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41.
Yulia?A.?Piskun Irina?V.?Vasilenko Ludmila?V.?Gaponik Sergei?V.?KostjukEmail author 《Polymer Bulletin》2012,68(6):1501-1513
The activated anionic ring-opening polymerization of ε-caprolactam initiated by 0.35 mol% of combined initiator, i.e., equimolar
mixture of magnesium di(ε-caprolactamate) (CL2Mg) with magnesium halides (MgCl2, MgBr2, and MgI2) as well as of ε-caprolactam magnesium bromide (CLMgBr) in the presence of 0.35 mol% of N-acetyl-ε-caprolactam as an activator has been investigated in the temperature range 140–200 °C. It was found that the reaction
rate increased while the apparent activation energy decreased in the following series: CL2Mg/MgCl2 < CL2Mg/MgBr2 ~ CLMgBr < CL2Mg/MgI2. In addition, the poly(ε-caprolactam)s prepared with CL2Mg/MgX2 (MgX2 = MgCl2, MgBr2, and MgI2) are characterized by slightly higher thermal stability than polymers obtained with CLMgBr as initiator. These observations
were explained in terms of the coordination of Lewis acids (MgX2, where X = Cl, Br, and I) with imide carbonyl of N-acyllactam end groups leading to the increase of their reactivity and stability. 相似文献
42.
Sung-Chul Seo Sergey A. Grinshpun Yulia Iossifova Detlef Schmechel Carol Y. Rao Tiina Reponen 《Aerosol science and technology》2013,47(8):794-803
A field-compatible collection system was developed and tested for the collection and analysis of fungal fragments. The new collection system consists of two types of Sharp-Cut cyclone samplers (PM 2.5 and PM 1.0 ) and an after-filter. Fungal particles are collected into three size fractions: (1) spores ( > 2.5 μ m); (2) a fragment-spore mixture (1.0–2.5 μ m); and (3) submicrometer-sized fragments ( < 1.0 μ m). The system was laboratory-tested using polystyrene latex (PSL) particles and particulate matter aerosolized from sporulating Aspergillus versicolor and Stachybotrys chartarum cultures. In addition to the particle count measured with direct-reading instruments, the (1 → 3)- β -D-glucan content in each size fraction was determined with the Limulus Amebocyte Lysate (LAL) assay. Experiments conducted with PSL particles showed that the 50% cut-off values of the two cyclone samplers under the test conditions were 2.25 μ m and 1.05 μ m, respectively. No particle bounce onto the after-filter was observed when the total particle number entering the collection system was kept below 1.6 × 10 8 . The (1 → 3)- β -D-glucan assay of samples aerosolized from both fungal species suggested that surface area is an important factor for determining the (1 → 3)- β -D-glucan content in the entire size-range of particles. In conclusion, the new methodology is a promising tool for separating and analyzing fungal fragment samples. 相似文献
43.
Yulia O. Kabova V. V. Kuznetsov O. A. Kabov 《Microgravity science and technology》2009,21(Z1):145-152
The present study is focused on the investigation of gravity effect on thermocapillary deformations in a film flowing under
action of co-current gas flow, which creates the tangential force on the gas–liquid interface. The influence of local heating
intensity on the heater at a substrate is also investigated. Effects of surface tension, temperature dependent viscosity and
thermocapillarity are taken into account. Investigations have shown that gravity has a significant effect on the film deformations
and pattern. Decreasing of gravity level leads to a flow destabilization. 3D liquid film pattern noticeably changes in spanwise
direction. Increasing of heat flux leads to increasing of liquid film deformations. Dependence of film thinning on heat flux
is strongly nonlinear. The most dangerous deformations (regions of minimum film thickness with possible disruption of liquid)
take place behind the downstream edge of the heater at any gravity conditions. 相似文献
44.
