The investment in the hydrogen infrastructure for hydrogen mobility has lately seen a significant acceleration. The demand for energy and cost efficient hydrogen liquefaction processes has also ...increased steadily. A significant scale-up in liquid hydrogen (LH2) production capacity from today's typical 5–10 metric tons per day (tpd) LH2 is predicted for the next decade. For hydrogen liquefaction, the future target for the specific energy consumption is set to 6 kWh per kg LH2 and requires a reduction of up to 40% compared to conventional 5 tpd LH2 liquefiers. Efficiency improvements, however, are limited by the required plant capital costs, technological risks and process complexity. The aim of this paper is the reduction of the specific costs for hydrogen liquefaction, including plant capital and operating expenses, through process optimization. The paper outlines a novel approach to process development for large-scale hydrogen liquefaction. The presented liquefier simulation and cost estimation model is coupled to a process optimizer with specific energy consumption and specific liquefaction costs as objective functions. A design optimization is undertaken for newly developed hydrogen liquefaction concepts, for plant capacities between 25 tpd and 100 tpd LH2 with different precooling configurations and a sensitivity in the electricity costs. Compared to a 5 tpd LH2 plant, the optimized specific liquefaction costs for a 25 tpd LH2 liquefier are reduced by about 50%. The high-pressure hydrogen cycle with a mixed-refrigerant precooling cycle is selected as preferred liquefaction process for a cost-optimized 100 tpd LH2 plant design. A specific energy consumption below 6 kWh per kg LH2 can be achieved while reducing the specific liquefaction costs by 67% compared to 5 tpd LH2 plants. The cost targets for hydrogen refuelling and mobility can be reached with a liquid hydrogen distribution and the herewith presented cost-optimized large-scale liquefaction plant concepts.
•Simulation and optimization of newly developed hydrogen liquefaction processes.•Specific liquefaction costs and energy consumption as optimization objectives.•HP-H2 cycle with MRC precooling as preferred liquefaction process up to 100 tpd.•Specific liquefaction costs: reduced by about 50% at 25 tpd and by 67% at 100 tpd.•Energy consumptions ≤6 kWh per kg LH2 feasible with low technical risk.
High-throughput DNA sequencing significantly contributed to diagnosis and prognostication in patients with myelodysplastic syndromes (MDS). We determined the biological and prognostic significance of ...genetic aberrations in MDS. In total, 944 patients with various MDS subtypes were screened for known/putative mutations/deletions in 104 genes using targeted deep sequencing and array-based genomic hybridization. In total, 845/944 patients (89.5%) harbored at least one mutation (median, 3 per patient; range, 0-12). Forty-seven genes were significantly mutated with TET2, SF3B1, ASXL1, SRSF2, DNMT3A, and RUNX1 mutated in >10% of cases. Many mutations were associated with higher risk groups and/or blast elevation. Survival was investigated in 875 patients. By univariate analysis, 25/48 genes (resulting from 47 genes tested significantly plus PRPF8) affected survival (P<0.05). The status of 14 genes combined with conventional factors revealed a novel prognostic model ('Model-1') separating patients into four risk groups ('low', 'intermediate', 'high', 'very high risk') with 3-year survival of 95.2, 69.3, 32.8, and 5.3% (P<0.001). Subsequently, a 'gene-only model' ('Model-2') was constructed based on 14 genes also yielding four significant risk groups (P<0.001). Both models were reproducible in the validation cohort (n=175 patients; P<0.001 each). Thus, large-scale genetic and molecular profiling of multiple target genes is invaluable for subclassification and prognostication in MDS patients.
The promoter effect of alkali causes an increased 1-alkene selectivity, a slightly increased reaction rate, an increased growth probability of hydrocarbons and an increased resistance against ...oxidation by water. These effects are interpreted by a novel hypothesis of the reaction mechanism of F.T.-synthesis.
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The promoter effect of alkali on Fischer-Tropsch iron catalysts causes an increased 1-alkene selectivity, a slightly increased reaction rate, an increased growth probability of hydrocarbon chains and also an increased resistance against oxidation of iron by the reaction product water. Experiments are presented which show that for cobalt catalysts alkali addition also leads to increased 1-alkene selectivity. However, the reaction rate is markedly reduced.
The effect on the 1-alkene selectivity is without doubt due to increased adsorption strength of carbon monoxide causing an enhanced displacement of 1-alkenes while the propensity towards hydrogenation is hardly reduced. For iron catalysts the 1-alkene selectivity increases in the turn of Li, Na, K, Cs. With respect to the bimodal Anderson-Schulz-Flory (ASF) distribution the strong effect on the growth probability
α
2 is independent of the nature of the alkali cation while the fraction
f
2 of the distribution that is characterized by
α
2 increases in the turn Li, Na, K, and Cs.
