A Novel Electrochemical Oxygen Sensor for Determination of Ultra-low Oxygen Contents in Molten Metal

A novel electrochemical oxygen sensor has been developed by using La beta -Al2O3 as solid electrolyte and Cr+Cr2O3 as reference electrode. The sensor not only can be used as normal oxygen sensor but also as an ultra-low oxygen sensor. Especially, it is very sensitive to measure ultra-low oxygen in molten metal. For estimating the accuracy of La beta -Al2O3 oxygen sensor, two series of oxygen activities in molten iron at different oxygen contents and different temperature were measured by both La beta -Al2O3 oxygen sensor and ZrO2 oxygen sensor. The theoretical values of oxygen activities in molten iron (3.30%C, in mass fraction) at 1723K and 1745K were also evaluated for comparing the measuring results of two sensors. At last, the error of measurement for La beta -Al2O3 oxygen sensor was discussed too.

短期超低氧处理抑制花生芽常温物流褐变作用的研究

探究不同超低氧处理时间对常温物流中花生芽褐变的抑制效果及作用机制,为实际物流包装应用提供理论依据。采用包装袋中充100%N2方式实现超低氧处理,然后分别在超低氧4、8、12 h后将包装袋打微孔,实现自发式气调,以不充氮直接微孔组为对照,于23℃下贮藏并测定相关指标。结果表明,直接微孔组因包装内含氧量相对较高对抑制常温下花生芽采后褐变无法起到积极作用。超低氧12 h微孔组由于在超低氧环境中处理时间过长,会引发无氧呼吸,从而产生过量的乙醇、乙醛对细胞造成毒害作用,导致花生芽生理代谢紊乱。而超低氧4、8 h微孔组均能形成花生芽适应的自发气调环境,有效降低呼吸强度,通过提高与活性氧代谢有关的超氧化物歧化酶、过氧化氢酶、过氧化物酶的活性,增强自由基清除能力,抑制超氧阴离子的积累,减弱了膜脂过氧化,其相对电导率和丙二醛含量的上升得到抑制,细胞膜的完整性得以更好地保护;同时超低氧4、8 h还抑制了多酚氧化酶活性的上升,保持花生芽良好的色泽,进而延缓花生芽的褐变;其中超低氧8 h处理的效果最佳。

Short-term prone positioning for severe acute respiratory distress syndrome after cardiopulmonary bypass:A case report and literature review

BACKGROUND Aortic dissection is a complex and dangerous cardiovascular disease,with many complications in the perioperative period,including severe acute respiratory distress syndrome(ARDS),which affects prognosis and increases mortality.Despite the effect of prone positioning(PP)in improving oxygenation in patients with severe ARDS,reports about PP early after cardiac surgery are few and such an opt-ion may be an issue in cardiac surgery patients because of the recent sternotomy.CASE SUMMARY A 40-year-old male patient diagnosed with acute type A aortic dissection on October 22,2021 underwent ascending artery replacement plus total aortic arch replacement plus stent elephant trunk implantation under cardiopulmonary bypass.Unfortunately,he developed ARDS on postoperative day 1.Despite comprehensive treatment with aggressive pulmonary protective ventilation,fluid management with continuous renal replacement therapy,the condition continued to deteriorate and rapidly progressed to severe ARDS with a minimum oxygenation index of 51.We are ready to implement salvage therapy,including PP and extracorporeal membrane oxygenation(ECMO).Due to the large amount of pericardial mediastinal and thoracic drainage after thoracotomy,ECMO may result in massive postoperative bleeding.Prolonged prone ventilation is often inappropriate after thoracotomy.Therefore,we chose short-term PP for<6 h.Finally,the oxygenation index greatly improved and the diffuse exudation in both lungs of the patient was significantly reduced with short-term prone positioning.CONCLUSION Intermittent short-term PP can improve early postoperative severe ARDS after acute aortic dissection.

高阻隔包装材料构建的超低氧短期处理对仔姜贮藏品质的影响

为探究短期超低氧处理对仔姜贮藏品质的控制作用,选用高阻隔性PET12/PE15/CPP30复合膜为包装材料构建超低氧内环境,设置无超低氧组(一直打孔)、长期超低氧组(不打孔)、短期超低氧-1微孔组(超低氧3 d后打1个微孔)、短期超低氧-2微孔组(超低氧3 d后打2个微孔)4组,研究高阻隔包装材料构建的超低氧短期处理协同微孔包装对仔姜感官品质、膜脂氧化、色泽以及气味的影响。结果表明,长期超低氧组和无超低氧组对仔姜品质都产生了负面影响,其中长期超低氧组在贮藏过程中,会引发无氧呼吸,导致丙酮酸脱羧酶、乙醇脱氢酶活性上升,进而提高乙醛、乙醇含量,加剧了仔姜品质的劣变,产生异味;而短期超低氧-1微孔组和短期超低氧-2微孔组都能够形成仔姜适应的低氧高二氧碳气体环境,避免不良气味的产生,同时延缓了超氧阴离子自由基产生速率,提高了超氧化物歧化酶和过氧化氢酶活性,抑制了相对电导率和丙二醛含量的上升,从而减弱了膜脂过氧化,保护了细胞膜的完整性,且其多酚氧化酶活性得到抑制,总酚消耗得以减缓,使其色泽更优,感官品质更好,且以短期超低氧-1微孔组效果最佳。因此,短期超低氧处理协同微孔包装能够有效保持仔姜贮藏品质,且使用高阻隔性包装材料构建超低氧环境的成本很低,可避免气调包装机(如充100%氮气)形成超低氧环境带来的高成本问题。

