Enhanced visible-light photocatalytic activity of anatase-rutile mixed-phase nano-size powder given by high-temperature heat treatment

Nano-size EVONIK AEROXIDE® P25 titanium dioxide, TiO2, powder was heat-treated at temperatures, 700–900°C, in air. An X-ray diffraction study showed that the P25 powder is composed of approximately 20 and approximately 80 mass% of rutile and anatase phases, respectively. It was also shown that the transformation from anatase to rutile induced by hightemperature heat treatment was almost completed at 750°C, whereas a small amount (less than 3 mass%) of anatase phase was still left even in the powder heat-treated at 900°C. The transformation behaviour was consistent with results obtained by Raman scattering spectroscopy. Raman experiments also indicated that high-temperature heating induced the formation of oxide ion vacancies. Powders were dispersed in methyl orange (MO) aqueous solution, and the bleach rate of MO was measured to evaluate photocatalytic activity under ultraviolet (UV)- and visible-light irradiation. After the heat treatment, the UV-light photocatalytic performance sharply deteriorated. Interestingly, visible-light photocatalytic activity was enhanced by high-temperature heating and reached the highest performance for an 800°C-heated sample, indicating that the P25 powder obtained high visible-light photocatalytic performance after heat treatment. Even after 900°C heat treatment, the photocatalytic performance was higher than that of as-received powder. Enhancement of photocatalytic activities was discussed in relation to visible light absorption and charge carrier transfer.T.I., H.O. and D.H. were supported by a programme, the Strategic Research Foundation at Private Universities, grant no. S1311023, from Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan

Micropollutant rejection by nanofiltration membranes: a mini review dedicated to the critical factors and modelling prediction

Nanofiltration (NF) membranes, extensively used in advanced wastewater treatment, have broad application prospects for the removal of emerging trace organic micropollutants (MPs). The treatment performance is affected by several factors, such as the properties of NF membranes, characteristics of target MPs, and operating conditions of the NF system concerning MP rejection. However, quantitative studies on different contributors in this context are limited. To fill the knowledge gap, this study aims to assess critical impact factors controlling MP rejection and develop a feasible model for MP removal prediction. The mini-review firstly summarized membrane pore size, membrane zeta potential, and the normalized molecular size (λ = rs/rp), showeing better individual relationships with MP rejection by NF membranes. The Lindeman-Merenda-Gold model was used to quantitatively assess the relative importance of all summarized impact factors. The results showed that membrane pore size and operating pressure were the high impact factors with the highest relative contribution rates to MP rejection of 32.11% and 25.57%, respectively. Moderate impact factors included membrane zeta potential, solution pH, and molecular radius with relative contribution rates of 10.15%, 8.17%, and 7.83%, respectively. The remaining low impact factors, including MP charge, molecular weight, logKow, pKa and crossflow rate, comprised all the remaining contribution rates of 16.19% through the model calculation. Furthermore, based on the results and data availabilities from references, the machine learning-based random forest regression model was trained with a relatively low root mean squared error and mean absolute error of 12.22% and 6.92%, respectively. The developed model was then successfully applied to predict MPs’ rejections by NF membranes. These findings provide valuable insights that can be applied in the future to optimize NF membrane designs, operation, and prediction in terms of removing micropollutants

Pharmacokinetics, Bioavailability, and Tissue Distribution Study of Angoroside C and Its Metabolite Ferulic Acid in Rat Using UPLC-MS/MS

Angoroside C is a phenylpropanoid glycoside compound isolated from the dried root of Scrophularia ningpoensis Hemsl., which possesses the effects of preventing ventricular remodeling, reducing pulmonary oedema, and reducing blood pressure, as well as having the properties of anti-platelet aggregation, hepatoprotection and anti-nephritis, etc. However, few investigations have been conducted on the absorption, distribution, metabolism, and excretion (ADME) study of angoroside C. Thus, a fast ultra-high performance liquid chromatography-tandem quadrupole mass spectrometry (UPLC-MS/MS) method was established for the determination of angoroside C and its metabolite ferulic acid in rat plasma and tissue homogenate. The two analytes were extracted from the biosamples using a simple protein precipitation with acetonitrile. The developed method was validated and successfully applied to the pharmacokinetics, bioavailability and tissue distribution study after the intragastric administration of angoroside C (100 mg/kg) or the intravenous administration of angoroside C (5 mg/kg), respectively. The results showed that angoroside C can be absorbed extremely quickly (Tmax = 15 min), can be eliminated very rapidly (t1/2 = 1.26 h), and its oral bioavailability is only about 2.1%. Furthermore, angoroside C was extensively distributed in all main organs (liver, heart, spleen, lung, kidney, and brain), and the highest concentration was detected in the lung 15 min after oral administration. This paper also indicated that angoroside C could be converted to the active metabolite ferulic acid in vivo. The maximum concentrations of ferulic acid in the kidney occurred at 6 h after oral administration. In summary, this study explored some of the pharmacokinetic characteristics of angoroside C in vivo, and the data produced could provide a basis for the further investigation of angoroside C

Phosphor Deposits of β-Sialon:Eu2+ Mixed with SnO2 Nanoparticles Fabricated by the Electrophoretic Deposition (EPD) Process

