Energy release rate and fracture toughness of amorphous aluminum nanoparticles reinforced soda‐lime silica glass (SLSG) were measured by performing fracture simulations of a single‐notched specimen via molecular dynamics simulations. The simulation procedure was first applied to conventional oxide glasses and the accuracy was verified with comparing to experimental data. According to the fracture simulations on three models of SLSG/‐Al2O3 composite, it was found that the crack propagation in the composites is prevented through following remarkable phenomena; one is that a‐Al2O3 nanoparticles increase fracture surface area by disturbing crack propagation. The other is that the deformation of a‐Al2O3 nanoparticle dissipates energy through cracking. Moreover, one of the models shows us that the crack cannot propagate if the initial notch is generated inside a‐Al2O3 nanoparticle. Such strengthening is partly due to the fact that the strength of the interface between nanoparticle and SLSG matrix is comparable to that of SLSG matrix, implying that their interface does not reduce crack resistance of the oxide glass. 相似文献
The degradation of 1,4-dioxane was investigated on a laboratory scale. The extents of degradation and/or removal of 1,4-dioxane by ozonation at pH 6–8, UV irradiation, aeration, and addition of H2O2 were very limited. On the other hand, the degradation of 1,4-dioxane by O3/UV and O3/H2O2 was accelerated compared with the above respective methods. The amounts of 1,4-dioxane degraded per amount of ozone consumed in O3/UV and O3/H2O2 were also higher than in ozonation. The amount of 1,4-dioxane degraded in O3/UV was affected by the intensity of UV irradiation, and that in O3/H2O2 was affected by the amount of H2O2 added only in the case of a high initial concentration of 1,4-dioxane. 相似文献
The effects of droplet size and emulsifiers on oxidative stability of polyunsaturated TAG in oil-in-water (o/w) emulsions
with droplet sizes of 0.806±0.0690, 3.28±0.0660, or 10.7±0.106 μm (mean ± SD) were investigated. Hydroperoxide contents in
the emulsion with a mean droplet size of 0.831 μm were significantly lower than those in the emulsion with a mean droplet
size of 12.8 μm for up to 120 h of oxidation time. Residual oxygen contents in the headspace air of the vials containing an
o/w emulsion with a mean droplet size of 0.831 μm were lower compared with those of the emulsion with a mean droplet size
of 12.8 μm. Hexanal developed from soybean oil TAG o/w emulsions with smaller droplet size showed significantly lower residual
oxygen contents than those of the larger droplet size emulsions. Consequently, oxidative stability of TAG in o/w emulsions
could be controlled by the size of oil droplet even though the origins of TAG were different. Spin-spin relaxation time of
protons of acyl residues on TAG in o/w emulsions measured by 1H NMR suggested that motional frequency of some acyl residues was shorter in o/w emulsions with a smaller droplet size. The
effect of the wedge associated with hydrophobic acyl residues of emulsifiers was proposed as a possible mechanism to explain
differences in oxidative stability between o/w emulsions with different droplet sizes. 相似文献
Abstract A diarylheptanoid, named 3,17-dihydroxy-tricyclo[12.3.1.12,6]nonadeca- 1(18),2,4,6(19),14,16-hexaen-9,11-dione, was newly isolated from the branch wood of Alnus sieboldiana, together with two known diarylheptanoids. The chemical structure of this compound was assigned on the basis of the NMR and MS data, information obtained though 1D- and 2D-NMR analyses. These three diarylheptanoids were found to significantly inhibit the activity of α-glucosidase. 相似文献
Among various kinds of fluorine-substituted biomolecules, 2-fluoroadenine (2FA) and its derivatives have been actively investigated as therapeutic reagents, radio-sensitizers, and 19F NMR probes. In spite of their excellent properties, DNA containing 2FA has not been studied well. For fundamental understanding and future applications to the development of functional nucleic acids, we characterized 2FA-containing oligonucleotides for canonical right-handed DNA duplex, G-quadruplex, and i-motif structures. Properties of 2FA were similar to native adenine due to the small size of the fluorine atom, but it showed unique features caused by high electronegativity. This work provides useful information for future application of 2FA-modified DNA. 相似文献
A variable stiffness actuator (VSA) is considered a promising mechanism-based approach for realizing compliant robotic manipulators. By changing the stiffness of each joint, the robot can modulate the stiffness of the entire system to enhance safety and efficiency during physical interaction with other systems. This paper presents a feedforward method to modulate the operational stiffness of a parallel planar robot with multiple VSAs. A VSA utilizing a lever mechanism was developed, clearly presenting its mechanical design and kinematic model details. A computational model of joint-restoring torque was developed based on deformation measurements and hysteresis loop geometry to estimate the applied torque of each joint in real-time. An algorithm was proposed to compute the joint stiffness solution using the robot's kinematic model for modulating the operational stiffness of the parallel robot. Experiments were performed to evaluate the proposed method by comparing the performances of two DOF serial and parallel robot systems. The results demonstrated the capability of the VSA in both feedforward stiffness modulation and external force estimation.