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Search Results: 1 - 10 of 866 matches for " Jyri-Pekka Mikkola "
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Ionic Liquid Assisted Extraction of Nitrogen and Sulphur-Containing Air Pollutants from Model Oil and Regeneration of the Spent Ionic Liquid  [PDF]
Ikenna Anugwom, P?ivi M?ki-Arvela, Tapio Salmi, Jyri-Pekka Mikkola
Journal of Environmental Protection (JEP) , 2011, DOI: 10.4236/jep.2011.26091
Abstract: Removal of air pollutants, such as nitrogen and sulphur containing compounds from a model oil (dodecane) was studied. An ionic liquid (1-ethyl-3-methylimidazolium chloride [C2mim] [Cl]) was used as an extractant. Liquid-liquid extraction by using 1-ethyl-3-methylimidazolium chloride [C2mim] [Cl] was found to be a very promising method for the removal of N- and S-compounds. This was evaluated by using a model oil (dodecane) with indole as a neutral nitrogen compound and pyridine as a basic nitrogen compound. Dibenzothiophene (DBT) was used as a sulphur compound. An extraction capacity of up to 90 wt% was achieved for the model oil containing pyridine, while only 76 wt% of indole in the oil was extracted. The extraction capacity of a model sulphur compound DBT was found to be up to 99 wt%. Regeneration of the spent ionic liquid was carried out with toluene back-extraction. A 1:1 toluene-to-IL wt ratio was performed at room temperature. It was observed that, for the spent ionic liquid containing DBT as a model compound more than 85 wt% (corresponding 3852 mg/kg) could be removed from the oil. After the second regeneration cycle, 86 wt% of the DBT was recovered from the ionic liquid to toluene. In the case of indole as the nitrogen containing species, more than 99 wt%, (corresponding to 2993 mg/kg) of the original indole was transferred from the model oil to the ionic liquid. After the first-regeneration cycle of the spent ionic liquid, 54 wt% of the indole–in-IL was transferred to toluene. Thus, both extractions of nitrogen and sulphur model compounds were successfully carried out from model oil and the back-extraction of these compounds from the ionic liquids to toluene demonstrated the proved the concept of the regeneration point of view.
Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal
Eero Salminen,Pasi Virtanen,Jyri-Pekka Mikkola
Frontiers in Chemistry , 2014, DOI: 10.3389/fchem.2014.00003
Abstract: The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat) benzalkonium [ADBA] (alkyldimethylbenzylammonium) was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs). Typically, a SILCA contains metal nanoparticles, enzymes, or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC). The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70% molar yield toward citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide.
The Challenge of Efficient Synthesis of Biofuels from Lignocellulose for Future Renewable Transportation Fuels
P?ivi M?ki-Arvela,Eero Salminen,Toni Riittonen,Pasi Virtanen,Narendra Kumar,Jyri-Pekka Mikkola
International Journal of Chemical Engineering , 2012, DOI: 10.1155/2012/674761
Abstract: Dehydration of sugars to 5-hydroxymethylfurfural (HMF) has recently been under intensive study by a multitude of research groups. On the other hand, when lignocellulosic biomass is applied as the starting material, very few studies can be found in the open literature. The direct synthesis of HMF, in line with the idea of “one-pot” synthesis strategy from lignocellulose, is demanding since the overall process should encompass dissolution, hydrolysis, and dehydration steps in a single processing unit. Ionic liquid-assisted methods to produce hydroxymethyl-furfural directly from lignocellulosic biomass are reported here together with a short overview of the most important biofuels. In reality, HMF is not suitable to be used as a single-component fuel as such, and, consequently, methods to produce HMF derivatives suitable as liquid fuels are reported. 