2,312 results on '"Gas analysis"'
Search Results
2. Semi-empirical analysis of leptons in gases in crossed electric and magnetic fields. I. Electrons in helium.
- Author
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Hildebrandt, Malte and Robson, Robert E.
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MAGNETIC fields ,ELECTRIC fields ,GAS analysis ,TRANSPORT theory ,ELECTRON gas ,MUONS - Abstract
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]
- Published
- 2023
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3. Regularized weighted sine least-squares spectral analysis for gas electron diffraction data.
- Author
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Tikhonov, Denis S.
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ELECTRON gas ,GAS analysis ,RADIAL distribution function ,ELECTRON diffraction ,NEUTRON diffraction ,REGULARIZATION parameter ,X-ray diffraction - Abstract
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]
- Published
- 2023
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4. Experimental Study on OH* Chemiluminescence and Emissions in the Single-Element Lean Direct Injection Combustor.
- Author
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Li, Qiandong, Suo, Jianqin, Liang, Hongxia, and Wu, Yafeng
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IMAGE intensifiers ,GAS analysis ,FLAME ,INLETS - Abstract
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]
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- 2024
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5. Study of the Transfer of Alcohols from Aqueous Solutions into the Gas Phase by the Action of Liquid Cathode Discharge.
- Author
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Chistolinov, A. V., Yakushin, R. V., Lubin, A. A., and Perfil'eva, A. V.
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CHROMATOGRAPHIC analysis ,WATER transfer ,GAS analysis ,AQUEOUS solutions ,ALCOHOLISM ,GAS condensate reservoirs - Abstract
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]
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- 2024
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6. Assessing transformer health through analysis of dissolved gases in cooling oil.
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Nisworo, Sapto, Hasibuan, Arnawan, Isa, Muzamir, Nrartha, I Made Ari, Jannah, Misbahul, and Muhammad
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GAS analysis ,ELECTRIC transformers ,ELECTRIC power system faults ,INSULATING oils ,ELECTRICAL engineering - Abstract
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]
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- 2024
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7. Methane Emission in a Small-Scale Rice Field under Two Different Water Management Strategies - An Insight for Landscape Level Adjustments.
- Author
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Bunquin, Michelle Anne B., Bugia, Sophia Alelie Cotoner, Buladaco II, Marcial S., and Rocamora, Patrick M.
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METHANE & the environment ,WATER management ,CROPPING systems ,GAS analysis ,GREENHOUSE gases - Abstract
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]
- Published
- 2024
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8. Use of a modified Yo-Yo intermittent endurance level 2 test for evaluation of field soccer referees.
- Author
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Paes, Mauro Ricetti and Fernandez, Ricardo
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SOCCER referees ,PHYSICAL fitness testing ,GAS analysis ,OXYGEN consumption ,TREADMILLS - Abstract
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 (VO
2 ) 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]- Published
- 2024
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9. Sensitivity analysis of models of gas exchange for lung hyperpolarised 129Xe MR.
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Taylor, Yohn, Wilson, Frederick J., Kim, Mina, and Parker, Geoff J. M.
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SCATTER diagrams ,SENSITIVITY analysis ,GAS analysis ,PARAMETER identification ,SURFACE area - Abstract
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]
- Published
- 2024
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10. Enhanced Matrix Removal-Lipid (EMR-L): a novel approach for efficient clean-up in systemic toxicological analysis of drugs and pesticides.
- Author
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Imran, Muhammad, Raza, Asif, Faisal Usman, Hafiz, Mubasher, Muhammad, Din, Najam Ud, Amir Nadeem, Muhammad, Irfan Ashiq, Muhammad, Amjad, Muhammad, and Tahir, Mohammad Ashraf
- Subjects
BIOPESTICIDES ,GASTROINTESTINAL contents ,DRUG analysis ,CHROMATOGRAPHIC analysis ,GAS analysis - Abstract
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 C
18 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]- Published
- 2024
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11. Decarburization and Gas Formation During Sintering of Alloyed PM Steel Components.
