Silicon oxide films grown in microwave discharge

Silicon oxide films thicker than 1000 angstrom are produced in the dense plasma of a microwave discharge. The oxide growth is characterized by a rate limiting diffusion process modified by sputtering effects produced by the discharge. Silicon is rapidly oxidized at temperatures estimated to be 500 degrees C or lower

Silicon oxide films grown and deposited in a microwave discharge

Growth and deposition of silicon dioxide films in microwave discharg

Environmental effects on the tensile strength of chemically vapor deposited silicon carbide fibers

The room temperature and elevated temperature tensile strengths of commercially available chemically vapor-deposited (CVD) silicon carbide fibers were measured after 15 min heat treatment to 1600 C in various environments. These environments included oxygen, air, argon and nitrogen at one atmosphere and vacuum at 10/9 atmosphere. Two types of fibers were examined which differed in the SiC content of their carbon-rich coatings. Threshold temperature for fiber strength degradation was observed to be dependent on the as-received fiber-flaw structure, on the environment and on the coating. Fractographic analyses and flexural strength measurements indicate that tensile strength losses were caused by surface degradation. Oxidation of the surface coating is suggested as one possible degradation mechanism. The SiC fibers containing the higher percentage of SiC near the surface of the carbon-rich coating show better strength retention and higher elevated temperature strength

In vivo magnetic resonance imaging of mesenchymal stem cells in myocardial infarction

Background - We investigated the potential of magnetic resonance imaging (MRI) to track magnetically labeled mesenchymal stem cells (MR-MSCs) in a swine myocardial infarction (MI) model. Methods and Results - Adult farm pigs (n=5) were subjected to closed-chest experimental MI. MR-MSCs (2.8 to 16×107 cells) were injected intramyocardially under x-ray fluoroscopy. MRIs were obtained on a 1.5T MR scanner to demonstrate the location of the MR-MSCs and were correlated with histology. Contrast-enhanced MRI demonstrated successful injection in the infarct and serial MSC tracking was demonstrated in two animals. Conclusion - MRI tracking of MSCs is feasible and represents a preferred method for studying the engraftment of MSCs in MI

Are trials of intravascular infusions of autologous mesenchymal stem cells in patients with multiple system atrophy currently justified, and are they effective?

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92397/1/23655_ftp.pd

Myocardial first-pass perfusion cardiovascular magnetic resonance: history, theory, and current state of the art

In less than two decades, first-pass perfusion cardiovascular magnetic resonance (CMR) has undergone a wide range of changes with the development and availability of improved hardware, software, and contrast agents, in concert with a better understanding of the mechanisms of contrast enhancement. The following review provides a perspective of the historical development of first-pass CMR, the developments in pulse sequence design and contrast agents, the relevant animal models used in early preclinical studies, the mechanism of artifacts, the differences between 1.5T and 3T scanning, and the relevant clinical applications and protocols. This comprehensive overview includes a summary of the past clinical performance of first-pass perfusion CMR and current clinical applications using state-of-the-art methodologies

Intravascular MR-monitored balloon angioplasty: An in vivo feasibility study

PURPOSE: To develop a new method for monitoring balloon angioplasty by using an intravascular magnetic resonance (MR) imaging technique. MATERIALS AND METHODS: Nine New Zealand White rabbits were used: seven for technique refinement, including surgery, device insertion, stenosis creation, and MR protocol development; and two for the final MR imaging of the balloon angioplasty. The in vivo experimental method involved insertion of a catheter antenna and a balloon catheter, via femoral arteriotomies bilaterally, into the target site of the upper abdominal aorta, where a stenosis was artificially created by binding a plastic cable tie. Then, the entire process of the dilation of the stenosis with balloon inflation was monitored under MR fluoroscopy. RESULTS: Catheter insertions were successful, and a 5-mm-long stenosis of the aorta was produced in all nine rabbits. Eight complete balloon angioplasty procedures were satisfactorily monitored and recorded, showing clearly the stenosis of the aorta at the beginning of the procedure, the dilation of the stenosis during the balloon inflation, and the complete opening of the stenosis after balloon dilation. CONCLUSION: Preliminary results of in vivo balloon angioplasty monitored with intravascular MR imaging are presented. MR fluoroscopy, based on the intravascular MR imaging technique, may represent a potential alternative to x-ray fluoroscopy for guiding interventional treatment of cardiovascular diseases