the use of paper electrophoresis is described for the study of binary and mixed-complex systems in solution. This technique is based on the movement of a spot of metal ion in an electric field with the complexants added in the background electrolyte at pH 8.5. The concentration of primary ligand (nitrilotriacetate) was kept constant, while that secondary ligand (penicillamine) was varied. A graph of log[penicillamine] versus mobility was used to obtain information on the mixed complexes and to calculate stability constants. The stability constants of mixed-ligand complexes lead(II)-nitrilotriacetate-penicillamine and uranyl(II)-nitrilotriacetate-penicillamine have been found to be 5.68 ± 0.09 and 6.56 ± 0.05 (logarithm stability constant values), respectively, at ionic strength 0.1 M and a temperature of 35°C. The text was submitted by the author in English.     

Ca2+、La3+及Eu3+对NaDC胶团的作用

在水溶液中将脱氧胆酸钠（ＮａＤＣ）分别与ＣａＣＬ２、ＥｕＣｌ３及ＬａＣｌ３反应,改变反应物浓度和配比,合成了系列脱氧胆酸络全物。利用红外光谱（ＦＴＩＲ）、元素分析、ＩＣＰ分析及Ｘ身材线粉末衍射谱,对它们的组成和结构进行了研究。结果表明：水溶液中ＣａＣｌ２与ＮａＤＣ的反应不是简单离子间的反应,改变其反应物浓度和配比,生成组成和结构不同的络合物;而ＬｎＣｌ３与ＮａＤＣ反应时,反应物浓度和配比的改变不影     

Gamma irradiation-induced Cd2+ and Pb2+ removal from different kinds of water

Gamma irradiation-induced removal of cadmium ion (Cd²⁺) and lead ion (Pb²⁺) in different kinds of water was investigated. It is observed that solution pH, dissolved oxygen (DO) concentration, sodium carbonate and EDTA played an important effect on Cd²⁺ and Pb²⁺ removal. Low solution pH, low DO concentration and sodium carbonate were favorable for removal of Cd²⁺ and Pb²⁺ by reducing species, while the presence of EDTA in solution restrained Cd²⁺ and Pb²⁺ reduction. Pb²⁺ removal percentage was higher compared to that of Cd²⁺ at the same experimental conditions. Cd²⁺ and Pb²⁺ removal under different conditions was well described by the pseudo-first-order kinetics model. Cd²⁺ and Pb²⁺ removal in different water followed an increasing order: water inflow<surface water<effluent<ground water. In addition, gamma irradiation resulted in a slight decrease in pH and TOC values of water inflow of municipal sewage treatment plant.     

Influence of Cd2+, Hg2+ and Pb2+ on (+)-catechin binding to bovine serum albumin studied by fluorescence spectroscopic methods

The effect of heavy metal ions, Cd(2+), Hg(2+) and Pb(2+) on (+)-catechin binding to bovine serum albumin (BSA) has been investigated by spectroscopic methods. The results indicated that the presence of heavy metal ions significantly affected the binding modes and binding affinities of (+)-catechin to BSA, and the effects depend on the types of heavy metal ion. One binding mode was found for (+)-catechin with and without Cd(2+), while two binding modes - a weaker one at low concentration and a stronger one at high concentration were found for (+)-catechin in the presence of Hg(2+) and Pb(2+). The presence of Cd(2+) decreased the binding affinities of (+)-catechin for BSA by 20.5%. The presence of Hg(2+) and Pb(2+) decreased the binding affinity of (+)-catechin for BSA by 8.9% and 26.7% in lower concentration, respectively, and increased the binding affinity of (+)-catechin for BSA by 5.2% and 9.2% in higher concentration, respectively. The changed binding affinity and binding distance of (+)-catechin for BSA in the presence of Cd(2+), Hg(2+) and Pb(2+) were mainly because of the conformational change of BSA induced by heavy metal ions. However, the quenching mechanism for (+)-catechin to BSA was based on static quenching combined with non-radiative energy transfer irrespective of the absence or presence of heavy metal ions.     

