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101.
This work studies the inverse problem of reconstructing an initial value function in the degenerate parabolic equation using the final measurement data. Problems of this type have important applications in the field of financial engineering. Being different from other inverse backward parabolic problems, the mathematical model in our article may be allowed to degenerate at some part of boundaries, which may lead to the corresponding boundary conditions missing. The conditional stability of the solution is obtained using the logarithmic convexity method. A finite difference scheme is constructed to solve the direct problem and the corresponding stability and convergence are proved. The Landweber iteration algorithm is applied to the inverse problem and some typical numerical experiments are also performed in the paper. The numerical results show that the proposed method is stable and the unknown initial value is recovered very well.© 2017 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 33: 1900–1923, 2017 相似文献
102.
Johnny W. Lee Katarzyna N. Lee Ming‐Yu Ngai 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(33):11289-11299
Trifluoromethoxy (OCF3) and difluoromethoxy (OCF2H) groups are fluorinated structural motifs that exhibit unique physicochemical characteristics. Incorporation of these substituents into organic molecules is a highly desirable approach used in medicinal chemistry and drug discovery processes to alter the properties of a parent compound. Recently, tri‐ and difluoromethyl ethers have received increasing attention and several innovative strategies to access these valuable functional groups have been developed. The focus of this Minireview is the use of visible‐light photoredox catalysis in the synthesis of tri‐ and difluoromethyl ethers. Recent photocatalytic strategies for the formation of O?CF3, C?OCF3, O?CF2H, and C?OCF2H bonds as well as other transformations leading to the construction of ORF groups are discussed herein. 相似文献
103.
Pudlarz Agnieszka Małgorzata Ranoszek-Soliwoda Katarzyna Czechowska Ewa Tomaszewska Emilia Celichowski Grzegorz Grobelny Jarosław Szemraj Janusz 《Applied biochemistry and biotechnology》2019,187(4):1551-1568
Applied Biochemistry and Biotechnology - Superoxide dismutase (SOD) is one of the best characterized enzyme maintaining the redox state in the cell. A bacterial expression system was used to... 相似文献
104.
Katarzyna Bednarczyk Tomasz Kukulski Ryszard Fryczkowski Ewa Schab-Balcerzak Marcin Libera 《Molecules (Basel, Switzerland)》2021,26(9)
The thermal, mechanical and electrical properties of polymeric composites combined using polythiophene (PT) dopped by FeCl3 and polyamide 6 (PA), in the aspect of conductive constructive elements for organic solar cells, depend on the molecular structure and morphology of materials as well as the method of preparing the species. This study was focused on disclosing the impact of the polythiophene content on properties of electrospun fibers. The elements for investigation were prepared using electrospinning applying two substrates. The study revealed the impact of the substrate on the conductive properties of composites. In this study composites exhibited good thermal stability, with T5 values in the range of 230–268 °C that increased with increasing PT content. The prepared composites exhibited comparable PA Tg values, which indicates their suitability for processing. Instrumental analysis of polymers and composites was carried out using Fourier Transform Infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM). 相似文献
105.
Koralewicz Maria Pruchnik Florian P. Szymaszek Anna Wajda-Hermanowicz Katarzyna Wrona-Grzegorek Katarzyna 《Transition Metal Chemistry》1998,23(4):523-525
The dimeric rhodium(II) complexes [Rh2(leu)4(H2O)2]- (ClO4)4 and [Rh2(pro)4(H2O)2](ClO4)4 have been prepared and characterized by elemental analyses, i.r., u.v.–vis. and 1H-n.m.r. spectroscopy. The amino acid molecules are coordinated as bridging ligands via their carboxylato groups. Cyclic voltammetry in DMF has shown that the complexes undergo a quasi-reversible reduction to yield dimers containing a Rh
2
3+
core. Oxidation processes within the 0–1.5V range were not observed. 相似文献
106.
Kamil J. Kuder Magdalena Kotaska Katarzyna Szczepaska Kamil Mika David Reiner-Link Holger Stark Katarzyna Kie-Kononowicz 《Molecules (Basel, Switzerland)》2021,26(8)
In an attempt to find new dual acting histamine H3 receptor (H3R) ligands, we designed a series of compounds, structurally based on previously described in our group, a highly active and selective human histamine H3 receptor (hH3R) ligand KSK63. As a result, 15 obtained compounds show moderate hH3R affinity, the best being the compound 17 (hH3R Ki = 518 nM). Docking to the histamine H3R homology model revealed two possible binding modes, with key interactions retained in both cases. In an attempt to find possible dual acting ligands, selected compounds were tested for antioxidant properties. Compound 16 (hH3R Ki = 592 nM) showed the strongest antioxidant properties at the concentration of 10−4 mol/L. It significantly reduced the amount of free radicals presenting 50–60% of ascorbic acid activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, as well as showed antioxidative properties in the ferric reducing antioxidant power (FRAP) assay. Despite the yet unknown antioxidation mechanism and moderate hH3R affinity, 16 (QD13) constitutes a starting point for the search of potential dual acting H3R ligands-promising tools for the treatment of neurological disorders associated with increased neuronal oxidative stress. 相似文献
107.
