Poly(carbonate-imide) polymer

A novel series of polymers and copolymers based on a polyimide backbone with the incorporation of carbonate moieties along the backbone. The process for preparing these polymers and copolymers is also disclosed as is a novel series of dinitrodiphenyl carbonates and diaminodiphenyl carbonates. The novel polymers and copolymers exhibit high temperature capability and because of the carbonate unit, many exhibit a high degree of order and/or crystallinity

Citrullination of CXCL8 by peptidylarginine deiminase alters receptor usage, prevents proteolysis, and dampens tissue inflammation

Biological functions of proteins are influenced by posttranslational modifications such as on/off switching by phosphorylation and modulation by glycosylation. Proteolytic processing regulates cytokine and chemokine activities. In this study, we report that natural posttranslational citrullination or deimination alters the biological activities of the neutrophil chemoattractant and angiogenic cytokine CXCL8/interleukin-8 (IL-8). Citrullination of arginine in position 5 was discovered on 14% of natural leukocyte-derived CXCL8(1–77), generating CXCL8(1–77)Cit5. Peptidylarginine deiminase (PAD) is known to citrullinate structural proteins, and it may initiate autoimmune diseases. PAD efficiently and site-specifically citrullinated CXCL5, CXCL8, CCL17, CCL26, but not IL-1β. In comparison with CXCL8(1–77), CXCL8(1–77)Cit5 had reduced affinity for glycosaminoglycans and induced less CXCR2-dependent calcium signaling and extracellular signal-regulated kinase 1/2 phosphorylation. In contrast to CXCL8(1–77), CXCL8(1–77)Cit5 was resistant to thrombin- or plasmin-dependent potentiation into CXCL8(6–77). Upon intraperitoneal injection, CXCL8(6–77) was a more potent inducer of neutrophil extravasation compared with CXCL8(1–77). Despite its retained chemotactic activity in vitro, CXCL8(1–77)Cit5 was unable to attract neutrophils to the peritoneum. Finally, in the rabbit cornea angiogenesis assay, the equally potent CXCL8(1–77) and CXCL8(1–77)Cit5 were less efficient angiogenic molecules than CXCL8(6–77). This study shows that PAD citrullinates the chemokine CXCL8, and thus may dampen neutrophil extravasation during acute or chronic inflammation

A drug evaluation of 1% tenofovir gel and tenofovir disoproxil fumarate tablets for the prevention of HIV infection.

Introduction: More than a million people acquire HIV infection annually. Pre-exposure prophylaxis (PrEP) using antiretrovirals is currently being investigated for HIV prevention. Oral and topical formulations of tenofovir have undergone preclinical and clinical testing to assess acceptability, safety and effectiveness in preventing HIV infection. Areas covered: The tenofovir drug development pathway from compound discovery, preclinical animal model testing and human testing were reviewed for safety, tolerability and efficacy. Tenofovir is well tolerated and safe when used both systemically or applied topically for HIV prevention. High drug concentrations at the site of HIV transmission and concomitant low systemic drug concentrations are achieved with vaginal application. Coitally applied gel may be the favored prevention option for women compared with the tablets, which may be more suitable for prevention in men and sero-discordant couples. However, recent contradictory effectiveness outcomes in women need to be better understood. Expert opinion: Emerging evidence has brought new hope that antiretrovirals can potentially change the course of the HIV epidemic when used as early treatment for prevention, as topical or oral PrEP. Although some trial results appear conflicting, behavioral factors, adherence to dosing and pharmacokinetic properties of the different tenofovir formulations and dosing approaches offer plausible explanations for most of the variations in effectiveness observed in different trials

Presbyopia:Effectiveness of correction strategies

Presbyopia is a global problem affecting over a billion people worldwide. The prevalence of unmanaged presbyopia is as high as 50% of those over 50 years of age in developing world populations due to a lack of awareness and accessibility to affordable treatment, and is even as high as 34% in developed countries. Definitions of presbyopia are inconsistent and varied, so we propose a redefinition that states “presbyopia occurs when the physiologically normal age-related reduction in the eye's focusing range reaches a point, when optimally corrected for distance vision, that the clarity of vision at near is insufficient to satisfy an individual's requirements”. Presbyopia is inevitable if one lives long enough, but intrinsic and extrinsic risk factors including cigarette smoking, pregnancy history, hyperopic or astigmatic refractive error, ultraviolet radiation, female sex (although accommodation is similar to males), hotter climates and some medical conditions such as diabetes can accelerate the onset of presbyopic symptoms. Whilst clinicians can ameliorate the symptoms of presbyopia with near vision spectacle correction, bifocal and progressive spectacle lenses, monovision, translating or multifocal contact lenses, monovision, extended depth of focus, multifocal (refractive, diffractive and asymmetric designs) or ‘accommodating’ intraocular lenses, corneal inlays, scleral expansion, laser refractive surgery (corneal monovision, corneal shrinkage, corneal multifocal profiles and lenticular softening), pharmacologic agents, and electro-stimulation of the ciliary muscle, none fully overcome presbyopia in all patients. While the restoration of natural accommodation or an equivalent remains elusive, guidance is gives on presbyopic correction evaluation techniques

Mechanism and kinetics of the catalytic synthesis of ammonia

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Forced convection heat transfer from pin fin arrays

Extended surfaces in the form of fins are widely used to enhance heat dissipation from a surface. A review of the literature revealed that there exists considerable experience in experimental and numerical analyses for rectangular fins, but there is a scarcity of information on pin fins. This dissertation presents the findings of a comprehensive literature search on the state-of-the-art of pin fins, detailed experimental investigation of forced convection heat transfer from pin fin arrays involving complex flow fields that are caused by orientation of the fin arrays at various angles of inclination and fin tip clearances, and a simplified numerical analysis. An experimental investigation was conducted to study the forced convection/radiation heat transfer characteristics of three staggered and in-line pin fin arrays that had different fin diameter to interfin spacing ratios. The experiments were performed for two tip clearances, four to seven heat inputs to the array baseplate, two or three flow rates, two fin orientations and five different angles of inclinations with respect to the incoming flow field. Limited number of natural convection experiments were performed on one of the arrays. The combined mode rate of heat transfer was measured and the contribution of the radiation heat transfer was determined analytically. The flow field was studied through flow visualization, velocity and pressure measurements. The heat transfer results were used to establish an empirical correlation to evaluate and predict the performance of pin fin arrays subjected to complex boundary conditions. A simplified numerical analysis was performed for an in-line fin array with simple boundary conditions. The results showed that in general the overall rate of heat transfer (a) increased with an increase in Reynolds number; (b) increased as the angle of inclination was reduced from 90\sp\circ to about 30\sp\circ to 45\sp\circ; (c) increased in the absence of clearance at the tip of the fins; and (d) decreased as the fin diameter to the interfin spacing ratio was increased from 0.333 to 0.667. It was observed that the forced convection rate of heat transfer was about 3 to 5 times higher than in natural convection