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Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 497
Author(s):  
Alejandro Torregrosa-Chinillach ◽  
Rafael Chinchilla

Performing synthetic transformation using visible light as energy source, in the presence of a photocatalyst as a promoter, is currently of high interest, and oxidation reactions carried out under these conditions using oxygen as the final oxidant are particularly convenient from an environmental point of view. This review summarizes the recent developments achieved in the oxidative dehydrogenation of C–N and C–O bonds, leading to C=N and C=O bonds, respectively, using air or pure oxygen as oxidant and metal-free homogeneous or recyclable heterogeneous photocatalysts under visible light irradiation.


Catalysts ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 20
Author(s):  
Seyed Sepehr Moeini ◽  
Umberto Pasqual Laverdura ◽  
Eleonora Marconi ◽  
Nicola Lisi ◽  
Emanuele Serra ◽  
...  

Catalytic aerobic oxidation of benzyl alcohol (BnOH) to benzaldehyde (PhCHO) over supported noble metal catalysts has grabbed the attention of researchers due to the critical role of PhCHO in numerous industrial syntheses. In the present study, a novel catalyst, Pd-P alloy supported on aminopropyl-functionalized mesoporous silica (NH2-SiO2), was prepared through in situ reduction and characterized by BET-BJH analysis, SEM, TEM, XRD, FTIR, TG-DTA, and XPS. Chemical properties and catalytic performance of Pd-P/NH2-SiO2 were compared with those of Pd0 nanoparticles (NPs) deposited on the same support. Over Pd-P/NH2-SiO2, the BnOH conversion to PhCHO was much higher than over Pd0/NH2-SiO2, and significantly influenced by the nature of solvent, reaching 57% in toluene at 111 °C, with 63% selectivity. Using pure oxygen as an oxidant in the same conditions, the BnOH conversion increased up to 78%, with 66% selectivity. The role of phosphorous in improving the activity may consist of the strong interaction with Pd that favours metal dispersion and lowers Pd electron density.


Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7976
Author(s):  
Junjie Zhang ◽  
Erjiang Hu ◽  
Qunfei Gao ◽  
Geyuan Yin ◽  
Zuohua Huang

The application of laser ignition in the aerospace field has promising prospects. Based on the constant volume combustion chamber, the laser ignition of CH4/O2/N2 mixture with different initial pressure, different laser energy, different equivalence ratio and different oxygen content has been carried out. The development characteristics of the flame kernel and shock wave under different conditions are analyzed. In addition, the Taylor model and Jones model are also used to simulate the development process of the shock wave, and a new modified model is proposed based on the Jones model. The experimental results show that under pure oxygen conditions, the chemical reaction rate of the mixture is too fast, which makes it difficult for the flame kernel to form the ring and third-lobe structure. However, the ring structure is easier to form with the pressure and laser energy degraded; the flame kernel morphology is easier to maintain at a rich equivalence ratio, which is caused by the influence of the movement of hot air flow and a clearer boundary between the ring and the third-lobe. The decrease of the initial pressure or the increase of the laser energy leads to the increase in shock wave velocity, while the change of the equivalence ratio and oxygen content has less influence on the shock wave.


Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 2057
Author(s):  
Fan Yang ◽  
Shengji Li ◽  
Xunjie Lin ◽  
Jiankan Zhang ◽  
Heping Li ◽  
...  

Although the gas phase combustion of metallic magnesium (Mg) has been extensively studied, the vaporization and diffusive combustion behaviors of Mg have not been well characterized. This paper proposes an investigation of the vaporization, diffusion, and combustion characteristics of individual Mg microparticles in inert and oxidizing gases by a self-built experimental setup based on laser-induced heating and microscopic high-speed cinematography. Characteristic parameters like vaporization and diffusion coefficients, diffusion ratios, flame propagation rates, etc., were obtained at high spatiotemporal resolutions (μm and tens of μs), and their differences in inert gases (argon, nitrogen) and in oxidizing gases (air, pure oxygen) were comparatively analyzed. More importantly, for the core–shell structure, during vaporization, a shock wave effect on the cracking of the porous magnesium oxide thin film shell-covered Mg core was first experimentally revealed in inert gases. In air, the combustion flame stood over the Mg microparticles, and the heterogeneous combustion reaction was controlled by the diffusion rate of oxygen in air. While in pure O2, the vapor-phase stand-off flame surrounded the Mg microparticles, and the reaction was dominated by the diffusion rate of Mg vapor. The diffusion coefficients of the Mg vapor in oxidizing gases are 1~2 orders of magnitude higher than those in inert gases. However, the diffusive ratios of condensed combustion residues in oxidizing gases are ~1/2 of those in inert gases. The morphology and the constituent contents analysis showed that argon would not dissolve into liquid Mg, while nitrogen would significantly dissolve into liquid Mg. In oxidizing gases of air or pure O2, Mg microparticles in normal pressure completely burned due to laser-induced heating.


