Micro Scale Analysis Of Fluid Flow And Diffusion In Coarse Grained Porous Media

Thesis (Ph.D.) University of Alaska Fairbanks, 2011X-ray computed tomography and finite element analysis were used to visualize the internal geometry of porous media and calculate the hydraulic conductivity and the diffusion of a dissolved species through the media. The results were compared to laboratory generated results. The calculated hydraulic conductivity showed good agreement with the laboratory results, over-predicting the laboratory results with only 12.5%. Comparison of the calculated results with the Kozeny-Carman equation showed that the Kozeny-Carman equation over-predicted the laboratory results between 62% and 740% depending on the formulation used. The tortuosity and specific surface area showed the highest correlation in predicting the difference between the Kozeny-Carman equation and the modeling results, while the porosity showed the greatest influence in determining the magnitude of the hydraulic conductivity as calculated by the Kozeny-Carman equation. The calculation of the diffusion of potassium iodide through ceramic disks and sandstone showed accurate prediction of the concentration in the receiving cell for the length of the experiment (35 days) for one of the ceramic disks and the sandstone. The other ceramic disk showed accurate prediction up to 20 days, after which it deviated. The results from the study indicate that the diffusional tortuosity and the hydrodynamic tortuosity differ in magnitude, and that they can not be used interchangeably, since (1) the ceramic disks showed the closest prediction to the laboratory results when the diffusional tortuosity is used, rather than the hydrodynamic tortuosity, and when it enters the equation to the first power; and (2) the sandstone showed the closest prediction to the laboratory results when the diffusional tortuosity is used, and when it enters the equation to the second power. Broadly speaking, the results from this study show that the micro scale analysis of porous media allows the accurate calculation of macro scale parameters

Auswirkungen von Energieholzstreifen auf Laufkäfer und Nacktschnecken ökologisch bewirtschafteter Ackerflächen

Short rotation alley cropping can affect biodiversity and ecosystem services. Thus the epigeic fauna was investigated in different distances from a strip with short rotation poplar cultivation at two sites in Bavaria. An increase of carabid beetle diversity on field-scale was noted due to the appearance of adapted carabid species inside the strip, however with no distinct correlation between distance from poplar strip and carabid species diversity. Slug activity density decreased with increasing distance

Molecular watchdogs on genome patrol

By removing various obstacles from single strands of DNA, an enzyme called Pif1 clears the way for other enzymes that act on DNA

Auswirkungen von ökologisch bewirtschafteten Agroforstsystemen auf Regenwürmer

The earthworm fauna was investigated in 2011, 2013 und 2015 on two organically managed fields of agroforestry systems in Bavaria with poplar strips established in 2009. The abundance and biomass of earthworms in the field surrounding the poplar strip were more affected by different agricultural management measures and weather conditions than by the poplar strip itself. At one site the abundance of endogeic species in the soil of the poplar strip increased while the total biomass and the abundance of Lumbricus species (almost exclusively the anecic species Lumbricus terrestris) decreased. In addition, at the same site in 2015 a lower total earthworm biomass was detected up to 10 m into the adjacent field, due to a low abundance of Lumbricus species. Therefrom varying results were obtained at the other site, collecting a higher earthworm biomass inside the poplar strip during the investigation period of one year. Influences of specific local characteristics, weather conditions, soil tillage intensity, crop rotation and predators are discussed

Mitochondrial heat shock protein 70, a molecular chaperone for proteins encoded by mitochondrial DNA

Mitochondrial heat shock protein 70 (mt-Hsp70) has been shown to play an important role in facilitating import into, as well as folding and assembly of nuclear-encoded proteins in the mitochondrial matrix. Here, we describe a role for mt-Hsp70 in chaperoning proteins encoded by mitochondrial DNA and synthesized within mitochondria. The availability of mt-Hsp70 function influences the pattern of proteins synthesized in mitochondria of yeast both in vivo and in vitro. In particular, we show that mt-Hsp70 acts in maintaining the var1 protein, the only mitochondrially encoded subunit of mitochondrial ribosomes, in an assembly competent state, especially under heat stress conditions. Furthermore, mt-Hsp70 helps to facilitate assembly of mitochondrially encoded subunits of the ATP synthase complex. By interacting with the ATP-ase 9 oligomer, mt-Hsp70 promotes assembly of ATP-ase 6, and thereby protects the latter protein from proteolytic degradation. Thus mt-Hsp70 by acting as a chaperone for proteins encoded by the mitochondrial DNA, has a critical role in the assembly of supra- molecular complexes