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Search Results: 1 - 10 of 782493 matches for " A. B. M. Sadique Rayhan "
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Kinetics of Degradation of Eosin Y by One of the Advanced Oxidation Processes (AOPs)—Fenton’s Process  [PDF]
Ashraf Hossain, A. B. M. Sadique Rayhan, Md. Jahir Raihan, Aklima Nargis, Iqbal M. I. Ismail, Ahsan Habib, Abu Jafar Mahmood
American Journal of Analytical Chemistry (AJAC) , 2016, DOI: 10.4236/ajac.2016.712074
Abstract: Kinetics of homogeneous degradation of Eosin Y (EY), also known as Acid red 87 (CI 45380), are studied, mostly using Fenton’s process, at 30 by monitoring its absorbance at 517 nm (λmax of EY). This process is one of the advanced oxidation processes (AOPs). Mixture of H2O2 and Fe(II) ion in acetate buffer medium (pH 2.74 - 4.56) generates hydroxyl free radicals (?OH) which attack the dye molecules, resulting in degradation of the dye molecules. Results show that the initial rate of EY degradation decreases with the increasing of solution pH because of removal of kinetically important Fe (iron) species through formation of ferric hydroxide. On the other hand, the rate increases with increasing the?concentrations of H2O2, Fe(II) and EY at low solution pH. The initial rate increases with increasing of concentration of H2O2 and, subsequently remains unaffected with further increase of its concentration at a constant Fe(II) concentration because of the enhanced scavenging environment created by H2O2 at its higher concentration. The initial rate also increases with increasing of concentration of Fe(II) at a constant H2O2 concentration and remains unaffected with its further increase. EY concentration also enhances the initial rate at low pH. However, the initial rate is significantly enhanced by UV light. This is because of formation of additional hydroxyl radicals through excitation of the dye molecules by UV light. During the period of experiment, EY in aqueous solution alone hardly suffered any degradation. Degradation mechanism of EY by the Fenton and photo-Fenton’s processes is also discussed. Statistical analysis was used to validate the experimental results. Low values of the standard deviation for both the initial rate and % degradation indicated the consistency of the experimental data.
First-principles study of Vickers hardness and thermodynamic properties of Ti3SnC2 polymorphs
M. A. Rayhan,M. A. Ali,S. H. Naqib,A. K. M. A. Islam
Physics , 2015,
Abstract: We have investigated Vickers hardness and the thermodynamic properties of the recently discovered nanolaminate carbide Ti3SnC2 polymorphs using the first-principles calculations. The chemical bonding shows a combination of covalent, ionic and metallic types. The strong covalent bonding is mainly responsible for high Vickers hardness of Ti3SnC2 polymorphs. Thermodynamic properties are studied using the quasi-harmonic Debye model. The variation of bulk modulus, thermal expansion co-efficient, specific heats, and Debye temperature with applied pressure (P) and temperature (T) are investigated systematically within the ranges of 0 - 50 GPa and 0 - 1000 K. The calculated results have been compared with available experimental and theoretical data.
Is Drotrecogin alfa (activated) for adults with severe sepsis, cost-effective in routine clinical practice?
M Zia Sadique, Richard Grieve, David A Harrison, Brian H Cuthbertson, Kathryn M Rowan
Critical Care , 2011, DOI: 10.1186/cc10468
Abstract: This CEA used data from a prospective cohort study that compared DrotAA versus no DrotAA (control) for severe sepsis patients with multiple organ systems failing admitted to critical care units in England, Wales, and Northern Ireland. The cohort study used case-mix and mortality data from a national audit, linked with a separate audit of DrotAA infusions. Re-admissions to critical care and corresponding mortality were recorded for four years. Patients receiving DrotAA (n = 1,076) were matched to controls (n = 1,650) with a propensity score (Pscore), and Genetic Matching (GenMatch). The CEA projected long-term survival to report lifetime incremental costs per quality-adjusted life year (QALY) overall, and for subgroups with two or three to five organ systems failing at baseline.The incremental costs per QALY for DrotAA were £30,000 overall, and £16,000 for the subgroups with three to five organ systems failing. For patients with two organ systems failing, DrotAA resulted in an average loss of one QALY at an incremental cost of £15,000. When the subgroup with two organ systems was restricted to patients receiving DrotAA within 24 hours, DrotAA led to a gain of 1.2 QALYs at a cost per QALY of £11,000. The results were robust to other assumptions including the approach taken to projecting long-term outcomes.DrotAA is cost-effective in routine practice for severe sepsis patients with three to five organ systems failing. For patients with two organ systems failing, this study could not provide unequivocal evidence on the cost-effectiveness of DrotAA.Severe sepsis is the most common cause of death for patients admitted to critical care [1-3]. Recent international studies suggest that the annual incidence of severe sepsis is 50 to 100 cases per population of 100,000 [4]. Approximately 80% of critical care admissions with severe sepsis have multiple organ systems failing, and the associated hospital mortality is around 50%. Severe sepsis is associated with substantial health
