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排序方式: 共有871条查询结果,搜索用时 6 毫秒
131.
Julia Modrzejewska Marcin Szala Aleksandra Grzelakowska Magorzata Zakos-Szyda Jacek Zielonka Radosaw Podsiady 《Molecules (Basel, Switzerland)》2021,26(19)
Derivatives of coumarin, containing oxidant-sensitive boronate group, were recently developed for fluorescent detection of inflammatory oxidants. Here, we report the synthesis and the characterization of 3-(2-benzothiazolyl)-7-coumarin boronic acid pinacol ester (BC-BE) as a fluorescent probe for the detection of peroxynitrite (ONOO–), with high stability and a fast response time. The BC-BE probe hydrolyzes in phosphate buffer to 3-(2-benzothiazolyl)-7-coumarin boronic acid (BC-BA) which is stable in the solution even after a prolonged incubation time (24 h). BC-BA is slowly oxidized by H2O2 to form the phenolic product, 3-benzothiazol-2-yl-7-hydroxy-chromen-2-one (BC-OH). On the other hand, the BC-BA probe reacts rapidly with ONOO−. The ability of the BC-BA probe to detect ONOO– was measured using both authentic ONOO– and the system co-generating steady-state fluxes of O2•– and •NO. BC-BA is oxidized by ONOO– to BC-OH. However, in this reaction 3-benzothiazol-2-yl-chromen-2-one (BC-H) is formed in the minor pathway, as a peroxynitrite-specific product. BC-OH is also formed in the reaction of BC-BA with HOCl, and subsequent reaction of BC-OH with HOCl leads to the formation of a chlorinated phenolic product, which could be used as a specific product for HOCl. We conclude that BC-BA shows potential as an improved fluorescent probe for the detection of peroxynitrite and hypochlorite in biological settings. Complementation of the fluorescence measurements by HPLC-based identification of oxidant-specific products will help to identify the oxidants detected. 相似文献
132.
Luca Sancineto Carmine Ostacolo David Ortega-Alarcon Ana Jimenez-Alesanco Laura Ceballos-Laita Sonia Vega Olga Abian Adrian Velazquez-Campoy Silvia Moretti Agnieszka Dabrowska Pawel Botwina Aleksandra Synowiec Anna Kula-Pacurar Krzysztof Pyrc Nunzio Iraci Claudio Santi 《Molecules (Basel, Switzerland)》2021,26(19)
The COVID-19 pandemic outbreak prompts an urgent need for efficient therapeutics, and repurposing of known drugs has been extensively used in an attempt to get to anti-SARS-CoV-2 agents in the shortest possible time. The glycoside rutin shows manifold pharmacological activities and, despite its use being limited by its poor solubility in water, it is the active principle of many pharmaceutical preparations. We herein report our in silico and experimental investigations of rutin as a SARS-CoV-2 Mpro inhibitor and of its water solubility improvement obtained by mixing it with l-arginine. Tests of the rutin/l-arginine mixture in a cellular model of SARS-CoV-2 infection highlighted that the mixture still suffers from unfavorable pharmacokinetic properties, but nonetheless, the results of this study suggest that rutin might be a good starting point for hit optimization. 相似文献
133.
Radosaw W. Piast Rafa M. Wieczorek Nicola Marzec Maciej Garstka Aleksandra Misicka 《Molecules (Basel, Switzerland)》2021,26(19)
Chondrocalcinosis is a metabolic disease caused by the presence of calcium pyrophosphate dihydrate crystals in the synovial fluid. The goal of our endeavor was to find out whether short peptides could be used as a dissolving factor for such crystals. In order to identify peptides able to dissolve crystals of calcium pyrophosphate, we screened through a random library of peptides using a phage display. The first screening was designed to select phages able to bind the acidic part of alendronic acid (pyrophosphate analog). The second was a catalytic assay in the presence of crystals. The best-performing peptides were subsequently chemically synthesized and rechecked for catalytic properties. One peptide, named R25, turned out to possess some hydrolytic activity toward crystals. Its catalysis is Mg2+-dependent and also works against soluble species of pyrophosphate. 相似文献
134.
We try to establish the commonalities and leadership in the cryptocurrency markets by examining the mutual information and lead-lag relationships between Bitcoin and other cryptocurrencies from January 2019 to June 2021. We examine the transfer entropy between volatility and liquidity of seven highly capitalized cryptocurrencies in order to determine the potential direction of information flow. We find that cryptocurrencies are strongly interrelated in returns and volatility but less in liquidity. We show that smaller and younger cryptocurrencies (such as Ripple’s XRP or Litecoin) have started to affect the returns of Bitcoin since the beginning of the pandemic. Regarding liquidity, the results of the dynamic time warping algorithm also suggest that the position of Monero has increased. Those outcomes suggest the gradual increase in the role of privacy-oriented cryptocurrencies. 相似文献
135.
