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RISS 인기검색어
- 검색키워드
- 저자 : S. U. Rehman (검색결과 18 건)
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Rehman, S.U.,Choi, M.S.,Kim, I.S.,Kim, S.H.,Yoo, H.H. Pergamon Press ; Elsevier Science Pub. Co 2016 Journal of pharmaceutical and biomedical analysis Vol.129 No.-
Hederacoside C is a principal bioactive pharmaceutical ingredient of Hedera helix leaf extracts. H. helix extracts have long been used in folk medicine for the treatment of respiratory disorders. Currently, hederacoside C is investigated as a promising candidate for the treatment of respiratory diseases. In this study, an accurate, sensitive, rapid, and reliable bioanalytical method was developed for the determination of hederacoside C in rat plasma using ultra high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). For sample preparation, plasma proteins were precipitated with 0.1% acetic acid in acetonitrile. Waters UPLC BEH C<SUB>18</SUB> (2.1mm I.D.x100mm, 1.7μm) column was used for chromatographic separation. A gradient elution of mobile phases consisting of 0.02% acetic acid in distilled water (solvent A) and 0.02% acetic acid in acetonitrile (solvent B) was used at a flow rate of 0.3mL/min. The multiple reaction monitoring (MRM) mode was used for mass spectrometric detection; the MRM transitions were m/z 1219.7→m/z 469.2 for hederacoside C and m/z 1108.3→m/z 221.2 for ginsenoside Rb1 (internal standard) in the negative ionization mode. A calibration curve was constructed in the range of 10-1000ng/mL. The intra- and inter-day precision and accuracy were within 5%. The developed UPLC-MS/MS method was successfully applied in a pharmacokinetic study of hederacoside C in rats. Hederacoside C was quickly but inadequately absorbed from the gastrointestinal tract of rats resulting in extremely low bioavailability and relatively slow clearance.
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Common fixed point theorems for compatible and weakly compatible maps in fuzzy cone metric spaces
S. U. Rehman,S. Jabeen,F. Abbas,H. Ullah,I. Khan 원광대학교 기초자연과학연구소 2020 ANNALS OF FUZZY MATHEMATICS AND INFORMATICS Vol.19 No.1
In this paper, we present some common fixed theorems for compatible and weakly compatible four self-mappings in fuzzy cone metric spaces in which $h$ is a continuous self-map. We extend and improve some results given in the literature.
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Rehman, S.U.,Song, R.H.,Lee, J.W.,Lim, T.H.,Park, S.J.,Lee, S.B. Ceramurgica ; Elsevier Science Ltd 2016 Ceramics international Vol.42 No.10
Equal amounts of Gd<SUB>0.1</SUB>Ce<SUB>0.9</SUB>O<SUB>2-δ</SUB> (GDC) were added to La<SUB>0.65</SUB>Sr<SUB>0.3</SUB>MnO<SUB>3-δ</SUB>/(Y<SUB>2</SUB>O<SUB>3</SUB>)<SUB>0.08</SUB>(ZrO<SUB>2</SUB>)<SUB>0.92</SUB> (LSM/YSZ) powder either by physical mixing or by sol-gel process, to produce a porous cathode support for solid oxide fuel cells (SOFCs). The effect of the GDC mixing method was analyzed in view of sinterability, thermal expansion coefficient, microstructure, porosity, and electrical conductivity of the LSM/YSZ composite. GDC infiltrated LSM/YSZ (G-LY) composite showed a highly porous microstructure when compared with mechanically mixed LSM/YSZ (LY) and LSM/YSZ/GDC (LYG) composites. The cathode support composites were used to fabricate the button SOFCs by slurry coating of YSZ electrolyte and a nickel/YSZ anode functional layer, followed by co-firing at 1250<SUP>o</SUP>C. The G-LY composite cathode-supported SOFC showed maximum power densities of 215, 316, and 396mWcm<SUP>-2</SUP> at 750, 800, and 850<SUP>o</SUP>C, respectively, using dry hydrogen as fuel. Results showed that the GDC deposition by sol-gel process on LSM/YSZ powder before sintering is a promising technique for producing porous cathode support for the SOFCs.
