A comparative study on antibacterial activities of chitosan based products and their combinations with gentamicin against S. epidermidis and E. coli

Antibacterial activity of chitosan, and a graft copolymer based on chitosan namely chitosan-graft-poly(N-vinyl imidazole), (Chi-graft-PNVI), was studied against Staphylococcus epidermidis (S. epidermidis) and Escherichia coli (E. coli). The graft copolymer was prepared by two different methods; via an N-protection route and without N-protection to observe the effect of free amine groups on the antibacterial activity. It was further investigated whether a combination of each of these products would produce a synergetic effect with the antibiotic gentamicin against S. epidermidis and E. coli compared to gentamicin alone. Antibacterial activity was determined by the inhibition zone measurement method. Results reveal an improvement in the antibacterial activity of gentamicin, when combined with chitosan or chitosan-based biomaterials against S. epidermidis and E. coli compared to that of gentamicin itself. When gentamicin is used in combination with Chi-graft-PNVI prepared via N-protection, antibacterial activity against S. epidermidis is three times higher in comparison with the activity of gentamicin alone according to the inhibition zone measurements. Gentamicin produces an inhibition zone of 8.2 ± 0.2 mm against S. epidermidis when undiluted, while the inhibition zone increases to 25.8 ± 0.7 mm in combination with Chi-graft-PNVI prepared via N-protection. These combinations have a potential to form a basis for new formulations of gentamicin with improved antibacterial activity and might allow usage of decreased doses of the antibiotic.     

Surface-initiated growth of copper using isonicotinic acid-functionalized aluminum oxide surfaces

Isonicotinate self-assembled monolayers (SAM) were prepared on alumina surfaces (A) using isonicotinic acid (iNA). These functionalized layers (iNA-A) were used for the seeded growth of copper films (Cu-iNA-A) by hydrazine hydrate-initiated electroless deposition. The films were characterized by scanning electron microscopy (SEM), electron-dispersive X-ray spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and advancing contact angle measurements. The films are Cu⁰ but with surface oxidation, and show a faceted morphology, which is more textured (R _q = 460 ± 90 nm) compared to the SAM (R _q = 2.8 ± 0.5 nm). In contrast, growth of copper films by SnCl₂/PdCl₂ catalyzed electroless deposition, using formaldehyde (CH₂O) as the reducing agent, shows a nodular morphology on top of a relatively smooth surface. No copper films are observed in the absence of the isonicotinate SAM. The binding of Cu²⁺ to the iNA is proposed to facilitate reduction to Cu⁰ and create the seed for subsequent growth. The films show good adhesion to the functionalized surface.     

Development of natural and synthetic polymer-based semi-interpenetrating polymer network for controlled drug delivery: optimization and in vitro evaluation studies

This research paper describes the development, optimization and in vitro characterization of chemically cross-linked pectin–polyvinyl alcohol-co-poly(2-Acrylamido-2-methylpropane sulfonic acid) semi-interpenetrating polymer network hydrogel [pectin–PVA-co-poly(AMPS) semi-IPN hydrogel] for controlled delivery of model drug tramadol HCl. Response surface methodology based on 3² factorial design was used for optimization and investigating the effect of independent factors: polymer-blend ratio (pectin:PVA = X ₁) and monomer (AMPS = X ₂) concentration on the dependent variables, swelling ratio (q _18th), percent drug release (R _18th, %), time required for 80 % drug release (t _{80 %}, h), drug encapsulation efficiency (DEE, %) and drug loaded contents (DLC, mg/g) in pectin-PVA-co-poly(AMPS) gels prepared by free radical polymerization. The optimized semi-IPN gel (FPP-10) showed controlled in vitro drug release (R _18th) of 56.34 % in 18 h, t _{80 %} of 30 h, and DEE of 23.40 %. These semi-IPN hydrogels were also characterized through SEM, FTIR, sol–gel analysis, swelling studies and drug release characteristics. Therefore, this newly synthesized polymeric network could be a potential polymeric system for controlled drug delivery of tramadol HCl for prolonged drug release.     

