灰铸铁铁水活性氧量的测定与分析

用浓差电池测氧装置测试铁水中的活性氧量,可对该铁水的冶金特性和它对铸铁的内在质量的影响有所了解,为正确制定熔炼工艺指明方向。

Comparison of Fe^(2+) oxidation by Acidithiobacillus ferrooxidans in rotating-drum and stirred-tank reactors

Fe2＋ oxidation by Acidithiobacillus ferrooxidans（At.ferrooxidans） under different solid contents by adding inert Al2O3 powder was examined in rotating-drum and stirred-tank reactors.The results show that the bioactivity of At.ferrooxidans in the stirred-tank is higher than that in the rotating-drum in the absence of Al2O3 powder,but the biooxidation rate of Fe2＋ decreases markedly from 0.23 g/（L·h） to 0.025 g/（L·h） with increasing the content of Al2O3 powder from 0 to 50%（mass fraction） in the stirred-tank probably due to the deactivation of At.ferrooxidans resulting from the collision and friction of solid particles.The increase in Al2O3 content has a little adverse effect on the bioactivity of At.ferrooxidans in the rotating-drum due to different mixing mechanisms of the two reactors.The biooxidation rate of Fe2＋ in the rotating-drum is higher than that in the stirred-tank at the same content of Al2O3 powder,especially at high solid content.The higher bioactivity of At.ferrooxidans can be maintained for allowing high solid content in the rotating-drum reactor,but its application potential still needs to be verified further by the sulfide bioleaching for the property differences of Al2O3 powder and sulfide minerals.

Science Letters:Alterations in seedling vigour and antioxidant enzyme activities in Catharanthus roseus under seed priming with native diazotrophs

An experiment was conducted on Catharanthus roseus to study the effect of seed treatments with native diazotrophs on its seedling growth and antioxidant enzyme activities. The treatments had significant influence on various seedling parameters. There is no significant influence on dry matter production with the diazotrophs, Azospirillum and Azotobacter. However, the vital seedling parameters such as germination percentage and vigour index were improved. Azotobacter treatment influenced maximum of 50% germination, whereas Azospirillum and Azotobacter were on par with C. roseus with respect to their vigour index. There was significant difference in the population of total diazotrophs. Azospirillum and Azotobacter between rhizosphere and non-rhizosphere soils of C. roseus had the same trend and were observed at various locations of the study. The activities of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POX) and catalase (CAT) were increased to a significant extent due to the treatment with diazotrophs.

Physiological characteristics of Ficus tikoua under antimony stress

A greenhouse culture experiment was used to evaluate the effects of antimony(Sb)stress on Ficus tikoua(F.tikoua).Theresults showed that the growth of F.tikoua leaves was significantly inhibited when Sb concentration was higher than30μmol/L,andno significantly inhibitory effect of Sb on the roots and stems of F.tikoua was found in all the treatments,implying that leaves weremore sensitive to Sb toxicity than roots and stems.Antimony concentration in the roots was higher than that in the stems and leaves.To reduce reactive oxygen species(ROS)level in the F.tikoua,the activities of superoxide dismutase(SOD),peroxidase(POD)andcatalase(CAT)increased with Sb treatments,but the SOD and CAT were more early active than POD.Although the decrease ofchlorophyll content with high Sb treatments(450μmol/L)was observed at the end of the experiments,the positive impact onchlorophyll content was observed with all the Sb treatments at the early period.No significant difference of the maximum quantumefficiency of PSII and quantum yield of PSII electron transport values with different Sb treatments was observed at the end of thisexperiment,suggesting that the photosynthesis was not inhibited with Sb concentration below450μmol/L.The results implied acertain tolerance to Sb stress for F.tikoua.This meets the essential condition for utilization in Sb contamination environments.

Precisely Controlled Synthesis of Pt-Pd Octahedral Nanoframes as a Superior Catalyst towards Oxygen Reduction Reaction

Pt-based nanoframes represent a class of promising catalysts towards oxygen reduction reaction. Herein, we, for the first time, successfully prepared Pt-Pd octahedral nanoframes with ultrathin ridges less than 2 nm in thickness. The Pt-Pd octahedral nanoframes were obtained through site-selected deposition of Pt atoms onto the edge sites of Pd octahedral seeds, followed by selective removal of the Pd octahedral cores via chemical etching. Due to that a combination of three-dimensional opens geometrical structure and Pt-skin surface compositional structure, the Pt-Pd octahedral nanoframes/C catalyst shows a mass activity of 1.15 A/mgPt towards oxygen reduction reaction, 5.8 times enhancement in mass activity relative to commercial Pt/C catalyst （0.20 A/mgPt）. Moreover, even after 8000 cycles of accelerated durability test, the Pt-Pd octahedral nanoframes/C catalyst still exhibits a mass activity which is more than three times higher than that of pristine Pt/C catalyst.

