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71.
Grégoire Herzog Patrycja Eichelmann-Daly Damien W.M. Arrigan 《Electrochemistry communications》2010,12(3):335-337
We report here the influence of chemical denaturation of haemoglobin on its electrochemical behaviour at the polarised liquid|liquid interface. Denaturation with urea resulted in a modification of the haemoglobin electrochemical behaviour, with the disappearance of the forward transfer peak and a decrease of the reverse peak current. Although the reverse peak current increased linearly with the concentration of denatured haemoglobin in the aqueous phase, the slope of the current-concentration plot was three-times lower than that for native haemoglobin over the 0.1–1 μM concentration range. These results indicate the sensitivity of electrochemistry at liquid|liquid interfaces to protein tertiary structure. 相似文献
72.
Dąbrowska-Maś E Frączyk T Ruman T Radziszewska K Wilk P Cieśla J Zieliński Z Jurkiewicz A Gołos B Wińska P Wałajtys-Rode E Leś A Nizioł J Jarmuła A Stefanowicz P Szewczuk Z Rode W 《Organic & biomolecular chemistry》2012,10(2):323-331
Highly purified preparations of thymidylate synthase, isolated from calf thymus, and L1210 parental and FdUrd-resistant cells, were found to be nitrated, as indicated by a specific reaction with anti-nitro-tyrosine antibodies, suggesting this modification to appear endogenously in normal and tumor tissues. Each human, mouse and Ceanorhabditis elegans recombinant TS preparation, incubated in vitro in the presence of NaHCO(3), NaNO(2) and H(2)O(2) at pH 7.5, underwent tyrosine nitration, leading to a V(max)(app) 2-fold lower following nitration of 1 (with human or C. elegans TS) or 2 (with mouse TS) tyrosine residues per monomer. Enzyme interactions with dUMP, meTHF or 5-fluoro-dUMP were not distinctly influenced. Nitration under the same conditions of model tripeptides of a general formula H(2)N-Gly-X-Gly-COOH (X = Phe, Tyr, Trp, Lys, Arg, His, Ser, Thr, Cys, Gly), monitored by NMR spectroscopy, showed formation of nitro-species only for H-Gly-Tyr-Gly-OH and H-Gly-Phe-Gly-OH peptides, the chemical shifts for nitrated H-Gly-Tyr-Gly-OH peptide being in a very good agreement with the strongest peak found in (15)N-(1)H HMBC spectrum of nitrated protein. MS analysis of nitrated human and C. elegans proteins revealed several thymidylate synthase-derived peptides containing nitro-tyrosine (at positions 33, 65, 135, 213, 230, 258 and 301 in the human enzyme) and oxidized cysteine (human protein Cys(210), with catalytically critical Cys(195) remaining apparently unmodified) residues. 相似文献
73.
Dynarowicz Łatka P Pérez-Morales M Muñoz E Broniatowski M Martín-Romero MT Camacho L 《The journal of physical chemistry. B》2006,110(12):6095-6100
The behavior of a semi-fluorinated alkane (C(10)F(21)C(19)H(39)) has been studied at the air-water interface by using surface pressure and surface potential-area isotherms as well as infrared spectroscopy for the Langmuir-Blodgett films. In addition, based on the quantum chemical PM3 semiempirical approach, the dimer structure was investigated, and the double helix was found to be the most stable conformation of the dimer. The obtained results allow us to imply that the phase transition observed in the course of the surface pressure/area isotherm is due to a conformational change originating from the double helix to a vertical, single helix configuration. 相似文献
74.
