Generation of metal and metal oxide nanoparticles by liquid flame spray process

A liquid flame spray (LFS) process has been investigated for the generation of single component nanoparticles. In the LFS process, a solution consisting of metal nitrate dissolved in water is sprayed into a turbulent, high temperature H₂-O₂-flame. The primary spray droplets evaporate and subsequent reactions in the flame produce metal or metal oxide vapours which nucleate to final particulate form. In the study, the process characteristics were examined to produce 10–60 nm particles from silver, palladium and iron containing precursors. A systematic study using variable process parameters proved that the size of the generated nanoparticles is set by the mass flow rate of the metal precursor, only. The geometric standard deviation of the size distributions was seen to vary in a limited range of 1.35–1.4. The particle size was verified by aerosol instrumentation, the composition and morphology by X-ray diffraction (XRD) and transmission electron microscopy (TEM), correspondingly. The Ag and Pd particles were seen to consist of pure metals. For iron, the presence of all three of the following compounds were detected: Fe, Fe₂O₃ and Fe₃O₄.     

Breaststroke swimmer's knee. A biomechanical and arthroscopic study

The cause of the breaststroke swimmer's knee with medial pain of the knee joint has not been clearly identified. Breaststroke swimmers with knee pain were, therefore, examined arthroscopically. None showed any other disorders of their knees than medial synovitis in seven of nine swimmers. Since structural abnormalities could be ruled out, biomechanical analyses utilizing cinematographic techniques were used to study patients swimming in a special flume with the speed set at 90% of their best competitive performance. The results indicate that the extension and flexion and also in some cases the hip abduction and adduction movements of the whip kick were performed with high peak angular velocities. No significant differences in swimming technique among the six patients studied and three controls could be observed. It is concluded that a combination of high angular velocities at the hip and knee and external rotation of the tibia relative to the femur repeated in excessive amounts might be the primary cause for the medial synovitis documented in these patients. The breaststroker's knee thus seems to be an overuse syndrome.     

HPLC-ESI-MS/MS characterization of phenolics in <Emphasis Type="Italic">prunus amygdalus</Emphasis>, cultivar “umm alfahm” and its antioxidant and hepatoprotective activity

Metabolite profiling of the total ethanolic extract of Prunus amygdalus stem and leaves was carried out for the first time using LC-DAD-ESI-MS in the negative ion mode to investigate its chemical composition. Results revealed the identification of 33 phenolic compounds. Fifteen compounds were investigated in P. amygdalus for the first time and identified as; veratic acid, rosmarinicacid, protocatechuic acid-hexoside, 3-O-caffeoylquinic acid (neochlorogenic acid), dihydroquercetin- hexoside, coumaroyl-quinic acid, vanillic acid glucoside, cis piceid, hesperidin, dihydrokaempferol, acteoside, quercetin acetyl hexoside, homovanillic acid, fisetin-deoxyhexoside. The antioxidant potential of the total ethanolic extract (EE) and the fractions: petroleum ether (PE), chloroform (CE), ethyl acetate (EtE), methanol eluted diaion (DME) and diaion eluted with 50% methanol (D 50%E) was performed using DPPH assay. The most potent antioxidant EE, EtE and D50%E extracts (compared with vitamin C) were selected for further hepatoprotective assessment against hepatotoxicity induced by thioacetamide in a dose of 200 mg/kg compared with silymarin (50 mg/kg) as a standard drug. Results revealed the significant reversal of the deleterious effects of thioacetamide on serum ALT, AST and total protein in the order: EtE >?(Silymarin?=?EE)?>?D50% E. The biochemical results were corroborated with the histological studies of liver.     

Effects of fungal species,cultivation time,growth substrate,and air exposure velocity on the fluorescence properties of airborne fungal spores

Real‐time bioaerosol monitoring is possible with fluorescence based instruments. This study provides information on major factors that can affect the fluorescence properties of airborne fungal spores. Two fluorescence‐based bioaerosol detectors, BioScout, and ultraviolet aerodynamic particle sizer (UVAPS), were used to study fluorescent particle fractions (FPFs) of released spores of three fungal species (Aspergillus versicolor, Cladosporium cladosporioides, and Penicillium brevicompactum). Two culture media (agar and gypsum board), three ages of the culture (one week, one month, and four months), and three aerosolization air velocities (5, 15, and 27 m/s) were tested. The results showed that the FPF values for spores released from gypsum were typically lower than for those released from agar indicating that poor nutrient substrate produces spores with lower amounts of fluorescent compounds. The results also showed higher FPF values with lower air velocities in aerosolization. This indicates that easily released fully developed spores have more fluorescent compounds compared to forcibly extracted non‐matured spores. The FPFs typically were lower with older samples. The FPF results between the two instruments were similar, except with four‐month‐old samples. The results can be utilized in field measurements of fungal spores to estimate actual concentrations and compare different instruments with fluorescence‐based devices as well as in instrument calibration and testing in laboratory conditions.     

Has the difference in accident patterns between male and female drivers changed between 1984 and 2000?