Elmira Khusnutdinova Anastasiya Petrova Zulfia Zileeva Ulyana Kuzmina Liana Zainullina Yulia Vakhitova Denis Babkov Oxana Kazakova 《International journal of molecular sciences》2021,22(18)
A series of A-ring modified oleanolic and ursolic acid derivatives including C28 amides (3-oxo-C2-nicotinoylidene/furfurylidene, 3β-hydroxy-C2-nicotinoylidene, 3β-nicotinoyloxy-, 2-cyano-3,4-seco-4(23)-ene, indolo-, lactame and azepane) were synthesized and screened for their cytotoxic activity against the NCI-60 cancer cell line panel. The results of the first assay of thirty-two tested compounds showed that eleven derivatives exhibited cytotoxicity against cancer cells, and six of them were selected for complete dose–response studies. A systematic study of local SARs has been carried out by comparative analysis of potency distributions and similarity relationships among the synthesized compounds using network-like similarity graphs. Among the oleanane type triterpenoids, C2-[4-pyridinylidene]-oleanonic C28-morpholinyl amide exhibited sub-micromolar potencies against 15 different tumor cell lines and revealed particular selectivity for non-small cell lung cancer (HOP-92) with a GI50 value of 0.0347 μM. On the other hand, superior results were observed for C2-[3-pyridinylidene]-ursonic N-methyl-piperazinyl amide 29, which exhibited a broad-spectrum inhibition activity with GI50 < 1 μM against 33 tumor cell lines and <2 μM against all 60 cell lines. This compound has been further evaluated for cell cycle analysis to decipher the mechanism of action. The data indicate that compound 29 could exhibit both cytostatic and cytotoxic activity, depending on the cell line evaluated. The cytostatic activity appears to be determined by induction of the cell cycle arrest at the S (MCF-7, SH-SY5Y cells) or G0/G1 phases (A549 cells), whereas cytotoxicity of the compound against normal cells is nonspecific and arises from apoptosis without significant alterations in cell cycle distribution (HEK293 cells). Our results suggest that the antiproliferative effect of compound 29 is mediated through ROS-triggered apoptosis that involves mitochondrial membrane potential depolarization and caspase activation. 相似文献
45.
本文在pH6.5磷酸盐缓冲溶液中研究了热变性前后牛乳铁蛋白(bovine lactoferrin,LF)和α-乳白蛋白(α-lactalbumin,ALA)之间的自组装行为。采用ζ-电位、浊度法、动态光散射、光学显微镜、荧光光谱和红外色谱等方法进行表征。结果表明,与天然LF和ALA自组装复合物相比,热变性LF和ALA自组装复合物的ζ-电位较低。天然LF与ALA可以自组装可形成纳米颗粒,粒径最大为(35.24±0.82) nm;经过热变性的LF与ALA自组装形成超分子结构,通过调整ALA浓度,可以得到亚微米和微米颗粒,颗粒粒径最大为(4.11±0.14) μm。天然LF与ALA的复合物均为球状聚集体,分布均一;而热变性LF与ALA的复合物则为网状聚集体,分布不均一。ALA的添加增强了LF中色氨酸残基的疏水性。LF中的C=O和C-N基团均参与了与ALA25 ℃的相互作用。本研究为构建新型双蛋白自组装体及理解双蛋白组装机制提供了理论依据。 相似文献
46.
Vadim E. Filatov Dmitrii A. Iuzabchuk Viktor A. Tafeenko Yuri K. Grishin Vitaly A. Roznyatovsky Dmitrii A. Lukianov Yulia A. Fedotova Maxim A. Sukonnikov Dmitry A. Skvortsov Nikolai V. Zyk Elena K. Beloglazkina 《International journal of molecular sciences》2022,23(12)
In this work, we present the first synthesis of dispirooxindole-β-lactams employing optimized methodology of one-pot Staudinger ketene-imine cycloaddition with N-aryl-2-oxo-pyrrolidine-3-carboxylic acids as the ketene source. Spiroconjugation of indoline-2-one with β-lactams ring is considered to be able to provide stabilization and wide scope of functionalization to resulting scaffolds. The dispipooxindoles obtained demonstrated medium cytotoxicity in the MTT test on A549, MCF7, HEK293, and VA13 cell lines, and one of the compounds demonstrated antibacterial activity against E. coli strain LPTD. 相似文献
47.
