Lipoxygenase Inhibitory Constituents from Indigofera oblongifolia

Sharif, Ahsan,Ahmed, Ejaz,Malik, Abdul,Riaz, Naheed,Afza, Nighat,Nawaz, Sarfraz Ahmad,Arshad, Muhammad,Shah, Muhammad Raza,Chaudhary, Muhammad Iqbal The Pharmaceutical Society of Korea 2005 Archives of Pharmacal Research Vol.28 No.7

Indigin, alkylated xanthene (1) and indigoferic acid (2) have been isolated from the chloroform soluble fraction of Indigofera oblongifolia, along with $\beta$-sitosterol (3) and 3-hydroxybenzoic acid (4), which are reported for the first time from this species. Their structures were determined through spectroscopic techniques. Both the new compounds 1 and 2 showed significant activity against enzyme lipoxygenase, while 2 further showed moderate inhibition against BChE.

THE INFLUENCE OF OXYGEN-CONTAINING FUNCTIONAL GROUPS ON THE SURFACE BEHAVIOR AND ROUGHNESS CHARACTERISTICS OF GRAPHENE OXIDE

AHMAD ALLAHBAKHSH,FARHAD SHARIF,SAEEDEH MAZINANI 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.4

The effects of oxygen-containing functional groups on the surface roughness of graphene oxide are thoroughly studied using three-dimensional atomic force microscopy images, ball-and-stick model and wire-frame view results. Moreover, X-ray diffraction method and Fourier transform infrared spectroscopy are employed for characterizing the structural and chemical behavior of graphene oxide, respectively. Graphene oxide sheets show a clear concavity on one side when the aggregation of functional groups increased on the other side. This behavior could be the main reason for the surface fluctuation of graphene oxide sheets that is observed in microscopic images. In addition, the individual graphene oxide sheet presents greater values of mean roughness compared to multilayered sheets.

Theoretical fabrication of Williamson nanoliquid over a stretchable surface

Sharif, Humaira,Hussain, Muzamal,Khadimallah, Mohamed Amine,Ayed, Hamdi,Taj, Muhammad,Bhutto, Javed Khan,Mahmoud, S.R.,Iqbal, Zafer,Ahmad, Shabbir,Tounsi, Abdelouahed Techno-Press 2022 Advances in concrete construction Vol.14 No.2

On the basis of fabrication, the utilization of nano material in numerous industrial and technological system, obtained the utmost significance in current decade. Therefore, the current investigation presents a theoretical disposition regarding the flow of electric conducting Williamson nanoliquid over a stretchable surface in the presence of the motile microorganism. The impact of thermal radiation and magnetic parameter are incorporated in the energy equation. The concentration field is modified by adding the influence of chemical reaction. Moreover, the splendid features of nanofluid are displayed by utilizing the thermophoresis and Brownian motion aspects. Compatible similarity transformation is imposed on the equations governing the problem to derive the dimensionless ordinary differential equations. The Homotopy analysis method has been implemented to find the analytic solution of the obtained differential equations. The implications of specific parameters on profiles of velocity, temperature, concentration and motile microorganism density are investigated graphically. Moreover, coefficient of skin friction, Nusselt number, Sherwood number and density of motile number are clarified in tabular forms. It is revealed that thermal radiation, thermophoresis and Brownian motion parameters are very effective for improvement of heat transfer. The reported investigation can be used in improving the heat transfer appliances and systems of solar energy.

Five-Dimensional Perfect Fluid Collapse with the Cosmological Constant

Muhammad Sharif,Zahid Ahmad 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.4

This paper is devoted to the study of a five-dimensional spherically symmetric perfect fluid collapse with a positive cosmological constant. We take a five-dimensional spherically symmetric metric in the interior region and a five-dimensional Schwarzschild-de Sitter metric in the exterior region. The junction conditions between the interior and the exterior spacetimes are derived. By assuming that the energy density and the pressure satisfy the weak energy condition, we discuss the solution for the interior spacetime with a perfect fluid for both the marginally bound and the non-marginally bound cases. We investigate the apparent horizons and their physical significance and conclude that the cosmological constant slows down the collapse of matter and, hence, limits the size of the black hole. This analysis generalizes four-dimensional perfect fluid collapse. The energy density is found to diverge faster in five dimensions than in four dimensions, indicating faster collapse here. Also, the cosmological horizon and the black hole horizon have larger proper areas than they do in four dimensions. This paper is devoted to the study of a five-dimensional spherically symmetric perfect fluid collapse with a positive cosmological constant. We take a five-dimensional spherically symmetric metric in the interior region and a five-dimensional Schwarzschild-de Sitter metric in the exterior region. The junction conditions between the interior and the exterior spacetimes are derived. By assuming that the energy density and the pressure satisfy the weak energy condition, we discuss the solution for the interior spacetime with a perfect fluid for both the marginally bound and the non-marginally bound cases. We investigate the apparent horizons and their physical significance and conclude that the cosmological constant slows down the collapse of matter and, hence, limits the size of the black hole. This analysis generalizes four-dimensional perfect fluid collapse. The energy density is found to diverge faster in five dimensions than in four dimensions, indicating faster collapse here. Also, the cosmological horizon and the black hole horizon have larger proper areas than they do in four dimensions.