- Author
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Quadbeck, Peter, Strauß, Alexander, and Weißgärber, Thomas
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CHROMIUM oxide ,HEAT treatment ,STEEL alloys ,IRON oxides ,GAS analysis - Abstract
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, CO
2 , H2 O, 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]- Published
- 2024
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12. A Review of the Analysis of Phthalates by Gas Chromatography in Aqueous and Food Matrices.
- Author
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Bhogal, Shikha, Grover, Aman, and Mohiuddin, Irshad
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ENDOCRINE disruptors ,COMPLEX matrices ,EXTRACTION techniques ,GAS analysis ,CONSTRUCTION materials ,PHTHALATE esters - Abstract
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]
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- 2024
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13. A Critical Review on Chemical Speciation of Chlorine-Produced Oxidants in Seawater. Part 3: Chromatographic- and Mass Spectrometric-Based Methodologies.
- Author
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Roumiguières, Adrien, Bouchonnet, Stéphane, and Kinani, Said
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LIQUID chromatography-mass spectrometry ,CHEMICAL speciation ,GAS analysis ,LIQUID chromatography ,GAS chromatography ,WATER chlorination - Abstract
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]
- Published
- 2024
- Full Text
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14. Simulation and Validation of a Novel Colorimetric Three‐Layer Intelligent Indicators With Different Binders to Monitor Freshness of Atlantic Bonito (Sarda sarda) Under Two Different Atmospheres.
- Author
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Al Obaidi, Amal, Haskaraca, Guliz, Ayhan, Zehra, and Gultekin, Emre
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CONTROLLED atmosphere packaging ,METHYLCELLULOSE ,FISH spoilage ,GAS analysis ,CARBON dioxide ,CELLULOSE acetate - Abstract
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]
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- 2024
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15. Assessing residual fragrances on skin after body washing: Optimization of an analytical method using solid‐phase microextraction coupled with gas chromatography–mass spectrometry.
- Author
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Goh, Areum, Im, Song Hee, Bae, Jung‐Eun, Choi, Yunsik, Jeon, Jeonghoon, and Im, Sung Hyun
- Subjects
HYGIENE products ,GAS analysis ,ANALYTICAL chemistry ,STANDARD deviations ,SPECTROMETRY - Abstract
Copyright of International Journal of Cosmetic Science is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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- 2024
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16. Testing and approval standard development of online dissolved gas analysis monitors for oil‐filled transformers—Part I hydrogen monitors.
- Author
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Su, Paul, Madan, Rajni, and Purushothaman, Sujit
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GAS analysis ,EXPLOSIONS ,HYDROGEN ,MINERALS ,DIAGNOSIS - Abstract
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]
- Published
- 2024
- Full Text
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17. Gas fees on the Ethereum blockchain: from foundations to derivative valuations.
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Meister, Bernhard K. and Price, Henry C. W.
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GAS dynamics ,TRANSACTION costs ,BROWNIAN motion ,GAS analysis ,PRICES - Abstract
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]
- Published
- 2024
- Full Text
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18. Investigation of the thermal degradation of indinavir sulfate.
- Author
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de Freitas, Jonatha, Rais, Luciano C. R., Ferreira, Ana P. G., and Cavalheiro, Éder T. G.
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ISOCYANIC acid ,GAS analysis ,THERMAL analysis ,CARBON dioxide ,MASS spectrometry - Abstract
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]
- Published
- 2024
- Full Text
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19. Critical Assessment of Clean‐up Procedures Used for Gas Chromatography‐Mass Spectrometry Analysis of Pesticide Residues in Cannabis Inflorescence.
- Author
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Mraz, Petr, Drabova, Lucie, Stupak, Michal, Schusterova, Dana, Kocourek, Vladimir, and Hajslova, Jana
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FREE fatty acids ,PESTICIDE pollution ,MATRIX effect ,GAS analysis ,COMPLEX matrices - Abstract
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]
- Published
- 2024
- Full Text
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20. Gas Permeation through V2O5 Nanoribbons‐Based Membrane.
- Author
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Chevrier, Sarah M., Goh, Kunli, Chuah, Chong Yang, and Gabriel, Jean‐Christophe P.
