Analytical Principles Research Articles

Group form reconsidered: Physicality and humanity of collective spaces

In 1964, Japanese architect Fumihiko Maki presented the need for investigation in housing collective form. The need was explained through his sensitivity towards the dynamic change of society and simultaneous inadequacy of architectural static and fragmented respond. This paper presents the contemporary view on the theory of collective form and its investigation into why and how the group of buildings stands together. It brings forward the need for renewed architectural focus on group form, one of Maki's collective form types, and the social and human reasoning of design decisions. The theory of linkages in group form is related to more recent sociospatial analytical theories and interpreted as an analytical tool for understanding housing morphologies, configurations, and its social capacity of group form. It is proposed that the morphological and configurational approach can be used in combination for reading and understanding the historical and contemporary housing ensembles and their relation to an urban whole. The aim of the theoretical research is the identification of the analytical framework and design principles of group form based on architectural and configurational elements and their relations, as socially and culturally relevant.

A Novel Dual-Rotor Bidirectional Flux-Modulation PM Generator for Stand-Alone DC Power Supply

A novel bidirectional flux-modulation permanent magnet (BFMPM) machine for stand-alone dc wind power generation is proposed in this paper. The key is to control the inner rotor position with a small servo motor, and with the bidirectional flux-modulation effect, the resultant induced voltages in two sets of stator windings can be adjusted accordingly. Consequently, in a wide wind speed range, the various-speed constant-amplitude-voltage operation is realized. The novel structure has two major merits. First, it has high reliability without the maintenance problems caused by mechanical gearboxes, slip ring assembly, and brushes. Second, the proposed system requires a low-cost uncontrolled diode rectifier, which enhances the reliability and reduces the cost of the system. The analytical model and operation principle of the BFMPM machine are illustrated and the simulation results using a finite-element method is presented. A prototype is optimized and fabricated. The experimental results agree well with the simulation results and verify the correctness of the analytical model and the effectiveness of the proposed structure. Therefore, the novel structure offers a potential solution to provide a stable dc power for the standalone condition, such as remote area and offshore island.

Robust Inter-Vehicle Distance Estimation Method Based on Monocular Vision

Advanced driver assistance systems (ADAS) based on monocular vision are rapidly becoming a popular research subject. In ADAS, inter-vehicle distance estimation from an in-car camera based on monocular vision is critical. At present, related methods based on a monocular vision for measuring the absolute distance of vehicles ahead experience accuracy problems in terms of the ranging result, which is low, and the deviation of the ranging result between different types of vehicles, which is large and easily affected by a change in the attitude angle. To improve the robustness of a distance estimation system, an improved method for estimating the distance of a monocular vision vehicle based on the detection and segmentation of the target vehicle is proposed in this paper to address the vehicle attitude angle problem. The angle regression model (ARN) is used to obtain the attitude angle information of the target vehicle. The dimension estimation network determines the actual dimensions of the target vehicle. Then, a 2D base vector geometric model is designed in accordance with the image analytic geometric principle to accurately recover the back area of the target vehicle. Lastly, area–distance modeling based on the principle of camera projection is performed to estimate distance. The experimental results on the real-world computer vision benchmark, KITTI, indicate that our approach achieves superior performance compared with other existing published methods for different types of vehicles (including front and sideway vehicles).

New Discoveries for User Acceptance of E-Learning Analytics Recommender Systems in Saudi Arabia

This article adopts e-learning analytics principles to provide a new model to explain the acceptance behaviour of recommender systems adoption with e-learning in the Saudi Arabian context and reflects the increasing focus of the Saudi Arabian Ministry of Education on delivering online educational services. This focus has come at the necessity to improve overall access to the education system, and higher education and has been driven with evidence of improving learning outcomes with electronic learning (e-learning) information and instructional technology with the use of e-learning analytics recommender systems. This review utilises the technology acceptance model as a theoretical framework to generate a set of interlocked hypotheses that go to explaining student behaviours towards technological acceptance and continued usage intention of recommender systems.

