Structure of l-Diphenylmethyl-3-hydroxyazetidinium Chloride,* C 16 H lsN O+.CI -

M r=275.8, monoclinic, P21/a, a= 12.356 (5), b=9.054 (4), c= 14.043 (4) A, t= 100.34 (3) ° , V=1545.5A 3, Z=4, D,,,= 1.14, D x = 1.185 Mg m -3, p(Mo Ka, /l = 0.7107 ]k) = 2.77 mm -1, F(000) = 584.0, T= 293 K, R = 0.053 for 1088 reflections. The four-membered ring is buckled 13.0 ° (0= 167.0°). The azetidinium moiety is linked to the C1- ion through a hydrogen bond [O-H...C1 = 3.166 (5) A].

Evolution of texture during equal channel angular extrusion of commercially pure aluminum: Experiments and simulations

The evolution of crystallographic texture has been comprehensively studied for commercially pure Al as a function of amount of ECAE deformation for the three major routes of ECAE processing. It has been observed that processing through different routes leads to different type of texture, in both qualitative as well as quantitative sense. The results have been analyzed on the basis of existing concepts on ECAE deformation and simulations have been carried out using the simple shear model of ECAE implemented into the Viscoplastic Self Consistent model of polycrystal plasticity. The simulations revealed that non-octahedral slip is needed to reproduce the experimental texture development.

Mixed ligand complexes in vinyl polymerization-II: [NN′-ethylenebis(salicylideneiminato)] (benzoylacetonato)cobalt(III) as an initiator

The polymerization of methyl methacrylate initiated by a mixed ligand complex. [NN′-ethylenebis(salicylideneiminato)](benzoylacetonato)cobalt(III) has been studied in bulk and in benzene at 70° and 80°. The rate of polymerization is proportional to (concentration of the chelate)1/2 and the monomer exponent is close to 1.5. The activation energy and the kinetic and transfer constants are evaluated. A free radical mechanism has been proposed.

Conformation And C-N Rotational Barrier Of Dithiocarbamate Esters Nmr And Molecular-Orbital Studies

The variable temperature proton and ambient temperature carbon-13 NMR spectra of S-methyl dithiocarbamate esters have been recorded. The results of the theoretical energy calculations (CNDO/2 and EHT types) together with the experimental data have been interpreted in terms of the molecular conformations. The barrier heights for the rotation about the thioamide C—N bond are calculated using the CNDO/2 method and the results are discussed in terms of the computed charge densities and bond orders.

The Structure of the Monosodium Salt of Cytidine(5')diphosphoethanolamine

CI1H19N4OIIP2.Na+.TH2 O, Mr = 594.08, is orthorhombic, space group P21212 l, with a = 6.946 (2), b = 12.503 (4), c = 28.264 (8)/k, U = 2454.6 A, a, D x = 1.61 Mg m -a, Z = 4, ~t(CuKa) = 2.612 mm -1, F(000) = 1244. Final R = 0.101 for 1454 observed reflections. The cytosine base is in the anti conformation with respect to the sugar (ZCN = 62"60) . The ribose exhibits an uncommon C(l')exo-C(2')endo puckering. The pyrophosphate has a characteristic staggered geometry. The conformation about P(2)-O(7') is trans (-103.4°). This makes CDPethanolamine more extended compared to the folded geometry of CDP-choline, which has a gauche conformation (71.3 o). The molecular interactions in the extended crystal structure, however, are similar to those found in CDP-choline, with the CMP-5' portions tightly bound by metal ligation and the phosphorylethanolamine parts only loosely held by water molecules.

Separation β-apocarotenals and related compounds by reversed-phase paper and thin-layer chromatography

Abstract is not available.

Cross Talk between Receptor Guanylyl Cyclase C and c-src Tyrosine Kinase Regulates Colon Cancer Cell Cytostasis

Increased activation of c-src seen in colorectal cancer is an indicator of a poor clinical prognosis, suggesting that identification of downstream effectors of c-src may lead to new avenues of therapy. Guanylyl cyclase C (GC-C) is a receptor for the gastrointestinal hormones guanylin and uroguanylin and the bacterial heat-stable enterotoxin. Though activation of GC-C by its ligands elevates intracellular cyclic GMP (cGMP) levels and inhibits cell proliferation, its persistent expression in colorectal carcinomas and occult metastases makes it a marker for malignancy. We show here that GC-C is a substrate for inhibitory phosphorylation by c-src, resulting in reduced ligand-mediated cGMP production. Consequently, active c-src in colonic cells can overcome GC-C-mediated control of the cell cycle. Furthermore, docking of the c-src SH2 domain to phosphorylated GC-C results in colocalization and further activation of c-src. We therefore propose a novel feed-forward mechanism of activation of c-src that is induced by cross talk between a receptor GC and a tyrosine kinase. Our findings have important implications in understanding the molecular mechanisms involved in the progression and treatment of colorectal cancer.