1. Introduction The demand for renewable energy is expected to significantly increase from current levels, partially due to the depletion of fossil fuels and, also, as a result of political decisions aiming at reduced dependency on fossil resources. Among other actors, European Union (EU) has announced an ambitious goal of reaching 20% renewable energy share by 2020 [1]. In fact, the focus on the use of renewable energy is at low carbon-footprint fuels, resulting in reduced emissions of greenhouse gases to countermeasure the ever-increasing global use of fossil fuels affecting our biosphere [2]. Different sources of renewable energy such as utilization of wind and solar power, hydroelectric installations, and geothermal energy are used today. The use of biomass resources, either for direct combustion (including thermal processes such as gasification and pyrolysis) or as a source of raw material for various biological processes (fermentations; enzymatic transformation; anaerobic bacterial biogas production), as well as chemical and catalytic processes exist that aim at liquid or gaseous products. Transport sector stands for approximately one-third of the world’s primary energy-consumption currently amounting to about 500 EJ [3]. Since, for example, electric cars are not ideal for long distance transportation due to the low energy capacity of even the best batteries of today, there is a strong need to develop new liquid transportation fuel mixes. Upon formulation of renewable fuels from biomass, a general central step is to reduce the oxygen content embedded in the molecular structure of any biomass. Various liquid biofuels were already used in the beginning of the era of internal combustion engines (like
One-Pot Liquid-Phase Catalytic Conversion of Ethanol to 1-Butanol over Aluminium Oxide—The Effect of the Active Metal on the Selectivity
Toni Riittonen,Esa Toukoniitty,Dipak Kumar Madnani,Anne-Riikka Leino,Krisztian Kordas,Maria Szabo,Andras Sapi,Kalle Arve,Johan W?rn?,Jyri-Pekka Mikkola
Catalysts , 2012, DOI: 10.3390/catal2010068
Abstract: Direct catalytic valorization of bioethanol to 1-butanol over different alumina supported catalysts was studied. Thirteen (13) heterogeneous catalysts were screened in search for the optimal material composition for direct one-pot conversion of ethanol to 1-butanol. For the most promising catalyst, a 25% ethanol conversion with 80% selectivity (among liquid carbon products) to 1-butanol could be reached at 250 °C. Additionally, the reaction kinetics and mechanisms were further investigated upon use of the most suitable catalyst candidate.
Evolution of Migmatitic Granulite Complexes: implications from Lapland Granulite Belt, Part I: metamorphic geology
Pekka Tuisku,Perttu Mikkola,Hannu Huhma
Bulletin of the Geological Society of Finland , 2006,
Abstract: The Palaeoproterozoic Lapland granulite belt was juxtaposed between Archaean and Proterozoic terrains in the NE part of the Fennoscandian Shield concurrently with the accretion of Svecofennian arc complexes at ~1.9 Ga. The belt consists mainly of aluminous migmatiticmetagreywackes. Abundant noritic to enderbitic magmas were intruded concordantly into the metasediments and were probably an important heat source for metamorphism, which took place during the crystallization of the magmas. This is supported by structural and contact relations of metasediments and igneous rocks, and by the lack progressive metamorphic reaction textures in the igneous rock series. The peak of metamorphism took place above the dehydration melting temperature of the biotite-sillimanite-plagioclase-quartz assemblageat 750 850°C and 5 8.5 kbar which lead to formation of a restitic palaeosome and peraluminous granitic melt in metapelites. Subsequently, the rocks were decompressed and cooled below the wet melting temperature of pelitic rocks (650°C) under the stability field of andalusite coexisting with potassium feldspar (2 3 kbar). Cooling was accompanied by the crystallization of the neosomes, often carrying aluminium-rich phases. Postmetamorphic duplexing of the LGB is clearly seen in the distribution of calculated PT conditions.
The rise of eversion techniques in lepidopteran taxonomy (Insecta: Lepidoptera)
K. Mikkola
SHILAP Revista de Lepidopterología , 2007,
Abstract: Durante las últimas décadas del siglo veinte, un nuevo paso para la manera tradicional de realizar las preparaciones microscópicas de los lepidópteros fue adoptada extensamente, la técnica de inflar y adaptar las zonas blandas de las genitalias internas. Mejora considerablemente, la revisión de la solución taxonómica en los grupos de especies problemáticas, particularmente las relaciones alopátricas. Al mismo tiempo, se ha revisado la conocida hipótesis llave-cerradura, ya que generalmente los sexos muestran los detalles estructurales correspondientes en sus genitalias. Sobre la base de los estudios intercontinentales de los Noctuidae, se considera que la divergencia de sus genitalias en especies gemelas, está basada en la tendencia genética. Se revisa la historia de la técnica de la eversión.
