Calculations of Thermal Expansivity and Lattice Constant of GaN Using Integer and Noninteger n-Dimensional Debye Functions

A theoretical model to calculate the thermal expansivity and lattice constant are described and used to evaluate the GaN semiconductor. This method is based on the use of integer and noninteger n-dimensional Debye functions for analytical evaluation of the thermal expansivity and lattice constant. The agreement between calculated and experimental values for GaN is generally satisfactory.     

Titanium-containing bioactive phosphate glasses

The use of biomaterials has revolutionized the biomedical field and has received substantial attention in the last two decades. Among the various types of biomaterials, phosphate glasses have generated great interest on account of their remarkable bioactivity and favourable physical properties for various biomedical applications relating to both hard and soft tissue regeneration. This review paper focuses mainly on the development of titanium-containing phosphate-based glasses and presents an overview of the structural and physical properties. The effect of titanium incorporation on the glassy network is to introduce favourable properties. The biocompatibility of these glasses is described along with recent developments in processing methodologies, and the potential of Ti-containing phosphate-based glasses as a bone substitute material is explored.     

Microbiological aspects and challenges of whey powders – I thermoduric,thermophilic and spore-forming bacteria

For dairy processors, spoilage and pathogenic spore-forming bacteria are key sources of concern, not only due to their ability to remain dormant in a desiccated state in powders and to survive heat treatments, but also their ability to form biofilms in the vegetative state that lead to contamination of foods. These include members of the genera Bacillus, Geobacillus, Anoxybacillus, Brevibacillus, Paenibacillus and Clostridium, many of which are associated with food poisoning and spoilage. Here, we review the common bacterial species that form spores in whey powders and their sources and provide insights into their risks and strategies to control them.     

Prediction of critical total drawdown in sand production from gas wells: Machine learning approach

Sand production is a critical issue in petroleum wells. The critical total drawdown (CTD) is an essential indicator of the onset of sand production. Although some models are available for CTD prediction, most of them are proven to lack accuracy or use commercial software. Furthermore, the previous correlations have not studied the trend analysis to verify the correct relationships between the parameters. Therefore, this study aims to build accurate and robust models for predicting CTD using response surface methodology (RSM) and support vector machine (SVM). The RSM is utilized to obtain the equation without using any software. The SVM model is an alternative method to predict the CTD with higher accuracy. This study used 23 datasets to develop the proposed models. The CTD is a strong function of the total vertical depth, cohesive strength, effective overburden vertical stress, and transit time with correlation coefficients (R) of 0.968, 0.963, 0.918, and −0.813. Different statistical methods, that is, analysis of variance (ANOVA), F-statistics test, fit statistics, and diagnostics plots, have shown that the RSM correlation has high accuracy and is more robust than correlations reported in the literature. Moreover, trend analysis has proven that the proposed models ideally follow the correct trend. The RSM correlation decreased the average absolute percent relative error (AAPRE) by 12.7% compared to all published correlations' AAPRE of 22.6%–30.4%. The SVM model has shown the lowest AAPRE of 6.1%, with the highest R of 0.995. The effects of all independent variables on the CTD are displayed in three-dimensional plots and showed significant interactions.     

Improving the performance of LSSVM model in predicting the safety factor for circular failure slope through optimization algorithms

Circular failure can be seen in weak rocks, the slope of soil, mine dump, and highly jointed rock mass. The challenging issue is to accurately predict the safety factor (SF) and the behavior of slopes. The aim of this study is to offer advanced and accurate models to predict the SF of slopes through machine learning methods improved by optimization algorithms. To this view, three different methods, i.e., trial and error (TE) method, gravitational search algorithm (GSA), and whale optimization algorithm (WOA) were used to investigate the proper control parameters of least squares support vector machine (LSSVM) method. In the constructed LSSVM-TE, LSSVM-GSA and LSSVM-WOA methods, six effective parameters on the SF, such as pore pressure ratio and angle of internal friction, were used as the input parameters. The results of the error criteria indicated that both GSA and WOA can improve the performance prediction of the LSSVM method in predicting the SF. However, the LSSVM-WOA method, with root mean square error of 0.141, performed better than the LSSVM-GSA with root mean square error of 0.170.

     

Quantitative study of food integrity climate in Belgian and Saudi Arabian food businesses in view of their organisational characteristics

Managing food integrity within a food business represents a novel dimension in food safety management. In this study, the prevailing food integrity climate of different food companies was analysed and compared across two distinct countries (Belgium and Saudi Arabia), and its relation with various organisational characteristics was examined. A quantitative questionnaire was filled up by the principal quality manager of forty-three food companies. Results show that the overall food integrity climate in the participating Saudi Arabian (n = 15) and Belgian food companies (n = 28) was estimated as medium–high. Scores varied substantially across the different participating food organisations, but only slightly between the two countries. The companies’ certification status was found statistically significantly related to a higher perceived food integrity climate, in particular for ISO 9000 as well as FSSC 22000 in both countries and IFS only in the Saudi Arabian sample. It was also demonstrated that the prevailing food integrity climate is associated with the company’s product type or sector, but only in the Belgian participating food companies, since Belgian quality managers employed in plant-based food companies estimated their food integrity climate higher than their counterparts in animal-based food companies. This horizontal comparative study, based on an intercontinental quantitative assessment of food integrity performance in food companies, contributes to enhance the understanding of food integrity in relation to specific organisational characteristics of food businesses, offering both theoretical and practical implications.     

