Changes in the composition of volatile monoterpenes and sesquiterpenes of Pinus armandi, P. tabulaeformis, and P. bungeana in Northwest China

The volatile mono-and sesquiterpenes obtained from the needles and resin of Pinus armandi, P. tabulaeformis, and P. bungeana growing in the Qinling, Taibai, and Huanglong Mountain forest ecosystem were analyzed by means of GC-MS. Forty-eight constituents were identified, and α-pinene, β-pinene, 1R-α-pinene, β-caryophyllene, cadindiene, α-caryophyllene, D-limonene, and 1S-β-pinene were the major components of the mono-and sesquiterpenes in the needles and resin. The components of the volatile mono-and sesquiterpenes from the needles and resin at Qinling, Taibai, and Huanglong Mountains had remarkable differences in three pine species, whereas the monopertene content such as α-pinene, β-pinene, D-limonene, and camphene were mostly changed in the growing stage. The intraspecies variation in the different ecosystems can be attributed to the species’ geography and genetic variation, and even the adaptation of the pine species to different ecological environments. Moreover, monoterpenes and sesquiterpenes can be induced by the attack of bark beetles, of which the α-pinene, β-pinene, 1R-α-pinene, 1S-α-pinene, b-myrecene, and β-caryophyllene contents had positive relations with the attacking Dendroctonus armandi and D. valens. Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 430–433, September–October, 2006.     

Lösungsmitteleinfluß auf das Redoxverhalten des Hexakismethylisonitrilmangan (I) ions

The redox behaviour of hexakismethylisonitrilmanganese(I) [MnL ₆ ⁺] has been studied in acetic acid, dichloromethane, 1,2-dichloroethane, propylenecarbonate, butyrolactone, methanol, ethanol, nitromethane, acetonitrile, N-methyl-2-pyrrolidinone, dimethylformamide, dimethyl sulfoxide and water. The reversible diffusion-controlled oxidation MnL ₆ ⁺/MnL ₆ ²⁺ could be observed in all solvents studied, on both the dropping mercury electrode and the stationary platinum electrode. Employing tetrabutylammonium perchlorate as supporting electrolyte, the oxidation MnL ₆ ²⁺/MnL ₆ ³⁺ was observable only in acetic acid, nitromethane, 1,2-dichloroethane, dichloromethane, propylenecarbonate, butyrolactone and acetonitrile. In all other solvents oxidation of the solvent preceded the oxidation MnL ₆ ²⁺/MnL ₆ ³⁺. Poorly defined polarographic waves attributable to the one electron reduction of the MnL ₆ ⁺ were observed in butyrolactone, propylenecarbonate, acetonitrile, dimethylformamide, N-methyl-2-pyrrolidinone and dimethyl sulfoxide. All potential values were recorded versus bisbiphenylchromium(I)-iodide [BBCr(I)J], the problems of measuring against external aqueous reference electrodes are discussed. The redox potential of the process MnL ₆ ⁺/MnL ₆ ²⁺ was found to be a function of the donor properties of the solvents used; the effects of outer sphere coordination on the redox behaviour of this couple are discussed. No effect of the supporting electrolytes tetrabutylammonium perchlorate, tetraethylammonium nitrate and tetraethylammonium perchlorate on the redox behaviour of MnL ₆ ⁺ was found. The UV-spectrum of MnL ₆(PF₆)₂ has been recorded.

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Mit 3 Abbildungen     

Nanostructuring in the process of the formation of mixed-anion compounds: Rare-earth borogermanates, germanophosphates, and borotungstates

Specific features of the textures (the preferred orientation of the nanometer building blocks) in the structures of mixed-anion compounds—rare-earth borogermanates, germanophosphates, and borotungstates that arise from the acid-base interaction in the Ln₂O₃-B₂O₃-GeO₂, Ln₂O₃-GeO₂-P₂O₅, and Ln₂O₃-B₂O₃-WO₃ systems (Ln = La-Gd)—have been studied. Based on characteristic texture traits, the mixed-anion compounds of early rare-earth elements can be divided into three groups: (i) Ln₂O₃: E_xO_y > 1, (ii) Ln₂O₃: E_xO_y = 1, and (iii) Ln₂O₃: E_xO_y < 1. Because of the dominant structural effect of the basic oxide Ln₂O₃ in the compounds of the first group, the structures of Nd₁₄O₈(BO₃)₆(GeO₄)₂ and Pr₁₁O₁₀(GeO₄)(PO₄)₃ are composed of infinite [LnO_n] bands and layers and discrete groups [EO_m] located in the interband and interlayer spaces. The dominant structural effect of the acid oxides [E_xO_y] in the compounds of the third group leads to the appearance of ring textures composed of [LnO_n], as well as to the appearance of chains and networks composed of [EO_m], in the structures of Ln(BGeO₅) and Ln(BO₂)(WO₄). Original Russian Text ￠ G.A. Bandurkin, N.N. Chudinova, G.V. Lysanova, K.K. Palkina, E.V. Murashcva, V.A. Krut’ko, G.M. Balagina, 2006, published in Zhurnal Neorganicheskoi Khimii, 2006, Vol. 51, No. 2, pp. 334–347.     

