Mass-based Methods Research Articles

Identification of different plastic types and natural materials from terrestrial environments using fluorescence lifetime imaging microscopy

Environmental pollution by plastics is a global issue of increasing concern. However, microplastic analysis in complex environmental matrices, such as soil samples, remains an analytical challenge. Destructive mass-based methods for microplastic analysis do not determine plastics’ shape and size, which are essential parameters for reliable ecological risk assessment. By contrast, nondestructive particle-based methods produce such data but require elaborate, time-consuming sample preparation. Thus, time-efficient and reliable methods for microplastic analysis are needed. The present study explored the potential of frequency-domain fluorescence lifetime imaging microscopy (FD-FLIM) for rapidly and reliably identifying as well as differentiating plastics and natural materials from terrestrial environments. We investigated the fluorescence spectra of ten natural materials from terrestrial environments, tire wear particles, and eleven different transparent plastic granulates <5 mm to determine the optimal excitation wavelength for identification and differentiation via FD-FLIM under laboratory conditions. Our comparison of different excitation wavelengths showed that 445 nm excitation exhibited the highest fluorescence intensities. 445 nm excitation was also superior for identifying plastic types and distinguishing them from natural materials from terrestrial environments with a high probability using FD-FLIM. We could demonstrate that FD-FLIM analysis has the potential to contribute to a streamlined and time-efficient direct analysis of microplastic contamination. However, further investigations on size-, shape-, color-, and material-type detection limitations are necessary to evaluate if the direct identification of terrestrial environmental samples of relatively low complexity, such as a surface inspection soil, is possible.Graphical

Impact of quantification method on microfiber assessment – A comparative analysis between mass and count based methods

Microfiber from textiles is one of the new anthropogenic pollutants which attracted a wide range of researchers. Domestic laundry, being the most common cause of microfiber release from textiles, is widely studied. Studies exhibit a broad range of quantities of microfibers owing to the distinct quantification methodologies employed due to their convenience and resource availability. Out of several such estimation processes, reporting microfiber quantity in numbers or mass (mg or g) is quite common with respect to the unit area or weight of the textile used. However, results reported by different literature vary significantly. Hence, this study aims to analyze the microfiber release from knitted polyester fabric using count- and mass-based methods. Four different fabrics were used for this study with three different counting processes from literature along with direct weight difference estimation. The results of the direct counting method showed that the average microfiber release of selected fabrics is 13.28–33.16 microfibers per sq.cm, whereas, the direct weight estimation showed an average weight of 0.0664 ± 0.0289 mg/sq.cm. The subsequent conversion showed a release of 887.89 ± 633.49 microfibers/sq.cm of the fabric. Further, the microfiber mass was also estimated using the number of microfiber count and found that a sq.cm of fabric releases up to 0.0010–0.0024 mg of microfibers. While comparing the results, the weight-based estimation showed a significantly higher microfiber release (41.3–42.9 times) than the direct counting method. The deposition of surfactants in detergents, contaminants from the water, atmospheric contaminants, and finishes released from the fabric can be the sources of additional weights noted in the direct mass estimation. As the weight-based method is quite simple and the fastest way to quantify the microfibers, future studies must focus on this area to reduce the error percentage in quantification.

Fundamentals of Biosensors and Detection Methods.

Biosensors have a great impact on our society to enhance the life quality, playing an important role in the development of Point-of-Care (POC) technologies for rapid diagnostics, and monitoring of disease progression. COVID-19 rapidantigen tests, home pregnancy tests, and glucose monitoring sensors represent three examples of successful biosensor POC devices. Biosensors have extensivelybeen used in applications related to the control of diseases, food quality and safety, and environment quality. They can provide great specificity and portability at significantly reduced costs. In this chapter are described the fundamentals of biosensors including the working principles, general configurations, performance factors, and their classifications according to the type of bioreceptors and transducers. It is also briefly illustrated the general strategies applied to immobilize biorecognition elements on the transducer surface for the construction of biosensors. Moreover, the principal detection methods used in biosensors are described, giving special emphasis on optical, electrochemical, and mass-based methods. Finally, the challenges for biosensing in real applications are addressed at the end of this chapter.

