Endohedral and Exohedral Complexes of Polyhedral Oligomeric Silsesquioxanes (POSS): Endohedral Clusters of Si12 : a Theoretical Study

Two distinct research projects were carried out in this dissertation. In the first project the results of first principle calculations on endo- and exohedral complexes of polyhedral oligomeric silsesqiuoxanes (POSS) with atomic and ionic species were carried out. Detailed studies were performed on structures, stabilities and electronic properties of these complexes. The stabilities of the endohedral Tn-POSS ( n = 8, 10 and 12) complexes depends on both the cage size and the nature of the endohedral species. Alkali metal ion encapsulation leads to cage contraction. Electron density was transferred from the cage to the alkali metal cations. Halide encapsulation caused the cages to expand. Electron density was transferred from the halides to the cage. Noble gas encapsulation has minimum effect on the cage structure. Electron transfer between cage framework atoms and He and Ne were negligible. However, a small amount of electron transfer between Ar and POSS cages occurred. Ionization potentials calculated for T10-POSS and T12-POSS endohedral complexes with alkali metals indicate that these complexes have superalkali behavior. Several transition metal encapsulations into the T8-POSS cage gave thermodynamically stable endohedral complexes. The HOMO-LUMO gaps for the transition metal endohedral complexes were reduced versus that of pure cage. In almost all cases, the exohedral Tn (n = 8, 10, 12) complexes were energetically more stable than their corresponding endohedral counterparts except for the complex with F-. The exohedral Fpenetrates directly into the Tn-POSS cage forming an endohedral complex. In the second project ab initio electronic structure calculations based on density functional theory were performed to study small silicon clusters containing an endohedral atoms or ions. The formation of endohedral clusters M@Si12 (Li0,1,-1, Na0,1,-1, K+, He, F- and Cl-) depended on the Si12 cage structure and the nature of the embedding species. Only Li0,1,-1, Na0,1,-1 and He form endohedral clusters with different Si12 cage isomers. All observed endohedral clusters are stable and have large HUMO-LUMO gaps (\u3e1eV). The endohedral clusters Li-@Si12 and Na-@Si12 are thermodynamically more stable than their neutral and cationic counterparts. The stability order predicted for the alkali metal series was anionic clusters \u3e neutral clusters\u3e cationic clusters. Encapsulations of halides are completely unfavorable and halide insertions cause the Si12 cage rupture. Encapsulation of two Li atoms into the Si18 cage generates the endohedral Li2@Si18 complex. Encapsulating Na atoms into Si18 cage leads to an exohedral Na2Si18 cluster. Endohedral Si20@Li20 was also investigated and characterized

Socioeconomic Status and Maternal Health-seeking Behavior: A Comparative Study between a Rural Site and an Urban Community in Bangladesh

Maternal health-seeking behavior is not only a crucial public health issue but also a serious women’s health concern in Bangladesh. The present study examines the relationship between couples’ socioeconomic status and maternal health-seeking behavior in comparison of rural areas and urban communities in Bangladesh. Based on the research objectives, it included 95 rural and 95 urban couples (total 190 couples) randomly selected from purposively selected rural areas and urban communities in Thakurgaon District (north western area of Bangladesh). Results of the present study indicate that the rate of illiteracy was higher in rural sites than in the urban communities (rural: husbands - 25.26% and wives - 13.69%; urban: husbands - 5.26% and wives - 10.52%). The main occupation in rural areas is agriculture for husbands (48.42%) and home making for wives (84.21%) compared to 36.84% urban husbands in services and 75.79% wives in home making. By income, most of the rural couples (47.37%) earn less than Tk. 2000 per month compared to 1.05% in urban area. Data also indicates that 47.37% of rural women did not have medical check-ups during the pregnancy period, 73.69% gave birth at home and 68.42% used a traditional birth attendant (TBA) compared to 20.0%, 38.94% and 33.69% in the urban communities, respectively. The data analysis explores that, both in rural and urban communities, the low rate of maternal health-seeking behavior (e.g., no check-up, child birth at home, and traditional birth attendant) was higher among the husbands with illiteracy, wives only engaged in home-making jobs, and the couples earning less than Bangladesh taka 2000 (1 USD = 83 BDT in currency exchange) in a month. The findings suggest that education, income and particularly women’s employment or women’s engagement in income generating activities should be taken into account in addressing maternal health issues in Bangladesh

Analysis of consumer loan in BRAC Bank Limited

This internship report is submitted in a partial fulfillment of the requirements for the degree of Bachelor of Business Administration,2007.Cataloged from PDF version of Internship report.Includes bibliographical references (page 112).Delwar HossainB. Business Administratio

Nursing students' information literacy skills prior to and after information literacy instruction

Information literacy has been identified by the University of Southern Queensland as an essential graduate quality. It has also been identified in the nursing literature as a requirement for nursing profession. Data were collected from Toowoomba and Fraser Coast campuses using a questionnaire to assess first-year nursing students' information literacy skills prior to and after information literacy instruction. The findings indicate that embedding such instruction into nursing courses is beneficial

