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81.
Amanmammet Bugrayev Nazli Al-Haq Rukeme A. Okopie Asma Qazi Michael Suggate Alice C. Sullivan John R.H. Wilson 《Journal of molecular catalysis. A, Chemical》2008,280(1-2):96-101
New covalently linked sulfonic acid modified silicas have been formed and characterised and their catalytic Brönsted activity evaluated. Thus phenylmercaptoethyltrimethoxysilane, (MeO)3SiCH2CH2SC6H5 and benzylmercaptoethyltrimethoxysilane, (MeO)3SiCH2CH2SCH2C6H5, were used to prepare the corresponding T-functional silica derivatives silica CH2CH2SC6H4-4-SO3H and silica CH2CH2SCH2C6H4-4-SO3H by grafting on commercial silica, followed by sulfonation of the aryl group. Solid-state NMR, DTA and surface area characteristics of the materials are reported. The mercaptophenylsulfonic acid materials are thermally robust highly efficient solid catalysts for a range of transformations including, esterification, etherification and carbonyl group protection. An apparent pore size effect on rate of conversion was observed. The mercaptobenzylsulfonic acid materials were comparatively unstable. 相似文献
82.
Daphne mucronata-mediated phytosynthesis of silver nanoparticles and their novel biological applications,compatibility and toxicity studies 总被引:1,自引:0,他引:1
Asma Shah Ghosia Lutfullah Ali Talha Khalil Malik Maaza 《Green Chemistry Letters and Reviews》2018,11(3):318-333
This contribution reports the biosynthesis of silver nanoparticles (AgNPs) using aqueous leaf extracts of D. mucronata and their diverse applications. Synthesized AgNPs were characterized using diverse techniques, i.e. UV, XRD, EDS, SEM, TEM, FTIR and TGA/DTA. These techniques confirmed the authenticity of the synthesized nanoparticles. The bimodulated AgNPs revealed the highest radical scavenging potential, i.e. 86.4% relative to plant extract at 600?μg/ml. Escherichia coli was found to be the most susceptible strain to AgNPs. Growth of vancomycin-resistant Staphylococcus aureus was also inhibited. Hemolytic activity revealed negligible hemolysis, indicating the biocompatible nature of biomodulated AgNPs. Furthermore, no mutagenic properties were shown by the biogenic AgNPs. Synthesized nanoparticles possessed promising insecticidal potential and had no phytotoxic activity. No haemagglutination was observed for biogenic AgNPs. 相似文献
83.
84.
Mahreen Akram Shazia Bashir Muhammad Shahid Rafique Asma Hayat Khaliq Mahmood 《Plasma Chemistry and Plasma Processing》2017,37(1):287-304
Surface modifications of laser irradiated molybdenum have been correlated with plasma parameters. Nd:YAG laser (1064 nm, 10 ns) was employed at various laser irradiances ranging from 6 to 50 GW/cm2 under argon environment. The ablation efficiency has been investigated by measuring the crater depth using surface profilometry analysis. Scanning electron microscope (SEM) analysis reveals the formation of coarse grains along with cracked boundaries, cavities and cones at the central ablated areas. Whereas, uplifted re-solidified material, cavities, ridges, droplets and cones were observed at boundary regions. Laser Induced Breakdown Spectroscopy (LIBS) analysis has been performed to evaluate electron temperature and number density of molybdenum plasma. Electron temperature and electron density varies from 6670 to 9305 K and 0.62 × 1018 to 0.72 × 1018 cm?3 respectively. Both the parameters showed similar trend in variation with laser irradiance i.e. an initial increase from 13 to 19 GW/cm2 followed by a decrease from 19 to 25 GW/cm2 and then a saturation from 25 to 50 GW/cm2. The initial increasing trend is attributed to the enhanced excited vapor content of the ablated material, confinement effects of the surrounding argon and absorption of laser energy into the molybdenum vapor plasma during the trailing part of laser pulse leading to ignition of laser supported combustion (LSW) waves. The decreasing trend is attributed to the shielding effect and saturation is explainable on the basis of the formation of a self-regulating regime. Surface modifications of laser irradiated molybdenum were correlated with the plasma parameters. 相似文献
85.
Belhadj Asma Bessrour Jamel Bouhafs Mahmoud Barrallier Laurent 《Journal of Thermal Analysis and Calorimetry》2009,97(3):911-915
In this paper we are concerned with the t-dependent cooling velocity during laser welding sequences. The temperature profile
has been yielded by using keyhole approximation for the melted zone and solving the heat transfer equation. A polynomial expansion
has been adopted as a guide to determining the cooling velocity during welding cut-off stage. A thorough comparison with experimental
results and recently published profiles has been carried out. 相似文献
86.
