Kinetic Model of CCA Fixation on Wood. Part I. The Initial Reaction Zone

The fixation process for chromated copper arsenate (CCA-C) preservative treated wood has at least two distinctly different zones. One of these is a fast "Initial Reaction," characterized by a rapid increase in pH and a decrease in available hexavalent chromium (Crvi). In the present study we develop a mathematical model that describes the initial reaction kinetics for red pine (Pinus resinosa Ait.) treated with 1% CCA-C. The results show that the initial fixation reactions follow pseudo 10th order kinetics. The activation energy and pre-exponential factors were found to be 37.8 kj.mol-1 and 8.7 X 10-19 h-1 mol-9 I9, respectively. At all treatment temperatures tested, the initial reaction resulted in approximately 47% chromium reduction. At 4° the time required to complete the initial reaction is approximately 4.5 h; at room temperature the initial reaction is complete in about 1.7 h. At 50° the initial reaction is complete in about 25 min. The complete model incorporates the rate equation, Arrhenius temperature dependence, and the fixation definition into a single equation that expresses % chromium fixation as a function of initial chromium concentration in the treating solution and time and temperature history of the wood following treatment.This model can also be used as an integral part of an overall fixation model that can be used to predict the percent fixation at a given treatment condition based on knowledge of the temperature history of the wood during fixation

Kinetic Model of CCA Fixation in Wood. Part II. The Main Reaction Zone

Fixation of chromated copper arsenate type C (CCA-C) solution on wood, measured by hexavalent chromium reduction, follows different rates in different reaction zones. We identify two main zones: an initial reaction and a second main reaction. The main reaction zone in red pine (Pinus resinosa Ait.) starts once approximately 47% of the total CrvI in the impregnated CCA-C solution is fixed on wood matrix. The second main fixation reaction follows first-order reaction kinetics, and an Arrhenius type of correlation can be used in modeling the fixation kinetics. We obtained similar values of Arrhenius parameters for CCA-C concentrations of 1% and 3%. The activation energies for fixation reactions in the second zone were 87.6 and 88.1 kJ/mol for 1% and 3% CCA-C concentrations, respectively. The pre-exponential factors of the reaction rate constant were 2.7 X 1013 and 2.2 X 1013 h-1 for 1 and 3% solutions, respectively. By combining the reaction rate equations and the temperature-dependence (Arrhenius) relationship, a mathematical model for the main reaction of 1% CCA-C fixation in red pine was produced.This model estimates the percentage of CCA-C solution fixation on red pine for a given time (in hours)/temperature (K) history of the wood following treatment

Development and validation of a UPLC method for quantification of antiviral agent, Acyclovir in lipid-based formulations

AbstractPurposeThe objective of the current study is to evaluate the Ultra Performance Liquid Chromatography (UPLC) method for quantification of Acyclovir in lipid-based formulations.MethodA simple, rapid, reliable and precise reversed phase UPLC method has been developed and validated according to the regulatory guidelines, which composed of isocratic mobile phase; 0.25% formic acid (FA) in Milli-Q water with a flow rate of 0.5ml/min, and column BEH C18 (2.1×50mm, 1.7μm). The detection was carried out at 254nm.ResultsThe developed UPLC method was found to be rapid (1.2min run time), selective with well resoluted Acyclovir peak (0.89min) from different lipid matrices and sensitive (Limit of Detection (LOD) was 0.3ppm and Lower Limit of Quantification (LLOQ) was 1ppm). The accuracy and precision were determined and were perfectly matching with the standard FDA limits.ConclusionThe study showed that the proposed UPLC method can be used for the assessment of drug purity, stability, solubility and lipid-formulation release profile with no interference of excipients or related substances of active pharmaceutical ingredient

Impact of Principals' Managerial Roles Under School-based Management on School Improvement at Urban Secondary Schools of Bangladesh

This article aims al observing the relationship between principals' managerial roles and the improvement of schools and the impacts of principals' managerial roles toward school improvement based on the school-based management. This research uses 127 principals and 694 teachers of urban secondary schools of Bangladesh as the sample. Schools are becoming better when the principals give more emphasizing on strategic plan, supportive and comprehensive roles but less emphasizing on shared decision making. The findings of this study offer valuable information for policy makers and educational managers, especially the principals and teachers. Key words: Principals managerial roles, school-based management, teachers' Professional development activities, school improvement &nbsp