Melt processing of biodegradable poly(lactic acid)/functionalized chitosan nanocomposite films: mechanical modeling with improved oxygen barrier and thermal properties

The present work demonstrates about the formulation of functionalized chitosan (CH-g-OLLA) through the transformation of hydrophilic nature of chitosan into hydrophobic by grafting with oligo(L-lactic acid) (OLLA). The developed CH-g-OLLA is easily soluble in poly(lactic acid) (PLA) matrix, which provides an opportunity towards producing industrially viable nanocomposite films for stringent food packaging and beverages applications. The grafting of OLLA chains is confirmed at NH₂ group of chitosan through the presence of two new peaks at 4.2 and 5.1 ppm in ¹H–NMR spectra. Various parameters like yield (%), grafting efficiency (%) and percent grafting (%) are calculated as ~51.6, ~40 and ~150%, respectively. Functionalized chitosan has been utilized as nano-filler in PLA matrix to fabricate PLA/CH-g-OLLA nanocomposite films which have compounded successfully by co-rotating twin screw compounder cum cast film extrusion technique (distinctly advantageous over conventional solution casting) at bench scale as well as semi-pilot scale and further demonstrated for its application in the area of food packaging with tailored oxygen barrier properties. Uniform dispersion of spherical aggregates of functionalized chitosan is observed in PLA/CH-g-OLLA nanocomposite films using TEM analysis. A significant reduction up to ~11 °C in glass transition temperature of PLA is observed by adding 5 wt% of nano-filler as a result of plasticization effect, which is an essential property in designing of flexible packages. Mechanical modeling of extruded PLA/CH-g-OLLA films has been performed to compare the experimental values with theoretical results using various mathematical models in which modified foam model, Nielsen model and modified Mitsuishi model demonstrate the best match for Young’s modulus (±0.08), tensile strength (±0.06) and percentage elongation (±0.03), respectively. This may be a significant contribution towards commercialization of such formulation where elegant melt extrusion process of PLA with functionalized chitosan is capable of reducing oxygen permeability up to ~10 folds due to a drastic reduction (~96%) in oxygen solubility.     

Synthesis and self-assembly behavior of POSS tethered amphiphilic polymer based on poly(caprolactone) (PCL) grafted with poly(acrylic acid) (PAA) via ROP,ATRP, and CuAAC reaction

This investigation reports the preparation and self-assembly behavior of polyhedral oligomeric silsesquioxane (POSS) containing poly(caprolactone)-graft-poly(acrylic acid) (POSS-PCL-graft-PAA) polymer. This article focuses on the self-assembly behavior of POSS tethered amphiphilic graft copolymer. In this investigation, POSS tethered alkyne functionalized polycaprolactone (PCL) was prepared by strategic ring opening polymerization (ROP) of ε-caprolactone and α-propargyl-ε-caprolactone using hydroxyl-terminated POSS as an initiator. Azide-terminated poly(tert-butyl acrylate) (P ^t BA) was grafted onto functional PCL via Cu-catalyzed azide-alkyne “click” (CuAAC) reaction. Finally, hydrolysis of the tert-butyl ester group into acid furnished the POSS tethered PCL-graft-PAA polymer. This amphiphilic graft copolymer was characterized by GPC, NMR, and FT-IR analyses and the morphology of the graft copolymer analyzed by HRTEM and FESEM analyses. On changing the graft copolymer concentration (low to high) in water, the morphology of the final graft copolymer changed from micelles to worm-like and core-shell. The structural motif of POSS plays an important role in this morphological transformation. The pH sensitivity was studied using DLS analysis as well as via release profile of rhodamine B as a model compound.     

Iron chelating polypropylene films: Manipulating photoinitiated graft polymerization to tailor chelating activity

Transition metals, especially iron, enhance the oxidative degradation of lipids. Nonmigratory metal chelating active packaging can inhibit lipid oxidation and meet consumer demand for ‘cleaner' labels. Recently, the development of iron chelating films prepared by photoinitiated graft polymerization of acrylic acid on polypropylene (PP‐g‐PAA) was reported. The objective of this study was to tailor the chelating activity of PP‐g‐PAA by manipulating graft conditions. Carboxylic acids graft density and PAA graft thickness increased with graft time and acrylic acid concentration, with carboxylic acids density of up to 143 ± 32 nmol cm^?2, PAA graft thickness of ～6–18 μm, and ligand (carboxylic acid) to metal (Fe²⁺) binding ratio of ～4–5. Reducing photoinitiator graft density decreased this ratio to ～2–2.5, suggesting that graft chain density influences chelating activity. This work demonstrates the ability to tailor chelating activity of PP‐g‐PAA with potential applications in active packaging, chelation therapy, and water purification. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39948.     

