E. Laine

University of Turku, Turku, Varsinais-Suomi, Finland

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Publications (90)230.27 Total impact

  • J. Salonen · V-P. Lehto · E. Laine ·

    MRS Online Proceeding Library 01/2011; 485. DOI:10.1557/PROC-485-79
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    ABSTRACT: We have studied chemical stability of thermally-carbonized porous silicon (PS). The initial hydrogen termination of PS has been replaced by carbon using thermal dissociation of acetelyne molecules. This kind of carbonized surface has been found to be at least as stable in humid atmosphere as a thermally-oxidized PS surface. It is also found to be stable in an aqueous KOH and HF. In-vitro studies of tissue compatible in simulated human fluid indicate improved stability and that the carbonized surface could be bioactive.
    MRS Online Proceeding Library 01/2011; 638. DOI:10.1557/PROC-638-F14.19.1

  • MRS Online Proceeding Library 01/2011; 486. DOI:10.1557/PROC-486-323
  • J. Pirttimäki · V-P. Lehto · E. Laine ·
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    ABSTRACT: Abstract The quantitative x-ray diffraction analysis offers often an exact and practical technique to determine the relative amounts of the phases of the solid in question. The sample may contain only one amorphous phase. The purpose of this paper is to estimate the suitability of this technique to quantify the phase fractions of pharmaceutical substances. Three different method were used to determine the relative amounts of phases. Methods were compared and the major sources of error were estimated. The measurements and calculations are carried out using selegilin hydrochloride, mannitol and modified starch as an example. The results show that the amount of about 2 % of selegilin hydrochloride can be observed reliably from among the mannitol (crystalline substance) or modified starch (amorphous substance). During the work it became obvious that the accuracy of these calculations can essentially be improved planning the measurements carefully.
    Drug Development and Industrial Pharmacy 10/2008; 19(19):2561-2577. DOI:10.3109/03639049309047201 · 2.10 Impact Factor
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    ABSTRACT: Electrostatic charge of lactoses of different particle morphology and amorphous contents were measured during actuation from two different dry powder inhalers (DPIs). Triboelectric studies may give important information when new inhaler devices, materials and formulations are designed in order to improve the drug deposition. Two inhalers, Taifun (Focus Inhalation Oy, Finland) and Clickhaler (Innovata Biomed Ltd., UK) were filled with lactose powders which were spray dried from different solutions or suspensions of lactose, ethanol and water. Differences in the amorphous contents were determined with isothermal microcalorimetry (IMC) and X-ray diffraction (XRD) and the particle morphology was examined with laser diffraction and electron microscopy (SEM). Samples were actuated from the inhalers at given intervals into the Faraday pail and the generated charges were recorded. Increase in the water concentration of the feed suspension had negligible effect on the charging until it exceeded 70%. Reproducibility of the measurement was found to be better with samples of homogenous particles and higher crystallinity while more amorphous samples with different morphology and wide particle size distribution showed change in the sign of the charge in addition to higher variations of the magnitude. In this study we show that different inhalers, as well as the morphology of the lactose powder, has noticeable effects on the generated charge which has previously been shown to affect the deposition of the drug and the function of an inhaler.
    International Journal of Pharmaceutics 10/2004; 282(1-2):107-14. DOI:10.1016/j.ijpharm.2004.06.002 · 3.65 Impact Factor
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    ABSTRACT: In the field of pharmaceutics, spray drying is often used for producing particles with predetermined qualities. Produced particles are usually insulating in nature, and this property combined with small particle size, might lead to electrostatic problems. These problems involve, for example, dust explosions, fires, reduced process efficiency and particle accumulation on the walls. In the spray drying process, the static charge might be generated in different ways: double layer charging in the feed pipe, double layer or induction charging at the spray nozzle, and contact and frictional charging at the walls of the spray cylinder and the cyclone chamber. In this paper, these charging processes are assessed using electric field measurements and Faraday pail.
    Journal of Electrostatics 09/2004; 62(1-62):63-72. DOI:10.1016/j.elstat.2004.05.001 · 0.86 Impact Factor
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    ABSTRACT: The influence of chemical reduction on the properties of bimetallic Ru-Sn/SiO2 catalyst was studied. Prepared sol-gel catalysts were reduced by NaBH4, KBH4, H2, and CH2O. Physical and catalytic properties of reduced catalysts were compared to non-reduced ones in the liquid-phase hydrogenation of cinnamaldehyde. The influence of boron impregnation was investigated. The observed hydrogenation activity and selectivity towards cinnamylalcohol were effected by reduction pretreatment. The NaBH4 reduced catalyst exhibited the highest activity and selectivity. Reduction pretreatment influenced the pore sizes, active metal surface as well as content of carbon impurities. Traces of the reduction agents were detected in the catalysts. Boron impregnation presumably improved the catalyst activity, but had a minor effect on the selectivity.
