Biodétection de Legionella pneumophila par biocapteur à photocorrosion digitale à base de peptide antimicrobien

La détection de bactéries pathogènes par culture microbienne est lente, nécessite un milieu de culture spécifique pour garantir la croissance de certaines souches bactériennes fastidieuses telle que Legionella pneumophila (L. pneumophila) et en plus pourrait ne pas déceler les bactéries viables mais non cultivables mais restant dangereuse en termes de pathogénicité. Par conséquent, l’usage de biocapteurs pour la détection de L. pneumophila serait, potentiellement, une approche attrayante permettant une détection précise et rapide. Cependant, la sensibilité et la spécificité des biocapteurs dépendent fortement des molécules de bioreconnaissance utilisées. Jusqu'à présent, différents ligands tels que les anticorps, les enzymes, les acides nucléiques fonctionnels (aptamères) et les bactériophages ont été utilisés comme éléments de bioreconnaissance. En raison de leur haute spécificité, Les anticorps de mammifères ont été largement employés pour le développement de divers biocapteurs. Cependant, les anticorps sont connus pour souffrir de la variabilité des lots produits et d'une stabilité limitée, ce qui réduit l'usage et la constance des performances des biocapteurs à base d'anticorps. Au cours des dernières années, les peptides antimicrobiens (PAM) ont été de plus en plus investigués pour des applications thérapeutiques en plus d’être considérés comme des ligands de bioreconnaissance prometteurs en raison de leur grande stabilité et leurs fortes réactivités aux bactéries. Dans le but d’améliorer les performances du biocapteur à DIP, notre hypothèse reposait sur l’usage de bioarchitectures à base de PAM à courte séquence pour une capture efficace des bactéries et une détection considérablement améliorée en raison du transfert de charge plus facilitée vers dans la biopuce à base de semiconducteur III-V. Dans la première phase du projet, nous avons évalué un biocapteur à DIP consistant en une puce d’arséniure de gallium/arséniure de gallium aluminium (GaAs/AlGaAs) fonctionnalisée par le warnericine RK pour la détection directe in situ de L. pneumophila dans l’eau. Nous avons démontré une détection linéaire de L. pneumophila pour des concentrations allant de 103 à 106 CFU/mL. De plus, le nombre relativement important d'interfaces constituant la bioarchitecture d’un tel biocapteur pourrait affecter sa reproductibilité et sa sensibilité. Dans ce cas, la couche de bioreconnaissance est plus mince (~ 2 nm) permettant une distance plus courte entre les bactéries et la surface du biocapteur, ce qui pourrait jouer un rôle important dans la promotion du transfert de charge entre les bactéries et la biopuce, et ainsi nous avons pu démontrer une détection efficace de L. pneumophila à une concentration de 2 x 102 CFU/mL. Cette configuration a permis d’atteindre des LODs de 50 et 100 UFC/mL, respectivement pour de légionnelle dans du PBS et collectées d’échantillons d’eau de tour de refroidissement. Nous avons observé une détection sélective de L. pneumophila sérogroupe 1 (SG1) comparé au sérogroupe 5 (SG 5). Les biocapteurs à photocorrosion digitale (DIP) en configuration sandwich PAM et Ab pourraient être une approche prometteuse pour développer un biocapteur à faible coût, hautement sensible et spécifique pour la détection rapide de L. pneumophila dans l’eau.Abstract: Culture based detection of pathogenic bacteria is time consuming, and needs specific culture medium to identify bacterial strains such as Legionella pneumophila (L. pneumophila) which does not flourish in typical growth medium. Culture based methods cannot detect viable but unculturable bacteria. Therefore, the detection of L. pneumophila with biosensors potentially could be an attractive approach enabling accurate and rapid detection. The sensitivity and specificity of biosensors depend critically on the biorecognition probes employed for the detection. Until now, different elements such as antibodies, enzymes, functional nucleic acids (aptamers) and bacteriophages have been utilized as biorecognition elements. Due to high specificity of antibodies, and the advanced technology of their production, mammalian antibodies have been widely investigated for the development of various biosensors. However, mammalian antibodies are known to suffer from batch-to-batch variation, as well as limited stability, which could reduce the consistent utility of the proposed biosensors. In recent years, antimicrobial peptides (AMPs) have been increasingly investigated for their therapeutic applications. At the same time, AMPs are considered as promising biorecognition ligands due to their high stability and multiple niches for capturing bacteria. The hypothesis was that AMP-based bioarchitectures allows for highly efficient capturing of bacteria, and the short length of the AMP would significantly enhance detection due to limited obstructive charge transfer in the charge sensing biosensor. In the first phase of the project, we investigated a warnericin RK AMP functionalized gallium arsenide/aluminum gallium arsenide (GaAs/AlGaAs) photonic biosensor for direct detection of L. pneumophila in water environments. This approach allowed for detecting a low to high concentration of L. pneumophila (103 to 106 CFU/mL) with a 103 CFU/mL limit of detection (LOD). In addition, a relatively large number of interfaces constituting the architecture of such biosensors could affect their reproducibility and sensitivity. A thinner biorecognition layer (~2 nm) resulted in a shorter distance between bacteria and the biosensor surface, which played important role in promoting charge transfer between bacteria and biochip. L. pneumophila was detected at concentrations as low of 2 x 102 CFU/mL. This configuration allowed the detection sensitivity of L. pneumophila as low as 50 CFU/mL and 100 CFU/mL in clean water and water originated from cooling tower, respectively, along with the selective detection of whole cell L. pneumophila serogroup 1 (SG1) and serogroup 5 (SG5). The proposed AMP and Ab conjugated sandwich architecture with digital photocorrosion (DIP) biosensors is a promising approach for developing low cost, highly sensitive and specific biosensors for rapid detection of L. pneumophila in water environments

