Stimulating Biological Nitrification via Electrolytic Oxygenation

The feasibility of electric current prompted aerobic biodegradation of NH4+–N in an attached growth bioreactor system is demonstrated. Nitrification was induced at electric current densities of 1.25 and 2.5?mA/cm2 and with pure oxygen supplied at a rate equivalent to 1.25?mA/cm2 when the bioreactor was operated in batch mode at 6 days detention time. About 84% (27?mg/L)?NH4+–N loss was observed at the end of each detention period during all three experimental conditions, indicating that the electric current did not negatively impact the rate of nitrification. Nitrite accumulation was observed during the initial stages of nitrification experiments with 1.25?mA/cm2 current intensity, but nitrite did not accumulate during the other two sets of nitrification experiments. A mathematical model formulated to obtain the rates of biological reactions showed that rates of NH4+–N removal are similar for all aeration conditions. Abiotic experiments showed that NH4+–N was not removed electrolytically and via stripping, confirming that NH4+–N disappearance is due to biological activity.     

The effects of oxygenation aeration treatment on dissipation behaviors of tricaine mesylate in carp (Cyprinus carpio) muscle and water

Tricaine mesylate (MS-222) is one of the most used anesthetics in fish. It can be absorbed by the human body via food consumption, with related detriments to human health. In this study, a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was developed for the determination of MS-222 in carp muscle and water samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS). For cleanup procedure, multiplug filtration cleanup (m-PFC) method with n-Hexane delipidation was adopted. The extraction solvent, cleanup methods and sorbents were optimized. All method validation parameters were in the acceptable range. The dissipation behavior study was followed by the method development. Firstly, the anesthesia dose and time were optimized in application study. Secondly, carps were revived for different period of time with (experimental group) and without (control group) the oxygenation aeration treatment to compare the dissipation rate of MS-222. After being anesthetized for 6 h at 50 mg/L and 12 h of elimination, the concentrations of MS-222 in crap muscle and water of experimental group was lower than those of control group. After 36 h of elimination under oxygenation aeration, over 90% of MS-222 was dissipated in carp muscle. The results showed that the half-life of MS-222 in carp muscle was 6.2 h. The findings suggested that the commonly-used oxygenation aeration treatment in aquaculture production had potential effects in accelerating the dissipation of MS-222 in carp and water. In this study, three days of withdrawal period was recommended in carps after MS-222 administration under oxygenation aeration.     

Process Optimization of an Aerobic Upflow Sludge Blanket Reactor System

Response of an aerobic upflow sludge blanket (AUSB) reactor system to the changes in operating conditions was investigated by varying two principle operating variables: the oxygenation pressure and the flow recirculation rate. The oxygenation pressure was varied between 0 and 25?psig (relative), while flow recirculation rates were between 1,300 and 600% correspondingly. The AUSB reactor system was able to handle a volumetric loading of as high as 3.8?kg total organic carbon (TOC)/m3?day, with a removal efficiency of 92%. The rate of TOC removal by AUSB was highest at a pressure of 20?psig and it decreased when the pressure was increased to 25?psig and the flow recirculation rate was reduced to 600%. The TOC removal rate also decreased when the operating pressure was reduced to 0 and 15?psig, with corresponding increase in flow recirculation rates to 1,300 and 1,000%, respectively. Maintenance of a high dissolved oxygen level and a high flow recirculation rate was found to improve the substrate removal capacity of the AUSB system. The AUSB system was extremely effective in retaining the produced biomass despite a high upflow velocity and the overall sludge yield was only 0.24–0.32?g VSS/g TOC removed. However, the effluent TOC was relatively high due to the system’s operation at a high organic loading.     

