1,721,884 research outputs found
Problems, prospects and possibilities of inclusive education for physically disabled children in Bangladesh
Get PDFThis thesis is submitted in partial fulfillment of the requirements for the degree of Masters of Science in Early Child Development, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (page 34 -37).Md. Abdullah Al ZubayerM. Early Child Developmen
Effect of Surfactant on Water Vapor Absorption into Aqueous Lithium Bromide
No full textThis thesis is submitted to the Department of Mechanical Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Mechanical Engineering, Septmber 2012.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 61-67).The objective of the present study is to investigate the absorbing characteristics of water vapor in LiBr-H2O (weak solution) and also the enhancement of absorption in presence of a surfactant in the absorber of a vapor absorption refrigeration system. It reveals from literature that the rate of absorption enhances for marangoni convection occurs due to inclusion of surfactant in the weak solution. An experimental setup for testing the effect of surfactant on the absorption of water vapor in LiBr-H2O solution in a Vapor Absorption Refrigeration (VAR) system is designed and constructed. The experiments were performed with four different concentrations of LiBr such as 45%, 50%, 55% and 60% in LiBr-H2O solution by weight and three different surfactant concentrations such as 100, 200 and 300 ppm in the weak solution. 2-ethyl-l-hexanol was used as surfactant in this experiment. From the experimental results it can be said that, the absorption of water is found to increase with the increase of concentration of LiBr in the weak solution of LiBr-H2O.The addition of surfactant enhances the absorption of water vapor. The
maximum enhancement of water vapor absorption is obtained when surfactant concentration is 300 ppm and LiBr concentration is 50% in LiBr-H2O weak solution by weight. Also the experimental results agree with the experimental results of Jung [68] et al. and Kim [65] et al. closely (the deviations of enhancement of present work are about 6.3% and 6.6% less than that work of Jung et al. and Kim et al. respectively).Md. Abdullah Al BariMaster of Science in Mechanical Engineerin
sj-docx-1-trr-10.1177_03611981231182927 – Supplemental material for Risk Perception of Vehicle-to-Vehicle Vendors and General Pedestrians: A Comparative Study
No full textSupplemental material, sj-docx-1-trr-10.1177_03611981231182927 for Risk Perception of Vehicle-to-Vehicle Vendors and General Pedestrians: A Comparative Study by Farhan Anjum Badhon, Shoumic Shahid Chowdhury, Tashdid Haque, Saifur Rahman, Md Asif Raihan, Moinul Hossain and Md. Abdullah Al Mamun in Transportation Research Record</p
Transcriptomic characterisation of NK cell subsets in anti-tumour immunity
No full text© 2025 Md Abdullah Al Kamran KhanNatural killer (NK) cells are key players in the innate immune system and are thought to play a pivotal role in immune surveillance of malignant cells and intracellular pathogens. Two major subtypes of circulating NK cells include the cytokine-producing CD56bright NK and the potently cytotoxic CD56dim NK populations. While NK cells contribute to direct tumour clearance and modulation of the broader tumour-immune landscape, the subset-specific roles of NK cells within the tumour microenvironment (TME) remains incompletely understood.
Here, I quantified the abundance of NK cell subsets across bulk tumour transcriptomes from The Cancer Genome Atlas (TCGA) using cellular deconvolution and examined their associations with clinical outcomes. I first developed transcriptional signatures for these NK subsets, alongside three stromal and eighteen immune cell types. By applying my Bayesian multilevel noise modelling method, cellsig, to pre-process the reference transcriptomes, I markedly improved marker gene selection and, consequently, deconvolution accuracy.
