A Product Inhibition Study on Adenosine Deaminase by Spectroscopy and Calorimetry

(Ali Akbar Saboury),(Ghasem Ataie Jafari),(Ali Akbar Moosavi Movahedi),(Mohammad Reza Housaindokht),(Gholam Hosain Hakimelahi),(Adeleh Divsalar) 생화학분자생물학회 2002 BMB Reports Vol.35 No.3

Kinetic and thermodynamic studies have been made on the effect of the inosine product on the activity of adenosine deaminase in a 50 mM sodium phosphate buffer, pH 7.5, at 27oC using UV spectrophotometry and isothermal titration calorimetry (ITC). A competitive inhibition was observed for inosine as a product of the enzymatic reaction. A graphical-fitting method was used for determination of the binding constant and enthalpy of inhibitor binding by using isothermal titration microcalorimetry data. The dissociation-binding constant is equal to 140 μM by the microcalorimetry method, which agrees well with the value of 143 μM for the inhibition constant that was obtained from the spectroscopy method.

Numerical study of different conduction models for Al2O3-water nanofluid with variable properties inside a trapezoidal enclosure

Ali Akbar Abbasian Arani,Ali Akbar Azemati,Mohammad Rezaee,Behzad Shirkavand Hadavand 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.5

Natural convection in enclosures containing nanofluids is important in physical and environmental applications. Different models for conduction have been developed because of the importance of this phenomenon in natural convection in enclosures. In this study, effects of conduction models of Chon, Corcione, Khanafer, and Koo and Kleinstreuer on the natural convection inside a trapezoidal enclosure with hot and cold walls are evaluated numerically. The enclosure contains Al 2 O 3 -water nanofluid with variable properties. Effects of the conduction models on fluid flow, natural convection, variations in volume fraction, and diameter of nanoparticles in the models, as well as the variations in the Rayleigh number, are examined. Results show that at Rayleigh numbers of 10 5 and 10 6 , the maximum and minimum values of the average Nusselt number are obtained using the models of Khanafer and Chon, respectively. In all models, the average Nusselt number presents upward and downward trends when the volume fraction of nanoparticles increases but decreases when the diameter of the nanoparticles increases. At Ra = 10 5 in all models, as the volume fraction of nanoparticles increases, the nanofluid provides a higher average Nusselt number compared with the base fluid. By contrast, at Ra = 10 6 , at volume fractions larger than 0.01 and using the model of Chon, the average Nusselt number of the nanofluid is lower compared with that of the base fluid.

A Product Inhibition Study on Adenosine Deaminase by Spectroscopy and Calorimetry

Saboury, Ali Akbar,Divsalar, Adeleh,Jafari, Ghasem Ataie,Moosavi-Movahedi, Ali Akbar,Housaindokht, Mohammad Reza,Hakimelahi, Hosain 생화학분자생물학회 2002 Journal of biochemistry and molecular biology Vol.35 No.3

Kinetic and thermodynamic studies have been made on the effect of the inosine product on the activity of adenosine deaminase in a 50 mM sodium phosphate buffer, pH 7.5, at $27^{\circ}C$ using UV spectrophotometry and isothermal titration calorimetry (ITC). A competitive inhibition was observed for inosine as a product of the enzymatic reaction. A graphical-fitting method was used for determination of the binding constant and enthalpy of inhibitor binding by using isothermal titration microcalorimetry data. The dissociation-binding constant is equal to $140\;{\mu}M$ by the microcalorimetry method, which agrees well with the value of $143\;{\mu}M$ for the inhibition constant that was obtained from the spectroscopy method.

Yellowing Inhibition of Bagasse Chemimechanical Pulp

ALI ABDULKHANI,SEYED AHMAD MIRSHOKRAIE,AHMAD JAHAN LATIBARI,ALI AKBAR ENAYATI 한국펄프·종이공학회 2006 한국펄프종이학회 기타 간행물 Vol.- No.-

