Search results for "LIMIT"
showing 10 items of 2826 documents
Mediterranean diet and adiposity in children and adolescents: A systematic review
2021
Our aim was to summarize, through a systematic review, the current evidence from dietary intervention and observational studies on the impact of adherence to the Mediterranean diet on adiposity markers and obesity in children and adolescents. We searched Medline up to June 1, 2021 for the identification of intervention and observational studies meeting the inclusion criteria, following the PRISMA statement. We included 55 articles: 8 intervention studies and 47 observational studies. Three trials report a beneficial effect of the dietary intervention, whereas two did not, and three did not compare with a control. All observational studies were cross-sectional, and only five studies also inc…
Physical Activity Among Children With Congenital Heart Defects in Germany: A Nationwide Survey
2020
Objective: In children with congenital heart defects (CHD), a sedentary lifestyle should be avoided and usually WHO recommendations on physical activity (PA) are supposed to be followed. In order to obtain representative data of the actual amount of PA (and potential influencing factors) in children with CHD we performed a nationwide online survey.Methods: All patients aged 6–17 years registered in the German National Register for CHD were contacted by email and asked to participate in the survey using the comprehensive questionnaire of the “Motorik-Modul” from the German Health Interview and Examination Survey for Children and Adolescents (KiGGS), thus allowing the comparison with a repres…
Analysis of perfluorinated compounds in sewage sludge by pressurized solvent extraction followed by liquid chromatography–mass spectrometry
2011
Perfluorinated compounds (PFCs) are widely used in everyday life and one of the main recipients of these compounds is waste water treatment plants (WWTPs). Due to the structure and physicochemical properties of PFCs, these compounds could be redistributed from influent water to sludge. This work reports a new validated protocol for the analysis of 13 perfluorinated acids, 4 perfluorosulfonates and the perfluorooctanesulfonamide. The present work has been focused to develop a sensitive and robust method for the analysis of 18 PFCs in sewage sludge, based on pressurized solvent extraction (PSE) followed by solid phase extraction (SPE) clean-up, analytes separation by liquid chromatography and…
Modelling anaerobic biomass growth kinetics with a substrate threshold concentration.
2004
Abstract Many bacteria have been observed to stop growing below a certain substrate threshold concentration. In this study, a modification of the Monod kinetics expression has been proposed to take into account this substrate threshold concentration observed in bacterial growth. Besides the threshold concentration no additional parameters have been added to the kinetic expression and so, only the substrate threshold concentration and the half-saturation constant have to be estimated for model calibration purposes. Furthermore, for parameter estimation purposes, practical identifiability of this new function has been studied and the results have been satisfactory. The new model has been appl…
Self-normalized and randomly centered spectral estimates
1996
We review some limit theory for the periodogram and for integrated versions of it and explain the use of random normalizing and centering techniques.
Gas chromatography/mass spectrometry of catechol estrogens
1992
Abstract Catecholestrogens (CCEs), namely 2- or 4-hydroxyestradiol and hydroxyestrone, are highly polar, reactive, and extremely labile estrogen metabolites in many experimental conditions. For these reasons, indirect assay methods mainly have been used. Some experimental evidence suggests that CCEs are synthesized and biologically active mostly in target cells. At this level, unfortunately, the indirect assays cannot be used. We present a method of gas Chromatographic/mass spectral (GC/MS) analysis for the identification of individual CCEs; the major fragmentation ions of authentic estrogen standards as trimethylsilylether derivatives, and the MS patterns of the major CCEs, namely, 2-hydro…
Determination of phenobarbital in plasma by micellar liquid chromatography
2000
A new liquid chromatographic procedure for the determination of phenobarbital in plasma samples is described. The proposed system uses a Spherisorb octadecyl-silane ODS-2 C(18) analytical column, a guard column of similar characteristics, and a 0.03 M CTAB-3% 1-propanol at pH 7 mobile phase. The UV detector was set at 250 nm. Butabarbital was used as internal standard. Sample preparation only required the addition to the plasma samples of a 0.1 M SDS solution at pH 3 and centrifugation before injection into the chromatographic system. The limit of detection was 0.83 microg/mL of phenobarbital in plasma samples. The coefficients of variation were lower than 7. 5%.
A multicommutated flow system for determination of bismuth in milk shakes by hydride generation atomic fluorescence spectrometry incorporating on-lin…
2004
Abstract A highly sensitive method was developed for determination of bismuth in milk shakes by multicommutation hydride generation atomic fluorescence spectrometry (HG-AFS) based on off-line sonication for 10 min with aqua regia 8% (v/v) and on-line waste treatment. The instrumentation and chemistry variables were studied in order to provide the best performance. The limit of detection in the original samples, established for a probability level of 99.6% (k = 3), was 1.67 ng/g Bi. The method provides a fast alternative in control analysis with a sampling throughput of 72 h as compared with 31 h obtained by the classical continuous measurement. Additionally, multicommutation reduces waste g…
Determination of amobarbital and secobarbital in plasma samples using micellar liquid chromatography
2000
A new liquid chromatographic procedure for the determination of amobarbital and secobarbital in plasma samples is proposed. The method uses a Spherisorb octadecylsilane ODS-2 C18 analytical column, a guard column of similar characteristics and 0.04 M CTAB solution buffered at pH 7.5 containing 3% 1-propanol as micellar mobile phase. The UV detection was carried out at 250 nm. Butabarbital was used as internal standard. Plasma samples preparation only required adequate dilution with the mobile phase before injection into the chromatographic system. The limits of detection were 0.2 and 0.4 mg/L for amobarbital and secobarbital, respectively. The proposed method allows the determination of amo…
Comparison of Methods and Kits for Colorimetric Determination of Residual Chlorine in Water
1997
Abstract The use of 3,3',5,5'-tetramethylbenzidine (TMB) for residual chlorine determination in water offers 2 possibilities, one at pH 1-2 and absorbance measurement at 450 nm and another at pH 3.8-5.8 and measurement at 650 nm. The reaction of chlorine with TMB reaches its maximum sensitivity at pH 1-2. The detection limit is 2 ng/mL. A calibrated scale for colorimetric determination of residual chlorine in water with 3,3',5,5'-tetramethylbenzidine (TMB), prepared with tropaeolin O (C.I. 14270), is described. This scale is stable for several months and can be useful in replacing the conventional and much less stable scale prepared from standard solutions of oxochlorate (I). Kits for deter…