Benzophenone used as the photochemical reagent for pinpointing C=C locations in unsaturated lipids through shotgun and liquid chromatography-mass spectrometry approaches

Unsaturated lipids exhibit different physiological significances due to the different locations of the carbon–carbon double bond (C=C). Identifying lipid isomers with mass-based methods remains challenging. Xia's group has been successfully employed Paternò–Büchi (PB) reaction, a photochemical reaction with UV irradiation, coupled with tandem mass spectrometry (MS/MS) to identify and quantify unsaturated lipids in complex mixtures. However, the existing PB reagents possess certain demerits. In this regard, a new PB reagent that is compatible with various lipidomic analysis platforms must be screened. In this study, we comprehensively evaluated the conditions of the PB reaction and screened benzophenone as a new PB reagent. Benzophenone possesses unique advantages, such as a relative high PB yield; the PB products could be readily distinguished from the reacted lipids based on the added high molecular weight (182 Da); and the benzophenone does not affect the lipids appearance interval for reversed-phase column separation. Furthermore, we optimized the reaction conditions by using benzophenone as a PB reagent and summarized the molecular formulas of the diagnostic ions according to the fragment rules. The proposed PB method has been implemented in shotgun and LC–MS lipidomics. To our best knowledge, this work is the first to report the integrated PB reaction with LC–MS lipidomics for identification of lipid isomers.

Dead weight: Validation of mass regression equations on experimentally burned skeletal remains to assess skeleton completeness

In very fragmentary remains, the thorough inventory of skeletal elements is often impossible to accomplish. Mass has been used instead to assess the completeness of the skeleton. Two different mass-based methods of assessing skeleton completeness were tested on a sample of experimentally burned skeletons with the objective of determining which of them is more reliable. The first method was based on a simple comparison of the mass of each individual skeleton with previously published mass references. The second method was based on mass linear regressions from individual bones to estimate complete skeleton mass. The clavicle, humerus, femur, patella, metacarpal, metatarsal and tarsal bones were used. The sample was composed of 20 experimentally burned skeletons from 10 males and 10 females with ages-at-death between 68 and 90years old. Results demonstrated that the regression approach is more objective and more reliable than the reference comparison approach even though not all bones provided satisfactory estimations of the complete skeleton mass. The femur, humerus and patella provided the best performances among the individual bones. The estimations based on the latter had root mean squared errors (RMSE) smaller than 300g. Results demonstrated that the regression approach is quite promising although the patella was the only reasonable predictor expected to survive sufficiently intact to a burning event at high temperatures. The mass comparison approach has the advantage of not depending on the preservation of individual bones. Whenever bones are intact though, the application of mass regressions should be preferentially used because it is less subjective.

Laser Wavelength and Pressure Dependence of Laser Breakdown Time-of-Flight Mass Spectrometry

Since the demands for lowering the burdens on the environment will continue to grow steadily, understanding of pollutant emission characteristics becomes more and more important to minimize environmental disruption. These pollutant emission conditions cannot be estimated in real-time using conventional mass-based methods because of their low concentrations in air or exhaust gases. Therefore, new evaluation criteria are required for better understanding of their characteristics. In this study, the laser breakdown time-of-flight mass spectrometry was developed and applied to hydrocarbons to detect the elemental composition of gas phase materials. The laser wavelength dependence of this method was evaluated using 1064 and 266 nm laser outputs. Signals from fragments of hydrocarbons appeared using 266 nm. On the other hand, it was found that the mass spectra of atoms can be detected using the 1064 nm laser breakdown process without intermediate fragment signals. This feature is important to detect atomic signals of the measured materials without the interference of fragmentations. The pressure effect was also evaluated to enhance the detection limit. The higher pressure tends to induce the higher atomic signals. The detection limit can easily reach to ppb or less. The signal intensity was proportional to the concentration of hydrocarbons introduced. The method was applied to various hydrocarbons and the breakdown characteristics of these molecules were taken for the quantitative analysis. Compared with conventional measurements, this method has a lot of merits of the simple signal analysis, real-time and sensitive detection features. The method can cover various industrial applications including the exhaust analysis of combustors, environmental monitoring of air, and plant monitoring for safety and security.

