Ship-borne aerosol profiling with lidar over the Atlantic Ocean: from pure marine conditions to complex dust–smoke mixtures

The multi-wavelength Raman lidar PollyXT has been regularly operated aboard the research vessel Polarstern on expeditions across the Atlantic Ocean from north to south and vice versa. The lidar measurements of the RV Polarstern cruises PS95 from Bremerhaven, Germany, to Cape Town, Republic of South Africa (November 2015), and PS98 from Punta Arenas, Chile, to Bremerhaven, Germany (April/May 2016), are presented and analysed in detail. The latest set-up of PollyXT allows improved coverage of the marine boundary layer (MBL) due to an additional near-range receiver.Three case studies provide an overview of the aerosol detected over the Atlantic Ocean. In the first case, marine conditions were observed near South Africa on the autumn cruise PS95. Values of optical properties (depolarisation ratios close to zero, lidar ratios of 23 sr at 355 and 532 nm) within the MBL indicate pure marine aerosol. A layer of dried marine aerosol, indicated by an increase of the particle depolarisation ratio to about 10 % at 355 nm (9 % at 532 nm) and thus confirming the non-sphericity of these particles, could be detected on top of the MBL. On the same cruise, an almost pure Saharan dust plume was observed near the Canary Islands, presented in the second case. The third case deals with several layers of Saharan dust partly mixed with biomass-burning smoke measured on PS98 near the Cabo Verde islands. While the MBL was partly mixed with dust in the pure Saharan dust case, an almost marine MBL was observed in the third case.A statistical analysis showed latitudinal differences in the optical properties within the MBL, caused by the down-mixing of dust in the tropics and anthropogenic influences in the northern latitudes, whereas the optical properties of the MBL in the Southern Hemisphere correlate with typical marine values. The particle depolarisation ratio of dried marine layers ranged between 4 and 9 % at 532 nm.Night measurements from PS95 and PS98 were used to illustrate the potential of aerosol classification using lidar ratio, particle depolarisation ratio at 355 and 532 nm, and Ångström exponent. Lidar ratio and particle depolarisation ratio have been found to be the main indicator for particle type, whereas the Ångström exponent is rather variable.</p

Constrictive tuberculous pericarditis in a HIV-positive patient

Constrictive pericarditis is a relatively rare clinical manifestation nowadays. We present the case of an HIV-positive patient with constrictive calcified pericarditis due to an infection with Mycobacterium tuberculosis. Pericardectomie was performed. The therapeutical approach is discussed and the literature is reviewe

Fission product behavior in the Molten Salt Reactor Experiment

Essentially all the fission product data for numerous and varied samples taken during operation of the Molten Salt Reactor Experiment or as part of the examination of specimens removed after particular phases of operation are reported, together with the appropriate inventory or other basis of comparison, and relevant reactor parameters and conditions. Fission product behavior fell into distinct chemical groups. Evidence for fission product behavior during operation over a period of 26 months with $sup 235$U fuel (more than 9000 effective full-power hours) was consistent with behavior during operation using $sup 233$U fuel over a period of about 15 months (more than 5100 effective full- power hours). (auth

Assembly induced delaminations in composite structures

Experimental and analytical studies of the development of delaminations around fastener holes in composite structures are presented. This type of delamination is known to occur in composite skins that are mechanically fastened to a poorly mating substructure. Results of an experimental study to determine the resistance of laminates to the initiation of assembly induced delaminations and the residual strength of assembly damaged coupons are presented for AS4/3501-6, IM7/8551-7A, and AS4/PEEK material systems. A survey of existing analytical models for predicting the residual strength and stability of delaminations is presented, and the development of a new model for predicting the initiation of delaminations around a fastener hole is outlined. The fastener hole damage initiation model utilizes a finite element based Fourier series solution, and is validated through comparisons of analytical and experimental results

Effects of Thermal Spiking on Graphite-Epoxy Composites

Tests were performed evaluating the effects of thermal spikes on the moisture absorption characteristics, the ultimate tensile strength, and the buckling modulus of Thornel 300/Fiberite 1034 composites. Measurements were made on unidirectional and π/4 laminates, using different types of thermal spikes. A survey was also made of the existing data. This survey, together with the present data indicate how thermal spikes affect the mois ture absorption and the mechanical properties of different graphite-epoxy composites.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66923/2/10.1177_002199837901300102.pd

Prenylated p-Hydroxyacetophenone Derivatives from the Giant Senecio johnstonii

The extract of the aerial parts of S. johnstonii afforded five known prenylated p-hydroxyacetophenone derivatives, scopoletin and 5-pentadecyl resorcinol together with the tridecyl derivative. The chemotaxonomic situation is discussed briefly.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28519/1/0000316.pd

Moisture Absorption of Graphite-Epoxy Composites Immersed in Liquids and in Humid Air

Moisture absorption of graphite-epoxy composites immersed in liquids and in himid air were investigated. The moisture content as a function of time and temperature was measured for three materials: Fiberite T300/1034, Hercules AS/3501-5 and Narmco T300/5208. Tests were per formed a) with the materials immersed in No. 2 diesel fuel, in jet A fuel, in aviation oil, in saturated salt water, and in distilled water (in the range of 300 to 322 K) and b)with the materials exposed to humid air (in the range 322 to 366 K). The results obtained were compared to available composite and neat resin data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68153/2/10.1177_002199837901300205.pd

Continuous vertical aerosol profiling with a multi-wavelength Raman polarization lidar over the Pearl River Delta, China

A dataset of particle optical properties of the highly polluted atmosphere over the Pearl River Delta (PRD), Guangzhou, China, is presented in this paper. The data were derived from the measurements of a multi-wavelength Raman and depolarization lidar PollyXT and a co-located AERONET sun photometer. The measurement campaign was conducted from November 2011 to mid-June 2012. These are the first Raman lidar measurements in the PRD that lasted for several months. A mean value of aerosol optical depth (AOD) of 0.54 ± 0.33 was observed by the sun photometer at 500 nm in the polluted atmosphere over this megacity for the whole measurement period. The lidar profiles frequently show lofted aerosol layers, which reach altitudes of up to 2 to 3 km and, especially during the spring season, up to 5 km. These layers contain between 12 and 56 % of the total AOD, with the highest values in spring. The aerosol types in these lofted layers are classified by their optical properties. The observed lidar ratio values range from 30 to 80 sr with a mean value of 48.0 ± 10.7 sr at 532 nm. The linear particle depolarization ratio at 532 nm lies mostly below 5 %, with a mean value of 3.6 ± 3.7 %. The majority of the Ångström exponents lie between 0.5 and 1.5, indicating a mixture of fine- and coarse-mode aerosols. These results reveal that mostly urban pollution particles mixed with particles produced from biomass and industrial burning are present in the atmosphere above the Pearl River Delta. Trajectory analyses show that these pollution mixtures arise mainly from local and regional sources