Glass Loss Research Articles

Bioactive Vitamin C Content from Natural Selected Fruit Juices

The content of vitamin C in fruit juices can be lowered by alterations in storage and temperature. This study compared storage circumstances (temperature, duration, and packaging type) to determine which variable had the biggest influence on changes in the vitamin C content of juices (grapefruit, mandarin, peach, apple, pear, plum). Fruit juices held in glass (plastic) containers at 4 °C saw vitamin C losses in the range of 0.0–10.9% (2.4–17.4%) in 24 h, 1.4–22.6% (5.2–25.3%) in 48 h, and 2.8–37.0% (6.0–39.0%) in three days. By raising the storage temperature to 23 °C, vitamin C losses in glass (plastic) containers were found to be 1.4–19.1% (5.2–22.2%), 2.8–20.9% (5.9–25.9%), and 4.5–43.5% (6.0–38.7%) of the value after 24 h, 48 h, and three days, respectively. When decreasing the temperature to −18 °C in fruit juices stored in glass (plastic) containers, there were losses of vitamin C in 24 h in the range of 1.5–19.6% (3.0–20.0%), in 48 h, 4.5–26.1% (4.5–26.1%), and in three days, 6.0–43.1% (5.8–43.5%) of the value. The effect of temperature on vitamin C concentration has been proven. Fruit juice’s vitamin C is more stable when kept in glass containers as opposed to plastic ones, which have a limited shelf life.

Investigation of phase separation as a source of optical losses in IR glasses for fiber optics

Extremely tough requirements for the optical transparency of IR glasses for fiber optics determine the specifics of the study of phase separation in such materials. Theoretical approaches and experimental techniques of such research are proposed. The permissible contents of phase inclusions in IR glasses for active and passive fiber optics are estimated. The priority field of their control is identified and highly sensitive methods for its implementation are selected. Their effectiveness in choosing the most resistant to crystallization and liquation glasses for fiber optics is demonstrated by the example of GeSx (1.3 ≤ x ≤ 1.5) glasses. The selection criterion is the scattering losses caused by phase separation. For the first time, micro-liquation has been revealed in the studied compositions. Based on data on the sizes, contents, and refractive indices of phase inclusions, scattering losses in glasses obtained under various quenching conditions are estimated. The most promising glass compositions for fiber applications are established.

Influence of collection and storage materials on glycol ether concentrations in urine and blood

Glycol ethers, such as propylene glycol monomethyl ether (PGME) and propylene glycol monobuthyl ether (PGBE) are solvents found in many professional and domestic products. In biomonitoring studies, the type of materials used to collect, store, and transport these samples can greatly influence the analytical results because materials can adsorb the analyte. Plastic tubes generally have a hydrophobic internal surface that can reduce the concentration of certain chemicals and result in an underestimation of workers' exposures. The aim of this study was to assess whether the storage of PGME and PGBE spiked blood and urine samples led to different PGME and PGBE concentrations in vials made of glass and common plastics (polypropylene (PP), polyethylene (PE) or polystyrene (PS)). Glycol ether concentrations were quantified with headspace gas chromatography equipped with a flame ionization detector. Our results show stable urinary PGME and PGBE concentrations in PP, while up to 15% variations in urinary PGME for PE and PS. For PGME and PGBE in blood, we observed no statistically significant losses in glass, while losses were recorded for all types of plastic tested (PS, PP and PE). We conclude that biomonitoring samples should be collected in glass for blood and PP for urine.

