background: welding emits harmful rays to the eyes. we evaluate and compare the uv, blue light and ir transmittance characteristics of some currently available welding safety protectors with ansi z87.1 criteria. materials and methods: three type of welding safety protectors (three of each type) have been evaluated for spectral transmittance. one-sample t-test was performed to establish is there...

bioactive glasses are silicate-based and can form a strong chemical bond with the tissues. these biomaterials are highly biocompatible and can form a hydroxyapatite layer when implanted in the body or soaked in the simulated body fluid. due to several disadvantages, conventional glass processing method including melting of glass components, is replaced by sol-gel method with a large number of b...

the monolithic oxynitride glasses in sio2-al2o3-b2o3 system were synthesized using sol-gel method. the porous, dried gels were heated in flowing ammonia for different times and varying temperatures. the nitrogen content of the oxynitride glasses was determined using an oxygen-nitrogen analyzer. the chemical bonding state and properties of glasses were investigated by means of fourier transform ...

in spite of rapid advances in keratorefractive surgery in recent decades, the most common method for refractive error correction throughout the world is glasses, the discovery of which is attributed to the persians. other advantages include protection of the eye against trauma and radiations, correction of phorias and tropias and cosmetic reasons. the purpose of this article is to describe and ...

Oxynitride glasses are found as grain boundary phases in silicon nitride ceramics. They are effectively alumino-silicate glasses in which nitrogen substitutes for oxygen in the glass network, and this causes increases in glass transition and softening temperatures, viscosities (by two to three orders of magnitude), elastic moduli and microhardness. Calcium silicate-based glasses containing fluo...

The structural and optical characterization of bulk GeO2-PbO glasses was the goal of this study. In this regard, six different (100-x)GeO2‌-xPbO (15<x<45) glasses were prepared by conventional melt quenching technique between two steel sheets. The produced samples were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and UV-Vis s...

different glasses suitable for temperature sensing in the fiber optic sensors were studied in this article. the phase changes for eight different glass materials were calculated and results were compared. our results showed that extra dense flint glass is the most sensitive one, while pure silica results in the lowest phase change. in another study the effect of wavelength on the phase variatio...

Metallic glasses are kinetically metastable materials. Metallic glass is defined as “A liquid, which has been cooled into a state of rigidity without crystallizing”. Properties of metallic glasses differ form non metallic glasses. Ordinary glasses are made up of silica while metallic glasses are made of alloy metals. Ordinary glasses are transparent whereas metallic glasses are opaque. In ordin...

BACKGROUND Offering free glasses can be important to increase children's wear. We sought to assess whether "Upgrade glasses" could avoid reduced glasses sales when offering free glasses to children in China. METHODS In this cluster-randomized, controlled trial, children with uncorrected visual acuity (VA)< = 6/12 in either eye correctable to >6/12 in both eyes at 138 randomly-selected primary...