Papers made from unbleached and bleached bagasse chemimechanical pulp were chemically modified by acetylation. The effects of irradiation on unbleached and bleached also reduced papers of bagasse chemimechanical pulp before and after acetylation were investigated in this study. Chemimechanical pulp was prepared from bagasse and then bleached with hydrogen peroxide. Unbleached and hydrogen bleached pulps were reduced by Sodium borohydride in different procedures. Paper sheets were prepared from pulps and then acetylated using a technical grade of acetic anhydride. Accelerated photo-aging was run on the samples using fluorescent lamps to verify photo-stability of paper sheets before and after pretreatments. Brightness reversion (as Post-color number) and other optical properties of the paper sheets were measured. Efficient inhibition of photo-yellowing of papers made from bagasse CMP was achieved by acetylation. The acetylated unbleached CMP was noticeably photo-bleached during irradiation. Sodium borohydride reduction followed by acetylation had the same effect as acetylation alone at the same degree of reaction time and reductive treatment did not affect the yellowing rate to any great extent. The pre-reduced, acetylated unbleached papers were, however, not brightened during irradiation. Calculation done by Kubelka-Munk equation showed that reductive treatment had little effect in reducing the photo-yellowing of paper made from CMP pulp; a small stabilization effect was observed in the case of bleached CMP, while unbleached CMP was slightly more prone to discolor in the later phase of photo-reversion. The improved stability towards light may was closely related to the decrease in the phenolic hydroxyl content as a result of blocking by acetyl groups during treatment with acetic anhydride. The results support the hypothesis that phenolic hydroxyl has an important role in the process of photo-reversion of high-yield pulps. The results obtained in this study demonstrate that the acetylation of paper manufactured from peroxide bleached Bagasse CMP significantly retards light-induced discoloration. The inhibition of yellowing is connected with a decrease in the phenolic hydroxyl content of both unbleached and peroxide bleached papers.

Observer-based Reliable Control for Lipschitz Nonlinear Networked Control Systems with Quadratic Protocol

Ali-Akbar Ahmadi,Farzad R. Salmasi 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.3

In this paper, observer-based reliable control problem for nonlinear networked control systems (NCSs) with quadratic protocol (QP) in presence of actuator fault is studied. Two sensor nodes are employed for system output measurement and transmission to remote observer-based reliable controller (RORC) based on QP. In spite of the majority of the existing results, both measurement and actuation channels are taken into account for data transmission of sensor-to-RORC and RORC-to actuator, respectively. A RORC is developed to estimate the system states and simultaneously generate the control input at its side. The closed-loop system is modeled by a hybrid system with interval time-varying delays in continuous dynamics and in the reset conditions. By using Lyapunov-Krasovskii functional method and some matrix manipulations, designing of RORC and the QP parameters are formulated in linear matrix inequalities (LMIs) framework with equality constraint. Numerical simulations are presented to show the effectiveness and applicability of the proposed approach.

A new electrochemical biosensor for hydrogen peroxide using HRP/AgNPs/cysteamine/p-ABSA/GCE self-assembly modified electrode

Ali Shokuhi Rad,Mohsen Jahanshahi,Mehdi Ardjmand,Ali-Akbar Safekordi 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.12

An electrochemical hydrogen peroxide biosensor was designed by immobilizing horseradish peroxidase (HRP) on Ag nanoparticles/cysteamine/p-aminobenzene sulfonic acid/glassy carbon (GC) electrode. Ag nanoparticles can act as tiny conduction centers on electrodes that adsorb redox enzymes, facilitating the transfer of electrons with no requiring any loss of biological activity. The forerunner film was first electropolymerized on the glassy carbon electrode with p-aminobenzene sulfonic acid (p-ABSA) by cyclic voltammetry. The cysteamine (CA) was bound on the surface of the film by electrostatic force, then Ag nanoparticles were immobilized on the cysteamine monolayer, and lastly HRP was adsorbed onto the surfaces of the Ag nanoparticles. A dramatic decrease in the overvoltage of H2O2was observed with improved sensitivity, which makes the modified electrodes of great promise for oxidase-based amperometric biosensors. The biosensor responded to H2O2 in the linear range from 1.2×106 mol/L to 9.8×103 mol/L with a detection limit of 1.1×108 mol/L. Moreover, the obtained biosensor exhibited good accuracy and high sensitivity.

Brain Medical Image Retrieval Using Non-Negative Matrix Factorization and Canny Edge Detection

Ali Akbar Lubis,Suharjito 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.4

Disease conditions in the human brain can be detected by using medical image analysis. Content Based Image Retrieval of medical images can be used as an alternative to recognize the medical images of the human brain. In CBIR, feature extraction and recognition methods was an important feature because of medical image was different from the general image. In this study medical images that contain clinical information will be used as feature extraction using a canny edge detection and recognition features using non-negative matrix Factorization (NNMF). The purpose of this paper was to describe the use of canny edge detection and NNMF in CBIR. So CBIR could provide information on brain diseases and abnormalities. The results showed that the detection of disease in the human brain can be done by using both methods with good results if done preprocessing using histogram equalization.