Further analyses revealed that the CD56bright NK cell signature was associated with favourable survival in bladder cancer (BLCA) patients. Transcripts coding activating NK cell receptors, such as KLRK1 (NKG2D), NCR2 (NKp44), and CD160 as well as their ligands, were also linked to improved BLCA prognosis. Using this approach, I identified a potential NK-dendritic cell-cytotoxic T lymphocyte (NK-DC-CTL) crosstalk axis, which may be of indicative of a coordinated immune response predictive of better BLCA clinical outcomes. In addition, I observed putative evidence for tissue-resident CD56bright NK and CD8+ effector memory T (TEM) cells marked by the transcription factor ZNF683 (HOBIT), which correlated with favourable prognosis.
In contrast, lower-grade glioma (LGG) was characterised by reduced abundance of human leukocyte antigen class I (HLA-I) and increased abundance of a gene signature of CD56dim NK cells that was correlated with improved patient survival. These suggest that elevated HLA-I expression could suppress the anti-tumour potential of cytotoxic NK cells in the LGG TME. Moreover, transcripts coding activating NK family receptors such as KLRK1 (NKG2D), KLRC2 (NKG2C), and KLRC3 (NKG2E) were positively associated with LGG prognosis, whereas upregulation of transcripts for HLA-E, ligand of inhibitory receptor NKG2A, were associated with poor LGG outcomes and thus may contribute to NK cell dysfunction in the LGG TME.
In summary, my work has used a computational approach to uncover the putative tumour-type specific roles of NK cell subsets, providing a foundation for future mechanistic investigations to better understand NK cell-mediated anti-tumour immunity that may inform the design of NK cell-based immunotherapeutic strategies in these settings
Floodplain avulsion channels: understanding their distribution and how they reconnect to the parent channel
Get PDF© 2018 Dr. Md Abdullah Al BakyThis study is concerned with new river channels that develop on floodplains. These channels can develop gradually, or they can develop more rapidly (avulsions). This study concentrates on the relatively more rapid channel changes known as avulsions. An avulsion specifies the gradual abandonment of an existing river-channel and in response to this, the processes of development of a new channel on a floodplain nearby.
The study addresses two specific knowledge gaps: 1) how common are river floodplain avulsions globally, and 2) what are the detailed processes that occur at the up and downstream points where avulsions connect to the main channel?
Using random sampling from a global spatial layer I discovered that developing avulsions are extremely common on alluvial floodplains globally, wherever the floodplain is wider than several channel widths. Avulsions are most common on single thread meandering floodplain types, but a review of avulsion literature shows that research is biased to relatively less common floodplain types. Avulsions increase the rate of valley widening, particularly in narrow floodplains. There is a relationship between floodplain width and the number of avulsion channels. The rest of the thesis is focussed in the major process knowledge gap which is how avulsion channels connect into the main channel at the up and downstream ends.
The focus of the process component of this study is the broad Murray river floodplain from Yarrawonga to Echuca, SE Australia. I mapped and classified developing channels on the floodplain and found that the avulsion connection point here develops in an unusual way, involving the development and coalescence of low points (depressions) on the levee (this mechanism is very different from normal crevasse splay development). The chain of low points on the alluvial levee coalesce to form a levee channel. Rather than forming by erosion as expected from the literature, form progressively by locally reduced vertical accretion. This identifies a new process by which topography is developed on floodplains. Initially the levee channels are not connected with the Murray main stream and slope away from the river. The connection occurs by lateral migration of the river bank into the levee channel, but also by progressive upslope (river ward) migration of the deepest part of the levee channel towards the river, narrowing the gap between the river and the levee channel. Following connection, the levee channel captures flow from the river, and hydraulic modelling shows that shear stress is sufficient to erode the upstream end of the levee channel. As the channel erodes the shear stress declines, but the proportion of back-flow from the flood recession increases. The result is that the slope of the levee channel reverses to slope towards the river. This is a new mechanism, and it is critical in the sequence of avulsion development. The final stage of the development of avulsion is when a knickzone moves up the levee channel joining another levee channel that is leaving the river upvalley. This is new mechanism of avulsion likely to operate in low energy river systems dominated by fine-grained sediments
Developing contraceptive and anticancer agents RAR ALPHA antagonists and pironetin analogs.