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GAS separation membranes ,MEMBRANE separation ,VANADIUM pentoxide ,ALUMINUM oxide ,GAS analysis - Abstract
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]
- Published
- 2024
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21. Speciation of the Removed Pollutants in Bioremediation of Hydrocarbon-Contaminated Soil.
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Vergnano, Andrea, Raffa, Carla Maria, Godio, Alberto, and Chiampo, Fulvia
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CHEMICAL speciation ,SOIL pollution ,POTTING soils ,GAS analysis ,GAS chromatography - Abstract
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]
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- 2024
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22. Adsorption Properties of Metal Atom (Co, V, W, Zr)-Modified MoTe 2 for CO, CH 3 CHO, and C 6 H 6 Gases: A DFT Study.
- Author
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Xiao, Weizhong, Wang, Zixuan, and Gui, Yingang
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MOLECULAR orbitals ,DENSITY functional theory ,DENSITY of states ,GAS analysis ,CARBON dioxide - Abstract
This study investigates the adsorption characteristics of the pristine MoTe
2 monolayer and the metal atom (Co, V, W, Zr)-modified MoTe2 monolayer on the hazardous gases CO, CH3 CHO, and C6 H6 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, CH3 CHO, and C6 H6 . 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]- Published
- 2024
- Full Text
- View/download PDF
23. Chromatography-Based Metabolomics as a Tool in Bioorganic Research of Honey.
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Kranjac, Marina, Kuś, Piotr Marek, Prđun, Saša, Odžak, Renata, and Tuberoso, Carlo Ignazio Giovanni
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METABOLOMIC fingerprinting ,HONEY ,DATABASE management software ,METABOLOMICS ,GAS analysis ,SAMPLING (Process) - Abstract
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]
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- 2024
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24. Radon gas and geomorphic analysis as supportive tools for fault exploration: an example from the Aba South Fault basin, western Sichuan.
- Author
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Kang, Guichuan, He, Li, He, Zhengwei, Wu, Xiaoyi, and Guan, Sensen
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TECTONIC landforms ,MORPHOTECTONICS ,GAS analysis ,RADON ,SOILS ,GEOMORPHOLOGY - Abstract
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]
- Published
- 2024
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25. Comparison of Aroma and Taste Profiles Between Two Fermented Pea Pastes Using Intelligent Sensory Analysis and Gas Chromatography–Mass Spectrometry.
- Author
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Wang, Tianyang, Yang, Lian, Tang, Wanting, Yuan, Haibin, Zeng, Chuantao, Dong, Ping, Yi, Yuwen, Deng, Jing, Wu, Huachang, and Guan, Ju
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ELECTRONIC tongues ,ELECTRONIC noses ,TARTARIC acid ,GAS analysis ,LIQUID chromatography - Abstract
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]
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- 2024
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26. Impact of Gas Accumulation on the Stability of Parallel Upward Ventilation in High-Temperature Sloped Shafts of Deep Wells.
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Yuan, Xiaoping, Zhang, Qinghua, and Wang, Zejun
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WIND pressure ,GAS flow ,KINETIC energy ,NUMERICAL analysis ,GAS analysis - Abstract
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]
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- 2024
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27. The relationship between helium-rich gas and regional shale in the Sichuan Basin, Southwest China.
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He, Jianglin, Li, Shuangjian, Zhao, Ankun, Wang, Dong, Gao, Jian, Zhou, Xiaolin, Ahmed, Mohamed S., Wang, Zhenghe, and Zhu, Lixia
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GAS reservoirs ,OIL shales ,NATURAL gas ,GAS analysis ,HELIUM - Abstract
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/m
2 , 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]- Published
- 2024
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28. 白茶饮料高温贮藏期间香气感官评价及挥发性物质分析.
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谢关华, 李博洋, 吕逸凡, 李盼盼, 陈鑫宇, 徐艳群, 龙丹, 洪鹏, and 陈佳
- Subjects
TREND analysis ,KETONES ,GAS analysis ,BENZALDEHYDE ,GAS chromatography/Mass spectrometry (GC-MS) - Abstract
Copyright of Food & Fermentation Industries is the property of Food & Fermentation Industries and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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- 2024
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29. Theoretical Analysis of Landfill Gas Migration in Capillary Barrier Covers Considering Effects of Waste Temperature.
