Methanation of carbon dioxide by hydrogen reduction using the Sabatier process in microchannel reactors

This paper describes the development of a microchannel-based Sabatier reactor for applications such as propellant production on Mars or space habitat air revitalization. Microchannel designs offer advantages for a compact reactor with excellent thermal control. This paper discusses the development of a Ru-TiO₂-based catalyst using powdered form and its application and testing in a microchannel reactor. The resultant catalyst and microchannel reactor demonstrates good conversion, selectivity, and longevity in a compact device. A chemically reacting flow model is used to assist experimental interpretation and to suggest microchannel design approaches. A kinetic rate expression for the global Sabatier reaction is developed and validated using computational models to interpret packed-bed experiments with catalysts in powder form. The resulting global reaction is then incorporated into a reactive plug-flow model that represents a microchannel reactor.     

秦南凹陷秦皇岛29-2油气田原油来源及其勘探意义

秦皇岛29-2油气田的发现是秦南凹陷首次重大勘探突破,其影响意义深远.通过对原油物性和地球化学特征分析发现,虽然该油气田凝析油、正常原油和稠油3类原油的物性变化较大,但其母质来源和沉积环境相同、具有同源的特征.以规则甾烷C2920S/(20S+20R)为约束条件,综合利用ααα20RC27/C29规则甾烷和原油碳同位素2种油源对比参数,证实该油气田原油来自沙三段烃源岩.进一步利用回归方程求得原油所对应烃源岩镜质组反射率为0.71％ ～0.72％,与研究区钻井揭示的沙三段烃源岩的成熟度相当,表现出近源供烃的特征.研究结果表明,秦南凹陷内小型次洼已具备较大的生排烃能力,而与之相邻的烃源岩厚度更大、埋藏更深的秦南凹陷东洼周边勘探前景应更为广阔.     

Distribution of sterane maturity parameters in a lacustrine basin and their control factors: A case study from the Dongying Sag, East China

Fifty samples from the source rocks in Member 3 and Member 4 of the Paleogene Shahejie Formation in the Bohai Bay Basin,East China,were analyzed to investigate the distribution,evolution of the molecular maturity ratios C 29 ββ/(ββ+αα) and C 29 20S/(20S+20R) and their control factors in the natural geological profile and sequence.The results showed that progressive changes in molecular maturity parameters are associated with major changes in thermal evolution of related biomarkers.Increases in the C 29 ββ/(ββ+αα) and C 29 20S/(20S+20R) ratios result from the difference in the relative rate between generation and thermal degradation of isomers involved.The samples from a hyper-saline environment below 3.5 km in which evaporitic rocks deposited shows high response of Sr/Ba,Sr/Ca,Fe/Mn,Pr/n-C 17,Ph/n-C 18 and gammacerane and low response of Pr/Ph.There presents negative reversal of biomarker maturity C 29 ββ/(ββ+αα),C 29 20S/(20S+20R) and Ts/(Ts+Tm) in the samples from hypersaline environment,reflecting that the gypsum-halite have negative effect on the isomerization of biomarker and thermal evolution of organic matter.The minerals in evaporites also retard the conventional thermal indicators including vitrinite reflectance (R o) and pyrolysis peak temperature T max at the depth below 3.4 km (i.e.>3.4 km),and these parameters also show the inhibition from overpressure in the range of 2.4-3.4 km.This result will be helpful in the interpretation and application of molecular maturity parameters for similar saline lacustrine basins.     

Polymer membranes for high temperature proton exchange membrane fuel cell: Recent advances and challenges

Proton-exchange membrane fuel cells (PEMFCs) are considered to be a promising technology for efficient power generation in the 21st century. Currently, high temperature proton exchange membrane fuel cells (HT-PEMFC) offer several advantages, such as high proton conductivity, low permeability to fuel, low electro-osmotic drag coefficient, good chemical/thermal stability, good mechanical properties and low cost. Owing to the aforementioned features, high temperature proton exchange membrane fuel cells have been utilized more widely compared to low temperature proton exchange membrane fuel cells, which contain certain limitations, such as carbon monoxide poisoning, heat management, water leaching, etc. This review examines the inspiration for HT-PEMFC development, the technological constraints, and recent advances. Various classes of polymers, such as sulfonated hydrocarbon polymers, acid-base polymers and blend polymers, have been analyzed to fulfill the key requirements of high temperature operation of proton exchange membrane fuel cells (PEMFC). The effect of inorganic additives on the performance of HT-PEMFC has been scrutinized. A detailed discussion of the synthesis of polymer, membrane fabrication and physicochemical characterizations is provided. The proton conductivity and cell performance of the polymeric membranes can be improved by high temperature treatment. The mechanical and water retention properties have shown significant improvement., However, there is scope for further research from the perspective of achieving improvements in certain areas, such as optimizing the thermal and chemical stability of the polymer, acid management, and the integral interface between the electrode and membrane.     

Surface hardening of biomedical Ti–29Nb–13Ta–4.6Zr and Ti–6Al–4V ELI by gas nitriding

The microstructure and hardness near the surface of a biomedical titanium alloy, Ti–29Nb–13Ta–4.6Zr (TNTZ), subjected to gas nitriding at 1023–1223 K was investigated in comparison with the conventional biomedical Ti–6Al–4V ELI (Ti64). After gas nitriding, the microstructure near the specimen surface was observed by optical microscopy, X-ray diffraction (XRD), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS). In both alloys, two types of titanium nitrides (TiN and Ti₂N) are formed and the phase is precipitated by gas nitriding. Furthermore, the oxygen impurity in the gas nitriding atmosphere reacts with the titanium nitrides; thus, TiO₂ is formed at the outermost titanium nitride layer. The surface hardening was also evaluated by Vickers hardness measurement. The Vickers hardness near the surface of TNTZ and Ti64 increases significantly by gas nitriding.     