2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Logan Kluis ◽  
Ana Diaz-Artiles

AbstractGas pressurized spacesuits are cumbersome, cause injuries, and are metabolically expensive. Decreasing the gas pressure of the spacesuit is an effective method for improving mobility, but reduction in the total spacesuit pressure also results in a higher risk for decompression sickness (DCS). The risk of DCS is currently mitigated by breathing pure oxygen before the extravehicular activity (EVA) for up to 4 h to remove inert gases from body tissues, but this has a negative operational impact due to the time needed to perform the prebreathe. In this paper, we review and quantify these important trade-offs between spacesuit pressure, mobility, prebreathe time (or risk of DCS), and space habitat/station atmospheric conditions in the context of future planetary EVAs. In addition, we explore these trade-offs in the context of the SmartSuit architecture, a hybrid spacesuit with a soft-robotic layer that, not only increases mobility with assistive actuators in the lower body, but it also applies some level of mechanical counterpressure (MCP). The additional MCP in hybrid spacesuits can be used to supplement the gas pressure (i.e., increasing the total spacesuit pressure), therefore reducing the risk of DCS (or reduce prebreathe time). Alternatively, the MCP can be used to reduce the gas pressure (i.e., maintaining the same total spacesuit pressure), therefore increasing mobility. Finally, we propose a variable pressure concept of operations for the SmartSuit spacesuit. Our framework quantifies critical spacesuit and habitat trade-offs for future planetary exploration and contributes to the assessment of human health and performance during future planetary EVAs.


2021 ◽  
Author(s):  
Heng Zhao ◽  
Haiqi He ◽  
Lei Ma ◽  
Kun Fan ◽  
Jinteng Feng ◽  
...  

Abstract Purpose The purpose of this study is to explore the feasibility of identifying the intersegmental plane by arterial ligation alone during thoracoscopic anatomical segmentectomy. Methods We selected 35 patients with peripheral small lung nodules who underwent thoracoscopic anatomical segmentectomy between May and December 2020. First, the targeted segmental arteries were distinguished and ligated during the operation. Then, bilateral pulmonary ventilation was performed with pure oxygen to fully inflate the entirety pulmonary lobes. After waiting for a while, the intersegmental plane appeared. Finally, the intersegmental plane was observed using thoracoscopy after indocyanine green was injected into the peripheral vein. The intersegmental planes determined by these two methods were compared. Results Thirty-four patients underwent segmental resection and one patient finally underwent lobectomy. The intersegmental planes were successfully observed in all patients using the arterial ligation method. The time from contralateral pulmonary ventilation to the appearance of the intersegmental plane was 13.7±3.2 min (6-19 min). The intersegmental planes determined by the arterial ligation method and the fluorescence method were comparable. After the operation, CT examinations showed that the remaining lung segments of all patients were well inflated. The mean duration of closed thoracic drainage was 3.1±0.9 days. Conclusion The arterial ligation method can be used to determine the intersegmental plane in anatomical segmentectomy. The method is feasible, reliable, and safe.


