Practical Analytical Procedure Research Articles

New Reference Materials, Analytical Procedures and Data Reduction Strategies for Sr Isotope Measurements in Geological Materials by LA‐MC‐ICP‐MS

Laser ablation multi‐collector mass spectrometry (LA‐MC‐ICP‐MS) has emerged as the technique of choice for in situ measurements of Sr isotopes in geological minerals. However, the method poses analytical challenges and there is no widely adopted standardised approach to collecting these data or correcting the numerous potential isobaric inferences. Here, we outline practical analytical procedures and data reduction strategies to help establish a consistent framework for collecting and correcting Sr isotope measurements in geological materials by LA‐MC‐ICP‐MS. We characterise a new set of plagioclase reference materials, which are available for distribution to the community, and present a new data reduction scheme for the Iolite software package to correct isobaric interferences for different materials and analytical conditions. Our tests show that a combination of Kr‐baseline subtraction, Rb‐peak‐stripping using βRb derived from a bracketing glass reference material, and a CaCa or CaAr correction for plagioclase and CaCa or CaAr + REE2+ correction for rock glasses, yields the most accurate and precise 87Sr/86Sr measurements for these materials. Using the analytical and correction procedures outlined herein, spot analyses using a beam diameter of 100 μm or rastering with a 50–65 μm diameter beam can readily achieve < 100 ppm 2SE repeatability ("internal") precision for 87Sr/86Sr measurements for materials with < 1000 μg g‐1 Sr.

Performance Audit in Construction Organisations: Relevant Criteria and Analytical Procedures

Performance audit is becoming increasingly ubiquitous in commercial and business spheres internationally. Due to itsimportant role in promoting efficient organisational and administrative practices, performance audit is becoming asubject more rigorously analised in the academic sphere.This study seeks to develop and test analytical tools of performance audit in Russian construction organisations. Weplace emphasis on the industry-specific dimensions of information disclosure. We intend to offer a solution to severalcrucial challenges in the field, which will allow for the development of a comprehensive method to implement analyticalprocedures. This is done with a view towards obtaining and collating sufficient and adequate audit evidence to helpachieve business goals.In order to devise a consistent methodology, first, a link is highlighted between construction industry constraintsand performance audit criteria. Second, an algorithm is developed to carry out comparative integrated estimation ofperformance audit criteria in order to shortlist relevant indicators. Third, the algorithm is tested using financial reportingof selected construction companies, which makes it possible to build a consistent system of performance audit criteriaand identify a reliable set of controlled parameters.A profile of practical analytical procedures, performance audit criteria and measurement indicators is formed throughfinancial and performance audit and imbedded statistical methods. Implementing this approach will be seen to closesome information gaps commonly found in the reporting data of construction industry, as it links the subject area ofperformance audit and the objective criteria of effectiveness, efficiency and economy.The findings are presented with reference to existing statistical surveys on construction industry constraints. Whilerecent studies provide a broader picture across construction industry, they do not address its regional aspects. Assuch, within this study we have carried out estimates of performance indicators for construction companies operatingin the Novosibirsk region. The estimates are based on the information available through Professional Market andCompany Analysis System. As a result, a system of performance audit criteria is identified in relation to the dimensionsof effectiveness, efficiency and economy and a framework of controlled parameters is shaped. The level of disclosureconcerning these parameters presented in a company’s reporting is supposed to determine the decisions of stakeholdersand potential investors.In consideration of further research, this study highlights that it is necessary to identify and validate performance criteriain view of the fact that only few construction companies are profitable. The mix of qualitative and quantitative analyticalprocedures demonstrated herein is an effective approach to address the challenges of information integrity assessment.We consider that the most promising aspect of this study is the analysis of how the quality and amount of informationdisclosed in the reporting of construction companies affects their public image and business activities. This can be seento have widespread industry and academic applications. Additionally, our approach represents a suitable framework forpossible adaptation towards not only other industries, but also further development of the methodological approachitself

Exact method for the stability analysis of time delayed linear‐time invariant fractional‐order systems

In this study, a practical analytical procedure is introduced for determining the stability robustness map of a general class of linear-time invariant fractional-order systems with single and multiple commensurate delays of retarded type, against delay uncertainties. The complexity arises due to the exponential type transcendental terms and fractional order in their characteristic equation (CE). It is shown that this procedure analytically reveals all possible stability regions exclusively in the parametric space of the time delay. Using the presented method in this study, first, the authors will eliminate the transcendental terms of exponential type from the CE and then, they can determine all the locations where roots pass through the imaginary axis. By definition of root tendency on the boundary of each interval, the number of unstable roots in each region is calculated. Finally, the concept of stability is expressed in the intervals of delay values. The effectiveness of the proposed method results is illustrated via six numerical examples and to gain a better understanding of the problem, the root-locus curve of these systems has been depicted as a function of delay parameter changes.

