A conceptualization of factors affecting collaborative knowledge building in online environments

PurposeThe purpose of this paper is to address the major findings of published research on the factors influencing students’ knowledge building in an online collaborative environment.Design/methodology/approachThe Preferred Reporting Items for Systematic Reviews and Meta-Analyses was used to review and synthesize existing empirical studies on knowledge building in a collaborative learning context. In total, 24 studies were identified from major electronic bibliographic databases. The research was conducted between 2017 and 2019. Results of these studies were analyzed to determine potential factors that may influence the knowledge-building process among students.FindingsFactors related to interaction and participation, task, student and support were found to be the major factors driving students’ knowledge building in the online collaborative learning environment. The association between these factors and certain collaborative tasks was mapped.Originality/valueFindings from this review can help decision makers of higher education in both developing and developed countries to take the necessary steps in order to promote effective knowledge-building practices in online collaborative learning. It may also help educational policy makers to understand the particulars of collaborative knowledge-building practices, so to increase organizational overall effectiveness and performance

Stability-indicating method for the determination of Rivaroxaban and its degradation products using LC-MS and TLC

A validated stability indicating thin layer chromatographic (TLC) and liquid chromatography coupled with mass spectrometry LC/MS methods were developed to analyse Rivaroxaban and its degradation products. Forced degradation studies under stress conditions were carried out in order to establish its stability profile. Stress conditions recommended by the International Conference on Harmonization (ICH) including oxidative, photolytic, thermal, acidic, and basic hydrolysis were applied. Rivaroxaban found susceptible to acid and base hydrolytic stress conditions. Degradation products were identified isolated and characterized using LC-MS and TLC. Three major degradation products were detected, separated and determined and two of them were further characterized by NMR spectroscopy and FT-IR

MODULAR COMPOSITE SANDWICH STRUCTURES FOR THERMAL AND STRUCTURAL RETROFITTING OF EXISTING BUILDINGS

Around 40% of global energy consumption and 30% of worldwide carbon dioxide (CO2) emissions are attributed to buildings. Most of this consumption is dedicated to ensuring thermal comfort. The goal of this research was to develop and field validate retrofit solutions to improve the energy efficiency of buildings. Exterior cladding panels were designed and tested to ensure adequate thermal and structural performance. Sandwich panels (glass fibers reinforced polymer (GFRP) skins and polymeric foam cores) were fabricated using the vacuum assisted resin transfer molding (VARTM) process. Extruded polystyrene (XPS) and polyurethane (PU) foams were compared as core materials through a series of thermal and mechanical tests. Thermal resistances of 3.62-4.66 h.ft2.°F/Btu (0.64-0.82 K.m2/W) per inch were obtained for sandwich structures. XPS samples were 26% lighter, 24%-40% stronger, and 16%-28% more brittle than PU in quasi-static loading configurations. PU absorbed 11% more energy than XPS in a low-velocity impact (LVI) test. Flatwise tensile test showed that the bonding strength between XPS and GFRP was 47% higher than PU foam. Consequently, XPS was chosen as core material and further tests were conducted accordingly. Tensile testing performed on the GFRP material resulted in a 3,191 ksi (22 GPa) elastic modulus, 42,786 psi (295 MPa) tensile strength, and 0.165 Poisson’s ration. To predict the wind loads according to the American Society of Civil Engineers (ASCE) building standard, flexural tests were conducted on a 4 x 8 ft2 (121.92 x 243.84 cm2) sandwich panel. FEA simulations were also developed to accurately predict the behavior of the retrofit panels based on actual dimensions and connections. Less than 4% variation was noted between experimental and numerical data. The deflections were within the allowable limits set by the International Building Code (IBC). The panels were supposed to be used as an exterior application; therefore, it was important to understand the environmental effects. Discoloration of the GFRP skin due to v ultraviolet (UV) and moisture exposure was observed. Ceramic coating was applied to eliminate the discoloration effect. A fire simulation (ASTM E84) was conducted on a 2 x 24 ft2 (60.96 x 731.52 cm2) panel to obtain surface burning characteristics

Series connected photovoltaic cells-modelling and analysis

As solar energy costs continue to drop, the number of large-scale deployment projects increases, and the need for different analysis models for photovoltaic (PV) modules in both academia and industry rises. This paper proposes a modified equivalent-circuit model for PV modules. A PV module comprises several series-connected PV cells, to generate more electrical power, where each PV cell has an internal shunt resistance. Our proposed model simplifies the standard one-diode equivalent-circuit (SEC) model by removing the shunt resistance and including its effect on the diode part of the circuit, while retaining the original model accuracy. Our proposed equivalent circuit, called here a modified SEC (MSEC), has less number of circuit elements. All of the PV cells are assumed operating under the same ambient conditions where they share the same electric voltage and current values. To ensure the simplification did not come at a reduction in the accuracy of the SEC model, we validate our MSEC model by simulating both under the same conditions, calculate, and compare their current/voltage (I/V) characteristics. Our results validate the accuracy of our model with the difference between the two models falling below 1%. Therefore, the proposed model can be adopted as an alternative representation of the equivalent circuit for PV cells and modules

DETERMINATION OF PROTEIN AND FAT OXIDATION LEVELS IN IMPORTED INFANT FORMULA AVAILABLE IN SYRIA

Objective: The aim of this study was to evaluate fat and protein oxidation levels in imported infant formulas [infant formula (IFa1) and follow up formula (IFa2)]; which are available in Syrian market. In addition, the aim was to determine the best conditions for preparing the feeds, and for storage of the opened cans. Methods: Fat oxidation was evaluated by peroxide value (PV) using the iodometric method. Protein oxidation was assessed by the selective indicator protein carbonyls (PCs), using the spectrophotometry method at 280 nm to measure the protein content. Next, the effects of storage at room temperature and refrigerator temperature on both fat and protein oxidation were studied. Furthermore, we studied the changes on fat and proteins oxidation caused by reconstituting the feeds by 40 áµ’C and 70 áµ’C water. Results: PV levels of IFa1 ranged between 0.88 and 1.30 mEqO2 ∕ kg, and were higher than those of IFa2 which ranged between 0.76 and 1.24 mEqO2 ∕ kg. Similarly, PCs levels of IFa1 ranged between 40.5 and 87.6 m mol ∕ kg protein, and were also higher than PCs levels of IFa2 which ranged between 27.78 and 82.96 m mol ∕ kg protein. We found no differences between PCs levels of samples stored at refrigerator and room temperature for 21 d, while PV levels of samples stored at refrigerator temperature were lower than those stored at room temperature for 21 d. For preparation conditions, no differences were observed in oxidation levels between the feed reconstituted by 40 áµ’C and 70 áµ’C water. Conclusion: All IF samples available in Syrian market showed oxidation levels using PV and PCs. Additionally, it is better to keep the opened IF cans at refrigerator temperature than keeping them at room temperature, especially for fat oxidation. Finally, no differences were observed by reconstitution IF by 40 áµ’C and 70 áµ’C water.Â