Gamma-ray bursts: cosmic rulers for the high-redshift universe?

The desire to extend the Hubble Diagram to higher redshifts than the range of current Type 1a Supernovae observations has prompted investigation into spectral correlations in gamma-ray bursts (GBRs), in the hope that standard candle-like properties can be identified. In this paper, we discuss the potential of these new 'cosmic rulers' and highlight their limitations by investigating the constraints that current data can place on an alternative Cosmological model in the form of Conformal Gravity. By fitting current Type 1a Supernovae and GRB data to the predicted luminosity distance redshift relation of both the standard Concordance Model and the Conformal Gravity, we show that currently neither model is strongly favoured at high redshift. The scatter in the current GRB data testifies to the further work required if GRBs are to cement their place as effective probes of the cosmological distance scale.     

Lipid molecular order in liver mitochondrial outer membranes, and sensitivity of carnitine palmitoyltransferase I to malonyl-CoA

Mitochondrial outer membranes were prepared from livers of rats that were in the normal fed state, starved for 48 h, or made diabetic by injection of streptozotocin. Membranes were also prepared from starved late-pregnant rats. The latter three conditions have previously been shown to induce varying degrees of desensitization of mitochondrial overt carnitine palmitoyltransferase (CPT I) to malonyl-CoA inhibition. We measured the fluorescence polarization anisotropy of two probes, 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene-p-toluenesulfonate (TMA-DPH) which, when incorporated into membranes, report on the hydrophobic core and on the peripheral regions of the bilayer, respectively. The corresponding polarization indices (r _DPH and r _TMA-DPH) were calculated. In membranes of all three conditions characterized by CPT I desensitization to malonyl-CoA, r _DPH was decreased, whereas there was no change in r _TMA-DPH, indicating that CPT I is sensitive to changes in membrane core, rather than peripheral, lipid order. The major lipid components of the membranes were analyzed. Although significant changes with physiological state were observed, there was no consistent pattern of changes in gross lipid composition accompanying the changes to membrane fluidity and CPT I sensitivity to malonyl-CoA. We conclude that CPT I kinetic characteristics are sensitive to changes in lipid composition that are localized to specific membrane microdomains.     

Levels of 12 perfluorinated chemicals in pooled australian serum, collected 2002-2003, in relation to age, gender, and region

Pooled serum samples from 3802 Australian residents were analyzed for four perfluoroalkylsulfonates, seven perfluoroalkylcarboxylates, and perfluorooctanesulfonamide (PFOSA). Serum was collected from men and women of five different age groups and from rural and urban regions in Australia. The highest mean concentration was obtained for perfluorooctane sulfonate (PFOS, 20.8 ng/mL) followed by perfluorooctanoic acid (PFOA, 7.6 ng/mL), perfluorohexane sulfonate (PFHxS, 6.2 ng/mL), perfluorononanoic acid (PFNA, 1.1 ng/mL), and PFOSA (0.71 ng/mL). Additional four PFCs were detected in 5-18% of the samples at concentrations near the detection limits (0.1-0.5 ng/mL). An increase in PFOS concentration with increasing age in both regions and genders was observed. The male pool levels of some of the age groups compared to females were higherfor PFOS, PFOA, and PFHxS. In contrast, PFNA concentrations were higher in the female pools. No substantial difference was found in levels of PFCs between the urban and rural regions. The levels are equal or higher than previously reported serum levels in Europe and Asia but lower compared to the U.S.A. These results suggest that emissions from production in the Northern Hemisphere are of less importance for human exposure.     

Growth of InGaN quantum dots with AlGaN barrier layers via modified droplet epitaxy

The growth of c-plane InGaN quantum dots via modified droplet epitaxy with AlGaN barrier layers is reported. The growth of the AlGaN layer underlying the InGaN quantum dot layer was carried out under H₂ at 1050 °C, while the capping AlGaN layer was grown at the same temperature (710 °C) and using the same carrier gas (N₂) as that used to grow the InGaN quantum dot layer to prevent decomposition of the InGaN. Atomic force microscopy of InGaN epilayers grown and annealed on high temperature AlGaN using identical growth conditions used for the quantum dot samples highlighted a narrower distribution of nanostructure heights than that obtained for similar growth on GaN. Scanning transmission electron microscopy (STEM) imaging combined with energy dispersive X-ray (EDX) analysis revealed the presence of a thin high aluminium content layer at the surface of both AlGaN layers, which is believed to be related to loss of Ga during temperature ramping processes. Micro-photoluminescence studies carried out at low temperature revealed near resolution-limited peaks while time-resolved measurements on these peaks demonstrated mono-exponential decay times between 1 and 4 ns, showing that quantum dots had successfully been formed between the AlGaN barriers. Temperature-dependant measurement of the emission lines revealed that quenching of the peak often occurred at ∼60–70 K, with some of the peaks exhibiting significant line broadening whilst others remained narrow.     