Preconcentration and determination of chromium in water with flame atomic absorption spectrometry by thiourea-formaldehyde as chelating resin

Homayon Ahmad Panahi,Amir Abdollah Mehrdad Sharif,Mehrnaz Bigonah,Elham Moniri 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.6

Thiourea-formaldehyde chelating resin is synthesized simply and rapidly from thiourea and formaldehyde by condensation polymerization and characterized by IR spectra and studied for the preconcentration and determination of trace Cr(Ⅲ) ion from solution samples. The optimum pH value for sorption of the metal ion was 6.5. The sorption capacity of resin for Cr(Ⅲ) was determined. The chelating resin can be reused for 20 cycles of sorption-desorption without any significant change in sorption capacity. A recovery of 96% was obtained for the metal ion with 0.5M HNO3 as eluting agent. The equilibrium adsorption data of Cr(Ⅲ) on modified resin were analyzed by Langmuir, Freundlich and Temkin models. Based on equilibrium adsorption data the Langmuir, Freundlich and Temkin constants were determined as 0.016, 0.040 and 0.074 at pH 6.5 and 20℃. The method was applied for chromium ion determination from river water sample.

Output Feedback Robust Siding Mode Controller Design for Wind Turbine

Azita Sharif Faskhodi,Ahmad Fakharian 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.6

In this paper, by choosing a nonlinear model of wind turbine, we want to control the output power of a wind turbine by measuring the rotor speed. For this purpose, the robust sliding mode controller is used to improve the response and the observer is used to estimate system states, which ultimately the proposed controller will be able to limit the power by limiting the rotor speed. In this control system, the rotor speed is considered as output of the system and also input of the controller, blades angle is considered as output of the controller. Here, we use observer state, output feedback and robust sliding mode controller to get the desired response at speed faster than nominal wind speed. First, using rotor speed, system states are estimated while wind is considered as an exogenous state. Then, robust Disturbance Accommodation Controller (DAC) based on sliding mode (SM) is developed. Finally, the efciency of the proposed DAC-SM approach is compared with existing Disturbance Accommodation Controller (DAC) method. At the end, after obtaining the data and analyze them, the simulation results verify the merits of the proposed controller.

Lipoxygenase Inhibitory Constituents from Indigofera oblongifolia

Ahsan Sharif,Ejaz Ahmed,Abdul Malik,Naheed Riaz,Nighat Afza,Sarfraz Ahmad Nawaz,Muhammad Arshad,Muhammad Raza Shah,Muhammad Iqbal Choudhary 대한약학회 2005 Archives of Pharmacal Research Vol.28 No.7

Indigin, alkylated xanthene (1) and indigoferic acid (2) have been isolated from the chloroform soluble fraction of Indigofera oblongifolia, along with β-sitosterol (3) and 3-hydroxybenzoic acid (4), which are reported for the first time from this species. Their structures were determined through spectroscopic techniques. Both the new compounds 1 and 2 showed significant activity against enzyme lipoxygenase, while 2 further showed moderate inhibition against BChE.

OPTIMIZATION OF THE MECHANICAL STRENGTH PROPERTIES OF POLY(L-LACTIDE)/MULTI-WALLED CARBON NANOTUBE SCAFFOLDS USING RESPONSE SURFACE METHODOLOGY

HASSAN ADELI,SHARIF HUSSEIN SHARIF ZEIN,SOON HUAT TAN,ABDUL LATIF AHMAD 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2011 NANO Vol.6 No.2

In this study the response surface methodology (RSM) coupled with the central composite design (CCD) were used to optimize the mechanical strength properties of poly(L-lactide)/multi-walled carbon nanotube (MWCNT) scaffolds. The scaffolds were prepared by the freeze-extraction method. MWCNTs were incorporated into PLLA composite as a reinforcement agent in order to improve the strength properties of the scaffolds. The effect of process parameters such as ratio of PLLA/(PLLA + MWCNT) (93–100%), solvent amount (100–200 ml), freezing time (5–7 h) and immersing time (2–4 days) were studied using the design of experiment (DOE). Based on CCD, quadratic model was obtained and developed to correlate the process parameters to the strength of the scaffolds. An analysis of variance (ANOVA) was applied to determine the significant factors affecting the experimental design response (strength) of the scaffolds. The predicted values after optimization process were in good agreement with the experimental values. The model was able to accurately predict the response of strength with less than 5% error.

