Absorption and emission cross sections of Er(3+) in Al(2)O(3) waveguides

Al(2)O(3) slab waveguide films were doped with erbium using ion implantation to a peak concentration of 1.5 at. %. Prism coupling measurements show absorption caused by (4)I (15/2) ?(4)I (13/2) intra-4f transitions in Er(3+) with a maximum at 1.530 mum of 8 dB/cm. The Er(3+) absorption cross section is determined as a function of wavelength. We used the McCumber theory to derive the emission cross section spectrum from the absorption results, which we then compared with the Er(3+) photoluminescence spectrum. The peak absorption and emission cross sections are found to be 6 x 10(-21) cm(-2). The results are used to predict the optical gain performance of an Er-doped Al(2)O(3) optical amplifier that operates around 1.5 mum.     

Soil Microvariation as a Source of Variability in the Wild: The Case of Secondary Metabolism in <Emphasis Type="Italic">Origanum dayi</Emphasis> Post

The volatile components of Origanum dayi Post were analyzed in 10 wild populations grown in a limited area. ANOVA tests showed no significant differences among the compositions of plants that grew in different locations, which suggests that differences in composition are of genetic origin and do not spring from environmental variation. However, the use of new statistical methods (such as use of the correlation coefficient, r, as a parametric value) revealed that, despite their reduced range of variation, most of the 22 soil properties (SPs) measured correlated with the composition of the volatile components. This analysis also indicated that the main volatile components were modified in parallel in response to SP variations. It is concluded that variations in soil properties affected the composition of volatile components in O. dayi, and that the main influencing factors were soil microelement contents and texture. This study highlights the need for highly sensitive statistical tools to determine the actual influence of environmental factors in natural environments, especially when their range of variation is small.     

A comparison of organic contaminants in two high Arctic lake ecosystems, Bjørnøya (Bear Island), Norway

Persistent methyl sulfone (MeSO2-) and hydroxylated (HO-) polychlorinated biphenyl (PCB) metabolites have emerged as important classes of environmental contaminants in vertebrate, aquatic biota and humans. In the present study, PCB, MeSO2-PCB and HO-PCB concentrations and congener patterns were determined in the whole blood and adipose tissue of male (n = 7) and female (n = 12) polar bears (Ursus maritimus) of random age (3-25 years of age), and collected in 1999-2001 from the Ittoqqortoormiit/Scoresby Sound area in central East Greenland. There was no significant difference (P < 0.05) between males and females with respect to PCB or PCB metabolite concentrations in either tissue. The mean sum (Sigma) PCB concentrations were 7020+/-3366 ng/g lipid weight (lw) (range 2708-18148 ng/g lw) and 46.1+/-44.6 ng/g wet weight (ww) (range 12.6-204.2 ng/g ww) in adipose and blood, respectively. The mean Sigma-HO-PCB concentration in whole blood was 182.3+/-72.1 ng/g ww (range 93.8-382.1 ng/g ww). The mean Sigma-HO-PCB to Sigma-PCB concentration ratios in whole blood were 4.59+/-3.58 (range 1.03-11.88) and 8.30+/-5.56 (range 2.16-19.47) in females and males, respectively, which are the highest ratios reported so far for polar bears from any population, or for any free-ranging animal. Sigma-HO-PCB concentrations were greater than all other major classes of organochlorines (i.e. Sigma-PCBs, Sigma-MeSO2-PCBs, Sigma-chlordanes (CHLs), Sigma-hexachlorocyclohexanes (HCHs) and Sigma-chlorobenzenes (CBzs). The mean Sigma-MeSO2-PCB concentrations were 699+/-836 ng/g lw (range 127-3920 ng/g lw) and 10.9+/-9.6 ng/g ww (range 4.3-52.1 ng/g ww) in the adipose and blood, respectively. Regardless of age and sex, in both adipose and whole blood the MeSO2-PCB congener pattern was dominated by 3'- and 4'-MeSO2-CB101 and -CB87, and 4-MeSO2-CB149 (approx. 70% of the Sigma-MeSO2-PCBs). Minor differences in the MeSO2-PCB congener pattern were observed between blood and adipose, which suggests the possible influence of metabolite structure on mobilization and/or deposition to the adipose tissue. Sixteen HO-PCB congeners and one di-HO-PCB congener were identified, and five HO-PCB isomers and one di-HO-PCB isomer were detected. However, congener patterns were dominated by 4'-OH-CB120, 4-HO-CB146/3-HO-CB153, 4-OH-CB187, 4'-HO-CB172, 4-HO-CB193 and 4,4'-di-HO-CB202 (> 10 ng/g ww). HO-PCB congener patterns in whole blood were not significantly different (P < 0.05) between males and females. Other chlorinated phenolic contaminants, pentachlorophenol (0.3+/-0.3 ng/g ww) and 4-HO-heptachlorostyrene (7.5+/-2.9 ng/g ww) were also detected in blood. To our knowledge, this is to first report comparing PCBs, MeSO2-PCBs and HO-PCBs in whole blood and adipose tissue in a free-ranging wildlife species. HO-PCBs and MeSO2-PCBs are both important circulating contaminants in polar bears from this eastern Greenland population. Given the known toxicities of PCB metabolites, this population of polar bear may be experiencing health risks due to exposure to a complex loading of organohalogen contaminants that include HO-PCB and MeSO2-PCB metabolites.     

