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•Sensors based on two Co-MOF-74 types were designed for the detection of gaseous H2.•Coexistence of Co2+ and Co3+ in Co-MOF-74 clusters is promising for H2 sensing.•High porosity and ...high Co concentration cause excellent sensing performance.
Two Co-MOF-74 (Co-MOF-I and Co-MOF–II) were designed for the sensing of H2 gas. Owing to the high density of Co ions (+2 and + 3 states) located in metal clusters in the p-type phase, Co-MOF-74 exhibited better selectivity in gaseous H2 sensing, compared with those of Ni-MOF-74 and Mg-MOF-74. The Co-MOF-II sensor, with higher porosity and Co ion concentration than the Co-MOF-I sensor, had more adsorption sites; consequently, more target gas molecules were adsorbed, resulting in a stronger change in the underlying resistance and better sensing. The gas sensing performance, characterized in the present study, highlights the advantages of using Co-MOFs gas sensors, in terms of their safety, energy usage, and scope of applications.
Gas chromatography (GC) is an excellent tool to obtain qualitative and quantitative information on volatile organic compounds (VOCs) present in gaseous samples. However, to carry out an appropriate ...quantitative analysis of unknown samples, the use of known concentration gas mixtures, to exploit as standards, is required. Commonly, these mixtures are obtained from cylinders of compressed gas at known concentrations: this involves a considerable economic outlay and problems relating to their handling. This paper aims to apply a method, proposed as a versatile, simple, and economical alternative to the use of such cylinders, for preparing gaseous calibration standards useful to obtain calibration curves for quantification of air pollutants. In addition, the operative limits of this method were investigated. The method involves the continuous injection of volatile compounds in liquid form into a stream of neutral gas, such as air or nitrogen. Exploiting the high volatility of the compounds used, it is possible to generate a continuous gas stream containing the chosen VOC at the desired concentration based on the mass balance of the system. This method proved to be suitable for compounds with volatility ranging from 36 kPa to 0.1 kPa at 293 K and it showed relative bias and relative standard deviation (RSD) values of less than 16% and 8%, respectively. The described dynamic method results are repeatable and accurate. It can be used effectively for compounds with vapour pressure values within the stated limits and provides a more versatile and cost-effective alternative to compressed gas cylinders.
The effect of corrosion in the oil industry leads to the failure of parts. This failure results in shutting down the plant to clean the facility. The annual cost of corrosion to the oil and gas ...industry in the United States alone is estimated at $27 billion (According to NACE International)-leading some to estimate the global annual cost to the oil and gas industry as exceeding $60 billion. In addition, corrosion commonly causes serious environmental problems, such as spills and releases. An essential resource for all those who are involved in the corrosion management of oil and gas infrastructure, this book provides engineers and designers with the tools and methods to design and implement comprehensive corrosion-management programs for oil and gas infrastructures. The book addresses all segments of the industry, including production, transmission, storage, refining and distribution.
Small polymer particles with a diameter of less than 5 mm called microplastics find their way into the environment from polymer debris and industrial production. Therefore a method is needed to ...identify and quantify microplastics in various environmental samples to generate reliable concentration values. Such concentration values, i.e. quantitative results, are necessary for an assessment of microplastic in environmental media. This was achieved by thermal extraction in thermogravimetric analysis (TGA), connected to a solid-phase adsorber. These adsorbers were subsequently analysed by thermal desorption gas chromatography mass spectrometry (TDS-GC-MS). In comparison to other chromatographic methods, like pyrolyse gas chromatography mass spectrometry (Py-GC-MS), the relatively high sample masses in TGA (about 200 times higher than used in Py-GC-MS) analysed here enable the measurement of complex matrices that are not homogenous on a small scale. Through the characteristic decomposition products known for every kind of polymer it is possible to identify and even to quantify polymer particles in various matrices. Polyethylene (PE), one of the most important representatives for microplastics, was chosen as an example for identification and quantification.
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•Using a thermal decomposition method for analysing PE microplastics in environmental matrices in one step.•Direct measuring without a pre selection.•Identification and quantification of polymers in environmental samples.