非晶态镍硼酸盐结构的EXAFS研究

由摩尔比分别为1:2和1:8的NiCl₂·6H₂O和Na₂B₄O₇·10H₂O作为反应物, 合成两种非晶态镍硼酸盐, 同时通过水热法合成β-Ni(OH)₂. 化学分析和热重-微商热重法(TG-DTG)分析结果确定两种非晶态镍硼酸盐的分子组成分别为NiO·0.8B₂O₃·4.5H₂O和NiO·B₂O₃·3H₂O. 激光拉曼(Raman)实验结果表明镍硼酸盐样品中主要存在的硼氧阴离子为B₃O₃(OH)₅^2-和B₂O(OH)₆^2-. 同步辐射扩展X射线吸收精细结构(EXAFS)方法对样品进行结构解析, 通过数据拟合给出样品中Ni 原子周围近邻配位原子种类、配位数以及原子间距离. 用不同晶体结构作为标准对两种非晶态镍硼酸盐进行拟合的结果表明, 样品中Ni 原子周围局域结构与Ni₃B₂O₆晶体(ICSD No.31387)中的吻合较好. Ni 原子周围配位原子为O、B和Ni, 对于NiO·0.8B₂O₃·4.5H₂O, 配位数分别为5.7、3.8和3.8, 配位距离分别为0.208、0.263 和0.311 nm; 对于NiO·B₂O₃·3H₂O, 配位数分别为6.0、4.0 和4.0, 配位距离分别为0.207、0.262和0.310 nm.     

Binuclear Pd(II) complexes with chiral ethylenediaminodioxime (H2L) and bis-α-thiooxime (H2L1), the derivative of monoterpenoid(+)-3-carene. Crystal structures of [Pd2(H2L)Cl4] and [Pd2(H2L1)Cl4] · 3CDCl3

Diamagnetic Pd(II) complexes with the chiral ethylenediaminodioxime (H 2 L) and bis-α-thiooxime (H₂L¹), the derivatives of monoterpenoid (+)-3-carene, of the composition Pd₂(H₂L)Cl₄(I), Pd₂(H₂L¹)Cl₄ (II), and the solvate Pd₂(H₂L¹)Cl₄·3DCl₃ (III) were synthesized. The crystal structures of complex I and solvate III were determined from X-ray diffraction data. The structures consist of acentric binuclear molecules with the coordination cores PdN₂Cl₂ (in I) and PdNSCl₂ (in III) in the form of the distorted squares. In complex I, each Pd atom coordinates two N atoms of the tetradentate bridge-cyclic ligand H₂L and two Cl atoms; in compound III, one N and one S atom of the tetradentate bridge-cyclic ligand H₂L¹, and 2 Cl atoms. The CDCl₃ molecules in compound III lie in the cavities formed by the molecules of complex II. In both structures, the PdCl₂ fragments are in the trans-positions. The ¹H NMR spectra indicate that the structures of complexes I, II in solutions are similar to the structures of compounds I, III in the solid state. Original Russian Text ? T.E. Kokina, L.I. Myachina, L.A. Glinskaya, A.V. Tkachev, R.F. Klevtsova, L.A. Sheludyakova, S.N. Bizyaev, A.M. Agafontsev, N.B. Gorshkov, S.V. Larionov, 2008, published in Koordinatsionnaya Khimiya, 2008, Vol. 34, No. 2, pp. 120–132.     

