Effect of calcination and reaction conditions on the catalytic performance of Co–Ni/Al2O3 catalyst for CO hydrogenation

Akbar Zare,Mehdi Shiva,Ahad Zare,Ali Akbar Mirzaei 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.6

The Co–Ni/Al2O3 catalysts prepared using impregnation procedure, were used for the Fischer–Tropsch synthesis. The effect of calcination conditions of the catalyst as well as reactor situation was studied. It was found that the catalyst calcined at 550 8C for 6 h in air atmosphere has shown the best catalytic performance for CO hydrogenation. The best operational conditions were obtained as following:T = 350 8C, P = 1 atm and H2/CO = 2/1.

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 brief review on graphene applications in rechargeable lithium ion battery electrode materials

Sameen Akbar,Muhammad Rehan,Liu Haiyang,Iqra Rafique,Hurria Akbar 한국탄소학회 2018 Carbon Letters Vol.28 No.-

Graphene is a single atomic layer of carbon atoms, and has exceptional electrical, mechanical, and optical characteristics. It has been broadly utilized in the fields of material science, physics, chemistry, device fabrication, information, and biology. In this review paper, we briefly investigate the ideas, structure, characteristics, and fabrication techniques for graphene applications in lithium ion batteries (LIBs). In LIBs, a constant three-dimensional (3D) conductive system can adequately enhance the transportation of electrons and ions of the electrode material. The use of 3D graphene and graphene-expansion electrode materials can significantly upgrade LIBs characteristics to give higher electric conductivity, greater capacity, and good stability. This review demonstrates several recent advances in graphenecontaining LIB electrode materials, and addresses probable trends into the future.

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.

Manual Liquid Based Cytology for Pap Smear Preparation and HPV Detection by PCR in Pakistan

Akbar, Shehla,Pervez, Shgufta Nasir,Shah, Walayat Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.2

This study was conducted on female patients with different gynecological problems attending the gynecology out-patient departments of two tertiary care hospitals in Peshawar city of Khyber Pakhtunkhwa, Pakistan between August 2012 and October 2013. The 200 patients had an age range of 21-65 years. Smears were taken with cervical brushes and preserved in preservative medium and processed for manual liquid based cytology (MLBC) for Pap staining. Out of 200 collected samples, 30 samples were found inadequate on cytology. Of the remaining 170 samples, 164 (96.47%) were normal, 5 (2.94%) were of atypical squamous cells of unknown significance (ASCUS) and 1 (0.6%) was of high grade squamous intraepithelial lesion (HSIL). On PCR all the samples were positive for beta globin gene fragment including those reported inadequate on cytology. Out of the 5 ASCUS samples, 2 samples were positive for HPV, one each for HPV 16 and HPV 18, and the rest of the 3 samples were negative for HPV DNA. The 1 sample of HSIL was positive for HPV 16 on PCR. Out of 164 normal samples on cytology, only 1 sample was HPV 16 positive. So overall, 4 (2%) out of 200 samples were positive for HPV DNA, where 3 were HPV 16 (1.5%), and 1 was HPV 18 (0.5%) positive, and thus the ratio of infection with of HPV 16 to HPV 18 was 3:1 in the general population. In conclusion, PCR based HPV detection is a more sensitive method for screening of HPV infection than cytology as sample inadequacy does not affect the results. However, it can be combined with cytology methods in a HPV positive female to achieve the maximum results.

High-Efficiency FTO-Free Counter Electrodes for Dye-Sensitized Solar Cells Based on Low-Pt-Doped Carbon Nanosheets

Akbar, Zico Alaia,Lee, Jae-Seon,Joh, Han-Ik,Lee, Sungho,Jang, Sung-Yeon American Chemical Society 2015 The Journal of Physical Chemistry Part C Vol.119 No.5

<P>Highly efficient fluorine doped tin oxide (FTO)-free counter electrodes (CEs) for dye-sensitized solar cells (DSSCs) are developed by a low amount doping of Pt on carbon nanosheet (CNS)-based charge-collecting electrodes. The low Pt-doped CNS-based CEs were prepared by simple deposition of Pt by a conventional method. The CNSs had a dual function as both highly conducting charge-collecting electrodes (sheet resistance of ∼40 Ω/sq) and decent electrocatalytic CE layers for iodine reduction. Low Pt doping (using ∼100 times less Pt than with conventional doping) on a CNS dramatically improved the electrocatalytic activity for the I<SUB>3</SUB> reduction of the CNSs and the charge transfer resistance at CE/electrolyte interfaces, which was not possible using FTO. The performance of the low-Pt-doped CNS CEs was comparable to that of high (conventional)-Pt-doped FTO CEs. DSSCs using the low-Pt-doped CNS CEs showed a power conversion efficiency (PCE) of 7.56%, whereas those using high-Pt-doped CNS CEs showed a PCE of 8.05%. In contrast, DSSCs using low-Pt-doped FTO CEs showed a PCE of 4.50%, whereas those using high-Pt-doped FTO CEs showed a PCE of 8.21%. Pt/CNS is an intriguing CE material that can use 100 times less Pt than conventional Pt/FTO CEs, which suggests a useful strategy for reducing the fabrication cost of DSSCs.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2015/jpccck.2015.119.issue-5/jp510871c/production/images/medium/jp-2014-10871c_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp510871c'>ACS Electronic Supporting Info</A></P>

