 Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 374 journals)
| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | | The end of the list has been reached or no journals were found for your choice. |
|
|
- Optical and Structural Study of the CZTS (Cu2ZnSnS4) Thin Film for Solar
Cell Derived from the Chloride-Based sol-gel Precursor Solution
Authors: M Rahman, MS Bashar, N Islam
Pages: 1 - 7
Abstract: Fabrication of environmentally safe C2ZnSnS4 (CZTS) photovoltaic thin films of pure kesterite state is crucial. We have prepared
CZTS thin films by sol-gel dip-coating process from chloride-based chemicals. After vacuum-annealed at 550°C, the optical and
structural characters of the films were further examined by UV–vis spectroscopy, X-ray diffraction (XRD), scanning electron
microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) methods. The CZTS films offered high optical absorption
(0.4x104cm-1) and nearly optimum bandgap energy (1.65e V). X-ray diffraction examination confirmed the kesterite structure of
films. Scanning electron micrograph affirmed the creation of jam-packed, condensed and granulated CZTS films. The thin film
displayed intermittent disposal of agglomerated particles with clear-cut edges. The energy dispersive X-ray spectroscopy study gave
the stoichiometric ratio as Cu: Zn: Sn: S= 2.2: 1.4: 1: 5.1. Dhaka Univ. J. Sci. 70(1): 1-7, 2022 (January)
PubDate: 2022-07-24
DOI: 10.3329/dujs.v70i1.60374
Issue No: Vol. 70, No. 1 (2022)
- An Econometric Analysis to Forecast the Food Grain Production in
Bangladesh by Using ARIMA and VAR Models
Authors: Md Mehedi Hossain, Murshida Khanam, Salma Akhter
Pages: 8 - 13
Abstract: In this study, an Econometric analysis has been conducted to identify the important factors that affect the food grain productions in
Bangladesh. Here, we have considered time series data for the years from 1989- 1990 to 2019-2020. Vector Autoregressive (VAR)
Model and Autoregressive Integrated Moving Average (ARIMA) model have been considered in this study. Both these models
have been considered to forecast the productions of food grains in Bangladesh. The forecasting performances of these two models
have been compared by using RMSE, MAE, and MAPE. It has been found that the VAR model is better than the ARIMA model to
forecast the food grain production. On the other hand, it has been come out from the analysis that there is no significant impact of
chemical fertilizer on the food grain production, but irrigation area has significant impact on the food grain production. Among the
three variables: food grain production, irrigation area and chemical fertilizer, there exists short run relationship. Dhaka Univ. J. Sci. 70(1): 8-13, 2022 (January)
PubDate: 2022-07-24
DOI: 10.3329/dujs.v70i1.60375
Issue No: Vol. 70, No. 1 (2022)
- The State of Healthcare Facilities to Provide Diabetes, Cardiovascular and
Chronic Respiratory Disease Related Services in Bangladesh
Authors: Gaylan Peyari Tarannum Dana, Sawkia Afroz
Pages: 14 - 21
Abstract: The rapid rise of diabetes, cardiovascular disease (CVD) and chronic respiratory disease (CRD) are causing serious challenges for
Bangladesh to achieve the sustainable development goal (SDG) target 3.4 by 2030. The study aims to describe the state of healthcare
facilities to provide diagnosis and treatment for diabetes, CVD and CRD related services in Bangladesh. This cross-sectional study
used data from 2017 Bangladesh Health Facility Survey (BHFS). A total of 406 health facilities providing all three services were
considered for this study. Findings of the study illustrated that there were rural-urban disparities in healthcare facilities to provide
diabetics, CVD, CRD related services. Diabetics and CRD related services were significantly higher in public healthcare facilities
of urban areas compared to rural areas (P <0.008 and P<0.001, respectively). Also, public health facilities of urban areas were more
likely to provide CVD related services compared to rural areas. While private healthcare facilities of urban areas were more likely
to provide CVD, CRD related services than rural areas. Private healthcare facilities of rural areas were in better condition to provide
diabetes related services than urban areas. However, the country is yet to attain optimal progress in the overall status of health sector.
