oxygen scavengers
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Author(s):  
Qianqian Duan ◽  
Jialin Wang ◽  
Boye Zhang ◽  
Xiaoyuan Wang ◽  
Juanjuan Xue ◽  
...  

2021 ◽  
Author(s):  
Jussi Isokuortti ◽  
Iiro Kiiski ◽  
Tiina Sikanen ◽  
Nikita Durandin ◽  
Timo Laaksonen

The full potential of triplet fusion photon upconversion (TF-UC) of providing high-energy photons locally with low-energy excitation is limited in biomedicine and life sciences by its oxygen sensitivity. This hampers the applicability of TF-UC systems in sensors, imaging, optogenetics and drug release. Despite the advances in improving the oxygen tolerability of TF-UC systems, the evaluation of oxygen tolerability is based on comparing the performance at completely deoxygenated (0 % oxygen) and ambient (20–21 %) conditions, leaving the physiological oxygen levels (0.3–13.5 %) neglected. This oversight is not deliberate and is only the result of the lack of simple and predictable methods to obtain and maintain these physiological oxygen levels in an optical setup. Herein, we demonstrate the use of microfluidic chips made of oxygen depleting materials to study the oxygen tolerability of four different micellar nanocarriers made of FDA-approved materials with various oxygen scavenging capabilities by screening their TF-UC performance over physiological oxygen levels. All nanocarriers were capable of efficient TF-UC even in ambient conditions. However, utilizing oxygen scavengers in the oil phase of the nanocarrier improves the oxygen tolerability considerably. For example, at the mean tumour oxygen level (1.4 %), nanocarriers made of surfactants and oil phase both capable of oxygen scavenging retained remarkably 80 % of their TF-UC emission. This microfluidic concept enables faster, simpler and more realistic evaluation of, not only TF-UC, but any micro or nanoscale oxygen-sensitive system and facilitates their development and implementation in biomedical and life science applications.


Author(s):  
Yanling He ◽  
Xiaoqing Hu ◽  
Muxian Xu ◽  
Alan Man Ching Ng ◽  
Aleksandra B. Djurišić

2021 ◽  
Author(s):  
Amela Keserovic ◽  
Øystein Birketveit

Abstract Biulfite-based oxygen scavengers (OS) have been traditionally used in oilfields to reduce corrosion resulting from dissolved oxygen. Recent experience with a leakage in OS-A oxygen scavenger injection system has shown that the same production chemicals in neat form can cause corrosion themselves, specifically – crevice corrosion. In this paper a tendency of three bisulfite-based oxygen scavengers to initiate crevice corrosion on 316 stainless steel (316 SS) was evaluated by means of long-term exposure tests and short-term electrochemical techniques; cyclic potentiodynamic polarization (CPP) and Tsujikawa–Hisamatsu electrochemical method (THE). The testing was performed at ambient temperature and pressure to mimic the topside injection system conditions. The tested oxygen scavengers differed in bisulfite concentration (OS-A, 341 g/L; OS-B, 328 g/L; OS-C, 750 g/L) and pH (pH 3, 6 and 5, respectively). Two 316 SS coupons were attached together using elastomer O-rings to simulate steel-to-steel crevice between. The surface of the coupons was examined at 50x magnification after the test termination. The results presented herein showed that 30-day long exposure tests were not long or aggressive enough to provide information about the corrosivity of the chemicals in terms of crevice corrosion. Instead, the combination of short-term electrochemical techniques proved to be useful in explaining a possible cause of the leakage in OS-A injection system and allowed ranking of the products based on their tendency to initiate localized corrosion.


2021 ◽  
Author(s):  
Helena de Fátima Silva Lopes ◽  
Zhihao Tu ◽  
Hisako Sumi ◽  
Isao Yumoto

Abstract Being insoluble in the oxidize form, indigo dye must be solubilized by reduction for it to penetrate textile. One of the procedures is the reduction by natural bacterial fermentation. Sukumo, composted leaves of Polygonum tinctorium, is a natural source of indigo in Japan. Although sukumo has an intrinsic bacterial seed, the onset of indigo reduction with this material may vary greatly. Certain additives improve indigo fermentation. Here, we studied the effects of Indigofera tinctoria leaf powder (LP) on the initiation of indigo reduction, bacterial community, redox potential (ORP), and dyeing intensity in the initial stages and in aged fermentation fluids prepared with sukumo. I. tinctoria LP markedly decreased ORP at day 1 and stabilised it during early fermentation. These effects could be explained by the phytochemicals present in I. tinctoria LP that act as oxygen scavengers and electron mediators. Using next generation sequencing results, we observed differences in the bacterial community in sukumo fermentation treated with I. tinctoria LP, which was not influenced by the bacterial community in I. tinctoria LP per se. The concomitant decrease in Bacillaceae and increase in Proteinivoraceae at the onset of fermentation and the ratio of facultative to obligate anaerobes are vital to the for initiation and maintenance of indigo reduction. Hence, I. tinctoria LP improved early indigo reduction by decreasing the ORP and hasten the appropriate transitions in the bacterial community in sukumo fermentation.


2020 ◽  
Vol 14 (2) ◽  
pp. 148-157
Author(s):  
Miso Kim ◽  
Eun Hye Kim ◽  
Thi Hai Yen Pham ◽  
Tuan Anh Hoang Le ◽  
Thi Phuong Do ◽  
...  

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