895 resultados para Corrosion and anti-corrosives


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Wear and corrosion of metal-on-metal hip replacements results in wear debris and metal-ion release in vivo, which may subsequently cause pain and hypersensitivity for patients. Retrieved metal-on-metal hip replacements have revealed that two-body sliding wear and three-body abrasive wear are the predominant wear mechanisms. However, there is a lack of understanding of the combined effects of wear/corrosion, especially the effect of abrasion-corrosion.

This study investigates the sliding-corrosion and abrasion-corrosion performance of a cast CoCrMo alloy in simulated hip joint environments using a microabrasion rig integrated with an electrochemical cell. Tests have been conducted in 0.9% NaCl, phosphate buffered saline solution, 25% and 50% bovine serum solutions with 0 or 1 g cm(-3) SiC at 37 degrees C. Experimental results reveal that under abrasion-corrosion test conditions, the presence of proteins increased the total specific wear rate. Conversely, electrochemical noise measurements indicated that the average anodic current levels were appreciably lower for the proteinaceous solutions when compared with the inorganic solutions. A severely deformed nanocrystalline layer was identified immediately below the worn surface for both proteinaceous and inorganic solutions. The layer is formed by a recrystallisation process and/or a strain-induced phase transformation that occurs during microabrasion-corrosion. (C) 2008 Elsevier Ltd. All rights reserved.

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Design and operation of Fe0 permeable reactive barriers (PRBs) can be improved by understanding the long-term mineralogical transformations that occur within PRBs. Changes in mineral precipitates, cementation, and corrosion of Fe0 filings within an in situ pilot-scale PRB were examined after the first 30 months of operation and compared with results of a previous study of the PRB conducted 15 months earlier using X-ray diffraction and scanning electron microscopy employing energy dispersive X-ray and backscatter electron analyses. Iron (oxy)hydroxides, aragonite, and maghemite and/or magnetite occurred throughout the cores collected 30 mo after installation. Goethite, lepidocrocite, mackinawite, aragonite, calcite, and siderite were associated with oxidized and cemented areas, while green rusts were detected in more reduced zones. Basic differences from our last detailed investigation include (i) mackinawite crystallized from amorphous FeS, (ii) aragonite transformed into calcite, (iii) akaganeite transformed to goethite and lepidocrocite, (iv) iron (oxy)hydroxides and calcium and iron carbonate minerals increased, (v) cementation was greater in the more recent study, and (vi) oxidation, corrosion, and disintegration of Fe0 filings were greater, especially in cemented areas, in the more recent study. If the degree of corrosion and cementation that was observed from 15 to 30 mo after installation continues, certain portions of the PRB (i.e., up-gradient entrance of the ground water to the Fe0 section of the PRB) may last less than five more years, thus reducing the effectiveness of the PRB to mitigate contaminants.

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This article examines Presbyterian interpretations in Scotland and Ireland of the Scottish Reformations of 1560 and 1638–43. It begins with a discussion of the work of two important Presbyterian historians of the early nineteenth century, the Scotsman, Thomas McCrie, and the Irishman, James Seaton Reid. In their various publications, both laid the template for the nineteenth-century Presbyterian understanding of the Scottish Reformations by emphasizing the historical links between the Scottish and Irish churches in the early-modern period and their common theology and commitment to civil and religious liberty against the ecclesiastical and political tyranny of the Stuarts. The article also examines the commemorations of the National Covenant in 1838, the Solemn League and Covenant in 1843, and the Scottish Reformation in 1860. By doing so, it uncovers important religious and ideological linkages across the North Channel, including Presbyterian evangelicalism, missionary activity, church–state relationships, religious reform and revival, and anti-Catholicism

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Proliferative Diabetic Retinopathy (PDR) and Eales' Disease (ED) have different aetiologies although they share certain common clinical symptoms including pre-retinal neovascularization. Since there is a need to understand if the shared end-stage angiogenic pathology of PDR and ED is driven by common stimulating factors, we have studied the cytokines contained in vitreous from both patient groups and analyzed the angiogenic potential of these samples in vitro.

