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11.
Combination of Reaction and Separation in Heterogeneous Catalytic Hydrogenation of Ethylformate 下载免费PDF全文
Gerson Martin Carla Pereira Frank Pettersson Henrik Saxén Dmitry Y. Murzin Alírio Rodrigues Tapio Salmi 《化学工程与技术》2015,38(5):804-812
Continuous hydrogenation reaction of ethyl benzoylformate was studied over a (–)‐cinchonidine (CD)‐modified Pt/Al2O3 catalyst. The catalyst showed a good stability, and high enantioselectivity was achieved in the fixed‐bed reactor. Chromatographic separation of (R)‐ and (S)‐ethyl mandelate originating from a post‐continuous hydrogenation reaction of ethyl benzoylformate over the (–)‐CD‐modified Pt/Al2O3 catalyst was investigated in the same reaction mixture. A commercial column filled with a chiral selector resin was chosen as a perspective preparative‐scale adsorbent. Since adsorption equilibrium isotherms were linear within the entire investigated range of concentrations, they were determined by pulse experiments for the isomers present in a post‐reaction mixture. Breakthrough curves were measured and described successfully by the dispersive plug‐flow model with linear driving force approximation. 相似文献
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Kati Miettunen Jarkko Etula Tapio Saukkonen Sami Jouttijrvi Janne Halme Jyrki Romu Peter Lund 《Progress in Photovoltaics: Research and Applications》2015,23(8):1045-1056
The main issue in using low cost metals in dye solar cells is the corrosion caused by the liquid electrolyte. Contrary to typical applications of metals, the adverse effects of corrosion in dye solar cells are related to irreversible depletion of charge carriers from the electrolyte rather than consumption of the metal itself. It is calculated that the penetration rate due to corrosion should not exceed 10−4 mpy (a couple of nanometers per year) to ensure device lifetime longer than 1 year. This is 10 000 times slower rate than what is considered to be a general benchmark value for very low corrosion rate in the field of corrosion science and has a major effect on how corrosion should be investigated in the case of dye solar cells. Different methods, their applicability, and limitations to investigate corrosion in dye solar cells are evaluated here. The issue with most techniques is that they can detect metals that are clearly corroding, but they have significant limitations in proving a metal stable. Our investigation shows that the most reliable information on corrosion is obtained from complete dye solar cells that are exposed to working conditions. A combination of color analysis of the electrolyte to such measurement is proposed as a means to extrapolate future performance of the cells and estimate potential lifetimes of the dye solar cells in regards to corrosion. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
14.
Kinetic modeling of hemicellulose hydrolysis in the presence of homogeneous and heterogeneous catalysts 下载免费PDF全文
Tapio Salmi Dmitry Yu. Murzin Päivi Mäki‐Arvela Bright Kusema Bjarne Holmbom Stefan Willför Johan Wärnå 《American Institute of Chemical Engineers》2014,60(3):1066-1077
Kinetic models were developed for the hydrolysis of O‐acetyl‐galactoglucomannan (GGM), a hemicellulose appearing in coniferous trees. Homogeneous and heterogeneous acid catalysts hydrolyze GGM at about 90°C to the monomeric sugars galactose, glucose, and mannose. In the presence of homogeneous catalysts, such as HCl, H2SO4, oxalic acid, and trifluoroacetic acid, the hydrolysis process shows a regular kinetic behavior, while a prominent autocatalytic effect was observed in the presence of heterogeneous cation‐exchange catalysts, Amberlyst 15 and Smopex 101. The kinetic models proposed were based on the reactivities of the nonhydrolyzed sugar units and the increase of the rate constant (for heterogeneous catalysts) as the reaction progresses and the degree of polymerization decreases. General kinetic models were derived and special cases of them were considered in detail, by deriving analytical solutions for product distributions. The kinetic parameters, describing the autocatalytic effect were determined by nonlinear regression analysis. The kinetic model described very well the overall kinetics, as well as the product distribution in the hydrolysis of water soluble GGM by homogeneous and heterogeneous catalysts. The modelling principles developed in the work can be in principle applied to hydrolysis of similar hemicelluloses as well as starch and cellulose. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1066–1077, 2014 相似文献
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Tapio Eeva Samuli Helle Juha-Pekka Salminen Harri Hakkarainen 《Journal of chemical ecology》2010,36(6):608-613
Dietary carotenoids are important pigments, antioxidants, and immune-stimulants for birds. Despite recent interest in carotenoids
in bird ecology, we know surprisingly little about the carotenoid content of invertebrates consumed by birds. We compared
carotenoid (lutein, β-carotene, and total) concentrations in invertebrates brought to nestlings by two insectivorous passerines,
the great tit, Parus major and the pied flycatcher, Ficedula hypoleuca. We also compared carotenoid levels between environments that were either polluted by heavy metals or were not polluted,
because the carotenoid-based plumage color of P. major nestlings is affected by environmental pollution. Lepidopterans were the most carotenoid-rich food items and contained the
largest proportion of lutein. There were no differences in carotenoid concentrations in the food items of the two bird species
but P. major nestlings obtained more carotenoids from their invertebrate diet than F. hypoleuca nestlings because the P. major diet had a higher proportion of lepidopteran larvae. In polluted areas, P. major nestlings consumed lower levels of dietary carotenoids than in unpolluted areas because of temporal differences in caterpillar
abundance between polluted and unpolluted sites. Our study suggests that pollution-related difference in nestling plumage
color in P. major is related to varying dietary proportion of lutein-rich food items rather than pollution-related variation in insect carotenoid
levels. 相似文献
16.