Effects of Nitrate Concentration in Main Anoxic Zone on Denitrifying Dephosphatation

The effects of nitrate concentration in the main anoxic zone on denitrifying dephosphatation capability were conducted based on modified University of Cape Town （MUCT） process. Meanwhile the relation between optimal nitrate concentration （Nopt） and influent C/N ratio was evaluated, in which the influont chemical oxygen demand （COD） concentration was stabilized at （2905：10）mg/L, the influent total phosphorus （TP） concentration was stabilized at （7.0±0. 5）mg/L. The results indicated that： （1） the nitrate concentration in the main anoxic zone had an effect on denitrifying dephosphatation capability, and the average percentages of anoxic phosphorus uptake in total phosphorus uptake （ηa） increased with nitrate cancentration increasing, i.e., increasing from 62.1% at2.0 mg/L to63.7%, 65.6%, 68.1%, and 72.3% at 2.2, 2.4, 2.6 and 2.8mg/L, respectively; （2） the Nopt as function of influent C/N ratio could be calculated by the equation： y = 0.67x^2-7.79x ＋ 22. 21; the maximum percentages of anoxic phosphorus uptake in total phosphorus uptake （ηa,max） as function of the Nopt could be calculated by the equation： y=0.77-0.33e^-（x/1.52）. The Nopt was the important control parameter that must be optimized for operation of conveational biological nutrieat removal activated sludge （BNRAS） system.

Antioxidation Activities of Low-Molecular-Weight Gelatin Hydrolysate Isolated from the Sea Cucumber Stichopus japonicus

Gelatin extracted from the body wall of the sea cucumber （Stichopus japonicus） was hydrolyzed with flavourzyme. Low-molecular-weight gelatin hydrolysate （LMW-GH） of 700-- 1700 Da was produced using an ultrafiltration membrane bioreaetor system. Chemiluminescence analysis revealed that LMW-GH scavenges high free radicals in a concentration-dependent manner; IC50 value for superoxide and hydroxyl radicals was 442 and 285 μgmL-1, respectively. LMW-GH exhibited excellent inhibitory characteristics against melanin synthesis and tyrosinase activity in B16 cells. Furthermore, LMW-GH notably increased in- traeellular glutathione （GSH）, which in turn suppressed melanogenesis. LMW-GH performs antioxidation activity, holding the potential of being used as a valuable ingredient in function foods, cosmetics and pharmaceuticals or nutriceuticals.

Studies on the Effects on Growth and Antioxidant Responses of Two Marine Microalgal Species to Uniconazole

Uniconazole, as a plant growth retardant, can enhance stress tolerance in plants, possibly because of improved antioxidation defense mechanisms with higher activities of superoxide dismutase(SOD) and peroxidase(POD) enzymes that retard lipid peroxidation and membrane deterioration. These years much attention has been focused on the responses of antioxidant system in plants to uniconazole stress, but such studies on aquatic organism are very few. Moreover, no information is available on growth and antioxidant response in marine microalgae to uniconazole. In this paper, the growth and antioxidant responses of two marine microalgal species, Platymonas helgolandica and Pavlova viridis, at six uniconazole concentrations(0-15 mg L-1) were investigated. The results demonstrated that 3 mg L-1 uniconazole could increase significantly chlorophyll a and carbohydrate contents of P. helgolandica(P < 0.05). Higher concentrations(≥12 mg L-1) of uniconazole could inhibit significantly the growth, dry weight, chlorophyll-a and carbohydrate contents of P. helgolandica and P. viridis(P < 0.05). Uniconazole caused a significant increase in lipid peroxidation production(MDA) at higher concentrations(≥ 9 mg L-1). The activities of antioxidant enzymes, superoxide dismutase(SOD) and catalase(CAT) were enhanced remarkably at low concentrations of uniconazole. However, significant reduction of SOD and CAT activities was observed at higher concentrations of uniconazole.

