On-nanowire spatial band gap design for white light emission.

This is the accepted manuscript. The final version is available from ACS at http://pubs.acs.org/doi/abs/10.1021/nl203529h.We demonstrated a substrate-moving vapor-liquid-solid (VLS) route for growing composition gradient ZnCdSSe alloy nanowires. Relying on temperature-selected composition deposition along their lengths, single tricolor ZnCdSSe alloy nanowires with engineerable band gap covering the entire visible range were obtained. The photometric property of these tricolor nanowires, which was determined by blue-, green-, and red-color emission intensities, can be in turn controlled by their corresponding emission lengths. More particularly, under carefully selected growth conditions, on-nanowire white light emission has been achieved. Band-gap-engineered semiconductor alloy nanowires demonstrated here may find applications in broad band light absorption and emission devices

Franck-Condon Factors and Radiative Lifetime of the A^{2}\Pi_{1/2} - X^{2}\Sigma^{+} Transition of Ytterbium Monoflouride, YbF

The fluorescence spectrum resulting from laser excitation of the A^{2}\Pi_{1/2} - X^{2}\Sigma^{+} (0,0) band of ytterbium monofluoride, YbF, has been recorded and analyzed to determine the Franck-Condon factors. The measured values are compared with those predicted from Rydberg-Klein-Rees (RKR) potential energy curves. From the fluorescence decay curve the radiative lifetime of the A^{2}\Pi_{1/2} state is measured to be 28\pm2 ns, and the corresponding transition dipole moment is 4.39\pm0.16 D. The implications for laser cooling YbF are discussed.Comment: 5 pages, 5 figure

Relationship between occupational stress and job burnout among rural-to-urban migrant workers in Dongguan, China: a cross-sectional study

Objectives: In China, there have been an increasing number of migrant workers from rural to urban areas, and migrant workers have the highest incidence of occupational diseases. However, few studies have examined the impact of occupational stress on job burnout in these migrant workers. This study aimed to investigate the relationship between occupational stress and job burnout among migrant workers. Design: This study used a cross-sectional survey. Setting: This investigation was conducted in Dongguan city, Guangdong Province, China. Participants: 3806 migrant workers, aged 18–60 years, were randomly selected using multistage sampling procedures. Primary and secondary outcome measures: Multistage sampling procedures were used to examine demographic characteristics, behaviour customs and jobrelated data. Hierarchical linear regression and logistic regression models were constructed to explore the relationship between occupational stress and burnout. Results: Demographics, behaviour customs and jobrelated characteristics significantly affected on burnout. After adjusting for the control variable, a high level of emotional exhaustion was associated with high role overload, high role insufficiency, high role boundary, high physical environment, high psychological strain, high physical strain, low role ambiguity, low responsibility and low vocational strain. A high level of depersonalisation was associated with high role overload, high role ambiguity, high role boundary, high interpersonal strain, high recreation, low physical environment and low social support. A low level of personal accomplishment was associated with high role boundary, high role insufficiency, low responsibility, low social support, low physical environment, low self-care and low interpersonal strain. Compared to the personal resources, the job strain and personal strain were more likely to explain the burnout of rural-to-urban migrant workers in our study. Conclusions: The migrant workers have increased job burnouts in relation to occupational stress. Relieving occupational stress and maintaining an appropriate quantity and quality of work could be important measures for preventing job burnout among these workers

Model Study on the Transport and Mixing of Dust Aerosols and Pollutants during an Asian Dust Storm in March 2002

The transport and mixing of dust aerosols and pollutants in East Asia during March 18 to 22, 2002 was studied using the nested air quality prediction model system (NAQPMS). Dust was primarily generated in the Gobi desert on 19 March and then swept across several areas of East Asia. The model results were verified with observations of surface weather, TSP/PM10, SO2 and lidar data. The model simulated the right timing and strength of dust events, capturing most of the variation features in dust and SO2. Numerical results showed that the dust aerosols were mainly transported in two layers and mixed with pollutants in different ways. Some of the dust kicked up in the source region was uplifted to a higher layer (200 - 2000 m layer) and transported downwind faster than dust of the lower level. This lower-level dust was of greater concentration. The dust arriving at the upper layer began to drop and mixed well with pollutants in the atmosphere during ¡§the first period¡¨. During ¡§the second period¡¨, pollutants were diluted by the dust air mass that was transported along the lower layer. The remaining pollutants mixed well with dust aerosols during this period. The mixed air mass of the higher layer (1500 m) eventually reached the Northwestern Pacific. A large amount of clouds in the upper layers potentially led to an increase in sulfate mass on the surface of dust particles