These strong promoter effects are interpreted on the basis of a novel mechanism of Fischer-Tropsch synthesis whereby the alkali cation takes part in the catalytic circle.
Finally an analogy of the promoter effect of alkali on iron for the ammonia synthesis and the Fischer-Tropsch synthesis is suggested.
We report the self-organization of universal branching patterns of oil nanodroplets under the Ouzo effect Vitale S, Katz J (2003) Langmuir 19:4105–4110—a phenomenon in which spontaneous droplet ...formation occurs upon dilution of an organic solution of oil with water. The mixing of the organic and aqueous phases is confined under a quasi-2D geometry. In a manner analogous to the ramification of ground stream networks Devauchelle O, Petroff AP, Seybold HF, Rothman DH (2012) Proc Natl Acad Sci USA 109: 20832–20836 and Cohen Y, et al. (2015) Proc Natl Acad Sci USA 112:14132–14137 but on a scale 10 orders of magnitude smaller, the angles between the droplet branches are seen to exhibit remarkable universality, with a value around 74° ± 2°, independent of the various control parameters of the process. Numerical simulations reveal that these nanodroplet branching patterns are governed by the interplay between the local concentration gradient, diffusion, and collective interactions. We further demonstrate the ability of the local concentration gradient to drive autonomous motion of colloidal particles in the highly confined space, and the possibility of using the nucleated nanodroplets for nanoextraction of a hydrophobic solute. The understanding obtained from this work provides a basis for quantitatively understanding the complex dynamical aspects associated with the Ouzo effect. We expect that this will facilitate improved control in nanodroplet formation for many applications, spanning from the preparation of pharmaceutical polymeric carriers, to the formulation of cosmetics and insecticides, to the fabrication of nanostructured materials, to the concentration and separation of trace analytes in liquid–liquid microextraction.
The distribution of hydrogen in liquid state has several advantages because of its higher volumetric density compared to compressed hydrogen gas. The demand for liquid hydrogen (LH2), particularly ...driven by clean fuel cell applications, is expected to rise in the near future. Large-scale hydrogen liquefaction plants will play a major role within the hydrogen supply chain. The barriers of built hydrogen liquefiers is the low exergy efficiency and the high specific liquefaction costs. Exergy efficiency improvements, however, are limited by economic viability. The focus of this paper is to present a roadmap for the scale-up of hydrogen liquefaction technology, from state-of-the-art plants to newly developed large-scale liquefaction processes. The work is aimed at reducing the specific liquefaction costs by finding an optimal trade-off between capital costs and operating costs. To this end, two developed hydrogen liquefaction processes were optimized for specific energy consumption and specific liquefaction costs, showing the potential to reduce the specific liquefaction costs by 67% for a 100 tpd LH2 plant compared to a conventional 5 tpd LH2 plant while achieving a specific energy consumption between 5.9 and 6.6 kWh per kg LH2 with technology that is or will be available within 5 years. The results make liquid hydrogen a viable distribution route for hydrogen for mobility.
•A roadmap for stepwise implementation of large hydrogen liquefiers is proposed.•New liquefaction processes are optimized in efficiency and total cost of ownership.•Specific energy consumption between 5.9 and 6.6 kWh per kg LH2 within 5 years.•Specific liquefaction costs reduced by about 60% by upscaling from 5 to 50 tpd.•Results make liquid hydrogen a viable distribution route for hydrogen mobility.
A novel mechanism of the Fischer–Tropsch synthesis is proposed based on the hypothesis that two incompatible mechanism are involved resting exclusively on methylene and on carbon monoxide insertion, ...respectively. This hypothesis is supported by various co-feeding experiments with alkenes, alcohols and diazomethane and contributes to a sound interpretation of the promoter effect of alkali on iron and of the distribution of branched hydrocarbons.
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A new mechanism of the Fischer–Tropsch synthesis is proposed based on the hypothesis that two incompatible mechanisms are involved resting exclusively on methylene and on carbon monoxide insertion, respectively. This hypothesis is reflected by the well known superposition of two Anderson–Schulz–Flory distributions. Experiments with co-feeding of ethene, 1-alkenes and diazomethane as a source of surface methylene and also the carbon number distribution of branched hydrocarbons strongly support the hypothesis of two independent mechanisms and the methylene insertion mechanism of one of them.
Co-feeding of alcohols, the dependence of the ratio of the two mechanisms on the pressure of hydrogen and carbon monoxide and the promoter effect of alkali on iron catalysts also prove the hypothesis of the two mechanisms and point to the carbon monoxide insertion mechanism as the second mechanism that is characterized by the higher growth probability of the resulting Anderson–Schulz–Flory distribution.