黄孢展齿革菌菌丝球同时吸附铅镉离子的动力学

采用间歇法，利用黄孢展齿革菌菌丝球吸附溶液中的Pb^2 和Cd^2 ，研究Pb^2 和Cd^2 共存体系中吸附初速率随初始浓度的变化规律。实验结果表明，少量Cd^2 的存在促进其对Pb^2 的吸附，并提高吸附初速率，但随着Cd^2 初始浓度的增加，促进作用逐渐减弱并转为抑制作用；Cd^2 的吸附初速率随着Pb^2 初始浓度增大而减小；Pb^2 和Cd^2 的吸附初速率都随自身初始浓度的增加而增大。     

Ca2+ Responsive Microgel-Stabilized Pickering Emulsions

As an ionic cross-linker that can change the size of poly(N-isopropylacrylamide-co-acrylic acid) microgel, Ca²⁺ is applied as a trigger to demulsify microgel-stabilized oil/water Pickering emulsions. The influence of Ca²⁺ induced intra-particle ionic cross-linking and inter-particle aggregation on the stability of microgel-stablized “Pickering” emulsion is described. At low and mediate concentration of Ca²⁺, ionic cross-linking can change the internal elasticity of the microgel, and cause the coarsening of the oil droplets. At high concentration of Ca²⁺, microgels flocculate due to the salt out effect and the emulsion is destabilized. This work provide a facile method to control the stability of the Pickering emulsions at ambient condition.     

Study of weak Mn2+ and Cu2+ complexes by a nuclear magnetic resonance method

An NMR method is described and applied, which allows the investigation of the first coordination sphere of certain transition metal ions. It is based on the measurement of the solvent proton nuclear magnetic relaxation times both as a function of magnetic field and of concentration of an admixed diamagnetic salt. This procedure enables an unambiguous separation of dynamic effects from ion-pair formation effects, which both can influence the relaxation times. As an application of this method, the complex formation of Mn²⁺ and Cu²⁺ with Br^–, I^–, ClO ₄ ^– , and SO ₄ ^2– in aqueous solution is studied. Thus the hydration numbersn _H2O of these cations as a function of anion concentration are obtained, allowing the detection of weak inner-sphere or outersphere complexes. Also several complex stability constants are derived and are compared with literature data.     

Ca2+- and Mg2+-induced molecular interactions in a dehydrocholic acid/didodecyldimethylammonium bromide mixed monolayer

The aim of this article is the evaluation of Ca²⁺ and Mg²⁺ subphases presence effect on mixed monolayers composed by dehydrocholic acid (HDHC) and didodecyldimethylammonium bromide (DDAB). The monolayer stability was analyzed by the evaluation of thermodynamic parameters, ΔG _mix^E and α. At all calcium ion-tested concentration, the mixed systems X _HDHC = 0.6 and 0.8 at π = 30 mJ m⁻² were always the most favored proportions. The X _HDHC = 0.6 system was also stable in magnesium presence, and the X _HDHC = 0.2-mixed monolayer went through a stable to an unstable state as the content of Ca²⁺ or Mg²⁺ augment. Finally, the X _HDHC = 0.4 monolayer showed a particular behavior, i.e., remained stable at low cation concentration, unstable at intermediate concentration and stable again at high concentration. The effect was similar at Mg²⁺ presence.     

Effects of Cu~(2+) on characteristic of SV currents

Applying the patch-clamp technique to vacuoles from Radish we studied the effects of Cu2 on Slow Vacuolar (SV) current’s characteristic. Our results show that Cu2 in bath solution at higher concentration inhibits SV currents and the percentage of inhibition increases with increasing concentration and changes with different voltage. When at lower concentration, Cu2 significantly promotes the SV currents and the promotion ratio decrease with increasing voltage. At the same time, the time constants of activation become lesser after adding Cu2 . These results show that there may be some Cu2 binding sites on SV channels and binding to which can change SV current’s characteristic.     

