基于第一性原理的水氧相互作用下混凝土中钢筋锈蚀机理研究

为了阐明水氧相互作用下钢筋锈蚀的机理,采用基于第一性原理的密度泛函理论,建立了O2分子和H2O分子在Fe(100)表面的吸附模型,研究分析了各吸附体系的吸附能、几何结构和电荷变化.结果表明,H2O分子与清洁Fe(100)表面之间是弱的物理吸附作用,而在Fe(100)表面预先吸附O2分子,可通过氢键作用促进后续H2O分子的吸附;O2分子在预吸附H2O分子的Fe(100)表面上的吸附是很强的化学吸附作用.由此可见,相比于H2O分子单独作用于铁表面,H2O和O2分子相互作用对铁表面腐蚀的影响更大,从微观尺度证明了与水下区相比,处于干湿交替环境的浪溅区混凝土结构中钢筋的腐蚀更为严重。

Hydration transformation behaviors of CO_(2) and excellent anti-inflammatory activity on RAW 264.7 cell

Skin care products with carbonic acid(H_(2)CO_(3))have gained extensive attention worldwide.However,the conversion of CO_(2) to H_(2)CO_(3) is not stable,and the mechanism of the effect of H_(2)CO_(3) on skin care has not been clearly proved.The hydration-dissolution behaviors of CO_(2) were investigated under different temperature,pH,and pressure conditions.Moreover,based on the phenomenon of CO_(2) hydration transformation,the inflammatory effect of CO_(2) hydrate on macrophages(RAW 264.7)was investigated.The result shows that the increase in temperature weakened the hydration of CO_(2),and the increase in pH and pressure both promoted the water-phase transformation of CO_(2).When pH<6,CO_(2) reacts with water to generate H_(2)CO_(3).When pH was between 6-7,the prompt solution was a mixture of H_(2)CO_(3) and HCO_(3)^(-).When the pH was between 7-9,they mainly generated HCO_(3)^(-).And when pH>9,CO_(2) solubility mainly converts to CO_(3)^(2-).Besides,CO_(2) can inhibit the secretion of inflammatory factors by RAW 264.7 cells by inhibiting the phosphorylation of the p38 protein.CO_(2) hydrate inhibited the expression of pro-inflammatory factors IL-6,TNF-α,and up-regulated the expression of anti-inflammatory factor IL-10.Furthermore,the anti-inflammatory molecular mechanism of CO_(2) hydration inhibited the MAPK signaling pathway by inhibiting the phosphorylation of p38.The hydration-dissolution behavior of CO_(2) was investigated.This work revealed the anti-inflammatory bioeffect of CO_(2) hydrate,providing a theoretical basis and application support for CO_(2) skin care products.

不同热-氧-水老化条件对Evotherm温拌橡胶沥青性能的影响

为了研究热-氧-水综合老化作用对Evotherm温拌橡胶沥青性能的影响,文章通过不同热-氧-水老化条件对Evotherm温拌橡胶沥青的作用,采用针入度试验、延度试验、软化点试验、弹性恢复试验以及布氏旋转黏度试验进行老化前后性能评价。试验结果显示,在热、氧的共同作用下,水分的存在会加速Evotherm温拌橡胶沥青的老化;液态水和气态水的存在都会使Evotherm温拌橡胶沥青的针入度减小,但液态水的作用更加明显;热-氧-水浸老化后的5℃低温延度比热-氧-水浸老化的好,热-氧-水蒸气老化的15℃、25℃延度比热-氧-水浸老化的好;热-氧-水浸老化和热-氧-水蒸气老化均可提高Evotherm温拌橡胶沥青的黏度,但热-氧-水浸老化后黏度增长更快;在热-氧-水综合老化作用下,Evotherm温拌橡胶沥青的温度敏感性会下降,热-氧-水蒸气老化15h的温度敏感性最小。

A hydrated amorphous iron oxide nanoparticle as active water oxidation catalyst

Developing efficient water oxidation catalysts(WOCs)with earth‐abundant elements still remains a challenging task for artificial photosynthesis.Iron‐based WOC is a promising candidate because it is economically cheap,little toxic and environmentally friendly.In this study,we found that the catalytic water oxidation activity on amorphous iron‐based oxide/hydroxide(FeOx)can be decreased by an order of magnitude after the dehydration process at room temperature.Thermogravimetric analysis,XRD and Raman results indicated that the dehydration process of FeOx at room temperature causes the almost completely loss of water molecule with no bulk structural changes.Based on this finding,we prepared hydrated ultrasmall(ca.2.2 nm)FeOx nanoparticles of amorphous feature,which turns out to be extremely active as WOC with turnover frequency(TOF)up to 9.3 s^-1 in the photocatalytic Ru(bpy)3^2+‐Na2S2O8 system.Our findings suggest that future design of active iron‐based oxides as WOCs requires the consideration of their hydration status.

