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Assessment of Potential Ecological Risks Associated with Heavy Metals in Soil of Waste Disposal Site at Khulna: A Spatial and Temporal Appraisal
No full textThis thesis is submitted to the Department of Civil Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Civil Engineering, November 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 142-157)Most of the ecological and health risk occurs due to the emission of heavy metal from contaminated soil of waste disposal site. The main focus of this study was to assess the ecological risk associated with heavy metals present in soil of waste disposal site. To these endeavors, sixty soil samples were collected from different locations of a selected waste disposal site at Rajbandh, Khulna, Bangladesh. This study period covered both, dry season (March to May, 2016) and rainy season (June to August, 2016). In the laboratory, metal elements of Aluminium (Al), Arsenic (As), Barium (Ba), Calcium (Ca), Cadmium (Cd), Cobalt (Co), Chromium (Cr), Copper (Cu), Iron (Fe), Mercury (Hg), Potassium (K), Manganese (Mn), Sodium (Na), Nickel (Ni), Lead (Pb), Antimony (Sb), Scandium (Sc), Strontium (Sr), Titanium (Ti), Vanadium (V) and Zinc (Zn) in soil was measured through standard test methods. In this study, to assess the ecological risks associated with heavy metals various indices such as potential contamination index (Cp), contamination factor (CF), contamination load index (PLI), modified contamination degree (mCD), numerical integrated contamination factor (NICF), enrichment factor (EF), geo-accumulation index (Igeo), ecological risk index (ER) and potential ecological risk index (PERI) were used. In addition, Pearson’s correlation and principal component analysis (PCA) was performed using SPSS and XLSTAT.
The results of skewness and kurtosis revealed that the heavy metals in soil were normally distributed for both seasons. The soil sample collected from center of disposal site showed comparatively the higher concentration than the other soil samples from larger distances with respect to center of the disposal site for both seasons. Results indicated the level of contamination for soil was severe or very severe based on Cp for Cd and Sb for both seasons as well as Pb and As for dry season. In addition, CF for Cd and Sb showed very high level of contamination in both seasons. Additionally, CF for Pb and As showed moderate to considerable contamination in dry season; where, CF for same elements showed moderate to low contamination in rainy season. The results of EF for Pb, Zn, Cd, As, Hg, Co and Sb contributed the class of extremely severe enriched for dry season. Mainly, EF for Sb and Cd indicated the soil was extremely severe enrichment for dry and rainy season. Besides, ER for Cr, Cu, Pb, Zn, Ni, As, Hg and Co; and ER for Cd indicated the slightly ecological risk and extremely strong ecological risk, respectively, for dry season. Moreover, PERI for entire soil samples indicated the extremely strong ecological risk. It was observed that the soil sample of the central point of the disposal site showed comparatively the higher potential ecological risk than other soil samples collected from larger distances with respect to center of the disposal site for both seasons.
Results of Pearson’s correlation and PCA indicated that most of the heavy metals were found to correlate significantly with each other indicating close association of these parameters in both seasons. The spatial distribution of heavy metals represented the same pattern for both seasons but the intensity of heavy metals decreases in relation to the increasing of lateral distance from the center of disposal site. Finally, it can be concluded that the outcome of this study will help to know the degree of contamination of soil as well as the ecological risk from the contaminated soil of a selected waste disposal site.Kanij FahmidaMaster of Science in Civil Engineerin
Study on Effect of Energy Fluxes in Relation to the Movement and Intensity of Tropical Cyclones in the Bay of Bengal
No full textThis thesis is submitted to the Department of Physics, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Physics, February, 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 88-92).Comprehensive sensitivity analysis on physical parameterization schemes of Weather
Research and Forecasting model (WRF v3.2.1) have been carried out for the effects of energy