Sayed Mehdi Ghoreishi Mohsen Behpour Mona Delshad Asma Khoobi 《Central European Journal of Chemistry》2012,10(6):1824-1829
Tyrosine (Tyr) was quantitated with high sensitivity and selectivity in the presence of uric acid (UA) using a carbon paste electrode modified with multi-walled carbon nanotubes. Tyr and UA were catalytically oxidized with diffusion-controlled characteristics. They were determined simultaneously by differential pulse voltammetry with a potential difference of 350 mV. The electrocatalytic currents increase linearly with Tyr and UA concentrations 4×10?7?1×10?4 M and 3×10?7?2×10?4 M. Their detection limits were 1×10?7 and 5.1×10?8 M respectively. In the presence of sodium dodecyl sulfate the Tyr detection limit improved from 1×10?7 to 6.9×10?8 M. The electrode was successfully used to quantitate Tyr and UA in serum. 相似文献
87.
Abdul Wajid Khan Saleem Jan Shaista Parveen Rahmat Ali Khan Asma Saeed Abdul Jabbar Tanveer Anwar Ali Shad 《Chemistry Central journal》2012,6(1):1-6
Background
Nickel ferrite, a kind of soft magnetic materials is one of the most attracting class of materials due to its interesting and important properties and has many technical applications, such as in catalysis, sensors and so on. In this paper the synthesis of NiFe2O4 nanoparticles by the hydrothermal method is reported and the inhibition of surfactant (Glycerol or Sodium dodecyl sulfate) on the particles growth is investigated.Methods
For investigation of the inhibition effect of surfactant on NiFe2O4 particles growth, the samples were prepared in presence of Glycerol and Sodium dodecyl sulfate. The X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM) and inductively coupled plasma atomic emission spectrometer (ICP-AES) techniques were used to characterize the samples.Results
The results of XRD and ICP-AES show that the products were pure NiFe2O4 and also nanoparticles grow with increasing the temperature, while surfactant prevents the particle growth under the same condition. The average particle size was determined from the Scherrer's equation and TEM micrographs and found to be in the range of 50-60 nm that decreased up to 10-15 nm in presence of surfactant. The FT-IR results show two absorption bands near to 603 and 490 cm-1 for the tetrahedral and octahedral sites respectively. Furthermore, the saturated magnetization and coercivity of NiFe2O4 nanoparticles were in the range of 39.60 emu/g and 15.67 Qe that decreased for samples prepared in presence of surfactant. As well as, the nanoparticles exhibited a superparamagnetic behavior at room temperature.Conclusions
Nanosized nickel ferrite particles were synthesized with and without surfactant assisted hydrothermal methods. The results show that with increasing of temperature, the crystallinity of nanoparticles is increased. In the presence of surfactants, the crystallinity of NiFe2O4 nanoparticles decreased in comparison with surfactant- free prepared samples. All of the nickel ferrite nanoparticles were superparamagnetic at room temperature.Graphical abstract
相似文献88.
Tougerti A Llorens I D'Acapito F Fonda E Hazemann JL Joly Y Thiaudière D Che M Carrier X 《Angewandte Chemie (International ed. in English)》2012,51(31):7697-7701
Surface-dependent precipitation: The adsorption of Ni(II) complexes in aqueous solution on (0001) and (1102) α-Al(2)O(3) single-crystal surfaces has been studied (see the X-ray absorption spectra obtained for parallel and perpendicular polarization directions). The use of planar model systems emphasizes the crucial role of the Al(2)O(3) orientation for Ni dispersion with practical implications in catalyst preparation procedures. 相似文献
89.
Montazer M Behzadnia A Pakdel E Rahimi MK Moghadam MB 《Journal of photochemistry and photobiology. B, Biology》2011,103(3):207-214
In this study an effective nanocomposite antimicrobial agent for wool fabric was introduced. The silver loaded nano TiO(2) as a nanocomposite was prepared through UV irradiation in an ultrasonic bath. The nanocomposite was stabilized on the wool fabric surface by using citric acid as a friendly cross-linking agent. The treated wool fabrics indicated an antimicrobial activity against both Staphylococcus aureus and Escherichia coli bacteria. Increasing the concentration of Ag/TiO(2) nanocomposite led to an improvement in antibacterial activities of the treated fabrics. Also increasing the amount of citric acid improved the adsorption of Ag/TiO(2) on the wool fabric surface leading to enhance antibacterial activity. The EDS spectrum, SEM images, and XRD patterns was studied to confirm the presence of existence of nanocomposite on the fabric surface. The role of both cross-linking agent and nanocomposite concentrations on the results was investigated using response surface methodology (RSM). 相似文献
90.