177 research outputs found
Functionalization of Titanium surface with Chitosan via silanation: 3D CLSM imaging of cell biocompatibility behaviour
Introduction Biocompatibility ranks as one of the most important properties of dental materials. One of the criteria for biocompatibility is the absence of material toxicity to cells, according to the ISO 7405 and 10993 recommendations. Among numerous available methods for toxicity assessment; 3-dimensional Confocal Laser Scanning Microscopy (3D CLSM) imaging was chosen because it provides an accurate and sensitive index of living cell behavior in contact with chitosan coated tested implants. Objectives: The purpose of this study was to investigate the in vitro biocompatibility of functionalized titanium with chitosan via a silanation using sensitive and innovative 3D CLSM imaging as an investigation method for cytotoxicity assessment. Methods The biocompatibility of four samples (controls cells, TA6V, TA6V-TESBA and TA6V-TESBAChitosan) was compared in vitro after 24h of exposure. Confocal imaging was performed on cultured human gingival fibroblast (HGF1) like cells using Live/Dead® staining. Image series were obtained with a FV10i confocal biological inverted system and analyzed with FV10-ASW 3.1 Software (Olympus France). Results Image analysis showed no cytotoxicity in the presence of the three tested substrates after 24 h of contact. A slight decrease of cell viability was found in contact with TA6V-TESBA with and without chitosan compared to negative control cells. Conclusion Our findings highlighted the use of 3D CLSM confocal imaging as a sensitive method to evaluate qualitatively and quantitatively the biocompatibility behavior of functionalized titanium with chitosan via a silanation. The biocompatibility of the new functionalized coating to HGF1 cells is as good as the reference in biomedical device implantation TA6V
Atomically Sharp Interface in an h-BN-epitaxial graphene van der Waals Heterostructure
International audienceStacking various two-dimensional atomic crystals is a feasible approach to creating unique multilayered van der Waals heterostructures with tailored properties. Herein for the first time, we present a controlled preparation of large-area h-BN/graphene heterostructures via a simple chemical deposition of h-BN layers on epitaxial graphene/SiC(0001). Van der Waals forces, which are responsible for the cohesion of the multilayer system, give rise to an abrupt interface without interdiffusion between graphene and h-BN, as shown by X-ray Photoemission Spectroscopy (XPS) and direct observation using scanning and High-Resolution Transmission Electron Microscopy (STEM/HRTEM). The electronic properties of graphene, such as the Dirac cone, remain intact and no significant charge transfer i.e. doping, is observed. These results are supported by Density Functional Theory (DFT) calculations. We demonstrate that the h-BN capped graphene allows the fabrication of vdW heterostructures without altering the electronic properties of graphene
Using primary sources to produce a microhistory of translation and translators: theoretical and methodological concerns
In descriptive studies, where the source and target texts are the main primary sources (‘primary text products’), ‘extra-textual’ sources are looked at with ‘circumspection’. However, in historical research methodologies they are central. This article examines the use and value of archives, manuscripts and, especially, translator papers, post-hoc accounts and interviews in producing a history of translation and translators. Rather than informing a ‘traditional’ Rankean history of facts and major personalities, the article underlines the potential value of such material in creating a ‘microhistory’, reclaiming the details of the everyday lives and working processes of sometimes little-known or forgotten translators and contextualising them to construct a social and cultural history of translation and translators. Sometimes these sources are housed in collections where translation may not be very visible, which creates problems of location. Examples are given from the autobiography of A. Birse and research on the working papers of Sam Hileman, Andrew Hurley, Bernard Miall and Margaret Sayers Peden
Direct observation and control of near-field radiative energy transfer in a natural hyperbolic material
Heat control is a key issue in nano-electronics, where new efficient energy
transfer mechanisms are highly sought after. In this respect, there is indirect
evidence that high-mobility hexagonal boron nitride (hBN)-encapsulated graphene
exhibits hyperbolic out-of-plane radiative energy transfer when driven
out-of-equilibrium. Here we directly observe radiative energy transfer due to
the hyperbolic phonon polaritons modes of the hBN encapsulant in intrinsic
graphene devices under large bias, using mid-infrared spectroscopy and
pyrometry. By using different hBN crystals of varied crystalline quality, we
