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71.
Jadwiga Szydłowska Paulina Krzyczkowska Piotr Gniewek Damian Pociecha Adam Krówczyński 《Liquid crystals》2013,40(11):1558-1570
Series of new Ni(II) metalomesogens of triangular molecular shape and forming Colh liquid crystalline (LC) phase were synthesised and described. Using in the molecular core the barbituric moieties that contain carbonyl or thiocarbonyl groups causes strong polarisation of the molecules and creates a permanent dipole moment μ, which was confirmed by quantum mechanical calculations. The relationship between molecular dipole moment and self-organisation of molecules into the columnar phase was considered. The position of alkyl and alkoxy chains substituted at phenyl ring that affects LC phase formation seems to be connected with planar conformation of the attached chains. These can broaden the mesogenic core and stabilise the Colh mesophase. 相似文献
72.
Prediction of liquid-liquid flow in an SMX static mixer using large eddy simulations 总被引:1,自引:0,他引:1
The main purpose of the paper is to apply the large eddy simulations (LES) technique and to verify its use as a predicting
tool for turbulent liquid-liquid flow in an SMX static mixer. LES modeling was carried out using the Smagorinsky-Lilly model
of the turbulent subgrid viscosity for the Reynolds number of 5000 and 10000. The continuous phase was water and the dispersed
phase was silicon oil. The investigation covers the effects of the density ratio between the phases. Three different cases
of liquid densities were considered. The dispersed phase concentration distribution in the mixer cross-sections was compared
with the corresponding time averaged results obtained formerly for the same configuration in a steady-state simulation using
the standard RANS approach with the k-ɛ model. The dependency of the standard deviation of the dispersed phase concentration on the distance from the mixer inlet
and the impact of the centrifugal force on the phase concentration distribution were investigated. The presented results for
the SMX static mixer confirm conclusions of previous studies by Jaworski et al. (2006) obtained for a Kenics static mixer
and show less a pronounced influence of the centrifugal force on the phase concentration distribution of the LES results in
comparison to the RANS case. 相似文献
73.
Gregory B. Kharas Amanda M. Claro Youya Gao Jay S. Bhanot Paulina Bosek Timothy R. Corwin 《高分子科学杂志,A辑:纯化学与应用化学》2016,53(10):595-599
Trisubstituted ethylenes, alkyl ring-substituted propyl 2-cyano-3-phenyl-2-propenoates, RPhCH?C(CN)CO2C3H7 (where R is H, 2-methyl, 3-methyl, 4-methyl, 4-ethyl, 4-propyl, 4-i-propyl, 4-butyl, 4-i-butyl, 4-t-butyl) were prepared and copolymerized with styrene. The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and propyl cyanoacetate, and characterized by CHN analysis, IR, 1H and 13C-NMR. All the ethylenes were copolymerized with styrene (M1) in solution with radical initiation (ABCN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, 1H and 13C-NMR. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 250–500°C range with residue (2–4% wt.), which then decomposed in the 500–800°C range. 相似文献
74.
Ewa Szefer Krzysztof Stafin Agnieszka Leszczyska Paulina Zajc Edyta Hebda Konstantinos N. Raftopoulos Krzysztof Pielichowski 《Journal of Polymer Science.Polymer Physics》2019,57(17):1133-1142
A top‐down approach is applied for the production of polyurethane (PU)–polyhedral oligomeric silsesquioxane (POSS) nanocomposites, namely melt blending. As opposed to the typical chemical incorporation during synthesis, a POSS moiety with two hydroxyl groups is melt blended into a commercial thermoplastic polyurethane with mass fraction up to 2 wt %. POSS disperses in the matrix in submicrometer‐sized crystals, as well as in length scale of few tens of nanometers, in the bulk. Phase separation of the produced composites was studied by both standard dynamic and isothermal annealing experiments. In an approach rare in the literature, the dynamics of phase separation is discussed based on isothermal differential scanning calorimetry curves recorded during annealing. The blended‐in nanoparticles affect the micromorphology in a complicated manner, dependent on the intrinsically complex phase separation mechanism of PU. At higher temperatures, POSS slows down the phase separation, whereas at lower ones, it enhances and accelerates it. POSS decreases the mechanical modulus of the final material, presumably as a result of changes in the microphase separation. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1133–1142 相似文献
75.
Structural Chemistry - Stacking interactions play an important role in stabilizing DNA and RNA secondary structure. To select a computational level to study the stacking interactions, both energy... 相似文献
76.
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78.
