Influence of the Impaction Angle on the Triboelectric Charging of Aerosol Nanoparticles

A low pressure impactor is used to measure triboelectric charging behavior of metallic nanoparticles. Ag nanoparticles, produced by spark discharge, were impacted onto Pt sputtered targets. The influence of the impaction angle and impaction velocity on the triboelectric charging was investigated. While for perpendicular impaction the charge transfer behavior of previous work was confirmed, the oblique impaction revealed new phenomena. Additional charge transfer was observable, which increases with obliqueness. The possibility of mass transfer between particle and target due to the high-energy collisions was also investigated. SEM characterization and Auger spectroscopy indicate mass transfer from the particle to the target surface.     

Wood surface discolouration due to simulated indoor sunlight exposure

Wood surface colour is a very important quality criterion in the utilisation of wood, especially in indoor applications. In this study, an attempt was made to analyse wood surface discolouration due to artificial indoor light irradiation of the most frequently traded wood species in Europe altogether. Sixteen wood species, twelve hardwood and four softwood species, were exposed for 120 hours to a xenon-arc lamp equipped with a 3 mm window glass filter, in order to simulate natural sunlight behind a window glass. Eleven wood species were chosen and further exposed to irradiation for up to 600 hours. Colour measurements were performed by means of a colorimeter device on exposed and non-exposed areas of the samples. Using the CIE-L*a*b* colour measuring system, wood surface discolouration was measured and calculated according to ?L*, ?a*, ?b* and ?E* values. An idea of the different behaviour of these species and how they relate to each other could be given.     

Processing and analytical characterisation of pulp-enriched cloudy apple juices

Pulp-enriched cloudy apple juices were manufactured from two apple varieties by blending of apple puree with natural cloudy apple juice in order to enrich bioactive secondary plant substances. Finishing of the puree with a 0.6-mm mesh screen and final product homogenisation revealed as the optimum processing technology for the novel 100% fruit beverage. The presence of large particles originating from the puree prevented long-term cloud stability, but due to the proportion of cloud-stable juice a complete phase separation did not occur. Optimal drinkability was achieved at a viscosity of 11.5 mPa s. Polyphenol compositions and concentrations were determined by means of RP-HPLC/PDA. The results ranged from 109 to 610 mg/l. All samples showed the typical polyphenol pattern of apples with dominating hydroxycinnamic acids followed by flavanols and flavonols. The puree addition to the cloudy apple juices increased the polyphenol concentrations by average 100%. Relatively, the highest increase could be observed for dimeric procyanidins. Different technological variants did not affect significantly the polyphenol concentrations. The dietary fibre contents of the pulp-enriched cloudy apple juices ranged from 5.8 to 9.4 g/l.     

Removal of oxide nanoparticles in a model wastewater treatment plant: influence of agglomeration and surfactants on clearing efficiency

The rapidly increasing production of engineered nanoparticles has created a demand for particle removal from industrial and communal wastewater streams. Efficient removal is particularly important in view of increasing long-term persistence and evidence for considerable ecotoxicity of specific nanoparticles. The present work investigates the use of a model wastewater treatment plant for removal of oxide nanoparticles. While a majority of the nanoparticles could be captured through adhesion to clearing sludge, a significant fraction of the engineered nanoparticles escaped the wastewater plant's clearing system, and up to 6 wt % of the model compound cerium oxide was found in the exit stream of the model plant. Our study demonstrates a significant influence of surface charge and the addition of dispersion stabilizing surfactants as routinely used in the preparation of nanoparticle derived products. A detailed investigation on the agglomeration of oxide nanoparticles in wastewater streams revealed a high stabilization of the particles against clearance (adsorption on the bacteria from the sludge). This unexpected finding suggests a need to investigate nanoparticle clearance in more detail and demonstrates the complex interactions between dissolved species and the nanoparticles within the continuously changing environment of the clearing sludge.     

Influence of convection and grain movement on globular equiaxed solidification

A two-phase volume averaging model was used to study convection and grain movement, and their influence on the globular equiaxed solidification. Both liquid and solid phases were treated as separate interpenetrating continua. The mass, momentum, species and enthalpy conservation equations for each phase and a grain transport equation were coupled. An ingot casting (Al-4 wt.% Cu) with near globular solidification morphology was simulated. Case studies with different modeling assumptions such as with and without grain movement, and with slip and non-slip boundary conditions for solid phase were presented and compared. Understanding of grain evolution and macrosegregation formation in globular equiaxed solidification was improved.     

REFORMING OF N-OCTANE ON A Pt/Al2O3 CATALYST. II. KINETIC ANALYSIS OF HYDROGEN DEPENDENCE.

ABSTRACT

The conversion of n-octane on Pt/Al₂O₃ catalyst was found to pass through pronounced maxima with the variation of the partial pressure of hydrogen at temperatures between 420°C-460°C, P_N = 7·63 × 10^-3 atm and W/F = 0·11lg min cm_-3. The products of reaction were hydrocracked products, octane, ethylbenzene, o-.p-,m,-xylene and toluene. The order of appearance of the optimum PH for the various reactions were: Isooctane>Dehydrocyclized products>Hydrocracked products.

