Intramolecular disorder and its relation to mesophase structure in lyotropic liquid crystals

NMR SPDE measurements are reported for the lamellar (dispersions and multibilayer stacks) and hexagonal phases of sodium octanoate/octanol/D₂O mixtures. In the lamellar L_β and L_γ (gel) phases the octyl chains are rigid and perfectly ordered, while in the lamellar L_α and hexagonal phases they are flexible and disordered. In particular, the measurements show that in the fluid lamellar L_α phase, there is a marked discontinuity in the octyl chain flexibility at the C₅-C₆ segment; this behaviour is identical to that previously reported for the alkyl end-chains in smectic 4,4′-di-n-octyloxyazoxybenzene. In contrast, in the hexagonal phase, there is an effectively continuous flexibility gradient along the whole length of the octyl chain as in nematic 4,4′-di-n-octyloxyazoxybenzene. The behaviour in the lamellar phase is attributed to interference between cooperative conformational modes and localized random thermal fluctuations.     

Synthetic studies relating to acetylergosterol-(tricarbonyl)iron

Acetylergosterol(tricarbonyl)iron has been prepared in good yield using benzylideneacetone(tricarbonyl)iron. The steroidal complex may be hydroborated or subject to osmolysis, to yield potential vitamin D precursors.     

Spectroscopic and electrochemical studies of transition metal tetrasulfonated phthalocyanines: Part V. Voltammetric studies of adsorbed tetrasulfonated phthalocyanines (MTsPc) in aqueous solutions

Cyclic voltammetric measurements of adsorbed Fe- and Co-tetrasulfonated phthalocyanine (TsPc) and Co-phthalocyanine (Pc) have been carried out on ordinary pyrolytic graphite and silver electrodes at different solution pH ranging from 1 to 13. Many voltammetric peaks were found to be pH dependent with a slope of ?59 mV/ unit pH. In some instances this dependence was observed in alkaline or acid solutions only. The influence of oxygen has been also examined.     

Structural studies in main group chemistry : XV. Di- and tri-organotin arylsulphonates

An X-ray diffraction study of (2,6-dimenthylphenyl)dicyclopentadienyl-titanium has shown the two slightly staggered cyclopentadienyl ligands to be π-bonded to the titanium atom (average distance TiC 2.35 Å); the ring planes include an angle of 41.6°. The aryl ligand is σ-bonded to the titanium atom (TiC distance 2.18 Å). The short distance (2.55 Å) between Ti and one of the methyl hydrogen atoms suggests an interaction between the two atoms.     

Chronopotentiometric studies of the tetrabutylammonium ion transfer from water to 1,2-dichloroethane

Electrochemically reduced graphite in contact with tetralkylammonium ions/DMF may react with electrophiles either as a nucleophile or as a reducing reagent. The reaction at the interface or at the immediately accessible active centres of the crystal causes some modification of the structure, which is studied here. This method allows the formation of polybutylated or poly-carboxylated graphite and may lead to other modified crystals of great interest for building modified electrodes.     

Esca studies on the structure of amorphous addition complexes of tin dichloride with aromatic schiff bases

The ESCA characterization of three similar new amorphous addition complexes of tin dichloride with tetradentate aromatic Schiff bases has been carried out. The results support the previously proposed ionic structure.     

Molecularly adsorbed oxygen on metals: electron spectroscopic studies

Oxygen is shown to adsorb molecularly on gold as well as on Ag and Pt. UV and X-ray photoelectron spectroscopy and Auger electron spectroscopy have been employed to investigate electron states of molecularly adsorbed oxygen.     

Linewidths and line shapes in solid state ESCA studies: Electric field gradient broadening of Sn 3d lines

ESCA Sn 3d linewidths of nonconducting organometallic tin solids, prepared by in situ evaporation, are within about 10% of the values for analogous gas phase measurements. The similar line shapes (≈ 35% gaussian, 65% lorentzian) observed for solid state and gas phase spectra show that effects which give increasing gaussian components, such as charge broadening and phonon broadening, are very small in our solid state spectra. The general correlation between ESCA Sn 3d linewidths and Mössbauer quadrupole splittings indicates that electric field gradient splitting of the Sn 3d lines approaches ≈ 0.4 eV.     