The Weiyuan (WY) and Changning (CN) fields are the largest shale gas fields in the Sichuan Basin. Though the shale gases in both fields are sourced from the Longmaxi Formation, this study found ...notable differences between them in molecular composition, carbon isotopic composition, and noble gas abundance and isotopic composition. CO2 (av. 0.52%) and N2 (av. 0.94%) were higher in Weiyuan than in Changning by an average of 0.45% and 0.70%, respectively. The δ13C1 (−26.9% to −29.7%) and δ13C2 (−32.0% to −34.9%) ratios in the Changning shale gases were about 8% and 6% heavier than those in Weiyuan, respectively. Both shale gases had similar 3He/4He ratios but different 40Ar/36Ar ratios. These geochemical differences indicated complex geological conditions and shed light on the evolution of the Lonmaxi shale gas in the Sichuan Basin. In this study, we highlight the possible impacts on the geochemical characteristics of gas due to tectonic activity, thermal evolution, and migration. By combining previous gas geochemical data and the geological background of these natural gas fields, we concluded that four factors account for the differences in the Longmaxi Formation shale gas in the Sichuan Basin: a) A different ratio of oil cracking gas and kerogen cracking gas mixed in the closed system at the high over-mature stage. b) The Longmaxi shales in WY and CN have had differential geothermal histories, especially in terms of the effects from the Emeishan Large Igneous Province (LIP), which have led to the discrepancy in evolution of the shales in the two areas. c) The heterogeneity of the Lower Silurian Longmaxi shales is another important factor, according to the noble gas data. d) Although shale gas is generated in closed systems, natural gas loss throughout geological history cannot be avoided, which also accounts for gas geochemical differences. This research offers some useful information regarding the theory of shale gas generation and evolution.
•CMOS-compatible ScAlN-based pyroelectric detector in NDIR CO2 sensing.•8-inch wafer level fabrication with ScAlN film deposited at ∼200 °C.•CO2 gas detection limit 25 ppm, response time ∼2 s.•CO2 ...gas response in relative humidity up to 70 %.
We demonstrate NDIR CO2 gas sensing using CMOS compatible MEMS ScAlN-based pyroelectric detectors. The ScAlN-based pyroelectric detectors are fabricated using 8-inch wafer level technology with 12 % Sc-doped AlN deposited at a temperature of ∼200 °C. Together with a blackbody thermal emitter, a 10 cm long enclosed gas channel with only inlet and outlet holes connected to tubings, and testing using 2 different reference gases (N2 and synthetic air), measurements show voltage signal drop due to CO2 gas absorption at the 4.26 μm wavelength at CO2 gas concentrations ranging from 5000 ppm down to 25 ppm. The signal change due to the CO2 gas response ranges from ∼2% at 100 ppm CO2 concentration to ∼40 % at 5000 ppm CO2 gas concentration for both CO2 gas measured in N2 and in synthetic air. CO2 gas response times are also measured for CO2 gas in N2 and in synthetic air at concentrations of 5000 ppm, 1000 ppm and 400 ppm. The gas response times measured around 2 s and lower. Introduction of humidity show some minor effect (<3%) to the CO2 gas response and seems most perturbed at 10 % relative humidity. To the best of our knowledge, this is the first demonstration using ScAlN-based pyroelectric detectors in NDIR CO2 gas sensing, towards practical sensor applications. The results obtained show promise in using CMOS-compatible MEMS ScAlN-based pyroelectric detectors for NDIR gas sensing, opening up possibilities for low cost, wafer-level, monolithic NDIR gas sensors with small footprint integrated with CMOS circuits.
The prediction model's performance in view of the wavelet transform (WT) is affected because the wavelet basis function (WBF) and its orders and layers are determined randomly. To solve this problem, ...this research devises a crossover experiment with 160 components of each WBF (Coiflets and Symlets) and forecasts 320 schemes with sparse autoencoder (SAE) and long short-term memory (LSTM), developing a combination model with WT, SAE, and LSTM. Furthermore, to verify the performance of the combination prediction model, the difference between the natural gas production and consumption in the U.S. is determined which is taken as an example. The results indicate that the SAE-LSTM exceeds other AI models (e.g. ELM), and WT outperforms other preprocessing algorithms (e.g. EMD) based on forecasting accuracy. The best performance of the established model is obtained by using the two orders six layers of Coiflets, and six orders seven layers of Symflets for natural gas production and consumption. In addition, the average difference between consumption and production of natural gas is 10.6809 Bcfpd. To make up for such a gap, some import methods can be adopted. It can be concluded that this study can provide a reference for other time-series prediction and natural gas policymakers.
