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101.
By coupling the bromate-sulfite-ferrocyanide oscillating chemical reaction with the complexation of calcium ion by EDTA, we construct a system that generates periodic pulses of free Ca(2+) with an amplitude of 2 orders of magnitude and a period of ca. 20 min. These pulses may be observed either with a calcium ion-selective electrode or with Arsenazo(III) as an indicator. We describe the systematic design procedure and the properties of this first abiotic calcium-based chemical oscillator. 相似文献
102.
Allan L Leith JL Papakosta M Morrow JA Irving NG McFerran BW Clark AG 《Combinatorial chemistry & high throughput screening》2006,9(1):9-14
The glycine transporter (GlyT-1b) is a Na(+)/Cl(-)-dependent electrogenic transporter which mediates the rapid re-uptake of glycine from the synaptic cleft. Based on its tissue distribution, GlyT-1 has been suggested to co-localise with the NMDA receptor where it may modulate the concentration of glycine at its co-agonist binding site. This data has led to GlyT-1 inhibitors being proposed as targets for disorders such as schizophrenia and cognitive dysfunction. Radiolabelled uptake assays (e.g. [(3)H]glycine) have been traditionally used in compound screening to identify glycine transporter inhibitors. While such an assay format is useful for testing limited numbers of compounds, the identification of novel glycine uptake inhibitors requires a functional assay compatible with high-throughput screening (HTS) of large compound libraries. Here, the authors present the development of a novel homogenous cell-based assay using the FLIPR membrane potential blue dye (Molecular Devices) and FLEXstation. Pharmacological data for the GlyT-1 inhibitors Org 24598 and ALX 5407 obtained using this novel electrogenic assay correlated well with the conventional [(3)H]-glycine uptake assay format. Furthermore, the assay has been successfully miniaturised using FLIPR(3) and therefore has the potential to be used for high-throughput screening. 相似文献
103.
WYETH Paul 《中国科学:化学》2010,(3)
Silks represent some of the most precious ancient and historic textile artefacts in collections worldwide.Their optimum preservation demands an appreciation of their characteristics.One important concern,especially with regard to ancient Chinese silks,is whether the fabrics have been degummed.Silks with remnant sericin gum coating the fibroin fibres would require different conservation protocol.In previous research on aged silks,the presence of sericin has been inferred from amino acid analysis of hydrolysa... 相似文献
104.
The dynamic behavior of a simple elastic tensegrity structure is examined, in order to validate observations that the natural damping of the elastic elements in such a structure is poorly mobilized, due to the natural flexibility of the equilibrium position of the structure. It is confirmed, analytically and numerically, that the energy decay of such a system is slower than that of a linearly-damped system. 相似文献
105.
Irving J. Borowitz Whei-Oh Lin Tze-Chein Wun Robert Bittman Louis Weiss Vladimir Diakiw Grace B. Borowitz 《Tetrahedron》1977,33(14):1697-1705
The preparation of a series of neutral ligands featuring ether and N-methyl-N-carbethoxypentylamide groups is described. These ligands as well as related ones bearing other diamide groups are shown to selectively chelate Group IIA cations by picrate extraction from water to methylene chloride. The changes in UV absorption of aromatic rings and amide groups in the ligands upon titration with metal salts in methanol allow the estimation of the stoichiometry of complexation and the ordering of cation binding. The observed selectivity sequences of cation extraction and binding are briefly discussed. Preliminary proton and 13C NMR studies on the effect of addition of Group IIA cation salts to several of the ligands in methanol suggest that most of the complexation occurs at the central ether and amide groups. 13C NMR T1 changes by the Inversion Recovery Fourier Transform method are in agreement with the cation-induced shift data. 相似文献
106.
Irving M Krueger CA Wade JV Hodges JC Leopold K Collins N Chan C Shaqair S Shornikov A Yan B 《Journal of combinatorial chemistry》2004,6(4):478-486
A 4-amido-pyrrolidone library that was intentionally synthesized as pairs of diastereomers was produced by solution-phase parallel syntheses and purified by an automated high-throughput purification system. A total of 2592 4-amido-pyrrolidinones were ultimately isolated as single diastereomers from a matrix of 1920 syntheses. After the four-step synthesis and HPLC purification, the average yield of a single diastereomer was 36.6%. The average chemical purity was >90%, and the average diastereomeric purity was >87%. The choice of chiral amines used to make amides with heterocyclic acid chlorides had a dramatic effect on success. Analysis of the relationship between amines used for synthesis and the diastereomeric separation showed that amides made from chiral 1,2-amino alcohols gave superior separation to amides from chiral morpholines. The presence of a hydrogen bond donor on the amide side chain seems to be required for a better diastereomeric separation. 相似文献
107.
