Interpenetrating photopolymers for intraocular lens application

Interpenetrating photopolymer network materials suitable for intraocular lens application are presented. A rapidly curable, transparent, hydrophobic material with appropriate optical and thermomechanical properties has been prepared from Benzyl acrylate and Benzyl methacrylate. To improve its biocompatibility and optimize surface—cell interactions, this material was modified with respect to its hydrophobicity. Materials which are more hydrophobic, and more hydrophilic, than the base resin were prepared by copolymerization with either a fluoroacrylate or a PEG acrylate respectively. All materials were characterized for their optical and thermomechanical properties. Their in‐vitro cytotoxicity and interaction with mouse fibroblast cells were also studied. It was shown that all materials of the study were biocompatible and more hydrophilic materials resisted cell attachment and may be more suitable for IOL application than their more hydrophobic counter parts of the study. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44496.     

Preparation and characterization of pH sensitive crosslinked Linseed polysaccharides-co-acrylic acid/methacrylic acid hydrogels for controlled delivery of ketoprofen

Some pH responsive polymeric matrix of Linseed (Linum usitatissimum), L. hydrogel (LSH) was prepared by free radical polymerization using potassium persulfate (KPS) as an initiator, N,N-methylene bisacrylamide (MBA) as a crosslinker, acrylic acid (AA) and methacrylic acid (MAA) as monomers; while ketoprofen was used as a model drug. Different formulations of LSH-co-AA and LSH-co-MAA were formulated by varying the concentration of crosslinker and monomers. Structures obtained were thoroughly characterized using Fourier transforms infrared (FTIR) spectroscopy, XRD analysis and Scanning electron microscopy. Sol-gel fractions, porosity of the materials and ketoprofen loading capacity were also measured. Swelling and in vitro drug release studies were conducted at simulated gastric fluids, i.e., pH 1.2 and 7.4. FTIR evaluation confirmed successful grafting of AA and MAA to LSH backbone. XRD studies showed retention of crystalline structure of ketoprofen in LSH-co-AA and its amorphous dispersion in LSH-co-MAA. Gel content was increased by increasing MBA and monomer content; whereas porosity of hydrogel was increased by increasing monomer concentration and decreased by increasing MBA content. Swelling of copolymer hydrogels was high at pH 7.4 and low at pH 1.2. Ketoprofen release showed an increasing trend by increasing monomer content; however it was decreased with increasing MBA content. Sustained release of ketoprofen was noted from copolymers and release followed Korsmeyer-Peppas model.     

Effect of TiO2 and Ta2O5 additions on the electrical properties of Li2CaAl4Si4O16 glass-ceramic

Influence of TiO₂ and Ta₂O₅ on crystallisation for ceramic based on Li–Ca–Al–Si was studied. Sintering of glass-ceramics leads to the formation of β-eucryptite, anorthite and Ca-olivine. These phases are developed only on samples containing TiO₂ and Ta₂O₅. Incorporation of either TiO₂ or Ta₂O₅ gives clear crystals of low pores than in the base sample. Addition of Ta₂O₅ or TiO₂ improves densification properties and reduces sintering temperature. Electrical measurements were done in audio frequency range and lower (90?Hz–100?kHz). Composition changes on electrical properties were examined. Experimental electrical data show that the response of specimens was not simple (not a linear relation). The increase of TiO₂ and Ta₂O₅ generally decreases the electrical properties of the ceramic specimens used in this case. Electrical properties were able to follow and interpret the change in composition. This information was correlated to the internal structure of the samples.     

Synthesis and antimicrobial activity of some polymers derived from modified amino polyacrylamide by reacting it with benzoate esters and benzaldehyde derivatives

Functionalized polymers have gained much interest in the last decades. This is due to their functional groups and their polymer nature, which give them unique properties and more advantages than the corresponding small molecules. In this trend, we modified polyacrylamide by introducing an amino group in the side chain of the polymer by reacting it with ethylenediamine. The amine‐modified polymer was reacted with two classes of active compounds. The first group is aromatic aldehydes containing active groups such as p‐hydroxybenzaldehyde, vanillin, p‐chlorobenzaldehyde, and anisaldehyde. The second group is phenolic ester derivatives such as p‐hydroxymethylbenzoate, 2,4‐dihydroxymethylbenzoate, 2‐hydroxymethylbenzoate and 3,4,5‐trihydroxypropylbenzoate. The antimicrobial activity of these two classes were explored by cut plug method against Candida albicans SC5314, Aspergillus flavus, and Fusarium oxysporium as fungal organisms and Bacillus subtilis, Escherichia coli, and Staphylococcus aureus as bacterial organisms. It was found that the diameter of inhibition zone varied according to the active group in the modified polymer and the examined microorganism. In general, the modified polymers showed antimicrobial activity against the tested microorganisms. However, the polymer derivative of p‐chlorobenzaldehyde being the most effective on bacteria and fungi species. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Development a Novel Integrated Distributed Multi-objective Simulation-optimization Model for Coastal Aquifers Management Using NSGA-II and GMS Models

Water Resources Management - Groundwater is one of the most valuable water resources in the world in terms of quantity and quality. Therefore, their protection as an important issue should be...     

