75 research outputs found
Von gelben Feldern zu GrĂŒner Chemie. Ăber die Selektive Desaktivierung bei der Oxidation von Glycerol zu Dihydroxyaceton an Platin-Bismut-Katalysatoren
Die Nutzung des nachwachsenden Rohstoffs Glycerol beschrĂ€nkt sich bislang auf seinen Einsatz in Kosmetika, Nahrungs- und Genussmitteln sowie Kunststoffen. Die Produktionsmenge ĂŒbersteigt den Bedarf jedoch deutlich. Die industrielle Herstellung von Folgeprodukten wĂ€re daher wĂŒnschenswert, zumal Chemikalien aus petrochemischen Grundstoffen ersetzt werden können. Insbesondere die in dieser Arbeit untersuchte selektive Oxidation des Glycerols kann die Herstellung des Produktes Dihydroxyaceton wirtschaftlich attraktiver machen. Dabei ist Dihydroxyaceton nicht nur als Aktivkomponente in Kosmetika interessant, denn die selektive Oxidation des Glycerols stellt bis heute eine wissenschaftliche Herausforderung dar. Die Probleme dieser Reaktion bestehen in der Desaktivierung des Katalysators, die zu einer Abnahme der SelektivitĂ€t mit fortschreitendem Reaktionsfortschritt fĂŒhrt. Durch deren Untersuchung und kinetische Modellierung konnte festgestellt werden, dass besonders die starke Adsorption von Nebenprodukten am Katalysator zur Katalysatordesaktivierung beitrĂ€gt. Es wurde ein kinetisches Modell unter BerĂŒcksichtigung zweier aktiver Zentren aufgestellt, auf dessen Basis eine Ausbeute von 70 % an Dihydroxyaceton vorausgesagt wird, wenn es gelingt, Nebenprodukte aus dem Reaktionsgemisch zu entfernen. Mit Hilfe von Membrantrennverfahren gelang es, Nebenprodukte annĂ€hernd quantitativ zu entfernen. Die AktivitĂ€t erhöhte sich und die Abnahme der SelektivitĂ€t zu Dihydroxyaceton konnte verringert werden. Bei DurchfĂŒhrung der Reaktion in einem kontinuierlichen Trickle-Bed-Reaktor konnten Ausbeuten von bis zu 60 % an Dihydroxyaceton erhalten werden, jedoch fĂŒhren hier weitere Desaktivierungsprozesse zu einer Abnahme der Ausbeute
The GRAVITY Coud\'e Infrared Adaptive Optics (CIAO) system for the VLT Interferometer
GRAVITY is a second generation instrument for the VLT Interferometer,
designed to enhance the near-infrared astrometric and spectro-imaging
capabilities of VLTI. Combining beams from four telescopes, GRAVITY will
provide an astrometric precision of order 10 micro-arcseconds, imaging
resolution of 4 milli-arcseconds, and low and medium resolution
spectro-interferometry, pushing its performance far beyond current infrared
interfero- metric capabilities. To maximise the performance of GRAVITY,
adaptive optics correction will be implemented at each of the VLT Unit
Telescopes to correct for the effects of atmospheric turbulence. To achieve
this, the GRAVITY project includes a development programme for four new
wavefront sensors (WFS) and NIR-optimized real time control system. These
devices will enable closed-loop adaptive correction at the four Unit Telescopes
in the range 1.4-2.4 {\mu}m. This is crucially important for an efficient
adaptive optics implementation in regions where optically bright references
sources are scarce, such as the Galactic Centre. We present here the design of
the GRAVITY wavefront sensors and give an overview of the expected adaptive
optics performance under typical observing conditions. Benefiting from newly
developed SELEX/ESO SAPHIRA electron avalanche photodiode (eAPD) detectors
providing fast readout with low noise in the near-infrared, the AO systems are
expected to achieve residual wavefront errors of \leq400 nm at an operating
frequency of 500 Hz.Comment: to be published in Proc. SPIE vol. 8446 (2012
An Equine Model for Vaccination against a Hepacivirus: Insights into Host Responses to E2 Recombinant Protein Vaccination and Subsequent Equine Hepacivirus Inoculation
Equine hepacivirus (EqHV) is the closest known genetic homologue of hepatitis C virus. An effective prophylactic vaccine is currently not available for either of these hepaciviruses. The equine as potential surrogate model for hepacivirus vaccine studies was investigated, while equine host responses following vaccination with EqHV E2 recombinant protein and subsequent EqHV inoculation were elucidated. Four ponies received prime and booster vaccinations (recombinant protein, adjuvant) four weeks apart (day â55 and â27). Two control ponies received adjuvant only. Ponies were inoculated with EqHV RNA-positive plasma on day 0. Blood samples and liver biopsies were collected over 26 weeks (day â70 to +112). Serum analyses included detection of EqHV RNA, isotypes of E2-specific immunoglobulin G (IgG), nonstructural protein 3-specific IgG, haematology, serum biochemistry, and metabolomics. Liver tissue analyses included EqHV RNA detection, RNA sequencing, histopathology, immunohistochemistry, and fluorescent in situ hybridization. Al-though vaccination did not result in complete protective immunity against experimental EqHV inoculation, the majority of vaccinated ponies cleared the serum EqHV RNA earlier than the control ponies. The majority of vaccinated ponies appeared to recover from the EqHV-associated liver insult earlier than the control ponies. The equine model shows promise as a surrogate model for future hepacivirus vaccine research
An Equine Model for Vaccination against a Hepacivirus: Insights into Host Responses to E2 Recombinant Protein Vaccination and Subsequent Equine Hepacivirus Inoculation
