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Search Results: 1 - 10 of 401995 matches for " M. Abid Zia "
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Green and Sustainable Heterogeneous Organo-Catalyst for Asymmetric Aldol Reactions  [PDF]
Mohammad Sadiq, Razia Aman, Khalid Saeed, M. Sohail Ahmad, M. Abid Zia
Modern Research in Catalysis (MRC) , 2015, DOI: 10.4236/mrc.2015.42006
Abstract: Linear amino acids covalently supported on graphene sheet were employed as catalysts for asymmetric aldol reactions between cyclohexanone and aldehydes (aliphatic and/or aromatic) in a batch type reactor in the presence of water. The reactions were found to exhibit high yield as well as excellent ee value. Additionally, the catalysts were found to be truly heterogeneous and eco-friendly.
High Density Fluorine Negative-Ion Source Generated by Utilizing Magnetized SF6  [PDF]
M. Abid Imtiaz, Tetsu Mieno
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.52014

In a magnetized plasma column generated from an electronegative gas, negative-ions accumulate around the plasma column via radial diffusion. In this study, a dc discharge is applied in SF6 gas to produce a plasma column, and the radial density profile of negative-ions is measured by Langmuir probes using the modified Bohm criterion. The gas pressure and discharge current dependences of negative-ion density are also measured. It is found that the negative-ion density of 8.0 × 1017 m-3 is obtained around the plasma column at r = 1.0 cm when SF6 pressure is 0.13 Pa and discharge current is 0.50 A. The negative-ion density has radial gradient, and the electron density is much lower in this region.

Green and Efficient Oxidation of Octanol by Iron Oxide Nanoparticles Supported on Activated Carbon  [PDF]
Mohammad Sadiq, Razia Aman, Saddam Hussain, Muhammad Abid Zia, Najeeb Ur Rahman, Mohammad Saeed
Modern Research in Catalysis (MRC) , 2015, DOI: 10.4236/mrc.2015.41004
Abstract: Iron oxide nanoparticles were synthesized by precipitation method and supported on activated carbon. The catalyst thus obtained was characterized by various physicochemical techniques, and used for the liquid phase dehydrogenation/oxidation of octanol in a batch reactor at various temperatures in the range 30 °C - 60 °C. Maximum conversion of octanol to octanal was attained at 60°;C in 30 min. However, with longer reaction time, the selectivity of the catalyst was found to change in favor of octene as a product. The catalyst could be recovered and reused multiple times without any decline in its catalytic performance.
IEEE 802.11s Wireless Mesh Networks for Last-Mile Internet Access: An Open-Source Real-World Indoor Testbed Implementation  [PDF]
Riduan M. Abid, Taha Benbrahim, Saad Biaz
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.2010.210088
Abstract: Due to their easy-to-deploy and self-healing features, WMNs (Wireless Mesh Networks) are emerging as a new promising technology with a rich set of applications. While the IEEE standardization of this new technology is still in progress, its main traits are already set, e.g., architecture and MAC routing. WMNs are attracting considerable research in academia and industry as well, but the lack of open-source testbeds is restricting such a research to simulation tools. The main problem with simulation tools is that they do not reflect the complexity of RF propagation, especially in indoor environments, of which IEEE 802.11s WMNs are an example. This paper presents an open-source implementation of an indoor IEEE 802.11s WMN testbed. The implementation is transparent, easy-to-deploy, and both the source code and deployment instructions are available online. The implementation can serve as a blueprint for the WMN research community to deploy their own testbeds, negating the shortcomings of using simulation tools. By delving into the testbed implementation subtleties, this paper is shedding further light on the details of the ongoing IEEE 802.11s standard. Major encountered implementation problems (e.g., clients association, Internetworking, and supporting multiple gateways) are identified and addressed. To ascertain the functionality of the testbed, both UDP and TCP traffic are supported and operational. The testbed uses the default IEEE 802.11s HWMP (Hybrid Wireless Mesh Protocol) routing protocol along with the default IEEE 802.11s Airtime routing metric.