ANALYSIS OF THE MAGNETIC HYPERFINE STRUCTURE IN THE B3B^{3}Φ4−X3Φ4\Phi_{4}-X^{3}\Phi_{4} BAND SYSTEM OF IRIDIUM MONOFLUORIDE, IrF

A.G. Adam; A.D. Granger; L.E. Downie; D.W. Tokaryk and C. Linton \textit {Can.J. Phys.R. Li, R.J. Jensen, W.J. Balfour, S.A. Shepard and A.G. Adam; \textit {J.Chem.Phys.J.J. Harrison, J.M. Brown, M.A. Flory, P.M. Sheridan, S.K. McLamarrah and L.M. Ziurys \textit {J. Chem. Phys.Author Institution: Department of Chemistry and Biochemistry, Arizona State University, Tempe,AZ 85287; Center for Lasers, Atomic and Molecular Sciences and Physics Department, University of New Brunswick, Fredericton, NB Canada E3B 5A3Recently the New Brunswick group (accepted).} reported on the detection and analysis of the $B^{3}$$\Phi_{4}-X^{3}\Phi_{4}$ band system of IrF. The free-jet expansion conditions limited the spectral resolution to approximately 200 MHz, which was insufficient to fully resolve the $^{191}$Ir(I=3/2), $^{193}$Ir(I=3/2)and $^{19}$F(I=1/2)magnetic hyperfine splitting. Here we report on the analysis of the same band system recorded under molecular beam conditions which resulted in a resolution of 40 MHz. A simple molecular orbital correlation diagram is used to rationalize the determined parameters of IrF and the isovalent molecules RhF {\textbf{121}} 2591, 2004.} and CoF {\textbf{127}} 194308, 2007.}

Health risk assessment of nitrate pollution in shallow groundwater: a case study in Changchun New District, China

High concentrations of nitrate in groundwater pose a threat to human health. To quantify groundwater nitrate pollution in China's Changchun New District and evaluate its human health risks, 98 groundwater samples were collected and analyzed. The spatial distribution of groundwater chemical components was variable with concentrations descending from TDS > HCO3− > Ca2+ > NO3− > SO42- > Na+ > Cl− > Mg2+ > K+ > NO2− > NH4+. Notably, NO3− concentrations ranged from 0.02–492.72 mg/L and averaged 98.62 mg/L. Over 50% of samples exceeded the Quality Standard for Groundwater of China Class III N threshold (20 mg/L). Principal component analysis determined that NO3 contamination was primarily due to the excessive use of fertilizers in agriculture. A human health risk assessment model was used to assess the potential health risks of groundwater NO3− via drinking water and skin contact pathways. Approximately 90% of adults, 66% of children, and 45% of infants had acceptable health risks in the study area. NO3− exposure risk in the towns of Longjia and Xiyingcheng was the highest, while urban areas tended to have lower exposures. The health risks of residents, especially minors and infants, were concerned

THE VISBLE SPECTRUM OF TITANIUM DIOXIDE

Author Institution: Department of Chemistry and Biochemistry, Arizona State University, Tempe,AZ 85287; Department of Chemistry, University of Basel, Basel SwitzerlandBulk TiO$_{2}$ is a widely used photo-activated catalytic material, yet poorly understood. Much of the motivation for studies of molecular TiO$_{2}$ is the observation {\textbf{129}} 3022, 2007.} that there is a smooth correlation of the molecular electronic states to the band gap of the bulk. The field-free energy levels of the ground state of the monomer have been fully characterized by microwave spectroscopy. {\textbf{676}} 1367, 2008.} Here we report on the visible spectrum in the region between 18200 cm$^{-1}$ to 18750 cm$^{-1}$ of a cold molecular beam sample of TiO$_{2}$ using laser induced fluorescence detection and mass-selected REMPI. Bands at 18240 cm$^{-1}$, 18411 cm$^{-1}$ and 18470 cm$^{-1}$ were recorded at a resolution of 40 MHz and rotationally analyzed. The dispersed fluorescence of 18411 cm$^{-1}$ and 18470 cm$^{-1}$ bands were analyzed to produce a set of vibrational parameters for the ground state. The optical Stark spectra of the 18411 cm$^{-1}$ and 18470 cm$^{-1}$ bands were recorded and analyzed to determine permanent electric dipole moments and compared with the results for the band at 18655 cm$^{-1}$ {\textbf{11}} 2649, 2008.