urinary 1-hydroxypyrene is frequently used as a major metabolite and biological indicator of the overall exposure to polycyclic aromatic hydrocarbons. in this study, solid phase extraction was appropriately conditioned with regard to sample ph, sample concentration, loading flow rate, elution solvent, washing solvent, sample volume and sorbent mass. octadecyl silica cartridge (c18) was used as ...

A method for indicator selection is proposed in this paper. The method, which adopts the General Methodology and Design Research approach, consists of four steps: Problem Identification, Requirement Gathering, Indicator Extraction, and Evaluation. Rough Set approach also has been applied in the Indicator Extraction phase. This phase consists of 5 steps: Data selection, Data Preprocessing, Discr...

We report the use of a porous polytetrafluoroethylene capillary for the inline separation of liquid-liquid segmented flows, based on the selective wetting and permeation of the porous capillary walls by one of the liquids. Insertion of a narrow flow restriction at the capillary outlet allows the back pressure to be tuned for multiple liquid-liquid combinations and flow conditions. In this way, ...

In this paper we propose a limit characterization of the behaviour of classes of graphs with respect to their number of spanning trees. Let {Gn} be a sequence of graphs G0,G1,G2, . . . that belong to a particular class. We consider graphs of the form Kn −Gn that result from the complete graph Kn after removing a set of edges that span Gn. We study the spanning tree behaviour of the sequence {Kn...

Convergence to the Poisson distribution, for the number of occurrences of dependent events, can often be established by computing only first and second moments, but not higher ones. This remarkable result is due to Chen (1975). The method also provides an upper bound on the total variation distance to the Poisson distribution, and succeeds in cases where third and higher moments blow up. This p...

Pre-main sequence (PMS) stars evolve into main (MS) phase over a period of time. Interestingly, we found scarcity studies in existing literature that examines and attempts to better understand the PMS MS transition phase. The purpose present study is detect such rare stars, which named as 'Transition Phase' (TP) candidates - evolving from We identified 98 TP using photometric analysis sample 21...