Hydrogen Production by Partial Catalytic Dehydrogenation of Kerosene

Due to decreasing supplies of fossil fuels and increasing environmental pollution, the introduction of a more fuel efficient electrical power system in aircraft applications is necessary. One possibility to improve the efficiency is to run the auxiliary power unit (APU), which provides electric energy on airplanes, with an efficient proton exchange membrane fuel cell system (PEMFC). The hydrogen for this concept can be provided by partial catalytic dehydrogenation (PCD) of Jet fuel stored onboard. The difference of this alternative thermochemical catalytic process to the more common reforming process is that no water is needed as a reaction partner. Therefore, no CO is generated, which would poison the catalyst in PEMFC. Other than gaseous hydrocarbons, no gaseous side products are expected. Beyond that, a high hydrogen purity of 98 vol.-% can be achieved. The partial conversion of jet fuel of about 10 to 15 % allows further use of the converted fuel in combustion processes on board. Since the composition of kerosene is very diverse, suitable reaction conditions for a process concept of the PCD of kerosene Jet A-1 have to be defined and the efficiency of the process has to be evaluated. In this thesis, two different process concepts for PCD of jet fuel are developed and their efficiency is evaluated by process simulation. One process concept is designed to run with regular kerosene Jet A-1, which involves a desulfurization step of the jet fuel before the PCD to reduce catalyst deactivation by sulfur poisoning. Since the sulfur containing components in Jet A-1 are found in the higher boiling range of kerosene, the desulfurization is accomplished by thermal distillation of desulfurized Jet A-1 fractions by rectification. The second concept is designed to run with desulfurized kerosene which differs in its chemical composition from regular Jet A-1. The first part of this thesis deals with the experimental characterization of the fuels. As the hydrogen yield, conversion of the fuel and product compositions highly depend on the composition of the hydrocarbon groups in kerosene, the detailed chemical composition of kerosene Jet A-1 was investigated and model components have been defined. These model components represent the hydrocarbon groups in the Jet fuel and they can be used for the design of model mixtures to experimentally investigate hydrogen yield, product composition, conversion rates, stability of the catalytic reaction and the reaction conditions. The catalyst used for the experimental investigation is platinum with tin on an aluminum oxide carrier. The experimental results using the model components show, that the hydrocarbon group of cycloalkanes leads to high hydrogen yield and stable reaction conditions. On the other hand, n-alkanes lead to catalyst deactivation by carbon formation on the catalyst surface and side reactions, thus causing a decline of hydrogen purity of the product gas by evolution of gaseous hydrocarbons. In a next step, the previously defined reaction conditions from the model mixture tests are applied to real kerosene. Due to the content of long chain hydrocarbons of up to 22 carbon atoms causing catalyst deactivation by carbon formation, the stability of this reaction is strongly reduced in comparison to the model mixtures. So far, a more suitable catalyst for more stable process conditions does not yet exist. In the second part of the thesis, the experimental results of the model components and model mixture are used for modelling the two process concepts for PCD in the process simulation. To achieve the highest possible system efficiency, a heat and material integration of the two process concepts is accomplished within the process simulation. For the definition of the system efficiency, the hydrogen yield is a key figure since it is the output of the process. The electric efficiency of both process concepts includes system losses of the fuel cell and product gas conditioning. With the experimentally investigated hydrogen yields of the model mixtures, a system efficiency for the process concept, including the desulfurization of the Jet fuel, of 17% is achieved. The process concept working with desulfurized Jet fuel has no additional energy demand for the desulfurization and achieves for system efficiency a value of 20.7%. To compete with a regular gas turbine APU, with average efficiency of 15 to 18%, the fuel cell APU system provided with hydrogen from PCD of kerosene has to be advanced to higher hydrogen yield. This could be accomplished by the development of design fuels for aircraft applications which suit PCD conditions and catalyst development. The results in this work can provide the boundary conditions for these investigations

Hydrogen production by partial catalytic dehydrogenation of kerosene

Die Verknappung fossiler Energieträger erhöht den Bedarf an effizienten Technologien in der Luftfahrt. Für die Stromerzeugung an Bord eines Flugzeugs, während des Bodenbetriebs, können anstelle eines konventionellen Hilfstriebwerks alternativ Brennstoffzellensysteme eingesetzt werden. Der dafür notwendige Wasserstoff kann durch partielle katalytische Dehydrierung des an Bord verfügbaren Kerosins bereitgestellt werden. In dieser Arbeit werden zwei alternative Prozesskonzepte für die Wasserstofferzeugung aus Kerosin entwickelt und auf Ihren elektrischen Wirkungsgrad energetisch bewertet. Für diesen Zweck wird die partielle katalytische Dehydrierung von Kerosin detailliert experimentell untersucht und die Ergebnisse in die Modellierung der Prozesskonzepte eingebunden

