Flexible hydrogels connecting adhesion and wetting

Raindrops falling on window panes spread upon contact, whereas hail can cause dents or scratches on the same glass window upon contact. While the former phenomenon resembles classical wetting, the latter is dictated by contact and adhesion theories. The classical Young-Dupre law applies to the wetting of pure liquids on rigid solids, whereas conventional contact mechanics theories account for rigid-on-soft or soft-on-rigid contacts with small deformations in the elastic limit. However, the crossover between adhesion and wetting is yet to be fully resolved. The key lies in the study of soft-on-soft interactions with material properties intermediate between liquids and solids. In this work, we translate from adhesion to wetting by experimentally probing the static signature of hydrogels in contact with soft PDMS of varying elasticity of both the components. Consequently, we probe this transition across six orders of magnitude in terms of the characteristic elasto-adhesive parameter of the system. In doing so, we reveal previously unknown phenomenology and a theoretical model which smoothly bridges adhesion of glass spheres with total wetting of pure liquids on any given substrate. Lastly, we highlight how solid like hydrogels can be treated as potential candidates for cleaning impurities from conventionally sticky PDMS substrates

Study on the effects of culture and pH variations on quality of ghee.

Milk was analyzed for several parameters like pH, acidity, fat, protein, solids-not-fat, total solids and moisture content. The values obtained were found to be satisfactory in comparison to composition of normal cow milk. Cream was separated from milk using hand-operating cream separator. Analysis of cream showed satisfactory results in comparison to cream obtained by cream separation process. The cream was divided into three parts of which first was directly made ghee without culturing, second was cultured with dahi culture and third with yoghurt culture. Chemical analysis of all ghee samples gave satisfactory results in comparison to normal ghee composition. Sensory evaluation of the three samples were performed taking attributes like flavor, acidity, color, texture, absence of impurities and overall. Ghee prepared from dahi cultured cream showed the highest. Again, dahi cultured cream was treated to different pH (4.5, 4.0 and 3.6). Ghee was prepared and subjected to sensory evaluation. The cream cultured to pH 3.6 showed the highest score. This finding indicates that flavor is produced in ghee in greater extent by dahi cultured cream in respect to yoghurt cultured and non-cultured cream and greater the extent of culturing, more is the flavor yielding diacetyl produced

Synthesis, Conformational Studies and Biological Profiles of Tetrahydrofuran Amino-Acid-Containing Cationic Antitubercular Peptides

Linear cationic tetra- and octapeptides containing a tetrahydrofuran amino acid were synthesised, a conformational analysis performed, and their structure-activity relationships explored by evaluating their antibacterial, antitubercular and cytotoxic properties. Only the octapeptides showed activities, which was weak to moderate against Gram-positive and Gram-negative bacteria for only two peptides, but was very significant against Mycobacterium tuberculosis, and peptides were devoid of toxicity towards mammalian Vero cells. N-Terminus-deprotected esters showed the best results with excellent selectivity for M.tuberculosis and these peptides promise to be potential leads

Tetrahydrofuran amino acid-containing gramicidin S analogues with improved biological profiles

Gramicidin S (GS) is a cyclic cationic antimicrobial peptide (CAP) with a wide spectrum of antibiotic activities whose usage has been limited to topical applications owing to its cytotoxic side effects. We have synthesized tetrahydrofuran amino acid (Taa)-containing GS analogues, and we have carried out conformational analysis and explored their structure activity relationships by evaluating their antitubercular, antibacterial and cytotoxic properties. Two of these analogues showed impressive as well as selective activity against Mycobacterium tuberculosis (MTB) without toxicity towards mammalian Vero cells or human RBCs, and are promising as potential leads

THE CAPITAL STRUCTURE PUZZLE: ANOTHER LOOK AT THE EVIDENCE

Since the formulation of the M & M irrelevance propositions 40 years ago, financial economists have been debating whether there is such a thing as optimal capital structure-a proportion of debt to equity that maximizes current firm value. Some finance scholars have followed M & M by arguing that both capital structure and dividend policy are largely "irrelevant" in the sense that they have no significant, predictable effects on corporate market values. Another school of thought holds that corporate financing choices reflect an attempt by corporate managers to balance the tax shields and disciplinary benefits of greater debt against the increased probability and costs of financial distress. Yet another theory says that companies do not have capital structure targets, but instead follow a financial "pecking order" in which retained earnings are preferred to outside financing, and debt is preferred to equity when outside funding is required. 1999 Morgan Stanley.