Effect of Tree Litter Application on Lowland Rice Yield in Bangladesh

The effect of tree litters on rice yield (cv. BR11) was evaluated in the study. Four kinds of tree litter, i.e., ipil-ipil or lamtoro (Leucaena leucocephala (Lamk) De Witt), sissoo (Dalbergia sissoo), akashmoni (Acacia auriculiformis) and mander (Erythrina orientalis) were incorporated into the soil 15 days before transplanting at rate of 5 ton/ha supplemented with inorganic fertilizers (83 kg N, 48 kg P205­, 42 kg K20, 10 kg S and 3.6 kg Zn/ha). In the control plots only recommended inorganic fertilizer were applied. Results showed that tree litter application had a significantly positive effect on the yield parameters such as plant height, panicle length, tillers per hill, filled grain and index of 1000-grain weight. Grain yield of plots treated with ipil-ipil, sissoo, akashmoni and mander was 5.61, 4.49, 4.95 and 5.36 ton/ha, and the yield increased over control plots 39.6, 11.7, 23.1 and 33.3%, respectively. It is worthy to note that addition of tree litter to inorganic fertilizer produced significantly higher yield than inorganic fertilizers solely. Among the tree litter, ipil-ipil and mander had the greatest increase in rice yield, while akashmoni was intermediate and sissoo was the least

A review on the mobile applications developed for COVID-19: An exploratory analysis

The objective of this research is to explore the existing mobile applications developed for the COVID-19 pandemic. To obtain this research objective, firstly the related applications were selected through the systematic search technique in the popular application stores. Secondly, data related to the app objectives, functionalities provided by the app, user ratings, and user reviews were extracted. Thirdly, the extracted data were analyzed through the affinity diagram, noticing-collecting-thinking, and descriptive analysis. As outcomes, the review provides a state-of-the-art view of mobile apps developed for COVID-19 by revealing nine functionalities or features. It revealed ten factors related to information systems design characteristics that can guide future app design. The review outcome highlights the need for new development and further refinement of the existing applications considering not only the revealed objectives and their associated functionalities, but also revealed design characteristics such as reliability, performance, usefulness, supportive, security, privacy, flexibility, responsiveness, ease of use, and cultural sensitivity.Comment: 11 pages, 3 figures, 4 table

Optical Quadruple Feynman Gate using SLM and Savart Plate

In recent years, Reversible logic is emerged as a promising computing paradigm with applications in low-power CMOS, quantum computing, optical computing and nanotechnology. The classical set of gates such as AND, OR, andEXOR are not reversible. However, optical computing technology the trinary and quadruple valued logic systems are the most important ones in the many valued logic system.In this paper, spatial light modulator (SLM) and Savart Plate based circuit has been proposed and described for realization of quadruple Fenyman Gate. It is optical in nature. SLM and Savart Plate can play a significant role in this field of ultra-fast all optical signalprocessing

Latent Patient Network Learning for Automatic Diagnosis

Recently, Graph Convolutional Networks (GCNs) has proven to be a powerful machine learning tool for Computer Aided Diagnosis (CADx) and disease prediction. A key component in these models is to build a population graph, where the graph adjacency matrix represents pair-wise patient similarities. Until now, the similarity metrics have been defined manually, usually based on meta-features like demographics or clinical scores. The definition of the metric, however, needs careful tuning, as GCNs are very sensitive to the graph structure. In this paper, we demonstrate for the first time in the CADx domain that it is possible to learn a single, optimal graph towards the GCN's downstream task of disease classification. To this end, we propose a novel, end-to-end trainable graph learning architecture for dynamic and localized graph pruning. Unlike commonly employed spectral GCN approaches, our GCN is spatial and inductive, and can thus infer previously unseen patients as well. We demonstrate significant classification improvements with our learned graph on two CADx problems in medicine. We further explain and visualize this result using an artificial dataset, underlining the importance of graph learning for more accurate and robust inference with GCNs in medical applications