Mobile Instrument Research Articles

Liberalization in the Context of Democratization: Assessment of the January 2012 Fuel Subsidy Removal Protests in Nigeria

The decision by the Good Luck Jonathan-led regime to effect the removal of fuel subsidies on January 1st, 2012, prompted the most coordinated popular protests in Nigeria’s Fourth Republic. The subsidy removal and social protests it triggered had numerous socio-political implications. This paper examines the implications of the social protest on civic activism and political participation. The study adopts the qualitative research method. Data was derived from a combination of primary and secondary sources, which include news articles, opinion pieces, commentaries, editorials and press interviews published by Nigerian newspapers and sourced from their archives. It also utilized information sourced from official documents and reports published by governmental and non-governmental bodies. These materials were analyzed using the content analysis method. The study finds that it is essential for the State to engender citizen trust, given that trust is a core requirement for securing the legitimacy of the governed. The study also finds that the protests helped to rekindle the spirit of civic activism among Nigerians, especially the youth segment. This activism was largely aided by the deployment of digital tools as instruments for mobilization, coordination and communication in the protest movement. The article concludes that the subsidy removal protests had profound impacts on civic political activism, long thought to be dead among Nigerians.

Taming the time zone: National large-scale assessments as instruments of time in the Russian Federation

Nationwide large-scale assessments (NLSA)—an example of cross-border policy mobility—manifest a proliferating means of governing formal schooling. In the Russian context, NLSA takes the form of a compulsory graduation examination called the Unified State Examinations (USE). In this article, we explore how a mobile policy instrument of the NLSA participates in the relational processes of time- and space-making in a particular federated context of Russia, and how this process intertwines with and is shaped by the presence of multiple time zones. We argue that NLSA is an instrument of time that attempts to achieve centralization of the complex federated structure of the Russian Federation. Yet, the work of the NLSA is not a smooth process in a country characterized by territorial vastness, a complex federated structure, and the existence of multiple time zones. Guided by the theory of logistical power and sociological perspectives on time, as well as empirical insights, we show how the time zones need to be tamed in order for the NLSA to exercise its centralizing role. Discursively, the time zone is introduced and publicly discussed to symbolically characterize Russia and justify political actions or their outcomes. Bureaucratically, the desire for simultaneity and synchronicity takes the form of a meticulous ordering of a sequence of actions through prescriptive documentation that regulates the NLSA. Technologically, synchronicity, simultaneity, and instantaneousness rely on and engender an expanding national infrastructure that mediates social relations and the processes of conducting the NLSA, cutting across the time zones and federal units. Based on this analysis, we propose that scholarship on policy mobility and education policy sociology at large could benefit from examining the relationship between time and education policy and governance in four intertwined ways: the time of policy, context as time, policy instruments as instruments of time, and time in policy instruments.

Weak degassing from remote Alaska volcanoes characterized with a new airborne imaging DOAS instrument and a suite of in situ sensors

Gas emissions from volcanoes occur when volatile species exsolve from magmatic and hydrothermal systems and make their way to the surface. Measurements of emitted gases therefore provide insights into volcanic processes. On 16 July 2021, we made airborne measurements of weak gas plumes emitted from four remote Alaska volcanoes: Iliamna Volcano, Mount Douglas, Mount Martin, and Mount Mageik. Integrated into a small fixed-wing aircraft, a new Imaging Differential Optical Absorption Spectroscopy (DOAS) instrument was used to map the spatial extent of SO2 plumes as they drifted downwind. Contrary to conventional Mobile DOAS instruments, which provide only a single viewing direction, the Imaging DOAS simultaneously measures SO2 column density along 48 individual viewing directions oriented in a swath above or below the aircraft. Each of the individual measurements have a comparable precision and sensitivity to those obtained by conventional instruments. Together, they provide high resolution 2D imagery of the volcanic plumes and allow calculation of limited emission rate time series information. Although zenith-facing DOAS measurements achieve greater accuracy and are performed here, the application of the Imaging DOAS in a nadir-facing setup is also discussed and compared to satellite observations made in similar geometries. Also onboard the aircraft, a suite of electrochemical and optical sensors measured the relative abundances of the six major volcanic volatile species H2O, CO2, SO2, H2S, HCl, and HF as the aircraft passed through the plumes. Mean SO2 emission rates of 90 ± 10, 20 ± 3, and 13 ± 3 t/d were measured at Iliamna Volcano, Mount Douglas, and Mount Martin, respectively. SO2 emissions were below the DOAS detection limit at Mount Mageik but CO2 and H2S could be measured with the in situ sensors. The information gleaned from these measurements was used to assess and compare activity at these volcanoes, all of which were found to be in a state of background degassing but whose emissions pointed to different source conditions ranging from mixed magmatic-hydrothermal to purely hydrothermal in character. Additional measurements at Mount Spurr, Redoubt Volcano, and Augustine Volcano failed to detect the very weak gas concentrations downwind of these persistently degassing vents.