Nitrous Oxide Production in a Sequence Batch Reactor Wastewater Treatment System Using Synthetic Wastewater

The rate of nitrous oxide emission from a laboratory sequence batch reactor （SBR） wastewater treatment system using synthetic wastewater was measured under controlled conditions. The SBR was operated in the mode of 4 h for aeration, 3.5 h for stirring without aeration, 0.5 h for settling and drainage, and 4 h of idle. The sludge was acclimated by running the system to achieve a stable running state as chemical oxygen demand, NO2^-, NO3^-, NH4^＋, pH, and N2O. indicated by rhythmic changes of total N, dissolved oxygen, Under the present experimental conditions measured nitrous oxide emitted from the off-gas in the aerobic and anaerobic phases, respectively, accounted for 8.6%-16.1% and 0-0.05% of N removed, indicating that the aerobic phase was the main source of N2O emission from the system. N2O dissolved in discharged water was considerable in term of concentration. Thus, measures to be developed for the purpose of reducing N2O emission from the system should be effective in the aeration phase.

Iron-based binary metal-organic framework nanorods as an efficient catalyst for the oxygen evolution reaction

First-row transition metal compounds have been widely explored as oxygen evolution reaction(OER)electrocatalysts due to their impressive performance in this application.However,the activity trends of these electrocatalysts remain elusive due to the effect of inevitable iron impurities in alkaline electrolytes on the OER;the inhomogeneous structure of iron-based(oxy)hydroxides further complicates this situation.Bimetallic metal-organic frameworks(MOFs)have the advantages of well-defined and uniform atomic structures and the tunable coordination environments,allowing the structure-activity relationships of bimetallic sites to be precisely explored.Therefore,we prepared a series of iron-based bimetallic MOFs(denoted as Fe_(2)M-MIL-88B,M=Mn,Co,or Ni)and systematically compared their electrocatalytic performance in the OER in this work.All the bimetallic MOFs exhibited higher OER activity than their monometallic iron-based counterpart,with their activity following the order FeNi>FeCo>FeMn.In an alkaline electrolyte,Fe2Ni-MIL-88B showed the lowest overpotential to achieve a current density of 10 mA cm^(–2)(307 mV)and the smallest Tafel slope(38 mV dec^(–1)).The experimental and calculated results demonstrated that iron and nickel exhibited the strongest coupling effect in the series,leading to modification of the electronic structure,which is crucial for tuning the electrocatalytic activity.

Inactivation of Chironomid Larvae with Chlorine Dioxide and Chlorine

Chironomid larvae propagate prolifically in eutrophic water body and they cannot be exterminated by conventional disinfection process. The inactivation effects of chlorine and chlorine dioxide on Chironomid larvae were investigated and some bourdary values in practice were determined under .conditions of various oxidaat dosage, organic precursor concentmtion and pH value. In addition, removal effect of different pre-oxidation cambined with coagulation process on Chironomid larvae in raw water was evaluated. It was found that chlorine dioxide possessed better inactivation effect than chlorine. Complete inactivation of Chironomid larvae in raw water was resulted by 1.5 mg/L of chlorine dioxide with 30 min of contact ＇time. Additionally, the organic precursor concentration, pH value had little influence on the inactivation effect. The coagulation jar test showed that Chironomid larvae in the raw water could be completely removed by chlorine dioxide pre-oxidation in combination with the coagulation process at chlorine dioxide dosage of 0.8 mg/L.

