排序方式: 共有19条查询结果,搜索用时 15 毫秒
11.
Mechanics of Composite Materials - A mathematical model describing the thermoelastic characteristics of a composite reinforced by anisotropic ellipsoidal inclusions is proposed. The model is... 相似文献
12.
Vinyl phenylboronic acid controlling co‐monomer for nitroxide mediated synthesis of thermoresponsive poly(2‐N morpholinoethyl methacrylate)
下载免费PDF全文
![点击此处可从《Journal of polymer science. Part A, Polymer chemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Xeniya Savelyeva David Chondon Milan Marić 《Journal of polymer science. Part A, Polymer chemistry》2016,54(11):1560-1572
Low concentrations of 4‐vinylphenylboronic acid (VPBA) were copolymerized with 2‐N‐morpholinoethyl methacrylate (MEMA) by nitroxide mediated polymerization using BlocBuilder? unimolecular initiator at 80 to 90 °C. The MEMA/VPBA copolymerizations were performed at initial feed compositions (fVPBA,0) of 0.05 to 0.10 VPBA, with fVPBA,0 = 0.10 using dimethylacetamide (DMAc) solvent being most effective, as seen by a linear increase in number average molecular weight, Mn, versus conversion and low dispersity, ? < 1.40. The copolymers were further chain‐extended with a second batch of VPBA, resulting in a block copolymer with monomodal molecular weight distribution and ? = 1.66. For MEMA/VPBA copolymers, increases in VPBA composition and polymer solution concentration resulted in decreases in the cloud point temperature (CPT, typically varied between 27.4–37.8 °C) and CPT increased from 31.2 to 33.8 °C to about 88 °C with decreases in pH from 7 to 4. Rheological tests with small angle light scattering (SALS) confirmed CPTs measured by UV‐Vis and DLS. These copolymers were targeted as models to combine possible glucose‐sensing boronic acid functionality the thermoresponsiveness provided by MEMA groups. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1560–1572 相似文献
13.
A. A. Tulupov O. B. Bogomyakova L. A. Savelyeva Yu. A. Prygova 《Applied magnetic resonance》2011,41(2-4):543-550
Here we present on the ability of phase-contrast magnetic resonance imaging (MRI) to accurately measure dynamic properties of cerebrospinal fluid (CSF) flow on basal level of brain. CSF characteristics were compared in a group of 55 healthy volunteers. MRI study was performed using 1.5 T system with the following parameters: repetition time TR/echo time TE = 14/8.3 ms; flip angle FA = 15°; slice thickness = 4 mm. Velocity values of CSF flow on basal level of brain obtained in the study were statistically analyzed by capturing mean values and building confidence intervals (p = 0.05). Student’s paired t-test was performed to determine significance of the differences between mean values and between caudal and cranial CSF flows. Normal values of mean velocity, mean flux and peak velocity were defined by Q-flow technique. The highest values of CSF flow characteristics were observed in the Sylvian aqueduct and pontomedullaris cistern. Mean velocity and mean flux of caudal CSF flow had significantly higher values compared to the cranial CSF flow in all investigated structures. 相似文献
14.
Xeniya Savelyeva Milan Marić 《Journal of polymer science. Part A, Polymer chemistry》2014,52(14):2011-2024
Nitroxide‐mediated polymerization (NMP) of N‐(2‐methacryloyloxyethyl) pyrrolidone (MAEPYR) with 2‐([tert‐butyl[1‐(diethoxyphosphoryl)‐2,2‐dimethylpropyl]amino]oxy)‐2‐methylpropanoic acid (BlocBuilder) initiator and N‐tert‐butyl‐N‐[1‐diethylphosphono‐(2,2‐dimethylpropyl)] (SG1) nitroxide permitted controlled synthesis of poly(N‐(2‐methacryloyloxyethyl)‐pyrrolidone‐stat‐9‐(4‐vinylbenzyl)‐9H‐carbazole) (poly(MAEPYR‐stat‐VBK)) statistical copolymers. With at least 5 mol % VBK, the dispersity ? of the copolymers was below 1.4 at conversions less than 50%. At conversions higher than 50%, and at lower VBK feed content, there was a significant amount of termination reactions, which broadened the molecular weight distribution of the final polymers (? = 1.4–2.3). The MAEPYR‐rich statistical copolymers were subsequently tested for thermoresponsive behavior in aqueous media. The cloud point temperatures (CPTs) in aqueous solution were tuned by changing the VBK composition, solution concentration, and heating rate, and the transitions were thermally reversible with partial loss of reversibility at higher heating rates. The CPT decreased from 59.0 to 49.7 °C with addition of only 1 mol % of VBK in the copolymer, and at more than 6 mol % VBK, the copolymer was water insoluble. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2011–2024 相似文献
15.
