Glass Rings Research Articles

The fluidity and molding ability of glass-forming Zr-based alloy melt

The fluidity and filling ability of glass-forming Zr-based alloy melt in copper mould were investigated both theoretically and experimentally. The major factors which affected the flowing behavior of the metallic melt in the mold were determined, which provides the foundation for overcoming the contradiction between the filling and formation of amorphous alloy during the rapid cooling process of the metallic melts. The casting factors to prepare a metallic ring were discussed and selected. As a result, a Zr-based bulk metallic glass ring was prepared successfully.

THE STUDY OF COPPER-DOPED B2O3·Bi2O3 GLASS MATRIX BY SPECTROSCOPIC METHODS

Glasses of x CuO · (100-x)[ B 2 O 3 · Bi 2 O 3] systems with 0≤x≤50 mol% were prepared and investigated by means of FT-IR, Raman and optical absorption spectroscopies. Complex network structures mainly built by BiO 3, BiO 6, BO 3 and BO 4 units were revealed for these glasses by means of FT-IR measurements. Similar structures were evidenced by means of Raman spectroscopy and additional new structural groups were detected in the glass structures, i.e. pyroborate, chain and ring type metaborate groups. The influence of copper-ion content (x) on the short-range order structure evolution was investigated. The optical absorption spectra for all glass samples present a single asymmetric band which corresponds to a 2 B 1g→2 B 2g transition of the of Cu 2+ ions in octahedral symmetry with an elongated tetragonal distortion.

Raschig rings-Fe2O3 composite photocatalyst activate in the degradation of 4-chlorophenol and Orange II under daylight irradiation

Fe2O3 on Raschig glass rings (Fe2O3/RR) was investigated as photocatalyst under simulated solar radiation during the degradation of 4-chlorophenol (4-CP) and the azo dye Orange II (Or II). Thin films of Fe2O3 particles were coated on glass rings using polyethylene-graft-maleic anhydride (PEGMA) as a negative interfacial agent. The Fe2O3/RR photocatalyst presented absorption in the visible range up to 535nm. The catalytic activity of Fe2O3/RR coated with preformed Fe2O3 (11.4m2/g) was found to be superior to that of Fe2O3/RR1 catalyst obtained by the precipitation of Fe-ions on the glass rings surface. The photoactivated degradation of 4-CP and Or II was possible at pH values of 5.5 using both catalysts. The Fe2O3/RR photocatalyst shows a stable catalytic performance during long-term operation under simulated sunlight radiation. The Fe2O3/RR and Fe2O3/RR1 photocatalysts were characterized by diffusion reflectance spectroscopy (DRS), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), atomic absorption spectroscopy (AAS) and gas adsorption measurements (BET). The Fe 2p binding energy (BE) in the Fe2O3/RR samples was 711.6eV before the catalysis and 711.7eV after the catalysis, indicating the stability of the Fe-oxidation state on the glass rings. The pore diameter did not decrease when going from Fe2O3 powder to the Fe2O3 attached on the Raschig glass rings but the Fe2O3 BET area decreased considerably involving restructuring of the Fe2O3 particles. The experimental data allows to formulate a mechanism of reaction for the degradation of 4-CP on the Fe2O3/RR catalyst.

The formation of nanoscale structures in soluble phosphosilicate glasses for biomedical applications: MD simulations

The occurrence of chain-like fragments and rings in phosphosilicate glasses of known bioactivity was examined using classical molecular dynamics simulations, in order to reveal the possible effect of such nanostructures on the bioactive behaviour. Highly bioactive compositions display a large fraction of non-crosslinked, nonlinear chains of tetrahedra, which are not present in bio-inactive compositions. The low(er) energetic cost associated with the direct release of these silicate fragments into solution can assist the fast partial dissolution observed for bioactive glass compositions. Loss of bioactivity when the silicate content increases is accompanied by the transformation of these chains into small closed rings (3- to 8-membered), which appear to protect the silicate network from fast dissolution.