trans-2-Tribromomethyl-5-trichloromethyl-1,3-dioxolan-4-one is monoclinic,P21/c,a=6.381(6),b=17.116(6),c=10.598(5) Å,=94.07(6)°,Z=4. The structure was solved by direct methods from data collected at room temperature on an Enraf-Nonius CAD4 diffractometer, and refined by full-matrix least squares to a finalR value of 0.042 using 1274 reflections. The conformation of the molecule is very similar to that of chloralide with the 5-mem-bered ring being almost planar. Evidence is provided for a possible C-HO intermolecular interaction. The average C-Br distance is 1.931(11) Å and the average Br-C-Br angle is 109.7(9)°. A table of average C-Br bond lengths and Br-C-Br angles, with the ranges for these parameters, in compounds containing -CBr3 groups is given. Some1H NMR and mass spectra data are included for the title compound and for chloralide. 相似文献
108.
The host compound forms a coordinato-clathrate in a coordination assisted host lattice. The host lattice is provided by hydrogen bonding between the nitrogen atom of the cyano group and two hydrogen atoms from the phosphonium methyl group. Guest molecules ofp-xylene occupy constricted channels in the lattice. The twop-xylene molecules participate in C–H...(Ar)...H–C interactions. Results from searches of the Cambridge Structural Database for other C–H...(Ar)...H–C and C–H...(Ar) interactions are presented. 相似文献
109.
Anne Irving 《Journal of chemical crystallography》1992,22(5):533-540
8-Acetylamino-6-methyl-2,4-bis(trichloromethyl)-1,3-benzdioxin, (I), is monoclinic,P21/c,a=15.174(4),b=11.977(7),c=9.911(3)Å,=99.72(2)°. 6-Acetylamino-2,4-bis(trichloromethyl)-1,3-benzdioxin, (II), is monoclinic,P21/n,a=5.927(4),b=40.623(1),c =7.120(3)Å,=91.39(4)°. In compound (I) the imino hydrogen atom is locked in an intramolecular hydrogen bond to the proximate oxygen atom of the heterocyclic ring and is not available for intermolecular hydrogen bonding. Instead the weakly acidic hydrogen atom [Cl3C-C(2)]H takes part in a hydrogen bond to the carbonyl oxygen atom in another molecule. In compound (II) a normal intermolecular hydrogen bond of the type N-HO=C occurs. The 6-acetylam-ino group is twisted about the (CAr-N) bond such that the angles NHO=C, CArHArO=C, NHOHArCAr, at the carbonyl oxygen group total 360° (where NH is in the related molecule). The packing in both compounds takes the form of infinite chains and in compound (II) partial overlap of the aromatic ring and the acetylamino group, with very little offset, also occurs. 相似文献
110.
2,6-bis (trichloromethyl)-4-dichloromethylene-1-oxa-3,5-dithian is triclinic,P¯1,a=10.125(3),b=10.294(3),c=14.631(10) Å,=92.84(5),=96.51(5), =96.18(2)°,V=1503 Å3,Z=4. The structure was solved by direct methods, from data collected at room temperature on an Enraf-Nonius CAD4 diffractometer, and refined by least squares to a finalR value of 0.035 using 3961 reflections. The conformation of the molecules is twist-boat, one molecule being almost symmetrically twisted about the O-C(Cl2) direction. The range of endocyclic O-C-S angles is 111.8(3) to 115.1(3)° and data are given which support the possibility of there being a correlation between the endocyclic O-C(X)-S angle, the C-O-C(X)-C(Cl3) torsion angle, and the C-S-C(X)-C(Cl3) torsion angle. The -CCl3 groups are in pseudoequatorial positions. Average bond lengths (Å) for the two molecules are C-O 1.405, C(sp
3)-S 1.822, C(sp
2)-S 1.759, C-Ceq 1.529 and average endocyclic angles (°) are O 117.3, C (sp
3) 113.5, S 97.4, C(sp
2) 119.3, the esds on the individual bond lengths and angles being in the ranges of 0.003–0.004 Å and 0.2–0.4° respectively. 相似文献