Applications of chemical imaging techniques in paleontology

Chemical imaging techniques, based on a combination of microscopy and spectroscopy, are designed to analyse the composition and spatial distribution of heterogeneous chemical complexes within a sample. Over the last few decades, it has become an increasingly popular tool for characterizing trace elements, isotopic information and organic biomarkers (molecular biosignatures) found in fossils. Here, we introduce the analytical principle of each technique and the interpretation of the chemical signals, followed by a review of the main applications of these techniques in paleontology. We also demonstrate that each technique is associated with pros and cons, and the current limitations and obstacles associated with the use of each specific technique should be taken into account before being applied to fossil samples. Finally, we propose that, due to the rapid advances in the available technology and overall trends towards more multi-disciplinary studies in paleontology, chemical imaging techniques can be expected to have broader applications in paleontology in the near future.

Counting and Sizing of Single Vesicles/Liposomes by Electrochemical Events

AbstractThe analysis of single entities in a liquid phase by electrochemical events has received much attention in recent years due to innovations and advances in exciting electrochemical methods as well as precise manufacturing techniques. Vesicles, as a special type of entity, play an important role in biological systems. However, the soft character and complex surface chemistry of vesicles present inherent challenges for single‐vesicle analysis. This minireview mainly focuses on the theory and recent progress of single‐vesicle/liposome analysis based on electrochemical events. Three different analytical principles, namely, pore/channel translocation, microelectrode impact and nanopipette collision, are reviewed and expatiated. Not only the capabilities for size determination, vesicle/liposome counting and the electroactive quantification of the contents within vesicles/liposomes but also the specificities of vesicle/liposome or entity‐pore/electrode interactions reflected in translocation or collision events are discussed in detail. Moreover, the advantages and disadvantages of each method of single‐vesicle analysis are discussed in this minireview.

TexTonic: Interactive visualization for exploration and discovery of very large text collections

TexTonic is a visual analytic system for interactive exploration of very large unstructured text collections. TexTonic visualizes hierarchical clusters of representative terms, snippets, and documents in a single, multi-scale spatial layout. Exploration is supported by interacting with the visualization and directly manipulating the terms in the visualization using semantic interactions. These semantic interactions steer the underlying analytic model by translating user interactions within the visualization to contextual updates to the supporting data model. The combination of semantic interactions and information visualization at multiple levels of the data hierarchy helps users manage information overload so that they can more effectively explore very large text collections. In this article, we describe TexTonic’s data processing and analytic pipeline, user interface and interaction design principles, and results of a user study conducted mid-development with experienced data analysts. We also discuss the implications TexTonic could have on visual exploration and discovery tasks.

Expert opinions on endocrine toxicity induced by new anticancer therapies: Precautions to be taken in performing and interpreting hormonal assays under immunotherapy

As well as tyrosine kinase and mTOR inhibitors, new anticancer therapies make use of antibodies targeting tyrosine kinase receptors or blocking anti-tumor immune response checkpoints. These are always monoclonal; in their international non-proprietary names, the origin is prefixed to “-mab”: e.g., mouse antibodies end in “o-mab”, chimeric antibodies in “xi-mab”, humanized antibodies in “zu-mab” and human antibodies in “u-mab”. When the analytic principle of the assay involves a murine monoclonal antibody and the therapeutic antibody contains a murine sequence, analytic interference is to be feared if the patient develops antibodies against the therapeutic antibody. The interfering heterophilic antibody may be a HAMA (anti-mouse), a HACA (anti-chimeric) or a HAHA (anti-humanized-antibody). In immunoassay for patients under immunotherapy, it is therefore recommended to check the type of therapeutic antibody: if it is liable to contain murine sequences, heterophilic antibodies should be screened for and neutralized.

Prática Intercultural da Liderança: Princípios e Desafios da Pesquisa Empírica

Practice-based studies are gaining importance in Management research, theoretically, epistemologically and methodologically. However, in the field of leadership as cross-cultural practice, methodological proposals and reflections for sustaining empirical research practice are still limited. The purpose of this article is to formulate and discuss a methodological and analytical framework to assist scholars in their practice of empirical research on leadership as cross-cultural practice. The presented framework articulates conceptual, methodological and analytical principles to guide the research of cross-cultural leadership practices. In addition, the article illustrates the use of the framework through an empirical study on leadership in international projects in the Rotary organization and discusses the main challenges in conducting this type of research. With this, the results of this research contribute to the development of empirical research with more refined reflexivity and with full consideration of the strength of culture in the cross-cultural practice of leadership in the contemporary world.