Vitamin A, vitamin E, iron and zinc status in a cohort of HIV-infected mothers and their uninfected infants

Introduction We hypothesized that nutritional deficiency would be common in a cohort of postpartum, human immunodeficiency virus (HIV)-infected women and their infants. Methods Weight and height, as well as blood concentrations of retinol, α-tocopherol, ferritin, hemoglobin, and zinc, were measured in mothers after delivery and in their infants at birth and at 6-12 weeks and six months of age. Retinol and α-tocopherol levels were quantified by high performance liquid chromatography, and zinc levels were measured by atomic absorption spectrophotometry. The maternal body mass index during pregnancy was adjusted for gestational age (adjBMI). Results Among the 97 women 19.6% were underweight. Laboratory abnormalities were most frequently observed for the hemoglobin (46.4%), zinc (41.1%), retinol (12.5%) and ferritin (6.5%) levels. Five percent of the women had mean corpuscular hemoglobin concentrations < 31g/dL. The most common deficiency in the infants was α-tocopherol (81%) at birth; however, only 18.5% of infants had deficient levels at six months of age. Large percentages of infants had zinc (36.8%) and retinol (29.5%) deficiencies at birth; however, these percentages decreased to 17.5% and 18.5%, respectively, by six months of age. No associations between infant micronutrient deficiencies and either the maternal adjBMI category or maternal micronutrient deficiencies were found. Conclusions Micronutrient deficiencies were common in HIV-infected women and their infants. Micronutrient deficiencies were less prevalent in the infants at six months of age. Neither underweight women nor their infants at birth were at increased risk for micronutrient deficiencies

Prostate Cancer Induced by Loss of Apc Is Restrained by TGFβ Signaling

Recent work with mouse models of prostate cancer (CaP) has shown that inactivation of TGFβ signaling in prostate epithelium can cooperate with deletion of the Pten tumor suppressor to drive locally aggressive cancer and metastatic disease. Here, we show that inactivating the TGFβ pathway by deleting the gene encoding the TGFβ type II receptor (Tgfbr2) in combination with a deletion of the Apc tumor suppressor gene specifically in mouse prostate epithelium, results in the rapid onset of invasive CaP. Micro-metastases were observed in the lymph nodes and lungs of a proportion of the double mutant mice, whereas no metastases were observed in Apc single mutant mice. Prostate-specific Apc;Tgfbr2 mutants had a lower frequency of metastasis and survived significantly longer than Pten;Tgfbr2 double mutants. However, all Apc;Tgfbr2 mutants developed invasive cancer by 30 weeks of age, whereas invasive cancer was rarely observed in Apc single mutant animals, even by one year of age. Further comparison of the Pten and Apc models of CaP revealed additional differences, including adenosquamous carcinoma in the Apc;Tgfbr2 mutants that was not seen in the Pten model, and a lack of robust induction of the TGFβ pathway in Apc null prostate. In addition to causing high-grade prostate intra-epithelial neoplasia (HGPIN), deletion of either Pten or Apc induced senescence in affected prostate ducts, and this restraint was overcome by loss of Tgfbr2. In summary, this work demonstrates that TGFβ signaling restrains the progression of CaP induced by different tumor suppressor mutations, suggesting that TGFβ signaling exerts a general tumor suppressive effect in prostate.This work was supported by a Program Project Grant from the National Cancer Institute (2P01CA104106 to B. Paschal and D. Wotton), and by a pilot grant from the UVA Cancer Center (funded from the CCSG P30 CA44579, the James and Rebecca CraigFoundation, and UVA Women's Oncology fund) to D. Wotton. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. We thank Sharon Birdsall for technical assistance, Anindya Dutta and Dan Gioeli for helpful discussions, and Chun-Song Yang for advice and reagent

Identification of genetic variants associated with Huntington's disease progression: a genome-wide association study

Background Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. Methods We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008–11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003–13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. Findings Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10−10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10−8 DHFR p=8·37 × 10−7 MTRNR2L2 p=2·15 × 10−9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10−4 DHFR p=8·45 × 10−4 MTRNR2L2 p=1·20 × 10−3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10−8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16–0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06–0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. Interpretation The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