FTO-free counter electrodes for dye-sensitized solar cells using carbon nanosheets synthesised from a polymeric carbon source

Akbar, Zico Alaia,Lee, Jae-Seon,Kang, Jinhyeon,Joh, Han-Ik,Lee, Sungho,Jang, Sung-Yeon The Royal Society of Chemistry 2014 Physical chemistry chemical physics Vol.16 No.33

<P>Highly conductive carbon nanosheets (CNSs) are fabricated using a polymeric carbon source and subsequently applied as the counter electrodes (CNS-CEs) for dye-sensitized solar cells (DSSCs). The CNSs have a similar structure to multilayered graphene, and their high electrical conductivity and electrocatalytic activity enable them to have a dual-function as both CEs and charge supporting electrodes. CNSs form a unique CE material that functions successfully while being metal- and fluorine doped tin oxide (FTO)-free and allowing DSSCs to achieve ∼5% power conversion efficiency. The chemical structure, electrical properties, electrocatalytic activity, and work function of the CNS-CEs prepared under various conditions of carbonization are investigated, and their effects on the performance of the corresponding DSSCs are discussed. Carbonization temperature is shown to have influenced the size of graphitic domains and the presence of heteroatoms and functional groups in CNS-CEs. The change in the graphitic domain size has a marginal influence on the work function of the CNS-CEs and the overpotential for the reduction of the redox couples (I<SUP>−</SUP>/I<SUB>3</SUB><SUP>−</SUP>). However, the electrical conductivity of CNS-CEs and the charge transfer resistance at CE/electrolyte interfaces in the DSSCs are considerably influenced by the carbonization condition. Our study shows that CNSs serve as efficient, FTO-free CE materials for DSSCs, and they are appropriate materials with which the effects of the chemical/physical properties of graphene-based materials on the electrode performance of various electrochemical devices may be studied.</P> <P>Graphic Abstract</P><P>Dye-sensitized solar cells were fabricated using novel carbon nanosheets synthesized from polymeric sources as the Pt and FTO-free counter electrodes. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cp01913j'> </P>

MINIMUM PENDANT DOMINATING ESTRADA INDEX OF A GRAPH

AKbar Jahanbani,Ismail Naci CANGUL 장전수학회 2020 Advanced Studies in Contemporary Mathematics Vol.30 No.4

The main purpose of this paper is to introduce the con- cept of minimum pendant dominating Estrada index of a graph. First, we compute minimum pendant dominating Estrada index for complete graph, star graph, complete bipartite graph and cocktail party graph which are amongst the most widely-used graph classes. Also, upper and lower bounds for this new index are established. Finally, the rela- tions between the new Estrada index and the new type of energy are investigated.

Comparison between Tear Film Osmolar Cocentration and Other Tear Film Function Parameters

akbar derakhshan,arash omidtabrizi,majid abrishami,mohamad khajedaluee,somayeh ghassemi moghaddam 대한안과학회 2019 Korean Journal of Ophthalmology Vol.33 No.4

Purpose: To evaluate tear film function in patients with diabetes mellitus (DM) using tear film osmolarity (TFO)measurements compared to other tear film function tests. Methods: DM patients without any history of ocular surface disorder but with potential effects on the tear filmwere enrolled in this cross-sectional study. Data including dry eye symptoms, duration of DM, stage of diabeticretinopathy and blood hemoglobin A1c levels were recorded. Tear film break-up time (TBUT) and basic tearsecretion (Schirmer test) were assessed. TFO was determined using the Tearlab Osmolarity System. The outcomemeasures were the difference between the mean values of TBUT, basic tear secretion and TFO in boththe study and control groups. Results: We recruited 51 DM patients and 20 control subjects with a mean age of 51.2 (range, 21 to 70) and48.5 (range, 24 to 70) years, respectively. A total of 27 patients (53%) and 11 controls (55%) reported dry eyesymptoms (p = 0.668). The mean TBUT was 10.2 + 4.8 seconds in the study group versus 10.5 + 2.8 secondsin controls, which was not significantly different (p = 0.747). The mean Schirmer test score was 8.1 + 4.3 mmin the patients versus 10.1 + 3.0 mm in the controls (p = 0.069). The mean TFO was 294.1 + 12.9 mosmol/Lin the patients versus 291.4 + 14.5 mosmol/L in the controls (p = 0.456). It was significantly higher in patientswith poor glycemic control determined by hemoglobin A1c > 8% (p = 0.003). TFO had a positive correlationwith the duration of DM (p = 0.030) but not with the stage of diabetic retinopathy (p = 0.944). However, TFOshowed a significant relationship with dry eye symptoms (p = 0.001). Conclusions: TFO is impaired in patients with uncontrolled DM and is better correlated with glycemic controland dry eye symptoms than the TBUT and Schirmer tests.