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991.
Hydrodechlorination and hydrogenation of aromatic compounds over palladium on alumina in hydrogen-saturated water 总被引:2,自引:0,他引:2
The catalytic transformations of 1,2-dichlorobenzene, chlorobenzene, 4-chlorobiphenyl, γ-hexachlorocyclohexane (Lindane), naphthalene and phenanthrene were studied over palladium on alumina in hydrogen-saturated water (Pd/Al2O3/H2) at room temperature and ambient pressure. The chlorinated benzenes were rapidly hydrodechlorinated and Lindane was dehydrochlorinated to benzene. Partial or complete hydrogenation was observed for biphenyl and the polycyclic aromatic hydrocarbons. The phenanthrene ring was cleaved at the 9,10-position. In general dechlorination reactions were faster than hydrogenation reactions. 相似文献
992.
993.
Media photo‐degradation in pharmaceutical biotechnology – impact of ambient light on media quality,cell physiology,and IgG production in CHO cultures 下载免费PDF全文
Lukas Neutsch Paul Kroll Matthias Brunner Alexander Pansy Michael Kovar Christoph Herwig Tobias Klein 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2018,93(8):2141-2151
BACKGROUND
Many vital components in bioprocess media are prone to photo‐conversion or photo‐degradation upon exposure to ambient light, with severe negative consequences for biomass yield and overall productivity. However, there is only limited awareness of light irradiation as a potential risk factor when working in transparent glass bioreactors, storage vessels or disposable bag systems. The chemical complexity of most media renders a root‐cause analysis difficult. This study investigated in a novel, holistic approach how light‐induced changes in media composition relate to alterations in radical burden, cell physiology, morphology, and product formation in industrial Chinese hamster ovary (CHO) bioprocesses.RESULTS
Two media formulations from proprietary and commercial sources were tested in a pre‐hoc light exposure scenario prior to cultivation. Using fluorescence excitation/emission (EEM) matrix spectroscopy, a photo‐sensitization of riboflavin was identified as a likely cause for drastically decreased IgG titers (up to ?80%) and specific growth rates (?50% to ?90%). Up to three‐fold higher radical levels were observed in photo‐degraded medium. On the biological side, this resulted in significant changes in cell morphology and aberrations in the normal IgG biosynthesis/secretion pathway.CONCLUSION
These findings clearly illustrate the underrated impact of room light after only short periods of exposure, occurring accidentally or knowingly during bioprocess development and scale‐ up. The detrimental effects, which may share a common mechanistic cause at the molecular level, correlate well with changes in spectroscopic properties. This offers new perspectives for online monitoring concepts, and improved detectability of such effects in future. © 2018 The Authors. Journal of Chemical Technology & Biotechnology published by JohnWiley & Sons Ltd on behalf of Society of Chemical Industry.994.
Laura Hader-Kregl Gernot M. Wallner Christoph Kralovec Carola Eyßell 《The Journal of Adhesion》2013,89(12):1088-1100
Interlaminar shear test methods (ILS) were implemented to characterize the delamination behavior of asymmetric steel/carbon fiber reinforced plastic (CFRP) hybrids. To improve the delamination behavior thermoplastic inter-plies were inserted between CFRP and steel. Supported by optical strain measurement the maximum shear stress (τMAX), the shear stress at interfacial delamination (τIF) and the shear stress at large-scale CFRP ply delamination τD were evaluated. The significant effect of inter-plies on the adhesion was best reflected by the shear stress value at interfacial delamination. Finite element analysis of the actual shear stress distribution in an asymmetric hybrid sample without inter-ply revealed that the calculated shear strength is just slightly overestimated compared to the standardized evaluation procedure. 相似文献
995.