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Wu, Tao, Yang, Huaning, Cheng, Jiankang, Chen, Guannian, Xu, Haoqing, and Zhang, Lei
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GAS migration ,LANDFILL final covers ,SOIL moisture ,TEMPERATURE effect ,LANDFILL gases ,GAS analysis - Abstract
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]
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- 2024
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30. Determination of Hydroxylated Polyaromatic Hydrocarbons in Urine by Gas Chromatography–Mass Spectrometry Using Dispersive Liquid-Liquid Microextraction and Injector-Port Derivatization.
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Alekseenko, A. N., Zhurba, O. M., Merinov, A. V., and Shayakhmetov, S. F.
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POLYCYCLIC aromatic hydrocarbons ,CAPILLARY columns ,URINALYSIS ,GAS analysis ,DERIVATIZATION ,LIQUID-liquid extraction - Abstract
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]
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- 2024
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31. Silagerm 8040-Based Planar Microfluidic Chips for Sampling and Sample Preparation in the Analysis of Gas Media.
- Author
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Margaryan, A. E., Platonov, I. A., Kolesnichenko, I. N., Novikova, E. A., and Karsunkina, A. S.
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AIR analysis ,AIR sampling ,GAS analysis ,DIABETES ,DESORPTION - Abstract
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 (T
ads ) 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]- Published
- 2024
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32. Clamping Pressure and Catalyst Distribution Analyses on PEMFC Performance Improvement.
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Yang, Qinwen, Wang, Xu, and Xiao, Gang
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PROTON exchange membrane fuel cells ,GAS distribution ,CURRENT distribution ,GAS analysis ,CATALYSTS - Abstract
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]
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- 2024
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33. Optimizing Low-Cost Gas Analysis with a 3D Printed Column and MiCS-6814 Sensor for Volatile Compound Detection.
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Skowronkova, Nela, Adamek, Martin, Zvonkova, Magdalena, Matyas, Jiri, Adamkova, Anna, Dlabaja, Stepan, Buran, Martin, Sevcikova, Veronika, Mlcek, Jiri, Volek, Zdenek, and Cernekova, Martina
- Subjects
THREE-dimensional printing ,FOOD science ,GAS detectors ,GAS analysis ,CAPILLARY columns - Abstract
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]
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- 2024
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34. Identification of Phospholipids Relevant to Cancer Tissue Using Differential Ion Mobility Spectrometry.
- Author
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Sioris, Patrik, Mäkelä, Meri, Kontunen, Anton, Karjalainen, Markus, Vehkaoja, Antti, Oksala, Niku, and Roine, Antti
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FISHER discriminant analysis ,SUPPORT vector machines ,SURGICAL smoke ,SURGICAL instruments ,GAS analysis - Abstract
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]
- Published
- 2024
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35. Cobalt Molybdenum Telluride as an Efficient Trifunctional Electrocatalyst for Seawater Splitting.
- Author
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Kar, Rajarshi, Nouralishahi, Amideddin, Singh, Harish, and Nath, Manashi
- Subjects
ARTIFICIAL seawater ,OXIDATION of water ,OXYGEN reduction ,GAS analysis ,SEAWATER ,OXYGEN evolution reactions ,HYDROGEN evolution reactions - Abstract
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]- Published
- 2024
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36. Low-Power Chemiresistive Gas Sensors for Transformer Fault Diagnosis.