The phosphor deposits of the β-sialon:Eu2+ mixed with various amounts (0–1 g) of the SnO2 nanoparticles were fabricated by the electrophoretic deposition (EPD) process. The mixed SnO2 nanoparticles was observed to cover onto the particle surfaces of the β-sialon:Eu2+ as well as fill in the voids among the phosphor particles. The external and internal quantum efficiencies (QEs) of the prepared deposits were found to be dependent on the mixing amount of the SnO2: by comparing with the deposit without any mixing (48% internal and 38% external QEs), after mixing the SnO2 nanoparticles, the both QEs were improved to 55% internal and 43% external QEs at small mixing amount (0.05 g); whereas, with increasing the mixing amount to 0.1 and 1 g, they were reduced to 36% and 29% for the 0.1 g addition and 15% and 12% l QEs for the 1 g addition. More interestingly, tunable color appearances of the deposits prepared by the EPD process were achieved, from yellow green to blue, by varying the addition amount of the SnO2, enabling it as an alternative technique instead of altering the voltage and depositing time for the color appearance controllability

Changes in net anthropogenic nitrogen and phosphorus inputs in the Yangtze River Economic Belt, China (1999–2018)

Since the industrial revolution, excess inputs of nitrogen (N) and phosphorus (P) from human activities have been the main threat of deterioration to water environmental quality. In this study, to understand the variation characteristics, evolutionary pattern, composition structure, and main influencing factors on net anthropogenic nitrogen inputs (NANI) and net anthropogenic phosphorus inputs (NAPI) in the Yangtze River Economic Belt, 20 years of data from 1999 to 2018 at the general, provincial and city scales were analyzed. The results showed that NANI and NAPI in the Yangtze River Economic Belt increased and then decreased from 1999 to 2007 and from 2008 to 2018, with average values of 7189.26 kg N km−2 yr−1 and 2169.31 kg P·km−2 yr−1. Fertilizer application constituted the largest source of contributions to NANI and NAPI, with average contribution rates of 66.31 % and 68.20 %. The spatial pattern of NANI and NAPI exhibited a decreasing trend from east to west and from north to south. Western Jiangsu, eastern Anhui, central Hubei, and western Sichuan were high-risk areas. The contribution rates of human activity factors were ranked as economic factors > land-use factors > social factors, and changes in economic factors contributed the most to changes in NANI and NAPI, with averages of 70.50 % and 70.10 %. The Yangtze River Economic Belt has crossed the Environmental Kuznets Curve (EKC) inflection point for the N/P input load and has entered the coordinated development stage of economic growth and environmental improvement. The city scale can effectively identify and optimize the control area compared with the provincial scale, and the proportions of the administrative areas for NANI and NAPI at different targets decreased by 4.11 % (5.20 %), 7.52 % (11.95 %), and 9.79 % (17.29 %), respectively

Research on Seismic Response of Base-Isolated Nuclear Island Building considering FSI Effect of PCS Water Tank

Base isolation can be used to reduce seismic response of structure and protect the structure from damage subjected to earthquake. To study the isolation effect of new PWR nuclear power plant with a base isolation system, considering FSI (fluid-structure interaction) effect by the simplified model, two 3D numerical models (one nonisolated model and one isolated model) were established. After natural frequency analysis, one artificial ground motion was chosen to analyze isolation effect qualitatively. Based on the results, the accelerations and relative displacements of nuclear island building under ten natural ground motions were statistically analyzed to evaluate the isolation effect quantitatively. The results show that the base isolation system can reduce the natural frequencies of nuclear island building. Horizontal accelerations can be reduced effectively, but the isolation effect is not obvious in vertical direction. The acceleration reduction ratio of the top is about 70%–90%, and the acceleration reduction ratio of the lower part is about 20%–60%. Horizontal displacement of the isolated model is far larger than that of the nonisolated model, and horizontal displacement will become larger considering FSI effect. These conclusions could provide some references for studies on the isolation system of nuclear island building

Surface Modification on Cellulose Nanofibers by TiO₂ Coating for Achieving High Capture Efficiency of Nanoparticles

Cellulose nanofibers were modified by TiO2 gel layer (~25 nm in thickness) via hydrolysis reaction on the surface of the cellulose nanofibers. After the TiO2 coating, the surface charge of the nanofiber dramatically changed from negative to positive. A high efficiency (~100%) of capturing negatively charged Au nanoparticles (5 nm) was successfully obtained by effectively utilizing the electrostatic interaction of surface charge between the TiO2-coated cellulose nanofibers and Au nanoparticles. Therefore, this technique of surface modification will be potentially used in improving filtration efficiency for membrane applications

Influence of the Duration Compression Ratio of the Input Motion on the Seismic Response of a Soil–Pile–Bridge Structure System in Shaking Table Tests

In the shaking table test of a soil–pile–bridge structure system, it is difficult to keep the similarity relations of the model structure and that of the model soil consistent. Due to the difference of geometry and material similarity ratios for the model structure and model soil, the determination of the duration compression ratio of input motions is a key problem. The spectrum characteristics of input motions will be varied by the duration compression ratio so that the seismic responses of structure and soil system will be affected. There are three commonly used approaches to determine the duration compression ratio of input motions in shaking table tests: the time similarity ratio of model structure; the time similarity ratio of model soil; and uncompressed. To study the influence of the duration compression ratio on the seismic response of a soil–structure system in shaking table tests, the El Centro record and the Wolong record were chosen as the input motions, and the durations were compressed by the three commonly used approaches in this paper. The influence of the duration compression ratios of the input motions on the acceleration response of a soil–pile–bridge structure system was compared and analyzed through a series of shaking table tests. The results showed that the duration compression ratio affected the acceleration response of the model soil and the model structure, and the effect was more obvious when the peak ground acceleration (PGA) was small. If the research is focused on the seismic response of the soil, it is recommended to use the time similarity ratio of the model soil to compress the input motions. If the research is focused on the seismic response of the structure, it is recommended to use the time similarity ratio of the model structure to compress the input motions. This study could provide a reference for the design of the shaking table test of a soil–pile–bridge structure system