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71.
Jens Schoene Hassen Bel Abed Mathias Christmann Marc Nazaré 《Tetrahedron letters》2017,58(16):1633-1635
A versatile two-step, one-pot reaction to access N-substituted-2H-indazol-2-amine derivatives has been elaborated. A diverse set of analogues was obtained by a sequential hydrazone formation and reductive cyclization in moderate to good yields from readily available starting materials. The strategy tolerates a broad range of substitutions pattern and functional groups allowing further derivatizations. 相似文献
72.
In this paper, a non-isobaric Marangoni boundary layer flow that can be formed along the interface of immiscible nanofluids
in surface driven flows due to an imposed temperature gradient, is considered. The solution is determined using a similarity
solution for both the momentum and energy equations and assuming developing boundary layer flow along the interface of the
immiscible nanofluids. The resulting system of nonlinear ordinary differential equations is solved numerically using the shooting
method along with the Runge-Kutta-Fehlberg method. Numerical results are obtained for the interface velocity, the surface
temperature gradient as well as the velocity and temperature profiles for some values of the governing parameters, namely
the nanoparticle volume fraction φ (0≤φ≤0.2) and the constant exponent β. Three different types of nanoparticles, namely Cu, Al2O3 and TiO2 are considered by using water-based fluid with Prandtl number Pr =6.2. It was found that nanoparticles with low thermal conductivity,
TiO2, have better enhancement on heat transfer compared to Al2O3 and Cu. The results also indicate that dual solutions exist when β<0.5. The paper complements also the work by Golia and Viviani (Meccanica 21:200–204, 1986) concerning the dual solutions in the case of adverse pressure gradient. 相似文献
73.
Shazia Bashir Nazar Farid Khaliq Mahmood M. Shahid Rafique 《Applied Physics A: Materials Science & Processing》2012,107(1):203-212
The ablation of Cd has been performed by employing Q-switched Nd: YAG 10 ns laser pulses with a central wavelength of 1064 nm
for a pulsed energy of 200 mJ under various ambient environments of argon, air and helium. The optical emission spectroscopy
of Cd plasma has been studied under different filling pressures of shield gases ranging from 5 torr to 760 torr using LIBS
spectrometer system. The effect of different gases and their pressures on the intensity of spectral emission, electron temperature
and density of the laser-produced plasma has been investigated. SEM analysis has been performed to investigate the dependence
of surface morphological changes of an irradiated target on the nature and pressure of an ambient gas. A strong correlation
has revealed the vital role of electron temperature and density of laser-induced plasma for the surface modification of Cd.
These results strongly indicate that the nature and pressure of the ambient atmosphere is one of the controlling factors of
the plasma characteristics, as well as the factors related to the laser energy absorption for surface modification. 相似文献
74.
In this paper, the problem of free convection boundary layer flow on a solid sphere in a micropolar fluid with Newtonian heating,
in which the heat transfer from the surface is proportional to the local surface temperature, is considered. The transformed
boundary layer equations in the form of partial differential equations are solved numerically using an implicit finite-difference
scheme. Numerical solutions are obtained for the local wall temperature, the local skin friction coefficient, as well as the
velocity, angular velocity and temperature profiles. The features of the flow and heat transfer characteristics for different
values of the material or micropolar parameter K, the Prandtl number Pr and the conjugate parameter γ are analyzed and discussed. 相似文献
75.
Nazar Ul Islam Kamran Jalil Muhammad Shahid Naveed Muhammad Abdur Rauf 《Arabian Journal of Chemistry》2019,12(8):2310-2319
This paper reports a rapid, facile and one-pot synthesis of environmentally safe gold nanoparticles capped and stabilized with galls extract of Pistacia integerrima. The aqueous gold ions when exposed to P. integerrima galls extract were rapidly reduced as evident from abrupt color change to ruby red, suggesting the biosynthesis of gold nanoparticles (Au-NPs) which were further characterized by UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). Their stability was evaluated against varying pH and different volumes of sodium chloride (NaCl) as well as at a range of temperature (20–80 °C). Au-NPs were tested for enzyme inhibition, antibacterial, antifungal, antinociceptive, muscle relaxant and sedative activities. The UV–Vis spectra of the gold nanoparticles gave surface plasmon resonance at 540 nm while the SEM analysis revealed the particle size in the range of 20–200 nm. FTIR spectra confirmed the involvement of amines, amide groups and alcohols in capping and reduction of gold nanoparticles. Au-NPs showed remarkable stability in different NaCl and pH solutions as well as at elevated temperature. Au-NPs have good antifungal activity and possessed antinociceptive and muscle relaxant properties as observed from their zone of inhibition and significant attenuation of acetic acid induced writhing and reduction of time spent on the rota rod respectively. These results concluded that the gall extract of P. integerrima is a very good bioreductant for the synthesis of gold nanoparticles that have potential for various biomedical and pharmaceutical applications. 相似文献
76.