Layout of ancient Greek papyri through lead-drawn ruling lines revealed by Macro X-Ray Fluorescence Imaging

The use of lead-drawn ruling lines by ancient scribes for the layout of Greek papyrus rolls was known to us only from classical authors and was postulated by a few scholars in modern times. In situ application of noninvasive Macro X-Ray Fluorescence Imaging Spectroscopy (MA-XRF) to unrolled papyri from Herculaneum, dating from about 200 BC to the 1st century AD, has provided the first direct evidence of such practice in ancient book production. The key experimental proof of periodic lines drawn in lead was gathered by a highly sensitive MA-XRF mobile instrument, which allowed detection of ultra-low trace residues of metals with detection limits that rival synchrotron light instruments. Elemental distribution maps of Pb have revealed three different systems of textual layout in ancient papyrus rolls and have resolved the dispute around so-called Maas’ Law, by delivering experimental proof that slanted text columns were a deliberate aesthetic choice of scribes.

Validation of Sentinel-5P TROPOMI tropospheric NO2 products by comparison with NO2 measurements from airborne imaging DOAS, ground-based stationary DOAS, and mobile car DOAS measurements during the S5P-VAL-DE-Ruhr campaign

Abstract. Airborne imaging differential optical absorption spectroscopy (DOAS), ground-based stationary DOAS, and car DOAS measurements were conducted during the S5P-VAL-DE-Ruhr campaign in September 2020. The campaign area is located in the Rhine-Ruhr region of North Rhine-Westphalia, western Germany, which is a pollution hotspot in Europe comprising urban and large industrial sources. The DOAS measurements are used to validate spaceborne NO2 tropospheric vertical column density (VCD) data products from the Sentinel-5 Precursor (S5P) TROPOspheric Monitoring Instrument (TROPOMI). Seven flights were performed with the airborne imaging DOAS instrument for measurements of atmospheric pollution (AirMAP), providing measurements that were used to create continuous maps of NO2 in the layer below the aircraft. These flights cover many S5P ground pixels within an area of 30 km × 35 km and were accompanied by ground-based stationary measurements and three mobile car DOAS instruments. Stationary measurements were conducted by two Pandora, two Zenith-DOAS, and two MAX-DOAS instruments. Ground-based stationary and car DOAS measurements are used to evaluate the AirMAP tropospheric NO2 VCDs and show high Pearson correlation coefficients of 0.88 and 0.89 and slopes of 0.90 ± 0.09 and 0.89 ± 0.02 for the stationary and car DOAS, respectively. Having a spatial resolution of about 100 m × 30 m, the AirMAP tropospheric NO2 VCD data create a link between the ground-based and the TROPOMI measurements with a nadir resolution of 3.5 km × 5.5 km and are therefore well suited to validate the TROPOMI tropospheric NO2 VCD. The observations on the 7 flight days show strong NO2 variability, which is dependent on the three target areas, the day of the week, and the meteorological conditions. The AirMAP campaign data set is compared to the TROPOMI NO2 operational offline (OFFL) V01.03.02 data product, the reprocessed NO2 data using the V02.03.01 of the official level-2 processor provided by the Product Algorithm Laboratory (PAL), and several scientific TROPOMI NO2 data products. The AirMAP and TROPOMI OFFL V01.03.02 data are highly correlated (r=0.87) but show an underestimation of the TROPOMI data with a slope of 0.38 ± 0.02 and a median relative difference of −9 %. With the modifications in the NO2 retrieval implemented in the PAL V02.03.01 product, the slope and median relative difference increased to 0.83 ± 0.06 and +20 %. However, the modifications resulted in larger scatter and the correlation decreased significantly to r=0.72. The results can be improved by not applying a cloud correction for the TROPOMI data in conditions with high aerosol load and when cloud pressures are retrieved close to the surface. The influence of spatially more highly resolved a priori NO2 vertical profiles and surface reflectivity are investigated using scientific TROPOMI tropospheric NO2 VCD data products. The comparison of the AirMAP campaign data set to the scientific data products shows that the choice of surface reflectivity database has a minor impact on the tropospheric NO2 VCD retrieval in the campaign region and season. In comparison, the replacement of the a priori NO2 profile in combination with the improvements in the retrieval of the PAL V02.03.01 product regarding cloud heights can further increase the tropospheric NO2 VCDs. This study demonstrates that the underestimation of the TROPOMI tropospheric NO2 VCD product with respect to the validation data set has been and can be further significantly improved.

