A Novel Method for In Situ Synthesis of Nanostructure Hydroxyapatite–nylon 66 Composites in Tissue Engineering

An interfacial polymerization method for nylon 66 was adapted to produce nanostructured composites with nanohydroxyapatite (n-HA) via in situ polymerization. Nylon 66 was synthesized in n-HA slurry to increase homogeneity and biocompatibility. Synthesis powders was characterized by XRD, TEM, TGA, and FT-IR analysis. The results showed a uniform dispersion in composites, whereas needle-like, n-HA crystals dispersed in condensed polymer matrix. The samples were immersed in SBF for bioactivity tests in different periods, and results were monitored by SEM and EDX in terms of forming an apatite layer. The mechanical properties of the n-HA/nylon66 nanocomposites are discussed in terms of n-HA loading.     

Design,Synthesis, and Fabrication of Chitosan/Hydroxyapatite Composite Scaffold for Use as Bone Replacement Tissue by Sol–Gel Method

Journal of Inorganic and Organometallic Polymers and Materials - Injuries or bone defects are phenomena that are harmful to human health. In the field of bone scaffold tissue engineering,...     

Study of C─H⋯O Bond of Organic–Inorganic Hybrids Based on Polyhydroxybutyrate and Oxides Obtained Via an In Situ Sol–Gel Route

Sol–gel-based zirconia (ZrO₂) and silica (SiO₂) were obtained in situ via hydrolysis–polycondensation of metal alkoxide precursors in membranes of poly(3-hydroxybutyrate) (PHB). What followed was an assessment of thermal and spectroscopic effects from the insertion of the inorganic network in the PHB matrix. The findings exhibited a dependence of both the concentration and the chemical nature of the precursor on the properties of the as-formed inorganic–organic hybrids. The results also indicated that positive nucleating effects, a reduction of the crystallite size and a variation in thermal transitions correlate with spectroscopic data from the alpha and beta crystal forms of the PHB matrix, as well as the crystallization data obtained through polarized light microscopy. POLYM. ENG. SCI., 60:673–681, 2020. © 2020 Society of Plastics Engineers     

Efficient Removal of Methylene Blue Using a Hybrid Organic–Inorganic Hydrogel Nanocomposite Adsorbent Based on Sodium Alginate–Silicone Dioxide

In this work, we reported synthesis, structure characterization and methylene blue (MB) adsorption of a novel organic–inorganic hydrogel nanocomposite adsorbent (HNA) based on sodium alginate (NaAlg) and silicone dioxide nanoparticles (SiO₂-NPs). The HNAs were prepared using grafting of acrylic acid (AA) onto NaAlg by using ammonium persulfate as a free radical initiator and methylene bisacrylamide as a crosslinker in the presence of SiO₂-NPs, which synthesized in situ from the base-catalyzed hydrolysis of tetraethylorthosilicate (TEOS). The structure of HNAs were characterized by FTIR, SEM, EDX, TEM, XRD, UV–Vis and TGA techniques and a proposed mechanism for preparation of adsorbents was also suggested. The swelling capacity of HNAs was examined in buffer solutions with pH ranged 1.0–14.0. The nanocomposites exhibited a pH-responsiveness character so that a swelling-deswelling pulsatile behavior was recorded at pHs 2.0 and 9.0. The swelling kinetics of HNA was also preliminary investigated. Moreover, the effects of agitation time, pH, initial dye concentration, adsorbent dose, TEOS content, AA concentration and temperature were optimized with respect to dye adsorption capacity of HNAs in detail. Furthermore, the kinetic and adsorption isotherm of MB dye onto HNAs were investigated in detail. The HNAs also showed excellent regeneration capacity after five consecutive cycles of dye adsorption–desorption. In general, the results indicated that the synthesized adsorbents with biodegradability and biocompability properties can be used in wastewater treatment via dye adsorption.     

Synthesis and Assessment of Novel Gelatin–Chitosan Lactate Cohydrogels for Controlled Delivery and Tissue Engineering Applications

The current study discusses the synthesis of novel gelatin–chitosan lactate cohydrogels. Mechanical studies indicated the viscoelastic nature of the cohydrogels. The cohydrogels were predominantly elastic in nature. Inherent mechanical stability of the cohydrogels was better than the pristine gelatin hydrogel. Incorporation of chitosan lactate improved the in vitro swelling and the drug release properties of the cohydrogels. The cohydrogels showed good antimicrobial drug delivery capacity. The properties of the developed cohydrogels demonstrated that they could be used as delivery vehicles for antimicrobial drugs. Cell proliferation study suggested that the cohydrogels supported the proliferation of the human keratinocytes.     

