Study of phase equilibria and boundary elements in the KBr-KVO3-K2MoO4 ternary system

By differential thermal analysis, the coordinates of the following characteristic points in the KBr-KVO₃-K₂MoO₄ system were determined: a eutectic in the KBr-KVO₃ system (12% KBr, 88% KVO₃, T _melt = 458°C), a eutectic in the KBr-KVO₃-K₂MoO₄ ternary system (12.8% KBr, 84.7% KVO₃, 2.5% K₂MoO₄,T _melt = 430°C), and also three points of polymorphic transitions in K₂MoO₄ ((1) δ ? γ: 21.7% KBr, 72.3% KVO₃, 6% K₂MoO₄,T _melt = 476°C; (2) γ ? β: 19% KBr, 78% KVO₃, 3% K₂MoO₄,T _melt = 450°C; and (3) γ ? β: 6% KBr, 89% KVO₃, 5% K₂MoO₄,T _melt = 450°C). For elements of the ternary system, phase equilibria were described.     

Origin of the Solar System and its elements

Formation of the Solar System from heterogeneous debris of a supernova (SN) that exploded 5 billion years ago was recorded as (1) inter-linked chemical and isotopic heterogeneities in meteorites, (2) higher levels of extinct nuclides in grains that trapped larger isotopic anomalies, (3) the physical properties of grains mentioned in part (2), and (4) patterns of isotopic anomalies in meteorites, in the solar-wind, and in solar flare particles. The Sun formed on the SN core, and planets formed in a rotationally-supported, equatorial disk of SN debris. Interiors of the Sun and the inner planets accreted first in a central, Fe-rich region surrounding the SN core. These were layered as condensate from other parts of the SN fell toward the condensing Sun. Elements in outer SN layers formed low-density, giant Jovian planets. Intra-solar diffusion enriches hydrogen and lighter isotopes of individual elements at the Sun's surface.     

Study on the co-luminescence system Sm-Gd-BPMPHD-CTMAB and its analytical application

It has been found that the Sm-BPMPHD-CTMAB ion association system shows a strong fluorescence intensity. In this system some rare earth ions, such as Lu³⁺, Y³⁺, Gd³⁺ and Tb³⁺, exert an evident fluorescence enhancement effect. The formation conditions of the system and the factors affecting the columinescence effect were studied in detail in order to determine trace amounts of Sm³⁺. Under optimum conditions a linear relationship was obtained between the fluorescence intensity and the Sm³⁺ concentration in the range of 5.0×10^?8–8.0×10^?6 mol·L^?1. The detection limit of Sm³⁺ was 2.0×10^?8 mol·L^?1. The determination gave satisfactory results.     

Chemical species of iridium and other trace elements in the Cretaceous-Tertiary boundary clays and their implication

The geological samples: Cretaceous-Tertiary (K-T) boundary clays, meteorites, volcanic lava, and ultrabasic rock were separated into carbonate, metal, sulfide, oxide, silicate and acid-resistant residue by a selective chemical dissolution procedure developed in our laboratory. Some conclusions were drawn by analyzing the chemical speciation of anomalous iridum in the above samples and especially by studying the characteristics of mineral components in those residue phases. (1) It is impossible that the anomalous Ir was caused by geochemical enrichment; (2) The iridium enrichment in the K-T boundaries did not necessarily associate with kerogen; (3) The volcanic activity has participated in the extinction event at the end of Cretaceous; (4) Extraterrestrial impact was the trigger of K-T event. Then, we proposed a mixed model by which the extant anomalous Ir in K-T boundary clays was interpreted as a combined effect of extraterrestrial impact, volcano eruption and post-depositional redistribution.     