A mobile instrument for joint X-ray fluorescence and diffraction measurements on complex-shape Cultural Heritage objects

A mobile instrument for joint X-ray fluorescence and diffraction measurements on complex-shape Cultural Heritage objects

A computational tool for conceptual design and optimization of planetary rovers

The design process of a Mars rover is driven by multiple design constraints, namely overall mass, power consumption and volume (dimensions). Various systems, such as mobility, manipulation, handling, power, thermal, communication, navigation, avionics and science instruments, together make a complete rover vehicle and they should function collectively to perform a given task. Each of the subsystems can be thought of as modular building blocks that are integrated together to form a fully functional rover vehicle. When approaching the design of such a vehicle, the designer should take into account of cross design dependencies existent between different subsystems and technology limitations. Performing any particular task, would lead to many design possibilities. Choosing the final design from many feasible solutions is arguably a daunting task. In order to make this process simple and convenient, as well as to understand the design non-linearity existing in this solution space, the authors have employed a systems engineering approach to develop a tool comprising subsystem models. The subsystem models comprise parametric and physics-based models. For designing suitable user-defined objectives, these models when integrated with Genetic Algorithm forms an effective tool to support design trade-offs during the conceptual design process. This integrated modeling and optimization approach is thought to be efficient in identifying rover system concepts.

Gamma Scientific Sets High Standards for Light Measurement

Gamma Scientific Sets High Standards for Light Measurement

Comparative assessment of two portable Raman spectrometers for the characterisation of historical natural dye lakes

AbstractThis paper explores the use of portable Raman instruments to characterise natural dye lakes in paint mixtures, as an alternative approach to other Raman techniques (e.g. SERS). Raman spectroscopy has indeed been used extensively to study natural dyes as pure substances or as artistic pigments (dye lakes). However, the examination of these compounds with Raman spectroscopy is particularly challenging because of a strong fluorescence, a relatively weak Raman signal and their occurrence at low concentrations in artefacts. Because of these challenges, the typical way of analysing these materials is through either surface‐enhanced Raman spectroscopy (SERS) or Fourier‐transform (FT) Raman spectroscopy, yet those approaches are not always desirable in art analysis, especially as they often require micro‐sampling. Therefore, this study explores the potential of using commercial mobile instruments, which would open the possibilities for direct in situ analysis. Two dispersive instruments, one using a fibre‐optic probe and a 1064‐nm excitation laser and the other using the subtracted‐shifted excitation (SSE) post‐processing algorithm, have been tested in their feasibility to characterise dye lakes. Raman spectra were acquired from a set of laboratory reproductions of paint mixtures prepared with a chosen set of common lakes, three red (brazilwood, cochineal and madder) and one yellow (weld), mixed with natural proteinaceous and polysaccharide binders. The feasibility has been evaluated, and it is shown that these lakes produce a detectable Raman signal, in spite of the strong interference of the painting support (parchment) and that the two instruments provide significantly different information.