Short-Term Cytotoxicity Assessment of Components of the Epiphany Resin-Percha Obturating System by Indirect and Direct Contact Millipore Filter Assays

The Epiphany Resin-Percha Obturating System was assessed for cytotoxicity, compared with gutta-percha and AH-Plus sealer. Specimen disks (Resilon, gutta-percha), filled glass rings (sealers), or imbibed cellulose disks (primer, thinning resin) were placed over Millipore filters in direct or indirect contact with HeLa cell monolayer, incubated for 2 hours, and stained with tetrazolium blue. Cytotoxicity was rated by the surrounding unstained zone: none (0 mm), mild (≤7 mm), moderate (7–12 mm), or marked (>12 mm). Data were analyzed with one-way ANOVA and post hoc pairwise t tests. Unstained zones indicating moderate cytotoxicity were significantly larger (p < 0.05) for Epiphany primer than for thinning resin and for freshly mixed AH-Plus than for Epiphany sealer. Set sealers (24 and 48 hours), gutta-percha, and Resilon elicited noncytotoxic responses. In conclusion, cytotoxicity of set Epiphany sealer and Resilon was comparable with that of set AH-Plus and gutta-percha. Cytotoxicity of freshly mixed Epiphany sealer, primer, and thinning resin did not exceed that of freshly mixed AH-Plus.

Absorption of carbon dioxide by raw and treated dye-bath effluents

A bench-scale experimental apparatus, consisting of a glass column randomly packed with cylindrical glass rings, was utilized for the removal of carbon dioxide (CO 2) by chemical absorption. Various liquid solvents were used, in a batch mode, circulating between the column and a reservoir vessel, and contacting the gas in counter current flow. The absorptive capacity of the liquid solvents and the absorption kinetics were studied by obtaining the respective ‘breakthrough curves’. Aqueous solutions of sodium hydroxide (NaOH) were initially utilized in order to demonstrate the experimental apparatus function. Dye-bath effluent proved highly effective due to its high alkalinity and the capacity of the hydrolyzed “azo-reactive” dyes to react with CO 2. Decolorized dye-bath effluent (treated with FeSO 4) can also be used as a chemical solvent for the absorption of CO 2; however, its absorptive capacity is much lower compared to the raw wastewater. The above technique is also a very effective method to neutralize industrial effluents.

Design of low-loss and highly birefringent hollow-core photonic crystal fiber

A practical hollow-core photonic crystal fiber design suitable for attaining low-loss propagation is analyzed. The geometry involves a number of localized elliptical features positioned on the glass ring that surrounds the air core and separates the core and cladding regions. The size of each feature is tuned so that the composite core-surround geometry is antiresonant within the cladding band gap, thus minimizing the guided mode field intensity both within the fiber material and at material/air interfaces. A birefringent design, which involves a 2-fold symmetric arrangement of the features on the core-surround ring, gives rise to wavelength ranges where the effective index difference between the polarization modes is larger than 10(-4). At such high birefringence levels, one of the polarization modes retains favorable field exclusion characteristics, thus enabling low-loss propagation of this polarization channel.

Les éléments de parure en verre du site de Lumaca (Âge du Fer, Centuri, Haute-Corse) : compositions et typochronologie

Lumaca, an open air settlement located at the northern end of Cap Corse, was occupied from the Early Neolithic until historic times. This long occupation is explained by the presence of a little sheepfold; all the stratigraphic levels are strongly disturbed. During the excavation of the site eight glass beads and rings were discovered. Analyses reveal that these ancient glass beads were all manufactured with Near-Eastern soda glasses. These glasses, obtained by fusing calcareous sands together with a mineral soda flux, characterise the production of the Syro-Palestinian glass factories and are found throughout the Mediterranean Basin from the beginning of the first millennium B. C. to the end of the first millennium A. D. The analytical data allow the beads from Lumaca to be divided in three groups which are essentially attributed to the Iron Ages (from Hallstatt to the 1st century A. D.). It is important to note that these beads were discovered in a dwelling and not (as often) in a tomb.

