Glass Rings Research Articles

Dirac‐mode guidance in silica‐based hollow‐core photonic crystal fiber with high‐index dielectric rings

Transmission of light in hollow‐core photonic crystal fiber (HC‐PCF) is traditionally based on the out‐of‐plane photonic bandgap of the crystal cladding that usually consists of periodically arranged air holes in silica glass. A new kind of wave guidance relying on a special point (Dirac point) of eigenfrequency dispersion plot in high‐index glass‐based HC‐PCF has been reported recently. Pure silica‐based HC‐PCF is not suitable for this kind of guidance. The existence of the Dirac point in a triangular lattice of air holes surrounded by a germania (GeO2)‐doped high‐index ring in pure silica host has been demonstrated. The addition of the high‐index layer provides a control over the density of states around the Dirac point. The operating wavelength can be tuned precisely by controlling the doping concentration and thickness of the doped glass rings. The structure is very simple and can be fabricated through a conventional stack and draw method.

Ag-loaded ZnO materials for photocatalytic water treatment

ZnO materials with different morphologies were obtained by hydrothermal and solid state techniques. The ZnO materials were loaded with different amounts of silver nanoparticles (atomic percentages ranging from 0.25 to 1) by a liquid impregnation method. The materials were characterized by physical adsorption of nitrogen, scanning and high-resolution transmission electron microscopy (SEM, HRTEM), UV–vis diffuse reflectance spectroscopy (DRUV-Vis), X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR). The photocatalytic efficiency of the materials was assessed in the degradation of phenol using simulated solar light, by means of the pseudo-first-order kinetic constant (kapp) for phenol conversion and corresponding degree of mineralization.The photocatalyst made of ZnO prepared by thermal decomposition of zinc acetate (ZnO-t) loaded with a 0.25 atomic percentage of Ag (0.25%Ag/ZnO-t) was the most efficient, reaching a 58% mineralization after 60min irradiation (kapp=7.7×10−2min−1). Trapping of photogenerated holes and radicals by selective scavengers showed that photogenerated holes played the main role on phenol oxidation. The study was extended to a complex mixture containing phenol, resorcinol, 4-methoxyphenol and 4-chorophenol using bare ZnO-t and 0.25%Ag/ZnO-t photocatalysts, either in powder form or immobilized on glass rings (packed in a continuous photocatalytic reactor). The conversion of the phenolic compounds was faster when Ag particles were deposited on the photocatalyst.

Photocatalytic degradation of an emerging pollutant by TiO2-coated glass rings: a kinetic study.

This work presents the photocatalytic degradation of the pharmaceutical drug clofibric acid in a fixed-bed reactor filled with TiO2-coated glass rings. Experiments were carried out under UV radiation. A kinetic model that takes into account radiation absorption by means of the local surface rate of photon absorption (LSRPA) has been developed. The LSRPA was obtained from the results of a radiation model. The Monte Carlo method was employed to solve the radiation model, where the interaction between photons and TiO2-coated rings was considered. Data from experiments carried out with rings with different numbers of catalyst coatings and different irradiation levels were used to estimate the parameters of the kinetic model. A satisfactory agreement was obtained between model simulations and experimental results.

Hydrogen production via methane pyrolysis in a liquid metal bubble column reactor with a packed bed

Methane pyrolysis experiments using a quartz glass-steel bubble column reactor filled with liquid tin and cylindrical quartz glass rings serving as a packed bed were conducted at various liquid metal temperature levels in the range of 930–1175°C. Besides the liquid metal temperature, special attention was paid to the influence of the feed gas volume flow rate in the range of 50–200mln/min and the inlet feed gas dilution with nitrogen. Increasing liquid metal temperatures resulted in increasing hydrogen yields, leading to a maximum hydrogen yield of 78% at 1175°C and 50mln/min methane volume flow rate. Within all experimental runs, less than 1.5mol-% intermediate products were detected in the product gas. The produced carbon appeared as a powder consisting of flake shaped agglomerations in the size range of 15–20μm, wherein the particle size varied from 40nm to 100nm. During the experiments, the produced carbon was completely separated and accumulated at the top surface of the liquid metal. Only minor quantities were transported with the off gas stream. Within the liquid metal inventory, a thin carbon layer of about 10μm, probably partly showing the formation of nanotubes, in the hot reaction zone, had been deposited on the quartz glass reactor wall.

Note: High temperature pressure sensor for petroleum well based on silicon over insulator.