•SAE-LSTM has higher prediction accuracy.•The optimal wavelet's orders and layers based on SAE-LSTM are determined.•The difference between NGP and NGC in U.S. is fixed by using WT-SAE-LSTM.
This paper presents a summary of the work done within the European Union's Seventh Framework Programme project ECLIPSE (Evaluating the Climate and Air Quality Impacts of Short-Lived Pollutants). ...ECLIPSE had a unique systematic concept for designing a realistic and effective mitigation scenario for short-lived climate pollutants (SLCPs; methane, aerosols and ozone, and their precursor species) and quantifying its climate and air quality impacts, and this paper presents the results in the context of this overarching strategy. The first step in ECLIPSE was to create a new emission inventory based on current legislation (CLE) for the recent past and until 2050. Substantial progress compared to previous work was made by including previously unaccounted types of sources such as flaring of gas associated with oil production, and wick lamps. These emission data were used for present-day reference simulations with four advanced Earth system models (ESMs) and six chemistry transport models (CTMs). The model simulations were compared with a variety of ground-based and satellite observational data sets from Asia, Europe and the Arctic. It was found that the models still underestimate the measured seasonality of aerosols in the Arctic but to a lesser extent than in previous studies. Problems likely related to the emissions were identified for northern Russia and India, in particular. To estimate the climate impacts of SLCPs, ECLIPSE followed two paths of research: the first path calculated radiative forcing (RF) values for a large matrix of SLCP species emissions, for different seasons and regions independently. Based on these RF calculations, the Global Temperature change Potential metric for a time horizon of 20 years (GTP20) was calculated for each SLCP emission type. This climate metric was then used in an integrated assessment model to identify all emission mitigation measures with a beneficial air quality and short-term (20-year) climate impact. These measures together defined a SLCP mitigation (MIT) scenario. Compared to CLE, the MIT scenario would reduce global methane (CH4) and black carbon (BC) emissions by about 50 and 80 %, respectively. For CH4, measures on shale gas production, waste management and coal mines were most important. For non-CH4 SLCPs, elimination of high-emitting vehicles and wick lamps, as well as reducing emissions from gas flaring, coal and biomass stoves, agricultural waste, solvents and diesel engines were most important. These measures lead to large reductions in calculated surface concentrations of ozone and particulate matter. We estimate that in the EU, the loss of statistical life expectancy due to air pollution was 7.5 months in 2010, which will be reduced to 5.2 months by 2030 in the CLE scenario. The MIT scenario would reduce this value by another 0.9 to 4.3 months. Substantially larger reductions due to the mitigation are found for China (1.8 months) and India (11-12 months). The climate metrics cannot fully quantify the climate response. Therefore, a second research path was taken. Transient climate ensemble simulations with the four ESMs were run for the CLE and MIT scenarios, to determine the climate impacts of the mitigation. In these simulations, the CLE scenario resulted in a surface temperature increase of 0.70 plus or minus 0.14 K between the years 2006 and 2050. For the decade 2041-2050, the warming was reduced by 0.22 plus or minus 0.07 K in the MIT scenario, and this result was in almost exact agreement with the response calculated based on the emission metrics (reduced warming of 0.22 plus or minus 0.09 K). The metrics calculations suggest that non-CH4 SLCPs contribute ~ 22 % to this response and CH4 78 %. This could not be fully confirmed by the transient simulations, which attributed about 90 % of the temperature response to CH4 reductions. Attribution of the observed temperature response to non-CH4 SLCP emission reductions and BC specifically is hampered in the transient simulations by small forcing and co-emitted species of the emission basket chosen. Nevertheless, an important conclusion is that our mitigation basket as a whole would lead to clear benefits for both air quality and climate. The climate response from BC reductions in our study is smaller than reported previously, possibly because our study is one of the first to use fully coupled climate models, where unforced variability and sea ice responses cause relatively strong temperature fluctuations that may counteract (and, thus, mask) the impacts of small emission reductions. The temperature responses to the mitigation were generally stronger over the continents than over the oceans, and with a warming reduction of 0.44 K (0.39-0.49) K the largest over the Arctic. Our calculations suggest particularly beneficial climate responses in southern Europe, where surface warming was reduced by about 0.3 K and precipitation rates were increased by about 15 (6-21) mm yr-1 (more than 4 % of total precipitation) from spring to autumn. Thus, the mitigation could help to alleviate expected future drought and water shortages in the Mediterranean area. We also report other important results of the ECLIPSE project.