fluxes on the prediction of track and intensity of Tropical Cyclone Roanu, Hudhud and Mala
those formed in the Bay of Bengal and crossed Bangladesh, Visakhapatnam of India and
Myanmar coast during May 2016, October 2014 and April 2006 respectively. The initial and
boundary conditions of tropical cyclone (TC) are drawn from the global operational analysis
and forecast products of National Center for Environmental Prediction (NCEP-GFS)
available for the public at 1°×1o resolution. The model was run by using Kessler (KS), Lin et
al. (Lin), WSM3-class simple ice, Ferrier (FE), WSM6-class graupel and Thomson (TH)
graupel microphysics (MP) schemes coupling with different cumulus parameterization (CP)
schemes and different initial conditions. Kain-Fritsch (KF) and Betts-Miller-Janjic (BMJ)
schemes have been used to study the effects of energy fluxes on the track of TC. The model
domain consists of 8-24oN and 77-96oE and has 12 km horizontal resolution with 28 vertical
sigma levels. The model was run for 96 and 72-h using initial conditions at 0000 UTC of 18
and 19 May 2016 for TC Roanu, 120 and 96-h using initial conditions of 0000 UTC of 8 and
9 October 2014 for TC Hudhud, and 120 and 96-h using initial conditions of 0000 UTC of 26
and 27 April 2006 for TC Mala. To examine the effect of energy fluxes on the movement of
TC we have considered five different regions inside the model domain. The regions are R1
(22-26oN & 87-93oE), R2 (18-22oN & 81-85oE), R3 (14-18oN & 78-84oE), R4 (12-22oN & 85-
94oE) and R5 (17-22oN & 94-97oE). In this research the Convective available potential energy
(CAPE), Convective inhibition (CIN), Downward long wave heat flux (DLHF), Downward
shortwave heat flux (DSHF), Ground heat flux (GHF), latent heat flux (LH), moisture heat
flux (QFX), Outgoing long wave radiation (OLR), and upward heat flux (HFX) have been
analyzed in R1, R2, R3, R4 and R5 to observe the impact of these parameters for the
movement of TC. The vertically integrated space averaged CAPE, CIN, DLHF, DSHF, OLR
have found to decrease continuously for all MPs in combination with KF and BMJ schemes
in a region where TC moves. These parameters have decreased for TC Roanu in R1, for TC
Mala in R5 and TC Hudhud in R2. The QFX and LH have been increased in a region where
TC moves.Kaniz FatemaMaster of Science in Physic
Effect of N-Acetylcysteine on Volumetric and Viscometric Properties of Chitosan in Aqueous Acidic Solution
No full textThis thesis is submitted to the Department of Chemistry, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Philosophy in Chemistry, December 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 115-121).Volumetric and viscometric studies of Chitosan-H20-CH3COOH and NAC (NAcetylcysteine)-Chitosan-[H20-CH3COOH] systems were investigated at 298.15 to 323.15 K at 5 K intervals. In a]l investigated systems concentrations of NAC were 0.10,0.50 & 1.00 mol.L' and concentrations of chitosan were 0.003, 0.006 & 0.012 mol.L* H20-CH3COOH mixed solvent was used for the experiment and H20 to CH3COOH ratios 9:1, 7:3 and 3:2 were maintained.
Densities have been found to be increased with increasing concentration of both NAC
and chitosan but decreased with increasing temperature. Densities were found to be
increased with increasing the ratio of CH3COOH in Chitosan-H20-CH3COOH systems
but this trend was not so significant is case of NAC-Chitosan-H20-CH3COOH systems.
Density Values of NAC-Chitosan-[H20-CH3COOH] systems were remarkably higher
than those Chitosan-H20-CH3COOH systems.The apparent molar volumes, φv of both Chitosan-H20-CH3COOH and NACChitosan-H20-CH3COOH systems were determined from the experimental density values data at 298.15 to 323.15 K at 5 intervals. The φv values were dependent upon
concentration of NAC and chitosan in mixed solvents as well as the temperature. φv values have been found to be positive in all investigated systems. The φv values
decreased throughout the whole concentration range for NAC and chitosan in their
specific solvent systems. These results may be due to the solute—solvent, and
solute—solute interaction through dipole-dipole interaction, ion-dipole interaction,
hydrogen bond, hydrophilic or hydrophobic interaction among NAC, chitosan and
aqueous acetic acid in the solutions. Besides, φv values were found to be increased
with increasing temperature at any concentration of NAC and chitosan in solutions and
this is may be due to increased thermal agitation at higher temperatures.
