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This article employs fluid equations to analyze muon beams in gases subject to crossed electric and magnetic fields, focusing, in particular, on a scheme proposed by Taqqu [Phys. Rev. Lett. 97, 194801 (2006)], whereby transverse compression of the beam is achieved by creating a density gradient in the gas. A general criterion for maximizing beam compression, derived from first principles, is then applied to determine optimal experimental conditions for μ+ in helium gas. Although the calculations require the input of transport data for (μ+, He), which are generally unavailable, this issue is circumvented by "aliasing" (μ+, He) with (H+, He), for which transport coefficient data are available. [ABSTRACT FROM AUTHOR]

In this series, we outline a strategy for analyzing electrons and muons in gases in crossed electric and magnetic fields using the straightforward transport equations of momentum-transfer theory, plus empirical arguments. The method, which can be carried through from first principles to provide numerical estimates of quantities of experimental interest, offers a straightforward, physically transparent alternative to "off-the-shelf" simulation packages, such as Magboltz and GEANT. In this first article, we show how swarm data for electrons in helium gas subject to an electric field only can be incorporated into the analysis to generate electron swarm properties in helium gas in crossed electric and magnetic fields and to estimate the Lorentz angle in particular. The subsequent articles in the series analyze muons in crossed fields using similar transport theory, though the absence of muon swarm data requires empiricism of quite a different nature. [ABSTRACT FROM AUTHOR]

Here, we present a new approach for obtaining radial distribution functions (RDF) from the electron diffraction data using a regularized weighted sine least-squares spectral analysis. It allows for explicitly transferring the measured experimental uncertainties in the reduced molecular scattering function to the produced RDF. We provide a numerical demonstration, discuss the uncertainties and correlations in the RDFs, and suggest a regularization parameter choice criterion. The approach is also applicable for other diffraction data, e.g., for x-ray or neutron diffraction of liquid samples. [ABSTRACT FROM AUTHOR]

OH* chemiluminescence and emissions of the convergent swirler module and the Venturi swirler module are studied in a single-element lean direct injection combustor. The OH* chemiluminescence images are captured by a CCD camera with an image intensifier, and the emissions are measured by a gas analysis system. The flame of the Venturi swirler module is closer to the inlet plane of the combustor compared to that of the convergent swirler module. At the equivalence ratio (ϕ) of 0.55, 0.65, and 0.75, the EINOx of the convergent swirler module is 1.02 g/kg, 1.44 g/kg, and 1.98 g/kg, and the EICO is 0.32 g/kg, 0.54 g/kg, and 3.65 g/kg separately. The EINOx of the Venturi swirler module is 0.95 g/kg, 1.37 g/kg, and 2.05 g/kg and the EICO is 0.32 g/kg, 0.93 g/kg, and 5.86 g/kg. The NOx emissions of the two swirler modules are similar. But the CO emission of the convergent swirler module is lower at the ϕ of 0.65 and 0.75. The convergent swirler module has an advantage in reducing emissions. In addition, the influence of the swirl number (S) on OH* Chemiluminescence and emissions of the convergent swirler module is studied. At the ϕ of 0.55, the EINOx is between 0.88 g/kg and 1.17 g/kg and the EICO is between 0.13 g/kg and 0.44 g/kg with different S. With the increase of the S, the NOx emission increases and the CO emission decreases. But at the ϕ of 0.65 and 0.75, with the increase of the S, the NOx emission first increases and then decreases and the CO emission first decreases and then increases. [ABSTRACT FROM AUTHOR]

Customer-side piping systems involve low Reynolds number flows with prolonged periods under no-flow conditions. In this research, odorized CH 4 (methane)/H 2 and N 2 (nitrogen)/He (helium) blends are investigated experimentally at variable Reynolds number (0 < Re d < 5200) to determine if component separation occurs and if the presence of H 2 suppresses odorant performance. After prolonged periods under no-flow conditions, all investigated mixtures exhibit varying degrees of component separation. Leak events of odorized CH 4 /H 2 are examined using gas sample analysis. After accounting for gas dilution, leaks of odorized CH 4 /H 2 under no-flow conditions exhibit odorant fade of Tert -Butyl Mercaptan while Methyl Ethyl Sulfide concentrations remain constant. Although odorant fade of Tert -Butyl Mercaptan occurs, measured levels are still approximately 50 times above levels at which the human olfactory sense can either detect or characterize the odorant. For both odorants, suppression due to the presence of H 2 is not observed. • Fully-mixed gas mixtures of methane/hydrogen and nitrogen/helium undergo varying degrees of component separation under no-flow conditions for prolonged periods • Component separation under no-flow conditions is found to be minimal based on both remixing experiments and gas chromatography analysis • Levels of Tert -Butyl Mercaptan show an odorant fade process in odorized methane and hydrogen blends, while levels of Methyl Ethyl Sulfide remain constant • Measured odorant levels in blends up to 70% methane and 30% hydrogen remain significantly higher than detection thresholds of the human olfactory sense [ABSTRACT FROM AUTHOR]

A study has been carried out on the transfer of water and alcohols from aqueous solutions into the gas phase under the action of a discharge with a liquid electrolyte cathode. It has been shown that the coefficient of water transfer from solution depends on the concentration and type of dissolved alcohol. A gas chromatographic analysis of the condensate composition has revealed that the condensate contains both alcohols present in the initial solution and their oxidation products, with the concentration of alcohols in the condensate being significantly lower than in the untreated solution. The dependence of alcohol transfer coefficients on the type of alcohol and some parameters, such as the discharge gap, discharge current, alcohol concentration in the solution, and the presence of air in the discharge chamber, has been examined. [ABSTRACT FROM AUTHOR]

In this study, the outgassing properties of bamboo-derived cellulose nanofibers (CNFs) for space applications were investigated. Outgassing rate tests based on ASTM E1559 were conducted on bamboo, bamboo-derived CNF, and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized CNF (T-CNF). The results showed that CNF emitted only water, while bamboo and T-CNF emitted outgas that is not water and had the peaks at − 40 °C and 55 °C, respectively, in quartz crystal microbalance thermogravimetric gas analysis. These findings reveal that CNFs are promising materials for low-outgassing applications. Moreover, the results indicate that the TEMPO treatment produces outgassing sources into the CNF. • Bamboo-derived CNF is found out to emit only water evaluated by outgassing tests. • Bamboo and TEMPO-oxidized CNF show significant outgassing. • TEMPO treatment introduces outgassing sources into CNF. • Bamboo-derived CNF is promising for space use with excellent outgassing properties. [ABSTRACT FROM AUTHOR]