Study on the Molecular Weight Composition and Antioxidant Activity of Peanut Bioactive Peptides

[ Objective] To prepare peanut bioactive peptides and analyze their molecular weight composition and antioxidant activity. [ Method ] The dialysis bag of 8.0, 3.5 and 1.0 kD were used to classify the hydrolyzate derived from alcalase and flavourzyme, peanut bioactive poptides of differ-ent molecular weight were obtained and then their scavenging capacity of free radicals was measured. The molecular weight composition was stud-ied by Tricine-SDS-PAGE.[Result] The content of peptides 〈 1.0 kD were 76.21% and 83.42% in the total hydrolyzate from alcalase and fla-vourzyme respectively. All hydrolyzate with different molecular grades showed free radical scavenging capacity, which was increased with the reduc- tion of molecular mass. The peptides 〈 1.0 kD exhibited higher radical scavenging capacity of （87.41 ±0.66） % （alcalase） and （67.88 ±0.48）% （ flavourzyme）, respectively. [ Conclusion] Peanut bioactive peptides had strong effect of antioxidant capacity, especially that 〈 1.0 kD, which had great prospect.

The Enhancement of CO2 Chemical Absorption by K2CO3 Aqueous Solution in the Presence of Activated Carbon Particles

The enhancement of chemical absorption of CO2 by K2CO3/H2O absorbents in the presence of activated carbon （AC） particles was investigated. The results show that the gas absorption rates can be enhanced significantly in the presence of AC particles, and the maximum enhancement factor 3.7 was observed at low stirring intensities. The enhancement factor increased rapidly with the solid loading during the initial period of absorption and then be- came mild gradually to a maximum value. Both the liquid-solid contact area and the probability of solid particles residing at the gas-liquid interface decreased with the increase of the particle size, leading to a negative effect on the enhancement of mass transfer. The influence of the particles on gas absorption decreased with the reaction rate. The stirring speed changed the interfacial coverage and mass transfer rate on the liquid side and consequently affected the mass transfer between the gas and liquid phases; the enhancement factor decreased with the stirring intensity. A heterogeneous two-zone model was proposed for predicting the enhancement factor and the calculated results agreed well with the experimental data.

Optimization of Extraction Process of Olive Leaves by RSM and Evaluation of Antioxidant Capacity Measurements to the Mixtures

Water extracts prepared from seven varieties of olive leaves native to the Mediterranean area but planted in Sichuan province, P.R. China, namely Frantoiao, Leccio, Ezhi, Picholine, Pendollino, Chenggu and Huaou 9#, were examined for their total phenonic and flavonoid contents, antioxidant capacity. Total phenolic and flavonoid content were measured by Folin-Ciocalteu method and a colorimetric method, respectively. ABTS＋ method and FRAP were used for examining antioxidant activity. Response surface methodology （RSM） was used for optimizing the extract condition. Under the optimum condition, the total phenolic and flavonoid content of aqueous extracts of the dry olive leaves （DOL） ranged from 40.27 to 56.58 mg gallic acid （GAE）/g DOL and 21.59 to 33.72 mg catechin （CE）/g DOL in June, 34.31 to 52.81 mg GAE/g DOL and 17.11 to 23.53 mg CE/g DOL in November. The ABTS＋ method and FRAP ranged from 0.23 to 0.35 mmol trolox （TE）/g DOL and 313.01 to 409.69 μmol Fe2＋/g DOL in June, 0.19 to 0.30 mmol TE/g DOL and 254.69 to 418.10 pmol Fe2＋/g DOL in November. Our results revealed that the total phenolic and flavonoid, or antioxidant capacity of the water extract were higher in June than November. Moreover, it was noticed that the antioxidant activity depends on the flavonoid and phenolic.

Influence of Nonionic Surfactant Addition on Drag Reduction of Water Based Nanofluid in a Small Diameter Pipe

The goal of this research was to determine the impact of nonionic surfactants on drag reduction effect in water and metal oxide nanofluid. Two nonionic surfactants （Rokacet 07 and Rokanol KT） and copper（II） oxide wa- ter-based nanofluid were examined. Friction factors in a 4 mm diameter pipe for the Reynolds number between 8000 and 50000 were determined. Results showed that addition of nonionic surfactants caused the decrease of fric- tion factor in water and nanofluid. The drag reduction effect was similar in both cases. Presence of nanoparticles in the system has no great influence on drag reduction effect.

