Dual Gas Research Articles

Hyaluronic acid modified prussian blue analogs/TiO₂ janus nanostructures through efficient charge separation to enhance photocatalytic-driven dual gas for achieve multimodal treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by the abnormal proliferation of fibroblast-like synoviocytes and changes in the joint synovium, including elevated reactive oxygen species, decreased pH, and reduced oxygen content. In this study, we synthesized a novel nanocomposite material, namely HA-PBA-TiO2 Janus nanocomposite, by in situ etching in prussian blue analogs doped with Co and Ni, followed by the growth of TiO2 nano-flowers and encapsulation in hyaluronic acid. When these janus nanoparticles diffused to the inflammatory sites of RA, they exhibited outstanding photocatalytic water-splitting ability under 660 nm laser irradiation, generating H2 and O2. This capability helps ameliorate the hypoxic microenvironment at RA inflammatory sites by eliminating reactive oxygen species (ROS) and enhancing antioxidation and oxygenation. Furthermore, owing to the doping of Co and Ni, HA-PBA-TiO2 exhibits photothermal conversion capability, which significant damage to FLS upon exposure to 660 nm laser irradiation, thereby controlling their aberrant proliferation. Through a series of in vitro and in vivo experiments, we validated the significant therapeutic efficacy of HA-PBA-TiO2 in treating RA, highlighting its broad prospects for application.

Ni-doped (MoO3/MoS2) heterostructure chemiresistive sensor for dual selective detection of NH3 and NOx at room temperature

The transition metal dichalcogenide heterostructures are emerging as promising candidates for room-temperature gas sensors. This work presents a Ni-doped (MoO3/MoS2) heterostructure, synthesized via hydrothermal methods with varying Ni concentrations, for the dual selective detection of NH3 and NOx gases. The electronic sensitization of Ni improves the sensitivity of heterostructure. The heterostructure was characterized by using X-ray diffractometer, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM), with Ni incorporation confirmed by X-ray photoelectron spectroscopy (XPS). The 10 % Ni-doped MoO3/MoS2 heterostructure showed high sensitivity, achieving responses of 15 % and 18.3 % towards 10 ppm NH3 and NOx, respectively, with detection limits of 0.13 ppm and 0.11 ppm. Furthermore, the sensor demonstrated outstanding cyclic stability, device-to-device reproducibility, and long-term stability, with a retained response of 98.1 % and 98.5 % towards NH3 and NOx, respectively. These findings highlight the potential of Ni-doped (MoO3/MoS2) heterostructures for dual gas sensing applications at room temperature.

Highly selective dual gas (NO & NO2) sensing depended on operating temperature of WO3 thin films sputtered at room temperature

Highly selective dual gas (NO & NO2) sensing depended on operating temperature of WO3 thin films sputtered at room temperature

High-sensitive and fast-responsive In2O3 thin film sensors for dual detection of NO2 and H2S gases at room temperature

In this work, the room-temperature dual gas sensing characteristics of indium oxide (In2O3) thin films towards NO2 and H2S have been studied. In2O3 thin films were synthesized by the thermal oxidation of indium metal films of various thicknesses in the range of 50–250 nm deposited by thermal evaporation method. Grazing incidence X-ray diffraction (GI-XRD) revealed the change in preferred orientation of In2O3 thin films corresponding to varying thickness, while field-emission electron microscopy studies showcased evolving surface morphologies from individual grains to granular network with respect to the increase in film thickness. Investigations were made on the ability of In2O3 thin films to detect various low concentrations of nitrogen dioxide (NO2) and hydrogen sulfide (H2S) gases at ambient temperature. In2O3 thin films synthesized using 100 nm thick In films exhibited good sensing response of around 58 and 68 % towards NO2 and H2S gases of 5 ppm respectively, at room temperature (27 °C) with the response time of 36 and 18 s. Remarkably, the lower experimental detection limit of these toxic gases could be extended up to 100 ppb. Using X-ray photoelectron spectroscopy, a large presence of surface oxygen is observed on the In2O3 thin film. The sensor has demonstrated remarkable sensing abilities, including strong selectivity, quick sensing response, and good repeatability.

