Deep level transient spectroscopy (DLTS) and minority carrier transient spectroscopy (MCTS) are used to investigate electrically active defects in commercial SiC Schottky power diodes after heavy-ion ...microbeam irradiation at different voltages. The DLTS and MCTS spectra of pristine samples are analysed and compared to devices showing or not signatures of Single Event Leakage Current (SELC) degradation. An additional peak labelled 'C' with an activation energy of 0.17 eV below the conduction band edge is observed in the DLTS spectra of a sample degraded with SELC.
Many factors affect plywood formaldehyde emission and content, such as raw materials, manufacturing processes, stacking conditions, etc. In order to show the influence of veneer wood species on ...formaldehyde emission and content, several groups of plywood panels have been manufactured in the laboratory using commercial urea-formaldehyde resins and following the process employed in the industry. Four veneer wood species have been studied: Ceiba (Ceiba pentandra Gaertn.), beech (Fagus sylvatica L.), ilomba (Pycnathus angolensis Exell) and okumT (Aucoumea klaineana Pierre), all widely used in wood processing factories. Plywood formaldehyde emission and content have been determined according to CEN standards EN 717-2 and EN 120, respectively. Wood porosity and the overall exposed surface of vessels in the edges of plywood have been measured as well. This investigation has permitted to establish the correlation between plywood formaldehyde emission and content and the above mentioned physical and anatomical wood characteristics.
Viele Faktoren beeinflussen Emission und Gehalt an Formaldehyd in Furnieren, u.a. das Ausgangsmaterial, der Herstellungsprozess und die Lagerungsbedingungen. Um den Einfluss der verwendeten Holzart zu untersuchen, wurden mehrere Gruppen von Furnierplatten mit kommerziellen UF-Harzen im Labor nach Industrievorgaben hergestellt. Vier hSufig genutzte Holzarten kamen zum Einsatz: Ceiba pentandra Gaertn., Fagus sylvatica, Pycnathus angolensis und Aukoumea klaineana Pierre. Emission und Gehalt an Formaldehyd wurden nach den CEN-Normen EN 717-2 und EN 120 bestimmt. Au¯erdem wurde die PorositSt des Holzes und die GesamtoberflSche der GefS¯e an den Schmalseiten der Furniere gemessen. Dadurch konnte eine Korrelation zwischen Formaldehydemission und physikalischen und anatomischen Eigenschaften der verwendeten H÷lzer aufgestellt werden.
Several microbes and chemicals have been considered as potential tracers to identify fecal sources in the environment. However, to date, no one approach has been shown to accurately identify the ...origins of fecal pollution in aquatic environments. In this multilaboratory study, different microbial and chemical indicators were analyzed in order to distinguish human fecal sources from nonhuman fecal sources using wastewaters and slurries from diverse geographical areas within Europe. Twenty-six parameters, which were later combined to form derived variables for statistical analyses, were obtained by performing methods that were achievable in all the participant laboratories: enumeration of fecal coliform bacteria, enterococci, clostridia, somatic coliphages, F-specific RNA phages, bacteriophages infecting Bacteroides fragilis RYC2056 and Bacteroides thetaiotaomicron GA17, and total and sorbitol-fermenting bifidobacteria; genotyping of F-specific RNA phages; biochemical phenotyping of fecal coliform bacteria and enterococci using miniaturized tests; specific detection of Bifidobacterium adolescentis and Bifidobacterium dentium; and measurement of four fecal sterols. A number of potentially useful source indicators were detected (bacteriophages infecting B. thetaiotaomicron, certain genotypes of F-specific bacteriophages, sorbitol-fermenting bifidobacteria, 24-ethylcoprostanol, and epycoprostanol), although no one source identifier alone provided 100% correct classification of the fecal source. Subsequently, 38 variables (both single and derived) were defined from the measured microbial and chemical parameters in order to find the best subset of variables to develop predictive models using the lowest possible number of measured parameters. To this end, several statistical or machine learning methods were evaluated and provided two successful predictive models based on just two variables, giving 100% correct classification: the ratio of the densities of somatic coliphages and phages infecting Bacteroides thetaiotaomicron to the density of somatic coliphages and the ratio of the densities of fecal coliform bacteria and phages infecting Bacteroides thetaiotaomicron to the density of fecal coliform bacteria. Other models with high rates of correct classification were developed, but in these cases, higher numbers of variables were required.
•Methane inhibition does not lead to additional energy products for the host animal.•Phenolic compounds increased acetate and total volatile fatty acid production.•Phenolic compounds reduced ...dihydrogen accumulation in vitro.•Phloroglucinol and gallic acid are potential dihydrogen acceptors in ruminant diets.
Some antimethanogenic feed additives for ruminants promote rumen dihydrogen (H2) accumulation potentially affecting the optimal fermentation of diets. We hypothesised that combining an H2 acceptor with a methanogenesis inhibitor can decrease rumen H2 build-up and improve the production of metabolites that can be useful for the host ruminant. We performed three in vitro incubation experiments using rumen fluid from lactating Holstein cows: Experiment 1 examined the effect of phenolic compounds (phenol, catechol, resorcinol, hydroquinone, pyrogallol, phloroglucinol, and gallic acid) at 0, 2, 4, and 6 mM on ruminal fermentation for 24 h; Experiment 2 examined the combined effect of each phenolic compound from Experiment 1 at 6 mM with two different methanogenesis inhibitors (Asparagopsis taxiformis or 2-bromoethanesulfonate (BES)) for 24 h incubation; Experiment 3 examined the effect of a selected phenolic compound, phloroglucinol, with or without BES over a longer term using sequential incubations for seven days. Results from Experiment 1 showed that phenolic compounds, independently of the dose, did not negatively affect rumen fermentation, whereas results from Experiment 2 showed that phenolic compounds did not decrease H2 accumulation or modify CH4 production when methanogenesis was decreased by up to 75% by inhibitors. In Experiment 3, after three sequential incubations, phloroglucinol combined with BES decreased H2 accumulation by 72% and further inhibited CH4 production, compared to BES alone. Interestingly, supplementation with phloroglucinol (alone or in combination with the CH4 inhibitor) decreased CH4 production by 99% and the abundance of methanogenic archaea, with just a nominal increase in H2 accumulation. Supplementation of phloroglucinol also increased total volatile fatty acid (VFA), acetate, butyrate, and total gas production, and decreased ammonia concentration. This study indicates that some phenolic compounds, particularly phloroglucinol, which are naturally found in plants, could improve VFA production, decrease H2 accumulation and synergistically decrease CH4 production in the presence of antimethanogenic compounds.
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