132 research outputs found
Synthesis and Characterization of Poly(Hydroxamic Acid) and Poly(Amidoxime) Chelating Resins from Polymer Grafted Sago Starch
The graft copolymerization of methyl acrylate (MA) onto sago starch was
performed by free radical initiating process in which ceric ammonium nitrate (CAN)
was used as an initiator. It was found that the optimum yield of grafting, grafting
efficiency and rate of graft polymerization were all dependent upon the
concentration of CAN, MA, sago starch (AGU) and mineral acid (H2S04) as well as
reaction temperature and period. A new equation rate of polymerization was derived
from the proposed reaction mechanism. A new kinetic model for graft fraction was
proposed and the validity of the model was tested by the plot of l/(l-GF)ll2 as a
function of sago starch concentration and reciprocal monomer (MA) concentration.
The required straight line and ordinate intercept unity was obtained and the predicted
kinetic model was satisfactory supported by the experimental results until a certain
limit of monomer (MA) concentration.
A chelating polymeric resin containing hydroxamic acid was synthesized
from poly(methyl acrylate) (PMA) grafted sago starch. The binding capacity of the poly(hydroxamic acid) resin with copper is high and other metal ions also show
significant binding capacity. This chelating resin has the advantage of faster rate of
equilibrium and negligible affinity for alkali metal ions. The sorption capacities of
metal ions were pH dependent and its selectivity towards these metal ions is in the
following order: Cu2+ > Fe3+ > Cr3+ > Ni2+ > Co2+ > Zn2+ > Cd2+ > As3+> Pb2+. These paration of Cu2+ from Co2+ and Cd2+, and Fe3+ from Co2+ and Cd2+ were carried
out by column technique
Quality of Health Care in Bangladesh: A Study on Selected Upazila Health Complexes
Quality of care is an overwhelming issue in the context of health services of developing countries including Bangladesh. Performance of health care professionals and institutions determines the quality of care provided by the health facilities which in turn depends on governance as well as factors like access, safety, equity, appropriateness, timeliness, acceptability, reliability, assurance, responsiveness and empathy of care providers, health improvement and continuity of care etc. Though the governance issues affect massively the quality of care, in this article, an attempt has been taken to explore the factors which affect quality of care in health sector of Bangladesh. This paper also identifies the problems threat towards providing quality of health care in Bangladesh. Finally, this study recommends some policy options to ensure quality care in health sector and thus a healthy nation. To conduct this research and achieve the above mentioned objectives, upazila health complexes, the part and parcel of the public health sector in Bangladesh, has been selected as a case. Keywords: Quality Health Care, Public Health Sector , Upazila Health Comple
Governance and Good Governance: A Theoretical Framework
“Good governance” as an issue of development is being widely used for improvements in socio-economic outcomes and for aid effectiveness and considered as the effective tool for overcoming multidimensional challenges existed in both developed as well as developing countries of the world and it has generated increasing attention and debate both at the national and international level over the past two decades. The concept of ‘good governance’ conveys the qualitative dimension of governance that indicates effective, efficient, participative, or democratic form of government which is responsible for transparent and accountable management of human, natural, economic and financial resources for equitable and sustainable development. Addition of the adjective ‘good’ to governance has given a sense of enhancement and almost become an obsession in the recent debates on international development and public administration in developing countries. Other than the nations, international organizations such as the World Bank, the United Nations Development Programme (UNDP), Asian Development Bank (ADB), the Organization for Economic Co-operation and Development (OECD), the European Union (EU) and other donor agencies, have given rigorous importance to the issue of governance – particularly for aid receiving countries. The purpose of this article is to develop a conceptual framework on governance and good governance. This article highlights the emergence of governance as a shifting paradigm from government along with the differences between government and governance. It also focuses the meaning of governance and good governance in general and particularly the views from World Bank and UNDP as a problem solving mechanisms. For ensuring effective performance of the institutions, different international organizations like World Bank and UNDP addressed good governance indicators which are also explore in this article. Keywords: Governance, Good Governance, Theoretical Framewor
FINANCIAL CONTROL AND VARIABLE AMORTIZATION UNDER UNCERTAINTY: AN APPLICATION TO TEXAS RICE FARMS
Agricultural Finance,
Electrically conductive concrete heated pavement system: Challenges and solution
In regions characterized by harsh winter climates, transportation networks face substantial challenges due to ice and snow accumulation, disrupting air and ground travel. These disruptions can result in significant financial losses for the aviation industry and a worrying, problematic increase in weather-related road accidents. Traditional snow and ice removal methods involving mechanical equipment and chemical de-icers are costly and raise ecological concerns by threatening soil and water quality and global food supplies. Heated Pavement Systems (HPS), particularly Electrically Conductive Concrete (ECON) HPS, have emerged as a promising technology that, particularly Electrically Conductive Concrete (ECON) HPS, which shows potential in for effectively alleviating snow and ice accumulation in critical infrastructure areas such as airports and busy roadways. Despite its promise, the widespread implementation of ECON HPS technology remains limited, warranting a closer investigation into the barriers hindering its adoption. This research paper reviews the existing literature on ECON HPS technology to identify key aspects and challenges. Among the challenges highlighted is the elevated electrical resistivity of ECON during field implementation, increasing its operational costs. Subsequently, the study delves into efforts to produce low-resistivity ECON, presenting findings that provide valuable insights and directions for future research, with the ultimate goal of promoting the widespread adoption of ECON HPS technology and enhancing the resilience of transportation infrastructure in frigid climates
