Mechanical and thermodynamic properties of butyl acrylate-N-vinylpyrrolidone hydrogels

Copolymerization to almost 100% conversion has been effected by the γ-irradiation of mixtures of n-butyl acrylate (BA) and N-vinyl-2-pyrrolidone (VP) in the presence of a crosslinking agent, 1,1,1-trimethylolpropane trimethacrylate (TPT). Swelling in water at 294 K yielded hydrogels having equilibrium water contents in the range 1–89%, the corresponding extension ratios and volume fractions of water being obtained from dimensional changes on swelling. Stress(compression)-strain measurements yielded the compression and Young's moduli, the effective crosslinking density (v_e) and the copolymer-water interaction parameters (χ). From the linear dependence of v_e on the theoretical value based on the concentration of TPT, the efficiency of crosslinking was found to increase with increasing BA content; a finite v_e was also interpolated to exist even in the absence of added TPT. Increasing the VP content of xerogels produced a corresponding increase and decrease in the fractional contents of water and BA respectively within the hydrogels, whereas the fractional content of VP displayed an increase followed by a decrease. This latter behaviour mirrors that exhibited by v_e and the elastic moduli. Possible explanations are proposed.     

Influence of crude olive leaf juice on rat liver and kidney functions

Crude juice of olive leaves (Kronakii cultivar) was obtained by hydraulic press. The level of polyphenlic compounds in the juice was 215 ppm. An aliquots of the concentrated olive leaf juice, represent 600, 1200 and 2400 ppm as polyphenols and butylated hydroxy toluene (BHT; 200 ppm) were administered to rats daily for 6 weeks by stomach tube. The liver (aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase activities) and kidney (bilirubin, uric acid, creatinine and urea) function tests and serum contents (total lipids, total cholesterol and low and high‐density lipoproteins) were measured to assess the safety limits of the polyphenolic compounds in the olive leaf juice. The data of the aforementioned measurements indicated that the administration of olive leaf juice did not cause any changes in liver and kidney functions. On the contrary, BHT at 200 ppm induced significant increases in the enzyme activities and the serum levels of total lipids, uric acid, urea and creatinine. Microscopical examinations of kidney and liver tissues of rats administered with the phenolic compounds of olive leaf juice had the histological character as that of control rats whilst, the administration of BHT at 200 ppm altered the features of rat liver tissues and severely damaged the rat kidney tissues.     

Design and testing of high-density polyethylene nanocomposites filled with lead oxide micro- and nano-particles: Mechanical,thermal, and morphological properties

This research discusses the mechanical behavior and the microstructure of high-density polyethylene (HDPE)-based composites, manufactured using the melt-mixing and thermal-pressing techniques, where HDPE is mixed with various percentages of either bulk lead monoxide (bulk PbO) or PbO nanoparticles (PbO-NPs) acting as fillers. The scanning electron microscope and the field emission transmission electron microscope were utilized to identify the morphology of polymeric composites. Both showed the proper dispersion of PbO in the HDPE matrix without substantial agglomerations. The effect of PbO on the thermal behavior of the HDPE was studied using the thermogravimetric analysis. Tensile tests were implemented to find out how the mechanical characteristics of the composites were affected. Yield stress, % elongation at break, stiffness, tensile energy (toughness), ultimate tensile strength, and ultimate tensile strain were elucidated in this work. The values of stiffness, ultimate tensile strength, and yield stress increased by increasing either the bulk PbO or PbO-NPs' loading up to 40.0 wt % with reference to the hosting matrix. The values of ultimate tensile strain, tensile energy, and % elongation at break of the assembled composites diminished dramatically by increasing the filler's content from 10.0 to 50.0 wt %. Besides, composites with PbO-NPs as a filler were identified as having higher mechanical characteristics than those with bulk PbO for the same wt %. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47812.     