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S. U. Rehman,A. Zeeshan,A. Majeed,M. B. Arain 한국자기학회 2017 Journal of Magnetics Vol.22 No.3
The target of the current study is to inspect theoretically two-dimensional boundary layer flow of a Maxwell ferromagnetic fluid toward a flat plate. An external magnetic field due to two equal line dipole which are equidistant from the wall and perpendicular to the flow plane is applied. Cattaneo-Christov heat flux model is utilized in modified form of Fourier’s Law to disclose the heat transfer characteristic. Governing flow problem is normalized into ordinary differential equation by adopting similarity transform procedure. The solution of resulting non-linear ODE’s are solved by shooting technique based on Runge-Kutta algorithm with the help of MATLAB. Characteristic of sundry parameter like magneto-thermomechanical (ferrohydrodynamic) interaction parameter, dimensionless thermal relaxation, Prandtl number and Debora number on velocity and temperature profile are displayed via graphs and in tabular form. It is also pointed out that temperature profile suppresses by varying values of the thermal relaxation time and Prandtl number and increasing behaviour is seen against ferrohydrodynamic interaction. Present numerical results are compared with those published previously in the literature for the case of Newtonian fluid (α₁ → 0) and found an excellent agreement.
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Rehman, S. U.,Shah, S. A.,Ali, T.,Chung, J. I.,Kim, M. O. HUMANA PRESS INC 2017 Molecular Neurobiology Vol.54 No.1
<P>Aging is a major factor involved in neurological impairments, decreased anti-oxidant activities, and enhanced neuroinflammation. D-galactose (D-gal) has been considered an artificial aging model which induces oxidative stress and inflammatory response resulting in memory and synaptic dysfunction. Dietary supplementation exerts valuable effects against oxidative stress and neuroinflammation. Polyphenolic flavonoids, such as anthocyanins, have been reported as an anti-inflammatory and anti-oxidant agents against various neurodegenerative diseases. Recently, our group reported anthocyanin neuroprotection of the developing rat brain against ethanol-induced oxidative stress and neurodegenaration and ethanol-induced neuronal apoptosis via GABA(B1) receptor intracellular signaling in prenatal rat hippocampus. Here, we examined the protective effect of anthocyanin neuroprotection against D-gal-induced oxidative and inflammatory response in the hippocampus and cortex regions and explore the potential mechanism of its action. Our results indicated that anthocyanins treatment significantly improved behavioral performance of D-gal-treated rats in Morris water maze and Y-maze tests. One of the potential mechanisms of this action was decreased expression of the receptor for advance glycation end product, reduced level of reactive oxygen species (ROS) and lipid peroxidation as well as markers of the Alzheimer's disease. Furthermore, the results also indicated that anthocyanins inhibited activated astrocytes and neuroinflammation via suppression of various inflammatory markers including p-NF- (K) B, inducible nitric oxide synthase (iNOS), and tumor necrosis factor-alpha (TNF-alpha) in the hippocampus and cortex regions of D-gal-treated rats brain. Moreover, anthocyanins abrogated neuroapoptosis via C-jun N-terminal kinase (p-JNK) suppression and improved deregulated synaptic proteins including synaptophysin, synaptosomal-associated protein (SNAP)-23, SNAP-25, and phosphorylated CREB. This data suggests that anthocyanins could be a safe and promising anti-oxidant and anti-neuroinflammatory agent for age-related neurodegenerative diseases such as Alzheimer's disease.</P>
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HPLC Determination of Bioactive Flavonoids in Hovenia dulcis Fruit Extracts
Park, J. S.,Kim, I. S.,Rehman, S. U.,Na, C. S.,Yoo, H. H. Oxford University Press 2016 Journal of Chromatographic Science Vol.54 No.2
