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Anatase thin films spin coated on soda–lime–silica (SLS) glass and unpolished (001) rutile were annealed at 200–550 °C for 8 h, followed by GAXRD, Raman, XPS, SIMS, AFM, TEM, UV–Vis, ellipsometry, and MB dye degradation. Films on SLS substrates annealed at 200–350 °C were amorphous but those annealed at 450°–550 °C consisted of anatase; the rutile substrates gave epitaxial rutile films. Annealing caused diffusion of glass ions into the films and counterdiffusion of Ti into the glass substrates. The decrease in glass ion concentrations during aqueous MB testing shows that grain boundary diffusion occurred. The AFM, TEM, and UV–Vis data were affected by the substrate topographies, where SLS was smooth and rutile was rough/uneven. Decreasing Eg in the anatase films with increasing annealing temperature was attributed to increasing crystallinity (heterogeneous nucleation) while the same effect in the rutile films was attributed to the substrate topography (homogeneous nucleation). The anatase films photocatalytically outperformed the rutile films; this was attributed to the potential to form midgap states from oxygen vacancy formation and/or Ti vacancy formation (deriving from the Ti counter-diffusion). However, the deep energy levels of these defects suggest that the performance is dominated by the crystallinity and blockage of the active sites.

The present work reports data for TiO2 thin films on borosilicate glass and (001) single-crystal TiO2, annealed at 200–550 °C for 8 h. Characterization included GAXRD, laser Raman microspectroscopy, AFM, UV–Vis, XPS, SIMS, TEM, ellipsometry, and methylene blue (MB) dye degradation. The substrate determined the TiO2 polymorph that formed, while the annealing temperature and boron contamination from the substrate determined most of the associated properties. The films on glass substrates were amorphous following annealing at 200 °C but were anatase at higher temperatures. The films on rutile exhibited epitaxial growth at all annealing temperatures. Annealing caused diffusion of glass component elements into the films and counterdiffusion of Ti into the glass substrates. Since aqueous MB testing caused decreased glass ion concentrations, the diffusion mechanism is via the grain boundaries. Volatilization of boron occurred during annealing at 550 °C. The morphological features dominated the optical properties; the anatase films exhibited high transmissions and low reflectances, while the rutile films exhibited the converse. The band gap decreased slightly with increasing annealing temperatures, reflecting increasing crystallinity. The refractive indices showed an anomalous trend of decrease with increasing annealing temperature and associated crystallinity; this is attributed to the effects of boron volatilization and associated air-filled pore formation. Although the anatase films outperformed the rutile films, the effect of annealing temperature is likely to have been dominant in that it determined the relative extents of crystallinity, grain size, RMS roughness, optical indirect band gap, and oxygen vacancy concentration.

The present work reports data for TiO2 thin films spin coated on unpolished fused silica (FS) and unpolished (001) rutile annealed at 200°, 350°, 450°, and 550 °C for 8 h in air. Characterization/testing consisted of glancing-angle X-ray diffraction, laser Raman microspectroscopy, atomic force microscopy, UV–Vis spectrophotometry, X-ray photoelectron spectroscopy, secondary ion mass spectrometry, transmission electron microscopy, and methylene blue (MB) photodegradation. The recrystallization depended on the type of substrate, where FS substrates yielded Si-contaminated anatase films of limited crystallinity (amorphous at 200 °C) and thickness ~160–200 nm while the rutile substrates resulted in well crystallized epitaxial films of ~200–300 nm thickness. The Si grain boundary diffusion coefficients were 4.59 × 10−19 m2s (200 °C) and 5.00 × 10−19 m2s (550 °C). This diffusion mechanism was supported by the XPS data before and after MB aqueous solution testing, which suggested that Si contamination was on the grain boundaries and was leached during testing. The thickness of all films increased slightly as the annealing temperature increased, which resulted from grain rearrangement and growth. The optical transmissions of all films were low and the reflectances higher, which resulted from the roughness and unevenness of the films. The optical indirect band gaps (Eg) from transmission and reflectance spectrophotometries decreased for the anatase films but increased for the rutile films with increasing annealing temperature. These trends reflect the dominance of competing mechanisms, where recrystallization and Eg decrease are dominant for anatase but void formation and Eg increase are dominant for rutile. The photocatalytic performances of the anatase films were superior to those of the rutile films. The performances corresponded to the annealing temperatures and so were linked directly to the crystallinity and, to a lesser extent, the surface area (reflected by the roughness and unevenness) since the other factors examined were inconsistent with the performance data.