Vegetation cover and grasslands in the vicinity accelerate development of carabid beetle assemblages on restored landfill sites
There is increasing evidence that rare and scarce carabid species of conservation importance are frequent in brownfield sites such as restored landfill. However, this potential has largely been unexplored and was investigated here by examining carabid species composition, richness, and abundance in relation to habitat quality and landscape structure on landfill sites in comparison to paired reference sites of existing wildlife value. Sampling was conducted by collecting carabids in ten pitfall traps set along two 100 m transects on each of nine restored landfill and their paired reference sites in the East Midlands region of the UK. A total of 1014 individuals representing thirty seven carabid species were found during April to September in 2007 and 2008. On the landfill sites, generalist species were common, while no nationally rare or scarce species were found. Neither species richness nor diversity of carabid species was found to be different from that of the reference sites. Seeding during restoration was found to have a strong positive effect on richness and diversity, with seeded landfill sites tending to be similar to reference sites in terms of carabid species composition. Marked differences in diversity and richness were also attributed to variation in the amount of local vegetation cover, with presence of grassland in the surrounding landscape having a positive effect on carabid assemblages. We suggest that initial seeding may be an appropriate conservation strategy to improve beetle diversity and richness, coupled with management in terms of cutting to increase the potential of these sites for carabid conservation at the landscape scale
Silica gel-supported Pd nanocatalyst: Efficient Mizoroki-Heck reactions and sustainable Ozagrel synthesis
We developed a cost-effective silica gel-supported palladium nanocatalyst in a three-step reactions process. Initially, silica gel (60–120 mesh) underwent amino group functionalization using 3- aminopropyltriethoxysilane, leading to the formation of a Schiff base through a reaction with the 1,10- phenanthroline-2,9-dicarboxaldehyde ligand. Subsequently, palladium nanocatalyst was introduced to the silica matrix ligand in the presence of palladium salt and hydrazine hydrate, resulting in the formation of the silica gel-supported Schiff-base palladium nanocatalyst (Si@SBPdNPs 3). Successful functionalization of the silica matrix was confirmed using various spectroscopic techniques. FT-IR spectra demonstrated the incorporation of organic moieties onto the silica surface, while SEM images revealed the modified spherical shape of the silica gel. TEM and XRD analyses confirmed the presence of palladium on the silica matrix. ICP and EDX measurements validated the anchoring of 0.55 mmol/g of palladium to the catalyst. Additionally, XPS analysis showed the complexation of Pd(0) with the organic ligand on the silica matrix, confirming the successful integration of palladium into the system. This nanocatalyst demonstrated outstanding performance in Mizoroki-Heck reactions, yielding high product outputs in the cross-coupling of various aryl halides and olefins under mild conditions. Additionally, the nanocatalyst was effectively utilized in synthesizing Ozagrel, a thromboxane A2 synthesis inhibitor used for treating noncardioembolic stroke patients. Remarkably, the catalyst demonstrated excellent reusability, maintaining high productivity across five consecutive cycles, underscoring its economic and sustainable potential for industrial applications
Declaration Effect of Cash & Stock Dividends on Share Price: An Empirical Study on Dhaka Stock Exchange
This study analyzes the impact of different types of dividend declaration, namely stock and cash dividends. Using event study method, MAAR and CAAR, this study found no evidence of abnormal returns on the declaration day for either of the types of dividends. However, significant negative returns are reported on days prior to the declaration day for stock dividend, indicating speculative nature of the investors. Furthermore, it provides positive returns during the post-announcement period as the investors realize the chance of potential gains. However, as far as cash dividend is concerned companies listed under DSE do not provide any significant abnormal returns during the 60 days event window. For CAAR, no significant return is reported for cash dividend, while stock dividend provided a maximum 5.6% abnormal returns during the post announcement period
Influences of Central Units and Terminal Chains on the Banana-Shaped Liquid Crystals
Azo-functionalized materials are one of the appealing groups of the functionalized materials owing to their photoswitching behaviour and have been explored for various potential applications viz., optical data storage, sensor, display devices, nonlinear materials and molecular switches. Recently, azo-functionalized bent-core liquid crystals (BCLCs) have gained significant attention because they have dual properties of BCLCs and azobenzene, which enables to generate new multifaceted functional and smart materials. In this report, the recently synthesized azobenzene containing bent-core mesogens and its subclass, the so-called hockey stick and V-shaped molecules are summarized. The mesomorphic behaviour of reported BCLCs affected by the type of central core unit, the nature, number and position of the lateral substituents and the type and length of the terminal chain are discussed. The photoisomerization process of these photoresponsive BCLCs in solid, solution and mesophase, as well as the impact of light on the chemical and electrical properties of them, are discussed
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