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1.
Central European Journal of Operations Research - Many approaches have been designed to solve a stock portfolio selection problem. The aim of this paper is to provide a complex supporting tool for... 相似文献
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Tomáš Hložek Martin Štícha Miroslava Bursová Ivan Jelínek Petr Tůma Radomír Čabala 《Electrophoresis》2020,41(18-19):1564-1567
Riociguat is novel antihypertensive drug for treatment of pulmonary hypertension. As such, it is still being tested in many clinical and pharmacokinetic trials. Existing methods that determine serum riociguat and desmethylriociguat (DMR) are based solely on liquid chromatography with mass spectrometry. Therefore, we present a novel capillary electrophoresis with mass spectrometry method (CE-MS) for their determination in human serum as alternative method for ongoing trials. Complete resolution of both analytes was achieved by means of pH optimization of ammonium formate background electrolytes that are fully compatible with ESI/MS detection. Simple liquid-liquid extraction was used as sample pretreatment. The calibration dependence of the method was linear (in the range of 10–1000 ng/mL), with adequate accuracy (90.1–114.9%) and precision (13.4%). LOD and LOQ were arbitrarily set at 10 ng/mL for both analytes. Clinical applicability was validated using serum samples from patients treated with riociguat in pharmacokinetic study and the results corresponded with reference HPLC-MS/MS values. Capillary electrophoresis proved to be sensitive and selective tool for the analysis of riociguat and DMR. 相似文献
4.
Petr P. Sharin Sofia P. Yakovleva Susanna N. Makharova Maria I. Vasilieva Vasilii I. Popov 《Composite Interfaces》2019,26(1):53-65
The structural-phase state of the contact zone and the factors that influence on the strength of diamond retention in the diamond carbide composites were determined. Composites were obtained by the new hybrid technology that eliminates the reheating of the metalized coating. The elaborated technology combines the thermal diffusion metallization of a diamond and the sintering by the scheme of self-dosed impregnation in a one-stage technological cycle. By the methods of electron microscopy, X-ray diffraction analysis, and Raman spectroscopy the structural and phase characteristics of the interphase boundary were investigated. The improvement of chemical and mechanical adhesion between the diamond and carbide matrix was obtained. It was shown that the specific productivity of the samples with a metalized diamond component is 39% higher than those without metallization. 相似文献
5.
Atiruj Theppawong Tim Van de Walle Dr. Charlotte Grootaert Prof. Dr. Kristof Van Hecke Nathalie Catry Prof. Dr. Tom Desmet Prof. Dr. John Van Camp Prof. Dr. Matthias D'hooghe 《ChemistryOpen》2019,8(2):236-247
Curcumin is known to display pronounced anticancer effects and a variety of other biological activities. However, the low bioavailability and fast metabolism of this molecule present an issue of concern with respect to its medicinal applications. To address this issue, structural modifications of the curcumin scaffold can be envisioned as a strategy to improve both the solubility and stability of this chemical entity, without compromising its biological activities. Previous work in our group targeted the synthesis of symmetrical azaheteroaromatic curcuminoids, which showed better solubility and cytotoxicity profiles compared to curcumin. In continuation of that work, we now focused on the synthesis of non-symmetrical nitrogen-containing curcuminoids bearing both a phenolic and an azaheteroaromatic moiety. In that way, we aimed to combine good solubility, antioxidant potential and cytotoxic properties into one molecule. Some derivatives were selected for further chemical modification of their rather labile β-diketone scaffold to the corresponding pyrazole moiety. In this way, thirteen new non-symmetrical aza-aromatic curcuminoids and four pyrazole-based analogues were successfully synthesized in a yield of 11–69 %. All newly synthesized analogues were evaluated for their antioxidant properties, reactive oxygen species (ROS) production, water solubility and anticancer activities. Several novel derivatives displayed good cytotoxicity profiles compared to curcumin, in combination with an improved water solubility and stability, and were thus identified as potential hit scaffolds for further optimization studies. 相似文献
6.
Thi Lieu Nguyen Van Hoang Cao Thi Hai Yen Pham Truong Giang Le 《Electroanalysis》2019,31(12):2538-2545
Platinum nanoflowers modified glassy carbon electrodes (PtNFs/GCE) was fabricated simply for lead determination in water samples. The modified electrodes were prepared by electrodeposition in hexachloroplatinic acid solution at constant potential. The influence of deposition time and potential on surface morphology, chemical composition, electrochemical properties of electrode were investigated. At ?0.2 V of potential and 150 s of deposition duration, platinum developed as nanoflower shape and scattered densely all over the glassy carbon surface, producing the largest electrochemically active surface areas. The highest differential pulse stripping voltammetry (DPSV) signal of lead was obtained by using the prepared electrode. Under optimized experimental condition of electrolyte, accumulation potential and time, the peak current was found to be linear proportion to lead concentration in range of 1 to 100 μg L?1 (slope=0.371) with a limit of detection of 0.398 μg L?1. The method has good repeatability and reproducibility with relative standard deviations of 1.47 % and 4.83 %, respectively. The modified PtNFs/GCE also demonstrated an excellent long‐term stability with only 9 % decrease in Pb peak current over 30 days. Moreover, the performance of the modified PtNFs/GCE in determination of Pb(II) in two industrial wastewaters was good agreement with data obtained by a graphite furnace atomic absorption spectrometry (GFAAS) method. 相似文献
7.