A novel approach for cost-effective and temporally resolved in-line combustion gas diagnostics based on spontaneous Stokes Raman spectroscopy is presented in this paper. The proposed instrument uses a multipass configuration designed to increase the scattering generation, giving information about gas species concentrations, including H2 and N2 that are not commonly available from analysis with absorption spectroscopy techniques. The system performs calibrated analysis providing both qualitative and quantitative information about the gas composition. Depending on the application, the device can work with spectra integration time from 0.15 s up to 10 s, with a Raman spectrum ranging from the H2 rotational peak at Raman shift of 587 cm−1 up to the H2 vibrational peak at 4156 cm−1, covering all the Raman emissions of major combustion species. The device response was characterized by a working pressure from 0.7 to 7.5 bar. The instrument prototype has been made completely transportable, designed to operate using a gas sampling system, and ready to be operated in relevant industrial in-line environments. [ABSTRACT FROM AUTHOR]

Detecting Clostridium in milk presents a significant challenge for the dairy industry given that traditional methods are time-consuming and not specific for these bacteria. Microbiological techniques are expensive and require qualified personnel. Clostridium, in the form of spores, can withstand pasteurization and revert to its vegetative form during cheese aging. These gas-producing bacteria are known for their production of carbon dioxide and hydrogen, causing the formation of slits, cracks, and irregular eyes in hard and semi-hard cheeses. However, gas analysis in the vial headspace of appropriate culture can be exploited to specifically detect Clostridium presence, since the closest competing bacterial Bacilli produces only carbon dioxide. The aim of this paper is to present a Raman-spectroscopy-based instrument for a rapid, inexpensive identification of Clostridium in milk with a limit of detection of 29 spores/L. The proposed measurement procedure is analog to that routinely used, based on the most probable number method. The Raman-based instrument speeds up the detection of a vial's positivity. A test conducted with Clostridium spores demonstrated its effectiveness in almost halving the time needed for the measurement campaign compared to the traditional method. [ABSTRACT FROM AUTHOR]

As a commonly well-known industrial chemical, phthalates are produced in high volumes to be used in various consumer products (e.g., plasticizers, medical devices, construction materials, and toys) to enhance softness, durability, transparency, and flexibility. Phthalates are generally not chemically bonded to the polymer chain of the plastic in which they are mixed. Thus, they may leach, migrate, or evaporate into indoor/outdoor air, and foodstuffs. In this review, a comprehensive overview of several sample preparation methods coupled with gas chromatography for the analysis of phthalates in various kinds of complex matrices, with a focus on the last 20 years' worth of papers. The review begins by highlighting the environmental significance of phthalate pollution along with the various routes to their exposure to general population. Then, the discussion is extended to cover the pretreatment and extraction techniques for phthalates for their quantitation based on gas chromatographic approach. Finally, the present and future challenges for the detection of phthalates in aqueous and food matrices are discussed. [ABSTRACT FROM AUTHOR]

Chlorination of seawater forms a range of secondary oxidative species – collectively called "chlorine-produced oxidants" (CPOs) – having different biocidal, environmental and ecotoxicological properties. The chemical speciation of these compounds is an important step in attempts to assess the effectiveness of chlorination and the potential impacts of its releases. However, comprehensive determination of CPOs represents a significant analytical challenge for many reasons, including the following: CPO species are numerous, highly reactive, with short-lifetimes, difficult to isolate and generally present at low concentrations in a complex salt matrix. Literature review reveals the development of a wide variety of analytical approaches for analysis of CPOs, either collectively via group parameters or individually. A first category of these approaches was the subject of article II (also including sampling and sample preparation) of a trilogy devoted to the chemical speciation of CPOs in seawater. In this third article – which closes the trilogy – emphasis is placed on chromatographic- and mass spectrometric-based approaches. It reviews more than 80 methods, reported from 1981 to date, and thoroughly discusses their principles and performances. Methodologies involving chemical derivatization of CPOs prior to their analysis by gas or liquid chromatography coupled to mass spectrometry provide the best sensitivities, achieving sub-ppb detection limits for species for which suitable derivatization reagents are available. Online mass spectrometry approaches are attracting increasing interest for their ability to analyze multiple CPO species in real time without extensive sample preparation steps, reaching detection limits of about ppb for less polar oxidants. At the current state of metrological development, neither the methodologies based on chromatography nor those based on online mass spectrometry allow complete speciation of CPOs. Future trends and major challenges related to these approaches are discussed. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study is to develop and optimize a method for evaluating the persistence of residual fragrance after body washing, addressing a significant requirement in the development of personal care products. The main objective is to establish a reliable, sensitive and reproducible analytical technique to assess fragrance longevity on skin post‐use of body wash products. Methods: Headspace solid‐phase microextraction (HS‐SPME) coupled with gas chromatography–mass spectrometry (GC–MS) is used to analyse residual fragrances. We investigate the extraction efficiencies of various SPME fibres and compare different methods for sampling skin‐emitted fragrances, including tape stripping and sealed glass funnels. A controlled body‐washing procedure is implemented to standardize the cleansing process. Results: Our findings indicate that the relative standard deviation for measuring five distinct fragrances is within the range of 3%–14%, highlighting the precision of the method. A notable variance exists in the extraction efficiency of fragrances using different types of SPME fibres, with some exhibiting over a threefold difference. Furthermore, the glass funnel method for fragrance collection demonstrates an 11.7 times greater sensitivity to galaxolide than that of the tape‐stripping method. Residual fragrances with base notes as the main components can be detected on the skin up to 24 h after body washing. Conclusion: The optimized method for residual fragrance evaluation developed in this study offers a robust tool for analysing fragrance components persisting on the skin for up to 24 h post‐wash. This advancement facilitates a deeper understanding of fragrance longevity in personal care products, enabling comparative analyses between different products. [ABSTRACT FROM AUTHOR]

Background: Since 1989, FIFA has used a battery of physical tests to evaluate the fitness levels of soccer referees. However, to date, there is no consensus, and the specificity, reliability, and validity of these tests remain a matter of debate. Aims: Develop a new specific field test to assess the fitness level of field soccer referees. Methods: Oxygen consumption (VO2) of 12 male professional field soccer referees was directly measured with a portable metabolic gas analysis system during two incremental protocols: treadmill and a Yo-Yo IE2 adapted in-field test (ADYYIE2). Physiological performance was measured by GPS methodology. Results: The distance covered until exhaustion between the protocols was 2098.61 ± 425.72 and 1025.83 ± 304.89 m, for the treadmill and ADYYIE2 protocols, respectively (p < 0.0001). Time to exhaustion during the treadmill protocol was also significantly higher than that observed in the ADYYIE2 test. The VO2peak measured were not significantly different between the protocols. A significant correlation was obtained between the total distance covered during the ADYYIE2 test and VO2peak, but the relationship between the treadmill protocol and VO2peak was not significant. The VO2peak values obtained during the ADYYIE2 test showed a correlation of very large magnitude with the total distance covered and the amount of high intensity activities recorded during an official match. Therefore, these match activities are related to the physical capacity of the referee evaluated by the test proposed. Conclusions: This study is the first to direct assessment the VO2peak during a Yo-Yo test performance (via portable spirometry), and the main finding was that direction change influences the physiological parameters assessed during physical tests. [ABSTRACT FROM AUTHOR]

