Effect of strain rate on the formation of nanocrystallites in an Al-based amorphous alloy during nanoindentation

Copyright 2003 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The article originally appeared in Journal of Applied Physics 93, 9287 (2003) and may be found at http://jap.aip.org/resource/1/japiau/v93/i11/p9287_s1.The effect of deformation by nanoindentation on nanocrystallization in amorphous Al90Fe5Gd5Al90Fe5Gd5 was investigated by transmission electron microscopy. Massive precipitation of nanocrystallites is observed within the indents. Under the quasistatic condition used, a temperature rise due to adiabatic heating is likely negligible, confirming that plastic deformation can induce crystallization without a heating effect. The nucleation of nanocrystallites is significantly affected by the strain rate. © 2003 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69990/2/JAPIAU-93-11-9287-1.pd

Lava channel formation during the 2001 eruption on Mount Etna: evidence for mechanical erosion

We report the direct observation of a peculiar lava channel that was formed near the base of a parasitic cone during the 2001 eruption on Mount Etna. Erosive processes by flowing lava are commonly attributed to thermal erosion. However, field evidence strongly suggests that models of thermal erosion cannot explain the formation of this channel. Here, we put forward the idea that the essential erosion mechanism was abrasive wear. By applying a simple model from tribology we demonstrate that the available data agree favorably with our hypothesis. Consequently, we propose that erosional processes resembling the wear phenomena in glacial erosion are possible in a volcanic environment.Comment: accepted for publication in Physical Review Letter

High-dose cyclosporin with etoposide--toxicity and pharmacokinetic interaction in children with solid tumours.

The tolerability, anti-tumour activity and pharmacokinetic interaction of high-dose intravenous cyclosporin combined with intravenous etoposide was evaluated in children. Eighteen patients with recurrent or refractory tumours, all of whom had previously received etoposide, were treated with a combination of high-dose cyclosporin and etoposide. In 13, cyclosporin was given as a continuous infusion (15 mg kg(-1) per 24 h for 60 h) and in five a short 3-hour infusion of 30 mg kg(-1) day(-1) on three consecutive days. Pharmacokinetic profiles of etoposide were determined with and without cyclosporin. Cyclosporin levels ranged from 1359 to 4835 ng ml(-1) and cyclosporin increased the median area under the concentration time for etoposide curve from 7.2 to 12.5 mg ml(-1) min. The major toxicity was acute with varying forms of hypersensitivity reactions. In four cases this was severe. Hyperbilirubinaemia was present in 25 of 32 courses but was of short duration. In 14 courses, creatinine and/or urea was elevated, but was also transient. Significant hypertension was seen in six courses. Four of 17 patients evaluable for response obtained a partial response and one showed stable disease. It is concluded that in children given the combination of high-dose cyclosporin and etoposide, the etoposide dose should be halved in order to achieve an area under the drug concentration-time curve similar to that with etoposide alone. A continuous infusion schedule of cyclosporin is better tolerated during the period of administration but is associated with similar hepatic and renal dysfunction to a short schedule. The 24% response rate in children who had previously received etoposide suggests that this may be an effective method of enhancing drug sensitivity and further phase II evaluation is justified

Air Pollution and Lymphocyte Phenotype Proportions in Cord Blood

Effects of air pollution on morbidity and mortality may be mediated by alterations in immune competence. In this study we examined short-term associations of air pollution exposures with lymphocyte immunophenotypes in cord blood among 1,397 deliveries in two districts of the Czech Republic. We measured fine particulate matter < 2.5 μm in diameter (PM(2.5)) and 12 polycyclic aromatic hydrocarbons (PAHs) in 24-hr samples collected by versatile air pollution samplers. Cord blood samples were analyzed using a FACSort flow cytometer to determine phenotypes of CD3(+) T-lymphocytes and their subsets CD4(+) and CD8(+), CD19(+) B-lymphocytes, and natural killer cells. The mothers were interviewed regarding sociodemographic and lifestyle factors, and medical records were abstracted for obstetric, labor and delivery characteristics. During the period 1994 to 1998, the mean daily ambient concentration of PM(2.5) was 24.8 μg/m(3) and that of PAHs was 63.5 ng/m(3). In multiple linear regression models adjusted for temperature, season, and other covariates, average PAH or PM(2.5) levels during the 14 days before birth were associated with decreases in T-lymphocyte phenotype fractions (i.e., CD3(+) CD4(+), and CD8(+)), and a clear increase in the B-lymphocyte (CD19(+)) fraction. For a 100-ng/m(3) increase in PAHs, which represented approximately two standard deviations, the percentage decrease was −3.3% [95% confidence interval (CI), −5.6 to −1.0%] for CD3(+), −3.1% (95% CI, −4.9 to −1.3%) for CD4(+), and −1.0% (95% CI, −1.8 to −0.2%) for CD8(+) cells. The corresponding increase in the CD19(+) cell proportion was 1.7% (95% CI, 0.4 to 3.0%). Associations were similar but slightly weaker for PM(2.5). Ambient air pollution may influence the relative distribution of lymphocyte immunophenotypes of the fetus

