297 research outputs found
Technology of production of Syrian lustre (11th to 13th century)
Lustre is a decoration consisting of a surface layer of silver and copper metal nanoparticles, a few hundreds of nanometres thick and incorporated into the glaze. It shows a colourful metallic and iridescent appearance which makes use of the quantum confined optical response of the metallic nanoparticles. Three apparently unrelated lustre decorations, yellow-orange golden (Tell Minis), a dark brown-reddish with iridescences (Raqqa) and yellow-brown golden (Damascus) were produced in the same area in successive periods over tin and lead-free glazes which is known to require specific strategies to obtain a metallic shiny lustre. The composition and nanostructure of the lustre layers are analysed and the materials and specific firing conditions followed in their production determined. The optical properties of the lustre layers have been analysed in terms of the nanostructure obtained and correlated to the specific processing conditions.Peer ReviewedPostprint (author's final draft
Production of lentiviral vectors using novel, enzymatically-produced, linear DNA vectors
The manufacture of large quantities of high-quality DNA is a major bottleneck in the production of viral vectors for gene therapy. Touchlight Genetics has developed a proprietary abiological technology that addresses the major issues in commercial DNA supply. The technology uses ‘rolling-circle’ amplification to produce large quantities of concatameric DNA that is then processed to create closed linear double-stranded DNA by enzymatic digestion. This novel form of DNA, Doggybone™ DNA (dbDNA™), is structurally distinct from plasmid DNA. Here we compare lentiviral vectors production from dbDNA™ and plasmid DNA. Lentiviral vectors were administered to neonatal mice via intracerebroventricular injection. Luciferase expression was quantified in conscious mice continually by whole-body bioluminescent imaging. We observed long-term luciferase expression using dbDNA™-derived vectors, which was comparable to plasmid-derived lentivirus vectors. Here we have demonstrated that functional lentiviral vectors can be produced using the novel dbDNA™ configuration for delivery in vitro and in vivo. Importantly, this could enable lentiviral vector packaging of complex DNA sequences that have previously been incompatible with bacterial propagation systems, as dbDNA™ technology could circumvent such restrictions through its phi29-based rolling-circle amplification
Dominant suppression of inflammation via targeted mutation of the mRNA destabilizing protein tristetraprolin
In myeloid cells, the mRNA-destabilizing protein tristetraprolin (TTP) is induced and extensively phosphorylated in response to LPS. To investigate the role of two specific phosphorylations, at serines 52 and 178, we created a mouse strain in which those residues were replaced by nonphosphorylatable alanine residues. The mutant form of TTP was constitutively degraded by the proteasome and therefore expressed at low levels, yet it functioned as a potent mRNA destabilizing factor and inhibitor of the expression of many inflammatory mediators. Mice expressing only the mutant form of TTP were healthy and fertile, and their systemic inflammatory responses to LPS were strongly attenuated. Adaptive immune responses and protection against infection by Salmonella typhimurium were spared. A single allele encoding the mutant form of TTP was sufficient for enhanced mRNA degradation and underexpression of inflammatory mediators. Therefore, the equilibrium between unphosphorylated and phosphorylated TTP is a critical determinant of the inflammatory response, and manipulation of this equilibrium may be a means of treating inflammatory pathologies
Therapeutic DNA vaccine induces broad T cell responses in the gut and sustained protection from viral rebound and AIDS in SIV-infected rhesus macaques.
