Quantitative sampling and analysis of trace elements in atmospheric aerosols: impactor characterization and Synchrotron-XRF mass calibration.

he presented work is partly funded by theSwiss Federal Roads Office (ASTRA), the Swiss Federal Office forthe Environment (BAFU) and a post-doc contract sponsored by theSpanish Ministry of Science and Innovation (MICINN). Parts ofthe work were performed at the Swiss Light Source, Paul ScherrerInstitut, Villigen, Switzerland.We thank Andreas Jaggi fortechnical support at the beamline X05DA. Portions of this researchwere carried out at the light source facility DORIS III at HASY-LAB/DESY. DESY is a member of the Helmholtz Association(HGF)

Source apportionment of size and time resolved trace elements and organic aerosols from an urban courtyard site in Switzerland

Time and size resolved data of trace elements were obtained from measurements with a rotating drum impactor (RDI) and subsequent X-ray fluorescence spectrometry. Trace elements can act as indicators for the identification of sources of particulate matter <10 μm (PM10) in ambient air. Receptor modeling was performed with positive matrix factorization (PMF) for trace element data from an urban background site in Zürich, Switzerland. Eight different sources were identified for the three examined size ranges (PM1-0.1, PM2.5-1 and PM 10-2.5): secondary sulfate, wood combustion, fire works, road traffic, mineral dust, de-icing salt, industrial and local anthropogenic activities. The major component was secondary sulfate for the smallest size range; the road traffic factor was found in all three size ranges. This trace element analysis is complemented with data from an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (AMS), assessing the PM1 fraction of organic aerosols. A separate PMF analysis revealed three factors related to three of the sources found with the RDI: oxygenated organic aerosol (OOA, related to inorganic secondary sulfate), hydrocarbon-like organic aerosol (HOA, related to road traffic) and biomass burning organic aerosol (BBOA), explaining 60 %, 22 % and 17 % of total measured organics, respectively. Since different compounds are used for the source classification, a higher percentage of the ambient PM10 mass concentration can be apportioned to sources by the combination of both methods. © 2011 Author(s)

Fungal chitinases: diversity, mechanistic properties and biotechnological potential

Chitin derivatives, chitosan and substituted chito-oligosaccharides have a wide spectrum of applications ranging from medicine to cosmetics and dietary supplements. With advancing knowledge about the substrate-binding properties of chitinases, enzyme-based production of these biotechnologically relevant sugars from biological resources is becoming increasingly interesting. Fungi have high numbers of glycoside hydrolase family 18 chitinases with different substrate-binding site architectures. As presented in this review, the large diversity of fungal chitinases is an interesting starting point for protein engineering. In this review, recent data about the architecture of the substrate-binding clefts of fungal chitinases, in connection with their hydrolytic and transglycolytic abilities, and the development of chitinase inhibitors are summarized. Furthermore, the biological functions of chitinases, chitin and chitosan utilization by fungi, and the effects of these aspects on biotechnological applications, including protein overexpression and autolysis during industrial processes, are discussed in this review

Quantitative analysis of heavy metals in automotive brake linings: A comparison between wet-chemistry based analysis and in-situ screening with a handheld X-ray fluorescence spectrometer

Two extraction procedures for ecologically relevant elements present in automotive brake linings (Sb, Bi, Pb, Cd, Cr (total), Co, Cu, Mo, Ni, Sr. V, Zn, Sn) were developed and validated, applying a high pressure asher (HPA-S) and microwave extraction, respectively. Both of these methods allowed for the quantitative analysis of the extracted elements by inductively coupled plasma optical emission spectrometry (ICP-OES). The results were compared to measurements using a handheld energy-dispersive X-ray fluorescence spectrometer (ED-XRF), being in discussion by regulating agencies as in-situ screening tool for brake pads. The comparison indicates that the handheld ED-XRF analysis is basically an efficient screening tool for a reliable assessment of trace metal contents in automotive brake pads with respect to legal standards. While a quantitative determination of elements like Cd, Co, Cr, Mn. Mo, Ni, Pb and Sb was achievable, other elements (V, Cu, Bi, Zn, Sn and Sr) could only be determined qualitatively due to the special matrix characteristics of brake pads

Decrease in VEGF expression induces intussusceptive vascular pruning

Diminution of VEGF level induces vascular tree regression by intussusceptive vascular pruning. This observation may allude to the mechanism underlying the "normalization" of tumor vasculature if treated with antiangiogenic drugs. The mechanism described here gives new insights into the understanding of the processes of vasculature regression and hence provides new and potentially viable targets for antiangiogenic and/or angio-modulating therapies during various pathological processes