Application of the relativistic DV-Xα molecular orbital method to γ-uranium alloys with transition metals

The alloying behavior of 4d and 5d transition metals (TMs) in γ-phase solid uranium (U) has been investigated using the discrete-variational Dirac–Fock–Slater (DV-DFS) method. We examined the d-orbital energy (Md value) of these TMs, the orbital overlap population (OOP) between the d-orbital of these TMs and the 5f or 6d orbital of γ-U, and the effective charge on each atom of the γ-U/TM alloy, and the effect of these parameters on alloying. It was found that the maximum solid solubility (MSS) of TMs into γ-U was exponentially proportional to both the Md and the OOP (U5f–TMd and U6d–TMd), except for Ta and W elements. We found a good correlation between the MSS and Md, the effective charge, or OOP.     

Dispersion of single-walled carbon nanotubes in water by the use of novel fluorinated dendrimer-type copolymers

New fluorinated dendrimer-type block copolymers were applied to the dispersion of single-walled carbon nanotubes (SW-CNTs) and single-walled carbon nanotubes containing carboxy groups [(SW-CNT)-COOH] in water. Fluorinated block copolymer could disperse SW-CNTs more effectively in water, compared to that of the corresponding ABA triblock-type fluoroalkyl end-capped dimethylacrylamide oligomer [R_F-(DMAA)_n-R_F]. Dynamic light-scattering (DLS) measurements and transmission electron microscopy (TEM) images show that SW-CNTs could be smoothly encapsulated into fluorinated copolymeric aggregates cores. Interestingly, it was demonstrated that SW-CNTs could be in part released from the fluorinated copolymeric aggregates/SW-CNTs composites or encapsulated into these composites with increasing the dispersion times. On the other hand, fluorinated block copolymer and R_F-(DMAA)_n-R_F oligomer were not able to disperse well (SW-CNT)-COOH in water; however, ABA triblock-type fluoroalkyl end-capped acrylic acid oligomer was able to disperse quite effectively (SW-CNT)-COOH in water.     

Soil Spring Constants of Buried Pipelines for Seismic Design

This paper presents within the scope of the theory of static elasticity a derivation of soil spring constant in longitudinal direction of a buried pipeline in the seismic design. It is found that the spring constant depends on the shear modulus G of the soil deposits and the ratio λ of the radius of zero displacement over the radius of a buried pipeline structure. When λ increases, the soil spring constant decreases and the decreasing rate reduces remarkably when λ is greater than about 10. The ratio of soil spring constant over G is 2.7 when λ = 10. Furthermore, the dynamic effect of soil spring constants on buried pipeline structures is estimated analytically by the dynamic theory of elasticity. The soil spring constant that is derived, taking into account the boundary condition of ground surface, depends on the shear modulus G of the ground, nondimensional frequency ωb∕Vs (ω = circular frequency; b = radius of buried pipeline; Vs = ground shear-wave velocity) and nondimensional depth d∕b (d = depth of pipeline).     

Photon-assisted oxidation and oxide thin film synthesis: A review

The article reviews an oxide materials synthesis approach utilizing photons. Photon-assisted oxide processing is an interesting and unique approach to synthesize ultra-thin oxides at relatively low temperatures. Photon-assisted oxidation can be implemented both during oxide synthesis as well as a post-deposition annealing step. The mechanisms governing photon-assisted oxygen incorporation into growing oxide films, namely, electric field and chemical effects are discussed. Experimental observations on representative oxide structures in the fluorite, rutile and perovskite family are highlighted. It is shown that the technique enables near-room temperature modification of structure and chemistry of oxide surfaces, interfaces with atomic-level control. Oxygen non-stoichiometry can be controllably tuned using this approach in a self-limiting manner. Potential relevance of the processing approach in the context of applications in emerging electronics and energy technologies are pointed out.     

