Some Correlations Between Chelate Extraction Distribution Ratios,Bond Types,and Solvent Physical Properties

Abstract

Correlations between extraction distribution ratios, bond types, and common solvent physical properties were determined for 19 extraction systems. Different types of bonding are involved in the water adduct formation on different types of chelates.     

Characterizing the origins of bottled water on the South Korean market using chemical and isotopic compositions

We analyzed the major elements and stable isotopes of oxygen, hydrogen, and carbon (dissolved inorganic carbon: DIC) in various types of bottled water (domestic and foreign) commercially available in South Korea to classify the water types and to identify their origins. Only marine waters and some sparkling waters could be discriminated by their physicochemical compositions. Oxygen and hydrogen isotopes made marine waters more distinguishable from other water types. The determination of the carbon isotope composition of DIC was clearly useful for distinguishing between naturally and artificially sparkling waters. In addition, statistical analysis also appeared to aid in the discrimination of bottled water types. Our results indicate that a method that combines chemical and stable isotope composition analysis with statistical analysis is the most useful for discriminating water types and characterizing the origins of bottled water.     

Selectivity effects related to the diversity of active sites operating on nanostructured multifunctional catalysts

The goal of the present study was to gain a better understanding of the selectivity of processes over multifunctional catalysts exhibiting diversity of operating active sites. The concept is that the concurrent performance of different types of active sites may provoke effects on the process selectivity comparable to the effects resulting from the kinetic regularities and activation energies of the occurring reactions. Accordingly, in the kinetic model the authors introduce specific parameters reflecting the contribution of distinct types of active sites, facilitating different reaction routes. Reasons are adduced how suchlike parameters serve to account the impact of various reaction routes occurring on different types of sites. The suggested approach links the deactivation-caused selectivity changes to dissimilarities in the vulnerability of different types of active sites. This work relates the probabilities for action of different types of sites to the size of active-phase islands. Various reaction mechanism patterns are modeled to examine relevant selectivity effects.     

Atomic Properties of Amino Acids: Computed Atom Types as a Guide for Future Force‐Field Design

The quantum chemical topology (QCT) is able to propose atom types by direct computation rather than by chemical intuition. In previous work, molecular electron densities of 20 amino acids and smaller derived molecules were partitioned into a set of 760 topological atoms. Each atom was characterised by seven atomic properties and subjected to cluster analysis element by element, that is, C, H, O, N, and S. From the respective dendrograms, 21 carbon atom types were distinguished, 7 hydrogen, 2 nitrogen, 6 oxygen, and 6 sulfur atom types. Herein, we contrast the QCT atom types with those of the assisted model building with energy refinement (AMBER) force field. We conclude that in spite of fair agreement between QCT and AMBER atom types, the latter are sometimes underdifferentiated and sometimes overdifferentiated. In summary, we suggest that QCT is a useful guide in designing new force fields or improving existing ones. The computational origin of QCT atom types makes their determination unbiased compared to atom type determination by chemical intuition and a priori assumptions. We provide a list of specific recommendations.     

Sorption of U(VI) onto granite surfaces: A kinetic approach

Surface sorption experiments of U(VI) onto the surfaces of a Korean granite rock are carried out in order to investigate the kinetics and reversibility of U(VI) sorption as a function of pH and surface types such as fresh intact surfaces and natural fracture surfaces. It was shown that the effect of pH is significant in the sorption of U(VI) onto both types of the granite surfaces. However the sorption rates do not greatly depend upon the pH regardless of the surface types. A two-step first order kinetic behavior dominates onto both the intact surfaces and natural fracture surfaces of granite and that the linearization approach of the kinetic model agrees well with experimental sorption data. The desorption results showed that the sorption process of U(VI) was a little irreversible for the two types of granite surfaces regardless of pH and surface types. This kinetic approach could give a better understanding of U(VI) sorption onto granite surfaces depending on pH and surface types. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis of two types of nanoparticles in polyelectrolyte capsule nanoreactors and their dual functionality

Polyelectrolyte multilayer capsule reactors (PEMCRs) for the synthesis of two types of nanoparticles were prepared. The tunable PEMCRs containing two different functional groups that can be used to synthesize two types of nanoparticles simultaneously and to control the composition of two types of nanoparticles within the shell of PEMCs. These PEMCRs enabled the composition as well as the amount of the loaded two types of nanoparticles within the shell of PEMCs to be controlled by the copolymer ratio and the number of reaction cycles. Another interesting finding is that, as a result of the synthesis of two types of nanoparticles, these specially designed PEMCs containing both silver and goethite nanocrystals can be used as antimicrobial capsules, which can move by an external magnetic field. Such a technology has the potential for use in sterilization at the desirable sites.     