Therefore, in order to cope up with the rising burden of diabetes, CVD and CRD and to minimize the burden of disease specific outof
pocket healthcare expenses, recommendations include strengthening and improving stewardship, improving quality of services
and improving monitoring as well as supervision of decentralized healthcare facilities. Dhaka Univ. J. Sci. 70(1): 14-21, 2022 (January)
PubDate: 2022-07-24
DOI: 10.3329/dujs.v70i1.60376
Issue No: Vol. 70, No. 1 (2022)
- Determination of Toxic Heavy Metal Contents of Some Selected Tropical
Fruits Grown in Industrial Areas of Bangladesh
Authors: Md Ashraful Islam, Maksuda Parvin, Md Fahad Bin Quader, Md Shakhawat Hossain
Pages: 22 - 27
Abstract: Fourteen tropical fruit items were collected from different industrial sites of the Dhaka and Chattogram region, Bangladesh to
determine toxic heavy metal contents. This study aimed at the assessment of the distribution of heavy metals (As, Pb and Cr) as well
as comparison of their level among different locations. The fruit items were analyzed for the quantification of the selected heavy
metals using Atomic Absorption Spectrophotometer (AAS). The range of lead, chromium and arsenic in the fruit items were 1.12
± 0.077 to 2.899 ± 0.013, 0 to 0.217 ± 0.005 and 0 to 0.078 ± 0.002 mg kg-1 respectively. It was revealed from the results that the
level of toxic metals (As, Cr) in almost all fruit samples were within tolerable limit whereas the level of Pd in all of the fruit samples
exceeded the acceptable limits of WHO standard value. It was also observed from the results obtained that the concentration of the
metals found in the samples from Dhaka regions were considerably higher than that of Chattogram. These metal contributors mainly
arising from anthropogenic sources including industrial wastes, automobile emissions, use of fertilizers, pesticides and herbicides in
agriculture, paints, sewage and waste disposal. The extended level of these metals causing environmental pollution is hazardous since
plants accumulate them. Subsequently, crops uptaking these heavy metals consumed by humans and animals which is detrimental to
health. It is therefore very important that necessary actions need to be taken to monitor the level of these deleterious elements in food
plants. In decision making, planning and risk assessing this present study will play significant role. Dhaka Univ. J. Sci. 70(1): 22-27, 2022 (January)
PubDate: 2022-07-24
DOI: 10.3329/dujs.v70i1.60377
Issue No: Vol. 70, No. 1 (2022)
- Mixed Ligand Binuclear Complexes of Copper(II) and Cadmium(II) with
Adenine and 1,4-Diazabicyclo[2.2.2]octane
Authors: Sumaia Abdullah, MS Rahman, AA Shaikh, Pradip K Bakshi
Pages: 28 - 33
Abstract: Mixed ligand binuclear complexes of Cu(II) and Cd(II) with adenine (Ade) and 1,4-diazabicyclo[2.2.2]octane (DABCO) have
been synthesized at a metal to ligands (M:L:L′) molar ratio of 1:1:1 in aqueous medium under ambient conditions. All synthesized
complexes are powdery solids of different colours, slightly soluble in hot water and decompose at high temperature. Characterization
of the complexes was accomplished using various analytical techniques, e.g. metal and chloride content analysis, Fourier transform
spectrophotometer (FT-IR), UV-visible spectrophotometer, magnetic measurement, and thermal analyses. The metal and chloride
contents analyses of the complexes reveal to their stoichiometry [M2Cl2(Ade)2(H2O)2(DABCO)]Cl2 [M = Cu(II) or Cd(II)]. Analytical
data suggests that they are homo metal symmetric binuclear complexes comprises of two [MCl(Ade)(H2O)] moieties in between
a DABCO molecule is N,N′-bridge bonded. The arrangements of the ligands around the metal centers are essentially tetrahedral
involving N(9) of deprotonated imidazole moiety, one Cl- ion, one oxygen from the water molecule and one tertiary N atom from
DABCO completing the coordination. Proton migration occurs from N(9) to the N(1) site resulting into a zwitterionic form of
adenine, additionally N(3) site of which is hydrogen bonded with the coordinated water molecule. Electrochemical redox behaviour
of Cu(II) in presence of adenine and DABCO in the aqueous medium was also studied. It exhibits quasi-reversible one-electron
transfer processes. Dhaka Univ. J. Sci. 70(1): 28-33, 2022 (January)
PubDate: 2022-07-24
DOI: 10.3329/dujs.v70i1.60378
Issue No: Vol. 70, No. 1 (2022)
- Simulation Based Temperature Profiling of Human Eye due to the Exposure of
LED Light
Authors: Md Ashiqur Rahman, Mamun Rabbani
Pages: 34 - 41
