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The aim of the present work is to explore the age-hardening potential of Ti-6Al-4V (Ti-64) alloy with variation of the starting microstructure, with attention to the precipitation of nano-sized Ti3Al phase, as influenced by microstructural features. The alloy was either solution-treated or deformed by compression at temperatures above and below its β-transus to produce microstructures comprising martensitic, lamellar and globular α morphologies, as well as the existence or absence of β phase, and subsequently submitted to ageing treatments at 400°C/8h using in situ x-ray diffraction. Precipitated fractions of Ti3Al were obtained via Rietveld refinement and aged microstructures were characterized by micro-hardness measurements. Results show that α2 precipitation is favored by a globular morphology of α and hindered by a martensitic α morphology, and suggest that the presence of β phase also has as influence on precipitation.

The austenitic stainless steels are a group of alloys normally used under high mechanical and thermal requests, in which high temperature oxidation is normally present due to oxygen presence. This study examines the oxide layer evolution for Fe24Cr12NiXNb modified austenitic stainless steel A297 HH with 0,09%Nb and 0,77%Nb content at 900°C under atmospheric air and isothermal oxidation. The modifiers elements such as Mo, Co and Ti, added to provide high mechanical strength, varied due to the casting procedure, however main elements such as Cr, Ni, Mn and Si were kept at balanced levels to avoid microstructure changing. The oxide layer analysis was performed by confocal laser scanning microscopy (CLS) and scanning electron microscopy (SEM). The elemental analysis of the different phases was measured with energy dispersive X-ray spectroscopy (EDX). The Nb-alloyed steel generated a thicker Cr oxide layer. Generally elemental Nb did not provide any noticeable difference in oxide scale growth, for the specific range of Nb amount and temperature studied. High temperature oxidation up to 120h was characterized by protective Cr oxidation, after this period a non-protective Fe-based oxidation took place. Cr, Fe and Ni oxides were observed in the multilayer oxide scale. [ABSTRACT FROM AUTHOR]

Aluminium plates are used as power attenuators in beamline ID15 at the ESRF. They absorb the low-energy part of the synchrotron light to reduce the heat-load on the following beamline components. Despite of many proposed design criteria, the high heat-load generated in the zone interacting with the X-rays may result in a marked deterioration of the absorber plate. Absorber plates of an old design, that failed were investigated here. Microscopy and diffraction methods revealed that the irradiated zone recrystallized during service and that its mechanical properties deteriorated. High thermal stresses built up, which were relieved by crack formation. Today a new aluminium power attenuator with an optimised cooling system is implemented, which so far is successful. This investigation shall give evidence about possible failure sources since in case of an increase in electron storage ring current, the increase in heat-load similar absorber failures shall be prevented. [ABSTRACT FROM AUTHOR]

An in situ study of the kinetics of nucleation and growth of the γ′ phase in the single crystal Ni base superalloy SC16 was carried out by means of neutron diffraction. The investigation was aimed at a better understanding of the fundamental kinetic phenomena, in view of the optimisation of the heat treatments applied prior to the industrial use of the alloy. On heating above the solvus point (1525 K) the γ′ phase decomposes, and when cooling down back towards lower temperatures, it reappears. Measuring superlattice reflections allows the different stages of decomposition, nucleation, growth and concurrent coarsening to be followed. Results show that at temperatures T≤1490 K an increasing volume fraction of γ′ can be found with decreasing temperature, until saturation occurs at around 1100 K. Following classical kinetic theory, an Avrami like growth (time) law was used at each aging temperature and the isothermal reaction rates calculated. They show a maximum at around 1300 K, where the competing nucleation and growth processes find equilibrium. Nucleation and growth can be described with a modified Arrhenius law, analogous to that used for eutectoid reactions. The reaction rate first increases with the undercooling and then decreases. This implies a change in the character of the reaction, which was found to be initially surface and then bulk driven. [ABSTRACT FROM AUTHOR]

