The original version of this Article contained errors in the symbols displayed in the eighteenth sentence of the third paragraph of the ‘Determination of H ab and k ET data for the Mo 2 dimers’ section of the Results, and the third sentence of the Discussion. This has been corrected in both the PDF and HTML versions of the Article.
Abstract Although silica‐based ceramic cores have important applications in the precision casting of metallic devices, their high‐temperature stability and removal performances are seriously affected by the liquid phase sintered fused silica. Herein, we develop a manufacturing strategy of high‐collapse silica‐based ceramic core via using cristobalite crystals as the sintering inhibitor, waterglass as the binder, and injection moulding at 100°C and 80 MPa, followed by heat treatment simulating the casting process for sintering at 1200°C and 1500°C. The results demonstrated that the addition of cristobalite crystals could effectively form the core skeleton to ensure high‐temperature performance. Meanwhile, it inhibited the liquid flow during sintering and induced the crytsallization from fused SiO 2 glass into cristobalite crystals, and the resulting plenty of micropores and microcracks within the microstructure effectively improve the removal performance. Especially, the porosity was highest up to 35.36% and the flexural strength was only 6.74 MPa when the addition of cristobalite reached 45%, realizing a 100% removing by high‐frequency and fast‐speed specific mechanical vibration. And, the casting is guaranteed to be flat and free of defects. This work provides a simple and flexible strategy to manufacture high‐collapse silica‐based ceramic cores, which can be removed by specific mechanical vibration without immersion in acid or alkali solutions after casting.
The chemical composition of fulvic acid (FA) with a molecular weight below 500 (FA-500) was analyzed, and its activity on promoting the seed germination of wheat was studied in this paper. The FA-500 was obtained by membrane separation technology and qualitatively and quantitatively analyzed by using gas chromatography-mass spectrometry combined with the retention index. Forty-seven constituents were identified, including structures with ester, acid and alcohol groups, which accounted for 95% of the total composition. The highest relative content of compounds was diethyl succinate and diethyl malonate, accounting for 29% and 17% of the total, respectively. Yannong 19 and Luyuan 301 wheat seeds were steeped with the FA-500 solution of different concentration respectively for two hours. Several markers were assessed: germination rate, coleoptile and radicle length, germination index, vitality index and the activity of α-amylase and (α+β) amylase. The results indicated that FA-500 had a significant effect on promoting seed germination within an appropriate concentration range. The best concentration was 0.5‰, and an inhibiting effect would appear with the increase of concentration. In the process of seed germination, FA-500 may affect the growth of the seed through influencing the amylase activity, which was related to respiration.
WIS platform is a wireless interactive sensor platform designed to support dynamic and interactive applications. The platform consists of a capture system which includes multiple on-body Zigbee compatible motion sensors, a processing unit and an audio-visual display control unit. It has a complete open architecture and provides interfaces to interact with other user-designed applications. Therefore, WIS platform is highly extensible. Through gesture recognitions by on-body sensor nodes and data processing, WIS platform can offer real-time audio and visual experiences to the users. Based on this platform, we set up a multimedia installation that presents a new interaction model between the participants and the audio-visual environment. Furthermore, we are also trying to apply WIS platform to other installations and performances.
The hydro-chemical properties of litter layers of 6 typical forests including Pinus massoniana×Adinandra bockiana×Gordonia acuminata Chang mixed forest(forest type Ⅰ),Lindera kwangtungensis×Symplocos setchuanensis mixed forest(forest type Ⅱ),Phyllostachys pubescens forest(forest type Ⅲ),Symplocos setchuanensis×Cunninghamia Lanceolata(forest type Ⅳ),Pinus massoniana forest(forest type Ⅴ) and shrub forest(forest type Ⅵ)in Jinyun mountain were studied by the simulated acid rain experiment.The results showed: ①Litter leaching pH values of 6 typical forest stands reduced with the decrease of pH of simulated acid rain.The acid buffer ability of litter layer in forest type Ⅴ was best.②Base cation(Ca2+,Mg2+,K+,Na+,NH+4) concentrations of all 6 typical forest litter leaching increased with the decrease of pH of simulated acid rain.Under the eluviation of different simulated acid rain(pH value: 2.7,3.5),the base cation concentrations of litter leaching of forest type Ⅴ were always largest: 0.143 6 mmol/L(pH 2.7),0.074 0 mmol/L(pH 3.5).Under the eluviation of pH 4.5 simulated acid rain,the base cation concentrations of litter leaching of forest type Ⅱ were the largest: 0.138 9 mmol/L.③The concentrations of Al3+,Fe,Mn,Zn in litter leaching of 6 typical forest stands increased dramatically when the pH value of simulated acid rain was 2.7.And the concentrations of Al3+(0.018 2 mmol/L),Fe(0.004 4 mmol/L),Mn(0.010 7 mmol/L) and Zn(0.002 5 mmol/L) in forest type Ⅴ litter leaching were larger than that of the others.It indicated that forest type Ⅴ was more vulnerable to these toxic elements.
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