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131.
Jaakko Yli-Ojanperä Hiromu Sakurai Kenjiro Iida Jyrki M. Mäkelä Kensei Ehara Jorma Keskinen 《Aerosol science and technology》2013,47(11):1163-1173
We carried out a set of experiments to compare three particle number concentration standards (NCSs) by calibrating the same condensation particle counter (CPC) unit (Model 3772, TSI Inc., Shoreview, MN, USA). The standards were, in the order of operation size range, the primary NCS of the National Institute of Advanced Industrial Science and Technology (AIST, Japan), the Single Charged Aerosol Reference (SCAR) (Finland), and the Inkjet Aerosol Generator (IAG) of AIST. The results obtained with the 3 standards were found to agree at all overlapping particle sizes within the uncertainty limits. The relative expanded uncertainties varied between 0.6% and 2.6%, depending on the size and standard, while the overall agreement between the standards was within 0.5%. The observed consistency of the results is an important step toward establishing internationally coherent particle NCSs. As a result, the CPC 3772 was successfully calibrated in a particularly wide size range, approximately from 10 nm to 10 μm. The results indicate that the CPC can be considered as a practical tool for calibrating particle number concentration up to 1 μm. In general, the particle number concentration can be measured up to 2.5 μm without a significant decrease of the detection efficiency. By attaching an appropriate size-classifying inlet, the CPC could be used even for measuring the total number concentration for particles smaller than 2.5 μm, in parallel with the PM2.5 mass measurement. Above this particle diameter, the detection efficiency gradually decreased and reached 50% at about 10 μm. Copyright 2012 American Association for Aerosol Research 相似文献
132.
Analysis of aircraft impact to concrete structures 总被引:1,自引:0,他引:1
Analysis of aircraft impact to nuclear power plant structures is discussed utilizing a simplified model of a “fictitious nuclear building” to perform analyses using LS-DYNA software, representing the loading: (i) by the Riera force history method and (ii) by modeling the crash by impacting a model of a plane similar to Boeing 747-400 to the structure (i.e., “missile–target interaction method”). Points discussed include: (1) comparison of shock loading within the building as obtained from the Riera force history analysis versus from the missile–target interaction analysis, (2) sensitivity of the results on the assumed Riera force loading area, (3) linear versus nonlinear modeling and (4) on failure criteria. 相似文献
133.
Alkali chlorides are often involved in superheater tube fouling and corrosion problems, especially during biofuel combustion. We have carried out a modelling study on fume particle and condensable alkali chloride vapour behaviour in superheater tube boundary layers. Two models of boundary layer aerosol behaviour are presented: one is a general computational fluid dynamics (CFD)-based model and the other one is a one-dimensional boundary layer theory-based model for the stagnation point. Simulations of NaCl behaviour in recovery boiler panel heat exchangers indicated that both (1) boundary layer condensation and subsequent particle thermophoretic deposition and (2) direct vapour deposition are significant deposition mechanisms for NaCl. In the first panel tube boundary layer, NaCl is clearly supersaturated, while further in the panel section boundary layer, it seems to be closer to the thermodynamic equilibrium. As the surface temperature of the ash deposit layer increases during a soot-blowing cycle from 480 to 670 °C, the overall deposition rate of NaCl remains fairly constant (increases only by 52%) due to boundary layer aerosol dynamics. Homogeneous nucleation within boundary layers may take place at certain conditions. Additionally, we have made estimates of the subsequent behaviour of deposited alkali chlorides. The rates of deposit sulphation and generation of HCl(g) do not seem to be sensitive to alkali chloride deposition rates provided that SO2 levels are sufficiently low. 相似文献
134.
Mikko Kiirikki Juha Haapamki Jorma Koponen Ari Ruuskanen Juha Sarkkula 《Environmental Modelling & Software》1998,13(5-6)
One of the most visible symptoms of eutrophication in the Gulf of Finland is blooms of unattached filamentous algae. This decomposing algal biomass causes serious nuisance problems for recreational uses of the coastal zone, particularly when cast ashore. The nutrient availability for these macroscopic filamentous algae is regulated by a superior competitor, the phytoplankton. Nutrients are left for the weaker competitor only when the conditions are not suitable for the growth of phytoplankton. This happens during vertical mixing of the water column. The lack of stratification prevents the formation of phytoplankton blooms, but does not limit the growth of filamentous algae when still growing attached to the bottom. A simple growth model was developed to describe the growth and biomass of filamentous algae. In the absence of suitable nutrient measurements, the model was linked to a 3D-ecohydrodynamic model which generated the nutrient input data. The model was calibrated with three-year monitoring data of filamentous algal biomass at one location. Validation was carried out with one-year monitoring data from an adjacent location. The model was able to describe the number of biomass peaks and their timing with good accuracy. After further development, the filamentous algal model will be used as one of the management tools for the evaluation of the sustainable nutrient load to the Gulf of Finland. 相似文献
135.
