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Studies on Microbial Electrochemical Cells Using Different Anode Respiring Bacteria

Thesis Info

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Author

Khan, Qaiser Farid

Program

PhD

Institute

Quaid-I-Azam University

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2016

Thesis Completion Status

Completed

Subject

Natural Sciences

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/2932/1/Full%20thesis%20_%20Hard%20Bind%20.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727304287

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Microbial electrochemical cell (MXC) technology is a source of sustainable energy which comes from microorganisms. Recent advances in the fields of electromicrobiology and electrochemistry with focus on microbial electrolysis cells (MECs) has earned this technology its name as alternate “green energy”. Despite advances, this technology is still facing challenges to address low power and current density output. Thermoanaerobacter pseudethanolicus 39E (ATCC 33223), a thermophilic, Fe(III)-reducing, and fermentative bacterium, was evaluated for its ability to produce current from four electron donors xylose, glucose, cellobiose, and acetate with a fixed anode potential (+ 0.042 V vs SHE) in a microbial electrochemical cell (MXC). Under thermophilic conditions (60 °C), T. pseudethanolicus produced high current densities from xylose (5.8 ± 2.4 Am −2 ), glucose (4.3 ± 1.9 A m −2 ), and cellobiose (5.2 ± 1.6 A m −2 ). It produced insignificant current when grown with acetate, but consumed the acetate produced from sugar fermentation to produce electrical current. Low-scan cyclic voltammetry (LSCV) revealed a sigmoidal response with a midpoint potential of −0.17 V vs SHE. Coulombic efficiency (CE) varied by electron donor, with xylose at 34.8% ± 0.7%, glucose at 65.3% ± 1.0%, and cellobiose at 27.7% ± 1.5%. Anode respiration was sustained over a pH range of 5.4−8.3, with higher current densities observed at alkaline pH values. Scanning electron microscopy showed a well-developed biofilm of T. pseudethanolicus on the anode, and confocal laser scanning microscopy demonstrated a maximum biofilm thickness (Lf) greater than ~150 μm for the glucose-fed biofilm. Microbial electrochemical cells (MXCs) are devices powered by microorganisms to generate electricity via oxidation of organic substrates. It is critical to understand the significance of sediment inocula in forming anodic biofilms to improve MEC performance. Five environmental samples were evaluated for electrical current production using acetate-fed microbial electrolysis cells (MECs). Three of these samples were able to produce significant current densities ranging between 3 to 6.3 Am -2 . 16S rDNA targeted deep sequencing comparisons of anodic biofilms and sediment bacterial community structures revealed significant differences in bacterial community structures. Bacterial community producing the highest current density ixafter enrichment was dominated by the class Bacteroidia, δ-proteobacteria and Erysipelotrichi. Comparison of phylogenetic information of bacterial communities with 7 previously reported enriched samples by reconstruction of unobserved states (PICRUSt) analysis clearly distinguished the biofilm communities from the sediment inocula in terms of higher abundance of genes related to anode respiration. Principal Coordinate Analysis (PCoA) also indicated that the clustering of biofilm communities was in accordance with the predominant genera in each sample, such as Geobacter dominating one cluster of biofilms. All the sediments formed a single cluster, which included the Carolina mangrove biofilm community which showed only minor changes from its originating sediment community after enrichment. Predominantly, high current densities are associated with the enrichment of a few microorganisms, often within a single family; however, this organism can be different depending on the inoculum source. Because the selective enrichment selects for just a few bacteria, the biofilm community is significantly different from that of the sediment. While δ- proteobacteria (or the family Geobacteraceae) is dominant in many samples producing high current densities, other samples show communities with yet unidentified ARB as the major fraction.
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اطہرؔ صدیقی

اطہرؔ صدیقی(۱۹۳۵ء۔پ) کا اصل نام محمدیسیٰن صدیقی اور اطہرؔ تخلص کرتے تھے۔ آپ چوہان حال برہان پور تحصیل پسرور میں پیدا ہوئے۔ آپ معروف شاعر پروفیسر حفیظ صدیقی کے بھائی تھے۔ حفیظ صدیقی کی راہنمائی میں اطہر نے زمانہ طالب علمی میں شاعری کا آغاز کیا تو ان کا کلام ملک کے معروف ادبی رسائل و جرائد میں شائع ہونے لگا۔(۹۱۶)

اطہرؔ کا پہلا شعری مجموعہ’’ کاکل غم‘‘ غزلوں اور نظموں پر مشتمل ہے جو۱۹۸۷ء میں شائع ہوا۔دوسرامجموعہ کلام’’ذوق سفر‘‘ کے نام سے ۱۹۸۹ء میں صدیقی پبلی کیشنز لاہور سے طبع ہوا۔ یہ مجموعہ غزلیات پر مشتمل ہے۔ تیسرا شعری مجموعہ’’آبرؤے غم‘‘۱۹۹۰ء میں صدیقی پبلی کیشنز لاہور سے شائع ہوا۔ یہ مجموعہ بھی غزلیات پر مشتمل ہے۔ چوتھا شعری مجموعہ ’’گردِ مسافت‘‘غزلیات اور نظموں پر مشتمل ہے۔

اطہر ؔصدیقی کی شاعری کا بڑا موضوع عظمت انسان ہے ۔وہ اپنی شاعری میں حضور ؐ کی ذات اقدس کے شیدائی نظر آتے ہیں۔ ان کے نزدیک حضرت محمدؐ کی ہستی عظمت انسان کی علامت ہے۔ اور وہی مثالیِانسان کا نمونہ ہیں۔انھوں نے نعت میں ہی نہیں بلکہ اپنی نظم اور غزل میں بھی عظمتِ انسان کی حقیقت کا اظہار کیا ہے:

ذرے ذرے سے پوچھ دیکھا ہے

 

-دشت در دشت کون رہتا ہے

 

5کون رہتا ہے لا مکاں میں اب

 

3کس کی رعنائیوں کا چرچا ہے

(۹۱۷)

ƒاطہرؔ کی شاعری عزم و ہمت ،جوش ،جواں جذبوں ،جستجو اور بلند حوصلوں سے بھر پور شاعری ہے ۔وہ اپنی شاعری میں کہیں بھی پست ہمت نظر نہیں آتے۔ان کے ہاں جوش اور جذبات کی شدت قاری کے حوصلے کو بلند...