Photocatalytic EDTA degradation on suspended and immobilized TiO 2

The photocatalytic degradation of EDTA solutions (5 mM) has been studied under different conditions in the presence of TiO 2 in suspension or immobilized on glass rings and in the absence and presence of Fe(III). Using the response surface methodology, the initial pH, amount of photocatalyst, and the Fe/EDTA molar ratio were optimized in order to obtain better degradation. Under optimized conditions, 90% EDTA degradation (at a 0.28 Fe/EDTA molar ratio) was reached after 60 min illumination at pH 3.0 and using 0.73 g L −1 TiO 2. Increase of the acute toxicity (Microtox) was observed in the course of the reaction, and degradation intermediates were identified by GC/MS analysis.

Innovative Supported Composite Photocatalyst for the Oxidation of Phenolic Waters in Reactor Processes

This study focuses on the preparation and performance of an innovative, novel supported TiO2 photocatalyst to fix TiO2 Degussa P25 on Raschig glass rings. An interfacial electrostatically charged agent polyethylene−graft−maleic anhydride is used as a binder for the TiO2. This photocatalyst presented a stable performance during the degradation of phenolic waters. The photodegradation process was investigated as a function of (i) the concentration of the electron acceptor (H2O2), (ii) the intensity of the applied light, and (iii) the recirculation of the wastewaters in the photoreactor. The TiO2 catalyst was observed to maintain the pH at values close to 7 during the reactor treatment, enabling the treated phenolic waters to be discharged directly to a biological treating station. Modeling of the phenolic waters degradation was conducted through a single-exponential polynomial function. This gives a systematic way to determine the most economic use of the oxidant (H2O2) and electric energy required for the degradation process.

EVALUATION OF GRAFT COMPATIBILITY FOR TAXONOMIC RELATIONSHIPS AMONG SPECIES OF THE ORANGE SUBFAMILY

EVALUATION OF GRAFT COMPATIBILITY FOR TAXONOMIC RELATIONSHIPS AMONG SPECIES OF THE ORANGE SUBFAMILY

Surface study of water influence on chemical corrosion of Roman glass

Roman glass surfaces have been studied to understand water effects on glass degradation and ionic mobility. Studied specimens mainly come from the Roman ship Iulia Felix, found on the seabed of Grado lagoon (Italy) and dated to the 2nd century AD. Many different corrosion features have been investigated including white glass, glossy glass and growth rings. A typical multilayered structure found in glass is characterised by the presence of different ions in depth profiles. Layered structure is also underlined by variations in hydration oxygen value and adventitious carbon content. Evidence of ion mobility can be found in the study of growth rings, which have metal rich centres rounded with concentric rings. The centres are characterised by the presence of antimony and titanium in their maximum oxidation state: Sb(V) and Ti(IV). The evolution can be understood according to ‘Liesegang ring’ kinetics. Data of glass surfaces have been collected using many techniques, i.e. X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and environmental scanning electron microscopy (ESEM). Several bulk techniques to characterise the specimens have been used.

Low-Cost TiO2 Photocatalytic Technology for Water Potabilization in Plastic Bottles For Isolated Regions. Photocatalyst Fixation

Abstract Experiments to evaluate the photocatalytic activity of supported TiO2 to potabilize water in common plastic PET bottles under solar irradiation were performed. Commercial titanium dioxide (Degussa P-25) was applied to different cheap materials—glass rings, glass rods and porcelain beads—by dip coating, or directly to the plastic wall of the bottles. The adherence and stability of TiO2 on the supports and the photocatalytic activity in bottles under solar irradiation was evaluated using model compounds as 4-chlorophenol and 2,4-dichlorophenoxyacetic acid. Rings were found to be the best glass supports, but PET bottles were superior for this specific application, as no fragile fillings are used, and the materials can be easily fabricated on site.

