Jahangirnagar University Journal of Science

DRIFTS Studies and Quantification of Water uptake experiments onto Iron(II) fumarate, Polyguaiacol and Polycatechol particles

2025-07-31T14:01:09+06:00

This research investigates the hygroscopic properties of organic and organometallic polymeric
particles, namely Iron(II) fumarate, Polyguaiacol, and Polycatechol. These particles are efficiently
formed in iron-catalyzed reactions with aromatic and aliphatic dicarboxylic acid compounds which
were detected in field-collected Secondary Organic Aerosol (SOA). The structure of surface water
was studied using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS).
Spectroscopic data show that water bonding with organic functional groups acting as hydrogen bond
acceptors causes shifts in their vibrational modes. Analysis of the hydroxyl group stretching region
revealed weak and strong hydrogen bonding networks that suggest cluster formation reflecting
water-water and water-organics interactions, respectively. A modified Type II multilayer Brunauer
Emmett-Teller (BET) adsorption model described the adsorption isotherm on the materials, Fe
fumarate, polycatechol, and polyguaiacol. Modified BET analysis shows that multilayer adsorption
takes place for model organic compounds.

Synthesis of 2,3-dihydroquinazoline -4(H)-one Derivatives by Intramolecular Oxidative Coupling Reaction as Cytotoxic Agent

2025-11-10T00:58:11+06:00

A series of 2,3-dihydroquinazoline-4(H)-ones derivatives having fused with 9,10- dihydrophenanthrene were prepared by a three component condensation reaction of isatoic anhydride, primary amines and aromatic aldehydes followed by the intramolecular oxidative coupling reaction in the presence of nontoxic FeCl_3.This reaction involves dehydrogenative coupling of a various of 1,2-diarylethylene derivatives at temperature 0-5 ^oC. NMR and IR spectroscopy were used to characterize all the synthesized compounds and studied their cytotoxic property by Brine Shrimp Lethality Bioassay. Among these compounds, compound 2b and 3b showed moderate cytotoxicity with LC₅₀ values 76.16 and 70.70 µg/ml respectively.

Application of Extreme Value Analysis in Epidemiology: Modeling Dengue Prevalence Extremes

2025-08-29T21:08:24+06:00

This study explores the application of Extreme Value Theory (EVT) to epidemiology, demonstrating its capability to model rare but impactful disease prevalence events. Using monthly dengue prevalence in Bangladesh (January 2008–September 2023) as a case study, the objectives are to: evaluate the suitability of the Generalized Pareto Distribution (GPD) for capturing upper-tail behavior in epidemiological data, assess an automated threshold selection method based on the Anderson–Darling statistic and L-moments estimation (AD-L), and examine the impact of dataset extension on model performance and uncertainty. Non-stationarity is addressed by fitting a Seasonal ARIMA (SARIMA) model, with residuals used for GPD modeling. Return levels for 5-, 10-, and 20-year periods are estimated and expressed on the original prevalence scale, with 95% confidence intervals obtained via bootstrap resampling. A hybrid simulation framework generates synthetic series (N = 500) replicating observed trend, seasonality, and tail features to assess the effect of increased sample size. Results show that the GPD, combined with the AD-L method, effectively models heavy-tailed residual extremes, while simulated data improve goodness-of-fit metrics substantially. However, the scarcity of exceedances limits reductions in return level uncertainty. This work demonstrates a novel, data-driven application of EVT to infectious disease prevalence, offering a transferable framework for epidemiological risk assessment.

Transient temperature distribution in Human Skin during burn injury using The Finite Element Method with Bio-Heat Equation

2024-11-28T10:08:20+06:00

Human skin is exposed to high thermal energy due to solar radiation, contact of a hot disk, contact of hot fluid etc. This high thermal energy may result in the thermal burn. Depending upon the excess thermal energy and exposure duration, burn injury can be severe and may lead to damage of the skin. Prior knowledge of the temperature distribution in the skin burn is thus necessary for the proper treatment of the skin burn injuries. In this study a 2D Finite Element (FE) model of human skin in contact with a heating disk is developed. Natural convection to ambient air and evaporation boundary condition is considered to the area that is not in direct contact with the heating disk. Whether, temperature boundary condition is considered at the body core. A C-code is developed for the solution of the finite element model. Linear and quadratic triangular element is used for the analysis. FEM result was compared with commercial numerical solver (COMSOL-Multiphysics) and boundary element method. A good agreement was found. Both steady and transient temperature is measured. The effect of various parameters i.e. ambient temperature, ambient heat transfer coefficient, blood perfusion, evaporation rate, disk temperature is briefly discussed.