Oxygen nonstoichiometry and the thermodynamic and structural properties of double perovskites PrBaCo2 ? xCuxO5 + δ

The special features of the structure, electrophysical properties, and oxygen nonstoichiometry of new double perovskites PrBaCo_{2 − x} Cu _x O_{5 + δ} were studied. Within the homogeneity region with respect to copper 0 < x ≤ 1, solid solution samples had an orthorhombic structure (space group Pmmm) with the parameters a _p × 2a _p × 2a _p , where a _p ≈ 3.8 ?. The oxygen nonstoichiometry of PrBaCo_{2 − x} Cu _x O_{5 + δ} changes as the copper content increases approximately as δ ≈ 0.85 − x/2. The content of oxygen was measured by coulometric titration over wide temperature and oxygen pressure ranges. The partial thermodynamic functions of labile oxygen were calculated and the limits of the thermodynamic stability of the solid solution were established. Original Russian Text ? A.Yu. Suntsov, I.A. Leonidov, A.A. Markov, M.V. Patrakeev, Ya.N. Blinovskov, V.L. Kozhevnikov, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 5, pp. 954–960.     

Physicochemical and catalytic properties of systems based on CeO<Subscript>2</Subscript>

The effect of synthesis conditions, the nature of components, and the ratio between the components on the phase composition, the texture, and the redox and catalytic properties of the Ce-Zr-O, Ce-Zr-M₁-O (M₁ = Mn, Ni, Cu, Y, La, Pr, or Nd), N/Ce-Zr-O (N = Rh, Pd, or Pt), and Pd/Ce-Zr-M₂-O/Al₂O₃ (M₂ = Mg, Ca, Sr, Ba, Y, La, Pr, Nd, or Sm) was considered. A cubic solid solution with the fluorite structure was formed on the introduction of <50 mol % zirconium into CeO₂, and the stability of this solid solution depended on preparation procedure and treatment conditions. The presence of transition or rare earth elements in certain concentrations extended the range of compositions with the retained fluorite structure. The texture of the Ce-Zr-O system mainly depended on treatment temperature. An increase in this temperature resulted in a decrease in the specific surface area of the samples. The total pore volume varied over the range of 0.2–0.3 cm³/g and depended on the Ce/Zr ratio. The presence of transition or rare earth elements either increased the specific surface area of the system or made it more stable to thermal treatment. The introduction of the isovalent cation Zr⁴⁺ into CeO₂ increased the number of lattice defects both on the surface and in the bulk to increase the mobility of oxygen and facilitate its diffusion in the Ce_{1 − x} Zr _x O₂ lattice. The catalytic properties of the Ce-Zr-M₁-O or N/Ce-Zr-M₂-O systems were due to the presence of anion vacancies and the easy transitions Ce⁴⁺ ai Ce³⁺, M₁²ⁿ⁺ ai M₁ ⁿ⁺, and N ^δ+ → N ⁰ in the case of noble metals.     

Novel correlations between the critical constants of the noble gases

For any particular fluid, the set of three critical constants (CC) – pressure P_c, temperature T_c and molar volume V_c – has a central importance in defining the physical behaviour of the fluid in the gas and liquid states. However, little attention seems to have been paid in the past to the relations between the CC of different substances. In the present paper, some simple and apparently novel relations have been found between the three CC for the set of four noble gases: Ne, Ar, Kr, Xe. Defining the critical quotient Q_c ≡ RT_c/P_c (where R is the Gas Constant) the correlations may be summarised by the dual equation: (V_c/cm³ mol⁻¹) = 27 + 0.31 (T_c/K) = 3.3 + 0.280 (Q_c/cm³ mol⁻¹), which describes the CC data for the quartet Ne–Xe with an average uncertainty of 0.5%. Regarding the other two noble gases, the two isotopes of the lightest member, ³He and ⁴He, show the deviations from these relations that are expected from quantal effects and their low molar masses; while for the heaviest member, Rn, the correlations enable a value of 145(5) cm³ mol⁻¹ to be estimated for V_c that is not otherwise well defined in the literature. By contrast, and contrary to the general assumption, the second lightest member, Ne, apparently does not show appreciable quantal effects in the area, so that Ne–Xe may be considered together as a group. These correlations are compared with the behaviour of a selection of polyatomic fluids; in these comparisons, the NG dual correlation equation provides a reference line defining the presumed simplest behaviour. This and related areas show a “Residual Volume Effect”, in that extrapolating the equivalent temperature and energy parameters to zero for the state of zero-mass point particles, referred to here as the hypothetical element zeronium (Ze), the system in each case still has a finite intercept; this intercept amounts to essentially 34% of the average volume for the present quartet Ne–Xe, rather than the zero volume expected for this condition.     

