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排序方式: 共有94条查询结果,搜索用时 234 毫秒
1.
研究了一系列聚芳醚砜的H2、CO2、O2、N2和CH4气体透过性能,讨论了其气体透过的温度依赖性。与双酚A聚砜(PSF)相比,几种新型聚芳醚砜的气体透过系数和气体选择系数同时有所提高。通过聚合物的分子链段活动性和自由体积数据系列变化,讨论了气体透过速率与分子结构的关系。  相似文献   
2.
Summary: The blends of poly(hydroxyether sulfone) (PHES) with poly(N‐vinylpyrrolidone) (PVPy) were investigated by means of differential scanning calorimetry (DSC) and FTIR spectroscopy. The miscibility of the blend system was established on the basis of the thermal analysis results. DSC showed that the PHES/PVPy blends prepared by casting from N,N‐dimethylformamide (DMF) possessed single, composition‐dependent glass transition temperatures, indicating that the blends are miscible in the entire composition. The experimental glass transition temperatures have higher values than those calculated on the basis of additive behavior; the variation of the glass transition temperatures of the blends was accounted for by the Kwei equation. FTIR studies indicate that competitive hydrogen bonding interactions exist upon addition of PVPy to the system, which were involved in the self‐ and cross‐association, i.e., ? OH···O?S, ? OH···OH of PHES and ? OH···O?C< of PVPy. The FTIR spectra in the range of the sulfonyl stretching vibrations showed that the hydroxyl‐associated sulfonyl groups are partially “set free” upon addition of PVPy to the system. The IR spectroscopic investigation of both the model compounds and the PHES/PVPy blends suggests that the strength of the hydrogen bonding interactions in the blend system increases in the following order: ? OH···O?S, ? OH···OH and ? OH···O?C<.

Plot of glass transition temperature for PHES/PVPy blends as a function of weight fraction of PVPy. The prediction of the Kwei equation yields the values of k = 1 and q = 122.  相似文献   

3.
聚醚砜表面光固定脲酶的研究   总被引:3,自引:0,他引:3  
我们利用含芳香叠氮基的光活性酯将脲酶光固定在聚醚砚(Polyether sulfone,PES)膜的表面。同时研究了紫外光辐照时间对固定化脲酶密度、固定化脲酶活性的影响,温度、PH值对自由脲酶、固定化脲酶相对活性的影响;并考察了固定化脲酶的相对活性随光活性酶浓度的变化、固定化脲酶的重复使用次数及储存稳定性等性质。结果表明,PES膜表面固定化脲酶的浓度为0.33mg/cm^2;当紫外光辐照时间为5分钟时,固定化脲酶的相对活性最高;固定化脲酶的最适Ph值和最适温度分别为7℃和50 ℃;在50℃时,连续使用12次后,固定化脲酶仍具有50%的催化活性;在4℃保存储存一个多月仍可保持80%的催化活性。  相似文献   
4.
Summary: The mechanisms of the Michael addition polymerization of N‐aminoethyl piperazine (AEPZ) with divinyl sulfone (DVS) were clarified based on the reactivity sequence of three different amines in AEPZ: 2° amine in piperazine ring > 1° amine ≫ 2° amine formed in situ. When the feed molar ratio of DVS to AEPZ was 1:1, the polymerization of AB intermediate formed proceeded, and the linear poly(sulfone amine) containing secondary and tertiary amines in the backbones were produced. The linear structure of the product was confirmed by NMR spectra, and the molecular weights, molecular weight distribution, and properties of poly(sulfone amine)s were characterized by GPC, DSC, and TGA.

