Synthesis and characterization of molybdenum disulphide formed from ammonium tetrathiomolybdate

An investigation has been carried out into the possibility of in situ formation of MoS2 within porous anodic films on aluminium, to improve subsequent tribological behaviour, by re-anodizing in thiomolybdate electrolyte. Acidification of thiomolybdate was employed to simulate the conditions for formation of the sulphide at the anodic film/electrolyte interface, followed by appropriate vacuum heat treatments to study possible temperature effects on the sulphide due to either friction or Joule heating during anodizing. The products of both acidification and heat treatment, characterized by X-ray powder diffraction and scanning electron microscopy, were compared with those formed by direct thermal decomposition of ammonium tetrathiomolybdate crystals. The precipitate formed by acidification was mainly amorphous molybdenum trisulphide (MoS3), which on heat treatment at 450 and 850°C yielded 3R-MoS2. 3R-MoS2 also formed by the thermal decomposition of thiomolybdate crystals. Thermogravimetric and differential thermal analyses showed that the decomposition of MoS3 to MoS2 occurred in the range 220–370°C and revealed the sequence of reaction steps. The findings suggest that mainly amorphous MoS3 is formed as a consequence of changes in the pH of the film/electrolyte interface during re-anodizing but the product is relatively easily transformed to crystalline MoS2 on moderate heating which may occur during wear processes.     

Corrosion of Lead Glasses in Acid Media: I, Leaching Kinetics

The leaching kinetics of lead glasses (25 to 35 mol% PbO-75 to 65 mol% SiO₂; some with K₂O and A1₂O₃, additions) were determined in 10% acetic acid. Except for a ternary glass (SiO₂-PbO-K₂O) which had a linear dependence on time, all compositions exhibited a linear dependence on the square root of time for the amount of Pb and K removed. Increasing the SiO₂: PbO ratio or the Al₂O₃ content improved the durability whereas adding K₂O to a binary PbO-Si0₂ glass greatly increased the corrosion rate. Activation energies for the rates of Pb and K removal were determined for three compositions and it was deduced that the diffusion of H⁺ controlled the leaching for binary and 4-component glasses whereas dissolution of the silica network was rate-controlling for the ternary.     

Soil moisture estimation over grass-covered areas using AIRSAR

An empirical study of the relation between the AIRSAR's signals and land surface parameters is conducted using data collected during MACEUROPE' 91. General additive regression models are fitted to the data simulated from a calibrated microwave backscattering model. A comparison between the model predictions and field observations indicates that the regression models are good predictors to the AIRSAR's signals over the grass-covered areas. Based on the regression relationships, a soil moisture retrieval algorithm combining the Lvband multi-polarization AIRSAR data is proposed and used to create spatial soil moisture maps of the Slapton Wood catchment.     

Morphological Studies on Amaranthus cruentus

The morphology of Amaranthus cruentus was studied using scanning election and light microscopy. The A. cruentus seed consists of a single layer of cells which is intimately associated with the perispeim. In the region of the embryo, the seed coat is attached to the endosperm remaining in the mature seed. The major portion of endosperm caps the root. Large, thick-walled endosperm cells contain spherical bodies embedded in a spongy matrix. The cells of the campylotropous embryo contain material which has properties typical of lipid and lipid complexes as demonstrated by hexane extraction and by staining with osmium tetroxide. Spherical cell bodies, embedded in the lipid-containing matrix are partially digested by trypsin, thus suggesting they are proteinaceous in nature. Perisperm in the center of the seed contains starch granules in the form of amylopectin, demonstrated by iodine-potassium iodide stain and α-amylase digestion.     

Comparison of Solid-State Microwave Annealing with Conventional Furnace Annealing of Ion-Implanted SiC

Rapid solid-state microwave annealing was performed for the first time on N⁺-, Al⁺-, and B⁺-implanted SiC, and the results were compared with the conventional furnace annealing. For microwave annealing, temperatures up to 2,000 °C were attained with heating rates exceeding 600 °C/s. An 1,850 °C/35 s microwave anneal yielded a root-mean-square (RMS) surface roughness of 2 nm, which is lower than the 6 nm obtained for 1,500 °C/15 min conventional furnace annealing. For the Al implants, a minimum room-temperature sheet resistance (R _s ) of 7 kΩ/□ was measured upon microwave annealing. For the microwave annealing, Rutherford backscattering (RBS) measurements indicated a better structural quality, and secondary-ion-mass-spectrometry (SIMS) boron implant depth profiles showed reduced boron redistribution compared to the corresponding results of the furnace annealing.     

Laboratory and Pilot Scale Recovery of Protein from Mechanically Separated Chicken Residue

Bone residue resulting from mechanical deboning of chicken backs and necks was subjected to alkali extraction followed by acid precipstation to recover food grade protein. A laboratory study of effects of varying die size in the grinding of the starting material, of extraction temperature, and of g-force during centrifugation on composition of process fractions was conducted. Grinding increased ash content, higher temperature reduced fat content, and increasing centrifugal force decreased ash content, of the final products. Effects of grinding, extraction temperature, and centrifugal type were also studied on a pilot scale. Final protein product yield was higher at a 22°C than at a 3–7°C extraction temperature, and less fat was incorporated using a basket centrifuge than with a horizontal decanter centrifuge.     

{7 6 6} Oriented V-groove surfaces on Br2–CH3OH etched (1 0 0) GaAs wafers

Etched V-grooves on (1 0 0) gallium arsenide crystal surfaces produced using various compositions of bromine-in-methanol etchant are bounded by sidewall surfaces, presumably of Ga atoms, aligned along the original {7 6 6} position of the bulk crystal as determined by optical and electron microscope observations. The measurements are tentatively explained by rotational surface reconstruction of Ga-deficient, rehybridized {1 1 1} planes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of Sulfanilamide on the TBA Values of Cured Meats

The effect of sulfanilamide addition on the TBA numbers of meats cured with 0 - 200 ppm levels of sodium nitrite has been investigated. Results indicate that the TBA numbers of meats cured with 100 - 200 ppm level were always larger when sulfanilamide was present than in its absence. However, at low levels of 0 - 50 ppm sodium nitrite the TBA values were always lower in the presence of sulfanilamide. This effect is substantial and has apparently not been observed before. A possible explanation has been put forward. In all cases a distillation method was employed to evaluate TBA numbers.