Structure and magnetic properties of sulfides of the type CdRE2S4 and Mg(GdxYb1−x)2S4

CdRE₂S₄ (RE = Gd, Tb, Dy, Ho, Er, Tm, and Yb) and Mg(Gd_xYb_1?x)₂S₄ were prepared by solid-state reactions. All the cadmium-containing compounds are cubic, i.e., the Th₃P₄ structure for Gd, Tb, and Dy and the spinel type for all the others. The first three compounds were deficient in CdS. In the case of the Mg system, for x = 1 the system is cubic Th₃P₄, for x = 0 cubic spinel, and for 0 < x < 1 orthorhombic MnY₂S₄ (Cmc2₁). All the materials studied are paramagnetic above 77 K. Below 77 K in the magnesium family both cubic materials are paramagnetic down to 4.2 K and the orthorhombic materials show magnetic ordering. In the cadmium family all but CdTm₂S₄ show exchange coupling.     

Fast sequential multi-element determination of Ca,Mg, K,Cu, Fe,Mn and Zn for foliar diagnosis using high-resolution continuum source flame atomic absorption spectrometry: Feasibility of secondary lines,side pixel registration and least-squares background correction

The fast sequential multi-element determination of Ca, Mg, K, Cu, Fe, Mn and Zn in plant tissues by high-resolution continuum source flame atomic absorption spectrometry is proposed. For this, the main lines for Cu (324.754 nm), Fe (248.327 nm), Mn (279.482 nm) and Zn (213.857 nm) were selected, and the secondary lines for Ca (239.856 nm), Mg (202.582 nm) and K (404.414 nm) were evaluated. The side pixel registration approach was studied to reduce sensitivity and extend the linear working range for Mg by measuring at wings (202.576 nm; 202.577 nm; 202.578 nm; 202.580 nm; 202.585 nm; 202.586 nm; 202.587 nm; 202.588 nm) of the secondary line. The interference caused by NO bands on Zn at 213.857 nm was removed using the least-squares background correction. Using the main lines for Cu, Fe, Mn and Zn, secondary lines for Ca and K, and line wing at 202.588 nm for Mg, and 5 mL min^− 1 sample flow-rate, calibration curves in the 0.1–0.5 mg L^− 1 Cu, 0.5–4.0 mg L^− 1 Fe, 0.5–4.0 mg L^− 1 Mn, 0.2–1.0 mg L^− 1 Zn, 10.0–100.0 mg L^− 1 Ca, 5.0–40.0 mg L^− 1 Mg and 50.0–250.0 mg L^− 1 K ranges were consistently obtained. Accuracy and precision were evaluated after analysis of five plant standard reference materials. Results were in agreement at a 95% confidence level (paired t-test) with certified values. The proposed method was applied to digests of sugar-cane leaves and results were close to those obtained by line-source flame atomic absorption spectrometry. Recoveries of Ca, Mg, K, Cu, Fe, Mn and Zn in the 89–103%, 84–107%, 87–103%, 85–105%, 92–106%, 91–114%, 96–114% intervals, respectively, were obtained. The limits of detection were 0.6 mg L^− 1 Ca, 0.4 mg L^− 1 Mg, 0.4 mg L^− 1 K, 7.7 µg L^− 1 Cu, 7.7 µg L^− 1 Fe, 1.5 µg L^− 1 Mn and 5.9 µg L^− 1 Zn.     

A pilot study for the production of a certified reference material for trace elements in honey

In the context of the general mandate of the European Union Community Reference Laboratory (CRL) for residues in living animals and their products established at the Istituto Superiore di Sanità, a pilot study was undertaken to assess the possibility of producing a new certified reference material (CRM) for trace elements in a matrix of honey. The elements considered were As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sn, V and Zn. Their determination was performed by inductively coupled plasma (ICP)-based techniques. Data obtained with different ICP techniques were generally in good agreement. In light of these results, the next step was the effective production of a candidate CRM in a honey matrix. In the preliminary phase, two different types of honey, i.e., Eucalyptus (solid and sticky) and Robinia (viscous and sticky), were pretreated at the Institute for Reference Materials and Measurements, Joint Research Centre, European Commission (EC-JRC-IRMM) in order to produce the materials candidate for the certification process. Approximately 600 ampoules were thus produced for the Robinia honey and 450 ampoules for the Eucalyptus honey, each ampoule containing 5 g of an aqueous solution of honey (with 20% and 30% high purity water, respectively) and sealed under inert gas (Ar). A ring test to determine the levels of the chemical elements and a long-term study to evaluate the stability of the samples is in progress. Tentative figures for the analytes of interest are (in ng g⁻¹): Robinia, As, 1.28±0.09; Cd, 0.59±0.08; Cr, 2.36±0.21; Cu, 57.6±3.2; Fe, 209±9; Mn, 90.8±3; Ni, 18.1±0.6; Pb, 23±1.5; Sn, 8.10±0.35; V, 1.19±0.37; and Zn, 178±4; Eucalyptus, As, 3.18±0.21; Cd, 0.70±0.08; Cr, 2.73±0.22; Cu, 141±6; Fe, 926±16; Mn, 1905±81; Ni, 7.77±0.4; Pb, 138±4; Sn, 7.97±0.16; V, 3.47±0.15; and Zn, 405±9.     