String and Ball-Like TiO_2/rGO Composites with High Photo-catalysis Degradation Capability for Methylene Blue

Novelthree-dimensionalstring and ball-like titanium dioxide/reduced graphene oxide, TiO_2/rGO(STG) composites were prepared using a one-step hydrolysis process followed by a low-temperature hydrothermaltreatment. The STG composites exhibited excellent photo-catalytic degradation performance for methylene blue owing to a good synergistic effect between TiO_2 and rGO. The STG composites with 1.0 wt% of rGO loading exhibited the highest removalrate of 86.0% for methylene blue and its reaction rate constant(5.27 × 10^(-3) min^(-1)) was much higher than those of pure string and ball-like TiO_2(ST). In addition, the STG composites also showed an outstanding capability for the photo-catalysis degradation of other cationic dyes. In addition, a possible photo-catalytic degradation mechanism for the STG composite was postulated, in which~?O_2^- and~·OH were the main oxidizing groups. This work of fers new insights into a better design and preparation of novelcomposite materials for the removalof organic dyes.

Buffer anion effects on water oxidation catalysis: The case of Cu(Ⅲ) complex

Water oxidation is the bottleneck of artificial photosynthesis.Since the first ruthenium-based molecular water oxidation catalyst,the blue dimer,was reported by Meyer’ s group in 1982,catalysts based on transition metals have been widely employed to explore the mechanism of water oxidation.Because the oxidation of water requires harsh oxidative conditions,the stability of transition complexes under the relevant catalytic conditions has always been a challenge.In this work,we report the redox properties of a CuⅢ complex(TAML-CuⅢ] with a redox-active macrocyclic ligand(TAML) and its reactivity toward catalytic water oxidation.TAML-CuⅢ displayed a completely different electrochemical behavior from that of the TAML-CoⅢ complex previously reported by our group.TAML-CuⅢ can only be oxidized by one-electron oxidation of the ligand to form TAML·+-CuⅢand cannot achieve water activation through the ligand-centered proton-coupled electron transfer that takes place in the case of TAML-CoⅢ.The generated TAML·+-CuⅢ intermediate can undergo further oxidation and ligand hydrolysis with the assistance of borate anions,triggering the formation of a heterogeneous B/CuOx nanocatalyst Therefore,the choice of the buffer solution has a significant influence on the electrochemical behavior and stability of molecular water oxidation catalysts.

Role of transition-metal electrocatalysts for oxygen evolution with Si-based photoanodes

A comprehensive understanding of the role of the electrocatalyst in photoelectrochemical(PEC)water splitting is central to improving its performance.Herein,taking the Si-based photoanodes(n^(+)p-Si/SiO_(x)/Fe/FeOx/MOOH,M=Fe,Co,Ni)as a model system,we investigate the effect of the transition-metal electrocatalysts on the oxygen evolution reaction(OER).Among the photoanodes with the three different electrocatalysts,the best OER activity,with a low-onset potential of∼1.01 VRHE,a high photocurrent density of 24.10 mA cm^(-2)at 1.23 VRHE,and a remarkable saturation photocurrent density of 38.82 mA cm^(-2),was obtained with the NiOOH overlayer under AM 1.5G simulated sunlight(100 mW cm^(-2))in 1 M KOH electrolyte.The optimal interfacial engineering for electrocatalysts plays a key role for achieving high performance because it promotes interfacial charge transport,provides a larger number of surface active sites,and results in higher OER activity,compared to other electrocatalysts.This study provides insights into how electrocatalysts function in water-splitting devices to guide future studies of solar energy conversion.

Oxidative Desulfurization of Non-hydrotreated Kerosene Using Hydrogen Peroxide and Acetic Acid

The oxidative desulfurization of a real refinery feedstock (i.e.,non-hydrotreated kerosene with total sulfur mass content of 0.16%) with a mixture of hydrogen peroxide and acetic acid was studied.The influences of various operating parameters including reaction temperature (T),acid to sulfur molar ratio (nacid/nS),and oxidant to sulfur molar ratio (nO/nS) on the sulfur removal of kerosene were investigated.The results revealed that an increase in the reaction temperature (T) and nacid/nS enhances the sulfur removal.Moreover,there is an optimum nO/nS related to the reaction temperature and the best sulfur removal could be obtained at nO/nS=8 and 23 for the reaction temperatures of 25 and 60°C,respectively.The maximum observed sulfur removal in the present oxidative desulfurization system was 83.3%.