乙醇增敏光泽精－H_2O_2－Pb（Ⅱ）化学发光体系的研究及应用

本文研究了Ｈ＿２Ｏ＿２氧化光泽精发光反应及乙醇的敏化作用，发现加入乙醇可使铅催化Ｈ＿２Ｏ＿２，氧化光泽精的发光强度有较大幅度的增强；铅量在３×１０￣（－７）～８×１０￣（－５）ｇ／ｍＬ。范围内与发光强度成正比．方法检出限为０．１０μｇ／ｍＬ；对含４μｇ／ｍＬＰｂ（Ⅱ）１１次重复测定，其ＲＳＤ为２．３％．对３２种常见的阴阳离子进行了干扰实验，表明方法具有较好的选择性。本法应用于水样及沉积物标样中痕量铅的测定，结果良好。     

Phase diagram and high-pressure boundary of hydrate formation in the ethane-water system

Dissociation temperatures of gas hydrate formed in the ethane-water system were studied at pressures up to 1500 MPa. In situ neutron diffraction analysis and X-ray diffraction analysis in a diamond anvil cell showed that the gas hydrate formed in the ethane-water system at 340, 700, and 1840 MPa and room temperature belongs to the cubic structure I (CS-I). Raman spectra of C-C vibrations of ethane molecules in the hydrate phase, as well as the spectra of solid and liquid ethane under high-pressure conditions were studied at pressures up to 6900 MPa. Within 170-3600 MPa Raman shift of the C-C vibration mode of ethane in the hydrate phase did not show any discontinuities, which could be evidence of possible phase transformations. The upper pressure boundary of high-pressure hydrate existence was discovered at the pressure of 3600 MPa. This boundary corresponds to decomposition of the hydrate to solid ethane and ice VII. The type of phase diagram of ethane-water system was proposed in the pressure range of hydrate formation (0-3600 MPa).     

Group of symmetry of the periodic system of chemical elements

The concurrence of the group of symmetry of the periodic system of elements with the group of dynamical symmetry of a hydrogenlike atom is employed in the theoretical investigation of atoms. The character of the degeneracy of the eigenvalues of a hydrogenlike atom Hamiltonian, without changing its eigenfunctions, was changed by introducing into this Hamiltonian a term which violates the symmetry in relation to transformations from the subgroup O(4) of the group SO(4, 2). In consequence, it was realized that such “reorganization” of the states of a hydrogenlike atom, which form a representation of the group SO(4, 2), effects the splitting of this representation into finite‐dimensional multiplets, first of which are in full agreement with the experimentally observable composition of electron shells of atoms, and retains the physical meaning of quantum numbers that define electron states. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 72: 499–508, 1999     

A regular periodic table of the elements and its quantum mechanical requirement

By using the n + (1/2)l filling rule of the atomic Aufbau principle, where n is the principal quantum number and l is the azimuthal quantum number, a new periodic table is presented, its periods having, in order, 8, 18, 18, 32, 42, 50, … elements. The mentioned rule is proposed instead of the n + l rule (or Madelung's rule) which constitutes the quantum mechanical basis of the current periodic table and predicts periods having, in order, 2, 8, 8, 18, 18, 32, 32, 50, … elements. The new periodic table is called “regular” because its groups are formed according to a single rule (namely, the first elements of each period are placed in the same order as the elements of the preceding period), in contrast with the current periodic table, where no simple rule can be applied for the same purpose. The most characteristic feature of the regular periodic table is the fact that its groups are also related in a periodic manner.     

Some solved problems of the periodic system of chemical elements

Basic questions on the periodic system (PS) of chemical elements are still under discussion. Several common misconceptions will be resolved. The word “chemical element” comprises more than two concepts. The PS can be rationalized on a quantum chemical basis, namely with the aid of four concepts: (1) electron configurations of bonded atoms, (2) realistic sequences of orbital energies, (3) spatial extension of valence and Rydberg orbitals, and (4) energy gaps above the closed 1s² and np⁶ shells (n = 2–6). The PS of known elements cannot be naively extrapolated. The common discussion of the PS in textbooks of general, inorganic, and physical chemistry needs revision. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Phase complex of the quaternary system LiF-SrFCl-SrCO3-SrMoO4 and the thermodynamic properties of its eutectics

By physicochemical analysis methods, the quaternary system LiF-SrFCl-SrCO₃-SrMoO₄ was studied for the first time. The tree of phases and the tree of crystallization of the system were constructed by an a priori prediction method. The compositions and temperatures at invariant points were determined, and the phase diagram of the system was constructed, the liquidus surface of which is represented by the crystallization fields of the initial compounds and the incongruently melting binary compounds Sr₅F₄Cl₄CO₃, Sr₂FClCO₃, and LiSrFCO₃. The heat-storage properties of eutectics in the system were evaluated.     

