Investigation and identification of breath acetone as a potential biomarker for type 2 diabetes diagnosis

Acetone is regarded as a promising biomarker for the noninvasive diagnosis and monitoring of diabetes.We collected breath acetone from 25 type 2 diabetics(T2D)and 44 healthy subjects using aluminum foil bags(3 L),and the samples were analyzed by gas chromatography–mass spectrometry.T2D patients had significantly higher acetone levels(mean=2.167 ppmv(1 ppmv=1 lL/L),standard error(SE)=0.231)than healthy volunteers(mean=0.488 ppmv,SE=0.025;P\0.0001).The receiver operating characteristics curve showed that the optimum diagnostic cutoff value for exhaled acetone was 0.891 ppmv(area under the curve 0.999,sensitivity 100%,and specificity 97.7%)in T2D patients relative to healthy subjects.Thus,breath acetone could be a useful marker for the high accuracy diagnosis and monitoring of diabetes.In addition,the ratios of the mean acetone concentration in ambient air relative to that in the total exhaled air and in the net exhaled air were 1:18 and 1:17,respectively.The post-breakfast acetone concentrations(mean=0.437 ppmv,SE=0.035)were slightly lower than the pre-breakfast levels(mean=0.553 ppmv,SE=0.047;P[0.05).Thus,the increased acetone concentrations in T2D patients are affected strongly by physiological factors related to the disease,rather than the ambient air and diet.

Characterization of the globular oxide inclusion ratings in steel using laser-induced breakdown spectroscopy

Grade assessment of steel is generally performed via the metallographic method, which is time-consuming and is not able to provide the elemental distribution information. In this paper, we present a method to measure the globular oxide inclusion ratings in steel using laser-induced breakdown spectroscopy (LIBS). The measurement is performed in two basic steps: steel samples are polished using metallographic sand paper and the Al2O3 inclusion number and size distribution in a marked area are observed using scanning electron microscope/energy dispersive X-ray spectroscopy (SEM/EDS) for further LIBS scanning analysis. The threshold intensity that distinguishes soluble aluminum and insoluble aluminum inclusions is determined using LIBS combined with the SEM/EDS statistical data. Carbon steel (the sample number is S9256) and bearing steel (the sample number is GCr15) are analyzed in scanning mode, and the number of Al2O3 inclusions in different size ranges is obtained from the statistical information derived from the Al2O3 size calibration curve. According to heavy and thin series for globular oxide inclusions grade assessment, the method we propose is comparable to the traditional metallographic method in terms of accuracy; however, the process is simplified and the measurement speed is significantly improved.