Anionic high-temperature conduction in single crystals of nonstoichiometric phases R1 ? y M y F3 ? y (R = La-Lu, M = Ca, Sr, Ba) with the tysonite (LaF3) structure

Electrophysical properties of single crystals of nonstoichiometric phases R_{1 − y} M _y F_{3 − y} , where R = La-Lu, M = Ca, Sr, or Ba, with the tysonite (LaF₃) structure, which are present in a metastable state after being grown and cooled, are measured in the temperature interval extending from 300 to 1073 K. It is discovered that, during a sufficiently long high-temperature investigation, solid solutions R_{1 − y} Ca _y F_{3 − y} , where R = Tb, Dy, or Ho, undergo irreversible variations in the phase composition in the temperature region 723 to 823 K. This level of temperatures, which correspond to partial decomposition of phases R_{1 − y} Ca _y F_{3 − y} with the rare-earth elements of the end of the period, lies above the temperatures to which the fluoride solid electrolytes are usually heated when used in solid-state electrochemical devices. The temperature and concentration dependences of the phases’ electroconduction are explained in the framework of the vacancy mechanism of anionic transport. Original Russian Text ? N.I. Sorokin, B.P. Sobolev, 2007, published in Elektrokhimiya, 2007, Vol. 43, No. 4, pp. 420–431. The paper is dedicated to the memory of Prof. M.W. Breiter, formerly of the Vienna Technical University, Austria.     

L?sungsmitteleinflu? auf das Redoxverhalten des Hexakismethylisonitrilmangan (I) ions

The redox behaviour of hexakismethylisonitrilmanganese(I) [MnL ₆ ⁺] has been studied in acetic acid, dichloromethane, 1,2-dichloroethane, propylenecarbonate, butyrolactone, methanol, ethanol, nitromethane, acetonitrile, N-methyl-2-pyrrolidinone, dimethylformamide, dimethyl sulfoxide and water. The reversible diffusion-controlled oxidation MnL ₆ ⁺/MnL ₆ ²⁺ could be observed in all solvents studied, on both the dropping mercury electrode and the stationary platinum electrode. Employing tetrabutylammonium perchlorate as supporting electrolyte, the oxidation MnL ₆ ²⁺/MnL ₆ ³⁺ was observable only in acetic acid, nitromethane, 1,2-dichloroethane, dichloromethane, propylenecarbonate, butyrolactone and acetonitrile. In all other solvents oxidation of the solvent preceded the oxidation MnL ₆ ²⁺/MnL ₆ ³⁺. Poorly defined polarographic waves attributable to the one electron reduction of the MnL ₆ ⁺ were observed in butyrolactone, propylenecarbonate, acetonitrile, dimethylformamide, N-methyl-2-pyrrolidinone and dimethyl sulfoxide. All potential values were recorded versus bisbiphenylchromium(I)-iodide [BBCr(I)J], the problems of measuring against external aqueous reference electrodes are discussed. The redox potential of the process MnL ₆ ⁺/MnL ₆ ²⁺ was found to be a function of the donor properties of the solvents used; the effects of outer sphere coordination on the redox behaviour of this couple are discussed. No effect of the supporting electrolytes tetrabutylammonium perchlorate, tetraethylammonium nitrate and tetraethylammonium perchlorate on the redox behaviour of MnL ₆ ⁺ was found. The UV-spectrum of MnL ₆(PF₆)₂ has been recorded.     

