Isolation of onosmins A and B, lipoxygenase inhibitors from Onosma hispida

Onosmins A (1) and B (2), lipoxygenase inhibitors, have been isolated from Onosma hispida. Their structures were established as 2-[(4-methylbenzyl)amino]benzoic acid (1) and methyl 2-[(4-methylbenzyl)amino]benzoate (2) through spectroscopic studies, including 2D-NMR. The known compounds apigenin (3), 6,4'-dimethoxy-3,5,7-trihydroxyflavone (4), 6,7-dimethoxy-3,5,4'-trihydroxyflavone (5) and apigenin 7-O-beta-D-glucoside (6) are also reported for the first time from this species. Compounds (1) and (2) inhibited lipoxygenase (LOX, EC 1.13.11.12) enzyme in a concentration-dependent fashion with IC50 values of 24.0 and 36.2 microM, respectively. Lineweaver-Burk as well as Dixon plots and their secondary replots indicated that the nature of inhibition was purely a non-competitive type, with K(i) values 22.0 microM and 31.1, respectively.     

Lipoxygenase inhibiting constituents from Indigofera hetrantha

A lignan and two acylphloroglucinols have been isolated from the ethyl acetate soluble fraction of the whole plant of Indigofera hetrantha. Their structures have been assigned on the basis of spectral analysis including 1D and 2D NMR techniques. Compounds 1-3 displayed promising inhibitory potential against enzyme lipoxygenase in concentration-dependent manner.     

Tyrosinase-inhibitory long-chain esters from Amberboa ramosa

Long-chain esters 1 and 2 have been isolated from the chloroform-soluble fraction of Amberboa ramosa and their structures assigned to be methyl 2beta(2S)-hydroxyl-7(E)-tritriacontenoate (1) and methyl 2beta(2S)-O-beta-D-galactopyranosyl-7(E)-tetratriacontenoate (2). In addition, tricontane (3) and apigenin (4) are also reported for the first time from this species. The structures were assigned on the basis of 1D and 2D NMR techniques. Compounds 1 and 2 showed strong to moderate inhibitory activity against tyrosinase.     

Replacement of native copper in superoxide dismutase with copper-64 without much loss in its enzymatic activity

Superoxide dismutase, containing copper and zinc, has been labeled with copper-64 by incubating the prepared apoenzyme with cupric(65) chloride at room temperature. No significant loss in the enzymatic activity was observed after labeling. The incorporation of copper-64 was ascertained by starch gel electrophoresis and high performance liquid chromatography. The labeling efficiency was found to be >95%.     

Cucurbitacin glucosides from Citrullus colocynthis

A new cucurbitacin glucoside 2-O-beta-D-glucopyranosyl-16alpha-20R-dihydroxy-cucurbita-1,5,23E,25(26)-tetraen-3,11,22-trione (1) has been isolated from the methanolic extract of the fruits of Citrulluscolocynthis. The structure has been assigned on the basis of spectral analysis including 1D and 2D NMR techniques. In addition 2-O-beta-D-glucopyranosyl-cucurbitacin B (arvenin I) (2) and 2,25-di-O-beta-D-glucopyranosyl-cucurbitacin L (3) are reported for the first time from this species.     

Dual beam method for laser welding of galvanized steel: Experimentation and prospects

Laser welding of zinc-coated steel sheets in lap configuration poses a challenging problem, because of the zinc vapours spoiling the quality of the weld. In continuation to the earlier work, the novel solution of dual laser beam method for lap welding of galvanized steel sheets is discussed here in view of the recently obtained observations and ensuing concerns. In this method the precursor beam cuts a slot, thus making an exit path for the zinc vapours, while the second beam performs the needed welding. The metallurgical analysis of the welds is encouraging showing absence of zinc in the welded area. In the current work on this technique, new experimental results have been obtained verifying the earlier observations. Along with this, the possibility of using a transversely split-up beam for the welding purposes with this approach is discussed and analyzed in this paper. This new technique is expected to be very useful in prospective industrial applications requiring higher welding throughput along with the needed quality.     

Depth and Stanley depth of the edge ideals of square paths and square cycles

In this paper, we compute depth and Stanley depth for the quotient ring of the edge ideal associated to a square path on n vertices. We also compute depth and Stanley depth for the quotient ring of the edge ideal associated to a square cycle on n vertices, when n≡0,3,4( mod 5), and give tight bounds when n≡1,2( mod 5). We also prove a conjecture of Herzog presented in [5 Herzog, J. (2013). A survey on Stanley depth. In: Bigatti, M. A., Gimenez, P., Sáenz-de-Cabezón, E., eds. Monomial Ideals, Computations and Applications. Lecture Notes in Mathematics, Vol. 2083. Heidelberg: Springer, pp. 3–45. https://arxiv.org/pdf/1702.00781.pdf.[Crossref] , [Google Scholar]], for the edge ideals of square paths and square cycles.     

Synthesis,Crystal Structure and Spectroscopy of 3,4-Perylene-dicarboxylic Monoanhydride

The preparation, via a chemical vapor deposition process, of metallic-green whiskers of 3,4-perylenedicarboxylic monoanhydride (PDCMA), is described. The crystal structure and the electronic, infrared and resonance-enhanced Raman spectra of the PDCMA crystals are reported and compared with the corresponding data for the dianhydride, PTCDA. Interesting differences in the spectroscopy of PDCMA compared with that of PTCDA have been found. This has been correlated with the somewhat increased charge delocalization in PDCMA caused by the packing of the molecules in the crystal. The application of some of these results in characterizing the partly solid state, heat-induced polymerization of PTCDA to the intrinsically conducting polymer, polyperinaphthalene, is also pointed out.     

Enhancement of the electrical properties of carbon nanotubes with Ar–N2 plasma treatment

Optical emission spectroscopy and Langmuir probe are used to investigate the low pressure inductively coupled Ar–N₂ plasmas as function of rf power, filling pressure and Ar content in N₂ discharge. It is observed that the active species generation, dissociation fraction and electron temperature significantly depends on discharge parameters and may be used to optimize the plasma reactor. Mixture of SWCNTs and MWCNTs are treated for different treatment time (0–120 min) at optimum discharge conditions. Changes induced in the elemental composition, surface morphology, crystallographic structure, and structural disorder in the plasma irradiated CNTs are analyzed by EDX, FTIR, SEM, XRD and Raman spectroscopy, respectively. Ar–N₂ mixture plasma treatment of CNTs lead to a significant increase in the electrical conductivity, modify the microstructure and induce structural disorder and cause a transition of crystalline phase from well crystalline to an amorphous structure.