Processes of Reflectivity

The aim of this article is to suggest a useful approach demonstrating the focal role of processes of reflectivity in qualitative research. In particular, we distinguish between levels of analysis and analytical procedures for generating and organizing the interpretation of data and meanings in knowledge construction. We argue that reflective processes simultaneously involve both a state of mind and an active engagement. Within this context, reflective processes may refer to deliberate awareness involving both a contemplative stance (state of mind) and intentional activity aimed at recognizing differentness and generating knowledge (active engagement). Specifically, we identify four levels of reflection: observation, informants’ accounts, text deliberation, and contextualization and reconstruction. Simultaneously, we suggest several practical analytical procedures of reflectivity, which emanate from a dialectical line of thinking, including figure and ground, pre-existing expectations, apparent contradictions and opposites, and turning points (epiphanies). The dialectical approach to qualitative inquiry presented here maintains that discrepancies and opposites found at one level of analysis may be reconciled at a higher level of conceptual integration. During this process, the researcher becomes aware of the emergence of new knowledge by being attuned to a sense of differentness. We demonstrate the application of this model utilizing a concrete example taken from a research project evaluating a rehabilitation program for imprisoned male batterers.

Computerized sequence-based predictive methods: their use in the conformational characterization of proteins and in the analysis of their homologies a practical case employing lysozyme and α-lactalbumin

1 ~.5 experimentally deduced internal constraints.'' Furthermore, their use is restricted to highly specialized teams with a high level of physicochemical and mathematical training and who have at their disposal large computer facilities. However, for most initial studies the use of traditional and less sophisticated methods for the prediction of the secondary structure or the polar/apolar character along the protein sequence, 4'6-9 is highly informative. The application of these methods is usually simple, either being used manually or by computer-assisted approaches. Here we shall examine the reliability and accuracy of several simple predictive methods by applying them to the conformational analysis of a very well-known protein, chicken lysozyme. The limitations and the precautions that must be taken in the application of these methods will be stressed. Moreover, several simple computer programmes for the application of those predictive methods and for the semi-quantitative analysis of structural homologies among proteins will be discussed. A practical demonstration of these abilities will be made by comparing lysozyme and a-lactalbumin, two proteins considered as 'text-book' examples of homology. We present here a review of those methods which may also be used as a practical class for students of biochemistry and molecular biology since it requires discussion and work on different basic aspects of protein chemistry. Thus, the relationships between sequence-conformation and function is stressed. Moreover, important concepts such as protein differentiation, conservative substitutions, differential evolution of protein segments at the sequence and conformational level, and intronexon location and function, amongst others, are also discussed. The work was carried out in collaboration with a student (MF) in the last year of her degree in biochemistry. Background From the 1970s many empirical methods for the prediction of conformational traits of a protein from its amino acid sequence were developed (see ref 6-9 for reviews). These methods can be classified into two groups: those based on probabilistic studies and those based on a physicochemical approach. Most of these methods start from the same initial observation: each of the twenty usual amino acid residues in a protein has a particular potential to participate in different secondary structures (eg ahelix, 6-strand, reverse turn, random coil) or in buried or exposed stretches of it. Quantitative scales were deduced from statistical analysis of the structures of a large., mngr°up of proteins of known three-dimensional conformanon ' (probabilistic method) or from the quantification, using different techniques, of the polar/apolar character of each residue and its tendency to become exposed or buried lz (physicochemical method). To start the analysis, using probabilistic methods, an analytical window including a small number of residues (three to seven) is usually selected. The average (or positional, in certain cases) probability of the participation of this group of residues in a given secondary structure is calculated, and a probability profile for this conformational trait is elaborated by moving the window along the sequence of the protein.l°'13-15The regions of the protein which present an averaged probability above a neutral (or threshold) value for a particular trait are predicted to possess this trait. When one region has positive probabilities for more than one conformation trait, qualitative 1° or mathematical discriminant rules s'1°'16 are given to select the most probable. The physicochemical-based methods follow a similar practical analytical procedure, with a moving window to elaborate the 'hydropathy profile' and a given threshold to distinguish the polar/apolar characters for a given residue or protein stretch. 17-19 This profile is directly related to the overall (secondary and tertiary) folding of the protein. Some of these physicochemical methods also try to predict definite secondary structures through the observation of repeated polar and nonpolar patterns of residues (eg 1-2-5 or 1-4-5 for a-helix and alternate polar/non-polar for 13-strand) along the sequence. 12,~)-22

Nebulization with Nitrogen versus Argon in the DCP

The consequences of using N2 as a nebulizer gas during operation of a direct current plasma were evaluated with respect to its utility as a practical analytical procedure. Performance of the N2 system vs. that of an all-Ar plasma was compared on the basis of background plasma emission, atomization efficiency, detection limits, sensitivity, plasma electron density, and immunity from the easily ionized matrix element interference effect. Observations with regard to the mechanism of the EIE effect were also made. It was concluded in many cases that the use of N2 as a nebulizer gas does not significantly degrade analytical performance. An exception to this conclusion was the finding that refractory samples did not atomize as efficiently in the N2 plasma system.

Identification of Phencyclidine and Its Analogues at Low Concentrations in Urine by Selected Ion Monitoring

This paper presents retention behavior and mass spectra of eluting peaks for twelve phenyl and thienyl analogues of phencyclidine (PCP) as well as PCP itself. An on-column decomposition product common to all thienyl analogues is described. Finally, a practical analytical procedure is given for the detection and identification of these compounds in low (under 5 ng/mL) concentrations in urine.