Some features of solid propellant chemistry

Abstract is not available.

XPES studies of oxides of second- and third-row transition metals including rare earths

X-ray photoelectron spectroscopy has been employed to investigate oxides of second- and third-row transition metals, including those of rare earths. Systematics in the spin—orbit splittings and binding energies of core levels of the metals are described. In most of the cases studied, the dependence of the spin—orbit splittings on the atomic number Z is given by the relation ΔE = a(Z - Z0)4, where a is the quantum defect parameter and Z0 is the effective screening. Core-level binding energies are found to increase with the oxidation state of the metal. Most of the core-level binding energies are related to the atomic number Z by the expression E = x(Z - Z0)2, giving rise to linear plots of ln E versus ln Z. Specific features of individual oxides, with respect to satellites, multiplet structure, configuration mixing, and other properties are also discussed. The spectra of PrO2, Pr6O11, TbO2 and Tb4O7 are reported for the first time.

Predicting a new phase (T′′) of two-dimensional transition metal di-chalcogenides and strain-controlled topological phase transition

Single layered transition metal dichalcogenides have attracted tremendous research interest due to their structural phase diversities. By using a global optimization approach, we have discovered a new phase of transition metal dichalcogenides (labelled as T′′), which is confirmed to be energetically, dynamically and kinetically stable by our first-principles calculations. The new T′′ MoS2 phase exhibits an intrinsic quantum spin Hall (QSH) effect with a nontrivial gap as large as 0.42 eV, suggesting that a two-dimensional (2D) topological insulator can be achieved at room temperature. Most interestingly, there is a topological phase transition simply driven by a small tensile strain of up to 2%. Furthermore, all the known MX2 (M = Mo or W; X = S, Se or Te) monolayers in the new T′′ phase unambiguously display similar band topologies and strain controlled topological phase transitions. Our findings greatly enrich the 2D families of transition metal dichalcogenides and offer a feasible way to control the electronic states of 2D topological insulators for the fabrication of high-speed spintronics devices.

Direct estimation of an element of order matrix from H-1 NMR spectra of strongly dipolar coupled spins

NMR spectra of molecules oriented in thermotropic liquid crystalline media provide information on the molecular structure and order. The spins are generally strongly dipolar coupled and the spectral analyse require the tedious and time consuming numerical iterative calculations. The present study demonstrates the application of multiple quantum spin state selective detection of single quantum transitions for mimicking the homonuclear decoupling and the direct estimation of an element of ordering matrix. This information is utilized to estimate the nearly accurate starting dipolar couplings for iterative calculations. The studies on the spectra of strongly dipolar coupled five and six interacting spin systems are reported.

Styrene Oxidation to Benzaldehyde by Polymer Anchored Wilkinson Complex

Wilkinson complex, insolubilized by anchoring to polymeric Amberlite beads, had been used for the liquid-phase catalytic oxidation of styrene to benzaldehyde and formaldehyde in toluene medium. Styrene conversion was followed by measuring the oxygen volume in contact with the reaction mixture in a specially designed closed batch apparatus. Styrene conversion depended upon catalyst loading and distribution inside the porous beads, while temperature had little effect on it. The internal diffusional effects on the conversion process have been taken into consideration by a mathematical model which allowed calculation of effectiveness factors for various catalyst loadings and corresponding catalyst distributions. The influence of external diffusion was separately determined by plotting initial rate versus catalyst loading. The proposed method can be readily extended to immobilized enzymes in porous matrices.

Styrene Oxidation to Benzaldehyde by Polymer Anchored Wilkinson Complex

Wilkinson complex, insolubilized by anchoring to polymeric Amberlite beads, had been used for the liquid-phase catalytic oxidation of styrene to benzaldehyde and formaldehyde in toluene medium. Styrene conversion was followed by measuring the oxygen volume in contact with the reaction mixture in a specially designed closed batch apparatus. Styrene conversion depended upon catalyst loading and distribution inside the porous beads, while temperature had little effect on it. The internal diffusional effects on the conversion process have been taken into onsideration by a mathematical model which allowed calculation of effectiveness factors for various catalyst loadings and corresponding catalyst distributions. The influence of external diffusion was separately determined by plotting initial rate versus catalyst loading. The proposed method can be readily extended to immobilized enzymes in porous matrices.

Elizabeth Krakauer nee Gottschalk seated in a Oberprima (high school) chemistry laboratory; Sophienschule; Hannover, Germany.

This picture was taken during her last year of high school. The chemistry teacher, Professor Schmigielski was one of Elizabeth's favorite teachers.

