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901.
902.
Silver nanoparticles in chitosan medium were prepared by the chemical reduction method. Silver nitrate and hydrazine were used as the precursor and reducing agent in the present of chitosan as a natural host polymer. The samples are characterized by UV–visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The measurements of nonlinear optical properties were defined by Z-scan technique using green CW laser beam operated at 532 nm wavelengths. Thermal effect has a dominant role in the overall material nonlinearity with CW laser. It is shown that the synthesized samples have a negative nonlinear refractive index. 相似文献
903.
A. Elahi M. Irfan M. Munawar M. Qasim K. Mahmood M. Saeed N. A. Niaz A. Shakoor M. Ahmad A. Ali 《Polymer Science Series A》2016,58(3):429-437
Polypyrrole (PPy) doped with dodecylbenzene sulfonic acid was synthesized and was blended with compatible polymer PMMA in chloroform. Flexible and free-standing films with compositions PPy: PMMA = 10: 90, 20: 80, 30: 70, and 50: 50 were obtained. The percentage of crystallinity and particle size of synthesized polymers were estimated from X-rays diffraction studies. Scanning Electron Micrographs showed that phase separation was observed and compatibility of the mixture decreased with increase of PMMA content. The dielectric measurements were performed in the frequency range 0.1 kHz–1 MHz in temperature range 303–473 K. The frequency dependent conductivity (σac) obeyed a power law of frequency with an exponent s < 1. Electric modulus formalism exhibits a peak in frequency. The peak of conductivity relaxation shifted towards higher frequencies and the magnitude of relaxation decreased with the increase of PMMA content in the composites. 相似文献
904.
Fabrication of polyaniline‐coated halloysite nanotubes by in situ chemical polymerization as a solid‐phase microextraction coating for the analysis of volatile organic compounds in aqueous solutions 下载免费PDF全文
Mir Mahdi Abolghasemi Naser Arsalani Vahid Yousefi Mahmood Arsalani Marzieh Piryaei 《Journal of separation science》2016,39(5):956-963
We have synthesized an organic–inorganic polyaniline–halloysite nanotube composite by an in situ polymerization method. This nanocomposite is immobilized on a stainless‐steel wire and can be used as a fiber coating for solid‐phase microextraction. It was found that our new solid‐phase microextraction fiber is an excellent adsorbent for the extraction of some volatile organic compounds in aqueous samples in combination with gas chromatography and mass spectrometry. The coating can be prepared easily, is mechanically stable, and exhibits relatively high thermal stability. It is capable of extracting phenolic compounds from water samples. Following thermal desorption, the phenols were quantified by gas chromatography with mass spectrometry. The effects of extraction temperature, extraction time, sample ionic strength, stirring rate, pH, desorption temperature and desorption time were studied. Under optimal conditions, the repeatability for one fiber (n = 5), expressed as the relative standard deviation, is between 6.2 and 9.1%. The detection limits range from 0.005 to 4 ng/mL. The method offers the advantage of being simple to use, with a shorter analysis time, lower cost of equipment and higher thermal stability of the fiber in comparison to conventional methods of analysis. 相似文献
905.
A.H. Bhrawy A.A. Alshaery E.M. Hilal Michelle Savescu Daniela Milovic Kaisar R. Khan Mohammad F. Mahmood Zlatko Jovanoski Anjan Biswas 《Optik》2014
This paper studies the propagation of solitons through birefringent fibers in the presence of spatio-temporal dispersion. Both Kerr and parabolic laws of nonlinearity are addressed. The exact 1-soliton solutions are obtained. There are several constraint conditions that ensure soliton solutions are derived. Three types of solitons are obtained: bright, dark and singular solitons. 相似文献
906.