Surface and internal modification of composite ion exchange membranes for removal of molybdate,phosphate, and nitrate from polluted groundwater

Al₂O₃/chitosan-multiwall carbon nanotubes (MWCNTs) were created to increase the exchange capacity of polyvinylidene fluoride (PVDF) ion-exchange membranes. The composite membranes were made by mixing Al₂O₃ nanoparticles into the PVDF cast solution, then applying a thin coating of chitosan functionalized carbon nano tubes (Cs-MWCNTs) to the PVDF membrane surface. The structure and characteristics of the hybrid membranes were described using XRD, SEM, IR, and TG-DTA. The Al₂O₃-PVDF/Cs-MWCNTs membrane beat the other Al₂O₃-PVDF/Cs, Al₂O₃-PVDF, and PVDF membranes in terms of molybdate, phosphate, and nitrate adsorption. The removal efficiency, pH solution, adsorption capacity, and desorption process of molybdate, phosphate, and nitrate anions by Al₂O₃-PVDF and PVDF membranes were investigated. The removal effectiveness of molybdate, phosphate, and nitrate, according to the testing findings, was 94.3, 65.6, and 85.78 %, respectively. The adsorption of MoO₄^2?, PO₄^3?, and NO₃^? increased as the pH increased initially until the best adsorption was achieved, and then decreased significantly as the pH increased further. The total adsorption capabilities of MoO₄^2?, PO₄^3?, and NO₃^?for the Al₂O₃-PVDF/Cs-MWCNTs membrane were 65.50, 61.22, and 59.77 mg/g, respectively. Using regeneration and reuse experiments for the simultaneous adsorption of molybdate, phosphate, and nitrate during three consecutive cycles, the adsorption/desorption of Al₂O₃-PVDF/Cs-MWCNTs was assessed. Al₂O₃-PVDF/Cs-MWCNTs offer a lot of promise when it comes to eliminating MoO₄^2?, PO₄^3?, and NO₃^?from actual wastewater samples.     

Chromatographische Analyse mit Papier aus Butyryl-, Benzoyl- und Phthaloylzellulose

Zusammenfassung Für die chromatographische Trennung hydrophober Substanzen werden aus Zellulosepapier unter Erhaltung der Faserstruktur Butyrylzellulose-, Benzoyl-zellulose- und Phthaloyl-zellulose-Papiere hergestellt. Sie zeichnen sich gegenüber dem früher beschriebenen Acetyl-zellulose-Papier bei verschiedenen Substanzen durch deren höhereR _f -Werte aus. Im Phthaloylpapier ist nur eine Carboxylgruppe der Phthalsäure verestert. Es eignet sich deshalb auch gut zur Basenaustauschchromatographie und ist dem Carboxyl-zellulose-Papier wegen seiner Unlöslichkeit in Lauge überlegen.

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Summary Butyrylcellulose-, benzoylcellulose-, and phthaloylcellulose papers were prepared for the Chromatographic separation of hydrophobic substances, with retention of the fiber structure of the paper. As compared with the earlier acetylcellulose paper, they are distinguished by their higherR _f values in the case of various substances. Only one of the carboxyl groups of the phthalic acid is esterified in the phthaloyl paper. Consequently, it is also well suited for base exchange chromatography, and because of its insolubility in alkalies it is superior to the carboxylcellulose paper.

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Résumé Pour la séparation chromatographique de substances hydrophobes, on a préparé des papiers à structure fibreuse, de butyrylcellulose, benzoylcellulose, phtaloylcellulose à partir de papier à la cellulose. Ils se distinguent des papiers déjà décrits à l'acétylcellulose par les valeurs duR _f plus élevées pour des substances diverses. Dans le papier phtaloyle, il n'y a qu'un groupement carboxyle de l'acide phtalique estérifié. Par conséquent, il convient aussi très bien pour la Chromatographie d'échange des bases et, à cause de son insolubilité dans les lessives alcalines, il est supérieur au papier à la carboxylcellulose.

     

Prüfung von Beugungsgittern nach dem Phasenkontrastverfahren

Zusammenfassung Als Hinweis für die Güte eines optischen Beugungsgitters gibt man gewöhnlich die in Prozenten ausgedrückte Intensität der Rowlandgeister, bezogen auf eine beliebige Spektrallinie, an. Der periodische Teilungs-fehler des Gitters, der in einer einfachen Beziehung zur Intensität der Rowlandgeisterlinie steht, gibt jedoch keine Auskunft über die Beschaffenheit bestimmter Teile des Gitters. Der Hersteller eines Gitters ist aber daran interessiert, Einzelheiten über jeden Abschnitt der Gitter-fläche zu erfahren, um so Mängel an seiner Teilmaschine zu entdecken. Für diese Untersuchungen werden interferometrische Methoden und, seit kurzer Zeit, das Phasenkontrastverfahren (PKV) nachZernike herangezogen. Nach einem Abriß über die Theorie des PKV's, die besonders einfach ist, weil es sich bei den Gittern um nur eindimensionale Objekte handelt, wird die praktische Anwendung des PKV's zur Gitterprüfung erläutert. Gewisse besondere Unregelmäßigkeiten des Gitters, z. B. Teilungssprünge, sind jedoch im Phasenkontrastbild nicht so klar ersichtlich wie in dem zum Vergleich gezeigten Interferogramm, weswegen auch zuerst die interferometrische Prüfung empfohlen wird. Zum Schluß werden die nach dem PKV und die nach der Messung der Intensität der Rowlandgeister bei einigen Gittern ermittelten periodischen Fehler gegenübergestellt.

