Glasses Tech – Prescription Glasses, Prescription Eyeglasses

March 8, 2010

Looking Through the Glasses: J. D. Salinger’s Wise Children and Gifted Education

Filed under: Glasses 2002 — admin @ 5:18 am

Eyeglasses

Gifted children are often Big Picture thinkers (Schultz & Delisle, 1997). Even as young children, they may ask profound questions and view life from the perspective of The Most Important Things: meaning, goodness, truth, spirituality, death, and the like. J. D. Salinger’s stories about the gifted and precocious Glass children offer a vivid, provocative, and very useful description of a spiritual Big Picture perspective on life. (more…)

Development of a Novel Composite Based on Thermoplastic Polymers and Low Melting Point Thermoplastic Chalcogenide Glasses

Filed under: Glasses 2002 — admin @ 5:09 am

A novel composite material has been developed based on thermoplastic polymers on one hand and thermoplastic chalcogenide glass on the other hand. Extrusion technique and pressing allowed the production of very different structures of the composite, ranging from fibrous to “sandwich” structures. Also obtained were highly homogenous compositions that contain perfectly spherical glass particles of 1-6 mm in diameter dispersed into a polymer matrix. (more…)

Progression of Childhood Myopia in Soft Contact Lenses and Glasses

Filed under: Glasses 2002 — admin @ 5:08 am

Purpose: to examine the effect of correction type on myopia progression in subjects who completed a randomized clinical trial of bifocal glasses.
Methods: Forty nine of 55 subjects, who completed a 42-month clinical trial, returned for a 1-yr post-treatment visit (54 months of follow-up). Original treatment assignments were single-vision glasses (SV) or bifocal glasses (BF) with a +1.50 D add. Once released from treatment, children chose either to wear soft contact lenses (CL), to continue in their assigned glasses, or to switch to the other type of glasses. Progression during that year, i.e. from 42 to 54 mos., was used to estimate the effect of switching correction type. Myopia was measured with automated refraction 30 min after instilling two drops of 1% tropicamide. We used ANOVA with age as co-variate and averaged myopia over both eyes. Means presented here are age-adjusted. (more…)

Mantle-melt Evolution (Dynamic Source) in the Origin of a Single MORB Suite: a Perspective from Magnesian Glasses of Macquarie Island

Filed under: Glasses 2002 — admin @ 4:41 am

The effects of source composition and source evolution during progressive partial melting on the chemistry of mantle-derived mid-ocean ridge basalt (MORB) melts were tested using a comprehensive geochemical and Sr–Nd–Pb isotopic dataset for fresh, magnesian basaltic glasses from the Miocene Macquarie Island ophiolite, SW Pacific. These glasses: (1) exhibit clear parent–daughter relationships; (2) allow simple reconstruction of primary melt compositions; (3) show exceptional compositional diversity (e.g. K2O/TiO2 0·09–0·9; La/Yb 1·5–22; 206Pb/204Pb 18·70–19·52); (4) preserve changes in major element and isotope compositions, which are correlated with the degree of trace element enrichment (e.g. La/Sm). (more…)

“Drink at least eight glasses of water a day.” Really? Is there scientific evidence for “8 × 8″?

Filed under: Glasses 2002 — admin @ 4:39 am

Despite the seemingly ubiquitous admonition to “drink at least eight 8-oz glasses of water a day” (with an accompanying reminder that beverages containing caffeine and alcohol do not count), rigorous proof for this counsel appears to be lacking. This review sought to find the origin of this advice (called “8 × 8″ for short) and to examine the scientific evidence, if any, that might support it. The search included not only electronic modes but also a cursory examination of the older literature that is not covered in electronic databases and, most importantly and fruitfully, extensive consultation with several nutritionists who specialize in the field of thirst and drinking fluids. (more…)

Si-F bonding in aluminosilicate glasses: Inferences from ab initio NMR calculations