Immunotherapies that induce durable immune control of chronic HIV infection may eliminate the need for life-long dependence on drugs. We investigated a DNA vaccine formulated with a novel genetic adjuvant that stimulates immune responses in the blood and gut for the ability to improve therapy in rhesus macaques chronically infected with SIV. Using the SIV-macaque model for AIDS, we show that epidermal co-delivery of plasmids expressing SIV Gag, RT, Nef and Env, and the mucosal adjuvant, heat-labile E. coli enterotoxin (LT), during antiretroviral therapy (ART) induced a substantial 2-4-log fold reduction in mean virus burden in both the gut and blood when compared to unvaccinated controls and provided durable protection from viral rebound and disease progression after the drug was discontinued. This effect was associated with significant increases in IFN-γ T cell responses in both the blood and gut and SIV-specific CD8+ T cells with dual TNF-α and cytolytic effector functions in the blood. Importantly, a broader specificity in the T cell response seen in the gut, but not the blood, significantly correlated with a reduction in virus production in mucosal tissues and a lower virus burden in plasma. We conclude that immunizing with vaccines that induce immune responses in mucosal gut tissue could reduce residual viral reservoirs during drug therapy and improve long-term treatment of HIV infection in humans
Cooperation between Referees and Authors Increases Peer Review Accuracy
Peer review is fundamentally a cooperative process between scientists in a community who agree to review each other's work in an unbiased fashion. Peer review is the foundation for decisions concerning publication in journals, awarding of grants, and academic promotion. Here we perform a laboratory study of open and closed peer review based on an online game. We show that when reviewer behavior was made public under open review, reviewers were rewarded for refereeing and formed significantly more cooperative interactions (13% increase in cooperation, P = 0.018). We also show that referees and authors who participated in cooperative interactions had an 11% higher reviewing accuracy rate (P = 0.016). Our results suggest that increasing cooperation in the peer review process can lead to a decreased risk of reviewing errors
Nano-Architecture of nitrogen-doped graphene films synthesized from a solid CN source
New synthesis routes to tailor graphene properties by controlling the concentration and chemical configuration of dopants show great promise. Herein we report the direct reproducible synthesis of 2-3% nitrogen-doped ‘few-layer’ graphene from a solid state nitrogen carbide a-C:N source synthesized by femtosecond pulsed laser ablation. Analytical investigations, including synchrotron facilities, made it possible to identify the configuration and chemistry of the nitrogen-doped graphene films. Auger mapping successfully quantified the 2D distribution of the number of graphene layers over the surface, and hence offers a new original way to probe the architecture of graphene sheets. The films mainly consist in a Bernal ABA stacking three-layer architecture, with a layer number distribution ranging from 2 to 6. Nitrogen doping affects the charge carrier distribution but has no significant effects on the number of lattice defects or disorders, compared to undoped graphene synthetized in similar conditions. Pyridinic, quaternary and pyrrolic nitrogen are the dominant chemical configurations, pyridinic N being preponderant at the scale of the film architecture. This work opens highly promising perspectives for the development of self-organized nitrogen-doped graphene materials, as synthetized from solid carbon nitride, with various functionalities, and for the characterization of 2D materials using a significant new methodology
Elevation in Body Temperature to Fever Range Enhances and Prolongs Subsequent Responsiveness of Macrophages to Endotoxin Challenge
Macrophages are often considered the sentries in innate immunity, sounding early immunological alarms, a function which speeds the response to infection. Compared to the large volume of studies on regulation of macrophage function by pathogens or cytokines, relatively little attention has been devoted to the role of physical parameters such as temperature. Given that temperature is elevated during fever, a long-recognized cardinal feature of inflammation, it is possible that macrophage function is responsive to thermal signals. To explore this idea, we used LPS to model an aseptic endotoxin-induced inflammatory response in BALB/c mice and found that raising mouse body temperature by mild external heat treatment significantly enhances subsequent LPS-induced release of TNF-α into the peritoneal fluid. It also reprograms macrophages, resulting in sustained subsequent responsiveness to LPS, i.e., this treatment reduces “endotoxin tolerance” in vitro and in vivo. At the molecular level, elevating body temperature of mice results in a increase in LPS-induced downstream signaling including enhanced phosphorylation of IKK and IκB, NF-κB nuclear translocation and binding to the TNF-α promoter in macrophages upon secondary stimulation. Mild heat treatment also induces expression of HSP70 and use of HSP70 inhibitors (KNK437 or Pifithrin-µ) largely abrogates the ability of the thermal treatment to enhance TNF-α, suggesting that the induction of HSP70 is important for mediation of thermal effects on macrophage function. Collectively, these results support the idea that there has been integration between the evolution of body temperature regulation and macrophage function that could help to explain the known survival benefits of fever in organisms following infection
Non-destructive characterisation and classification of ceramic artefacts using pEDXRF and statistical pattern recognition
Background: Portable energy dispersive X-ray fluorescence (pEDXRF) spectrometry analysis was applied for the characterisation of archaeological ceramic findings from three Neolithic sites in Serbia. Two dimension reduction techniques, principal component analysis (PCA) and scattering matrices-based dimension reduction were used to examine the possible classification of those findings, and to extract the most discriminant features. Results: A decision-making procedure is proposed, whose goal is to classify unknown ceramic findings based on their elemental compositions derived by pEDXRF spectrometry. As a major part of decision-making procedure, the possibilities of two dimension reduction methods were tested. Scattering matrices-based dimension reduction was found to be the more efficient method for the purpose. Linear classifiers designed based on the desired output allowed for 7 of 8 unknown samples from the test set to be correctly classified. Conclusions: Based on the results, the conclusion is that despite the constraints typical of the applied analytical technique, the elemental composition can be considered as viable information in provenience studies. With a fully-developed procedure, ceramic artefacts can be classified based on their elemental composition and well-known provenance
Immunoregulation by covalent antigen-antibody complexes. II. Suppression of a T-cell independent anti-hapten response.
Covalent antigen-antibody complexes containing the hapten fluorescein were found to suppress the thymus-independent response to that hapten. This suppression required the presence of an intact Fc fragment in the complex but could still be established in the complete absence of T cells
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