We have mapped the full crystallographic orientation of sea ice using electron backscatter diffraction (EBSD). This is the first time EBSD has been used to study sea ice. Platelet ice is a feature of sea ice near ice shelves. Ice crystals accumulate as an unconsolidated sub-ice platelet layer beneath the columnar ice (CI), where they are subsumed by the advancing sea–ice interface to form incorporated platelet ice (PI). As is well known, in CI the crystal preferred orientation comprises dominantly horizontal c-axes, while PI has c-axes varying between horizontal and vertical. For the first time, this study shows the a-axes of CI and PI are not random. Misorientation analysis has been used to illuminate the possible drivers of these alignments. In CI the misorientation angle distribution from random pairs and neighbour pairs of grains are indistinguishable, indicating the distributions are a consequence of crystal preferred orientation. Geometric selection during growth will develop the a-axis alignment in CI if ice growth in water is fastest parallel to the a-axis, as has previously been hypothesised. In contrast, in PI random-pair and neighbour-pair misorientation distributions are significantly different, suggesting mechanical rotation of crystals at grain boundaries as the most likely explanation.

Phase maps of Co–Cr alloys bonded to dental porcelain cycled through an incremental number of porcelain firings at two separate thicknesses (0.5 and 1 mm) were analyzed. Bulk hexagonal close-packed (hcp) phase vol% of the alloy was found to increase with the number of porcelain firings for both 0.5 and 1 mm specimens. At the metal-porcelain interface, a uniform fine-grained hcp phase was observed. The depth and grain size of this hcp layer increased with the number of porcelain firings with the thicker specimens undergoing more substantial growth and transformation. Simple heat transfer modeling of the specimens during heat treatment cycles indicated that the thicker specimen had more time at high temperature to affect the face-centered cubic to hcp phase transformation. Therefore, the amount of porcelain firings and the thickness of the alloy should be considered and kept to a minimal when manufacturing metal-porcelain restoration.

Dust particles in an ice core from East Rongbuk Glacier on the northern slope of Qomolangma (Mount Everest; 28°01′ N, 86°58′ E; 6518 m a.s.l.), central Himalaya, have been identified as mica using a combination of scanning electron microscope-based techniques and energy-dispersive X-ray spectroscopy to identify the elements present, and electron backscatter diffraction to identify the crystal type. This technique for identifying individual crystalline dust particles in samples of glacial ice could be especially useful in the future for identifying water-soluble crystals in ice, for studying the strain history (glaciotectonics) of basal ice or in studies of ice–mica composites used as analogs of quartz-mica rocks.

A fire-mediated recruitment bottleneck provides a possible explanation for the coexistence of trees and grasses in mesic savannas. The key element of this hypothesis is that saplings are particularly vulnerable to fire because they are small enough to be top-killed by grass fires, but unlike juveniles, they take several years to recover their original size. This limits the number of recruits into the adult size classes. Thus savanna vegetation may be maintained by a feedback whereby fire restricts the density of adult trees and allows a grass layer to develop, which provides fuel for subsequent fires. Here, we use results from a landscape-scale fire experiment in tropical Australia, to explore the possible existence of a recruitment bottleneck. This experiment compared tree recruitment and survival over 4 y under regimes of no fire, annual early and annual late dry-season fire. Stem mortality decreased with increasing stem height in the fire treatments but not in the unburnt treatment. Tree recruitment was 76–84% lower in the fire treatments than the unburnt treatment. Such fire-induced stem loss of saplings and reduced recruitment to the canopy layer in this eucalypt savanna are consistent with the predictions of the fire-mediated recruitment bottleneck hypothesis.

We have developed a system using ‘forescatter detectors’ for backscattered imaging of specimen surfaces inclined at 50–80° to the incident beam (inclined-scanning) in the SEM. These detectors comprise semiconductor chips placed below the tilted specimen. Forescatter detectors provide an orientation contrast (OC) image to complement quantitative crystallographic data from electron backscatter patterns (EBSP). Specimens were imaged using two detector geometries and these images were compared to those collected with the specimen surface normal to the incident beam (normal-scanning) using conventional backscattered electron detector geometries and also to an automated technique, orientation imaging microscopy (OIM). When normal-scanning, the component of the BSE signal relating to the mean atomic number (z) of the material is an order of magnitude greater than any OC component, making OC imaging in polyphase specimens almost impossible. Images formed in inclined-scanning, using forescatter detectors, have OC and z-contrast signals of similar magnitude, allowing OC imaging in polyphase specimens.

OC imaging is purely qualitative, and by repeatedly imaging the same area using different specimen-beam geometries, we found that a single image picks out less than 60% of the total microstructural information and as many as 6 combined images are required to give the full data set. The OIM technique is limited by the EBSP resolution (1–2°) and subsequently misses a lot of microstructural information. The use of forescatter detectors is the most practical means of imaging OC in tilted specimens, but it is also a powerful tool in its own right for imaging microstructures in polyphase specimens, an essential asset for geological work.