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101.
Effects of external fields on a two-dimensional Klein-Gordon particle under pseudo-harmonic oscillator interaction
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We study the effects of the perpendicular magnetic and Aharonov-Bohm(AB) flux fields on the energy levels of a two-dimensional(2D) Klein-Gordon(KG) particle subjected to an equal scalar and vector pseudo-harmonic oscillator(PHO).We calculate the exact energy eigenvalues and normalized wave functions in terms of chemical potential parameter,magnetic field strength,AB flux field,and magnetic quantum number by means of the Nikiforov-Uvarov(NU) method.The non-relativistic limit,PHO,and harmonic oscillator solutions in the existence and absence of external fields are also obtained. 相似文献
102.
Sameer M. Ikhdair 《Central European Journal of Physics》2012,10(2):361-381
Using an approximation scheme to deal with the centrifugal (pseudo-centrifugal) term, we solve the Dirac equation with the
screened Coulomb (Yukawa) potential for any arbitrary spin-orbit quantum number κ. Based on the spin and pseudospin symmetry, analytic bound state energy spectrum formulas and their corresponding upper-
and lower-spinor components of two Dirac particles are obtained using a shortcut of the Nikiforov-Uvarov method. We find a
wide range of permissible values for the spin symmetry constant C
s
from the valence energy spectrum of particle and also for pseudospin symmetry constant C
ps
from the hole energy spectrum of antiparticle. Further, we show that the present potential interaction becomes less (more)
attractive for a long (short) range screening parameter α. To remove the degeneracies in energy levels we consider the spin and pseudospin solution of Dirac equation for Yukawa potential
plus a centrifugal-like term. A few special cases such as the exact spin (pseudospin) symmetry Dirac-Yukawa, the Yukawa plus
centrifugal-like potentials, the limit when α becomes zero (Coulomb potential field) and the non-relativistic limit of our solution are studied. The nonrelativistic solutions
are compared with those obtained by other methods. 相似文献
103.
Characterization of Rubber Epoxy Blends by Thermal Analysis 总被引:1,自引:0,他引:1
Differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and dynamic mechanical analysis (DMA) of the blends
ofepoxy cresol novolac (ECN) resin toughened with liquid carboxy terminated butadiene-co-acrylonitrile (CTBN) rubber have
been carried out. Exothermal heat of reaction (ΔH) due to crosslinking of the resin in presence of diaminodiphenyl methane(DDM, as amine hardener) showed a decreasing trend
with increasing rubber concentration. Enhancements of thermal stability as well as lower percentage mass loss of the epoxy-rubber
blends with increasing rubber concentration have been observed in TG. Dynamic mechanical properties reflected a monotonic
decrease in the storage modulus (E′) with increasing rubber content in the blends. The loss modulus (E″) and the loss tangent(tanδ) values, however, showed an increasing trend with rise of the temperature up to a maximum (peak)
followed by a gradual fall in both cases. Addition of 10 mass% of CTBN resulted maximum E″ and tanδ.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
104.
Jonathan Bould John D. Kennedy Rhodri Ll. Thomas Nigam P. Rath Lawrence Barton 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(11):1245-1247
The structural characterization of the osmahexaborane 2-carbonyl-2,2-bis(triphenylphosphine)-nido-2-osmahexaborane(9), [Os(B5H9)(C18H15P)2(CO)], (I), a metallaborane analogue of B6H10, confirms the structure proposed from NMR spectroscopy. The structure of the osmadecaborane 6-carbonyl-6,6-bis(triphenylphosphine)-nido-6-osmadecaborane(13), [Os(B9H13)(C18H15P)2(CO)], (IV), is similarly confirmed. The short basal B—B distance of 1.652 (8) Å in (I), not bridged by an H atom, mirrors that in the parent hexaborane(10) [1.626 (4) Å]. 相似文献
105.
Mohammed Alqarni Nader Ibrahim Namazi Sameer Alshehri Ibrahim A. Naguib Amal M. Alsubaiyel Kumar Venkatesan Eman Mohamed Elmokadem Mahboubeh Pishnamazi Mohammed A. S. Abourehab 《Molecules (Basel, Switzerland)》2022,27(14)
Industrial-based application of supercritical CO2 (SCCO2) has emerged as a promising technology in numerous scientific fields due to offering brilliant advantages, such as simplicity of application, eco-friendliness, and high performance. Loxoprofen sodium (chemical formula C15H18O3) is known as an efficient nonsteroidal anti-inflammatory drug (NSAID), which has been long propounded as an effective alleviator for various painful disorders like musculoskeletal conditions. Although experimental research plays an important role in obtaining drug solubility in SCCO2, the emergence of operational disadvantages such as high cost and long-time process duration has motivated the researchers to develop mathematical models based on artificial intelligence (AI) to predict this important parameter. Three distinct models have been used on the data in this work, all of which were based on decision trees: K-nearest neighbors (KNN), NU support vector machine (NU-SVR), and Gaussian process regression (GPR). The data set has two input characteristics, P (pressure) and T (temperature), and a single output, Y = solubility. After implementing and fine-tuning to the hyperparameters of these ensemble models, their performance has been evaluated using a variety of measures. The R-squared scores of all three models are greater than 0.9, however, the RMSE error rates are 1.879 × 10−4, 7.814 × 10−5, and 1.664 × 10−4 for the KNN, NU-SVR, and GPR models, respectively. MAE metrics of 1.116 × 10−4, 6.197 × 10−5, and 8.777 × 10−5errors were also discovered for the KNN, NU-SVR, and GPR models, respectively. A study was also carried out to determine the best quantity of solubility, which can be referred to as the (x1 = 40.0, x2 = 338.0, Y = 1.27 × 10−3) vector. 相似文献
106.