Strength-ductility synergy in a non-equiatomic Co–Cr–Ni medium entropy alloy wall structure deposited using twin-wire arc additive manufacturing

An innovative twin-wire arc additive manufacturing (T-WAAM) has been deployed to fabricate a Co-rich non-equiatomic Co–Cr–Ni medium entropy alloy. The TWAAM-built single-wall structures of Co50Cr10Ni40 alloy were fabricated under argon gas shielding using dual gas metal arc welding sources. The microstructure studies revealed a single-phase FCC crystal structure and defect-free deposition. The slender columnar substructure and cellular substructure are formed along the build direction (BD) and scan direction (SD) respectively, which are commonly observed in the wall structures of other conventional FCC alloys. The tensile coupon SD and BD displayed a superior high strength and ductility combination. The T-WAAM-fabricated Co50Cr10Ni40 alloy showed both strength and elongation 1.4 times greater than that of the laser additive manufactured equiatomic CoCrNi wall structure. Thus, the study opens up a new avenue to tailor the mechanical properties of CoCrNi MEA by composition variation, with an added advantage of higher deposition rates of TWAAM.

The variation law and mechanism of titanium alloy MIG welding process under the synergistic effect of coaxial dual channel gas path

The variation law and mechanism of titanium alloy MIG welding process under the synergistic effect of coaxial dual channel gas path

Hollow mesoporous In2O3 derived from MIL-68 (In) for dual gas sensing of NO2 and H2

NO2 is one of the most important air pollutant gases for the environment and human health. H2 is seen as the next generation of clean energy to promote sustainable development. However, sensitive detection of NO2 at room temperature is still a major challenge, and reliable H2 sensors are also scarce. Metal oxide semiconductor (MOS) gas sensors are advantageous for detecting gas. Hence, we synthesized the unique hexahedral hollow mesoporous In2O3 (h-In2O3) derived from MIL-68 (In). The formation process and properties of h-In2O3 were analyzed. The surface of h-In2O3 is rich in hydroxyl groups, which are active sites for NO2 adsorption at room temperature. Increasing working temperature up to 160 °C enables effective sensing reaction with H2. Based on different temperature-dependent gas sensing mechanisms, the h-In2O3 sensor exhibits ultrasensitive response values of 400 towards 100 ppb NO2 at room temperature (24 °C) and of 17.99 towards 10 ppm H2 at 160 °C. In addition, the h-In2O3 sensor exhibits reliable linear response, low theoretical detection limit of 1.8 ppt and 23 ppb for NO2 and H2, excellent selectivity, repeatability and long-term stability. The synergistic effect of the unique structure, larger specific surface area, and abundant adsorbed oxygen plus oxygen vacancy contribute to the excellent gas sensing performance of the h-In2O3 sensor. This study provides a promising strategy for the development of bifunctional gas sensors.

Humidity-Mediated Dual Ionic-Electronic Conductivity Enables High Sensitivity in MOF Chemiresistors.

In the presence of water, the electrically conductive metal-organic framework (MOF) Cu3HHTT2 (H6HHTT = 2,3,7,8,12,13-hexahydroxy-4b1,5,10,15-tetraazanaphtho[1,2,3-gh]tetraphene) provides a conduit for proton transport, thereby becoming a dual ionic-electronic conductor. Owing to its dual conducting nature and its high density of imine and open metal sites, the MOF operates as a particularly sensitive chemiresistor, whose sensing mechanism changes with relative humidity. Thus, the interaction of NH3 gas with the MOF under low humidity promotes proton transport, which translates to high sensitivity for ammonia detection. Conversely, NO2 gas hinders proton conductivity, even under high relative humidity conditions, leading to large resistance variations in the humid regime. This dual ionic-electronic conduction-based gas sensor provides superior sensitivity compared to other conventional chemiresistors under similar conditions and highlights its potential as a platform for room-temperature gas sensors.