Our objective was to evaluate the histopathological features of chronic hepatitis C of 64 liver biopsies and to correlate this with the route of transmission of hepatitis C virus, the genotype of HCV, and the patient's age. Moderate chronic hepatitis was the most frequently observed (62.5%). Cirrhosis was observed in 14 patients (21.9%) and was more frequently found among patients over 40 years of age (34.3% vs. 6.9%, P = 0.025). The mean histopathological activity index (HAI) was significantly higher in the sporadic (10+/-3.1) than the posttransfusional (7.5+/-3.7) and the intravenous drug use (IVDU) groups (6.3+/-2.8) (P<0.02). Moreover the sporadic group showed more fibrosis (P<0.04) than the posttransfusional group. No liver cirrhosis was found in the IVDU group. The overall prevalence of HCV variants was: 54.7% type 1b, 4.6% type 1a, 37.5% type 2c, 1.6% type 2b, 1.6% type 2. The genotype distribution showed no relation to the HAI, hepatitis activity (grade), and fibrosis (stage) of the liver disease. In conclusion, the sporadic route of transmission of HCV was related to a more severe chronic hepatic disease, a finding that could influence future antiviral therapies. The predominance of HCV type 1b in this study reflects the higher frequency of this variant in our area. Our data suggests that the ultimate consequence of HCV chronic infection depends on patient age rather than on HCV genotype.

This study reports a clinicopathological analysis of 105 patients whose liver histology showed a pattern of alcohol-like steatohepatitis. There were 32 nonalcoholic, 21 asymptomatic ambulatory, and 52 hospitalized alcoholic hepatitis patients. Female sex, obesity, and diabetes predominated in nonalcoholics. Clinical and laboratory presentation were similar in nonalcoholics and ambulatory alcoholics, but different from the hospitalized alcoholics. Histology showed an increasing degree of severity of hepatocellular damage, Mallory bodies, neutrophil and mononuclear infiltration, and pericellular and portal fibrosis from the nonalcoholics to the hospitalized alcoholics, with ambulatory alcoholics displaying an intermediate degree of severity. Steatosis and glycogenated nuclei were prevalent in the obese, diabetic nonalcoholics, of whom 47% had significant fibrosis and 8% cirrhosis, the latter present in 38% and 89% of ambulatory and hospitalized alcoholic hepatitis (P = 0.0001), respectively. In asymptomatic subjects with suspected liver disease, a liver biopsy is the only way of establishing the type and severity of liver lesions.

Background/aims: Genetically diabetic (db/db) mice are a model for non-insulin-dependent diabetes in humans. The gastrointestinal tracts in 12-week-old db/db and nondiabetic control (db/+) mice were studied with particular emphasis on the endocrine cells., Methods: Immunocytochemical and quantification techniques were used to localize and determine the number of cells containing serotonin and various regulatory peptides., Results: In the antrum, the gastrin- and serotonin-immunoreactive cells were increased in number. In the large intestine, the enteroglucagon and the peptide tyrosine-immunoreactive cells were increased in number, whereas there were fewer serotonin-immunoreactive cells. There were also fewer somatostatin-immunoreactive cells in most gastrointestinal regions. In diabetic mice, the intestine was longer and its mucosa thicker than in control mice., Conclusions: The results indicate that the genetic diabetic (db/db) condition exerts a significant influence on the gastrointestinal tract and on the endocrine cell systems studied. The observed alterations may reflect the effect of indirect factors rather than the diabetes per se.

At present immune-based therapies are not an alternative to alpha-interferon in the treatment of chronic hepatitis B. Patients who do not respond to alpha-interferon should probably be followed without re-treatment. Re-treatment using a short course of prednisone before alpha-interferon deserves further study. Future investigation of immune-based therapies should be done in the context of available antiviral therapies. Alternatives need to be propounded and tested, especially alternatives that cause us to question assumptions and to rethink our current beliefs about chronic HBV immunopathogenesis.

A study has been carried out on the 5-yr survival curves of 287 patients admitted with upper gastrointestinal bleeding and portal hypertension. In 78.7%, the cause of bleeding was from esophageal varices. Only 2.4% had noncirrhotic portal hypertension, and 80% were alcoholics. At 5 yr, the overall survival probability was 26.2%. The curve had three segments with survival rates of 69% at 2 wk and 46.6% at 12 months. According to Child's grade, the curves were very different at 2 wk, 12 months, and 60 months: Group A, 94.0, 78.0, and 51.8%; group B, 77.0, 46.0, and 32.2; group C, 52.0, 11.0, and 2.3%. The largest differences were observed in the first 2 wk immediately after the first bleeding. The recurrence of bleeding in a period of 6 months significantly decreased the survival. Age, as well as the introduction of prophylactic measures (propranolol or sclerotherapy), did not influence long-term survival. Alcohol abstinence was accompanied by better survival. This difference was due to the impact of abstinence only in group B patients.