Regenerated silk fibroin (RSF) fibers were directly dry-spun from RSF aqueous solutions into air. To improve mechanical properties of fiber, the as-spun fibers were postdrawn in 80 vol.% ethanol aqueous solution, in which an immersion process was performed subsequently. With the increase in draw ratio, the fibers show substantial improvements of orientation and mechanical properties. Quantitative analysis of Fourier transform infrared spectroscopy indicates that the ratio of β-sheet to α-helix conformation increases sharply at the beginning of immersion process, then approaches a constant value after 90 min of immersion. All fibers exhibit very smooth surfaces. There is no obvious relationship between the pH of the spinning dope and the mechanical properties of the regenerated fibers. The breaking stress of the posttreated fiber is improved up to 301 MPa, which approaches that of degummed silk. The posttreated fiber is over three times the breaking energy of degummed silk.

Bi1.95La1.05TiNbO9 (BLTN-1.05) thin films were prepared on fused quartz substrates by pulsed laser deposition. The x-ray diffraction (XRD) analysis and atomic force microscope (AFM) surface morphology measurements were performed on the samples. The XRD pattern demonstrated that the films are single-phase perovskite structured and well crystallized. The AFM analysis indicated that the films have less rough surface. The fundamental optical constants were obtained through optical transmittance measurements. The nonlinear optical properties of BLTN thin films were measured by a single beam Z-scan technique under 1064 nm excitation. The real and imaginary parts of the third-order nonlinear optical susceptibility χ(3) of the film were measured to be 9.56 × 10−9 and −3.67 × 10−9 esu, respectively. The Z-scan results show that BLTN thin films have potential applications in nonlinear optics.

We report the results of an investigation on the structural evolution of a potential new thermoelectric material, Cu3SbSe3, as a function of temperature from 25 to 390 °C. From high-temperature x-ray diffraction data, the refined lattice parameters were seen to change nonlinearly, but continuously, with temperature, with an increased rate of thermal expansion in the a and b lattice parameters from around 125 °C to 175 °C and negative thermal expansion in the c axis from around 100 °C to 175 °C. Crystallographic charge flipping analysis indicated an increase in the disorder of the copper cations with temperature. This reversible order/disorder phase transition in Cu3SbSe3 affects the transport properties, as evidenced by thermal conductivity measurements, which change from negative to positive slope at the transition temperature. This structural change in Cu3SbSe3 has implications for its potential use in thermoelectric generators.

Nanocrystalline silicon thin films were fabricated using a vacuum arc discharge technique. These thin films can be deposited on plastic substrates effectively when cooled by a cryogenic substrate holder. We used single crystal silicon wafers as both the electrodes to ignite the vacuum arc and the silicon ion source to deposit thin films. This resulted in nanocrystalline silicon clusters embedded in the amorphous silicon matrix. This thin film has highly crystalline volume (≈87%), which enhanced the absorption in wide range of wavelengths. Without ion implantation, the in situ doping of p- or n-type thin films can also be achieved. This thin film deposition process has its potential for fabricating thin film transistors and photovoltaic cells on plastic substrates at fairly low production costs.

We describe experiments on self-heating and melting of nanocrystalline silicon microwires using single high-amplitude microsecond voltage pulses, which result in growth of large single-crystal domains upon resolidification. Extremely high current densities (>20 MA/cm2) and consequent high temperatures (1700 K) and temperature gradients (1 K/nm) along the microwires give rise to strong thermoelectric effects. The thermoelectric effects are characterized through capture and analysis of light emission from the self-heated wires biased with lower magnitude direct current/alternating current voltages. The hottest spot on the wires consistently appears closer to the lower potential end for n-type microwires and to the higher potential end for p-type microwires. The experimental light emission profiles are used to verify the mathematical models and material parameters used for the simulations. Good agreement between experimental and simulated profiles indicates that these models can be used to predict and design optimum geometry and bias conditions for current-induced crystallization of microstructures.

We propose a phenomenological Landau theory to describe polymorphic melting in binary solid solutions. We use the mean atomic displacement as the primary order parameter to represent the loss of the long-range order and the elastic strain induced by alloy component as the secondary order parameter. Under polymorphic constraint where alloy concentration fluctuation is restricted, the model predicts the melting line, also called T0-curve that is depressed by two factors, the static strain field caused by the solute, and the anharmonicity induced by the thermal vibration. We also obtain other thermodynamic properties at and around the melting point. The results confirm well with available experimental results for dilute solutions. We extrapolate the melting line to high concentration region for which no experimental data are available. From the results, we discuss the relation between polymorphic melting and glass transition, as well as glass formability.

In a 2.25Cr1.5W heat-resistant alloy, it is shown that the time to intergranular failure under tensile stress t can be expressed by , where t0 is the constant of proportionality, n is the stress exponent, and Q is the activation enthalpy. It is shown that the dimples observed at elevated-temperature intergranular fracture surfaces are not the micro-ductile fracture areas but the interfaces between the grain boundary carbides and the neighboring grains. It is also shown that the segregation concentration of solute atoms is much higher at the grain boundary carbide interfaces than at the carbide-free grain boundaries. Under tensile stress, the elevated-temperature intergranular cracking occurs through the decohesion of grain boundary carbide interfaces, which is followed by the eventual carbide-free grain boundary cracking.

Education research strongly indicates that students make decisions in their mid- to late adolescence that impact the general direction of their careers, including choices about pursuing studies in science and mathematics. Educators can play an important role in these student career choices. By creating and implementing teacher professional development programs that increase teachers’ awareness/understanding of materials science and providing materials science-based classroom materials, researchers can take concrete actions toward improving the number and quality of students entering materials science and engineering departments as undergraduate students. No matter where you live or work throughout the world, there is a school nearby and abundant opportunities for researchers to make a difference in K–12 science education.