The QuEChERS extraction method was extensively modified and validated for effective screening of drugs and pesticides in diverse biological matrices, such as blood, urine, liver, and stomach contents. This method involved the extraction of 2 mL biological samples using acetonitrile as the solvent. To eliminate interferences, particularly lipids, a novel sorbent comprising a combination of C18 and specialized polymers called EMR-L (Enhanced Matrix Removal-Lipid) was employed. The extracted samples were then subjected to analysis using GCMS with a DB-5 MS column. The validation study encompassed various parameters including carryover, limit of detection (LOD), and interference investigation. LOD of analytes were ranged from 0.5 to 1.0 µg/mL. The validated method is known for its simplicity and effectiveness in conducting systemic toxicological analysis, covering a wide range of acidic, neutral, and basic analytes. Moreover, this method has the potential to detect additional drugs and pesticides not included in the validation study, provided they are compatible with gas chromatographic analysis. The modified method was successfully applied to real case samples, proving to be a valuable tool for systemic toxicological analysis. Its versatility allows for the screening of acidic, neutral, and basic drugs and pesticides in various biological matrices. [ABSTRACT FROM AUTHOR]

Gases can form within the insulation system for various reasons while a transformer is in operation. If these gases are not promptly and properly managed, they can negatively impact the transformer's performance. Using the dissolved gas analysis (DGA) method to identify and assess the type and quantity of dissolved gases in transformer oil can uncover potential issues within the transformer. This information is crucial for guiding preventive maintenance and necessary repairs. Dissolved gas analysis testing was conducted by extracting transformer oil samples to identify signs of disturbances in the transformer based on the dissolved gas content. This research was conducted at the Paiton plant operations and maintenance services division. The condition of transformers was assessed by analyzing dissolved gases using the Rogers ratio method. Results indicate that the transformer at Paiton 9 is in good condition but overheating has occurred and requires treatment. Conversely, the transformers at Paiton 1 and 2 are in poor condition, showing signs of electrical faults and excessive heat. Despite several attempts to add inhibitors and conduct frequent testing, the transformers remained in poor condition, necessitating their replacement or repair. [ABSTRACT FROM AUTHOR]

The main purpose of this study was to optimize the methods for determining methane emission in a continuously flooded (CF) and an alternately wetted and dried rice system. A field experiment was conducted at Block B1, Pili Drive, Los Baños, Laguna for one cropping season to evaluate the CH4 emission in both FP and AWD treatment plots. Fertilizer application rates were similar across treatments and were based on the recommended rate. Gas sampling was done weekly at 0, 15, and 30 - minute intervals and gas samples were analyzed using a gas chromatograph equipped with a flame-ionization detector (FID). Results showed that FP plots emitted methane at 15.07 to 459.14 mg CH4 day-1 m-2, which was higher than those produced in AWD plots which ranged from 1.68 to 36.26 mg CH4 day-1 m-2 throughout the cropping period. In both treatments, a decreasing trend in methane emission was observed which was attributed to the depleting carbon source of methanotrophs where methane was utilized rather than produced at an unfavorable redox potential for methane production. Global warming potential (GWP) of 7.000 kg CO2-eq and 1.350 kg CO2-eq was contributed by FP and AWD treatments, respectively. Overall, CH4 emission was reduced by 80-85% when AWD was employed without having a yield compromise. The result of this pilot study is limited to a 1.300 m2 field area but it showed a significant comparison between the two water management strategies in rice systems. Also, the learnings in this study will be used further for landscape greenhouse gas measurements in major rice-producing areas in the Philippines and ultimately will contribute to the carbon footprint assessment of rice cultivation. [ABSTRACT FROM AUTHOR]

Sensitivity analysis enables the identification of influential parameters and the optimisation of model composition. Such methods have not previously been applied systematically to models describing hyperpolarised 129Xe gas exchange in the lung. Here, we evaluate the current 129Xe gas exchange models to assess their precision for identifying alterations in pulmonary vascular function and lung microstructure. We assess sensitivity using established univariate methods and scatter plots for parameter interactions. We apply them to the model described by Patz et al and the Model of Xenon Exchange (MOXE), examining their ability to measure: i) importance (rank), ii) temporal dependence and iii) interaction effects of each parameter across healthy and diseased ranges. The univariate methods and scatter plot analyses demonstrate consistently similar results for the importance of parameters common to both models evaluated. Alveolar surface area to volume ratio is identified as the parameter to which model signals are most sensitive. The alveolar‐capillary barrier thickness is identified as a low‐sensitivity parameter for the MOXE model. An acquisition window of at least 200 ms effectively demonstrates model sensitivity to most parameters. Scatter plots reveal interaction effects in both models, impacting output variability and sensitivity. Our sensitivity analysis ranks the parameters within the model described by Patz et al and within the MOXE model. The MOXE model shows low sensitivity to alveolar‐capillary barrier thickness, highlighting the need for designing acquisition protocols optimised for the measurement of this parameter. The presence of parameter interaction effects highlights the requirement for care in interpreting model outputs. [ABSTRACT FROM AUTHOR]

This study investigates the delubrication, reduction, and decarburization processes of powder metallurgical steel alloys (CrM, CrL, AHC, Mo85, SintD 35) and an unalloyed steel during sintering in a pure hydrogen atmosphere. Utilizing in-situ FTIR gas phase analysis, components with ethylenebisstearamide (EBS) as a lubricant are analyzed. EBS decomposition in steel components yields CO, CO2, H2O, and CH4, with dominant CH groups observed in the 230 °C to 480 °C range. In the temperature range between 750 °C and 850 °C, where CO formation is expected due to the reduction of surface iron oxides, CH4 is present instead, indicating that an "internal getter effect" also occurs in pre-alloyed powders. In addition, with high carbon activity, the reduction of internal iron oxides and the reduction of chromium oxides also trigger an internal getter effect. Depending on the carbon potential, these processes cause a considerable reduction in the carbon content of the powder metallurgical components. The study therefore shows that the decarburization of powder metallurgical components during the heat treatment phases prior to sintering in a 100 pct hydrogen atmosphere is less due to the mechanism of delubrication, but rather to mechanisms of carbothermal reduction. [ABSTRACT FROM AUTHOR]