Experimental Densities, Speeds of Sound, Isentropic Compressibilties and Shear Relaxation Times of CaSO4·2H2O + CaCl2 + H2O and CaSO4·2H2O + NaCl + H2O Systems at Temperatures 30 and 35 °C

Speeds of sound, u, have been measured as a function of concentration for the systems, CaSO₄·2H₂O +CaCl₂ + H₂O and CaSO₄·2H₂O + NaCl + H₂O, at temperatures of 30 and 35 °C. Derived parameters such as the isentropic compressibility, κ _S , and the shear relaxation time,τ,were calculated using the experimental speed of sound data in combination with viscosity values from our earlier work. Results have been compared with those of the CaCl₂+ H₂Oand NaCl + H₂O systems reported in literature,to examine the effect of adding CaSO₄·2H₂O(s).Values of κ _S for the system,CaSO₄·2H₂O + CaCl₂+H₂O,are smaller compared with those for the CaCl₂+ H₂O system.Values of τ are lower at lower concentrations and then cross over in a narrow concentration region.Values of κ _S for the system,CaSO₄·2H₂O+NaCl+H₂O, are also smaller when compared with those forthe NaCl +H₂O system.For this system the τ values are higher. These τ values reach a minimum at a certain concentration of NaCl in the solution and then increase with further increases in concentration.The influenceof solvent-separated and/or solvent-shared ion pairs plays a dominant role at higher concentrations for both systems.Results have been interpreted and discussed in terms of the expansion and contraction of the primary hydration shell of the ionic species present in the studied systems.     

Characterization of hydromedusan Ca2+-regulated photoproteins as a tool for measurement of Ca2+concentration

Calcium ion is a ubiquitous intracellular messenger, performing this function in many eukaryotic cells. To understand calcium regulation mechanisms and how disturbances of these mechanisms are associated with disease states, it is necessary to measure calcium inside cells. Ca²⁺-regulated photoproteins have been successfully used for this purpose for many years. Here we report the results of comparative studies on the properties of recombinant aequorin from Aequorea victoria, recombinant obelins from Obelia geniculata and Obelia longissima, recombinant mitrocomin from Mitrocoma cellularia, and recombinant clytin from Clytia gregaria as intracellular calcium indicators in a set of identical in vitro and in vivo experiments. Although photoproteins reveal a high degree of identity of amino acid sequences and spatial structures, and, apparently, have a common mechanism for the bioluminescence reaction, they were found to differ in the Ca²⁺ concentration detection limit, the sensitivity of bioluminescence to Mg²⁺, and the rates of the rise of the luminescence signal with a sudden change of Ca²⁺ concentration. In addition, the bioluminescence activities of Chinese hamster ovary cells expressing wild-type photoproteins also differed. The light signals of cells expressing mitrocomin, for example, slightly exceeded the background, suggesting that mitrocomin may be hardly used to detect intracellular Ca²⁺ without modifications improving its properties. On the basis of experiments on the activation of endogenous P2Y₂ receptor in Chinese hamster ovary cells by ATP, we suggest that wild-type aequorin and obelin from O. longissima are more suitable for calcium detection in cytoplasm, whereas clytin and obelin from O. geniculata can be used for calcium measurement in cell compartments with high Ca²⁺ concentration. Figure

Hydromedusan photoproteins differ in Ca²⁺ concentration detection limit, sensitivity of bioluminescence to Mg²⁺, and rates of rise of luminescence signal with a sudden change of [Ca²⁺] despite a high degree of identity of their amino acid sequences and spatial structures, and, apparently, a common mechanism for the bioluminescence reaction.     

Thermodynamics of Pb2+ and Ni2+ adsorption onto natural bentonite from aqueous solutions

Removal of Pb2+ and Ni2+ from aqueous solutions by sorption onto natural bentonite was investigated. Experiments were carried out as a function of particle size, the amount of bentonite, pH, concentration of metals, contact time, and temperature. The adsorption patterns of metal ions onto followed the Langmuir, Freundlich, and Dubinin-Radushkevich isotherms. This included adsorption isotherms of single-metal solutions at 303 K by batch experiments. The thermodynamic parameters (DeltaH,DeltaS,DeltaG) for Pb2+ and Ni2+ sorption onto bentonite were also determined from the temperature dependence. The adsorptions were endothermic reactions. The results suggested that natural bentonite is suitable as a sorbent material for recovery and adsorption of metal ions from aqueous solutions.