644 resultados para corrosion prevention


Relevância:

20.00% 20.00%

Publicador:

Resumo:

The advent of highly active antiretroviral therapy (HAART) improved HIV infection prognosis. However, adverse metabolic and morphologic effects emerged, highlighting a lack of investigation into the role of nutritional interventions among this population. The present study evaluated the impact of a nutritional counseling program on prevention of morphologic and metabolic changes in patients living with HIV/AIDS receiving HAART. A 12-month randomized clinical trial was conducted with 53 adults of both genders in use of HAART. Subjects were allocated to either an intervention group (IG) or a control group (CG). Nutritional counseling was based on the promotion of a healthy diet pattern. Anthropometrical, biochemical, blood pressure, and food intake variables were assessed on four separate occasions. Sub scapular skin-fold results showed a significant tendency for increase between time 1 (Mean IG = 14.9 mm; CG = 13.6 mm), time 3 (Mean IG = 16.7 mm; CG = 18.2 mm), and time 4 (Mean IG = 16.4 mm; CG = 17.7 mm). Lipid percentage intake presented a greater increase among controls (time 1 mean = 26.3%, time 4 mean = 29.6%) than among IG subjects (time 1 mean = 29.1%, time 4 mean = 28.9%). Moreover, participants allocated to the IG presented an increase in dietetic fiber intake of almost 10 grams. The proposed nutritional counseling program proved to be effective in improving diet by reducing fat consumption and increasing fiber intake.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The biocompatibility of commercially pure (cp) titanium stems from its chemical stability within an organism, due to a fine film of impermeable titanium oxide covering the metal surface, which guarantees its resistance to corrosion. Despite its biocompatible characteristic, this material does not promote the formation of a hydroxyapatite layer, therefore, many research groups have sought to alter the material`s surface, introducing modifications that might influence corrosion resistance. The electrochemical behavior of cp Ti, with hydroxyapatite coating and without hydroxyapatite coating, commonly used in implant materials, was investigated using an artificial saliva solution at 25 degrees C and pH=7.4. In the conditions of the study it was observed that the hydroxyapatite layer influences the properties of corrosion resistance. This study of the behavior of cp Ti with and without hydroxyapatite coating, in naturally aerated artificial saliva solution at 25 degrees C, was based on open circuit potential measurements and potentiodynamic polarization curves. At approximately 1x10(-6) A/cm(2) the potential for cp Ti with and without hydroxyapatite coating begins to increase at a faster rate, but at -74mV (SCE) for coated cp Ti and at 180mV (SCE) for uncoated cp Ti the increase in potential begins to slow. This behavior, characterized by a partial stabilization of current density, indicates that in those potential ranges a protective passive film is formed.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Spleen or spleen plus bone marrow cells from (BALB/c x C57Bl/6)F1 donors were transferred into BALB/c recipients 21 days before skin or cardiac transplantation. Prolonged graft survival was observed on recipients treated with the mixture of donor-derived cells as compared to those treated with spleen cells alone. We evaluated the expression of CD45RB and CD44 by splenic CD4(+) and CD8(+) T cells 7 and 21 days after donor cell transfer. The populations of CD8(+)CD45RB(low) and CD8(+)CD44(high) cells were significantly decreased in mice pre-treated with donor spleen and bone marrow cells as compared to animals treated with spleen cells only, although these cells expanded in both groups when compared to an earlier time-point. No differences were observed regarding CD4+ T cell population when recipients of donor-derived cells were compared. An enhanced production of IL-10 was observed seven days after transplantation in the supernatants of spleen cell cultures of mice treated with spleen and bone marrow cells. Taken together these data suggest that donor-derived bone marrow cells modulate the sensitization of the recipient by semi-allogeneic spleen cells in part by delaying the generation of activated/memory CD8(+) T cells leading to enhanced graft survival. (c) 2007 Elsevier B.V. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The corrosion resistance of Ti and Ti-6Al-4V was investigated through electrochemical impedance spectroscopy, EIS, potentiodynamic polarisation curves and UV-Vis spectrophotometry. The tests were done in Hank solution at 25 degrees C and 37 degrees C. The EIS measurements were done at the open circuit potential at specific immersion times. An increase of the resistance as a function of the immersion time was observed, for Ti (at 25 degrees C and 37 degrees C), and for Ti-6Al-4V (at 25 degrees C), which was interpreted as the formation and growth of a passive film on the metallic surfaces. (C) 2009 Elsevier Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper presents a study of AISI 1040 steel corrosion in aqueous electrolyte of acetic acid buffer containing 3.1 and 31 x 10(-3) mol dm(-3) of Na(2)S in both the presence and absence of 3.5 wt.