Synthesis,structural, thermal,optical and dielectric properties of chitosan biopolymer; influence of PVP and <Emphasis Type="Italic">α</Emphasis>-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> Nanorods

The present work reports the influence of Polyvinylpyrrolidone (PVP) and hematite (α-Fe₂O₃) nanorods (NRs) on the physicochemical properties of chitosan (Cs), as an approach to broaden its medical and technological applications. Hematite NRs of 11.4 nm diameter and 87.9 nm crystallite size were prepared by a free-template chemical method. Cs, PVP/Cs and blend loaded with hematite NRs were prepared by solution casting. Significant changes in the films’ surface were clarified using the scanning electron microscope (SEM). Fourier transformation infrared spectroscopy (FT-IR) confirmed the interaction between the NRs and the NH₂ and OH functional groups of Cs. DSC measurements showed one endothermic peak assigned to the water elimination, and an exothermic one, in the range 268–287 °C, attributed to the decomposition of saccharine structure in Cs. The swelling properties of the films were sensitive to the pH of the solution. PVP/Cs film showed ~ 85% transmittance in the visible region and its optical band gap narrowed from 5.4 eV to 4.05 eV after loading with 2.0 wt.% hematite. The influence of NRs content on the optical constants of the films is discussed. The dielectric properties depend on the film’ structure. The large Polaron tunneling (LPT) model is the best suitable mechanism for the electric conduction. Due to their high thermal stability and decomposition temperature, transmittance and high conductivity, the prepared films are a candidate for the packaging industry, for use in some medical applications such as treating some chronic wounds, and optical windows and fibers.     

Enzymatic Interesterification of Coconut and High Oleic Sunflower Oils for Edible Film Application

Blends [60:40, 70:30, and 80:20 (w/w)] of coconut oil (CO) and high oleic sunflower oil (HOSO) were interesterified using immobilized enzyme, Lipozyme^® TL IM (Novozymes North America Inc., Franklinton, NC, USA). The structured lipids (SLs), referred to as interesterified products (IPs) IP60:40, IP70:30, and IP80:20, were compared to CO and HOSO for application in edible films. IPs were compared based on fatty acid profile, TAG molecular species, melting profile, moisture vapor permeability, mechanical properties, film transparency, density, and thickness. Interesterification increased oleic acid content at the sn-2 position of IPs. CO had 5.50 ± 1.67 mol% oleic acid at the sn-2 position, and when interesterified with HOSO (92.81 ± 1.10 mol% oleic acid) the amount of oleic acid significantly increased (p < 0.05) at the sn-2 position for IP60:40, IP70:30, and IP80:20 (33.86 ± 1.55, 27.34 ± 1.20, 20.61 ± 1.50 mol%), respectively. There was no significant difference between SLs, HOSO, and CO for water vapor permeability and density when applied to emulsion edible films. The HOSO film was significantly different (1.43 ± 0.27 AUmm^?1) from the rest of the SLs and CO for film transparency. IP60:40 (2.20 ± 0.22 AUmm^?1) decreased the opacity and was significantly different from HOSO and IP80:20 (2.88 ± 0.08 AUmm^?1). Tensile strength of IP60:40 was 0.39 ± 0.17 MPa which was significantly different from IP70:30, IP80:20, and HOSO. The elongation at break was significantly different for HOSO and IP60:40. IP60:40 could be used to further investigate the use of SL in edible film for sports nutrition products.     

Synthesis and properties of novel soluble fluorinated aromatic polyamides containing 4-benzoyl-2,3,5,6-tetrafluorophenoxy pendant groups