Effect of BEDGEN 40 on Growth, Anti-Oxidant Activity and Resistance against Aeromonas Hydrophila Infection in Tilapia （Oreochromis niloticus x O. aureus）

The globe artichoke has become important as a medicinal herb in recent years following the discovery of cynarin. This bitter-tasting compound, which is found in the leaves, improves liver and gall bladder function, stimulates the secretion of digestive juices, especially bile, and lowers blood cholesterol levels. The leaves are anticholesterolemic, antirheumatic, cholagogue, digestive, diuretic, hypoglycaemic and lithontripic. BEDGEN 40 , a compound made with Cynara scolymus L. （artichoke） extract and choline chloride was evaluated for growth performance and anti-oxidant activity in tilapia. There were four treatment groups; group 1 was fed only with a basal diet and served as the control, group 2 - 4 were experimental groups that received 150, 300, or 600 mg/kg BEDGEN 40 , respectively, added to the basal diet and fed for 8 weeks. The results showed signifi- cant differences for weight gain, feed conversion, and protein efficiency in fish diets containing 150, 300, or 600 mg/kg BEDGEN 40 compared to the control. Generally, BEDGEN 40 improved the body condition factor and hepatosomatic index of tilapia, and reduced liver fat content. Fish consum- ing BEDGEN 40 also exhibited improved liver antioxidant status. BEDGEN 40 （300, or 600 mg/kg） was also found to significantly reduce the mortality of tilapia subsequently challenged with Aeromonas hydrophila.

Experimental Research on Coke Wastewater Treatment by Hybrid Biological Reactor

Phase hybrid biological reactor （HBR） was used in treating coke wastewater by adding submerging fiber-ball fillers in suspended growth activated sludge. The optimum operation parameters for the highest performance were determined. It was found that the hybrid biological reactor worked well for the coke wastewater treatment in terms of Chemical Oxygen Demand （COD）, NH4＋ -N and other refractory organic compounds removal efficiencies. Compared with conventional activated sludge system, the removal rate of COD and NH4＋ -N and the nitrating rate were higher and more stable in the hybrid biological reactor. COD of effluent was less than 75 mg/L and the removal rate of COD and NH4＋ -N could be up to 95.0% and 92.5% when COD of influent and NH4＋ -N were less than 700 mg/L and 300 rag/L, respectively. In this way, the quality of effluent concentration could reach the first class of integrated wastewater discharge standard （GB8978-1996） （COD ≤100 mg/L）.

Detection and Quantitative Analysis of Dominant Bacteria On Aging Flue-cured Tobacco Leaves

[Objective] The aim was to construct the internal motivation of flued-cured tobacco natural aging. [Method] The variation of DNA copies of Bacillus megaterium, amylase activity, PPO, peroxydase and content of starch, neutro-protein, polyphenol in different aging period were investigated using Henan flue-cured tobacco leaves. [Result] Results showed that the DNA copies of Bacillus megaterium increased initially but decreased subsequently with the aging time. The DNA copies of Bacillus per gram of tobacco leaf surface reached the maximum number at 6 months aging. The activities of four enzymes showed the same variation trend as in DNA copies, and also reached the highest level at 6 months aging. Chemical ingredients, however, displayed a downward trend. The variation of enzyme activity and content of chemical composition were reflected in the changes of DNA copies in Bacillus megaterium. [Conclusion] The result indicate that Bacillus megaterium was the internal motivation of flue-cured tobacco natural aging.

Variations of antioxidant enzyme activity and malondialdehyde content in nemertean Cephalothrix hongkongiensis after exposure to heavy metals

The antioxidant enzyme activity and malondialdehyde(MDA) content of Cephalothrix hongkongiensis were studied to assess variations in the biochemical/physiological parameters of nemerteans under heavy metal stress.Worms were exposed to copper,zinc and cadmium solutions at different concentrations,and the activity of three antioxidant enzymes,catalase(CAT),superoxide dismutase(SOD),and glutathione peroxidase(GPX),and MDA content were measured.The results show that the activity of each enzyme changed immediately after exposure to heavy metals.CAT was invariably inhibited throughout the experimental period,while the SOD activity was significantly elevated by exposure to Cu^(2+) for 48h,but then decreased.SOD was inhibited by Zn^(2+) during the first 12h of exposure,but activated when exposed for longer periods.Under Cd^(2+) stress,SOD activity decreased within 72h.GPX activity varied greatly,being significantly increased by both Cu^(2+) and Zn^(2+),but significantly inhibited by Cd^(2+) in the first 12-24h after exposure.MDA content increased on Cu^(2+) exposure,but normally decreased on Zn^(2+) exposure.MDA content followed an increase-decrease-increase pattern under Cd^(2+) stress.In conclusion,the antioxidant system of this nemertean is sensitive to heavy metals,and its CAT activity may be a potential biomarker for monitoring heavy metal levels in the environment.