Adsorption，Oxidation and Complexation of Water－So－Inble Organic Snbstances in Soils

A greater part of water-solnble organic substances, accounting for 6070To of the total, could be adsorbedby soils, which included strongly and weekly reducing substances, positively and negatively charged substancesand substances containing amido. There existed a tendency of decrease in adsorption of the negativelycharged organic substances by the soil from South China to North China, with expression as Coulombianadsorption. A simultaneous reduction of iron and manganese appeared with clear voltammetric behavioursupon oxidation of water-soluble organic substances. Complexation of organic ligands with ferrons iron andmanganous manganese was proved by differential pulse voltammetric method, with disappearance of oxidationpeaks of ferrous iron and manganous manganese at 0.00 V and 0.35 V and occurrence of Fe`+-complex andMn￣2+ -complex at 0.75 V and 1.2 V respectively, whose peak potentials shifted backward.

Characters of the P_(CO)_2 and CO_2 Flux in the East China Sea in Autumn

P CO 2 of air and seawater samples from the East China Sea (ECS) were measured in situ in autumn, 1994. Ocean currents, terrestrial fluviation, biological activities, etc.,P CO 2 characters in air and seawater were investigated. CO 2 flux and its character in the East China Sea are discussed on the basis of theP CO 2 profiles of air and seawater. It was clear that the nearshore was the source of CO 2; and that the outer sea area was the sink of CO 2; and that the shelf area of the ECS is a net sink for atmospheric CO 2 in autumn.

Hydrolysis of Aluminum Ions in Kaolinite and Oxisol Suspensions as Influenced by Organic Anions

To evaluate the role of kaolinite and variable charge soils on the hydrolytic reaction of Al, the hydrolysis of Al ions in suspensions of a kaolinite and an Oxisol influenced by organic anions was investigated using changes of pH, Al adsorption, and desorption of pre-adsorbed Al. Kaolinite and the Oxisol promoted the hydrolytic reaction of Al above a certain initial Al concentration (0.1 mmol L-1 for kaolinite and 0.3 mmol L-1 for the Oxisol). The Al hydrolysis accelerated by kaolinite and the Oxisol increased with an increase in initial concentration of Al and was observed in the range of pH from 3.7 to 4.7 for kaolinite and 3.9 to 4.9 for the Oxisol. The acceleration of Al hydrolysis also increased with the increase of solution pH, reached a maximum value at pH 4.5, and then decreased sharply. Al hydrolysis was promoted mainly through selective adsorption for hydroxy-Al. Soil free iron oxides compensated a portion of the soil negative charge or masked some soil surface negative sites leading to a decrease in Al adsorption, which retarded acceleration to some extent. For the Oxisol organic anions increased the proportion of adsorbed Al3+ in total adsorbed Al with the increase in soil negative surface charge and eliminated or reduced the acceleration of Al hydrolysis. Different organic anions inhibited the hydrolysis of Al in the order: citrate > oxalate > acetate (under initial pH of 4.5). The formation of Al-organic complexes in solution also inhibited the hydrolysis of Al.

Activated Sludge Ozonation to Reduce Sludge Production in MBR

The total experimental period was divided into two stages. At the first stage, a series of batch studies were carried out to get an understanding of the effect of ozouation on sludge properties. At the following stages, three MBRs with different amounts of activated sludge to be ozonated were run in parallel for a long period to evaluate the influence of sludge ozonation on sludge yield and permeate quality. Through batch study, it was found that ozone could disrupt the cell walls and caused the release of plasm from the cells, then the amounts of soluble organics in the solution increased with ozouation time. With the rise of soluble organics, the amount of soluble organics to be mineralized increased as well, which would reduce the soluble organics content. For the counteraction between these two aspects, a pseudo-balanee could be achieved, and soluble organics would vary in a limited range. Sludge ozonation also increased the contents of nitrogen and phosphorus in the solution. In addition, ozouation was effective in improving sludge settling property. On the basis of batch study, a suitable ozone dosage of 0.16 kgO3/kgMLSS was determined. Three systems were run in parallel for a total period of 39 days, it was demonstrated that a part of activated sludge ozonation could reduce sludge production significantly, and biological perfonnanee of mineralization and nitrification would not be inhibited due to sludge ozouation. Experimental results proved that the combination of ozonation unit with MBR unit could achieve an excellent quality of permeate as well as a small quantity of sludge production, and economic analysis indicated that an additional ozonation operating cost for treatment of both wastewater and sludge was only 0.096Yuan （US$ 0.011,5 ）/m^3 wastewater.