An Van Cleempoel Jorma Joutsensaari Esko Kauppinen Renaat Gijbels Magda Claeys 《Fullerenes, Nanotubes and Carbon Nanostructures》1998,6(4):599-627
Aerosol routes were used to produce fullerene particles in the nanometer size range. Particle formation mechanisms at processing temperatures of 400-700°C were studied by measuring particle number and mass size distributions in the gas phase by a differential mobility analyzer and a low-pressure impactor respectively. Subsequently, the foils of the impactor onto which fullerene particles were collected were examined by HPLC. 相似文献
136.
Joanna Cybi
ska Jorma Hls Mika Lastusaari Janina Legendziewicz Gerd Meyer Claudia Wickleder 《Journal of Alloys and Compounds》2004,380(1-2):27-33
The high resolution absorption, luminescence and excitation spectra of the orthorhombic potassium lanthanum praseodymium ternary chloride, K2La1−xPrxCl5, (0.02 ≤ x ≤ 0.15) single crystals were recorded at 4, 77 and 293 K with different excitation sources. The experimental 4f2 energy level scheme of the Pr3+ ion in K2LaCl5 derived from the absorption and emission spectra consisted of 86 (out of 91) Stark components. This energy level scheme was simulated by using a phenomenological crystal field (cf) model which included eight free ion and nine cf parameters according to the C2v symmetry. Despite the approximate C2v point symmetry instead of the real Cs one, the simulation yielded a very satisfactory rms deviation of 17 cm−1 between the experimental and calculated energy level schemes. The results, especially the weak cf strength, are discussed taking into account the bonding characteristics in K2LaCl5. 相似文献
137.
Magnetization transfer (MT) imaging provides a novel opportunity to characterize interactions between tissue water and macromolecules. Although severalin vitro investigations have shown that proteins and lipids are important determinants of MT, the contribution of DNA is still unknown. This study was designed to determine whether DNA and cell nuclear material exhibit MT. We measured the magnetization transfer effect of pure DNA strands and purified bovine sperm head nuclei. Although no transfer of magnetization could be detected in samples of pure DNA strands, the sperm head nuclei exhibited a strong MT effect that increased with increasing solid content of the samples. Since the purified bovine sperm head samples consist of large nuclei with only minor traces of perinuclear matrix, the measured MT effect arises from the chromatin of the nuclei. The DNA fills 90% of the nuclear volume and it is extremely tightly packed as chromatin fibers by nucleoproteins. We hypothesize that the numerous intra- and intermolecular disulfide bonds that stabilize the chromatin fibers restrict the movement of the surface water binding sites of both DNA and protamines and thus facilitate the transfer of magnetization. Therefore, the results indicate that the amount of nuclear material may positively contribute to MT in tissues. 相似文献
138.
Iko Hyppnen Jorma Hls Jouko Kankare Mika Lastusaari Laura Pihlgren 《Optical Materials》2009,31(12):1787
Up-converting yttrium oxysulfide nanomaterials doped with ytterbium and erbium (Y2O2S:Yb3+,Er3+) were prepared with the flux method. The precursor oxide materials were prepared using the combustion synthesis. The morphology of the oxysulfides was characterized with transmission electron microscopy (TEM). The particle size distribution was 10–110 nm, depending on the heating temperature. According to the X-ray powder diffraction (XPD), the crystal structure was found hexagonal and the particle sizes estimated with the Scherrer equation agreeded with the TEM images. Upon the 970 nm infrared (IR) laser excitation, the materials yield moderate green ((2H11/2, 4S3/2) → 4I15/2 transition) and strong red (4F9/2 → 4I15/2) luminescence. The green luminescence was enhanced with respect to the red one by an increase in both the crystallite size and erbium concentration due to the cross-relaxation (CR) processes. The most intense up-conversion luminescence was achieved with xYb and xEr equal to 0.10 and 0.005, respectively. Above these concentrations, concentration quenching occurred. 相似文献
139.
140.
Alcohol has been reported to increase the urinary excretion of dolichols, and urinary dolichols are suggested to be derived
from the lysosomes of the renal cells. In the present study we examined the effects of alcohol and glucagon on the biliary
excretion of dolichols in rats. Chronic ethanol treatment decreased both biliary dolichol and β-hexosaminidase excretion.
The absolute amount of dolichol excreted into the bile correlated highly significantly with the absolute amount of biliary
β-hexosaminidase. Our results indicate that biliary dolichols are—at least in part—derived from hepatic lysosomes. Decreased
biliary dolichol output during chronic alcohol administration suggests that urinary and biliary dolichol excretions are regulated
independently of each other. 相似文献