Abstract: The use of LED luminaries is increasing day by day and the traditional sources of light are being replaced by this semiconductor
technology. In this study, the interactions of Red, Green and Blue LED light with human-eye are considered to model the temperature
profile due to the attenuation in the ocular media. The simulation has been done using COMSOL Multiphysics 5.3. The results of the
study show that Blue LED light causes temperature rise more than the other two colours of light. At the tip of the corneal surface,
blue LED light causes the temperature to rise by 0.91⁰C whereas the rise of temperature for green and red LED are 0.85⁰C and
0.46⁰C respectively. However, the temperature at the posterior layers of the eye, sclera, choroid and retina undergoes little thermal
effects due to LED light owing to the fact that the heat-flux due blood flow is dominant in that region. Dhaka Univ. J. Sci. 70(1): 34-41, 2022 (January)
PubDate: 2022-07-24
DOI: 10.3329/dujs.v70i1.60379
Issue No: Vol. 70, No. 1 (2022)
- Composition of Energy Drink Samples in Bangladesh
Authors: Md Reazul Alam Refat, Polash Nandi, Mohammad Shoeb, Abida Sultana
Pages: 42 - 48
Abstract: The commercial energy drink samples of 10 different brands were analyzed to study the level of alcohol (if any), sodium benzoate,
caffeine, vitamin B, and carbohydrates content. Samples were degassed by ultrasonicator, and CO2 was found to be in a range of 1.27
± 0.05 to 4.10 ± 0.10 mL per 100 mL sample. The amount of caffeine, sodium benzoate, glucose, and vitamin B were studied by a
UV-Visible spectrophotometer. The wavelength of absorption maxima was 224, 272, 489, 445, and 292 nm, respectively, for sodium
benzoate, caffeine, glucose, vitamin B2, and vitamin B6. The correlation coefficients of the calibration curves were found to be
0.998, 0.992, 0.998, 0.997, and 0.989 for caffeine, glucose, sodium benzoate, vitamin B2 and vitamin B6, respectively. The alcohol
content was studied by gas chromatography equipped with a flame ionization detector. Ethanol was not found to be present in any
sample. The caffeine and sodium benzoate content in different samples was found in the range of 147.84 ± 0.53 to 846.78 ± 2.64 and
52.92 ± 6.23 to 1575.37 ± 4.99 μg/mL, respectively. The sugar content in different samples was found to be 16.16 ± 4.25 to 338.33
± 0.75 mg/mL. Vitamin B2 was found to be 13.21± 0.08 and 1.04 ± 0.002 μg/mL, respectively in Bacchus and Wild Brew samples
and Vitamin B6 was found to be 261.17 ± 8.38 and 115.88 ± 0.31 μg/mL in Red Bull and Bacchus samples, respectively. The pH of
the samples was found to be in the range of 2.79 ± 0.04 to 4.88 ± 0.04. Dhaka Univ. J. Sci. 70(1): 42-48, 2022 (January)
PubDate: 2022-07-24
DOI: 10.3329/dujs.v70i1.60380
Issue No: Vol. 70, No. 1 (2022)
- Assessment of Physico-Chemical Parameters of Water Samples Collected from
the Southern Part of Bangladesh
Authors: Mohammad Shoeb, Farhana Sharmin, Md Nazrul Islam, Lutfun Nahar, Rafiza Islam, Nargis Parvin
Pages: 49 - 57
Abstract: Bangladesh has a vast natural water resources. In order to determine the water quality parameters such as pH, EC, DO, BOD, TOC, ions
i.e., NO3-, SO42-, PO43- and heavy metals, thirty surface water samples were collected from the southern part of Bangladesh including
the coastal regions of Patuakhali district and Kuakata sea beach area during the dry season. The pH of water samples was ranged from
7.58 to 8.77 with an average of 8.15. The average conductivity value was 8.83±2 mS/cm. The average DO was 8.33±1.82 mg/L and
BOD was 0.31±0.03 mg/L. TOC was found between 0.78 and 1.78 mg/L with an average of 1.24 mg/L. The concentration of NO3
-,SO42-, PO43- was determined by ion chromatography and only sulphate ion was detected in a very low concentration. Water samples
from different sources were analysed for five metals by AAS and the concentrations of Pb, Cd, Mn, Hg and As were below 0.2, 0.01,
0.22, 0.001 and 0.005 mg/L, respectively. Dhaka Univ. J. Sci. 70(1): 49-57, 2022 (January)
PubDate: 2022-07-24
DOI: 10.3329/dujs.v70i1.60381
Issue No: Vol. 70, No. 1 (2022)
- Proximate Analysis of Melon Seeds Available in Bangladesh
Authors: Md Reazul Alam Refat, Mohammad Shoeb, Abida Sultana
Pages: 58 - 63
Abstract: The seeds of winter (wax gourd), long (bottle gourd) and large (pumpkin) melon were analyzed for nutritional parameters mainly
protein, fat/oil, carbohydrate, dietary fiber, protein, minerals and moisture and fatty acids composition. The double beam ultravioletvisible spectrophotometer was used for analysis of total sugar. The protein content was determined using the Kjeldahl method. An atomic absorption spectrophotometer was used to quantify minerals (Fe, Cu, and Zn). Fatty acid was analyzed by gas chromatography