Real‐time monitoring of spoilage/freshness of perishable food products using intelligent indicators under commercial packaging conditions is of interest. Thus, this study is aimed at fabricating intelligent indicators to determine the possibility of using developed indicators to monitor fish freshness packaged under real packaging conditions. Bromothymol blue (BTB) dye and two different binders (methyl cellulose [MC] and cellulose acetate [CA]) were used to fabricate four different indicators, with the addition of NaOH for carbon dioxide (CO2) or HCl for total volatile basic nitrogen (TVB‐N) sensitive indicators. The colour of produced indicators was observed during 10‐day simulations using CO2 and trimethyl amine (TMA) at different concentrations (0%–30% for both) at 4°C. BTB‐MC‐NaOH changed from blue to green at 15% CO2, while BTB‐CA‐NaOH changed from green to yellow at 25% CO2. Both BTB‐MC‐HCl and BTB‐CA‐HCl indicators changed colour completely at 15% TMA (BTB‐MC‐HCl from yellow to navy and BTB‐CA‐HCl from yellow to green). Indicators were used to monitor the spoilage of Atlantic bonito for 10 days at 4°C under two different modified atmosphere packaging (MAP) conditions (30% CO2, 70% nitrogen (N2) and 100% N2). Headspace gas analysis, pH, TVB‐N, TMA, microbiology, sensory and colour analyses were conducted. For 30% CO2 70% N2, CO2‐sensitive indicators showed a colour change responding to CO2 used, while TVB‐N sensitive indicators showed no visible colour change since the TMA level in packages did not reach the spoilage threshold. Colour transition was also not clear in any of indicators under 100% N2‐packaging, since neither colour‐changing range of CO2 or TMA was reached. [ABSTRACT FROM AUTHOR]

The failure of mineral oil‐filled transformers has been involved in numerous fire and explosion incidents during operations. The power industry has developed online dissolved gas analysis (DGA) monitoring systems capable of diagnosing transformer faults continuously. This study has established new test procedures and pass/fail criteria to evaluate the accuracy of online H2 monitors, resulting in the creation of a new approval standard. [ABSTRACT FROM AUTHOR]

Abstract2-((1H-Benzo[d]imdazole-2yl) thio)1(4-chlorophenyl) ethan-1-one modified chitosan (BIMC) was applied as an effective inhibitor for the corrosion of C-steel in 1.0 M HCl solution. Various techniques such as gravimetry, H2 evolution, electrochemical potentiodynamic, PD, and impedance spectroscopy were included. The data indicated that the rate of metal dissolution is lowered with more additions of the BIMC compound and increased with temperature. EIS measurements proved that the presence of the BIMC compound in the acidic media reduces the values of the double layer capacitance, Cdl, and raises the charge transfer resistance, Rct explaining the formation of the passive layer of the BIMC inhibitor through an adsorption process. PD measurements proved that the BIMC compound is conducted as a mixed-kind inhibitor. The protection efficacy, η %, increased with more additions of the BIMC and was reduced with temperature. The η % takes higher values to reach 93% at 5 mg/L, at 25 °C. The protection process is controlled by the adsorption of the BIMC molecules on the metallic surface obeying Langmuir’s pattern. The computed ΔGads° values were found to depend on the temperature and varied between −31.42 and −34.62 kJ/mol. Such a conclusion could be attributed to the mixed adsorption mechanism. The higher values of Kads could confirm the stability of the adsorption process. The lowering in the Kads values with T can be related to the desorption of some BIMC molecules from the electrode surface. Theoretical quantum computation confirmed the adsorption of the BIMC compound in concurrence with the data obtained by practical techniques. [ABSTRACT FROM AUTHOR]

The "gas fee" paid for inclusion in the blockchain is analyzed in two parts. First, we consider how "effort" in terms of resources required to process and store a transaction turns into a "gas limit," which, through a fee comprised of the "base" and "priority fee" in the current version of Ethereum, is converted into the cost paid by the user. We adhere closely to the Ethereum protocol to simplify the analysis and to constrain the design choices when considering "multidimensional gas." Second, we assume that the "gas" price is given deus ex machina by a fractional Ornstein–Uhlenbeck process and evaluate various derivatives. These contracts can, for example, mitigate gas cost volatility. The ability to price and trade "forwards" in addition to the existing "spot" inclusion into the blockchain could enable users to hedge against future cost fluctuations. Overall, this article offers a comprehensive analysis of gas fee dynamics on the Ethereum blockchain, integrating supply-side constraints with demand-side modelling to enhance the predictability and stability of transaction costs. [ABSTRACT FROM AUTHOR]

Accurate analysis of pesticide residues in such a complex matrix as cannabis is a challenging task. The aim of this study was to find an optimal way of removing abundant matrix co‐extracts from Quick, Easy, Cheap, Effective, Rugged, and Safe extract prior to its analysis by gas chromatography‐tandem mass spectrometry (GC‐MS/MS). Out of the seven procedures tested, clean‐up with Supel QuE Verde sorbent provided the most satisfactory performance characteristics for 277 targeted pesticides, which is the highest number of these analytes ever investigated within a GC‐MS‐based study focused on cannabis. The criteria set in the SANTE/11312/2021 V2 document were considered to assess the results obtained within the method validation. Recoveries in the range of 70%–120% with repeatability ≤20% were obtained for 219 and 114 pesticides at spiking levels of 0.1 and 0.01 mg/kg, respectively. For a deeper insight into the function of tested sorbents and to understand the effects of interfering matrix co‐extracts, the two‐dimensional GC coupled with the time‐of‐flight MS method was employed for the analysis of all purified extracts. Co‐eluting major phytocannabinoids and free fatty acids were shown to be responsible for high "chemical noise", increasing limits of quantification of pesticides at respective retention times. Since cannabis chemotypes fairly differ in phytocannabinoid content, the matrix effects, thus performance characteristics, may vary. Under such conditions, validation is recommended for different cannabis chemotypes. [ABSTRACT FROM AUTHOR]

The thermal behavior of the antiviral drug indinavir sulfate was investigated by TG/DTG, TG/DTA, DSC, hot stage microscopy and TG-FTIR. TG curve indicated the loss of water followed by four decomposition steps after melting at 150 °C. DSC curves on heat–cool–heat mode showed no evidence of recrystallization of the drug on cooling. From thermoanalytical techniques, mass spectrometry and characterization of the evolved gases, it was suggested that the decomposition starts with the release of water, carbon dioxide, isocyanic acid, ammonia, 2-indanol and 2-pentanol. At higher temperatures, the release of water, isocyanic acid, carbon dioxide, ammonia and 2-pentanol was observed. In addition, carbonyl sulfide was also present as a gaseous product of thermal decomposition and detected by the first time. Mass spectra of the sample heated up to 150 °C confirmed the release of 2-indanol and ammonia just after melting. Finally, a complete description of the thermal behavior of the drug is presented based on all these results. [ABSTRACT FROM AUTHOR]

Hydroxylamine nitrate (HAN) is a new type of high-energy oxidant used in controllable propulsion. The present study explores the reaction mechanism of HAN using density functional theory and constructs reaction mechanism diagrams to understand the mechanism of small-molecule gas formation during the thermal decomposition of HAN. Based on transition state theory, the half-life of each reaction is calculated under standard conditions and the kinetic parameters of each reaction are scanned across the temperature range 298.15–1200 K. The research revealed a vast half-life time scale forreaction of NO generation, NO 2 generation, NO+NO 2 generation, N 2 O generation and N 2 generation process, meaning thatthese reaction can not occur. The half-life of RDS5 is very short. However, the reaction is also limited by the concentration of the reactant HNO. However, increasing the temperature rapidly decreases the reaction half-life and the reaction can easily proceed. Taking 300 s as the easily reactive boundary point, the cut-off points of the rate-determining steps of Processes 1 (NO generation), 2 (NO 2 generation), 3 (NO + NO 2 generation), 4 and 5 (N 2 O generation) and 6 (N 2 generation) are 466 K, 468 K, 576 K, 587 K and 402 K, respectively. The calculated reaction mechanism revealed two isomeric transformations of HNO 2 and H 2 N 2 O 2 and three isomeric transformations of H 2 N 2 O. Both HNO 2 and H 2 N 2 O 2 are transformed via H-atom transfer, while H 2 N 2 O is transformed either by H-atom transfer or intramolecular rotation. As the formation reaction of NO 2 does not have the lowest free energy, the NO 2 product is easily converted to other products. When NO 2 coexists with NO, it is also easily converted to the stable products N 2 O, N 2 and NH 3. [ABSTRACT FROM AUTHOR]