Effect of hypolimnetic oxygenation on oxygen depletion rates in two water-supply reservoirs

Oxygenation systems, such as bubble-plume diffusers, are used to improve water quality by replenishing dissolved oxygen (DO) in the hypolimnia of water-supply reservoirs. The diffusers induce circulation and mixing, which helps distribute DO throughout the hypolimnion. Mixing, however, has also been observed to increase hypolimnetic oxygen demand (HOD) during system operation, thus accelerating oxygen depletion. Two water-supply reservoirs (Spring Hollow Reservoir (SHR) and Carvins Cove Reservoir (CCR)) that employ linear bubble-plume diffusers were studied to quantify diffuser effects on HOD. A recently validated plume model was used to predict oxygen addition rates. The results were used together with observed oxygen accumulation rates to evaluate HOD over a wide range of applied gas flow rates. Plume-induced mixing correlated well with applied gas flow rate and was observed to increase HOD. Linear relationships between applied gas flow rate and HOD were found for both SHR and CCR. HOD was also observed to be independent of bulk hypolimnion oxygen concentration, indicating that HOD is controlled by induced mixing. Despite transient increases in HOD, oxygenation caused an overall decrease in background HOD, as well as a decrease in induced HOD during diffuser operation, over several years. This suggests that the residual or background oxygen demand decreases from one year to the next. Despite diffuser-induced increases in HOD, hypolimnetic oxygenation remains a viable method for replenishing DO in thermally-stratified water-supply reservoirs such as SHR and CCR.     

c取向YBa2Cu3O7—δ超导外延膜进脱氧过程

用电阻法测量了ＹＢａ２Ｃｕ３Ｏ７－δｃ取向外延膜进脱氧过程,结果表明在氧含量变化较小的情况下,进氧、脱氧速率相近,用Ｘ射线衍射方法证明了ＹＢａ２ＣＵ３Ｏ７－δｃ取向外延膜电阻率与氧含量成指数关系,获得氧化学扩散激活能久为０．９ｅｖ。     

Thirty years of ‘quiet eye’ with etafilcon A contact lenses

Frequent replacement contact lenses made from the etafilcon A hydrogel lens material were introduced onto the market over 30 years ago, and etafilcon A remains the most widely used hydrogel lens material today. Although the prescribing of silicone hydrogel lenses is increasing, millions of lens wearers globally have been wearing hydrogel lenses for many years and exhibit a physiologically-stable ‘quiet eye’, with a low profile of adverse events. Hydrogel lenses are demonstrated to maintain a low inflammatory response and infection risk profile during daily wear, which in the case of etafilcon A, may be related to its low modulus, and the naturally-protective, anti-microbial, non-denatured lysozyme absorbed into the lens from the tear fluid. Although improved corneal physiology from decreased hypoxia with silicone hydrogel lenses is well accepted, equivalent levels of corneal oxygenation are maintained during daily wear of low to medium powered hydrogel lenses, which do not impede the daily corneal de-swelling process, and do not induce clinically significant changes in ocular health. Therefore, hydrogel lenses remain an important alternative for daily wear in modern contact lens practice.     

Anaerobic Treatment of High Sulfate Wastewater with Oxygenation to Control Sulfide Toxicity

In this study, oxidation-reduction potential (ORP) was employed to regulate oxygen dosing for online sulfide toxicity control during anaerobic treatment of high sulfate wastewater. The experiment was conducted in an upflow anaerobic filter, which was operated at a constant influent total organic carbon of 6,740 mg/L [equivalent to a chemical oxygen demand (COD) of 18,000 mg/L], but with different influent sulfates of 1,000, 3,000, and 6,000 mg/L. The reactor was initially run at natural ORP (the system’s ORP without oxygenation) of about ?290 to ?300?mV and then was followed by oxygenation to raise ORP by +25?mV above the natural level for each influent sulfate level. At 6,000 mg/L sulfate under the natural ORP, methanogenesis was severely inhibited due to sulfide toxicity, and the anaerobic process was almost totally upset. Upon oxygenation by raising ORP to ?265?mV, the dissolved sulfide was quickly reduced to 12.2 mg S/L with a concomitant improvement in methane yield by 45.9%. If oxygen was not totally used up by sulfide oxidation, the excess oxygen was consumed by facultative bacteria which had been found to stabilize about 13.5% of the influent COD. Both sulfide oxidation and facultative activity acted as a shield to protect the anaerobes from an excessive oxygen exposure. This study showed that direct oxygenation of the recirculated biogas was effective to oxidize sulfide, and the use of ORP to regulate the oxygen dosing was practical and reliable during anaerobic treatment of high sulfate wastewater.     