In order to meet the requirements in petroleum well, a novel structure of high temperature pressure sensor based on the silicon over insulator (SOI) technology is proposed in this paper. The SOI sensor chip is bonded with a glass ring by electrostatic bonding. By controlling the inner diameter of the glass ring, the size of the circle membrane is obtained precisely. And the detailed parameters of the structure are established through analysis. Then, the sensor is fabricated. The test results show that this type sensor has high sensitivity and accuracy. It is able to measure at the temperature up to 180 °C and the measuring range is 60 MPa. Moreover, the results we got are closer to the actual situation.

A remarkable vision – Brewster's 1822 proposal for a ‘National Burning Apparatus’

In order to reduce the energy losses resulting from the thickness of large burning glasses, the French naturalist the Comte de Buffon proposed that such lenses should consist of a relatively small central lens surrounded by a series of stepped annular glass rings, all ground to direct light to the same focal point. In order to simplify the problems associated with manufacturing such rings, the Scottish physicist Sir David Brewster suggested in 1822 that it would be simpler if each annular ring consisted of a number of separate close-fitting segments. Convinced of the importance for scientific research in Britain of the availability of a burning glass larger than could be afforded by any single institution, he proposed the construction of a ‘National Burning Apparatus,’ “to the construction of which all the scientific institutions in the kingdom might contribute” – a remarkably prescient vision of the need for and value of national research facilities. He also outlined some of the important research that might be undertaken using such a device. However, his proposal elicited no response.

Three‐Dimensional Modeling of Glass Lens Molding

The required accuracy for the final dimensions of the molded lenses in wafer‐based precision glass molding as well as the need for elimination of costly experimental trial and error calls for numerical simulations. This study deals with 3D thermo‐mechanical modeling of the wafer‐based precision glass lens molding process. First, a comprehensive 3D thermo‐mechanical model of glass is implemented into aFORTRANuser subroutine (UMAT) in theFEprogramABAQUS, and the developedFEmodel is validated with both a well‐known sandwich seal test and experimental results of precision molding of several glass rings. Afterward, 3D thermo‐mechanical modeling of the wafer‐based glass lens manufacturing is performed to suggest a proper molding program (i.e., the proper set of process parameters including preset force‐time and temperature‐time histories) for molding a wafer to a desired dimension and quality. Moreover, the effect of some important process parameters such as cooling rate and pressing temperature on the final size and residual stress inside the wafer is evaluated. Finally, it is noted that the suggested molding program minimizes the costly empirical efforts and raises the process efficiency.

Temporal and spatial stability of ammonia-oxidizing archaea and bacteria in aquarium biofilters.

Nitrifying biofilters are used in aquaria and aquaculture systems to prevent accumulation of ammonia by promoting rapid conversion to nitrate via nitrite. Ammonia-oxidizing archaea (AOA), as opposed to ammonia-oxidizing bacteria (AOB), were recently identified as the dominant ammonia oxidizers in most freshwater aquaria. This study investigated biofilms from fixed-bed aquarium biofilters to assess the temporal and spatial dynamics of AOA and AOB abundance and diversity. Over a period of four months, ammonia-oxidizing microorganisms from six freshwater and one marine aquarium were investigated at 4–5 time points. Nitrogen balances for three freshwater aquaria showed that active nitrification by aquarium biofilters accounted for ≥81–86% of total nitrogen conversion in the aquaria. Quantitative PCR (qPCR) for bacterial and thaumarchaeal ammonia monooxygenase (amoA) genes demonstrated that AOA were numerically dominant over AOB in all six freshwater aquaria tested, and contributed all detectable amoA genes in three aquarium biofilters. In the marine aquarium, however, AOB outnumbered AOA by three to five orders of magnitude based on amoA gene abundances. A comparison of AOA abundance in three carrier materials (fine sponge, rough sponge and sintered glass or ceramic rings) of two three-media freshwater biofilters revealed preferential growth of AOA on fine sponge. Denaturing gel gradient electrophoresis (DGGE) of thaumarchaeal 16S rRNA genes indicated that community composition within a given biofilter was stable across media types. In addition, DGGE of all aquarium biofilters revealed low AOA diversity, with few bands, which were stable over time. Nonmetric multidimensional scaling (NMDS) based on denaturing gradient gel electrophoresis (DGGE) fingerprints of thaumarchaeal 16S rRNA genes placed freshwater and marine aquaria communities in separate clusters. These results indicate that AOA are the dominant ammonia-oxidizing microorganisms in freshwater aquarium biofilters, and that AOA community composition within a given aquarium is stable over time and across biofilter support material types.