A methodology for estimating airborne virus exposures in indoor environments using the spatial distribution of expiratory aerosols and virus viability characteristics

This study investigated the feasibility of using the spatial distribution of expiratory aerosols and the viability functions of airborne viruses to estimate exposures to airborne viruses in an indoor environment under imperfectly mixed condition. A method adopting this approach was tested in an air-conditioned hospital ward. Artificial coughs were produced by aerosolizing a simulated respiratory fluid containing a known concentration of benign bacteriophage. The bacteriophage exposures estimated on the basis of the spatial aerosol distributions and its viability function were in reasonable agreement with those measured directly by biological air sampling and culturing. The ventilation flow and coughing orientation were found to play significant roles in aerosol transport, leading to different spatial distribution patterns in bacteriophage exposure. Bacteriophage exposures decreased with lateral distance from the infector when the infector coughed vertically upward. In contrast, exposures were constant or even increased with distance in the case of lateral coughing. The possibility of incorporating the proposed exposure estimation into a dose-response model for infection risk assessment was discussed. The study has also demonstrated the potential application of viability functions of airborne viral pathogens in exposure assessment and infection risk analysis, which are often unavailable in literature for some important communicable diseases. PRACTICAL IMPLICATIONS: The proposed method makes use of the viability function of the virus and the spatial distribution of the expiratory aerosols for virus exposure estimation. Spatial differences in aerosol distribution and its influences on virus exposure in an air space can be determined. Variations in infectious dose with carrier aerosol size could also be considered. The proposed method may serve as a tool for further investigation of ventilation design and infection control in clinical or other indoor environments.     

Seabird guano is an efficient conveyer of persistent organic pollutants (POPs) to Arctic lake ecosystems

Migratory seabirds have been linked to localized "hotspots" of contamination in remote Arctic lakes. One of these lakes is Lake Ellasj?en on Bj?rn?ya in the Barents Sea. Here we provide quantitative evidence demonstrating that even relatively small populations of certain seabird species can lead to major impacts for ecosystems. In the present example, seabird guano accounts for approximately 14% of the contaminant inventory of the Lake Ellasj?en catchment area, approximately 80% of the contaminant inventory of the lake itself, and is approximately thirty times more efficient as a contaminant transport pathway compared to atmospheric long-range transport. We have further shown that this biological transport mechanism is an important contaminant exposure route for ecosystems, responsible for POPs levels in freshwater fish that are an order of magnitude higher than those in Arctic top predators. Given the worldwide presence of seabird colonies in coastal marine areas where resources are also harvested by humans, this biological transport pathway may be a greater source of dietary contamination than is currently recognized with consequent risks for human health.     