Individual freedom versus collective responsibility: an economic epidemiology perspective
M Zia Sadique
Emerging Themes in Epidemiology , 2006, DOI: 10.1186/1742-7622-3-12
Abstract: Immunisation represents a classic case of social dilemma: a conflict of interest between the private gains of individuals and the collective gains of a society. An individual's self-interest and choice often leads to a vaccination uptake rate less than the social optimum as individuals do not take into account the benefit to others [1]. Conventional wisdom generally favours public intervention in order to produce a socially warranted level of vaccination. This line of argument is primarily based on the externality associated with individual decisions, since individuals are presumed to make choices on the basis of their own welfare gains, without considering the full social impact of their decisions. As the benefits to society are larger than the sum of those to individuals, public policy measures aim to increase demand closer to the social optimum by subsidising the vaccine (many countries provide vaccines free of charge) or through compulsory vaccination, although such a policy is almost always partial. Individuals with religious, medical or social reasons are often exempted. There is, however, controversy over the effectiveness of public intervention compared to the free choice outcome [1-3], and it is the intention of this article to address this issue.Vaccination decisions are made under imperfect information, which means an individual's assessment of the risks and benefits of vaccination is often inaccurate. But even if individuals had perfect information regarding the cost and benefits of vaccination, the free choice outcome would still be different from the social outcome due to the 'free rider' problem associated with vaccination. The changes in risk of infection tend to induce changes in activities that put the individual at risk, which in turn alter the dynamics of disease transmission. There is a feedback mechanism between infection rate and rational response, but the classic models of infectious disease have not incorporated such endogenous behavioural r
Pakistan Veterinary Journal , 2006,
Abstract: The present study was undertaken to compare five laboratory diagnostic tests for sub-clinical mastitis in cattle and buffaloes and to compute cost, time taken by each test and its ranking for availability, adoptability, interpretability and sensitivity. There were 352 cases with each test type viz. California Mastitis Test (CMT), White Side Test (WST), White Side + Dye (WSTD), Surf Test and Surf + Dye, and 880 cases with each species type (cattle and buffaloes). Result scores (1760 ) for sub-clinical mastitis in each category of negative, trace, single positive, double positive and triple positive by species, and laboratory tests, were analyzed using nonparametric tests. Chi-square statistics showed that CMT was equally effective at both locations (farm vs. laboratory). Correlation further suggested that the association was highly significant. Moreover, cases in category of negative, trace and single positive strongly differed (P<0.05) amongst the laboratory tests. But differences were found vague in double and triple positive categories. However, Chi-square statistics of overall sub-clinical mastitis cases showed that the laboratory tests were significantly different for detecting various categories of sub-clinical mastitis of a cross-tabulation. The present findings uncovered stronger (P<0.05) positive correlation of both the WST and WSTD with CMT, while of Surf Test and Surf + Dye with CMT. Results also suggested that WSTD and Surf + Dye were equally associated with CMT in strength and direction as their counterpart tests WST and Surf Test with CMT and thus its response in efficacy to added dye was not distinct. Species effect on result scores was found negligible (P>0.05). The study further suggested that CMT was the most sensitive test, followed by WST/WSTD and Surf/Surf + Dye. Although, the five tests showed slight discrepancy in the trace category reaction, a strong relationship of Surf Test to CMT, its low cost, easy availability and readily adoptable qualities should spur the relevant authorities to recommend the use of Surf test as a routine practice in dairy farming and add this test in the curriculum of diploma and degree programmes.