Precision Glass Molding: Validation of an FE Model for Thermo‐Mechanical Simulation

In precision glass molding process, the required accuracy for the final size and shape of the molded lenses as well as the complexity of this technology calls for a numerical simulation. The current paper addresses the development of an FE model for thermo‐mechanical simulation of the precision glass molding process including heating, pressing, and cooling stages. Temperature‐dependent viscoelastic and structural relaxation behavior of the glass material are implemented through a FORTRAN material subroutine (UMAT) into the commercial FEM program ABAQUS, and the FE model is validated with a sandwich seal test. Subsequently, precision molding of several glass rings is performed at three different pressing temperatures, and the experimental deformation of the glass rings at the end of the molding is compared with the predicted ones from FE simulation. Furthermore, the transient and residual stress distribution inside the glass rings are calculated by the developed FE model, and the effects of some important process parameters such as interface friction and mold temperature on the FE results are assessed. The developed FE model can be employed to predict the deformation behavior, final size/shape, and the residual stress state inside the glass lenses in a precision glass molding process.

An SLF magnetic antenna calibration system

Calibrating the super low frequency (SLF) magnetic antenna in magnetic free space or an outdoor environment is difficult and complicated due to the large size calibration instruments and lots of measurement times. Aiming to calibrate the SLF magnetic antenna simply and efficiently, a calibration system comprised of a multi-frequency source, an AC constant-current source and a solenoid is proposed according to the characteristic of an SLF magnetic antenna. The static magnetic transfer coefficient of the designed solenoid is calibrated. The measurement of the frequency response characteristics suggests the transfer coefficient remains unchanged in the range of the SLF band and is unaffected by the magnetic antenna internally installed. The CORDIC algorithm implemented in an FPGA is realized to generate a linear evenly-spaced multi-frequency signal with equal energy at each frequency. An AC constant weak current source circuit is designed in order to avoid the impact on the magnetic induction intensity of a calibration system affected by impedance variation when frequency changing, linearity and the precision of the source are measured. The frequency characteristic of a magnetic antenna calibrated by the proposed calibration system agrees with the theoretical result and the standard Glass ring calibration result. The calibration precision satisfies the experimental requirement.

Evaluation of the viscoelastic behaviour and glass/mould interface friction coefficient in the wafer based precision glass moulding

Recent improvements in the manufacturing process of camera lenses have introduced the use of a new technology involving wafer based precision glass moulding. The utilization of this technology has some important advantages such as cost reduction, supply chain simplification and higher image quality. However, the required accuracy for the final size and shape of the moulded lenses as well as the complexity of this technology call for a high level of process understanding and numerical simulation is a very important part of achieving this goal. The viscoelastic parameters of the optical glass as well as the glass/mould interface friction coefficient play a key role in deformation behaviour and stress distribution of the moulded glass lens. Therefore, a proper evaluation of these parameters is the first important step in numerical modelling of the precision glass moulding process.The current paper deals with characterization of the interfacial glass/mould friction coefficient and viscoelastic behaviour of the L-BAL42 glass material above the glass transition temperature. Several glass rings are pressed at three different temperatures to various thicknesses and the experimental force, displacements, internal diameter and thickness of the rings are measured during the tests. Viscoelastic and structural relaxation behaviour of the glass are implemented into the ABAQUS FEM software through a FORTRAN material subroutine (UMAT) and the FE model is validated with a sandwich seal test. Then, by FE simulation of the ring compression test and comparison of the experimental creep with the simulated one in an iterative procedure, viscoelastic parameters of the glass material are characterized. Finally, interfacial glass/mould friction coefficients at different temperatures are determined through FEM based friction curves combined with experimental data points. The obtained viscoelastic parameters and interfacial friction coefficients can later be employed for prediction of the final shape/size as well as the stress distribution in the glass wafer during a real wafer based precision glass moulding process.

Polymerization shrinkage of six different fissure sealants

Objectives: The objective of this study was to evaluate and compare the polymerization shrinkage of six proprietary pit and fissure sealants (Helioseal F, Fissurit FX, Smartseal & loc F, Dyract Seal, Clinpro TM Sealant, Teethmate F-1). Materials and Methods: A total of 120 glass ring molds (8.5 mm in inner diameter and 2 mm in height) were prepared after which the internal surface of the molds were etched with hydrofluoric acid for 5 min. The test materials (n = 20/group) were placed into the molds and thereafter sandwiched between two glass slides. All groups were polymerized for 20 s using a high-intensity quartz tungsten halogen (HQTH) light unit (Optilux 501). The volumetric polymerization shrinkage for each pits and fissure sealant was measured using the specific density method modified by Puckett and Smith. All data were analyzed statistically using one-way analysis of variance and Tukey honest significant difference (HSD) test at P Clinpro TM Sealant (6.60 ± 1.54%) > Dyract Seal (5.38 ± 1.30%) > Smartseal & loc F (5.06 ± 1.22%) > Fissurit FX (4.30 ± 1.15%) > Helioseal F (3.30 ± 0.69%). Clinpro TM Sealant and Teethmate F-1 displayed the highest shrinkage values (P < 0.05). The lowest shrinkage values were obtained with Helioseal F (3.30 ± 0.69%) and Fissurit FX (4.30 ± 1.15%) (P < 0.05). Conclusion: Within the experimental conditions of the present study, sealant materials containing higher concentrations of fillers displayed lower polymerization shrinkage values.