A new diaroyl chloride monomer, 5-(4-benzoyl-2,3,5,6-tetrafluorophenoxy)isophthaloyl dichloride (BTFPIPC), was prepared in a three-step synthesis. Six novel aromatic polyamides containing 4-benzoyl-2,3,5,6-tetrafluorophenoxy pendant groups were synthesized by low temperature polycondensation of BTFPIPC with six aromatic diamines in N,N-dimethylacetamide (DMAc). All these new polymers are amorphous and readily soluble in various dipolar solvents such as DMAc, N-methyl-2-pyrrolidinone (NMP), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) at room temperature. These polymers showed glass transition temperatures between 212 and 243 °C and 5% weight loss temperatures ranging from 439 °C to 456 °C. These polyamides could be cast into transparent, flexible and strong films from DMAc solution with tensile strengths of 73.5–85.4 MPa, tensile moduli of 2.06–2.72 GPa, and elongations at break of 6.4–9.3%. These new polyamide films exhibited low dielectric constants of 3.26–3.57 (1 MHz), lower water uptakes in the range of 1.27–2.28%, and excellent transparency with an ultraviolet-visible absorption cut-off wavelength in the 326–373 nm range. Primary characterization of these new polyamides shows that they might serve as new candidates for processable high-performance polymeric materials.     

Biomimetic design of chelating interfaces

Siderophores are naturally occurring small molecules with metal binding constants greater than many synthetic chelators. Herein, we report a two‐step process to graft a siderophore‐mimetic metal chelating polymer from a polypropylene (PP) surface. Poly(methyl acrylate) was first grafted from the PP surface by photoinitiated graft polymerization, followed by the conversion into poly(hydroxamic acid) (PHA) to obtain PP‐g‐PHA films. ATR/FTIR, contact angle, SEM, and AFM were performed to characterize surface properties of films. Iron binding kinetics and the influence of pH (3.0–5.0) on the chelating ability of films were determined. PP‐g‐PHA exhibited significant iron chelating activity (～80 nmol/cm²) with an equilibration time of 24 h. The materials retained 50% chelating ability at pH 3.0 compared with pH 5.0, almost double the retention of previously reported polycarboxylate chelating interfaces. By using siderophore‐mimetic surface chemistry, such effective metal chelating interfaces can extend the applications of metal chelating polymers in environmental remediation, water purification, and active packaging areas. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41231.     

New potassium sodium niobate/poly(vinylidene fluoride) functional composite films with high dielectric permittivity

New and homogeneous KNN/PVDF functional hybrid films loaded with 2 vol.%, 4 vol.%, 9 vol.%, 21 vol.%, 30 vol.%, and 40 vol.% Na_0.5K_0.5NbO₃ (KNN) have been prepared by a solution casting process. The effects of the doping KNN particles on the structure, morphology, and dielectric properties of KNN/PVDF hybrid films were investigated. The introduction of KNN fillers has a remarkable influence on the α-, β-, γ-phase structure and the crystallinity of the polymer matrix. And it is also effective in improving the dielectric performance. A dielectric permittivity as high as 250 is obtained at 10 Hz when the concentration of the KNN filler reaches 30 vol.%, which is 28 times higher than that of the pure PVDF matrix. The conductivity of the hybrid film with 40 vol.% KNN concentrations is lower than 8 × 10^?10 (S cm^?1) at 10² Hz and at room temperature, which shows its excellent insulativity and the potential to be applied into the electronic industry.     

Preparation,physicochemical properties and biocompatibility of biodegradable poly(ether-ester-urethane) and chitosan oligosaccharide composites

In the paper, novel composites of biodegradable poly(ether-ester-urethane) (PEEU) and water-soluble chitosan oligosaccharide (CHO) were prepared using a simple physical mixing method and their potential application as biomaterials was assessed. The PEEU and CHO were dissolved in N,N-dimethylformamide to get a homogenous solution, then the composite films were obtained by the solvent evaporation method. The composites were characterized by FT-IR, and the influence of CHO content on the physicochemical properties of the composite films, including thermal properties, surface morphologies, mechanical properties, surface and bulk hydrophilicity, and in vitro biodegradability, were researched. The thermal stability studies indicated that the composite films had lower initial decomposition temperature and higher maximum decomposition temperature than PEEU film. Only one broad endothermic peak found in DSC curves demonstrated the high compatibility of CHO with PEEU. The ultimate stress and elongation at break of composite films decreased with the increment of CHO content, and the CHO content in the composites should be controlled no more than 25 wt% in order to maintain the mechanical properties (ultimate stress: 18.5 MPa; elongation at break: 890%) to meet the requirement of implant materials. The surface morphologies of composite films were observed by cold field emission scanning electron microscope (FE-SEM), and the results indicated that the homogeneous-dispersed composites could be obtained with CHO content being less than 20 wt%. The results of water contact angle and water absorption showed that the surface and bulk hydrophilicity were closely related with the water-solubility of CHO component. In vitro degradation studies showed that the degradation rate increased with the increasing content of CHO in composites, indicating that the degradation rate of composite films could be controlled by adjusting CHO content. The surface blood compatibility of the composite films was examined by bovine serum albumin adsorption and platelet adhesion tests. It was found that composite films had improved resistance to protein adsorption and possessed excellent resistance to platelet adhesion.     

