A novel transformation of O-methyldalbergin

O-methyldalbergin and related 4-phenylcoumarins are markedly different from ordinary coumarins in their behaviour towards alkali. They are stable in boiling alkali and on addition of mercuric oxide yield coumarilic acids. Phenyl-coumarilic acids undergo decarboxylation readily when boiled with aqueous alcoholic mercuric chloride to yield phenyl substituted coumarones.     

Phototoxic and photochemical properties of sanguinarine.

Sanguinarine, a commercial drug exhibiting antimicrobial and antitumor properties, was studied with respect to its basic photochemical characteristics and also with regard to its phototoxicity to mosquito larvae (Aedes atropalpus). Sanguinarine proved to be clearly phototoxic to larvae, with an LD50 of 0.096 mg/mL with near UV exposure as compared with 23.3 mg/mL without. Flash photolysis experiments enabled the study of the triplet state of sanguinarine to be undertaken. Quenching by oxygen occurs with a rate constant of 6 x 10(9) M-1s-1 and time-resolved emission studies indicate that sanguinarine produces a significant amount of singlet oxygen (phi delta = 0.16) as does the isoquinoline alkaloid, berberine (phi delta = 0.25). These values represent the first direct quantitative measurements of photosensitization parameters of these compounds. Additionally, sanguinarine exhibits efficient electron donation properties, undergoing reaction with methyl viologen with a rate constant greater than 10(10) M-1s-1, but is a poor electron acceptor. Phototoxicity of sanguinarine can thus be explained in terms of its photosensitization properties.     

A comparative study on thermoresponsive magnetic nanohydrogels: role of surface-engineered magnetic nanoparticles

A comparative study of thermoresponsive poly(N-isopropylacrylamide)(PNIPAAm)-chitosan (CS)-based magnetic nanohydrogels (MNHGs) encapsulating functionalized Fe₃O₄ nanoparticles (NPs) in terms of the parameters governing their suitability for real hyperthermia is reported. Iron oxide NPs functionalized with (a) citric acid (CA-Fe₃O₄), (b) ethylenediamine (Amine-Fe₃O₄) and (c) dimercaptosuccininc (DMSA-Fe₃O₄) have been synthesized and their encapsulation into MNHGs was obtained through physical encapsulation method. The structural characterizations of synthesized materials include X-ray diffraction, FT-IR, TGA, ICP-AES and X-ray photoelectron spectroscopy (XPS). Encapsulation of the functionalized NPs into MNHGs were observed in TEM micrographs, while SEM and AFM micrographs confirmed their spherical morphology (~250–300 nm). Lower critical solution temperature (LCST) variation was measured by UV–visible spectrophotometer and differential scanning calorimetry (DSC). MNHGs exhibited sufficient magnetization and heating ability for hyperthermia. Typically, hydrogels containing CA-Fe₃O₄ (50 mg/ml) raised the temperature of the medium to 43 °C, a suitable dose for in vivo application in tumor-bearing mice.     

High spin states in120Xe

High spin states in ¹²⁰Xe, populated via¹⁰⁷Ag(¹⁶O, p2n) and¹⁰⁸Pd(¹⁶O, 4n)reactions have been studied using γ-ray spectroscopic techniques. 21 new transitions have been added to extend the level scheme. Two S-bands are extended upto 26⁺ and 22⁺;these bands are found to cross the g. s band at hΩ=0. 39 and 0. 47 MeV. The band structures have been discussed within the framework of CSM.     

Pre-exponential factor for non-isothermal crystallization of glassy Se85− x Te15Sb x (0 ≤ x ≤ 10) alloys

We report observations of the Meyer–Neldel rule for the non-isothermal crystallization of glassy Se_{85? x} Te₁₅Sb _x (x =?0, 2, 4, 6, 8, 10) alloys. We found a strong co-relation between the pre-exponential factor K ₀ of the rate constant K(T) for crystallization and the activation energy of crystallization E _c. This indicates the presence of a compensation effect for the non-isothermal crystallization process in this glassy system. The composition dependence of the crystallization temperature T _c and the activation energy for crystallization E _c is discussed.     

Recent trends in optical data processing

Optical data processing is an advancing field which has received much attention in recent years. Optical techniques have already shown their applicability in target identification, advanced signal processing operations and advanced linear algebra operations. The potential capabilities of processing of data using photons instead of electrons as the carrier of information have established, beyond any doubt, that the optical techniques will be the next generation technology surpassing electronic techniques in some important areas such as air traffic control, missile guidance and remote sensing. Although great strides have been made in all the areas of optical data processing, the goal of high performance, high speed and very accurate all-optical computers would be realised only around the year 1995. The main difficulty is that the required materials for high resolution and fast spatial light modulators and optical interconnects are yet to be perfected. The present paper reviews the recent trends and the future prospects of optical data processing.     

Rotational structures in the 125Cs nucleus

The collective band structures of the ¹²⁵Cs nucleus have been investigated by in-beam γ-ray spectroscopic techniques following the ¹¹⁰Pd ( ¹⁹F, 4n) reaction at 75MeV. The previously known level scheme, with rotational bands built on πg_7/2, πg_9/2 and πh_11/2 orbitals, has been extended and evolves into bands involving rotationally aligned ν(h_11/2)² and π(h_11/2)² quasiparticles. A strongly coupled band has been reassigned a high-K πh_11/2 ⊗ νg_7/2 ⊗ νh_11/2 three-quasiparticle configuration and a new side band likely to be its chiral partner has been identified. Configurations assigned to various bands are discussed in the framework of Principal/Tilted Axis Cranking (PAC/TAC) model calculations.