Critical cooling rate and thermal stability of Zr–Ti–Cu–Ni–Be alloys

The critical cooling rate as well as the thermal stability are measured for a series of alloys in the Zr–Ti–Cu–Ni–Be system. Upon cooling from the molten state with different rates, alloys with compositions ranging along a tie line from (Zr70Ti30)55(Ni39Cu61)25Be20 to (Zr85Ti15)55(Ni57Cu43)22.5Be27.5 show a continuous increase in the critical cooling rate to suppress crystallization. In contrast, thermal analysis of the same alloys shows that the undercooled liquid region, the temperature difference between the glass transition temperature and the crystallization temperature, is largest for some compositions midway between the two endpoints, revealing that glass forming ability does not correlate with thermal stability. The relationship between the composition-dependent glass forming ability and thermal stability is discussed with reference to a chemical decomposition process

Protein transduction: A novel tool for tissue regeneration

Tissue regeneration in humans is limited and excludes vitals organs like heart and brain. Transformation experiments with oncogenes like T antigen have shown that retrodifferentiation of the respective cells is possible but hard to control. To bypass the risk of cancer formation a protein therapy approach has been developed. The transient delivery of proteins rather than genes could still induce terminallydifferentiated cells to reenter the cell cycle. This approach takes advantage of proteintransducing domains that mediate the transfer of cargo proteins into cells. The goal of this brief review is to outline the basics of protein transduction and to discuss potential applications for tissue regeneration

Anti-tumor necrosis factor-alpha therapy during murine Klebsiella pneumoniae bacteremia: increased mortality in the absence of liver injury.

Klebsiella pneumoniae is a leading cause of gram-negative bacterial pneumonia, often resulting in bacteremia concurrent with the localized pulmonary infection. The beneficial role of tumor necrosis factor (TNF)-alpha during pulmonary infection has been well documented; however, consequences of TNF-alpha production during systemic bacterial infection are controversial. A murine model of K. pneumoniae was developed to address this important issue. Liver-associated TNF-alpha mRNA was induced within 30 min after intravenous bacterial inoculation and remained elevated through 6 h before returning to near-baseline at 24 h postinfection. Intravenous K. pneumoniae infection induced liver cellular injury that was completely ablated when mice were pretreated with a neutralizing anti-TNF-alpha antibody. Interestingly, this reduction in liver injury failed to translate into improved survival. Mice receiving anti-TNF-alpha continued to succumb to the infection even out to day 10 postinfection. Bacterial clearance after TNF-alpha neutralization was significantly impaired at later time points during infection. Correlating with impaired bacterial clearance was diminished production of liver-associated MIP-2, MIP-1alpha, MCP-1, and interferon-gamma. Further evidence of diminished antibacterial immune responses was noted when the activational status of splenic natural killer cells in anti-TNF-alpha-treated mice was examined 24 h postinfection. Natural killer cells displayed decreased CD69 expression. Combined, these data indicate that the beneficial effects of TNF-alpha during systemic K. pneumoniae infection outweigh the detrimental effects of TNF-alpha-mediated hepatocyte cellular injury. Anti-TNF-alpha therapy, although preventing liver injury during blood-borne bacterial infection, results in a dampened anti-bacterial host response, resulting in decreased bacterial clearance and overall survival

Is There Enhanced Depletion of Gas-Phase Nitrogen in Moderately Reddened Lines of Sight?

We report on the abundance of interstellar neutral nitrogen (NI) for 30 sightlines, using data from the Far Ultraviolet Spectroscopic Explorer (FUSE) and the Hubble Space Telescope (HST). NI column densities are derived by measuring the equivalent widths of several ultraviolet absorption lines and subsequently fitting those to a curve of growth. We find a mean interstellar N/H of 51+/-4 ppm. This is below the mean found by Meyer et al. of 62(+4,-3) ppm (adjusted for a difference in f-values). Our mean N/H is similar, however, to the (f-value adjusted) mean of 51+/-3 ppm found by Knauth et al. for a larger sample of sightlines with larger hydrogen column densities comparable to those in this study. We discuss the question of whether or not nitrogen shows increased gas-phase depletion in lines of sight with column densities log(H_tot) >~ 21, as claimed by Knauth et al. The nitrogen abundance in the line of sight toward HD 152236 is particularly interesting. We derive very small N/H and N/O ratios for this line of sight that may support a previous suggestion that members of the Sco OB1 association formed from an N-deficient region.Comment: Accepted in The Astrophysical Journal, 9/2006 (expected pub. date: 1/2007) 38 pages, 5 figures (4 color

The Oxidizable Organic Matter and Organic Nitrogen Content of the Okoboji Lakes

The amount of dissolved organic material which is present in a lake may be used as an index of the amount of food available for growth of micro-organisms, and is therefore of importance in studying the biological productivity of any given body of water. The purpose of this investigation was to determine the amount and distribution of organic matter in the Okoboji Lakes. This was studied as a function of depth below the surface and also as a function of the particle size of the organic material, that is, whether the material could be considered as net plankton, nannoplankton, or as dissolved matter. For this investigation two general methods were used: (1) Determination of the amount of readily oxidizable organic material by means of the potassium permanganate method. Data of this type are usually referred to as the oxygen consumption of the material. (2) Determination of the amount of organic nitrogen present by means of a modified Kjeldahl method. For convenience these will be considered separately

Flagellar membrane association via interaction with lipid rafts

The eukaryotic flagellar membrane has a distinct composition from other domains of the plasmalemma. Our work shows that the specialized composition of the trypanosome flagellar membrane reflects increased concentrations of sterols and saturated fatty acids, correlating with direct observation of high liquid order by laurdan fluorescence microscopy. These findings indicate that the trypanosome flagellar membrane possesses high concentrations of lipid rafts: discrete regions of lateral heterogeneity in plasma membranes that serve to sequester and organize specialized protein complexes. Consistent with this, a dually acylated Ca(2+) sensor that is concentrated in the flagellum is found in detergent-resistant membranes and mislocalizes if the lipid rafts are disrupted. Detergent-extracted cells have discrete membrane patches localized on the surface of the flagellar axoneme, suggestive of intraflagellar transport particles. Together, these results provide biophysical and biochemical evidence to indicate that lipid rafts are enriched in the trypanosome flagellar membrane, providing a unique mechanism for flagellar protein localization and illustrating a novel means by which specialized cellular functions may be partitioned to discrete membrane domains

Genetic control of cadmium tolerance in Drosophila melanogaster.

Files from a transgenic line of Drosophila melanogaster with two copies of the metallothionein allele Mtn3 were more tolerant to cadmium than strains with only one copy of the gene. However, flies with the Mtn3 allele were as tolerant as flies with the Mtn3 allele, despite the level of expression of Mtn3 being three times higher than of Mtn3. We propose that the substitution of Lys-40 (in Mtn3) for Glu-40 (in Mtn1) accounts for a reduction in binding affinity of Mtn1, which offsets the increased expression levels