Evaluation of Effective Interfacial Area in a Rotating Packed Bed Equipped with Dual Gas Inlets

This study investigates the effective interfacial area in a novel rotating packed bed (RPB) equipped with dual gas inlets instead of the conventional single-gas-inlet RPB. The aim is to enhance the mass transfer efficiency of gas-liquid contacting processes in RPBs by increasing the number of gas inlets to improve the spread of gas supply into the packing. The RPB is a promising gas-liquid contactor configuration known for its intensified mass transfer characteristics. However, the impact of additional gas inlets on the effective interfacial area of the packing remains unexplored. An experimental method assessed the interfacial area under varying operational conditions which include a liquid flow rate of 0.30-0.60 m3/h, a gas flow rate of 100-300 Nm3/h, and a rotation speed of 600-1000 rpm. At operating conditions covering the maximum rotation speed of 1400 rpm, gas flow and liquid flow rates of 300 Nm3/h and 0.60 m3/h respectively, the results showed that on average, 55 to 97% of the 2400m2/m3 specific packing area can be effectively utilized for gas-liquid mass transfer during separation operations using the RPB. Compared to results reported for single-gas-inlet RPBs using similar packings, the RPB with double gas inlet proved to provide higher utilization of the packing. By simply doubling the number of gas inlets, the findings provide valuable insights into optimizing RPB designs and operations which could enhance mass transfer efficiency for various chemical and environmental applications.

Differential detection of NH3 and NO2 by polymer non-covalently encapsulated semiconducting single-walled carbon nanotubes

Semiconductor single-walled carbon nanotubes (sc-SWCNTs) exhibit exceptional optoelectronic properties and possess a substantial specific surface area, rendering them highly promising materials for the development of gas sensors with increasing the sensitivity and portability. In this study, we synthesized polymer bearing two Schiff base side chains (PF2L) via the Suzuki coupling reaction with enhanced polymer solubility. The sc-SWCNTs were selectively sorted using PF2L from commercially available SWCNTs to prepare PF2L/sc-SWCNTs composites. The incorporation of side chains enhanced the π-π interactions within the polymers and facilitated the interactions between the polymers and SWCNTs, thereby promoting superior dispersion of sc-SWCNTs. The PF2L/sc-SWCNTs-based sensors were fabricated using the drop-coating method, and their gas sensing performance was evaluated for gases with distinct properties (reducing: NH3 and oxidizing: NO2). The sensor exhibits a response of 2.415 % and 14.85 % for 1 ppm NH3 vapor and 1 ppm NO2, respectively. The sensor shows response and recovery times of 50 s and 220 s, respectively, for the detection of 1 ppm NH3 vapor, while it demonstrated response and recovery times of 59 s and 733 s for the detection of 1 ppm NO2. Subsequently, we developed an LED-based detection device for the selective discrimination of NH3 vapor and NO2, thereby offering valuable insights into the potential practical applications of a single material for dual gas sensing.

Microstructural design characteristics of high-density polyethylene for thick-walled pressure pipe applications

Advancements in process technology and structure-property relationship-based design of high-density polyethylene has led to development of high-performance bimodal polyethylene grades suitable for large diameter thick-walled pressure pipe applications. These high-density bimodal products have enhanced design life, high pressure rating and sag resistance for fabrication of large diameter thick-walled pipe. Achieving optimal balance of these performance properties require controlled microstructural characteristics. The design characteristics are intricately influenced by catalyst type and process technology employed in resin manufacturing. In this study, we systematically establish correlations between microstructural characteristics of seven commercially available bimodal PE resins, produced using dual slurry or gas phase reactors, and their most relevant performance properties. We conducted comprehensive microstructural characterization of all samples using GPC-IR (high-temperature gel permeation chromatography coupled with an infrared composition detector), 13C NMR (nuclear magnetic resonance), TREF (temperature rising elution fractionation) and DSC (differential scanning calorimetry) techniques. Additionally, we measured mechanical, thermal, and rheological properties, focusing on crystallization kinetics, density, slow crack growth resistance (PENT and strain hardening modulus SHM) and low-frequency shear rheology of these products. Comparisons were made between key properties of interest, including slow crack growth resistance and low-frequency rheology (relevant for sag resistance), and microstructural characteristics. Theoretical and empirical correlations based on phenomenological models were employed for this analysis. The detailed study contributes to determining the critical levels of short and long chain branching, as well as molecular weight distribution characteristics essential to produce bimodal PE-4710 certifiable high-density polyethylene resins with low sag resistance. These design principles may serve as a foundation for the efficient design of reactor recipes and post-reactor modification processes, contributing to the evolution of pressure pipe polyethylene resin development and paving the way for design of next-generation pressure pipe grades.