The motorcar accident pattern of culpable young (18-25 years old) and middle-aged (35-55 years old) male and female drivers was studied in Finland. The aim was to see whether the difference in accident patterns between males and females has remained constant or whether it has changed over a 16-year period. Two different sets of traffic accident data were used. The first set of data covered all motorcar accidents for which damages were paid between 1987 and 2000, a total of 140802 accidents. The second set of data covered all fatal motor vehicle accidents in Finland during the time period between 1984 and 2000, a total of 2401 accidents. The results are analysed and discussed in the framework of a four-level hierarchical model of driving behaviour [Keskinen, E., 1996. Why do young drivers have more accidents? In: Junge, F., Fahrerinnen (Eds.), Young Drivers (in German and in English). Berichte der Bundesanstalt für Strabetaenwesen, Mensch und Sicherheit, Heft M 52, Bergisch Gladbach, Germany; Hatakka, M., Keskinen, E., Gregersen, N.P., Glad, A., Hernetkoski, K., 2002. From control of the vehicle to personal self-control; broadening the perspectives to driver education. Transportation Res. Part F 5 (3), 201-215]. Female drivers had proportionally more accidents that were connected to vehicle manoeuvring and control of traffic situations, e.g. reversing and loss-of-control accidents in a sober state and when not speeding. Male drivers, and especially young male drivers, had proportionally more accidents connected to higher levels of driving behaviour like motives for driving and attitudes. Factors that characterised these accidents were speeding and alcohol consumption. Male drivers also had previous traffic offences more often than female drivers. The study concludes that the difference in accident patterns between male and female drivers has remained constant, i.e. the accident pattern of female drivers was as dissimilar to the accident pattern of male drivers in the year 2000 as in the middle of the 1980s.     

Reductions in particulate and NO(x) emissions by diesel engine parameter adjustments with HVO fuel

Hydrotreated vegetable oil (HVO) diesel fuel is a promising biofuel candidate that can complement or substitute traditional diesel fuel in engines. It has been already reported that by changing the fuel from conventional EN590 diesel to HVO decreases exhaust emissions. However, as the fuels have certain chemical and physical differences, it is clear that the full advantage of HVO cannot be realized unless the engine is optimized for the new fuel. In this article, we studied how much exhaust emissions can be reduced by adjusting engine parameters for HVO. The results indicate that, with all the studied loads (50%, 75%, and 100%), particulate mass and NO(x) can both be reduced over 25% by engine parameter adjustments. Further, the emission reduction was even higher when the target for adjusting engine parameters was to exclusively reduce either particulates or NO(x). In addition to particulate mass, different indicators of particulate emissions were also compared. These indicators included filter smoke number (FSN), total particle number, total particle surface area, and geometric mean diameter of the emitted particle size distribution. As a result of this comparison, a linear correlation between FSN and total particulate surface area at low FSN region was found.     

Characteristics of the liquid flame spray process

Liquid flame spraying (LFS) is a new thermal spray process. Liquid feedstock is injected and atomized in an oxygen-hydrogen flame where the liquid phase is evaporated and thermochemical reactions are completed to produce fine particles. Production of nanoparticles requires a thorough understanding of the process. Therefore, various process stages were studied; i.e., the atomization of liquid feedstock, and characterization of the flame and flame-droplet interactions. Experimental techniques included laser diffraction anemometry for droplet size distribution, laser doppler velocimetry for particle velocity, pulsed laser Rayleigh back scattering for flame temperature and Schlieren photography for flame structure.

Atomization is optimized with an organic solvent, such as isopropanol, nebulized with hydrogen gas at a high flow rate. Liquid droplets injected into the flame are subjected to a maximum temperature of 2600°C and are accelerated to about 160 m s⁻¹. The flame length can be controlled by flame velocity and the solvent type. Water produces a shorter flame whereas ispropanol extends the flame. Injection of the aerosol produces a “pencil-like” region which does not experience turbulence for most of the flame length. Experimentation with manganese nitrate and aluminium isopropoxide or aluminium nitrate showed conversion to a     

The effect of speech and speech intelligibility on task performance

The aim of this study was to find out what are the effects of three different sound environments on performance of cognitive tasks of varying complexity. These three sound environments were 'speech', 'masked speech' and 'continuous noise'. They corresponded to poor, acceptable and perfect acoustical privacy in an open-plan office, respectively. The speech transmission indices were 0.00, 0.30 and 0.80, respectively. Sounds environments were presented at 48 dBA. The laboratory experiment on 36 subjects lasted for 4 h for each subject. Proofreading performance deteriorated in the 'speech' (p < 0.05) compared to the other two sound environments. Reading comprehension and computer-based tasks (simple and complex reaction time, subtraction, proposition, Stroop and vigilance) remained unaffected. Subjects assessed the 'speech' as the most disturbing, most disadvantageous and least pleasant environment (p < 0.01). 'Continuous noise' annoyed the least. Subjective arousal was highest in 'masked speech' and lowest in 'continuous noise' (p < 0.05). Performance in real open-plan offices could be improved by reducing speech intelligibility, e.g. by attenuating speech level and using an appropriate masking environment.     

Instrumentation for measuring fluorescence cross sections from airborne microsized particles

An experimental instrument for measuring a laser-induced fluorescence spectrum from a single aerosol particle is described. As a demonstration of instrument capabilities, the results of monodisperse 4.7 microm sodium chloride particles doped with fluorescent riboflavin, produced with an inkjet aerosol generator, are presented. The fluorescence of the aerosol particles is excited in the wide range from 210 to 419 nm using a pulsed, tunable optical parametric oscillator laser. The maximum of the fluorescence emission of separately measured particles is detected at 560 nm. The dependence of the fluorescence on the excitation wavelength is studied and fluorescence cross sections are estimated. Agreement between the measured fluorescence data and the literature data for riboflavin is observed.