University of Southern Denmark

About: University of Southern Denmark is a education organization based out in Odense, Syddanmark, Denmark. It is known for research contribution in the topics: Population & Randomized controlled trial. The organization has 11928 authors who have published 37918 publications receiving 1258559 citations. The organization is also known as: SDU.

Solid–liquid separation of animal slurry in theory and practice. A review

Abstract: Animal slurry contains plant nutrients that are essential for crop production. However, intensive livestock production may lead to a surplus of plant nutrients on farms and, as a consequence, discharge or emission to the environment. In order to ensure that the slurry applied to fields matches the nutrient requirements of the crops, techniques have been developed to reduce the nutrient content of slurry by means of separation. This review discusses the separation technologies used for animal slurry treatment and the physical and chemical processes involved in separation. These processes need to be understood before efficient, reliable and cheap separation technologies that take into account the actual properties of slurry and the likely end-use of the separation products can be developed. A simple separation efficiency expression can be used to assess the efficiency of slurry separation. It is indeed important to measure the amount and composition of the slurry before treatment, the dry-matter-rich fraction and the liquid fraction. The separation efficiency of mechanical separators for the removal of dry matter and phosphorus (P) is ranked as follows: centrifugation > sedimentation > non-pressurized filtration > pressurized filtration. In general, the separation of total N and NH + follows the same pattern, but the separation efficiency is lower than for dry matter and P. Treatment with a flocculant before separation improves separation efficiency significantly. Of the polyacrylamide polymers tested, high-molecular-weight, linear cationic polymers with a medium charge density (20-40 mol%) were found to be the most efficient flocculants. The best mechanical separation techniques for flocculated slurry are screens or filter belts. The separation efficiency of polyacrylamide-treated slurry can be improved by adding a multivalent ion to coagulate particles and for precipitation of phosphorus. Aluminium sulfate (Al2(SO4)3 )o r ferric chloride (FeCl 3) seem to be very efficient for improving the mechanical separators. Alternatively, the mineral struvite (MgNH4PO4) may be formed by changing the slurry characteristics, such as by the addition of magnesium (Mg) or by increasing the pH to 9. The struvite crystals are removed during solid-liquid separation. The products of the solid-liquid separation may be further treated by evaporation, membrane filtration or ammonia stripping in order to obtain the desired end-products; however, low-maintenance and/or cost-efficient operation of these post-treatments has not yet been demonstrated. The separation should be developed as a whole-system approach, paying attention to parameters such as the value of end-products, environmental consequences and economy.

Improved peptide identification in proteomics by two consecutive stages of mass spectrometric fragmentation

Abstract: MS-based proteomics usually involves the fragmentation of tryptic peptides (tandem MS or MS2) and their identification by searching protein sequence databases. In ion trap instruments fragments can be further fragmented and analyzed, a process termed MS/MS/MS or MS3. Here, we report that efficient ion capture in a linear ion trap leads to MS3 acquisition times and spectra quality similar to those for MS2 experiments with conventional 3D ion traps. Fragmentation of N- or C-terminal ions resulted in informative and low-background spectra, even at subfemtomol levels of peptide. Typically C-terminal ions are chosen for further fragmentation, and the MS3 spectrum greatly constrains the C-terminal amino acids of the peptide sequence. MS3 spectra allow resolution of ambiguities in identification, a crucial problem in proteomics. Because of the sensitivity and rapid scan rates of the linear ion trap, several MS3 spectra per peptide can be obtained even when sequencing very complex mixtures. We calculate the probability that an experimental MS3 spectrum originates from fragmentation of a given N- or C-terminal ion of a peptide under consideration. This MS3 identification score can be combined with the MS2 scores of the precursor peptide from existing search engines. When MS3 is performed on the linear ion trap–Fourier transform mass spectrometer combination, accurate peptide masses further increase confidence in peptide identification.

Nonlocal optical response in metallic nanostructures

Abstract: This review provides a broad overview of the studies and effects of nonlocal response in metallic nanostructures. In particular, we thoroughly present the nonlocal hydrodynamic model and the recently introduced generalized nonlocal optical response (GNOR) model. The influence of nonlocal response on plasmonic excitations is studied in key metallic geometries, such as spheres and dimers, and we derive new consequences due to the GNOR model. Finally, we propose several trajectories for future work on nonlocal response, including experimental setups that may unveil further effects of nonlocal response.