Effect of the Synthesis Method on Co-catalysts Based on MCM-41 for the Fischer–Tropsch Reaction

In this work, cobalt catalysts based on ordered mesoporous materials of the MCM-41 type were synthesized and characterized. The synthesis of the catalysts was performed by using different methods: impregnation; incorporation of the metal in the synthesis gel and ionic exchange of the metal by the template. Different characterization techniques were used (N₂ adsorption–desorption, XRD, TPR, SEM and XPS) to study the textural and structural properties of the samples and the metal-support interaction corresponding to each method of synthesis. These samples were tested in the CO Hydrogenation (Fischer–Tropsch Synthesis) by measuring the CO conversion and the selectivity to CO₂ and some groups of hydrocarbons chains. The results show that structural and textural properties as well as the metal-support interactions are affected by the synthesis method. According to this study, catalytic performance is related to the properties of the samples, observing that the metal support interaction highly affects the activity and selectivity of the catalysts.     

Mixed Matrix Membranes Based on Polyamide/Montmorillonite for Pervaporation of Methanol–Toluene Mixture

Novel mixed matrix membranes were obtained by the dispersion of montmorillonite (MMT) nanoparticles in poly(phenylene-iso-phtalamide) (PA) matrix. Membrane structure was determined on the basis of density measurement and morphology study by SEM. The effect of MMT inclusion on membrane hydrophilic properties was estimated by the measurement of contact angles of water, methanol, and toluene, respectively, and the calculation of surface tension. Transport properties of PA/MMT membranes were studied by use of swelling and pervaporation tests. The prepared membranes were used in the pervaporation of methanol–toluene mixtures. Total fluxes and separation factors, such as permeabilities and selectivities, were determined. It was established that the improvement of some physicochemical properties and transport parameters occurs only by inclusion up to 3 wt% MMT in the PA matrix.     

Preparation,Characterization and Assessment of the Novel Gelatin–tamarind Gum/Carboxymethyl Tamarind Gum-Based Phase-Separated Films for Skin Tissue Engineering Applications

The current study delineates the development of novel gelatin–tamarind gum/carboxymethyl tamarind gum-based phase-separated films for probable skin tissue engineering applications. Polyethylene glycol was used as plasticizer. The films were characterized thoroughly using mechanical tester and impedance analyzer. Cell proliferation ability and drug release properties of the films were investigated. Mechanical studies indicated composition-dependent stress relaxation properties. Polysaccharide containing films supported better proliferation of human keratinocytes as compared to control. Drug-loaded films showed good antimicrobial properties against Escherichia coli. Analysis of the results indicated that the prepared films may be tried as matrices for skin tissue engineering.     

Technology for Oil Sludge Disposal Based on Liquid and Supercritical Fluid Extraction with Propane–Butane Extractant

The results of using the processes of liquid and supercritical fluid extraction to separate petroleum products from oil sludge have been presented. A mixture that consists of 75 wt % propane and 25 wt % butane has been used as an extractant. The initial oil sludge is characterized by the absence of water and a content of mechanical impurities in the amount of 12.05 wt %. Extraction processes are carried out in the temperature range of 85–160°C and pressure interval of 5–50 MPa. The results of modeling the extraction process for the separation of petroleum products from oil sludge have been presented.     

Electrochemical Sensor for Detection of Trichlorfon Based on Molecularly Imprinted Sol–Gel Films Modified Glassy Carbon Electrode

Thin films of molecularly imprinted sol–gel polymer with specific binding sites for trichlorfon were prepared, fixed on glassy carbon electrodes and used as recognition material. The binding characteristic of the imprinted films to trichlorfon was evaluated by equilibrium binding experiments; and, the morphology was studied by scanning electronic microscope. A novel electrochemical sensor for determination of trichlorfon was developed based on the reaction between trichlorfon and the molecularly imprinted sol–gel film, which was a modified glassy carbon electrode. The sensor displayed excellent selectivity and high sensitivity. The linear response range of the sensor was 10⁻⁸ –10⁻⁶ g mL⁻¹, and the limit of detection was 2.8 × 10⁻⁹ g mL⁻¹. The relative standard deviation for the determination of 10⁻⁷ g mL⁻¹ trichlorfon was 3.5%. The sensor was applied to the determination of trichlorfon in vegetables with satisfactory results.     

