Search results for "Cyano"
showing 10 items of 1058 documents
Impact of the position isomer of the linkage in the double D–A branch-based organic dyes on the photovoltaic performance
2014
Abstract Three organic dyes with double D–A system were synthesized and applied in the dye-sensitized solar cells. These dyes contain phenothiazine as an electron donor and cyanoacetic acid as an acceptor/anchor. Linkages were incorporated at the ortho-, meta- and para-positions and their impact on the performance of photovoltaic was observed. Among them, the dye with a para-position linkage exhibited the highest short-circuit photocurrent density (12.26 mA cm−2) and open-circuit photovoltage (756 mV), leading to the best overall efficiency (6.14%) due to better light harvesting capacity under standard global 1.5 AM conditions. Under similar measuring conditions the dyes with ortho and meta…
Thermostability of Two Cyanobacterial GrpE Thermosensors
2011
GrpE proteins act as co-chaperones for DnaK heat-shock proteins. The dimeric protein unfolds under heat stress conditions, which results in impaired interaction with a DnaK protein. Since interaction of GrpE with DnaK is crucial for the DnaK chaperone activity, GrpE proteins act as a thermosensor in bacteria. Here we have analyzed the thermostability and function of two GrpE homologs of the mesophilic cyanobacterium Synechocystis sp. PCC 6803 and of the thermophilic cyanobacterium Thermosynechococcus elongatus BP1. While in Synechocystis an N-terminal helix pair of the GrpE dimer appears to be the thermosensing domain and mainly mediates GrpE dimerization, the C-terminal four-helix bundle i…
Influence of the polymerization step alone on oxygen affinity and cooperativity during production of hyperpolymers from native hemoglobins with cross…
1994
The aim of this study was to find out how the polymerization per se changes oxygen affinity (P50) and cooperativity (n50) of various soluble huge hyperpolymers prepared from native hemoglobins by crosslinking. Increase of cooperativity would be expected considering natural hemoglobin networks. Those hyperpolymers with molecular weights of some 10(6) g/mol are candidates for artificial oxygen-carrying blood additives rather than volume substitutes. Human and bovine hemoglobin reacted with several crosslinkers (2,5-diisothiocyanatobenzenesulfonate (DIBS); 4,4'-diisothiocyanatostilbene-2, 2'-disulfonate (DIDS); 1,3-butadiene diepoxide (BUDE); glutaraldehyde (GDA)) in concentrated (case 1) and …
Ab Initio Modeling of Donor–Acceptor Interactions and Charge-Transfer Excitations in Molecular Complexes: The Case of Terthiophene–Tetracyanoquinodim…
2015
This work presents a thorough quantum chemical study of the terthiophene-tetracyanoquinodimethane complex as a model for π-π donor-acceptor systems. Dispersion-corrected hybrid (B3LYP-D) and double hybrid (B2PLYP-D), hybrid meta (M06-2X and M06-HF), and recently proposed long-range corrected (LC-wPBE, CAM-B3LYP, and wB97X-D) functionals have been chosen to deal with π-π intermolecular interactions and charge-transfer excitations in a balanced way. These properties are exhaustively compared to those computed with high-level ab initio SCS-MP2 and CASPT2 methods. The wB97X-D functional exhibits the best performance. It provides reliable intermolecular distances and interaction energies and pre…
Charge transfer in the novel donor-acceptor complexes tetra- and hexamethoxypyrene with tetracyanoquinodimethane studied by HAXPES
2012
Abstract The effect of charge transfer (CT) in complexes of the donors tetra - and hexamethoxyprene ( TMP and HMP ) with the classical acceptor tetracyanoquinodimethane ( TCNQ ) was studied using hard X-ray photoemission (HAXPES). Microcrystals of the complex were grown via vapour diffusion from donor–acceptor mixtures. The bulk sensitivity of HAXPES at a photon energy of 6 keV completely eliminates the problem of surface contamination for such delicate organic materials grown from solution. The donor molecules were produced using a novel synthesis route functionalizing polycyclic aromatic hydrocarbons at their periphery. For comparison, spectra were also taken from thin-film samples of the…