Presenting a Pattern for Increasing the Relative Efficiency of the Bank by Using Data Envelopment Analysis: (Case Study Agricultural Bank of Lorestan Province).

One of the factors in success of the developed countries is considering the efficiency of units. Efficient units not only do not waste the energy but also they obtain the resources properly. As, in every economy, bank are important institutions and essential posts and have a determinant role in developing the economy, their performance assessment has always been important. In todays world, considering the limitation of resources and excessive cost of providing them, proper decisions about the strategy of applying resources are significant. For the time being, domestic banks use transactional mass-based methods and methods based on performance operations, on the amount of equipment, and on obtaining resources in order to assess the performance & ranking of branches. So efficiency index reflects the process of activity between inputs & outputs of a branch which can be a more suitable criterion in assessing the branches performance. Data envelopment analysis is a theoretical framework in assessing, analyzing, & measuring efficiency which do the function of evaluating Decision making units via solving its own models. In this study, for assessing relative efficiency of Agriculture Bank branches in Lorestan Province, two basic models in Data Envelopment Analysis have been used: input-oriented CCR, BCC. The results of this research show that, among 23 branches under evaluation in CCR model, 6 branches are efficient and 17 are inefficient and among 23 branches in BCC model, 15 branches are efficient and 8 are inefficient. By applying AP model, branches have been ranked and a model has been presented for inefficient branches.

Immunodetection and quantification of airborne (1–3)-β-D-glucan-carrying particles with the halogen immunoassay

Fungal cell wall components, such as (1–3)-β-D-glucan, are known to be capable of activating the innate immune system and pose a respiratory health risk in different environments. Mass-based non-viable techniques commonly used for assessment of fungal exposures could be β-D-glucan-specific, but are limited to analysis of liquid extracts. The variable solubility of different β-D-glucans may underestimate β-D-glucan exposure and long sampling times required for mass-based methods make assessing short-term exposures difficult. In this study, we evaluated the utility of the halogen immunoassay (HIA), an immunoblotting technique previously used for allergens, to immunodetect and quantify β-D-glucan-carrying particles (BGCPs). The HIA was able to detect BGCPs without background staining when β-D-glucan standards and air samples collected at a poultry house during short sampling periods were evaluated. The image analysis protocol previously developed by our group for mouse allergen allowed simultaneous immunodetection and quantification of β-D-glucan-containing particles. Our results suggest that the HIA holds promise for quantifying β-D-glucan exposures. To our knowledge, this is the first time in which the HIA was used for non-allergenic compounds of microbial or fungal origins.

New and notable at ASMS

Earlier this month, more than 6,200 scientists gathered in Denver for the American Society for Mass Spectrometry’s 59th Conference on Mass Spectrometry & Allied Topics. At the meeting, instrument companies unveiled an array of new products. MASS SPECTROMETERS AB SCIEX INTRODUCES ION MOBILITY CAPABILITY AB Sciex is adding an extra level of analytical selectivity to its Triple Quad 5500 and QTRAP 5500 instruments with differential ion mobility. In ion mobility, components in a mixture are separated on the basis of molecular size and shape rather than mass, adding an orthogonal separation method to the instruments’ existing mass-based methods. The SelexION ion mobility cell is incorporated as part of the ionization source. AB Sciex customer Rick King, founder and director of PharmaCadence Analytical Services, said that adding SelexION to a system improved the limits of quantification by a factor of 10. BRUKER LAUNCHES COMPACT VERSION OF MAXIS With the new maXis impact, Bruker Daltonics is ...

