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931.
Comparative tests on spruce glulam members subject to tension and bending, respectively, were numerically simulated to determine the tensile-to-bending-strength ratio. Nine different grading methods were applied to cover a wide strength range. They are based on visual inspection and mechanical determination of density and MOE. The simulated tensile and bending strength values result in an almost constant tensile-to-bending-strength ratio of 0.88. The ratio is valid for fifth percentile values and for standardized tests with prescribed member sizes. It is independent of the grading method used. In addition the size effect in glulam tension members was numerically studied. The results show a strong dependence of the glulam tensile strength upon the length subject to tension in case of short members. The dependence slowly wears off in case of long members. The tensile strength for members 150 mm in length is 140 percent of the reference value. The limit strength for a quasi-infinite length is about 80 percent. 相似文献
932.
Hans-Ulrich Waiblinger Marc Ohmenhaeuser Stefanie Meissner Miriam Schillinger Klaus Pietsch Ottmar Goerlich Joachim Mankertz Kathrin Lieske Hermann Broll 《Journal für Verbraucherschutz und Lebensmittelsicherheit》2012,7(3):243-254
In this work, the in-house and interlaboratory validation of a DNA extraction method from pollen in an unifloral rape honey as well as several multifloral honeys is described. The amplifiability of plant and rape DNA amplifiable by real-time PCR was used as a parameter for the evaluation of the method. The practical (i.e., relative) limit of detection was used as a tool for assessing the suitability of the extraction method for further GMO analysis. In a collaborative study with 14 participating labs the results of the in-house validation could be confirmed. The amount of amplifiable plant and rape DNA varied depending on the type of honey. For rape honey, a mean practical LOD of 0.12?% was obtained. 相似文献
933.
934.
Tanin Kangwanpongpan Francis H.R. França Rodrigo Corrêa da Silva Paulo Smith Schneider Hans Joachim Krautz 《International Journal of Heat and Mass Transfer》2012,55(25-26):7419-7433
Oxy-fuel combustion is one of the promising options for carbon dioxide capture in future coal power plants. Radiative properties of combustion gases and heat transfer characteristics inside oxy-fuel furnaces are different from those found in air-fired furnace. Nowadays, few publications provide appropriate radiation property correlations for oxy-fuel conditions. The available correlations are based on previous versions of HITRAN database, which is not accurate for prediction of spectral intensities at high temperature in combustion applications or above 1000 K. This paper considers the determination and evaluation of new correlations for the weighted-sum-of-gray-gases model to predict the radiative transfer in gases under oxy-fuel conditions. The new correlations are fitted from emittance charts calculated from the up-to-date HITEMP 2010 database for molar ratios of water vapor to carbon dioxide between 0.125 and 4, temperature range of 400–2500 K, and pressure path-length varying from 0.001 to 60 bar m. The new correlations are validated by comparing the radiative source term with line-by-line calculations from HITEMP 2010 database for a one-dimensional slab system. The radiative transfer equation is solved with the discrete ordinate method. 相似文献
935.
Males of the parasitic wasp Nasonia vitripennis (Hymenoptera: Pteromalidae) attract virgin females by releasing a sex pheromone composed of (4R,5R)- and (4R,5S)-5-hydroxy-4-decanolide (HDL). The pheromone is biosynthesized in the rectal vesicle of males. In the present study, we investigated
the mechanism and behavioral context of pheromone release, and determined the range of activity and the longevity of the chemical
signal. Our data show that the sex pheromone of N. vitripennis is substrate-borne and is deposited on surfaces by dabbing movements of the abdominal tip, a behavior previously described
in N. vitripennis males as ‘abdomen dipping’. Chemical markings deposited by a single male were highly attractive to virgin females. Chemical
analyses revealed the presence of HDL in surface washings of marked areas, and HDL amounts correlated with male marking activity.
Pheromone deposition occurred spontaneously without any additional cues being present, but marking intensity increased greatly
after copulation or after a single contact with a virgin female. In contrast, marking intensity was not influenced by the
presence of host puparia. Male pheromone deposits were perceived by females in a still-air olfactometer at distances of up
to 4.5 cm and remained attractive for at least 2 h. The function of the substrate-borne sex pheromone is discussed with respect
to the mating system of N. vitripennis. 相似文献
936.