Experimental study on zero excess sludge production process with ozonation unit in MBR process

In order to investigate the influence factors of zero excess activated sludge (EAS) process by ozonation, a 100 L membrane bioreactor coupled with a sludge ozonation unit (MBR-SO) was performed for 80 d without EAS wasting. Some mathematical models were developed to elucidate the relationship between process parameters and the operating effects. It is considered that the sludge lysing ratio (ξ), produced COD per unit mass lysed MLSS (η), observed sludge yield coefficient (Yobs) and intrinsic yield coefficient for COD produced by lysed sludge (Y2) significantly affect the flowrate to ozonation unit (q). When q is 0.0067 times of influent flowrate (Q) and ξ is about 0.72 for each batch ozonation, a relatively stable MLSS concentration of 8168 mg/L and zero Yobs are achieved in the MBR-SO system. The calculation of sludge disintegration number indicates that the high ξ can apparently decrease the sludge amount needed for ozonation. At the same ozone dose, the low input ozone concentration and high flowrate can enhance the sludge lysing effects and a low energy consumption of 0.041 Yuan/m3 wastewater is obtained.

Effects of Boscalid on the Antioxidant Enzyme System of Adult Zebrafish (Danio rerio)

Abstract [Objective] This study was conducted to evaluate the ecotoxicity of boscalid to adult zebrafish （Danio rerio）. [Method] The activities of antioxidant enzymes superoxide dismutase （SOD）, catalase （CAT）, peroxidase （POD）, glutathione peroxidase （GPx）, as well as a non-enzymatic antioxidant malondialdehyde （MDA）, in the liver were measured 3, 7, 14 and 21 d post exposure （dpe） to 0.02 （1/100 of acute toxicity）, 0.036 （monitored concentration）, 0.08 （1/20 of acute toxicity）, 0.16 （1/10 of acute toxicity） and 0.32 mg/L （1/5 of acute toxicity） boscalid using a semi-static method. [Result] SOD, CAT, POD, GPx and MDA activity in the liver of zebrafish varied with boscalid concentration and exposure time. Boscalid significantly enhanced MDA content at 21 dpe. A significant upregulation of the activity of SOD, CAT, POD and GPx at 7 dpe was observed, suggesting that boscalid resulted in oxidative stress and lipid peroxidation. [Conclusion] These results show that these biomarkers are all appropriate for monitoring oxidative stress and the lipid peroxidation status of fish after exposure to boscalid. Key words Boscalid; Zebrafish; Antioxidant enzyme

Intervarietal Variation in Proximate Composition and Antioxidant Potential of Dry Peas （Pisum sativum L）

The present research work was carried out to investigate the proximate composition and antioxidant capacities of newly invented varieties of dry peas. The proximate composition in terms of moisture （7.00-8.50%）, ash （3.85-4.97%）, fiber （3.8-12.3%） and protein （17.3-18.8%） contents varied significantly with respect to various cultivars. Total phenolic contents （TPC）, total flavonoids contents （TFC）, percentage inhibition of peroxidation of linoleic acid system, reducing power and DPPH free radical scavenging capacity of different dry peas extracts were found in range of 0.651-0.684 g/100g of GAE, 0.021-0.041 g/100g of CE, 0.713-0.895, 40.051-84.608%, 18.097-24.591 mg/mL, respectively. The amount of TFC, and percent inhibition of per oxidation in linoleic system of different dry peas extracts varied significantly among various cultivars and solvents. From the results of present investigations it is reasonable to say that 80% methanolic extracts of dry peas have exhibited varying degree of antioxidant activity.

Study on the Effective Components in Pomegranate Leaf and Extraction Method

Experimental results show that, all the sample of seasonal-temperature combinations, the effective component content is highest in November to collect leaves in the 25%; drying, and the strongest antioxidant activity. The results of this study will provide theoretical basis for the preparation process of pomegranate leaf tea. Results of the correlation between antioxidant activity and the effective components show that the antioxidant activity of pomegranate leaves is closely related to polyphenol content, in particular had significant correlation with the content of tannin polyphenols, flavonoids, and ellagic acid content had no significant correlation.