Developing Rigorous Mathematical Thinking Approach-Based Learning Materials for Sequences and Series Concept at High School Level in Tanjungpinang

Mathematics encourages logical reasoning and critical thinking. Rigorous thinking helps in analysing problems to decision-making and ensures that solutions are accurate and reliable. Prior research indicated students’ lack of those abilities when learning the concept of sequences and series. Therefore, this research aims to develop learning materials for the concept of sequences and series based on rigorous mathematical thinking (RMT) approach. The learning materials developed with the ADDIE model include mobile learning, student worksheets, and test instruments, which provide clear explanations, examples, problem-solving activities with RMT approach, and assessments enabling teachers to evaluate students’ understanding of mathematics concepts of the sequences and series. The learning materials were validated using a questionnaire by mathematics experts. The quantitative and qualitative data results show that the mobile learning, student worksheets, and test instruments are valid. Mobile learning that was developed and tested valid entails that the study can add to a new learning strategy that proposes technology and digital tools to engage students in the learning process and promote RMT.

Healthcare surveillance based on cloud computing utilizing mobile devices

Cardiologists utilized electrocardiograms (ECGs) to observe cardiac disease in everyday life. A system for reading ECGs outside the hospital based on a Mobile Instrument (MobileInst) was developed to make it easier for specialists to observe their patients’ ECGs. A MobileInst receives an ECG signal and sends the signals to an ECG instrument based on the proposed system. By using MobileInst, ECG equipment alarms can be detected. A Cloud Alarm Service (SCA), which records ECG signaling and alert information, receives alarm information when MobileInst receives alarm signals. MobileInst displays the ECG signaling and alarm data when the messages are received by Alert Server. Using the suggested scheme, specialists can keep track of their patients’ ailments through ECG signaling sent to their MobileInst devices. Signals for this study were collected from the MIT-BIH PhysioBank database. In observing patients, the technique was found to be accurate in providing accurate results.

Effectiveness n Online Professional i Education: Influences of Technology, Lms, Personal Factors and Teaching Aids

Abstract: Student learning through online tools during the pandemic covid-19 situation has been studied and reported in this paper. Students pursuing engineering under graduation and business management post graduation were given a Google form to respond to questions related to type and kind of online platform used, difficulties in teaching-learning, expectations of students etc. Suggestions were invited for better learning online. This paper presents the results of the feedback of students on technical and non-technical issues during online learning. The online environment is sub-divided into four broad categories viz., technological, personal, teaching aids and learning management system. Influence of these parameters on effectiveness of online teaching and feedback from students are discussed. Students had difficulties in internet network, bandwidth, clarity of audio-visual, interruptions in power supply, wifi-networks, poor infrastructure and affordability. 57 percent of respondents are dependent on mobile phone instruments for online class work. Majority of students felt that online certification courses can reduce burden to some extent. The results can be used for designing better online tools for effective online learning for students. Key words: Online learning platform, teachinglearning, difficulties in learning,

Загальний підхід до поводження з паливовмісними матеріалами і супутніми радіоактивними відходами на етапі діяльності з вилучення їх із приміщень об’єкта «Укриття»