Revising the machine smoking regime for cigarette emissions: implications for tobacco control policy

Background

The WHO Framework Convenion on Tobacco Control includes provisions for testing and regulating cigarette emissions. However, the current international standard for generating cigarette emissions—the ISO machine smoking regime—is widely acknowledged to be inappropriate for purposes of setting regulatory restrictions.

Objective

To review alternatives to the ISO machine smoking regime and the extent to which they: 1) Represent human smoking behaviour, 2) Reduce the potential for industry exploitation, particularly in the area of risk communication, and 3) Serve as suitable measures for product regulation.

Methods

Emissions data from 238 Canadian cigarette brands tested under the ISO and “Canadian Intense” machine smoking regimes.

Results

None of the alternative smoking regimes, including the Canadian Intense method, are more “representative” of human smoking behaviour and none provide better predictors of human exposure.

Conclusions

Given that alternatives such as the Canadian Intense regime are subject to the same fundamental limitations as the ISO regime, key questions need to be addressed before any smoking regime should be used to set regulatory limits on smoke emissions. In the meantime, regulators should remove quantitative emission values from cigarette packages and more work should be done on alternative machine smoking methods.The issue of how to test and regulate conventional cigarettes represents a critical challenge for tobacco control. To date, the primary means of testing cigarette toxicity has been to machine smoke the cigarettes according to a standard puffing regime and to measure the chemical emissions in the mainstream smoke. In many jurisdictions, these cigarette “yields” are printed on packages and represent the only source of information on constituents or toxicity available to consumers. Cigarette emissions also serve as a regulatory standard in several of jurisdictions, including the European Union, where brands that generate emissions >10 mg of tar, 1 mg of nicotine or 10 ppm of carbon monoxide are prohibited. The puffing regime used to machine smoke the cigarettes—the International Organization for Standardization (ISO) regime¹—is widely recognised to be inadequate for the purposes of product regulation or consumer information. The ISO regime constitutes a set of puffing parameters that systematically underestimate smoking behaviour in humans.^2,3,4 Tobacco manufacturers have also designed cigarette brands to perform one way under the machine smoking conditions, but to deliver much greater smoke constituents to humans.^5,6 As a result, the emissions generated under the ISO smoking regime have little relationship with actual measures of human exposure, and exaggerate the differences between brands in a manner that has proved deceptive to both consumers and regulators.^7,8,9 Overall, the emissions from the ISO regime have served as more of an industry marketing tool to falsely reassure health‐concerned smokers, rather than as a valid measure of cigarette toxicity.^2,10,11,12There is a growing movement to develop a more meaningful machine testing method. The World Health Organization''s Framework Convention on Tobacco Control (FCTC)—the world''s first international public health treaty—includes provisions for testing and regulating cigarette emissions under Article 9.¹³ These provisions will need to be specified now that the FCTC has come into force. After discussions with the WHO, the ISO convened a working group (ISO TC 126 WG9) to develop recommendations for “…a robust and practical smoking regime that as far as possible is representative of smokers'' behaviour”. Meanwhile, the World Health Organization''s Study Group on Tobacco Product Regulations (WHO TobReg) has developed its own set of recommendations, which were under consideration by the ISO Working Group.¹⁴ There are also concerns that the ISO committee structure responsible for setting tobacco standards is dominated by the tobacco industry.¹²Before any new testing regime is implemented, it is critical to ensure that the new standards will serve the interests of public health rather than the tobacco industry. The purpose of this paper is to review the smoking regimes that are under consideration by the ISO Working Group, and to examine the implications for tobacco control policy and product regulation. In particular, we examine the extent to which the proposed regimes will: (1) succeed in “representing” smoking behaviour in humans and generate better predictors of human exposure; (2) reduce the potential for industry exploitation, particularly in the field of risk communication; and (3) help to establish more effective regulatory limits on cigarette toxicity.     