New Superconductor (Na0.25K0.45) Ba3Bi4O12: A First-principles Study
Ali M. S.,Aftabuzzaman M.,Roknuzzaman M.,Rayhan M. A.,Parvin F.,Ali M. M.,Rubel M. H. K.,Islam A. K. M. A
Physics , 2014,
Abstract: A new superconductor (Na0.25K0.45)Ba3Bi4O12, having an A-site-ordered double perovskite structure, with a maximum Tc ~ 27 K has very recently been discovered through hydrothermal synthesis at 593 K. The structural, elastic, electronic, and thermal properties of the new synthesized compound have been investigated theoretically. Here we have employed the pseudo-potential plane-wave (PP-PW) approach based on the density functional (DFT) theory, within the generalized gradient approximation (GGA). The elastic constants (Cij), Pugh`s ratio, Cauchy`s pressure and other elastic parameters are derived and analyzed using energy strain method for the first time. We have discussed the bonding nature in the light of the electronic valence charge density. Both electron and hole-like Fermi surfaces are present in the compound under study which indicate the multiple-band nature of (Na0.25K0.45)Ba3Bi4O12. The compound is indicated to be a strongly coupled superconductor which is based on the estimated e-ph coupling constant. The thermodynamic properties such as bulk modulus, Debye temperature, heat capacities and volume thermal expansion coefficient at elevated temperature and pressure are calculated and analyzed for the first time by using quasi-harmonic model. Key words: double perovskite, superconductor, elastic properties, electronic properties, thermal properties
Factors Causing Malnutrition among under Five Children in Bangladesh
Md. Israt Rayhan,M. Sekander Hayat Khan
Pakistan Journal of Nutrition , 2006,
Abstract: The nutritional status of under five children is a sensitive indicator of a country`s health status as well as economic condition. This study investigated differential impact of some demographic, socio-economic, environmental and health related factors on nutritional status among under five children in Bangladesh. The study used Bangladesh Demographic and Health Survey 1999-2000 (BDHS 1999-2000) data. Bivariate analysis and multivariate analysis (Cox`s linear logistic regression model) were used to identify the determinants of under-five malnutrition. The analyses revealed that 45 percent of the children under age five were suffering from chronic malnutrition, 10.5 percent were acutely malnourished and 48 percent had under-weight problem. The main contributing factors for under five malnutrition were found to be previous birth interval, size at birth, mother`s body mass index at birth and parent`s education.
Complex Question Answering: Unsupervised Learning Approaches and Experiments
Yllias Chali,Shafiq Rayhan Joty,Sadid A. Hasan
Computer Science , 2014, DOI: 10.1613/jair.2784
Abstract: Complex questions that require inferencing and synthesizing information from multiple documents can be seen as a kind of topic-oriented, informative multi-document summarization where the goal is to produce a single text as a compressed version of a set of documents with a minimum loss of relevant information. In this paper, we experiment with one empirical method and two unsupervised statistical machine learning techniques: K-means and Expectation Maximization (EM), for computing relative importance of the sentences. We compare the results of these approaches. Our experiments show that the empirical approach outperforms the other two techniques and EM performs better than K-means. However, the performance of these approaches depends entirely on the feature set used and the weighting of these features. In order to measure the importance and relevance to the user query we extract different kinds of features (i.e. lexical, lexical semantic, cosine similarity, basic element, tree kernel based syntactic and shallow-semantic) for each of the document sentences. We use a local search technique to learn the weights of the features. To the best of our knowledge, no study has used tree kernel functions to encode syntactic/semantic information for more complex tasks such as computing the relatedness between the query sentences and the document sentences in order to generate query-focused summaries (or answers to complex questions). For each of our methods of generating summaries (i.e. empirical, K-means and EM) we show the effects of syntactic and shallow-semantic features over the bag-of-words (BOW) features.
Do Stock Prices in Turkey Reflect Fundamental Information? A Firm-level Analysis
M. Arifur Rahman,M. Shibley Sadique,Shah Saeed Hassan Chowdhury
International Journal of Economics and Finance , 2012, DOI: 10.5539/ijef.v4n12p137
Abstract: This paper investigates the correspondence between stock prices and firm fundamentals in Turkey. In pursuing our objective, we explore the relationship between firm-specific variation in stock returns and fundamentals in the context of a simple present value framework. We overcome the typical insufficiency of the spans of time-series accounting data in emerging market research, and the consequent loss of statistical testing power, by adopting a firm-level micro panel data approach. After properly accounting for unobserved heterogeneity, potential endogeneity bias and volatility persistence, we find that firm-specific variation of stock returns in Turkey is only weakly correlated with alternative proxies of firm-specific variation in firm fundamentals and that the relationship is not robust to the influence of control variables such as the firm size. Our findings are, therefore, consistent with the usual perception that stock prices in emerging markets contain little firm-specific information.
Review on fifteen Statistical Tests proposed by NIST
Journal of Theoretical Physics and Cryptography , 2012,
Abstract: With a motivation to understand all the fifteen test algorithms and to write their codes independently without looking at various sites mentioned in the NIST document a review study of the NIST Statistical Test Suite is undertaken. All the codes are executed with the test data given in the NIST document and excellent agreements have been found. The codes have been put together in a software, called as CU software, executable in Linux platform. Based on the CU software, exhaustive tests are executed on a long bit sequence generated by the Blum‐Blum‐Shub generator (BBSG). The CU software executes properly giving the results almost matched with those of the NIST results.
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