The influence of NaCl and CO2 on the atmospheric corrosion of magnesium alloy AZ91

The influence of NaCl and CO₂ on the atmospheric corrosion of magnesium alloy AZ91 is studied in the laboratory. Samples were exposed under carefully controlled air and flow conditions; the relative humidity was 95%, the temperature was 22.0°C and the concentration of CO₂ was < 1 ppm or 350 ppm. Different amounts of sodium chloride (0–70 μg/cm²) were added before exposure. The corrosion products were analyzed by gravimetry, ion chromatography, X‐ray diffraction and scanning electron microscopy. Mass gain and metal loss results are reported. The combination of high humidity and NaCl is very corrosive towards AZ91. However, the NaCl‐induced corrosion is inhibited by ambient concentrations of CO₂. Exposure in the absence of CO₂ gives rise to heavy pitting, with brucite, Mg(OH)₂, being the dominant corrosion product. In the presence of CO₂ a layer of hydrated magnesium hydroxy carbonate, Mg₅(CO₃)₄(OH)₂ · 5 H₂O forms. A tentative corrosion mechanism is presented that explains the behavior in the two environments.     

Microstructural investigation of the breakdown of the protective oxide scale on a 304 steel in the presence of oxygen and water vapour at 600 °C

This article focuses on the detailed microstructural investigation of the oxide scale formed on a 304 steel in the presence of oxygen and water vapour (40%) at 600 °C. The work has been carried out using a combination of microanalytical techniques including FIB, TEM, EDX and electron diffraction. The local breakdown of the initially protective oxide scale and the growth of island/crater oxide morphology are described. Special consideration is given to the influence of the microstructure of the steel and the oxide scale on the breakdown behaviour.     

Association between oxygen delivery and consumption in patients undergoing cardiac surgery. Is there supply dependence?

Numerous investigators have suggested that cell glycoconjugates are modified by the development of cancer and the progression of this to a malignant form. Accordingly, in the present work, beta-D-galactosidase, alpha-L-fucosidase, beta-N-acetyl-D-glucosaminidase and beta-N-acetyl-D-galactosaminidase activities were studied in human thyroid and gastric tumours. Samples were obtained from human gastric mucosa and thyroid gland tumours together with a part of the surrounding normal tissue (control). Enzyme activity was determined spectrophotometrically based on the release of p-nitrophenol from suitable p-nitrophenyl-derivative substrates. Results showed that beta-D-galactosidase, alpha-L-fucosidase, beta-N-acetyl-D-glucosaminidase and beta-N-acetyl-D-galactosaminidase activities were detected in tumour and control samples from thyroid and gastric tissues. The gastric mucosa also showed alpha-L-mannosidase activity. The specific activities of these glycosidases were higher (two- or three-fold) in tumour tissues as compared with their controls. beta-D-galactosidase, beta-N-acetyl-D-glucosaminidase and beta-N-acetyl-D-galactosaminidase activities from thyroid and gastric tumours showed a significant increase in V(max) as compared with their respective controls (P < 0.05 or P < 0.001). Thyroid alpha-L-fucosidase activity showed a statistically and significantly increased affinity (lower K(m)) in tumour samples as compared to normal tissue. In conclusion both gastric and thyroid tumours showed enhanced glycosidase activity as compared with enzyme activity observed in normal tissue. These results are in agreement with the notion of a markedly raised degradation within lysosomes of tumour cells.     

Intensive postremission chemotherapy in adults with acute myeloid leukemia. Cancer and Leukemia Group B

BACKGROUND: About 65 percent of previously untreated adults with primary acute myeloid leukemia (AML) enter complete remission when treated with cytarabine and an anthracycline. However, such responses are rarely durable when conventional postremission therapy is administered. Uncontrolled trials have suggested that intensive postremission therapy may prolong these complete remissions. METHODS: We treated 1088 adults with newly diagnosed AML with three days of daunorubicin and seven days of cytarabine and randomly assigned patients who had a complete remission to receive four courses of cytarabine at one of three doses: 100 mg per square meter of body-surface area per day for five days by continuous infusion, 400 mg per square meter per day for five days by continuous infusion, or 3 g per square meter in a 3-hour infusion every 12 hours (twice daily) on days 1, 3, and 5. All patients then received four courses of monthly maintenance treatment. RESULTS: Of the 693 patients who had a complete remission, 596 were randomly assigned to receive postremission cytarabine. After a median follow-up of 52 months, the disease-free survival rates in the three treatment groups were significantly different (P = 0.003). Relative to the 100-mg group, the hazard ratios were 0.67 for the 3-g group (95 percent confidence interval, 0.53 to 0.86) and 0.75 for the 400-mg group (95 percent confidence interval, 0.60 to 0.94). The probability of remaining in continuous complete remission after four years for patients 60 years of age or younger was 24 percent in the 100-mg group, 29 percent in the 400-mg group, and 44 percent in the 3-g group (P = 0.002). In contrast, for patients older than 60, the probability of remaining disease-free after four years was 16 percent or less in each of the three postremission cytarabine groups. CONCLUSIONS: These data support the concept of a dose-response effect for cytarabine in patients with AML who are 60 years of age or younger. The results with the high-dose schedule in this age group are comparable to those reported in similar patients who have undergone allogeneic bone marrow transplantation during a first remission.     

Lateral buckling of beams analysed as elastically supported columns subject to a varying axial force

The stability problem for an elasticallu supported column subject to a varying axial force has been solved by means of a general numerical procedure based on Galerkin's method. Apart from the intrinsic value of the solution itself, its possible value modelling some complex stability problems in the area of restrained lateral-torsional stability problems is demonstrated and specific numerical solutions are applied to the case of lateral buckling of the free flange of a composite girder. The results obtained are discussed and suggestions for additional investigations are presented.     

Can radioactive iodine be used in the treatment of diffuse non-toxic goiter?

Traditional treatment modalities of diffuse nontoxic goitre are thyroid hormone suppression or surgery. When treating nodular nontoxic goitre with 131I treatment, a reduction in thyroid volume to about 50% is seen. In the present study we evaluated the effect of 131I treatment in 21 patients treated for a diffuse nontoxic goitre and followed by evaluation of thyroid volume measured by ultrasound. Thyroid volume declined in all patients from median of 66 ml (range 27-160 ml) to 21 ml (9-108 ml) over a year, a reduction of 62%. Three patients developed hypothyroidism in the follow-up period (14%), one of these had a temporary hyperthyroid fase. In conclusion, 131I treatment of diffuse nontoxic goitre reduces thyroid volume by approximately 60% within 12 months. Hypothyroidism developed in 14% during a limited follow-up period.