William M. Rosenblum

Recent results and new hardware developments for protein crystal growth in microgravity

Abstract Protein crystal growth experiments have been performed on 16 space shuttle missions since April 1985. The initial experiments used vapor diffusion crystallization techniques similar to those used in laboratories for earth-based experiments. More recent experiments have assessed temperature-induced crystallization as an alternative method for growing high quality protein crystals in microgravity. Results from both vapor-diffusion and temperature-induced crystallization experiments indicate that protein crystals grown in microgravity may be larger, display more uniform morphologies, and yield diffraction data to significantly higher resolutions than the best crystals of these proteins grown on earth.

Optical matrix method: optometeric applications:.

&NA; A unique and advantageous method for determining the paraxial properties of an optical system is described. Using matrix algebra, any optical array can be fully described by a series of 2 × 2 matrices. Several sample systems of optometric interest, lenses and the schematic eye, are analyzed by means of this technique.

A light scattering method for qualitatively monitoring aggregation rates in macromolecular systems

Abstract This paper suggests an alternative light scattering procedure for qualitative assessment of aggregation rates in aggregating macromolecular systems. The procedure is based on the light scattering behavior of particles as their size becomes comparable to the wavelength of the incident light. The experimental results discussed demonstrate that this procedure is feasible for macromolecular systems whose constituents begin aggregation with a maximum size in the Rayleigh regime.

Protein crystal growth results from the United States Microgravity Laboratory-1 mission

Protein crystal growth experiments have been performed on fourteen space shuttle missions between April 1985 and June 1992. These space shuttle missions have been used to grow crystals of a variety of proteins using vapour diffusion, liquid diffusion, and temperature induced crystallization techniques. The United States Microgravity Laboratory-1 mission (june 25-July 9, 1992) was a space lab mission dedicated to experiments involved in materials processing. New protein crystal growth hardware was developed to allow in-orbit examination of initial crystal growth results, the knowledge from which was used on subsequent days to prepare new crystal growth experiments. The hardware developed specifically for the USML-1 mission is discussed along with preliminary experimental results.

Examination of protein crystals in the hanging drop using digital image capture techniques

Abstract One of the current methods of producing protein crystals in a microgravity environment is to grow them in a hanging droplet suspended from a two barrel syringe. A large number of these hanging drop experiments have been with mixed success since there has been no way to constantly monitor growth rate or events that could perturb the growth of the crystals. In our research we have been using image capture techniques using a monochrome CCD and a microscope objective lens to record images of the crystals within the hanging drop. Using a two barrel syringe, we extrude a solution of lysozyme and salt so that a drop is produced at the tip of the syringe. As the crystals begin to grow, we record the images of the backlit drop with an Imaging Technology frame grabber connected to an IBM PC XT. Sequential pictures are stored for further analysis. From the stored pictures we can measure crystal sizes, their distribution in the droplet and any movements which occur, as well as relative size changes from which we can calculate rates of growth or changes in morphology. This system is a prototype for a flyable unit which will be enclosed in an hermetically sealed box containing six droplets and six cameras. Each cell will be monitored by a small CCD microscope and the images will be recorded on the video tape unit in the Space Shuttle. It will also be possible for the principal investigator to view the activity within each drop in real-time.

Temperature-induced conformational transitions for flexible synthetic polymers in solution

Abstract Herein we report experimental results on a wide variety of common, linear flexible polymers in solution in an attempt to confirm prior reports of abrupt ‘conformational transitions’ for these materials. Such transitions have been claimed by numerous authors, and they have been reported to reflect sudden conformational changes brought about, in most cases, by varying temperature. Methods used both in our work and earlier work include viscometry, differential refractometry and size exclusion chromatography. We observed no evidence of such conformational transitions and conclude that in reality such events are probably rare. We believe that many prior reports of such sudden changes in shape/size are probably mistaken because of the failure of some authors to take into account realistic experimental errors during data analysis and interpretation.

The subjective quality (SQF) of Bausch and Lomb SoflensTM.

&NA; The visual acuity of a person is examined in terms of his response to a unique target. This target is a sequence of black bars on a white background, where the spacing of the bars and their width is governed by a log periodic function. The generation of these targets is performed by a PDP‐8 computer connected to an X‐Y plotter. There are six sets of bars which vary in contrast and frequency. In a clinical situation, an observer notates the position where he can no longer resolve the bar pattern. A recording of these positions produces a Subjective Quality Function (SQF) curve for the individual. On fitting with soft contact lenses, a new SQF curve is generated. A comparison of the SQF for soft lenses with that for spectacle corrections is given.

Computerized analysis of the image quality of the human eye with optical aids.

Spot diagrams are computer generated by skew ray tracing for a model of the human eye which is corrected by means of a contact lens and spectacle lens. An examination of the images of a point source of light at 0 degrees and 20 degrees off the optical axis of the eye-lens system are shown. For the correction of aphakia, the performance of the contact lens is shown to be superior in off-axis optical performance.

Caustic and Analytical Illuminance Calculations for a Model of the Human Eye

The analytical flux monitoring technique has been used to evaluate the caustic surface and line spread function (energy flux distribution along a line) on different image planes for point source light passing through a model of the human eye. It is shown by comparison with the standard spot diagrams that the caustic is a valuable tool in evaluating the aberra-tions and performance of the model of the human eye.