Glasses Tech – Prescription Glasses, Prescription Eyeglasses

September 22, 2009

Fitting children with glasses.

Filed under: Glasses 1995 — admin @ 6:33 am

Eyeglasses

1. When fitting children for glasses, the emphasis must always be on ensuring that the glasses not only correct the visual problems but also feel and look good. Otherwise, they will not be worn. 2. There is a great value in creating an atmosphere in an optical shop that makes children want to visit. The process of visiting and selecting glasses should be fun for a child. Children’s theme sections or toys are an effective method of making a visit pleasurable for a child. 3. For all the extra features an optical shop may offer, perhaps the most special are the intangibles of patience, respect, and genuine affection.

Rooney J

Optical and optoelectronic glasses by sol-gel

Filed under: Glasses 1995 — admin @ 6:33 am

Application of the sol-gel method to the fabrication of opticallyhigh-performance bulk glasses has been tried by many researchers in the world. Although to date ithas not been as successful as was expected at the beginning, there exist various high-performanceglasses which will be prepared more advantageously by the sol-gel method than with conventionalglass fabrication process. These are all promising materials and will appear in optical andoptoelectronic devices in the near future.

Sports glasses and ultraviolet protection

Filed under: Glasses 1995 — admin @ 6:32 am

Nineteen current makes of sports glasses and six older types of sunglasses were tested for spectral UV transmission. Transmissions in the UVB range (280–320 nm) were less than 10^-4; all glasses therefore offered 100% protection against keratitis. Transmissions of UVA radiation (320–400 nm) varied greatly. All makes transmitted varying small amounts of cataract effective UVA radiation, but the effectiveness for cataract is less than 0.15% in the UVA range. If lateral incident radiation is shielded, sports glasses protect against ocular damage from solar UV radiation even in a very bright environment.

WALTER AMBACH, MARIO BLUMTHALER, and JULIAN GROBNER

Exact Dynamical Relations of Ising Spin Glasses

Filed under: Glasses 1995 — admin @ 6:31 am

We investigate dynamical systems of gauge symmetric Ising spin glasses usingthe method of the gauge transformation. Several exact relations are derived among dynamicalquantities such as the equilibrium auto-correlation function and the non-equilibrium remanentmagnetization. The same result as in the static case is obtained in terms of the equivalence of theferromagnetic and the spin glass order if the temperature and the randomness satisfy a specialcondition (Nishimori line). An exact equivalence of non-equilibrium relaxations in the spin glassphase is derived between the remanent magnetization evolved from the strong field limit and theauto-correlation function from a supercooled state. We also have a plausible argument for theabsence of re-entrant transition.

Y. OZEKI

Structure of sodium tellurite glasses. Sodium cation environments from sodium-23 NMR

Filed under: Glasses 1995 — admin @ 6:31 am

In order to study the way in which the modifying sodium cations interact with the network in (Na//2O)//x(Teo//2)//1// minus //x glasses, we have probed the sodium sites using the dynamic angle spinning NMR experiment. By performing this experiment at two different magnetic field strengths, we extract the chemical shift and quadrupole coupling parameters, which we relate to the glass structure with the aid of an empirical model. Our results suggest that the sodium coordination changes from about six, at low modifier concentrations, to about five, at high concentrations. This decrease is not monotonic, however; it is relatively independent of concentration from 10 to about 18 mol %, at which point it begins to decrease. We interpret this change as due to the onset of formation of significant numbers of nonbridging oxygen. (Author abstract) 29 Refs.

Tagg, S.L. Youngman, R.E. Zwanziger, J.W.

Electrical conduction of glasses in the system

Filed under: Glasses 1995 — admin @ 6:30 am

Fe//2O//3-Sb//2O//3-TeO//2 glasses were prepared by the press-quenching method and their dc conductivities were measured. The glass formation region was found to be 0 less than equivalent to Fe//2O//3 less than equivalent to 15mol%, 0 less than equivalent to Sb//2O//3 less than equivalent to 18mol%, and 78 less than equivalent to TeO//2 less than 100mol%. Seebeck coefficient measurements showed that these glasses were n-type semiconductors. The glasses gave conductivities sigma ranging from 1.62 multiplied by 10** minus **6 to 1.86 10** minus **7S center dot cm** minus **1 at 473K. The dc conductivity increased with an increase in Fe//2O//3 content. Evaluated carrier mobility and concentration ranged from 7.5 multiplied by 10** minus **1**0 to 5.3 multiplied by 10** minus **3cm**2 center dot V** minus **1 center dot s** minus **1 and from 1.5 multiplied by 10**2**1 to 1.9 multiplied by 10**1**5cm** minus **3 at 473K, respectively. The conduction of these glasses was due to non-adiabatic small polaron hopping. (Author abstract) 34 Refs.