Leli Deswita Roslinda Nazar Anuar Ishak Rokiah Ahmad Ioan Pop 《Heat and Mass Transfer》2010,46(8-9):1013-1018
The effects of suction/injection on steady laminar mixed convection boundary layer flow over a permeable horizontal surface of a wedge in a viscous and incompressible fluid is considered in this paper. The similarity solutions of the governing boundary layer equations are obtained for some values of the suction/injection parameter f 0, the constant exponent m of the wall temperature as well as the mixed convection parameter λ. The resulting system of nonlinear ordinary differential equations is solved numerically for both assisting and opposing flow regimes using an implicit finite-difference scheme known as the Keller-box method. Numerical results for the reduced skin friction coefficient, the local Nusselt number, and the velocity and temperature profiles are obtained for various values of parameters considered. Dual solutions are found to exist for the case of opposing flow. 相似文献
77.
The infrared chemiluminescence technique has been used to obtain k(V′, R′, T′) (V′, R′, Tt? are product vibrational, rotational and translational energies) for the reactions (i) H + ClNO → HCl + NO (energy-release Etot′ = 68.5 kcal mole?1) and (ii) H + CII → HCl + I (Etot′ = 55.8 kcal mole?1). Reaction (i) exhibits inefficient conversion of energy-release into vibration in the new bond, characteristic of a light attacking atom reacting on a repulsive energy-surface. Reaction (ii) has a bimodal HCl product-energy-distribution suggesting that 18% of the reaction proceeds by direct attack at the Cl end of CII to yield low V′ and R′, and 82% by indirect reaction from the 1 end to give high V′ and R′. 相似文献
78.
Synthesis,spectroscopic characterization,and computed optical analysis of green fluorescent cyclohexenone derivatives 下载免费PDF全文
Muhammad Faizan Nazar Amir Badshah Asif Mahmood Muhammad Naveed Zafar Muhammad Ramzan Saeed Ashraf Janjua Muhammad Asam Raza Riaz Hussain 《Journal of Physical Organic Chemistry》2016,29(3):152-160
Cyclohexenone containing chalcones core is one important class of materials, which exhibit high nonlinear optical (NLO) responses and good crystallizability. The present study reports the successful development of six new fluorescent cyclohexenone derivatives (CDs) via conventional Robinson annulation method. The molecular structures of these newly synthesized CDs were confirmed by using various analytical techniques such as 1H NMR, 13C NMR, FTIR, EIMS, UV–Vis spectroscopy and single crystal X‐ray diffraction. The crystallographic data revealed that the spatial structure of the representative CD (4BE) belongs to monoclinic, P21/c space group. The results from luminescence studies show that the CDs molecules apparently emit intense green light at room temperature in aqueous media. The relative polarity and molecular chemical stability of the CDs molecules were predicted by measuring the molecular electrostatic potential and frontier molecular orbital energy. In addition, the UV–Vis spectra, transition character and electronic structures of these CDs were computed by using quantum chemical methodology. It was interesting to note that the values of computed and experimental electronic transitions (λmax) were in good agreement and these CDs display high hyperpolarizability (β) values. The present work will be helpful for systematical understanding of the structures and the optical properties of CDs for studying the structure–activity relationship that will suggest their potential application in photonic devices. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
79.
M. N. Zafar M. F. Nazar S. H. Sumrra Gul-E-Saba A. Yasmin A. H. Atif 《Russian Journal of Coordination Chemistry》2016,42(4):225-251
This review provides a broad overview of the literature related to the importance of ligands in homogeneous catalysis. In particular, it describes the types of nitrogen donor ligands that have typically been used for homogeneous catalysis. We surveyed the important transition metal homogenous catalysts explicitly from 2011 up to early 2014 and summarize their comparative catalytic activities. Generally, the main factors observed are the ligand structure, electron donor property and steric bulk which can affect the catalytic activity. Electron count and inductive effect can also influence the efficiency of homogeneous catalyst. 相似文献
80.
Strategic synthesis of SBA-15 nanorods 总被引:1,自引:0,他引:1
A simple synthesis of homogeneously sized, ordered mesoporous silica nanorods (SBA-15), spanning about 10 porous channels in width and ranging from 300 to 600 nm in length is reported. 相似文献