Stock structure of Grey Mackerel, Scomberomorus semifasciatus (Pisces: Scombridae) across northern Australia, based on otolith stable isotope chemistry

The stable isotopes of delta O-18 and delta C-13 in sagittal otolith carbonates were used to determine the stock structure of Grey Mackerel, Scomberomorus semifasciatus. Otoliths were collected from Grey Mackerel at ten locations representing much of their distributional and fisheries range across northern Australia from 2005 to 2007. Across this broad range (similar to 6500 km), fish from four broad locations-Western Australia (S1), Northern Territory and Gulf of Carpentaria (S2, S3, S4, S5, S6, S7), Queensland east coast mid and north sites (S8, S9) and Queensland east coast south site (S10)-had stable isotope values that were significantly different indicating stock separation. Otolith stable isotopes differed more between locations than among years within a location, indicating temporal stability across years. The spatial separation of these populations indicates a complex stock structure across northern Australia. Stocks of S. semifasciatus appear to be associated with large coastal embayments. These results indicate that optimal fisheries management may require a review of the current spatial arrangements, particularly in relation to the evidence of shared stocks in the Gulf of Carpentaria. Furthermore, as the population of S. semifasciatus in Western Australia exhibited high spatial separation from those at all the other locations examined, further research activities should focus on investigating additional locations within Western Australia for an enhanced determination of stock delineation. From the issue entitled "Proceedings of the 4th International Otolith Symposium, 24-28 August 2009, Monterey, California"

Elizabeth Krakauer nee Gottschalk conducting an experiment in a Oberprima (high school) chemistry laboratory; Sophienschule; Hannover, Germany.

This picture was taken during her last year of high school. The chemistry teacher, Professor Schmigielski was one of Elizabeth's favorite teachers.

Elizabeth Krakauer nee Gottschalk seated in a Oberprima (high school) chemistry laboratory; Sophienschule; Hannover, Germany.

This picture was taken during her last year of high school. The chemistry teacher, Professor Schmigielski was one of Elizabeth's favorite teachers.

Theoretical studies of lithium bonding in lithium chloride/aliphatic amine complexes

In the systematic study of amine … LiCl [amines = NH3, CH3NH2, (CH3)2NH] complexes the possibility of an ion-pair structure and the effect of methylation on the stabilization energy is investigated. ΔEis evaluated by the SCF/4-31G method and augmented by the approximate dispersion energy calculated perturbationally. The interaction energy decreases with the increasing number of methyl groups in the amine. The dispersion energy plays a negligible role in the stabilization of complexes. None of the systems studied are ion pairs; their Li bonds are of a so-called molecular type. Due to the divergence of the multipole expansion, the attempt to correct the 4-31G stabilization energies via the electrostatic energy fails. The relative order of the ΔE in the series of complexes is verified instead in the extended basis set calculation. The lithium bonds are compared with their H-bonded analogues.

A Monte Carlo study of crystal structure transformations

The Metropolis algorithm has been generalized to allow for the variation of shape and size of the MC cell. A calculation using different potentials illustrates how the generalized method can be used for the study of crystal structure transformations. A restricted MC integration in the nine dimensional space of the cell components also leads to the stable structure for the Lennard-Jones potential.

Quantum supersymmetric generalisation of Bogomolnyi bounds

We review here classical Bogomolnyi bounds, and their generalisation to supersymmetric quantum field theories by Witten and Olive. We also summarise some recent work by several people on whether such bounds are saturated in the quantised theory.

Quest for new materials: Inorganic chemistry plays a crucial role

There is an endless quest for new materials to meet the demands of advancing technology. Thus, we need new magnetic and metallic/semiconducting materials for spintronics, new low-loss dielectrics for telecommunication, new multi-ferroic materials that combine both ferroelectricity and ferromagnetism for memory devices, new piezoelectrics that do not contain lead, new lithium containing solids for application as cathode/anode/electrolyte in lithium batteries, hydrogen storage materials for mobile/transport applications and catalyst materials that can convert, for example, methane to higher hydrocarbons, and the list is endless! Fortunately for us, chemistry - inorganic chemistry in particular - plays a crucial role in this quest. Most of the functional materials mentioned above are inorganic non-molecular solids, while much of the conventional inorganic chemistry deals with isolated molecules or molecular solids. Even so, the basic concepts that we learn in inorganic chemistry, for example, acidity/basicity, oxidation/reduction (potentials), crystal field theory, low spin-high spin/inner sphere-outer sphere complexes, role of d-electrons in transition metal chemistry, electron-transfer reactions, coordination geometries around metal atoms, Jahn-Teller distortion, metal-metal bonds, cation-anion (metal-nonmetal) redox competition in the stabilization of oxidation states - all find crucial application in the design and synthesis of inorganic solids possessing technologically important properties. An attempt has been made here to illustrate the role of inorganic chemistry in this endeavour, drawing examples from the literature its well as from the research work of my group.