The problems of optical loss reduction in arsenic sulfide glass IR fibers

The actively developed direction at the present time is the production of chalcogenide glasses with a low content of impurities and the manufacture of optical fibers with low optical losses on their basis. The transparency of glasses, characterized in optical fibers by the level of optical losses, refers to the key parameters of optical fibers and determines the attenuation of the signal passing through the fiber. The lowest optical losses that were achieved in multimode fibers from sulfide, selenide, and arsenic sulfoselenide glasses are 12–14; 60 and 67 dB/km, respectively. Real level of optical losses in chalcogenide glass fibers are two or more orders higher than theoretically predicted. The magnitude of this discrepancy contains the constituent parts associated with the nature and properties of glass, with the conditions for the manufacture of glass and optical fibers as well as with the methodology for the theoretical evaluation of the magnitude of intrinsic optical losses in glass. In this paper the structure, the main sources of excessive losses, the ways of approximation of real and theoretically predicted losses are considered on the example of optical fibers produced from arsenic-based chalcogenide glasses.

Optical properties of the zinc-tellurite glasses doped with Cr3+ ions

The zinc-tellurite glasses doped with Cr3+ ion have been synthesized using orthotelluric acid, zinc nitrate, and ammonium dichromate as raw materials. According to the yielded results, Cr3+ ions in the spectral range from 0.3 to 2.8 µm demonstrate two intense broad bands with maxima 454 and 650 nm, corresponding to the transitions 4A2g(F) → 4T1g(F) and 4A2g(F) → 4T2g(F). For the studied wavelength range the spectral dependence of the specific coefficient of Cr3+ allows establishing the minimum chromium content for achieving the determined level of optical losses in glasses. The electron paramagnetic resonance spectra of the doped glasses demonstrate that ions Cr3+ are presented both in the isolated ions and in Cr3+−Cr3+ paired in the distorted octahedral site. The optical band gap, Urbach energies, the crystal field and Racah parameters of the prepared glasses have been evaluated.

Excess wing physics and nearly constant loss in glasses

Excess wings and nearly constant loss are almost universal nonequilibrium phenomena in glass formers. Both lack an accepted theoretical foundation. A model-free and unified theoretical description for these phenomena is presented that encompasses also fast -processes, emergent Debye peaks, and the relaxation strength of the boson peak. The theory is model-free in the same way as the classical Debye relaxation equation for orientational polarisation. It is based on generalizing time flow from translation semigroups to composite time translation-convolution semigroups. Composite translation-convolution fits have less parameters than traditional fits. They need only one dynamic scaling exponent, while four are needed in Havriliak–Negami fits. For glycerol the single dynamic exponent in the translation-convolution fit is found to be temperature-independent.

Effect of CeO2 Doping on the Structure and Properties of Titanium Barium Silicate Glass

Glasses with the composition 50SiO2 · 20TiO2 · 15BaO · 7.5SrO · 7.5CaO doped with the varied content of CeO2 were prepared by conventional melt quenching technique. The effect of CeO2 on the structure of glasses was investigated by X-ray photoelectron spectroscopy and Raman spectroscopy. The density, thermal stability, dielectric properties and acid resistance of glasses were studied by Archimedes method, differential thermal scanning analysis and X-ray diffraction, dielectric measuring as well as the powder method. The results showed that the coordination of Ti, which existed in glasses as [TiO4], did not change. An increase in the content of non-bridging oxygen atoms and a corresponding decrease in the content of bridging oxygens correlated. The depolymerization of the glass network was attributed to an increase in the number of Si–O–Ti bonds and the change of the Qn distribution. With an increase in the CeO2 content, the thermal stability and acid resistance of glass first increased and then decreased, and the dielectric constant and dielectric loss of glass decreased first and then increased.

Heterophase inclusions as a source of non-selective optical losses in high-purity chalcogenide and tellurite glasses for fiber optics

The results of investigation of the impurity and phase inclusions as sources of non-selective losses in high-purity chalcogenide and tellurite glasses are reported. Extinction on the SiO2 inclusions is shown to be responsible for non-selective losses in the chalcogenide glasses obtained by direct synthesis from elements in quartz equipment. Optimization of the temperature/duration conditions of the synthesis makes it possible to decrease these losses. The problem of achieving the theoretical minimum of optical loss in the glasses prone to crystallization is considered. The minimal scattering loss in such glasses can be limited not only by “freezing” fluctuations but also by the phase inhomogeneity of the glasses. A substantial contribution of the phase inclusions to optical losses is demonstrated on the example of high-purity tellurite glasses. The scattering in highly homogeneous samples of these glasses appears to be two orders of magnitude higher than the known theoretical value for scattering on “freezing” fluctuations.