Can hypobaric hypoxia affect human thermal comfort?An experimental study in Tibet,China

Hypobaric hypoxia is the main environmental feature of the Tibetan plateau which would influence the efficiency of human metabolic heat production and the ability of thermal regulation.In order to understand the influence of the hypoxic environment on the plateau on the thermal comfort of short-term sojourners in Tibet,China,oxygen generators were used to create oxygen-enriched environments,and physiological and psychological reactions of subjects were compared under different oxygen partial pressures(p_(O_(2)))and air temperatures(t_(a)).The results showed that subjects’thermal sensation,thermal comfort and mean skin temperature decreased with a decrease in the oxygen partial pressure.When t_(a)=17℃,the influence of oxygen partial pressure was more pronounced,compared to p_(O_(2))=16.4 kPa,the thermal sensation of subjects under p_(O_(2))=13.7 kPa decreased by 33%.The rate of subjects feeling comfortable decreased by 25%,and the mean skin temperature decreased by 0.7℃.The hypoxic environment of the plateau exacerbates human discomfort.Therefore,it is necessary to fully understand the actual thermal requirements of sojourners in Tibet,China.The results of this study would have implications for a better understanding of thermal comfort characteristics in the hypoxia environment in plateau.

Storability of “Jonagold” Apple Fruit under Extreme Controlled Atmosphere Conditions

In two consecutive seasons, the storage capacity of “Jonagold” apple fruit was investigated under regular air (RA) and various controlled atmosphere (CA) conditions during six months at 0 ± 0.3 °C. The different CA treatment combinations were: (1) 0.5 kPa O2 + 0.5 kPa CO2, (2) 2.0 kPa O2 + 1.0 kPa CO2, (3) 1.0 kPa O2 + 3.0 kPa CO2 and (4) 0.5 kPa O2 + 6.0 kPa CO2. Ethylene production and respiration rate were evaluated at each two months storage intervals during 7 d shelf life at 20 °C. Fruit quality traits were analyzed immediately at the end of storage period and after 7 d shelf life at 20 °C. Under CA treatment, the lower the O2 and/or the higher the CO2 partial pressure, the stronger was the inhibition of the ethylene production and respiration rate of apple fruit. The 0.5 kPa O2 + 6.0 kPa CO2 CA condition induced the strongest suppression in ethylene production and consequently lower CO2 release by apple fruit. At the end of storage period, “Jonagold” apple fruit was very tolerant to all CA conditions, and any kind of internal storage disorders was observed. The storage of “Jonagold” apple at 1.0 kPa O2 + 3.0 kPa CO2 and 0.5 kPa O2 + 6.0 kPa CO2 proportionated higher flesh firmness (FF), greener skin color (SC) and higher titratable acidity (TA) either immediately after storage or after 7 d shelf life at 20 °C. Total soluble solids were not significantly affected by CA storage conditions.

Comparative analysis of time series neural network methods for three-way catalyst modeling

Relative Oxygen Level of the Three-Way Catalyst is an important parameter that affects the conversion efficiency of pollutants. ROL is a time-varying hidden state variable that is difficult to directly observe in practice. Therefore, it is common to use a method of clearing oxygen storage to simplify control in vehicles. However, this method negates the positive effects of ROL on pollutant treatment. ROL can be indirectly observed through modeling methods. Chemical modeling methods involve extensive computational requirements that cannot meet the demands of practical control. In contrast, time-series neural networks offer computational speed advantages when dealing with similar problems. Therefore, the ROL observation models using both NARX and LSTM neural networks are developed and compared in this study. The results indicate that the NARX neural network exhibits higher precision with a smaller number of neurons and time steps. The LSTM neural network demonstrates greater stability when dealing with data error fluctuations. In practical applications, the ROL model can monitor the TWC operating status and assist in the development of intelligent pollutant aftertreatment control strategies.

Low-content and highly effective zoned Rh and Pd three-way catalysts for gasoline particulate filter potentially meeting Euro 7

The next-generation Euro 7 standard proposed much lower pollutant limits from gasoline vehicles,specifically for CO and NO_(x),which would be challenging for the three-way catalysts(TWCs)utilized commercially to eliminate these pollutants.TWCs with reductive(Rh)and oxidative(Pd)active components on gasoline particulate filters(TWC on GPF)play importantly auxiliary roles in the remediation of CO and NO_(x)downstream the close coupled TWCs to meet their emission targets.Here,a low-content Rh-based TWC(0.17 wt%)zoned with a less expensive Pd-based TWC(0.29 wt%)for GPF applications(cGPF)is reported using improved colloidal deposition method.The supporting of Rh on Y-stabilized ZrO_(2)rather than on CeO_(2)-ZrO_(2)inhibits the formation of inactive Ce rhodate species,while Pd on CeO_(2)-ZrO_(2)not only guarantees the high oxygen storage capacity(OSC)but also enhances catalytic activity.The layout of the front one-fifth in volume being 0.29 wt%Pd on Ce_(0.43)Zr_(0.5)7O_(2)and the rear four-fifths being 0.17 wt%Rh on Zr_(0.85)Y_(0.15)O_(2)prevents the possible alloying of Rh with Pd.The highly effective zoned Rh and Pd TWCs show synergistic three-way activity before and after severe hydrothermal aging at 1000℃with 10%water for24 h,which could be potential choices for close coupled GPF application to satisfy the upcoming stringent emission standards,such as Euro 7 and China 6b.