Particle velocity measurement within a free-falling particle curtain using microscopic shadow velocimetry.

We report an optical method for particle velocity measurement that is suitable for the measurement of particle velocities within dense particle-laden flows with high spatial resolution. The technique is based on particle shadow velocimetry with the use of a long-distance microscopic lens for images collection. The narrow depth of field of the lens allows particles within the focal plane to have much higher pattern intensities than those outside it on the collected images. Data processing was then employed to remove particles from outside the focal plane based on the gradient of the signal and a threshold. Following this, particle velocity was calculated from two successive images in the usual way. The technique was successfully demonstrated in a free-falling particle curtain with volume fractions in the four-way coupling regime of near-spherical micro-particles falling under gravity. The method was successfully employed to measure the transverse velocity profile through the curtain, which is the first time that such a measurement has been performed. Other highly-fidelity experimental data, which is also well suited to model development and validation, include the particle mass flow rate, curtain thickness and opacity.

[Isolation and identification of Banna virus from mosquito for the first time in Inner Mongolia].

OBJECTIVE: To identify the virus isolated from a mosquito Culex modestus collected from Tongliao city of Inner Mongolia Autonomous Region. METHODS: A strain of virus isolated from mosquito in Tongliao city was identified by serological and molecular biological methods. The nucleotides of the virus isolate were amplified by RT-PCR, and the products were purified and sequenced. Multiple alignment, phylogenetic and amino acid (AA) analysis were carried out by software Clustal X, MEGA4 and MegAlign (DNAStar). RESULTS: The new isolate was identified to be Banna virus by serological and molecular biological methods. Phylogenetic analysis showed that the Chinese isolates were distributed within one cluster. The homologue of nucleotide and amino acid of 12 segments between the new isolate and other strains isolated from China were 89.6%-98.4% and 90.4%-98.6%. CONCLUSION: The virus isolated from Culex modestus in Inner Mongolia belonged to Banna virus, and it is the first time that Banna virus was isolated in this region.