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1.
Mohaimed I. Al-Hassan 《合成通讯》2013,43(3):353-356
It was found that diphenylacetylene reacts at 55[ddot]C with i-Bu2AlH to form cis-vinylalane. On the other hand, i-Bu2AlH adds mostly in anti-manner to diphenylacetylene at 110[ddot] C. 相似文献
2.
Taha ZA Ajlouni AM Al-Hassan KA Hijazi AK Faiq AB 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,81(1):317-323
Eight new lanthanide metal complexes [LnL(NO(3))(2)]NO(3) {Ln(III) = Nd, Dy, Sm, Pr, Gd, Tb, La and Er, L = bis-(salicyladehyde)-1,3-propylenediimine Schiff base ligand} were prepared. These complexes were characterized by elemental analysis, thermogravimetric analysis (TGA), molar conductivity measurements and spectral studies ((1)H NMR, FT-IR, UV-vis, and luminescence). The Schiff base ligand coordinates to Ln(III) ion in a tetra-dentate manner through the phenolic oxygen and azomethine nitrogen atoms. The coordination number of eight is achieved by involving two bi-dentate nitrate groups in the coordination sphere. Sm, Tb and Dy complexes exhibit the characteristic luminescence emissions of the central metal ions attributed to efficient energy transfer from the ligand to the metal center. Most of the complexes exhibit antibacterial activity against a number of pathogenic bacteria. 相似文献
3.
DETECTION OF DNA-PSORALEN PHOTOADDUCTS in situ 总被引:1,自引:0,他引:1
ZOFIA ZAREBSKA† MARIA JARZABEK-CHORZELSKA ‡ GENOWEFA RZSA WIESLAW GLISKI MARIA PAWIKA TADEUSZ CHORZELSKI STEFANIA JABLOKA 《Photochemistry and photobiology》1984,39(3):307-312
Abstract— An immunological method, with the use of specific immune serum, has been developed for detection of 8-methoxypsoralen (8-MOP) photoadducts to DNA, formed in situ in cell nuclei, after combined treatment with 8MOP and UV-A irradiation (Zarçbska et al. , 1978). Lymphocytes fixed on slides or in suspension, and cryostat sections of different mammalian tissues, served as antigenic substrate, after treatment with 8-MOP and UV-A in vitro. Specific fluorescence in these substrates was detected in the nuclei after treatment with 30 ˜ 140 kJ/m2 UV-A in the presence of 0.1-0.3 μg/cm2 8-MOP. PHA-stimulated-lymphocytes appeared to be the most sensitive substrate.
However, hairless mice treated with high doses of UV-A in vivo , 70 ˜ 360 kJ/m2 did not reveal a specific fluorescence of epidermal nuclei, unless a high local concentration of 8-MOP was attained.
The apparent discrepancy in the level of photoadduct detection between the in vitro and in vivo treated specimens was explained by the low number of DNA-8-MOP-photoadducts formed in vivo under these experimental conditions. The relevance of these findings to the role of DNA-8-MOP-photoadducts formed during PUVA photochemotherapy is discussed. 相似文献
However, hairless mice treated with high doses of UV-A in vivo , 70 ˜ 360 kJ/m
The apparent discrepancy in the level of photoadduct detection between the in vitro and in vivo treated specimens was explained by the low number of DNA-8-MOP-photoadducts formed in vivo under these experimental conditions. The relevance of these findings to the role of DNA-8-MOP-photoadducts formed during PUVA photochemotherapy is discussed. 相似文献
4.
5.
ABSTRACT. Let G be the group ?[t, t ?1] x ?. By studying the action of the braid group Bn on the set Gn , we obtain representations of Bn into a wreath product of the symmetric group and the general linear group over ?[t, t ?1]. This in particular recovers the Burau representation of the braid group. Furthermore, some quotients of the braid group are obtained by using the representations found. 相似文献
6.
Khader A. Al-Hassan 《Journal of fluorescence》2013,23(6):1197-1206
An evidence is introduced through the b- and the twisted intramolecular charge transfer (TICT) fluorescence of ethyl-4-(N,N-dimethylamino)benzoate (EDMAB) and ethyl-4-(N,N-diethylamino)benzoate (EDEAB), confirming the role of donor size on the formation and emission of various inclusion complexes formed between these probes and α-CD in aqueous solution. A large variation in the b-fluorescence band of EDEAB as compared to that of EDMAB and a large variation in the TICT-fluorescence band of EDMAB as compared to that EDEAB, as the concentration of α-CD is increased in their aqueous solutions are observed. These variations are supported by time resolved fluorescence (TRF) spectra, fluorescence decay lifetimes and red edge effect (REE) results. 相似文献
7.
