Biomedical subjects

Richard A Myers

Publications and source records attributed to Richard A Myers.

3 recordsLinked to original sources

PubMed2006

Enhancing near-infrared avalanche photodiode performance by femtosecond laser microstructuring.

A processing technique using femtosecond laser pulses to microstructure the surface of a silicon avalanche photodiode (APD) has been used to enhance its near-infrared (near-IR) response. Experiments were performed on a series of APDs and APD arrays using various structuring parameters and poststructuring annealing sequences. Following thermal annealing, we were able to fabricate APD arrays with quantum efficiencies as high as 58% at 1064 nm without degradation of their noise or gain performance. Experimental results provided evidence to suggest that the improvement in charge collection is a result of increased absorption in the near-IR.

Journal Article↗

PubMed2005

Analysis of hyaluronan content in chondroitin sulfate preparations by using selective enzymatic digestion and electrospray ionization mass spectrometry.

Two important glycosaminoglycans (GAGs) with structural roles in the body's cartilage are hyaluronan (HA) and chondroitin sulfate (CS). A simple mass spectrometric method for determining the amount of HA that may be present in isolated CS samples is presented in this article. Samples are subjected to selective enzymatic digestion using a bacterial hyaluronidase (HA lyase, EC 4.2.2, from Streptococcus dysgalactiae) specific for HA. Undigested CS GAG is then removed by centrifugal filtration, and digested HA left in the filtrate is quantified by electrospray ionization mass spectrometry using an internal standard and selected ion monitoring. The described method was applied to the analysis of several CS samples prepared for use in nutritional supplements.

Carbohydrate Sequence↗

PubMed2003

Geiger photodiode array for compact, lightweight laser-induced breakdown spectroscopy instrumentation.

The development of a unique spectrometer based on an array of Geiger photodiodes has been shown to enhance the performance of laser-induced breakdown spectroscopy (LIBS) instrumentation. These compact, silicon-based detectors eliminate the need for postamplification electronics, allow for the detection of single photons at room temperature, and do not require complex gating-timing circuitry. The detectors have dark-count rates of <500 Hz at room temperature and a good response from the UV to the near IR. Their high sensitivity makes them candidates for standoff analysis as part of a LIBS spectrum analyzer.

Journal Article↗