Evaluation of methane adsorption isotherms at ambient temperature on carbon materials from NLDFT pore size analysis derived from standard N2 and CO2 adsorption isotherms

In this paper, we attempt to estimate CH4 adsorption on carbon materials based on the pore size distribution (PSD) characteristics evaluated from standard nitrogen and carbon dioxide adsorption isotherms using the nonlocal density functional theory (2D-NLDFT), or more precisely, its two-dimensional version (2D-NLDFT). The PSDs of the carbons were calculated by the simultaneous fit of the NLDFT models to the corresponding N2 and CO2 adsorption data. This method is referred to in the literature as the dual gas analysis method which is implemented in SAIEUS software. Essential features of carbon PSDs affecting the shapes of methane adsorption isotherms measured at ambient temperature were identified as related to micro and mesopores carbon structure. We discuss how different micro and mesopore size ranges contribute to methane adsorption isotherms in the low and higher-pressure ranges. The results of the present study may serve as guidance for selecting and designing suitable carbon materials for practical applications such as PSA recovery of CH4 from its mixtures or for methane storage.

On-Chip Annealing Using Embedded Micro-Heater for Highly Sensitive and Selective Gas Detection.

The demand for gas sensing systems that enable fast and precise gas recognition is growing rapidly. However, substantial challenges arise from the complex fabrication process of sensor arrays, time-consuming data transmission to an external processor, and high energy consumption in multi-stage data processing. In this study, a gas sensing system using on-chip annealing for fast and power-efficient gas detection is proposed. By utilizing a micro-heater embedded in the gas sensor, the sensing material of adjacent sensors in the same substrate can be easily varied without further fabrication steps. The response to oxidizing gas is constrained in metal oxide (MOX) sensing material with small grain sizes, as the depletion width of grain cannot extend beyond the grain size during the gas reaction. On the other hand, the response to reducing gases and humidity, which decrease the depletion width, is less affected by grain sizes. A readout circuit integrating a differential amplifier and dual FET-type gas sensors effectively emphasizes the response to oxidizing gases by canceling the response to reducing gases and humidity. The selective on-chip annealing method is applicable to various MOX sensing materials, demonstrating its potential for application in commercial fields due to its simplicity and expandability.

Ultra-highly sensitive dual gases detection based on photoacoustic spectroscopy by exploiting a long-wave, high-power, wide-tunable, single-longitudinal-mode solid-state laser.

Photoacoustic spectroscopy (PAS) as a highly sensitive and selective trace gas detection technique has extremely broad application in many fields. However, the laser sources currently used in PAS limit the sensing performance. Compared to diode laser and quantum cascade laser, the solid-state laser has the merits of high optical power, excellent beam quality, and wide tuning range. Here we present a long-wave, high-power, wide-tunable, single-longitudinal-mode solid-state laser used as light source in a PAS sensor for trace gas detection. The self-built solid-state laser had an emission wavelength of ~2 μm with Tm:YAP crystal as the gain material, with an excellent wavelength and optical power stability as well as a high beam quality. The wide wavelength tuning range of 9.44 nm covers the absorption spectra of water and ammonia, with a maximum optical power of ~130 mW, allowing dual gas detection with a single laser source. The solid-state laser was used as light source in three different photoacoustic detection techniques: standard PAS with microphone, and external- and intra-cavity quartz-enhanced photoacoustic spectroscopy (QEPAS), proving that solid-state laser is an attractive excitation source in photoacoustic spectroscopy.

