Thermal,spectral and morphological studies on cellulose,cellulose ethylthiophosphate and its metal complexes in air

Metal complexes of thiophosphorylated cellulose, when heated, give rise to high char yields. These and related observations suggest that such derivatisation may give rise to novel flame retardant treatments for cellulosic materials. The kinetics of thermal degradation of cellulose, cellulose ethylthiophosphate (CESP) and metal complexes of the CESP have been studied by thermogravimetry (TG) and differential thermal analysis (DTA) from ambient temperature to 700°C in dynamic air to investigate the potential flame retardance of the CESP and its metal complexes. Various parameters such as energy, entropy, enthalpy and free energy of activation have been calculated using the Broido method and transition state theory. For the decomposition stage of thermal degradation, the activation energies of the CESP samples lie in the range 53-133 kJmol^?1 and of the metal complexes, 108-177kJmol^?1, which are found to be lower than that of cellulose (187 kJmol^?1). Scanning electron micrographs of the CESP show that the fibrillar structure of cotton has become more evident and chars retain the general morphology of the original fibre although severe, localised zones of damage reflect the gross chemical and physical changes occurring during pyrolysis. The IR spectra of chars of modified samples indicate formation of compounds containing C=O, C=C and P=O groups. The mechanisms of thermal degradation of the CESP and its metal complexes have been proposed.     

Finite element method in magnetohydrodynamic channel flow problems

The finite element method has been applied to the steady-state fully developed magnetohydrodynamic channel flow of a conducting fluid in the presence of transverse magnetic field. Simple elements have been used to obtain the numerical values of velocity and induced magnetic field. To test the efficiency of the method, three different geometries, viz., rectangle, circle and triangle, are taken as the section of the pipe whose walls are non-conducting. Comparison is made with those cases in which exact solutions are available. Apart from giving good results, the FEM makes it possible to solve the problem for a pipe with arbitrary cross-section which was not possible by the other methods.     

Scientometric profile of Indian agricultural research as seen through Science Citation Index Expanded

Summary An analysis of 16891 publications published by Indian scientists during 1993-2002 and indexed by Science Citation Index Expanded (Web of Science) indicates that the publication output in the agricultural sciences is on the decline since 1998 onwards. 'Dairy and animal sciences' followed by 'veterinary sciences' constitute the largest component of the Indian agricultural research output. Agricultural universities and institutes under the aegis of Indian Council of Agricultural Research (ICAR) are the major producers of research output. Most of the papers have been published in domestic journals and in low normalized impact factor journals with a low rate of citation per paper. Most of the highly productive institutions are either agricultural universities or the institutes under the aegis of ICAR. Most of the prolific authors are from the highly productive institutions. However, only a few highly cited authors are from highly productive institutions.     

In vitro anthelmintic action of some indigenous medicinal plants on Ascardia galli worms

Different parts of ten indigenous medicinal plants were screened for their in vitro anthelmintic activity against Ascaridia galli worms of the birds. Preparations from Carica papaya, Sapindus trifoliatus, Butea frondosa and Momordica charantia were more effective than piperazine hexahydrate.     

Transition from ploughing to cutting during machining with blunt tools

When machining at small depths of cut, metal flow near a rounded tool edge becomes important. It has been established that there is a critical depth of cut which signifies the onset of chip formation. The approximate analysis predicts the neutral point angle corresponding to this critical depth of cut to be 37.6°. The value compares reasonably well with experimental results.     

An analysis of non-propagating fatigue cracks

An analysis for the formation of nonpropagating fatigue cracks at (the base of V-shaped) notch roots, based on the considerations of the extent of the critically stressed region ahead of a notch or a crack tip, and the resulting volumetric strength effect, is developed. Assuming that the minimum local cyclic stress required for crack initiation from a notch root is equal to the unnotched fatigue limit, σ_e, and that the minimum local cyclic stress required for the propagation of the crack is equal to the theoretical strength of the material, σ_e, a model of notch fatigue limit is proposed that shows that nonpropagating cracks should form at the notch base if ρ≤ ρ⁰, a critical root radius, provided the notch is sufficiently deep,i.e. d ≥ ρ₀. The radius ρ₀ is a material constant and can be estimated from known material properties. The estimated values of ρ₀ are in fairly good agreement with available experimental values for steels and pure copper. For stresses near the notch fatigue limit it is suggested that p₀ be regarded as a radius above which notch fatigue limit is essentially initiation controlled and below which essentially propagation controlled. The notch fatigue limit based on complete fracture can then be estimated more accurately with mild as well as sharp notches. D. N. LAL, formerly a Graduate Assistant in Materials Science, Syracuse University     

Über die Basizität flüssiger Schlacken der Systeme CaO–SiO2 und CaO–Al2O3

EMK-Messungen mit einer Diffusionszelle an flüssigen Schlacken der Systeme CaO–Al₂O₃ und CaO–SiO₂ bei 1600°C. EMK und Sulfidkapazität zeigen lineare Abhängigkeit. EMK-Werte können als relatives Basizitätsmaß gewertet werden.     

In search of novel water soluble forskolin analogues for positive inotropic activity

Using the novel lead from hydroxy acetyl substituted forskolin analogues, such as 7 beta-hydroxyacetyl-7 beta-deacetyl forskolin or 6 beta-hydroxyacetyl forskolin, a number of water soluble omega-amino acyl derivatives were synthesized. Two such compounds 6 and 18 showed better in vitro activity but failed to show in vivo activity.     

A study of the new K2NiF4-type solid solutions Sr2FexRu1−xO4 by Mőssbauer spectroscopy and other techniques

The magnetic and structural properties of the solid solutions Sr₂Fe_xRu_1?xO₄ (O ? x ? 0.5) have been studied using ⁵⁷Fe and ⁹⁹Ru Mőssbauer spectroscopy and other techniques. These phases, which are reported for the first time, have the K₂NiF₄-type structure with iron and ruthenium distributed at random on the B-site. As the ruthenium is replaced by iron the weakly-metallic conductivity and Pauli paramagnetism of Sr₂RuO₄ give way to localized-electron behaviour and long-range antiferromagnetic order despite the layer-type structure which is unfavourable for 180° Ru-O-M (M = Fe or Ru) magnetic exchange interactions in three dimensions. For x = 0.1-0.4 the iron is present almost entirely in the +3 oxidation state, but for x = 0.5 appreciable amounts of Fe^IV are also present, in conjunction with Fe^III, Ru^IV, and Ru^V.