Abstract: Gallium oxide nanorods with unprecedented small dimensions (20-80nm length and 3-5nm width) were prepared using a novel, template-free synthesis method. This nanomaterial is an excellent heterogeneous catalyst for the sustainable epoxidation of alkenes with H2O2, rivaling the industrial benchmark microporous titanosilicate TS-1 with linear alkenes and being much superior with bulkier substrates. A thorough characterization study elucidated the correlation between the physicochemical properties of the gallium oxide nanorods and their catalytic performance, and underlined the importance of the nanorod morphology for generating a material with high specific surface area and a high number of accessible acid sites.

Abstract: MFI zeolite nanosheets with thickness of 2 and 8 nm were synthesized, transformed into bifunctional catalysts by loading with platinum and tested in n-decane isomerization and hydrocracking. Detailed analysis of skeletal isomers and hydrocracked products revealed that the MFI nanosheets display transition-state shape-selectivity similar to bulk MFI zeolite crystals. The suppressed formation of bulky skeletal isomers and C5 cracking products are observed both in the nanosheets and the bulk crystals grown in three dimensions. This is typical for restricted transition-state shape-selectivity, characteristic for the MFI type pores. It is a first clear example of transition-state shape-selectivity inside a zeolitic nanosheet. Owing to the short diffusion path across the sheets, expression of diffusion-based discrimination of reaction products in the MFI nanosheets was limited. The 2-methylnonane formation among monobranched C10 isomers and 2,7-dimethyloctane among dibranched C10 isomers, which in MFI zeolite are favored by product diffusion, was much less favored on the nanosheets compared to the reference bulk ZSM-5 material.

Abstract: A new sol-gel synthesis procedure is proposed for the preparation of MoVSbOx catalysts for the selective oxidation of isobutane. Physico-chemical characterization of the materials calcined at 400 degreesC, showed essentially amorphous catalysts, with long-range order. Increase of calcination temperature, however, resulted in the formation of small crystalline regions, confirmed through TEM. EPR measurements on the calcined samples pointed to the presence of isolated and magnetically interacting V(IV) species. The reported catalysts proved to be much more selective for partial oxidation compared to a literature reference catalyst. Furthermore, it is shown that this versatile synthesis recipe forms an excellent start for high-throughput and combinatorial studies. (C) 2004 Elsevier B.V. All rights reserved.

Abstract: Porous solids with organized multiple porosity are of scientific and technological importance for broadening the application range from traditional areas of catalysis and adsorption/separation to drug release and biomedical imaging. Synthesis of crystalline porous materials offering a network of uniform micro- and mesopores remains a major scientific challenge. One strategy is based on variation of synthesis parameters of microporous networks, such as, for example, zeolites or metal organic frameworks (MOFs). Here, we show the rational development of an hierarchical variant of the microporous cubic Cu-3(BTC)(2) (BTC = 1,3,5-benzenetricarboxylate) HKUST-1 MOF having strictly repetitive S inn wide mesopores separated by uniform microporous walls in a single crystal structure. This new material coined COK-15 (COK = Centrum voor Oppervlaktechemie en Katalyse) was synthesized via a dual-templating approach. Stability was enhanced by Keggin type phosphotungstate (HPW) systematically occluded in the cavities constituting the walls between the mesopores.

Abstract: Historical buildings and castles that have been turned nowadays into museums, as an exhibition area for precious cultural heritage (CH) items, need more attention since they are CH objects by themselves. Moreover, the preservation techniques require often, significant interventions; however such changes are not always possible or are very limited. The aim of the present study was to investigate the influence of outdoor air pollution on the composition of particulate matter and gases inside the museum of Wawel Castle in Cracow, Poland. During this study a combination of micro and trace analysis techniques were applied, including energy dispersive X-ray fluorescence (EDXRF) and electron probe microanalysis (EPMA). An intensive transport of air pollutants coupled with accumulation of the particles inside the museum was noticed (considerably higher in winter than summer). A high content of carbon and organic matter agglomerated with inorganic particles was determined. Those particles are of special concern because of their adhesive properties and reactivity. It was also noted that the conditions inside the museum favour the reaction of the particles with gaseous pollutants. It was especially the case for nitrate particles.

Abstract: Composition of the prehistoric pigments (from Carriqueo rock shelter, Rio Negro province, Argentina) has been analysed by means of molecular spectroscopy (Fourier transform infrared (FTIR) and micro-Raman) and scanning electron microscopy (SEM) coupled to an energy-dispersive X-ray spectrometer (EDS). Red and yellow pigments were recognized as red and yellow ochre. The matrix of the pigments is composed of one or more substances. According to the matrix composition yellow and red pigments were also divided into two groupsi.e. those containing kaolinite or sulphates. Green pigment was detected as green earth, made up of celadonite as a chromophore.