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Summary Ordinarily, the excellence of an optical diffraction grating is expressed as the intensity of the Rowland images, expressed in percentage referred to some chosen spectral line. The periodic dividing error of the grating, which is in simple relation to the intensity to the Rowland ghost lines, however furnishes no information regarding the quality of given parts of the grating. The manufacturer of a grating is however interested in obtaining details concerning every portion of the grating surface in order to thus discover the defects of his dividing engine. Such studies are made with interferometric methods, and, in recent times, the phase contrast method ofZernike (the PKV) has been employed. After outlining the theory of PKV, which here is strikingly simple, since in the case of gratings it involves only one-dimensional objects, the practical application of PKV for the testing of gratings is explained. Certain special irregularities in the grating, for example, discontinuties in the rulings, are, however, not as clearly shown in the phase contrast picture as in the interferogram shown for comparison. For this reason, the interferometric testing is recommended first. In conclusion, the periodic errors determined by the PKV and by the intensity of the Rowland images are compared for several gratings.

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Résumé Habituellement on exprime la qualité d'un réseau de diffraction par l'intensité des fantômes deRowland, exprimée en pourcent par rapport à une raie spectrale donnée. L'erreur périodique de division du réseau qui est en relation simple avec l'intensité des fantômes deRowland, ne fournit cependant aucun renseignement sur la qualité des diverses parties du réseau. Cependant le fabricant du réseau a intérêt à obtenir des renseignements sur chaque partie de la surface gravée afin de trouver ainsi les défauts de la machine à graver. On a fait des telles études par une méthode interférométrique et plus récemment par la méthode de contraste de phase deZernicke (PKV). Après un exposé de la théorie de la méthode PKV, particulièrement simple dans le cas des réseaux, objets à une dimension, on explique la méthode PKV pratique d'essai des réseaux. Certaines irrégularités particulières du réseau, par exemple les discontinuités dans le traçage, ne sont pas aussi clairement montrées par le contraste de phase que par un interférograrnme. Pour cette raison on recommande de faire un essai interférométrique. En conclusion, on compare les erreurs périodiques déterminées pour plusieurs réseaux par la méthode PKV et par l'intensité des fantômes deRowland.

     

The small-scale titrimetric determination of complex cyanides

Summary Ferrocyanide, or ferricyanide after reduction, may be precipitated as uranyl ferrocyanide, the precipitate decomposed with alkali, and the uranium corresponding to the complex cyanide determined titrimetrically by standard methods. An alternative method, which can also be applied to cobalticyanide, is to decompose the precipitate produced with iron(II) ion, and to determine the resulting iron(III) by standard procedures. Alternatively, a known excess of iron(II) may be added, and the excess determined titrimetrically. The method may be applied to amounts of 1–100 mg of the complex ion, titrations are of the order of 1–6 ml, and relative errors over the stated range are of the order of ±2%.

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Zusammenfassung Cyanoferrat(II) oder Cyanoferrat(III), nachdem dieses reduziert wurde, lassen sich bestimmen, indem man als Uranylcyanoferrat(II) fällt, den Niederschlag mit Alkali zersetzt und die äquivalente Uranmenge nach einer Standardmethode titriert. Ein anderer Weg, der auch für die Bestimmung von Cyanokobaltat geeignet ist, führt über die Zersetzung des mit Eisen(II) erhaltenen Niederschlages und die Bestimmung des dabei entstandenen dreiwertigen Eisens nach Standardmethoden. Schließlich kann man einen gemessenen Überschuß Eisen(II) zusetzen und diesen titrieren. Das Verfahren eignet sich für 1 bis 100 mg Komplexion. Dabei werden 1 bis 6 ml Maßlösung verbraucht. Der relative Fehler beträgt ±2%.