- Author
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Mei, Haixia, Peng, Jingyi, Xu, Dongdong, and Wang, Tao
- Subjects
GAS detectors ,FAULT diagnosis ,GAS analysis ,POWER transformers ,PRECIOUS metals - Abstract
Dissolved gas analysis (DGA) is considered to be the most convenient and effective approach for transformer fault diagnosis. Due to their excellent performance and development potential, chemiresistive gas sensors are anticipated to supersede the traditional gas chromatography analysis in the dissolved gas analysis of transformers. However, their high operating temperature and high power consumption restrict their deployment in battery-powered devices. This review examines the underlying principles of chemiresistive gas sensors. It comprehensively summarizes recent advances in low-power gas sensors for the detection of dissolved fault characteristic gases (H
2 , C2 H2 , CH4 , C2 H6 , C2 H4 , CO, and CO2 ). Emphasis is placed on the synthesis methods of sensitive materials and their properties. The investigations have yielded substantial experimental data, indicating that adjusting the particle size and morphology structure of the sensitive materials and combining them with noble metal doping are the principal methods for enhancing the sensitivity performance and reducing the power consumption of chemiresistive gas sensors. Additionally, strategies to overcome the significant challenge of cross-sensitivity encountered in applications are provided. Finally, the future development direction of chemiresistive gas sensors for DGA is envisioned, offering guidance for developing and applying novel gas-sensitive sensors in transformer fault diagnosis. [ABSTRACT FROM AUTHOR]- Published
- 2024
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37. A Critical Review on Soil Gas Analysis: Modern Technologies and Problems.
- Author
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Bannov, Alexander G., Trubin, Igor' V., Zakharov, Ilya K., Maksimovskiy, Evgeny A., and Kurmashov, Pavel B.
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SOIL air ,SOIL testing ,OPTICAL measurements ,GAS analysis ,GAS detectors - Abstract
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]
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- 2024
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38. Geochemical and Physical Methods for Estimating the Saturation of Natural Gas Hydrates in Sediments: A Review.
- Author
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Xue, Yuan, Lu, Hailong, Yang, Hailin, Cai, Wenjiu, and Zhan, Linsen
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GAS hydrates ,PORE water ,WATER chemistry ,VOLUMETRIC analysis ,GAS analysis ,METHANE hydrates ,NATURAL gas - Abstract
The saturation of natural gas hydrates is a key parameter for characterizing hydrate reservoirs, estimating hydrate reserves, and developing hydrate as an energy resource. Several methods have been proposed to estimate hydrate saturation, although most of these studies rely on logging and seismic data. However, the methods for estimating hydrate saturation from recovered core sediments have not been thoroughly reviewed, which hinders a deeper understanding, proper application, and the use of these experimental data to integrate geophysical and numerical model results with the actual geological conditions. In this paper, the methods widely used for estimating natural gas hydrate saturation from core sediments, including those based on pore water chemistry (Cl
− concentration, δD, and δ18 O values), gas volumetric analysis, and temperature anomaly, have been summarized in terms of the principle, estimation strategy, and issues to be considered of each method. The applicability, advantages and disadvantages, and scope of application of each method are also compared and discussed. All methods for estimating gas hydrate saturation have certain limitations. A comprehensive application of results from multiple methods could lead to a better understanding of the amount of gas hydrate in sediments, although the chlorinity of pore water is the most commonly used method of estimation. [ABSTRACT FROM AUTHOR]- Published
- 2024
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39. A multi-year characterization of confiscated vaping products from Virginia school youth.
- Author
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Holt, Alaina K, Buckmire, Meredith G, Moss, Kelsey S, Meekins, Jessemia, Outhous, Ashleigh E, Reveil, Laerissa, Goden, Akira B, Hoetger, Cosima, Eversole, Alisha, Poklis, Justin L, Soule, Eric K, Cobb, Caroline O, and Peace, Michelle R
- Subjects
ELECTRONIC cigarettes ,ANALYTICAL chemistry ,MANUFACTURING industries ,GAS analysis ,COOLANTS - Abstract
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]
- Published
- 2024
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40. Synchrotron Infrared Microspectroscopy of Zeolite Catalysts.
