Publications by authors named "Kokkonen E"

The methanol-to-hydrocarbons (MTH) process involves the conversion of methanol, a C1 feedstock that can be produced from green sources, into hydrocarbons using shape-selective microporous acidic catalysts - zeolite and zeotypes. This reaction yields a complex mixture of species, some of which are highly reactive and/or present in several isomeric forms, posing significant challenges for effluent analysis. Conventional gas-phase chromatography (GC) is typically employed for the analysis of reaction products in laboratory flow reactors.

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This work employs ambient pressure X-ray photoelectron spectroscopy (APXPS) to delve into the atomic and electronic transformations of a core-shell Ni@NiO/NiCO photocatalyst - a model system for visible light active plasmonic photocatalysts used in water splitting for hydrogen production. This catalyst exhibits reversible structural and electronic changes in response to water vapor and solar simulator light. In this study, APXPS spectra were obtained under a 1 millibar water vapor pressure, employing a solar simulator with an AM 1.

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The Ambient-Pressure X-ray Photoelectron Spectroscopy (APXPS) endstation at the SPECIES beamline at MAX IV Laboratory has been improved. The latest upgrades help in performing photo-assisted experiments under operando conditions in the mbar pressure range using gas and vapour mixtures whilst also reducing beam damage to the sample caused by X-ray irradiation. This article reports on endstation upgrades for APXPS and examples of scientific cases of in situ photocatalysis, photoreduction and photo-assisted atomic layer deposition (photo-ALD).

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Ambient pressure x-ray photoelectron spectroscopy (APXPS) can provide a compelling platform for studying an analyte's oxidation and reduction reactions in solutions. This paper presents proof-of-principle operando measurements of a model organometallic complex, iron hexacyanide, in an aqueous solution using the dip-and-pull technique. The data demonstrates that the electrochemically active liquid meniscuses on the working electrodes can undergo controlled redox reactions which were observed using APXPS.

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The synthesis of high-value fuels and plastics starting from small hydrocarbon molecules plays a central role in the current transition towards renewable energy. However, the detailed mechanisms driving the growth of hydrocarbon chains remain to a large extent unknown. Here we investigated the formation of hydrocarbon chains resulting from acetylene polymerization on a Ni(111) model catalyst surface.

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Atomic layer deposition (ALD) is one of the backbones for today's electronic device fabrication. A critical property of ALD is the layer-by-layer growth, which gives rise to the atomic-scale accuracy. However, the growth rate - or growth per cycle - can differ significantly depending on the type of system, molecules used, and several other experimental parameters.

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An ambient pressure cell is described for conducting synchrotron-based x-ray photoelectron spectroscopy (XPS) measurements during atomic layer deposition (ALD) processes. The instrument is capable of true in situ and operando experiments in which it is possible to directly obtain elemental and chemical information from the sample surface using XPS as the deposition process is ongoing. The setup is based on the ambient pressure XPS technique, in which sample environments with high pressure (several mbar) can be created without compromising the ultrahigh vacuum requirements needed for the operation of the spectrometer and the synchrotron beamline.

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Tuning the anisotropy through exchange bias in bimagnetic nanoparticles is an active research strategy for enhancing and tailoring the magnetic properties for a wide range of applications. Here we present a structural and magnetic characterization of unique FeCr-oxide nanoparticles generated from seed material with a Fe : Cr ratio of 4.71 : 1 using a physical aerosol method based on spark ablation.

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An experimental approach is described in which well-defined perturbations of the gas feed into an Ambient Pressure X-ray Photoelectron Spectroscopy (APXPS) cell are fully synchronized with the time-resolved x-ray photoelectron spectroscopy data acquisition. These experiments unlock new possibilities for investigating the properties of materials and chemical reactions mediated by their surfaces, such as those in heterogeneous catalysis, surface science, and coating/deposition applications. Implementation of this approach, which is termed perturbation-enhanced APXPS, at the SPECIES beamline of MAX IV Laboratory is discussed along with several experimental examples including individual pulses of N gas over a Au foil, a multi-pulse titration of oxygen vacancies in a pre-reduced TiO single crystal with O gas, and a sequence of alternating precursor pulses for atomic layer deposition of TiO on a silicon wafer substrate.

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The SPECIES beamline has been transferred to the new 1.5 GeV storage ring at the MAX IV Laboratory. Several improvements have been made to the beamline and its endstations during the transfer.

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An in-depth understanding of the reaction mechanism is required for the further development of Mo-based catalysts for biobased feedstocks. However, fundamental studies of industrial catalysts are challenging, and simplified systems are often used without direct comparison to their industrial counterparts. Here, we report on size-selected bimetallic NiMo nanoparticles as a candidate for a model catalyst that is directly compared to the industrial system to evaluate their industrial relevance.

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This study aimed to evaluate the suitability of two bioaerosol generation systems (dry and wet generation) for the aerosolization of microorganisms isolated from the International Space Station, and to calibrate the produced bioaerosols to fulfill the requirements of computational fluid dynamics model (CFD) validation. Concentration, stability, size distribution, agglomeration of generated bioaerosol and deposition of bioaerosols were analyzed. In addition, the dispersion of non-viable particles in the air was studied.