After the commissioning of the New Safe Confinement — Shelter object (NSC-SO) complex, radioactive waste (RAW) management activities during the removal of fuel containing materials (FCM) from the SO premises must be carried out with the involvement of NSC systems, including the system of main cranes (SMC), as well as systems and equipment of the technological building (TB), as a component of the NSC. The paper presents a new principled approach to waste management that will be generated during the extraction of FCM from the SO. The transport and technological chains of waste management by their types are considered: FCM, highly active waste and associated RAW. It is noted that the dose rates in many areas of work in the SO can reach 10 Sv/h. In such conditions, the involvement of personnel in physical work should be completely excluded, and the robotics, which will participate in technological operations, should be prepared for work in high ionizing radiation fields. For this reason, the removed FCM cannot be sent for processing to the TB of the NSC, as is done with other RAW (medium-level waste, low-level waste), which were removed from the premises of the SO earlier. It is justified that handling of FCM should be carried out in hermetic protective blocks (block of hot cells). Such cameras should be built in the NSC space as part of the new production building. It is noted that the volume of associated RAW, which will be formed during the extraction of FCM from the SO, will be extremely large. It is practically impossible to carry out their quantitative assessment. The work on the management of associated RAW will be carried out similarly to the work on the removal of FCM. Detected highly active fragments on overall structures should be cut out if possible, and small fragments or detected explosives in building materials are loaded into a transportable container for explosives with their further transfer of the container to the block of hot cameras. The remaining RAW, including radioactively contaminated metal structures and radioactively contaminated concrete structures, are loaded into the container for adjacent RAW and moved to the NSC temporary storage site. Waste removal work should be carried out using a system of a mobile instrument platform of the NSC crane with a remotely controlled robot manipulator (RCRM) attached to it and separate mobile remotely controlled mechanisms (RCM) on their own, depending on their needs. Conclusions are given regarding the sufficiency of infrastructure capabilities for RAW handling at the Chornobyl nuclear power plant and in the Exclusion Zone (EZ), to ensure this activity in general. It is noted that the activities for the preparation of infrastructure facilities for waste management during the removal of FCM from the SO should be directed both to the extension of the operational life of existing facilities and to the construction of new ones.

The dependence of reduced mobility, ion-neutral collisional cross sections, and alpha values on reduced electric field strengths in ion mobility.

As ion mobility spectrometry (IMS) is used with mass spectrometry in more applications, increased emphasis is placed on the ion-neutral collisional cross sections (CCS) to identify unknown analytes in complex matrices. While CCS values can provide useful information about relative analyte size, several critical assumptions are inherent in the most common method of calculating CCS values, the Mason-Schamp equation. The largest source of error in the Mason-Schamp equation originates from not accounting for higher reduced electric field strengths, which are present in low-pressure instruments that require calibration. Previous corrections based on field strength have been proposed in literature, but their data used atomic ions in atomic gases, whereas most applications examine molecules measured in nitrogen. Here, we use a series of halogenated anilines measured in air and nitrogen between 6-120 Td on a first principles ion mobility instrument (HiKE-IMS). With this series of measurements, the average velocity of the ion packet is known allowing for direct calculation of reduced mobilities (K0), alpha functions, and finally, a detailed examination of CCS as a function of E/N. In the worst-case scenario, there is over a 55% difference in CCS values for molecular ions measured at high fields depending on the method used. When comparing CCS values to those in a database for unknown identification, this difference can lead to misidentification. To immediately alleviate some of the error in calibration procedures, we propose an alternative method using K0 and alpha functions that simulate first principles mobilities at higher fields.

DEVELOPMENT OF BUSINESS STRUCTURES DURING THE COVID-19 PANDEMIC

The relevance of the topic is dictated by the fact that currently the ongoing transformational processes in the modern economy have almost completely covered all business structures and require scientists to develop fundamentally new methods and methodologies for the formation of an effective organizational and economic mechanism for their development.
 The positive impact of entrepreneurship on the economic system of the state is beyond doubt. In addition to budget revenues and job creation, as a factor of socio-economic development, entrepreneurship is also the most mobile instrument of economic relations in the new market realities, helping to systematically transform the economy of the state.
 This article examines the current state and development of entrepreneurial structures in Russia and the problems faced by entrepreneurs in carrying out economic activities.
 The result of the research is the solution of the tasks of substantiating theoretical and methodological provisions and developing practical recommendations for the formation and development of business structures in modern conditions of increased instability and crisis caused by the COVID-19 pandemic.