- Author
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Howe, Russell F., Wright, Paul A., Tuxworth, Ivalina, Frogley, Mark D., and Cinque, Gianfelice
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ZEOLITE catalysts ,SINGLE crystals ,GAS analysis ,SPATIAL resolution ,SYNCHROTRONS - Abstract
This article reviews recent work undertaken at the beamline B22 of the Diamond Light Source using infrared (IR) microspectroscopy to characterise zeolite catalysts and to study their reactivity in real time. The advantage of vibrational microspectroscopic analysis when linked to the brightness and spectral bandwidth of synchrotron IR light are illustrated. The high spatial resolution means that the uniformity of acid site concentrations within individual large crystals of zeolites and between different crystals can be readily checked and changes to acid site concentrations within crystals resulting from steam treatment mapped. When an in situ reaction cell is coupled with mass spectrometric analysis of evolved gases the rapid time response of the method has provided new insight into the initial stages of the conversion of methanol to hydrocarbons over ZSM-5 and SAPO-34 single crystals. Future prospects for applying the method to other types of zeolite catalysed reactions with improved reaction cell design are also discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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41. Breath Analysis via Gas Chromatography–Mass Spectrometry (GC-MS) in Chronic Coronary Syndrome (CCS): A Proof-of-Concept Study.
- Author
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Lombardi, Marco, Segreti, Andrea, Miglionico, Marco, Pennazza, Giorgio, Tocca, Lorenzo, Amendola, Luca, Vergallo, Rocco, Di Sciascio, Germano, Porto, Italo, Grigioni, Francesco, and Antonelli Incalzi, Raffaele
- Subjects
MYOCARDIAL revascularization ,VOLATILE organic compounds ,CORONARY angiography ,GAS analysis ,GAS chromatography/Mass spectrometry (GC-MS) - Abstract
Background: This proof-of-concept study aimed to assess the diagnostic potential of gas chromatography–mass spectrometry (GC-MS) in profiling volatile organic compounds (VOCs) from exhaled breath as a diagnostic tool for the chronic coronary syndrome (CCS). Methods: Exhaled air was collected from patients undergoing invasive coronary angiography (ICA), with all samples obtained prior to ICA. Post hoc, patients were divided into groups based on coronary lesion severity and indications for revascularization. VOCs in the breath samples were analyzed using GC-MS. Results: This study included 23 patients, of whom 11 did not require myocardial revascularization and 12 did. GC-MS analysis successfully classified 10 of the 11 patients without the need for revascularization (sensitivity of 91%), and 7 of the 12 patients required revascularization (specificity 58%). In subgroup analysis, GC-MS demonstrated 100% sensitivity in identifying patients with significant coronary lesions requiring intervention when the cohort was divided into three groups. A total of 36 VOCs, including acetone, ethanol, and phenol, were identified as distinguishing markers between patient groups. Conclusions: Patients with CCS exhibited a unique fingerprint of exhaled breath, which was detectable with GC-MS. These findings suggest that GC-MS analysis could be a reliable and non-invasive diagnostic tool for CCS. Further studies with larger cohorts are necessary to validate these results and explore the potential integration of VOC analysis into clinical practice. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
42. Prediction of interface morphology formed by the oblique gas jet impinging on a liquid surface.
- Author
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Fu, Weijie, Li, Daqi, and Zhang, Xinming
- Subjects
LIQUID surfaces ,SURFACE tension ,FLUID dynamics ,COMPUTER vision ,GAS analysis - Abstract
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]
- Published
- 2024
- Full Text
- View/download PDF
43. Photoacoustic spectroscopy with a widely tunable narrowband fiber-feedback optical parametric oscillator.
- Author
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Schmid, Luca, Kadriu, Florent, Kuppel, Sandro, Floess, Moritz, Steinle, Tobias, and Giessen, Harald
- Subjects
OPTICAL parametric oscillators ,PHOTOACOUSTIC effect ,TRACE gases ,GAS analysis ,EARLY diagnosis ,PHOTOACOUSTIC spectroscopy - Abstract
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]- Published
- 2024
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- View/download PDF
44. Possibilities of producing lightweight aggregates from silica-clay raw material and cellulosic waste.
- Author
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Panna, Wojciech, Prewendowski, Sebastian, Juda, Wiesław, and Szumera, Magdalena
- Subjects
ORGANIC wastes ,MATERIALS testing ,GAS analysis ,CLAY minerals ,MINERAL aggregates - Abstract
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]
- Published
- 2024
- Full Text
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45. Thermal degradation of nanoporous Si-containing hybrid terpolymer.