Stability and rheology of three types of W/O/W multiple emulsions emulsified with lecithin

Three types of multiple emulsions were prepared with lecithin. The morphology, stability, and rheological properties of the three types of W/O/W multiple emulsions were evaluated. The formulation factors, including salts and aliphatic alcohol, were further examined. The three types of multiple emulsions were formed by different emulsifiers. An excellent multiple emulsion occurred with 2?wt% lecithin concentration, stabilized by 0.05?wt% NaCl. All multiple emulsions showed shear-thinning behavior, i.e., the apparent viscosity decreased with the increase of the shear rate. With the high concentration of lecithin, the multiple emulsions exhibited the highest viscosity at low shear rate and had higher storage modulus (G′) and the loss modulus (G″). This study was conducted to reveal that different types of multiple emulsions can be formed with lecithin, and that the stability and rheological properties were different with different types of multiple emulsions.     

Comparison of the changes of the antigenicities of a hen's egg albumin by a gamma and an electron beam irradiation

The study was conducted to compare the radiation types of a gamma ray and an electron beam for the inhibition and reduction of a food allergy. OVA (2 mg/ml) were irradiated at 3, 5, 7 and 10 kGy. Patterns detected by the SDS-PAGE and an immunoblot showed that the intact OVA band disappeared and that it was dependant upon the radiation doses regardless of the radiation types. Binding abilities of the irradiated OVA against the monoclonal IgG and the egg allergic patients’ IgE decreased due to a conformational change of the epitope, but differences from using the two different radiation types were not observed. The results indicate that both the radiation types can be used for an inhibition and a reduction of a food allergy regardless of the radiation types.     

茂型稀土金属有机配合物催化甲基丙烯酸酯类聚合研究进展

综述了茂型稀土金属有机配合物催化甲基丙烯酸酯类聚合的研究现状和最新进展。系统地介绍了不同的茂型稀土金属有机催化体系中温度、反应时间、溶剂等条件对催化甲基丙烯酸酯类聚合的影响规律,并研究其催化反应机理,最后展望茂型稀土金属有机化学今后的研究方向及前景。     

化学知识类型与学习方式选择的探讨

基础教育新一轮课程改革是教育领域里的一场深刻革命,它呼唤着学生学习方式的根本转变。根据现代认知心理学的研究成果与化学学科内容的特点,我们将化学知识分为系统-演绎化学知识与经验-缄默化学知识2大类,每一类又可划分为不同的类型,化学知识的类型影响着化学学习方式的选择。     

对MgO重新水合及两类羟基的研究

采用IR、XRD、TG-DTA等手段对MgO重新水合及其两类羟基进行了研究。发现MgO水解后活性增大,在实验条件下水解仅发生在表面浅层;水合可得到自由、水合两类羟基,600℃灼烧使两类羟基脱除;自由羟基由水合羟基在碱[O^2-]作用下生成;添加Li⁺对表面两类羟基有影响。     

The definition of core electrons

The traditional separation of electrons in molecules into core and valence types is often based on molecular orbital energies. This method is known to lead in some cases to large relative errors in correlated calculations. Instead, we propose a method based on the definition of molecular core character using separation of basis functions into core and valence types. This gives size-consistency to separation of electrons in molecules into core and valence types.     

The first linear multiphosphazene having five different types of side groups and its use as the core of a dendrimeric species

The step-by-step synthesis of the first oligophosphazenes having more than two types of side functions is described. These multifunctionalized oligophosphazenes possess up to four phosphazene linkages and up to four types of functional side groups. These compounds may serve as models for a better understanding of electronic delocalization phenomena in linear inorganic chains, and constitute novel cores for the synthesis of new dendrimeric species possessing several types of functions as end groups, at the level of the core, and within the branches.     

The use of iron carbonyls in the C—C bond formation reactions

Russian Chemical Bulletin - The review systematizes material by key types of reactions promoted by iron carbonyls. The reaction types are subdivided into several principal directions, focusing...     