Study of Dielectric and Ferroelectric Properties of Lead Titanate Glass–Ceramics

The glass samples with composition 37.5PbO:37.5TiO2:22.5B2O3:2.5SiO2 were synthesized by conventional melt quenching technique. These glasses were converted to glass–ceramic by following the two stage heat treatment, by varying systematically the duration of heat treatment. The density, dielectric constant and dielectric loss of glass and glass–ceramic samples were measured. The density and dielectric constant of the glass–ceramic samples were observed to increase with the heat treatment duration up to 32 h. The glass–ceramic samples exhibited ferroelectric hysteresis due to the presence of PbTiO3 crystals as confirmed from XRD. From the results it can be concluded that 32 h heat treatment duration is optimum for getting PbTiO3 glass–ceramic. The high temperature ferroelectric hysteresis measurements have been carried out for the optimized (32 h) glass–ceramic sample. The exhibition of ferroelectric behaviour up to 250 °C indicates the possibility of utilization of this sample for high temperature transducer applications.

Computational Methods for Determining the Effect of Stress on Cutting Quality1

The characteristics of the residual stresses arising in float-glass production are presented. The forms, causes, magnitude and direction of the stresses are described. The condition for off-cut breakage is derived mathematically. Modeling with ANSYS Structural Ver. 14.0 is used to obtain the stress pattern when the breaking bar is raised and the critical parameters for which glass losses occur during cutting are determined.

Universal dielectric loss in glass from simultaneous bias and microwave fields.

We derive the ac dielectric loss in glasses due to resonant processes created by two-level systems and a swept electric field bias. It is shown that at sufficiently large ac fields and bias sweep rates, the nonequilibrium loss tangent created by the two fields approaches a universal maximum determined by the bare linear dielectric permittivity. In addition, this nonequilibrium loss tangent is derived for a range of bias sweep rates and ac amplitudes. A predicted loss function can be understood in a Landau-Zener theory and used to extract the two-level system density, dipole moment, and relaxation rate.

Heat Loss Measurement and Analyses of Solar Parabolic Trough Receiver

The heat loss of vacuum receiver plays critical important role in solar parabolic trough system. In this paper, experimental measurements and calculation models were conducted to investigate the heat loss of solar parabolic trough receiver with receiver length of 10.2 m and diameter of 0.120 m. In general, the heat loss of receiver decreased with the receiver wall temperature, while it can approach minimum under special wind condition. The heat loss of receiver mainly included the heat loss of glass and boundary region, and the heat losses of receiver, glass region and boundary region with tube temperatures of 176.2oC were respectively 987.1 W, 762.2 W and 224.9 W. Outside the glass envelope, the convection and radiation both play an important role in the heat loss of receiver, while the heat transfer is mainly dependent upon the radiation inside the glass envelope. In addition, the heat losses of convection outside the glass and radiation inside the glass from calculation very well agreed with the experimental data.

Preparation of chalcogenide glasses of As–S, Ge–S, Ge–Se systems from monoisotopic elements

As2S3, GeS3, GeSe4 glasses have been prepared from monoisotopic (isotopically enriched) arsenic, germanium, sulfur and selenium. Impurity composition was investigated; IR-spectra and glass transition temperature of prepared glasses were measured as compared with glass samples from the elements of natural isotopic composition. It is shown that the change in isotopic composition of glass leads to the expected shift in resonance absorption bands in IR-spectra by ~1–8cm−1 as compared with the samples of natural isotopic composition. Optical fibers were fabricated from As2S3.26 glass with natS and 32S. Great difference in optical losses in glass of natural and isotopically enriched composition is due to a different degree of purity of the used sulfur.