Material and Methods

Vitreous samples from patients with PDR (n = 13) and ED (n = 5) were quantified for various cytokines using a cytokine biochip array and sandwich ELISA. An additional group of patients (n = 5) with macular hole (MH) was also studied for comparison. To determine the angiogenic potential of these vitreous samples, they were analyzed for their ability to induce tubulogenesis in human microvascular endothelial cells. Further, the effect of anti-VEGF (Ranibizumab) and anti-IL-6 antibodies were studied on vitreous-mediated vascular tube formation.

Results

Elevated levels of IL-6, IL-8, MCP-1 and VEGF were observed in vitreous of both PDR and ED when compared to MH. PDR and ED vitreous induced greater levels of endothelial cell tube formation compared to controls without vitreous (P<0.05). When VEGF in vitreous was neutralized by clinically-relevant concentrations of Ranibizumab, tube length was reduced significantly in 5 of 6 PDR and 3 of 5 ED samples. Moreover, when treated with IL-6 neutralizing antibody, apparent reduction (71.4%) was observed in PDR vitreous samples.

Conclusions

We have demonstrated that vitreous specimens from PDR and ED patients share common elevations of pro-inflammatory and pro-angiogenic cytokines. This suggests that common cytokine profiles link these two conditions.

Figures 12

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As global resistance to conventional antibiotics rises we need to develop new strategies to develop future novel therapeutics. In our quest to design novel anti-infectives and antimicrobials it is of interest to investigate host-pathogen interactions and learn from the complexity of host defense strategies that have evolved over millennia. A myriad of host defense molecules are now known to play a role in protection against human infection. However, the interaction between host and pathogen is recognized to be a multifaceted one, involving countless host proteins, including several families of peptides. The regulation of infection and inflammation by multiple peptide families may represent an evolutionary failsafe in terms of functional degeneracy and emphasizes the significance of host defense in survival. One such family is the neuropeptides (NPs), which are conventionally defined as peptide neurotransmitters but have recently been shown to be pleiotropic molecules that are integral components of the nervous and immune systems. In this review we address the antimicrobial and anti-infective effects of NPs both in vitro and in vivo and discuss their potential therapeutic usefulness in overcoming infectious diseases. With improved understanding of the efficacy of NPs, these molecules could become an important part of our arsenal of weapons in the treatment of infection and inflammation. It is envisaged that targeted therapy approaches that selectively exploit the anti-infective, antimicrobial and immunomodulatory properties of NPs could become useful adjuncts to our current therapeutic modalities. © 2012 Bentham Science Publishers.

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How did the counter-cultural aims of Radical Psychiatry coincide with those of documentary filmmaking in the 1960s? Where the forms and structures of new approaches to the documentary necessarily complicit in promoting the clinical and anti-clinical practices, and wider political agenda, of Radical Psychiatry? How did the documentary deal with the ethical, aesthetic, and audience-related issues associated with filming personalities and environments associated with Radical Psychiatry? How did Radical Psychiatry and the documentary shape postwar discourses on trauma, especially within conflict and post-conflict (PTSD) contexts? What is the legacy of Radical Pschiatry today, and how has it been explored by contemporary documentray film?

This article addresses these question by examining a range of documentaries dealing with the radical and 'anti-psychiatric' ideas and methods of figures such as R.D.Laing, David Cooper, Jan Bastiaans, Timothy Leary, and Franco Basaglia. Films analysed include Peter Robinson's Asylum (1972) and Psychiatry and Violence (1973); Ah, Sunflower (Klinkert and Sinclair, 1967); Anatomy of Violence (Davis, 1967); Turn On, Tune In, Drop Out (Robin Clarke, 1967), W. R. - Mysteries of the Organism (Makavejev, 1971); Raymond Depardon's San Clemente (1980) and Urgences (1988); and Louis van Gasteren's trilogy Now Do You Get it Why I am Crying (1969), The Price of Survival (2003), and There is No Plane to Zagreb (2012). 
The article concludes with a discussion of Nicolas Philibert's Every Little Thing (1997) within the context of the French documentary tradition and the film's more immediate subject - the famous clinic at La Borde established by Jean Oury, and associated with the methods and theories of figures such as Jacques
 Lacan, Francesc Tosquelles, Franz Fanon, and Félix Guattari.

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Background: Cigarette smoke induces a pro-inflammatory response in airway epithelial cells but it is not clear which of the various chemicals contained within cigarette smoke (CS) should be regarded as predominantly responsible for these effects. We hypothesised that acrolein, nicotine and acetylaldehyde, important chemicals contained within volatile cigarette smoke in terms of inducing inflammation and causing addiction, have immunomodulatory effects in primary nasal epithelial cell cultures (PNECs).

