RNetCDF – A Package for Reading and Writing NetCDF Datasets

This paper describes the RNetCDF package (version 1.6), an interface for reading and writing files in Unidata NetCDF format, and gives an introduction to the NetCDF file format. NetCDF is a machine independent binary file format which allows storage of different types of array based data, along with short metadata descriptions. The package presented here allows access to the most important functions of the NetCDF C-interface for reading, writing, and modifying NetCDF datasets. In this paper, we present a short overview on the NetCDF file format and show usage examples of the package

Interpenetrated Magnesium–Tricalcium Phosphate Composite: Manufacture, Characterization and In Vitro Degradation Test

Magnesium and calcium phosphates composites are promising biomaterials to create biodegradable load-bearing implants for bone regeneration. The present investigation is focused on the design of an interpenetrated magnesium–tricalcium phosphate (Mg–TCP) composite and its evaluation under immersion test. In the study, TCP porous preforms were fabricated by robocasting to have a prefect control of porosity and pore size and later infiltrated with pure commercial Mg through current-assisted metal infiltration (CAMI) technique. The microstructure, composition, distribution of phases and degradation of the composite under physiological simulated conditions were analysed by scanning electron microscopy, elemental chemical analysis and X-ray diffraction. The results revealed that robocast TCP preforms were full infiltrated by magnesium through CAMI, even small pores below 2 lm have been filled with Mg, giving to the composite a good interpenetration. The degradation rate of the Mg–TCP composite displays lower value compared to the one of pure Mg during the first 24 h of immersion test.Magnesium and calcium phosphates composites are promising biomaterials to create biodegradable load-bearing implants for bone regeneration. The present investigation is focused on the design of an interpenetrated magnesium–tricalcium phosphate (Mg–TCP) composite and its evaluation under immersion test. In the study, TCP porous preforms were fabricated by robocasting to have a prefect control of porosity and pore size and later infiltrated with pure commercial Mg through current-assisted metal infiltration (CAMI) technique. The microstructure, composition, distribution of phases and degradation of the composite under physiological simulated conditions were analysed by scanning electron microscopy, elemental chemical analysis and X-ray diffraction. The results revealed that robocast TCP preforms were full infiltrated by magnesium through CAMI, even small pores below 2 lm have been filled with Mg, giving to the composite a good interpenetration. The degradation rate of the Mg–TCP composite displays lower value compared to the one of pure Mg during the first 24 h of immersion test

Does fog chemistry in Switzerland change with altitude?

During two extended summer seasons in 2006 and 2007 we operated two battery driven versions of the Caltech active strand cloud water collector (MiniCASCC) at the Niesen mountain (2362 m a.s.l.) in the northern part of the Swiss Alps, and two devices at the Lägeren research tower (690 m a.s.l.) at the northern boundary of the Swiss Plateau. During these two field operation phases we gained weekly samples of fog water, where we analyzed the major anions and cations, and the isotope ratios of fog water (in form of δ2H and δ18O). Dominant ions in fog water at all sites were NH4+, NO3−, and SO42 −. Compared to precipitation, the enrichment factors in fog water were in the range 5–9 at the highest site, Niesen Kulm. We found considerably lower summertime ion loadings in fog water at the two Alpine sites than at lower elevations above the Swiss Plateau. The lowest ion concentrations were found at the Niesen Kulm site at 2300 m a.s.l., whereas the highest concentrations (a factor 7 compared to Niesen Kulm) were found in fog water at the Lägeren site. Occult nitrogen deposition was estimated from fog frequency and typical fog water flux rates. This pathway contributes 0.3–3.9 kg N ha− 1 yr− 1 to the total N deposition at the highest site on Niesen mountain, and 0.1–2.2 kg N ha− 1 yr− 1 at the lower site. These inputs are the reverse of ion concentrations measured in fog due to the 2.5 times higher frequency of fog occurrence at the mountain top (overall fog occurrence was 25% of the time) as compared to the lower Niesen Schwandegg site. Although fog water concentrations were on the lower range reported in earlier studies, fog water is likely to be an important N source for Northern Alpine ecosystems and might reach values up to 16% of the total N deposition and up to 75% of wet N deposition by precipitation

MiniCASCC - A battery driven fog collector for ecosystem research

We developed a small version of the Caltech active strand cloud water collector (CASCC) for biogeochemical investigations in ecological applications. The device is battery powered and thus allows operation at locations where mains power is not available. The collector is designed for sampling periods of up to one week, depending on fog frequency. Our new device is equipped with standard sensors for air temperature, relative humidity, wind, and horizontal visibility for fog detection with a low-cost optical sensor. In mountain areas and during times when clouds are thin the installation of the visibility sensor became a key issue, which limits the potential to estimate liquid water content of the sampled fog. Field tests with 5 devices at three different sites in the Swiss Alps (Niesen) and the Jura Mountains (Lägeren, Switzerland) during two extended summer seasons in 2006 and 2007 showed that in almost all cases it was possible to obtain sample volumes which were large enough for the examination of basic inorganic chemistry of the collected cloud water. Collection rates varied typically from 12 to 30 mL h− 1. The fog droplet cutoff diameter is ≈ 6 μm, which is low enough to include all droplet sizes that are relevant for the liquid water content of typical fog types in the collected samples. From theoretical assumptions of the collection efficiency and theoretical droplet spectra it is possible to estimate the liquid water content of the sampled fog or cloud. Our new fog collector can be constructed and operated at relatively low costs. In combination with chemical and isotopic analyses of the sampled water, this allows to quantify nutrient and pollutant fluxes as is typically needed in ecosystem biogeochemistry studies