Qiu, Hong-Hua Mori, Hidetsugu Sakata, Hironobu Hirayama, Toru

Upconversion fluorescence of tellurite glasses doped with rare earths

Filed under: Glasses 1995 — admin @ 6:18 am

Ternary tellurite glasses were prepared by a conventional quenching method in the system TeO//2-LiO//0//.//5-YO//1//.//5. IR spectra reveal that the glasses contain the following polyhedra: deformed TeO//6 groups, TeO//4-trigonal bipyramids, TeO//3-trigonal pyramids, or combinations of these polyhedra. The highly addition of glass-network modifiers, especially Li** plus ion, leads to a collapse of polyhedra networks. The intense emission peak, due to the transition**4S//3/////2- **4I//1//5/////2, was found at 546 nm in tellurite glasses doped with Er**3** plus under 378 nm and 973 nm excitations at the room temperature. Upon excitation at 973 nm, the emission shows a typical upconversion characteristic, indicating the quadratic profiles of the emission intensities against the exciting powders. The emission intensities tend to be dependent upon 378 nm excitation, but independent of Er**3** plus concentration upon 973 nm excitation. The excitation and emission involve two photons process through the**4I//1//1/////2 level of Er**3** plus ion. Upconversion fluorescence is, also, enhanced at 547 nm by the supplementary doping with Yb**3** plus ion. (Author abstract) 9 Refs.

Endo, Tadashi Tanaka, Kuniharu Takizawa, Hirotsugu Shimada, Masahiko

in candidate glasses for nuclear waste immobilisation. Part 2. A summary for binary alkali silicates and borates

Filed under: Glasses 1995 — admin @ 6:17 am

A thermogravimetric technique was employed to measure CO//2 solubilities in binary R//2O plus SiO//2 and R//2O plus B//2O//3 melts (R equals Li, Na, K, Rb, Cs). CO//2 solubilities can be interpreted by taking account of the free energy changes for the reaction, R//2O plus CO//2 equals R//2CO//3 and the activity coefficients of R//2O and R//2CO//3 in R//2O plus R//2CO//3 plus SiO//2 and R//2O plus R//2CO//3 plus B//2O//3 pseudo ternary systems. (Author abstract) 9 Refs.

Haba, K. Watanabe, H. Iwase, M. Oh-uchi, H. Kawamura, K.

Nitrogen dissolution in phosphate glasses containing

Filed under: Glasses 1995 — admin @ 6:16 am

Phosphorus oxynitride glasses containing M//2O, MO and M//2O//3 were prepared by melting in dry ammonia. The glass composition and the water content in the furnace atmosphere were factors controlling the maximum nitrogen dissolution in a phosphate glass. For the same cation concentration in a phosphate glass, the amount of nitrogen that could be dissolved decreased with increasing cation valence. Other properties evaluated included the thermal expansion coefficient and the dissolution rate in water. (Author abstract) 22 Refs.

Peng, Y.B. Lei, X. Day, D.E.

Laboratory experiments on the Ne enrichments in terrestrial natural glasses

Filed under: Glasses 1995 — admin @ 6:15 am

In order to study Ne diffusion into glasses, we measured noble gas concentrations in obsidian samples which were degassed in a vacuum at 800°C and subsequently heated in air at various temperatures and heating times. Neon was concentrated in samples which were kept at room temperature, indicating that Ne is easily diffused into obsidians from the atmosphere even at room temperature. We also measured noble gas concentrations in five size-separated fractions of the obsidian (ME1) (>250, 149-250, 74-149, 46-74 and <46 μm fractions) and in three size-separated fractions of tektite (TE6) (>250 and 149-250 μm fractions and powdered fraction) to examine the degassing effect on noble gases by crushing. The Ar and Kr concentrations, and especially the Ne concentration, show a gradual decrease with decreasing grain size of the obsidian samples. For the tektite samples, Ne concentration in the powdered fraction was about half of that in the >250 and 149-250 μm fractions. These results confirm that Ne in glasses mainly resides in vesicles in the glass.

Kayo Matsubara and Jun-ichi Matsuda

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Glasses Tech – Prescription Glasses, Prescription Eyeglasses