Materials Analysis by Mass Spectrometry of Sputtered Neutrals

Mass spectrometric detection of neutral surface particles released by ion bombardment has become an important method for surface and depth profile analysis. Its fundamental difference to secondary ion mass spectrometry SIMS is the separation of the formation of the analyzed particles and their ionization. Hence, matrix and selectivity effects influencing SIMS signals in a mostly unknown manner via the ionization process in secondary ion emission are avoided in general. The different techniques being presently employed for the necessary postionization of the sputtered neutrals are reviewed and discussed with respect to their potentialities. Secondary Neutral Mass Spectrometry (SNMS) using efficient postionization by the electron component of a special tow pressure high frequency plasma is the presently most elaborated technique. The quantifiability of SNMS signals is discussed and illustrated by various examples. Depth resolution in the subnanometer range is shown to be obtained with the direct bombardment mode of SNMS in which the sample is bombarded with noble gas ions from the SNMS-plasma at energies in the order of only 102 eV

Chemical surface and thin film analysis in glass coating

After a short overview of recent analytical techniques for compositional surface analysis and the determination of concentration depth profiles, the principle, the Instrumentation and the Performance of the routinely used electron spectroscopic and mass spectrometric methods, namely photo- and Auger electron spectroscopy as well as secondary ion and secondary neutral mass spectrometry, are described. The application of these techniques to electrically insulating surfaces and layer structures is particularly emphasized by corresponding practical examples. Secondary neutral mass spectrometry is specifically addressed with regard to the potentialities of the novel high-frequency mo d e of electron-gas secondary neutral mass spectrometry for quantitative composition analysis and high-resolution depth profiling of electrically nonconducting sample structures

Analysis of Insulator Samples by Secondary Neutral Mass Spectrometry

Secondary Neutral Mass Spectrometry (SNMS) offers new possibilities for the analysis of insulators when the electron component of the postionizing SNMS plasma is employed for a precise compensation of sample charging. The compensation techniques for the three operation modes of SNMS, namely the direct, the separate and the external bombardment mode are described. Corresponding examples for bulk and depth profile analysis of insulating samples and dielectric thin film systems will be reported and discussed

Untersuchungen zum Einfluss der Biogasgärung auf die Keimfähigkeit von Unkraut- und Kulturpflanzensamen unter besonderer Berücksichtigung des Ampfers (Rumex obtusifolius)

Fazit: Die durchgeführten Versuche zeigen, dass durch die Biogasgärung die Keim-fähigkeit von Samen beeinträchtigt wird und somit die Verbreitung von Unkrautsamen vermindert werden kann. Neben Faktoren wie Mikroorganismenaktivität, Schadgasen, die beim Abbau von organischer Substanz entstehen, und dem Samenfeuchtig-keitsgehalt spielten hierbei vermutlich vor allem die Temperatur des Substrats und die Verweildauer der Samen in der Biogasanlage eine Rolle. Berücksichtigt man dies bei der Betriebsweise einer Biogasanlage, kann man davon ausgehen, dass der Unkraut-druck durch die Verbreitung der Unkrautsamen über die Gülleausbringung gesenkt werden kann

Oat husks in anaerobic digestion

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Effects of full-scale substrate pretreatment with a cross-flow grinder on biogas production

The enhancement of the degradation rate of energy crops, agricultural residues and manure by different lab scale pretreatment pathways is shown in previous studies.  In general, the pretreatments resulted in higher degradation efficiencies and an increase in methane yield for lignocellulosic and fibrous biomass.  The major drawback of most of the different pretreatment methods is that either they are not feasible for application in practice or the high energy demand makes them economically inefficient.  The aim of this study was to evaluate the effects of a full-scale mechanical pretreatment with a cross-flow grinder on commonly used energy crops (maize silage, grass silage and rye grain silage) and horse manure. Furthermore, the optimal treatment intensity for the highest energy output was estimated.  A grinding time of 15 s led to a significant increase in methane yield for horse manure (+ 9.2%) and a mixture of energy crops and horse manure (+ 9.7%).  However, only lower treatment intensities proved   to have a positive energy balance.  An increase in treatment intensity resulted in a further reduction of particle size but showed no effects on the degradation efficiency.  Hence, it can be concluded that the utilization of the mechanical treatment enables the digestion of lignocellulosic and fiber-rich substrates like residuals and organic wastes and therefore increases the environmental sustainability of energy production by anaerobic digestion.Keywords: anaerobic digestion, biogas production, mechanical pretreatment, lignocellulosic materials, horse manur