New functional copolymers of <Emphasis Type="Italic">N</Emphasis>-acryloyl-<Emphasis Type="Italic">N</Emphasis>′-methyl piperazine and 2-hydroxyethyl methacrylate: synthesis,determination of reactivity ratios and swelling characteristics of gels

Copolymers of N-acryloyl-N′-methylpiperazine (AcrNMP) and 2-hydroxyethyl methacrylate (HEMA) were synthesized by free radical solution polymerization in dioxane at 70 ± 1 °C, using 2,2′-azobisisobutyronitrile (AIBN) as initiator. The copolymer compositions were analyzed by the methods of FTIR spectroscopy and elemental analysis. Both the method of analysis yielded results that agreed reasonably well. The monomer reactivity ratios of the copolymerization were determined by the linearization methods of Finemann–Ross (FR) and Kelen–Tüdös (KT). The reactivity parameter results derived using FTIR analysis showed that the copolymerization yielded mainly alternating structure with reactivity ratios, r ₁(AcrNMP) = 0.263 ± 0.011 and r ₂(HEMA) = 0.615 ± 0.097 by F–R method and r ₁ = 0.227 ± 0.074 and r ₂ = 0.53 ± 0.15 by KT method. Microstructure data calculated by the method of Igarashi also supports the alternating structure (tendency) of the copolymer. Crosslinked polymer gels of this system exhibited remarkably high swelling of more than 500% in water at ambient temperature.     

Physical properties and shape memory behavior of thermoplastic polyurethane/poly(ethylene-<Emphasis Type="Italic">alt</Emphasis>-maleic anhydride) blends and graphene nanoplatelet composite

A new thermoplastic polyurethane (TPU) was prepared from polylactide-b-poly(ethylene glycol)-b-polylactide (soft segment) and 2,4-toluene diisocyanate (hard segment). Then, TPU in various proportions (i.e., 50, 70, and 90 wt%) was blended with poly(ethylene-alt-maleic anhydride) (PEMA) to form samples coded as TPU/PEMA50, TPU/PEMA70, and TPU/PEMA90. The TPU and PEMA blend at ratio of 50:50 was reinforced by various graphene nanoplatelets (GNPs) contents. Three novel strategies were opted in this research, including design of novel thermoplastic polyurethane, blend of TPU with poly(ethylene-alt-maleic anhydride), and fabrication of graphene nanoplatelet-based nanocomposites. Hydrogen bonding between blend component and GNPs directed the formation of regular nanostructure. Consequently, unique self-assembled flower-shaped morphology was observed in blends as well as hybrid materials using the scanning electron microscopy technique. Physical interlinking between blend components and nanofiller was also responsible for rise in tensile modulus (39.3 MPa) and Young’s modulus (4.04 GPa) of the TPU/PEMA/GNP 5 hybrid compared with the neat blend. The crystallization property was studied by the X-ray diffraction analysis and differential scanning calorimetry. The melting temperature of about 70 °C was preferred for the shape recovery studies. The results from heat-induced shape recovery were compared with those of electroactive shape memory effects. Electrical conductivity was increased to 0.18 S cm^?1 using 5 wt% GNP nanofiller, which was dependent on the applied temperature, as well. The original shape of TPU/PEMA/GNP 5 sample was almost 95 % recovered using heat-induced shape memory effect, while 98 % recovery was observed in an electric field of 40 V. Electroactive shape memory results were found to be better than those induced by heat stimulation effect.     

