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排序方式: 共有467条查询结果,搜索用时 31 毫秒
161.
Ullah H. Davoudi B. Mariampillai A. Hussain G. Ikram M. Vitkin I. A. 《Laser Physics》2012,22(4):797-804
The increase of glucose levels in blood changes the viscosity of flowing fluids and shape of the erythrocytes. Both of these
can affect the details of light scattering as can be quantified via decorrelation times measured by optical coherence tomography
(OCT). The relative contributions of these competing effects have been studied by examining the motion dynamics of deformable
asymmetrical (red blood cells, RBCs with ∼7 μm diameter and ∼2 μm thickness) and non deformable symmetrical (polystyrene microspheres,
PSM with 1.4 μm diameter) flowing scattering particles. The fluid flow under the action of gravity was modulated by changing
the glucose concentrations. Quantitative analysis of the OCT’s M-mode autocorrelation functions enabled the derivations of
the translational diffusion coefficients. These systematic studies are aimed at eventual tissue imaging scenarios with speckle-variance
OCT to obtain local glucose concentrations maps. 相似文献
162.
Muhammad Haneef Suneela Arif Jehan Akbar Nasrullah Shah Muhammad Zahir Aneela Shamim Hameed Ullah 《理论物理通讯》2013,59(3):356-360
We report the combined effects of laser polarization and curvature of the spherical surface on the detached electron spectra from H-.The Theoretical imaging method is used as a tool of investigation.The photodetachment cross sections for various polarization angles,radii of curvatures and inter ion surface distances are displayed.The analysis of the spectra reveals that the laser polarization angle θL,curvature of the surface rc and inter ion surface distance d strongly affect oscillations in the spectra.Therefore,a fine control on the laser polarization and that of curvature in the surface can be used to control oscillations in the photodetachment of negative ions. 相似文献
163.
Heejeong Choi Il Young Ryu Inkyu Choi Sultan Ullah Hee Jin Jung Yujin Park Yeongmu Jeong YeJi Hwang Sojeong Hong In-Soo Yoon Hwayoung Yun Min-Soo Kim Jin-Wook Yoo Yunjin Jung Pusoon Chun Hyung Ryong Moon 《Molecules (Basel, Switzerland)》2021,26(16)
To confirm that the β-phenyl-α,β-unsaturated thiocarbonyl (PUSTC) scaffold, similar to the β-phenyl-α,β-unsaturated carbonyl (PUSC) scaffold, acts as a core inhibitory structure for tyrosinase, twelve (Z)-5-(substituted benzylidene)-4-thioxothiazolidin-2-one ((Z)-BTTZ) derivatives were designed and synthesized. Seven of the twelve derivatives showed stronger inhibitory activity than kojic acid against mushroom tyrosinase. Compound 2b (IC50 = 0.47 ± 0.97 µM) exerted a 141-fold higher inhibitory potency than kojic acid. Kinetic studies’ results confirmed that compounds 2b and 2f are competitive tyrosinase inhibitors, which was supported by high binding affinities with the active site of tyrosinase by docking simulation. Docking results using a human tyrosinase homology model indicated that 2b and 2f might potently inhibit human tyrosinase. In vitro assays of 2b and 2f were conducted using B16F10 melanoma cells. Compounds 2b and 2f significantly and concentration-dependently inhibited intracellular melanin contents, and the anti-melanogenic effects of 2b at 10 µM and 2f at 25 µM were considerably greater than the inhibitory effect of kojic acid at 25 µM. Compounds 2b and 2f similarly inhibited cellular tyrosinase activity and melanin contents, indicating that the anti-melanogenic effects of both were due to tyrosinase inhibition. A strong binding affinity with the active site of tyrosinase and potent inhibitions of mushroom tyrosinase, cellular tyrosinase activity, and melanin generation in B16F10 cells indicates the PUSTC scaffold offers an attractive platform for the development of novel tyrosinase inhibitors. 相似文献
164.
Khan KM Ullah Z Lodhi MA Ali M Choudhary MI Rahman AU Haq ZU 《Molecular diversity》2006,10(2):223-231
By using internal combinatorial library we were able to identify (4R)-thiazolidines carboxylic acid and its 2-substituted analogs as active inhibitors of urease. Molecular modeling and virtual
screening were utilized to find out potential compounds. Computational techniques were employed at database of 90,000 ligands
and selected the structure representing the low energy conformations, Grid and FlexX docking algorithms were used and the
top binding ligands were synthesized and screened in wet-lab. 相似文献
165.
