University of Texas System

About: University of Texas System is a education organization based out in Austin, Texas, United States. It is known for research contribution in the topics: Cancer & Population. The organization has 13901 authors who have published 10925 publications receiving 319328 citations. The organization is also known as: UT System.

Purification of Rat Spermatogenic Cells and Preliminary Biochemical Analysis of These Cells

Abstract: A method forobtaininghighlypurifiedfractions of rat testicular cells is described. Single cell suspensions from adult rat testes were separated by centrifugal elutriation. Fractions enriched in pachytene primary spermatocytes, early spermatids, and cytoplasts detached from late spermatids were obtained. These fractions were further separated by equilibrium density centrifugation on gradients of Percoll. In this manner fractions of 3 X 10� pachytene spermatocytes (98% purity), 1.1 X 10� early spermatids (93% purity), and 1.1 X i05 cytoplasts (98% purity) were obtained within 6 h after sacrificing the rats. The cells appeared to be morphologically intact and to have retained their biochemical integrity. Analysis of acid-soluble nuclear proteins by polyacrylamide gel electrophoresis showed that histone 4 is synthesized during the pachytene stage, and confirmed that testis-specific histones are also synthesized during this stage. Analysis of a microsomal RNA preparation from purified pachytene spermatocytes and purified early spermatids by sucrose gradients indicated that intact ribosomal RNA (rRNA) can be obtained from purified cells. Both cell types are active in synthesizing presumptive messenger RNA (mRNA) with a wide range of sedimentation values, but no appreciable rRNA synthesis was detected.

High precision orientation alignment and gap control stages for imprint lithography processes

Abstract: Processes and associated devices for high precision positioning of a template and substrate during imprint lithography includes a calibration system with a course calibration stage and a fine orientation stage capable of maintaining a uniform gap between the template and substrate. The fine orientation stage includes a pair of flexure members having flexure joints for motion about a pivot point intersected by first and second orientation axes. Actuators lengthen or shorten to expand or contract the flexure members. Separation of the template is achieved using a peel-and-pull method that avoids destruction of imprinted features from the substrate.

PspC, a pneumococcal surface protein, binds human factor H.

Abstract: PspC was found to bind human complement factor H (FH) by Western blot analysis of D39 (pspC+) and an isogenic mutant TRE108 (pspC). We confirmed that PspA does not bind FH, while purified PspC binds FH very strongly. The binding of FH to exponentially growing pneumococci varied among different isolates when analyzed by fluorescence activated cell sorting analysis.

Method of producing parts by selective beam interaction of powder with gas phase reactant

Abstract: A method and apparatus for selectively sintering a layer of powder to produce a part comprising a plurality of sintered layers. The apparatus includes a computer controlling a laser to direct the laser energy onto each layer of the powder to produce a sintered mass corresponding to a cross-section of the part. For each cross-section, the aim of the laser beam is scanned over a layer of powder and the beam is switched on to sinter only the powder within the boundaries of the cross-section. Powder is applied and successive layers sintered until a completed part is formed. Also disclosed is a method of forming a part by interaction of material in the powder layer with reactants in the surrounding atmosphere, at locations of the powder irradiated by the energy, or laser, beam. The reaction may be nitridation, oxidation or carburization of the powder, with the product being a chemical compound of one or more constituents in the powder with one or more gases in the atmosphere. Alternatively, reduction of the powder may be so enabled by the energy beam so that a metallic phase product is formed at the irradiated locations. Particular benefits of the invention include the densification of the material of the part as a result of the reaction, and the ability to form high temperature materials by way of a relatively low temperature process.