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61.
H. Dicko O. Pags R. Hajj Hussein G. K. Pradhan C. Narayana F. Firszt A. Marasek W. Paszkowicz A. Maillard C. Jobard L. Broch F. El Hajj Hassan 《Journal of Raman spectroscopy : JRS》2016,47(3):357-367
The apparently universal 1‐bond → 2‐mode percolation behavior in the Raman spectra of zincblende semiconductor alloys is generally observed for the short bond only, and not for the long one. In this work we perform a combined high‐pressure‐backward/near‐forward Raman study of the leading percolation‐type (Zn,Be)Se alloy (~50 at.% Be), which exhibits a distinct percolation doublet in the spectral range of its short Be―Se bond, in search of a Zn―Se analogue. The high‐pressure‐backward insight is not conclusive per se, but clarifies the perspective behind the near‐forward Raman study. The latter reveals an unique Zn―Se phonon–polariton. Its fair contour modeling depending on the scattering angle is achieved within the linear dielectric approach, based on ellipsometry measurement of the ZnBeSe refractive index. Somewhat surprisingly this reveals that the phonon–polariton in question is a ‘fractional’ one in that it carries only half of the available Zn―Se oscillator strength, as ideally expected in case of a BeSe‐like bimodal Raman behavior of the long Zn―Se bond. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
62.
Habu Tela Abba Wan Muhamad Saridan Wan Hassan Muneer Aziz Saleh Abubakar Sadiq Aliyu Ahmad Termizi Ramli Hassan Abdulsalam 《Isotopes in environmental and health studies》2018,54(5):522-534
The Jos Plateau has been reported to have elevated levels of natural background radiation. A few earlier studies have measured the levels of natural radioactivity for specific locations in the area. Our interest is to investigate how geology of the study area influences the activity concentrations of natural radionuclides. Thus, the activity concentrations of terrestrial radionuclides in soil samples collected across the geological formations of the Jos Plateau were determined by gamma spectrometry technique. The mean activity concentrations of 226Ra, 232Th and 40K were found to exceed their corresponding world reference values of 35, 40 and 400?Bq?kg?1, respectively. Data were compared using statistical methods, analysis of variance (ANOVA) and post hoc tests. The results revealed in some instances significant influences of geological types on the activity concentrations in the area. The spatial distribution maps of activity concentrations of 226Ra, 232Th and 40K were geostatistically interpolated by ordinary Kriging method using ArcGIS software. 相似文献
63.
Prasad G. Mahajan Nilam C. Dige Balasaheb D. Vanjare Hussain Raza Mubashir Hassan Sung-Yum Seo Seong-Karp Hong Ki Hwan Lee 《Journal of fluorescence》2018,28(6):1305-1315
Herein, we design and synthesized new fluorescein based derivatives by insitu formation of fluorescein ester and further treated with corresponding hydrazide and amine to yield respective compounds i.e. FB1, FB2, FB3 and FB4. The spectral purity and characterization was done by using IR, NMR and Mass spectroscopies. The synthesized derivatives were examined for their photophysical properties by using variety of organic solvents and results were discussed in details. The structural diversity of synthesized compounds motivate us to evaluate these compounds for urease inhibition. The compound FB3 (IC50?=?0.0456 μM) shows 100 fold more active against Jack bean urease than standard drug thiourea (IC50?=?4.7455 μM). Other synthesized compounds showed potent activity. Free radical percentage scavenging assay further supported the capacity of compounds to urease inhibition. While, molecular docking simulations helps to examine the molecular interactions of active compounds FB1, FB2, FB3 and FB4 within the binding site of urease enzyme. 相似文献
64.
K. I. Osman S. S. Hassan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(3):537-544
The steady state bistable behaviour of a three-level Λ-shape is
examined in the presence of a control field
$({\rm \Omega} +\chi \left( t\right)
e^{i\varphi})$({\rm \Omega} +\chi \left( t\right)
e^{i\varphi})
: Ω is the strong Rabi component,
$\chi \left(
t\right) $\chi \left(
t\right)
is the stochastic part with relative phase ϕ; with
quantum interference between decay channels taken into account. One- and
two-way phase switching effect for the transmitted field against the phase
are predicted at fixed values for the incident input field. Also cooperative
switching effect shows multistable/bistable behaviour. Quantum interference
tends to diminish the dispersive effects responsible for multistable
behaviour (in the input-output relation and the cooperative switching
diagram) and asymmetry (in the phase switching diagram). Equivalence of the
role of the stochastic part of the control field with that of the
“classically” squeezed field is shown to occur only in the absence
of quantum interference. 相似文献
65.
Mariame A. Hassan Loreto B. Feril Kosho Suzuki Nobuki Kudo Katsuro Tachibana Takashi Kondo 《Ultrasonics sonochemistry》2009,16(3):372-378
Three novel lipid-shell-type microbubbles (MBs), AS-0100, BG6356A and BG6356B, have been evaluated for their impact on ultrasound (US)-induced cell death and free radicals production. Previously studied and well-characterized US exposure conditions were employed in which human myelomonocytic lymphoma U937 cells were exposed to 1 MHz pulsed US beam (0.3 W/cm2, 10% duty factor) for 1 min with or without MBs. Three different concentrations of each MB were used. Apoptosis and cell lysis were assessed by examining phosphatidylserine externalization and by counting viable cells, respectively, 6 h post-exposure. Free radicals production and scavenging activities were evaluated using electron paramagnetic resonance (EPR)-spin trapping. The results showed that only AS-0100 and BG6356A were able to enhance the US-induced apoptosis, mainly by increasing the secondary necrosis. Apoptosis and cell lysis seemed to depend more on mechanical forces exerted by oscillating MBs while free radicals played a trivial role. BG series MBs exhibited pronounced scavenging activities. Generally, despite the need for further optimization, AS-0100 and BG6356A appear to be promising as adjuncts in cases where US-induced cell death is required. 相似文献
66.
