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Study of the Physical and Mechanical Properties of Coconut Spathe Fiber Reinforced Obsolete Polymer Composites

Materials Sciences and Applications 2021年第5期12卷 223-238页

作者： rabeya akter Budrun Neher M. A. Gafur Rakib Hossain Farid Ahmed Department of Physics Jahangirnagar University Dhaka Bangladesh Pilot Plant and Process Development Centre Bangladesh Council of Scientific and Industrial Research Dhaka Bangladesh Department of Physics Bangabandhu Sheikh Mujibur Rahman Science & Technology University Gopalganj Bangladesh

Fiber-reinforced polymer (FRP) composites have gradually gained wide acceptance as engineering material applications due to their unique advantages including their high strength-to-weight ratio and excellent corrosion resistance. This study was carried out with composites prepared by hot press molding method using coconut spathe fiber as reinforcing material and HDPE (from HDPE can as obsolete polymer) as polymer matrix. Composites were made at 150°C under 60 kN load by taking diverse weight percentage (wt.%) of fiber from 0 to 20 of its total weight. In this research investigation, different properties of the composites such as bulk density, water absorption, tensile and flexural properties, impact strength and hardness test properties were carried out. The fiber content enhancement increases the bulk density in all composites. The rate of water absorption improves with the improvement of fiber addition with respect to HDPE in all composites. But the water absorption was not increased uniformly with the increase of fiber addition in composites. In all cases, composites absorbed water very rapidly up to 80 hrs and then water absorption is in saturated condition. The mechanical properties like tensile strength (TS), flexural strength (FS), impact strength (IS) and hardness were observed to be comparatively more enhanced for 5% composite, while further increasing of fiber addition, all mechanical properties changes irregularly. The irregular nature of change might be caused due to the over loading of fiber in polymer matrix.

关键词： Coconut Spathe Fiber Obsolete Polymer Matrix Tensile Strength Impact Strength

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Effect of Exchange-Correlation Functional on the Structural, Mechanical, and Optoelectronic Properties of Orthorhombic RbSrBr3 Perovskite

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Materials Sciences and Applications 2024年第6期15卷 137-154页

作者： Fatema Najrin rabeya Bakar Sarna Md. Alamin Sarker Budrun Neher Md. Mahbubur Rahman Bhuiyan Farid Ahmed Department of Physics Jahangirnagar University Dhaka Bangladesh Department of Electrical and Electronics Engineering Green University of Bangladesh Purbachal American City Kanchan Rupganj Narayanganj-1461 Dhaka Bangladesh

In the present study, the effect of the exchange-correlation functional on the structural, mechanical, and optoelectronic properties of orthorhombic RbSrBr3 perovskite has been investigated using various functionals in Density Functional Theory (DFT) with the CASTEP code. The optimized lattice parameters are quite similar for all the functionals. The electronic properties have shown that RbSrBr3 perovskite is a wide direct band gap compound with a band gap energy ranging from 4.296 eV to 4.494 eV for all the functionals. The mechanical parameters like elastic constants, Young’s modulus, Shear modulus, Poisson’s ratio, Pugh’s ratio, and an anisotropic factor reveal that the RbSrBr3 perovskite has ductile behavior and an anisotropic nature which signifies the mechanical stability of the compound. The Debye temperature might withstand lattice vibration heat. High absorption coefficient (>104 cm−1), high optical conductivity, and very low reflectivity have been found in the RbSrBr3 perovskite for all functions. The computed findings on the RbSrBr3 perovskite suggested that the presented studied material is potentially applicable for photodetector and optoelectronic devices.

关键词： Density Functional Theory Mechanical Properties Photodetector Ductility Anisotropic Factor

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Feto-Maternal Outcome and Complications of Emergency Caesarean Section among the Patients Admitted at a Tertiary Care Hospital in Dhaka City

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Open Journal of Obstetrics and Gynecology 2016年第13期6卷 874-878页

作者： Rifat Sultana Aftabun Nahar Fatema Mahbooba akter rabeya Sultana Afroza Ghani Md. Abdullah Yusuf Department of Gynaecology & Obstetrics Shaheed Taj Uddin Ahmad Medical College Gajipur Bangladesh Department of Gynaecology & Obstetrics Mugda Medical College Dhaka Bangladesh Department of Gynaecology & Obstetrics City Medical College Gazipur Bangladesh Department of Gynaecology & Obstetrics Shaheed Suhrawardy Medical College Dhaka Bangladesh Department of Microbiology National Institute of Neurosciences & Hospital Dhaka Bangladesh