Inactivation of Protein Tyrosine Phosphatase 1B （PTP1B） Activity by the Aqueous Partition of Guava Leaf Extract

Guava leaf tea has been used as a folk medicine for treating hyperglycemic conditions in Asia and Africa. The hypoglycemic efficacy of guava leaf has been documented by many scientists in these regions, but the hypoglycemic mechanism is poorly understood. Guava leaves were extracted with methanol and the crude extract was partitioned against hexane, ethyl acetate, and butanol in sequence. The leftover in water is defined as the aqueous partition. A second smaller batch was extracted with hot water directly. Oral glucose tolerance test was carried out on healthy mice instead of diabetic mice that lack endogenous insulin. Glucose uptake was examined with 3T3-L1 adipocytes. Oxidative effect on PTP1B （protein tyrosine phosphatase 1b） was carried out with real-time PTP1B enzymatic assay. The aqueous partition of guava leaf extract possesses a potent inhibitory effect on PTP1B enzymatic activity and this PTP1B inhibition is through a slow oxidative but reversible inactivation on the enzyme. The reversible inactivation would suggest guava leaf extract may augment PTP1B inhibition alongside the endogenous H2O2 which itself is induced by insulin. In addition, our study confirmed the hypoglycemic efficacy being associated with guava leaf and found the most effective molecules reside in the aqueous partition which is also less cytotoxic to Chinese hamster ovary cells when compared to other less polar partitions. The guava leaf extract can modulate insulin activity through a redox regulation on PP1B enzymatic activity. It is speculated that a compound similar to gallocatechin in the aqueous partition can reduce an oxygen molecule to hydrogen peroxide which in turn oxidizes the catalytic residue Cys in PTP1B. Therefore, the guava leaf tea can serve as a functional hypoglycemic drink that is suitable for either healthy or diabetic subjects.

Investigation into the Total Phenols and Antioxidant Activity during Storage of Fruit Smoothies

In this study, the total phenols （TP） and antioxidant activity of three different fruit smoothies （Blackberries, Raspberry and Boysenberry （BRAB）, Mango and Passion fruits （MAP） and Blackcurrant, Acerola cherries and Rosehips （BACAR）） were determined during storage by Folin-Ciocalteu and ferric reducing antioxidant power （FRAP） assays respectively. TP ranged from 1,943 to 2,692 mg L-1 gallic acid equivalent whereas FRAP from 43,217 to 126,125 μmol L-1 Trolox equivalent for the three smoothies on opening. BACAR had the highest TP and antioxidant activity. The smoothies showed significant decrease （P 〈 0.05） in TP during storage. The decrease in antioxidant activity was significant （P 〈 0.05） for BRAB and MAP only. However, the study revealed that the smoothies had high antioxidant activity even during shelf-life at 4 ℃ which implies that consumption of smoothies may give considerable antioxidant benefits. Correlation between TP and antioxidant activity was strong and highly significant （r = 0.890, P 〈 0.0001）.

Movement of lateral hyporheic flow between stream and groundwater

The hyporbeic zone plays an important role in groundwater and stream water quality protection. To investigate the stream-groundwater interaction mechanisms in the lateral hyporheic zone, this study examined Ma＇an Creek in Chongqing during the dry season from December 2015 to April 2016. The water level, water temperature, pH and CF concentration in the hyporheic zone and groundwater were monitored in situ. The sediment permeability coefficient, stable isotopes of hydrogen and oxygen and concentration of DOC were analyzed. The results show that the water level changes of hyporheic zone and the movement of hyporheic flow were influenced significantly by the permeability coefficient of sediment. The hyporheic flow approximately 10 cm from the stream bank was clearly affected by precipitation infiltration and evapotranspiration. During the study period, the groundwater recharged the stream, and the impact of groundwater on the hyporheic flow gradually decreased with the flow path. The hyporheic flow approximately 30 cm from the stream bank was still mainly affected by groundwater. Approximately 10-30 cm from the stream bank, the mixing of groundwater with precipitation and stream water intensified. Due to the sediment properties, moisture accumulated approximately 10 cm from the stream bank and drained into the stream via hyporheic flow, with potential impacts on stream water quality.