Solvent extraction studies of cobalt in aqueous thiocyanate solutions using Aliquat-336

Cobalt ions in aqueous thiocyanate solution react with Aliquat-336-xylene solution to form anion-association complex which is easily extracted into the organic phase. A typical extraction procedure involves extracting a solution which is 10 ppm in cobalt and 0.06 M,

5. Stripping of Cobalt from 2% Aliquat-336-Xylene Solutions

     

13.

Preparation and X-ray diffraction studies of curium hydrides     

J.K. Gibson  R.G. Haire 《Journal of solid state chemistry》1985,59(3):317-323

Curium hydrides were prepared by reaction of curium-248 metal with hydrogen and characterized by X-ray powder diffraction. Several of the syntheses resulted in a hexagonal compound with average lattice parameters of a₀ = 0.3769(8) nm and c₀ = 0.6732(12) nm. These products are considered to be CmH_3?δ by analogy with the behavior of lanthanide-hydrogen and lighter actinide-hydrogen systems. Face-centered cubic products with an average lattice parameter of a₀ = 0.5322(4) nm were obtained from other curium hydride preparations. This parameter is slightly smaller than that reported previously for cubic curium dihydride, CmH_2+x (B. M. Bansal and D. Damien, Inorg. Nucl. Chem. Lett., 6, 603, 1970). The present results established a continuation of typical heavy trivalent lanthanide-like behavior of the transuranium actinide-hydrogen systems through curium.     

14.

Surface studies with the vacuum microbalance     

A.W. Czanderna 《Thermochimica Acta》1978,24(2):345-358

This paper is generally concerned with presenting a broad overview of the capabilities, limitations, and potential uses of the vacuum ultramicrobalance for surface studies. Determination of micromass changes of samples in vacuum and controlled gaseous environments at various temperatures is one of the powerful methods for studying surfaces. The traditional application of the vacuum microbalance and accompanying theoretical foundation for obtaining surface areas, activation energies of adsorption and desorption, the heat of adsorption and the initial stages of oxidation are reviewed. As with most physical measurements, the simultaneous measurement of mass change and other parameters greatly increases the ability to understand physical and chemical processes. Examples of the combined measurement of residual gases, infrared spectroscopy, and electrical properties as well as the mass change are presented. Recent progress in developing an automated ultramicrobalance for operation in a UHV system combined with RGA and AES is discussed. Information about specific gas—solid systems is presented to illustrate the utility of the microbalance.     

15.

Application of Mössbauer spectroscopy in pyritic and copper calcines studies     

R. Dimitrov  A. Hekimova 《Thermochimica Acta》1980,40(3):349-355

In the present study, Mössbauer spectroscopy is applied to the qualitative and quantitative investigation of pyritic and copper calcines prepared by the roasting of untreated concentrates and those which have received a preliminary treatment in a magnetic field. It was established that there are no significant differences in phase content between those calcines which have received a preliminary treatment and those which have not.

New phases were found in copper calcines depending on the intensifying factor applied.     

16.

Thermal studies of Zn(II) hydrazine complexes in the solid state     

B. Banerjee  A. Ghosh  N.Ray Chaudhuri 《Thermochimica Acta》1983,71(3):273-280

The synthesis and characterization of ZnL_nX₂ · mH₂O, where L = N₂H₄; n = 3, 2 and 1.5; X = Cl^?, Br^? and $\text{1}\text{2}$SO^2?₄; and m = 0 or 1, have been done and their thermal studies have been carried out using a Shimadzu DT-30 Thermal Analyzer. ZnL₃SO₄, ZnL_2.75SO₄, ZnL₂SO₄, ZnLCl₂ and ZnL_0.5Cl₂ have been synthesized pyrolytically in the solid state from their parent complexes synthesized from solution. Two varieties of ZnL₂Cl₂ synthesized by us are indistinguishable by IR spectroscopy but possess appreciable differences in their thermal profiles. Two forms of ZnL₃SO₄ which are also indistinguishable by IR spectroscopy show noticeable differences in their thermal profiles.     