Investigation of the methane potential of horse manure

During recent years the renewable energy production with agricultural biomass became more and more important.  The increased use of agricultural products instead for nutrition aroused a debate.  Therefore, the utilization of agricultural byproducts and residuals for anaerobic digestion is the essential step for the future sustainable energy production.  One available substrate would be horse manure, but literature is still lacking information about gas potential and digestibility of horse manure in biogas plants.  This work aims at investigating the suitability of horse manure with different bedding materials and to produce standard values for different horse manure samples.  Additionally the methane yields of the components of the horse manure were analyzed.  The results of the batch digestion test showed the highest specific methane yields for straw pellets with 0.247 Nm³ CH4 kg-1 VS.  Slightly lower are the values for the straw samples in range of 0.183 to 0.237 Nm³ CH4 kg-1 VS.  The digestion of alternate bedding materials like flax and woody materials leads to specific methane values beneath 0.100 Nm³ CH kg-1 VS.  Based on these results these materials should be avoided for anaerobic digestion.  The straw based horse manure produced 0.191 ± 0.02 Nm³ CH4 kg-1 VS in the batch assay.  The storage of the manure resulted in significant lower methane yields.  Hence, the anaerobic digestion of the straw based horse manure is an efficient conversion pathway and can help to avoid the utilization of acreage for energy production instead of the production of food.    Keywords: biogas, methane yield, horse manure, anaerobic digestio

Batch anaerobic digestion of banana waste - energy potential and modelling of methane production kinetics

Different fractions of banana (stalk, peel, and flesh) as well as the whole unpeeled banana were studied in a laboratory Biochemical Methane Potential (BMP) assay. After completion of 35-day digestion at 37°C in 2L-reactors, specific methane yields reached 0.256, 0.322, 0.367 and 0.349 m³/kg VS (volatile solids) for stalk, peel, flesh, and unpeeled banana respectively. Considering the country of Uganda, East Africa, the collection of peels and stalks from banana production would yield a theoretical potential of about 60 GWh of electrical energy per year in biogas plants. In order to verify the suitability of banana fractions to the biogas process, their chemical composition was analyzed, and their methane production kinetics was estimated with exponential and logistic models. Banana peel was found to be easily degradable, and well suited for biogas production. Banana flesh had the fastest degradation rate of all banana fractions, and banana stalk had the slowest degradation rate, respectively. Methane production kinetics was fitted with first order and logistic models. The kinetics of methane production from banana flesh correlated well with a logistic model, but did not with exponential models. Alternately, methane production kinetics from banana stalk correlated well with exponential models, but did not with the logistic model. Methane production kinetics from banana peel did not correlate well with any model. Hence, the biochemistry of anaerobic processes may follow different patterns depending on substrate degradability, explaining the difficulty of finding a universal explanatory model of methane production kinetics in batch mode

McLeod myopathy revisited: more neurogenic and less benign

The X-linked McLeod neuroacanthocytosis syndrome (MLS) has originally been denoted as ‘benign' McLeod myopathy. We assessed the clinical findings and the muscle pathology in the eponymous index patient, Hugh McLeod, and in nine additional MLS patients. Only one patient had manifested with neuromuscular symptoms. During a mean follow-up of 15 years, however, eight patients including the initial index patient showed elevated skeletal muscle creatine kinase levels ranging from 300 to 3000 U/L, and had developed muscle weakness and atrophy. Two patients had disabling leg weakness. Muscle histology was abnormal in all 10 patients. Clear but unspecific myopathic changes were found in only four patients. All patients, however, had neurogenic changes of variable degree. Post-mortem motor and sensory nerve examinations support the view that muscle atrophy and weakness are predominantly due to an axonal motor neuropathy rather than to a primary myopathy. Multisystem manifestations developed in eight patients at a mean age of 39 years. Three patients manifested with psychiatric features comprising schizophrenia-like psychosis and personality disorder, two presented with generalized seizures and one with chorea. During follow-up, seven patients developed chorea, six had psychiatric disorders, five had cognitive decline and three had generalized seizures. Five patients died because of MLS-related complications including sudden cardiac death, chronic heart failure and pneumonia between 55 and 69 years. In conclusion, our findings confirm that MLS is not a benign condition but rather a progressive multisystem disorder sharing many features with Huntington's diseas