The high-energy physicistʼs guide to MathLink

MathLink is Wolfram Research?s protocol for communicating with the Mathematica Kernel and is used extensively in their own Notebook Frontends. The Mathematica Book insinuates that linking C programs with MathLink is straightforward but in practice there are quite a number of stumbling blocks, in particular in cross-language and cross-platform usage. This write-up tries to clarify the main issues and hopefully makes it easier for software authors to set up Mathematica interfacing in a portable way.     

Canadian Field Soils I. Mineral Composition by XRD/XRF Measurements

Forty Canadian soils were laboratory tested for the presence of quartz and other minerals using X-ray diffraction/X-ray fluorescence techniques. On average, the highest quartz content was observed in soil samples from sites in Nova Scotia followed by Prince Edward Island sites, whereas soil sample from British Columbia sites had the lowest quartz content. The second most abundant mineral was albite that mainly occurred in soil samples from Ontario and Quebec sites. Illite was the third most abundant and prevailed in soils mainly from British Columbia and New Brunswick sites. Soil samples from British Columbia sites had the highest combined clay and silt content and were composed of illite, albite, kaolinite, and chlorite. The lowest clay content was found in the samples from the Quebec sites. The highest microcline (a potassium feldspar) content was observed in Quebec, Ontario, and Prince Edward Island sites. In contrast to other provinces, samples from Quebec and Ontario sites also included amphibole. Soil samples from Saskatchewan and Manitoba sites also comprised carbonates, i.e., calcite and dolomite. Iron oxides (e.g., goethite) were present in all soils, except the Quebec sites, but their occurrence was rather insignificant.     

Purification of cadmium by selective volatilization in vacuum in presence of oxide phase on its melt

Purification of cadmium in the presence of a thin (~0·001?mm) oxide layer on the surface of the molten metal was carried out using a simple system designed and fabricated locally. The analytical results revealed that the distillation through oxide layer gave better separation for Co, Ni, Cu, Zn, Ag, Sn, Hg and Tl, when compared to the distillation without oxide layer. This was attributed due to the impurity metal oxide phases formation on the surface of the molten metal. The influence of oxygen flow time on the distillation rate of cadmium was established. There was no excess oxygen (O) retained in the distillate after two consecutive vacuum distillations through oxide route. The experiments were conducted at the level of nearly 1·5?kg a batch to study the impurities behaviour due to upscaling. The detailed chemical analysis of 58 impurity elements in Cd in presence and absence of oxide layer was carried out by glow discharge mass spectrometry (GDMS).     

Thermal cis–trans conversion in thiophene oligomers

Thermal cis–trans conversion has been examined in oligothiophene single molecules encapsulated in the molecular vessels of cyclodextrin and Na-mordenite. At high temperatures, optical absorption intensities are enhanced in bithiophene, terthiophene and quinquethiophene, while the intensity of quarterthiophene is temperature independent. Optical absorption comes from uncompensated transition dipole moment due to the thermal torsion between cis and trans forms.     

Characterization of Sulfur Distribution in Ni-Based Superalloy and Thermal Barrier Coatings After High Temperature Oxidation: A SIMS Analysis

Sulfur segregation was characterized by secondary ion mass spectrometry (SIMS) in uncoated single-crystal Ni-based AM1 superalloys with various S contents and on NiPtAl, NiAl and NiPt bondcoats of complete TBC systems. In spite of technical difficulties associated with diffuse sputtered interfaces, an original sample preparation technique and a careful choice of analysis conditions enabled a chemical characterization of S distribution below metal/oxide interfaces. An initial heterogeneous distribution of S in as-received high S (3.2 ppmw) AM1 was measured. After oxidation, a S depletion profile formed, with a slope that depended on the initial bulk S content. GDMS measurements enabled a quantitative distribution of S in oxidized low S (0.14 ppmw) AM1 to be constructed and discussed in relation to equilibrium surface segregation of S on Ni. The quantity of S integrated in the thermally grown oxide (TGO) was estimated and found to be very similar to that measured from depletion found in the metal. Localized S enrichments in Pt-containing coatings are related to a possible beneficial trapping mechanism of Pt on the adherence of oxide scales.     

Structural peculiarities of Bi,Pb-2223/Ag composites annealed in an N<Subscript>2</Subscript>-O<Subscript>2</Subscript> atmosphere

X-ray diffraction analysis, transmission and scanning electron microscopy, and electron microprobe analysis were used to study Bi,Pb-2223/Ag composites annealed in a low-oxygen atmosphere (7.5% O₂ + 92.5% N₂). The ceramics was found to be characterized by some nonuniformity in the distribution of all the components. Two structural peculiarities of the 2223 phase were found. These are the existence of atomic displacement waves, which are related to the oxygen deficiency or nitrogen substitution for oxygen, and a more intense Ag penetration into the ceramics, which results from the annealing in the O₂-N₂ atmosphere at a pressure of 10 atm. The unstable state of the lattice characterized by oxygen atomic displacement waves is due to the prolonged annealing in oxygen-depleted atmosphere. Usually, in the case of other favorable factors of the ceramics structure, the lattice instability positively affects the superconducting properties of the ceramics.     

On the strength of polycrystalline tungsten monocarbide

The paper consists of analytical and applied parts. The mathematical means of mechanics of hexagonal polycrystals are used in the former. Here the correspondence of the published data on single crystal elastic constants of tungsten monocarbide to elasticity moduli of polycrystalline WC has been analyzed. The relationship between ultimate tensile stress and ultimate compressive stress of polycrystalline tungsten monocarbide has been established too. The dependence of ultimate tensile stress and ultimate compressive stress of polycrystalline tungsten monocarbide on mean grain diameter is considered in the applied part. Here the available experimental data are used.     

Multi-displacement continuum model for discrete systems

A first-order multi-displacement microstructure continuum model is introduced to represent a discrete diatomic lattice system. This model is developed based on a two-term Taylor series expansion of the local displacement of the lattice. It is found that the multi-displacement continuum model obtained by keeping two terms in the Taylor series yields, in general, a better representation of the lattice system than the effective modulus model. However, this microstructure continuum model cannot characterize the negative group velocity of an optical mode of harmonic wave motion in the diatomic lattice. To capture the negative group velocity, a higher-order multi-displacement continuum model is necessary.     

An automated dilatometric system

A setup for studying dilatometric characteristics of metals and alloys in a 20 to 1350°C temperature range in vacuum or an inert gas medium is described. The built-in mass spectrometer is intended to monitor the composition and dynamics of gas release in the process of sample heating. Results obtained during sintering powdered compacts from titanium hydride are given.