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121.
Cheong KW Leow TC Rahman RN Basri M Rahman MB Salleh AB;Enzyme Microbial Technology Research Group 《Applied biochemistry and biotechnology》2011,164(3):362-375
A thermostable lipase from Geobacillus zalihae strain T1 was chemically modified using propionaldehyde via reductive alkylation. The targeted alkylation sites were lysines,
in which T1 lipase possessed 11 residues. Far-UV circular dichroism (CD) spectra of both native and alkylated enzyme showed
a similar broad minimum between 208 and 222 nm, thus suggesting a substantial amount of secondary structures in modified enzyme,
as compared with the corresponding native enzyme. The hydrolytic activity of the modified enzymes dropped drastically by nearly
15-fold upon chemical modification, despite both the native and modified form showed distinctive α-helical bands at 208 and
222 nm in CD spectra, leading us to the hypothesis of formation of a molten globule (MG)-like structure. As cooperative unfolding
transitions were observed, the modified lipase was distinguished from the native state, in which the former possessed a denaturation
temperature (T
m) in lower temperature range at 61 °C while the latter at 68 °C. This was further supported by 8-anilino-1-naphthalenesulfonic
acid (ANS) probed fluorescence which indicated higher exposure of hydrophobic residues, consequential of chemical modification.
Based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis, a small number
of lysine residues were confirmed to be alkylated. 相似文献
122.
El-Wahab AH Al-Fifi ZI Bedair AH Ali FM Halawa AH El-Agrody AM 《Molecules (Basel, Switzerland)》2011,16(1):307-318
Vilsmeier formylation of 2-(1-phenylhydrazonoethyl)naphtho[2,1-b]furan (2) gave 3-naphtho[2,1-b]furan-2-yl-1-phenyl-1H-pyrazole-4-carbaldehyde (3), which was reacted with C- and N-nucleophiles to afford naphthofuranpyrazol derivatives 4-8. Treatment of 2-[(3-(naphtho[2,1-b]furan-2-yl)-1-phenyl-1H-pyrazol-4-yl)methylene]-malononitrile (4a) with reactants having active hydrogen and Et?N gave the corresponding pyrazoline, pyran and chromene addition product derivatives 10, 12 and 13, consisting of three different connected heterocyclic moieties. Reaction of 1-((3-(naphtho[2,1-b]furan-2-yl)-1-phenyl-1H-pyrazol-4-yl) methylene)-2-phenylhydrazone (6b) with AcONa and ethyl bromoacetate or chloroacetone afforded the thiazolidinone and methylthiazole derivatives 14 and 15, respectively. In addition, intramolecular cyclization of 6d with Ac?O afford the corresponding 1,3,4-thiadiazol-2-yl acetamide derivative 16. The structures of the synthesized compounds were confirmed by IR, 1H-NMR/13C-NMR and mass spectral studies. Compound 14 showed promising effects against the tested Gram positive and negative bacteria and fungi. 相似文献
123.
The present paper investigates phenomena brought about into the classic peristaltic mechanism by inclusion of non-Newtonian effects through a porous space in a channel. The peristaltic motion of a second-order fluid through a porous medium was studied for the case of a planar channel with harmonically undulating extensible walls. The system of the governing nonlinear PDE is solved by using the perturbation method to second-order in dimensionless wavenumber. The analytic solution has been obtained in the form of a stream function from which the axial pressure gradient has been derived. The flow is investigated in a wave frame of reference moving with velocity of the wave. Numerical calculations are carried out for the pressure rise and frictional force. The features of the flow characteristics are analyzed by plotting graphs and discussed in detail. 相似文献
124.
Abd El-Moneim Anwar Mohamed Mohamed Abd El-Hady Kassem Mohamed Abd Allah El-Hadidy 《Applied Mathematical Modelling》2011,35(9):4127-4139
This paper investigates a search problem for a brownian target motion on one of n-intersected real lines in which any information of the target position is not available to the searchers all the time. We have n-searchers start searching for the target from the origin that is the intersection point of these lines. Each of the searchers moves continuously along his line in both directions of the starting point. The purpose of this paper is to formulate a search model and find the condition under which the expected value of the first meeting time between one of the searchers and the target is finite. Also, we show the existence of the optimal search plan which minimizes the expected value of the first meeting time and find it. 相似文献
125.