Temperature dependence of the turn-on time delay (ton) of uncooled semiconductor laser diodes biased below and above threshold is analyzed in presence of data pattern effect. We show that even when the laser is biased at or slightly above threshold, the increase in temperature of operation will lead to increase in the threshold carrier (Nth) and consequently the laser diode will be biased below the threshold again and a significant value of ton will be produced. Thus, knowledge about a value of dc-bias current required to achieve zero ton within wide range of temperature degrees is important when considering uncooled laser diode in high-speed optical communication systems. The temperature dependence of ton is calculated according to the temperature dependence of Nth and Auger recombination coefficient (C) and not by the well-know exponentional relationship of threshold current with temperature. The temperature dependence of Nth is calculated according to the temperature dependence of laser cavity parameters. Advanced analytical model is derived in term of carrier density, recombination coefficients and the injection current (Iinj). The validity of proposed model is confirmed by a numerical method. In addition, approximated models are included where under specified assumptions the proposed model reduces to the well-known approximate models of ton. According to our typical values and at a specified value of modulation current, the dc-bias one (Iib) should be increased from Iib = Ith to Iib ≈ 1.25 and 1.5Ith in order to achieve approximately zero ton when the temperature increases from 25°C to 55°C and 85°C, respectively. 相似文献
67.
Hassan Bassereh Vahid Salari Farhad Shahbazi Tapio Ala-Nissila 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(6):111
We consider quantum excitation energy transport (EET) in a network of two-state nodes in the Markovian approximation by employing the Lindblad formulation. We find that EET from an initial site, where the excitation is inserted to the sink, is generally inefficient due to the inhibition of transport by localization of the excitation wave packet in a symmetric, fully-connected network. We demonstrate that the EET efficiency can be significantly increased up to ≈100% by perturbing hopping transport between the initial node and the one connected directly to the sink, while the rate of energy transport is highest at a finite value of the hopping parameter. We also show that prohibiting hopping between the other nodes which are not directly linked to the sink does not improve the efficiency. We show that external dephasing noise in the network plays a constructive role for EET in the presence of localization in the network, while in the absence of localization it reduces the efficiency of EET. We also consider the influence of off-diagonal disorder in the hopping parameters of the network. 相似文献
68.
Rehan Zahid Masjuki Bin Haji Hassan Mahendra Varman Riaz Ahmad Mufti Md. Abul Kalam Nurin Wahidah Binti Mohd Zulkifli 《固体与材料科学评论》2017,42(4):267-294
Tribological efficiency of industrial applications involving boundary lubrication regime can be improved to an appreciable extent by the deposition of hard coatings on interacting surfaces. Among such coatings, diamond-like carbon (DLC) coatings are considered to be one of the most suitable ones for the said role. DLC coatings possess a unique combination of physical, chemical, and material properties due to which they can help in minimizing friction-induced energy and material losses even under starved lubrication conditions. Since commercial lubricants are optimized for steel surfaces, therefore, a lot of experimental investigations were carried out to analyze the tribological compatibility of these lubricants with various DLC coatings. However, there is still a lack of understanding about how DLC coatings interact with conventional lubricant additives. Some researchers reported tribologically beneficial interactions between DLC coatings and formulated lubricants while others observed no such behavior. To address these inconsistencies, there is a need to rearrange the published data in a more apprehensible and organized manner with a special emphasis on the mechanisms responsible for a particular tribological behavior. In this way, it can be determined whether synergistic or antagonistic correlation exists between a particular DLC-lubricant combination and research on DLC coatings can be continued in a logical way. In this article, most widely investigated non-doped DLC coatings (ta-C, a-C:H, a-C, and ta-C:H) are tribologically analyzed. Average values of friction and wear coefficients are calculated for various DLC-lubricant combinations using already published data and compared to quantify the effectiveness of a particular lubricant additive in enhancing tribological characteristics of symmetrical non-doped DLC contacts. Moreover, tribological performance parameters of non-doped DLC coatings are compared with those of doped-DLC coatings to understand differences in their tribological behavior in combination with additives. 相似文献
69.
Mahwish?Khan Taquwa?Aslam Hassan?ShahzadEmail author Hammad?Omer 《Applied magnetic resonance》2017,48(3):227-240
Conjugate gradient SENSE (CG-SENSE) is a parallel magnetic resonance imaging reconstruction algorithm which solves the inversion problem of SENSE iteratively. One major limitation of CG-SENSE is the appropriate choice of the number of iterations required for good reconstruction results. Fewer iterations result in aliasing artifacts and too many iterations result in an increased noise level. This paper proposes a novel method to define the stopping criterion of CG-SENSE algorithm which is based on the use of correlation measure between the line profiles of the reconstructed images in the current and the previous iterations. The results are compared with Bregman distance-stopping criterion. Artifact power and peak signal-to-noise ratio are used to quantify the quality of the reconstructed images. The results demonstrate that the line profile correlation measure acts as an effective stopping criterion in CG-SENSE. 相似文献
70.
Oussama Hijazi Sebastián Montiel Xiao Zhang 《Communications in Mathematical Physics》2001,221(2):255-265
Under standard local boundary conditions or certain global APS boundary conditions, we get lower bounds for the eigenvalues
of the Dirac operator on compact spin manifolds with boundary. For the local boundary conditions, limiting cases are characterized
by the existence of real Killing spinors and the minimality of the boundary.
Received: 22 August 2000 / Accepted: 15 March 2001 相似文献