Jelena Nikoli Zoran Peri Danijela Aleksi Stefan Tomi Aleksandra Jovanovi 《Entropy (Basel, Switzerland)》2021,23(12)
Driven by the need for the compression of weights in neural networks (NNs), which is especially beneficial for edge devices with a constrained resource, and by the need to utilize the simplest possible quantization model, in this paper, we study the performance of three-bit post-training uniform quantization. The goal is to put various choices of the key parameter of the quantizer in question (support region threshold) in one place and provide a detailed overview of this choice’s impact on the performance of post-training quantization for the MNIST dataset. Specifically, we analyze whether it is possible to preserve the accuracy of the two NN models (MLP and CNN) to a great extent with the very simple three-bit uniform quantizer, regardless of the choice of the key parameter. Moreover, our goal is to answer the question of whether it is of the utmost importance in post-training three-bit uniform quantization, as it is in quantization, to determine the optimal support region threshold value of the quantizer to achieve some predefined accuracy of the quantized neural network (QNN). The results show that the choice of the support region threshold value of the three-bit uniform quantizer does not have such a strong impact on the accuracy of the QNNs, which is not the case with two-bit uniform post-training quantization, when applied in MLP for the same classification task. Accordingly, one can anticipate that due to this special property, the post-training quantization model in question can be greatly exploited. 相似文献
136.
Wanda Mczka Anna Duda-Madej Aleksandra Grny Magorzata Grabarczyk Katarzyna Wiska 《Molecules (Basel, Switzerland)》2021,26(16)
One of the primary reasons for the search for new antimicrobial agents is the increasing and spreading resistance of microorganisms to previously used drugs. This is particularly important in the case of rapidly progressing infections that require the rapid administration of an appropriately selected antibiotic. However, along with the administration of antibiotics, complications in the disease-weakened body may arise in the form of systemic mycoses, viral infections, and protozoan infections. Therefore, there is an increasing interest among researchers focusing on the use of naturally occurring terpenic compounds in stand-alone or combined therapies with antibiotics. In this publication, the aim of our work is to present the results of a literature review on the antimicrobial activity of eucalyptol. 相似文献
137.
The present paper contains theoretical analysis and a thorough discussion of the applicability of Fick’s approach to modelling
CO2 and CH4 diffusion in heterogeneous coal, especially with regard to the estimation of a single diffusion coefficient from the dependence
defined by a number series. The computations were performed for high rank coal depending on the grain size of coal samples
and within a narrow range of temperature − 293 and 303 K.
The results of the model’s application to the experimental data show that the method of estimation of the diffusion coefficient
is very important. Our results also show that the diffusion coefficient changes are closely related with the one-parameter
analysis of coal grain size distribution. 相似文献
138.
Aleksandra Dubiella-Jackowska Żaneta Polkowska Lech Dariusz Piotr Pasławski Wojciech Staszek Jacek Namieśnik 《Central European Journal of Chemistry》2009,7(1):35-41
A solid phase extraction technique for the determination of platinum(IV) at trace levels by inductively coupled plasma mass
spectromA solid phase extraction technique for the determination of platinum(IV) at trace levels by inductively coupled plasma
mass spectrometry (ICP-MS) was developed. The method was based on retention of platinum in a sample on silica gel modified
with aminepropyl groups. The retention of platinum(IV) from the sample solution and the recovery of platinum with 1.0 mol
L−1 thiourea solution were quantitative. The relative standard deviation (RSD) was calculated as 5% (n = 7) at the 10 ng L−1 level. The enrichment factor was found to be (50-fold) for 250 mL of water sample. Under optimum conditions, the method detection
limit (MDL) was found to be 1 ng L−1 for platinum in water matrices. Recoveries of Pt from spike addition to atmospheric water samples were quantitative (80–95%).
The present method was used for the determination of platinum in precipitation, throughfall and runoff water samples.
相似文献
139.
Let Λ be an algebraic set and let (n is even) be a polynomial mapping such that for each there is r(λ) > 0 such that the mapping g
λ = g(· , λ) restricted to the sphere S
n
(r) is an immersion for every 0 < r < r (λ), so that the intersection number I(g
λ|S
n
(r)) is defined. Then is an algebraically constructible function.
I. Karolkiewicz and A. Nowel supported by the grant BW/5100-5-0286-7. 相似文献
140.
Izabela Bobowska Aleksandra Wypych-Puszkarz Agnieszka Opasinska Waldemar Maniukiewicz Piotr Wojciechowski 《Phase Transitions》2017,90(1):44-53
ABSTRACTEffects of the elevated temperature on the structure evolution of the ZnO nanorod array (ZNA) and their hybrid nanocomposite with layered (tetramethyl)ammonium titanate (LTMAT) prepared by the liquid phase deposition were investigated. The vertically oriented ZnO nanorods were deposited on a quartz plate by a chemical bath deposition method and then they were penetrated by the LTMAT using the dip-coating method from the water solution. As a result of such an experimental procedure, an assembly composed of the ZNA with LTMAT was obtained and called hybrid nanocomposite. Since the LTMAT converts to TiO2 upon subsequent sintering at 350 °C, it can be regarded as TiO2 precursor for the thermal treatment experiments. The experiments with ZNA and their hybrid nanocomposite at the elevated temperature revealed coalescence of the deposited ZnO nanorods and crystallization of zinc titanate with Zn2TiO4 stoichiometry. 相似文献