Typical binary nitrate (NaNO3-KNO3 as 60:40 rat io by weight) based AlN nanofluid was prepared by a two-step solutionmethod. The specific heat capacities of nanofluids with AlN amount ranging from 0.5 to 4 wt. % were investigated. The results suggest a good compatibility between AlN and molten binary nit rates. Meanwhile, AlN nanoparticles are proved to be an effective additive in improving the thermal properties of binary nitrates. For binary nitrate-based materials, samples with AlN amount as 1 wt. % shows the best thermal enhancement of specific heat capacity.
A numerical technique is presented in the analysis for loading behavior of general three-dimensional pile groups. The striking characteristics of the pile-group model may include raked pile, different pile sizes, non-uniform pile sections, soil inhomogeneit y, soil nonlinearity, and pile-soil-pile interaction. A typical six-pile group is analyzed and the results are compared with that obtained by four other computer programs that are based on different approaches. The computed solutions are shown to have reasonally good agreement with the measured values.
This paper examines the interaction between the spatial variations in binder concentration (i.e. cement slurry concentration) and in situ water content, in cement-mixed soil, using field and model data as well as statistical analysis and random field simulation. The field data are first analysed to shed light on the spatial variation in the in situ water content, including its scale of fluctuation. A statistical model is then developed which takes into account the variation in binder concentration and in situ water content. This leads to a two-parameter model for the prediction of the mean, variance and probability distribution function of the strength of the cement-treated soil. The scale of fluctuation for the variation in binder concentration arising from imperfect mixing within a cement-mixed column is then examined using centrifuge model data. This indicates that the scale of fluctuation in binder concentration is much shorter in range than that of the in situ water content. The combined effect of these two scales of fluctuation is then studied by simulating the resulting random field using Monte-Carlo simulations. This indicates that the size of the sampling region has a significant effect on the scale of fluctuation that is captured. If the sampling region is of a similar size to the column diameter, the measured scale of fluctuation reflects that of the binder concentration. As the size of the sampling region increases, so does the measured scale of fluctuation. This explains the wide range of scales of fluctuation that have been reported for cement-treated soil. To capture both scales of fluctuation in core sampling, some boreholes should be sunk at close spacings of less than a column diameter, in order to capture short-range variation.
Supported Ni on yttria stabilized zirconia (YSZ) is the most widely used anode for a solid oxide fuel cell (SOFC), where Ni particles are easy to agglomerate at a high temperature of 1400 °C and reductive hydrothermal environments. In this study, Ni particles are successfully dispersed on YSZ through strong interaction between Ni and SiO2. The thin and amorphous SiO2 films, grown by low-temperature chemical vapor deposition (CVD), become spherical particles of nickel silicates uniformly dispersed on the YSZ skeleton after sintering at 1400 °C. Also, the SiO2-anchored Ni particles supported on YSZ (Ni/YSZ-SiO2) are obtained via direct reduction. The electrochemical performance of the Ni/YSZ-SiO2 anode shows a higher power density of approximately 18% than an unmodified Ni/YSZ anode, which resulted from the longer effective TPB area assigned to the highly dispersed Ni particles. The microstructure containing SiO2-anchored Ni particles exhibits high stability under testing and reductive hydrothermal conditions. Accordingly, the method of growing a SiO2 layer via low-temperature CVD is considered as a probable route for the preparation of the Ni/YSZ electrode material with a well-defined microstructure.
Punch-through failure of mobile jack-up rigs is still a main concern for spudcan foundations. Using centrifuge model tests and numerical modelling, this paper examines the mitigating effect of top-mounted sleeves and a downward skirt on spudcan punch-through in medium dense sand overlying clay. The findings show that the top-mounted sleeves and downward skirt are both useful separately for reducing punch-through distance. The top-mounted sleeve functions by interfering with soil backfilling above the spudcan and maintaining confinement to the sides. This results in an earlier recovery in penetration resistance and reduces the peak-to-trough drop in resistance. The downward skirt appears to mobilise the soil further ahead of the spudcan, which reduces the peak penetration resistance and increases the rate of post-trough recovery in penetration resistance. A combination of a top-mounted sleeve with a downward skirt appears to confer a smaller peak-to-trough drop in resistance and higher rate of post-peak recovery, and thereby a much smaller punch-through distance. The results would suggest that, compared with the downward skirt, the top-mounted square sleeve with a similar area ratio to the existing lattice leg is supposed to be a more effective option in mitigating spudcan punch-through failure.
To characterize and optimize a novel Bacillus pumilus strain isolated from biological waste which produces protease with excellent dehairing effect. This newly isolated strain could be utilized in the industrial leather dehairing process.Bacterial strains secreting proteases were screened from biological wastes. Positive clones were further characterized by analysing their efficacy in dehairing and effects on collagen integrity. Among 171 colonies tested, a strain BA06, identified as B. pumilus, was picked owing to its efficient dehairing capabilities with minimal impact on collagen. By combined mutagenesis using UV, N-methyl-N'-nitro-N-nitrosdguanidine and Co(60)-gamma-rays, this strain was further improved with regard to its alkaline protease production. The alkaline protease activity of the mutant strain SCU11was greatly improved up to 6000 U ml(-1), in comparison with its parent strain BA06 of 1200 U ml(-1).By using screening and mutagenesis methods, we have successfully created a B. pumilus strain that can produce high levels of alkaline proteases that are able to efficiently remove hair from skin with minimal damage on the collagen.This strain could be used in commercial alkaline protease production for leather dehairing.
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