Long-wave infrared laser-induced breakdown spectroscopy of complex gas molecules in the vicinity of a laser-induced plasma.

Vibration-rotation signatures of intact water and complex organic molecules in vapor phase were detected, identified, and mode-assigned in the long-wave infrared emissions of laser-induced plasma. Time resolved long-wave infrared emissions were also studied to assess the temporal behaviors of these gaseous molecular emitters. The temperatures of these molecular vapors in the hot and transient vapor-plasma plume of the laser-induced plasma were estimated to be well above room temperatures during their existence. The temperatures of the water vapors in the vapor-plasma plume were found to be evolving with time and ranging from > 2700 K at 10 µs to âˆ¼ 1500 K at 200 µs after plasma initiations using HITRAN/HAPI based molecular spectral analysis. The observations in the present study comprise (to our knowledge) the first direct evidence of hot water and intact complex organic gas molecules in the vicinity of the laser-induced plasma. The findings presented in this work serve as an important step forward in improving the understanding of the thermodynamic characteristics (such as temperatures and phases) of intact complex molecules in a hot and intricate system such as the vapor-plasma plume of a laser-induced plasma, which is essential in both fundamental studies of plasmas and of laser-induced plasma based analytical applications.

Association between central obesity and risk for heart disease in adults in China: a prospective study / 中华流行病学杂志

Objective: To understand the association between central obesity, assessed by waist circumference, and the risks for ischemic heart disease (IHD), major coronary event (MCE), and IHD death. Methods: After excluding participants with heart disease, stroke, cancer, COPD, and diabetes at baseline survey, we included a total of 428 595 participants from the China Kadoorie Biobank for the analysis. The baseline survey was conducted from June 2004 to July 2008. We used Cox proportional hazards model to estimate the hazard ratio (HR) and 95%CI. Results: During an average 9.1 years of follow-up (3 803 637 person-years), we documented 26 900 incident cases of IHD, 4 320 cases of MCE, and 2 787 of deaths from IHD. After adjustment for possible confounders and BMI, central obesity was found to be associated with increased risks for IHD, MCE, and IHD death. The adjusted HRs (for the participants who had waist circumference of 85.0-89.9 cm in men and 80.0-84.9 cm in women were 1.13 (95%CI: 1.09-1.17) for IHD, 1.15 (95%CI: 1.05-1.26) for MCE and 1.11 (95%CI: 0.98-1.24) for IHD death. The respective HRs for those central obese participants (men ≥90.0 cm, women ≥85.0 cm) were 1.29 (95%CI: 1.24-1.34), 1.30 (95%CI: 1.17-1.44) and 1.32 (95%CI: 1.16-1.51). Further stratification analysis according to BMI showed that the risks for incident IHD, MCE, and IHD death increased along with the increase of waist circumference even in the participants with normal weight. Conclusion: This large-scale prospective study revealed that central obesity was an independent risk factor for IHD in adults in China, and the risk of IHD would increase with the increase of waist circumference.

Mid infrared emission spectroscopy of carbon plasma.

Mid infrared time-resolved emission spectra were recorded from laser-induced carbon plasma. These spectra constitute the first study of carbon materials LIB spectroscopy in the mid infrared range. The carbon plasma was induced using a Q-switched Nd: YAG laser. The laser beam was focused to high purity graphite pellets mounted on a translation stage. Mid infrared emission from the plasma in an atmospheric pressure background gas was detected by a cooled HgCdTe detector in the range 4.4-11.6µm, using long-pass filters. LIB spectra were taken in argon, helium and also in air. Despite a gate delay of 10µs was used there were strong backgrounds in the spectra. Superimposed on this background broad and noisy emission bands were observed, the form and position of which depended somewhat on the ambient gas. The spectra were digitally smoothed and background corrected. In argon, for instance, strong bands were observed around 4.8, 6.0 and 7.5µm. Using atomic spectral data by NIST it could be concluded that carbon, argon, helium and nitrogen lines from neutral and ionized atoms are very weak in this spectral region. The width of the infrared bands supports molecular origin. The infrared emission bands were thus compared to vibrational features of carbon molecules (excluding C2) of various sizes on the basis of previous carbon cluster infrared absorption and emission spectroscopic analyses in the literature and quantum chemical calculations. Some general considerations are given about the present results.