A rapid, high resolution, and low sample consumption CZE method is developed for peptide nucleic acid (PNA) analysis for the first time. 30% v/v acetonitrile in PNA sample and 20% v/v acetonitrile in 50 mM borax‐boric acid (pH 8.7) as BGE were employed after optimization. The calibration curves were linear for PNA concentration ranging from 1 to 50 μmol/L. LOD and LOQ of PNA were 0.2 and 1.0 μmol/L, respectively. Since the commercially available reagent gives rise to huge PNA peak and an apparent impurity peak, the purity of PNA was evaluated to be about 81.4% by CZE method, obviously lower than the supplier's purity value of 99.9% evaluated by RP–HPLC, and also lower than 94.8% determined with RP–HPLC by our research group. The CZE method takes only 5 min, needs only 90 nL PNA, much less than 20 min and 20 μL PNA in RP–HPLC method. Moreover, the CZE method is applicable for the analysis of glutamic acid modified and lysine modified PNAs, they show different migration time with their corresponding complementary PNAs. Our results show CZE provides a new choice for PNA and modified PNA analysis, also their purity or quality evaluation. 相似文献
166.
Kamran Ullah 《Physics letters. A》2019,383(25):3074-3079
We provide a theoretical technique to study the occurrence of multistability and normal mode splitting in an optomechanical system driven by a single mode cavity field. For this purpose, we consider the position-dependent mass mechanical resonator (PDMR) which produces the nonlinearity in the system. This shifts the system from monostable to bistable regime and bistable to a multistable regime at different conditions of the nonlinearity. Further, we use the Fourier transform technique to find out the fluctuation in the position of the nano-mechanical resonator and their energy spectrum as well. Moreover, we used the input-output theory to analyze the transmitted field spectrum as well as x and y quadratures spectra of the output field. We explain the effect of the non-linearity on the normal mode splitting of the former and later spectra. In addition, we also explain the normal mode splitting as a function of cavity decay rate and laser power, respectively. 相似文献
167.
Wasiq Ali Yaan Li Muhammad Asif Zahoor Raja Wasim Ullah Khan Yigang He 《Entropy (Basel, Switzerland)》2021,23(9)
In this study, an application of deep learning-based neural computing is proposed for efficient real-time state estimation of the Markov chain underwater maneuvering object. The designed intelligent strategy is exploiting the strength of nonlinear autoregressive with an exogenous input (NARX) network model, which has the capability for estimating the dynamics of the systems that follow the discrete-time Markov chain. Nonlinear Bayesian filtering techniques are often applied for underwater maneuvering state estimation applications by following state-space methodology. The robustness and precision of NARX neural network are efficiently investigated for accurate state prediction of the passive Markov chain highly maneuvering underwater target. A continuous coordinated turning trajectory of an underwater maneuvering object is modeled for analyzing the performance of the neural computing paradigm. State estimation modeling is developed in the context of bearings only tracking technology in which the efficiency of the NARX neural network is investigated for ideal and complex ocean environments. Real-time position and velocity of maneuvering object are computed for five different cases by varying standard deviations of white Gaussian measured noise. Sufficient Monte Carlo simulation results validate the competence of NARX neural computing over conventional generalized pseudo-Bayesian filtering algorithms like an interacting multiple model extended Kalman filter and an interacting multiple model unscented Kalman filter. 相似文献
168.