Improved Slime Mould Algorithm based on Firefly Algorithm for feature selection: A case study on QSAR model

Feature selection (FS) methods are necessary to develop intelligent analysis tools that require data preprocessing and enhancing the performance of the machine learning algorithms. FS aims to maximize the classification accuracy by minimizing the number of selected features. This paper presents a new FS method using a modified Slime mould algorithm (SMA) based on the firefly algorithm (FA). In the developed SMAFA, FA is adopted to improve the exploration of SMA, since it has high ability to discover the feasible regions which have optima solution. This will lead to enhance the convergence by increasing the quality of the final output. SMAFA is evaluated using twenty UCI datasets and also with comprehensive comparisons to a number of the existing MH algorithms. To further assess the applicability of SMAFA, two high-dimensional datasets related to the QSAR modeling are used. Experimental results verified the promising performance of SMAFA using different performance measures.

     

Evaluation of the dielectric properties of grease containing copolymers and ester

Poly(1-octadecene-co-maleic anhydride) bis behanate ester, poly(1-octadecene-co-maleic anhydride) bis stearate ester, and ethylene glycol bis stearate ester were prepared and their structures were confirmed by IR spectroscopy. Wax gel was prepared from base oil blend (base lube oil grade 260/290, transformer oil) and microcrystalline wax in ratio 2.3 : 1, respectively, in the presence of antioxidant and anticorrosion additives in ratio of 0.1–2%. Atactic polypropylene was added in mixture with the above copolymers and ester to the wax gel in different proportions. Dielectric constant, dielectric loss, and volume resistivity at frequency range of 1–10³ kHz 35°C have shown better results than that of wax gel alone. The grease which includes poly(1-octadecene-co-maleic anhydride) bis behanate ester in mixture with atactic polypropylene recorded the best results. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and antimicrobial activity of the Schiff base from polyoxyalkylene‐montmorillonite nanocomposites and aldehydes

Vanillin (4‐hydroxy‐3‐methoxy benzaldehyde) and 5‐formylamino salicylic acid microbicides were reacted with polyoxyalkylene‐montmorillonite (D_230–2000‐MMT) nanocomposites. The microstructure of these Schiff base nanocomposites was characterized by TEM and XRD. D_230–2000‐MMT nanocomposites were prepared by an ion exchange process of sodium montmorillonite (Na‐MMT) and NH₃ ⁺ groups in polyoxyalkylene amine hydrochloride with three different molecular masses of D₂₃₀, D₄₀₀, and D₂₀₀₀. Wide‐angle X‐ray diffraction confirms the intercalation of the polymer between the silicate layers. Electrostatic interaction between the positively charged NH₃ ⁺ groups and the negatively charged surface of MMT was observed. The nanocomposites were tested for antimicrobial activity against the Gram‐negative bacteria (Escherichia coli NCIM 2065), Gram‐positive bacteria (Bacillus subtillus ATCC), and fungi (Candida albicans SC5314 and Cryptococcus neoformans). The D₂₀₀₀‐MMT/vanillin Schiff base nanocomposite strongly inhibited the growth of all microorganisms that can be used in different applications. The amount of loaded polymer and the structure of the nanocomposite play an important role in inhibiting the bacterial and fungal strains. It is found that the Schiff base nanocomposite affect the morphology, oxygen consumption, and the release of cytoplasmic constituents such as potassium (K⁺), sodium (Na⁺), and calcium (Ca²⁺) ions leading to death of the cells. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

A New Decision-Making Model Based on Plithogenic Set for Supplier Selection

Supplier selection is a common and relevant phase to initialize the supply chain processes and ensure its sustainability. The choice of supplier is a multi-criteria decision making (MCDM) to obtain the optimal decision based on a group of criteria. The health care sector faces several types of problems, and one of the most important is selecting an appropriate supplier that fits the desired performance level. The development of service/product quality in health care facilities in a country will improve the quality of the life of its population. This paper proposes an integrated multi-attribute border approximation area comparison (MABAC) based on the best-worst method (BWM), plithogenic set, and rough numbers. BWM is applied to regulate the weight vector of the measures in group decision-making problems with a high level of consistency. For the treatment of uncertainty, a plithogenic set and rough number (RN) are used to improve the accuracy of results. Plithogenic set operations are used to deal with information in the desired manner that handles uncertainty and vagueness. Then, based on the plithogenic aggregation and the results of BWM evaluation, we use MABAC to find the optimal alternative according to defined criteria. To examine the proposed integrated algorithm, an empirical example is produced to select an optimal supplier within five options in the healthcare industry.