Microbial Electrochemical System: extracellular electron transfer from photosynthesis and respiration to electrode

The electrochemical communication between microorganisms and electrodes has substantial implications both for basic understanding of biological electron transfer as well as in diverse applications, such as, microbial electrochemical system (MES), microbial biosensors and in production of valuable chemicals. In these systems the extracellular electron transfer (EET) from microbial metabolism to electrodes is restricted due to the insulated cellular exterior made of lipid structures. To obtain the electrochemical wiring of biomaterials with electrodes, osmium redox polymers (ORPs) was used as an efficient electron transfer (ET) mediator. In this thesis a systematic study on EET from a variety of biomaterials is demonstrated. The EET from the most metabolically versatile purple bacterium, i.e., Rhodobacter capsulatus, grown under both heterotrophically and photoheterotrophically conditions was studied. Shewanella oneidensis MR-1 is a metal ion reducing bacterium and was highly studied in microbial electrochemical systems (MES) due to its direct ET competence. We have shown that S. oneidensis MR-1 can be coupled with ORP modified graphite electrodes that results in an enhanced current density. A secured supply of cost effective sustainable energy is on of the greatest challenges in the 21st century. Biological photovoltaics (BPVs) is emerging as a potential energy generating technology to convert solar energy into electrical energy. To harness solar energy we studied the photo-excited EET from water oxidation via thylakoid membranes, the site of photosynthesis in green plants and algae. In addition three prokaryotic cyanobacteria, two different Leptolyngbya sp., and Chroococcales sp. were photo-electrochemically wired with electrodes. The photo-electrochemical communication of a multicellular eukaryotic alga was assumed to be challenging, since here photosynthesis occurs in a specially designed subcellular organelle called chloroplast. We have shown the photoelectrochemical communication of the eukaryotic alga, Paulschulzia pseudovolvox immobilized on a graphite electrode wired with ORPs. Although a great deal of research is focussed on MES, however, to seek any potential practical application their performance due the low power output and restricted stability need to be improved many folds. Our findings could have substantial implications in MES, such as microbial fuel cells (MFC), microbial biosensors, photosynthetic energy generation and in other light sensitive bioelectrochemical devices

Cyber Defense Remediation in Energy Delivery Systems

The integration of Information Technology (IT) and Operational Technology (OT) in Cyber-Physical Systems (CPS) has resulted in increased efficiency and facilitated real-time information acquisition, processing, and decision making. However, the increase in automation technology and the use of the internet for connecting, remote controlling, and supervising systems and facilities has also increased the likelihood of cybersecurity threats that can impact safety of humans and property. There is a need to assess cybersecurity risks in the power grid, nuclear plants, chemical factories, etc. to gain insight into the likelihood of safety hazards. Quantitative cybersecurity risk assessment will lead to informed cyber defense remediation and will ensure the presence of a mitigation plan to prevent safety hazards. In this dissertation, using Energy Delivery Systems (EDS) as a use case to contextualize a CPS, we address key research challenges in managing cyber risk for cyber defense remediation. First, we developed a platform for modeling and analyzing the effect of cyber threats and random system faults on EDS\u27s safety that could lead to catastrophic damages. We developed a data-driven attack graph and fault graph-based model to characterize the exploitability and impact of threats in EDS. We created an operational impact assessment to quantify the damages. Finally, we developed a strategic response decision capability that presents optimal mitigation actions and policies that balance the tradeoff between operational resilience (tactical risk) and strategic risk. Next, we addressed the challenge of management of tactical risk based on a prioritized cyber defense remediation plan. A prioritized cyber defense remediation plan is critical for effective risk management in EDS. Due to EDS\u27s complexity in terms of the heterogeneous nature of blending IT and OT and Industrial Control System (ICS), scale, and critical processes tasks, prioritized remediation should be applied gradually to protect critical assets. We proposed a methodology for prioritizing cyber risk remediation plans by detecting and evaluating critical EDS nodes\u27 paths. We conducted evaluation of critical nodes characteristics based on nodes\u27 architectural positions, measure of centrality based on nodes\u27 connectivity and frequency of network traffic, as well as the controlled amount of electrical power. The model also examines the relationship between cost models of budget allocation for removing vulnerabilities on critical nodes and their impact on gradual readiness. The proposed cost models were empirically validated in an existing network ICS test-bed computing nodes criticality. Two cost models were examined, and although varied, we concluded the lack of correlation between types of cost models to most damageable attack path and critical nodes readiness. Finally, we proposed a time-varying dynamical model for the cyber defense remediation in EDS. We utilize the stochastic evolutionary game model to simulate the dynamic adversary of cyber-attack-defense. We leveraged the Logit Quantal Response Dynamics (LQRD) model to quantify real-world players\u27 cognitive differences. We proposed the optimal decision making approach by calculating the stable evolutionary equilibrium and balancing defense costs and benefits. Case studies on EDS indicate that the proposed method can help the defender predict possible attack action, select the related optimal defense strategy over time, and gain the maximum defense payoffs. We also leveraged software-defined networking (SDN) in EDS for dynamical cyber defense remediation. We presented an approach to aid the selection security controls dynamically in an SDN-enabled EDS and achieve tradeoffs between providing security and Quality of Service (QoS). We modeled the security costs based on end-to-end packet delay and throughput. We proposed a non-dominated sorting based multi-objective optimization framework which can be implemented within an SDN controller to address the joint problem of optimizing between security and QoS parameters by alleviating time complexity at O(MN2). The M is the number of objective functions, and N is the population for each generation, respectively. We presented simulation results that illustrate how data availability and data integrity can be achieved while maintaining QoS constraints

SME Financing and Entrepreneurship Development in Bangladesh: An Impact Analysis

The current study has examined 41 SMEs financed by BASIC Bank to evaluate the impact on entrepreneurship development. The study evaluates the entrepreneurship development of the sample enterprises through  variables like, sales growth, return on investment, assets turnover and profit margin. The study found that by taking loans from BASIC Bank the sample enterprises have been able to increase their sales, profit, assets and the like. Thus, the findings of the study show that firms that receive bank loans can significantly increase their performance. The regression analysis also depicted the significance of the impact of financing on entrepreneurship development of selected SMEs. The study also highlighted several areas where BASIC bank’s assistance programs create positive effect like, improved profitability, higher level of output, increased sales, increased productivity, increased employment and the like. Keywords: Productivity, Profitability, Financial assistance, Entrepreneurship Development. DOI: 10.7176/EJBM/11-4-0