2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 272-272
Author(s):  
Semen Nikolaev ◽  
Igor Konopeltsev

Abstract Postpartum endometritis is one of the leading causes of infertility in cattle. The study aims to investigate the possibility of using ozonized flaxseed oil (OFO) for treating postpartum purulent-catarrhal endometritis in cows. Ozone was synthesized by using medical ozone generator and chemically pure oxygen. Linseed oil (400.0 ml) was bubbled with an ozone-oxygen mixture for 4 hours through a ceramic sprayer. An ozone concentration at the outlet was 30 mg/l. The therapeutic efficacy of OFO was studied on cattle of the Kholmogory breed with a productivity of 4800 - 5800 kg of milk per year. Thirty animals with symptoms of postpartum purulent-catarrhal endometritis were divided into two groups (n = 15). All of the subjects were in the second and third lactation periods. Animals from both groups were injected with 2% sinestrol solution on days 1 and 3 of treatment. OFO was used in the experimental group (EG). The cattle of the control group (CG) received a 7.5% solution of benzethonium chloride. Drugs were administered intrauterine at a dose of 50–150 ml (depending on the uterus’s size) using a polystyrene pipette, with an interval of 48–72 hours. Cows were inseminated artificially by the cervical method. The pregnancy was determined on the 30-35th day after insemination by ultrasonography. After 5 months of observation, all animals of the CG were pregnant. The pregnancy rate in the EG was 93,3%. In the groups efficiency of the first insemination was 20% and 47%, respectively. In the EG, one impregnation required 1.8±0.2 inseminations, which is 0.5 less than in the CG (2.3±0.3). The duration from calving to impregnation in cows in the EG was 104.4±6.9, 21.2 days less (P < 0.05) than the control, where the period was 125.6±7.6. Thus, OFO can be effectively used for the treatment of endometritis in cattle.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
W. A. Wetsch ◽  
H. Herff ◽  
D. C. Schroeder ◽  
D. Sander ◽  
B. W. Böttiger ◽  
...  

Abstract Background Preoxygenation and application of apneic oxygenation are standard to prevent patients from desaturation e.g. during emergency intubation. The time before desaturation occurs can be prolonged by applying high flow oxygen into the airway. Aim of this study was to scientifically assess the flow that is necessary to avoid nitrogen entering the airway of a manikin model during application of pure oxygen via high flow nasal oxygen. Methods We measured oxygen content over a 20-min observation period for each method in a preoxygenated test lung applied to a human manikin, allowing either room air entering the airway in control group, or applying pure oxygen via high flow nasal oxygen at flows of 10, 20, 40, 60 and 80 L/min via nasal cannula in the other groups. Our formal hypothesis was that there would be no difference in oxygen fraction decrease between the groups. Results Oxygen content in the test lung dropped from 97 ± 1% at baseline in all groups to 43 ± 1% in the control group (p < 0.001 compared to all other groups), to 92 ± 1% in the 10 L/min group, 92 ± 1% in the 20 L/min group, 90 ± 1% in the 40 L/min group, 89 ± 0% in the 60 L/min group and 87 ± 0% in the 80 L/min group. Apart from comparisons 10 l/ min vs. 20 L/min group (p = .715) and 10/L/min vs. 40 L/min group (p = .018), p was < 0.009 for all other comparisons. Conclusions Simulating apneic oxygenation in a preoxygenated manikin connected to a test lung over 20 min by applying high flow nasal oxygen resulted in the highest oxygen content at a flow of 10 L/min; higher flows resulted in slightly decreased oxygen percentages in the test lung.


2021 ◽  
Vol 2053 (1) ◽  
pp. 012006
Author(s):  
I I Komarov ◽  
S K Osipov ◽  
I A Shcherbatov ◽  
B A Makhmutov ◽  
I B Kaplanovich

Abstract Mitigation of harmful and greenhouse gas emissions produced by the coal combustion in thermal power plant is a topic goal. Reduction of the nitrogen oxides, sulfur and ash emissions makes remarkable progress but the carbon dioxide emission still meets considerable difficulties mostly caused by the low greenhouse gas content in the flue gas. A prospective solution to this problem may be the fuel combustion in oxygen-enriched air, which increases the flue gas carbon dioxide content. In this technology, the carbon dioxide content in flue gas is higher and this results in its easier capture. This paper presents the thermodynamic analysis results of a steam turbine power production facility that burns coal in the air with high oxygen content. The computer simulation shows that the oxygen content increase from 21 to 95.6% increases the carbon dioxide content in flue gas by a factor of 3.3 and lowers the power consumption for carbon dioxide capture by 11%. On the other side, the power consumption for pure oxygen production reduces the facility’s net efficiency from 28.54 to 21.59%.


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