We examine the relative efficiencies of three- algorithms for performing Brownian Dynamics simulations without many-body hydrodynamics. We compare the conventional Brownian Dynamics algorithm of Ermak (CBD), Smart Monte Carlo (SMC) which incorporates Boltzmann sampling into essentially a CBD procedure, and the Stochastic Runge Kutta (SRK) method. We show, using the repulsive potential φ(r) = ε(σ/r) n , where n = 36 and 72, that the SRK algorithm gives the most accurate short-time dynamics for the mean-square displacements. The SRK algorithm static and dynamical properties converge better with a reducing time step to the exact values, than those generated by the CBD algorithm; giving efficiency gains typically of a factor of 3–4. Both CBD and SMC have the incorrect sign for the first correction term to the mean square displacement in a time step, whereas the SRK algorithm gives essentially the exact solution to order Δt 2, where Δt is the simulation time step. In fact, these correction terms are almost equal and opposite in sign. Expressions for these terms were derived in terms of the average interaction energy per particle. The force, shear and bulk stress autocorrelation functions were calculated. The average energy per particle and time correlation functions at short time have values in excess of the exact values, while the corresponding quantities for SRK are below this. This difference in behaviour can be traced back to the extent of compliance of the particle trajectories with the exact expansion of the Smoluchowski equation. The accuracy, at a given value of the time step, of the stochastic algorithms can significantly depend on the form of the interaction potential between particles. It is also demonstrated that the long time limits of various correlation functions are fairly insensitive to a particular scheme (SRK or CBD) used in the simulations. All the correlation functions have a stretched exponential region at intermediate to long times, and the values of the exponents on density and force law steepness have been determined. 相似文献
8.
It is shown that the relative intensity of the twisted intramolecular charge transfer (TICT) band of ester and benzonitrile
derivatives of dialkylaniline in polymethylmethacrylate polymer matrices of different molecular weights (MW) to increase with
increasing MW of the polymer. Our results emphasis the role of local free volumes (mobility in the matrix cage) and focus
attention on the role of the MW of the polymer on the fluorescence of various TICT probes. These observations are confirmed
by the red edge effect and fluorescence decay results. 相似文献
9.
V. Ivanova J. Hristov E. Dobreva Z. Al-Hassan I. Penchev 《Applied biochemistry and biotechnology》1996,59(2):187-198
This paper is focused on the possibility to apply the magnetic stabilization technique in bioprocessing. The feasibility of
a continuous ethanol fermentation process with immobilizedSaccharomyces cerevisiae cells in a magnetically stabilized bed (MSB) was demonstrated. The fermentation processes were carried out in an external
magnetic field, transverse to the fluid flow. The flexibility to change the bed expansion owing to the independent change
of the fluid flow and the field intensity (the “magnetization FIRST” mode) permitted the creation of fixed beds with different
particle arrangements, which affected the bed porosity, the effective fluid-particle contact area, and the mass transfer processes
on the particle-fluid interface. As a result, higher ethanol concentration, ethanol production, and glucose uptake rates than
in conventional packed bed reactor were reached. 相似文献
10.
Supporting maintenance strategies using Markov models 总被引:1,自引:0,他引:1
Al-Hassan K.; Swailes D. C.; Chan J. F. L.; Metcalfe A. V. 《IMA Journal of Management Mathematics》2002,13(1):17-27
The basic principle of total productive maintenance (TPM) isto reduce and ultimately eliminate breakdowns by pre-emptivemaintenance strategies, which rely on the cooperation of allemployees. When properly applied, TPM can bring about tremendousimprovements in a company's performance. However, recent research,using interviews and questionnaires, suggests that many managersin manufacturing industries in Europe still have to be convincedof the usefulness of TPM. Many more are perhaps unsure of thelosses which can accrue as a consequence of not having an appropriatemaintenance programme implemented in their organizations. Asimple yet powerful Markov model is proposed as a diagnostictool for the manager who wants an effective way of identifyingthe prime costs involved in production line downtimes, and hencethe potential benefits of TPM. The influence of the performanceof a single machine on a line can be investigated. This is vitalinformation for strategic planning of machine replacements,which involve major capital investments. In particular, an approximateanalysis of the benefits of a machine building up a buffer stockis presented, and assessed against the costs involved. The modelhas been implemented as an Excel macro. 相似文献