Determination of silicon,phosphorus and sulfur in alloy steel by neutron activation analysis

Silicon, phosphorus, and sulfur in alloy steel were determined by neutron activation analysis involving rapid radiochemical separation procedures. The standard deviations for silicon, phosphorus, and sulfur were 1.6%, 2.3%, and 2.4% respectively; the sensitivity limits were 3.2, 0.20, and 2.50 p.p.m., respectively. The three constituents could be determined in alloy steel within 2 h of the irradiation.     

Spectrophotometric study of the formation of adducts between U(TTA)4 and some neutral organo sulphoxide donors

Adduct formation between U(TTA)₄ and neutral organosulphoxide donors dibenzyl sulphoxide (dbso), dimethyl sulphoxide (dmso), dihexyl sulphoxide (dhso) and dioctylsulphoxide (doso) was studied by spectrophotometry. Each of these donors form a 1 : 1 adduct with U(TTA)₄. The adduct formation constants (log β_AB) were calculated from spectral changes and were found to be 3.10 (dbso), 3.23 (dmso), 3.62 (dhso) and 3.64 (doso).     

Wide-angle X-ray diffraction study of the effect of periodate oxidation and thermal treatment on the structure of cellulose powder

Cellulose and periodate oxidised cellulose powders were investigated for any structural changes occurring when subjected to thermal treatment, since their use as fillers in composites involves prolonged exposure to high temperatures. The wide-angle X-ray diffraction peak at 2θ = 22·9° for the oxidised cellulose samples was found to decrease almost proportionately to the degree of oxidation of the starting cellulose. Whereas heat treatment of cellulose powder at 120°, 180° and 240°C for three hours also produces a continual decrease in the crystallinity of the cellulose, heat treatment of periodate oxidised cellulose at 120°, 180° and 240°C for three hours produces drastic changes in the crystallinity of the resultant products. For 16% oxidised cellulose heated at 240°C for three hours, almost total crystallinity is lost. This is also seen from the increase in line broadening of the X-ray diffractogram. An interesting feature in the above cases was the appearance of an additional peak at 2θ ≈ 12°. In DTG studies the temperature at which the major loss in weight (～ 62%) occurred was ～ 290°C for most samples. The final weight loss (～ 85%) generally occurred at 430–450°C. The 16% oxidised cellulose behaved somewhat differently, and reasons for this are explained.     

Neutron activation determination of noble metals using a selective group separation scheme

A rapid and comprehensive method has been developed for the determination of ppm to sub-ppb amounts of Ru, Pd, Ag, Os, Ir, Pt and Au, based on thermal neutron irradiation, dissolution of samples, selective absorption on Srafion NMRR ion exchange resin and high resolution γ-ray spectrometry. Two noble metals “specific” resins were tested for their absorption behaviour. The method has been used for analysis of standard rocks, ores, minerals, lunar samples, coal, coal fly ash, and several biological materials.     

Substoichiometric determination of tungsten by neutron activation analysis

A method for the substoichiometric determination of tungsten by thermal neutron activation analysis has been developed based on the selective extraction of the tungsten dithiol complex into amyl acetate. The method is simple, rapid and accurate. It has been used in the determination of tungsten in alloy steel, meteorites and biological standard kale.     

When isf(x,y) = u(x) + v(y)?

LetX andY be arbitrary non-empty sets and letS a non-empty subset ofX ×Y. We give necessary and sufficient conditions onS which ensure that every real valued function onS is the sum of a function onX and a function onY.     

Structure development in curing of poly(phenylene sulfide)

The structure development during melt curing of poly(phenylene sulfide) (PPS) is reported. The changes in the structure were monitored using various characterization techniques such as differential scanning calorimetry, thermogravimetric analysis, infrared spectroscopy, and optical microscopy. It was observed that the thermal parameters such as melting point and heat of fusion are very sensitive to the structural changes and can be effectively used to monitor the curing process. The effect of curing environment was also investigated, and it was found that the rate of change of structure is considerably higher in air than in nitrogen. The results are discussed on the basis of the different mechanisms for curing of PPS.     

Polyureas by interfacial polycondensation: Preparation and properties

This paper concerns poly(hexamethylene) ureas produced by the technique of interfacial polycondensation. The polymer has been produced under various conditions of preparation and aspects of its structure have been elucidated using x-ray diffraction, differential scanning calorimetry, and other thermal analyses such as ther-mogravimetric analysis. The polymer has been shown to be a high-melting thermoplastic, with a melting point of about 285°C. The polymer is semicrystalline. The rate at which the polymerization takes place has an important influence on the crystal structure and the degree of crystallinity of the polymer as formed, and hence offers the possibility of manipulating the structure through a choice of preparation conditions. Chemical treatment of the formed polymer is another possible way of manipulating the structure, and some exploratory experiments on end capping show promise in this direction.     

Modification of etching properties of a newly developed nuclear track detector called allyl bis-(2-nitroxy-ethyl) carbomate (ABNEC)–allyl diglycol carbonate (ADC) copolymer [ABNEC:ADC (1:9)] by gamma irradiation

The gamma irradiation effects on the bulk etch rate, V _b of an indigenously prepared new nuclear track detector which is a copolymer of allyl bis-(2-nitroxy-ethyl) carbomate (ABNEC) and allyl diglycol carbonate (ADC) [ABNEC:ADC (1:9)] were studied in the dose range of 25.0–250.0 kGy and etching temperature range of 60–80 °C. The bulk etch rates increase and the activation energy values for bulk etching of gamma-irradiated detectors decrease with the increase in gamma dose indicating the scission of the detector. UV–visible spectra of the unirradiated and the irradiated films were also taken to explore the possibility of using this new detector for gamma dose measurements.     

Measure free martingales and martingale measures

Let T ⊂ ℝ be a countable set, not necessarily discrete. Let f _t , t ∈ T, be a family of real-valued functions defined on a set Ω. We discuss conditions which imply that there is a probability measure on Ω under which the family f _t , t ∈ T, is a martingale.