Search

Abstract: We investigated the polymerization and decomposition of C60 solids by high-energy ion irradiation. Young''s modulus of the films showed a slight increase after irradiation with 15MeV C4+ ions at a dose of 1×1013 ioncm−2. Relaxation and lambda-shaped peaks were observed at approximately 135 and 250K, respectively, in the internal friction; these almost disappeared at a dose of 1×1015 ioncm−2. We concluded that the polymerization of C60 and the local destruction of the face-centered cubic (FCC) structure proceed concurrently on irradiation, and the structural phase transition at 250K is suppressed after irradiation with doses greater than 1×1015 ioncm−2. [Copyright &y& Elsevier]

Abstract: By means of Visual Basic.NET and as part of a series of CAL programs we developed a program “Mounting of Dental Radiographs”, the aim of which is to make dental students understand how to place dental radiographs in a logical order—a prerequisite for easy viewing and interpretation. The program is built up as a game where the student from a stack of randomly arranged dental radiographs has to first make certain that they do not have to be reversed or rotated and then drag-and-drop them in their correct positions. After having placed all radiographs–around 20–the mounting is checked by a “teacher”. If not correct the student has two more chances to try before “game over”. The reason we used Visual Basic.NET is that it is a very versatile tool permitting other users of the program to make their own modifications of it. [Copyright &y& Elsevier]

Number–size distributions of aerosol particles with diameters of 10–500 nm in the marine boundary layer were observed continually onboard the R/V Hakuho Maru over the equatorial and subtropical North Pacific and South Pacific during December 2011–March 2012. Number–size distributions over each area were parameterized using a sum of up to three lognormal functions. Bi-modal size distributions with peak diameters at 30–80 nm (Aitken mode) and 100–200 nm (accumulation mode) were observed frequently. Larger peak diameters of Aitken and accumulation modes were observed over the eastern equator, where 5-day backward trajectories showed that the air masses had derived from high-chlorophyll oceanic regions without precipitation. Smaller peak diameters and low concentrations were often observed over the North Pacific. The trajectories show that such air mass originated from oceanic regions with less chlorophyll, exhibiting high precipitation frequency. New particle formation (NPF) events have often been observed over the mid-latitude eastern South Pacific with a low condensation sink (CS) and some dimethyl sulfide, although none was observed over the equator, where CS was higher. The lesser CS condition at NPF events was mostly correlated with local precipitation or precipitation along the trajectories within 1 day. These results suggest that differences of the number–size distribution and occasions of NPF events among sea areas most closely accord with precipitation along the trajectories. [ABSTRACT FROM AUTHOR]

Abstract: Aerosols in the troposphere influence photolysis frequencies and hence the concentrations of chemical species. We used a three-dimensional regional chemical transport model (NAQPMS) coupled with an accurate radiative transfer model to examine the impacts of aerosols on summertime photochemistry in Central Eastern China (CEC) via changing photolysis frequencies. In addition to looking at changes in concentrations as previous studies have done, we examined the changes in ozone (O3) budgets and the uncertainties related to our estimations. The 1st–12th June 2006 was selected as the simulation period when high aerosol optical depth at 550nm (AOD550) and O3 were found. A comparison of measurements showed that the model was capable of reproducing the spatial and temporal variations in photolysis frequencies, ultraviolet (UV) radiation, AOD550, cloud optical depth, O3 and other chemical constitutes in CEC. Aerosols have important impacts on atmospheric oxidation capacity in CEC. On a regional scale, aerosols decreased the average O3→O (1D) photolysis frequency by 53%, 37% and 21% in the lower, middle and upper troposphere in CEC. The uncertainties of these estimations were 37%, 25% and 14%, respectively. Mean OH concentrations decreased by 51%, 40% and 24% in layers below 1km, 1–3km and 3–10km, with uncertainties of 39%, 28% and 9%, respectively. The changes in HO2 concentrations were smaller but significant. In contrast, NOx showed a significant increase at 0–1km and 1–3km in CEC, with magnitudes of 6% and 8%. The largest relative enhancement occurred in downwind regions below 1km. Summertime boundary layer O3 (below 1km and 1–3km) was reduced by 5% with a maximum of 9% in highly polluted regions. The reduced ozone production (P (O3)) was responsible for this reduction below 3km. [Copyright &y& Elsevier]