Study of complexation in the Nd3+-SCN− system

Summary A spectroscopic study of the association in the Nd³⁺-SCN^– system is presented. A characteristic change of the molar absorptivity of the solution with a plateau at 2–4M [SCN^–] and an increase at 4–8M [SCN^–] reflects the change from outer- to innersphere complexation.

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Untersuchungen zur Komplexierung im Nd³⁺-SCN^–-System

Zusammenfassung Es wird eine spektroskopische Studie der Assioziationsverhältnisse im Nd³⁺-SCN^–-System präsentiert. Die charakteristische Änderung in der molaren Absorption der Lösung mit einem Plateau bei 2–4M [SCN^–] und ein Anstieg bei 4–8M [SCN^–] ist auf einen Wechsel von außensphärischer zu innensphärischer Komplexierung zurückzuführen.

     

Study of the diffusion of trace elements and radionuclides in soils

Thin layer method of measuring diffusion processes was modified to shorten time and to increase efficiency of experiments. For this purpose small and fine glass capillaries of 20 mm length and inner diameter of several millimeters were used as diffusion cells. The diffusion of trace amounts of¹³⁷Cs, its dependence on soil moisture and interaction with the soil have been studied. Experimental technique. evaluation of records and the basic interpretation of the migration process are described.     

Study of the electrosynthesis of poly(3-butylthiophene) and its semiconductor properties

The mechanism of the electrosynthesis of poly(3-butylthiophene) (PBuT) was studied by cyclic voltammetry and potential step methods in comparison with polybithienyl. The anodic oxidation polymerization of the 3-butylthiophene underwent two steps: oligomer formation and further polymerization to form the polymer. The doping level of the PBuT increases with the cycle number of the potential sweeps during polymerization. The current responses to the potential steps indicate a nucleation and nuclei growth process which is repeated layer to layer. The differential capacity (C _d) and photocurrent were measured at the PBuT films in the aqueous electrolyte solution. The C _d ⁻² vs. E plot shows two regions of linearity, one with a negative slope and the other with a positive slope in different potential regions, which give the same flat-band potential. This indicates that the PBuT film exhibits both p-type and n-type features of a semiconductor at differrent potential regions. The cathodic photocurrent spectrum was analysed by the (j _ph hν)^{2/ n} vs. hν plots, giving band gap energies of 2.41 eV for n=1 and and 2.01 eV for n=4. Received: 29 July 1999 / Accepted: 15 November 1999     

镧系元素对Pd/Al2O3的修饰及其与丙烯腈气相加氢的关联

用浸渍法制备了镧系元素(Ce,La,Sm)修饰的低负载Pd(0.05 w.t%)/A l2O3催化剂,并应用于丙烯腈选择性加氢反应,实验结果表明:这种方法制备的催化剂对丙烯腈具有很好的选择性,镧系元素的添加大大促进了催化剂的活性和稳定性。XRD的测试结果表明稀土元素铈的添加减弱了Pd和载体A l2O3之间的相互作用,从而导致了Pd从载体表面游离出来。从TEM照片上可以看出催化剂颗粒尺寸的变化。XPS的测试结果表明用镧系元素修饰的Pd的结合能向较高能级发生了转移,从而使得钯被还原为零价。     

Trace elements in brown coal and its products of combustion

Concentrations of 38 elements in brown coal, bottom ash and size fractionated ESP coal ash from the Belchatów I Power Plant were determined by INAA. Based on enrichment factors calculated relatively to iron and average crustal rock composition as a function of particle size the elements are grouped into three classes: Group I, elements that show little or no enrichment in the small particles /Na, Mg, Al, K, Sc, Ti, Mn, Co, Rb, Cs, Ba, La, Ce, Sm, Eu, Lu, and Th/; Group II, elements whose enrichment increases greatly with decreasing particle size /Cl, Zn, As, Se, Br, Cd, Sb, and I/; and Group III, elements whose behaviour is intermediate to that of elements in Group I and II /Ca, V, Cr, Ni, Cu, Ga, Sr, Mo, In, W, and Au/.     