Sol–gel preparation of TiO 2–ZrO 2 thin films supported on glass rings: Influence of phase composition on photocatalytic activity

In order to optimize the characteristics of TiO 2–ZrO 2 thin films supported on glass for the photocatalytic removal of VOCs, acidic sols of different composition (ZrO 2, TiO 2 and Ti–Zr mixed oxides) have been prepared using metal alkoxides as starting materials. The photoactive oxides were deposited on “Raschig rings” of borosilicate glass using a dip-coating technique. The phase composition of the thin films was controlled during the sol preparation stage to produce either (1) Ti 0.90Zr 0.10O 2 solid solutions, or (2) ZrO 2/TiO 2 binary metal oxides (10% and 20% molar content of Zr). The particle size of the different sols was measured by photon correlation spectroscopy, and the xerogels were characterized by XRD, N 2 adsorption isotherms, and TG–DTA, so as to monitor the modifications induced by the thermal treatments. Raman spectroscopy was used to determine the crystalline structure of the supported TiO 2–ZrO 2 oxides, which in all cases corresponded to the anatase phase. The band gap of the thin films was estimated from the UV–vis spectra, and none of them differed significantly from that of unmodified TiO 2. The photoactivity of the coated glass “Raschig rings” was measured for the oxidation of acetone and methylcyclohexane vapors using, respectively, total recycle and single pass plug flow photoreactors. The results obtained indicate that, for the same Zr content, the photoactivity of the films containing binary metal oxides is slightly higher than that of the solid solution. In contrast, specific surface area seems to have little influence on the performance of the thin films.

Photodegradation of dyes in aqueous solutions catalyzed by highly efficient nanocrystalline titania films

Thin nanocrystalline titanium dioxide films were deposited on glass rings by the sol-gel method in the presence of ethanol, acetic acid and the non-ionic surfactant Triton X-100. Nanocrystallites are formed due to surfactant self-organization that acts as a template. These films have high active surface area and are very efficient for the photodegradation of dyes in aqueous solutions. In addition, the catalyst can be easily recovered and can be repeatedly used without loss of efficiency. Three dyes were used: Basic Blue 41, Acid Orange 7, and Crystal Violet. Decoloration of solutions of Basic Blue is much faster than those of the other two dyes. A very low load of catalyst, i.e. 120 mg l−1, is capable of bleaching dilute solutions in only a few hours by shining black light of 0.7 mW cm−2. An inexpensive and simple reactor of cylindrical symmetry is described which employs a 4 W black-light tube as light source.

Dynamics and characterization of an innovative Raschig rings–TiO 2 composite photocatalyst

This study presents a novel supported photocatalyst on Raschig glass rings using polyethylene-graft-maleic anhydride (PEGMA) as a functionalized copolymer to fix TiO 2 Degussa P25 on the glass rings. The immobilized photocatalyst presented long-term stability and could be reused during the photodegradation of 4-chlorophenol (4-CP) without a loss in activity. Aqueous solution of 4-CP (0.49 mM or 35 mg C/L) at their natural pH of 5.6 and TiO 2 loaded Raschig rings showed complete decomposition of 4-CP within 5 min under irradiation with a medium pressure mercury lamp. The dependence of the 4-CP photodegradation was investigated as a function of: (a) gas atmosphere of the reaction, (b) concentration of the electron acceptor (H 2O 2), (c) initial concentration of 4-CP (d) intensity of the applied light and (e) pH of the solution. By X-ray photoelectron spectroscopy (XPS), the percentage of the elements and the binding energies (BE) was determined for the main elements on the catalyst surface. Scanning electron microscopy (SEM) determined a coating with variable a thickness of ∼100–300 nm on the glass rings. This is equivalent to a TiO 2 Degussa P25 coating of ∼10 layers thick. By atomic force microscopy (AFM) the increase in the roughness radius of TiO 2 pores was observed from 37.6 nm before use to 46.4 nm after use. This indicates that the catalyst pore diameter has increased as observed by AFM. The BET area of the sample was observed to increase from 29.4 m 2/g for the catalyst before use to 40.7 m 2/g for the TiO 2 Raschig glass rings samples after use.