Evaluation of sericin/collagen membranes as prospective wound dressing biomaterial

Sericin, a silk protein, has high potential for use in biomedical applications. In this study, wound dressing membranes of Sericin (S) and Collagen (C) were prepared by glutaraldehyde cross-linking at S/C; 2:1, 1:1, 1:2, and 0:1 weight ratios. They were stable in water for 4 weeks. However, increasing the proportion of sericin had decreasing effect on the membrane stability. Water swelling property of membranes was enhanced with sericin. The highest water swelling was obtained in 1:1 group (9.06 g/g), but increasing collagen or sericin content in the membranes had a diminishing effect. Highest water vapor transmission rate was obtained with 1:2 group (1013.80 g/m²/day). Oxygen permeability results showed that 1:2 (7.67 mg/L) and 2:1 (7.85 mg/L) S/C groups were better than the other groups. While sericin decreased the tensile strength and elongation of membranes, it increased modulus. Sericin also increased brittleness of membranes, but their UTS range (24.93–44.92 MPa) was still suitable for a wound dressing. Membranes were not penetrable to microorganisms. Cytotoxicity studies showed that fibroblasts and keratinocytes attached and gained their characteristic morphologies. They also proliferated on membranes significantly. After 1 week of subcutaneous implantation, a fibrous capsule formed around all membranes with an acute inflammation. Sericin containing membranes showed signs of degradation (at 2nd week), while collagen only membranes remained largely intact. Eventually, sericin containing membranes degraded in 3 weeks with moderate inflammatory response. Overall results suggest that sericin/collagen membranes would be favorable as wound dressing material when sericin ratio is less than or equal to the collagen component.     

Experimental study of gasoline-ethanol-hydrogen blends combustion in an SI engine

This study presents experimental results of engine performance, combustion and emissions in an SI engine fueled by gasoline-ethanol-hydrogen blends. In the experimental studies, engine performance and emission values were analyzed fueled by gasoline, gasoline-ethanol and gasoline-ethanol-hydrogen blends, respectively. When ethanol has been added volumetrically to gasoline 20% of ethanol (G80E20), engine performance and emissions have been worsened. However, the engine performance and emission values have been improved with the adding of hydrogen to blend. The results showed that the addition of hydrogen to the gasoline-ethanol blend improved the combustion process and improved the combustion efficiency, expanded the combustibility range of the gasoline-ethanol blend, reduced emissions. But, nitrogen oxide emission values increased with the adding of hydrogen.     

An ELISA assay for the rapid diagnosis of acute bacterial meningitis

The de novo purine synthesis inhibitor 5,10-dideazatetrahydrofolate (DDATHF) has previously been shown to inhibit the growth of mouse L1210 and human CCRF-CEM leukemia cells. The present study demonstrates that both the 6R and 6S diastereomers of DDATHF are also cytotoxic to mammalian cells in a stereospecific manner. The cytotoxic potency of (6R)-DDATHF (also known as Lometrexol) towards different cell lines varied by approximately 14-fold and that of (6S)-DDATHF by as much as 156-fold. Compared to (6R)-DDATHF, (6S)-DDATHF was 6.0- and 7.2-fold more cytotoxic to human WiDr colon adenocarcinoma and Chinese hamster ovary (CHO) cells, respectively, and only 1.5- and 2.0-fold more cytotoxic to human T24 bladder carcinoma and mouse L1210 leukemia cells, respectively. However, compared to (6S)-DDATHF, (6R)-DDATHF was 8.7- and 6.9-fold more cytotoxic to C3H/10T1/2 clone 8 and clone 16 mouse fibroblasts, respectively. Weak inhibition of aminoimidazolecarboximide ribonucleotide formyltransferase (AICARFT, EC 2.1.2.3) appeared to have little role in the cytotoxicity of DDATHF diastereomers to WiDr cells during a 24-h exposure. Although glycinamide ribonucleotide formyltransferase (GARFT, EC 2.1.21) is the main biochemical target of DDATHF, DDATHF stereoisomers' cytotoxic potency showed no clear negative correlation with cellular GARFT levels. However, cellular folylpolyglutamate synthetase (FPGS, EC 6.3.2.17) levels correlated with cytotoxic potency in a positive manner. Surprisingly, two enzyme-dose/DDATHF LD90-response curves were observed for FPGS corresponding to differences in (6R) and (6S)-DDATHF cytotoxic potency among the six cell lines studied.