Recent advances in natural polymer-based hydroxyapatite scaffolds:Properties and applications

New materials that mimic natural bone properties, matching functional, mechanical, and biological properties have been continuously developed to rehabilitate bone defects. Desirably, 'tissue engineering' has been a multidisciplinary ground that uses the principles of life sciences and engineering for the biological replacements that restore or replace the tissue function or a whole organ. Nevertheless, the bone grafting treatment has numerous restrictions, counting the major hazards of morbidity from the sites where donor bone grafts are removed, the likelihood for an immune rejection or bacterial transport from the donor site (in case of allogeneic grafting), and the inadequate availability of donor bone grafts that can meet the current demands. Since the proper growth of synthetic materials for implantable bones encourages the reconstruction of bone tissues by providing strong structural support without any damages to the interferences of biological tissue. To serve for such behavior, the biodegradable matrices provide temporary scaffolds within which the bone tissues can be regenerated. Typically, the thermoplastic aliphatic polyesters are found to serve this purpose. The great significance of this field lies in the in vitro growth of precise cells on porous matrices (scaffolds) to generate three-dimensional (3D) tissues that can be entrenched into the location of tissue/bone damage. Numerous gifts have been gifted by our nature to advance and preserve the well-being of all living things either directly or indirectly. This review focuses on the recent advances in polymer-based hydroxyapatite scaffolds including their properties and applications

Functionalized graphene-based nanocomposites for smart optoelectronic applications

The recent increase in the use of graphene and its derivatives is due to their exceptional physicochemical, electrical, mechanical, and thermal properties as the industrial materials developed by involving graphene structures can fulfill future needs. In that view, the potential use of these graphene-containing nanomaterials in electronics applications has encouraged in-depth exploration of the electronic, conducting, and other functional properties. The protecting undifferentiated form of graphene has similarly been proposed for various applications, for example, as supercapacitors, photovoltaic and transparent conductors, touch screen points, optical limiters, optical frequency converters, and terahertz devices. The hybrid composite nanomaterials that undergo stimulus-induced optical and electrical changes are important for many new technologies based on switchable devices. As a two-dimensional smart electronic material, graphene has received widespread attention, and with that view, we aim to cover the various types of graphene oxide (GO)-based composites, linking their optical and electrical properties with their structural and morphological ones. We believe that the topics covered in this review can shed light on the development of high-yield GO-containing electronic materials, which can be fabricated as the field moves forward and makes more significant advances in smart optoelectronic devices

Enhanced gas sensing and photocatalytic activity of reduced graphene oxide loaded TiO2 nanoparticles

In the present study, we have evaluated the gas sensing and photocatalytic activity of reduced graphene oxide (rGO) conjugated titanium dioxide (TiO2) nanoparticles (NPs) formed by the hydrothermal method. The as-synthesized rGO-TiO2 nanocomposite were characterized for the physicochemical properties such as the nature of crystallinity, functionalization, and morphology by making use of the powder X-ray diffraction, Fourier transform-infrared spectroscopy, and scanning electron microscopy, respectively. On testing the gas sensing properties, we found that the rGO-TiO2 nanocomposite can serve as the chemoresistive-type sensor because of its sensitivity and selectivity towards different concentrations of hydrogen and oxygen at room temperature conditions. However, the rGO-TiO2 sensor’s response and recovery speed towards hydrogen and oxygen needs further optimization. Test of photocatalytic activity of TiO2-rGO catalyst for the removal of two model contaminant dyes, RhB and MB showed effective removal, with respective degradation percentages of about 80 and 90% within the first 50 min of irradiation under visible light irradiation. Besides, MB was more effectively degraded using TiO2-rGO than pure TiO2 during the first 30 min of irradiation and this enhanced activity can be attributed to the increased capacity of light absorption, the efficiency of charge carriers separation, and the specific surface area maintained by the rGO-TiO2 nanocomposite to effectively utilize the photo-generated holes (h+) and superoxide radicals (O2−radical dot), responsible for the degradation of the dye. Based on the overall analysis, the formation of rGO-TiO2 nanocomposite can significantly improve the gas sensing and photocatalytic properties of TiO2 NPs and thus can be potential for practical applications in future nanotechnology