Methods: PNECs from 19 healthy subjects were grown in submerged cultures and were incubated with acrolein, nicotine or acetylaldehyde prior to stimulation with Pseudomonas aeruginosa lipopolysaccharide (PA LPS). Experiments were repeated using cigarette smoke extract (CSE) for comparison. IL-8 was measured by ELISA, activation of NF-κB by ELISA and Western blotting, and caspase-3 activity by Western blotting. Apoptosis was evaluated using Annexin-V staining and the terminal transferase-mediated dUTP nick end-labeling (TUNEL) method.

Results: CSE was pro-inflammatory after a 24 h exposure and 42% of cells were apoptotic or necrotic after this exposure time. Acrolein was pro-inflammatory for the PNEC cultures (30 μM exposure for 4 h inducing a 2.0 fold increase in IL-8 release) and also increased IL-8 release after stimulation with PA LPS. In contrast, nicotine had anti-inflammatory properties (0.6 fold IL-8 release after 50 μM exposure to nicotine for 24 h), and acetylaldehyde was without effect. Acrolein and nicotine had cellular stimulatory and anti-inflammatory effects respectively, as determined by NF-κB activation. Both chemicals increased levels of cleaved caspase 3 and induced cell death.

Conclusions: Acrolein is pro-inflammatory and nicotine anti-inflammatory in PNEC cultures. CSE induces cell death predominantly by apoptotic mechanisms. 

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Throughout Africa, charismatic Christianity has been caricatured as an inhibitor of democratization. Its adherents are said either to withdraw from the rough and tumble of politics ('pietism') or to preach a prosperity gospel that encourages believers to pour their resources into their churches in the hope that God will 'bless' them. Both courses of action are said to encourage such people to be politically quietist, with no interest in democratization or other forms of political activity. This is said to thwart democratization. This article utilizes an ethnographic case study of a 'progressive' charismatic congregation in Harare, Zimbabwe, in 2007, to provide evidence that 'pietism' and 'prosperity' are not the only options for charismatic Christianity. Drawing on the concept of 'spiritual capital', it argues that some varieties of charismatic Christianity have the resources to contribute to democratization. For example, this congregation's self-styled 'de-institutionalization' process is opening up new avenues for people to learn democratic skills and develop a worldview that is relationship-centred, participatory, and anti-authoritarian. The article concludes that spiritual capital can be a useful tool for analysing the role of religions in democratizations. It notes, however, that analysts should take care to identify and understand what variety of spiritual capital is generated in particular situations, focusing on the worldviews it produces and the consequences of those worldviews for democratization. © 2009 Taylor & Francis.

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Nontypeable Haemophilus influenzae (NTHI) is an opportunistic pathogen that is an important cause of acute exacerbations of chronic obstructive pulmonary disease (AECOPD). COPD is an inflammatory disease of the airways, and exacerbations are acute inflammatory events superimposed on this background of chronic inflammation. Azithromycin (AZM) is a macrolide antibiotic with antibacterial and anti-inflammatory properties and a clinically proven potential for AECOPD prevention and management. Relationships between AZM efficacy and resistance by NTHI and between bactericidal and immunomodulatory effects on NTHI respiratory infection have not been addressed. In this study, we employed two pathogenic NTHI strains with different AZM susceptibilities (NTHI 375 [AZM susceptible] and NTHI 353 [AZM resistant]) to evaluate the prophylactic and therapeutic effects of AZM on the NTHI-host interplay. At the cellular level, AZM was bactericidal toward intracellular NTHI inside alveolar and bronchial epithelia and alveolar macrophages, and it enhanced NTHI phagocytosis by the latter cell type. These effects correlated with the strain MIC of AZM and the antibiotic dose. Additionally, the effect of AZM on NTHI infection was assessed in a mouse model of pulmonary infection. AZM showed both preventive and therapeutic efficacies by lowering NTHI 375 bacterial counts in lungs and bronchoalveolar lavage fluid (BALF) and by reducing histopathological inflammatory lesions in the upper and lower airways of mice. Conversely, AZM did not reduce bacterial loads in animals infected with NTHI 353, in which case a milder anti-inflammatory effect was also observed. Together, the results of this work link the bactericidal and anti-inflammatory effects of AZM and frame the efficacy of this antibiotic against NTHI respiratory infection.