Here, we report on studies on the influence of different crosslinking methods (ionic and chemical) on the physicochemical (swelling ability and degradation in simulated body fluids), structural (FT-IR spectra analysis) and morphological (SEM analysis) properties of SA/PVA hydrogels containing active substances of natural origin. First, an aqueous extract of Echinacea purpurea was prepared using a Soxhlet apparatus. Next, a series of modified SA/PVA-based hydrogels were obtained through the chemical crosslinking method using poly(ethylene glycol) diacrylate (PEGDA, Mn = 700 g/mol) as a crosslinking agent and, additionally, the ionic reaction in the presence of a 5% w/v calcium chloride solution. The compositions of SA/PVA/E. purpurea-based hydrogels contained a polymer of natural origin—sodium alginate (SA, 1.5% solution)—and a synthetic polymer—poly(vinyl alcohol) (PVA, Mn = 72,000 g/mol, 10% solution)—in the ratio 2:1, and different amounts of the aqueous extract of E. purpurea—5, 10, 15 or 20% (v/v). Additionally, the release behavior of echinacoside from the polymeric matrix was evaluated in phosphate-buffered saline (PBS) at 37 °C. The results indicate that the type of the crosslinking method has a direct impact on the release profile. Consequently, it is possible to design a system that delivers an active substance in a way that depends on the application. 相似文献
108.
Lipophilicity is a very important property of chemical compound taking into consideration in drugs design. Relationships between biological activity, among others lipophilicity, and chemical structure (QSAR) of the compound are very often used by researches. Especially important is the kind of substituents connected to the basic structural fragment and how it changes the lipophilicity of the compound. The aim of this study was to determine the parameters of lipophilicity of quinobenzothiazine derivatives using reversed phase - thin-layer chromatography (RP-TLC), which would enable one to determine the structure–activity relationship. The objective of our work is a series of 15 newly synthetized quinobenzothiazines. They were analyzed by thin-layer chromatography (TLC) with the use of two different mobile phases consisting of methanol or acetone as organic modifiers. For all compounds investigated, the values of lipophilicity obtained from computational method were also determined. Cluster analysis was carried out too for all data of lipophilicity obtained. Low correlation was found between values of experimental lipophilicity and lipophilicity from computational methods for newly synthetized compounds. 相似文献
109.
Antimicrobial properties of biosynthesized silver nanoparticles studied by flow cytometry and related techniques 下载免费PDF全文
Viorica Railean‐Plugaru Pawel Pomastowski Katarzyna Rafinska Magdalena Wypij Wojciech Kupczyk Hanna Dahm Marek Jackowski Boguslaw Buszewski 《Electrophoresis》2016,37(5-6):752-761
This work reports the effect of silver bionanoparticles (Bio(AgNPs) synthesized by Actinobacteria CGG 11n on selected Gram (+) and Gram (–) bacteria. Flow cytometry, classical antibiogram method and fluorescent microscopy approach was used for evaluation of antimicrobial activity of Bio(AgNPs) and their combination with antibiotics. Furthermore, the performed research specified the capacity of flow cytometry method as an alternative to the standard ones and as a complementary method to electromigration techniques. The study showed antibacterial activity of both BioAgNPs and the combination of antibiotics/BioAgNPs against all the tested bacteria strains in comparison with a diffusion, dilution and bioautographic methods. The synergistic effect of antibiotics/BioAgNPs combination (e.g. kanamycin, ampicillin, neomycin and streptomycin) was found to be more notable against Pseudomonas aeruginosa representing a prototype of multi‐drug resistant “superbugs” for which effective therapeutic options are very limited. 相似文献
110.
In the present work we investigate various optical properties (such as light absorption and reflectance) of anodic TiO2 nanotube layers directly transferred as self‐standing membranes onto quartz substrates. This allows investigation in a transmission geometry which provides significantly more reliable data than measurements on the metallic Ti substrate. Light transmission and reflectance measurements were carried out for layers of thickness varying from 1.8 to 50 μm, and the layers were investigated in their amorphous and crystalline forms. A series of wavelength‐dependent light attenuation coefficients are extrapolated and found to match the photocurrent versus irradiation wavelength behavior. A feature specific to anodic nanotubes is that their intrinsic carbon contamination content causes a proportional sub‐bandgap response. Overall, the extracted data provide a valuable basis and understanding for the design of photo‐electrochemical devices based on TiO2 nanotubes. 相似文献