Valery V. Gorbatchuk Marat A. Ziganshin Ludmila S. Savelyeva Nikolay A. Mironov Wolf D. Habicher 《Macromolecular Symposia》2004,210(1):263-270
A cooperative hydration effect being favorable for the binding of organic vapors by cross-linked poly(N-6-aminohexylacrylamide) and beta-cyclodextrin was observed in ternary systems in the absence of liquid phase. For these systems the vapor sorption isotherms were determined by the static method of headspace gas chromatographic analysis at 298 K. The obtained isotherms show an increase of binding affinity for vapor of hydrophobic sorbates above a threshold value of receptor hydration. Further hydration gives a saturation of this affinity for the studied hydrophilic polyacrylamide derivative, while the affinity of beta-cyclodextrin for the hydrophilic sorbate ethanol even decreases. A similar behavior of this polymer and beta-cyclodextrin at the change of their hydration helps to explain the observed cooperative hydration effect in terms of clathrate formation. 相似文献
16.
17.
Stimuli‐responsive 4‐acryloylmorpholine/4‐acryloylpiperidine copolymers via nitroxide mediated polymerization
下载免费PDF全文
![点击此处可从《Journal of polymer science. Part A, Polymer chemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Xeniya Savelyeva Adrien Métafiot Lucia Li Ian Bennett Milan Marić 《Journal of polymer science. Part A, Polymer chemistry》2017,55(13):2160-2170
4‐acryloylmorpholine/4‐acryloylpiperidine statistical copolymers were synthesized by nitroxide mediated polymerization (NMP) with BlocBuilder unimolecular initiator in dimethylformamide solution at 120 °C. The copolymers had narrow molecular weight distributions (dispersity ? = 1.25–1.35, number average molecular weights M n = 8.5–13.7 kg mol?1). The copolymer microstructure was essentially statistical (reactivity ratios r 4AP = 0.81 ± 0.73, r 4AM = 0.73 ± 0.68 based on non‐linear fitting of the Mayo‐Lewis equation). Cloud point temperatures (CPT) in aqueous media were tuned from 11 °C to 92 °C, merely by adjusting the initial monomer composition. Using NMP permitted sharper control of the CPT transitions, compared to the similar copolymer made using conventional radical polymerization. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 2160–2170 相似文献
18.
Z. A. Savelyeva S. A. Popov L. A. Glinskaya R. F. Klevtsova E. G. Boguslavsky A. V. Tkachev S. V. Larionov 《Journal of Structural Chemistry》2005,46(1):122-130
New coordination compounds of copper(I) have been synthesized: [Cu2L 2 1 Cl2] (I) and [Cu2(HL2)2Br2] (II), where L1 is methyl 3-[(3,5-dimethyl-pyrazole-1-carbothioyl)-amino]-propionate, and HL2 is ethyl [(3,5-dimethyl-pyrazole-1-carbothioyl)-amino]-acetate. X-ray diffraction analysis showed that the crystal structures of these compounds are built from binuclear molecules. The L1 and HL2 molecules perform the bridging tridentate cyclic function, which results in a closure of two five-membered chelate cycles CuN2SC and metallocycle Cu2S2. Each Cu atom coordinates the N atom of the pyrazole ring, the halogen atom (Cl in I and Br in II), and two S atoms, thus forming a distorted tetrahedron. The Cu2S2 metallocycles, the CuN2SC chelate cycles, and the pyrazole rings are flat. Both CuN2SC chelate cycles are almost perpendicular to the Cu2S2 metallocycle and form a chair conformation. Redox reactions in CuCl2·2H2O-L1-ethanol and CuBr2-HL2-ethanol systems were examined by EPR spectroscopy. 相似文献
19.
A. A. Tulupov L. A. Savelyeva O. B. Bogomyakova Yu. A. Prygova 《Applied magnetic resonance》2011,41(2-4):551-560
The estimation of blood flow velocity in cerebral veins and sinuses by ultrasound is limited because of technical factors that make visualization of the vessels near the acoustic windows of the skull difficult. The common quality of cerebral venous thrombosis (CVT) is associated with the poorly characterized imaging finding of parenchymal abnormalities. Phase-contrast magnetic resonance angiography (PC MRA) has offered some insight into these manifestations. The purpose of our research is to determine the ability of PC MRA to aid in the assessment of large cerebral sinuses and internal jugular veins, as well as to provide reference data for flow velocity in patients with CVT. We describe here the main clinical features and the MRI characteristics of collateral drainage and flow velocity data in patients with CVT. 相似文献