Saleh MI Kusrini E Mohd Sarjidan MA Abd Majid WH 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,78(1):52-58
A mononuclear of [Eu(NO3)(Pic)(H2O)2(EO3)](Pic)·(0.73)H2O complex, where EO3=trietraethylene glycol and Pic=picrate anion, shows a red emission when used as an active layer in a single layer of ITO/EO3-Eu-Pic/Al configuration. The crystal structure of the complex consists of [Eu(NO3)(Pic)(H2O)2(EO3)]+ cation and [Pic]- anion. The Eu(III) ion is coordinated to the 10 oxygen atoms from one EO3 ligand, one Pic anion, one nitrate anion, and two water molecules. The complex is crystallized in triclinic with space group P-1. The hybrids in thin films I and II were prepared in the respective order solution concentrations of 15 and 20 mg/mL the emissive center. Comparing the photoluminescence (PL) and electroluminescence (EL) spectra, we can find that all emissions come from the characteristic transitions of the Eu(III) ion. The EL spectra of both thin films showed the occurrence of the most intense red-light emission around at 612 nm. Comparison of organic light-emitting device (OLED) current intensity characteristics as a function of voltage (I-V) show that the thin film I is better than those found for the thin film II. The thickness of the emitting layer is an important factor to control the current-voltage curve. The sharp and intense emission of the complex at low voltage indicates that the complex is a suitable and promising candidate for red-emitting materials. 相似文献
126.
Abdelhalim B. Mahmoud Shereen Abd Algaffar Wendy van de Sande Sami Khalid Marcel Kaiser Pascal Mser 《Molecules (Basel, Switzerland)》2021,26(13)
Redox-active drugs are the mainstay of parasite chemotherapy. To assess their repurposing potential for eumycetoma, we have tested a set of nitroheterocycles and peroxides in vitro against two isolates of Madurella mycetomatis, the main causative agent of eumycetoma in Sudan. All the tested compounds were inactive except for niclosamide, which had minimal inhibitory concentrations of around 1 µg/mL. Further tests with niclosamide and niclosamide ethanolamine demonstrated in vitro activity not only against M. mycetomatis but also against Actinomadura spp., causative agents of actinomycetoma, with minimal inhibitory concentrations below 1 µg/mL. The experimental compound MMV665807, a related salicylanilide without a nitro group, was as active as niclosamide, indicating that the antimycetomal action of niclosamide is independent of its redox chemistry (which is in agreement with the complete lack of activity in all other nitroheterocyclic drugs tested). Based on these results, we propose to further evaluate the salicylanilides, niclosamide in particular, as drug repurposing candidates for mycetoma. 相似文献
127.
Abstract The interaction of iodine with donor bases such as neutral red (NR) and 1, 10 -phenanthroline (Ph) have been studied spectrophotometrically in C2H5OH. The results indicate the formation of 2:3 charge transfer complexes of the type (base)23I2. Mass, Raman and 1H NMR spectra have been recorded for each complex. I3 ? and I2 species are observed in these complexes. In addition, the d.c. conductivity is measured in the range (300–400) K°. The energy gap of the ionic conduction has been calculated. The conduction process is thought to involve iodide transfer between polyanions. 相似文献
128.
A. T. Naveed M. Q. Huda K. F. Abd El-Rahman J. Hartung J. H. Evans-Freeman A. R. Peaker D. C. Houghton C. Jeynes W. P. Gillin 《Journal of luminescence》1998,80(1-4):381-386
Strained Si1−xGex/Si quantum wells have been doped with erbium by implantation. A comparison is made with strained Si1−xGex/Si quantum wells and relaxed Si1−xGex, with x between 10% and 25%, doped with erbium during MBE growth. The erbium concentration was between 1×1018 and 5×1018 cm−3 throughout the active regions. Transmission electron microscopy, X-ray diffraction, and photoluminescence studies indicate that good regrowth can been achieved after full amorphisation by implantation of the strained quantum wells. The erbium luminescence is more intense in the Si1−xGex/Si layers, but erbium-implanted samples containing Si1−xGex exhibit defect luminescence in the region of 0.9–1.0 eV. These defects are also present when Si1−xGex/Si quantum wells are implanted with an amorphising dose of silicon, and then regrown. They are attributed to small germanium-rich platelets, rather than to erbium-related defects. Electroluminescence is presented from a forward biased erbium-implanted Si0.87Ge0.13/Si structure at a drive current density of only 1.8 mA/cm2. 相似文献
129.
The hydrogen-vacancy interaction in W and Mo was investigated by applying the perturbed angular correlation technique, using the isotope111In as a probe. Hydrogen trapping at InV2 manifests itself as a change of the vacancy-induced quadrupole frequency. We have observed trapping of up to two H atoms. The binding energies for the first H atom are 1.07(2) eV in Mo and 1.16(2) eV in W. These results are close to the values calculated with the effective-medium theory. The frequency shifts are both negative and amount to a few Mrad/s per trapped H atom. Contrary to the theoretical predictions, the binding energies for the second H atom differ strongly: 0.44(3) eV in Mo and 0.99(2) eV in W. The corresponding frequency shifts have opposite signs. Therefore, the lattice positions of the first H atom in Mo and W are similar, while those of the second H atom must be completely different. 相似文献
130.
The Publishers W.H. Abd. Majid 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(4):575
In spite of the precautions taken to check the originality of the articles,
it happens, unfortunately that our scientific colleagues' vigilance is sometimes caught up unprepared.
Today, it has come to our attention that
the following article results from a plagiarism.
We apologize to the authors who suffered from it.
You will
find hereafter a note written by Dr Majid which summarizes the situation. 相似文献