Analysis of SAW properties of epitaxial ZnO films grown on R-Al2O3 substrates.

ZnO thin films with a high piezoelectric coupling coefficient are widely used for high frequency and low loss surface acoustic wave (SAW) devices when the film is deposited on top of a high acoustic velocity substrate, such as diamond or sapphire. The performance of these devices is critically dependent on the quality of the ZnO films as well as of the interface between ZnO and the substrate. In this paper, we report the studies on piezoelectric properties of epitaxial (1120) ZnO thin films grown on R-plane sapphire substrates using metal organic chemical vapor deposition (MOCVD) technique. The c-axis of the ZnO film is in-plane. The ZnO/R-Al2O3 interface is atomically sharp. SAW delay lines, aligned parallel to the c-axis, were used to characterize the surface wave velocity, coupling coefficient, and temperature coefficient of frequency as functions of film thickness to wavelength ratio (h/lambda). The acoustic wave properties of the material system were calculated using Adler's matrix method, and the devices were simulated using the quasi-static approximation based on Green's function analysis.

Heparin-flush associated thrombocytopenia--induced hemorrhage: a case report.

Thrombocytopenia is a well known complication of heparin. It occurs when heparin is used in full therapeutic dose or in subcutaneous mini-doses for prophylaxis. This has also been reported with minuscule dose of heparin used in heparin-flushes to keep vascular access catheters patient. We are reporting for the first time, a case of severe hemorrhage due to thrombocytopenia associated with heparin flushes.

Blood staining of the cornea following radial keratotomy.

Although topical anesthesia is commonly used for radial keratotomy, a regional intraorbital block may offer better control of the eye in anxious or uncooperative patients. Some complications of retrobulbar injections can produce severe loss of vision. Besides perforation of the globe and optic atrophy due to nerve perineural or intraneural injection of the anesthetic, posterior orbital hemorrhages have been reported, with consequent proptosis, tightness of the eyelids, and even occlusion of the central retinal artery. We report an unusual complication: blood staining of the cornea.

[Prognostic value of postoperative determination of CEA in carcinoma of the large intestine]. / Valore prognostico del dosaggio postoperatorio del C.E.A. nel carcinoma del grosso intestino.

The C.E.A. level was routinely determined in the follow up of 133 patients who underwent surgery because of colorectal cancer. Preoperative levels of C.E.A. appear to be related to Dukes staging of the disease. Postoperative values of the marker were higher than normal in 36 patients, 91% of whom had recurrences; normal postoperative values were observed in 90 patients and only 21% of these eventually showed recurrences.