Dual Orthogonal Feed Circular Polarization Array Antenna Using Microstrip Slot Feed Network

This paper presents a new circularly polarized microstrip array antenna using dual-orthogonal feed technique. The feed network for 1x2 array is designed using microstrip lines and slot lines by applying double-sided MIC concept effectively. 90 degree phase difference between two orthogonally feed signals os created by choosing appropriate feed point in the feed network to advance one of the feed signals by quarter wavelength (lemda/4) from other. Excellent radiation performance is obtained from this proposed antenna with low cross polar component. The impedence (<-10dB) bandwidth of the array is 9.1% and the 3-dB axial ration bandwidth is 1.85% (9.905GHz to 10.09 GHz). The average  gain is higher than 9dBiC over the 3-dB AR bandwidth. The relation between antenna dimensions and characteristics ia also investigated with a parametric analysis of the antenna

Effects of integrated weed management practices on the performance of boro rice cultivars

An experiment was conducted during the period from November 2016 through May 2017 to evaluate the effect of integrated weed management practices on weed suppression and on the performance of boro rice cultivars. The experiment consisted of two cultivars viz., BRRI dhan28 and BRRI dhan29 along with eight different weed management practices. Cultivar did not exert any significant effect on weed density and dry weight. Integrated weed management practices exerted significant effect on weed density and dry weight. The highest weed dry weight was observed in no weeding treatment and lowest one was recorded in application of pre-emergence herbicide followed by one hand weeding at 35 DAT. BRRI dhan28 × no weeding treatment produced the highest weed dry weight and BRRI dhan28 × application of pre-emergence herbicide followed by one HW produced the lowest weed dry weight at different DATs. BRRI dhan28 produced higher grain and straw yields than BRRI dhan29. The highest grain yield was obtained from application of pre-emergence herbicide followed by one hand weeding at 35 DAT. BRRI dhan28 × application of pre-emergence herbicide followed by one HW at 35 DAT produced the highest grain yield and the lowest grain yield was resulted from BRRI dhan28 × no weeding treatment. From the study it may be concluded that BRRI dhan28 × application of pre-emergence herbicide followed by one HW at 35 DAT may be recommended for controlling weeds effectively and for getting the highest grain yield in boro rice

Financial Reforms in the Banking Sector of Bangladesh- An Evaluative Study

The aim of this study is to summarize the major reforms undertaken in the banking industry of Bangladesh from 1971 to 2015. The Financial Sector Reform is a continuous process. It comprises policy reforms and basic institutional changes in the status and their respective goals. Although Bangladesh became independent in 1971, the financial reform process in our economy started since early 80s with privatization of NCBs and allowing private sector banks and major changes have been brought about in policy areas with our own initiative and also under the surveillance and supervisory guidance of IMF and World Bank. The study suggests some policy implication like Implementing Basel III, Ensuring the optimum utilization of fund, Keeping additional capital and the like

Single feed circularly polarized crescent-cut and extended corner square microstrip antennas for wireless biotelemetry

In this paper, the development of two novel circularly polarized microstrip antennas is thoroughly explained. These antennas are fed by coaxial feeding technique. One of the primary objectives of the proposed work is to tune the antennas to work in ISM band. This frequency band refers to the internationally recognized radio frequency bandwidth which is to be used explicitly for Industrial, Scientific, and Medical applications. Therefore, these antennas would be suitable to use in the field of wireless biotelemetry. Two new antenna design techniques have been introduced to produce circular polarization, and details of these schemes are described. The proposed microstrip antennas are designed and simulated on Advanced Design System (ADS) software. The return loss of the proposed crescent-cut antenna is -19.3 dB at the operating frequency. The extended corner antenna has the return loss of -29.3 dB at the tuned frequency. The simulation results are also presented and discussed

Quality Assessment of Shoe Leather Based on the Properties of Strength and Comfort, Collected from Different Footwear and Leather Industries in Bangladesh

Based on the environmental condition, a shoe manufactured with different suitable materials has to provide optimum comfort and strength features by using high-quality leather parts. The aim of the study is to evaluate the quality of the shoe upper leather in Bangladesh. Ten different types of shoe leather, made from cow hides and goat skins, were collected from different footwear and leather industries in Bangladesh. The research was carried out by using approved methods of analysis as per the International Union of the Society of Leather Technologists and Chemists’ official methods for physical and chemical analysis. Physical and chemical properties, which were studied three times for each of the samples, were tensile strength, percentage of elongation, tearing strength, grain crack resistance, water vapor permeability, flexing endurance, scuff resistance, perspiration fastness, color rub fastness, bond strength of the finish film, the pH, moisture content, chromic oxide content and fat content, respectively. From the study, it has been revealed that samples 02 and 08 were completely unacceptable, samples 04, 05 and 07 were moderately acceptable, and the remaining samples, 01, 03, 06, 09 and 10, were strongly acceptable on the basis of the ISO standard for shoe leather. To get the better quality, the above mentioned tests should be improved, thus the demand and the value of shoe leather, as well as footwear, will be increased and the rejection rate will be decreased gradually