Buried hill zones in the rift basins have a significant impact on the enrichment of natural gas resources, and this is of great significance for exploration and development. This study aims to ...unravel the origins, migration, and dynamic accumulation process of natural gas in the Xinglongtai structural belt, Liaohe Subbasin. A comprehensive geological and geochemical analysis was performed on source rocks and natural gas samples from various geological structures within the Xinglongtai structural belt. Moreover, basin modeling techniques were employed to trace the genesis and migration of natural gas, offering an in-depth understanding of the dynamic process of accumulation. We identified the Fourth Mbr (Es4) and Third Mbr (Es3) of the Shahejie Fm as the main source rocks in the Qingshui and Chenjia Sags. The Es4, primarily Shallow Lacustrine Mudstones, contributed mainly type II organic matter, while the Es3, consisting of Nearshore Subaqueous Fan and Deep Lacustrine Mudstones, contributed mainly type III and type II organic matter, respectively. Two distinct hydrocarbon accumulation systems were observed, one inside and one outside the buried hills. The system outside the buried hill is governed by a complex fault system within the lacustrine basin, resulting in dual-source directions, dual-source rock types, two migration phases, and late-stage accumulation. In contrast, the system within the buried hill primarily involves reservoirs nested in the basement, exhibiting dual-source directions, dual-source rock types, a single migration phase, and early-stage charging. The understanding of this interplay, alongside dynamic simulation of generation, migration, and accumulation, can provide valuable insights for predicting natural gas distribution and accumulation patterns in terrestrial faulted lacustrine basins. This knowledge can guide more effective exploration and development strategies for natural gas.
Divers are at enhanced risk of suffering from acute cognitive deterioration because of the low ambient temperatures and the narcotic action of inert gases inspired at high pressures. Yet, the ...behavioral effects of cold and inert gas narcosis have commonly been assessed in isolation and during short-term provocations. We therefore evaluated the interactive influence of mild hypothermia and narcosis engendered by a subanesthetic dose of nitrous oxide (N
O; a normobaric intervention analog of hyperbaric nitrogen) on cognitive function during prolonged iterative exposure. Fourteen men partook in two ∼12-h sessions (separated by ≥4 days), wherein they performed sequentially three 120-min cold (20°C) water immersions (CWIs), while inhaling, in a single-blinded manner, either normal air or a normoxic gas mixture containing 30% N
O. CWIs were separated by a 120-min rewarming in room-air breathing conditions. Before the first CWI and during each CWI, subjects performed a finger dexterity test, and the Spaceflight Cognitive Assessment Tool for Windows (WinSCAT) test assessing aspects of attention, memory, learning, and visuospatial ability. Rectal and skin temperatures were, on average, reduced by ∼1.2 °C and ∼8 °C, respectively (
< 0.001). Cooling per se impaired (
≤ 0.01) only short-term memory (∼37%) and learning (∼18%); the impairments were limited to the first CWI. N
O also attenuated (
≤ 0.02) short-term memory (∼37%) and learning (∼35%), but the reductions occurred in all CWIs. Furthermore, N
O invariably compromised finger dexterity, attention, concentration, working memory, and spatial processing (
< 0.05). The present results demonstrate that inert gas narcosis aggravates, in a persistent manner, basic and higher-order cognitive abilities during protracted cold exposure.
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