Distortion Analysis Toolkit—A Software Tool for Easy Analysis of Nonlinear Audio Systems
Pakarinen Jyri
EURASIP Journal on Advances in Signal Processing , 2010,
Abstract: Several audio effects devices deliberately add nonlinear distortion to the processed signal in order to create a desired sound. When creating virtual analog models of nonlinearly distorting devices, it would be very useful to carefully analyze the type of distortion, so that the model could be made as realistic as possible. While traditional system analysis tools such as the frequency response give detailed information on the operation of linear and time-invariant systems, they are less useful for analyzing nonlinear devices. Furthermore, although there do exist separate algorithms for nonlinear distortion analysis, there is currently no unified, easy-to-use tool for rapid analysis of distorting audio systems. This paper offers a remedy by introducing a new software tool for easy analysis of distorting effects. A comparison between a well-known guitar tube amplifier and two commercial software simulations is presented as a case study. This freely available software is written in Matlab language, but the analysis tool can also run as a standalone program, so the user does not need to have Matlab installed in order to perform the analysis.
Distortion Analysis Toolkit—A Software Tool for Easy Analysis of Nonlinear Audio Systems
Jyri Pakarinen
EURASIP Journal on Advances in Signal Processing , 2010, DOI: 10.1155/2010/617325
Abstract: Several audio effects devices deliberately add nonlinear distortion to the processed signal in order to create a desired sound. When creating virtual analog models of nonlinearly distorting devices, it would be very useful to carefully analyze the type of distortion, so that the model could be made as realistic as possible. While traditional system analysis tools such as the frequency response give detailed information on the operation of linear and time-invariant systems, they are less useful for analyzing nonlinear devices. Furthermore, although there do exist separate algorithms for nonlinear distortion analysis, there is currently no unified, easy-to-use tool for rapid analysis of distorting audio systems. This paper offers a remedy by introducing a new software tool for easy analysis of distorting effects. A comparison between a well-known guitar tube amplifier and two commercial software simulations is presented as a case study. This freely available software is written in Matlab language, but the analysis tool can also run as a standalone program, so the user does not need to have Matlab installed in order to perform the analysis.
Diagnosis-related groups (DRGs) in Finnish Hospital Care
Mikkola H,Linna M
Revue Médicale de l'Assurance Maladie , 2002,
Abstract: The hospital districts in Finland determine the pricing of hospital services without any national guidelines. However, over the last few years the use of the DRG (Diagnosis-Related Groups) based pricing system has expanded in Finland. The aim of this article was to explore the use of DRGs in hospital care and to discuss the experiences and potential problems associated with DRGs in the Finnish context. We reviewed studies analysing the impacts of the DRG system in Finland. In order to discover the current and planned use of DRGs in various applications, we sent a questionnaire to all hospital districts in Finland. A clear majority of the hospital districts, 13 out of 20, already use DRGs in their internal reporting and management. DRG-based pricing systems were used in 6 hospital districts, covering 45% of the entire population in Finland, and several others were planning to use DRGs for pricing and contracting in the near future. The motivation for the use of DRGs has had a practical basis, mainly for simplifying product definitions used in hospital management. The adoption of DRGs may have partly been associated with a ‘signalling game’ between hospitals and municipalities whereby hospital administrations signal that they are seriously concerned with efficiency issues. In the near future, DRGs will play an increasingly important role in assisting Finnish municipalities to compare quality, costs and prices of services among hospitals.
Chaos in the one-dimensional gravitational three-body problem
Jarmo Hietarinta,Seppo Mikkola
Physics , 1993, DOI: 10.1063/1.165984
Abstract: We have investigated the appearance of chaos in the 1-dimensional Newtonian gravitational three-body system (three masses on a line with $-1/r$ pairwise potential). We have concentrated in particular on how the behavior changes when the relative masses of the three bodies change (with negative total energy). For two mass choices we have calculated 18000 full orbits (with initial states on a $100\times 180$ lattice on the Poincar\'e section) and obtained dwell time distributions. For 105 mass choices we have calculated Poincar\'e maps for $10\times 18$ starting points. Our results show that the Poincar\'e section (and hence the phase space) divides into three well defined regions with orbits of different characteristics: 1) There is a region of fast scattering, with a minimum of pairwise collisions and smooth dependence on initial values. 2) In the chaotic scattering region the interaction times are longer, and both the interaction time and the final state depend sensitively on the starting point on the Poincar\'e section. For both 1) and 2) the initial and final states consists of a binary + single particle. 3) The third region consists of quasiperiodic orbits where the three masses are bound together forever. At the center of the quasiperiodic region there is the periodic Schubart orbit, whose stability turns out to correlate strongly with the global behavior.
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