Spotty appearance

SR spotty polyurethane. This appears on the metal surface looking like splattered-on polyurethane. It is caused by either surface contamination with dust or the fact that the sprayed-on adhesive has dried as it leaves the spray nozzles. 

After the specimen rod is prepared, it is mounted in its holder so that it will lie accurately along the rotation axis of the camera when the specimen holder is rotated. This adjustment is made by viewing the specimen through a short-focus lens or low-power microscope temporarily inserted into the camera in place of the beam-stop tube the specimen holder is then adjusted so that the specimen does not appear to wobble when the holder is rotated. Rotation of the specimen during the exposure is common practice but not an intrinsic part of the powder method its only purpose is to produce continuous, rather than spotty, diffraction lines by increasing the number of powder particles in reflecting positions. 

Patients with Cushing s disease develop marked osteoporosis which affects the skull, the vertebrae, and other bones. The spotty loss of calcium in the flat bones of the skull leads to the appearance of the moth-eaten skull and the softening of the vertebrae may be so marked that the intervertebral disc burrows into the body of the vertebra. The pathogenesis of osteopor-esis in Cushing s disease is far from elucidated. Osteoporosis can result from decreased osteoblastic activity, increased osteoclastic activity, a negative calcium balance, or the elaboration of an abnormal matrix. 

First of all, it should be stressed that RHEED allows the observation of the phase purity of the layers in real time. During nucleation, a spotty pattern appears, which in itself allows for a judgment of the success of the nucleation procedure, since the symmetries of M- and C-plane GaN are distinctly different. Further growth at Ga-stable conditions yields a streaky RHEED pattern, reflecting the progressive smoothening of the surface. Phase mixture manifests itself in the occurrence of additional reflections (typically spots), which are readily distinguishable from the clean M-plane pattern. In addition, RHEED patterns can also reveal the in-plane orientation relationship between epilayer and substrate. 

---