Furthermore new interpretations of the crucial steps of C–C linkage and chain termination are given. The insertion of methylene is interpreted by coupling of an alkylidene and a methylene surface species towards a coordinated olefin with the chance of chain growth termination by 1-alkene desorption. For the carbon monoxide insertion mechanism the termination of chain growth is assumed to occur by the formation of 1-alkenes and of alcohols via an alcoholate intermediate.
The new mechanism gives without any exception a sound interpretation of a great variety of experiments and contributes also to the interpretation of the promoter effect of alkali and of the different performance of cobalt and iron catalysts.
A first direct intercomparison of aerosol vertical profiles from Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations, performed during the Cabauw Intercomparison Campaign ...of Nitrogen Dioxide measuring Instruments (CINDI) in summer 2009, is presented. Five out of 14 participants of the CINDI campaign reported aerosol extinction profiles and aerosol optical thickness (AOT) as deduced from observations of differential slant column densities of the oxygen collision complex (O4) at different elevation angles. Aerosol extinction vertical profiles and AOT are compared to backscatter profiles from a ceilometer instrument and to sun photometer measurements, respectively. Furthermore, the near-surface aerosol extinction coefficient is compared to in situ measurements of a humidity-controlled nephelometer and dry aerosol absorption measurements. The participants of this intercomparison exercise use different approaches for the retrieval of aerosol information, including the retrieval of the full vertical profile using optimal estimation and a parametrised approach with a prescribed profile shape. Despite these large conceptual differences, and also differences in the wavelength of the observed O4 absorption band, good agreement in terms of the vertical structure of aerosols within the boundary layer is achieved between the aerosol extinction profiles retrieved by the different groups and the backscatter profiles observed by the ceilometer instrument. AOTs from MAX-DOAS and sun photometer show a good correlation (R>0.8), but all participants systematically underestimate the AOT. Substantial differences between the near-surface aerosol extinction from MAX-DOAS and from the humidified nephelometer remain largely unresolved.
The sulfur-coordinated acyl(hydrido)cobalt(III) complex 1 was synthesized by reaction of thiosalicylaldehyde with CoMe(PMe3)4. The crystal structure of 1 was determined by X-ray diffraction. Complex ...1 is an excellent catalyst for the hydrosilylation of aldehydes and ketones under mild conditions. This might be the first example of hydrosilylation of aldehydes and ketones catalyzed by (hydrido)cobalt complexes.
The mechanisms that extend lifespan in humans are poorly understood. Here we show that extended longevity in humans is associated with a distinct transcriptome signature in the cerebral cortex that ...is characterized by downregulation of genes related to neural excitation and synaptic function. In Caenorhabditis elegans, neural excitation increases with age and inhibition of excitation globally, or in glutamatergic or cholinergic neurons, increases longevity. Furthermore, longevity is dynamically regulated by the excitatory-inhibitory balance of neural circuits. The transcription factor REST is upregulated in humans with extended longevity and represses excitation-related genes. Notably, REST-deficient mice exhibit increased cortical activity and neuronal excitability during ageing. Similarly, loss-of-function mutations in the C. elegans REST orthologue genes spr-3 and spr-4 elevate neural excitation and reduce the lifespan of long-lived daf-2 mutants. In wild-type worms, overexpression of spr-4 suppresses excitation and extends lifespan. REST, SPR-3, SPR-4 and reduced excitation activate the longevity-associated transcription factors FOXO1 and DAF-16 in mammals and worms, respectively. These findings reveal a conserved mechanism of ageing that is mediated by neural circuit activity and regulated by REST.
The purpose of this investigation was to compare a new psychotherapy for bulimia nervosa (BN), integrative cognitive-affective therapy (ICAT), with an established treatment, 'enhanced' ...cognitive-behavioral therapy (CBT-E).
Eighty adults with symptoms of BN were randomized to ICAT or CBT-E for 21 sessions over 19 weeks. Bulimic symptoms, measured by the Eating Disorder Examination (EDE), were assessed at baseline, at the end of treatment (EOT) and at the 4-month follow-up. Treatment outcome, measured by binge eating frequency, purging frequency, global eating disorder severity, emotion regulation, self-oriented cognition, depression, anxiety and self-esteem, was determined using generalized estimating equations (GEEs), logistic regression and a general linear model (intent-to-treat).
Both treatments were associated with significant improvement in bulimic symptoms and in all measures of outcome, and no statistically significant differences were observed between the two conditions at EOT or follow-up. Intent-to-treat abstinence rates for ICAT (37.5% at EOT, 32.5% at follow-up) and CBT-E (22.5% at both EOT and follow-up) were not significantly different.
ICAT was associated with significant improvements in bulimic and associated symptoms that did not differ from those obtained with CBT-E. This initial randomized controlled trial of a new individual psychotherapy for BN suggests that targeting emotion and self-oriented cognition in the context of nutritional rehabilitation may be efficacious and worthy of further study.
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