Membrane separation processes play a crucial role in gas separation applications, with the need for ongoing development to fulfill new needs for today's challenges. For this purpose, novel 2D nanomaterials are progressively showing promise over conventional polymer‐based membrane material, exhibiting excellent molecular transport properties. Beyond the 2D materials already studied in this field, this article presents the first gas separation performances of vanadium pentoxide membrane. Brand new in gas separation topic, 2D van der Waals nanoribbons of V2O5 are successfully synthesized and layered on an anodic aluminum oxide substrate. Gas permeation analysis of He, N2, and CO2 are performed on various membranes made from different quantities of the nanomaterial. Gas permeance results suggest a deviation from an expected Knudsen diffusion mechanism of the V2O5‐based membrane for He separation. The ideal selectivities of He/N2 and He/CO2 are compared to Robeson's upper bound for polymeric membranes. V2O5 membranes, prepared with the highest V2O5 quantity, exceeded the upper bound from 2008 for He/N2 and 2019 (the most recent) for He/CO2, demonstrating the interesting potential of V2O5 2D materials for gas separation. [ABSTRACT FROM AUTHOR]

This study investigates the adsorption characteristics of the pristine MoTe2 monolayer and the metal atom (Co, V, W, Zr)-modified MoTe2 monolayer on the hazardous gases CO, CH3CHO, and C6H6 based on the density functional theory. The adsorption mechanism was studied from the perspectives of molecular density differences, band structures, molecular orbitals, and the density of states. Research analysis showed that the changes in conductivity caused by the adsorption of different gases on the substrate were significantly different, which can be used to prepare gas sensing materials with selective sensitivity for CO, CH3CHO, and C6H6. This study lays a reliable theoretical foundation for the gas sensing analysis of toxic and hazardous gases using metal atom-modified MoTe2 materials. [ABSTRACT FROM AUTHOR]

Clarifying the response relationship between soil radon gas anomalies and active fault tectonic geomorphology, and to explore a rapid prediction method for concealed fractures, soil radon gas measurements and unmanned aerial vehicle micro-geomorphic scanning were carried out in the basin section of the Aba South Fault in western Sichuan. The areas of radon gas anomalies and tectonic features formed by fracture activities are highly consistent with the distribution areas of hidden fractures. It is concluded that the combination of soil radon gas measurements and tectonic geomorphologic analysis can rapidly and accurately predict hidden fractures covered by Quaternary sediments. [ABSTRACT FROM AUTHOR]

The biological removal of a mixture of soil contaminants, namely, hydrocarbons, is not equally efficient for each compound. Some pollutants can be metabolized by the microbial consortium but also generated again as by-products from the removal of others. At the end of the runs, notwithstanding the high integral removal, single compounds can still be present with a relevant concentration. This paper presents the results achieved in a study of the aerobic degradation of diesel oil in three mesocosms carried out for several months with the same operative conditions. They differed in biological management: Natural Attenuation (NA), Biostimulated without inoculation (BS), and Biostimulated with Inoculation (BS + IN). At the end of the runs, the pollution removal was calculated by measuring the residual diesel oil, both as an average in the total amount of soil and only at the bottom of each column. The overall removal was around 2%, 66%, and 72% for NA, BS and BS + IN, reduced to 0%, 48%, and 47%, respectively, if measured only at the bottom. For the biostimulated mesocosms, the speciation of the hydrocarbons was carried out to assess their concentration. The findings evidence the need to delve deeper into this issue and assess the speciation of contaminants. [ABSTRACT FROM AUTHOR]

This review presents the latest research on chromatography-based metabolomics for bioorganic research of honey, considering targeted, suspect, and untargeted metabolomics involving metabolite profiling and metabolite fingerprinting. These approaches give an insight into the metabolic diversity of different honey varieties and reveal different classes of organic compounds in the metabolic profiles, among which, key metabolites such as biomarkers and bioactive compounds can be highlighted. Chromatography-based metabolomics strategies have significantly impacted different aspects of bioorganic research, including primary areas such as botanical origins, honey origin traceability, entomological origins, and honey maturity. Through the use of different tools for complex data analysis, these strategies contribute to the detection, assessment, and/or correlation of different honey parameters and attributes. Bioorganic research is mainly focused on phytochemicals and their transformation, but the chemical changes that can occur during the different stages of honey formation remain a challenge. Furthermore, the latest user- and environmentally friendly sample preparation methods and technologies as well as future perspectives and the role of chromatography-based metabolomic strategies in honey characterization are discussed. The objective of this review is to summarize the latest metabolomics strategies contributing to bioorganic research onf honey, with emphasis on the (i) metabolite analysis by gas and liquid chromatography techniques; (ii) key metabolites in the obtained metabolic profiles; (iii) formation and accumulation of biogenic volatile and non-volatile markers; (iv) sample preparation procedures; (v) data analysis, including software and databases; and (vi) conclusions and future perspectives. For the present review, the literature search strategy was based on the PRISMA guidelines and focused on studies published between 2019 and 2024. This review outlines the importance of metabolomics strategies for potential innovations in characterizing honey and unlocking its full bioorganic potential. [ABSTRACT FROM AUTHOR]

The traditionally produced pea paste (PP) suffers from suboptimal flavor and inferior quality. Based on the study of single-strain fermentation, we further selected S. cerevisiae, Z. rouxii, and L. paracasei for PP production by dual-strain fermentation (SL, ZL). By combining intelligent sensory technology, gas chromatography–mass spectrometry (GC-MS), and ultra-high-performance liquid chromatography (UPLC) technology, the aroma and taste characteristics of SL- and ZL-fermented PP were compared. The electronic nose and tongue revealed the differences in the aroma and taste characteristics between the two fermentation methods for fermenting PP. In total, 74 volatile compounds (VOCs) in PP were identified through GC-MS analysis. In contrast, the number of VOCs and the concentrations of alcohols and acids compounds in SL were higher than in ZL. Among the 15 VOCs that were common to both and had significant differences, the concentrations of ethanol, 1-pentanol, and ethyl acetate were higher in SL. For taste characteristics, SL demonstrated significantly higher levels of sweet and bitter amino acids, as well as tartaric acid, compared with ZL. These results elucidate the flavor differences of dual-strain fermented PP, providing a theoretical basis for selecting suitable strains for fermenting PP. [ABSTRACT FROM AUTHOR]

