Time-resolved x-ray diffraction techniques for bulk polycrystalline materials under dynamic loading.

We have developed two techniques for time-resolved x-ray diffraction from bulk polycrystalline materials during dynamic loading. In the first technique, we synchronize a fast detector with loading of samples at strain rates of ~10(3)-10(4) s(-1) in a compression Kolsky bar (split Hopkinson pressure bar) apparatus to obtain in situ diffraction patterns with exposures as short as 70 ns. This approach employs moderate x-ray energies (10-20 keV) and is well suited to weakly absorbing materials such as magnesium alloys.

Grains and grain boundaries in single-layer graphene atomic patchwork quilts.

The properties of polycrystalline materials are often dominated by the size of their grains and by the atomic structure of their grain boundaries. These effects should be especially pronounced in two-dimensional materials, where even a line defect can divide and disrupt a crystal. These issues take on practical significance in graphene, which is a hexagonal, two-dimensional crystal of carbon atoms.

Retrospective analysis of prognostic factors after liver resection and transplantation for cholangiocellular carcinoma.

Background: Cholangiocellular carcinoma is an uncommon primary liver cancer, which may be mixed with hepatocellular carcinoma. A retrospective analysis was undertaken to evaluate the results of surgical treatment and to identify prognostic factors.

Methods: Between 1978 and 1996, 162 patients underwent surgery for cholangiocellular carcinoma: liver resection (n = 95), liver transplantation (n = 24) and exploratory laparotomy with and without drainage (n = 43).