Present eternity : quests of temporality in the literary production of the "extrême contemporain" in France (The Writings of Dominique Fourcade and Emmanuel Hocquard)

The term \uab extr\ueame contemporain \ubb is an expression currently used by scholars to indicate the French literary production of the last 20 years. This term was used in a work of literature for the first time by the French poet Dominique Fourcade in 1986 (\uc9l\ue9gie L apostrophe E.C.) in reference to an epoch, but also to a new sense of experiencing time and space in the so-called \uab age of digital reproducibility \ubb. The aim of this paper is to consider how the change in temporal protocols due to the triumph of Big Optics (Paul Virilio) affects the sense of teleology (destiny) and the quest for experience in French contemporary poetry (in particular, in the genre of the elegy). Including both memory and anticipation, the \uab extr\ueame contemporain \ubb production seems to prefer the \u201ctime of now\u201d, Jetz-zeit in Benjamin\u2019s words, to past or testimony, and speaks to the present, whose responsibility is to give voice to a space where everything is simply allowed to happen

Genomic investigations of unexplained acute hepatitis in children

Since its first identification in Scotland, over 1,000 cases of unexplained paediatric hepatitis in children have been reported worldwide, including 278 cases in the UK1. Here we report an investigation of 38 cases, 66 age-matched immunocompetent controls and 21 immunocompromised comparator participants, using a combination of genomic, transcriptomic, proteomic and immunohistochemical methods. We detected high levels of adeno-associated virus 2 (AAV2) DNA in the liver, blood, plasma or stool from 27 of 28 cases. We found low levels of adenovirus (HAdV) and human herpesvirus 6B (HHV-6B) in 23 of 31 and 16 of 23, respectively, of the cases tested. By contrast, AAV2 was infrequently detected and at low titre in the blood or the liver from control children with HAdV, even when profoundly immunosuppressed. AAV2, HAdV and HHV-6 phylogeny excluded the emergence of novel strains in cases. Histological analyses of explanted livers showed enrichment for T cells and B lineage cells. Proteomic comparison of liver tissue from cases and healthy controls identified increased expression of HLA class 2, immunoglobulin variable regions and complement proteins. HAdV and AAV2 proteins were not detected in the livers. Instead, we identified AAV2 DNA complexes reflecting both HAdV-mediated and HHV-6B-mediated replication. We hypothesize that high levels of abnormal AAV2 replication products aided by HAdV and, in severe cases, HHV-6B may have triggered immune-mediated hepatic disease in genetically and immunologically predisposed children

Hydrothermal Synthesis and Photocatalytic Activity of NiO Nanoparticles under Visible Light Illumination

In this present study, Nickel oxide (NiO) nanoparticles (NPs) have been synthesized using the hydrothermal method and characterized using powder X-ray Diffraction (XRD), UV-vis and Fourier Transform Infra Red (FTIR) spectroscopies, Scanning Electron Microscopy (SEM), and Energy-Dispersive X-ray (EDX) methods. The result of the characterization indicates that the synthesized sample has a pure cubic phase of NiO with roughly spherical shape morphologies and respective estimated crystallinity and microstrain values of about 78% and 5.1. Test of the photocatalytic activity of the synthesized sample towards the model contaminant dye methylene blue (MB) shows a degradation efficiency of 46% in a period of 2 h under nature sunlight irradiation at natural pH and that the reaction could satisfactorily describe both pseudo-first-order and pseudo-second-order kinetic models. So, this synthesis method may potentially be used for the effective elimination of toxic organic pollutants from water and wastewater over prolonged exposure under natural sunlight without adding any oxidant or adjusting the pH of the reaction medium. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

One-pot Hydrothermal Synthesis and Characterization of Zirconium Oxide Nanoparticles