Topoclimatological case-study of Alpine pastures near the Albula Pass in the eastern Swiss Alps

Alpine grasslands are an important source of fodder for the cattle of Alpine farmers. Only during the short summer season can these pastures be used for grazing. With the anticipated climate change, it is likely that plant production – and thus the fodder basis for the cattle – will be influenced. Investigating the dependence of biomass production on topoclimatic factors will allow us to better understand how anticipated climate change may influence this traditional Alpine farming system. Because small-scale topoclimatological variations of the main meteorological variables: temperature, humidity, precipitation, shortwave incoming radiation and wind speed are not easily derived from available long-term climate stations in mountainous terrain, it was our goal to investigate the topoclimatic variations over the pastures belonging to the Alp Weissenstein research station north of the Albula Pass in the eastern Swiss Alps. We present a basic assessment of current topoclimatic conditions as a site characterization for ongoing ecological climate change studies. To be able to link short-term studies with long-term climate records, we related agrometeorological measurements with those of surrounding long-term sites run by MeteoSwiss, both on valley bottoms (Davos, Samedan), and on mountain tops (Weissfluhjoch, Piz Corvatsch). We found that the Davos climate station north of the study area is most closely correlated with the local climate of Alp Weissenstein, although a much closer site (Samedan) exists on the other side of the Albula Pass. Mountain top stations, however, did not provide a convincing approximation for the climate at Alp Weissenstein. Direct comparisons of near-surface measurements from a set of 11 small weather stations distributed over the domain where cattle and sheep are grazed indicate that nocturnal minimum air temperature and minimum vapor pressure deficit are mostly governed by the altitudinal gradient, whereas daily maxima – including also wind speed – are more strongly depending on vegetation cover and less on the altitude

Topoclimatological case-study of Alpine pastures near the Albula Pass in the eastern Swiss Alps

Alpine grasslands are an important source of fodder for the cattle of Alpine farmers. Only during the short summer season can these pastures be used for grazing. With the anticipated climate change, it is likely that plant production – and thus the fodder basis for the cattle – will be influenced. Investigating the dependence of biomass production on topoclimatic factors will allow us to better understand how anticipated climate change may influence this traditional Alpine farming system. Because small-scale topoclimatological variations of the main meteorological variables: temperature, humidity, precipitation, shortwave incoming radiation and wind speed are not easily derived from available long-term climate stations in mountainous terrain, it was our goal to investigate the topoclimatic variations over the pastures belonging to the Alp Weissenstein research station north of the Albula Pass in the eastern Swiss Alps. We present a basic assessment of current topoclimatic conditions as a site characterization for ongoing ecological climate change studies. To be able to link short-term studies with long-term climate records, we related agrometeorological measurements with those of surrounding long-term sites run by MeteoSwiss, both on valley bottoms (Davos, Samedan), and on mountain tops (Weissfluhjoch, Piz Corvatsch). We found that the Davos climate station north of the study area is most closely correlated with the local climate of Alp Weissenstein, although a much closer site (Samedan) exists on the other side of the Albula Pass. Mountain top stations, however, did not provide a convincing approximation for the climate at Alp Weissenstein. Direct comparisons of near-surface measurements from a set of 11 small weather stations distributed over the domain where cattle and sheep are grazed indicate that nocturnal minimum air temperature and minimum vapor pressure deficit are mostly governed by the altitudinal gradient, whereas daily maxima – including also wind speed – are more strongly depending on vegetation cover and less on the altitude

Microstructural Characteristics of Al-Ti-B Inoculation Wires and Their Addition to the AlSi7Mg0.3 Alloy

Commercially supplied inoculation wires have a guaranteed chemical composition but not the size and distribution of individual phases, which are very important for nucleation. Therefore, two commercial alloys used for the inoculation of Al-Si alloys (AlTi3B1 and AlTi5B1) are investigated in this paper. The emphasis is placed on their structural analysis and the size and distribution of individual intermetallic phases. Furthermore, the grain refinement effect will be tested by adding these alloys to the AlSi7Mg0.3 alloy and testing the optimal amount of added inoculation wires. The results showed that the size and distribution of the individual phases in AlTi3B1 and AlTi5B1 meet the requirements for the successful inoculation of aluminum alloys, the intermetallic phases based on the TiAl3 phase are fine enough, and there is no agglomeration that would reduce the number of nuclei. This assumption was confirmed by adding these inoculants to the AlSi7Mg0.3 alloy, and it was found that the most ideal amount of inoculants added is 0.01 wt % when the structure was refined by approximately 32%