Computational Archival Science

The digitisation of archival materials and ingest of digitally born materials in digital archives has led to the possibilities of application of the big data analytical principles in the digital archives. The author explains the 5V characteristics of big data. He proceeds to define the concept of Computational Archival Science (CAS). Two CAS examples are given in order to illustrate the type of research that can be conducted in that area. Further, the author explains the prerequisites for engaging with CAS. Finally, suggestions on how archival institutions might get involved in CAS activities are given.

Visible-light-driven photoelectrochemical determination of Cu2+ based on CdS sensitized hydrogenated TiO2 nanorod arrays

A CdS sensitized hydrogenated TiO2 nanorod arrays (CdS@HTNRs) film was developed for the selective visible-light-driven photoelectrochemical (PEC) sensing of Cu2+ ion. The sensitive determination was based on extremely high PEC activity of the as-prepared CdS@HTNRs, i.e, the photocurrent density of the as-prepared CdS@HTNRs electrode could reach up to 10.1 mA cm−2, which was 33.7 times higher than that of the pure HTNRs film. Dramatic photocurrent quenching was observed upon immersion of the CdS@HTNRs electrode into Cu2+ solution. The analytical principle is based on significant quenching of photocurrent, i.e, the formation of CuS and subsequent CuxS (x = 1, 2) produced on the electrode surface under illumination reduces the absorption of light and boosts the electron-hole recombination, respectively. Due to the large photocurrent density of the as-prepared CdS@HTNRs and the high selectivity of chemical recognition reaction between CdS and Cu2+, the photocurrent quenching of CuxS, is proposed to be sensitive and selective in detecting Cu2+ ion. The linear detection range could be 0.8 nM to 82.0 μM with the detection limit of 0.3 nM via controlling recognition reaction time to be 7 min. The sensor was also successfully applied in the detecting Cu2+ ion in real samples such as tap water, lake water and urine.

Energy-Optimal Edge Content Cache and Dissemination: Designs for Practical Network Deployment

Cloud storage and computing, although it empowers ubiquitous and global information acquisition, analysis, and management, the latency performance and heavy traffic burdens at fronthaul/ hackhaul links have emerged as critical concerns due to the scalability issue, which consequently drives the development of edge content cache and dissemination. Despite ample research on latency and traffic load reduction, an effective design of edge content cache and dissemination from the perspective of energy efficiency is imperative. Noting the fact that wireless service demands are inherently unbalanced over geographic regions, a practical cell planning strategy of operators' basic interests should deploy base stations massively in hot spot areas and sparsely in rural areas. A mobile user is therefore able to acquire desired contents through multiple base stations in a hot spot, while performing autonomous content cache and dissemination with other mobile users in rural areas. Taking this practical constraint into consideration, this article offers energy-optimal edge content cache and dissemination designs for hot spot and rural areas. Exploiting Lyapunov optimization and optimum control theory, we demonstrate analytical foundations and principles of the proposed optimum designs. Engineering insights are also revealed through practical simulation investigations to extend the research frontier of energy-efficient edge content cache and dissemination.

Stanovení cukrů a celkových sacharidů v pivu

The concentration of total saccharides including polyols and sugars belongs to one of the main values of basic nutrition labelling information of food as well as beer. The article informs about the method of these compounds, describes its chemical and analytical principles, validation parameters and clearly explains how the method is applied in the beer analysis.

Generalized analytic solutions and response characteristics of magnetotelluric fields on anisotropic infinite faults

In order to understand directly and analyze accurately the detected magnetotelluric (MT) data on anisotropic infinite faults, two-dimensional partial differential equations of MT fields are used to establish a model of anisotropic infinite faults using the Fourier transform method. A multi-fault model is developed to expand the one-fault model. The transverse electric mode and transverse magnetic mode analytic solutions are derived using two-infinite-fault models. The infinite integral terms of the quasi-analytic solutions are discussed. The dual-fault model is computed using the finite element method to verify the correctness of the solutions. The MT responses of isotropic and anisotropic media are calculated to analyze the response functions by different anisotropic conductivity structures. The thickness and conductivity of the media, influencing MT responses, are discussed. The analytic principles are also given. The analysis results are significant to how MT responses are perceived and to the data interpretation of the complex anisotropic infinite faults.

