Application of PCA and SIMCA statistical analysis of FT-IR spectra for the classification and identification of different slag types with environmental origin.

In the past, different slag materials were often used for landscaping and construction purposes or simply dumped. Nowadays German environmental laws strictly control the use of slags, but there is still a remaining part of 35% which is uncontrolled dumped in landfills. Since some slags have high heavy metal contents and different slag types have typical chemical and physical properties that will influence the risk potential and other characteristics of the deposits, an identification of the slag types is needed. We developed a FT-IR-based statistical method to identify different slags classes. Slags samples were collected at different sites throughout various cities within the industrial Ruhr area. Then, spectra of 35 samples from four different slags classes, ladle furnace (LF), blast furnace (BF), oxygen furnace steel (OF), and zinc furnace slags (ZF), were determined in the mid-infrared region (4000-400 cm(-1)). The spectra data sets were subject to statistical classification methods for the separation of separate spectral data of different slag classes. Principal component analysis (PCA) models for each slag class were developed and further used for soft independent modeling of class analogy (SIMCA). Precise classification of slag samples into four different slag classes were achieved using two different SIMCA models stepwise. At first, SIMCA 1 was used for classification of ZF as well as OF slags over the total spectral range. If no correct classification was found, then the spectrum was analyzed with SIMCA 2 at reduced wavenumbers for the classification of LF as well as BF spectra. As a result, we provide a time- and cost-efficient method based on FT-IR spectroscopy for processing and identifying large numbers of environmental slag samples.

Echocardiography in the fetus--a systematic comparative analysis of standard cardiac views with 2D, 3D reconstructive and 3D real-time echocardiography.

PURPOSE: The aim of our study was to assess the feasibility and reliability of fetal three-dimensional reconstructive echocardiography using freehand technique (3DR) and 3D real-time echocardiography using matrix technology (RT-3D) in consecutive series of pregnancies and to compare the findings with the gold standard 2D ultrasound, as well as postnatal findings. MATERIALS AND METHODS: Fifty consecutive pregnant women (gestational age 19+3 to 37+0) including 10 fetuses with cardiac malformations were scanned prospectively with 2D, 3DR and RT-3D. 3D data sets were evaluated by a blinded independent examiner. The visualization rates for standard cardiac views and structures were determined and the quality and diagnostic accuracy of each modality were calculated. RESULTS: In RT-3D, the visualization rate of fetal cardiac views was equivalent to 2D, but was significantly lower for 3DR (4cv: 2D 98%, RT-3D 100%, 3DR 96% RVOT: 2D 96%, RT-3D 98%, 3DR 84%). Short-axis views or views of the complete aortic or ductal arch were more readily identified in RT-3D than in 2D (2D 70%, RT-3D 82%). 3DR was more susceptible than RT-3D to artifacts during acquisition and post-processing. The sensitivity and overall accuracy were significantly higher for 2D and RT-3D than for 3DR, when prenatal data was compared with postnatal findings. CONCLUSION: 3D freehand reconstruction has significantly lower visualization rates and overall accuracy compared to 2D and RT-3D. RT-3D echo is a feasible and reliable method for imaging the fetal heart. Offering the opportunity of data post-processing and evaluation, RT-3D is a promising method for improving the accuracy of sonographic analysis of fetal cardiac morphology and function.

Volumetry of fetal hearts using 3D real-time matrix echocardiography - in vitro validation experiments and 3D echocardiographic studies in fetuses.

PURPOSE: The aim of this study was to assess the feasibility, accuracy and reliability of 3D real-time echocardiography for fetal heart volumetry. MATERIALS AND METHODS: Fifty unselected and consecutive fetuses, including 14 with cardiac malformations, were scanned prospectively using real-time 3D matrix technology and 2D echocardiography to determine ventricular volumes. Small phantoms as well as modified balloons (0.5 - 20 ml) were used to assess the validity of 2D and 3D distance, area and volume calculations and to study potential sources of error during data acquisition and analysis. The data was evaluated by two blinded observers. RESULTS: In vitro, real-time 3D and 2D underestimated the actual volumes by -5.49 % (3D) and -6.86 % (2D). The intraobserver and interobserver variability were excellent. In vivo, real-time 3D was superior to 2D with regard to intraobserver and interobserver variability (mean coefficient of variation 8.28 % (3D) versus 13.96 % (2D), and mean intraclass correlation coefficient 0.997 (3D) versus 0.885 (2D) for left ventricular volumes). Similar to in vitro, in vivo 2D volumes were calculated smaller than 3D volumes (mean difference -0.39 to -0.94 ml). The ventricular volumes and stroke volumes increased exponentially with gestation. Secondary to poor imaging windows in advanced gestation or inadequate delineation of endocardial borders in small hearts at less than 19 weeks, 3D data could not be analyzed sufficiently in 6 / 50 fetuses. CONCLUSION: Real-time 3D using a matrix transducer is a feasible, reliable and valid method for volume determination in the fetus beyond 19 weeks of gestation. If compared to 2D, real-time 3D echocardiography provides improved accuracy of cardiac volumetry, decreases intraobserver and interobserver variability and is a promising tool for the accurate assessment of cardiac size and function.

Differentiating with fluorescence spectroscopy the sources of dissolved organic matter in soils subjected to drying

The relative fluorescence, normalised on dissolved organic carbon (DOC), and a humification index, based on the location of the fluorescence emission spectra, were used to investigate the possible sources of the increase in dissolved organic matter (DOM) when a soil is dried. From these 2 parameters it could be seen that air drying resulted in a minor increase of more humified material in DOM while the effect of oven drying was mainly due to cell lysis.