<P>A simple, accurate and reproducible reversed-phase liquid chromatographic method was developed for qualitative and quantitative determination of four bioactive flavonoids (ampelopsin, taxifolin, myricetin and quercetin) from the fruit-stalk extract of Hovenia dulcis Thunb. Chromatographic separation was performed on a C18 column (4.6 x 150 mm, 3.5 mu m) with mobile phase consisting of 0.1% acetic acid and 100% acetonitrile at a flow rate of 1.0 mL/min. The analysis was performed using a diode array detector at 365 nm. The method was validated in terms of selectivity, linearity, accuracy, precision and recovery. Good linearity was observed over the investigated concentration range (10-500 mu g/mL), with correlation coefficient values greater than 0.99. The intra-and inter-day precisions over the concentration range were <3.91% (relative standard deviation), and the accuracy was between 91.57 and 106.66%. The mean recovery for all the analytes was 100.87%. This method was successfully applied in the quality assessment of bioactive flavonoids in the fruit-stalk extract of H. dulcis.</P>
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Rehman, Z. U.,Shin, S. H.,Hussain, I.,Koo, B. H. Springer Science + Business Media 2017 Protection of metals and physical chemistry of sur Vol.53 No.3
<P>Detail study of the PEO coatings produced on AZ31B magnesium alloy in Na2SiO3-K2ZrF6 based electrolyte solution was carried out in this work. ZrO2, MgF2, MgO and Mg2SiO4 were observed as the major phases in the coatings. Electrolytic decomposition and then the severe thermochemical environment provoked various Zr-F-Mg based complexes in the coatings. From the surface analysis, various structures e.g, nano-grains, pores and volcano shape sintered material were evidenced. Using Vicker hardness test, maximum hardness was recorded as similar to 1280 HV. Potentiodynamic polarization technique in 3.5 wt % NaCl solution was used to predict the corrosion performances of the specimens. Among the coated samples, highest corrosion resistance was recorded to be similar to 223.5 x 10(3) k Omega/cm(2) for 15 min coatings.</P>
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Ahmad, A.,Ali, T.,Park, H. Y.,Badshah, H.,Rehman, S. U.,Kim, M. O. HUMANA PRESS INC 2017 Molecular Neurobiology Vol.54 No.3
<P>Alzheimer's disease (AD) is a devastating and progressive neurodegenerative disease and is characterized pathologically by the accumulation of amyloid beta (A beta) and the hyperphosphorylation of tau proteins in the brain. The deposition of A beta aggregates triggers synaptic dysfunction, hyperphosphorylation of tau, and neurodegeneration, which lead to cognitive disorders. Here, we investigated the neuroprotective effect of fisetin in the A beta(1-42) mouse model of AD. Single intracerebroventricular injections of A beta(1-42) (3 mu l/5 min/mouse) markedly induced memory/synaptic deficits, neuroinflammation, and neurodegeneration. Intraperitoneal injections of fisetin at a dose of 20 mg/kg/day for 2 weeks starting 24 h after A beta(1-42) injection significantly decreased the A beta(1-42)-induced accumulation of A beta, BACE-1 expression, and hyperphosphorylation of tau protein at serine 413. Fisetin treatment also markedly reversed A beta(1-42)-induced synaptic dysfunction by increasing the levels of both presynaptic (SYN and SNAP-25) and postsynaptic proteins (PSD-95, SNAP-23, p-GluR1 (Ser 845), p-CREB (Ser 133) and p-CAMKII (Thr 286) and ultimately improved mouse memory, as observed in the Morris water maze test. Fisetin significantly activated p-PI3K, p-Akt (Ser 473), and p-GSK3 beta (Ser 9) expression in A beta(1-42)-treated mice. Moreover, fisetin prevented neuroinflammation by suppressing various activated neuroinflammatory mediators and gliosis; it also suppressed the apoptotic neurodegeneration triggered by A beta(1-42) injections in the mouse hippocampus. Fluorojade-B and immunohistochemical staining for caspase-3 revealed that fisetin prevented neurodegeneration in A beta(1-42)-treated mice. Our results suggest that fisetin has a potent neuroprotective effect against A beta(1-42)-induced neurotoxicity. These results demonstrate that polyphenolic flavonoids such as fisetin could be a beneficial, effective and safe neuroprotective agent for preventing neurological disorders such as AD.</P>
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