Biopolymer Composites With High Dielectric Performance: Interface Engineering

Abstract: Boron nitride nanotube (BNNT)/polyvinyl alcohol (PVA) composite fibers (<5 vol % BNNTs) were fabricated via electrospinning so that all BNNTs became aligned in the fiber casting direction. A several-fibers-thick ensemble of parallel-arranged contacting fibers made a single polymer sheet. Numerous sheets were then stacked in different ways with respect to the BNNT orientation (all fibers in adjacent sheets were either parallel or alternately rotated 90°) to make multilayer films that were finally hot-pressed. Various BNNT textures were reflected by the corresponding differences in the measured thermal conductivities of the resultant films due to anisotropy of thermal transport in the nanotubes. The highest values (0.54 W/mK) were obtained along the long axes of aligned BNNTs. Somewhat lower values (0.38 W/mK) were documented in films with alternately stacked fibers/tubes. The theoretical thermal conductivity values were estimated using the Nielsen’s model. These show good match with the experimental data. ...

Abstract: The traditional healthcare method follows 'one-size-fits-all' criteria, which shows some limitations in rendering proper results due to varied pharmacokinetic traits of different patients. Each patient shows a different result to a set of prescribed medicines with respect to other patient. In addition, this empirical criterion is also vulnerable to develop unfavourable side-effects due to overdose or under-dose. The advancements in the field of pharmacogenetic testing has paved the way for searching solutions to achieve the goal of 'personalized medicine'. This concept has the potential to provide more effective results as compared to the traditional technique. The technology of additive manufacturing or 3D printing can cater the need of the patient-centric principle. A wide range of 3D printing techniques provide the independence to work with a number of bio-materials. This paper carries out a systematic review methodology based on the application of this novel technology in the field of drug delivery. The materials, methods of drug administration, techniques used for printing have been elaborated along with the manufacturing of polypills with varied release profiles and geometries. Certain in vivo studies has also been reported to assess the feasibility of this technology. The concept of 4D printing in this direction has also been discussed. Finally, some excerpts on estimated future scope have also been illustrated.

Abstract: In the present work, a proton-conducting hybrid solid biopolymer electrolytes (HSBEs) system was successfully prepared via the solution casting approached. The HSBEs comprised of CMC blended with kappa carrageenan and doped with NH4NO3. The HSBEs system was characterized to evaluate the structural and the proton conduction properties using FTIR, XRD and EIS techniques. The FTIR analysis showed that a complexation occurred between the CMC-KC and H+ moiety of the NH4NO3 via the –OH, C–O–C as well as –COO- groups with associated changes observed to their wavenumbers and peak intensities. At the 80:20 ratio of the CMC:KC hybrid system, the optimum value of the ionic conductivity was found to be ~10−7 S/cm. However, the addition of 30 wt % of NH4NO3 to the system markedly increased the ionic conductivity to ~10−4 S/cm due to the increase in the amorphous phase in the HSBEs system as revealed by the XRD analysis. Meanwhile, the IR-deconvolution approach revealed an increase of the protonation (H+) from NH4NO3 towards the co-ordinating site on the hybrid CMC-KC system and this in turn, led to the increment in the ionic mobility and diffusion of ions for transportation. An EDLC was fabricated using the highest conducting HSBEs sample developed in the present study and it exhibited favourable characteristics as a capacitor with a reasonably good stability with regards to its electrochemical properties.

Abstract: While terrestrial organisms are the primary source of natural products, recent years have witnessed a considerable shift towards marine-sourced biocompounds. They have achieved a great scientific interest due to the plethora of compounds with structural and chemical properties generally not found in terrestrial products, exhibiting significant bioactivity ten times higher than terrestrial-sourced molecules. In addition to the antioxidant, anti-thrombotic, anti-coagulant, anti-inflammatory, anti-proliferative, anti-hypertensive, anti-diabetic, and cardio-protection properties, marine-sourced biocompounds have been investigated for their neuroprotective potential. Thus, this review aims to describe the recent findings regarding the neuroprotective effects of the significant marine-sourced biocompounds.

Abstract: The rapid development of modern capacitor devices has raised an urgent need of high performance dielectric materials with superior electrical and mechanical properties with low fabrication costs. B...

Abstract: We describe monocrystalline graphitic films, which are a few atoms thick but are nonetheless stable under ambient conditions, metallic, and of remarkably high quality. The films are found to be a two-dimensional semimetal with a tiny overlap between valence and conductance bands, and they exhibit a strong ambipolar electric field effect such that electrons and holes in concentrations up to 10 13 per square centimeter and with room-temperature mobilities of ∼10,000 square centimeters per volt-second can be induced by applying gate voltage.

Abstract: Graphene is a rapidly rising star on the horizon of materials science and condensed-matter physics. This strictly two-dimensional material exhibits exceptionally high crystal and electronic quality, and, despite its short history, has already revealed a cornucopia of new physics and potential applications, which are briefly discussed here. Whereas one can be certain of the realness of applications only when commercial products appear, graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena, some of which are unobservable in high-energy physics, can now be mimicked and tested in table-top experiments. More generally, graphene represents a conceptually new class of materials that are only one atom thick, and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications.

Abstract: The chemistry of graphene oxide is discussed in this critical review Particular emphasis is directed toward the synthesis of graphene oxide, as well as its structure Graphene oxide as a substrate for a variety of chemical transformations, including its reduction to graphene-like materials, is also discussed This review will be of value to synthetic chemists interested in this emerging field of materials science, as well as those investigating applications of graphene who would find a more thorough treatment of the chemistry of graphene oxide useful in understanding the scope and limitations of current approaches which utilize this material (91 references)

Abstract: Chitin is the second most important natural polymer in the world. The main sources exploited are two marine crustaceans, shrimp and crabs. Our objective is to appraise the state of the art concerning this polysaccharide: its morphology in the native solid state, methods of identification and characterization and chemical modifications, as well as the difficulties in utilizing and processing it for selected applications. We note the important work of P. Austin, S. Tokura and S. Hirano, who have contributed to the applications development of chitin, especially in fiber form. Then, we discuss chitosan, the most important derivative of chitin, outlining the best techniques to characterize it and the main problems encountered in its utilization. Chitosan, which is soluble in acidic aqueous media, is used in many applications (food, cosmetics, biomedical and pharmaceutical applications). We briefly describe the chemical modifications of chitosan—an area in which a variety of syntheses have been proposed tentatively, but are not yet developed on an industrial scale. This review emphasizes recent papers on the high value-added applications of these materials in medicine and cosmetics.

Abstract: We developed a chemical route to produce graphene nanoribbons (GNR) with width below 10 nanometers, as well as single ribbons with varying widths along their lengths or containing lattice-defined graphene junctions for potential molecular electronics. The GNRs were solution-phase-derived, stably suspended in solvents with noncovalent polymer functionalization, and exhibited ultrasmooth edges with possibly well-defined zigzag or armchair-edge structures. Electrical transport experiments showed that, unlike single-walled carbon nanotubes, all of the sub-10-nanometer GNRs produced were semiconductors and afforded graphene field effect transistors with on-off ratios of about 10(7) at room temperature.