Equine hepacivirus (EqHV) is the closest known genetic homologue of hepatitis C virus. An effective prophylactic vaccine is currently not available for either of these hepaciviruses. The equine as potential surrogate model for hepacivirus vaccine studies was investigated, while equine host responses following vaccination with EqHV E2 recombinant protein and subsequent EqHV inoculation were elucidated. Four ponies received prime and booster vaccinations (recombinant protein, adjuvant) four weeks apart (day â55 and â27). Two control ponies received adjuvant only. Ponies were inoculated with EqHV RNA-positive plasma on day 0. Blood samples and liver biopsies were collected over 26 weeks (day â70 to +112). Serum analyses included detection of EqHV RNA, isotypes of E2-specific immunoglobulin G (IgG), nonstructural protein 3-specific IgG, haematology, serum biochemistry, and metabolomics. Liver tissue analyses included EqHV RNA detection, RNA sequencing, histopathology, immunohistochemistry, and fluorescent in situ hybridization. Al-though vaccination did not result in complete protective immunity against experimental EqHV inoculation, the majority of vaccinated ponies cleared the serum EqHV RNA earlier than the control ponies. The majority of vaccinated ponies appeared to recover from the EqHV-associated liver insult earlier than the control ponies. The equine model shows promise as a surrogate model for future hepacivirus vaccine research
A Seven-Marker Signature and Clinical Outcome in Malignant Melanoma: A Large-Scale Tissue-Microarray Study with Two Independent Patient Cohorts
Current staging methods such as tumor thickness, ulceration and invasion of the sentinel node are known to be prognostic parameters in patients with malignant melanoma (MM). However, predictive molecular marker profiles for risk stratification and therapy optimization are not yet available for routine clinical assessment.; Using tissue microarrays, we retrospectively analyzed samples from 364 patients with primary MM. We investigated a panel of 70 immunohistochemical (IHC) antibodies for cell cycle, apoptosis, DNA mismatch repair, differentiation, proliferation, cell adhesion, signaling and metabolism. A marker selection procedure based on univariate Cox regression and multiple testing correction was employed to correlate the IHC expression data with the clinical follow-up (overall and recurrence-free survival). The model was thoroughly evaluated with two different cross validation experiments, a permutation test and a multivariate Cox regression analysis. In addition, the predictive power of the identified marker signature was validated on a second independent external test cohort (n?=?225). A signature of seven biomarkers (Bax, Bcl-X, PTEN, COX-2, loss of ?-Catenin, loss of MTAP, and presence of CD20 positive B-lymphocytes) was found to be an independent negative predictor for overall and recurrence-free survival in patients with MM. The seven-marker signature could also predict a high risk of disease recurrence in patients with localized primary MM stage pT1-2 (tumor thickness ?2.00 mm). In particular, three of these markers (MTAP, COX-2, Bcl-X) were shown to offer direct therapeutic implications.; The seven-marker signature might serve as a prognostic tool enabling physicians to selectively triage, at the time of diagnosis, the subset of high recurrence risk stage I-II patients for adjuvant therapy. Selective treatment of those patients that are more likely to develop distant metastatic disease could potentially lower the burden of untreatable metastatic melanoma and revolutionize the therapeutic management of MM
Von gelben Feldern zu GrĂŒner Chemie. Ăber die Selektive Desaktivierung bei der Oxidation von Glycerol zu Dihydroxyaceton an Platin-Bismut-Katalysatoren
Die Nutzung des nachwachsenden Rohstoffs Glycerol beschrĂ€nkt sich bislang auf seinen Einsatz in Kosmetika, Nahrungs- und Genussmitteln sowie Kunststoffen. Die Produktionsmenge ĂŒbersteigt den Bedarf jedoch deutlich. Die industrielle Herstellung von Folgeprodukten wĂ€re daher wĂŒnschenswert, zumal Chemikalien aus petrochemischen Grundstoffen ersetzt werden können. Insbesondere die in dieser Arbeit untersuchte selektive Oxidation des Glycerols kann die Herstellung des Produktes Dihydroxyaceton wirtschaftlich attraktiver machen. Dabei ist Dihydroxyaceton nicht nur als Aktivkomponente in Kosmetika interessant, denn die selektive Oxidation des Glycerols stellt bis heute eine wissenschaftliche Herausforderung dar. Die Probleme dieser Reaktion bestehen in der Desaktivierung des Katalysators, die zu einer Abnahme der SelektivitĂ€t mit fortschreitendem Reaktionsfortschritt fĂŒhrt. Durch deren Untersuchung und kinetische Modellierung konnte festgestellt werden, dass besonders die starke Adsorption von Nebenprodukten am Katalysator zur Katalysatordesaktivierung beitrĂ€gt. Es wurde ein kinetisches Modell unter BerĂŒcksichtigung zweier aktiver Zentren aufgestellt, auf dessen Basis eine Ausbeute von 70 % an Dihydroxyaceton vorausgesagt wird, wenn es gelingt, Nebenprodukte aus dem Reaktionsgemisch zu entfernen. Mit Hilfe von Membrantrennverfahren gelang es, Nebenprodukte annĂ€hernd quantitativ zu entfernen. Die AktivitĂ€t erhöhte sich und die Abnahme der SelektivitĂ€t zu Dihydroxyaceton konnte verringert werden. Bei DurchfĂŒhrung der Reaktion in einem kontinuierlichen Trickle-Bed-Reaktor konnten Ausbeuten von bis zu 60 % an Dihydroxyaceton erhalten werden, jedoch fĂŒhren hier weitere Desaktivierungsprozesse zu einer Abnahme der Ausbeute
Production of high-value chemicals from biomass: Synthesis of DHA by aerobic glycerol oxidation on mono- and bimetallic platinum and gold catalysts
Production of high-value chemicals from biomass: Synthesis of DHA by continuous aerobic glycerol oxidation
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