Present-day methods for the determination of trace elements in oil and its fractions

The development and use of instrumental methods for the determination of a wide range of trace elements in oil is considered. Special attention is paid to methods of the direct introduction of samples into spectrometers. It is shown that preliminary sample preparation is in certain cases necessary for the determination of trace elements in oil. The main methods of sample preparation of oils, including methods of extraction of a series of trace elements from crude oil (extraction, membrane, sorption, etc.), are described.     

Study of the voltammetric behaviour of metam and its application to an amperometric flow system

The electrochemical behaviour of the pesticide metam (MT) at a glassy carbon working electrode (GCE) and at a hanging mercury drop electrode (HMDE) was investigated. Different voltammetric techniques, including cyclic voltammetry (CV) and square wave voltammetry (SWV), were used. An anodic peak (independent of pH) at +1.46 V vs AgCl/Ag was observed in MT aqueous solution using the GCE. SWV calibration curves were plotted under optimized conditions (pH 2.5 and frequency 50 Hz), which showed a linear response for 17–29 mg L⁻¹. Electrochemical reduction was also explored, using the HMDE. A well defined cathodic peak was recorded at −0.72 V vs AgCl/Ag, dependent on pH. After optimizing the operating conditions (pH 10.1, frequency 150 Hz, potential deposition −0.20 V for 10 s), calibration curves was measured in the concentration range 2.5×10⁻¹ to 1.0 mg L⁻¹ using SWV. The electrochemical behaviour of this compound facilitated the development of a flow injection analysis (FIA) system with amperometric detection for the quantification of MT in commercial formulations and spiked water samples. An assessment of the optimal FIA conditions indicated that the best analytical results were obtained at a potential of +1.30 V, an injection volume of 207 μL and an overall flow rate of 2.4 ml min⁻¹. Real samples were analysed via calibration curves over the concentration range 1.3×10⁻² to 1.3 mg L⁻¹. Recoveries from the real samples (spiked waters and commercial formulations) were between 97.4 and 105.5%. The precision of the proposed method was evaluated by assessing the relative standard deviation (RSD %) of ten consecutive determinations of one sample (1.0 mg L⁻¹), and the value obtained was 1.5%.     

Accurate solution of multi-region continuum biomolecule electrostatic problems using the linearized Poisson-Boltzmann equation with curved boundary elements

We present a boundary-element method (BEM) implementation for accurately solving problems in biomolecular electrostatics using the linearized Poisson-Boltzmann equation. Motivating this implementation is the desire to create a solver capable of precisely describing the geometries and topologies prevalent in continuum models of biological molecules. This implementation is enabled by the synthesis of four technologies developed or implemented specifically for this work. First, molecular and accessible surfaces used to describe dielectric and ion-exclusion boundaries were discretized with curved boundary elements that faithfully reproduce molecular geometries. Second, we avoided explicitly forming the dense BEM matrices and instead solved the linear systems with a preconditioned iterative method (GMRES), using a matrix compression algorithm (FFTSVD) to accelerate matrix-vector multiplication. Third, robust numerical integration methods were employed to accurately evaluate singular and near-singular integrals over the curved boundary elements. Fourth, we present a general boundary-integral approach capable of modeling an arbitrary number of embedded homogeneous dielectric regions with differing dielectric constants, possible salt treatment, and point charges. A comparison of the presented BEM implementation and standard finite-difference techniques demonstrates that for certain classes of electrostatic calculations, such as determining absolute electrostatic solvation and rigid-binding free energies, the improved convergence properties of the BEM approach can have a significant impact on computed energetics. We also demonstrate that the improved accuracy offered by the curved-element BEM is important when more sophisticated techniques, such as nonrigid-binding models, are used to compute the relative electrostatic effects of molecular modifications. In addition, we show that electrostatic calculations requiring multiple solves using the same molecular geometry, such as charge optimization or component analysis, can be computed to high accuracy using the presented BEM approach, in compute times comparable to traditional finite-difference methods.