Background: Caesarean Section done in emergency basis can result some adverse outcome to both the fetus & mother & complications may arise. Objective: The purpose of the present study was to see the fetal & maternal outcome or any complications among the pregnant woman who had undergone emergency caesarean section. Methodology: This descriptive type of cross sectional study was conducted in the Department of Gynaecology & Obstetrics at Dhaka Medical College Hospital during the period from July 2006 to December 2006. The patients underwent emergency caesarean section for any indication during the mentioned period of study was selected as study population. Among them, 100 cases were recruited in this study. Result: Among the cases, maternal morbidity was as high as 64% which were due to haemorrhage, post-operative infection, rise of blood pressure and other complications. Regarding fetal outcome, 92% babies were born with normal birth weight, 33% babies were developed complications which were mostly due to birth asphyxia and prematurity. Conclusion: In conclusion, emergency caesarean section has maternal morbidity as well as fetal and neonatal adverse outcome.

关键词： Foetal Outcome Neonatal Outcome Maternal Outcome Emergency Caesarean Section

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A Comparison of Change Detection Analyses Using Different Band Algebras for Baraila Wetland with Nasa’s Multi-Temporal Landsat Dataset

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Journal of Geographic Information System 2015年第1期7卷 1-19页

作者： Mohammad Ashraf rabeya Nawaz CSIR-NET (Earth Sciences) UGC-JRF (Geography) Department of Geography Patna University Patna India M. Tech 2nd Year Centre of Mining Environment Indian School of Mines Dhanbad India

Wetlands are those landscapes which are saturated with water or covered by water either perennially or for a major part of the year. Due to transforming nature of the wetlands from aquatic to terrestrial, the related physical features are not easy to be monitored. With the recent advancement in Remote sensing technique, the feature extraction of wetland with the help of different satellite derived band algebras including Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), Modified NDWI (MNDWI), Normalized Difference Moisture Index (NDMI) is being used by experts. The common diagnostic features of wetlands are surface water, swamps and aquatic vegetation. The present study is based on a comparison between these four indices. Baraila wetland of Vaishali district Bihar is selected as a site for the study because the surface water of this “BAT” shaped wetland has decreased rapidly in last half decade which is alarming for the related ecology and biodiversity.

关键词： Wetlands Remote Sensing NDVI NDWI MNDWI NDMI

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Single Image Dehazing: An Analysis on Generative Adversarial Network

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Journal of Computer and Communications 2020年第4期8卷 127-137页

作者： Amina Khatun Mohammad Reduanul Haque rabeya Basri Mohammad Shorif Uddin Department of Computer Science and Engineering Daffodil International University Dhaka Bangladesh.

Haze is a very common phenomenon that degrades or reduces visibility. It causes various problems where high-quality images are required such as traffic and security monitoring. So haze removal from scenes is an immediate demand for clear vision. Recently, in addition to the conventional dehazing mechanisms, different types of deep generative adversarial networks (GAN) are applied to suppress the noise and improve the dehazing performance. But it is unclear how these algorithms would perform on hazy images acquired “in the wild” and how we could gauge the progress in the field. To bridge this gap, this presents a comprehensive study on three single image dehazing state-of-the-art GAN models, such as AOD-Net, cGAN, and DHSGAN. We have experimented using benchmark dataset consisting of both synthetic and real-world hazy images. The obtained results are evaluated both quantitatively and qualitatively. Among these techniques, the DHSGAN gives the best performance.