Exciplex Emission from a Boron Dipyrromethene (Bodipy) Dye Equipped with a Dicyanovinyl Appendage
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Adela Nano Dr. Raymond Ziessel Patrycja Stachelek Dr. Mohammed A. H. Alamiry Prof. Dr. Anthony Harriman 《Chemphyschem》2014,15(1):177-186
The photophysical properties of a prototypic donor–acceptor dyad, featuring a conventional boron dipyrromethene (Bodipy) dye linked to a dicyanovinyl unit through a meso‐phenylene ring, have been recorded in weakly polar solvents. The absorption spectrum remains unperturbed relative to that of the parent Bodipy dye but the fluorescence is extensively quenched. At room temperature, the emission spectrum comprises roughly equal contributions from the regular π, π* excited‐singlet state and from an exciplex formed by partial charge transfer from Bodipy to the dicyanovinyl residue. This mixture moves progressively in favor of the locally excited π, π* state on cooling and the exciplex is no longer seen in frozen media; the overall emission quantum yield changes dramatically near the freezing point of the solvent. The exciplex, which has a lifetime of approximately 1 ns at room temperature, can also be seen by transient absorption spectroscopy, in which it decays to form the locally excited triplet state. Under applied pressure (P<170 MPa), formation of the exciplex is somewhat hindered by restricted rotation around the semirigid linkage and again the emission profile shifts in favor of the π, π* excited state. At higher pressure (170<P<550 MPa), the molecule undergoes reversible distortion that has a small effect on the yield of π, π* emission but severely quenches exciplex fluorescence. In the limiting case, this high‐pressure effect decreases the molar volume of the solute by approximately 25 cm3 and opens a new channel for nonradiative deactivation of the excited‐state manifold. 相似文献
75.
Miroslav Mrlik Michal Sedlacik Vladimir Pavlinek Patrycja Bober Miroslava Trchová Jaroslav Stejskal Petr Saha 《Colloid and polymer science》2013,291(9):2079-2086
Aniline oligomers were prepared by the oxidation of aniline with p-benzoquinone in aqueous solutions of methanesulfonic acid (MSA) of various concentrations. Their molecular structures were assessed by Fourier transform infrared spectroscopy. The electrorheological (ER) behavior of their silicone oil suspensions under applied electric field has been investigated. Shear stress at a low shear rate, τ 0.9, was used as a criterion of the rigidity of internal structures created by the application of an electric field. It was established from the fitting of the dielectric spectra of the suspensions with the Havriliak–Negami model that dielectric relaxation strength, as a degree of polarization induced by an external field contributing to the enhanced ER effect, increases and relaxation time, i.e., the response of the particle to the application of the field, decreases when a higher molar concentration of MSA is used. The best values were observed for suspensions of the sample prepared in the presence of 0.5 M of MSA. This suspension creates stiff internal structures under an applied electric field strength of 2 kV mm?1 with τ 0.9 of nearly 50 Pa, which is even slightly of higher value than that obtained for standard polyaniline base ER suspension measured at the same conditions. The concentration of the MSA used in the preparation of oligomers seems to be a crucial factor influencing the conductivity, dielectric properties and, consequently, rheological behavior, and finally ER activity of their suspensions. 相似文献
76.
Performance of selective and partially selective sensors in the recognition of beverages 总被引:1,自引:0,他引:1
A sensor array composed of selective and partially selective electrodes is applied to the recognition of beverages: milk, orange juice, and beer. The role of selective and partially selective sensors in classification results is discussed. For this reason two experiments are realized: distinguishing among various types of foodstuffs and the recognition of their origin (manufacturer). In both cases, the measurements were performed in stationary and flow mode. Classical ion-selective electrodes and miniaturized solid-state electrodes were considered.The best results are obtained when the two types of sensor are incorporated in the array, which leads to the highest correctness of the system response. It is however worth to notice, that in the case of some samples (for example, milk) satisfactory results were obtained when only selective or when only partially selective electrodes were applied. 相似文献
77.
