The thermoluminescence response of Ge-doped optical fibre subjected to photon irradiation

A radiation dosimeter based on Ge-doped silica fibre is described. Parameters concerning thermoluminescence (TL) induced by ⁶⁰Co irradiation are investigated, including activation energies, frequency factors, and reproducibility with dose and fading. It is concluded that Ge-doped silica fibres provide a good basis for medical radiation dosimetry at therapy levels. In particular, doses are reproducible to within 3%, the fibres are reusable and show linearity of dose versus TL output over the approximate range of dose 1 Gy to in excess of 100 Gy. At room temperatures, fading within the first 30 d following irradiation has been found to be of the order of 7%.     

The effect of humidity on the accuracy of measurement of an electret radon dosimeter

Test has been conducted for the response of electret radon dosimeters with varying levels of humidity. At a constant value of radon concentration, measured values have been found to increase linearly with increasing humidity, from 30% RH up to a value of 85% RH. On this basis we argue for the establishment of a humidity-dependent calibration factor.     

Highly Sensitive LC Method with Automated Co-Sense System and Fluorescence Detection for Determination of Sertraline in Human Plasma

A highly sensitive LC method with column-switching “Co-sense” system and fluorescence detection has been proposed for trace determination of sertraline in human plasma. A simple pre-column derivatization procedure with 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole reagent was employed. Fluxetine was used as an internal standard. Under the optimum chromatographic conditions, a linear relationship with good correlation coefficient (r = 0.9997) was found between the peak area ratio and sertraline concentration in the range of 5–5,000 ng mL^?1. The limit of detection and limit of quantitation were 1.41 and 4.28 ng mL^?1, respectively. The intra- and inter-assay precisions were satisfactory; the relative standard deviations did not exceed 5.63%. The accuracy of the method was proved; the recovery of sertraline from the spiked human plasma was 99.76–102.62 ± 2.19–5.63%. The proposed method had high throughput as the analysis involved simple sample pre-treatment procedure and short run-time (~12 min). The results demonstrated that the method would have a great value if applied in bioavailability and pharmacokinetic studies for sertraline.     

Some clarifications on the DEA clustering approach

This paper clarifies the role of alternative optimal solutions in the clustering of multidimensional observations using data envelopment analysis (DEA). The paper shows that alternative optimal solutions corresponding to several units produce different groups with different sizes and different decision making units (DMUs) at each class. This implies that a specific DMU may be grouped into different clusters when the corresponding DEA model has multiple optimal solutions.     

Solvent Free One-Pot Synthesis of 2-thioxo-1,3-thiazinane-4-one Derivatives

Abstract

An efficient one-pot synthesis of 2-thioxo-1,3-thiazinane-4-one derivatives through the reaction of primary amines and carbon disulfide in the presence of acryloyl chloride is described. This reaction is carried out under solvent-free condition and without any catalyst at room temperature within 15 min. The structures of products were deduced from their elemental analysis and IR, ¹H NMR, and ¹³C NMR spectroscopy, and mass spectrometric data.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional figures.]     

On the boundedness of the SORM DEA models with negative data

Emrouznejad et al. (2010) proposed a Semi-Oriented Radial Measure (SORM) model for assessing the efficiency of Decision Making Units (DMUs) by Data Envelopment Analysis (DEA) with negative data. This paper provides a necessary and sufficient condition for boundedness of the input and output oriented SORM models.     

A comparison of two nuclear analytical techniques for determination of 210Pb-specific activity in solid environmental samples

Two nuclear analytical techniques for determination of ²¹⁰Pb-specific activity in solid environmental samples have been validated and compared. The first technique depends on determination of ²¹⁰Pb via its alpha emitting daughter ²¹⁰Po using alpha-particle spectrometry, while the second technique is based on direct determination of ²¹⁰Pb by measuring its activity at the 46-keV gamma line by low-energy gamma-ray spectrometry. Detection limits, repeatability, reproducibility, and surrogate recovery were the main validation parameters. Measurement uncertainties were estimated and compared for both techniques. Results of this study have shown that the expected activity of ²¹⁰Pb in the environmental samples and the required measurement uncertainty are the main factors influencing a selection of the appropriate method for the application.     

Split-luciferase complementary assay: applications,recent developments,and future perspectives

Bioluminescent systems are considered as potent reporter systems for bioanalysis since they have specific characteristics, such as relatively high quantum yields and photon emission over a wide range of colors from green to red. Biochemical events are mostly accomplished through large protein machines. These molecular complexes are built from a few to many proteins organized through their interactions. These protein–protein interactions are vital to facilitate the biological activity of cells. The split-luciferase complementation assay makes the study of two or more interacting proteins possible. In this technique, each of the two domains of luciferase is attached to each partner of two interacting proteins. On interaction of those proteins, luciferase fragments are placed close to each other and form a complemented luciferase, which produces a luminescent signal. Split luciferase is an effective tool for assaying biochemical metabolites, where a domain or an intact protein is inserted into an internally fragmented luciferase, resulting in ligand binding, which causes a change in the emitted signals. We review the various applications of this novel luminescent biosensor in studying protein–protein interactions and assaying metabolites involved in analytical biochemistry, cell communication and cell signaling, molecular biology, and the fate of the whole cell, and show that luciferase-based biosensors are powerful tools that can be applied for diagnostic and therapeutic purposes.     

Kerr effect in quantum dot structure

A three-level ladder QD system is used to study Kerr effect in QD structures. Inhomogenous broadening is included where it is shown to be critical in calculating Kerr effect in QDs. Signal detuning is shown to control Kerr dispersion.     

New Colorimetric Methods for the Determination of Indapamide and its Formulations

 Two simple and sensitive methods for the determination of indapamide in pure and in dosage forms are developed. These methods are based on the oxidation of indapamide with iron(III) in acidic medium. The liberated iron(II) reacts with 1,10-phenanthroline (Method A) and the ferroin complex is colorimetrically measured at λ_max 509 nm against reagent blank. Method B is based on the reduction of Fe(III) by the drug. Iron(II) forms a colored complex (λ_max 522 nm) with 2,2′-bipyridyl. Optimization of the experimental conditions is described. Beer’s law is obeyed in the concentration range 1.0–12 μg ml⁻¹ and 4.0–18 μ g ml⁻¹ for A and B, respectively. The apparent molar absorptivity and Sandell sensitivity for method A is 3 × 10⁴ L mol⁻¹ cm⁻¹ and 0.0188 μ g cm⁻², while for method B is 2.3 × 10⁴ L mol⁻¹ cm⁻¹ and 0.0159 μg cm⁻². The detection and quantification limits are calculated. The developed methods are applied successfully for the determination of indapamide in pure and in tablet form without interference from common excepients. Received November 10, 2000. Revision April 6, 2001.