An Evaluation of Particle Size Distributions and Particle Number-Based Reductions from Various PM Emission Control Technologies

An Evaluation of Particle Size Distributions and Particle Number-Based Reductions from Various PM Emission Control Technologies

Soil organic carbon and nitrogen stocks in an age-sequence of poplar stands planted on marginal agricultural land in Northeast China

Afforestation of marginal agricultural land has been considered to be an effective measure to sequester atmospheric CO2. In this study, we adopted the volume- and mass-based methods to investigate the changes in soil organic C and total N stocks in 100 cm depth following afforestation of marginal agricultural land using a chronosequence of poplar (Populus euramericana cv. "N3016") stands in a semiarid region of Liaoning Province, Northeast China. Our results showed that soil organic C and total N concentrations in 45-60 cm layer increased gradually following afforestation of agricultural land, whereas in 60-100 cm layer, they declined initially, and then increased with stand development. Based on volume- and mass-based methods, such land-use change caused initial declines in soil organic C and total N stocks, and then increases between the stand ages of 10 and 20. Forest soils recovered to the initial soil organic C and N stocks found in agricultural land at age 15. However, the volume-based method would underestimate the absolute organic C and N stocks compared with the mass-based methods. Our results suggest that afforestation of marginal agricultural land has the potential to sequester atmospheric CO2 in soils in semiarid regions. Stand age, soil sampling depth and the methods used to quantify organic C and N stocks should be considered for accurate assessments of changes in soil organic C and N stocks.

Deflection, Acceleration, and Force Corridors for Small Females in Side Impacts

Objective. This study was undertaken to develop biomechanical corridors applicable to the small-sized female in side impacts. Methods. Sled tests were conducted using post mortem human subjects at a velocity of 6.7 m/s. Three chestbands were used to compute deflection-time histories at the axilla, xyphoid process, and tenth rib levels. Triaxial accelerometers were fixed to the upper and lower spine and sacrum to record acceleration-time histories. Specimens contacted the load wall with varying initial conditions (rigid and padded; flat wall and offset) from which impact forces to the thoracic, abdominal, and pelvic regions were obtained using load cell data. Adopting signal processing and mass-based scaling methods, corridors were derived for forces, accelerations, and chest deflections at three levels for all initial conditions. Results. All time history corridors were expressed as mean plus/minus one standard deviation and provided in the article. Conclusions. Acceleration-, deflection-, and force-time corridors obtained for the chest and pelvic regions of the human body will assist in the assessment of anthropomorphic test devices used in crashworthiness evaluations.

Full band approach to tunneling in MOS structures

Using atomistic quantum mechanical tight-binding (TB) methods that include the full band structure, we study electron tunneling through three-dimensional models of n/sup +/-Si/SiO/sub 2//p-Si capacitors with thicknesses between 0.7 and 4.4 nm. We find that the microscopic oxide structure influences transmission coefficients and tunnel currents significantly. The best agreement with experimental current-thickness and current-voltage data is obtained for a model derived from the /spl beta/-cristobalite polytype of SiO/sub 2/ that has a fairly small conduction band mass of 0.34 m/sub 0/. Standard approximate effective mass-based methods reproduce the TB results only if an energy and oxide thickness dependence of the mass parameter is introduced.

Coronary artery calcium: alternate methods for accurate and reproducible quantitation.

The aim of this study was to determine a more precise and accurate method of quantitating coronary artery calcium (CAC) detected with electron-beam computed tomography (CT) in patients with low CAC scores. Two 40-section, 3-mm-collimation, electrocardiographically gated electron-beam CT examinations of the heart were performed in each patient. Fifty patients with average scores between 2 and 100, as determined with the conventional scoring algorithm, were selected. The modified conventional scoring algorithm was compared with two techniques: calculated calcium volume and approximated calcium mass. The percentage difference between scans ranged from 37.2% for the conventional scoring method to 28.2% and 28.4% for volume- and mass-based methods, respectively. Increasing lesion size thresholds does not improve quantitative precision and reduces accuracy in patients with small amounts of CAC. Quantification methods based on calcification volume or mass decrease score variation compared with the conventional scoring method, and increased size threshold does not improve accuracy.