Polymerization of linear poly(DVS‐AEPZ).  相似文献   

5.
Nanoparticles (NPs) are a promising tool for in vivo multimodality imaging and theranostic applications. Hyaluronic acid (HA)-based NPs have numerous active groups that make them ideal as tumor-targeted carriers. The B-lymphoma neoplastic cells express on their surfaces a clone-specific immunoglobulin receptor (Ig-BCR). The peptide A20-36 (pA20-36) selectively binds to the Ig-BCR of A20 lymphoma cells. In this work, we demonstrated the ability of core-shell chitosan-HA-NPs decorated with pA20-36 to specifically target A20 cells and reduce the tumor burden in a murine xenograft model. We monitored tumor growth using high-frequency ultrasonography and demonstrated targeting specificity and kinetics of the NPs via in vivo fluorescent reflectance imaging. This result was also confirmed by ex vivo magnetic resonance imaging and confocal microscopy. In conclusion, we demonstrated the ability of NPs loaded with fluorescent and paramagnetic tracers to act as multimodal imaging contrast agents and hence as a non-toxic, highly specific theranostic system.  相似文献   
6.
Poisoning with organophosphorus compounds (OPCs) poses a serious threat worldwide. OPC‐induced mortality can be significantly reduced by prophylactic administration of reversible acetylcholinesterase (AChE) inhibitors. The only American Food and Drug Administration (FDA)‐approved substance for such pre‐treatment (to soman exposure) is presently pyridostigmine, although its efficacy is controversial. In search for more efficacious and broad‐spectrum alternatives, we have assessed in vivo the mortality‐reducing efficacy of a group of five compounds with known AChE inhibitory activity (pyridostigmine, physostigmine, ranitidine, tacrine and K‐27), when given in equitoxic dosage (25% of LD01) 30 min before exposure to the OPC terbufos sulfone. Protection was quantified in rats by determining the relative risk of death (RR) using Cox analysis, with RR = 1 for animals given only terbufos sulfone, but no pre‐treatment. All tested AChE inhibitors reduced terbufos sulfone‐induced mortality significantly (p ≤ 0.05) as compared with the non‐treatment group (RR = 1: terbufos sulfone only). Best in vivo protection from terbufos sulfone‐induced mortality was achieved, when K‐27 was given before terbufos sulfone exposure (RR = 0.06), which was significantly (P ≤ 0.05) superior to the pre‐treatment with all other tested compounds, for example tacrine (RR = 0.21), pyridostigmine (RR = 0.28), physostigmine (RR = 0.29) and ranitidine (RR = 0.33). The differences in efficacy between tacrine, pyridostigmine, physostigmine and ranitidine were not statistically significant. Prophylactic administration of an oxime (such as K‐27) in case of imminent OPC exposure may be a viable option. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
7.
ABSTRACT. In jaundiced newborn infants, hemolytic disease is considered a risk factor for kernicterus due to the suspected competition between bilirubin and other hemoglobin breakdown products for albumin binding. We have studied the effect of hematin on bilirubin-albumin binding using the peroxidase assay and a light-scattering technique for measuring unbound bilirubin. Our results show that hematin does not affect bilirubin-albumin binding. To determine if other albumin binding functions are affected by hematin, we used a microdialysis rate technique employing two ligands, diazepam and monoacetyldiaminodiphenyl sulfone (MADDS). Hematin does not utilize the diazepam binding function of albumin, but does decrease the albumin binding of MADDS. The results of this study indicate that the MADDS and bilirubin binding functions are not identical. The clinical usefulness of reserve albumin equivalent determination using MADDS is discussed.  相似文献   
8.
季红  袁牧  朱柳 《中国当代医药》2009,16(7):121-122
目的:研究卤化物介导的法呢基砜的简便合成方法。方法:以THF为溶剂,先用卤化试剂NBS和Ph3P对法呢醇进行活化.活性中间体在NaI催化下与苯亚磺酸钠于室温反应6h得法呢基砜。结果:在优化条件下合成香叶基砜的收率高于90%。结论:该法反应条件温和、操作简便,简化了从法呢醇制备法呢基砜的步骤。  相似文献   
9.
《Toxicology in vitro》2011,25(5):1075-1084
The effects of arsenic trioxide (ATO) in combination with sulindac (SUL), sulindac sulfide (SS) or sulindac sulfone (SF) on human (Jurkat, HL-60, K562 and HPB-ALL) and mouse (EL-4) leukemic cell lines were investigated. The cells showed different sensitivity to sulindacs (2.5-200 μM) with SS being the most cytotoxic (72 h WST-1 reduction test). The cytotoxicity of ATO was enhanced by combination with sulindacs. The combination of ATO (1 μM) with SS or SF at concentrations over 50 μM induced considerable cytotoxicity in all cell lines. Normal human lymphocytes exposed for 48 h to the combinations showed smaller decrease in viability. Measurements of Jurkat, HL-60 and K562 cells exposed to ATO (1 μM) and sulindacs (100 μM or 200 μM for K562 cells) indicated apoptosis as the main cell death mechanism. The mitochondrial membrane potential measurements (JC-1 probe) indicated an active involvement of mitochondria in the process. The results did not indicate involvement of an inhibitory effect of the combinations on NF-κB activity in Jurkat, HL-60 and K562 cells.  相似文献   
10.
采用溶液共混制备耻不同比例的热致液晶共聚酯/含酚酞侧基聚芳醚砜共混物。利用锥板流变仪对共混体系的熔体流变性能进行了初步研究,测定了熔体粘度-温度、粘度-剪切速度的关系,结果表明该液晶聚合物能明显降低聚芳醚砜的熔体粘度。  相似文献   
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