变革中的墓地景观：英国墓地设计与管理的新发展

1993年英国自然安葬的兴起以及英国政府提议的坟墓再利用计划将对基地景观产生深远影响。长久以来,很多墓地因缺乏资金而疏于养护,致使其价值被低估。自然安葬的迅速发展一方面是对人们越来越关心的英国墓地疏于养护问题作出的直接回应,另一方面也与英国众多城市可用于传统殡葬的土地日益减少有关。在自然安葬不断发展改进的时候,＂坟墓再利用＂计划的再次引入将有利于防止墓地成为荒废空间。通过当前英国谢菲尔德大学景观系和社会学系正在进行的墓地研究,阐述自然安葬和坟墓再利用的发展以及它们对墓地景观产生的影响。     

The mechanism of pleural inflammation by long carbon nanotubes: interaction of long fibres with macrophages stimulates them to amplify pro-inflammatory responses in mesothelial cells

Background

Little is known of how the toxicity of nanoparticles is affected by the incorporation in complex matrices. We compared the toxic effects of the titanium dioxide nanoparticle UV-Titan L181 (NanoTiO₂), pure or embedded in a paint matrix. We also compared the effects of the same paint with and without NanoTiO₂.

Methods

Mice received a single intratracheal instillation of 18, 54 and 162 μg of NanoTiO₂ or 54, 162 and 486 μg of the sanding dust from paint with and without NanoTiO₂. DNA damage in broncheoalveolar lavage cells and liver, lung inflammation and liver histology were evaluated 1, 3 and 28 days after intratracheal instillation. Printex 90 was included as positive control.

Results

There was no additive effect of adding NanoTiO₂ to paints: Therefore the toxicity of NanoTiO₂ was reduced by inclusion into a paint matrix. NanoTiO₂ induced inflammation in mice with severity similar to Printex 90. The inflammatory response of NanoTiO₂ and Printex 90 correlated with the instilled surface area. None of the materials, except of Printex 90, induced DNA damage in lung lining fluid cells. The highest dose of NanoTiO₂ caused DNA damage in hepatic tissue 1 day after intratracheal instillation. Exposure of mice to the dust from paints with and without TiO₂ was not associated with hepatic histopathological changes. Exposure to NanoTiO₂ or to Printex 90 caused slight histopathological changes in the liver in some of the mice at different time points.

Conclusions

Pulmonary inflammation and DNA damage and hepatic histopathology were not changed in mice instilled with sanding dust from NanoTiO₂ paint compared to paint without NanoTiO₂. However, pure NanoTiO₂ caused greater inflammation than NanoTiO₂ embedded in the paint matrix.     

Microbial quality assessment of household greywater

A monitoring program was undertaken to assess the microbial quality of greywater collected from 93 typical households in Melbourne, Australia. A total of 185 samples, comprising 75 washing machine wash, 74 washing machine rinse and 36 bathroom samples were analysed for the faecal indicator Escherichia coli. Of these, 104 were also analysed for genetic markers of pathogenic E coli and 111 for norovirus (genogroups GI and GII), enterovirus and rotavirus using RT-PCR. Enteric viruses were detected in 20 out of the 111 (18%) samples comprising 16 washing machine wash water and 4 bathroom samples. Eight (7%) samples were positive for enterovirus, twelve (11%) for norovirus genogroup GI, one (1%) for norovirus genogroup GII and another (1%) for rotavirus. Two washing machine samples contained more than one virus. Typical pathogenic E. coli were detected in 3 out of 104 (3%) samples and atypical enteropathogenic E. coli in 11 (11%) of samples. Levels of indicator E. coli were highly variable and the presence of E. coli was not associated with the presence of human enteric viruses in greywater. There was also little correlation between reported gastrointestinal illness in households and detection of pathogens in greywater.     

Evaluation of stable isotope tracing for ZnO nanomaterials--new constraints from high precision isotope analyses and modeling

This contribution evaluates two possible routes of stable isotope tracing for ZnO nanomaterials. For this we carried out the first high precision Zn isotope analyses of commercially available ZnO nanomaterials, to investigate whether such materials exhibit isotope fractionations that can be exploited for tracing purposes. These measurements revealed Zn isotopic compositions (of δ(66/64)Zn = +0.28 to -0.31‰ relative to JMC Lyon Zn) that are indistinguishable from "normal" natural and anthropogenic Zn in environmental samples. Stable isotope tracing therefore requires the application of purpose-made isotopically enriched ZnO nanoparticles. A detailed evaluation identified the most suitable and cost-effective labeling isotopes for different analytical requirements and techniques. It is shown that, using relatively inexpensive (68)Zn for labeling, ZnO nanoparticles can be reliably detected in natural samples with a Zn background of 100 μg/g at concentrations as low as about 5 ng/g, if the isotopic tracing analyses are carried out by high precision mass spectrometry. Stable isotope tracing may also be able to differentiate between the uptake by organisms of particulate ZnO and Zn(2+) ions from the dissolution of nanoparticles.     

Increased response/recovery lifetimes and reinforcement of polyaniline nanofiber films using carbon nanotubes

We have prepared high surface area, conductive, mechanically robust, responsive polyaniline–carbon nanotube composite films. These were produced by filtration from dilute dispersions of polyaniline nanofibers and single-walled carbon nanotubes. Unlike polyaniline alone, these composites are mechanically stable, maintain large intractable surfaces and exhibit greatly enhanced response/recovery behavior to changes in their local environment. This is illustrated by exposing the films to ammonia.