Hollow fiber microextraction: a new hybrid microextraction technique for trace analysis.

A new hybrid microextraction technique (hollow fiber microextraction) is presented that uses the main concepts and advantages of the modern miniaturized devices used for trace analysis. This novel analytical approach uses devices made of polypropylene membranes (10.0 mm long and 0.6 mm internal diameter) in which convenient organic solvents are embedded that promote fast kinetics during the enrichment process, using the floating sampling technology concept. An innovative analytical cycle is also proposed by use of low-cost disposable devices during the microextraction stage together with a user-friendly ("single liquid desorption step") back-extraction stage in compliance with green analytical chemistry principles. To evaluate the performance of the proposed technique, 18 polycyclic aromatic hydrocarbons (PAHs) were used as model compounds and were monitored by gas chromatography coupled with mass spectrometry. Under optimized experimental conditions, assays performed on 25 mL aqueous samples spiked with the PAHs at trace level yielded average recoveries between (14.5 ± 8.2)% (dibenzo[a,h]anthracene) and (90.4 ± 8.4)% (benzo[a]anthracene) with use of a device in which n-nonane had been embedded. Low detection limits were also achieved (2.50-6.00 ng L-1), as well as good linear dynamic ranges (20.00-2000.00 ng L-1), with suitable coefficients of determination (r2 > 0.9905) and appropriate precision (relative standard deviation below 15%). By use of the standard addition method, the proposed hybrid microextraction technique had remarkable performance to monitor PAHs at the ultratrace level in several types of matrices, including surface water, wastewater, soil, tea, and fish liver samples. From the data obtained, the new hybrid hollow fiber microextraction technique proved to be user-friendly, eco-friendly, cost-effective, and very competitive for routine work. In short, the novel microextraction technique proposed herein is a remarkable alternative to other well-established microextraction techniques for ultratrace analysis of emerging compounds in real matrices. Graphical abstract Innovative analytical procedure for hollow fiber microextraction (HFμE). GC gas chromatography, LD liquid desorption.

Examination of Indoor Mobile Mapping Systems in a Diversified Internal/External Test Field

Nowadays, simultaneous localization and mapping (SLAM) algorithms support several commercial sensors which have recently been introduced to the market, and, like the more common mobile mapping systems (MMSs), are designed to acquire three-dimensional and high-resolution point clouds. The new systems are said to work both in external and internal environments, and completely avoid the use of targets and control points. The possibility of increasing productivity in three-dimensional digitization projects is fascinating, but data quality needs to be carefully evaluated to define appropriate fields of application. The paper presents the analytical measurement principle of these indoor mobile mapping systems (IMMSs) and the results of some tests performed on three commercial systems. A common test field was defined in order to acquire comparable data. By taking the already available terrestrial laser scan survey as the ground truth, the datasets under examination were compared with the reference and some assessments are presented which consider both quantitative and qualitative aspects. Geometric deformation in the final models was computed using the so-called Multiscale Model to Model Cloud Comparison (M3C2) algorithm. Cross sections and cloud to mesh (C2M) distances were also employed for a more detailed analysis. The real usability assessment is based on the features of recognizability, double surface evidence, and visualization effectiveness. For these evaluations, comparative images and tables are presented.

First Deployment and Validation of in Situ Silicate Electrochemical Sensor in Seawater

An electrochemical sensor is proposed to measure silicate concentration, in situ, in the ocean without any addition of liquid reagent. From the analytical principle to the laboratory prototype toward the first in situ, immersible sensor, the evolution of the mechanical design is presented and discussed. The developed in situ electronics were compared to the commercial potentiostat and gave promising results to detect low silicate signals with a limit of quantification of 1 µmol L-1.The flow rate of the pump appeared to be a crucial parameter in order to transfer the silicomolybdic complex formed from the ‘complexation cell’ to the ‘detection cell’ without dilution as well as to fill and rinse the whole circuit. The study of temperature effect revealed no influence on the electrochemical signal between ~7°C and ~21°C. Finally the sensor was successfully deployed for the very first time on a mooring off Coquimbo, Chile and also integrated onto a PROVOR profiling float in the Mediterranean Sea off Villefranche-sur-Mer, France. The data collected and/or sent through satellite were in good agreement with the 2 reference samples and previously published values illustrating the great potential of this electrochemical sensor. A 7 days silicate time series from the mooring deployment off Chile is also presented.