Get PDFUniversity of Minnesota Ph.D. dissertation. June 2023. Major: Chemistry. Advisor: Gunda Georg. 1 computer file (PDF); xx, 306 pages.Despite much interest in the male contraceptive pill, none has been approved yet. Gene knockout studies have validated retinoic acid receptor α (RARα) as a target for male contraceptive discovery. Male RARα knockout mice are sterile due to impaired spermatogenesis but show no observable phenotypic abnormalities. This indicates that inhibiting RARα function could produce a contraceptive effect without an inherent risk for side effects. Therefore, we aimed to develop a selective RARα antagonist as a safe, effective, and reversible male contraceptive agent with no off-target effects on RARβ and RARγ. We utilized the structural differences between RARα, β, and γ ligand-binding domains to achieve RARα selectivity. Additionally, the structural differences between RARα bound to the agonist and the antagonist facilitated the design of full antagonists. We also explored modification on many RAR ligand scaffolds, employing structural information obtained from ligand-bound crystal structures of RARs. Over 130 compounds were synthesized and evaluated for RARα antagonist activity and selectivity using a β-lactamase reporter assay. Through structural modifications, we were able to increase compound potency more than 20-fold. We also obtained several antagonists with high antagonistic potency for RARα and excellent selectivity over RARβ and RARγ. Once fully characterized for in vitro and in vivo PK properties, potent and selective antagonists could serve as preclinical candidates for male contraceptive discovery.Compared to non-covalent RAR antagonists, covalent antagonists could offer a longer duration of action at a lower dose due to their longer on-target residence time. Therefore, we developed several covalent RARα antagonists by targeting the nucleophilic C235 residue in the RARα ligand binding pocket with a novel 5-hydroxydihydrofuran-2(3H)-one warhead. By leveraging the structural difference between RARα and RARβγ, we prepared one pan-RAR antagonist and one RARα selective antagonist. Both compounds demonstrated reversible covalent binding with RARα and potent time-dependent antagonism in a cell-based assay. The RARα-selective covalent antagonist could serve as a promising candidate for in vivo evaluation.
We also prepared synthetic analogs of the natural product pironetin for anticancer application. Pironetin, a polyketide natural product, has shown anticancer effects by binding to α-tubulin and inhibiting tubulin polymerization. Despite the excellent in vitro cytotoxicity of pironetin against many cancer cell lines, it was not effective in an in vivo tumor model due to poor PK/PD properties and off-target toxicities. Our group previously identified major metabolites of pironetin, and we designed new analogs to block the site of metabolism by replacing the metabolically susceptible exocyclic double bond with phenyl and 4-fluorophenyl groups. We synthesized three analogs using 18-step stereoselective reactions and evaluated their cytotoxic potency using several ovarian cancer cell lines. Two analogs showed cytotoxicity comparable to pironetin yet lacked metabolic stability. concurrently, we also observed a linear trend between clogP and instability in liver microsomes, indicating that increasing the clogP of the analogs increased their metabolic susceptibility.Noman, Md Abdullah Al. (2023). Developing contraceptive and anticancer agents RAR ALPHA antagonists and pironetin analogs.. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/276805
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A comparative analysis of the effect of temperature on band-gap energy of gallium nitride and its stability beyond room temperature using Bose-Einstein model and Varshni\u27s model
No full textSlum women and their socio-economic characteristics: A study in Dhaka city
No full textAn estimated 3.4 million people live in the overcrowded slums of Dhaka. Among them a handsome amount of population is women. These slum women are considered as poorest of the poor. Because their household activities are not recognized as productive ones. Study shows that, they have limited access to urban facilities such as water, gas, electricity and sanitation. Apart from these, they are living in unhygienic environment and facing a lot of challenges in slum life. The study was conducted on 150 women living in 10 slums of Dhaka city out of 4500 based on survey method. Besides, the study also suggests some solutions to improve the overall situation of slum women
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