A milestone in probability theory is the law of the iterated logarithm (LIL), proved by Khinchin and independently by Kolmogorov in the 1920s, which asserts that for iid random variables with mean 0 and variance 1 In this paper we prove that LIL holds for various functionals of random graphs and hypergraphs models. We first prove LIL for the number of copies of a fixed subgraph H. Two harder results concern the number of global objects: perfect matchings and Hamiltonian cycles. The main new ingredient in these results is a large deviation bound, which may be of independent interest. For random k‐uniform hypergraphs, we obtain the Central Limit Theorem and LIL for the number of Hamilton cycles. 相似文献
8.
Petr Popov Sergei Grudinin Andrii Kurdiuk Pavel Buslaev Stephane Redon 《Journal of computational chemistry》2019,40(27):2391-2399
In this study, we propose a novel optimization algorithm, with application to the refinement of molecular complexes. Particularly, we consider optimization problem as the calculation of quasi-static trajectories of rigid bodies influenced by the inverse-inertia-weighted energy gradient and introduce the concept of advancement region that guarantees displacement of a molecule strictly within a relevant region of conformational space. The advancement region helps to avoid typical energy minimization pitfalls, thus, the algorithm is suitable to work with arbitrary energy functions and arbitrary types of molecular complexes without necessary tuning of its hyper-parameters. Our method, called controlled-advancement rigid-body optimization of nanosystems (Carbon), is particularly useful for the large-scale molecular refinement, as for example, the putative binding candidates obtained with protein–protein docking pipelines. Implementation of Carbon with user-friendly interface is available in the SAMSON platform for molecular modeling at https://www.samson-connect.net . © 2019 Wiley Periodicals, Inc. 相似文献
9.
A new kind of flow gating interface (FGI) has been designed for online connection of CE with flow‐through analytical techniques. The sample is injected into the separation capillary from a space from which the BGE was forced out by compressed air. A drop of sample solution with a volume of 75 nL is formed between the outlet of the delivery capillary supplying the solution from the flow‐through apparatus and the entrance to the CE capillary; the sample is hydrodynamically injected into the CE capillary from this drop. The sample is not mixed with the surrounding BGE solution during injection. The functioning of the proposed FGI is fully automated and the individual steps of the injection process are controlled by a computer. The injection sequence lasts several seconds and thus permits performance of rapid sequential analyses of the collected sample. FGI was tested for the separation of equimolar 50 μM mixture of the inorganic cations K+, Ba2+, Na+, Mg2+, and Li+ in 50 mM acetic acid/20 mM Tris (pH 4.5) as BGE. The obtained RSD values for the migration times varied in the range 0.7–1.0% and the values for the peak area were 0.7–1.4%; RSD were determined for ten repeated measurements. 相似文献
10.
Maribel Rodríguez‐Aguilar Sofía Ramírez‐García Cesar Ilizaliturri‐Hernndez Alejandro Gmez‐Gmez Evelyn Van‐Brussel Fernando Díaz‐Barriga Susanna Medellín‐Garibay Rogelio Flores‐Ramírez 《Biomedical chromatography : BMC》2019,33(12)
An analytical method to identify volatile organic compounds (VOCs) in the exhaled breath from patients with a diagnosis of chronic obstructive pulmonary disease (COPD) using a ultrafast gas chromatography system equipped with an electronic nose detector (FGC eNose) has been developed. A prospective study was performed in 23 COPD patients and 33 healthy volunteers; exhalation breathing tests were performed with Tedlar bags. Each sample was analyzed by FCG eNose and the identification of VOCs was based on the Kovats index. Raw data were reduced by principal component analysis (PCA) and canonical discriminant analysis [canonical analysis of principal coordinates (CAP)]. The FCG eNose technology was able to identify 17 VOCs that distinguish COPD patients from healthy volunteers. At all stages of PCA and CAP the discrimination between groups was obvious. Chemical prints were correctly classified up to 82.2%, and were matched with 78.9% of the VOCs detected in the exhaled breath samples. Receiver operating characteristic curve analysis indicated the sensitivity and specificity to be 96% and 91%, respectively. This pilot study demonstrates that FGC eNose is a useful tool to identify VOCs as biomarkers in exhaled breath from COPD patients. Further studies should be performed to enhance the clinical relevance of this quick and ease methodology for COPD diagnosis. 相似文献