The Professional Medical Journal , 2002,
Abstract: A IMS & OBJECTIVES: 1. To demonstrate different etiological factors of stricture urethra. 2. To demonstratedifferent anatomical sites of urethra involved. 3. To describe management as being done at Allied Hospital, Faisalabadand suggest methods to improve it. STUDY DESIGN: Prospective. SETTING: Allied Hospital, Faisalabad.PERIOD: April 1996 to Aug 1998. PATIENTS & METHODS: A total of 100 consecutive male patients rangingfrom 6-80 years presenting to Surgical Unit II of Allied Hospital, Faisalabad with clinical diagnosis of stricture urethrawere included in the study. After history and examination, baseline investigations and retrograde urethrography wereperformed in all patients and micturating cystourethrography in patients with blind strictures. Treatment as being donewas also recorded. Follow up ranges from 4-24 months. RESULTS: Trauma was the most common cause of urethralstricture. Fracture pelvis alone was responsible for half of the strictures while straddle injury accounted for another 20%.The incidence of iatrogenic, infective and congenital stricture was found to be 24%, 4% and 2% respectively. Most of theposterior urethral strictures (86%) were due to indirect urethral trauma (fracture pelvis). Anterior urethra was the site ofinfective, congenital and iatrogenic strictures as well as strictures following direct urethral trauma. Internal urethrotomywas the treatment of first choice and was performed in 73% patients with satisfactory results. Urethroplasty was performedin 27% patients. Clean Intermittent Self Catheterization and active urethral dilatation was performed as adjuvanttreatment to prevent the recurrence of stricture. CONCLUSIONS; The etiological factors of stricture urethra andanatomical sites involved are comparable to international literature. Internal Urethrotomy is safe and reliable procedurefor simple urethral strictures while urethroplasty should be considered for complex strictures. Active urethral dilatation atrepeated intervals still has a role in preventing recurrence or stricture after initial treatment with internal urethrotomy andurethroplasty.
CFD Prediction of the Turbulent Flow Generated in Stirred Square Tank by a Rushton Turbine  [PDF]
W. Chtourou, M. Ammar, Z. Driss, M. S. Abid
Energy and Power Engineering (EPE) , 2014, DOI: 10.4236/epe.2014.65010

The Computational Fluid Dynamics (CFD) have been used in the analysis and design of agitated vessel. Most of the researches done in this area are limited to the baffled or unbaffled stirred tank. In this paper, we have been interested in studying of the new design. Particularly, the flow and turbulence fields in square vessel stirred by a standard Rushton turbine have been simulated by means of CFD techniques. The Navier-Stokes equations governing the phenomenon of transfer of momentum are solved by a discretization method for finite volume. The MRF approaches can be used in simulation of the steady state problem. The numerical results from the application of CFD code Fluent with the stationary approach Multi Reference Frame (MRF) are presented in the planes containing the blade. The validation of CFD results with experimental measurements showed a good agreement.