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Discrimination of different species in various target scopes within a single sensing platform can provide many advantages such as simplicity, rapidness, and cost effectiveness. Here we design a three-input colorimetric logic gate based on the aggregation and anti-aggregation of gold nanoparticles (Au NPs) for the sensing of melamine, cysteine, and Hg2+. The concept takes advantages of the highly specific coordination and ligand replacement reactions between melamine, cysteine, Hg2+, and Au NPs. Different outputs are obtained with the combinational inputs in the logic gates, which can serve as a reference to discriminate different analytes within a single sensing platform. Furthermore, besides the intrinsic sensitivity and selectivity of Au NPs to melamine-like compounds, the “INH” gates of melamine/cysteine and melamine/Hg2+ in this logic system can be employed for sensitive and selective detections of cysteine and Hg2+, respectively.

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The development of metal deposition processes based on electroless nickel, alloy and composite coatings on various surfaces has witnessed a surge in interest among researchers, with many recent applications made possible from many excellent properties. In recent years, these coatings have shown promising corrosion and wear resistance properties and large number of newer developments became most important from macro to nano level applications. After a brief review of the fundamental aspects underlying the coating processes, this paper discusses in detail about different electroless nickel alloy, composite, nano plating, bath techniques, preparation, characterization, new depositing mechanism and their recent applications, including brief notes on difficult substrate and waste treatment for green environment. Emphasis will be onto their recent progress, which will be discussed in detail and critically reviewed.

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The precise regulatory mechanisms of amplification and downregulation of the pro- and anti-inflammatory cytokines in the inflammatory response have not been fully delineated. Although activated protein C (APC) and its precursor protein C (PC) have recently been reported to be promising therapeutic agents in the management of meningococcal sepsis, direct evidence for the anti-inflammatory effect remains scarce. We report that APC inhibits in vitro the release of tumor necrosis factor (TNF) and macrophage migration inhibitory factor (MIF), two known cytokine mediators of bacterial septic shock, from lipopolysaccharide (LPS)-stimulated human monocytes. The THP-1 monocytic cell line, when stimulated with LPS and concomitant APC, exhibited a marked reduction in the release of TNF and MIF protein in a concentration-dependent manner compared to cells stimulated with LPS alone. This effect was observed only when incubations were performed in serum-free media, but not in the presence of 1-10% serum. Serum-mediated inhibition could only be overcome by increasing APC concentrations to far beyond physiological levels, suggesting the presence of endogenous serum-derived APC inhibitors. Inhibition of MIF release by APC was found to be independent of TNF, as stimulation of MIF release by LPS was unaltered in the presence of anti-TNF antibodies. Our data confirm that the suggested anti-inflammatory properties of APC are due to direct inhibition of the release of the pro-inflammatory monokine TNF, and imply that the anti-inflammatory action of APC is also mediated via inhibition of MIF release.

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Epidemiological studies suggest a relationship between blood lipids and immune-mediated diseases, but the nature of these associations is not well understood. We used genome-wide association studies (GWAS) to investigate shared single nucleotide polymorphisms (SNPs) between blood lipids and immune-mediated diseases. We analyzed data from GWAS (n~200,000 individuals), applying new False Discovery Rate (FDR) methods, to investigate genetic overlap between blood lipid levels [triglycerides (TG), low density lipoproteins (LDL), high density lipoproteins (HDL)] and a selection of archetypal immune-mediated diseases (Crohn's disease, ulcerative colitis, rheumatoid arthritis, type 1 diabetes, celiac disease, psoriasis and sarcoidosis). We found significant polygenic pleiotropy between the blood lipids and all the investigated immune-mediated diseases. We discovered several shared risk loci between the immune-mediated diseases and TG (n = 88), LDL (n = 87) and HDL (n = 52). Three-way analyses differentiated the pattern of pleiotropy among the immune-mediated diseases. The new pleiotropic loci increased the number of functional gene network nodes representing blood lipid loci by 40%. Pathway analyses implicated several novel shared mechanisms for immune pathogenesis and lipid biology, including glycosphingolipid synthesis (e.g. FUT2) and intestinal host-microbe interactions (e.g. ATG16L1). We demonstrate a shared genetic basis for blood lipids and immune-mediated diseases independent of environmental factors. Our findings provide novel mechanistic insights into dyslipidemia and immune-mediated diseases and may have implications for therapeutic trials involving lipid-lowering and anti-inflammatory agents.