Dr. Zafar Mahmood Jia He Shuqing Cai Zhanxiang Yuan Hui Liang Qian Chen Prof. Yanping Huo Prof. Burkhard König Prof. Shaomin Ji 《Chemistry (Weinheim an der Bergstrasse, Germany)》2023,29(1):e202202677
Tuning the redox potential of commonly available photocatalyst to improve the catalytic performance or expand its scope for challenging synthetic conversions is an ongoing demand in synthetic chemistry. Herein, the excited state properties and redox potential of commercially available [Ru(bpy)3]2+ photocatalyst were tuned by modifying the structure of the bipyridine ligands with electron-donating/withdrawing units. The visible-light-mediated photoredox phosphorylation of tertiary aliphatic amines was demonstrated under mild conditions. A series of cross-dehydrogenative coupling reactions were performed employing the RuII complexes as photocatalyst giving the corresponding α-aminophosphinoxides and α-aminophosphonates via carbon-phosphorus (C−P) bond formation. 相似文献
907.
Meccanica - Compliance is a strong requirement for human–robot interactions. Soft-robots provide an opportunity to cover the lack of compliance in conventional actuation mechanisms, however,... 相似文献
908.
Mahmood Hafiz Tariq Tsotsas Evangelos Kharaghani Abdolreza 《Transport in Porous Media》2021,140(1):351-369
Transport in Porous Media - The mass exchange between the surface of a model capillary porous medium and the adjacent gas-side boundary layer is studied in the limiting condition of isothermal,... 相似文献
909.
Arwa Al-shargabi Wan Ahmad Kamil Mahmood Chun-Chieh Han Hong-Cheu Lin Masato M Ito 《Liquid crystals》2020,47(2):219-230
ABSTRACT New liquid crystals categorised as cholesteryl dimers have been successfully synthesised through the reaction between cholesteryl 4-(prop-2-ynyloxy)benzoate moieties with n-azido(cholesteryloxy-carbonyl)alkane. All the dimers display enantiotropic mesophases. Whilst the odd-numbered dimers exhibit chiral nematic (N*), twisted grain boundary (TGB) and chiral smectic C (SmC*) phases, the even-numbered members from the same series show chiral smectic A and C. A detailed inspection on mesophase reveals that the chiral centres and the bent conformation of the odd-numbered members are essential for the induction of TGB phase. However, upon decreasing the temperature, the ratio of the transition temperatures (TSmC*-SmA*/TSmA*-I) is found to be 0.95, which indicate the second order transition according to the McMillan’s molecular theory. In addition, the X-ray diffraction study supports the presence of the smectic A phase on the even members rather than the N* by the appearance of the Bragg diffraction peaks at 190°C. A comparison study with the other analogues in which the cholesterol entity is substituted by azobenzene or biphenyl tails has been carried out to assess the relationship between the molecular structure and mesomorphic behaviour. 相似文献
910.
Negin Davoodian Ali Nakhaei Pour Mohammad Izadyar Ali Mohammadi Alireza Salimi Seyed Mehdi Kamali Shahri 《应用有机金属化学》2020,34(9):e5747
The Fischer–Tropsch synthesis using cobalt catalysts supported on zeolitic imidazolate frameworks (ZIFs), ZIF-7 and ZIF-8, has been investigated. ZIF-7, ZIF-8 and corresponding cobalt-containing catalysts, after preparation, were characterized using various techniques. Thermogravimetric analysis results show that ZIF-7 and ZIF-8 supports have good thermal stability for the Fischer–Tropsch synthesis reaction, and weaker interaction between cobalt and zinc in the ZIF-7 and ZIF-8 supports results in more cobalt reduction. The catalytic performance was evaluated in Fischer–Tropsch synthesis and compared with that of a cobalt catalyst supported on SBA-15 promoted with zinc. The pore structure of the ZIF supports plays an essential role in product selectivity for the prepared catalysts. The carbon number in hydrocarbon products and olefin selectivity depend on cobalt dispersion and support structure owing to the impacts of site density and carrier skeleton on the speed of diffusion-enhanced olefin re-adsorption reactions. 相似文献