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.     

Stability of Aqueous α-Al2O3 Suspensions with Poly(methacrylic acid) Polyelectrolyte

Stability of aqueous α-Al₂O₃ suspensions with Na⁺ salt of poly(methacrylic acid) (PMAA-Na) polyelectrolyte was studied as a function of pH. At a given pH, the transition from the flocculated to the dispersed state corresponded to the adsorption saturation limit of the powders by the PMAA. As the pH was decreased, the adsorption saturation limit increased until insolubility and charge neutralization of the PMAA was approached. The critical amount of PMAA required to achieve stability is outlined in a stability map.     

STATE ANTIPREDATORY LENDING LAWS AND NEIGHBORHOOD FORECLOSURE RATES

ABSTRACT: In this study, we examine the impact of state antipredatory lending laws (APLs) on neighborhood foreclosure and delinquency rates using a set of panel data regression models. We find strong evidence that neighborhoods have lower default rates in states with laws that extended federal coverage and/or restricted more mortgage contract terms, in states with broader coverage of subprime loans with high points and fees, and in states with more restrictive regulations on prepayment penalties. A typical APL lowers neighborhood default rates by between 3.8% and 18%, depending on the default risk measure considered. The findings remain consistent when we restrict the analysis to cross‐border neighborhoods, suggesting that they are not due solely to unobservable market variation.     

The shelf-life of dairy products: 2. Raw milk and fresh products

In the second of this series of articles, the specific factors controlling the shelf-life of raw milk, pasteurized milk and cream, cottage cheese and yogurt are considered. The shelf-life of raw milk depends on the quality of the milk ex-farm and on subsequent transport and storage conditions. Shelf-life may be enhanced by deep cooling or thermization. Post heat treatment contamination by Gram negative psychrotrophic bacteria is the major determinant of shelf-life of pasteurized products. In cultured dairy products, yeast and mould contamination is the most usual cause of spoilage.     

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.     

SOLUBILITY OF CO2AND H2S IN A MIXED SOLVENT

Mixed solvents are a combination of chemical and physical solvents and have some advantages over traditional treating solvents for the removal of acid gases from gas streams. The solubility of H₂S and CO₂in a mixed solvent consisting of AMP (2-amino-2-methyl-l-propanol), sulfolane, and water has been measured at 40 and 100°C at partial pressures of the acid gas to 6000 kPa. The solubility in the mixed solvent was compared with the solubility in an aqueous solution of equivalent amine concentration. At solution loadings less than 1 mol acid gas/mol amine, the solubility of the acid gas is lower in the mixed solvent than in the corresponding amine solvent. At higher loadings, the trend is reversed and the solubility is greater in the mixed solvent. The results are rationalized in terms of the effect of the physical solvent component on the chemical reaction and physical vapor-liquid equilibria. The solubility model of Deshmukh and Mather was used to correlate the data.     

The shelf-life of dairy products: 3. Factors influencing intermediate and long life dairy products

In this, the third part of a series of four reviews, the factors -which control the shelf-life of long and intermediate life dairy products are discussed. Two distinct types of product degradation are addressed. Firstly, the degradative potential of heat-resistant lipase, protease and phospholipase, derived from psychrotrophic bacteria commonly found in refrigerated milk, is examined. Secondly, the chemical composition of milk is reviewed and lipid oxidation, calcium induced aggregation of milk protein and Maillard reaction are identified as likely routes to product spoilage. The relative importance of these reactions to specific products will be discussed in the final part of this series of articles.     

COUNTERCONDITIONING THERAPY USING FREE ASSOCIATION: A PILOT STUDY.

DESCRIBES THE TREATMENT OF 2 SEVERELY NEUROTIC PATIENTS BY DESENSITIZATION USING FREE ASSOCIATION IN CONJUNCTION WITH MUSCLE RELAXATION. THIS THERAPY USED NO PREPLANNED FEAR HIERARCHIES; RATHER, THE SS SELECTED THEIR OWN MATERIAL AND THE RATE AT WHICH THEY DEALT WITH THAT MATERIAL IN EACH SESSION. PROCEDURES FOR TEACHING MORE EFFECTIVE INTERPERSONAL BEHAVIOR WERE USED WITH BOTH SS FOLLOWING COMPLETION OF COUNTERCONDITIONING. IN BOTH CASES, THE RATE OF IMPROVEMENT DURING COUNTERCONDITIONING WAS AT LEAST AS RAPID AS THAT REPORTED FOR COUNTERCONDITIONING USING HIERARCHIES OF SCENES. THE USE OF FREE ASSOCIATION OFFERS IMPORTANT ADVANTAGES WHERE AN S'S SOURCES OF ANXIETY ARE DIFFICULT TO ISOLATE AND SCALE FOR INTENSITY. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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.     

Global estimates from confusion matrices A reply to Jupp

Abstract

This Letter takes the form of a reply to Jupp (1989). It claims that Jupp's alternative direct method of deriving global estimates from confusion matrices is not generally valid, and it comments on some other issues highlighted by Jupp.