Kersten Christoph Link Ernst-Ulrich Schlünder 《Chemical Engineering and Processing: Process Intensification》1997,36(6)
The coating and granulation of solid particles in a fluidized bed is a process which converts pumpable and atomizable liquids (solutions, slurries, melts) into granular solids in one step by means of drying. The solution to be processed is sprayed onto a fluidized bed. Particle growth can take place either via surface layering or agglomeration. In the case of surface layering the atomized droplets deposit a thin layer of liquid onto the seed particles. The solvent is then evaporated by the hot fluidizing, leaving behind the dissolved material on the surface. Although fluidized bed spray granulation and film coating have been applied in industry for several years, there is still a lack of understanding of the physical fundamentals and the mechanisms by which spherical granules are formed. Hence a new method was developed which allows the direct observation of the subsequent particle-forming mechanisms such as droplet deposition, spreading, wetting and drying. The authors present a laboratory scale apparatus in which a single freely suspended particle can be coated under well defined and constant coating and drying conditions. With this device, particle-growth-rate and the development of particle morphology were measured and investigated under various experimental conditions. 相似文献
996.
Cejka C Knechtle B Knechtle P Rüst CA Rosemann T 《Journal of the International Society of Sports Nutrition》2012,9(1):11-10
Background
An association between fluid intake and changes in volumes of the upper and lower limb has been described in 100-km ultra-marathoners. The purpose of the present study was (i) to investigate the association between fluid intake and a potential development of peripheral oedemas leading to an increase of the feet volume in 100-km ultra-marathoners and (ii) to evaluate a possible association between the changes in plasma sodium concentration ([Na+]) and changes in feet volume.Methods
In seventy-six 100-km ultra-marathoners, body mass, plasma [Na+], haematocrit and urine specific gravity were determined pre- and post-race. Fluid intake and the changes of volume of the feet were measured where the changes of volume of the feet were estimated using plethysmography.Results
Body mass decreased by 1.8 kg (2.4%) (p < 0.0001); plasma [Na+] increased by 1.2% (p < 0.0001). Haematocrit decreased (p = 0.0005). The volume of the feet remained unchanged (p > 0.05). Plasma volume and urine specific gravity increased (p < 0.0001). Fluid intake was positively related to the change in the volume of the feet (r = 0.54, p < 0.0001) and negatively to post-race plasma [Na+] (r = -0.28, p = 0.0142). Running speed was negatively related to both fluid intake (r = -0.33, p = 0.0036) and the change in feet volume (r = -0.23, p = 0.0236). The change in the volume of the feet was negatively related to the change in plasma [Na+] (r = -0.26, p = 0.0227). The change in body mass was negatively related to both post-race plasma [Na+] (r = -0.28, p = 0.0129) and running speed (r = -0.34, p = 0.0028).Conclusions
An increase in feet volume after a 100-km ultra-marathon was due to an increased fluid intake. 相似文献997.
In the last decade the reduction of CO2 emissions from fossil fuels became a worldwide topic. Co-gasification of coal and wood provides an opportunity to combine the advantages of the well-researched usage of fossil fuels such as coal with CO2-neutral biomass. Gasification itself is a technology with many advantages. The producer gas can be used in many ways; for electric power generation in a gas engine or gas turbine, for Fischer-Tropsch synthesis of liquid fuels and also for production of gaseous products such as synthetic natural gas (bio SNG). Moreover, the use of the producer gas in fuel cells is under investigation. The mixture of coal and wood leads to the opportunity to choose the gas composition as best befits the desired process. Within this study the focus of investigation was of gasification of coal and wood in various ratios and the resulting changes in producer gas composition. Co-gasification of coal and wood leads to linear producer gas composition changes with linear changing load ratios (coal/wood). Hydrogen concentrations rise with increasing coal ratio, while CO concentrations decrease. Due to the lower sulfur and nitrogen content of wood, levels of the impurities NH3 and H2S in the producer gas fall with decreasing coal ratio. It is also shown that the majority of sulfur is released in the gasification zone and, therefore, no further cleaning of the flue gas is necessary. All mixture ratios, from 100 energy% to 0 energy% coal, performed well in the 100 kW dual fluidized bed gasifier. Although the gasifier was originally designed for wood, an addition of coal as fuel in industrial sized plants based on the same technology should pose no problems. 相似文献
998.
