Nanoindentation creep and uniaxial tension were conducted on pure Mg with a grain size of about 2 μm at room temperature and the data were directly compared. Despite the differences in stress state, the two sets of data were found to match remarkably well with each other. An apparent stress exponent value of 4 was obtained and the deformation mechanism was discussed in light of dislocation slips and twinning in anisotropic Mg.

Alloying effects of iridium on the glass formability (GFA) of the Zr–Ir–Cu–Al system have been investigated, and several new bulk metallic glasses (BMGs) with high GFA have been successfully developed. Additions of Ir in the Zr–Cu–Al system can yield a beneficial distribution in atomic sizes, but the strong chemical interaction of the Zr–Ir atomic pair limits the maximum addable Ir contents and the resultant GFA. Our analyses indicate that the optimum composition for alloying elements is determined by not only topological but also chemical factors. Phase competition upon solidification, rather than effects from individual affecting factors, dictates the GFA of BMG systems.

Hybrid zeolite-polyamide thin film nanocomposite (TFN) reverse osmosis membranes were synthesized by incorporating Linde type A (LTA)-type zeolite molecular sieve nanocrystals in the interfacial polymerization reaction used to form polyamide thin films. Nanocrystals were prepared with two different mobile cations (Na+ and Ag+) exchanged within the LTA crystal matrix. Incorporation of molecular sieve nanocrystals into polyamide thin films during interfacial polymerization was verified by infrared spectroscopy. Both TFN membranes exhibited higher water permeability, while maintaining similar salt rejection to pure polyamide thin film composite membranes. Nanocomposite thin films containing LTA nanocrystals in the silver form (AgA) produced a greater increase in water permeability than those in the sodium form (NaA). Furthermore, AgA-TFN membranes exhibited more hydrophilic and smooth interfaces, which appeared to inhibit adhesion of bacteria cells onto the membranes. The AgA nanocrystals exhibited significant bactericidal activity; however, when encapsulated within polyamide thin films the antimicrobial activity was significantly reduced.

We have developed a soft lithography-based process to create microscale patterns of silica on a diverse array of substrates. A sacrificial polymer layer was first patterned using a micromolding technique. A peptide was adsorbed on the substrate and the sacrificial layer was removed. The patterned peptide template then catalyzed the deposition of silica from a silicic acid solution. With this procedure, we have created both continuous and discontinuous silica patterns on metallic, ceramic, and polymer substrates.

The clean and ordered surfaces of CdZnTe (111)B grown by the Bridgman method were obtained by Ar ion bombardment and thermal annealing in situ in an ultrahigh vacuum. The surface atomic structures of CdZnTe (111)B after annealing at different temperature were observed by low-energy electron diffraction (LEED). The valence band and work function of CdZnTe (111)B surfaces were determined by synchrotron radiation photoemission spectroscopy. The order of CdZnTe (111)B after annealing at 350 °C will worsen, and the (111)B-(2 × 2) local reconstruction will be formed. The work function of CdZnTe (111)B after annealing at 350 °C is 0.8 eV higher than that of CdZnTe (111)B-(1 × 1), and the local reconstruction may be induced by Te adatoms on top of the ideal truncation.

The aim of this work is to study the effect of Nb element doping on the microstructure and electrical properties of lead zirconate stannum titanate (PZST) ceramic and to improve phase transition properties of PZST. Nb-doped Pb(Zr,Sn,Ti)O3 ceramic samples were prepared by the conventional mixed oxide method. Phase transitions induced by temperature, pressure, and electric field were measured with electric dielectric permittivity, hydrostatic pressure, and hysteresis. The microstructure of the samples was observed by electron scanning microscope to discuss the effect of Nb doping on PZST ceramics. The experiment results indicated that the remnant polarization (Pr), dielectric constant, phase transition, and microstructure were strongly dependent on Nb doping content.

Many clay-bearing sedimentary stones such as Portland Brownstone will swell when exposed to water, and this can generate damaging stresses as differential strains evolve during a wetting cycle. Current swelling inhibitors, consisting of α,ω-diaminoalkanes, can reduce swelling in Portland Brownstone up to 50%. In this study, through x-ray diffraction and swelling strain experiments, we demonstrate that the α,ω-diaminoalkanes inhibit swelling by substituting for interlayer cations and partially hydrophobicizing the interlayer, then rehydrating on subsequent wetting cycles. We also introduce the copper (II) ethylenediamine complex as a potential treatment for swelling inhibition.

A poly(acrylic acid)/gelatin interpenetrating network hydrogel was synthesized by aqueous solution polymerization. The influences of preparation conditions including cross-linker, initiator, gelatin content, and neutralization degree on the swelling ratios of the hydrogels are investigated. The swelling, mechanical strength, biodegradability, and drug-release properties of poly(acrylic acid)/gelatin hydrogel are evaluated. The hydrogel has excellent mechanical properties; tensile strength is 1500 kPa, and elongation at break is 887%, respectively. The in vitro biodegradation shows that an interpenetrating network structure exists in the poly(acrylic acid)/gelatin hybrid hydrogel. A release study indicates that the theophylline release from the hydrogel depends on the cross-linking density of the hydrogel and pH of the medium, and the drug diffusion obeys an anomalous transport model.