Development of a Novel High-Performance Thin Layer Chromatography–Based Method for the Simultaneous Quantification of Clinically Relevant Lipids from Cells and Tissue Extracts

Lipids such as cholesterol, triacylglycerols, and fatty acids play important roles in the regulation of cellular metabolism and cellular signaling pathways and, as a consequence, in the development of various diseases. It is therefore important to understand how their metabolism is regulated to better define the components involved in the development of various human diseases. In the present work, we describe the development and validation of a high-performance thin layer chromatography (HPTLC) method allowing the separation and quantification of free cholesterol, cholesteryl esters, nonesterified fatty acids, and triacylglycerols. This method will be of interest as the quantification of these lipids in one single assay is difficult to perform.     

Structural Effect of Pincer Pd(II)–ONO Complexes Modified with Acylthiourea on Sizes of the In Situ Generated Pd Nanoparticles During Heck Coupling Reaction

Catalysis Letters - The Pd nanoparticles generated in situ from Pd–pincer complexes catalyzed Heck coupling reaction. For this purpose, new Pd(II)–ONO pincer complexes (1–4)...     

Study on Adhesion Properties of a Hot-Melt Pressure-Sensitive Adhesive Based on Epoxidized Styrene–Isoprene-Styrene Triblock Copolymers (ESIS) for Transdermal Drug Delivery Systems

Pressure sensitive adhesives are a critical component in transdermal drug delivery systems (TDDS). In this study, styrene-isoprene-styrene triblock copolymers (SIS) was epoxidized with peroxyformic acid generated in situ. The hot-melt pressure sensitive adhesive (HMPSA) of ESIS with hydrogenated rosin, epoxidized soybean oil, and antioxidant was prepared. The structure and properties of ESIS were characterized with infrared spectroscopy and dynamic mechanical analysis (DMA). Water content and water vapor transmission rate on ESIS membranes were determined. The adhesion properties of HMPSA of ESIS were investigated. The experimental results showed that the HMPSA of ESIS was superior to traditional HMPSA of SIS in 180°peel strength when the substrates were polar materials, such as PVC and steel.     

Preparation,Characterization, and Properties of Novel Polyimide–SiO2 Hybrid Composites Based on Bipyridine for Low Dielectric Applications

Novel low dielectric polyimide–SiO₂ hybrid materials containing bipyridine were prepared with three-step sol–gel process from poly(amic acid)s. (3-Aminopropyl)triethoxysilane as coupling agent was used to increase the intrachain chemical bonding between the polyimide and SiO₂ groups. The thermal, dielectric, and physical properties of the hybrid materials were investigated and correlated with the porous structure. The glass transition temperatures of all the hybrids were found to be higher than polyimides. The effect of SiO₂ groups on the porous structure and dielectric properties was investigated. The dielectric constant of the hybrid materials was observed a decrease from 3.30 to 2.15 with increased SiO₂ amount.     

Effect of the Nature of the Binder on the Formation Temperature of Glass-Ceramic Coatings Based on Si–B–ZrB<Subscript>2</Subscript> for Graphite Protection

This work is devoted to fabricating and studying the properties of coatings based on the Si–B–ZrB₂ systems used in graphite protection. The kinetics of the oxidation of graphite with coatings at different temperatures in air are investigated. The optimal conditions for the thermal treatment of the material with the coating are suggested.     

Effect of Acid–Base Properties on the Catalytic Activity of Pt/Al2O3 Based Catalysts for Diesel NO Oxidation

The activity of Pt catalysts supported on Al₂O₃ modified with various acid–base additives has been investigated for oxidation of NO to NO₂. Although Pt dispersion was changed by the additives, there was no clear effect of Pt dispersion on the catalytic activity. The measurement of solid acid–base properties of the modified Pt/Al₂O₃ indicated that the NO oxidation activity increased by the increase of surface density of strong acid sites and decreased by the increase of basic sites. It was suggested that platinum on the acidic supports keeps its highly active metallic state for NO oxidation, while the formation of nitrate/nitrite on the basic supports inhibits the reaction on the Pt surface.