规模化养殖场废水中抗生素种类及残留特征研究

2010年调查了海南省6家规模化养猪场抗生素使用品种及来源,并采集养殖废水样品,用高效液相色谱紫外检测器检测了样品中4种四环素(四环素、土霉素、金霉素和强力霉素)和8种磺胺类药物(磺胺嘧啶、磺胺甲噻唑、磺胺噻唑、磺胺二甲基嘧啶、磺胺氯哒嗪、磺胺邻二甲氧嘧啶、磺胺间二甲氧嘧啶和磺胺喹恶啉)的残留浓度水平。结果显示,6家养殖场废水中土霉素、四环素和磺胺嘧啶的检出率及检出浓度较高,其中土霉素检出率为100%,最高浓度为71.75μg/L;四环素检出率为63%,最高检出浓度为24.83μg/L;磺胺嘧啶检出率为83%,最高检出浓度为17.69μg/L。4种四环素类检出总量变化范围为18.25～99.64μg/L,8种磺胺类检出总量变化范围为3.45～24.49μg/L;从养殖规模上看,小规模养殖场抗生素类检出品种较多,检出浓度也较高。     

Recent Studies of the Synthesis and Reactivity of Group 6 and 7 Transition Metal Compounds with Metal–Metal Bonds

Metal–metal bonded dinuclear compounds of Group 6 and 7 transition metals with several primary structural motifs and their reactivity toward halides and organic molecules are reviewed. The reactivities of dinuclear compounds of Cr, Mo, W, Mn, Tc, and Re are discussed in context with reaction types (ligand metathesis, oxidative addition), the types of ligands (carbon, sulfur or nitrogen containing), or the ligand substituted in the original starting material (carbonyl). Since the depth and breadth of the chemistry is extensive, the categories are fairly general and some overlap between ligand types and reaction types occurs. A brief history followed by recent studies of each of these transition metal centers provides a general overview of the reactivity of these metal–metal bonded systems.     

烟煤快速加氢热解的研究Ⅵ．煤和半焦中氮化学形态剖析

采用电子能谱(XPS)测定了我国以烟煤为主的10种煤样以及对应快速加氢热解半焦中氮的化学形态。研究结果表明我国煤的XPS谱图在398.8(±0.1)和400.2(±0.1)eV的位置上出现氮峰,其相应氮化合物是吡啶和吡咯,随煤种不同氮的形态不尽一致,但主要是吡啶和吡咯,且多数煤以吡咯氮为主。快速加氢热解半焦与煤有相同的氮出峰位置,即半焦与煤有相同的氮化学形态,加氢热解过程总体为吡咯氮相对含量的增加和吡啶氮的减少。     

Melting diagrams of quaternary systems with a single compound

Topological analysis was made of the structure of the melting diagrams of quaternary systems with a single compound. Graphs of phase diagrams were constructed, which show the relative positions of invariant points and monovariant lines on the liquidus hypersurface. It was shown that there exist two types of diagrams with a binary compound and six types of diagrams with a ternary compound. Quaternary compound C can form by congruent crystallization reaction L = C (I) or by the interaction of melt with components: L + K₁ = C (II), L + K₁ + K₂ = C (III), or L + K₁ + K₂ + K₃ = C (IV). There are 23 types of diagrams with reaction (I) and 23 types of diagrams with reaction (II), which described by identical graphs; 25 types of diagrams with reaction (III); and 6 types of diagrams with reaction (IV). Fragments of the obtained diagrams correspond to various topological situations, which may occur in more-component systems.     

Nanotubular boron-carbon heterojunctions

Linear nanotubular boron-carbon heterojunctions are systematically constructed and studied with the help of ab initio total energy calculations. The structural compatibility of the two classes of materials is shown, and a simple recipe that determines all types of stable linear junctions is illustrated in some detail. Our results also suggest the compatibility of various technologically interesting types of nanotubular materials, leading to different types of nanotubular compound materials, and pointing out the possibility of wiring nanotubular devices within heterogeneous nanotubular networks.     

Inorganic chemical approaches to pharmacognosy. VII. X-ray fluorescence spectrometric studies on the inorganic constituents of crude drugs. (5). The relationship between inorganic constituents of plants and the soils on which they are grown

Inorganic constituents of the leaves of several kinds of plants growing on different soil types were investigated using energy-dispersive X-ray fluorescence spectrometry. The results can be summarized as follows: (1) Each plant exhibited a characteristic metals profile, even if they were grown on similar soil types. (2) As we would expect, the metals profile of the plant leaves depends on the inorganic constitution of the soil on which it is grown. However, the degree of the influence of the soil types on the metals profile of the plant differs according to the kind of inorganic element: Ca and Cu are almost independent of the soil types, but the Ti and Fe content is dependent upon the soil types. (3) Sr content of plant leaves is closely related to the ratio of Sr to Ca of the soil on which the plants are grown. (4) This information should be helpful in identifying the producing district or original plant of a crude drug by its metals profile.