Maxwell equation for conductivity of dielectrics as the basis of direct relationship of ionic electrical conductivity and mechanical losses in glasses. New problems of physical chemistry of glass

Use of the Maxwell equation for the conductivity of dielectrics and the theory of mechanical losses in glasses caused by ionic shifts has made it possible to calculate directly the temperature of the "ionic" max� imum of mechanical losses using data on direct current conductivity. The Maxwell equation was used without changes, in the view accepted in electromagnetic theory. An intuitive physicochemical interpretation of the nature of ionic conductivity measured at constant voltage as a relaxation process was suggested. Verification of the suggestion equation's validity was performed for onealkali glasses in silicate, borosilicate, phosphate, borate, and germanate systems. The ratio of calculated and experimental values of the temperature of the "ionic" internalfriction maximum corresponds to 0.995 ± 0.034 and does not depend on the frequency of measurements of internal friction (it changed by four orders) or the parameters characterizing conductivity. These results also confirm the validity of the Maxwell equation for the conductivity of dielectrics. The possi� bility of describing the direct current ionic conductivity of glasses as a Debye relaxation transition proved in this work is a consequence of the constant voltage condition. The design of a theory for the condition of nat� ural decay of a given potential, when the Kohlrausch relaxation regularity becomes valid, represents a princi� pally important problem of physics and physical chemistry of disordered systems.

Theoretical Analysis of Optical Losses in CdS/CdTe Solar Cells

Based on the known refractive index and extinction coefficient, calculations of optical losses in glass/ transparent conducting oxide/CdS/CdTe solar cells have been carried out taking into account reflections at the interfaces and absorption in the transparent conducting oxide (indium tin oxide or SnO2:F) and CdS layers. It has been shown that the losses caused by reflections at the interfaces result in lowering the short-circuit current by ≈ 9% whereas absorption in the transparent conducting oxide and CdS layers with the typical thicknesses lead to losses of 15–16% for glass/SnO2/CdS/CdTe, and 22–24% for glass/indium tin oxide/CdS/CdTe solar cells.

Criteria for the experimental observation of multidimensional optical solitons in saturable media

Criteria for experimental observation of multidimensional optical solitons in media with saturable refractive nonlinearities are developed. The criteria are applied to actual material parameters (characterizing the cubic self-focusing and quintic self-defocusing nonlinearities, two-photon loss, and optical-damage threshold) for various glasses. This way, we identify operation windows for soliton formation in these glasses. It is found that two-photon absorption sets stringent limits on the windows. We conclude that, while a well-defined window of parameters exists for two-dimensional solitons (spatial or spatiotemporal), for their three-dimensional spatiotemporal counterparts such a window does not exist, due to the nonlinear loss in glasses.

Straie in fluoride glasses

The source of straie in optical heavy metal fluoride glass has been established as bulk buoyancy convection. Calculation suggests that this type of glass melt is unstable to almost negligible vertical temperature gradients. The inhomogeneity originates at the melt surface and may still be a source of optical loss in glasses prepared by melting, even when convection is not active. Surface convection has also been observed. Mechanisms of homogenisation are discussed.

Influence of alkali content and alkali mixing on the chemical durability of fluorozirconate glasses

The corrosion of alkali-containing fluorozirconate glasses in water and acidic and alkaline solutions was studied with glasses of the compositions (100−x) (0.6ZrF4·0.1AlF3·0.3BaF2)· xLiF and 48ZrF4·8AlF3·24BaF2·xLiF·(20−x)NaF. The corrosion of the glasses in deionized water and 0.1 n HCl solution is mainly controlled by diffusion with an inductive period due to the passage from reaction-controlled to diffusion-controlled mechanisms, and the weight loss of glass increases with increasing LiF content in the single-alkali glasses. There was no appreciable effect of alkali mixing on the corrosion of glasses in deionized water and 0.1 n HCl solution. The glasses exhibited good stability in alkaline solution. The weight loss due to corrosion of the glasses in acidic buffered solution increased exponentially with increasing LiF content.

