Influence of the Temperature on Coccolith-Containing Systems from Emiliania huxleyi Cultivations

Thermogravimetric analysis of a coccolith-containing biogenic broth showed a three-step degradation process. According to this system behavior, the biogenic broth was heated to specific temperatures and characterized in terms of its morphology, surface chemistry, and crystallinity. The elemental and organic composition of the treated samples was also evaluated and compared to the reference material. The presented results were acquired in an effort to exploit pretreatment scenarios for such a biogenic system that would improve and support a separation process.     

Oxidative thermal decomposition of poly(vinyl chloride) compositions

“Pure” poly(vinyl chloride) resin and four compositions containing poly(vinyl chloride) were subjected to oxidative thermal degradation in air at &400°C both in a quiescent and a flow system. The volatiles formed were identified and quantitatively determined on a gram-per-gram basis. Hydrogen chloride was the main product found. The nature and relative concentration of the produced organic chlorinated species appeared to be dependent not only on the poly(vinyl chloride) constituent but also on the other ingredients. All the compositions contained phthalate ester plasticizers. In the dynamic system, these distilled largely unchanged, whereas under static conditions transformation into phthalic anhydride occurred.     

Time-of-flight studies on catalytic model reactions

Time-of-flight spectroscopy (TOF) and REMPI-TOF (resonance enhanced multi-photon ionization-TOF) were applied to measure the angular and translational energy distribution, as well as the internal state resolved energy distribution of desorption and reaction products on some model systems. Desorption of hydrogen and deuterium from clean and modified Pd(111) surfaces was studied, where the palladium sample was part of a permeation source. Water formation by reaction of oxygen with hydrogen on palladium was investigated by using different types of hydrogen supply: molecular H₂ exposure and atomic H exposure from the gas phase, as well as H exposure by permeating hydrogen. Vanadium oxide nanostructures on Pd(111) were prepared and the influence on D₂ desorption and D₂O production was investigated with the permeation technique. Additionally, deuterium desorption from sulfur and oxygen covered V(111) and V(100) surfaces was studied by TOF and REMPI-TOF spectroscopy. From the TOF spectra information concerning the reaction and desorption dynamics (activation barriers) could be gained.     

Relationship between the attenuation of downwelling irradiance at 490 nm with the attenuation of PAR (400 nm-700 nm) in the Baltic Sea

The vertical attenuation coefficient of diffuse downwelling irradiance at 490 nm (K_d 490) is a parameter that we routinely derive from SeaWiFS images of the Baltic Sea. Here, through model simulations, we examine the relationship between K_d(490), and the vertical attenuation coefficient of PAR (K_d PAR), as this later coefficient determines the light available for aquatic photosynthesis. A simple semi-analytical model is used to predict K_d(490) and K_d(PAR), as a function of the concentrations of chlorophyll, colored dissolved organic material (CDOM), suspended inorganic, and suspended organic particulate material. A series of model simulations based on variations in these optically significant constituents over a range realistic for the Baltic Sea, are used to define the relationship between the two attenuation coefficients.

Kd(PAR)=0.6677Kd^0.6763(490).     

Seasonal changes in colour ratios and optically active contituents in the optical Case-2 waters of the Menai Strait,North Wales

A time series was conducted in the Menai Strait from March to December 1996 combining optical measurements by a colour sensor with measurements of light-absorbing constituents in the water. In order to improve estimations of pigment concentration in Case-2 waters, an optical model was used to synthesize the spectrum of sea-leaving radiance from the absorption properties of pure sea water, yellow substances, mineral suspended solids and phytoplankton. The original model was tested and improved by using a different set of parameters. Multiple regression was used to empirically relate colour ratios to pigments and total suspended solids.     

Recycling von marinen Sekundärrohstoffen

As a waste product, oyster shells pose a major environmental pollution problem and the reuse of the material is becoming increasingly important. Since the comminution process in the recycling of secondary raw materials defines the properties of the material, oyster shells were grinded using a planetary ball mill and an impact mill and the fractions obtained were analyzed in terms of size and shape and compared with each other. A comminuted material from the impact mill was used for a series of wetting experiments, which helped to demonstrate the surface free energy of the material.     