Highly-transparent V-doped TiO2 thin films were prepared by sol-gel processing, spin coated on fused silica glass substrates, and annealed in air at 450 °C for 2 h. All of the films were comprised of anatase as the sole crystalline phase. The XPS data suggested that V formed an interstitial solid solution with anatase. The formation of an unsaturated solid solution at the lowest doping level of 0.05 mol% resulted in the formation of lattice defect sites, which enhanced anatase recrystallisation, grain growth, and crystallinity. In contrast, the formation of supersaturated/oversaturated solid solutions at the higher doping levels of 0.10–1.00 mol% resulted in lattice deformation, partial amorphisation, precipitation, and liquid formation. The coexistence of multiple valence states, viz., Ti4+/3+, V4+/3+, and possibly V5+ in the doped TiO2 films was attributed to intervalence charge transfer. Dye degradation tests revealed that the 0.05 mol% V-doped films showed the best photocatalyic performance and this was attributed to the combined effects of greater anatase crystallinity and reduced band gap. In contrast, increasing V-doping levels resulted in gradual decreases in the photocatalytic performance, which are attributed principally to the decrease in areal density of the surface-active sites owing to liquid-phase densification. The greater degradation of MB solution relative to that of RhB solution is attributed principally to the cationic nature of MB, which allows greater adsorption on the photocatalyst surface in comparison to the anionic RhB.

Ensuring the stability of reservoir slopes requires a comprehensive understanding of the mechanical properties of rocks after the drying–wetting cycles under acidic conditions. In this work, sandstone samples were selected and subjected to cyclic drying–wetting treatments with aqueous solutions of pH 7.0, 6.0, 4.0, and 2.0. The uniaxial compression tests and P-wave velocity measurement were carried out to evaluate the variations in the physico-mechanical properties of sandstones with different treatments. The results revealed that the internal structure of sandstones is softened by the drying–wetting cycles, which deteriorate their physico-mechanical properties. As the acidity of the aqueous solution increases, porosity and Poisson’s ratio show an increasing trend, while the strength characteristics, Young’s modulus, and P-wave velocity of sandstones present a decreasing trend. The physico-mechanical properties of sandstones significantly deteriorate from neutral to weakly acidic solutions; however, the deterioration becomes slower as the acidity continues to increase. Moreover, the physico-mechanical properties of sandstones are markedly reduced under strong acidic conditions.

TiO 2 thin films with varying Mn and Fe dopant levels (0.01–5.00 mol% metal basis; single cation doping and codoping) were deposited on soda-lime-silica glass substrates by spin coating, followed by annealing in air at 450 °C for 2 h. The mineralogical, morphological, optical, and photocatalytic properties of the thin films were determined. The fabricated films were ∼250 nm thick and they were comprised of grains of ∼20–30 nm size. Anatase (or amorphous titania) was the only phase in essentially all the films, with the dopants' being soluble in anatase. All of the films were transparent (∼80%) in the visible region and the optical indirect band gaps were ∼3.4 eV. Photocatalytic testing (≤24 h) showed that the extent of photodegradation decreased with increasing dopant levels. The 0.01 mol% Fe-doped sample showed the best photoactivity since, at this doping level, the negative effects of electron/hole recombination and lattice distortion probably were minimal.

Vibration is often a problem causing poor quality of photon beams at synchrotron radiation facilities, since beamlines are quite sensitive to vibrations. Therefore, vibration analysis and control at synchrotron radiation facilities is crucial. This paper presents investigations on mechanical vibrations at four beamlines and endstations at the Canadian Light Source, i.e. the Canadian Macromolecular Crystallography Facility 08ID-1 beamline, the Hard X-ray MicroAnalysis 06ID-1 beamline, the Resonant Elastic and Inelastic Soft X-ray Scattering 10ID-2 beamline, and the Scanning Transmission X-ray Microscope endstation at the Spectromicroscopy 10ID-1 beamline. This study identifies vibration sources and investigates the influence of mechanical vibrations on beamline performance. The results show that vibrations caused by movable mechanical equipment significantly affect the data acquired from beamlines.

In this study we aimed at investigating size effects on mechanical properties of cranial suture in different animal research models. Lewis rats and C57BL/6 mice were selected as the larger research model and smaller research model, respectively. The objective of this study was to determine the mechanical properties of different cranial modules of cranial sutures in Lewis rats and same-aged C57BL/6 mice. Ten sagittal sutures were harvested from 4-month-old Lewis rats and C57BL/6 mice. The specimens, kept moist, were mounted fresh and distracted until rupture. A load–displacement curve was constructed. The stiffness, Young's modulus, fracture stress and fracture energy were calculated. Moreover, scanning electron microscope (SEM) images and fracture mechanisms are discussed. Cranial modules in Lewis rats and same-aged C57BL/6 mice are also provided. The results show differences between the two groups, with higher values from Lewis rat. Higher mechanical properties occurred mainly on the large type of cranial module in this mammalian system.