% NaCl. This investigation of steel corrosion was carried out using potential polarization, and open-circuit and in situ optical microscopy. The morphological analysis and classification of types of surface corrosion damage by digital image processing reveals grain boundary corrosion and shows a non-uniform sulfide film growth, which occurs preferentially over pearlitic grains through successive formation and dissolution of the film. (C) 2011 Elsevier Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Fuel distribution uses 304 stainless steel containers for the storage of biofuels, however there are few reports in the literature about the corrosive aspects this. steel in biodiesel. The objective of this research is to study the corrosive behavior of 304 austenitic stainless steel in the presence of biodiesel, unwashed and washed, with aqueous solutions of citric, oxalic, acetic and ascorbic acids 0,01 mol L(-1), and compare with results obtained for the copper (ASTM D130). The employedtechniques were: atomic absorption spectrometry (AAS) and optical microscopy (OM). The results of EA A showed a low rate of corrosion for the stainless steel, the alloys elements studied were Cr, Ni and Fe, the highest rate was observed for the chrome, 1.78 ppm / day in biodiesel with or without washing. The OM of the 304 steel, when compared with that of copper has a low corrosion rate in the 304 steel/biodiesel system. Not with standing, this demonstrates that not only the 304 steel, but also the copper corrodes in biodiesel

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Syftet med denna litteraturstudie var att beskriva riskfaktorer som påverkade uppkomsten av trycksår samt de vanligaste förekommande preventiva åtgärderna. Vidare var syftet att beskriva sjuksköterskans roll vid förebyggandet samt behandlingen av trycksår. De vetenskapliga artiklar (n=21) som ingick i studien söktes manuellt samt datoriserat via databaserna Blackwell Synergy, CHINAL, Elin@Dalarna och Elsiever. Inklusionskriterierna var att de skulle vara vetenskapliga samt av kvalitativ och kvantitativ design. Även litteraturstudier inkluderades. Artiklarna skulle vara publicerade 1990 eller senare och vara svensk eller engelskspråkiga. Resultatet visade att patienter med lågt nutritionsstatus och låga serum albuminvärden riskerade att utveckla trycksår. En annan stor riskgrupp var patienter i peri- och postoperativa skeden där operationstiden kraftigt inverkade på uppkomsten av sår. Även anestesiformen spelade roll. Trycksåren uppkom vanligen på hälarna och korsbenet. I preventativt syfte var evidensbaserade mätskalor viktiga. Även trycksårsreducerande madrasser visade sig vara betydelsefulla. Vidare framkom att hälso- och sjukvårdspersonalen visade ett svalt intresse för trycksår och att kvalitetssäkringen var bristfällig. Sjuksköterskan hade främst en informerande roll inom trycksårspreventionen. Såren rengjordes lämpligast med fysiologisk koksaltlösning och omlades med våt omläggning. Resultatet visade även att smärtanalyser i högre grad borde involveras i trycksårsbehandlingen.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Syftet med studien var att beskriva subjektiva multifaktoriella metoder som sjuksköterskor kan använda för att identifiera äldre patienter med malnutrition och patienter med risk för att utveckla malnutriion. Syftet var vidare att redogöra för vilka undersökningar som sjuksköterskor i kliniskt arbete använder för att bedöma patienters nutrionsstatus med samt att belysa sjuksköterskors attityder till prevention av malnutritionstillstånd. Studien genomfördes som en systematisk litteraturstudie. De vetenskapliga artiklar (n=17) som ingick i studiens resultat söktes i databaserna ELIN@Dalarna och CINAHL. De sökord som användes var malnutrition, nutrition, undernutrition, elderly, screening, assessment, MNA, SGA, nurses och attitudes i olika kombinationer. Genom analys och granskning av de vetenskapliga artiklarna framkom det i resultatet att SGA, MNA, Simplified Model Malnourishment och NUFFE var subjektiva multifaktoriella metoder som sjuksköterskor kan använda för identifiering av äldre patienter med malnutrition eller risk för malnutrition. Den vanligaste undersökningen som sjuksköterskor bedömde patienters nutritionsstatus med var vägning. Andra undersökningar var mätning, BMI, intervju om normal vikt och viktförlust, observation av patienten, kostregistrering samt nutritionsplan i journalen. Sjuksköterskor upplevde att sjukhusledningen inte förväntade sig att bedömning av patienters nutritionsstatus skulle ske vid inskrivning samt att ansvarsfördelningen mellan sjuksköterskor och läkare var oklar. Det förekom att sjuksköterskor var ointresserade av behandling av malnutrition, men majoriteten var mycket intresserade. Många sjuksköterskor kände att deras kunskaper inom nutrition var otillräckliga för arbetet.