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Open access

Naveed Ramzan, Muhammad Athar, Sharmina Begum, Syed Waqas Ahmad and Shahid Naveed

Abstract

A process model for turbulent pressurized circulating fluidized-bed coal gasifier is created using ASPEN PLUS software. Both hydrodynamic and reaction kinetics parameter are taken into account, whose expressions for fluidized bed are adopted from the literature. Various reactor models available in ASPEN PLUS with calculator as External Block are nested to solve hydrodynamics and kinetics. Multiple operational parameters for a pilot-plant circulating fluidized-bed coal gasifier are used to demonstrate the effects on coal gasification characteristics. This paper presents detailed information regarding the simulation model, including robust analysis of the effect of stoichiometric ratio, steam to coal ratio, gasification temperature and gasification agent temperature. It is observed that, with the increase in the flow rate of air, the components hydrogen, carbon monoxide, carbon dioxide and methane reduce, which causes the Lower Heating Value (LHV) of synthesis gas (Syn. Gas) to decrease by about 29.3%, while increment in the steam flow rate shows a minute increase in heating value of only 0.8%. Stoichiometric ratio has a direct relationship to carbon conversion efficiency and carbon dioxide production. Increasing the steam to coal ratio boosts the production of hydrogen and carbon monoxide, and causes a drop in both carbon dioxide concentration and the conversion efficiency of carbon. High gasifying agent temperature is desired because of high concentration of CO and H2, increasing carbon conversion and LHV. A high gasifying agent temperature is the major factor that affects the coal gasification to enhance H2 and CO production rapidly along with other gasification characteristics.

Open access

Faisal Rehman, Syed Waqas Ahmad, M. Shahzad Zafar, Sajjad Ahmad and Muhammad Zia-Ul-Haq

Abstract

Desulfurization of Pakistani coal has been carried out through alkaline leaching. During present experimental investigation, the effect of operating parameters like alkali concentration, time, temperature and particle size has also been analyzed, graphically represented and critically discussed. Parametric optimization of leaching process has been carried out by using response surface methodology (RSM) based on central composite design (CCD). The analysis of variance (ANOVA) was performed in order to assess the highest level interactions of variables and three way interactions were observed signifi cant. Further, the optimum value of total sulfur removal was observed as 53% when the operatic conditions fi xed at 10% W/V, 60 min, 80oC and 140 mesh for alkaline concentration, leaching time, temperature and particle size, respectively.

Open access

M. Azam Saeed, Syed Waqas Ahmad, Mohsin Kazmi, Muhammad Mohsin and Nadeem Feroze

Abstract

The concept of different compositional biomass is introduced to enhance the binding properties and utilize the use of different seasonal biomasses. The effect of densification on the heating values of single pure and mixed compositional biomasses is observed with and without applying special type of pretreatment named as ‘Torrefaction’. The moisture contents and bulk densities were also calculated for these briquettes. The effects of average moisture contents and bulk density (which show the swelling nature) on the heating values are also observed. The experiments have been performed on the pelletizer equipment to form briquetted biomass and bomb calorimeter was used to determine the calorific values of different briquettes. Finally, the percentage decrease in the average moisture contents of different categories of torrefied briquettes from non-torrefied briquettes were also calculated and compared.

Open access

Mohsin Kazmi, Anwar R. Saleemi, Nadeem Feroze, Amir Yaqoob and Syed Waqas Ahmad

This investigation enumerates the treatment of phenol contaminated synthetic wastewater by Activated Waste Tea Leaves (AWTL). Phosphoric acid was used for the modification of waste tea leaves. The effects of initial pH, biosorbent dose, contact time, and initial phenol concentration were studied on the phenol uptake from the synthetic solution. Kinetic modelling was performed using pseudo 1st and 2nd order kinetics. The Langmuir and Freundlich’s Models were employed to interpret the AWTL behaviour at various mass transfer gradients. The results show that the optimum values for pH, biosorbent dose and contact time were 2.2 g/L and 180 minutes, respectively. Pseudo 2nd order kinetic and the Langmuir’s Models best described the kinetic and equilibrium behaviours, respectively.

Open access

Xi-Lin Liu, Xiao-Li Feng, Guang-Ming Wang, Bin-Bin Gong, Waqas Ahmad, Nan-Nan Liu, Yuan-Yuan Zhang, Li Yang, Hong-Lin Ren and Shu-Sen Cui

Abstract

Introduction: The functions and mechanisms of prion proteins (PrPC) are currently unknown, but most experts believe that deformed or pathogenic prion proteins (PrPSc) originate from PrPC, and that there may be plural main sites for the conversion of normal PrPC into PrPSc. In order to better understand the mechanism of PrPC transformation to PrPSc, the most important step is to determine the replacement or substitution site.

Material and Methods: BALB/c mice were challenged with prion RML strain and from 90 days post-challenge (dpc) mice were sacrificed weekly until all of them had been at 160 dpc. The ultra-structure and pathological changes of the brain of experimental mice were observed and recorded by transmission electron microscopy.

Results: There were a large number of pathogen-like particles aggregated in the myelin sheath of the brain nerves, followed by delamination, hyperplasia, swelling, disintegration, phagocytic vacuolation, and other pathological lesions in the myelin sheath. The aggregated particles did not overflow from the myelin in unstained samples. The phenomenon of particle aggregation persisted all through the disease course, and was the earliest observed pathological change.

Conclusion: It was deduced that the myelin sheath and lipid rafts in brain nerves, including axons and dendrites, were the main sites for the conversion of PrPC to PrPSc, and the PrPSc should be formed directly by the conversion of protein conformation without the involvement of nucleic acids.

Open access

Yong-Jie Yang, Zeng-Shan Liu, Shi-Ying Lu, Pan Hu, Chuang Li, Waqas Ahmad, Yan-Song Li, Yun-Ming Xu, Feng Tang, Yu Zhou and Hong-Lin Ren

Abstract

Introduction: Serological diagnosis of brucellosis is still a great challenge due to the infeasibility of discriminating infected animals from vaccinated ones, so it is necessary to search for diagnostic biomarkers for differential diagnosis of brucellosis.

Material and Methods: Cell division cycle 42 (Cdc42) from sheep (Ovis aries) (OaCdc42) was cloned by rapid amplification of cDNA ends (RACE), and then tissue distribution and differential expression levels of OaCdc42 mRNA between infected and vaccinated sheep were analysed by RT-qPCR.

Results: The full-length cDNA of OaCdc42 was 1,609 bp containing an open reading frame (ORF) of 576 bp. OaCdc42 mRNAs were detected in the heart, liver, spleen, lung, kidneys, rumen, small intestine, skeletal muscles, and buffy coat, and the highest expression was detected in the small intestine. Compared to the control, the levels of OaCdc42 mRNA from sheep infected with Brucella melitensis or sheep vaccinated with Brucella suis S2 was significantly different (P < 0.01) after 40 and 30 days post-inoculation, respectively. However, the expression of OaCdc42 mRNA was significantly different between vaccinated and infected sheep (P < 0.05 or P < 0.01) on days: 14, 30, and 60 post-inoculation, whereas no significant difference (P > 0.05) was noted 40 days post-inoculation. Moreover, the expression of OaCdc42 from both infected and vaccinated sheep showed irregularity.

Conclusion: OaCdc42 is not a good potential diagnostic biomarker for differential diagnosis of brucellosis in sheep.