A sequence of elementary steps earlier postulated was found to predict the maximum in the n-octane P_H profiles for the three temperatures investigated. The rate determining steps for the two rate equations that were found suitable were conversion of adsorbed isooctane to adsorbed o-xylene and ethylbenzene.     

Balancing nutrient inputs to Lake Kivu

The primary production in meromictic Lake Kivu is sustained by external nutrient inputs and by internal loading due to upwelling caused by sub-aquatic sources. We present here the results of external loading of phosphorus (P), nitrogen (N) and silica (Si) by rivers and atmospheric deposition measured from 2006 to 2008. These external inputs are compared to internal loading. The input of soluble-reactive P (SRP), supplied in equal parts from rivers and atmospheric deposition, adds up to 230 t P yr^− 1, 20 times less than total P load. Ammonium (mainly via rainwater) and nitrate (mainly via rivers) are primary sources of the dissolved N load (5400 t N yr^− 1), with both species contributing ∼ 50%. Dissolved Si input (40,000 t Si yr^− 1) is unique in that only ∼ 60% enters by rivers, while the remaining ∼ 40% comes from sub-aquatic sources and atmospheric deposition is negligible. Based on the molar nutrient ratios, we identify P as the limiting factor for algae production. Despite the strong anthropogenic impact on the catchment and the high particle erosion (74 t km^− 2 yr^− 1), the area-specific nutrient mobilization is rather low. The external nutrient input is therefore not the cause for the reported increase of methane production in the last decades. External loading to the epilimnion plays a lesser role for all three nutrients (∼ 10% for SRP, ∼ 25% for dissolved N and ∼ 45% for dissolved Si), as compared to the lake-internal loading by upwelling (90%, 75% and 55%, respectively). Lake Kivu, therefore, is similar to other East African large lakes in that the internal loading exceeds the external loading. Despite the substantial uncertainty of the load estimates of up to 50%, we can conclude that the observed nutrient input is consistent with the primary production of 260 g C m^− 2 yr^− 1 recently measured by Sarmento et al. (2006) and also consistent with the lake-internal fluxes established by Pasche et al. (in press).     

Das Duftmarkieren des Baummarders(Martes martes) unter Gehegebedingungen

Zusammenfassung Das Markierverhalten von drei Baummarderpaaren unterschiedlichen Alters wurde von Januar bis Dezember 1991 erfaßt (Tab. 1). Es wurden folgende Verhaltensweisen differenziert: stoffwechselbedingte Kot- und Urinabgabe, Kotmarkieren, Urinmarkieren, Abdominalreiben, Körperreiben und Hinterlaufscharren (Abb. 1). Hinterlaufscharren und vermutlich auch Körperreiben sind im agonistischen Kontext angesiedelt.Abdominalreiben ist das mit großem Abstand häufigste Markierverhalten (Tab. 2). Abdominalreiben und Urinmarkieren korrelieren in hohem Maße (Tab. 3, 4). Bei beiden Verhaltensweisen trat im jahreszeitlichen Verlauf bei den drei- und fünfjährigen Tieren, insbesondere den Rüden, ein deutliches Häufigkeitsmaximum zwischen März und Mai auf. Die einjährigen Tiere markierten dagegen häufiger im Herbst und Winter (Abb. 2, Tab. 5). Die jahreszeitlichen Unterschiede der Markierhäufigkeit stehen vermutlich im Zusammenhang mit dem Territorialverhalten. Das abweichende Verhalten der einjährigen Tiere wird als eine altersbedingte Anpassung diskutiert.Zum Abdominalreiben wurden immer wieder dieselben Stellen aufgesucht. Diese Markierstellen wurden von beiden Partnern genutzt (Tab. 6). Möglicherweise dienen gemeinsam genutzte Markierstellen im Freiland zum Informationsaustausch.Abdominalreiben tritt gelegentlich mit Artgenossenbezug auf (Tab. 7). Die Tiere markieren auf dem Körper des Partners, mit Blickkontakt zum Partner, oder es wird an einer Stelle markiert, die soeben vom Partner markiert wurde (Übermarkieren). Partnermarkieren konnte bisher bei keinem anderen einheimischen solitären Marderartigen beobachtet werden.

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Scent marking in pine martens (Martes martes) in captivity

Summary The scent marking behaviour of three pairs of pine martens of different ages was recorded from January to December 1991 (Table 1). The following behaviour patterns were differentiated: Defecation and urination, fecal-marking, urine-marking, abdominal rubbing, body rubbing and scratching with the hind-legs (Fig. 1). Scratching with the hind-legs and possibly body rubbing are associated with the agonistic context.Abdominal rubbing is by far the most frequent marking behaviour (Table 2). Abdominal rubbing and urine marking correlate to a high degree (Tables 3, 4). Both behaviour patterns can frequently be seen in the three year old and the five year old animals, especially the males, from March to May, in the one year old animals in autumn and winter (Fig. 2, Table 5). The seasonal changes in marking frequency are considered as connected to the territorial behaviour. The different behaviour of the yearlings is discussed as an age-specific adaptation.Abdominal rubbing always took place at the same sites. These marking sites were used by both partners (Table 6). In natural environments these common marking sites may be used for an exchange of information.Sometimes abdominal rubbing happens in relation to a conspecific (Table 7). The animals mark on the body of the partner (allomarking), in visual contact with the partner, or they mark at a site, which was just marked by the partner (overmarking). Up to now, allomarking was not observed by any other solitary species of native mustelids.