Problematic Issues of E-Banking Management in Bangladesh

In Bangladesh, banking industry is getting mature to a great extent than earlier period. With the launching of internet the world has become a smaller one. Remarkable development in ICT has introduced a global revolution in banking sectors. Beside the every sector in social life it has rendered enormous impacts on banking sector. Internet together with other information and communication technologies are not only driving financial global economies but also transforming societies into knowledge-based economies around the world. As a third world developing country, Bangladesh is far behind to reach the expected level in global banking system. So it is our urgent need to upgrade its banking system. The main focus of this study is to examine the performance, problems and prospects of E-banking in Bangladesh. This paper is also aimed at to determine the present scenario of e-banking and banking sectors in Bangladesh and at the same time it demonstrated the scope and benefits of e-banking compared with the existing sector. The study is descriptive in nature. So this study has been done mainly based on secondary sources of data or information which sources included different published articles, books, newspaper, and websites. JEL Classification Code:  G2

Trade, productivity and welfare effects of regional integration in South Asia

The thesis examines the impacts of the South Asian free trade agreement (SAFTA) on trade, productivity, and welfare of the member countries. When theoretically relevant variables are controlled for, it is found that the agreement is not effective in creating intra-regional trade flows and improving productivity of the region. India and Nepal gain welfare in the long run, while the others lose. Deeper integration, embracing factor flows, is required to make the agreement fruitful

Machine Learning Assisted Ultra Reliable and Low Latency Vehicular Optical Camera Communications

Optical camera communication (OCC) has emerged as a key enabling technology for the seamless operation of future autonomous vehicles. By leveraging the supreme performance of OCC, the stringent requirements of ultra-reliable and low-latency communication (uRLLC) can be met in vehicular OCC. In this thesis, a rate maximization approach is presented to vehicular OCC that aims to optimize vehicle speed, channel code rate, and modulation order while adhering to uRLLC requirements. The reliability is modelled by satisfying a target bit error rate (BER) and latency as transmission latency. To improve transmission rate and reliability, low-density parity-check codes and adaptive modulation are adopted in this thesis. First, the rate maximization problem is formulated as an optimization problem aimed at determining vehicle speed, channel code rates, and modulation order given reliability and latency constraints. Even for a small set of modulation orders, this problem is mixed integer programming, which is NP-hard. To overcome the complexity of the NP-hard problem, the proposed optimization problem is modelled as a Markov decision process and then solved it distributively using multi-agent deep reinforcement learning (DRL). Then, the optimization problem is solved using the actor-critic DRL framework with Wolpertinger architecture. A deep deterministic policy gradient algorithm is employed to operate over continuous action spaces. The proposed model and optimization formulation are justified through numerous simulations by comparing capacity, BER, and latency. From the findings, it is clear that the multi-agent DRL framework in vehicular OCC leads to improved performance in terms of maximizing the communication rate while respecting uRLLC. This work constitutes a significant step towards addressing the challenges in vehicular OCC to respect uRLLC

Study on baseline characteristics and lipid profile abnormalities among type 2 diabetic patients attending urban diabetic care hospital, Bangladesh

Background: Altered levels of serum glycated hemoglobin (HbA1c) and lipid profile are prevalent in patients having type 2 diabetic mellitus (T2DM). Aim of the study was to investigate the relationship between serum HbA1c and lipid profile in T2DM to predict diabetic dyslipidemia.Methods: A structured questionnaire was filled up by each study subject to collect data according to study protocol including age, gender, BMI, BP, residential status, socio-economic status, educational status, physical activity, dietary habit, smoking and duration of diabetes. We collected blood samples from 270 type-2 diabetes mellitus (T2DM) patients aged 30-65 years after overnight fasting (10-12 hours). Then blood samples collected from T2DM patients were used to measure serum levels of HbA1c, fasting blood glucose (FBG), total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) were estimated by standard laboratory methods.Results: In this study, increased levels of fasting blood glucose (8.61 mmo/l), HbA1c (7.86%), TC (226.15 mg/dl), TG (193.34 mg/dl) and LDL (147.37 mg/dl), and decreased levels of HDL (40.36 mg/dl) were observed in T2DM patients. Moreover, the strong positive correlation of HbA1c levels with FBG, TC, TG, and LDL levels were found in this study. Besides, a very strong and significant negative correlation (R2=0.1822) between the serum levels of HbA1c and HDL were noted in this study.Conclusions: This study revealed a strong correlation between dyslipidemia and serum levels of HbA1c in T2DM patients