[en] In this study we describe the first example of 3D bioprinted triphasic chiral nanocomposite (NC) hydrogels/scaffolds to simulate the complex 3D architecture, nano/micro scale topography, and chiral nature of extracellular matrix. These multifunctional constructs are prepared using a 3D bioprinting technique and are composed of three connected hydrogels/scaffolds, two of which are loaded with nanomaterials functionalized with opposite enantiomers of a biomolecule. With these constructs, we direct the migration of cells toward the part of the triphasic chiral NC hydrogels/scaffolds containing the cells’ preferred biomolecule enantiomer. (paper)

[en] In this study, green synthesis of silver nanoparticles (AgNPs) and silver-montmorillonite (MMT) nanocomposites (Ag/MMT) were carried out using two local plants from Iran (Ocimum basilicum L and Teucrium Polium L). The biomolecules presenting in the plant extracts acted as the reducing and capping agents. The average size of the synthesized AgNPs, using OB and TP plant extracts were around 80 nm and 20 nm, respectively. In addition, the nanoparticle sizes were further decreased using MMT as substrate, to 70 nm and 15 nm for OB and TP plant extracts, respectively. Finally, high antibacterial efficiency against E. coli and S. aureus pathogens as well as the appropriate cytotoxicity against HEP G2 cells were observed from the biosynthesized AgNPs. The present work is eco-friendly benign and can be used for large-scale fabrication of AgNPs. (paper)

[en] Poly(lactic acid) (PLA) nanocomposite films reinforced with acetylated bacterial cellulose nanoribbons were prepared by solvent casting. Acetylation of bacterial cellulose (BC) was performed by an innovative and sustainable direct solvent-free route catalyzed by citric acid. The effect of derivatization and its extent on the morphological, optical, thermal and mechanical properties of the nanocomposites was analyzed. Data collected from the above studies showed that acetylation of BC nanoribbons clearly improved the nanofibers dispersion in the PLA matrix with respect to unmodified BC, which in turn resulted in increased transparency and mechanical properties of the nanocomposites produced.

[en] Nickel nanoparticles and its composites have been synthesized in a water–DMSO (1:1) mixture by reduction of Ni(NO₃)₂×6H₂O with sodium tetrahydridoborate. It has been found that, to obtain Ni nanoparticles in 5.0 mM Ni(NO₃)₂×6H₂O solution, it is best to use 5-fold excess of NaBH₄. Nickel nanocomposites have been formed on the basis of polyvinylpyrrolidone (PVP), hydroxyapatite and aluminium powder. The relationship between Ni(NO₃)₂×6H₂O concentration and (PVP)Ni composite morphology has been established, which allows to form nickel particles of various shapes with a PVP polymeric carrier. These nickel NPs and its composites have proved to be efficient catalysts in the reaction of reductive (Na[BH(OAc)₃]) amination of 4-carbomethoxybenzaldehyde with N-(2-methyl)-4-(pyridin-3-yl) pyrimidin-2,5-diamine to give methyl 4- {(4-methyl-3-(4-(5-methylpyridin-3-yl) pyrimidin-2-ylamino) phenylamino) methyl) benzoate. (authors)

[en] Electro-conductive nanocomposites have several applications in biomedical field. Development of a biocompatible electro-conductive polymeric materials is therefore of prime importance. In this study, electro-conductive nanofibrous mats of PLGA/CNT were fabricated through different methods including blend electrospinning, simultaneous PLGA electrospinning and CNT electrospraying and ultrasound-induced adsorption of CNTs on the electrospun PLGA nanofibers. The morphology and diameter of fibers were characterized by SEM and TEM, showing the lowest average diameters of 477 ± 136 nm for PLGA/MWCNT blend nanocomposites. MWCNT-sprayed PLGA specimens showed significant lower water contact angle (83°), electrical resistance (3.0 × 10⁴ Ω) and higher mechanical properties (UTS: 5.50 ± 0.46 MPa) compared to the untreated PLGA scaffolds. Also, results of PC12 cell study demonstrated highest viability percentage on the MWCNT-sprayed PLGA nanofibers. We propose that the conductive nanocomposites have capability to use as tool for the neural regeneration and biosensors.