Ni(II)chelates of 4,9-dimethyl-5,8-dizadodeca-4,8-diene-2,11-dione-3,10-diphenyl hydrazone and related molecules

Syntheses and structural characterization of Ni(II) chelates of a new series of symmetric and unsymmetric tetradentate linear ligands are described. Preparative routes involve either the direct reaction between a metal complex and arene diazonium diazonium salts or a simple metal incorporation into the independently synthesized ligands. Recent X-ray structure determination of 4,9-dimethyl-5,8-diazadodeca-4,8-diene-2,11-dione-3,10-di(4′-methyl phenyl) hydrazonatonickel(II) complex reveals the geometry around the Ni(II) to be very close to square planar. The expected distortion because of the disposition of bulky aromatic groups on the neighbouring nitrogens is minimized by their projection in the opposite directions from the plane. PMP, IR and electronic spectral data for the complexes are quite in agreement with this structure.

Role of heme in the synthesis of cytochrome c oxidase in Neurospora crassa

The role of heme in the synthesis of cytochrome c oxidase has been investigated in the mold Neurospora crassa. Iron-deficient cultures of the mold have low levels of cytochrome oxidase and delta-aminolevulinate dehydratase, the latter being the rate-limiting enzyme of the heme-biosynthetic pathway in this organism. Addition of iron to the iron-deficient cultures results in an immediate increase in the levels of delta-aminolevulinate dehydratase followed by an increase in the rate of heme synthesis and cytochrome oxidase levels. The rate of precursor labeling of the mitochondrial subunits of cytochrome oxidase is decreased preferentially under conditions of iron deficiency and addition of iron corrects this picture. Exogenous hemin addition which prevents iron-mediated induction of delta-aminolevulinate dehydratase also inhibits the increase in the activity of cytochrome oxidase and the enhanced precursor labeling of the mitochondrial subunits of cytochrome oxidase. Protein synthesis on mitoribosomes measured in vivo and in vitro is decreased under conditions of heme deficiency. Hemin addition in vitro to mitochondrial lysates prepared from heme-deficient mycelia restores a near normal rate of protein synthesis. It is concluded that heme is required for the optimal rate of translation on mitoribosomes.

Oxonium salt intermediates from half ester acid chlorides

Isomeric half eater acid chlorides derived from 1,2-and 1-3-carboxylic acids give rise to the same oxonium salt with Lewis acids.

Two-dimensional heat conduction with phase change in a semi-infinite mould

Analytical solution of a 2-dimensional problem of solidification of a superheated liquid in a semi-infinite mould has been studied in this paper. On the boundary, the prescribed temperature is such that the solidification starts simultaneously at all points of the boundary. Results are also given for the 2-dimensional ablation problem. The solution of the heat conduction equation has been obtained in terms of multiple Laplace integrals involving suitable unknown fictitious initial temperatures. These fictitious initial temperatures have interesting physical interpretations. By choosing suitable series expansions for fictitious initial temperatures and moving interface boundary, the unknown quantities can be determined. Solidification thickness has been calculated for short time and effect of parameters on the solidification thickness has been shown with the help of graphs.

Moiré Displacement Transducer for N/C Systems

Noncontact method of sensing accurately the magnitude and direction of displacements is essential in systems such as the numerically controlled machines. A displacement transducer, using Moiré transmission gratings is described. The notable feature of this instrument is that it requires only gratings of small lengths, even for measurement of large displacements.

D.c. and a.c. polarographic behaviour of vanadium-glycine complexes

A detailed investigation of the d.c. polarographic behaviour of vanadium(V),-(IV) and -(III) in glycine solutions has been made keeping the total glycine concentration at 0.1, 0.5 and 1.0 M and varying the pH of the solution. Experiments keeping the pH constant (using different ratios of glycine and glycine anion) and varying the glycine anion concentration, and also in predominantly anion solutions, have been made.