Dynamics of nonlinear waves in the tubes filled with aerosol

The results of experimental investigations of nonlinear oscillations of finely dispersed aerosol in the tube with various geometry on the end in the shock-wave, the shock-free wave modes and in the mode of transition to shock waves near the resonance frequency are presented. The time dependences of the numerical concentration of the oscillating aerosol droplets are presented. The effect of the frequency and amplitude of the piston displacement and the influence of the diaphragm internal diameter on the time coagulation and sedimentation of aerosol were studied. An increase in the amplitude of the piston displacement in all modes results in acceleration of the process of coagulation and sedimentation of aerosol. The dependence of time of coagulation and sedimentation of aerosol on the excitation frequency was found to be of a nonmonotonic character with the minimum value upon the resonance frequency.

Analysis of an Authentic Historical Italian Cosmetic Talc Sample – Further Evidence for the Lack of Cancer Risk

Italian talc from the Pinerolo Mines in North West Italy is known for its extreme purity. Several historical investigations of these mines have demonstrated very small amounts of tremolite in the host rock that occasionally found their way into the mined ore. However, more than sixty years of epidemiological studies of the Pinerolo miners and millers have failed to demonstrate any attendant cancer risk and show that this trace tremolite contamination is of no biological significance.Claims made that the Pinerolo Italian cosmetic talc produced prior to 1975 were contaminated with asbestos, principally tremolite, have been difficult to refute given the lack of authentic historical samples of commercial products. We now describe the analytical findings of a recently discovered authentic historical sample.Sample analyses of this material showed only a few non-asbestiform tremolite fibres - a finding discussed in the light of the historical (pre-1975) studies of this talc deposit: no serpentine (chrysotile) or amphibole fibres were detected.The numerical concentration of tremolite fibres in the talc sample was 3.687 x 106 fibres/gram, corresponding to a mass concentration of 0.722 parts per million.

The vertical distribution of buoyant plastics at sea

Millimeter-sized plastics are numerically abundant and widespread across the world's ocean surface. These buoyant macroscopic particles can be mixed within the upper water column due to turbulent transport. Models indicate that the largest decrease in their concentration occurs within the first few meters of water, where subsurface observations are very scarce. By using a new type of multi-level trawl at 12 sites within the North Atlantic accumulation zone, we measured concentrations and physical properties of plastics from the air–seawater interface to a depth of 5 m, at 0.5 m intervals. Our results show that plastic concentrations drop exponentially with water depth, but decay rates decrease with increasing Beaufort scale. Furthermore, smaller pieces presented lower rise velocities and were more susceptible to vertical transport. This resulted in higher depth decays of plastic mass concentration (mg m−3) than numerical concentration (pieces m−3). Further multi-level sampling of plastics will improve our ability to predict at-sea plastic load, size distribution, drifting pattern, and impact on marine species and habitats.

Nonlinear oscillations of aerosol in shock-wave flow in open tube

Nonlinear oscillations of aerosol in open tube in shock-free wave mode at resonance at various amplitudes of excitation are experimentally investigated. Pressure diagrams are continuous. With an increase in the excitation amplitude, the amplitude of the pressure oscillations of the medium increases. At large amplitudes, the oscillation form is close to harmonic. The numerical concentration of aerosol droplets decreases monotonically with time. This is due to the coagulation of the aerosol, which consists in the coalescence of droplets and their sedimentation on the walls of the tube, as well as the emission of the aerosol into the surrounding space. With an increase in the excitation amplitude, the dependences acquire greater curvature and the aerosol clearing time decreases. At the same time, the aerosol clearing time is 5-10 times lower than in the case of natural sedimentation.

Use of dietary tea seeds to manipulate the rumen ciliate protozoa population in sheep

Eighteen rumen cannulated sheep in three groups of six were supplemented with tea seeds at 0 (control), 3 or 6% of the dietary dry matter in a 22-d experiment. Rumen fluid samples were collected on 3 d before and on various days during the experiment. The concentration of protozoa in rumen fluid was not affected by the tea seed supplements (P > 0.05), but the numerical concentration of the Entodinium genera declined by 12% (P < 0.05) and that of cellulolytic protozoa increased by 90% (P < 0.05) due to the 6% tea seed supplement. The associated percentage in the rumen ciliate protozoa population of the cellulolytic protozoa increased (P < 0.05) and that of the Entodinium genera decreased (P < 0.05) due to the 6% supplement. There were no effects (P > 0.05) of the 3% tea seed supplement on the protozoa population parameters. Since ammonia and volatile fatty acid concentrations were not affected (P > 0.05) it was apparent that the tea seed supplements did not influence rumen fermentation. The positive effect of the 6% tea seed supplement on the ciliate protozoa population obtained in the present study was relatively modest. Because the seeds contain astringent properties, higher than 6% dietary supplements of tea seeds can be harmful to animals. It was therefore concluded that tea seeds are of no apparent value as an antiprotozoal dietary component in ruminant production. Key words: Tea seeds, ciliate protozoa, rumen fluid, sheep