Individual freedom versus collective responsibility: an economic epidemiology perspective
M Zia Sadique
Emerging Themes in Epidemiology , 2006, DOI: 10.1186/1742-7622-3-12
Abstract: Immunisation represents a classic case of social dilemma: a conflict of interest between the private gains of individuals and the collective gains of a society. An individual's self-interest and choice often leads to a vaccination uptake rate less than the social optimum as individuals do not take into account the benefit to others [1]. Conventional wisdom generally favours public intervention in order to produce a socially warranted level of vaccination. This line of argument is primarily based on the externality associated with individual decisions, since individuals are presumed to make choices on the basis of their own welfare gains, without considering the full social impact of their decisions. As the benefits to society are larger than the sum of those to individuals, public policy measures aim to increase demand closer to the social optimum by subsidising the vaccine (many countries provide vaccines free of charge) or through compulsory vaccination, although such a policy is almost always partial. Individuals with religious, medical or social reasons are often exempted. There is, however, controversy over the effectiveness of public intervention compared to the free choice outcome [1-3], and it is the intention of this article to address this issue.Vaccination decisions are made under imperfect information, which means an individual's assessment of the risks and benefits of vaccination is often inaccurate. But even if individuals had perfect information regarding the cost and benefits of vaccination, the free choice outcome would still be different from the social outcome due to the 'free rider' problem associated with vaccination. The changes in risk of infection tend to induce changes in activities that put the individual at risk, which in turn alter the dynamics of disease transmission. There is a feedback mechanism between infection rate and rational response, but the classic models of infectious disease have not incorporated such endogenous behavioural r
An Implementation of Active Contour and Kalman Filter for Road Tracking
Muhammad Asif,Mohd Rizal Arshad,Muhammad Yousuf Irfan Zia,Abid Yahya
IAENG International Journal of Applied Mathematics , 2007,
Ranking insertion, deletion and nonsense mutations based on their effect on genetic information
Amin Zia, Alan M Moses
BMC Bioinformatics , 2011, DOI: 10.1186/1471-2105-12-299
Abstract: We propose computational methods to rank insertion-deletion mutations in the coding as well as non-coding regions and nonsense mutations. We rank these variations by measuring the extent of their effect on biological function, based on the assumption that evolutionary conservation reflects function. Using sequence data from budding yeast and human, we show that variations which that we predict to have larger effects segregate at significantly lower allele frequencies, and occur less frequently than expected by chance, indicating stronger purifying selection. Furthermore, we find that insertions, deletions and premature stop codons associated with disease in the human have significantly larger predicted effects than those not associated with disease. Interestingly, the large-effect mutations associated with disease show a similar distribution of predicted effects to that expected for completely random mutations.This demonstrates that the evolutionary conservation context of the sequences that harbour insertions, deletions and nonsense mutations can be used to predict and rank the effects of the mutations.Genetic variations contribute to normal phenotypic variation [1]. For human, it is estimated that there are more than 10 million SNPs (i.e. 1 in 300 base pairs on average) with an observed minor allele frequency of ≥ 1% in the population [2]. Recent advances in sequencing technologies [3] have enabled rapid discovery of other types of variations, including mutations expected to have very large effects on protein function such as frame shifting insertions and deletions (indels) and nonsense mutations (mutations that introduce premature stop codons). Amazingly, insertions and deletions are also abundant in the human genome with sizes ranging from single to several million base pairs (bp) [4,5]. For example, in 179 human genomes there were 1.13 million short indels identified [6] indicating an estimate of 1 million indels per human genome (1 in 3600 bps on average). Sim
Towards a theoretical understanding of false positives in DNA motif finding
Amin Zia, Alan M Moses
BMC Bioinformatics , 2012, DOI: 10.1186/1471-2105-13-151
Abstract: Using large-deviations theory, we derive a remarkably simple relationship that describes the dependence of false positives on dataset size for the one-occurrence per sequence motif-finding problem. As expected, we predict that false-positives can be reduced by decreasing the sequence length or by adding more sequences to the dataset. Interestingly, we find that the false-positive strength depends more strongly on the number of sequences in the dataset than it does on the sequence length, but that the dependence on the number of sequences diminishes, after which adding more sequences does not reduce the false-positive rate significantly. We compare our theoretical predictions by applying four popular motif-finding algorithms that solve the one-occurrence-per-sequence problem (MEME, the Gibbs Sampler, Weeder, and GIMSAN) to simulated data that contain no motifs. We find that the dependence of false positives detected by these softwares on the motif-finding parameters is similar to that predicted by our formula.We quantify the relationship between the sequence search space and motif-finding false-positives. Based on the simple formula we derive, we provide a number of intuitive rules of thumb that may be used to enhance motif-finding results in practice. Our results provide a theoretical advance in an important problem in computational biology.
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