Electrocatalytic carboxylation of chloroacetonitrile at a silver cathode for the synthesis of cyanoacetic acid
2008
Abstract The electrocatalytic carboxylation of chloroacetonitrile to cyanoacetic acid performed at silver cathodes was investigated both theoretically and experimentally. Silver exhibits powerful electrocatalytic activities towards the reduction of chloroacetonitrile. In CO 2 -saturated CH 3 CN, reduction of NCCH 2 Cl occurs at potentials that are about 0.7 V more positive than those observed at glassy carbon and gives cyanoacetic acid in good yields. Theoretical considerations on the effect of operative parameters on the performances of the process were confirmed by electrocarboxylation experiments performed in undivided cells equipped with sacrificial anodes both in a bench-scale electroc…
Elucidating the picocyanobacteria salinity divide through ecogenomics of new freshwater isolates
2022
Abstract Background Cyanobacteria are the major prokaryotic primary producers occupying a range of aquatic habitats worldwide that differ in levels of salinity, making them a group of interest to study one of the major unresolved conundrums in aquatic microbiology which is what distinguishes a marine microbe from a freshwater one? We address this question using ecogenomics of a group of picocyanobacteria (cluster 5) that have recently evolved to inhabit geographically disparate salinity niches. Our analysis is made possible by the sequencing of 58 new genomes from freshwater representatives of this group that are presented here, representing a 6-fold increase in the available genomic data. …
Minireview: Nicotinic Acetylcholine Receptors on Hippocampal Neurons: Distribution on the Neuronal Surface and Modulation of Receptor Activity
1997
The recent development of a technique that uses infrared microscopy for the visualization of well-defined areas on the surface of neurons, and a computerized system of micromanipulators led to the discovery that functional nicotinic acetylcholine receptors (nAChRs) are expressed at higher density on the dendrites than on the soma of rat hippocampal neurons. The finding that the expression of alpha-bungarotoxin-sensitive, alpha 7-bearing, nAChRs and dihydro-beta-erythroidine-sensitive, alpha 4 beta 2 nAChRs tends to increase along the dendritic length suggests that these receptors may be highly involved in the integration of synaptic functions in hippocampal neurons. The present report also …
Differential response of benthic microbes and meiofauna to fish-farm disturbance in coastal sediments
2001
Bacterial and meiofaunal abundance and biomass and their response to the disturbance induced by fish-farm biodeposition were investigated from March to October 1997 on a monthly basis at two stations of the Gaeta Gulf (Tyrrhenian Sea, Mediterranean Sea). The biopolymeric fraction of the organic matter was characterized by high concentrations which was similar at both fish-farming-impacted and control stations. Similarly, bacteria accounted for a small fraction of the biopolymeric organic carbon (<1%), while the contribution due to auto-fluorescent cell biomass (i.e. prokaryotic and eukaryotic cells displaying auto-fluorescence) to the total biopolymeric carbon was quantitatively negligible …
Non-degenerate 1,2-silyl shift in silyl substituted alkyltrimethylcyclopentadienes
2005
Abstract The five new silanes C5Me3RSiMenCl3 − n (n = 3, R = i-Pr (5); n = 2, R = i-Pr (6); n = 2, R = s-Bu (7); n = 2, R = cyclohexyl (8); and n = 3, R = t-Bu (9)) were synthesized by reaction of 1-alkyl-2,3,4-trimethylcyclopentadienyl lithium salts with appropriate chlorosilane and characterized by NMR, MS, and IR spectra. At elevated temperatures (250–360 K), all the silanes undergo a non-degenerate sigmatropic silyl rearrangement, which generates non-equivalent structures a and b. The presence of minor structure c was observed in compounds 5 and 7 only. The Diels–Alder cycloaddition of 5 with strong dienophiles tetracyanoethylene (TCNE), and dimethylacetylenedicarboxylate (DMAD) provide…