engineer the energy transfer efficiency, a key asset for compact thermal
management of electronic circuits.Comment: 21 pages including Supplementary Material (Main text: 10 pages, 4
figures
Rare predicted loss-of-function variants of type I IFN immunity genes are associated with life-threatening COVID-19
Background: We previously reported that impaired type I IFN activity, due to inborn errors of TLR3- and TLR7-dependent type I interferon (IFN) immunity or to autoantibodies against type I IFN, account for 15–20% of cases of life-threatening COVID-19 in unvaccinated patients. Therefore, the determinants of life-threatening COVID-19 remain to be identified in ~ 80% of cases. Methods: We report here a genome-wide rare variant burden association analysis in 3269 unvaccinated patients with life-threatening COVID-19, and 1373 unvaccinated SARS-CoV-2-infected individuals without pneumonia. Among the 928 patients tested for autoantibodies against type I IFN, a quarter (234) were positive and were excluded. Results: No gene reached genome-wide significance. Under a recessive model, the most significant gene with at-risk variants was TLR7, with an OR of 27.68 (95%CI 1.5–528.7, P = 1.1 × 10−4) for biochemically loss-of-function (bLOF) variants. We replicated the enrichment in rare predicted LOF (pLOF) variants at 13 influenza susceptibility loci involved in TLR3-dependent type I IFN immunity (OR = 3.70[95%CI 1.3–8.2], P = 2.1 × 10−4). This enrichment was further strengthened by (1) adding the recently reported TYK2 and TLR7 COVID-19 loci, particularly under a recessive model (OR = 19.65[95%CI 2.1–2635.4], P = 3.4 × 10−3), and (2) considering as pLOF branchpoint variants with potentially strong impacts on splicing among the 15 loci (OR = 4.40[9%CI 2.3–8.4], P = 7.7 × 10−8). Finally, the patients with pLOF/bLOF variants at these 15 loci were significantly younger (mean age [SD] = 43.3 [20.3] years) than the other patients (56.0 [17.3] years; P = 1.68 × 10−5). Conclusions: Rare variants of TLR3- and TLR7-dependent type I IFN immunity genes can underlie life-threatening COVID-19, particularly with recessive inheritance, in patients under 60 years old
Primary rat sertoli and interstitial cells exhibit a differential response to cadmium
Two cell types central to the support of spermatogenesis, the Sertoli cell and the interstitial (Leydig) cell, were isolated from the same cohort of young male rats and challenged with cadmium chloride to compare their susceptibility to the metal. Both cell types were cultured under similar conditions, and similar biochemical endpoints were chosen to minimize experimental variability. These endpoints include the uptake of 109 Cd, reduction of the vital tetrazolium dye MTT, incorporation of 3 H-leucine, change in heat-stable cadmium binding capacity, and production of lactate. Using these parameters, it was observed that the Sertoli cell cultures were adversely affected in a dose-and time-dependent manner, while the interstitial cell cultures, treated with identical concentrations of CdCl 2 , were less affected. The 72-hr LC 50 's for Sertoli cells and interstitial cells were 4.1 and 19.6 μM CdCl 2 , respectively. Thus, different cell populations within the same tissue may differ markedly in susceptibility to a toxicant. These in vitro data suggest that the Sertoli cell, in relation to the interstitium, is particularly sensitive to cadmium. Because the Sertoli cell provides functional support for the seminiferous epithelium, the differential sensitivity of this cell type may, in part, explain cadmium-induced testicular dysfunction, particularly at doses that leave the vascular epithelium intact.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42554/1/10565_2004_Article_BF00135027.pd
Electrochemical properties of titanium electrodes under alpha irradiation
Bombardment of the back face of thin titanium foil electrodes with alpha particles causes important modifications of their electrochemical properties in aqueous solution at room temperature. We have observed two electrochemical regimes depending on the energy spectrum of the a particles attaining the Ti/solution interface : regime I corresponding to the [0, 1.6 MeV] range for which α-radiation reactivates the Ti surface in 1 M H2SO4, regime II corresponding to the [0, 3 MeV] range for which α-radiation passivates the Ti surface in otherwise identical experimental conditions. By changing the nature, concentration and pH of the solution, by using a scavenger of primary radicals (H, OH), it is suggested that water radiolysis plays a role in the electrochemical behaviour reported in regime I. The importance of the native oxide at the Ti electrode surface á-irradiated prior to immersion in solution is also emphasized. A mechanism in two steps involving reduction of the surface cations by H radicals followed by further oxidation during anodic polarisation of the electrode was inferred, solely applicable in regime I
- …