排序方式: 共有135条查询结果,搜索用时 203 毫秒
61.
Hac-Wydro K Wydro P Dynarowicz-Łatka P 《Journal of colloid and interface science》2005,286(2):504-510
Langmuir monolayers of cholesterol/ergosterol and dialkyldimethylammonium bromides (DXDABs) differing in alkyl chain length-14 (DTDAB), 16 (DHDAB), and 18 (DODAB)-spread at the air/water interface are examined. All the systems investigated are found to be nonideal and miscible. Negative values of the total free energy of mixing, proving film stability in the whole range of compositions and surface pressures, are observed for all the studied mixtures except for DTDAB/cholesterol. The strength of interactions, quantified with DeltaG(Exc) values, was found to be of the same order for mixtures of cholesterol/ergosterol and DHDAB or DODAB. Differences occurring for the mixtures of DTDAB with sterols indicate the affinity of DTDAB to ergosterol in contrast to cholesterol. 相似文献
62.
Quantitative Analysis of Active Pharmaceutical Ingredients (APIs) Using a Potentiometric Electronic Tongue in a SIA Flow System
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An advanced potentiometric electronic tongue and Sequential Injection Analysis (SIA) measurement system was applied for the quantitative analysis of mixtures containing three active pharmaceutical ingredients (APIs): acetaminophen, ascorbic acid and acetylsalicylic acid, in the presence of various amounts of caffeine as interferent. The flow‐through sensor array was composed of miniaturized classical ion‐selective electrodes based on plasticized PVC membranes containing only ion exchangers. Partial Least Squares (PLS) analysis of the steady‐state sensor array responses, measured in API mixtures prepared by the SIA system permitted a correct quantitative analysis of acetylsalicylic acid and ascorbic acid. Further optimization using multiway PLS fed by dynamic responses without additional feature extraction did not improve significantly the resolution of acetaminophen. Lastly, the chemometric treatment, involving the extraction of dynamic components of the transient response employing the Wavelet transform, the removal of less‐significant coefficients by means of Causal Index pruning and training of an Artificial Neural Network (ANN) with the selected coefficients, allowed the simultaneous determination of all the three studied APIs, while counterbalancing any interference due to caffeine. 相似文献
63.
Dr. Lea Gundorff Nielsen Dr. Anne Katrine Ravnsborg Hansen Dr. Patrycja Stachelek Dr. Robert Pal Prof. Dr. Thomas Just Sørensen 《欧洲无机化学杂志》2023,26(24):e202300245
Since the pioneering report by Selvin, we have been fascinated by the potential of using lanthanide luminescence in bioimaging. The uniquely narrow emission lines and long luminescence lifetimes both provide the potential for background free images together with full certainty of probe localization. General use of lanthanide based bioimaging was first challenged by low brightness, and later by the need of UV (<405 nm) excitation sources not present in commercial microscopes. Here, we designed three lanthanide-based imaging probes based on a known motif to investigate the limitations of 405 nm excitation. These were synthesized, characterized, investigated on dedicated as well as commercial microscopes, and the photophysics was explored in detail. It was proven without doubt that the lanthanide complexes enter the cells and luminesce internally. Even so, no lanthanide luminescence were recovered on the commercial microscopes. Thus, we returned to the photophysical properties that afforded the conclusion that – despite the advances in light sources and photodetectors – we need new designs that can give us brighter lanthanide complexes before bioimaging with lanthanide luminescence becomes something that is readily done. 相似文献
64.
Graphitized carbons, Carbopack X, Carbograph 5TD and Carbotrap B, used to enrich samples of C(3)-C(4) alcohols determined in the atmospheric air produce experimental artefacts. After thermal desorption, recoveries for alcohols are much smaller than unity with a concomitant appearance of aldehydes and ketones on chromatograms. Obviously, the adsorbents studied cannot be recommended for analysis of alcohols, ketones and aldehydes in the atmosphere. Polymeric adsorbents, Tenax TA and Chromosorb 106, do not exhibit such oxidative properties. 相似文献
65.
Agnieszka Łupicka-Słowik Mateusz Psurski Renata Grzywa Kamila Bobrek Patrycja Smok Maciej Walczak Andrzej Gaweł Tadeusz Stefaniak Józef Oleksyszyn Marcin Sieńczyk 《Applied biochemistry and biotechnology》2018,184(4):1358-1374
Adenosine deaminase (ADA) is currently used as a diagnostic marker for tuberculous pleuritis. Although ADA has been suggested as a potential marker for several types of cancer, the importance of each of ADA isoforms as well as their levels and enzymatic activities in tumors need to be further investigated. Herein we developed avian immunoglobulin Y highly specific to human ADA via hens immunization with calf adenosine deaminase. The obtained antibodies were used for the development of a sensitive double-egg yolk immunoglobulin (IgY) sandwich ELISA assay with an ADA detection limit of 0.5 ng/ml and a linearity range of up to 10 ng/ml. Specific, affinity-purified IgYs were able to recognize human recombinant ADA and ADA present in human cancer cell lines. In addition, antigen-specific IgY antibodies were able to inhibit catalytic activity of calf ADA with an IC50 value of 47.48 nM. We showed that generated IgY antibodies may be useful for ADA detection, thus acting as a diagnostic agent in immunoenzymatic assays. 相似文献
66.
Siang Hui Lim Patrycja Nowak-Sliwinska Fadzly Adzhar Kamarulzaman Hubert Van Den Bergh Georges Wagnières Hong Boon Lee 《Photochemistry and photobiology》2010,86(2):397-402
In this study, the photodynamic therapy (PDT) induced efficacy of a semi-synthesized analogue 151-hydroxypurpurin-7-lactone dimethyl ester or G2, in terms of chick chorioallantoic membrane blood vessel occlusion was evaluated in reference to verteporfin. Early formulation studies showed that G2 prepared in a system of cremophor EL 2.5% and ethanol 2.5% in saline was biocompatible up to 20 μL volume of injection. Following injection, G2 accumulation peaked within the first minute and its extravasation from intra- to extra-vascular occurred somewhat slower as compared with verteporfin. In the PDT study, closure of capillaries and small neovessels was observed with 4 μg per embryo of G2 and a light dose of 20 J cm−2 at a fluence rate of 40 mW cm−2 filtered at 400–440 nm—a result that may be considered optimum for the treatment of age-related macular degeneration (AMD). Also, partial occlusion of the large vessels was observed using the same dose of G2 and light—an effect which is desirable for cancer treatment. From this study, we conclude that G2 has the potential to be developed as a therapeutic agent for photodynamic treatment for AMD and cancer. 相似文献
67.
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
68.
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
69.
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
70.
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