PIXE and ToF-SIMS analysis of streaker samplers filters

This paper presents methodological innovations introduced in the characterisation of urban aerosol collected in Italy in a recent campaign. Two complementary ion beam analysis (IBA) techniques were used to analyse Nuclepore filters used in continuous streaker samplers to collect airborne particles in four Italian towns. Na to Pb elemental concentrations were obtained by particle induced X-ray emission (PIXE), while time of flight secondary ion mass spectrometry (ToF-SIMS) produced, on the same samples, time trends for several elements and molecular fragments. In addition, light attenuation measurements were used as a tracer for black carbon. The data produced by these three techniques was merged into a unique data set to address the characterisation of particulate matter sources. Correlations between elemental concentration trends (PIXE) and relative trends for molecular fragments (ToF-SIMS) and black carbon (light attenuation) have been studied by cluster and principal component analysis

Ultrastructural Observations on Bacterial Invasion in Cementum and Radicular Dentin of Periodontally Diseased Human Teeth

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141124/1/jper0493.pd

Hydrogen-Based Activity Enhancement in Sediment Cultures and Intact Sediments

The potential for hydrogen gas to stimulate microbial respiratory activity in sediments was investigated. Cell elutions from Passaic River (NJ), San Diego Bay (CA), and Marine Harbor sediments were amended with hydrogen gas to evaluate its impact on microbial activity measured by intracellular reduction of 5-cyano-2,3-ditolyl tetrazolium chloride (CTC). The transferability of this approach to sediment slurries and static sediment columns was evaluated based on microbial activity enhancement in Marine Harbor sediments. Results indicate that microbial activity can be increased by a factor of 2–3 at a threshold hydrogen concentration range (0.5 to 1.5 μM). Terminal restriction fragment (T-RF) length polymorphism analysis indicated that the community response to hydrogen resulted in the emergence of previously recessive populations. The causal relationship between hydrogen amendment and an increase in CTC-active cells was most likely due to community structure shifts, as evidenced by the emergence of new T-RFs (19% of total) at hydrogen concentrations above 1.5 μM. No RF was dominant within this emergent group, and no chlororespirers were detected within this group, the latter probably due to the lack of enrichment of halogenated compounds. Nevertheless, the transferability of the observed relationship between hydrogen gas amendment and microbial activity to complex sediment samples suggests a promising remedial strategy for in place contaminated estuarine sediments.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63230/1/ees.2006.0078.pd