Comparison of different fluid dynamics in activated sludge system for the treatment of a stimulated milk processing wastewater: Process analysis and optimization

Ali Akbar Zinatizadeh Lorestani,Hojjatollah Bashiri,Azar Asadi,Hossein Bonakdari 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.10

Wastewater from the milk industry usually undergoes activated sludge ahead of refining treatments, final discharge or reuse. To identify the most effective bioreactor hydraulic regime for the secondary treatment of wastewater resulting from the milk industry in an activated sludge system, two lab-scale activated sludge systems characterized by a different configuration and fluid dynamics (i.e., a compartmentalized activated sludge (CAS) with plug flow regime and a complete mixed activated sludge (AS)) were operated in parallel, inoculated with the same microbial consortium and fed with identical streams of a stimulated dairy wastewater. The effect of three process and operational variables--influent chemical oxygen demand (COD) concentration, sludge recycle ratio (R) and hydraulic retention time (HRT)--on the performance of the two systems were investigated. Experiments were conducted based on a central composite face-centered design (CCFD) and analyzed using response surface methodology (RSM). The region of exploration for treatment of the synthetic wastewater was taken as the area enclosed by the CODin (200, 1,000 mg/l), R (1, 5), and HRT (2, 5 h) boundaries. To evaluate the process, three parameters, COD removal efficiency (E), specific substrate utilization rate (U), and sludge volume index (SVI), were measured and calculated over the course of the experiments as the process responses. The change of the flow regime from complete-mix to plug flow resulted in considerable improvements in the COD removal efficiency of milk wastewater and sludge settling properties. SVI levels for CAS system (30-58 ml/g) were considerably smaller that for the AS system (50-145 ml/g). In addition, the biomass production yield could be reduced by about 10% compared to the AS system. The results indicated that for the wastewater, the design HRT of a CAS reactor could be shortened to 2-4 h.

Extraction conditions for removal of oxidized sulfur compounds in gas oil

Ali Akbar Safekordi,Mahsa Heidari,Maryam Ghaedian,Amin Shafeghat 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.3

An experimental study was conducted to investigate the extraction of oxidized sulfur compounds from gas oil. Solvents used for this purpose included acetone, acetonitrile, methanol and propanol. The effect of solvent concentration,solvent to gas oil ratio, temperature, time and number of stages was studied. To select the best solvent and conditions for extraction, two criteria were considered: high desulfurization and more hydrocarbon recovery. Results showed that extraction time and temperature have no significant effect. Methanol for low ability of extraction of oxidized sulfur compounds and propanol for low hydrocarbon recovery were excluded from further experiments. After the tests,the optimum conditions for extraction were determined to be 85% acetone, solvent/feed ratio of 1, two stages extraction in ambient temperature and enough time for mixing. In this condition 85% of sulfur compounds of gas oil containing 1,670 ppmw S were separated and 95% of gas oil was recovered.

Outcome of Rectal Cancer in Patients Aged 30 Years or Less in the Pakistani Population

Akbar, Ali,Bhatti, Abu Bakar Hafeez,Khattak, Shahid,Syed, Aamir Ali,Kazmi, Ather Saeed,Jamshed, Aarif Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.15

Background: The incidence of rectal cancer is increasing in younger age groups. Limited data is available regarding survival outcome in younger patients with conflicting results from western world. The goal of this study was to determine survival in patients with rectal cancer <30 years of age and compare it with their older counterparts in the Pakistani population. Materials and Methods: A retrospective chart review of patients operated for rectal adenocarcinoma between January 2005 and December 2010 was performed. Patients were divided into two groups, Group 1 aged ${\leq}30years$ and Group 2 aged >30years. Patient characteristics, surgical procedure, histopathological details and number of loco-regional and distant failures were compared. Expected 5 year survival was calculated using Kaplan Meier curves and significance was determined using the Log rank test. Results: There were 38 patients in group 1 and 144 in group 2. A significantly high number of younger patients presented with poorly differentiated histology (44.7% vs 9.7%) (p=0.0001) and advanced pathological stage (63.1% vs 38.1%) (p=0.04). Predicted overall 5 year survival was 38% versus 57% in groups I and II, respectively (p=0.05). Disease free survival was 37% versus 52% and was significantly different (p=0.007). Conclusions: Early onset rectal cancer is associated with poor pathological features and a worse outcome in Pakistani population.