- Author
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Sobiesiak, Magdalena, Puziy, Alexander M., Poddubnaya, Olga I., and Parcheta, Monika
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CARBON composites ,FULLERENES ,CHEMICAL properties ,GAS analysis ,THERMOGRAVIMETRY - Abstract
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]
- Published
- 2024
- Full Text
- View/download PDF
46. Preliminary study of hot gas duct heat transfer experimental power reactor.
- Author
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Sulistyo, F. Y., Bakhri, S., Rohanda, A., and Siswantara, A. I.
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GAS cooled reactors ,HEAT transfer ,INSULATING materials ,HIGH temperatures ,GAS analysis - Abstract
Experimental power reactor (RDE) is a 10 MWe high temperature gas cooled reactor that is designed by BATAN. A preliminary heat transfer analysis of hot gas duct, an important part in the reactor, has been studied and the result was satisfying and could be reanalyzed to obtain the exact method to solve the heat transfer issue. The design is simplified to maintain the specific parameter that will be analyze. The parameter are temperature, pressure and mass flow. The result is compared to technical RDE data and the result show that the error is below than 5%. This result is enough to represent the actual data and can be used to be the further design. The insulation material also put some effect that maintain the hot gas temperature stable. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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47. Phytochemical screening, GC-MS, FTIR, and antibacterial activity of methanol extract of Caesalpinia Bonduc (L.) roxb. seeds.
- Author
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Samriani, Samriani, Natsir, Hasnah, Dali, Seniwati, and Arif, Abdur Rahman
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PHYTOCHEMICALS ,GAS chromatography/Mass spectrometry (GC-MS) ,METABOLITES ,BIOACTIVE compounds ,GAS analysis ,ANTIBACTERIAL agents ,SAPONINS - Abstract
Caesalpinia bonduc (L.) Roxb. is a medicinal plant belonging to the family Caesalpiniaceae. It's popularly known as gorek in Indonesia. All part of the plant were claimed to possess some therapeutic property, but the seed is the most widely used part in various systems of medicine. The seeds contain secondary metabolites as bioactive compounds therefore this plant has antibacterial activity. This study aimed to identify secondary metabolites and to analysis the Gas Chromatography-Mass Spectrometry (GC-MS) and Fourier Transform Infred (FTIR) of methanol extract of C. bonduc seeds as well as antibacterial activity. The phytochemical screening of methanol extract of C. bonduc seeds indicate the presence of alkaloids, flavonoids, saponins, tannins, and phenolics. The GC-MS analysis showed the presence of 100 different compounds with three main compounds: 4-Methyl-1,3-Dioxolan-2-One, 2-Trimethylsilyl-1,3-dithiane, and Cholesta-5,7,9(11)-trien-3-ol acetate. The FTIR analysis showed that the extract has functional groups O-H, N-H, C-N, C-H, C-O, C=C, C=O, C-S, and C-Si. The antibacterial activity of methanol extract of C. bonduc seeds at various concentrations had an inhibitory activity against the growth of Escherichia coli and Stapylococcus aureus. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
48. Response of the ZnO/Fe2O3 sensors to the breath from individuals with combinations of diabetes at room temperature.
- Author
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Gaidan, Ibrahim, Ul-Ahad, Inam, Gaidan, Om Kalthoum, and Brabazon, Dermot
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BLOOD sugar ,GOLD electrodes ,VOLATILE organic compounds ,BREATH tests ,GAS analysis - Abstract
Various studies have shown that human breath analysis can detect presence of different diseases in patients, such as cancer, diabetes, renal failure, etc. The level of different volatile organic compounds (VOCs) in human breath can be different depending upon the disease that the patient is suffering from. The location of affected organs in the human body (e.g. lungs, stomach, pancreas, etc.) can also be identified on the basis of breath gas analysis. This encourages the development of advanced sensors that can detect human breath gases that are present in very low concentrations at low pressures. In this study, two sensors were fabricated using pure Fe2O3 powder and ZnO/Fe2O3 mixed powder. The sensors were screen printed on the top of glass substrates with interdigitated gold electrodes. The sensors were used to detect the breath of two diabetes patients two times a day (before and after breakfast). At the same time glucose blood tests for the two people were done. The response of the sensors was increased when exposed to breath compared with response to air. The results were compared by the glucose blood tests which examined at the same time as the breath tests. It was observed that responses of the sensors increased or decreased with increasing or decreasing the level of the glucose in the blood. Direct proportional relationship between the responses of the breath sensors and glucose level in the blood were observed. Initial results show that the sensors developed in this study can be used to analyse human breath and may give an indicator to the presence of the level of glucose. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
49. CHNSO Elemental Analyses of Volatile Organic Liquids by Combined GC/MS and GC/Flame Ionisation Detection Techniques with Application to Hydrocarbon-Rich Biofuels.