    Journal of Sol-Gel Science and Technology 05/2004; 30(3):187-195. DOI:10.1023/B:JSST.0000039504.89972.ee · 1.53 Impact Factor
  • Mikko Björkqvist · Jarno Salonen · Jaani Paski · Ensio Laine ·
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    ABSTRACT: We report the properties of a capacitance type thermally carbonized porous silicon (TC-PS) humidity sensor at room temperature. Several constructions to use porous silicon as a miniaturized humidity sensor material have been introduced earlier. In these applications, poor long-term stability of PS is most often improved by thermal oxidation. However, thermally carbonized PS surface has been found to be at least as stable in humid atmosphere, and in addition to that, the thermal carbonization also maintains the originally large specific surface area of PS. Indeed, our sensor shows good sensitivity over a wide range of relative humidity. The repeatability is excellent but the hysteresis above 60% of relative humidity should be reduced. The effect of measurement frequency on the sensitivity is also demonstrated.
    Sensors and Actuators A Physical 05/2004; 112(2-3-112):244-247. DOI:10.1016/j.sna.2004.01.002 · 1.90 Impact Factor
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    ABSTRACT: The MCM-41 mesoporous molecular sieve was modified with Ru using in-situ synthesis, ion-exchange and impregnation catalyst preparation methods. The physico-chemical properties of the Ru–MCM-41 synthesized catalysts were studied using characterisation techniques such as X-ray powder diffraction, scanning electron microscopy, energy dispersive X-ray micro-analysis, X-ray fluorescence, XPS and nitrogen adsorption. The hydrogenation of cinnamaldehyde was used as a test reaction to evaluate the catalytic properties of the Ru–MCM-41 catalysts.The in-situ synthesis, ion-exchange and impregnation methods used for the introduction of Ru did not influence the parent structure and phase purity of the MCM-41 mesoporous molecular sieve under suitable designed synthesis conditions. At the same time the method of Ru introduction in MCM-41 was found to influence the physico-chemical and catalytic properties. The Ru–MCM-41 catalyst synthesized using in-situ synthesis resulted in the largest Ru crystallite size, which provided highest selectivity to the desired product cinnamyl alcohol and lowest conversion of cinnamaldehyde in the hydrogenation. The Ru–MCM-41 catalyst prepared by impregnation showed sintering of Ru particles, and lower selectivity to cinnamyl alcohol than the in-situ synthesized Ru–MCM-41 catalyst. The Ru–MCM-41 mesoporous molecular sieve catalyst prepared by ion-exchange showed the highest conversion of cinnamaldehyde, however formation of cinnamyl alcohol was not observed.
    Microporous and Mesoporous Materials 04/2004; 69(3):173–179. DOI:10.1016/j.micromeso.2004.02.008 · 3.45 Impact Factor
  • J. Salonen · M. Björkqvist · E. Laine · L. Niinistö ·
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    ABSTRACT: A feasible route to produce hydrocarbon termination to the porous silicon (PSi) surface has been introduced using thermal decomposition of acetylene molecules. Treatment temperatures lower than 600 °C enable the use of continuous acetylene flushing during the treatment without problems arising from the graphitization of acetylene. The continuous acetylene flushing was found to significantly improve the quality and efficiency of the treatment. The decomposition process starts at low temperatures and appears to consist of three different parts as a function of temperature. It was also found that the treatment time has some effects on the treatment efficiency. The hydrocarbon terminated PSi surface was found to be hydrophobic, when the treatment temperature was below 680 °C. Due to the hydrogen desorption, the surface quickly changes to hydrophilic above 700 °C. Thermal oxidation studies of the treated surfaces show improvements in the stability against oxidation and the hydrocarbon termination was found to be very stable even in aqueous KOH environment.
    Applied Surface Science 03/2004; 225(1-4):389-394. DOI:10.1016/j.apsusc.2003.10.028 · 2.71 Impact Factor
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    ABSTRACT: A series of SAPO-11 catalyst samples were synthesized by varying source of silica and synthesis time. Products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption and FTIR spectroscopy of pyridine adsorption as well as evaluated towards 1-butene skeletal isomerization. By using waterglass as a source of silica, tridymite phase instead of SAPO-11 was obtained. The combination of colloidal silica and aluminum oxide as sources of silica and alumina resulted in SAPO-11 phase but small amounts of other phases, such as tridymite, were obtained. The number of the acid sites was observed to increase if synthesis time was prolonged indicating more silicon incorporation into the framework. Acidity and phase distribution had an influence on the conversion of 1-butene and selectivity to isobutene. The selectivity to isobutene was higher with catalysts, which contained more SAPO-11 phase.