Pulmonary diffusing capacity for carbon monoxide and nitric oxide after COVID-19: A prospective cohort study (the SECURe study).

Many patients exhibit persistently reduced pulmonary diffusing capacity after coronavirus disease 2019 (COVID-19). In this study, dual test gas diffusing capacity for carbon monoxide and nitric oxide (DL,CO,NO) metrics and their relationship to disease severity and physical performance were examined in patients who previously had COVID-19. An initial cohort of 148 patients diagnosed with COVID-19 of all severities between March 2020 and March 2021 had a DL,CO,NO measurement performed using the single-breath method at 5.7months follow-up. All patients with at least one abnormal DL,CO,NO metric (n=87) were revaluated at 12.5months follow-up. The DL,CO,NO was used to provide the pulmonary diffusing capacity for nitric oxide (DL,NO), the pulmonary diffusing capacity for carbon monoxide (DL,CO,5s), the alveolar-capillary membrane diffusing capacity and the pulmonary capillary blood volume. At both 5.7 and 12.5months, physical performance was assessed using a 30 s sit-to-stand test and the 6min walk test. Approximately 60% of patients exhibited a severity-dependent decline in at least one DL,CO,NO metric at 5.7months follow-up. At 12.5months, both DL,NO and DL,CO,5s had returned towards normal but still remained abnormal in two-thirds of the patients. Concurrently, improvements in physical performance were observed, but with no apparent relationship to any DL,CO,NO metric. The severity-dependent decline in DL,NO and DL,CO observed at 5.7months after COVID-19 appears to be reduced consistently at 12.5months follow-up in the majority of patients, despite marked improvements in physical performance.

Development of Oil and Gas Condensate Fields

In the world, with the development of science, brand new technologies are being created to generate energy resources (e.g., hydrogen energy, electric car, etc.). These inventions will reduce the consumption and cost of hydrocarbon resources. This leaves oil and gas resource producers with only one option – accelerated development of oil and gas fields with low capital investment. This monograph is devoted to the development of oil and gas fields in a short period of time with a reduction in the volume of drilling operations and well quality by at least 50%. The developed technology of simultaneous split operation will give an impetus to volumetric production of hydrocarbons, accelerated field development and reduction of capital investments, as well as lead to the production of all recoverable and non-recoverable reserves from the subsoil. This monograph also delves into the technological aspects of operating wells in the Altyguyi gas condensate field. The scientific work examines the operational and technological aspects of hydrodynamic and thermohydrodynamic studies. To support this research, patents for invention No. 643 and 644, dated January 6, 2015, were obtained (application numbers 14/101317 and 15/101320). These patents cover the “Simultaneous method of separate and joint operation of several productive horizons by one chink and device for its realization” and the “Method of dual oil and gas production from one well in a multizone”. Based on the findings of the conducted analyses, studies, and calculations, the implementation of the intensification of the gas condensate field using the oil and gas DC method by one well is justified. This approach represents a first in global practice and aims to reduce capital investments and accelerate development.

Enhanced dual gas sensing performance of MoS2/MoO3 nanostructures for NH3 and NO2 detection

Highly sensitive p-MoS2/n-MoO3 nanocomposite-based chemo-resistive gas sensors are synthesized by varying the reducing agents using hydrothermal synthesis followed by thermal annealing in an Ar environment for NH3 and NO2 detection at 50 °C. Structural characterizations confirmed the existence of MoS2 nanoflakes and MoO3 nanoplatelets and the appearance of abundant oxygen adsorption sites and sulfur vacancies in the nanocomposites. The MoS2:MoO3-based sensor (without any reducing agent) showed preferential detection of NH3 with 52% sensor response for 5 ppm gas concentration having response/recovery times of 28 s/97 s with n-type sensing behavior dominated by MoO3 charge carriers. On the contrary, NO2 gas attracts electrons from the MoS2 surface, exhibiting p-type sensing behavior with a sensor response of 42 % consisting of response/recovery times of 56 s/116 s with 5 ppm concentration at 50 °C. More interestingly, different adsorption sites and conductive channels play a huge role in the MoS2:MoO3 nanocomposite for exhibiting opposite sensing behaviours upon exposure to NH3 and NO2 gases. Enhanced sensitivity is dedicated to synergistic effects appearing due to the construction of p-n heterojunction to strengthen carrier transport by enhancing the sensor response. The present work provides a unique methodology for constructing MoS2:MoO3-based sensors and the effect of reducing agents on various MoS2:MoO3-based sensors. Moreover, our study recommends the plausible use of the MoS2:MoO3 composite-based heterojunctions to provide a constructive strategy for improving the performance of gas sensors.

