Since the 1915 launch of the first international eradication initiative targeting a human pathogen, much has been learned about the determinants of eradicability of an organism. The authors outline ...the first 4 eradication efforts, summarizing the lessons learned in terms of the 3 types of criteria for disease eradication programs: (1) biological and technical feasibility, (2) costs and benefits, and (3) societal and political considerations.
Background: Amine-containing (nitrosatable) drugs can react with nitrite to form N-nitroso compounds, some of which are teratogenic. Data are lacking on whether dietary intake of nitrates and ...nitrites modifies the association between maternal nitrosatable drug exposure and neural tube defects (NTDs) in offspring. Methods: We examined nitrosatable drug exposure and NTD-affected pregnancies in relation to dietary nitrite and total nitrite intake in a case-control study of Mexican American women. We interviewed 184 women with NTD-affected pregnancies and 225 women with normal live births, including questions on periconceptional drug exposures and dietary intake. For 110 study participants, nitrate was also measured in the usual source of drinking water. Results: Women who reported taking drugs classified as nitrosatable were 2.7 times more likely to have an NTD-affected pregnancy than women without this exposure (95% confidence interval CI = 1.4-5.3). The effect of nitrosatable drugs was observed only in women with higher intakes of dietary nitrite and total nitrite (dietary nitrite + 5% dietary nitrate). Women within the highest tertile (greater than 10.5 mg/day) of total nitrite were 7.5 times more likely to have an NTD-affected pregnancy if they took nitrosatable drugs (95% CI = 1.8-45.4). The association between nitrosatable drug exposure and NTDs was also stronger in women whose water nitrate levels were higher. Conclusions: Findings suggest that effects of nitrosatable drug exposure on risk for neural tube defects in offspring could depend on the amounts of dietary nitrite and total nitrite intake.
Hydrogen embrittlement of 316L type stainless steel Herms, E; Olive, J.M; Puiggali, M
Materials science & engineering. A, Structural materials : properties, microstructure and processing,
11/1999, Letnik:
272, Številka:
2
Journal Article
Recenzirano
Hydrogen embrittlement tests on type 316L stainless steel are performed including cathodic charging during slow strain rate tests. Brittle multiple cracking is observed and relationships between ...crack growth rate and diffusion are analysed. The influence of hydrogen on the morphology of ductile fracture is found after fractographic examination. Two aspects of ductile failure are observed in accordance with the hydrogen content of the sample; a reduced density of microvoids for higher hydrogen contents and brittle secondary cracking in addition to ductile fracture surfaces for lower hydrogen contents.
The susceptibility to stress corrosion cracking (SCC) of the Al-Zn-Mg-Cu French 7010 alloy of different temper has been investigated by Slow Strain Rate Testing. The tests have been carried out at ...strain rate ranged between 10
−5 and 10
−7s
−1, at corrosion potential and at cathodic polarisation, in NaCl and NaCl + As
2O
3 solution. The lowest susceptibility to SCC of overaged alloy has been explained by presence of large phase precipitates which increased the alloy resistance to pitting and intergranular corrosion, changed the conditions of crack initiation and trapped the absorbed hydrogen.
INTRODUCTIONHigh-strength aluminum alloys, especially the 2XXX and 7XXX series alloys, are used widely in aircraft construction because of their attractive properties, such as high strength-to-weight ...ratio, good fracture toughness, and low cost. These alloys, however, are susceptible to corrosion and corrosion fatigue that can compromise the integrity of aircraft structures. Localized pitting corrosion is considered one of the principal degradation mechanisms for these alloys, and corrosion pits have been identified as the major nuclei for onset of corrosion fatigue cracking.1-3 A better understanding of pitting in high-strength aluminum alloys is needed for estimating their corrosion fatigue response and for improving their performance. Because pitting is believed to begin by the breakdown of passive films on metal surfaces,4 the properties of oxide films on aluminum alloys have been studied by many researchers.5-10 For pure metals, the resistance to pitting is believed to depend upon electrochemical stability of the protective film and ability of the surface to repassivate.11 Pitting nucleation potentials (Enp) or pitting potentials (Ep), which characterize the electrochemical stability of the passive film, typically are used as a measure of the alloy's resistance to pitting.12-14 The most recent study on pitting in pure aluminum was that of Buzza and Alkire, who used a laser to initiate pitting.15 They suggested that pit growth is limited by diffusioncontrolled dissolution of a precipitated aluminum oxychloride film. A critical solution concentration at
Wernicke's syndrome after bariatric surgery SALAS-SALVADÓ, J.; GARCÍA-LORDA, P.; CUATRECASAS, G. ...