    Applied Catalysis A General 03/2004; 259(2):227-234. DOI:10.1016/j.apcata.2003.09.038 · 3.94 Impact Factor
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    Mikko Björkqvist · Jarno Salonen · Ensio Laine ·
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    ABSTRACT: We have studied the humidity behavior of thermally carbonized (TC) p+-type porous silicon (PS) samples as a function of carbonization temperature. The Fourier transform infrared (FTIR) spectroscopy and gas adsorption measurements indicate that the bond configuration and structure of thermally carbonized porous silicon surface are highly dependent on carbonization temperature. Moreover, the surface affects on the stability of porous silicon but also significantly on its humidity behavior. The porous silicon samples carbonized at or below 650°C remain hydrophobic, while the temperature of 730°C was high enough to produce a hydrophilic surface. The water sorption rate in thermally carbonized porous silicon samples was quite slow, however, this was interpreted to be mostly a consequence of a thick sample. Hygroscopicity was studied by measuring the weight of the sample under various relative humidity values, and also by using isothermal microcalorimeter (IMC). For humidity sensor purposes, we also studied the effect of water adsorption on electrical parameters of thermally carbonized porous silicon layer. The changes of resistance and capacitance were observed both for hydrophobic and hydrophilic surface.
    Applied Surface Science 01/2004; 222(1):269-274. DOI:10.1016/j.apsusc.2003.08.025 · 2.71 Impact Factor

  • Microporous and Mesoporous Materials 01/2004; 69(null):173. · 3.45 Impact Factor
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    ABSTRACT: Ru-modified MCM-41 mesoporous molecular sieve and Y zeolite catalysts were synthesised and characterised using XRD, electrochemical voltammetry, ESCA (XPS), nitrogen adsorption and H2-TPD. Selective liquid-phase hydrogenation of cinnamaldehyde to cinnamyl alcohol was investigated over these catalysts and compared to hydrogenation on a commercial Ru/C catalyst. The effect of support (MCM-41, Y and C), solvent (cyclohexane, hexane and 2-propanol) and catalyst pre-treatment (calcination) on the conversion of cinnamaldehyde and selectivity to cinnamyl alcohol was studied. The zeolite structure, pore size, acidity, catalyst pre-treatment as well as the solvent influenced the activity and selectivity. Non-calcined Ru/Y exhibited the highest selectivity to cinnamyl alcohol. The activity of Ru/Y was highest with 2-propanol as a solvent.
    Applied Catalysis A General 09/2003; 251(2):385-396. DOI:10.1016/S0926-860X(03)00345-4 · 3.94 Impact Factor
  • Matti Murtomaa · Satu Strengell · Ensio Laine · Adrian Bailey ·
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    ABSTRACT: This paper describes an electrostatic grid-probe which can be used to study the charge of an aerosol emitted from a dry powder inhaler (DPI). Electrostatic charge plays a significant role in the function of an inhaler, separation of the drug and additive particles, and drug deposition in the lungs. The measurement system consists of three conducting grids through which the charged aerosol passes. The outer ones are connected to earth and the one in the middle is connected to an electrometer and a PC. Charge inside the probe induces a potential to the middle grid which is recorded as a function of time. When the distance between the grids is relatively small, the probe gives information about the charge distribution as a function of time. Therefore, the probe can be used to study whether the drug and additive particles are emitted separately from the DPI and the charge levels of both compounds.Measurements have been performed using several example powders and mixtures. Results show that the probe can separate signals from the drug and additive particles. Care has to be taken in interpreting the signals due to particles colliding with the grid and exchanging charge with it. Results were also verified by separating the aerosol physically using a high electric field separator. Separated particles were identified optically and also by using a differential scanning calorimeter.
    Journal of Electrostatics 06/2003; 58(3):197-207. DOI:10.1016/S0304-3886(03)00048-2 · 0.86 Impact Factor
  • M. Björkqvist · J. Salonen · E. Laine ·
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    ABSTRACT: We have determined the thickness of an oxide layer at the p+-type porous silicon interface as a function of oxidation time, by using a small angle X-ray scattering (SAXS). The scattering experiments were carried out using a Kratky camera with a step-scanning device. Oxidation was achieved by storing the porous silicon samples in various temperatures under high relative humidity. The negative deviations from Porod's law were observed from the scattering curves of oxidized samples. The oxide layer thickness was determined from the scattering curve using a sigmoidal-gradient approximation for the diffuse boundary. The oxide layer thickness values as a function of oxidation time, obtained using SAXS are compared to measured weight increase values, caused by the oxidation.