Aerodynamic Coupling Effects on Flutter and Buffeting of Bridges

The effects of aerodynamic coupling among modes of vibration on the flutter and buffeting response of long-span bridges are investigated. By introducing the unsteady, self-excited aerodynamic forces in terms of rational function approximations, the equations of motion in generalized modal coordinates are transformed into a frequency-independent state-space format. The frequencies, damping ratios, and complex mode shapes at a prescribed wind velocity, and the critical flutter conditions, are identified by solving a complex eigenvalue problem. A significant feature of this approach is that an iterative solution for determining the flutter conditions is not necessary, because the equations of motion are independent of frequency. The energy increase in each flutter motion cycle is examined using the work done by the generalized aerodynamic forces or by the self-excited forces along the bridge axis. Accordingly, their contribution to the aerodynamic damping can be clearly identified. The multimode flutter generation mechanism and the roles of flutter derivatives are investigated. Finally, the coupling effects on the buffeting response due to self-excited forces are also discussed.     

Synthesis of Gadolinium-Doped Ceria Powders by Electrolysis of Aqueous Solutions

A gadolinium-doped ceria powder was produced by electrolysis of an aqueous solution containing Ce³⁺ and Gd³⁺ ions using direct and alternating current at 4–10 V of applied voltage between two platinum wire electrodes (anode and cathode). The powders produced were identified as a gadolinium-doped ceria solid solution by X-ray diffraction and chemical analysis. Large porous particles 60–70 μm in size were produced under a direct current field for 15 min. On the other hand, nanoparticles 40–250 nm in size were produced for 6–12 h of electrolysis using alternating current below 20 Hz of frequency. No particles were formed in the high frequency range from 100 Hz to 1 MHz. The nucleation and growth rates of the particles depended on the frequency of the alternating current and electrolysis time applied. The Gd₂O₃/CeO₂ ratio of the particles formed with alternating current was lower than that of the starting solution.     

Comparative study on water structures in polyHEMA and polyMEA by XRD‐DSC simultaneous measurement

We have found that poly(2‐methoxyethylacrylate) (polyMEA) has excellent blood compatibility and proposed that the property is due to freezing bound water in the polymer. This water is defined as that which cold‐crystallizes at around ?45°C in the heating process of differential scanning calorimetry (DSC). In addition, we have already reported that the water in polyMEA is classified into three types, nonfreezing, freezing bound, and free waters, whereas the water in other polymers is just classified into two types: free and nonfreezing waters. (J Biomed Mater Res 68A, 2004, 684) However, the phenomenon observed by DSC is the enthalpy change and is not a direct evidence for crystallization. To confirm cold‐crystallization, a comparative investigation of the thermal and crystallographical properties of water in hydrated polyMEA and poly(2‐hydroxyethylmethacrylate) (polyHEMA) as a control was carried out using simultaneous measurements by X‐ray diffractometer (XRD) and DSC. In addition, the effect of the water content in the polymers on the properties was studied. As for polyMEA, the finding that XRD crystalline peaks appearing in the heating process were assigned to hexagonal ice indicated cold‐crystallization. On the other hand, in the case of polyHEMA, the crystal due to ice was formed only in the cooling process, and during the heating process, the growth of crystal ice was not observed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Optimisation of hydrolysis conditions for the production of the angiotensin-I converting enzyme (ACE) inhibitory peptides from whey protein using response surface methodology

In the present research, the effect of process conditions on the angiotensin-I converting enzyme (ACE) inhibitory activity of whey protein concentrate hydrolysed with crude proteinases preparation from L. helveticus LB13 was investigated systematically using response surface methodology. It was shown that ACE inhibitory activity of the whey hydrolysates could be controlled by regulation of three process conditions (hydrolysis temperature, pH and enzyme to substrate (E/S) ratio). Hydrolysis conditions for optimal ACE inhibition were defined using a response surface model. E/S ratio at 0.60, pH at 9.18 and temperature at 38.9 °C were found to be the optimal conditions to obtain high ACE inhibitory activity close to 92.2% and DH of the whey protein was 18.8%.