アミロース含有率の異なる米粥のガラスリング法を用いた力学的特性評価の有効性

【目的】アミロース含有率の異なるもち米（アミロース0％），低アミロース米（11.9％），中アミロース米（16.2％），高アミロース米（27.9％）を用い加水量一定の米粥を調製し，アミロース含有率の相違が及ぼす力学的特性と食べやすさへの影響および米粥の口中感覚を推測するのに有効な力学的特性測定方法を検討した。【方法】材料米重量に対し5.0倍加水し，真空包装後95°C湯浴中60分間加熱し米粥試料を得た。試料品温とテクスチャー特性の関係，粥液重量，力学的特性の簡便な評価法としてガラスリング法（以下リング法）を用いて測定し，官能評価を行った。【結果】高アミロース米試料は品温30°C以下で顕著に硬くなる傾向を示し，品温20°Cで高アミロース米試料の硬さは他の3試料と比べ有意に硬くなった。付着性は品温20°Cで4種の試料間に有意差は認められなかった。高アミロース米試料は，品温20°Cで他の3種と比較してリング内壁の付着重量は有意に小さくなった。官能評価より，高アミロース米試料は最も口中でかたく，べたつかないと評価された。【考察】官能評価の結果より，もち米試料と比較し口中で有意にべたつかないと評価された高アミロース米試料のリング内壁の付着重量は，有意に小さくなった。本研究で用いたような明らかな力学的特性の差が認められる米粥試料の場合，口中でのべたつき感はリング法により得られるリング内壁の付着重量により推測できる可能性が示唆された。

Effect of multiple contactless rotations of charged particles in a hollow circular glass ring

Experimental results concerning the existence of a new physical effect of multiple (many-millioned) rotations of charged particles in a circular hollow electrified glass ring are reported for the first time. Experiments are performed for electron and ion beams. A theoretical model of the interaction of particles with the electrified channel wall is proposed. The effect of acceleration of particles in a circle in which an electrode at a low potential of ∼2 kV is fixed is discovered experimentally. Particles are accelerated in this case to hundreds of kilovolts. Intense radiation in the hard X-ray and γ ranges is generated as a result of interaction of accelerated particles with a thin tungsten filament. A number of important applications of the multiple rotation effect are briefly discussed.

Structural investigation of glasses along the MgSiO3–CaSiO3 join: Diffraction studies

The structure of glasses along the MgSiO3–CaSiO3 join has been investigated by X-ray and neutron diffraction measurements. Structure models were constructed by fitting the experimental data using the Reverse Monte Carlo method (RMC). The structural data indicate a random mixing between MgSiO3 and CaSiO3 glasses, in accordance with their melt properties. Though important disordering is observed, the structure evolves continuously along the join. The Ca environment is essentially similar for all compositions, with an average of 6 to 7-coordinated sites. The Mg environment tends to have higher coordinated sites as the MgO content decreases. There is a continuous mixing of Ca–Mg pairs with a non-random distribution emphasized by the distinct cation–cation distances. Changes were observed in the topology of the silicate network. The proportion of non-bridging oxygens decreases, the number of free-oxygens increases and the ring size distribution is shifted to high-membered rings in the Mg-rich glasses. These structural investigations indicate important differences with the crystalline pyroxene structures.