Abstract: The strategies for sampling and analysis by SEM/EDX and micro-Raman spectrometry for individual airborne particles analysis as applied at the University of Antwerp (Belgium) by the MITAC group have been reviewed. Microbeam techniques provide detailed information concerning the origin, formation, transport, reactivity, transformation reactions and environmental impact of particulate matter. Moreover, some particles of certain chemical properties have been recognized as a threat for human health and cultural heritage objects. However, the small sizes of particles result in specific problems with respect to single particle analysis. Development of equipment and software for improvement of analysis and quantification are reported.

Abstract: As swipe samples from enrichment activities typically contain uranium particles with a detectable amount of fluorine, the question was raised whether the analysis of fluorine in particles could complement the information on the uranium isotope ratios. For this, uranium oxyfluoride particles were prepared from the controlled hydrolysis of uranium hexafluoride (UF6). The relative amount of fluorine was characterized by scanning electron microscopy combined with energy-dispersive X-ray spectrometry (SEM-EDX), as well as ion-microprobe secondary ion mass spectrometry (IM-SIMS). Of particular interest was the assessment of the reduction of the amount of fluorine over time, and after exposure to UV-light and high temperatures. Micro-Raman spectrometry (MRS) was applied to look for differences in molecular structure between these various sample types. Both SEM-EDX and IM-SIMS showed a general reduction of the fluorine-to-uranium ratio after 12 years of storage. The exposure to UV-light and high temperatures was found to have accelerated the loss of fluorine. A distinct peak at 865 cm− 1 Raman shift was detected for the majority of particles analyzed by MRS. For the particles that were heat-treated, the Raman spectra were similar to the spectrum of U3O8. Although often large variations were observed between particles from the same sample, the three particle measurement techniques (IM-SIMS, SEM-EDX and MRS) showed some consistent trends. They therefore appear promising in terms of the ability to place bounds on particle age, as well as shedding light on the complex processes involved in UO2F2 particle ageing.

Abstract: In this study, we show the trends in the concentration Of SO2 and particulate matter (PM) in two health resorts, located in the tri-border region of Poland, Germany and Czech Republic. We analyze the annual time series and the seasonal variability of PM concentration for the months of July and February over the period of 1996-2007. Additionally, in July 2006, we measured the mean 24-hour concentration of PM and the content of heavy metals (by EDXRF analysis). We prove that nowadays air pollution in this region has diminished to a large extent as compared to the 90s of the last century. In Cieplice, the local influence is still evident; while Czerniawa is exposed to a periodical advection of polluted air from regional sources.

Abstract: Soil samples from an abandoned uranium mine have been investigated in order to determine the molecular phases of uranium compounds. The experiments were carried out with soil particulate matter, collected randomly from the area of the formerly exploited ore. To select the particles rich with uranium, scanning electron microscopy with energy-dispersive X-ray attachment (SEM/EDX) was applied first. Afterwards, the particles were relocated and measured by l-Raman spectrometry (MRS). Residues of the main deposit, uraninite UO2, were detected, along with its alteration products. In terms of Raman scattering properties, uranium oxides are quite sensitive to the laser beam wavelength, which results in very specific features of their Raman spectra. In this paper the Raman spectra of uranium oxides of different origin and oxidation states, measured with 514 and 785 nm lasers, are also presented

Abstract: In Ethiopia, the state owns all lands within the territory of the country. Cities are incorporating large parcels of land from their surrounding rural agricultural areas through land expropriation. However, these land developments do not consider the nonmarket value of ecosystem services (ES), which is causing a deterioration of the existing ES and reduction on the potential supply of ES from agricultural land. The aim of this study was to estimate the monetary value of nonmarketable ES from the agricultural land using a double-bounded dichotomous choice contingent valuation method. A survey of 524 smallholder farmers was conducted. In the survey, respondents were asked to state their willingness to pay for the improvement of some of the nonmarketable ES: erosion control, air and climate regulation, water regulation, and soil fertility. The estimation was carried out using a bivariate probit model. The results revealed that farmers are willing to pay on average 276 ETB (7.9 USD) per hectare per year for a period of 10 years. We found that individual characteristics such as age, family size, and a recent land expropriation experience adversely affect the willingness to pay by the farmers. On the other hand, individuals with higher income and larger land size are willing to pay more. In general, the study indicated that the nonmarket ES, which are affected by the land expropriation for urban expansion, are valuable for the farmers. Therefore, we recommend that the government consider the value of nonmarketable ES in its land use decisions and hence achieve sustainable land development.