Three problems and their relevance?

Three problems are posed and their solutions (ranging from complete to partial) described. They are (i) the Hydrogen atom in an intense magnetic field; (ii) the thermodynamics of one-dimensional chain of continuous spins in an external magnetic field interactingvia Heisenberg interaction; and (iii) the pair correlation function in an interactingmaariys electron system. The relevance of these problems and their solution and various aspects of physics are stressed.     

Selektive Alkylierung chelatisierter Hydroxylgruppen in kondensierten Benzpyronen, 1. Mitt.

Zusammenfassung Da chelatisierte Hydroxylgruppen in kondensierten Polyhydroxypyronen einen Boracetatkomplex bilden, während andere Hydroxylgruppen im gleichen Molekül normale Acetylierung erleiden, und da aus diesem Komplex die Hydroxylgruppe leicht zurückgewonnen und mittels aktiven Silberoxids und Methyljodids alkyliert werden kann, war es möglich, 1,3-Dihydroxyxanthon selektiv zum 1-Methoxy-3-hydroxyxanthon zu alkylieren. Dessen Konstitution wurde durch Äthylierung zum 3-Äthoxyderivat bewiesen. Letzteres wurde unabhängig davon auch auf anderem Wege synthetisiert.Aus der Dissertation vonG. S. Puranik, Karnatak-Universität     

Fluorescence Dynamics of Three UV-B Sunscreens

Polarity of the surrounding medium affects the excited states of UV-B sunscreens. Therefore understanding excited state processes in a mixed polarity model system similar to skin is essential. We report the excited state lifetimes, quantum yields, radiative and non-radiative rates of three sunscreens. Among the three UV-B sunscreens studied, octyl salicylate emits from a single excited state, while padimate O and octyl methoxy cinnamate show multiple states. The radiative rates of salicylate and cinnamate are approximately constant, while that of padimate O depends strongly on solvent. The non-radiative rates of all sunscreens vary with solvent polarity. Compared to salicylate and cinnamate, padimate O is complex to analyze because of its two emission peaks and one peak’s strong dependence on the dielectric constant. High absorbance, broad absorption peak with small fluorescence quantum yield, and low radiative rate make octyl methoxy cinnamate a superior UV-B sunscreen ingredient. The complexity in excited-state analysis shows that the lifetimes of the sunscreens are critical parameters, in addition to absorbance and quantum yield. Fluorescence lifetime substantiates the use of polystyrene nanospheres as a model host to study the photo-physical properties of sunscreen in a heterogeneous environment.     

Studies on Squalene Biosynthesis and the Standardization of Its Extraction Methodology from Saccharomyces cerevisiae

Applied Biochemistry and Biotechnology - In this study, a homogenization-based extraction method was developed and was compared to five conventional methods of squalene extraction. Squalene...     

Enhanced Electrocatalytic Activity of Ni‐CNT Nanocomposites for Simultaneous Determination of Epinephrine and Dopamine

A promising electrochemical sensor based nickel‐carbon nanotube (Ni‐CNT) modified on glassy carbon (GC) electrode had been developed and the properties of the modified electrode were characterized by multispectroscopic analysis. The fabricated sensor (GC/Ni‐CNT) electrode was utilized to determine the catecholamines such as epinephrine and dopamine simultaneously. Differential pulse voltammetry and amperometry were used to verify the electrochemical behavior of the studied compounds. The GC/Ni‐CNT based amperometric sensor showed a wide linear range and low detection limit with high analytical sensitivity of 8.31 and 6.61 μA μM^?1 for EP and DA, respectively which demonstrates better characteristics compared to other electrodes reported in the literature. Further, no significant change in amperometric current response was observed in presence of biological interference species such as glucose, cysteine, citric acid, uric acid and ascorbic acid in the detection of EP and DA. The utility of this GC/Ni‐CNT electrode was well established for the determination of EP and DA in human urine samples.