VOILA on the LUVMI-X Rover: Laser-Induced Breakdown Spectroscopy for the Detection of Volatiles at the Lunar South Pole

The project Lunar Volatiles Mobile Instrumentation-Extended (LUVMI-X) developed an initial system design as well as payload and mobility breadboards for a small, lightweight rover dedicated for in situ exploration of the lunar south pole. One of the proposed payloads is the Volatiles Identification by Laser Analysis instrument (VOILA), which uses laser-induced breakdown spectroscopy (LIBS) to analyze the elemental composition of the lunar surface with an emphasis on sampling regolith and the detection of hydrogen for the inference of the presence of water. It is designed to analyze targets in front of the rover at variable focus between 300 mm and 500 mm. The spectrometer covers the wavelength range from 350 nm to 790 nm, which includes the hydrogen line at 656.3 nm as well as spectral lines of most major rock-forming elements. We report here the scientific input that fed into the concept and design of the VOILA instrument configuration for the LUVMI-X rover. Moreover, we present the measurements performed with the breadboard laboratory setup for VOILA at DLR Berlin that focused on verifying the performance of the designed LIBS instrument in particular for the detection and quantification of hydrogen and other major rock forming elements in the context of in situ lunar surface analysis.

Senegal

In 2018, Senegalese hip hop celebrated its thirtieth anniversary as one of Africa’s most vibrant hip hop scenes. Senegalese rap has asserted itself not only as an expedient form of urban art, but also as a socially, politically, and culturally powerful instrument of both persuasion and mobilization for the masses. From its privileged beginnings in Dakar’s posh nightclubs and Catholic high schools, the genre soon asserted itself as quite distinct from hip hop in other parts of the world, and its popularity increasingly grew to wide segments of the Senegalese public. From the mid-1990s, the underprivileged segments of the society (especially those from the poor peripheral neighbourhoods of Dakar) became progressively vocal, using hip hop as an instrument to give voice to the economic and political predicaments of the people, particularly the youth. The production of the music became increasingly local, and its primary language the Senegalese lingua franca Wolof. What has given Senegalese rap both its personality and power, while enabling it to keep an international aura, has been its political engagement: from early on, Senegalese hip hop has been strongly penetrated by politics and the denunciation of the living conditions of the population, of political abuse and social inequality. This article examines ‘hip hop galsen’ over three decades, detailing its development as a successful genre grounded in local realities that gives voice to the concerns and predicaments of the Senegalese public. It concludes through an examination of recent changes, as evidenced in new musical influences, the several important female voices that can now be heard within a historically male-dominated genre, and the greater support and acceptance hip hop has recently enjoyed, equipping the current generation of Senegalese rappers with the promise of bringing it to the international stage.

Physical functioning assessment tools in critical care: a wide national survey in Chile during the COVID-19 pandemic

Physical functioning evaluation in intensive care units (ICUs) identifies rehabilitation requirements and response to interventions. To identify the usage rate of physical functioning measurement instruments in ICUs during the COVID-19 pandemic in Chile. Lead physiotherapists representing different national ICUs were invited to answer a National online survey at the onset (T1) and at the first year of COVID-19 pandemic (T2). The usage rate (defined as "always"/"almost always"/"almost never"/"never") of instruments assessing muscle strength, muscle mass, mobility, and physical performance was surveyed. Also, the reasons for selecting these instruments were requested. We received responses from 94 and 93 ICUs at T1 and T2, respectively, of 111 eligible ICUs (55% public). Compared with T2, the usage rate of instruments was lower at T1, and significant only for Medical Research Sum-Score (MRC-SS) (p = 0.04) and handgrip dynamometry (p = 0.05). Considering the answers "always", "almost always" and "almost never", between 89% and 91% of the ICUs reported the use of the MRC-SS; between 70% and 73% reported the use of the Functional Status Score for the Intensive Care Unit; between 5% and 35% of the ICUs reported the use of the rest of mobility scales; and between 44%-45% of ICUs reported that muscle ultrasound was "almost never" used. The main reasons reported for selecting instruments were quick use and clinimetric properties. The usage rate of muscle strength assessments was frequent, while the use of mobility and muscle mass instruments recommended by the literature was poorly reported, which was lower at the onset of the pandemic.