The Flexible Rare Event Sampling Harness System (FRESHS)

We present the software package FRESHS (http://www.freshs.org) for parallel simulation of rare events using sampling techniques from the ‘splitting’ family of methods. Initially, Forward Flux Sampling (FFS) and Stochastic Process Rare Event Sampling (SPRES) have been implemented. These two methods together make rare event sampling available for both quasi-static and full non-equilibrium regimes. Our framework provides a plugin system for software implementing the underlying physics of the system of interest. At present, example plugins exist for our framework to steer the popular MD packages GROMACS, LAMMPS and ESPResSo, but due to the simple interface of our plugin system, it is also easy to attach other simulation software or self-written code. Use of our framework does not require recompilation of the simulation program. The modular structure allows the flexible implementation of further sampling methods or physics engines and creates a basis for objective comparison of different sampling algorithms.     

Rechnerische Beurteilung der Schubtragfähigkeit einer Spannbetonbrücke mit geringem Querkraft bewehrungsgrad

Assessment of the shear strength of an existing post‐tensioned concrete bridge with a low amount of shear reinforcement – First application of the ”Flexural Shear Crack“ model in practice In recent years it was reported several times, that within a static assessment according to current standards the shear strength of post‐tensioned bridges, which were built in Austria before 1989, cannot be fulfilled any more. However, test results prove, that especially prestressed structures have additional load bearing capacities, which cannot be reproduced with current calculation models. In the framework of a pilot project a new developed shear model (Flexural Shear Crack Model) was used. In this paper the approach as well as the main results of a statical reevaluation of an existing post‐tensioned road bridge at the Tauern Autobahn A10 will be presented.     

Sources and temporal dynamics of arsenic in a New Jersey watershed, USA

We examined potential sources and the temporal dynamics of arsenic (As) in the slightly alkaline waters of the Wallkill River, northwestern New Jersey, where violations of water-quality standards have occurred. The study design included synoptic sampling of stream water and bed sediments in tributaries and the mainstem, hyporheic-zone/ground water on the mainstem, and seasonal and diurnal sampling of water at selected mainstem sites. The river valley is bordered by gneiss and granite highlands and shale lowlands and underlain by glacial deposits over faulted dolomites and the Franklin Marble. Ore bodies in the Marble, which have been mined for rare Zn ore minerals, also contain As minerals. Tributaries, which drain predominantly forested and agricultural land, contributed relatively little As to the river. The highest concentrations of As (up to 34 mug/L) emanated from the outlet of man-made Lake Mohawk at the river's headwaters; these inputs varied substantially with season--high during warm months, low during cold months, apparently because of biological activity in the lake. Dissolved As concentrations were lower (3.3 microg/L) in river water than those in ground water discharging into the riverbed (22 microg/L) near the now-closed Franklin Mine. High total As concentrations (100-190 mg/kg) on the <0.63 microm fraction of bed sediments near the mine apparently result from sorption of the As in the ground-water discharge as well as from the As minerals in the streambed. As concentrations in river water were diluted during high stream flow in fall, winter and spring, and concentrated during low flow in summer. In unfiltered samples from a wetlands site, diurnal cycles in trace-element concentrations occurred; As concentrations appeared to peak during late afternoon as pH increased, but Fe, Mn, and Zn concentrations peaked shortly after midnight. The temporal variability of As and its presence at elevated concentrations in ground water and sediments as well as streamwater demonstrate the importance of (1) sampling a variety of media and (2) determining the time scales of As variability to fully characterize its passage through a river system.     

Gallstone prevalence in relation to smoking, alcohol, coffee consumption, and nutrition. The Ulm Gallstone Study

BACKGROUND: Besides considering well-known risk factors for the development of gallbladder stones, such as age, sex, fecundity, and hereditary predisposition, efforts at prevention have focused increasingly on other factors, such as nicotine, alcohol, and caffeine consumption, as well as general nutrition, which may be modified. METHODS: A total of 1116 blood donors were examined between April 1994 and February 1995 in the central blood bank of the German Red Cross in Ulm, Germany. Each subject received a questionnaire and underwent to an upper abdominal ultrasound examination. RESULTS: Gallbladder stone disease (current cholecystolithiasis and history of cholecystectomy) was detailed in 5.8% of the men and 6.3% of the women. Neither regularity nor number of daily meals correlated with the frequency of gallstone disease. Vegetarians (n = 48), as a group, were not found to have gallstones. In relation to the consumption of alcohol, tobacco, or caffeine higher prevalence of cholecystolithiasis was found only in heavy drinkers of coffee (P = 0.051; odds ratio (OR), 1.083; 95% confidence interval (CI), 0.999, 1.174). CONCLUSION: Results of the present study do not show a definite relationship between nutritional factors and the consumption of alcohol, tobacco, or caffeine and an increased prevalence of gallbladder stone disease.