Alginate assessment by NMR microscopy

Alginate hydrogels have long been used to encapsulate cells for the purpose of cell transplantation. However, they also have been criticized because they fail to consistently maintain their integrity for extended periods of time. Two issues of critical importance that have yet to be thoroughly addressed concerning the long-term integrity of alginate/poly-L-lysine/alginate microcapsules are: (i) are there temporal changes in the alginate/poly-L-lysine interaction and (ii) are there temporal changes in the alginate gel structure. NMR microscopy is a non-invasive analytical technique that can address these issues. in this report, we present data to demonstrate the utility of ¹H NMR microscopy to (i) visualize the poly-L-lysine layer in an effort to address the first question, and (ii) to observe temporal changes in the alginate matrix that may represent changes in the gel structure.     

Holographic correction and phasing of large sparse-array telescopes

I have constructed a 1-m-diameter telescope using separate, low-quality spherical primary mirror segments. A single hologram of the mirrors is used to correct the random surface distortions as well as spherical aberration, while simultaneously phasing the individual apertures together. I present experimental results of the removal of an error of thousands of waves to produce a diffraction-limited instrument operating over a narrow bandwidth. This technique promises to have many benefits in future space-based telescopes for imaging, lidar, and optical communications.     

Effect of Hard Limiting on a Quadrature PSK Signal

The effect of a hard limiter on a quadrature PSK (QPSK) signal is determined for a sample detector and an integrate and dump detector. In the latter case theBTproduct is assumed to be infinite. The degradation due to hard limiting is approximately 1 dB.     

Evidence of two β’ phases in tristearin

Data from Raman spectroscopy, X-ray diffraction analysis, differential scanning calorimetry and features of the preparative method are all consistent with the existence of 2 intermediate β’ phases for tristearin; the first, a lower melting phase, β’₂, transforms at 61 C into the second, β’₁ , which in turn changes at 64 C into β-tristearin. Raman spectral evidence indicates that the 2 mesophases occur in an orthorhombic packing environment and that the β’₂ to β’₁ transition results from a change in lateral packing of the hydrocarbon chains.     

Scan Converting Extruded Lines at Ultra High Definition

We consider the problem of generating freehand raster graphics pictures at ultra high definition (typically one gigapixel per picture) by scan converting extruded lines. We describe a fast scan conversion algorithm which is linear in final resolution and which incorporates a number of features to ensure high efficiency. Sample pictures and corresponding performance figures are included.