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BACKGROUND: Diabetic retinopathy is an important cause of visual loss. Laser photocoagulation preserves vision in diabetic retinopathy but is currently used at the stage of proliferative diabetic retinopathy (PDR).

OBJECTIVES: The primary aim was to assess the clinical effectiveness and cost-effectiveness of pan-retinal photocoagulation (PRP) given at the non-proliferative stage of diabetic retinopathy (NPDR) compared with waiting until the high-risk PDR (HR-PDR) stage was reached. There have been recent advances in laser photocoagulation techniques, and in the use of laser treatments combined with anti-vascular endothelial growth factor (VEGF) drugs or injected steroids. Our secondary questions were: (1) If PRP were to be used in NPDR, which form of laser treatment should be used? and (2) Is adjuvant therapy with intravitreal drugs clinically effective and cost-effective in PRP?

ELIGIBILITY CRITERIA: Randomised controlled trials (RCTs) for efficacy but other designs also used.


REVIEW METHODS: Systematic review and economic modelling.

RESULTS: The Early Treatment Diabetic Retinopathy Study (ETDRS), published in 1991, was the only trial designed to determine the best time to initiate PRP. It randomised one eye of 3711 patients with mild-to-severe NPDR or early PDR to early photocoagulation, and the other to deferral of PRP until HR-PDR developed. The risk of severe visual loss after 5 years for eyes assigned to PRP for NPDR or early PDR compared with deferral of PRP was reduced by 23% (relative risk 0.77, 99% confidence interval 0.56 to 1.06). However, the ETDRS did not provide results separately for NPDR and early PDR. In economic modelling, the base case found that early PRP could be more effective and less costly than deferred PRP. Sensitivity analyses gave similar results, with early PRP continuing to dominate or having low incremental cost-effectiveness ratio. However, there are substantial uncertainties. For our secondary aims we found 12 trials of lasers in DR, with 982 patients in total, ranging from 40 to 150. Most were in PDR but five included some patients with severe NPDR. Three compared multi-spot pattern lasers against argon laser. RCTs comparing laser applied in a lighter manner (less-intensive burns) with conventional methods (more intense burns) reported little difference in efficacy but fewer adverse effects. One RCT suggested that selective laser treatment targeting only ischaemic areas was effective. Observational studies showed that the most important adverse effect of PRP was macular oedema (MO), which can cause visual impairment, usually temporary. Ten trials of laser and anti-VEGF or steroid drug combinations were consistent in reporting a reduction in risk of PRP-induced MO.

LIMITATION: The current evidence is insufficient to recommend PRP for severe NPDR.

CONCLUSIONS: There is, as yet, no convincing evidence that modern laser systems are more effective than the argon laser used in ETDRS, but they appear to have fewer adverse effects. We recommend a trial of PRP for severe NPDR and early PDR compared with deferring PRP till the HR-PDR stage. The trial would use modern laser technologies, and investigate the value adjuvant prophylactic anti-VEGF or steroid drugs.

STUDY REGISTRATION: This study is registered as PROSPERO CRD42013005408.

FUNDING: The National Institute for Health Research Health Technology Assessment programme.

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The studies on chloride induced corrosion of steel bars in alkali activated slag (AAS) concretes are scarcely reported in the past. In order to make this issue clearer and compare the corrosion performance of AAS with Portland cement (PC) counterpart, an investigation was carried out and the results are reported in this paper. Corrosion properties were assessed with the help of rate of corrosion, electrical resistivity and pore solution chemistry. It was found that: (i) steel corrosion resistance of the AAS concretes was comparable or in some cases even worse than that of Portland cement (PC) concrete under intermittent chloride ponding regime; (ii) the corrosion behaviour of the AAS concretes was significantly influenced by ionic exchange, carbonation and sulphide concentration; (iii) the increase of alkali concentration of the activator generally reduced chloride resulting corrosion, and a value of 1.5 was found to be an optimum modulus for the activator for improving the corrosion resistance.