We investigate the beam focusing technology of shear-vertical(SV) waves for a contact-type linear phased array to overcome the shortcomings of conventional wedge transducer arrays. The numerical simulation reveals the...We investigate the beam focusing technology of shear-vertical(SV) waves for a contact-type linear phased array to overcome the shortcomings of conventional wedge transducer arrays. The numerical simulation reveals the transient excitation and propagation characteristics of SV waves. It is found that the element size plays an important role in determining the transient radiation directivity of SV waves. The transient beam focusing characteristics of SV waves for various array parameters are deeply studied. It is particularly interesting to see that smaller element width will provide the focused beam of SV waves with higher quality, while larger element width may result in erratic fluctuation of focusing energy around the focal point. There exists a specific range of inter-element spacing for optimum focusing performance. Moreover, good beam focusing performance of SV waves can be achieved only at high steering angles.展开更多
This study focuses on the isolation and characterization of a novel strain of siderophore producing bacterium, i.e., Pseudomonas aeruginosa BUP2 (Pa BUP2) from the rumen of Malabari goat, coupled with qualitative and ...This study focuses on the isolation and characterization of a novel strain of siderophore producing bacterium, i.e., Pseudomonas aeruginosa BUP2 (Pa BUP2) from the rumen of Malabari goat, coupled with qualitative and quantitative analyses of the siderophore produced by it. Pa BUP2—a facultative anaerobe was tuned to be an aerobe by repeatedly growing in Benjamin flask. The new isolate was grown in a specially designed semi-synthetic medium, designated as BUP medium, and the yellowish-green pigment produced was identified as a typical siderophore by spectrophotometry, Chromazurol-S assay, thin layer chromatography and isolectric focusing (IEF). The characteristic orange fluorescence upon UV irradiation on chromatogram and absorption maximum at λ404 confirmed that the characteristic siderophore produced by Pa BUP2 was a typical pyoverdine (PVD). This PVD was further categorized under type 2 by comparing its profile on the IEF gel with that of the representative strains of each PVD types, viz., Pa O1, Pa ATCC 27853 and Pa6. Moreover, the type 2 PVD was purified by XAD-4 Amberlite column chromatography and quantified;maximum yield (11.17 mg/ml) was observed on day 4 of incubation (37°C). Thus, it was confirmed that the bacterium isolated from the rumen content of Malabari goat is a novel strain of Pa capable of producing large quantity of PVD type 2 in specially designed BUP medium under aerobic condition, and that its clinical and industrial implications remain elusive.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11774377 and 11574343)。
文摘We investigate the beam focusing technology of shear-vertical(SV) waves for a contact-type linear phased array to overcome the shortcomings of conventional wedge transducer arrays. The numerical simulation reveals the transient excitation and propagation characteristics of SV waves. It is found that the element size plays an important role in determining the transient radiation directivity of SV waves. The transient beam focusing characteristics of SV waves for various array parameters are deeply studied. It is particularly interesting to see that smaller element width will provide the focused beam of SV waves with higher quality, while larger element width may result in erratic fluctuation of focusing energy around the focal point. There exists a specific range of inter-element spacing for optimum focusing performance. Moreover, good beam focusing performance of SV waves can be achieved only at high steering angles.
文摘This study focuses on the isolation and characterization of a novel strain of siderophore producing bacterium, i.e., Pseudomonas aeruginosa BUP2 (Pa BUP2) from the rumen of Malabari goat, coupled with qualitative and quantitative analyses of the siderophore produced by it. Pa BUP2—a facultative anaerobe was tuned to be an aerobe by repeatedly growing in Benjamin flask. The new isolate was grown in a specially designed semi-synthetic medium, designated as BUP medium, and the yellowish-green pigment produced was identified as a typical siderophore by spectrophotometry, Chromazurol-S assay, thin layer chromatography and isolectric focusing (IEF). The characteristic orange fluorescence upon UV irradiation on chromatogram and absorption maximum at λ404 confirmed that the characteristic siderophore produced by Pa BUP2 was a typical pyoverdine (PVD). This PVD was further categorized under type 2 by comparing its profile on the IEF gel with that of the representative strains of each PVD types, viz., Pa O1, Pa ATCC 27853 and Pa6. Moreover, the type 2 PVD was purified by XAD-4 Amberlite column chromatography and quantified;maximum yield (11.17 mg/ml) was observed on day 4 of incubation (37°C). Thus, it was confirmed that the bacterium isolated from the rumen content of Malabari goat is a novel strain of Pa capable of producing large quantity of PVD type 2 in specially designed BUP medium under aerobic condition, and that its clinical and industrial implications remain elusive.
