To improve the efficiency of overall water splitting, highly active and stable bifunctional electrocatalysts are highly desirable. Herein, we fabricated mixed Ni-Co phosphides (NiCo-P) as bifunctional catalysts for overall water splitting. Structural characterizations indicated that the NiCo-P catalysts (0 > x > 1) exhibited hierarchical yolk-shelled morphologies, with a total diameter of 1-2 μm. Interestingly, the shell was assembled by numerous nanosheets with a thickness less than 10 nm. The electrochemical measurements indicated that the NiCo-P catalysts (0 < x < 1) showed significantly enhanced OER and HER activities in comparison to the pure Ni-P and Co-P catalysts, and the highest OER and HER activities were achieved as x = 0.31. To drive a current density of 10 mA cm, the NiCo-P catalyst required an overpotential of 266 mV for OER and 96 mV for HER, respectively. The alkaline water electrolyzer with the NiCo-P catalysts as the cathode and anode catalysts required a cell voltage of ca. 1.59 V to achieve a current density of 10 mA cm, which was comparable to the integrated performance of commercial Pt/C and IrO. Furthermore, the electrolyzer assembled by the bufictional electrocatalysts showed a more stable performance than one assembled by commercial Pt/C and IrO operated at the simialr current density. The superior activity and long-term stability demonstrate that the hierarchical mixed Ni-Co phosphides have promising potential for application in large-scale water splitting.

Animal fats and partially hydrogenated vegetable oils (PHVO) have preferentially been used for deepfrying of food because of their relatively high oxidative stability compared to natural vegetable oils. However, animal fats and PHVO are abundant sources of saturated fatty acids and trans fatty acids, respectively, both of which are detrimental to human health. Canola (Brassica napus) is the primary oilseed crop currently grown in Australia. Canola quality Indian mustard (Brassica juncea) is also being developed for cultivation in hot and low-rainfall areas of the country where canola does not perform well. A major impediment to using these oils for deep-frying is their relatively high susceptibility to oxidation, and so any processing interventions that would improve the oxidative stability would increase their prospects of use in commercial deep-frying. The oxidative stability of both B. napus and B. juncea crude oils can be improved dramatically by roasting the seeds (165 7C, 5 min) prior to oil extraction. Roasting did not alter the fatty acid composition or the tocopherol content of the oils. The enhanced oxidative stability of the oil, solventextracted from roasted seeds, is probably due to 2,6-dimethoxy-4-vinylphenol produced by thermal decarboxylation of the sinapic acid naturally occurring in the canola seed.

Development of noble-metal-free and active electrocatalysts is crucial for the oxygen evolution reaction (OER) in the water-splitting process. Herein, crystal Co x B catalysts (x = 1–3) of the OER are fabricated by a ball-milling method. Among these Co x B catalysts, Co2B exhibits the best OER activity, with a current density of 10 mA cm–2 at an overpotential of 287 mV in 1 M KOH solution. Such OER activity of Co2B is favorably comparable to that of the commercial IrO2 and most recently reported OER catalysts. Furthermore, the Co2B catalyst exhibits excellent stability with a stable current density of 50 mA cm–2 over 12 h of continuous electrolysis operation. X-ray photoelectron spectroscopy and cyclic voltammetry demonstrate that the B in Co x B makes oxidation easier, leading to their enhanced OER activities in comparison to metal Co. In addition, the Co2B electrocatalyst also exhibits high activity in the hydrogen evolution reaction; thus, the catalyst can be used as a bifunctional catalyst for full water splitting.

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The results obtained from the finite element model of laser-generated ultrasound are presented in terms of temperature and displacement. According to thermoelastic theory, considering the temperature dependence of the thermophysical parameters of the material, the transient temperature field can be precisely calculated by using the finite element method; then, laser-generated surface acoustic wave forms are calculated in Al plates of various thicknesses. The elastic waves excited by a pulsed laser in a thin plate are typical Lamb waves, and the numerical results demonstrate that the surface vibration is mainly determined by the lower frequency components of the symmetric mode s0 and antisymmetric mode a0 of the lowest order in very thin plate materials. It is also indicated that, when the sample thickness increases, both the higher frequency components of the lower Lamb wave modes and the higher order Lamb wave modes should be considered. In a relatively thicker plate, the numerical model can still capture the significant details of the transient features taking place in the plates. The surface skimming longitudinal and shear waves are relatively stronger in the near field, distorting the observed wave form of the Rayleigh wave. These effects must be considered when the quantitative near field is applied to determining elastic parameters or residual stresses.

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Several metal plates with different thickness including copper, iron, aluminum, and stainless steel have been drilled in the surroundings of air and water, respectively, by a Q-switched pulsed Nd:yttrium–aluminum–garnet laser. It is observed that for the same metal plate less energy is needed to drill a hole in water than that in air, and the surface morphology of hole drilled in water is improved greatly than that in air by comparison of the scanning electron micrographs. The underlying mechanisms behind the efficiency and quality enhancement in water are further investigated by means of optical beam deflection technique. The experimental results show that due to the water confinement the peak amplitude and duration of the laser-ablation-generated impact underwater is much larger than that in air. During the underwater laser drilling, besides laser ablation effect, both the first and second liquid-jet-induced impulses by cavitation bubble collapse in the vicinity of a solid boundary are also observed and their amplitudes are, respectively, about 12.4 and 5.2 times that of the laser ablation impact in air. Cavitation bubbles are the special dynamic phenomenon occurring in liquids. Therefore, it is concluded that in-air-drilling laser ablation-produced impact is a dominant mechanism; while during laser underwater drilling, it is the result of a combination of ablation-produced impact effect and liquid-jet-induced impact, especially the latter. Thus, the efficiency and quality of laser processing in the surrounding water can be greatly increased and improved compared with that in air.

The melting behavior of milk fat, hydrogenated coconut and cottonseed oils, and blends of these oils was examined by nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). Solid fat profiles showed that the solid fat contents (SFC) of all blends were close to the weighted averages of the oil components at temperatures below 15°C. However, from 15 to 25°C, blends of milk fat with hydrogenated coconut oils exhibited SFC lower than those of the weighted averages of the oil components by up to 10% less solid fat. Also from 25 to 35°C, in blends of milk fat with hydrogenated cottonseed oils, the SFC were lower than the weighted averages of the original fats. DSC measurements gave higher SFC values than those by NMR. DSC analysis showed that the temperatures of crystallization peaks were lower than those of melting peaks for milk fat, hydrogenated coconut oil, and their blends, indicating that there was considerable hysteresis between the melting and cooling curves. The absence of strong eutectic effects in these blends suggested that blends of milk fat with these hydrogenated vegetable oils had compatible polymorphs in their solid phases. This allowed prediction of melting behavior of milk-fat blends with the above oils by simple arithmetic when the SFC of the individual oils and their interaction effects were considered.Paper no. J9594 in JAOCS 78, 387-394 (April 2001).