Apparent molar volume at infinite dilution, φvo; apparent molar expansivity and Sv
values were also determined. The φvo; values of chitosan-[H20-CH3COOH] systems
decreased with increasing temperatures and increased with increasing the ratio of
CH3COOH in H20-CH3COOH mixed solutions. At elevated temperatures cages in the
investigated systems becomes less important hence the apparent molar volume at
infinite dilution, φv3 decreased with increasing temperature. in addition, incorporation
of more acetic acid ratio in Chitosan-H20-CH3COOH system hydrophobic-hydrophobic repulsion predominant over hydrogen bonding or dipole-dipoleinteraction. The apparent molar volume at infinite dilution gives an idea about the presence of solute—solvent interactions. The expansivity values are positive at all the investigated temperatures. Positive values indicate that, on heating some NAC and chitosan molecules may be released from the solvation layer of ion. It may also be
conferred that the positive φEo;values may be originated from the hydrophobic
character and steric effect of the NAC and chitosan in systems. As a whole there is a
hydrophilic/hydrophobic balance among the solute and solvent molecules. S
parameters contribute an idea about the prevailing solute—solute interactions in the
mixtures. The negative and large in magnitude values of Sv in all investigated systems
supports the weak solute-solute interaction present.
Both Chitosan-H20-CHICOOH and NAC-Cli itosan-H20-CH3COOH systems showed
rapid increase of viscosity values with the increase of chitosan and NAC concentrations
but viscosities decreased with the increase of temperature. The increase of η
values of with concentration of chitosan and NAC can be attributed to the increase in
solute—solvent, and solute—solute interactions in solution. The small range of
dissolution of chitosan and/or NAC in H2 0-Cl-13C00H might have intriguing aspects
which may be the consequence of the great ability of H20 and Cl-13C00H to make
hydrogen bond and dipole-dipole, ion-dipole interaction. In all cases with the increase
of temperature internal energy of the systems increased as a result solute-solute or
solute-solvent interaction may be depleted and viscosity values decreased.
The viscosity data were employed to determine A and B-coefficients; change of free
energy, ∆G*; change of enthalpy. ∆H* and change of entropy,∆*. From these
thermodynamic parameters state of the spontaneity of the investigated systems were
known. Besides, negative A and positive B co-efficient suggesting that weak solute solute
but strong solute-solvent interaction present. The change of free energy values
for viscous flow,∆G* were found to be positive indicate that work has to be done to
overcome the energy barrier for the flow process. The positive AH values indicate that
work has to be done for all the investigated systems. The ∆S* values are negative for
all the systems studied. This means that Chitosan-[H20-GH3COOH] and NACChitosan-[H20-CH3COOH]systems are regular than those of the pure one. Here one
point may be remarked that as ∆S 0, so the processes are never
spontaneous but the reverse process is always spontaneous.Md. Abul KashemMaster of Philosophy in Chemistr
Capacitance-Voltage Characterization of Ultra Scaled XOI FET: An Analytical Approach
No full textThis thesis is submitted to the Department of Electrical and Electronic Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Electrical and Electronic Engineering, July 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 51-58).Device scaling is the key factor that drives the microelectronics revolution as
described by Moore’s law. Reduction of the physical MOS device dimensions has been
proved beneficial in terms of circuit speed, cost and power consumption. But the continued
miniaturization of the MOS transistor imposes a lot of challenges in terms of device design.
Addressing to this issue “Compound semiconductor-on-insulator” was reported in 2010,
which is also termed as XOI. III-V materials can be considered as the perfect replacement of
silicon as the channel material in MOS devices due to their excellent transport properties. It is
well established that the capacitance – voltage (C-V) measurement is widely accepted
technique for different device parameter extraction and also to measure the interface quality
of a fabricated MOSFET. An analytical model is developed here using quantum mechanical
approach to explain the C-V characteristics of XOI FET by solving coupled Schrodinger-
Poisson equation. It is found that the energy quantization effect in such short channel device
causes a unique staircase nature in the C-V characteristics for channel thickness up to 20nm.
Beyond that this nature disappear reproducing traditional C-V characteristics of SOI FET. It
is also seen that channel thickness and dopant impurity has an impact on the shift of C-V
curve. The threshold voltage of such devices is found higher at reduced channel thickness.Muhammad Mainul IslamMaster of Science in Electrical and Electronic Engineerin