Experimental study on the life and performance of an improved DC arc plasma torch

A novel DC arc plasma torch is designed in this paper in order to reduce the electrode erosion, and a series of experiments are carried out to investigate how to improve the lifetime and performance of the nitrogen DC arc plasma torch. The analysis of voltage characteristics of the plasma torch indicates that the interelectrode insert can increase the average arc voltage and the sudden expansion structure can reduce the voltage fluctuation, which is helpful to improve the working stability to some extent. The spectrum characteristics at the plasma torch outlet and the cold flow simulations show that the dual shielding gas mainly act near the anode and can effectively cover the entire anode wall. Combining the shielding gas distribution with anode heat transfer processes in argon and nitrogen plasma torch, it is inferred that argon shielding gas plays an important role on reducing the anode heat transfer processes in nitrogen plasma torch, which can effectively suppress the anode erosion. The life testing experimental results find that there is no significant erosion of the cathode, anode, and interelectrode insert after cumulative working time exceeding 20 h. The maximum nitrogen plasma jet length can reach ∼35 mm with the outlet jet temperature of about 20 000 K at the current of 100 A and nitrogen gas flow rate of 10 slm. The maximum average specific enthalpy and thermal efficiency are respectively about 14 MJ kg−1 and 75% in the nitrogen plasma torch. Therefore, this newly designed DC arc plasma torch not only can suppress the electrode erosion but also has good working performance, which is expected to have excellent application prospects.

A baseline correction and noise suppression method based on fitting neural network for CH4/C2H6 dual gas sensing system

We designed a methane/ethane (CH4/C2H6) dual-gas sensor on the basis of direct absorption spectroscopy (DAS) technology and explored the potential for low power consumption and miniaturization of the detection system using the effective optical range is only 25 cm for absorption cell and an uncooled photodetector. The problem of baseline drift introduced by uncooled photodetectors has been improved by using of a fitting neural network approach, and absorbance spectrum denoising has been realized. We established the mathematical relationship between absorbance and concentration for each gas of CH4/C2H6 through experimental detection, which shows strong linearity. And the correlation coefficients (R2) reached 0.99995 and 0.99998, demonstrating the robustness of the sensor. Through 3 h of measured and evaluated system, we obtained the minimum detectable column densities of 0.588 ppm⋅m and 0.128 ppm⋅m for CH4 and C2H6, respectively, which proved that the sensor has high sensitivity, strong stability, and has broad application prospects.

Dual Test Gas Pulmonary Diffusing Capacity Measurement During Exercise in Humans Using the Single-Breath Method.

The combined single-breath measurement of the diffusing capacity of carbon monoxide (DL,CO) and nitric oxide (DL,NO) is a useful technique to measure pulmonary alveolar-capillary reserve in both healthy and patient populations. The measurement provides an estimate of the participant's ability to recruit and distend pulmonary capillaries. The method has recently been reported to exhibit a high test-retest reliability in healthy volunteers during exercise of light to moderate intensity. Of note, this technique permits up to 12 repeated maneuvers and only requires a single breath with a relatively short breath-hold time of 5 s. Representative data are provided showing the gradual changes in DL,NO and DL,CO from rest to exercise at increasing intensitiesof up to 60% of maximal workload. The measurement of diffusing capacity and evaluation of alveolar-capillary reserve is a useful tool to evaluate the lung's ability to respond to exercise both in the healthy population as well as in patient populations such as those with chronic lung disease.