The determination of residual stresses via X-ray diffraction is briefly reviewed, with particular emphasis on the triaxial stress state. A new method is proposed for determining the general stress tensor, which considerably reduces the variances of the stresses due to counting statistics and gradients. The procedure involves a generalised least-squares solution of strains measured at various tilts of the X-ray beam to the sample, and a new set of tilts is recommended to minimise these errors.

This qualitative case study examines the initial implementation of a problem-based version of an undergraduate course in materials science for the purpose of identifying areas of improvement to the curriculum prior to a planned second implementation. The course was designed around problems that students work in small teams to solve under the guidance of facilitators, with early sequence problems designed to foster the problem-solving skills required to succeed in the course. This report describes students' impressions of and experiences in the course as they worked to solve the final problem at the end of the semester and compares those impressions, where applicable, to impressions gathered after they had completed the first problem near the beginning of the semester. Using grounded theory techniques to analyze the data, six central themes emerged from the implementation: course structure, facilitation roles, student roles, group processes, coconstruction, and resources. Implications for practice and potential instructional design solutions that may aid in future implementations are discussed.

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Qualitative observation of flow patterns in water and nanofluid oscillating heat pipes was conducted at various heat inputs and condenser temperatures. Images of the liquid flow within the copper tubing were first captured at 30 frames per second using neutron radiography. Neutron radiography allows direct observation of a fluid position because liquid water is hydrogen rich and opaque while water vapor (because it is much less dense) and the other materials in the oscillating heat pipes are transparent. Flow visualization was conducted on an 8-turn water oscillating heat pipe, an 8-turn nanofluid oscillating heat pipe, and a 12-turn nanofluid oscillating heat pipe. The water oscillating heat pipe was filled with high performance liquid chromatography grade water. The 12-turn nanofluid oscillating heat pipe was filled with 1% by volume (35:0 g ml 1 ) diamond nanoparticles in high performance liquid chromatography water and the 8-turn oscillating heat pipe contained 0.016% by volume (0:5 mg ml 1 ) diamond nanoparticles high performance liquid chromatography water. The diamond nanoparticles were 5 to 50 nm in diameter. All oscillating heat pipes were charged at a filling ratio of 50%. Visual observation shows for all heat pipes that at low heat inputs, fluid oscillation is very random and intermittent. Increasing the heat input causes a steady flow pattern to appear. For all tested oscillating heat pipes, increased heat load or operating temperature resulted in an increased fluid velocity. Also, nucleation was never observed in the tested oscillating heat pipes.

Oscillating heat pipes (OHPs) provide a promising heat transfer device for a variety of applications, including the cooling of electronic devices. Recently, it has been shown that a hydrophilic, nanostructured cupric oxide (CuO) coating can significantly enhance the thermal performance of copper OHPs that use water as the working fluid. Motivated by these results, we report neutron scattering and electron microscopy (EM) measurements to investigate the interaction of water with copper-oxide surfaces on the nanoscale. Our measurements confirm earlier observations of a thin cuprous oxide (Cu 2 O) layer growing on a bare copper substrate followed by "grass-like" CuO nanostructures. New evidence of the nanostructure hydrophilicity is provided by EM measurements of wetting and by our high-energy-resolution elastic neutron scattering measurements, showing a continuous freezing and melting of the water in our samples over a temperature range of ∼80 K. In addition, our neutron diffraction measurements are consistent with water closest to the CuO nanostructures freezing into an amorphous solid at low levels of hydration and hexagonal ice at higher hydration. In short, our findings support a strong interaction of water with the CuO nanostructures, which could significantly affect the operation of an OHP.