Preparation and properties study of bulk Fe 75.5Ga 3P 10.5C 4B 4Si 3 metallic glass ring by copper mold casting

The bulk Fe 75.5Ga 3P 10.5C 4B 4Si 3 metallic glass ring with the outer diameter of 10 mm, the inner diameter of 6 mm and the thickness of 1 mm was successfully prepared by copper mold casting. The Curie temperature is 634 K, the glass transition temperature ( T g), the supercooled liquid region (Δ T x(= T x− T g)) and the saturation magnetization of the bulk metallic glass ring in as-made state were 634, 734, 40 K and 1.33 T. The associated activation energy of the bulk metallic glass ring was determined using differential scanning calorimetry and Kissinger's peak shift method. We hopefully can develop the bulk amorphous alloy into the application on a new type of magnetic cores.

Foam films stabilized by dodecyl maltoside. 1. Film thickness and free energy of film formation.

Foam films stabilized by a sugar-based nonionic surfactant, beta-dodecyl maltoside, are investigated. The film thickness and the film contact angle (which is formed at the transition between the film and the bulk solution) are measured as a function of NaCl concentration, surfactant concentration, and temperature. The film thickness measurements provide information about the balance of the surface forces in the film whereas the contact angle measurements provide information about the specific film interaction free energy. The use of the glass ring cell and the thin film pressure balance methods enables studies under a large variety of conditions. Thick foam films are formed at low electrolyte concentration. The film thickness decreases (respectively the absolute value of the interaction film free energy increases) with the increase of the electrolyte concentration according to the classical DLVO theory. This indicates the existence of a repulsive double layer electrostatic component of the disjoining pressure. An electrostatic double layer potential of 16 mV was calculated from the data. A decrease of the film thickness on increase of the surfactant concentration in the solution is observed. The results are interpreted on the basis of the assumption that the surface double layer potential originates in the adsorption of hydroxyl ions at the film surfaces. These ions are expelled from the surface at higher surfactant concentration.

Orange II photocatalysis on immobilised TiO2: Effect of the pH and H2O2

The discoloration and mineralisation of the azo-dye Orange II in a photoreactor using TiO2-coated glass rings as immobilised photocatalyst is reported. The variation of pH and the H2O2 addition effect were systematically investigated. The use of the response surface methodology allowed to fit the optimal values of the parameters leading to Orange II abatement. Also, a single polynomial expression modelling the reaction was obtained. The photocatalytic degradation of Orange II was followed by spectrophotometric analysis and total organic carbon (TOC) measurements.

Cytotoxicity of resin-based root canal sealer, adseal

The properties of ideal root canal sealers include the ability of sealing the total root canal system and no toxic effects to periradicular tissues. Cytotoxicity test using cell culture is a common screening method for evaluation of the biocompatibility of root canal sealers. The purpose of this study was to investigate the cytotoxic effect of newly developed resin-based sealer (Adseal 1, 2, and 3) comparing with those commercial resin-based sealers (AH26 and AH Plus), ZOE-based sealers (Tubliseal EWT, Pulp Canal Sealer EWT) and calcium hydroxide based sealer (Sealapex). An indirect contact test of cytotoxicity by agar diffusion was performed according to the international standard ISO 10993-5. L929 fibroblast cells were incubated at 37℃ in humidified 5% CO 2-containing air atmosphere. The freshly mixed test materials were inserted into glass rings of internal diameter 5 ㎜ and height 5 ㎜ placed on the agar. After the 24 hrs incubation period, the decolorization zones around the test materials were assessed using an inverted microscope with a calibrated screen. A Decolorization Index was determined for each specimen. Adseal 1, 2, and 3 did not exert any cytotoxic effects, whereas AH26, AH Plus, Tubliseal EWT, Pulp Canal Sealer EWT, and Sealapex