17.

Inelastic collisions of Li with N₂-molecules: A comparison of experimental results with trajectory studies     

D. Poppe  R. Bttner 《Chemical physics》1978,30(3):375-386

Rotationally and vibrationally inelastic collisions between Li⁺-ions and N₂-molecules have been investigated in a classical trajectory study. C     

18.

Mössbauer spectroscopic studies of magnesium nickel ferrites     

K. Seshan  A.S. Bommannavar  D.K. Chakrabarty 《Journal of solid state chemistry》1983,47(1):107-112

Mössbauer spectra of magnesium nickel ferrites having spinel structure with varying percentages of nickel were obtained at room temperature. The split extreme high-resonance line could be resolved into two Lorentzians from which the cation distribution was calculated. The calculated cation distributions match very well with those obtained from magnetization measurements as well as from ferromagnetic resonance studies on the same samples. The observed quadrupole split and the hyperfine field values can be rationalized based on the obtained cation distributions.     

19.

A spline-fitted potential surface for bent triatomic molecules     

Stephen K. Gray  James S. Wright  Xavier Chapuisat 《Chemical physics letters》1977,48(1):155-157

The rotated-Morse curve cubic spline method developed previously is extended to bent triatomic molecules by using 2D cubic spline. The Yates—Lester potential for bent H₃ is shown to be accurately fitted over the entire range of the three internal coordinates, with a standard deviation of less than 1 kcal mol^?1. The spline method compares favorably in computational speed with the analytical potential.     

20.

Positronium annihilation studies of polycarbonate,polyethersulphone and polysulphone     

B.D. Malhotra  R.A. Pethrick 《European Polymer Journal》1983,19(6):457-459

Positron annihilation studies are reported on polycarbonate polyethersulphone and polysulphone over the temperature range 260–370 K. The data were analysed into three components, the longest lifetime-o-component is associated with the pick-off mechanism; a linear variation of that component with temperature was observed. Using ultrasonic velocity data, the free volume distribution was calculated; its magnitude and temperature dependence are discussed in relation to the mechanical properties of the polymer.     

Strippant	Cobalt stripped (%)
Na2S (M) 1.0	18.3
2.0	10.7
Na2SO3 (M) 0.1	10.7
0.5	49.6
1.0	52.9
EDA (%) 2.5	76.6
NaOH (M) 0.1	4.1
0.5	74.1
1.0	90.8
2.0	76.8
NH4OH (M) 0.1	24.1
0.5	91.8
1.0	97.5
2.0	99.9
EDTA (M) 0.02	>99.9
0.05	>99.9
0.1	>99.9
EDTA (%) 0.1	>99.9
0.5	>99.9
1.0	>99.9

Preparation and X-ray diffraction studies of curium hydrides

Curium hydrides were prepared by reaction of curium-248 metal with hydrogen and characterized by X-ray powder diffraction. Several of the syntheses resulted in a hexagonal compound with average lattice parameters of a₀ = 0.3769(8) nm and c₀ = 0.6732(12) nm. These products are considered to be CmH_3?δ by analogy with the behavior of lanthanide-hydrogen and lighter actinide-hydrogen systems. Face-centered cubic products with an average lattice parameter of a₀ = 0.5322(4) nm were obtained from other curium hydride preparations. This parameter is slightly smaller than that reported previously for cubic curium dihydride, CmH_2+x (B. M. Bansal and D. Damien, Inorg. Nucl. Chem. Lett., 6, 603, 1970). The present results established a continuation of typical heavy trivalent lanthanide-like behavior of the transuranium actinide-hydrogen systems through curium.     