PanoMRT: Panoramic infrared thermography to model human thermal exposure and comfort

As summer heat waves become the new normal worldwide, modeling human thermal exposure and comfort to assess and mitigate urban overheating is crucial to uphold livability in cities. We introduce PanoMRT, an open source human-biometeorological model to calculate Mean Radiant Temperature (TMRT), Physiologically Equivalent Temperature (PET), and the Universal Thermal Climate Index (UTCI) from thermal equirectangular 360° panoramas and standard weather information (air temperature, relative humidity, wind speed). We validated the model for hot, dry, clear summer days in Tempe, Arizona, USA with in-situ observations using a FLIR Duo Pro R thermal camera on a rotating arm and the mobile human-biometeorological instrument platform MaRTy. We observed and modeled TMRT and thermal comfort for 19 sites with varying ground cover (grass, concrete, asphalt), sky view factor, exposure (sun, shade), and shade type (engineered, natural) six times per day. PanoMRT performed well with a Root Mean Square Error (RMSE) of 4.1 °C for TMRT, 2.6 °C for PET, and 1.2 °C for UTCI, meeting the accuracy requirement of ±5 °C set in the ISO 7726 standard for heat and cold stress studies. RayMan reference model runs without measured surface temperature forcing reveal that accurate longwave radiative flux estimations are crucial to meet the ±5 °C threshold, particularly for shaded locations and during midday when surface temperatures peak and longwave modeling errors are largest. This study demonstrates the importance of spatially resolved 3D surface temperature data for thermal exposure and comfort modeling to capture complex longwave radiation exposure patterns resulting from heterogeneity in built configuration and material radiative and thermal properties in the built environment.

A comparison between mobile and stationary gas chromatography–mass spectrometry devices for analysis of complex volatile profiles

On-site analysis of volatile organic compounds (VOCs) with miniaturized gas chromatography–mass spectrometry (GC–MS) systems is a very rapidly developing field of application. While, on the one hand, major technological advances are improving the availability of these systems on the market, on the other hand, systematic studies to assess the performance of such instruments are still lacking. To fill this gap, we compared three portable GC–MS devices to a state-of-the-art benchtop (stationary) system for analysis of a standard mixture of 18 VOCs. We systematically compared analytical parameters such as the sensitivity and similarity of the signal response pattern and the quality of the obtained mass spectra. We found that the investigated mobile instruments (i) showed different response profiles with a generally lower number of identified analytes. Also, (ii) mass spectral reproducibility (% relative standard deviation (RSD) of the relative abundance of selective fragments) was generally worse in the mobile devices (mean RSD for all targeted fragments ~9.7% vs. ~3.5% in the stationary system). Furthermore, mobile devices (iii) showed a poorer mass spectral similarity to commercial reference library spectra (>20% deviation of fragment ion relative intensity vs. ~10% in the stationary GC–MS), suggesting a less reliable identification of analytes by library search. Indeed, (iv) the performance was better with higher-mass and/or more abundant fragments, which should be considered to improve the results of library searches for substance identification. Finally, (v) the estimation of the signal-to-noise ratio (S/N) in mobile instruments as a measure of sensitivity revealed a significantly lower performance compared to the benchtop lab equipment (with a ratio among medians of ~8 times lower). Overall, our study reveals not only a poor signal-to-noise ratio and poor reproducibility of the data obtained from mobile instruments, but also unfavorable results with respect to a reliable identification of substances when they are applied for complex mixtures of volatiles.Graphical