Marcus Nagle Juan Carlos González‐Azcárraga Sarawut Phupaichitkun Busarakorn Mahayothee Methinee Haewsungcharern Serm Janjai Hermann Leis Joachim Müller 《International Journal of Food Science & Technology》2008,43(11):1979-1987
Bulk layer shifting during industrial drying of whole longan was evaluated. Analysis of drying conditions and product quality of samples from different areas of the dryer was conducted. The study found that both temperature and air velocity were non‐uniformly distributed during drying, which affected drying kinetics and product quality. High humidity and convective cooling of the drying air passing through the bulk caused condensation on fruits surfaces in the upper layer during the initial hours of drying. Those samples towards the sides of dryer, those initially in the upper layers, and especially those near the air inlet showed consistently lower quality. Four shifting schemes were tested, one of which was found to be exceptional in terms of end‐product uniformity. Issues concerning the improvement of industrial longan drying are addressed and an optimal shifting procedure is proposed. 相似文献
937.
o-Aminobenzalphenylhydrazon, ein spezifisches Reagens auf salpetrige S?ure und deren Salze (Nitrite)
Heinrich Pfeiffer 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1948,88(3):287-290
Zusammenfassung o-Aminobenzalphenylhydrazon (Nitrin)1 wird als spezifisches Reagens auf salpetrige Säure und deren Salze (Nitrite) vorgeschlagen. Vor anderen Nitritreagenzien hat Nitrin den Vorzug, daß intensive Farbreaktionen in 2 Phasen auftreten. Außerdem wird die Reaktion weder durch oxydierende noch durch redurierende Substanzen beeinflußt. Herstellungsweise und Analysengang werden beschrieben, eine Zusammenstellung der Anwendungsmöglichkeiten wird gegeben. 相似文献
938.
Joachim Say Chye Loo Chui Ping Ooi Meng Lu Tan Freddy Yin Chiang Boey 《Polymer International》2005,54(4):636-643
The purpose of this study was to examine how the presence of crystals can retard electron‐beam (e‐beam) radiation degradation, and their effects on the thermal and morphological properties of poly(lactide‐co‐glycolide) (PLGA) upon e‐beam irradiation. Isothermal annealing at 115 °C was carried out on PLGA films and the effect of different annealing times on the degree of crystallinity (DOC) of PLGA was recorded. The DOC increased with annealing time to a maximum value, and remained unchanged with further annealing. The annealed films were then e‐beam irradiated at doses of 5, 10, 20 and 30 Mrad. The degradation of the films was studied by measuring the changes in their molecular weight, DOC, thermal properties and FTIR spectra. It was observed that, regardless of the DOC of the films, the molecular weight of PLGA generally decreased with increasing radiation dose, indicating that chain scission is dominant. However, the extent of degradation is less for the films with a higher DOC. The thermal properties of PLGA also decreased with increasing radiation dose. Radiation increases the DOC for films with initial crystallinity below 5 % but decreases the DOC for films with initial crystallinity above 5 %. Crystals in PLGA films decreased the extent of radiation degradation. Copyright © 2005 Society of Chemical Industry 相似文献
939.
940.
Joachim Molkentin Hans Meisel Ines Lehmann Hartmut Rehbein 《European Food Research and Technology》2007,224(5):535-543
Using isotope ratio mass spectrometry (IRMS), the ratios of carbon (δ
13C) and nitrogen (δ
15N) stable isotopes were investigated in raw fillets of differently grown Atlantic salmon (Salmo salar) in order to develop a method for the identification of organically farmed salmon. IRMS allowed to distinguish organically
farmed salmon (OS) from wild salmon (WS), with δ
15N-values being higher in OS, but not from conventionally farmed salmon (CS). The gas chromatographic analysis of fatty acids
differentiated WS from CS by stearic acid as well as WS from CS and OS by either linoleic acid or α-linolenic acid, but not
OS from CS. The combined data were subjected to analysis using an artificial neural network (ANN). The ANN yielded several
combinations of input data that allowed to assign all 100 samples from Ireland and Norway correctly to the three different
classes. Although the complete assignment could already be achieved using fatty acid data only, it appeared to be more robust
with a combination of fatty acid and IRMS data, i.e. with two independent analytical methods. This is also favourable with
respect to a possible manipulation using suitable feed components. A good differentiation was established even without an
ANN by the δ
15N-value and the content of linoleic acid. The general applicability in the context of consumer protection should be checked
with further samples, particularly regarding the variability of feed composition and possible changes in smoked salmon. 相似文献