To explore the causes and influencing factors of wind flow oscillations in high-temperature inclined aisles of deep wells under parallel upward ventilation, this study conducts a comprehensive investigation using theoretical analysis and numerical simulations. Based on the kinetic analysis of gas flow, a discriminant formula for wind flow reversal in the side branch is derived. Further analysis identifies initial wind speed and branch length as key factors influencing the reversal. Both gas pressure and thermal pressure contribute to wind flow reversal in the side branch, and the opposing directions of these pressures cause high-temperature gas to periodically flow between the two branches, resulting in wind flow oscillations. A higher initial wind speed can effectively reduce the oscillation amplitude due to increased initial kinetic energy and a larger pressure difference, but it does not extend the oscillation duration. Increasing the branch length can suppress wind flow oscillations by increasing airflow frictional resistance and damping. [ABSTRACT FROM AUTHOR]

Despite over 60 years of helium development in the Sichuan Basin, the mechanism of helium enrichment remains poorly understood. Helium-rich gas is primarily found as gas composition analysis in the fields. This study explores the relationship between helium distribution and two regional shale formations (the Qiongzhusi and Wufeng-Longmaxi formation), basing on the spatial distribution of these shales, structural profiles, and reported helium concentrations. Our findings indicate a typical trend of helium enrichment within the Sichuan Basin, where helium concentrations generally increase from the basin margins toward its center. The R/Ra ratios in the natural gas are consistently below 0.1, indicating that the helium mainly originates from the granite basement. The Wufeng-Longmaxi Formation is absent from central to western parts of this basin. The hydrocarbon generation intensity of this shale is 3,627.26 m³/m2, which is 25,896.7 times greater than its helium generation intensity (0.14 m³/m2). Its helium capture time is short (237 Ma). There is no obvious correlation between the distribution of helium concentration and Wufeng-Longmaxi shale. The Qiongzhusi shale extends across the entire Sichuan Basin. Its hydrocarbon generation intensity is approximately 57 m³/m2, which is 267.4 times greater than its helium generation intensity (0.27 m³/m2). Beneath this shale, the Pre-Sinian granite exhibits a helium generation intensity exceeding 0.51 m³/m2, acting as the primary helium source rock in the basin. The helium capture time of Qiongzhusi shale is 435 Ma. Helium concentration increases as the burial depth of the Qiongzhusi shale decreases, and helium becomes isotopically lighter in the direction of fluid potential drop. This indicates that helium enrichment in the Sichuan Basin is predominantly influenced by the Qiongzhusi shale. From maximum burial depth to present, helium solubility in water has decreased by approximately 63.6% and 54.3% in the Wufeng-Longmaxi and Qiongzhusi shale respectively, suggesting that uplift processes contributed to helium degassing into gas reservoirs. The regional shale influenced the long-distance migration of helium, although faults can alter this pathway. Faults may either promote helium accumulation in shallow gas fields, such as the Jinqiu gas field, or lead to helium loss, as observed in the southeastern region of the Sichuan Basin. [ABSTRACT FROM AUTHOR]

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The reduction of CO2 has become a key role in reducing greenhouse gas emissions in efforts to search for long‐term responses to climate change. We report a couple of CO2‐reducing molecular catalysts based on earth‐abundant copper complexes. These are [Cu(DPA)(PyNAP)] (1) and [Cu(DPA)(PyQl)] (2) (where, DPA=pyridine‐2,6‐dicarboxylate, PyNAP=2‐(pyridin‐2‐yl)‐1,8‐naphthyridine, and PyQl=2‐(pyridin‐2‐yl)quinoline). The copper metal‐catalysed 2‐electron reduction of CO2 to CO in the presence of 2‐protons is challenging. These catalysts exhibit the production of CO gas in DMF/water mixtures, achieving an impressive Faradaic efficiency of 84 % and 72 % for complex 1 and 2 at −1.7 V vs. SCE, respectively, for selective CO2 reduction. The production of H2 due to 2H++2e− was also observed as a byproduct through the competitive proton reduction reaction. This was cross‐verified by online gas and mass analysis. A comprehensive series of electrochemical experiments have substantiated the homogeneous behaviour exhibited by these molecular electrocatalysts. Our investigations confirmed the stability of the electrocatalysts under the electrocatalytic conditions. The mechanistic pathways were proposed to work with the EECC and ECEC (E: electrochemical and C: chemical) mechanisms. A CO2 insertion into an in‐situ generated hydride from the Cu‐center generates CO through the favourable path. This critical path kinetically favors excess Faradaic efficiency in 1 than 2, which agrees with the computational investigation. [ABSTRACT FROM AUTHOR]

Transparent alumina ceramics produced by pulsed electric current sintering (PECS) include black dots, which can be observed with the naked eye. These black dots have porous structures caused by the aggregates in the raw powder. In order to investigate the detailed mechanism of black dot formation, transparent alumina ceramics were prepared by sintering α-alumina granules to produce large pseudo-aggregates and introducing them into α-alumina powder for PECS. Macroscopic black dots were formed in the sample. Characteristic Raman peaks of graphite were detected in porous parts of these macroscopic black dots. Analysis of gas phases generated from graphite sheets for PECS suspected to be involved in carbon contamination showed CO and CO 2 generation. In thermodynamic calculations on carbon activity during PECS, gas phase including CO and CO 2 generated from the hot graphite mold/sheet permeates the porous part of the cold sample, and the carbon activity of gases including CO and CO 2 on the porous surface theoretically exceeds unity. Then, CO is adsorbed and decomposed on the porous surface, resulting in carbon contamination. The formation of macroscopic black dots is caused by carbon deposition in agglomerates of the raw powder from CO generated by graphite sheets during PECS. [ABSTRACT FROM AUTHOR]

A tubular proton‐conducting fuel cell, anode‐supported, was fabricated using dip‐coating and followed by the co‐sintering of anode and electrolyte at 1500°C. The electrolyte and anode thicknesses are respectively 6 and 500 µm. The outer diameter of the tubular cell is 5.8 mm, featuring an anode porosity of 23%. Ammonia‐fueled single cell with Ru‐catalyzed internal cracking reactor is operated at various temperatures from 400°C to 600°C. Calculation results indicate that double‐ring current collection is an efficient current‐collecting mode. At 600°C, the device exhibited a high open‐circuit voltage of 1.02 V and a peak power density of 216 mW cm−2, with a total active area of 2.28 cm2. Exhaust gas analysis reveals a 99.13% ammonia decomposition rate at 600°C. [ABSTRACT FROM AUTHOR]