(GC) equipped with a flame ionization detector (FID). From the proximate analysis, it was found that the winter melon (wax gourd)
seeds contain protein, oil, carbohydrate, soluble dietary fiber, moisture and ash content of 19.71, 16.46, 56.48, 3.10, 68.88 and 4.26
%, respectively. Similarly, long melon (bottle gourd) was found to contain 16.12, 13.61, 46.88, 2.2, 76.45 and 5.2% of protein, oil,
carbohydrate, soluble dietary fiber, moisture and ash, respectively. The contents of protein, oil, carbohydrate, soluble dietary fiber,
moisture and ash in large melon (pumpkin) seeds were found to be 29.64, 18.17, 55.32, 1.3, 79.53 and 5.12%, respectively. In mineral
analysis, iron, copper, and zinc contents were found to be 6.75, 0.62, and 6.10 mg/100g in winter melon; 7.8, 1.63, and 4.25 mg/100g
in long melon; and 13.95, 1.15, and 5.11 mg/100g in large melon, respectively. Dhaka Univ. J. Sci. 70(1): 58-63, 2022 (January)
PubDate: 2022-07-24
DOI: 10.3329/dujs.v70i1.60382
Issue No: Vol. 70, No. 1 (2022)
- Cu(II) Doped TiO2 for Photodegradation of Remazol Black B in Aqueous
Solution
Authors: Md Abdul Momen, Md Ataur Rahman, Hosne Ara Begum, Md Mufazzal Hossain
Pages: 64 - 69
Abstract: In the present investigation, Cu(II) doped TiO2 was prepared by a precipitation method. The precipitate was calcined at 300 ºC for
2 hours. The prepared doped catalyst was characterized by scanning electron microscope (SEM), energy dispersive X-ray (EDX)
spectroscopy and X-ray diffractometry (XRD). SEM images revealed that the morphology of the doped catalyst was different from
that of TiO2. Elemental analysis was accomplished by EDX that indicated the presence of Cu, Ti and O atoms in the prepared sample.
XRD analysis confirmed that TiO2 was present as anatase with almost no distortion in peak position due to the presence of Cu(II)
in some interstitial sites. Photodegradation of remazol black B (RBB) was carried out at different experimental conditions under
different light sources. The catalytic efficiency of Cu(II) doped TiO2 increased up to a certain dosage then reduced with a further
increase in the amount of photocatalyst. The optimum conditions for degradation was found at pH 3.0 under UV light. Under these
experimental conditions, Cu(II) doped TiO2 degraded 98.8% of RBB, on the other hand, undoped TiO2 degraded only 80.0% of RBB. Dhaka Univ. J. Sci. 70(1): 64-69, 2022 (January)
PubDate: 2022-07-24
DOI: 10.3329/dujs.v70i1.60383
Issue No: Vol. 70, No. 1 (2022)
- Sensitivity of Different Physics Schemes in the Simulation of Heat Wave
Events over Bangladesh Using WRF-ARW Model
Authors: Sahadat Jaman, Md Jafrul Islam, Ashik Imran, Md Kamruzzaman, MAK Mallik, Pappu Paul, IM Syed
Pages: 70 - 78
Abstract: Heat waves (HWs) are an extreme temperature condition that has a direct impact on human lives. In recent years, a large number of
people have died all over the world due to hot weather. The purpose of this study is to predict HWs accurately to mitigate the casualties
caused by them. Two HW events are selected for this study (Event-1: 0000 UTC of 18 May to 0000 UTC of 25 May 2015, Event-2:
0000 UTC of 05 April to 2100 UTC of 08 April 2015). At first, sensitivity tests have been done using different combinations of
physics schemes. Sensitivity of Planetary boundary layer (PBL) and surface layer (SL) schemes combinations (YSU-Revised MM5,
YSU-MM5, MYJ-Eta, and ACM2-Revised MM5) and land surface models (RUC, Noah, Noah-MP, and CLM4) are investigated to
predict Comfort Index (CI), which is identified by using Physiological Equivalent Temperature (PET). To simulate PET, the primary
meteorological variables 2-m air temperature (T2), 2-m relative humidity (rh2), mean radiant temperature (TMRT), wind speed at 10
m (ws10), and cloud cover data have been used. These parameters were simulated by the WRF model using both single and nested
domains. The experiments found that the combination of the YSU-MM5 scheme and the Noah land surface model predicted the
WRF simulated variables very well. The study also found that the CI exists between the slight heat stress to extreme heat stress and
the maximum PET values were found to be 47.6 ºC and 48.5 ºC for Rajshahi and Khulna event respectively. Dhaka Univ. J. Sci. 70(1): 70-78, 2022 (January)
PubDate: 2022-07-24
DOI: 10.3329/dujs.v70i1.60384
Issue No: Vol. 70, No. 1 (2022)
|
Open Access journal