Clinical nutrition (Edinburgh, Scotland),
10/2000, Letnik:
19, Številka:
5
Journal Article
Recenzirano
Two young females with severe morbid obesity presented with Wernicke's syndrome after Roux-en-Y gastro-jejunum bypass had been performed. The first patient had recurrent vomiting and dyplopia two ...months post-surgery. Physical examination indicated bilateral ophthalmoparesia with conserved convergence and ataxia. The second patient had frequent vomiting episodes over the previous three months together with lower limb hypotonia, myoclonia and generalised tonicoclonic seizures on two occasions within one year of surgery. In both cases routine blood test, ion levels (sodium, potassium, calcium, phosphates), electroencephalogram and CT scan were normal. Thiamine therapy was instigated on the basis of clinical intuition and the first patient achieved complete remission within 24 hours while the second improved gradually in that two years later only mild lower limb hypotonia and a slight cognitive deficit remains. Erythrocyte transketolase activity determinations were abnormal on two separate occasions for this second patient. Vitamin B1 determinations were not available for the first patient. In conclusion, the restriction in energy intake and the persistent vomiting together with malabsorption induced by the surgical intervention could explain the vitamin deficiency causing Wernicke's encephalopathy. This indicates a need for close monitoring and systematic vitamin supplementation in those patients who undergo bariatric surgery.
Lessons learned from the successful end of endemic measles virus transmission (i.e., elimination) in the United States include the critical roles of strong political commitment, a regionwide ...initiative, adequate funding, and a broad coalition of partners. Implications of measles elimination in the United States for global measles control and regional elimination efforts include demonstration of the high vaccination coverage and, in turn, population immunity needed for elimination; the importance of accurate monitoring of vaccination coverage at local, state, and national levels; a vaccination strategy that includes at least 2 opportunities for measles immunization; and the essential role of integrated epidemiological and laboratory surveillance. The United States, with a population of 288 million, is, to our knowledge, the largest country to have ended endemic measles transmission. This experience provides evidence that sustained interruption of transmission can be achieved in large geographic areas, suggesting the feasibility of global eradication of measles.
Intergranular and transgranular fracture surfaces obtained in a face centered cubic alloy are studied using 3D maps reconstructed by scanning electron microscopy stereo imaging. The roughness ...exponents measured in the intergranular and transgranular surfaces, respectively, zeta = 0.83 +/- 0.05 and zeta = 0.75 +/- 0.05, are in agreement with the universal roughness value of 3D fractures. However, the slightly smaller value related to the transgranular surface could be a consequence of crystallographic transgranular zones disseminated on the surface whose roughness exponent zeta = 0.65 +/- 0.07 is close to the one usually measured on 2D fractures.
The morphology, the chemical composition, and the pitting corrosion resistance of a resulfurized stainless steel heated at 1000 °C for 2 hours were investigated at the microscale using ex-situ ...(field-emission-scanning electron microscope/electron dispersion spectrometer (FE-SEM/EDS) and secondary ion mass spectroscopy (SIMS)) and in-situ (electrochemical microcell technique and in-situ atomic force microscope (AFM) techniques. Although microcracks, which may have a deleterious effect, exist, the formation of a compound (Cr,Mn)^sub 2^(O,S)^sub 3^ instead of MnS is responsible for the better pitting corrosion resistance of sites containing an inclusion. Local electrochemical measurements indicate that no pitting was detected on these sites below 800 mV/SCE (saturated calomel electrode), whereas stable pitting was observed at around 350 mV/SCE before heating. Micropores were detected on the highly oxidized grains in which the ionic activity was found to be more marked than on the remaining surface (determined using in-situ AFM). Local electrochemical measurements revealed that the presence of such defects reduces significantly the corrosion resistance of the metallic alloy in NaCl-based media. PUBLICATION ABSTRACT
The accelerating progress in reducing measles incidence and mortality in many parts of the world has led to calls for its global eradication during the next 10–15 years. Three regions have ...established goals of elimination of indigenous transmission of measles. The strategy used in the Americas of a mass ‘catchup’ campaign of children 9 months to 15 years of age, high coverage through routine vaccination of infants, intensive surveillance and follow-up campaigns to prevent excessive build-up of susceptibles has had great success in reducing measles transmission close to zero. However, while these developments are impressive, much remains to be done to reduce measles-associated mortality in western and central Africa, where less than half of children are currently receiving measles vaccine and half a million children die from measles each year.
The obstacles to global measles eradication are perceived to be predominantly political and financial. There are also technical questions, however. These include the refinement of measles elimination strategies in the light of recent outbreaks in the Americas; the implications of the HIV epidemic for measles elimination, issues around injection safety, and concerns about the possibility that secondary vaccine failures will contribute in sustaining transmission in highly vaccinated populations. The global priorities are to improve measles control in low income countries, increase awareness among industrialized countries of the importance of measles, and conduct studies to answer the technical questions about measles elimination strategies.
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