Patrycja Bober Jaroslav Stejskal Miroslava Trchov�� Jan Proke? 《Journal of Solid State Electrochemistry》2011,15(11-12):2361-2368
The oxidation of aniline with silver nitrate in 1?mol?L?1 acetic acid at 20?°C yielded a composite of two conducting components, polyaniline and silver; the acceleration with 1?mol% of p-phenylenediamine is needed for efficient synthesis. The yield and molecular weight increased when aniline was copolymerized with 10?mol% p-phenylenediamine. Such product displayed metallic conductivity below 180?K and semiconductor type above this temperature. As the result, the conductivity was the same at 100 and 300?K. The oxidation of p-phenylenediamine alone with silver nitrate also produced a conducting composite having the conductivity of 1,750?S cm?1 despite the assumed nonconductivity of poly(p-phenylenediamine). The present study demonstrates that all oxidations proceeded also in frozen reaction mixtures at ?24?°C, i.e., in the solid state. In most cases, molecular weights of polymer component increased, the conductivity of composites with silver improved, to 2,990?S?cm?1 for poly(p-phenylenediamine)?Csilver, and remained high after deprotonation with 1?mol?L?1 ammonium hydroxide. 相似文献
78.
Patrycja ?ak Mariusz Majchrzak Cezary Pietraszuk 《Journal of organometallic chemistry》2011,696(4):887-891
A series of functionalised cubic monovinylheptaisobutylsilsesquioxanes and octavinylsilsesquioxanes were obtained via efficient and highly stereoselective cross-metathesis and silylative coupling with substituted styrenes. 相似文献
79.
Nitoń P Żywociński A Paczesny J Fiałkowski M Hołyst R Glettner B Kieffer R Tschierske C Pociecha D Górecka E 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(21):5861-5873
Aggregation in Langmuir films is usually understood as being a disorderly grouping of molecules turning into chaotic three-dimensional aggregates and is considered an unwanted phenomenon causing irreversible changes. In this work we present the studies of 11 compounds from the group of specific surfactants, known as bolaamphiphiles, that exhibit reversible aggregation and, in many cases, transition to well-defined multilayers, which can be considered as a layering transition. These bolaamphiphiles incorporate rigid π-conjugated aromatics as hydrophobic cores, glycerol-based polar groups and hydrophobic lateral chains. Molecules of different shapes (X-, T-, and anchor) were studied and compared. The key property of these compounds is the partial fluorination of the lateral chains linked to the rigid cores of the molecules. The most interesting feature of the compounds is that, depending on their shape and degree of fluorination, they are able to resist aggregation and preserve a monolayer structure up to relatively high surface pressures (T-shaped and some X-shaped molecules), or create well-defined trilayers (X- and anchor-shaped molecules). Experimental studies were performed using Langmuir balance, surface potential and X-ray reflectivity measurements. 相似文献
80.
Patrycja Gliska Andrzej Wolan Wojciech Kujawski Edyta Rynkowska Joanna Kujawa 《Molecules (Basel, Switzerland)》2021,26(14)
There has been an ongoing need to develop polymer materials with increased performance as proton exchange membranes (PEMs) for middle- and high-temperature fuel cells. Poly(vinyl alcohol) (PVA) is a highly hydrophilic and chemically stable polymer bearing hydroxyl groups, which can be further altered. Protic ionic liquids (proticILs) have been found to be an effective modifying polymer agent used as a proton carrier providing PEMs’ desirable proton conductivity at high temperatures and under anhydrous conditions. In this study, the novel synthesis route of PVA grafted with fluorinated protic ionic liquids bearing sulfo groups (–SO3H) was elaborated. The polymer functionalization with fluorinated proticILs was achieved by the following approaches: (i) the PVA acylation and subsequent reaction with fluorinated sultones and (ii) free-radical polymerization reaction of vinyl acetate derivatives modified with 1-methylimidazole and sultones. These modifications resulted in the PVA being chemically modified with ionic liquids of protic character. The successfully grafted PVA has been characterized using 1H, 19F, and 13C-NMR and FTIR-ATR. The presented synthesis route is a novel approach to PVA functionalization with imidazole-based fluorinated ionic liquids with sulfo groups. 相似文献