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Aiming at the problems of low scanning efficiency and difficult real-time imaging of TKIS-I color helmet mechanical scanning single-beam sonar developed in the laboratory at present, research on high-frequency high-resolution multi-beam imaging sonar is proposed. Multi-beam imaging sonar can be pre-formed into multiple beams using electronic scanning technology, which can simultaneously scan and image a large range, greatly improves the scanning efficiency of sonar. This paper will proceed from the two aspects of the output signal of the transducer array and the principle of beamforming to study some characteristics of the uniform linear array multi-beam sonar, and make a theoretical research basis for the development of high-frequency high-resolution multi-beam imaging sonar.

TKIS-I is a helmet-mounted single-beam mechanically scanned color imaging sonar with a working frequency of 678KHz, the beam width of 2.2°, and a maximum detection distance of 100m. It can be carried by a single soldier to complete the operation. It is mainly used for underwater salvage, search and rescue, etc. It has been used in naval forces and has been widely recognized. TKIS-I helmet-mounted colorful imaging sonar has a lower angular resolution effect on close-range targets, and cannot distinguish between close range targets. In this paper, FPGA is added on the basis of the system circuit of TKIS-I helmet-mounted colorful imaging sonar to process high-speed signal, which makes the system work at a frequency of 2. 25MHz. It can effectively improves the angular resolution of close-range underwater targets and enhances the signal strength of target objects. Finally, the imaging test was performed on the 2.25Mhz high-frequency imaging sonar system. From the comparison results, it can be concluded that the angular resolution of the target object has been enhanced.

In order to solve the problem that imaging is greatly disturbed by noise in the application of TKIS series helmet-mounted colorful imaging sonar, anti-noise ability research was conducted on three imaging methods commonly used in imaging sonar systems. In this paper, based on TKIS series helmet-mounted colorful imaging sonar system, the traditional fast Fourier transform (FFT) method, orthogonal-demodulation-based method and linear frequency modulation (LFM) cross-correlation method were used for comparative analysis of anti-noise capability. The imaging experiment of the traditional FFT method has been completed, and the imaging experiment of the other two methods will be completed in the future. The results show that the orthogonal-demodulation-based method has strong noise suppression ability in all scopes of the system, and is more suitable for the upgrade of TKIS series helmet-mounted colorful imaging sonar system.

Background: Loss of heterozygosity (LOH) at 13q22 is a common event in nasopharyngeal carcinoma (NPC). EDNRB gene located at 13q22 has been demonstrated to be hypermethylated in some kinds of tumors. In the current study, we focused on the epigenetic and genetic alterations of EDNRB in NPC. Methods: The mRNA expression of EDNRB was detected by semiquantitative RT-PCR and real-time quantitative PCR in 49 NPC and 12 chronic nasopharyngitis biopsies. The methylation and LOH status of EDNRB were examined by methylation-specific polymerase chain reaction, microsatellite PCR and sequencing. We also examined the mRNA expression of EDNRB in four NPC cell lines after 5-aza-2′-deoxycytidine treatment. Results:EDNRB was downregulated in primary NPC tissues and NPC cell lines, and a relatively higher methylation level of EDNRB was found in NPC biopsies (84%) compared to that in chronic nasopharyngitis biopsies (42%). Treatment of NPC cell lines with 5-aza-2′-deoxycytidine activated EDNRB expression. LOH of EDNRB gene was also found at two microsatellite sites with ratios of 6.25 and 16.67% in NPC. Conclusion: Our results suggested that EDNRB expression may be affected by aberrant promoter methylation and gene deletion and may play a role in the development of NPC.

The lactoferrin (LTF) gene, located at 3p21.3, behaves like a tumor suppressor gene in diverse tumors. To elucidate the exact role of LTF in NPC, we first detected its expression level in seven NPC cell lines by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). The results showed the mRNA level of LTF was nearly undetectable in all the seven NPC cell lines, while it could be detected in chronic nasopharyngitis tissues. Subsequently, we used methylation-specific PCR (MSP), microsatellite assay, PCR-single-strand conformation polymorphism (PCR-SSCP) and sequencing methods to examine the promoter methylation, loss of heterozygosity (LOH) and gene mutation of LTF in NPC cell lines respectively. Consequently, we found that 100% (7 of 7) of NPC cell lines were methylated in LTF promoter, only one cell line (14%, 1 of 7) had LOH and gene mutation of LTF, respectively, while LTF exhibited re-expression in all cell lines after 5-aza-dC treatment, indicating promoter methylation should be the key mechanism causing LTF downregulation in NPC cell lines. Furthermore, patched methylation assay confirmed that promoter methylation could down-regulate LTF gene expression in NPC cells. Finally, we investigated the function of LTF in NPC cell lines by gene transfection. Restoration of LTF expression in NPC cells resulted in blockage of cell cycle progression, significant inhibition of cell growth and a reduced colony-formation capacity in vitro and obviously weaker tumor formation potential in vivo. In conclusion, our data indicate LTF may participate in NPC carcinogenesis as a negative effector, that is, a tumor suppressor gene. J. Cell. Biochem. 112: 1832–1843, 2011. © 2011 Wiley-Liss, Inc.

Loss of heterozygosity (LOH) at 13q22 is a common event in nasopharyngeal carcinoma (NPC). EDNRB gene located at 13q22 has been demonstrated to be hypermethylated in some kinds of tumors. In the current study, we focused on the epigenetic and genetic alterations of EDNRB in NPC.The mRNA expression of EDNRB was detected by semiquantitative RT-PCR and real-time quantitative PCR in 49 NPC and 12 chronic nasopharyngitis biopsies. The methylation and LOH status of EDNRB were examined by methylation-specific polymerase chain reaction, microsatellite PCR and sequencing. We also examined the mRNA expression of EDNRB in four NPC cell lines after 5-aza-2'-deoxycytidine treatment.EDNRB was downregulated in primary NPC tissues and NPC cell lines, and a relatively higher methylation level of EDNRB was found in NPC biopsies (84%) compared to that in chronic nasopharyngitis biopsies (42%). Treatment of NPC cell lines with 5-aza-2'-deoxycytidine activated EDNRB expression. LOH of EDNRB gene was also found at two microsatellite sites with ratios of 6.25 and 16.67% in NPC.Our results suggested that EDNRB expression may be affected by aberrant promoter methylation and gene deletion and may play a role in the development of NPC.