Analysis of oxide formed on Ti during exposure in bentonite clay. I. The oxide growth

Titanium is a candidate as a canister material for the encapsulation of spent nuclear fuel due to its excellent corrosion properties. The aim of this paper is to determine the corrosion rate of titanium in ground-water saturated bentonite clay at 95°C. The exposure times were ranging from 4 months to 6 years. The analysis tool was ESCA. The results show that the oxide consists mainly of TiO² and is 65–90 Å thick. A few monolayers of TiO and Ti₂O₃ exist close to the metal interface. It is found, that the oxide follows the same logarithmic growth law as in aqueous solutions: y = 71.7 + 3.65 In t (y in Å and t in years). This law applies irrespective of salt or oxygen content or if bentonite is present on the surface. No influence of the alloying clement Pd was found. Deviations from the logarithmic growth law was also found, which indicates that a change of growth can occur in a long term perspective. It is suggested that the increased growth rate is caused by crystallization of the oxide. The influence of bentonite is that the majority component montmorillonite is adsorbed in a 10–40 Å thick layer on the surface.     

Cyclic nucleotides attenuate lipid peroxidation-mediated neuron toxicity

Recent studies suggest that increased lipid peroxidation and lipid peroxidation products, such as 4-hydroxynonenal (HNE), contribute to neuronal loss in conditions associated with oxidative stress. The focus of the present study was to determine possible neuroprotective effects of elevated cyclic nucleotide levels against lipid peroxidation and HNE-mediated neural toxicity. Application of 8-bromo derivative analogs of cAMP or cGMP resulted in attenuation of HNE-induced increases in mitochondrial calcium, reactive oxygen species, and neuron loss. Similar results were obtained when neural cells were pretreated with the phosphodiesterase inhibitors zaprinast or isobutylmethylxanthanine (IBMX). These data are consistent with a possible neuroprotective role for elevated cyclic nucleotide levels in disorders associated with increases in lipid peroxidation and HNE.     

Diagnosis of pancreatic carcinoma: role of FDG PET

OBJECTIVE: The purpose of this study was to investigate the role of positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) in differentiating benign from malignant disease in patients with possible pancreatic malignancy. SUBJECTS AND METHODS: All patients with a possible diagnosis of pancreatic carcinoma based on CT or ERCP findings were eligible for inclusion in this prospective study. PET imaging of the abdomen was performed in 37 patients and was interpreted as positive if FDG activity in the pancreas exceeded background activity and as negative if activity was less than or equal to background activity. Semiquantitative analysis was performed by calculating a standardized uptake ratio. Studies were reviewed independently by two radiologists, and results were correlated with biopsy results and with CT and ERCP findings. Sensitivity and specificity of FDG PET for revealing pancreatic malignancy was determined. RESULTS: FDG activity in the pancreas was increased in 24 patients, and adenocarcinoma was diagnosed in 22 of these patients (92%). Two patients (8%) with increased activity had benign disease, including one patient with chronic pancreatitis who showed no evidence of tumor at laparotomy and one patient with a mucinous cystic tumor who showed no malignant features at laparotomy. FDG uptake was low or normal in 13 patients, 10 of whom (77%) had benign disease. FDG uptake was also low in three patients with adenocarcinoma, whose tumor size ranged from 2 to 4 cm in diameter. The mean standardized uptake ratio value for malignant disease was 5.1 (range, 1.0-10.1) and for benign disease was 1.9 (range, 0.0-5.8) (p < .001). The sensitivity of FDG PET for revealing malignant disease in the pancreas was 88% and the specificity was 83%. CONCLUSION: FDG PET is a sensitive and specific noninvasive technique for the diagnosis of pancreatic malignancy.     

The Thought Disorder Index: Short-form assessments.

Investigated whether short forms of the Rorschach Test are as effective as the standard 10-card administration in eliciting thought disorder as measured by the Thought Disorder Index. Results showed the short 4-card forms yield excellent composite indexes of total thought disorder, severity levels, and the more frequently occurring qualitative scores. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Coadministration of zidovudine and interleukin-2 increases absolute CD4 cells in subjects with Walter Reed stage 2 human immunodeficiency virus infection: results of ACTG protocol 042

Interleukin-2 (IL-2) can increase numbers of absolute CD4 cells in persons infected with the human immunodeficiency virus who are receiving antiretroviral therapy. Twenty-five subjects with > 400/mm3 absolute CD4 cells received zidovudine and low-dose intravenous or subcutaneous IL-2 (< or = 10(6) U/m2). Absolute CD4 cells increased significantly during IL-2 treatment, and 56% of the subjects achieved a maximal increase of > or = 500 cells/mm3. A dose-response relationship favored increasing IL-2 doses, and subcutaneous delivery offered greater increases than intravenous administration. Fifteen subjects had persistent increases of > or = 100 cells/mm3 6 weeks after IL-2 was discontinued. No changes occurred in delayed-type hypersensitivity or helper T cell responses to recall antigens. Cell-mediated cytotoxicities increased against Daudi cells. IL-2 was well tolerated and only 1 subject required dose reduction. Relatively low-dose IL-2 delivered by subcutaneous or intravenous routes may provide an important complement to antiretroviral therapy to increase absolute CD4 cells with the potential for less toxicity than with higher IL-2 doses.     

Exploring the dimensions of egocentricity in aircraft navigation displays.

Researchers explain a model of navigation that proposes that local guidance and global awareness are better supported by more, and less, egocentric displays, respectively. Greater egocentrism is created by perspective viewing, map rotation, and viewpoint positions that correspond to the axis of control. The model was tested in an experiment in which 40 pilots flew simulated landings with displays that varied the degree of egocentrism between a fully egocentric viewpoint, 3 distances of exocentric 3-dimensional viewpoints, and a 2-dimensional planar display. The results generally supported model predictions: The egocentric viewpoint supported best guidance, whereas the mid-distance exocentric viewpoint supported best global awareness. Implications of the model for the design of flight displays in particular, and navigational displays in general, are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)