Hydrogen release from liquid organic hydrogen carriers catalysed by platinum on rutile-anatase structured titania.

A liquid organic hydrogen carrier (LOHC) is an interesting concept for hydrogen storage. We describe herein a new, active catalyst system for dehydrogenation of perhydrogenated dibenzyl toluene (H18-DBT), which is a promising LOHC candidate. Pt supported on a rutile-anatase form of titania was found to be more active than Pt supported on anatase-only titania, or on alumina, and almost equally active as Pt supported on carbon. Robust and durable metal oxide supports are preferred for catalysing reactions at high temperatures.

Development of a highly controlled gas-phase nanoparticle generator for inhalation exposure studies.

We have developed a gas-phase nanoparticle generator that produces stable and well-defined size distributions for TiO(2). The online analyses of the gas-phase compounds and total number concentration of the generated particles as well as the off-line analysis of the filter samples confirmed the stability of the production. The major advantage of this reactor is that the test substance is directly in the aerosol phase, and thus no preprocessing is needed. This eliminates the physicochemical changes between bulk and administrated material during storing or processing. This system is easy to adjust to different experimental setups and precursors. As a result, well-characterized nanomaterials for inhalation exposure studies can be produced. At mass concentration of 30 mg/Nm(3), the count mean diameter was 126 nm (geometric SD 1.6), mass mean diameter was 161 nm (2.0), mass median aerodynamic diameter was 125 nm, and the concentrations of harmful gas-phase by-products remained low. The produced powder consisted of crystals of anatase (77 vol%) and brookite (23 vol%), and its specific surface area was 69 m(2)/g.

Estimation of the wavelength-dependent effective refractive index of spherical plastic pigments in a liquid matrix.

Refractive-index data are important for the prediction of light scattering from spherical pigments. Reflectance from a slurry that contains plastic pigments was studied with the aid of a reflectometer. The effective refractive index of spherical plastic pigments in a slurry was determined by use of reflectance data and a phase-retrieval procedure based on the maximum-entropy method. This method provides a simple way to estimate the effective refractive index of pigments in a liquid matrix.

Trace and heavy metal analyses of a skeletal population representing the town people in Turku (Abo), Finland in the 16th-17th centuries: with special reference to gender, age and social background.

The Julin site in the city of Turku, Finland, was excavated in 1964, 1983-1985 and 1987. On this site are the remains of the church of the Holy Spirit with its cemetery. The burial period of the excavated skeletons lasted most probably from the 1580s to the 1650s. Sodium, phosphorus, calcium, manganese, iron, copper, zinc, bromine, strontium and lead concentrations of ribs from skeletal remains of 141 individuals were analyzed. The main finding is that the concentrations of Sr and Zn in younger women tend to be lower than that in men of a corresponding age, and in older people both the strontium and zinc values tend to be higher in women than men. On the basis of this study the Pb exposure in the early modern population in Finland was at a very low level. We conclude that the role of migration and the source of grain supply on the variation of the elemental values are more difficult to evaluate than the role of diagenesis.

Colloid cysts of the third ventricle: correlation of MR and CT findings with histology and chemical analysis.

Eight patients with colloid cysts of the third ventricle were examined with CT and MR. In six, surgical resection was performed and the material was subjected to histologic evaluation; the concentrations of trace elements were determined by particle-induced X-ray emission. Stereotaxic aspiration was performed in two. The investigation showed that colloid cysts are often iso- or hypodense relative to brain on CT (5/8), but sometimes have a center of increased density. Increased density did not correlate with increased concentration of calcium or other metals but did correlate with high cholesterol content. Colloid cysts appear more heterogeneous on MR (6/8) than on CT (3/8), despite a homogeneous appearance at histology. High signal on short TR/TE sequences is correlated with a high cholesterol content. A marked shortening of the T2 relaxation time is often noticed in the central part of the cyst. Analysis of trace elements showed that this phenomenon is not related to the presence of metals with paramagnetic effects. Our analysis of the contents of colloid cysts does not support the theory that differing metallic concentrations are responsible for differences in MR signal intensity or CT density. We did find that increased CT density and high MR signal correlated with high cholesterol content.

Colloid cysts of the third ventricle: correlation of MR and CT findings with histology and chemical analysis.

Eight patients with colloid cysts of the third ventricle were examined with CT and MR. In six, surgical resection was performed and the material was subjected to histologic evaluation; the concentrations of trace elements were determined by particle-induced X-ray emission. Stereotaxic aspiration was performed in two. The investigation showed that colloid cysts are often iso- or hypodense relative to brain on CT (5/8), but sometimes have a center of increased density. Increased density did not correlate with increased concentration of calcium or other metals but did not correlate with high cholesterol content. Colloid cysts appear more heterogeneous on MR (6/8) than on CT (3/8), despite a homogeneous appearance at histology. High signal on short TR/TE sequences is correlated with a high cholesterol content. A marked shortening of the T2 relaxation time is often noticed in the central part of the cyst. Analysis of trace elements showed that this phenomenon is not related to the presence of metals with paramagnetic effects. Our analysis of the contents of colloid cysts does not support the theory that differing metallic concentrations are responsible for differences in MR signal intensity or CT density. We did find that increased CT density and high MR signal correlated with high cholesterol content.

Proton microprobe and particle induced X-ray emission (PIXE) analysis for studies of pathological brain tissue.

Particle Induced X-ray Emission and proton microprobe analyses have been applied for the investigation of regional elemental distributions in connection with various pathological states in the brain. Malignant brain tumours and adjacent histologically intact tissue removed during surgery were analysed with PIXE. Systematic elemental variations, e.g., for calcium and selenium, were observed in the tumour front. The proton microprobe was applied to study the Ca and K concentrations in various cell strata in hippocampus following transient ischaemia in rat brain. Significant increases in the Ca level occurred in selectively vulnerable cells within 48 h after the ischaemia.