Measurements of microjoule-level, few-femtosecond ultraviolet dispersive-wave pulses generated in gas-filled hollow capillary fibers.

To the best of our knowledge, we demonstrate the first time-domain measurement of µJ-level, few-fs ultraviolet dispersive-wave (DW) pulses generated in gas-filled hollow capillary fibers (HCFs) in an atmosphere environment using several chirped mirrors. The pulse temporal profiles, measured using a self-diffraction frequency-resolved optical gating setup, exhibit full width at half maximum pulse widths of 9.6 fs at 384 nm and 9.4 fs at 430 nm, close to the Fourier-transform limits. Moreover, theoretical and experimental studies reveal the strong influences of driving pulse energy and HCF length on temporal width and shape of the measured DW pulses. The ultraviolet pulses obtained in an atmosphere environment with µJ-level pulse energy, few-fs pulse width, and broadband wavelength tunability are ready to be used in many applications.

Monitoring of Poyang lake water for sewage contamination using human enteric viruses as an indicator.

BACKGROUND: Recreational water contaminated with fecal pollution poses a great public health concern, as fecal waste may cause serious waterborne illnesses. Current recreational water standards using fecal indicator bacteria (FIB) have their limitations for human protection especially in developing countries such as China. METHODS: To explore the potential use of enteric viruses as a potential indicator of fecal contamination, four viruses: norovirus geno-groups I and II, enteroviruses, and adenoviruses were tested in this study using molecular detection methods and sensitive RT-PC developed in the University of Hawaii. Water samples were also tested for FIB in order to determine their association with enteric virus detection. RESULTS: All sample sites tested positive for four enteric viruses. Human enterovirus (58%) and adenovirus (67%) were more frequently detected from these six sites, followed by norovirus I (50%) and norovirus II (38%). Six sampling sites all met the level-I water quality of GB3838-2002 criteria in microbiological level, but they all tested positive for enteric viruses. CONCLUSION: These findings indicate the current sewage contamination of Poyang Lake and also support the essential need of additional indicator such as human enteric viruses for enhanced monitoring of water quality since the presence of enteric viruses does not always correlate with fecal bacterial indicator detection.