Effect of oxidised phenolic compounds on the gel property of mackerel (Rastrelliger kanagurta) surimi

The effects of different oxidised phenolic compounds (ferulic acid, OFA; tannic acid, OTA; catechin, OCT and caffeic acid, OCF) at different levels (0-0.60% of protein content) on the properties of gels from mackerel (Rastrelliger kanagurta) surimi were investigated. Gels with addition of 0.40% OFA, 0.50% OTA, 0.50% OCF or 0.10% OCT had increases in breaking force by 45%, 115%, 46.1% and 70.3% and in deformation by 12.2, 27.5, 28.1 and 28.4%, respectively, compared with the control (without addition of oxidised phenolics). Lowered expressible moisture content without any change in the whiteness of resulting gels was found. Slightly lower myosin heavy chain (MHC) band intensity of gels added with oxidised phenolics at the optimal level was noticeable compared with that of the control. A sensory evaluation study indicated that addition of oxidised phenolic compounds had no negative impact on the colour and taste of the resulting gels (P > 0.05). Gels with addition of all oxidised phenolics had a finer matrix with smaller strands.     

山核桃加工过程脂肪酸氧化及抗氧化能力变化研究

试验选取浙江临安山核桃加工过程样品。研究了山核桃原料脂肪酸组成和相对质量分数以及加工过程中4种主要脂肪酸氧化规律及抗氧化能力变化情况。结果表明:山核桃脂肪酸组分共确认13种,其中油酸(C18∶1)、亚油酸(C18∶2)、棕榈酸(C16∶0)、亚麻酸(C18∶3)为山核桃中最主要的4种脂肪酸;加工过程4种主要脂肪酸含量均呈缓慢下降趋势,其中亚油酸、亚麻酸在蒸煮阶段下降速度最快,棕榈酸则在第一次炒制阶段含量下降最快;蒸煮工序对抗氧化能力影响最大;山核桃细胞脂滴在蒸煮后即发生破裂,之后随着加工过程扩散融合。试验结果显示山核桃脂肪酸氧化在加工过程持续发生,长时间高温促进氧化加剧,自身抗氧化能力则逐渐下降,细胞结构破坏。     

Biosynthesis of Oxylipins by Rhizoctonia solani with Allene Oxide and Oleate 8S,9S‐Diol Synthase Activities

Oxylipin biosynthesis by fungi is catalyzed by both the lipoxygenase (LOX) family and the linoleate diol synthase (LDS) family of the peroxidase‐cyclooxygenase superfamily. Rhizoctonia solani, a pathogenic fungus, infects staple crops such as potato and rice. The genome predicts three genes with 9–13 introns, which code for tentative dioxygenase (DOX)–cytochrome P450 fusion enzymes of the LDS family, and one gene, which might code for a 13‐LOX. The objective was to determine whether mycelia or nitrogen powder of mycelia oxidized unsaturated C₁₈ fatty acids to LDS‐ or LOX‐related metabolites. Mycelia converted 18:2n‐6 to 8R‐hydroxy‐9Z,12Z‐octadecadienoic acid and to an α‐ketol, 9S‐hydroxy‐10‐oxo‐12Z‐octadecenoic acid. In addition to these metabolites, nitrogen powder of mycelia oxidized 18:2n‐6 to 9S‐hydroperoxy‐10E, 12Z‐octadecadienoic, and 13S‐hydroperoxy‐9Z,11E‐octadecadienoic acids; the latter was likely formed by the predicted 13‐LOX. 18:1n‐9 was transformed into 8S‐hydroperoxy‐9Z‐octadecenoic and into 8S,9S‐dihydroxy‐10E‐octadecenoic acids, indicating the expression of 8,9‐diol synthase. The allene oxide, 9S(10)epoxy‐10,12Z‐octadecadienoic acid, is unstable and decomposes rapidly to the α‐ketol above, indicating biosynthesis by 9S‐DOX‐allene oxide synthase. This allene oxide and α‐ketol are also formed by potato stolons, which illustrates catalytic similarities between the plant host and fungal pathogen.