- Author
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Onwudili, Jude Azubuike, Peters, Morenike Ajike, and Alves, Carine Tondo
- Subjects
QUANTITATIVE chemical analysis ,GAS chromatography/Mass spectrometry (GC-MS) ,LIQUID analysis ,ELEMENTAL analysis ,GAS analysis - Abstract
Elemental analysis is a fundamental method for determining the carbon, hydrogen, nitrogen, sulphur, and oxygen (CHNSO) contents in organic materials. Automated conventional elemental analysers are commonly used for CHNSO determinations, but they face challenges when analysing volatile organic liquids due to sample losses. This present study explores the combination of gas chromatography–mass spectrometry (GC/MS) and gas chromatography–flame ionisation detection (GC/FID) as a more accurate alternative method for elemental analysis of such liquids. Six different liquid samples containing various organic compounds have been analysed using both a conventional elemental analyser (Method 1) and the combined GC/MS–GC/FID method (Method 2). The results showed that Method 1 gave results with significant errors for carbon (by more than ±10 wt%) and oxygen (by up to ±30 wt%) contents due to volatile losses leading to inaccurate "oxygen-by-difference" determinations. In contrast, Method 2 gave more accurate and consistently representative elemental data in a set of simulated samples when compared to theoretical elemental data. This work proposes the use of the GC/FID method as a reliable alternative for CHNSO analysis of volatile organic liquids and suggests that employing the GC/FID technique can mitigate the common errors associated with conventional CHNSO analysis of such samples. However, successfully using Method 2 would depend on the skills and experience of users in qualitative and quantitative organic chemical analyses by gas chromatography. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
50. Homogenizing microwave pyrolysis of oily sludge using nano-Fe3O4: volatile gas product analysis.
- Author
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Yan, Jing, Shao, Zhiguo, Cheng, Wencai, Xu, Shipei, Wen, Qian, He, Zhicheng, Liu, Dujiang, Li, Jiangbo, and Lu, Xirui
- Subjects
GAS chromatography/Mass spectrometry (GC-MS) ,MOLECULAR dynamics ,ACTIVATION energy ,MAGNETIC materials ,GAS analysis - Abstract
To improve the homogeneity of heating, the magnetic absorbing material Fe
3 O4 is considered to use in microwave pyrolysis of oily sludge. Therefore, the effect of Fe3 O4 on the microwave pyrolysis of oily sludge is investigated based on gas volatile products. Thermogravimetric mass spectrometry result certifies that Fe3 O4 will increase the weight-loss ratio from 13.0% to 14.1%. Also, the characteristic peak intensity of CO in gas products decreases from 5.41 × 10−10 A/g to 1.95 × 10−10 A/g, while H2 O increases from 3.57 × 10−10 A/g to 7.32 × 10−10 A/g and CO2 increases from 6.87 × 10−10 A/g to 8.92 × 10−10 A/g. This is caused by the esterification of alcohols and esters and the reduction of Fe3 O4 by CO. Based on the decrease in activation energy and enthalpy values of Stage II and IV, it infers that Fe3 O4 catalyzes the pyrolysis process of oily sludge to some extent. Similarly, gas chromatography-mass spectrometry results show that Fe3 O4 can make the types of gas products increase. Especially, the number of molecular species increases from 5 to 46 under 200–300 °C. Finally, a simple molecular dynamics simulation model is conducted, and the results are in agreement with the experimental results. This study shows that Fe3 O4 improves the pyrolysis homogeneity and the pyrolysis efficiency also improves. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
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