Surface studies with the vacuum microbalance

This paper is generally concerned with presenting a broad overview of the capabilities, limitations, and potential uses of the vacuum ultramicrobalance for surface studies. Determination of micromass changes of samples in vacuum and controlled gaseous environments at various temperatures is one of the powerful methods for studying surfaces. The traditional application of the vacuum microbalance and accompanying theoretical foundation for obtaining surface areas, activation energies of adsorption and desorption, the heat of adsorption and the initial stages of oxidation are reviewed. As with most physical measurements, the simultaneous measurement of mass change and other parameters greatly increases the ability to understand physical and chemical processes. Examples of the combined measurement of residual gases, infrared spectroscopy, and electrical properties as well as the mass change are presented. Recent progress in developing an automated ultramicrobalance for operation in a UHV system combined with RGA and AES is discussed. Information about specific gas—solid systems is presented to illustrate the utility of the microbalance.     

Application of Mössbauer spectroscopy in pyritic and copper calcines studies

In the present study, Mössbauer spectroscopy is applied to the qualitative and quantitative investigation of pyritic and copper calcines prepared by the roasting of untreated concentrates and those which have received a preliminary treatment in a magnetic field. It was established that there are no significant differences in phase content between those calcines which have received a preliminary treatment and those which have not.

New phases were found in copper calcines depending on the intensifying factor applied.     

Thermal studies of Zn(II) hydrazine complexes in the solid state

The synthesis and characterization of ZnL_nX₂ · mH₂O, where L = N₂H₄; n = 3, 2 and 1.5; X = Cl^?, Br^? and $\text{1}\text{2}$SO^2?₄; and m = 0 or 1, have been done and their thermal studies have been carried out using a Shimadzu DT-30 Thermal Analyzer. ZnL₃SO₄, ZnL_2.75SO₄, ZnL₂SO₄, ZnLCl₂ and ZnL_0.5Cl₂ have been synthesized pyrolytically in the solid state from their parent complexes synthesized from solution. Two varieties of ZnL₂Cl₂ synthesized by us are indistinguishable by IR spectroscopy but possess appreciable differences in their thermal profiles. Two forms of ZnL₃SO₄ which are also indistinguishable by IR spectroscopy show noticeable differences in their thermal profiles.     

Inelastic collisions of Li with N2-molecules: A comparison of experimental results with trajectory studies

Rotationally and vibrationally inelastic collisions between Li⁺-ions and N₂-molecules have been investigated in a classical trajectory study. C     

Mössbauer spectroscopic studies of magnesium nickel ferrites

Mössbauer spectra of magnesium nickel ferrites having spinel structure with varying percentages of nickel were obtained at room temperature. The split extreme high-resonance line could be resolved into two Lorentzians from which the cation distribution was calculated. The calculated cation distributions match very well with those obtained from magnetization measurements as well as from ferromagnetic resonance studies on the same samples. The observed quadrupole split and the hyperfine field values can be rationalized based on the obtained cation distributions.     

A spline-fitted potential surface for bent triatomic molecules

The rotated-Morse curve cubic spline method developed previously is extended to bent triatomic molecules by using 2D cubic spline. The Yates—Lester potential for bent H₃ is shown to be accurately fitted over the entire range of the three internal coordinates, with a standard deviation of less than 1 kcal mol^?1. The spline method compares favorably in computational speed with the analytical potential.     

Positronium annihilation studies of polycarbonate,polyethersulphone and polysulphone

Positron annihilation studies are reported on polycarbonate polyethersulphone and polysulphone over the temperature range 260–370 K. The data were analysed into three components, the longest lifetime-o-component is associated with the pick-off mechanism; a linear variation of that component with temperature was observed. Using ultrasonic velocity data, the free volume distribution was calculated; its magnitude and temperature dependence are discussed in relation to the mechanical properties of the polymer.