Photocatalytic activity of TiO2-coated glass raschig rings on the degradation of phenolic derivatives under simulated solar light irradiation

Glass raschig rings were coated with different types of TiO2, namely Evonik P25 (EP), anatase TiO2 from Sigma–Aldrich (SA), and TiO2 obtained from a sol–gel procedure. The efficiency of the coating was tested on the degradation of phenol using simulated solar light irradiation. Regardless the material tested, phenol degradation gradually increases with the number of TiO2 layers. SA-coated glass rings show the highest efficiency for phenol degradation (90% conversion), but do lose activity when reused (78% conversion after 2 cycles) due to particle disaggregation from the support. Rings coated with EP are the most stable with an average 72% conversion over 3 cycles.Raschig rings coated with 3 layers of EP were used for the treatment of a synthetic effluent consisting of a solution with a mixture of seven phenolic derivatives namely phenol, 4-hydroxybenzoic acid, 4-methoxyphenol, 4-phenylethyl alcohol, benzoic acid, protocatechuic acid and gallic acid. Photocatalytic degradation efficiency depended on the organic compound, the most easily degraded molecule being gallic acid (85% removal after 8h of irradiation) contrasting with 4-hydroxybenzoic acid which was the most refractory compound (3% removal). A relationship between the extent of photocatalytic degradation and the activating/deactivating nature of the aromatic ring substituents is proposed.

MEDIEVAL LEAD GLASS IN CENTRAL EUROPE

In Trommsdorfstraße, Erfurt, a glass-processing workshop has been excavated, which produced lead glass rings and beads in the 13th century. This workshop produced two different lead glasses. The first, a high-lead glass, could be found throughout Europe, from England to Russia. However, another newly defined type of glass could be identified (Central European lead–ash glass). This can be demonstrated by analysing the literature, and it has been found in eastern Germany, Poland, Slovakia and the Czech Republic. A Slavic lead–ash glass with the same ash content as the Central European lead–ash glass but lower amounts of lead was produced in Eastern Europe. In western Germany, another type of ash (beech ash) was used to produce a wood-ash lead glass. Lead-isotope analysis proved that the same source of lead was used for the wood-ash lead glass and the high-lead glass in western Germany and the two types of glass from Erfurt.

In-situ high temperature Raman and Brillouin light scattering studies of sodium silicate glasses

In-situ Raman and Brillouin light scattering experiments were carried out to study the structure and elastic properties of sodium silicate glasses xNa2O–(100−x)SiO2 (x=0, 8, 10, 15, 20, 25, 30, and 40mol%) from room temperature up to the respective glass transition temperature for each composition. Temperature independent shear modulus and Young's modulus were observed in 15Na2O–85SiO2 glass up to 400°C, while the temperature independent bulk modulus occurred in glass with 15 to 20mol% Na2O in the same temperature range. A simple correlation was established between the Raman spectrum of a sodium silicate glass at room temperature and the evolution of its elastic properties with increasing temperature. The silica network stiffens upon heating up due to the conformation change from α-like to β-like rings in silica-rich sodium silicate glasses, characterized by the main band at ~440cm−1 in Raman spectra. When the 950cm−1 band associated with the Q2 species becomes obvious after substantial amount of Na2O was added into the glass matrix, glasses behave like normal solids (softening upon heating up). If neither the main band at ~440cm−1 nor the 950cm−1 band is well defined, intermediate glasses emerge, whose elastic moduli do not change with temperature because the stiffening and softening effects become comparable.

Generation of a human urinary bladder smooth muscle cell line

We report a cell line (hBSM) established from human urinary bladder wall smooth muscle that maintains most of the phenotypic characteristics of smooth muscle cells. Cells were dissociated from the muscular layer with collagenase (1mg/ml) and collected and grown in M199 supplemented with 10% fetal calf serum and 1% antibiotic-antimycotic. Primary cultures were grown for 2d and small colonies were isolated by placing glass rings around the colonies. These colonies were picked up with a fine-tipped Pasteur pipette and subcultured. This procedure was repeated several times until a culture with a uniform stable morphology was obtained. hBSM cells are elongated with tapered ends, and in high density cultures, they form swirls of cells arranged in parallel. These cells have a doubling time of approximately 72 h. Western blotting and immunofluorescence microscopy revealed stable expression of smooth muscle-specific proteins, including myosin isoforms (N-terminal isoforms SM-A/B and C-terminal isoforms SM1/2), SM22, α-smooth muscle actin, h-caldesmon, Ca(2+)-dependent myosin light chain kinase, and protein kinase G. These cells contract upon exposure to 10μM bethanechol and this contraction is reversible by washing away the drug. Karyotyping showed tetraploidy with a modal chromosome number of 87, with multiple rearrangements. To our knowledge, the hBSM cell line is the first human cell line established from bladder wall smooth muscle that expresses both N- and C-terminal smooth muscle myosin isoforms. This cell line will provide a valuable tool for studying transcriptional regulation of smooth muscle myosin isoforms and effects of drugs on cellular function.

Applicability of the Glass Ring Method for a Simple Evaluation of the Physical Properties of Gel-type Blender Gruel

Applicability of the Glass Ring Method for a Simple Evaluation of the Physical Properties of Gel-type Blender Gruel