Assessment and quantification of marginal lands for biomass production in Europe using soil-quality indicators

The cultivation of bioenergy plants in fertile, arable lands increasingly results in new land use conflicts with food production and cannot be considered as sustainable. Marginal lands have been frequently considered as potential alternatives for producing bioenergy from biomass. However, clear definitions and assessment methods for selecting marginal lands and for calculating potentials are still widely missing. The project “SEEMLA” aims at triggering the exploitation of currently underused marginal lands for biomass production for energy purposes. Study sites have been selected in different European countries: Germany, Greece, and Ukraine. The selected sites represent a wide variety of different types of marginal lands. Based on a soil assessment set given by the Muencheberg Soil Quality Rating (SQR) system potentially “marginal” sites have been investigated. The SQR system allows for clearly distinguishing between soils of higher and lower quality. Soils with SQR scores below 40 are regarded as “marginal”. They can be classified into different groups with regard to the importance of soil hazard indicators as evaluated by the SQR approach. The calculated SQR scores correlate significantly with biomass yields of bioenergy plants. Further, the SQR method was adapted for use in a GIS study on marginal-land potentials in Europe. Thus, 46&thinsp;% of the investigated European area could be classified as “marginal” with SQR scores below 40. From that area 22.6&thinsp;% can be considered as potentially suitable for producing renewable resources after eliminating protected sites or other places not suitable for any kind of land use. Taking the ecological demands of selected bioenergy plants into account it is possible to give first preliminary recommendations for regional crop cultivation. It can be concluded that Europe offers a large potential for renewable resources from marginal sites. However, the implementation into practice is often impeded by missing or varying policies and regulations. A proper implementation needs clear regulations and also incentives for farmers at the European level.</p

hMYH and hMTH1 cooperate for survival in mismatch repair defective T-cell acute lymphoblastic leukemia

hMTH1 is an 8-oxodGTPase that prevents mis-incorporation of free oxidized nucleotides into genomic DNA. Base excision and mismatch repair pathways also restrict the accumulation of oxidized lesions in DNA by removing the mis-inserted 8-oxo-7,8-dihydro-2'-deoxyguanosines (8-oxodGs). In this study, we aimed to investigate the interplay between hMYH DNA glycosylase and hMTH1 for cancer cell survival by using mismatch repair defective T-cell acute lymphoblastic leukemia (T-ALL) cells. To this end, MYH and MTH1 were silenced individually or simultaneously using small hairpin RNAs. Increased sub-G1 population and apoptotic cells were observed upon concurrent depletion of both enzymes. Elevated cell death was consistent with cleaved caspase 3 accumulation in double knockdown cells. Importantly, overexpression of the nuclear isoform of hMYH could remove the G1 arrest and partially rescue the toxicity observed in hMTH1-depleted cells. In addition, expression profiles of human DNA glycosylases were generated using quantitative reverse transcriptase–PCR in MTH1 and/or MYH knockdown cells. NEIL1 DNA glycosylase, involved in repair of oxidized nucleosides, was found to be significantly downregulated as a cellular response to MTH1–MYH co-suppression. Overall, the results suggest that hMYH and hMTH1 functionally cooperate for effective repair and survival in mismatch repair defective T-ALL Jurkat A3 cells

Microcrystalline silicon films and solar cells deposited by PECVD and HWCVD

The application of microcrystalline silicon (muc-Si:H) in thin-film solar cells is addressed in the present paper. Results of different technologies for the preparation of pc-Si:H are presented, including plasma enhanced chemical vapour deposition (PECVD) using 13.56MHz (radio frequency, rf) and 94.7MHz (very high frequency, vhf) and hot-wire chemical vapour deposition (HWCVD). The influence of the silane concentration (SC) on the material and solar cell parameters is studied for the different techniques as the variation of SC allows to optimise the solar cell performance in each deposition regime. The best performance of pc-Si:H solar cells is always observed near the transition to amorphous growth. The highest efficiency obtained so far at a deposition rate of 5 Angstrom/s is 9.4%, achieved with rf-PECVD in a deposition regime of using high pressure and high discharge power. High deposition rates and solar cell efficiencies could be also achieved by vhf-PECVD. An alternative approach represents the HWCVD which also demonstrated high deposition rates for muc-Si:H. However, good material quality and solar cell performance could only be achieved at low substrate temperatures and, consequently, low deposition rates. The pc-Si:H solar cells prepared by HWCVD exhibit comparably high efficiencies up to 9.4% and exceptionally high open circuit voltages up to 600mV but at lower deposition rates (approximate to1 Angstrom/s). The properties of PECVD and HWCVD solar cells are carefully compared. (C) 2004 Elsevier Ltd. All rights reserved

A new concept for mass production of large area thin-film silicon solar cells on glass

Thin-film silicon solar cells with up to 11.2% stable cell efficiency have been developed on ZnO coated glass substrates on laboratory scale using solely plasma enhanced chemical vapour deposition (PECVD) and magnetron sputtering as deposition techniques for all thin films. To transfer this concept towards large areas, we developed a novel PECVD electrode which proved its capability of providing homogenous amorphous and microcrystalline silicon films on similar to 1 m(2) sized substrates. Microcrystalline silicon (mu c-Si:H) solar cells were realised with efficiencies up to 7.2%. The high open-circuit voltage V-oc and fill factor FF of 520 mV and 71%, respectively, demonstrate that high quality pc-Si:H material can be prepared with this large area electrode. Note that finally the entire thin-film structure-including all silicon, TCO and metal films-can be produced using one single equipment platform which complies with the requirements for a cost-effective and large scale mass production. (c) 2005 Elsevier B.V. All rights reserved