HYDROGEN PRODUCTION FROM SELECTED KEROSINE COMPONENTS BY PARTIAL CATALYTIC DEHYDROGENATION

The providing and storage of hydrogen for efficient fuel cell systems is an on-going challenge. The partial catalytic dehydrogenation (PCD) of liquid fuels can provide stationary or mobile fuel cell systems with hydrogen. Through PCD, liquid fuels can be treated as hydrogen storage as well as an energy provider for combustion processes. It is also an alternative to the common reforming processes where the fuel is converted with steam into a hydrogen rich product gas with co- products like carbon monoxide and carbon dioxide that requires CO clean-up before feeding into a proton exchange membrane fuel cell. The direct dehydrogenation on a catalyst can provide a hydrogen product gas of high purity (95 vol-%) without carbon monoxide or carbon dioxide. The hydrogen is partly removed and the fuel is not completely transformed into a gaseous product. Therefore the partial dehydrogenated fuel can be used for further processes. At the Institute of Technical Thermodynamics of the German Aerospace Centre, a test rig was built for the PCD of kerosene, to investigate the product gas quality, the by-products, and hydrogen yield. A big challenge for PCD catalyst is the sulphur content, on average 500 ppmw, of kerosene [1]. To remove sulphur components from kerosene, thermal fractionation by rectification is suitable based on the boiling range of kerosene. The process concept for the PCD with fuel cell system includes the desulphurization of kerosene or the use of desulphurized kerosene (DK) (3ppmw sulphur)

Wasserstofferzeugung durch partielle katalytische Dehydrierung (PkD) ausgewählter Komponenten von Kerosin

Wasserstofferzeugung aus flüssigen Brennstoffen für die Versorgung von Brennstoffzellensystemen hat das Potenzial, sowohl in der stationären dezentralen Energieversorgung als auch im mobilen Bereich Anwendung zu finden. Im Flugzeug kann für die Bordstromversorgung mittels Brennstoffzelle on-board aus Kerosin erzeugter Wasserstoff eingesetzt werden. Damit wird ein wesentlicher Beitrag zur Reduzierung der Emissionen als auch der Lärmbeeinträchtigung durch Flugzeuge am Boden geleistet. Neben den bereits intensiv untersuchten Reformierungsverfahren zur Wasserstofferzeugung wird am DLR ein neuartiges Verfahrenskonzept aus Fraktionierung und nachfolgender partieller katalytischer Dehydrierung (PDh) verfolgt. Die Abtrennung einer signifikant schwefelreduzierten Kerosinfraktion mittels Rektifikation konnte bereits erfolgreich experimentell nachgewiesen werden. Mit der partiellen katalytischen Dehydrierung kann bei einer gegenüber der Reformierung deutlich reduzierten Umwandlungstemperatur unterhalb 500°C reiner Wasserstoff erzeugt werden. Dadurch können aufwendige Aufbereitungsschritte zur Reinigung des Produktgases für den Einsatz in der Brennstoffzelle entfallen. Die Herausforderung bei der Dehydrierung des Flugtreibstoffs Jet A1 liegt in dessen komplexer chemischer Zusammensetzung. Durch GCMS und GCFID können vier Hauptstoffgruppen, Paraffine, Iso-Paraffine, Naphthene und Aromaten in Jet A1 identifiziert werden. Die Wasserstoffausbeute aus Kerosin ist in hohem Maße von der Art und dem Anteil dieser Stoffgruppen abhängig. Während Naphthene sich gut zu Wasserstoff und Aromaten umsetzen lassen, werden Aromaten bei der PDh nicht umgesetzt und Paraffine und Iso-Paraffine führen zu teilweise gasförmigen Nebenprodukten wie Methan und Verkokungen am Katalysator. Da in dem vorgeschalteten Fraktionierungsschritt durch thermische Trennung auch die Zusammensetzung der Stoffgruppen des Kerosins verändert wird, ist es von besonderem Interesse, das Verhalten der Stoffgruppen in der PDh durch experimentelle Untersuchungen beurteilen zu können. Beim DLR wurde daher ein PDh-Laborteststand zur Untersuchung der erzielbaren Wasserstoffausbeuten und zur Identifizierung geeigneter Betriebsparameter aufgebaut. Qualifiziert werden neben reinem Kerosin und einzelnen Kohlenwasserstoffgruppen auch unterschiedliche, schwefelreduzierte Fraktionen für die katalytische partielle Dehydrierung. Basierend auf den experimentellen Ergebnissen erfolgt anschließend eine energetische Bewertung des Verfahrenskonzepts für die Bordstromversorgung anhand eines Prozessmodells in Aspen Plus. Für diesen Zweck wurden zwei wärmeintegrierte Prozesskonzepte entwickelt. Zum einen wird die PDh mit vorgeschalteter Fraktionierung abgebildet und zum anderen ein vereinfachtes System bei dem bereits schwefelarmes Kerosin für die PDh bereitgestellt wird aufgrund dessen ein höherer Wirkungsgrad erzielt werden kann. Im Rahmen des Vortrags werden ausgewählte experimentelle Ergebnisse zur partiellen katalytischen Dehydrierung sowie die energetische Bewertung der beiden Prozesskonzepte mittels Pinch- Methode vorgestellt