QUALITY OF LIFE AMONG PHYSICALLY DISABLED FEMALES IN BACKWARD AREAS OF PAKISTAN

Background and Aim: Social discrimination is one of the most fatal and important source of hindrance for women causing them depressed. The aim of this research study was to find important information on QOL of physically disabled women of backward areas (Triple discriminated population of Pakistan). Methodology: The current research was conducted at PRSP, D.I.Khan through Cross sectional survey. Sample size for current study was 300 and SF-36 was used to measure QOL. Data was analyzed by using SPSS 22. Results: The measured mean age of the sample was 27.07 ± 11.10 years. Only 22% of the participants were married. Only 10 3.3% of the participants, completed their tertiary education. The overall SF-36 score was 47.07 ± 12.78. the domains like Physical functioning was 41.33 ± 20.38, Role physical 31.66 ± 35.61, Body pain 74.77 ± 24.06, General health 44.91 ± 14.12, Energy/fatigue 43.16 ± 16.01, Social functioning 49.37 ± 19.80, Role emotional 30.77 ± 36.53, and Mental health 45.97 ± 13.71. This study shows that education has significant impact on the QOL. Conclusion: Physical disability has visible effects on quality of life of Female PWDs. In PWDs management, quality of life needs to be focused in Rehab program for more effective approach.

Numerical Methods for Phase-Field Model and its Applications to Multi-Phase Flow

Numerical Methods for Phase-field Model and its Applications to Multi-phase Flow Numerical methods for solving partial differential equations (PDEs) were used first by John von Neumann in the mid of 1940s as an effective tool. Since then, numerical computing has become the most versatile tool to experiments and complement theory. In principle, all mathematical equations can be easily solved numerically in comparison to the theoretical approach. They are low cost, high efficiency and no danger when compared with experimental approach. The driving force of numerical methods comes from practical application in all branches of science, engineering and other disciplines. The starting point of computational methods is a mathematical model, the form and origin of which depends on the particular field of study. There exist many important physical and biological processes in nature that can be represented by mathematical models. However, a physical and mathematical interpretation of the models and their numerical solutions is always a vital part of the computational science. Although, analytical solutions are difficult to obtain for many complex phenomena governed by nonlinear PDEs. However, with the rapid development in computational techniques and availability of high-speed computers, there is a continuously widening scope of nonlinear problems that can be solved numerically. Appropriate numerical algorithms, in particular those for solving time-dependent nonlinear PDEs are in heart of many of advanced scientific computations and software development. Moving free boundary problems are present in nature and many areas of physical and biological sciences. Examples include impact of a droplet on a solid surface, image segmentation, surface waves, jet breakup, realistic interfaces in animation movies, crystal and tumor growth and many others where the simulation of moving interfaces plays a key role in the problem to be solved. In dealing with moving boundary problems, an important consideration is how to model the moving boundary or interfacial surface on which the boundary conditions are imposed. Mathematical models adopted both in analytical and numerical studies for variety of free boundary problems are classified into two types, sharp interface and diffuse interface models. Sharp interface models like (level set method ) assumes that the interface has zero thickness. However, in phase transition, the existence of transition zone introduced an idea of diffuse interface by Gibbs, which allow the interface to have finite thickness. A type of diffuse interface model with particular interest is phase-field based model by the introduction of an order-variable representing the interface. In such approach, the phase-field variable is continuous as a function of space and time. Nevertheless, the partial differential equations describing the two-phase flow are highly nonlinear and numerical simulation is often necessary to solve them. This is why phasefield methods are numerically attractive with no tracking of interface explicitly but can be obtained as a part of the solution processes. This work deals with the development of numerical methods for solving phase-field models with some real world applications. There are several discretization method like finite difference method, finite volume method and finite element method etc. We have adapted the conforming finite element method for spatial discretization and have used different diagonally implicit schemes for time discretization. The performance of the proposed numerical algorithms in term of their accuracy and CPU time are demonstrated. The comparisons with analytical, experimental and numerical results are also provided for validation and verification of the computed results. The numerical simulations were carried out using DUNE-PDELab, which is a software tool for solving partial differential equations. This thesis is organized as follows: In chapter 1, an introduction of the phase-field models with some fundamental aspects and applications are given. Chapter 2 provides numerical methods with some discretization techniques and their modifications. Chapter 3 is based on the development of an efficient time stepping scheme for solving of 2ndorder nonlinear Allen-Cahn equation. Error estimates at different degrees of freedom are also provided using available exact solution. In chapter 4, the method developed in chapter 2 is further extended to solve 4th-order Cahn-Hillard equation with variable mobility. In chapter 5, a system of Allen-Cahn equation coupled with heat equation is solved with its application to dendritic crystal growth phenomena. Chapter 6 is based on the mathematical modeling and its numerical simulation of tumor hypoxia targeting in cancer treatment. Chapter 7 concludes this work with some future research directions.