An antibacterial composite system based on multi-responsive microgels hosting monodisperse gold nanoparticles

A multi-responsive microgel having response to pH, temperature, and salt concentration was successfully prepared using a water-soluble monomer. Microgels were readily prepared from 2-(N-morpholino)ethyl methacrylate (MEMA) via emulsion polymerization using glycidyl methacrylate as a comonomer cross-linker. The morpholino groups of MEMA residues of microgels were able to give complexation with metal containing anions such as AuCl₄ ^? in acidic conditions. The reduction of aurate ions with sodium borohydride led to immobilized-gold nanoparticles (AuNP) in the microgel system. Average particle diameters of AuNPs were determined to be 10 ± 2 nm. The resulting AuNP-microgel system was examined as a nanoreactor for catalyst system and determined to be very effective in the reduction of 4-nitrophenol model reaction in aqueous media. AuNPs-microgel composite system had antibacterial properties against several Gram-positive and Gram-negative bacteria similar to amoxicillin. This P(MEMA-co-GMA) microgel is also very useful for different applications such as a host for metal nanoparticle production, a drug carrier or drug delivery system.     

Hyperuricemia is Associated with Increased Apo AI Fractional Catabolic Rates and Dysfunctional HDL in New Zealand Rabbits

The potential cause–effect relationship between uric acid plasma concentrations and HDL functionality remains elusive. Therefore, this study aimed to explore the effect of oxonic acid (OA)-induced hyperuricemia on the HDL size distribution, lipid content of HDL subclasses, and apo AI turnover, as well as HDL functionality in New Zealand white rabbits. Experimental animals received OA 750 mg/kg/day by oral gavage during 21 days. The HDL-apo AI fractional catabolic rate (FCR) was determined by exogenous labeling with ¹²⁵I, and HDL subclasses were determined by sequential ultracentrifugation and PAGE. Paraoxonase-1 activity (PON-1) and the effect of HDL on relaxation of aorta rings in vitro were determined as an indication of HDL functionality. Oxonic acid induced a sixfold increase of uricemia (0.84 ± 0.06 vs. 5.24 ± 0.12 mg/dL, P < 0.001), and significant decreases of triglycerides and phospholipids of HDL subclasses, whereas HDL size distribution and HDL-cholesterol remained unchanged. In addition, HDL-apo AI FCR was significantly higher in hyperuricemic rabbits than in the control group (0.03697 ± 0.0038 vs. 0.02605 ± 0.0017 h^?1 respectively, P < 0.05). Such structural and metabolic changes were associated with lower levels of PON-1 activities and deleterious effects of HDL particles on endothelium-mediated vasodilation. In conclusion, hyperuricemia is associated with structural and metabolic modifications of HDL that result in impaired functionality of these lipoproteins. Our data strongly suggest that uric acid per se exerts deleterious effects on HDL that contribute to increase the risk of atherosclerosis.     

Proximate Analysis of <Emphasis Type="Italic">Adenanthera pavonina</Emphasis> L. Seed Oil,a Source of Lignoceric Acid Grown in Pakistan

Adenanthera pavonina L. is indigenous to Pakistan a proximate analysis of the seeds was carried out and a physicochemical characterization of the seed oil and also a quality evaluation of the oil was made. The hexane-extracted oil content of the seed was 13.32 ± 0.55 %. Analysis showed the seed of A. pavonina contained appreciable amounts of protein (22.14 ± 0.78 %). Fiber and ash contents were 3.13 ± 0.64 and 4.53 ± 0.47 %, respectively. Triacylglycerol (97.51 ± 1.12 %) was predominantly present in the seed oil. Unsaponifiable matter (0.95 ± 0.10 %), peroxide value (11.43 ± 0.51 mequiv./kg) and saponification value (196.3 ± 0.87 mg of KOH/g of oil), iodine value (83.73 ± 1.18 g I/100 g oil) are in close agreement with the edible seed oils. α-Tocopherol was the predominant tocopherol 152.33 ± 13.19 mg/kg of oil while sterols are present at a significant level. Linoleic acid (42.97 ± 0.91 %) and oleic acid (17.89 ± 0.54 %) were found predominantly in unsaturated fatty acids while lignoceric acid (20.24 ± 1.12 %) was the predominant one among the saturated fatty acids. Lignoceric acid is rarely found in seed which is an essential nutrient for growth, development and maintenance of the brain. It is concluded that A. pavonina seeds appear to be a potential source of lignoceric acid and linoleic acid. This oil can be utilized in the manufacture of cosmetics, paints, varnishes, soaps, pharmaceutical products, biodiesel and blended formulations. The high protein content revealed that the seeds could be a good source of energy.     