Zirconia (also known as zirconium dioxide, ZrO2) is a white crystalline naturally occurring mineral that offers excellent optical, dielectric, and mechanical properties. Considering these properties and referring to previous studies on the optimization of ZrO2 NPs synthesis, in the present study, we studied the crystalline, optical, and fluorescence properties of ZrO2 nanoparticles (NPs) formed by the hydrothermal synthesis route. The physicochemical features of the nanoparticles were examined in the photocatalytic oxidation of rhodamine B. From the powder XRD analysis, the ZrO2 NPs were found to be highly crystalline, while the fluorescence (FL) spectra indicated an emission band at 473 nm, which could be linked to a blue shift. Also, the FTIR and Raman spectroscopies confirmed the functionality and bonding, and in addition, the XPS analysis provided the elemental peaks of Zr 3d and O 1s, where all these analyses evidenced the successful formation of ZrO2. Examination of the photocatalytic activity of ZrO2 NPs revealed the capability of the material for rhodamine B photocatalytic degradation effectively, with a degradation efficiency of 86% after 2 h of treatment. Moreover, the nanoparticles exhibited stability and reusability over five cycles. Overall, from the analysis, ZrO2 NPs can be easily formed via the hydrothermal route with tailored optical and fluorescence properties to find applications in the electronics industry for the manufacturing of light emitting devices

Fabrication of reduced graphene oxide/CeO2 nanocomposite for enhanced electrochemical performance

A facile hydrothermal technique was utilized for the preparation of the CeO2/rGO nanocomposite. X-ray diffraction pattern was used to identify the crystal structure and calculate the crystallite size of the prepared samples. The average crystallite sizes for CeO2 and rGO/CeO2 nanocomposites were calculated to be 14 and 12 nm, respectively. The spectral analysis confirmed the functional groups of CeO2 nanoparticles and CeO2/rGO nanocomposites. The presence of G and D band peaks as well as the CeO2 and CeO2/rGO peaks was confirmed by the FT-Raman analysis. The optical characterization of the synthesized sample was also examined with the help of UV–visible absorption and photoluminescence spectra. The surface morphology of the prepared sample was analyzed by the scanning electron microscope and transmission electron microscopy. The energy-dispersive X-ray spectroscopy analysis confirmed the existence of cerium, oxygen and carbon as the elementary components in the nanocomposite. The electrical properties such as the dielectric constant, the dielectric loss and the AC conductivity were also analyzed. The observed specific capacitances for the CeO2/rGO composite and that of pure CeO2 NPs were calculated as 89 Fg−1 and 77 Fg−1, respectively. Thus, CeO2/rGO nanocomposites can exhibit excellent capacitive performance and thereby serve as a promising anode material for supercapacitor applications. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature

Fabrication and characterization of porous scaffolds for bone replacements using gum tragacanth

The practice of bone implants is the standard procedure for the treatment of skeletal fissures, or to substitute and re-establish lost bone. A perfect scaffold ought to be made of biomaterials that duplicate the structure and properties of natural bone. However, the production of living tissue constructs that are architecturally, functionally and mechanically comparable to natural bone is the major challenge in the treatment and regeneration of bone tissue in orthopaedics and in dentistry. In this work, we have employed a polymeric replication method to fabricate hydroxyapatite (HAP) scaffolds using gum tragacanth (GT) as a natural binder. GT is a natural gum collected from the dried sap of several species of Middle Eastern legumes of the genus Astragalus, possessing antibacterial and wound healing properties. The synthesized porous HAP scaffolds were analyzed structurally and characterized for their phase purity and mechanical properties. The biocompatibility of the porous HAP scaffold was confirmed by seeding the scaffold with Vero cells, and its bioactivity assessed by immersing the scaffold in simulated body fluid (SBF). Our characterization data showed that the biocompatible porous HAP scaffolds were composed of highly interconnecting pores with compressive strength ranging from 0.036 MPa to 2.954 MPa, comparable to that of spongy bone. These can be prepared in a controlled manner by using an appropriate binder concentration and sintering temperature. These HAP scaffolds have properties consistent with normal bone and should be further developed for potential application in bone implants