This paper is concerned with the chemical looping combustion of coal in a technique whereby the fuel is gasified in situ using CO2 in the presence of a batch of supported copper oxide (the “oxygen carrier”) in a single reactor. As the metal oxide becomes depleted, the feed of fuel is discontinued, the inventory of fuel is reduced by further gasification and then the contents are re-oxidised by the admission of air to the reactor, to begin the cycle again. A catalyst support, impregnated with a saturated solution of copper and aluminium nitrates, acted as a durable oxygen carrier over numerous cycles of reduction and oxidation, using air as the oxidant. Two bituminous coals (Taldinskaya, Russia, and Illinois No. 5, USA) were investigated and compared with a lignite (Hambach, Germany). The lignite was highly reactive and was gasified completely by 15 mol% CO2 in N2 at 1203 K and 1 bar, so that there was no build up of char in the bed. The bituminous coals produced chars much less reactive than the lignite char, so that there was a steady accumulation of char in the bed with number of cycles, with the degree of accumulation being dependent on the reactivity of the char. Since the kinetics of gasification by CO2 of the chars from either bituminous coal were slow, their rates were controlled by intrinsic chemical kinetics and were not affected by the ability of the oxygen carrier to alter the rates of external mass transfer when gasification is rapid. However, it is likely that rates of gasification in the presence of the carrier are still larger than in its absence, owing to the overall lower [CO] present in the bulk of the fluidised bed during chemical looping. At the temperature used, the carrier was cycling between Cu and Cu2O, since CuO is only stable if the partial pressure of O2 exceeds 0.03 bar at 1203 K. The CuO decomposes to Cu2O and O2 relatively rapidly at these temperatures, once the oxygen concentration is effectively zero. It was impossible to ascertain in our experiments whether the oxygen so generated, after the switching of the air for nitrogen before the start of the succeeding cycle of gasification, made any substantial difference to the reactivity of the char present in the bed. The rate of oxidation of the carrier was found to be much more rapid than the rate of oxidation of the inventory of char. This allows a preferential oxidation of the carrier and most likely accounts for why progressively less CO and CO2 is produced during successive cycles with short periods of oxidation: the increasingly reduced carrier reacts more rapidly than the char. There was no obvious impact from the sulphur contained in the fuels, but longer-term testing is needed. No agglomeration between the carrier particles and the ash was observed, despite the high temperatures during oxidation. 相似文献
999.
Christoph Brandes Laura Treccani Stephen Kroll Kurosch Rezwan 《Journal of the American Ceramic Society》2014,97(5):1393-1401
The growing demand of reliable high‐performance membrane materials for separation processes requires new simple, straightforward, environmental friendly, sustainable approaches for membrane fabrication. In this study, we present an environmentally friendly gel‐casting, one‐pot process based on ionotropic‐gelation for obtaining alumina membranes. A slurry of alumina particles and the biopolymer alginate, which acts in combination with calcium iodate like a resin, was gelled in a controllable temperature dependent manner. Alumina membranes are obtained by three different shaping routes (extrusion, free‐forming, casting). The suitability of extruded capillaries in a polymer‐ceramic hybrid state (green body) and after sintering (1150°C for 2 h) for potential application in micro‐ and ultrafiltration is evaluated by monitoring the chemical and mechanical stability, permeability and separation behavior. Varying the initial alumina particle size from 200 to 900 nm, membranes with a narrow pore size distribution, predictable and tunable average pore diameters from 70 up to 480 nm and a constant open porosity of ~40%, are obtained. The permeability behavior is tested with fluorescence labeled submicron‐ and nano‐particles. Our novel colloidal processing route represents a very versatile tool for designing and manufacturing ceramic membranes with complex shapes for micro‐ (>0.1 μm) and ultrafiltration (0.1–0.01 μm). 相似文献
1000.
Catalytic steam reforming of model biogas 总被引:2,自引:0,他引:2
Catalytic steam reforming of a model biogas (CH4/CO2 = 60/40) is investigated to produce H2-rich synthesis gas. Gas engines benefit from synthesis gas fuel in terms of higher efficiency and lower NOx production when compared to raw biogas or CH4. The process is realized in a fixed bed reactor with a Ni-based catalyst on CaO/Al2O3 support. To optimize the performance, the reactor temperature and the amount of excess steam are varied. The experimental results are compared to the theoretical values from thermodynamic calculation and the main trends of CH4 conversion and H2 yield are analyzed and verified. Finally, optimal reactor temperature is pointed out and a range of potential steam to methane ratios is presented. The experimental results will be applied to design a steam reformer at an existing anaerobic biomass fermentation plant in Strem, Austria. 相似文献