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[en] The objective of the this study was to analyze the under-surface hardness of light-cured nanofilled composite resins of different shades. The specimens were resin composites of each light (B1), medium (A3), and dark (C3) shades packed in a cylinder mold and subsequently polymerized. The hardness was tested using a Knoop system. The hardness test results for the bright (B1), medium (A3), and dark (C3) shades were 82.4+1.1, 75.9+1.2 and 65.9+1.9, respectively, and indicated significant differences between the under-surface hardness of each shade. It was concluded that resin composites of darker to brigher shades demonstrated lower to higher under-surface hardness. (paper)

[en] Nanocomposites have unprecedented potential for conductivity-based damage identification when used as matrices in structural composites. Recent research has investigated nanofiller alignment in structural composites, but because damage identification often requires in-plane measurements, percolation and conductivity transverse to the alignment direction become crucial considerations. We herein contribute indispensable guidance to the development of nanocomposites with aligned nanofiller networks and insights into percolation trends transverse to the alignment direction by studying the influence of alignment on transverse critical volume fraction, conductivity, and rate of transition from non-percolating to percolating in three-dimensional carbon nanotube composite systems. (paper)

[en] Due to the European Union (EU) waste frame work directive (WFD), legislations have been endorsed in EU member states such as UK for the Recycling of wastes with a vision to prevent and reduce landfilling of waste. Spent oil based drilling mud (drilling fluid) is a waste from the Oil and Gas industry with great potentials for recycling after appropriate clean-up and treatment processes. This research is the novel application of nanoclays extracted from spent oil based drilling mud (drilling fluid) clean-up as nanofiller in the manufacture of nanocomposite materials. Research and initial experiments have been undertaken which investigate the suitability of Polyamide 6 (PA6) as potential polymer of interest. SEM and EDAX were used to ascertain morphological and elemental characteristics of the nanofiller. ICPOES has been used to ascertain the metal concentration of the untreated nanofiller to be treated (by oil and heavy metal extraction) before the production of nanocomposite materials. The challenges faced and future works are also discussed

[en] This paper presents studies on the development and characterization of nanocomposites based on natural rubber, plasticised starch, precipitated silica and layered clay such as organically modified montmorillonite (OMMT). Mixtures were made containing 0, 3 and 6 phr (parts per 100 parts rubber) OMMT, respectively. They were obtained by melt intercalation in a Brabender mixer at 12/80 rotations/min and 100-150ºC, for 10 minutes. Curing agents (sulfur and curing accelerators) were embedded on a laboratory roller at 90ºC, friction 1:1.1, processing time 5 minutes. Rubber specimens were obtained by compression, using a hydraulic press at 165ºC and a pressing force of 300 kN. Curing time, determined using the Monsanto rheometer, decreases with the increased amount of OMMT in the mixtures. At the same time, it was noticed that mixtures containing OMMT show improvement in physical-mechanical properties and resistance in various working environments specific to the food and pharmaceutical industry. Permanent compressive deformation 25%, 24hx70°C shows very good values for mixtures containing OMMT. The new types of nanocomposites may be used to obtain O-rings for the sugar industry or for other areas of application.

[en] So far high thermoelectric performance of filled skutterudite can only be obtained at relatively high temperature, which severely limits its application. Here, Yb-filled skutterudite (Yb_0.35Co₄Sb₁₂) composites incorporated with silver nanoparticles are fabricated via electroless plating for achieving enhanced thermoelectric performance. The content and homogeneity of Ag nanoparticle can be well controlled to optimize the thermoelectric properties of bulk composite. As a result, the Yb_0.35Co₄Sb₁₂ composite with optimum Ag content shows remarkably improved Seebeck coefficient and power factor, which leads to high ZT values above 0.8 from 450 to 800 K and a peak value of 1.0 at 603 K.