Determining the Antifungal Agent Clioquinol by HPLC, the Not So Pure Preparation: A Laboratory-Based Case Study for an Instrumental Analytical Chemistry Course

The case study approach provides students with a better appreciation of how scientists solve problems and conduct themselves in the “real world”. When applied to the undergraduate chemistry laboratory, this approach also challenges critical thinking skills and creativity in ways “cook book” experiments very often do not. This approach provides students the opportunity to learn analytical principles in the context of relevant everyday problems, stimulate a sustaining interest, and develop higher cognitive skills and reasoning abilities. The laboratory-based case study described here combines the use of small collaborative groups and a modern instrumental technique, with application to a common consumer product. Students are required to conduct themselves as chemists would, when addressing the problem of product purity claims, and to make a determination based on their experimental results that will be used to direct future action taken by a formulation company. This case study even addresses potential lega...

New-generation bar adsorptive microextraction (BAμE) devices for a better eco-user-friendly analytical approach–Application for the determination of antidepressant pharmaceuticals in biological fluids

The present contribution aims to design new-generation bar adsorptive microextraction (BAμE) devices that promote an innovative and much better user-friendly analytical approach. The novel BAμE devices were lab-made prepared having smaller dimensions by using flexible nylon-based supports (7.5 × 1.0 mm) coated with convenient sorbents (≈ 0.5 mg). This novel advance allows effective microextraction and back-extraction (‘only single liquid desorption step’) stages as well as interfacing enhancement with the instrumental systems dedicated for routine analysis. To evaluate the achievements of these improvements, four antidepressant agents (bupropion, citalopram, amitriptyline and trazodone) were used as model compounds in aqueous media combined with liquid chromatography (LC) systems. By using an N-vinylpyrrolidone based-polymer phase good selectivity and efficiency were obtained. Assays performed on 25 mL spiked aqueous samples, yielded average recoveries in between 67.8 ± 12.4% (bupropion) and 88.3 ± 12.1% (citalopram), under optimized experimental conditions. The analytical performance also showed convenient precision (RSD < 12%) and detection limits (50 ng L−1), as well as linear dynamic ranges (160–2000 ng L−1) with suitable determination coefficients (r2 > 0.9820). The application of the proposed analytical approach on biological fluids showed negligible matrix effects by using the standard addition methodology. From the data obtained, the new-generation BAμE devices presented herein provide an innovative and robust analytical cycle, are simple to prepare, cost-effective, user-friendly and compatible with the current LC autosampler systems. Furthermore, the novel devices were designed to be disposable and used together with negligible amounts of organic solvents (100 μL) during back-extraction, in compliance with the green analytical chemistry principles. In short, the new-generation BAμE devices showed to be an eco-user-friendly approach for trace analysis of priority compounds in biological fluids and a versatile alternative over other well-stablished sorption-based microextraction techniques.

Fingerprinting Cynara scolymus L. (Artichoke) by Means of a Green Statistically Developed HPLC-PAD Method

The process to develop a chromatographic method for fingerprinting complex matrices should be performed through a multiparameter approach that could lead to the desired separation and save environmental resources such as organic solvents and energy. In other words, this process should be pursued by employing an optimized experimental design and having a response function which takes into consideration separation parameters together with environmental parameters. Green Analytical Chemistry principles should be pursued during all steps of the research. This work presents a heuristic approach to develop a high-performance liquid chromatography method for fingerprinting an extract from leaves of Cynara scolymus L., a food plant consumed worldwide. A fractional factorial design was used to identify relevant chromatographic variables followed by a comprehensive design for optimization purposes (Doehlert design). A response function called green chromatographic fingerprinting response was employed to obtain a compromise between fingerprint quality and low environmental impact of the method. This optimized approach led to the development of a robust and green method for fingerprinting C. scolymus by HPLC-PAD. This method proved to be greener than the reference method reported in literature and compatible even with no state of art HPLC instruments because the system backpressure did not exceed 15 MPa and the column temperature was 35 °C.