Patricia Nefertari Ramírez-Flores Paulina J. Barraza-Reyna Alain Aguirre-Vzquez María E. Camacho-Moll Carlos Enrique Guerrero-Beltrn Diana Resendez-Prez Vianey Gonzlez-Villasana Jesús Norberto Garza-Gonzlez Beatriz Silva-Ramírez Fabiola Castorena-Torres Mario Bermúdez de Len 《Molecules (Basel, Switzerland)》2021,26(19)
Hepatocellular carcinoma (HCC) is the most common form of liver cancer. The number of cases is increasing and the trend for the next few years is not encouraging. HCC is usually detected in the advanced stages of the disease, and pharmacological therapies are not entirely effective. For this reason, it is necessary to search for new therapeutic options. The objective of this work was to evaluate the effect of the drugs isotretinoin and thalidomide on c-MYC expression and cancer-related proteins in an HCC cellular model. The expression of c-MYC was measured using RT-qPCR and western blot assays. In addition, luciferase activity assays were performed for the c-MYC promoters P1 and P2 using recombinant plasmids. Dose-response-time analyses were performed for isotretinoin or thalidomide in cells transfected with the c-MYC promoters. Finally, a proteome profile analysis of cells exposed to these two drugs was performed and the results were validated by western blot. We demonstrated that in HepG2 cells, isotretinoin and thalidomide reduced c-MYC mRNA expression levels, but this decrease in expression was linked to the regulation of P1 and P1-P2 c-MYC promoter activity in isotretinoin only. Thalidomide did not exert any effect on c-MYC promoters. Also, isotretinoin and thalidomide were capable of inducing and repressing proteins associated with cancer. In conclusion, isotretinoin and thalidomide down-regulate c-MYC mRNA expression and this is partially due to P1 or P2 promoter activity, suggesting that these drugs could be promising options for modulating the expression of oncogenes and tumor suppressor genes in HCC. 相似文献
79.
Marta Kus Klaudia Gorniak Piotr Czaklosz Anna Olejnik Paulina Skupin-Mrugalska Izabela Ibragimow Hanna Piotrowska-Kempisty 《Molecules (Basel, Switzerland)》2022,27(7)
Perindopril arginine (PA) as an angiotensin-converting enzyme (ACE) inhibitor is widely used in cardiovascular diseases, especially in systemic hypertension and heart failure. Although the pharmacokinetics of PA are well documented, there is no available detailed data on its permeation in in vitro conditions. The present study aimed to assess the transport of PA across both biological membranes and artificial biomimetic ones. For the determination of PA transport, the Caco-2 cell line was selected as a reliable in vitro model of gastrointestinal biological barriers. Additionally, a novel 96-well plate with phospholipid membrane PermeaPad was used to evaluate the transport of PA by passive diffusion. We confirmed that PA is relatively poorly permeable across the Caco-2 monolayer. The permeability results obtained from the non-cell-based model demonstrated higher transport of PA as compared to that of Caco-2. Thus, PA transport across the biological membranes might be suggested to be regulated by the membrane transporters. 相似文献
80.
Magdalena Sowik-Borowiec Ewa Szpyrka Paulina Ksiek-Trela Magdalena Podbielska 《Molecules (Basel, Switzerland)》2022,27(7)
New analytical approaches to the simultaneous identification and quantification of 94 pesticides and 13 polycyclic aromatic hydrocarbons (PAHs) in five representative matrices (pepper, apple, lettuce, wheat, and soil) were developed. The analyses were based on gas chromatography coupled with triple quadrupole tandem mass spectrometry (GC-MS/MS). The procedure was optimized by changing the solvent used during the extraction, from acetonitrile to the acetone: n-hexane mixture at a volume ratio of 1:4 (v/v), as well as the use of a reduced amount of water during the extraction of compounds from cereals. An additional modification was the use of florisil instead of GCB in the sample cleanup step. A full method validation study was performed, at two concentration levels (LOQ and 1000 × LOQ), which showed satisfactory results for all analytes from the PAHs group, with recoveries ranging from 70.7–115.1%, and an average RSD of 3.9%. Linearity was tested in the range of 0.001–1.000 mg/kg and showed coefficients of determination (R2) ≥ 0.99 for all PAHs. Satisfactory recovery and precision parameters (LOQ and 100 × LOQ) were achieved for almost all analytes from the pesticide group in the range of 70.1–119.3% with the mean RSD equal to 5.9%. The observed linearity for all analytes in the concentration range of 0.005–1.44 mg/kg was R2 ≥ 0.99, with the exception of famoxadone, chizalofop-p-ethyl, prothioconazole, spirodiclofen, tefluthrin, and zoxamid. The extended uncertainties were estimated, using a top-down approach of 9.9% (average) and 15.3% (average) for PAHs and pesticides samples, respectively (the coverage factor k = 2, the 95% confidence level). Ultimately, the method was successfully applied to determine pesticide residues in commercial samples of fruit, vegetables and grain, and soil samples for PAHs, which were collected from selected places in the Podkarpacie region. A total of 38 real samples were tested, in which 10 pesticides and 13 PAHs were determined. Proposed changes allow us to shorten the sample preparation time (by 20%) and to reduce the consumption of organic solvents (by 17%). The use of florisil for sample cleanup, instead of GCB, improves the recovery of compounds with flat particles. 相似文献