The structural phase stability and electronic properties of the Ti–Al intermetallic compounds were investigated by means of density-functional theory (DFT) calculations in a generalized gradient approximation. Through comparison of the calculated formation energies of the parent and product phases, an in-depth theoretical understanding of the deformation-induced γ ↔ α2 phase transitions observed previously in TiAl alloys was achieved. The formation energy plays an important role in evaluating the feasibility of these phase transformations during plastic deformation of TiAl alloys. In addition, the density of states (DOS) was also calculated and used to analyze the stability of Ti–Al intermetallic compounds. The reasons for the absence of the deformation-induced (DI)-α2 and DI-γ (L12) phases in underformed TiAl alloys were analyzed.

Sol-gel-derived biocompatible titanium oxide–cerium oxide (TiO2–CeO2) nanocomposite film was deposited onto indium tin oxide (ITO)-coated glass substrate by the dip-coating method. This nanobiocomposite film has been characterized using x-ray diffraction, Fourier transform infrared, atomic force microscope, and electrochemical techniques, respectively. The particle size of the TiO2–CeO2 nanobiocomposite film was found to be 23 nm. The urea biosensor fabricated by immobilizing mixed enzyme [urease (Urs) and glutamate dehydrogenase (GLDH)] on this nanobiocomposite showed a response time of 10 s, sensitivity as 0.9165 μAcm−2mM−1, detection limit of 0.166 μM, and negligible effect due to interferants uric acid, cholesterol, glucose, and ascorbic acid. The value of Michaelis–Menten constant (Km) estimated using Lineweaver–Burke plot as 4.8 mM indicated enhancement in the affinity and/or activity of enzyme attached to their nanobiocomposite. This bioelectrode retained 95% of enzyme activity after 6 months at 4 °C.

A double-angle indenter model is proposed to determine the representative strain in the indentation process, and a new method is then developed aiming at the extraction of the yield strength and strain-hardening exponent from the surface layer of metals, because surface properties, especially in a small region, may differ from bulk ones and are sometimes closer to service properties such as fatigue strength, wear, and corrosion resistance. First, the isotropic metal was analyzed, the elastic modulus of which was fixed at 128 GPa, the yield strength was 50 to 200 MPa, and the strain-hardening exponent was 0.1 to 0.5. By introducing the yield strain to substitute the yield strength in the calculation, it was proved that the model can cover the majority of metals because the introduced weight parameter λ is independent of the yield strength and the elastic modulus, although it depends on the strain-hardening exponent to some extent. For the determination of yield strain εY (or yield strength Y), the precision is better for low C/E and low n, whereas for the determination of strain-hardening exponent n, the precision is better for high C/E and low εY. By using the double-angle indenter, the material constitutive relationship at the surface can be evaluated from just one indentation without any other measurements.

We report on a novel biocompatible hierarchical TiO2 porous coating on the surface of Ti, processed via anodic oxidation. The coating consists of large (∼1–20 μm) pores on the microscale and nanotubes (∼50 nm diameter) on the nanoscale. This structure is exciting because of its potential application as a bioactive coating for Ti bone implants. Surface characterization of the coating showed nanotubes of relatively uniform diameter. The interface between TiO2 nanotubes and Ti, studied by transmission electron microscopy, was incoherent. The tubes were also somewhat interconnected.

The orientation relationships among TiB (B27), B2, and Ti3Al phases have been investigated by transmission electron microscopy. By using the composite selected-area electron diffraction technique, the orientation relationship between TiB (B27) and B2 was determined to be [100]TiB[001]B2, (001)TiB(010)B2; and that between TiB (B27) and Ti3Al was . These orientation relationships have been predicted precisely by the method of coincidence of reciprocal lattice points.

The deformation behavior and indentation size effect (ISE) in amorphous and crystallized Pd40Cu30Ni10P20 alloy were comparatively studied through instrumented nanoindentation. It was found that the two alloys showed different deformation behaviors, the amorphous alloy exhibited conspicuous pop-in events in the load-depth (P-h) curve, while the crystallized alloy showed a relatively smooth P-h curve. In addition, the indentation hardness was observed to decrease with increasing penetration depth in the two alloys, exhibiting a significant ISE. However, the crystallized alloy displayed a sharper reduction of hardness with indentation depth as compared to the amorphous alloy, indicating a more significant indentation size effect in the crystalline alloy. The structure difference and friction factor associated with the surface residual stress are taken into account to interpret the difference in the deformation behavior and indentation size effect of the two alloys.