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Syftet med studien var att undersöka konsekvenserna avseende fallolyckor bland äldre, samt att undersöka vilka preventiva metoder som presenteras i internationell vetenskaplig litteratur. Metod: Studien genomfördes som en systematisk litteraturstudie. Databassökningen gjordes i Blackwell Synergy och ELIN@Dalarna. De vetenskapliga artiklarna som ingick i studien var skrivna på svenska eller engelska samt publicerade mellan åren 1999 och 2007. Artiklarnas vetenskapliga kvalitet bedömdes utifrån granskningsmallar. I resultatet som grundar sig på 20 artiklar framkom det att hos dem som fallit under studieperioden och som föll igen inom en tremånadersperiod var risken att avlida i samband med det andra fallet 95 procent. Vanliga konsekvenser efter ett fall var höftfrakturer och andra kroppsliga skador samt även fysiska funktionsnedsättningar och imobilitet. Resultatet visade även att socialpsykologiska konsekvenser var vanligt förekommande där dominerande känslor var rädsla, ångest, kraft- och orkeslöshet, förlorad eller minskad självständighet, depression samt förlorad självkontroll. Kvinnor föll oftare, var oftare rädda och hade mer ångest, dessutom fick de oftare höftfrakturer och komplikationer i samband med fallet jämfört med männen. Multidisciplinära preventionsprogram minskade fallolyckorna signifikant. Tidig prevention hos riskgrupper var viktigt. Balansträningsprogram som exempelvis Tai Chi Chuan visade sig ha positiv effekt på balansen och minskade risken att falla. Slutsats: Fallolyckor bland äldre är ett växande problem inte bara i Sverige utan i stora delar av världen. Eftersom fallförebyggande åtgärder är ett komplext område med många faktorer som har betydelse för utfallet krävs det ett samarbete mellan många aktörer men framförallt mellan kommun och landsting. Prevention måste struktureras för bästa resultat lämpligen genom att använda en färdigställd lokal preventionsplan. De samhällsekonomiska vinsterna lokalt, regionalt och nationellt skulle bli stora om det preventiva arbetet prioriterades och effektiviserades.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Bakgrund: I Sverige ökade prevalensen av rupturer grad IV från 2,6% till 4,2% mellan åren 1994-2004. Årligen är det cirka tretusen kvinnor som drabbas av bristningar av grad III och IV i Sverige. Det är en stor spridning mellan Sveriges olika förlossningsavdelningar.Syfte: Syftet var att beskriva åtgärder för prevention av perinealbristningar av grad III och grad IV vid normal förlossning på samtliga förlossningsavdelningar i Sverige.Metod: Deskriptiv kartläggningsstudie med induktiv ansats. Det är en nationell studie som riktar sig till Sveriges alla förlossningsavdelningar. Endast perinealbristning av grad III och grad IV berördes.Resultat: Totalt deltog 38 av 47 (81%) av Sveriges förlossningsavdelningar i studien. Respondenterna var chefsbarnmorskor, avdelningschefer och enhetschefer. Av deltagande förlossningsavdelningar var det 12 (32%) som har någon form av vårdprogram för perinealskydd, många svarar att barnmorskorna utför perinealskydd på rutin. Dock var det inte vedertaget att alltid hålla perinealskydd vid 8% av avdelningarna. 18 avdelningar svarade JA på frågan om särskilda handgrepp användes och då uppgavs Ritgens handgrepp, det norska handgreppet och det finska handgreppet. 74 % använder sig av även andra metoder än handgrepp, framför allt värme (varma handdukar, dukar, handskar, kompresser) som hålls över perineum. Många tog upp vikten av god kommunikation och att hjälpa kvinnan att krysta i rätt tid. Förlossningsställningar som många använde sig av var sidoläge och knästående, medan andra hävdade att knästående ej användes pågrund av den ökande risken för bristningar. 71% av deltagande avdelningar får kontinuerlig utbildning och då nämndes främst workshops och utbildningsdagar.Slutsats: Metoder för att skydda perineum varierar mellan förlossningsavdelningarna i Sverige. På flera av Sveriges förlossningsavdelningar är det inte vedertaget att alltid använda perinealskydd vid normal förlossning. Vad som orsakar detta tros vara att en del barnmorskor, under utbildningen, fått lära sig att inte hålla perinealskydd.Klinisk implikation: Nationella rikitlinjer angående perinealskydd skulle vara av värde för att kunna erbjuda kvinnan vård på samma villkor landet över. Det är av stor vikt att den förlösande barnmorskan är uppmärksam på riskfaktorerna.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The use of ceramic material as refractories in the manufacturing industry is a common practice worldwide. During usage, for example in the production of steel, these materials do experience severe working conditions including high temperatures, low pressures and corrosive environments. This results in lowered service lives and high consumptions of these materials. This, in turn, affects the productivity of the whole steel plant and thereby the cost. In order to investigate how the service life can be improved, studies have been carried out for refractories used in the inner lining of the steel ladles. More specifically, from the slag zone, where the corrosion is most severe. By combining thermodynamic simulations, plant