Wolfgang Dohle Xiangdong Su Yamni Nigam Edward Dudley Barry V. L. Potter 《Molecules (Basel, Switzerland)》2023,28(1)
A series of benzyl, phenyl guanidine, and aminoguandine hydrazone derivatives was designed and in vitro antibacterial activities against two different bacterial strains (Staphylococcus aureus and Escherichia coli) were determined. Several compounds showed potent inhibitory activity against the bacterial strains evaluated, with minimal inhibitory concentration (MIC) values in the low µg/mL range. Of all guanidine derivatives, 3-[2-chloro-3-(trifluoromethyl)]-benzyloxy derivative 9m showed the best potency with MICs of 0.5 µg/mL (S. aureus) and 1 µg/mL (E. coli), respectively. Several aminoguanidine hydrazone derivatives also showed good overall activity. Compounds 10a, 10j, and 10r–s displayed MICs of 4 µg/mL against both S. aureus and E. coli. In the aminoguanidine hydrazone series, 3-(4-trifluoromethyl)-benzyloxy derivative 10d showed the best potency against S. aureus (MIC 1 µg/mL) but was far less active against E. coli (MIC 16 µg/mL). Compound 9m and the para-substituted derivative 9v also showed promising results against two strains of methicillin-resistant Staphylococcus aureus (MRSA). These results provide new and potent structural leads for further antibiotic optimisation strategies. 相似文献
107.
We report an easy, one pot synthesis to prepare ordered CdS nanocrystals with varying inter-particle separation and characterize
the particle separation using x-ray diffraction at low and wide angles. 相似文献
108.
Cody Timmons Dianjun Chen C. Elizabeth Barney Sameer Kirtane Guigen Li 《Tetrahedron》2004,60(52):12095-12099
A new nitrogen source combination was found for the regio- and stereoselective diamination of α,β-unsaturated ketones. This combination employs the readily available and inexpensive combination of NCS and 2-NsNH2 as the electrophilic nitrogen source, and acetonitrile as the nucleophilic nitrogen source, respectively. The reaction is easily performed by mixing olefin, 2-NsNH2, NCS and 4 Å molecular sieves in freshly distilled acetonitrile at room temperature. The reaction is chemoselective without the formation of any haloamine side products. A new aziridinium ion formed from enones and 2-NsNHCl is suggested to exist and to react with nitrile via a [2+3] cycloaddition mechanism, which is responsible for the excellent regio-, stereoselectivity of the resulting diamination products. 相似文献
109.
Niraj K. Singh K.G. Suresh R. Nirmala A.K. Nigam S.K. Malik 《Journal of magnetism and magnetic materials》2006
Magnetization measurements have been carried out on the intermetallic compound TbNiAl in applied fields up to 120 kOe. Temperature dependence of magnetization under zero-field-cooled and field-cooled conditions shows thermomagnetic irreversibility, which is attributed to magnetic frustration. With the increase of field, the irreversibility decreases and vanishes completely at high fields. Magnetocaloric effect has been calculated in terms of isothermal magnetic entropy change using magnetization isotherms obtained at various temperatures. The maximum entropy change is 13.8 J kg−1 K−1 near the ordering temperature for a field change of 50 kOe. The refrigerant capacity is found to be 494 J kg−1 for the same field change and for a temperature difference of 52 K between the cold and the hot sinks. 相似文献
110.
Bimetallic Ag‐Pt Sub‐nanometer Supported Clusters as Highly Efficient and Robust Oxidation Catalysts
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Dr. Fabio R. Negreiros Dr. Avik Halder Dr. Chunrong Yin Dr. Akansha Singh Dr. Giovanni Barcaro Dr. Luca Sementa Dr. Eric C. Tyo Dr. Michael J. Pellin Dr. Stephan Bartling Dr. Karl‐Heinz Meiwes‐Broer Dr. Sönke Seifert Dr. Prasenjit Sen Dr. Sandeep Nigam Dr. Chiranjib Majumder Dr. Nobuyuki Fukui Dr. Hisato Yasumatsu Dr. Stefan Vajda Dr. Alessandro Fortunelli 《Angewandte Chemie (International ed. in English)》2018,57(5):1209-1213
A combined experimental and theoretical investigation of Ag‐Pt sub‐nanometer clusters as heterogeneous catalysts in the CO→CO2 reaction (COox) is presented. Ag9Pt2 and Ag9Pt3 clusters are size‐selected in the gas phase, deposited on an ultrathin amorphous alumina support, and tested as catalysts experimentally under realistic conditions and by first‐principles simulations at realistic coverage. In situ GISAXS/TPRx demonstrates that the clusters do not sinter or deactivate even after prolonged exposure to reactants at high temperature, and present comparable, extremely high COox catalytic efficiency. Such high activity and stability are ascribed to a synergic role of Ag and Pt in ultranano‐aggregates, in which Pt anchors the clusters to the support and binds and activates two CO molecules, while Ag binds and activates O2, and Ag/Pt surface proximity disfavors poisoning by CO or oxidized species. 相似文献