Thermographic Imaging for High-Temperature Composite Materials—A Defect Detection Study

The ability of a thermographic imaging technique for detecting flat-bottom hole defects of various diameters and depths was evaluated in four composite systems (two types of ceramic-matrix composites, one metal-matrix composite, and one polymer-matrix composite) of interest as high-temperature structural materials. The holes ranged from 1 to 13 mm in diameter and 0.1 to 2.5 mm in depth in samples approximately 2—3 mm thick. The thermographic imaging system utilized a scanning mirror optical system and infrared (IR) focusing lens in conjunction with a mercury—cadmium—telluride infrared detector element to obtain high-resolution infrared images. High-intensity flash lamps located on the same side as the infrared camera were used to heat the samples. After heating, up to 30 images were sequentially acquired at 70—150 ms intervals. Limits of detectability based on depth and diameter of the flat-botton holes were defined for each composite material. Ultrasonic and radiographic images of the samples were obtained and compared with the thermographic images. This study was done under a nonreimbursable Space Act Agreement between NASA—Lewis Research Center and Bales Scientific, Inc., to allow several heating configurations to be evaluated in a cost-effective and timely fashion.     

1H-MRS of femoral red and yellow bone marrow fat composition and water content in healthy young men and women at 3 T

Magnetic Resonance Materials in Physics, Biology and Medicine - There is a discrepancy between studies suggesting that higher bone marrow fat saturation is associated with impaired health, and...     

The Role of L-Arginine-NO System in Female Reproduction: A Narrative Review

Accumulating evidence are available on the involvement of l-arginine-nitric oxide (NO) system in complex biological processes and numerous clinical conditions. Particular attention was made to reveal the association of l-arginine and methylarginines to outcome measures of women undergoing in vitro fertilization (IVF). This review attempts to summarize the expression and function of the essential elements of this system with particular reference to the different stages of female reproduction. A literature search was performed on the PubMed and Google Scholar systems. Publications were selected for evaluation according to the results presented in the Abstract. The regulatory role of NO during the period of folliculogenesis, oocyte maturation, fertilization, embryogenesis, implantation, placentation, pregnancy, and delivery was surveyed. The major aspects of cellular l-arginine uptake via cationic amino acid transporters (CATs), arginine catabolism by nitric oxide synthases (NOSs) to NO and l-citrulline and by arginase to ornithine, and polyamines are presented. The importance of NOS inhibition by methylated arginines and the redox-sensitive elements of the process of NO generation are also shown. The l-arginine-NO system plays a crucial role in all stages of female reproduction. Insufficiently low or excessively high rates of NO generation may have adverse influences on IVF outcome.