Histidine is an amino acid present in proteins involved in biosilica formation and often found in peptides identified during phage display studies but its role(s) and the extent of its involvement in the silica precipitation process is not fully understood. In this contribution we describe results from an in vitro silicification study conducted using poly-histidine (P-His) and a series of different molecular weight synthetic polymers containing the imidazole functionality (polyvinylimidazole, PVI) for comparison. We show that the presence of imidazole from PVI or P-His is able to catalyze silicic acid condensation; the effect being greater for P-His. The catalytic mechanism is proposed to involve the dual features of the imidazole group—its ability to form hydrogen bonds with silicic acid and electrostatic attraction toward oligomeric silicic acid species.

Luminescent silica nanotubes and nanowires were fabricated from cellulose whisker templates by sol-gel processing. The cellulose templates were removed by calcination at 650 °C to generate silica nanotubes with diameters of 15 nm and lengths up to 500 nm. At temperatures of 900 °C the core region previously occupied by the cellulose template was closed yielding silica nanowires. Cathodoluminescence spectra of the silica nanotubes and nanowires were measured in the transmission electron microscope during irradiation with 150 keV electrons. A blue emission at 450 nm was observed for the silica nanowires calcined at 900 °C. This luminescence was found to be related to defects induced by electron irradiation and was investigated in situ as a function of irradiation dose. The as-synthesized and 650 °C calcined nanowires and nanotubes showed a fast decay of the signal. The observed irradiation dose dependent changes in the luminescence spectra will be discussed in terms of defect formation and transformation mechanisms.

Ferromagnetic Cu-doped GaN film was grown on a GaN-buffered sapphire (0001) substrate by a hybrid physical-chemical-vapor-deposition method (HPCVD). The GaCuN film (Cu: 3.6 at.%) has a highly c-axis-oriented hexagonal wurtzite crystal structure, which is similar to GaN buffer but without any secondary phases such as metallic Cu, CuxNy, and CuxGay compounds. Two weak near-band edge (NBE) emissions at 3.38 eV and donor-acceptor-pair (DAP) transition at 3.2 eV with a typical strong broad yellow emission were observed in photoluminescence spectra for GaN buffer. In contrast, the yellow emission was completely quenched in GaCuN film because Ga vacancies causing the observed yellow emission in undoped GaN were substituted by Cu atoms. In addition, GaCuN film exhibits a blue shift of NBE emission, which could be explained with the +2 oxidation state of Cu ions, replacing +3 Ga ions resulting in band gap increment. The valance sate of Cu in GaCuN film was also confirmed by x-ray photoelectron spectroscopy (XPS) analysis. The GaCuN film shows ferromagnetic ordering and possesses a residual magnetization of 0.12 emu/cm3 and a coercive field of 264 Oe at room temperature. The unpaired spins in Cu2+ ions (d9) are most likely to be responsible for the observed ferromagnetism in GaCuN.

The grain size of magnesium solid-solution alloys with lithium, indium, and/or zinc has been determined. Lithium, indium, and zinc additions decreased the grain size, D, of magnesium solid-solution alloys cast in a copper mold. The most effective grain refinement was obtained by zinc. In binary Mg–Zn alloys, grain size is related to the growth restriction factor, Q as D = 94 + 312/Q. In Mg–Li and Mg–In binary alloys, grain size versus growth relationships described as D = a + b/Q indicated that these alloys have lower numbers of nucleants but with higher potency than the Mg–Zn binary system. For Mg–Li and especially Mg–In, grain size could be related to growth restriction as D = 383Q−n with higher R2. Ternary and quaternary alloys based on Mg–Zn with Li and/or In additions also follow the D = a + b/Q relationship with the parameters indicating a larger number of lower potency nucleants than the Mg–Zn binary alloys. Electron probe microanalysis showed that Mg–Zn alloys exhibit pronounced and persistent grain-boundary enrichment of Zn, pointing toward Scheil solidification.

Sm3+, Ce3+ codoped Al2O3–La2O3–SiO2 glasses were prepared and their luminescence properties were characterized. Blue-cyan to orange-red tunable luminescence was observed from these glasses with different excitation wavelengths ranging from 385 to 410 nm. White light emission with internal luminescence efficiency 42% has been observed using commercially available purple light-emitting-diode excitation. The energy transfer between Ce3+ and Sm3+ has also been investigated from fluorescence decay curves and spectral properties.

Well-ordered nanoporous anodic aluminum oxide (AAO) templates have been prepared on aluminum substrates by a two-step anodization process. A voltage-controlled branching method was successfully used to thin the barrier layer of the AAO template. The nanostructures of the pores, the branched subpores, and the barrier layer in the AAO template were studied in association with the anodization process and barrier layer thinning methods. Results demonstrate the voltage-controlled branching method is a facile and effective way to thin the barrier layer. Uniform silver nanowires can be easily fabricated using alternating current (ac) electrodeposition into the pores of AAO after redressing the barrier layer.