Synergistic refining mechanism of Mg-3%Al alloy refining by carbon inoculation combining with Ca addition

Mg-3%Al alloy was refined by carbon inoculation combining with 0.2%Ca addition.High grain refining efficiency was obtained and the synergistic refining mechanism was deeply discussed in the present study.Al-C-O particles,actually Al4C3 particles,were formed in the carbon-inoculated Mg-3%A1 alloy acting as nuclei forα-Mg grains.Ca addition had no obvious effect on size distribution of the nucleating particles.Ca segregation was proved on Al4C3 particles,which should reduce the interfacial energy of nuclei/Mg.The constitutional undercooling in front of nucleus/liquid was increased from 0.12℃to 0.15℃induced by 0.2%Ca addition.The synergistic grain refining efficiency can be attributed to the higher constitutional undercooling and lower the interface energy of nucleus/Mg induced by Ca addition.More nucleating particles with small size could be activated acting as potent nuclei ofα-Mg grains.Consequently,Mg-3%Al alloy could be effectively refined due to the synergistic effect induced by carbon inoculation combining with Ca.

Coastal Reservoirs Strategy for Water Resource Development—A Review of Future Trend

Water use and access become a more and more important determinant of environmental equity and human development according to the view held by the UN [1]. Water scarcity is one of the major crises which has overarching implications for other world problems especially poverty, hunger, ecosystem degradation, desertification, climate change, threatening world peace and security [2]. In the decades to come, freshwater consumed by human will get to a tipping point. Many projects and concepts have been proposed and implemented for several years to improve the effectiveness of using water. These research activities can be grouped as: desalination plants;water detention (like rainwater tanks for collection and reuse);wastewater reuse;dams and reservoirs. This paper summarized the characters of these water solutions. But these methods can’t provide enough fresh water due to limitations imposed by these methods as well as following industry and population’s development. To overcome these shortcomings, coastal reservoir strategy is proposed in the paper. This new strategy is technically feasible, environmentally sustainable and cost effective by demonstration and comparison.

How to Purify a Polluted Lake Quickly—A Case Study from Shanghai, China

Water pollution has become a serious worldwide problem, especially for lakes with a large stagnant water body. Is it possible to develop high quality water from a heavily polluted river system quickly? This paper introduces an innovative technology termed SPP (separation, prevention and protection) for this purpose. Its feasibility is preliminarily examined using Dianshan Lake in Shang- hai as an example. Due to its very high population density and intensive industrial activities, almost all waterways in Shanghai are heavily polluted, including the lake. However, the data analysis shows that clean water always appears after heavy rains, especially in its suburban areas. Once the 1st flush water is discharged to downstream, high-quality water can be developed from its Dianshan Lake by using the SPP strategy. The Vollenweider model is used to analyze SPP’s feasibility. The results show that the water quality of the Dianshan Lake can be remediated as a drinking water source within 120 days if the SPP strategy is applied. It is suggested that Jinze reservoir’s water should come from the Dianshan lake, not Taipu River to improve the quality of water supply. It is highly recommended for other cities in the world to consider the SPP technology if needed.

Recent advances in two-dimensional nanomaterials for bone tissue engineering

Over the last decades,bone tissue engineering has increasingly become a research focus in the field of biomedical engineering,in which biomaterials play an important role because they can provide both biomechanical support and osteogenic microenvironment in the process of bone regeneration.Among these biomaterials,two-dimensional(2D)nanomaterials have recently attracted considerable interest owing to their fantastic physicochemical and biological properties including great biocompatibility,excellent osteogenic capability,large specific surface area,and outstanding drug loading capacity.In this review,we summarize the state-of-the-art advances in 2D nanomaterials for bone tissue engineering.Firstly,we introduce the most explored biomaterials used in bone tissue engineering and their advantages.We then highlight the advances of cutting-edge 2D nanomaterials such as graphene and its derivatives,layered double hydroxides,black phosphorus,transition metal dichalcogenides,montmorillonite,hexagonal boron nitride,graphite phase carbon nitride,and transition metal carbonitrides(MXenes)used in bone tissue engineering.Finally,the current challenges and future prospects of 2D nanomaterials for bone tissue regeneration in process of clinical translation are discussed.

Resistance of the flow over rough surfaces

The mechanism of the flow resistance in open channels and pipelines is of vital importance for various critical issues related to the water flow.The Nikurade’s method of calculating the friction factor is not applicable in some cases.It is necessary to consider the influence of the vortex volume surrounding the vegetation and to study the hydrodynamic characteristics of the vegetated channels.This paper analyzes the variation of the vortices created by the surface roughness of different types and different sizes and proposes new definitions of the hydraulic radius and the equivalent roughness height.With consideration of the skin friction and the form drag,on the basis of the force balance equation,a novel calculation method is used for the friction factor,and this method is verified by experimental data.The hydrodynamic mechanism of the flow resistance revealed in this study may serve as a theoretical basis for hydraulic engineers to calculate the friction factor.

Polymer Waveguide Coupled Surface Plasmon Refractive Index Sensor:A Theoretical Study

A waveguide coupled surface plasmon sensor for detection of liquid with high refractive index(RI)is designed based on polymer materials.The effects of variation of the thickness of the Au film,polymethyl methacrylate(PMMA)buffer,and waveguide layer on the sensing performance of the waveguide are comprehensively investigated by using the finite difference method.Numerical simulations show that a thinner gold film gives rise to a more sensitive structure,while the variation of the thickness of the PMMA buffer and waveguide layer has a little effect on the sensitivity.For liquid with high RI,the sensitivity of the sensor increases significantly.When RI of liquid to be measured increases from 1.45 to 1.52,the sensitivity is as high as 4518.14 nm/RIU,and a high figure of merit of 114.07 is obtained.The waveguide coupled surface plasmon RI sensor shows potential applications in the fields of environment,industry,and agriculture sensing with the merits of compact size,low cost,and high integration density.

Refractive Index Sensor Based on Metal-Clad Planar Polymer Waveguide Operating at 850nm

A metal-clad planar polymer waveguide refractive index sensor based on epoxy(EPO)polymer materials by using light intensity interrogation at 850 nm is designed.The polymethyl methacrylate(PMMA)material is deployed as the low refractive index(RI)buffer layer in order to better couple the optical guided mode and the surface plasmon polaritons(SPP)mode for working in water environment.The effects of the gold film thickness,PMMA buffer layer thickness,waveguide layer thickness,waveguide width,and gold length on the sensor sensing characteristics have been comprehensively studied.Simulation results demonstrate that the normalized transmission increases quasi-linearly with the increment of RI of the analyte from 1.33 to 1.46.The sensitivity is 491.5 dB/RIU,corresponding to a high RI resolution of 2.6×10^(9)RIU.The designed SPP-based optical waveguide sensor is low-cost,wide-range,and high-precision,and has a broad application prospect in biochemical sensing with merits of miniaturization,flexibility,and multiplexing.