Abstract: The present disclosure provides an N protein epitope mutation marker for preparing an epitope deletion-marked vaccine strain of type II porcine reproductive and respiratory syndrome virus (PRRSV) and use thereof, belonging to the technical field of biological products. In the mutation marker, one or more amino acids are mutated based on an epitope sequence at positions 92 to 103 of a C-terminal of an N protein of the type II PRRSV; and the epitope mutation marker has an amino acid sequence shown in SEQ ID NO: 1, where X1 is selected from the group consisting of T, P, and A; and X2 is selected from the group consisting of V and A.

Abstract: A tracer diffusion device includes: a first container, for holding a first fluid containing a tracer; a second container, for holding a second fluid; a drilling pipe; wherein, a first end of the drilling pipe is connected to the first container; a second end of the drilling pipe is extended into a borehole; and the second end of the drilling pipe is equipped with a first sealing capsule and a second sealing capsule; a plurality of through holes are arranged on the drilling pipe between the first sealing capsule and the second sealing capsule; a unidirectional driving device, arranged on the drilling pipe, for injecting the first fluid from the first container into the borehole between the first sealing capsule and the second sealing capsule; and a bidirectional driving device, arranged between the second container and the first sealing capsule.

Abstract: A device for separating and recovering flat-plate catalyst powder and a method for determining a wear ratio are provided. The device includes a powder separation unit and a powder recovery unit, a powder accumulation bin is respectively connected with a shell and a catalyst powder outlet, a cyclone outlet is configured on an inner side of a recovery shell, and a primary filter and a secondary filter are configured on an inner side wall of the recovery shell.

Abstract: A method includes performing blind spectrum sensing of a frequency band to determine whether a primary user is using the frequency band. The blind spectrum sensing is based at least in part on a comparison between a detection statistic based on a maximum correlation coefficient and a detection threshold based on theoretical computation of a distribution of the detection statistic. The maximum correlation coefficient is for correlations between a plurality of signals corresponding to a plurality of snapshots taken by a cognitive radio of the frequency band and corresponding to a plurality of antennas used by the cognitive radio for taking the snapshots. The method includes determining whether to communicate using the frequency band based on whether the blind spectrum sensing indicates the frequency band is or is not used by the primary user. Apparatus and program products are disclosed.