金川二矿区贫矿选矿工艺研究的讨论

金川二矿区贫矿选矿工艺研究已被列为国家“九五”科技攻关重点项目，组织九个单位共同攻关，选矿工艺有新的突破，获得良好的选矿效果。本文对提出的各种选矿方案进行分析讨论，将有助于今后科研工作的进展。     

General colorimetric detection of proteins and small molecules based on cyclic enzymatic signal amplification and hairpin aptamer probe

In this work, we developed a simple and general method for highly sensitive detection of proteins and small molecules based on cyclic enzymatic signal amplification (CESA) and hairpin aptamer probe. Our detection system consists of a hairpin aptamer probe, a linker DNA, two sets of DNA-modified AuNPs, and nicking endonuclease (NEase). In the absence of a target, the hairpin aptamer probe and linker DNA can stably coexist in solution. Then, the linker DNA can assemble two sets of DNA-modified AuNPs, inducing the aggregation of AuNPs. However, in the presence of a target, the hairpin structure of aptamer probe is opened upon interaction with the target to form an aptamer probe-target complex. Then, the probe-target complex can hybridize to the linker DNA. Upon formation of the duplex, the NEase recognizes specific nucleotide sequence and cleaves the linker DNA into two fragments. After nicking, the released probe-target complex can hybridize with another intact linker DNA and the cycle starts anew. The cleaved fragments of linker DNA are not able to assemble two sets of DNA-modified AuNPs, thus a red color of separated AuNPs can be observed. Taking advantage of the AuNPs-based sensing technique, we are able to assay the target simply by UV-vis spectroscopy and even by the naked eye. Herein, we can detect the human thrombin with a detection limit of 50 pM and adenosine triphosphate (ATP) with a detection limit of 100 nM by the naked eye. This sensitivity is about 3 orders of magnitude higher than that of traditional AuNPs-based methods without amplification. In addition, this method is general since there is no requirement of the NEase recognition site in the aptamer sequence. Furthermore, we proved that the proposed method is capable of detecting the target in complicated biological samples.     

Microemulsions as vehicles for topical administration of voriconazole: formulation and in vitro evaluation

This work was undertaken to investigate microemulsion (ME) as a topical delivery system for the poorly water-soluble voriconazole. Different ME components were selected for the preparation of plain ME systems with suitable rheological properties for topical use. Two permeation enhancers were incorporated, namely sodium deoxycholate or oleic acid. Drug-loaded MEs were evaluated for their physical appearance, pH, rheological properties and in vitro permeation studies using guinea pig skin. MEs based on polyoxyethylene(10)oleyl ether (Brij 97) as the surfactant showed pseudoplastic flow with thixotropic behavior and were loaded with voriconazole. Jojoba oil-based MEs successfully prolonged voriconazole release up to 4?h. No significant changes in physical or rheological properties were recorded on storage for 12 months at ambient conditions. The presence of permeation enhancers favored transdermal rather than dermal delivery. Sodium deoxycholate was more effective than oleic acid for enhancing the voriconazole permeation. Voriconazole-loaded MEs, with and without enhancers, showed significantly better antifungal activity against Candida albicans than voriconazole supersaturated solution. In conclusion, the studied ME formulae could be promising vehicles for topical delivery of voriconazole.     

Magnetic properties of (Fe50Co50)(1-x)-Gdx thin films with diluted Gd doping

(Fe50Co50)(1-x)-Gdx thin films (30 nm) with x<15% deposited on silicon substrates by magnetron sputtering were investigated by X-ray diffraction, vibrating sample magnetometer, and ferromagnetic resonance. Theoretical fittings of the angular dependent ferromagnetic resonance field of the FeCoGd films have been performed using the Landau-Lifshitz equation It is found that the ferromagnetic resonance experimental data is well fitted by the theory and various magnetic properties have been extracted in accordance. The saturation magnetization decreases from 22750 Oe at x = 0% to 14079 Oe at x = 14% in the FeCo-Gd film, and the perpendicular magnetic anisotropy has changed from an easy film plane to an easy film normal geometry. The gyromagnetic ratio, as well as the Landé g factor, are found increased also with increasing Gd content, i.e. from g = 2.08 at x = 0% to g = 2.29 at x = 14%. An enhancement of the L-S coupling in the presence of a low Gd content has been concluded based on an observable increase from 0.011 at x = 12% up to 0.015 at x = 14% in the Gilbert damping.