    Journal of Applied Crystallography 06/2003; 36(3‐1). DOI:10.1107/S0021889803000165 · 3.72 Impact Factor
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    ABSTRACT: The role of copper was studied in the skeletal isomerization of 1-butene over copper-modified mesoporous MCM-41 molecular sieve and Beta zeolite. The Cu–H-MCM-41 and Cu–H-Beta catalysts were synthesized in our laboratory and characterized by XRD, nitrogen adsorption, X-ray fluorescence, FTIR of adsorbed pyridine and direct current plasma atomic emission spectrometry. The oxidation state of copper after oxidation and reduction in Cu–H-MCM-41 was evaluated by FTIR with probe molecules. Copper ion-exchanged and the proton forms of MCM-41 and Beta catalysts were tested towards 1-butene skeletal isomerization by varying the weight hourly space velocity and temperature. Quantum chemical calculations at the B3LYP/6-31 + G** level were performed in order to understand the role of copper at the molecular level.Copper in Cu–H-MCM-41 pretreated in synthetic air was mostly in the form of Cu2+ but reduced during the catalytic experiment to the metallic form Cu0 via Cu+. Even if the copper exchange decreased the amount of Brønsted acid sites, Cu–H-MCM-41 pretreated in synthetic air was more active than H-MCM-41 towards 1-butene skeletal isomerization. The enhanced catalytic activity is due to copper Cu+, which was formed during the reaction. Introduction of copper into H-Beta, however, did not have any effect at all on the performance of the catalyst. The probable reason for this is the high initial activity of copper-modified H-Beta causing a very fast reduction of copper to the inactive metallic form Cu0.
    Microporous and Mesoporous Materials 06/2003; 60(1-3):159-171. DOI:10.1016/S1387-1811(03)00337-8 · 3.45 Impact Factor
  • M. Björkqvist · J. Salonen · E. Laine · L. Niinistö ·
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    ABSTRACT: The stabilities of porous silicon samples after thermal oxidation, thermal carbonization, thermal nitridation and dodecene-treatment have been compared. The stability of these samples in different temperatures and RH-atmospheres was examined by measuring the weight increase as a function of time. Also, the reactivity of the stabilized porous silicon samples in ethanol and KOH-solution at 25 °C was measured using an isothermal microcalorimeter. Other important properties of stabilized porous silicon samples for sensing applications, such as a specific surface area and a humidity adsorption behavior have also been compared.
    physica status solidi (a) 05/2003; 197(2):374 - 377. DOI:10.1002/pssa.200306528 · 1.21 Impact Factor
  • J. Salonen · E. Laine · L. Niinistö ·
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    ABSTRACT: Hydrosilylation of 1-dodecene on porous silicon surface has been studied by calorimetric methods. Using unpurified and purified 1-dodecene, it was possible to distinguish the reactions arising from oxidation from those due to hydrosilylation reactions. A surprising change from an exothermic reaction to an endothermic one was observed above 130 °C. A possible origin for this has been proposed, based on breaking of the double bond in the 1-dodecene molecule leaving CHx-termination on the PSi surface. The density functional calculations and measured FTIR spectra are presented as supporting evidence for the explanation given.
    physica status solidi (a) 05/2003; 197(1):246-250. DOI:10.1002/pssa.200306509 · 1.21 Impact Factor
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    ABSTRACT: Pd-Y- and Pd-Zr-Y-zeolite catalysts were prepared by the ion-exchange of parent NH3-Y-zeolite, thermally pre-treated Y-zeolite and hydrothermally pre-treated Y-zeolite. The activity of the catalysts was studied in conversion of gas mixtures simulating the flue gases from the combustion of biofuels and natural gas driven vehicles (NGVs) at temperature ranges of 120–800 °C. The effect of sulphur-poisoning was examined by the addition of 5 ppm SO2 into the feed gas mixtures. High activity in the removal of the model pollutants was obtained over the fresh catalysts. De-activation was observed as a result of catalyst ageing in the reactants’ flow (800 °C, 6 h) or steam treatment (850 °C, 12 vol.% H2O, 16 h). The de-activation was attributed to the de-alumination as well as to the migration of Pd2+ cations. The catalysts were characterised by XRD, SEM–EDXA, N2-physisorption, O2/SO2/NH3/naphthalene-TPD, XRF and DCP.
    Applied Catalysis A General 01/2003; 239(1-2):229-240. DOI:10.1016/S0926-860X(02)00386-1 · 3.94 Impact Factor