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Photon-induced fragmentation of a full set of chlorinated methanes (CHCl, CHCl, CHCl, CCl) has been investigated both experimentally and computationally. Using synchrotron radiation and electron-ion coincidence measurements, the dissociation processes were studied after chlorine 2p electron excitation. Experimental evidence for CHCl and CHCl contains unique features suggesting that fast dissociation processes take place.

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In many cases fragmentation of molecules upon inner-shell ionization is very unspecific with respect to the initially localized ionization site. Often this finding is interpreted in terms of an equilibration of internal energy into vibrational degrees of freedom after Auger decay. We investigate the X-ray photofragmentation of ethyl trifluoroacetate upon core electron ionization at environmentally distinct carbon sites using photoelectron-photoion-photoion coincidence measurements and ab initio electronic structure calculations.

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Ultraviolet light induced photofragmentation of mercury compounds is studied experimentally with electron energy resolved photoelectron-photoion coincidence techniques and theoretically with computational quantum chemical methods. A high resolution photoelectron spectrum using synchrotron radiation is presented. Fragmentation of the molecule is studied subsequent to ionization to the atomic-mercury-like d orbitals.

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The effect of the spin-orbit interaction to photofragmentation is investigated in the mercury(II) bromide (HgBr2) molecule. Changes in the fragmentation between the two spin-orbit components of Hg 5d photoionization, as well as within the molecular-field-splitted levels of these components are observed. Dissociation subsequent to photoionization is studied with synchrotron radiation and photoelectron-photoion coincidence spectroscopy.

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Vitamin D binding protein (DBP)/group-specific component (Gc), correlates positively with serum vitamin D metabolites, and phenotype influences serum 25-hydroxyvitamin D (S-25(OH)D) concentration. The protein isoform has been associated with decreased bone mineral density (BMD) and increased fracture risk. We examined the role of GC genotypes in S-25(OH)D status and BMD in 231 Finnish children and adolescents aged 7-19 yr.

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Background: Reticulate pigmentary disorders include the rare autosomal dominant Galli-Galli disease (GGD) and Dowling-Degos disease (DDD). Clinical diagnosis between some of the subtypes can be difficult due to a degree of overlap between clinical features, therefore analysis at the molecular level may be necessary to confirm the diagnosis.

Objectives: To identify the underlying genetic defect in a 48-year-old Asian-American woman with a clinical diagnosis of GGD.

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Background: Dietary phosphorus (P) intake in Western countries is 2- to 3-fold higher than recommended, and phosphate is widely used as a food additive in eg. cola beverages and processed meat products. Elevated serum phosphate concentrations have been associated with cardiovascular disease (CVD) risk factors and CVD itself in several studies in patients with renal dysfunction and in a few studies in the general population.

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Objective: To assess differences in the use of electronic medical records (EMRs) among medical specialties and practice settings.

Methods: A cross-sectional retrospective study using nationally representative data from the National Ambulatory Medical Care Survey for the period 2003-2010 was performed. Bivariate and multivariate analyzes compared EMR use among physicians of 14 specialties and assessed variation by practice setting.

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To ascertain the influence of juvenile-onset chronic physical diseases and associating factors of social environment on delayed social maturation and mental health disorders in young adults, we analysed a group of 407 (184 female, 223 male) subjects with these conditions and compared the results with those of 123 (63 female, 60 male) healthy controls studied at the age of 19-25 years. The social maturation index was formed on the basis of a demographic interview, which also reviewed the state of social development and the family situation during childhood. Mental health disorders were assessed with a Present State Examination (PSE) interview analysed with the CATEGO program.

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To assess whether juvenile-onset epilepsy or motor disability is complicated by an increased number of mental health disorders or experience of psychosomatic symptoms in young adulthood, we studied 81 subjects with epilepsy and 52 with motor disabilities at the age of 19 to 25 years and compared them with 211 controls. The main diagnostic tool, the Present State Examination, was administered to those attending the interviews in person who were of normal intelligence; there were 62, 38, and 123 subjects in the three categories, respectively. Compared with the controls, the subjects with epilepsy showed an equal prevalence of psychiatric disorders whereas those with motor disabilities had a significantly higher prevalence, particularly of depressive disorders.

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Objective: To evaluate social maturation and psychiatric morbidity in young adults treated for epilepsy during their childhood.

Methods: Eighty one young adults (43 women, 38 men, mean age 22.3 years) with epilepsy during their childhood were interviewed about their social development and psychiatric symptoms.

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To find out whether a long-term physical illness since childhood increases the risk of experiencing psychological and somatic symptoms, we interviewed a group of 487 patients aged 20-25 years and compared these findings to 211 controls. Both somatic (chi 2 = 9.11, d.

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To find out whether long-term physical disorders in childhood increase the risk for mental disorder, we interviewed 407 young adults and compared their findings to a control group of 123 age-matched controls. The overall prevalence of mental disorders according to ICD-8 classification exceeded 20% in both groups. Depression and phobic disorders were the most common diagnostic syndromes, being most prevalent in women with motor handicaps or short stature.

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