Madeeha Aslam Fozia Fozia Anadil Gul Ijaz Ahmad Riaz Ullah Ahmed Bari Ramzi A. Mothana Hidayat Hussain 《Molecules (Basel, Switzerland)》2021,26(20)
Green synthesis of silver nanoparticles (AgNPs) employing an aqueous plant extract has emerged as a viable eco-friendly method. The aim of the study was to synthesize AgNPs by using plant extract of Sanvitalia procumbens (creeping zinnia) in which the phytochemicals present in plant extract act as a stabilizing and reducing agent. For the stability of the synthesized AgNPs, different parameters like AgNO3 concentration, volume ratios of AgNO3, temperature, pH, and contact time were studied. Further, AgNPs were characterized by UV–visible spectroscopy, FT-IR (Fourier Transform Infrared Spectroscopy), XRD (X-ray Diffraction), SEM (Scanning Electron Microscopy), and EDX (Energy Dispersive X-ray Spectrometer) analysis. FT-IR analysis showed that the plant extract contained essential functional groups like O–H stretching of carboxylic acid, N–H stretching of secondary amides, and C–N stretching of aromatic amines, and C–O indicates the vibration of alcohol, ester, and carboxylic acid that facilitated in the green synthesis of AgNPs. The crystalline nature of synthesized AgNPs was confirmed by XRD, while the elemental composition of AgNPs was detected by energy dispersive X-ray analysis (EDX). SEM studies showed the mean particle diameter of silver nanoparticles. The synthesized AgNPs were used for photocatalytic degradation of Orange G and Direct blue-15 (OG and DB-15), which were analyzed by UV-visible spectroscopy. Maximum degradation percentage of OG and DB-15 azo dyes was observed, without any significant silver leaching, thereby signifying notable photocatalytic properties of AgNPs. 相似文献
169.
Gunawan Witjaksono Muhammad Junaid Mohd Haris Khir Zaka Ullah Nelson Tansu Mohamed Shuaib Bin Mohamed Saheed Muhammad Aadil Siddiqui Saeed S. Ba-Hashwan Abdullah Saleh Algamili Saeed Ahmed Magsi Muhammad Zubair Aslam Rab Nawaz 《Molecules (Basel, Switzerland)》2021,26(21)
Graphene as a material for optoelectronic design applications has been significantly restricted owing to zero bandgap and non-compatible handling procedures compared with regular microelectronic ones. In this work, nitrogen-doped reduced graphene oxide (N-rGO) with tunable optical bandgap and enhanced electrical conductivity was synthesized via a microwave-assisted hydrothermal method. The properties of the synthesized N-rGO were determined using XPS, FTIR and Raman spectroscopy, UV/vis, as well as FESEM techniques. The UV/vis spectroscopic analysis confirmed the narrowness of the optical bandgap from 3.4 to 3.1, 2.5, and 2.2 eV in N-rGO samples, where N-rGO samples were synthesized with a nitrogen doping concentration of 2.80, 4.53, and 5.51 at.%. Besides, an enhanced n-type electrical conductivity in N-rGO was observed in Hall effect measurement. The observed tunable optoelectrical characteristics of N-rGO make it a suitable material for developing future optoelectronic devices at the nanoscale. 相似文献
170.
Ibrahim El-Tantawy El Sayed Sami Ullah Omar A. Al-Hartomy Asmaa Mohammed Hasanein Abdullah A. S. Ahmed Khaled A. Kahilo Mehrez E. El-Naggar 《Molecules (Basel, Switzerland)》2022,27(3)
The naturally occurring neocryptolepine (5-Methylindolo [2,3-b]quinoline) and its analogs exhibited prominent anticancer and antimalarial activity. However, the main problem of this class of compounds is their poor aqueous solubility, hampering their bioavailability and preventing their clinical development. To overcome the problem of insolubility and to improve the physicochemical and the pharmacological properties of 5-Methylindolo [2,3-b]quinoline compounds, this work was designed to encapsulate such efficient medical compounds into mesoporous silica oxide nanoemulsion (SiO2NPs). Thus, in this study, SiO2NPs was loaded with three different concentrations (0.2 g, 0.3, and 0.6 g) of 7b (denoted as NPA). The findings illustrated that the nanoparticles were formed with a spherical shape and exhibited small size (less than 500 nm) using a high concentration of the synthesized chemical compound (NPA, 0.6 g) and good stabilization against agglomeration (more than −30 mv). In addition, NPA-loaded SiO2NPs had no phase separation as observed by our naked eyes even after 30 days. The findings also revealed that the fabricated SiO2NPs could sustain the release of NPA at two different pH levels, 4.5 and 7.4. Additionally, the cell viability of the produced nanoemulsion system loaded with different concentrations of NPA was greater than SiO2NPs without loading, affirming that NPA had a positive impact on increasing the safety and cell viability of the whole nanoemulsion. Based on these obtained promising data, it can be considered that the prepared NPA-loaded SiO2NPs seem to have the potential for use as an effective anticancer drug nanosystem. 相似文献