MATECH (United States)

It is a major misconception that freely falling reference frames are inertial in a gravitational field. This is one outcome when employing Einstein’s principle of equivalence between a dynamical acceleration and a homogeneous gravity, which does not exist technically in nature, because gravity is radial from all mass centers, even at nearly infinite distances between masses. Even though floating objects within a space station orbiting Earth appear to move with constant inertial velocities, tidal forces exist to accelerate all such objects. The four oceanic tides of Earth prove that the Moon and Sun are the two external gravitational bodies pulling on Earth, even if an earthbound observer cannot physically feel the tidal forces. Theoretical experiments demonstrate how to observe tidal effects internally to determine the external gravitational forces. Tidal forces make dumbbell-shaped artificial satellites rotate around a heavenly body once per orbit. A liquid in free fall like mercury becomes prolate in shape and aligns with the external gravitational force if the liquid’s surface tension can be minimized. Today’s technology is very precise and can detect most subtle forces, so that local experiments can distinguish between a reference frame in free fall versus a truly inertial frame placed far away from gravitational bodies. Tidal forces always exist in any neighborhood of a test mass due to the radial gravitational force from any external mass, so the mathematical limit of a shrinking local reference frame always contains tidal forces within its domain. Thus, Einstein’s equivalence principle is an approximation and is technically applicable for only point masses.

Germline mutations in the DNA mismatch repair (MMR) genes MSH2 and MLH1 are responsible for the majority of hereditary non-polyposis colorectal cancer (HNPCC), an autosomal-dominant early-onset cancer syndrome. Genetic testing of both MSH2 and MLH1 from individuals suspected of HNPCC has revealed a considerable number of missense codons, which are difficult to classify as either pathogenic mutations or silent polymorphisms. To identify novel MLH1 missense codons that impair MMR activity, a prospective genetic screen in the yeast Saccharomyces cerevisiae was developed. The screen utilized hybrid human-yeast MLH1 genes that encode proteins having regions of the yeast ATPase domain replaced by homologous regions from the human protein. These hybrid MLH1 proteins are functional in MMR in vivo in yeast. Mutagenized MLH1 fragments of the human coding region were synthesized by error-prone PCR and cloned directly in yeast by in vivo gap repair. The resulting yeast colonies, which constitute a library of hybrid MLH1 gene variants, were initially screened by semi-quantitative in vivo MMR assays. The hybrid MLH1 genes were recovered from yeast clones that exhibited a MMR defect and sequenced to identify alterations in the mutagenized region. This investigation identified 117 missense codons that conferred a 2-fold or greater decreased efficiency of MMR in subsequent quantitative MMR assays. Notably, 10 of the identified missense codons were equivalent to codon changes previously observed in the human population and implicated in HNPCC. To investigate the effect of all possible codon alterations at single residues, a comprehensive mutational analysis of human MLH1 codons 43 (lysine-43) and 44 (serine-44) was performed. Several amino acid replacements at each residue were silent, but the majority of substitutions at lysine-43 (14/19) and serine-44 (18/19) reduced the efficiency of MMR. The assembled data identifies amino acid substitutions that disrupt MLH1 structure and/or function, and should assist the interpretation of MLH1 genetic tests.

“Is it possible to incorporate a living microorganism as a second phase in a man-made, engineered material?” In this preliminary study, Saccharomyces cerevisiae has been encapsulated in a transparent matrix of porous, gel-derived silica. After gelation, aging, and prolonged storage at 5°C, S. cerevisiae bioactivity could be triggered. Bioactivity was followed by evolution of alcohol within the S. cerevisiae as a function of time during incubation by the molecular probe molecule pyranine using fluoresence spectrophotometry. Described also are some of the potential applications of this new class of biocomposite material incorporating a “living” second phase.

The photochromic organic molecule 2,3-diphenyl indenone oxide (DPIO) has been incorporated into transparent silica gel-PMMA nanocomposites. Under ultraviolet illumination, the colorless DPIO molecule transforms into 1,3-diphenyl-2-benzo-pyrillium-4- oxide (DPBO), which is deep red. Upon exposure to visible light, DPBO transforms reversibly into DPIO. Some DPBO, however, irreversibly decomposes into 3,4-diphenyl isocoumarin (DPIC) and other by-products. In this preliminary study, the rate of photochromic fatigue for a variety of samples of DPIO-doped PMMA, silica gel-PMMA nanocomposites, and ORMOSILs is presented and discussed. The prospects for DPIO-based photochromic materials exhibiting long-term stability are discussed.

The history and method of producing gel-polymer composites is presented. Tailoring properties, such as density, refractive index, hardness, elastic modulus, compressive strength, abrasion resistance, and modulus of rupture is achieved through controlling the ratio of gel-derived silica to polymer phases. Several different applications of composite technology are presented. Solid-state lasing in dye-doped silica gel-PMMA composites has been recently achieved. The difficulties in generating stable photochromism in gels and gel-derived composites are discussed. Microlens arrays for data reading, employing large gel-polymer spheres, have been developed. In addition, a new flat-screen color display technology, based upon the periodic arrangement of dye-doped microsphere pixels, emitting blue, green and red light, is disclosed for the first time.

Abstract Dye-doped porous silica microspheres can be prepared from liquid solution at temperatures near ambient. Microsphere diameter can be controlled between approximately 5.0 microns to in excess of a millimeter. The resulting microspheres can be attached to the distal end of an optical fiber in which the proximal end is attached to a spectrophotometer. Depending upon the organic species doped into the microsphere, a wide variety of sensing functions are possible. In this paper, the use of microsensors for measuring pH, temperature, and solvent content of aqueous solutions is demonstrated. Potential utility of this type of sensor to heavy metals detection and biomedical diagnostics is also discussed.

Neodymia‐doped glasses are currently commercially available for use in laser systems. Typically, these glasses are low‐softening‐temperature borates, phosphates, silicates, and fluorides. With its high softening temperature, high thermal shock resistance, and low nonlinear index of refraction, silica may be an ideal candidate for a neodymia bost glass for high‐power laser applications. Conventional glass processing methods, however, have thus far succeeded in incorporating only low levels of neodymia in silica. In this paper, the fabrication of neodymia–silica glasses with high neodymia content by the sol‐gel route is described. A possible structure for neodymia in silica is discussed.