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31.
Analysis of Solvent Effect on Mechanical Properties of Poly(ether ether ketone) Using Nano-indentation 下载免费PDF全文
Tanveer Iqbal Saima Yasin Ahmad Shakeel Hamayoun Mahmood Fahad Nazir Paul F. Luckham 《化学物理学报(中文版)》2018,31(2):211-215
Poly (ether ether ketone)(PEEK) is a high-performance semi-crystalline thermoplastic polymer.Exposure of the polymeric surface to solvents can have a strong effect like softening/swelling of polymeric network or dissolution.In this study, nano-indentation analysis was performed to study the effect of acetone on the surface mechanical properties of PEEK using different exposure time.The experiments were performed with a constant loading rate (10 nm/s) to a maximum indentation displacement (1000 nm).A 30-second hold segment was included at the maximum load to account for any creep effects followed by an unloading segment to 80% unloading.The indentation hardness and the elastic modulus were computed as a continuous function of the penetration displacement in the continuous stiffness mode (CSM) indentation.The experimental data showed that the peak load decreased from ~5.2 mN to ~1.7 mN as exposure time in solvent environment increased from 0 to 18 days.The elastic modulus and the hardness of PEEK samples also displayed a decreasing trend as a function of exposure time in the solvent environment.Two empirical models were used to fit the experimental data of hardness as a function of exposure time which showed a good agreement with the experimental values. 相似文献
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Lughmani Faiza Nazir Farzana Khan Shahid Ali Iqbal Mudassir 《Cellulose (London, England)》2022,29(3):1911-1928
Cellulose - In this study, microcrystalline cellulose (MCC) was modified to oxidized cellulose (OC), 6-deoxycellulose hydrazide and 6-deoxycellulose (N,N-diethyl)amine (MCC-Hyd and MCC-DEM)... 相似文献
34.
Tzanko Donchev Alina Ilinca Lazu Ammara Nosheen 《Set-Valued and Variational Analysis》2013,21(2):283-296
The main qualitative properties of the solution set of almost lower (upper) semicontinuous one-sided Perron differential inclusion with state constraints in finite dimensional spaces are studied. Using the technique introduced by Veliov (Nonlinear Anal 23:1027–1038, 1994) we give sufficient conditions for the solution map of the above state constrained differential inclusion to be continuous in the sense of Hausdorff metric. An application on the propagation of the continuity of the state constrained minimum time function associated with the nonautonomous differential inclusion and the target zero is given. Some relaxation theorems are proved, which are used afterward to derive necessary and sufficient conditions for invariance. 相似文献
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Zahoor Qadir Samra Sadaf Shabir Zainab Rehmat Mariam Zaman Aqsa Nazir Nadia Dar Muhammad Amin Athar 《Applied biochemistry and biotechnology》2010,162(3):671-686
Human serum paraoxonase 1 (PON1) is known as an antioxidant and is also involved in the detoxification of many compounds.
In this study, a novel purification strategy was employed to purify the PON1 by using cholesterol-conjugated magnetic nanoparticles.
Magnetic nanoparticles were synthesized and conjugated with cholesterol through diazotized p-aminohippuric acid. In Fourier transform infrared spectrum of cholesterol-p-aminohippuric acid-Fe3O4 nanoparticles, the appearance of peaks at 3,358.3, 1,645 cm−1, and at 2,334.9 cm−1 confirmed the conjugation. The molecular weight of purified PON1 was nearly 45 kDa on sodium dodecyl sulfate (SDS)–polyacrylamide
gel electrophoresis (PAGE), and isoelectric point was 5.3. The specific activity was 438 U mg−1 protein, and the purification fold was 515 with 73% yield. The K
m values were 1.3 and 0.74 mM with paraoxon and phenyl acetate, respectively. Western blot of 2D-PAGE confirmed the homogeneity
and stability of the enzyme. Mg+2, Mn+2, glycerol, (NH4)2SO4, PEG 6000, Triton X-100, and phenylmethylsulfonyl fluoride did not show any effect on activity. Pb+2, Co+2, Zn2+, ethanol, β-mercaptoethanol, and acetone reduced the activity while Ni2+, Cd2+, Cu2+, iodoacetic acid, SDS, dimethylformamide, DMSO inhibited the activity. In vitro enzyme activity was slightly reduced by acetyl
salicylic and acetaminophen and reduced 50% with amino glycosides and ampicillin antibiotics at concentrations of 0.6 and
30 mg ml−1, respectively. This is the first report for the synthesis of cholesterol-conjugated magnetic nanoparticles for simple purification
of PON1 enzyme. 相似文献
36.
In the radiolysis of cyclohexane in presence of 4×10?3M diphenylmercury (Hg φ3) three isomers of hexane, methylcyclopentane (G=0.018), benzene (G=0.42) and cyclohexene (G=0.047) were detected. Addition of benzene in the mixture of cyclohexane and Hg φ3 formed two isomers of pentane, hexene and one isomer of hexane as additional products, while cyclohexene was eliminated completely. Normally, eight products were detected in presence of 10 to 50% benzene. Total radiolytic yield of products increased in presence of 15 to 25% benzene but in presence of 35 to 50% benzene G values became very low. Considerable amount of hexene is formed in a mixture of benzene and cyclohexane but neither benzene nor cyclohexane in presence of Hg φ2 formed this compound. In the presence o. benzene and φ2Hg hexane yield is very much reduced. Protection is observed in presence of 10% as well as 35 to 50% benzene in this system. The plot of benzene concentration in moles/litre versus methylcyclopentane is linear and from the slope of the straight line, the values of rate constants were found to be 2.65×10?2 litre/mole sec., 5.25×10?3 litre mole sec., 9×10?7 litre/mole sec. for methylcyclopentane, cyclohexane and benzene respectively. A plot of G(–c-C6H12) versus 1/[C6H6] also gave a straight line which confirms the sponge type protection in this multicomponent system. 相似文献
37.
Analysis of commercial paraffin waxes by use of molecular sieves and decalin has been shown to give misleading results because of the formation of additional compounds. The source and the nature of these compounds have been investigated and it has been found that they are polymers of partially dehydrogenated decalin. Care should be taken when using this solvent in such analyses. 相似文献
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Muhammad Nazir Tahir Riaz-ul Qamar Ahmad Adnan Abdul Ghaffar Bong-Hyun Jun Jae-Hyuk Yu 《合成通讯》2014,44(5):589-599
The surface of glass microparticle (GMP) was functionalized with β-cyclodextrin (→ GMP-β-CD) and was characterized by x-ray photoelectron spectroscopy (XPS). GMP-β-CD was used to catalyze oxidation of alcohols into aldehydes and katones with excellent yield (86–92%). The modified surface of GMP-β-CD showed no change or degradation after repeated use as confirmed from XPS analysis after 10 cycles.
[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献