The coupling effects of clamping pressure and catalyst distribution are comprehensively considered to improve proton exchange membrane fuel cell (PEMFC) performance. Numerical models were constructed to study the performance changes and the corresponding internal states of PEMFC under different clamping pressures. Since the increased clamping pressure reduces the uniformity of current density, non-uniform designs with decreased catalyst loading under channel and increased catalyst loading under rib are proposed for performance improvement. A weighted objective function considering current density magnitude and uniformity was constructed, and the performances of different catalyst loading distributions were analyzed. Compared to the uniform distribution, the optimized distribution with a variation of −15% and 15% under channel and rib had the maximum objective function value of 17.24%. The deformation analysis of the gas diffusion layer and optimization of catalyst loading distribution based on deformation analysis provided a reference for the assembly of PEMFC and the production of MEA. [ABSTRACT FROM AUTHOR]

This paper explores an application of 3D printing technology on the food industry. Since its inception in the 1980s, 3D printing has experienced a huge rise in popularity. This study uses cost-effective, flexible, and sustainable components that enable specific features of certain gas chromatography. This study aims to optimize the process of gas detection using a 3D printed separation column and the MiCS-6814 sensor. The principle of the entire device is based on the idea of utilizing a simple capillary chromatographic column manufactured by 3D printing for the separation of samples into components prior to their measurement using inexpensive chemiresistive sensors. An optimization of a system with a 3D printed PLA block containing a capillary, a mixing chamber, and a measuring chamber with a MiCS-6814 sensor was performed. The optimization distributed the sensor output signal in the time domain so that it was possible to distinguish the peak for the two most common alcohols, ethanol and methanol. The paper further describes some optimization types and their possibilities. [ABSTRACT FROM AUTHOR]

Phospholipids are the main building components of cell membranes and are also used for cell signaling and as energy storages. Cancer cells alter their lipid metabolism, which ultimately leads to an increase in phospholipids in cancer tissue. Surgical energy instruments use electrical or vibrational energy to heat tissues, which causes intra- and extracellular water to expand rapidly and degrade cell structures, bursting the cells, which causes the formation of a tissue aerosol or smoke depending on the amount of energy used. This gas phase analyte can then be analyzed via gas analysis methods. Differential mobility spectrometry (DMS) is a method that can be used to differentiate malignant tissue from benign tissues in real time via the analysis of surgical smoke produced by energy instruments. Previously, the DMS identification of cancer tissue was based on a 'black box method' by differentiating the 2D dispersion plots of samples. This study sets out to find datapoints from the DMS dispersion plots that represent relevant target molecules. We studied the ability of DMS to differentiate three subclasses of phospholipids (phosphatidylcholine, phosphatidylinositol, and phosphatidylethanolamine) from a control sample using a bovine skeletal muscle matrix with a 5 mg addition of each phospholipid subclass to the sample matrix. We trained binary classifiers using linear discriminant analysis (LDA) and support vector machines (SVM) for sample classification. We were able to identify phosphatidylcholine, -inositol, and -ethanolamine with SVM binary classification accuracies of 91%, 73%, and 66% and with LDA binary classification accuracies of 82%, 74%, and 72%, respectively. Phosphatidylcholine was detected with a reliable classification accuracy, but ion separation setups should be adjusted in future studies to reliably detect other relevant phospholipids such as phosphatidylinositol and phosphatidylethanolamine and improve DMS as a microanalysis method and identify other phospholipids relevant to cancer tissue. [ABSTRACT FROM AUTHOR]

A simple, rapid, and sensitive procedure is developed for the determination of hydroxylated polycyclic aromatic hydrocarbons (2-hydroxynaphthalene, 2-hydroxyfluorene, 9-hydroxyphenanthrene, 3-hydroxyphenanthrene, 2-hydroxyphenanthrene, 1-hydroxypyrene, and 6-hydroxychrysene) in urine by gas chromatography–mass spectrometry. Sample preparation is based on dispersive liquid–liquid microextraction with trichloromethane in an acidic medium. Derivatization is carried out in a heated injector port using the reagent N,O-bistrimethylsilyltrifluoroacetamide. The type of dispersing solvent is experimentally selected and the optimal ratio of the following factors, i.e., pH value, volume of dispersing solvent, and extraction time, is found using a three-factor experiment. A high-temperature capillary column NT-8 is used in a temperature gradient mode for analysis by gas chromatography–mass spectrometry. The linearity range of the calibration function is found to be 0.5–100 ng/mL. The developed procedure for determining hydroxylated PAH in urine is tested on urine samples from aluminum production workers. [ABSTRACT FROM AUTHOR]

A technology is developed for manufacturing planar microfluidic chips (MFCs) based on Silgard 8040, encompassing template fabrication, mold production, sealing, and adsorbent filling. These MFCs, filled with a Porapak-Q adsorbent, facilitate sample preparation and calibration under uniform conditions, integrating both sample collection and preconcentration stages. Experimental investigations have identified optimal conditions for acetone preconcentration using Silgard 8040-based MFCs, achieving a maximum concentration factor of 43 at adsorption temperature (Tads) of 0°C, desorption temperature (Tdes) of 70°C, adsorption volume (Vads) of 45 mL, and desorption time (tdes) of 1 s. The feasibility of using MFCs for sample collection and preparation, taking into account sample storage time, has been evaluated. The procedure maintains accuracy within 6–10% over 8 h without a necessity for additional drying of the collected samples from exhaled air. [ABSTRACT FROM AUTHOR]

The high-temperature and high-humidity conditions arising from the biochemical degradation of landfill waste result in significant temperature gradients within the landfill cover. The effects of waste temperature on landfill gas transport and microbial aerobic methane oxidation are not fully understood. In this study, a fully coupled theoretical model was developed to simulate the interactions of moisture, heat, and gas transport within a capillary barrier cover. A series of parametric studies were carried out to investigate the influence of the combined effects of temperature gradient, initial soil moisture content, and landfill gas generation rate on methane transport, oxidation, and emissions. The simulated results indicated that increasing waste temperature intensified the temperature gradient, leading to higher surface evaporation rates and variations in methane oxidation efficiencies. Additionally, variations in initial soil moisture content and landfill gas generation rates were found to significantly impact gas migration and methane oxidation in the cover. This study demonstrates the critical role of waste temperature in landfill gas migration within landfill cover systems, providing technical methodologies for the optimized design of soil cover systems. [ABSTRACT FROM AUTHOR]

The subject of the work is the characterization of lightweight aggregates intended for construction using the example of silica-clay raw material from south-eastern Poland (Dylągówka-Zapady deposit). The primary objective of the research is to assess the possibility of managing the accumulated organic waste, including cellulose pulp. This storage is problematic for processing plants and local government bodies and incurs high costs annually. Therefore, based on the patent (Kukułka et al. Method of producing raw meal, dried clay granules, and fired clay granules and the production line of raw meal, dried clay granules, and baked clay granules. Patent RP no P.429284.), an attempt was made to confirm the assumptions of the technology of fired clay granules, which can be used for zootechnical, agricultural, and construction purposes. The presented work assessed the physicochemical transformations in the clay-silica raw material after adding a significant amount of cellulose waste (10%, 20%, and 30%) in the temperature range of 25–1300 °C were assessed. Thermal methods such as thermodilatometry, Hot-Stage Microscopy with image analysis (IA-HSM) and thermal DSC/TG analysis with gas analysis were used for this purpose. Based on the first method, a temperature range was established in which sintering occurs without an apparent effect of densification. Therefore, the range of 850–950 °C was used to obtain fired granules, which were tested as a material for lightweight aggregates. [ABSTRACT FROM AUTHOR]