The Prevalence of L. monocytogenes in Cull Sows

The goal of this study was to determine the distribution of Listeria monocytogenes in cull sows and their pork. Two trials were conducted at a single packing plant in 2001 (n=179 cull sows) and in 2002 (n= 160 cull sows). Fecal samples collected antemortem (trial 1) as well as animal tissues, carcass, and environmental swabs, and meat block samples collected at the abattoir (trials 1 and 2) were analyzed. When results from both trials were combined, overall L. monocytogenes was detected in five or 0.17% of the total samples (n=2,858). Specifically, L. monocytogenes was confirmed in a tonsil sample (0.55% of tonsils positive) and in a carcass swab sample (0.56% of carcasses) before the organic acid rinse. L. monocytogenes was recovered in three (1.21%) meat block samples (n=213). These data indicate that L. monocytogenes is present in the cull sow and their pork

Distribution of particulate matter and tissue remodeling in the human lung.

We examined the relationship between intrapulmonary particle distribution of carbonaceous and mineral dusts and remodeling of the airways along anatomically distinct airway paths in the lungs of Hispanic males from the central valley of California. Lung autopsy specimens from the Fresno County Coroner's Office were prepared by intratracheal instillation of 2% glutaraldehyde at 30 cm H(2)O pressure. Two distinct airway paths into the apico-posterior and apico-anterior portions of the left upper lung lobe were followed. Tissue samples for histologic analysis were generally taken from the intrapulmonary second, fourth, sixth, and ninth airway generations. Parenchymal tissues beyond the 12th airway generation of each airway path were also analyzed. There was little evidence of visible particle accumulation in the larger conducting airways (generations 2-6), except in bronchial-associated lymphoid tissues and within peribronchial connective tissue. In contrast, terminal and respiratory bronchioles arising from each pathway revealed varying degrees of wall thickening and remodeling. Walls with marked thickening contained moderate to heavy amounts of carbonaceous and mineral dusts. Wall thickening was associated with increases in collagen and interstitial inflammatory cells, including dust-laden macrophages. These changes were significantly greater in first-generation respiratory bronchioles compared to second- and third-generation respiratory bronchioles. These findings suggest that accumulation of carbonaceous and mineral dust in the lungs is significantly affected by lung anatomy with the greatest retention in centers of lung acini. Furthermore, there is significant remodeling of this transitional zone in humans exposed to ambient particulate matter

Role of small Rhizaria and diatoms in the pelagic silica production of the Sourther Ocean

We examined biogenic silica production and elementary composition (biogenic Si, particulate organic carbon and particulate organic nitrogen) of Rhizaria and diatoms in the upper 200 m along a transect in the Southwest Pacific sector of the Southern Ocean during austral summer (January–February 2019). From incubations using the 32Si radioisotope, silicic acid uptake rates were measured at 15 stations distributed in the Polar Front Zone, the Southern Antarctic Circumpolar Current and the Ross Sea Gyre. Rhizaria cells are heavily silicified (up to 7.6 nmol Si cell−1), displaying higher biogenic Si content than similar size specimens found in other areas of the global ocean, suggesting a higher degree of silicification of these organisms in the silicic acid rich Southern Ocean. Despite their high biogenic Si and carbon content, the Si/C molar ratio (average of 0.05 ± 0.03) is quite low compared to that of diatoms and relatively constant regardless of the environmental conditions. The direct measurements of Rhizaria's biogenic Si production (0.8–36.8 μmol Si m−2 d−1) are of the same order of magnitude than previous indirect estimations, confirming the importance of the Southern Ocean for the global Rhizaria silica production. However, diatoms largely dominated the biogenic Si standing stock and production of the euphotic layer, with low rhizarians' abundances and biogenic Si production (no more than 1%). In this manuscript, we discuss the Antarctic paradox of Rhizaria, that is, the potential high accumulation rates of biogenic Si due to Rhizaria in siliceous sediments despite their low production rates in surface waters.Versión del editor3,38

Direct exfoliation and dispersion of two-dimensional materials in pure water via temperature control

The high-volume synthesis of two-dimensional (2D) materials in the form of platelets is desirable for various applications. While water is considered an ideal dispersion medium, due to its abundance and low cost, the hydrophobicity of platelet surfaces has prohibited its widespread use. Here we exfoliate 2D materials directly in pure water without using any chemicals or surfactants. In order to exfoliate and disperse the materials in water, we elevate the temperature of the sonication bath, and introduce energy via the dissipation of sonic waves. Storage stability greater than one month is achieved through the maintenance of high temperatures, and through atomic and molecular level simulations, we further discover that good solubility in water is maintained due to the presence of platelet surface charges as a result of edge functionalization or intrinsic polarity. Finally, we demonstrate inkjet printing on hard and flexible substrates as a potential application of water-dispersed 2D materials.close1