关键词： Dehazing Deep Leaning Convulutional Neural Network (CNN) Generative Adversarial Networks (GAN)

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Environmental Study on a Coastal River of Bangladesh with Reference to Irrigation Water Quality Assessment: A Case Study on Shailmari River, Khulna

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Journal of Geoscience and Environment Protection 2016年第10期4卷 41-64页

作者： Md. Muhyminul Islam Abul Kalam Azad Mosummath Hosna Ara Masudur Rahman Nazia Hassan Sadhon Chandra Swarnokar Israth rabeya Tropical Hydrogeology and Environmental Engineering (TropHEE) Technische Universitaet Darmstadt Darmstadt Germany Environmental Science Discipline Khulna University Khulna Bangladesh Chemistry Discipline Khulna University Khulna Bangladesh

Water quality is the critical environmental determinant that influences the agricultural production and therefore, the economy that solely depends on its agricultural productions. Batiaghata Upazilla is one of the major crop productive areas of Khulna region and the agricultural production here largely depends on the natural water of the Shailmari River system around it. The present study was conducted to assess the suitability of this coastal river water for irrigational use. 66 water samples were collected during this study in three consecutive agricultural seasons, viz., pre-monsoon (22), monsoon (22) and post-monsoon (22) from 11 sampling stations within the river system considering the high (11) and ebb (11) tides for each station. Standard methods were followed throughout the study period for the collection of the samples and analysis of major physicochemical parameters (pH, EC, TDS, salinity, Na, K, Ca, Mg, Cl, HCO3, SO4, NO3 and PO4). Hydrocehmical characterization using Piper trilinear diagram shows that the water of the river system is Na-Cl dominated saline water type in pre-monsoon, whilst most of the samples of the river and the connected channel are characterized as fresh water of Ca-Mg-Na-HCO3 and Ca-Na-Mg-HCO3 types in monsoon and post-monsoon respectively. The calculated values of chemical indices like SAR, %Na, KI, PI and MH using the results of the analysed parameters indicate that the river water is chemically unsuitable for use in irrigation during pre-monsoon, while in the monsoon and post-monsoon the river water is within good to permissible limit for the use in the agricultural fields. However, high %Na, KI and MH values with high salinity of the channel water limit its use in agricultural applications in monsoon and post-monsoon. The USSL (United States Salinity Laboratory) diagram depicts that the river water is C4-S4 type with very high salinity and sodium content in pre-mon

关键词： Coastal River Irrigation Suitability Salinity SAR % Na FAO Piper USSL Shailmari Khulna

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Relationship of Circulating High-Density Lipoprotein Cholesterol and Anemia

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Journal of Life Sciences 2013年第5期7卷 459-463页

作者： Md. Aminul Haque Khan Rokshana rabeya Muhammad Saiedullah Rukhsana Parvin Sohel Ahmed Md. Rezwanur Rahman Department of Biochemistry Enam Medical College Dhaka 1340 Bangladesh Biochemistry Laboratory Enam Medical College Hospital Dhaka 1340 Bangladesh Department of Applied Laboratory Sciences Bangladesh University of Health Sciences Dhaka 1216 Bangladesh Department of Medicine Enam Medical College & Hospital Dhaka 1340 Bangladesh Department of Biochemistry & Molecular Biology Jahangirnagar University Dhaka 1342 Bangladesh Department of Biochemistry Delta Medical College Dhaka 1216 Bangladesh

Circulating level of low HDLC (high-density lipoprotein cholesterol) represents a common critical risk factor for IHD (ischemic heart disease) and may further aggravate the condition in anemic subjects, as the presence of anemia itself is a threat to cardiovascular consequences. To investigate the relationship of circulating HDLC with anemia, first we determined the levels of total hemoglobin (Hb) in a total of 301 subjects (male, n = 158; female, n = 143) randomly, and then examined the circulating levels of HDLC in fasting condition. Age of the study subjects was 47.9 ± 16.6 (mean ± SD) years. Both the male and female subjects were divided into three groups according to their levels of Hb. The relationship of circulating levels of HDLC with the levels of total Hb was statistically analyzed. In case of the male subjects, we found that the levels of HDLC differed significantly among the three groups with different levels of Hb (P = 0.0233) and decrease in the levels of HDLC correlated significantly with the gradual decrease of total Hb level (r = 0.2504; P = 0.0015). In female subjects, we observed a similar trend of difference among the three groups (P = 0.0685). However, decrease in the levels of HDLC correlated significantly with the gradual decrease of Hb level (r = 0.2199; P = 0.0083). Altogether, this study demonstrates that decrease in the circulating HDLC is related to the gradual decrease of Hb level. This study also indicates that circulating level of HDLC may be influenced by the level of total Hb and reveals the cardiovascular risks in anemia as well.

关键词： High density lipoprotein cholesterol hemoglobin anemia

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