Low-melting glasses for the potting of thick-film microcircuits

Low-melting glasses have attained broad use in thick-film microelectronics, including the prevalent lead-containing borate compositions. Since lead glasses have a number of valuable properties, they are used successfully in manufacture of microcircuits as the lowmelting constituents of capacitance and resistance elements, as glassy materials for interlayer insulation, and as protective coatings and glass solders. We studied the SiO2-B203-AI203-PbO system with a goal of developing low-melting glasses for potting thick-film microcircuits. We studied the effect of composition on glass-forming, crystallization, and physicochemical properties and also the glass compatibility with the substrates used in microelectronics of ST-50-1 crystal, steatite, and high-alumina ceramic. The data of Fig. 1 attest that the section SiO2-B203-1OAI203-PbO has a vast region of noncrystallizing glasses with a different combination of softening temperature and thermal expansion coefficient (LCTE). The absolute values of the latter are within the limits 315575~ and 50-90.I0-7~ -I, respectively, and depend basically on the PbO content of the glass. High-lead glasses of reduced wetting temperature have a relatively high LCTE. The glasses studied are typified by a comparably good water stability, a deciding effect on which is the B203 content. Accordingly, on increase of molar B203 content from i0 to 50~, the loss of glass in water increases from 0.02 to 2.75~. The most chemically stable are compositions of elevated SiO2 content. The glass dielectrics in thick-film microcircuits should combine a low melting temperature with a high chemical stability and a LTCE corresponding to that of the substrate material in order to ensure the spreading and adhesion of the glass film to the substrate while not initiating a chemical reaction with microcircuit materials. Figure 2 gives data on a study of the compatibility of glasses in the SiOz-BzO3-!0Al203-PbO system with substrates used in microelectronics of ST-50-1 crystal (LCTE -52.10-7~ 22KhS ceramic (LCTE -65.10-7~ -I, and steatite (LCTE -70.I0-7~ The coatings were obtained by applying a thin layer of glass powder to the substrate and annealing at 400-700~ As apparent, the glasses studied with a LCTE below the substrate LCTE form monolithic coatings without cracks, having good spreadability and strong adhesion of the glass film to crystal, steatite, and 22KhS ceramic. Coatings based on glasses with a LCTE above that of the substrate have cracks. There is an opinion that materials used in thick-film microelectronics should have a LCTE comparable to that of a substrate. It is known that for silver-palladium resistance compositions the LCTE of the glass binder should be 3-7~ below that of the substrate. Since glass is subject to substantial compressive stresses and sight tensile forces, according to our data, the glass composition for monolithic glass coatings without cracks must provide that the glass is in a state of compression; the LCTE of the glass should thus not exceed the LCTE of the substrate. We achieved during production of glasses for microelectronics, the resulting rules concerning the effect of glass composition on its properties and compatibility with the substrates used in electronics, and in microelectronics. Using modifying additives to optimize the oxide properties (RO and ROz), low-melting glasses of the types 71, 82, and 83 were developed in the SiO2-B203-AI203-PbO system for the potting of thick-film capacitance and resistance elements. The basic properties of the glasses are shown in Table 1 (patents 1081135, 1227605, 1313817). We used pure and analytical grade raw materials for synthesis of the glasses: sand, boric acid, alumina, and oxides of diand tetra-valent metals. The glasses were founded in a gas furnace in quartz crucibles at a temperature of 1300 • 50~ With this regime, the

Influence of the Design of Transmission Rooms on the Sound Transmission Loss of Glass--Intensity Versus Conventional Method

Influence of the Design of Transmission Rooms on the Sound Transmission Loss of Glass--Intensity Versus Conventional Method