In this work development of structural and chemical properties of four nanoporous hybrid carbons has been presented. The carbons were synthesized by direct carbonization at 450, 600, 750 and 900 °C of the terpolymeric hybrid precursor composed of methacrylamide, divinylbenzene and trimethoxyvinylsilane and impregnated with sulfanilic acid (SA) as the surface modifier. The conditions of the carbonization process were set on the basis of the thermogravimetric analysis combined with FTIR analysis of the evolved gases (TGA-EGA). The use of SA contributed to the reduction of the carbonization temperature by about 100 °C and resulted in carbons with very uniform and bimodal porosity with the width range of about 1 and 14–28 nm. Spectral (ATR, Raman, XPS) and X-ray diffraction methods used to characterize the resulting carbon products allowed to define the gradual changes taking place in the morphological and chemical structure of the prepared materials. Cyclic and symmetrical structures of silicates species were gradually replaced by amorphous arrangements. At the same time, the increase in the sp2/sp3 carbon ratio from 1 to 65% proved progressive ordering and aromatization of the carbonized polymeric hybrid precursor. Some functional groups (e.g., N-containing) were built into carbon clusters forming pyridinic, pyrrolic and N-graphitic like structures, while others (e.g., carbonyls) were removed from the surface. [ABSTRACT FROM AUTHOR]

This study presents a theoretical analysis of the oblique gas jet impingement process on a liquid surface, elucidating the evolution of the flow field distribution and the influence of jet parameters on cavity shape dynamics. By integrating surface tension effects, the existing Blanks and Chandrasekhara model was refined to develop an advanced predictive model for cavity morphology. The theoretical framework was substantiated through numerical simulations and corroborated with experimental measurements of cavity dimensions, captured using state-of-the-art machine vision technology. The findings reveal a consistent trend in cavity dimension variations: an increase in the cavity surface width with the elevation of the impinging angle from the vertical and an escalation in gas jet velocity. Conversely, a reduction in the impinging angle coupled with an increase in jet velocity leads to a deeper cavity. To enhance the predictive accuracy, the model underwent iterative optimization, incorporating experimental data and accounting for jet parameters. The refined model demonstrated achieved a maximum error of 0.135 mm and a minimum error of 0.03 mm, providing reliable forecasts of cavity depth, which is pivotal for applications in fluid dynamics and related engineering fields. [ABSTRACT FROM AUTHOR]

Trace gas analysis is a key tool for the investigation of man-made environmental pollution as well as for early detection of respiratory diseases. To detect tiny concentrations, sensitive methods such as cavity ring down spectroscopy or plasmonic sensors have been used. Here, we demonstrate the combination of the photoacoustic effect in a classical cell with a novel, rapidly tunable, narrowband fiber-feedback optical parametric oscillator. The high sensitivity of photoacoustic cells and the extremely narrow linewidth as well as the wide and rapid tunability of the fiber-feedback optical parametric oscillator enable a high resolution of the rotational and vibrational bands of molecules in the near-infrared region. Photoacoustic spectra of methane, carbon dioxide, and water at ambient pressure are obtained in a broad spectral range and compared to high-resolution transmission molecular absorption database. In particular, scanning the entire carbon dioxide overtone around 4965 cm−1 at 2000 ppm takes 185 s with a signal-to-noise ratio of 31. This approach enables a wide tunability in the entire near- and mid-infrared spectral region suitable for many environmental and medical applications. [ABSTRACT FROM AUTHOR]

A mixed-metal ternary chalcogenide, cobalt molybdenum telluride (CMT), has been identified as an efficient tri-functional electrocatalyst for seawater splitting, leading to enhanced oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR). The CMT was synthesized by a single step hydrothermal technique. Detailed electrochemical studies of the CMT-modified electrodes showed that CMT has a promising performance for OER in the simulated seawater solutions, exhibiting a small overpotential of 385 mV at 20 mA cm−2, and superior catalyst durability for prolonged period of continuous oxygen evolution. Interestingly, while gas chromatography analysis confirmed the evolution of oxygen in an anodic chamber, it showed that there was no chlorine evolution from these electrodes in alkaline seawater, highlighting the novelty of this catalyst. CMT also displayed remarkable ORR activity in simulated seawater as indicated by its four-electron reduction pathway forming water as the dominant product. One of the primary challenges of seawater splitting is chlorine evolution from the oxidation of dissolved chloride salts. The CMT catalyst successfully and significantly lowers the water oxidation potential, thereby separating the chloride and water oxidation potentials by a larger margin. These results suggest that CMT can function as a highly active tri-functional electrocatalyst with significant stability, making it suitable for clean energy generation and environmental applications using seawater. [ABSTRACT FROM AUTHOR]

The US Food and Drug Administration's (FDA) regulatory oversight over electronic cigarettes (e-cigs) includes access restriction for persons <21 years of age and flavor restrictions for "cartridge-based" products. Despite the restrictions, consumption by US youth perseveres. Studies on youth e-cig use are limited by the reliability and accuracy of self-reports. As an alternative to self-reports, the current study examined nicotine, cannabinoid, and unlabeled e-cigs and other vaping products confiscated from Virginia public schools to characterize trends among students. Findings highlight a shift from JUUL and pod-based products to single use disposable e-cigs following the FDA flavor restrictions on cartridge-based e-cigs. Chemical analysis of e-liquids by gas chromatography–mass spectrometry identified a wide variety of flavorants and an increase in the prevalence of synthetic coolants. Most confiscated products were nicotine salt formulations, but the prevalence of cannabinoid-based vaping products increased. The popularity of flavored disposable e-cigs highlights the need for further restrictions to reduce youth consumption. The increasing use of synthetic coolants instead of menthol may suggest that manufacturers are employing tactics to bypass regulations. Continued youth access to e-cigs and the abundance of cannabinoid-based products is problematic from health and safety perspectives. Continued research incorporating confiscated product analysis can be used to understand youth access to vaping products and evolutions in manufacturing practices. [ABSTRACT FROM AUTHOR]

In this review article, the main techniques for spectroscopic studies of gases in field conditions are considered. The issues related to the study of gas emissions from soils and the determination of their concentrations are analysed. The main types of spectroscopy used in portable devices for soil gas analysis, along with their design features and sampling approaches, are provided. Various studies aimed at optimising the operation of devices for analysing gases emitted from the soil, taking into account agronomic, agrochemical, and ecological specifics, are also presented. The effect of using different types of lasers and reflecting elements on the accuracy of optical measurements and the sensitivity to various substances in the gases is analysed. [ABSTRACT FROM AUTHOR]