Structural,Optical and Mössbauer Study of Ba<Subscript>1 − x</Subscript>Cu<Subscript>x</Subscript>Fe<Subscript>12</Subscript>O<Subscript>19</Subscript> (0.5 ≤ x) Nano Hexaferrites

In this study, a novel Ba_1?xCu_xFe₁₂O₁₉ (0.5?≤?x) nano-hexaferrites were prepared by a simple and cost-effective sol–gel auto-combustion method using barium nitrates, iron nitrate, copper (II) acetate monohydrate and citric acid, and its structural, optical properties and hyperfine interactions were reported. Structural properties were analyzed through XRD (X-ray diffraction), Scanning electron microscopy (SEM), and TEM (Transmission electron microscopy), while percent diffuse reflectance spectroscopy (DRS) and Mössbauer spectrometer were used for analyzing the optical and magnetic properties of the resultant products. The observed Mössbauer studies proved the ferromagnetic nature of nanoparticles (NPs) samples. The crystallite size (XRD) varies in a range of (23.30–35.12) nm. The direct optical energy band gap (E _g ) of all samples were calculated by Tauc plots where the E _g values are found in a small range of 1.97–2.15 eV. The experimental evidences signify the promising use of newly prepared nano-hexaferrites in the development of materials in various industrial devices and far better than the conventional available hexaferrites materials.     

Facile preparation and good performance of nano-Ag/metallocene polyethylene antibacterial coatings

Metallocene polyethylene/nano-silver coatings were prepared by a facile air-spray method on polymer films. Different from the prevailing strategy to endow polyethylene with antibacterial performance, we used metallocene polyethylene sol and nano-silver as a precursor to deposit coatings on polymers at a relatively low operating temperature. Antibacterial coatings with excellent mechanical properties, water resistance, and low silver release were achieved. The composite coatings were examined in terms of surface characteristics, mechanical properties, and antibacterial activity against two representative bacterial strains including Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The composite coatings exhibited favorable microstructure, good mechanical properties, and suitable crystallinity. The antimicrobial tests indicated that the fabricated composite coatings showed promising antibacterial activity against E. coli and S. aureus. Furthermore, Ag ions released by the composite coating after 30 days were under 1.2 ppb. These results indicated a promising prospect of the composite coating for wide antibacterial applications.     

Trisilanolphenyl-POSS nano-hybrid poly(biphenyl dianhydride-<Emphasis Type="Italic">p</Emphasis>-phenylenediamine) polyimide composite films: miscibility and structure-property relationship

A partially condensed polyhedral oligomeric silsesquioxane (POSS) compound, trisilanolphenyl-POSS (TSP-POSS) was prepared via a modified two-step procedure with phenyltrichlorosilane as the starting material. The solubility of the TSP-POSS in polyimide (PI) solvents, including N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc) was first evaluated. TSP-POSS could be dissolved in the test solvents with a solid concentration higher than 50 wt% and the obtained solution was stable both at room temperatures and in refrigerator at -18 °C for more than 1 month. TSP-POSS was then physically blended with a poly(amic acid) (PAA) obtained from 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride (BPDA) and para-phenylenediamine (PDA) with various adding proportions of 0, 5, 10, 15, 20, and 25 wt% (TSP-POSS in total solids). The obtained clear and homogeneous PAA/TSP-POSS solution was then thermally imidized at elevated temperatures to afford six PI/TSP-POSS composite films (PI-BP-0~PI-BP-25). For comparison, analogous composite films were prepared by blending TSP-POSS with another PI matrix, poly(pyromellitic anhydride-oxydianiline) (PI_PMDA-ODA) at the same hybrid proportion (PI-0~PI-25). TSP-POSS exhibited quite different miscibility with these two PI matrixes. All of the composite films based on PI_PMDA-ODA and TSP-POSS showed homogeneous nature and the films were optically transparent even at the high POSS loading of 25 wt%; however, the PI_BPDA-PDA analogues showed poor compatibility with the POSS additive when the adding proportion was over 10 wt%. PI-BP-20 and PI-BP-25 films were thoroughly opaque with the haze values of 100%. In addition, the residual weight ratio of the composite films at 760 °C in nitrogen increased from 62.0 wt% (PI-BP-0) to 74.1 wt% (PI-BP-25).