Effect of fenpropimorph, prochloraz and tebuconazole on growth and production of T-2 and HT-2 toxins by Fusarium langsethiae in oat-based medium

Fusarium langsethiae has been isolated from infected cereals in central and northern Europe where it has been identified in the last decade as the main species involved in the occurrence of high levels of T-2 and HT-2 toxins, mainly in oats. The efficacy of three fungicides (prochloraz, tebuconazole, fenpropimorph) for controlling growth of two strains of F. langsethiae isolated from oats was examined at 0.96 and 0.98 a_w at 15, 20 and 25 °C on oat-based media. The concentrations necessary for 50 and 90% growth inhibition (ED₅₀ and ED₉₀ values) were determined. The effect on the trichothecene type A mycotoxins T-2 and HT-2 was also determined. Without fungicides both strains grew faster at 0.98 than at 0.96 a_w and the influence of temperature on growth rates was 25 > 20 > 15 °C. Prochloraz and tebuconazole were more effective than fenpropimorph against F. langsethiae. Strain, temperature and type of fungicide significantly influenced the ED₅₀ and ED₉₀ values for growth. The concentration ranges under different environmental conditions were: prochloraz (0.03-0.1 and 0.3-1.5), tebuconazole (0.06-0.9 and 1.3-8.2), and fenpropimorph (22-59 and 125-215 mg l⁻¹). Production of T-2 and HT-2 toxins was influenced by temperature, a_w, type of fungicide and dose. Levels of T-2 were usually higher than those of HT-2 under the same conditions. The biosynthesis of T-2 toxin increased after 10 day incubation, but was reduced with decreasing temperature and increasing fungicide dose. At 0.98 a_w T-2 levels increased in cultures containing fenpropimorph while at 0.96 a_w the toxin concentrations increased in response to the other two fungicides. Low doses of prochloraz or tebuconazole enhanced toxin production when compared with untreated cultures for strain 2004-59 at 0.96 a_w and 20-25 °C. HT-2 was hardly detectable in the treatments with prochloraz or tebuconazole at 0.98 a_w. This is the first study on the effect of these anti-fungal compounds on control of growth of F. langsethiae and on production of T-2 and HT-2 toxins in oat-based media.     

A novel thermostable chitinase (PJC) from pomegranate (Punica granatum) juice

A novel chitinase was isolated and purified to its homogeneity from pomegranate juice by a combination of ammonium sulphate precipitation and ion-exchange chromatography. The pomegranate juice chitinase (PJC) was purified to specific activity of 14.5 U/mg and a recovery of 34%. The monomeric protein migrated on SDS–PAGE at 29 kDa. The enzyme was found to be glycosylated (7.2%). It exhibited optimal activity at pH 4.5 and 70 °C. The enzyme was stable in the pH range 3.0–9.0 and up to 65 °C. The internal peptide sequence results suggest that the purified PJC shared high homology with class III chitinases of other known plant chitinases. The purified enzyme could hydrolyse colloidal chitin to its oligomers. It did not exhibit any antifungal activity.     

Angulin-1 (LSR) Affects Paracellular Water Transport,However Only in Tight Epithelial Cells

Water transport in epithelia occurs transcellularly (aquaporins) and paracellularly (claudin-2, claudin-15). Recently, we showed that downregulated tricellulin, a protein of the tricellular tight junction (tTJ, the site where three epithelial cells meet), increased transepithelial water flux. We now check the hypothesis that another tTJ-associated protein, angulin-1 (alias lipolysis-stimulated lipoprotein receptor, LSR) is a direct negative actuator of tTJ water permeability depending on the tightness of the epithelium. For this, a tight and an intermediate-tight epithelial cell line, MDCK C7 and HT-29/B6, were stably transfected with CRISPR/Cas9 and single-guide RNA targeting angulin-1 and morphologically and functionally characterized. Water flux induced by an osmotic gradient using 4-kDa dextran caused water flux to increase in angulin-1 KO clones in MDCK C7 cells, but not in HT-29/B6 cells. In addition, we found that water permeability in HT-29/B6 cells was not modified after either angulin-1 knockout or tricellulin knockdown, which may be related to the presence of other pathways, which reduce the impact of the tTJ pathway. In conclusion, modulation of the tTJ by knockout or knockdown of tTJ proteins affects ion and macromolecule permeability in tight and intermediate-tight epithelial cell lines, while the transepithelial water permeability was affected only in tight cell lines.     

The effect of milk fat globules on adherence and internalization of Salmonella Enteritidis to HT-29 cells

Milk fat globules were extracted from bovine and goat milk and incubated with HT-29 human adenocarcinoma cells to assess the attachment and internalization of Salmonella Enteritidis. Because the expression of bacterial adhesins is highly affected by the presence of antibiotic, the attachment was studied with and without antibiotic in the cell growth medium. Although no inhibitory effect of the fat globules was observed in the presence of the antibiotic, milk fat globules significantly inhibited the binding and internalization of Salmonella in medium free of antibiotic. The fat globules from both bovine and goat milk markedly reduced bacterial binding and invasion compared with controls, and the cells treated with goat milk-derived fat globules demonstrated greater protective properties than those derived from bovine milk. The effect of heat treatment on bovine fat globules was also investigated, and it was shown that the fat globules from heated milk had a higher degree of inhibition than those from unheated milk.     

Begriff "Baumangel"

Baum?ngel sind unzureichende Zust?nde technischer Natur und nicht "bewilligungswidrige" Bauführungen.