Irina V. Ogneva Yulia S. Zhdankina Oleg V. Kotov 《International journal of molecular sciences》2022,23(14)
Studies of reproductive function under long-term space flight conditions are of interest in planning the exploration of deep space. Motility, including the use of various inhibitors, cellular respiration, and the content of cytoskeletal proteins were studied, assessing the level of expression of the corresponding genes in spermatozoa of Drosophila melanogaster, which were in space flight conditions for 12 days. The experiment was carried out twice on board the Russian Segment of the International Space Station. Sperm motility speed after space flight, and subsequently 16 h after landing, is reduced relative to the control by 20% (p < 0.05). In comparison with the simulation experiment, we showed that this occurs as a result of the action of overloads and readaptation to the Earth’s gravity. At the same time, cellular respiration, the content of proteins of the respiratory chain, and the expression of their genes do not change. We used kinase inhibitor 6-(dimethylamino)purine (6-DMAP) and phosphatase inhibitors; 6-DMAP restored the reduced the speed of spermatozoa in the flight group to that of the control. These results can be useful in developing a strategy for protecting reproductive health during the development of other bodies in the solar system. 相似文献
48.
Maksim R. Sokolov Yulia Yu. Enakieva Alexey D. Yapryntsev Andrey A. Shiryaev Alexandra I. Zvyagina Maria A. Kalinina 《Advanced functional materials》2020,30(27)
A strategy for rational design of synergetic hybrid materials exploiting stabilization of intercalated layered matrices via coordination bonding is described. A new hybrid material is assembled through subsequent intercalation of the surface‐anchored metal–organic framework (SURMOF) components, zinc acetate and 5,10,15,20‐tetrakis(4‐carboxyphenyl)‐porphyrin‐zinc(II) (ZnTCPP), into the layered europium(III) hydroxychloride (LEuH). The formation of the SURMOF clusters intercalated in LEuH is confirmed by X‐ray diffraction, FTIR and Raman spectroscopy, and BET nitrogen absorption methods. The catalytic function of the SURMOF/LEuH hybrid and its components in the model reaction of hydrolysis of bis(4‐nitrophenyl) phosphate in the acidic solution is studied by UV–vis and MALDI‐TOF spectroscopy. Both the non‐intercalated matrix and the MOF powder are inactive and unstable in the substrate solution. Unlike its components, the SURMOF/LEuH hybrid exhibits synergetic catalytic activity increasing with the amount of the intercalated compounds because of the mutual stabilization of the components through coordination interactions. The results provide a basis for symbimetic (mimicking the symbiotic behavior in biological systems) hybrid materials, in which stabilization of functional units in the intercalated structure translates into a synergy of useful properties. 相似文献
49.
Mikhail Khrizanforov Sofia Strekalova Vera Khrizanforova Alexey Dobrynin Kirill Kholin Tatyana Gryaznova Valeriya Grinenko Aidar Gubaidullin M. K. Kadirov Yulia Budnikova 《Topics in Catalysis》2018,61(18-19):1949-1956
Joined electrolysis of arenes (benzene or coumarin derivatives) and diethyl-H-phosphonate (EtO)2P(O)H in the presence of [CoCl2(bpy)] catalyst (5%) in an ethanol-aqueous solution in reductive conditions allows obtaining the desired products in a single step by aromatic C–H bonds phosphonation with yields up to 70%. The only by-product is hydrogen; the reaction proceeds at room temperature and does not require specially added reducing agents and oxidants or other initiators. Radical mechanism has been confirmed for the catalytic reaction proceeding via bicobalt phosphonates with Co–P bond, the structure of which also has been identified. 相似文献
50.
Zinc oxide (ZnO) is an essential ingredient in industrial rubber production; it regulates the onset of vulcanization, accelerates the kinetics of vulcanization, and improves the mechanical properties of rubber. However, environmental pollution with ZnO is a concern because it is recognized to be significantly ecotoxic and might also have adverse effects on human health. One of the major sources of ZnO environmental pollution is rubber items, tires in particular. Nitrogen (N)‐doped graphene is a promising next‐generation catalyst. We show here that the replacement of 3 phr ZnO by just 0.1 phr N‐doped graphene in styrene–butadiene rubber reduced the vulcanization onset time by more than a factor of two while retaining the fast vulcanization kinetics and enhancing the tensile strength in comparison with rubber with just ZnO. A shorter vulcanization time implies energy savings, which, together with the nontoxicity of N‐graphene, should make the resulting rubbers substantially more environmentally friendly. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46116. 相似文献