trails and post-mortem studies of the refractories after service, vital information about the behaviour of the slagline refractories during steel refining and the causes of the accelerated wear in this ladle area has been achieved. The results from these studies show that the wear of the slagline refractories of the ladle is initiated at the preheating station, through reduction-oxidation reactions. The degree of the decarburization process is mostly dependent on the preheating fuel or the environment. For refractories without antioxidants, refractory decarburization is slower when coal gas is used in ladle preheating than when a mixture of oil and air is used. In addition, ladle preheating of the refractories without antioxidants leads to direct wear of the slagline refractories. This is due to the total loss of the matrix strength, which results in a sand-like product. Thermal chemical changes that take place in the slagline refractories are due to the MgO-C reaction as well as the formation of liquid phases from impurity oxides. In addition, the decrease in the system pressure during steel refining makes the MgO-C reaction take place at the steel refining temperatures. This reduces the refractory’s resistance to corrosion. This is a serious problem for both the magnesia-carbon and dolomite-carbon refractories. The studies of the reactions between the slagline refractories and the different slag compositions showed that slags rich in iron oxide lead mostly to the oxidation of carbon/graphite in the carbon-containing refractories. This leads to an increased porosity and wettability and therefore an enhanced penetration of slag into the refractory structure. If the slag contains high contents of alumina and or silica (such as the steel refining slag), reactions between the slag components and the dolomite-carbon refractory are promoted. This leads to the formation of low-temperature melting phases such as calcium-aluminates and silicates. The state of these reaction products during steel refining leads to an accelerated wear of the dolomite-carbon refractory. The main products of the reactions between the magnesia-carbon refractory and the steel refining slag are MgAl2O4 spinels, and calcium-aluminates, and silicates. Due to the good refractory properties of MgAl2O4 spinels, the slag corrosion resistance of the magnesiacarbon refractory is promoted.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The current system of controlling oil spills involves a complex relationship of international, federal and state law, which has not proven to be very effective. The multiple layers of regulation often leave shipowners unsure of the laws facing them. Furthemore, nations have had difficulty enforcing these legal requirements. This thesis deals with the role marine insurance can play within the existing system of legislation to provide a strong preventative influence that is simple and cost-effective to enforce. In principle, insurance has two ways of enforcing higher safety standards and limiting the risk of an accident occurring. The first is through the use of insurance premiums that are based on the level of care taken by the insured. This means that a person engaging in riskier behavior faces a higher insurance premium, because their actions increase the probability of an accident occurring. The second method, available to the insurer, is collectively known as cancellation provisions or underwriting clauses. These are clauses written into an insurance contract that invalidates the agreement when certain conditions are not met by the insured The problem has been that obtaining information about the behavior of an insured party requires monitoring and that incurs a cost to the insurer. The application of these principles proves to be a more complicated matter. The modern marine insurance industry is a complicated system of multiple contracts, through different insurers, that covers the many facets of oil transportation. Their business practices have resulted in policy packages that cross the neat bounds of individual, specific insurance coverage. This paper shows that insurance can improve safety standards in three general areas -crew training, hull and equipment construction and maintenance, and routing schemes and exclusionary zones. With crew, hull and equipment, underwriting clauses can be used to ensure that minimum standards are met by the insured. Premiums can then be structured to reflect the additional care taken by the insured above and beyond these minimum standards. Routing schemes are traffic flow systems applied to congested waterways, such as the entrance to New York harbor. Using natural obstacles or manmade dividers, ships are separated into two lanes of opposing traffic, similar to a road. Exclusionary zones are marine areas designated off limits to tanker traffic either because of a sensitive ecosystem or because local knowledge is required of the region to ensure safe navigation. Underwriting clauses can be used to nullify an insurance contract when a tanker is not in compliance with established exclusionary zones or routing schemes.