RESUMO
A cadmium column reduction-azo dyes spectrophotometric method based on micro sequential injection lab-on-valve was established for the determination of total nitrogen in seawater. The experimental parameters were optimized, and the interference experiment was carried out. The results showed that the interference of the main components and salinity in sea water could be eliminated by using a series of standard solution prepared by national standard seawater with certain salinity. The concentration of total nitrogen in seawater was linear with the absorbance in the range of 0 . 03-1 . 00 mg/L with a correlation coefficient of 0. 9993. When determining the national standard seawater at nitrogen concentration of 0. 20 mg/L, the relative standard deviation (RSD) was 4. 9%, the detection limit was 0. 010 mg/L, and the recoveries were 99. 5%-101 . 1%. There were not significance differences between the results of this method and national standard method in the t-test analysis. The method is suitable for the determination of total nitrogen in seawater.
RESUMO
<p><b>OBJECTIVE</b>To determine the mid-term effects of cutting balloon angioplasty (CBA) on in-stent restenosis.</p><p><b>METHODS</b>A total of 69 patients with in-stent restenosis were divided into 2 groups randomly: cutting balloon angioplasty and plain old balloon angioplasty. The mechanisms of restenosis and dilation results were determined by quantitative coronary angiography and intravascular ultrasound. Follow-up was performed.</p><p><b>RESULTS</b>The procedural success rate was 100% without death and acute closure. One patient experienced dissection at the distal end of the stent and needed another stent. The mean follow-up period was 6.7 +/- 2.3 months. The final re-restenosis rate was 15% and 18% at 3 months and 6 months respectively, markedly lower than after plain old balloon angioplasty (38% and 43%). Acute gain by intravascular ultrasound (IVUS) was 1.72 +/- 0.52 mm after cutting balloon angioplasty, higher than 1.15 +/- 0.54 mm after plain old balloon angioplasty. The lumen diameter late loss in the cutting balloon group was 0.26 +/- 0.05 mm and 0.38 +/- 0.06 mm at 3 months and 6 months respectively, significantly lower than for those in conventional balloon group (0.78 +/- 0.19 mm and 0.89 +/- 0.16 mm, respectively, P < 0.001). As shown by IVUS, the main mechanism of cutting balloon angioplasty was marked reduction of plaque area without significant increase of vessel area (less vessel trauma).</p><p><b>CONCLUSION</b>Cutting balloon angioplasty is feasible and effective for the treatment of in-stent restenosis with less vessel trauma.</p>