Growth of undoped and Te doped InSb crystals by vertical directional solidification technique

We have successfully grown high mobility undoped and Te doped InSb crystals of size 10–12 mm dia. and 60 mm length under inert argon atmosphere in closed quartz ampoules, by vertical directional solidification (VDS) technique. The crystals showed predominantly (220) orientation along the growth axis. The surface defects, such as voids were reduced drastically by selecting proper lowering rate, rotational speed and cone angle of the ampoule. The high mobility and quality crystals were obtained with the ampoule conical angle less than 20°, lowering rate 5mm/h, and rotational speed 10 rpm.     

Determination of uranium in fertilisers using fission track method

Trace contents of uranium in various commercial fertilizers e.g. ureas, superphosphates, diammonium phosphates have been determined using fission track etch technique. The uranium content in ureas varies from .05 to 1.3 mg kg^–1 whereas in superphosphates it varies linearly with phosphate content.     

Distinction between differentiation and senescence and the absence of increased apoptosis in human keratinocytes undergoing cellular aging in vitro

OBJECTIVE: Changes in calcium homeostasis and bone mass around the climacteric are poorly understood. We examined relations between endocrine factors and indices of bone mass and metabolism in healthy women approaching the menopause. DESIGN: Cross-section study. PATIENTS: Sixty-eight spontaneously menstruating women aged 45-55. MEASUREMENTS: Bone density measured at lumbar spine (LS) and femoral neck (FN) using dual energy X-ray absorptiometry and distal non-dominant forearm using peripheral quantitative computed tomography. We recorded menstrual history, physical activity and dietary calcium, and measured serum calcium, phosphate, alkaline phosphatase, osteocalcin, vitamin D, fT3, T4, TSH, PTH, FSH and oestradiol (E2), and urinary pyridinoline (PYD) and deoxypyridinoline (DPD) excretion. RESULTS: Using serum FSH level as a marker of ovarian function, 63 subjects could be classified into one of three groups: group A (serum FSH < 10 U/l, n = 29), group B (10-35 U/l, n = 27) and group C (> 35 U/l, n = 7). Bone density fell with declining ovarian function at the LS, FN and forearm trabecular (but not cortical) sites. Serum PTH was lower in group A vs B (mean (SD) 2.68 (0.97) vs 3.52 (1.17) pmol/l, P < 0.05), but similar to group C (2.90 (1.09) pmol/l, P = NS). Serum phosphate was elevated in group C compared to groups A and B (1.17 (0.15) vs 1.04 (0.11) and 1.05 (0.13) mmol/l, P < 0.05), and urinary PYD (61.1 (8.0) vs 50.4 (11.6) and 43.9 (8.1) mumol/mol creatinine) and DPD (15.9 (3.9) vs 12.0 (3.6) and 11.4 (3.6) mumol/mol creatinine) excretion were also increased. There were no significant differences in vitamin D metabolites or osteocalcin. Multivariate analysis suggested serum osteocalcin was positively related to physical activity and serum 1,25-dihydroxycholecalciferol levels. Serum free T3 was positively correlated with urinary DPD excretion, and inversely related to serum PTH. In all subjects, serum PTH was related to body weight (r = 0.38, P = 0.002). CONCLUSIONS: Declining ovarian function before menopause is accompanied by reductions in bone mass and altered calcium metabolism. Free T3 may regulate bone resorption and indirectly modulate PTH release.     

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.     

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.     

Effect of dopamine on the esophageal smooth muscle in vivo

Using the method 133Xe clearance we investigated blood flow and calculated vascular resistances simultaneously in the muscles of the upper and lower extremities in 58 patients following successful surgical correction of aortic coarctation carried out at age 11.5 (+/- 2.9) years. The interval from operation to investigation was 11.5 (+/- 4.5) years. Resting and maximal ischemic exercise blood flows in the upper extremity were decreased and the duration of maximal blood flow was shortened. Values recorded from the lower extremities did not differ from normal controls. The difference between upper and lower extremities was statistically significant. Vascular resistance during maximal blood flow was higher in the upper extremities than in the lower. Differences between upper and lower extremities did not change after vasodilation elicited by amyl nitrite. The degree of differences was not dependent upon the age at operation, the age of the patients at investigation, or on the time interval between operation and investigation.     

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.