Tapio Salmi Henrik GrénmanJohan Wärnå Dmitry Yu. Murzin 《Chemical Engineering Research and Design》2013
Typical features of liquid–solid reactions were reviewed: reaction kinetics, mass transfer effects and particle morphology. It was concluded that classical liquid–solid models based on ideal, non-porous geometries (sphere, infinite cylinder, slab) cannot satisfactorily describe real reactive solid particles with various surface defects, such as cracks, craters and limited porosity. Typically a too low reaction order for the reactive solid is predicted by the classical models. The surface morphology can be revealed by electron microscopy, which gives inspiration to develop new mathematical models for reactive solids. 相似文献
17.
Johan Plomp Mikko Heiskanen Mika Hillukkala Tapio Heikkilä Jari Rehu Niek Lambert Victor van Acht Tom Ahola 《International Journal of Wireless Information Networks》2011,18(4):280-294
In this paper, we highlight considerations for synchronization issues in body area networks. Requirements for the synchronization
accuracy in body area networks depend on the application at hand. Synchronization may be needed for power management, sample
ordering, calculation of stimulus responses and for sensor fusion. This paper provides a theoretical exercise to help understand
the accuracy required for typical human motion sensing. It gives an overview of various synchronisation strategies used and
implemented in prototype systems. Lessons learnt from practical implementations using Bluetooth, an IEEE 802.15.4 proprietary
network and Nanonet are presented to illustrate the principles involved. The discussion provides some considerations and the
requirements for typical WBAN applications. 相似文献
18.
Heikki Käsnänen Mikko J. Myllymäki Anna Minkkilä Antti O. Kataja Susanna M. Saario Dr. Tapio Nevalainen Dr. Ari M. P. Koskinen Prof. Dr. Antti Poso Prof. Dr. 《ChemMedChem》2010,5(2):213-231
Carbamates are a well‐established class of fatty acid amide hydrolase (FAAH) inhibitors. Here we describe the synthesis of meta‐substituted phenolic N‐alkyl/aryl carbamates and their in vitro FAAH inhibitory activities. The most potent compound, 3‐(oxazol‐2yl)phenyl cyclohexylcarbamate ( 2 a ), inhibited FAAH with a sub‐nanomolar IC50 value (IC50=0.74 nM ). Additionally, we developed and validated three‐dimensional quantitative structure–activity relationships (QSAR) models of FAAH inhibition combining the newly disclosed carbamates with our previously published inhibitors to give a total set of 99 compounds. Prior to 3D‐QSAR modeling, the degree of correlation between FAAH inhibition and in silico reactivity was also established. Both 3D‐QSAR methods used, CoMSIA and GRID/GOLPE, produced statistically significant models with coefficient of correlation for external prediction (R2PRED) values of 0.732 and 0.760, respectively. These models could be of high value in further FAAH inhibitor design. 相似文献
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A novel microchip heated nebulizer for atmospheric pressure chemical ionization mass spectrometry is presented. Anisotropic wet etching is used to fabricate the flow channels, inlet, and nozzle on a silicon wafer. An integrated heater of aluminum is sputtered on a glass wafer. The two wafers are jointed by anodic bonding, creating a two-dimensional version of an APCI source with a sample channel in the middle and gas channels symmetrically on both sides. The ionization is initiated with an external corona-discharge needle positioned 2 mm in front of the microchip heated nebulizer. The microchip APCI source provides flow rates down to 50 nL/min, stable long-term analysis with chip lifetime of weeks, good quantitative repeatability (RSD < 10%) and linearity (r(2) > 0.995) with linear dynamic rage of at least 4 orders of magnitude, and cost-efficient manufacturing. The limit of detection (LOD) for acridine measured with microchip APCI at flow rate of 6.2 muL/min was 5 nM, corresponding to a mass flow of 0.52 fmol/s. The LOD with commercial macro-APCI at a flow rate of 1 mL/min for acridine was the same, 5 nM, corresponding to a significantly worse mass flow sensitivity (83 fmol/s) than measured with microchip APCI. The advantages of microchip APCI makes it a very attractive new microfluidic detector. 相似文献