Search results for "Precision"
showing 10 items of 448 documents
Evidence for eta(c) -> gamma gamma and measurement of J/psi -> 3 gamma
2013
The decay of J/psi to three photons is studied using psi (3686) -> pi(+) pi(-) J/psi in a sample of 1.0641 X 10(8) psi (3686) events collected with the BESIII detector. Evidence of the direct decay of eta(c) to two photons, eta(c) -> gamma gamma, is reported, and the product branching fraction is determined to be B(J/psi -> gamma eta(c,) eta(c) -> gamma gamma = (4.5 +/- 1.2 +/- 0.6) X 10(-6), where the first error is statistical and the second is systematic. The branching fraction for J/psi -> 3 gamma is measured to be (11.3 +/- 1.8 +/- 2.0) X 10(-6) with improved precision.
A decision support system based on multisensor data fusion for sustainable greenhouse management
2018
The sustainable exploitation of natural resources is nowadays an important challenge for governments and institutions, considering the expected increase of the world population. In order to respond to this emergent criticality, the principles of green economy have been introduced in the European policy discussion to achieve a good compromise between the sustainability and the profitability of productions by increasing the efficiency of farming operations. Such approach poses some technical and financial challenges for small-sized enterprises because they generally do not possess adequate internal knowledge, nor they can acquire external expertise due to their budget restrictions. Decision S…
New optical paper sensor for in situ measurement of hydrogen sulphide in waters and atmospheres
2016
A novel and low-cost colorimetric sensor for the determination of hydrogen sulphide in environmental samples has been developed. This sensor is based on the immobilization of the reagent N,N-Dimethyl-p-phenylenediamine and FeCl3 in paper support, in which the H2S is adsorbed in order to give rise to the formation of methylene blue as reaction product. The sensor has been applied to determine H2S in water and air samples. Two different sampling systems for H2S caption from the air have been assayed: active and passive sampling. The analytical properties of the different systems have been obtained and compared. The analytical signals, corresponding to the methylene blue, have been obtained me…
A new flow cell design for chemiluminiscence analysis.
2001
The present study proposes a new flow cell called a bundle cell for chemiluminescence analysis. The results obtained were compared with those achieved by manual and automated batch procedures and flow manifolds with different cells: an common quartz flow cell, a helix cell and the most used spiral cell. Figures of merit such as limit of detection, sensitivity, accuracy and precision for the Cr(III) determination were established with light emission produced by catalysed Cr(III) luminol oxidation by hydrogen peroxide in a basic aqueous solution. An improvement in sensitivity about 50% as compared with the spiral cell and even larger with respect to the other flow cells tested was observed. T…
Addition of thiourea and hydrochloric acid: Accurate nanogram level analysis of mercury in humic-rich natural waters by inductively coupled plasma ma…
2020
Abstract An analytical method was developed for the direct determination of total mercury in natural waters at low ng L−1 level by inductively coupled plasma mass spectrometry (ICP-MS). The presented method overcomes previously observed problems relating to poor spike recoveries by adding 0.12% thiourea in addition to 3% HCl to all samples and standards. The sample preparation is fast and easy to perform by the developed method since it requires only the addition of HCl and thiourea to the water samples. A very low instrument detection limit (0.4 ng L−1) was obtained without time-consuming preconcentration procedures. The accuracy and precision of the developed method were found excellent b…
Copper, iron and zinc determinations in human milk using FAAS with microwave digestion
2000
Abstract A method for determining copper, iron and zinc in human milk was optimized and validated. It includes microwave mineralization of the sample and measuring the elements by flame atomic absorption spectroscopy (FAAS). Only 2 ml of milk is needed, and the method is free of matrix interferences. The values obtained for the detection limits (0.07; 0.07; 0.11 μg/ml milk, for copper, iron and zinc) precision of the method, intra-assay (2.9; 5.2; 6.1%RSD for copper, iron and zinc) and accuracy, evaluated using recovery assays (98.8; 100.4; 95.9% for copper, iron and zinc) show that the method is useful for the purpose mentioned. Moreover, the method is rapid and simple, and the determinati…
Determination of methamphetamine in urine samples with sodium 1,2-naphthoquinone-4-sulphonate
1994
Optimal conditions have been studied for the determination of methamphetamine in urine samples by an extractive-spectrophotometric method with sodium 1,2-naphthoquinone-4-sulphonate (NQS) as reagent. These conditions are: NaHCO3 pH 10, NQS 6.3 × 10−3 mol/l and heating for 5 min at 45°C. The accuracy and precision of the method were tested. The detection limits were 0.2 mg/l in the standard and 0.9 mg/l when 5 ml of urine sample were taken. The standard deviation of blank urine was evaluated from 12 different samples. The relative errors found in the determination of methamphetamine in urine were lower than 10% if the methamphetamine-amphetamine ratio was higher than 4.
Influence of the differentiation system on the analytical parameters for the spectrophotometric determination of clonazepam in urine
1991
Abstract Electronic and mathematical differentiation of the ultraviolet visible spectra were compared from the study of the analytical parameters of the direct determination of clonazepam in urine samples. Third-order derivative spectra were used. The mathematical differentiation provides higher sensitivity, a lower limit of detection, and better accuracy and precision than the electronic one. The use of a diode array instrument provides lower sensitivity than that found using a conventional spectrometer; however, the limit of detection obtained in both cases is of the same order.
FI automatic method for the determination of copper(II) based on coproporphyrin I-Cu(II)/TCPO/H(2)O(2) chemiluminescence reaction for the screening o…
2004
Abstract In this paper, an automatic method for the screening of water samples containing Cu(II) was proposed, based on peryoxalate chemiluminescence reaction using coproporphyrin I as fluorophor compound to provide selectivity and a simple flow injection (FI) chemiluminescence detector (CLD). FI system conditions were chosen in order to distinguish samples over or under legislation limit established (50 μg l−1) with high reliability. The detection limit found was 9 μg l−1 and the linear dynamic range was 15–125 μg l−1 of Cu(II). Repeatibility and reproducibility studies gave good precision and accuracy with recovery near 100%. Under these conditions, the method resulted selective and only …
ETP/GDOP Behavior Study for N-Sensors Arrays ina Multilateration Radar System
2009
In this paper, we evaluated the ETP (Expected Theoretical Precision) and GDOP (Geometric Dilution Of Precision) enhancement related to the number of sensors in a Multilateration radar system. An introduction about the principles of the Multilateration radar system basis operation is described, then, the formulation for evaluation the ETP/GDOP of the 3D positioning is shown. We observed that the ETP and GDOP enhance with the increase of the number of sensors. A substantial improvement was obtained until nine sensors but, for more sensors that improvement is reduced. Results for a 75km×75km area are shown, including LAM (Local Area Multilateration) and WAM (Wide Area Multilateration) settings…