Effect of solvent on the characteristics of nanostructured composites of poly (1-naphthylamine) with poly (vinyl alcohol)

Ufana Riaz,Sharif Ahmad,S.M. Ashraf 한국물리학회 2009 Current Applied Physics Vol.9 No.3

Efficient utilization of inherently conducting polymers in nano technological applications faces the challenge to assemble them into highly ordered structures which may yield novel properties. The present study reports for the first time the synthesis and characterization of nanostructured poly (1-naphthylamine) (PNA) dispersed polyvinyl alcohol (PVA) composites. The composites were prepared by loading PNA from 2 wt% to 10 wt% in PVA in aqueous as well as nonaqueous media. The composites were characterized by UV–visible spectroscopy, TEM, stress–strain studies, electrical conductivity measurements and moisture absorption studies under controlled humidity. A discrete but uniform distribution of nanoparticles was obtained in PNA/PVA composites synthesized in water having particle size between 5 and 30 nm. A self assembled network of nanostructured PNA particles was obtained in case of PNA/PVA composites synthesized in N-methylpyrolidone (NMP) with particle sizes between 10 and 65 nm. The variation in the nanostructured morphology of PNA particles in PVA matrix in the two cases resulted from the pronounced interaction of PVA with NMP through hydrogen bonding. This leads to the formation of a homogeneous matrix that facilitates the formation of a self assembled network of PNA nano particles. In case of PNA/PVA composites synthesized in water, lower affinity of PVA towards water was responsible for a discrete, agglomerate free distribution of PNA particles. We have found that the PNA/PVA nano composite synthesized in water exhibited good mechanical properties and electrical conductivity (8.1 × 10-1 S/cm) as well as lowest moisture absorption (4 wt%) which holds potential for use in semiconductor and biomedical devices. Efficient utilization of inherently conducting polymers in nano technological applications faces the challenge to assemble them into highly ordered structures which may yield novel properties. The present study reports for the first time the synthesis and characterization of nanostructured poly (1-naphthylamine) (PNA) dispersed polyvinyl alcohol (PVA) composites. The composites were prepared by loading PNA from 2 wt% to 10 wt% in PVA in aqueous as well as nonaqueous media. The composites were characterized by UV–visible spectroscopy, TEM, stress–strain studies, electrical conductivity measurements and moisture absorption studies under controlled humidity. A discrete but uniform distribution of nanoparticles was obtained in PNA/PVA composites synthesized in water having particle size between 5 and 30 nm. A self assembled network of nanostructured PNA particles was obtained in case of PNA/PVA composites synthesized in N-methylpyrolidone (NMP) with particle sizes between 10 and 65 nm. The variation in the nanostructured morphology of PNA particles in PVA matrix in the two cases resulted from the pronounced interaction of PVA with NMP through hydrogen bonding. This leads to the formation of a homogeneous matrix that facilitates the formation of a self assembled network of PNA nano particles. In case of PNA/PVA composites synthesized in water, lower affinity of PVA towards water was responsible for a discrete, agglomerate free distribution of PNA particles. We have found that the PNA/PVA nano composite synthesized in water exhibited good mechanical properties and electrical conductivity (8.1 × 10-1 S/cm) as well as lowest moisture absorption (4 wt%) which holds potential for use in semiconductor and biomedical devices.

A review on conducting polymer reinforced polyurethane composites

Halima Khatoon,Sharif Ahmad 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.53 No.-

With the endless efforts in the development of polymer composite materials, conducting polymer reinforced in polyurethane (CP/PU) composites are gaining tremendous attention of scientific community in the past few years. Conducting polymers as a reinforcement, offers exceptional properties when it combines with the thermoplastic polyurethane matrix. In view of this, we critically highlight the development of different types of conducting polymers reinforced in polyurethane composites, with a detailed discussion on their method of synthesis and various characterizations techniques. Furthermore, the promising applications of CP/PU composites have also been discussed. Finally, we attempted to assemble the existing challenges and the possible future perspectives.