Critical ageing of hydroxyapatite sol-gel solutions

It has been established that hydroxyapatite coatings can be produced using an alkoxide based sol-gel technique. Previous work showed that in addition to hydroxyapatite other phases including CaO were observed. A critical factor in determining the composition of the final coating is the period between solution preparation and coating deposition. The current study addresses how the ageing time affects the composition of the coating and the time required before a solution can be used to deposit monophasic coatings. Powders and coatings were produced with ageing times up to one week and examined with X-ray diffraction, thermal gravimetric analysis and differential thermal analysis. By depositing coatings after various ageing times, it was found that a solution ageing time of at least 1 day was required before monophasic hydroxyapatite coatings could be deposited. Thermogravimetric analysis showed that heating of the gel in air or in nitrogen both produced hydroxyapatite. Thermogravimetric analysis could be used as a simple and effective tool for identifying the critical ageing time required to produce high-purity hydroxyapatite coatings.     

Rheology and filling characteristics of particulate dispersions in polymer melt formulations for liquid fill hard gelatin capsules

OBJECTIVE: In the postmenopausal years, women develop a central pattern of fat distribution and an increased risk of developing cardiovascular disease (CVD). The possibility that these events are related has not been extensively investigated. The object of the present study was to test the hypotheses that, 1) menopause-related differences in lipids are associated with greater estimated intra-abdominal adiposity, and 2) the relationship between individual adipose depots and plasma lipids differs with menopausal status. DESIGN: Cross-sectional. SUBJECTS: 141 healthy pre- and postmenopausal women aged 35-65 y. MEASUREMENTS: Total body fat by hydrodensitometry was used as an index of whole-body adiposity, the sum of five central skinfold measurements as an index of subcutaneous upper-body adiposity, and estimated intra-abdominal adipose tissue (IAF) as an index of visceral adiposity. Fasting plasma concentrations of total cholesterol (total-C), high- and low-density-lipoprotein cholesterol (HDL-C, LDL-C), and triglycerides were used as indices of CVD risk. RESULTS: Postmenopausal women had greater total body fat (P < 0.001), summed central skinfolds (P < 0.01), estimated IAF (P < 0.001), higher plasma concentrations of total-C (P < 0.001), LDL-C (P < 0.001) and triglycerides (P < 0.001), than premenopausal women. The relationship between central skinfolds and LDL-C differed with menopausal status, being significant in pre- but not postmenopausal women. Adjustment for estimated IAF with analysis of covariance decreased menopause-related differences in levels of total-C, LDL-C and triglycerides by approx 40-70%. CONCLUSION: These observations suggest that, 1) menopause-related changes in IAF may adversely affect the plasma lipid profile, and 2) menopausal status affects the relationship between central subcutaneous fat and LDL-C. Studies with measured IAF are needed to confirm present results.     

Electrokinetic potential and stability of suspensions of micropowders of titanium carbide in gelatin solutions

Translated from Poroshkovaya Metallurgiya, No. 1(313), pp. 65–71, January, 1989.     

Preparation of solid solutions of some complex carbides of the transition metals

Summary Alloys of all the systems investigated, sintered by the method of hot pressing at high temperatures, have extensive homogeneity regions of the solid solutions based on the carbide with an NaCl type crystalline lattice; this indicates a high solubility of the monocarbides of metals of group VI in the monocarbides of the transition metals of groups IV and V.Translated from Poroshkovaya Metallurgiya, No. 3(51), pp. 32–37, March, 1967.