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Le marquage olfactif de la Martre des pins (Martes martes) dans des conditions d'enclos

Résumé Le comportement de marquage de trois couples de Martre des pins d'âge varié a été relevé de janvier à décembre 1991 (Tabl. 1). Les comportements suivants furent identifiés: défécation et miction en tant que conditionnés par le métabolisme, marquage fécal, marquage urinaire, grattage abdominal, grattage corporel et trépignement des postérieurs (Fig. 1). Le trépignement des postérieurs de même que sans doute le grattage corporel se manifestent dans un contexte antagonique.Le grattement abdominal est de loin le comportement de marquage le plus fréquent (Tabl. 2). Le grattement abdominal et le marquage urinaire se trouvent être en corrélation très marquée (Tabl. 3, 4). Les deux modes de marquage présentèrent un pic saisonnier entre mars et mai chez les sujets de 3 et 5 ans, en particulier chez les mâles. Les sujets d'un an, par contre, marquèrent plus fréquemment en automne et en hiver (Fig. 2, Tabl. 5). Les différences saisonnières de fréquence de marquage sont vraisemblablement à mettre en lien avec le comportement territorial. Le comportement singulier des sujets d'un an est présenté comme une adaptation liée à l'âge.En ce qui concerne le grattage abdominal, ce sont toujours les mêmes lieux qui sont visités par les animaux (Tabl. 7). Ces endroits de marquage sont utilisés par chaque partenaire (Tabl. 6). Sans doute ces lieux communs de marquage servent-ils à un échange d'information sur le terrain.Le grattage abdominal se rapporte parfois aux relations d'individu à individu (Tabl. 7): soit les animaux marquent le corps de leur partenaire tout en gardant avec lui un contact visuel, soit le marquage s'effectue à un endroit lequel est aussitôt re-marqué par le partenaire ("sur-marquage"). Le marquage du partenaire n'a pu, jusqu'à présent, être observé sur aucun autre mustélidé indigène à tempérament solitaire.

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Eingesetzt wurde ein Druckkostenzuschuß der Landesjägerschaft Niedersachsen, für dessen Gewährung verbindlich gedankt wird. — Die Schriftleitung

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Eingesetzt wurde ein Druckkostenzuschuß der Landesjägerschaft Niedersachsen, für dessen Gewährung verbindlich gedankt wird. — Die Schriftleitung     

The pars intercerebralis of the locust brain: a developmental and comparative study.

The anterior midline of the brain, also known as the pars intercerebralis, contains the largest collection of neurosecretory cells in the central nervous system of the grasshopper. In this study, we use immunocytochemical, intracellular staining, and histological methods to establish the ontogenies of the various cell types in the brain midline, and show how these cells contribute to the pars intercerebralis of the adult brain. We show that the adult pars intercerebralis develops from three distinct embryonic cell groups: (1) the median neurosecretory cells, which derive from a subset of neuroblasts in the protocerebral hemispheres, and which project axons to the corpora cardiaca; (2) the paired primary commissure pioneers, which derive directly from the mesectoderm of the dorsal median domain and whose axons project to the ventral nerve cord via the midline tract; and (3) the six progeny of the median precursor in the dorsal median domain, which share a common axonal projection with the primary commissure pioneers. Since the adult pars intercerebralis is a fusion product of these independent cellular components, it can only be understood in terms of its origins in the embryonic brain. When the expression pattern of the TERM-1 antigen is compared in subsets of median neurosecretory cells in a wide range of insect orders, the results suggests a common organizational Bauplan for the pars intercerebralis. This hypothesis is supported by the identification of putative homologs of the grasshopper primary commissure pioneers in all these insects.     

Induction of Gushing with Recombinant Class II Hydrophobin FcHyd5p from Fusarium culmorum and the Impact of Hop Compounds on its Gushing Potential

Malt‐induced gushing is a problem that has been known for many years. Mechanisms and inducing agents are still not fully understood and identified. Hydrophobins produced by various filamentous fungi are currently under discussion as biological gushing‐inducing compounds. In the current study the class II hydrophobin FcHyd5p, from the cereal pathogen Fusarium culmorum, was employed in beer and other carbonated beverages for gushing experiments and the influence of hop compounds on gushing potential was examined. It was demonstrated that this protein strongly induces gushing in various carbonated beverages, including beer. It was further demonstrated that the resulting gushing volume is susceptible to certain hop compounds and can be decreased significantly by the addition of these substances.