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Résumé On peut précipiter les ferrocyanures, ou bien les ferricyanures après réduction, à l'état de ferrocyanure d'uranyle, décomposer le précipité par une base et doser par titrimétrie, au moyen de méthodes classiques, l'uranium correspondant au cyanure complexe. Une variante de la méthode, également applicable aux cobalticyanures, consiste à décomposer le précipité obtenu avec l'ion Fe-II et à doser le fer-III résultant suivant des procédés classiques. Une autre variante consiste aussi à ajouter un excès connu de fer-II et à doser l'excès par titrimétrie. On peut appliquer la méthode aux quantités de l'ordre de 1 à 100mg d'ion complexe et opérer sur 1 à 6ml environ avec des erreurs relatives de l'ordre de ±2% sur le domaine en question.

     

Gas hydrate equilibrium dissociation conditions in porous media using two thermodynamic approaches

We employ two thermodynamic approaches, based on the equal fugacities and the equal activities, to predict the gas hydrate equilibrium dissociation conditions in the porous media. The predictions are made for the hydrate systems, CH₄/H₂O, C₂H₆/H₂O, C₃H₈/H₂O, CO₂/H₂O, CH₄/CO₂/H₂O, C₃H₈/CH₄/C₂H₆/H₂O, and CH₄/CH₃OH/H₂O. For the non-hydrate phase, we used the Trebble–Bishnoi equation in the fugacity approach and the Soave–Redlich–Kwong equation in the activity approach. For the hydrate phase, the van der Waals–Platteeuw model incorporated with the capillary model of Llamedo et al. [M. Llamedo, R. Anderson, B. Tohidi, Am. Mineral. 89 (2004) 1264–1270] was used in the two approaches. The predictions are found to be in satisfactory to good agreement with the experimental data. The predictive ability of the fugacity approach is better than that of the activity approach.     

Theoretical study of substituent and solvent effects on the thermodynamics for <Emphasis Type="Italic">cis</Emphasis>/<Emphasis Type="Italic">trans</Emphasis> isomerization and intramolecular rearrangements of 2,2′-diphenoquinones

Enthalpies (Δ_isom H _(g)^o), Gibbs free energies (Δ_isom G _(g)^o), and equilibrium constants (log K _isom) for the trans → cis isomerization of various 3,3′-, 4,4′-, and 5,5′- disubstituted 2,2′-diphenoquinones with a range of electron withdrawing and releasing moieties (methyl, fluoro, chloro, bromo, trifluoromethyl, and amino) were calculated in the gas phase and in the solvent phase (n-hexane, benzene, n-octanol, acetonitrile, and water). In the gas phase, the trans isomer of the parent and all substituted 2,2′-diphenoquinones is predicted to be more thermodynamically stable than the cis configuration, with log K _isom ranging from −2.8 to −7.0. For all compounds, increasing solvent polarity/proticity progressively favors shifting the cis/trans equilibrium towards greater contributions of the cis configuration and substantially increases the log K _isom by up to 5.1 units relative to the gas phase. In polar protic and polar aprotic solvents, the estimated log K _isom ranges as low as −0.4, indicating significant populations of the cis isomers should be present. The findings support the polar solvent phase mechanistic predictions for a cis configuration of 2,2′-diphenoquinones participating in the thermal transformation of trans-2,2′-diphenoquinones to oxepino[2,3-b]benzofurans. With limited exceptions for some amino derivatives, the cis-2,2′-diphenoquinone to oxepino[2,3-b]benzofuran isomerization is expected to be thermodynamically favorable for all substituents/phases under consideration. The cis-2,2′-diphenoquinone to oxepino[2,3-b]benzofuran rearrangement is predicted to become less thermodynamically favored with increasing solvent polarity/proticity.     

Raman spectra and structural features of ClOF2 + cation in a solution of anhydrous HF

The Raman spectra of ClOF₂ ⁺ cation in solutions of anhydrous HF were studied. In the ClOF₂ ⁺HF₂ ⁻ and ClOF₂ ⁺BF₄ ⁻−HF systems, this cation exists as a pyramidal structure (C _s symmetry), while in the ClOF₂ ⁺AuF₆ ⁻−HF system, it exists as a planar structure (C _2v symmetry). Based on nonempirical calculations by the Hartree-Fock-Roothaan method, an explanation for the dependence of the structure of the ClOF₂ ⁺ cation on the nature of the anion was proposed. For the Cl−O bond vibrations, the correlation functions of vibrational and rotational relaxations were calculated, and the characteristic times of these processes were determined. The main contribution to the formation of the band contours corresponding to the above-mentioned modes is made by the vibrational dephasing. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 432–437, March, 1998.