Filed under: Glasses 2002 — admin @ 4:37 am

Although it has been well accepted that F-Al linkages dominate in F-bearing alkali aluminosilicate glasses, the possibility of F-Si linkages remains unresolved. Recent 19F NMR results have been interpreted as indicative of not only the presence of the Al-F-Na(n) linkages but also of the presence of Si-F-Na(n) linkages. High level ab initio NMR calculations were performed to investigate the nature of possible species contributing to the 19F spectra. (more…)

Molecular orbital calculations on aluminosilicate tricluster molecules: Implications for the structure of aluminosilicate glasses

Filed under: Glasses 2002 — admin @ 4:32 am

Ab initio, molecular orbital calculations were carried out to study the energetic stability and NMR characteristics of “triclusters” of composition [T(XO)(OH)2]O[Al(OH)3][T(OH)3] (X = no atom, H+, Li+, Na+, K+, Mg2+, or Ca2+; T = Si4+ or Al3+). These triclusters consist of a central oxygen atom in trigonal coordination (IIIO) surrounded by three tetrahedrally coordinated, network-forming cations (Al and Si). All tricluster configurations modeled are predicted to be dynamically stable except for one containing three Al3+ cations. Tricluster viability was further tested by computing energetic stabilities relative to Al(OH)3 and dimers with non-bridging oxygen atoms (NBO). With these species as reactants and T = Si4+, calculated reaction energies vary from –87 kJ/mol with X = H+, to –253 kJ/mol with X = Mg2+. For the case of X = Ca2+, where structures with 1 Si and 2 Al were also modeled, the reaction energy was found to be over 50 kJ/mol more negative in the latter case (–278 kJ/mol compared to –222 kJ/mol). (more…)

Volatiles in basaltic glasses from a subglacial volcano in northern British Columbia (Canada): implications for ice sheet thickness and mantle volatiles

Filed under: Glasses 2002 — admin @ 4:31 am

Dissolved H2O, CO2, S and Cl concentrations were measured in glasses from Tanzilla Mountain, a 500 m-high, exposed subglacial volcano from the Tuya-Teslin region, north central British Columbia, Canada. The absence of a flat-topped subaerial lava cap and the dominance of pillows and pillow breccias imply that the Tanzilla Mountain volcanic edifice did not reach a subaerial eruptive phase. Lavas are dominantly tholeiitic basalt with minor amounts of alkalic basalt erupted at the summit and near the base. Tholeiites have roughly constant H2O (c.0.56 ± 0.07 wt%), CO2 (<30 ppm), S (980 ± 30 ppm) and Cl (200 ± 20 ppm) concentrations. Alkalic basalts have higher and more variable volatile concentrations that decrease with increasing elevation (0.62–0.92 wt% H2O, <30 ppm CO2, 870–1110 ppm S and 280–410 ppm Cl) consistent with eruptive degassing. Calculated vapour saturation pressures for the alkalic basalts are 36 to 81 bars corresponding to ice thicknesses of 400 to 900 m. (more…)

Chloride ion sites in silicate and aluminosilicate glasses: A preliminary study by 35Cl solid-state NMR

Filed under: Glasses 2002 — admin @ 4:30 am

Despite the importance of the chloride ion in magmas and the fluids that separate from them, very little is known about atomic-scale structural environments for Cl– in silicate glasses. We present here the first solid-state 35Cl NMR data for Cl in silicate and aluminosilicate glasses, made possible by the availability of very high (14.1 to 18.8 Tesla) magnetic fields. (more…)

Determination of molar absorptivities for infrared absorption bands of H2O in andesitic glasses

Filed under: Glasses 2002 — admin @ 4:29 am

We have determined infrared molar absorptivities for water absorption bands in Fe-bearing and Fe-free andesitic glasses. Water dissolves in andesitic glasses as both hydroxyl groups and molecular water as observed in other silicate glasses. Concentrations of molecular water and hydroxyl species are a strong function of total water content. IR molar absorptivities for Fe-bearing andesite are 3570 = 62.32 ± 0.42 L/mol·cm, 4500 = 0.79 ± 0.07 L/mol·cm, (more…)

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Glasses Tech – Prescription Glasses, Prescription Eyeglasses