In this paper, the stress states of a sand particle (or aggregate) with an interface layer in a cement paste (or mortar) subjected to uniaxial compression or tension are studied. This is a dual layer inclusion problem. The general analytical solutions of stresses and deformations are obtained in closed form, and the solutions of several special cases including the sand (or aggregate) treated as rigid body and as a hole as well as when the thickness of the interface layer approaches zero are also given.

In this paper, the influence of geometrical and physical parameters (size of the sand particle, thickness of the interface layer and ratios of the modulus of elasticity) on stress distributions in a mortar is studied. It is found that a weak or soft interface layer in the mortar will greatly reduce the strength of the concrete ; if the modulus of the interface layer approaches to that of the cement paste and the modulus of the sand particle (or aggregate) is 4-10 times as large as that of the cement paste, the concrete will possess a much higher strength and thus has a better property.

The stability behavior of rigid and semirigid frames bent in the weak axis is investigated using a hardening plastic hinge method. The stability limit load of frames is usually overpredicted by the simple plastic hinge analysis neglecting the effect of partial plastification. The plastic zone analysis can predict the limit load more accurately but a large number of elements must be used. Hence, it is costly and time‐consuming. An alternative method called the “hardening plastic hinge method” is developed here for practical use. In the proposed method, one element is used per beam‐column. The initial yield surface including residual stress is first determined from the normalized moment‐curvature‐thrust relationship of W8×31 section. The member stiffness is then modified to simulate the effect of partial plastification through the concept of work‐hardening in which the average degradation of tangent stiffness of a cross section is calibrated against the slopes of the exact moment‐curvature‐thrust relationsh...

The present state of some key aspects of development of concrete plasticity is summarized. Emphasis is placed on the representation and interpretation of the inelastic deformation of concrete materials in the post-elastic range. The development of plasticity-based models in prepeak stress range is first summarized, emphasizing the fundamental concepts peculiar to concrete materials. A general formulation of softening behavior by the plasticity theory combined with the fracturing (damage) theory is then discussed. Next, recent studies relating macrospace features and microscopic events are presented. Finally, the role of cement-paste-sand interfaces in providing a deeper understanding of the concrete materials at the microscale are explored. Directions for further research are indicated.

The methods of simple plastic analysis and design are based on two basic assumptions. The first assumes that the structure is made of a ductile material such as steel that is able to absorb large deformations beyond the elastic limit without the danger of fracture. The second is that the deflections of a structural system under loading are small such that the effect of this upon the overall geometry can be ignored. Herein, we shall discuss the practicality of these assumptions and the limitations introduced by them in the methods of simple plastic analysis and design.

A complete constitutive relationship for the time-independent nonlinear behavior of reinforced concrete is presented. The nonlinear features include the inelastic responses of concrete and steel reinforcements, prediction of concrete fracture under multiaxial stress states, and post-failure behavior of fractured concrete. Moreover, the interaction effects between concrete and steel rebars are included in finite element stiffness calculations by considering tension stiffening and shear transferring due to dowel actions. The constitutive relationship was implemented into a nonlinear finite element program to investigate the deformation behavior of four reinforced concrete panels. Numerical results obtained from the finite element analysis are compared favorably with the available experimental data.

The upper bound technique of limit analysis has been found to be very successful in analyzing the stability of cuttings in normally consolidated clays. However, most soils in their natural states exhibit some anisotropy with respect to shear strength, and some nonhomogeneity with respect to depth. It is difficult to obtain the solution based on the classical limit equilibrium analysis with the assumed noncircular failure plane with such soil properties included. This paper establishes an expression for the stability factor Ns, based on the upper bound technique of limit analysis which yields a close-formed solution for sections in which the following conditions are considered: (a) log-spiral failure-plane, through and below toe; (b) non-homogeneity; (c) anisotropy; and (d) general slope.

The surface of 260 iron particles has been coated with a Co ferrite layer by chemical coprecipitation method. The Co ferrite layer causes a decrease of specific magnetization and increase of hyperfine field of a-Fe core. The effect of the Co ferrite layer on Hc belongs to an interface effect.

A constitutive relation and failure criterion for concrete material under general three-dimensional stress states has been developed using the work-hardening theory of plasticity. The formulation has all the required properties of concrete and gives a close estimate to experimental stresses for complete general stress states. In order that the results of research be readily usable in the analysis of suboceanic structures such as the large shells proposed for adoption in the Ocean Thermal Energy Conversion program (OTEC), corresponding computer codes have also been developed to reflect this material response. The proposed material model has been applied to several selected concrete and reinforced concrete shell structures. The finite-element subroutine for the NONSAP program has been modified and applied to analyze plain and reinforced concrete shell specimens of cone-, cylinder-, and dome-shapes under monotonically increasing axial load condition. The finite-element solid program (EPFFEP) has also been developed and applied to study the behavior of concrete cylindrical hulls under hydrostatic loading conditions. The analytical results are compared with corresponding experimental data. Preliminary results indicate a close agreement to the experimental failure load.