Network Model of the Disordered Phase in Symmetric Diblock Copolymer Melts.

We present a model for the order-disorder transition of symmetric A-B diblock copolymer melts in which the disordered phase is treated as a bicontinuous network, and in which self-consistent field predictions of properties of an analogous ordered network are used to estimate some properties. Such a model is shown to accurately predict the latent heat of this transition. The dependence of the location of the transition upon the invariant degree of polymerization N[over ¯] is shown to be consistent with a simple hypothesis that the disordered bicontinuous structure is stabilized relative to an analogous ordered network by a nearly constant entropy per network junction.

Generation of Aspherical Optical Lenses via Arrested Spreading and Pinching of a Cross-Linkable Liquid.

Aspherical optical lenses with spatially varying curvature are desired for capturing high quality, aberration free images in numerous optical applications. Conventionally such lenses are prepared by multistep top-down processes which are expensive, time-consuming, and prone to high failure rate. In this context, an alternate method is presented here based on arrested spreading of a sessile drop of a transparent, cross-linkable polymeric liquid on a solid substrate heated to an elevated temperature. Whereas surface tension driven flow tends to render it spherical, rapid cross-linking arrests such flow so that nonequilibrium aspherical shapes are attained. It is possible to tune also the initial state of the drop via delayed pinching of a liquid cylinder which precedes its release on the substrate. This method has led to the generation of a wide variety of optical lenses, ranging from spherical plano convex to superspherical solid immersion to exotic lenses not achieved via conventional methods.

Effect of Ocimum sanctum on homocysteine levels and lipid profile in healthy rabbits.

CONTEXT: Ocimum sanctum has been reported to have a variety of medicinal properties. OBJECTIVE: The present study was planned to evaluate the effect of O. sanctum on plasma homocysteine levels and lipid profile in healthy rabbits. MATERIAL AND METHODS: Forty rabbits were divided into two groups (20 each). Group I rabbits received normal diet and group II rabbits received fresh leaves of O. sanctum (2 g/day) for 8 weeks along with normal diet. Fasting plasma samples were estimated for homocysteine and lipid profile. The results were analysed statistically. RESULTS: The levels of homocysteine, total cholesterol, triglycerides, low density lipoprotein cholesterol, very low density lipoprotein cholesterol were found to be decreased and high density lipoprotein cholesterol levels increased significantly on supplementation with O. sanctum (p < 0.001). DISCUSSION AND CONCLUSION: Thus, O. sanctum can prove to be a significant cardioprotective substance and an important adjuvant in the treatment of hyperhomocysteinemia and dyslipidemia.

Effect of tulsi (Ocimum Sanctum Linn.) on sperm count and reproductive hormones in male albino rabbits.

Fresh leaves of Ocimum Sanctum (OS) were used to study its effect on male reproductive function (sperm count and reproductive hormones) in male albino rabbits. Animals in the test group received supplementation of 2 g of fresh leaves of OS per rabbit for 30 days, while the control group was maintained on normal diet for the same duration. Sperm count and hormonal estimation [testosterone, follicle stimulating hormone (FSH), and luteinizing hormone (LH)] were done in serum samples of both groups and compared. A significant decrease was noted in the sperm count in test group rabbits. Serum testosterone levels showed marked increase while FSH and LH levels were significantly reduced in OS-treated rabbits. The results suggest the potential use of OS as an effective male contraceptive agent.