Estimation of residues of carbofuran and its metabolites in sugarcane and soil by derivatization with 1-fluoro-2,4-dinitrobenzene and gas chromatography with nitrogen-phosphorus detection

Residues of carbofuran and its metabolites were studied in sugarcane plants and soil after application at 1 and 2 kg/ha. The residues of carbofuran and its metabolites were extracted by refluxing with 0.25N HCI, partitioned into dichloromethane, and cleaned up on acidic alumina. The respective 7-phenols of carbofuran, 3-ketocarbofuran, and 3-hydroxycarbofuran were destroyed by treatment with ceric ammonium sulfate, and the residues were derivatized with 1-fluoro-2,4-dinitrobenzene. The derivatives were estimated by gas chromatography with nitrogen-phosphorus detection. The concentration of 3-hydroxycarbofuran in sugarcane plants remained higher and persisted longer than that of the parent compound. Carbofuran-derived residues were not detected in cane juice. Soil samples were found to contain only carbofuran, which declined at a very fast rate that followed a first-order kinetics rate of reaction.     

Conformationally controlled high-affinity targeting of RNA or DNA by novel 2'-amino-DNA/LNA mixmers and pyrenyl-functionalized 2'-amino-DNA

9-Mer DNA sequences containing 2'-N-methyl-2'-N-(pyren-1-ylmethyl)-2'-amino-DNA monomers display significantly increased affinity towards DNA complements whereas the corresponding 2'-amino-DNA monomer has a detrimental effect on duplex stability. These effects are efficiently reversed by incorporation of four LNA nucleotides inducing a B-DNA to A-DNA conformational change.     

Purification and properties of membrane-bound coupling factor-latent ATPase from Mycobacterium phlei.

The membrane bound coupling factor-latent ATPase was solubilized from the membrane vesicles of Mycobacterium phlei by using 0.25 M sucrose or low ionic strength buffer. Purification of the solubilized enzyme by use of Sepharose-ADP conjugate gel yielded a homogenous preparation of latent ATPase which was purified about 216-fold in a single step with an 84% yield. The enzyme exhibits a specific activity of 39 mumoles of ATP hydrolyzed per min per mg protein. The purified enzyme exhibits coupling factor activity. Electrophoresis in two dissociating solvent systems indicates that the enzyme contains at least three major polypeptides of molecular weights 56,000, 51,000, and 46,000 daltons, and two minor polypeptides of 30,000 and 17,000 daltons. Equilibrium binding studies of ADP with purified coupling factor-latent ATPase reveal the presence of two nucleotide binding sites per molecule with an apparent Ka of 8.1 X 10(-5) M. By use of affinity chromatography, another latent ATPase has been isolated from the solubilized enzyme, which does not exhibit coupling factor activity.     

Excess permittivities,excess refractive indices and NMR spectroscopic studies of solutions of 1,2-dibromoethane in aromatic hydrocarbons

Excess permittivities and excess refractive indices data for solutions of 1,2-dibromoethane (DBE) in benzene, toluene, o-xylene, m-xylene and p-xylene over the whole composition range at 25°C have been obtained. The analysis of excess dielectric properties suggests the existence of weak electron donor-acceptor type interactions between 1,2-dibromoethane (DBE) and aromatic hydrocarbons. The equilibrium constants and the dipole moments of the DBE-aromatic hydrocarbon complexes in solutions have been evaluated. Strneght of interaction increases with electron donating power of aromatic hydrocarbons. NMR spectroscopic studies made on these binary liquid systems also provide evidence for the existence of weak electron donor-acceptor type specific interactions between DBE and aromatic hydrocarbons.     

Design of Ultra Compact Polarization Splitter Based on the Complete Photonic Band Gap

A novel design of polarization splitter based on the complete photonic band gap has been proposed in this paper. The proposed Photonic Band Gap (PBG) polarization splitter is formed by two photonic crystal waveguides composed of dielectric rods in air in honeycomb structure for which complete photonic band gap is obtained using the plane wave expansion (PWE) method. The splitting properties (i.e. coupling length, extinction ratio and insertion loss) of PBG polarization splitter have numerically been investigated using the finite difference time domain (FDTD) method. It has been shown that polarization splitter of length as small as 32 μm can be designed at λ=1.55 μm. The proposed polarization splitter offers a large bandwidth of 120 nm.     

Non-linear conduction in a quasi one-dimensional conductor at low temperatures

The current-voltage characteristics of a quasi one-dimensional organic system having asymmetric donor molecule like Qn-(TCNQ)₂ pellet with stoichiometry 1:2 grown from acetonitrile as a solvent have been studied atT=69 K. The characteristic curves show a pronounced deviation from ohmicity beyond a certain value of current. For higher values of currents a negative differential resistance region is observed.     

Excess conductivity of thin superconducting films of tin above the transition temperature

The excess conductivity of thin superconducting Sn films has been measured. These films have been grown at room temperature and ～ 77 K on glass substrates. The results show that the pair breaking parameter is not simply and solely related to the normal state sheet resistance but depends also on the substrate temperature.     

On the converse of a theorem of Schur

A well known theorem of Schur states that for any group G, if G/Z(G) is finite, then G′ is finite. We give a very short and elementary proof of a further generalization of the converse of Schur’s theorem proved by Niroomand [5] and Sury [7] and also improve the bound for the order of G/Z(G) obtained by Niroomand and Sury.