A cyanophage capable of infecting Anabaena floaquae was isolated by traditional dilution and plating techniques from a eutrophicated freshwater lake, Dianchi Lake, in Yunnan Province, China, and designated as F1. Morphologically, cyanophage F1 is similar to the bacteriophage T4, and it should belong to Myoviridae. Cyanophage F1 could effectively lyses Anabaena flosaquae cells both on the cyanobacterium plates and in liquid cultures. In microcosm experiments, inoculation of cyanophage F1 could clear the artificial Anabaena flosaqua water blooms within three days. The results could provide important information on the cyanobacterial/phage interactions in the field, and suggested that cyanophage F1 could be a promising bio-control agent in the control of cyanobacterial blooms.
Through nanomanipulation inside scanning electron microscope, a carbon nanotube scanning probe microscope tip was made by connecting a carbon nanotube with a silicon atomic force microscope tip. The carbon nanotube scanning probe microscope tip was then tailored to the desired length and end structure by a "nanoknife," which is a carbon nanotube adhered to a metal tip. Through mapping the same carbon nanotube on SiO(2) substrate, it was found that the lateral resolution of the carbon nanotube tips can be improved significantly through sharpening the tip ends, and the sharpened carbon nanotube tips had better performance than commercial silicon tips.
CdS nanowire (NW) ring cavities were fabricated and studied for the first time. The rings with radii from 2.1 to 5.9 mu m were fabricated by a nanoprobe system installed in a scanning electron microscope. Radius dependent whispering gallery modes (WGMs) were observed. A straight CdS NW with Fabry-Perot (F-P) cavity structure was fabricated and placed by the side of a NW ring cavity to form 6 coupled ring-F-P cavity. When the NW ring was excited by a focused laser, a bright green light spot was observed at the output end of the straight NW, indicating that the latter had served as an effect waveguide to couple the light out from the ring cavity. The corresponding light spectrum showed that the WGMs had been modulated. We confirmed that the NW F-P cavity had served as a modulator. Such a coupled cavity has potential application in a nanophotonic system.
The chemical composition of secondary organic aerosol (SOA) particles, formed by the dark ozonolysis of alpha-pinene, was characterized by a high-resolution time-of-flight aerosol mass spectrometer. The experiments were conducted using a continuous-flow chamber, allowing the particle mass loading and chemical composition to be maintained for several days. The organic portion of the particle mass loading was varied from 0.5 to >140 mu g/m(3) by adjusting the concentration of reacted alpha-pinene from 0.9 to 91.1 ppbv. The mass spectra of the organic material changed with loading. For loadings below 5 mu g/m(3) the unit-mass-resolution m/z 44 (CO2+) signal intensity exceeded that of m/z 43 ( predominantly C2H3O+), suggesting more oxygenated organic material at lower loadings. The composition varied more for lower loadings (0.5 to 15 mu g/m(3)) compared to higher loadings (15 to >140 mu g/m(3)). The high-resolution mass spectra showed that from >140 to 0.5 mu g/m(3) the mass percentage of fragments containing carbon and oxygen (CxHyOz+) monotonically increased from 48% to 54%. Correspondingly, the mass percentage of fragments representing CxHy+ decreased from 52% to 46%, and the atomic oxygen-to-carbon ratio increased from 0.29 to 0.45. The atomic ratios were accurately parameterized by a four-product basis set of decadal volatility (viz. 0.1, 1.0, 10, 100 mu g/m(3)) employing products having empirical formulas of C1H1.32O0.48, C1H1.36O0.39, C1H1.57O0.24, and C1H1.76O0.14. These findings suggest considerable caution is warranted in the extrapolation of laboratory results that were obtained under conditions of relatively high loading (i.e., >15 mu g/m(3)) to modeling applications relevant to the atmosphere, for which loadings of 0.1 to 20 mu g/m(3) are typical. For the lowest loadings, the particle mass spectra resembled observations reported in the literature for some atmospheric particles.