Design and Implementation of Implanted Log Periodic Spiral PIFA in Liver

A design of a log periodic SPIFA （spiral planar inverted-F antenna） is proposed. A way of tuning the SPIFA to work in the ISM band （2.45 GHz） is discussed. The purpose of the antenna is to detect any tumor in the liver depending on the change in the conductivity and the permittivity of the liver after being infected. Detecting liver cancer on its early stages will help in the treatment process and makes it much faster as cancer in early stages can be treated easily. The antenna is designed, simulated and measured in a rabbit＇s liver. The simulated and measured results show great agreement with each other.     

Grafting of acrylic monomers onto cotton fabric using an activated cellulose thiocarbonate–azobisisobutyronitrile redox system

The feasibility of a cellulose thiocarbonate–azobisisobutyronitrile (AIBN) initiation system to induce graft copolymerization of methyl methacrylate (MMA) and other acrylic monomers onto cotton fabric was investigated. Other acrylic monomers were acrylic acid, acrylonitrile, and methyl acrylate. The initiation system under investigation was highly activated in the presence of a metal‐ion reductant or a metal‐ion oxidant in the polymerization medium. A number of variables in the grafting reaction were studied, including AIBN concentration, pH of the polymerization medium, nature of substrate, monomer concentration, duration and temperature of polymerization, and composition of the solvent/water polymerization medium. The solvents used were methanol, isopropanol, 1,4‐dioxane, cyclohexane, benzene, dimethyl formamide, and dimethyl sulfoxide. There were optimal concentrations of AIBN (5 mmol/L), MMA (8%), Fe²⁺ (0.1 mmol/L), Mn²⁺ (8 mmol/L), and Fe³⁺ (2 mmol/L). A polymerization medium of pH 2 and temperature of 70°C constituted the optimal conditions for grafting. The methanol/water mixture constituted the most favorable reaction medium for grafting MMA onto cotton fabric by using the Fe²⁺–cellulose thiocarbonate–AIBN redox system. MMA was superior to other monomers for grafting. The unmodified cotton cellulose showed very little tendency to be grafted with MMA compared with the chemically modified cellulosic substrate. A tentative mechanism for the grafting reaction was proposed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1261–1274, 2004     

Effect of nano layered silicates on automotive polyurethane refinish clear coat

In the present investigation, effect of nano layered silicates on the properties of an automotive refinish clear coat based on polyurethane has been studied. Observation by means of X-ray diffraction (XRD) technique indicates the presence of a partially intercalated structure due to dispersion of nano layers in the polymer matrix. Some levels of hazing have been established by increasing the amount of nano-filler. The effect of nano-filled clear coat on the reflectance spectra of a metallic coated substrate has been studied under three different light sources using a goniospectrophotometer and compared with a blank clear coat to determine if it can be identified by human eye. Scratch and mar resistance tests showed significant improvement even 48 h after application, when there was no gloss reduction due to usage of nano-filler. Gloss retention was increased by about 10% in presence of only 3 wt% of nano-filler. In addition to some scratch and mar resistance tests, other standard tests like adhesion, impact and bending were performed to find out optimum nano-filler/polymer ratio.     

Uscharin,the most potent molluscicidal compound tested against land snails

Calotropis procera, is a shrub with broad ovate fleshy leaves that grows wild in the Egyptian deserts. The plant was discovered to be highly toxic to the land snailsThepa pisana. The active ingredient responsible for the molluscicidal activity was isolated from its latex by solvent extraction and partitioning and was finally purified by fractional crystallization from 95% aqueous ethanol. The purity of the isolated material was monitored by TLC. Chemical identification was carried out using mass, infrared, and proton magnetic resonance spectroscopic methods. The active compound was found to be uscharin, and its identity was confirmed by comparing its spectroscopic data with the literature values. The isolated compound was 128 times more toxic than methomyl to the snails tested.     

Characterization of oxidized reticulated vitreous carbon electrode for oxygen reduction reaction in acid solutions

The oxidation of reticulated vitreous carbon (RVC) and its impact on the oxygen reduction reaction (ORR) in H₂SO₄ solutions has been studied. The results are compared with that of a planar glassy carbon (GC) electrode. The oxidation process was characterized by using different electrode configurations, GC (planar) and RVC electrodes both with flooded (batch process) and flow-through assembly. Cyclic voltammetry, potentiodynamic and rotating ring-disk electrode voltammetry were used for the characterization of the ORR. Anodically oxidized GC and flooded RVC are similar in that the ORR on both electrodes gave a more defined limiting current plateau. For the flow-through porous electrode, the oxidation process caused a distribution of the oxidation extent within the bed thickness, as evident from the SEM images, and only about half of the porous electrode was utilized in the oxidation process. X-ray photoelectron spectroscopy (XPS) measurements confirmed the above distribution and a gradient of the oxygen-to-carbon ratio was obtained within the porous bed. Oxidation of RVC led to an enhancement of its electrocatalytic properties towards ORR. H₂O₂ production was tested at the oxidized RVC from flowing acid solutions. The oxidation of RVC resulted in higher current efficiencies and higher outlet concentrations of the H₂O₂ acid solutions.