Quartz Cylinder Research Articles

Gaseous Electrical Discharge-Induced Degradation of Organic Compound in Wastewater: UV Irradiation and Ozonation Effect

AbstractThis study investigated the degradation of an organic compound (an azo dye, Acid Red 4) in a synthetic wastewater by using dielectric barrier discharge (DBD) tube comprised of a hollow quartz cylinder and a coaxial copper rod. The DBD tube was immersed in the wastewater that was connected to the ground electrode. When AC high voltage was applied to the copper electrode, the electrical discharge occurred inside the quartz cylinder to produce ultraviolet (UV) light and reactive species such as ozone. The photocatalytic degradation of the organic compound with the UV emitted from the DBD tube was carried out in the presence of aluminum meshes coated with titanium oxide. The system further comprised a gas diffuser that distributed the ozone-containing gas produced in the DBD tube into the wastewater, such that the organic compound were degraded by reacting with ozone. The contributions of the photocatalysis and the ozonation to the degradation were separately assessed, and then combined effect on the degradation was examined. The results clearly revealed that the present system capable of degrading the organic compound in two ways (DBD-induced photocatalysis and ozonation) was very effective for the treatment of the wastewater.

Degradation of Organic Contaminant by Using Dielectric Barrier Discharge Reactor Immersed in Wastewater

Dielectric barrier discharge (DBD) was applied to the degradation of an organic contaminant in wastewater. When electrical discharge occurs, the DBD reactor produces oxidative species (ozone) and emits ultraviolet light. For the purpose of using both ozone and ultraviolet light for the degradation of the organic contaminant, the DBD reactor was immersed in the wastewater. The DBD reactor for this paper consisted of a quartz cylinder and a coaxial ceramic tube inside of which a steel rod was placed. High voltage was connected to the steel rod inside of the ceramic tube, and the wastewater was grounded. In this case, the wastewater acted not only as an electrode but also as the cooling medium for the DBD reactor. The performance of this DBD reactor system was evaluated with a simulated wastewater formed with distilled water and an azo dye (Acid Red 27) as the organic contaminant. The experimental results showed that this system was able to completely degrade the organic contaminant within 20 min at typical experimental condition. The energy requirement for the degradation of the organic contaminant was found to be 0.654 kJ/mg

Complete band gaps in two-dimensional phononic crystal slabs

The propagation of acoustic waves in a phononic crystal slab consisting of piezoelectric inclusions placed periodically in an isotropic host material is analyzed. Numerical examples are obtained for a square lattice of quartz cylinders embedded in an epoxy matrix. It is found that several complete band gaps with a variable bandwidth exist for elastic waves of any polarization and incidence. In addition to the filling fraction, it is found that a key parameter for the existence and the width of these complete band gaps is the ratio of the slab thickness, d, to the lattice period, a. Especially, we have explored how these absolute band gaps close up as the parameter d/a increases. Significantly, it is observed that the band gaps of a phononic crystal slab are distinct from those of bulk acoustic waves propagating in the plane of an infinite two-dimensional phononic crystal with the same composition. The band gaps of the slab are strongly affected by the presence of cutoff frequency modes that cannot be excited in infinite media.

Pityriacitrin – a potent UV filter produced by Malassezia furfur and its effect on human skin microflora

In Malassezia furfur, tryptophan as the main nitrogen source induces production of the potent ultraviolet-absorbing indole compound pityriacitrin. An in vitro study about the effects of pityriacitrin on other human skin microorganisms is presented, with special focus on Candida albicans and staphylococci in which its toxicity and UV-protective capacity were investigated. Candida albicans was irradiated with UVB light either in the presence or in the absence of pityriacitrin (11 mmol) and the growth rate was determined. A UVB dose of 1 J cm(-2) caused death of the fungi without pityriacitrin, whereas those in the presence of pityriacitrin showed almost unaffected growth. A diffusion test in staphylococci revealed no antibiotic effects of pityriacitrin. For testing of an ultraviolet-protective effect, staphylococci were either inoculated and irradiated in a plate model for visual assessment of growth or inoculated and irradiated in square quartz cylinders for quantitative measurement of cell density, each time in the absence or presence of pityriacitrin. Cell density of the bacterial suspensions exhibited nearly no influence of pityriacitrin on growth rates, while again a UV-protective effect was observed. In summary, pityriacitrin has an ultraviolet-protective effect on Candida albicans and staphylococci with no toxicity in the range tested.

The identification of carving techniques on Chinese jade

Abstract In a study of the technology used in China to carve jade, a tradition predating the 5th millennium BC, eight artefacts, dated stylistically to the Neolithic Hongshan and Liangzhu cultures (4th–3rd millennia BC), the Western and Eastern Zhou dynasties (11th–3rd centuries BC) and the Ming and Qing dynasties (14th–20th centuries AD) were examined. Initially, the materials of the artefacts were analysed non-destructively using Raman microscopy to confirm that they are nephrite jade. A survey using binocular microscopy showed that traces of the original tool marks survive on most of the artefacts. Following the approach and experience developed to investigate the engraving of Near Eastern quartz cylinder seals, scanning electron microscopy has been used to examine moulds of the tool marks. Sets of criteria have been established which permit six techniques of carving to be recognised. These have been interpreted as drilling, wheel-cutting, sawing, flexible string sawing, riffling and point or blade abrasion. The results suggest that study of a broader selection of artefacts should allow a chronology for the development of jade carving to be established. In addition, the results have demonstrated that original tool marks may have been lost on heavily weathered surfaces and that new tool marks may have been introduced during cleaning or restoration.

The identification of carving techniques on Chinese jade

In a study of the technology used in China to carve jade, a tradition predating the 5th millennium BC, eight artefacts, dated stylistically to the Neolithic Hongshan and Liangzhu cultures (4th–3rd millennia BC), the Western and Eastern Zhou dynasties (11th–3rd centuries BC) and the Ming and Qing dynasties (14th–20th centuries AD) were examined. Initially, the materials of the artefacts were analysed non-destructively using Raman microscopy to confirm that they are nephrite jade. A survey using binocular microscopy showed that traces of the original tool marks survive on most of the artefacts. Following the approach and experience developed to investigate the engraving of Near Eastern quartz cylinder seals, scanning electron microscopy has been used to examine moulds of the tool marks. Sets of criteria have been established which permit six techniques of carving to be recognised. These have been interpreted as drilling, wheel-cutting, sawing, flexible string sawing, riffling and point or blade abrasion. The results suggest that study of a broader selection of artefacts should allow a chronology for the development of jade carving to be established. In addition, the results have demonstrated that original tool marks may have been lost on heavily weathered surfaces and that new tool marks may have been introduced during cleaning or restoration.

Orientation, morphology and magnetostriction of a heat-treated 〈1 1 0〉 oriented TbDyFe alloy

〈1 1 0〉 oriented rods of a TbDyFe magnetostrictive alloy have been successfully prepared by zone melting unidirectional solidification. A homogenization annealing for 4 h or 48 h at 1000 °C has been carried out in a quartz cylinder under Ar 2 protection after pumping to 2×10 −3 Pa. The preferred orientation, morphologies and magnetostriction of the TbDyFe rods with directional solidification or annealing have been investigated. The 〈1 1 0〉 preferred orientation remains unchanged after annealing. The net-shaped pseudo-eutectic rare earth phase becomes discontinued and spheroidal after annealing for 4 h and shows spheroidal shape without the net-shaped morphology after annealing for 48 h. The magnetostriction slightly decreased after annealing without pre-stress, but increased drastically with pre-stress. An obvious magnetostriction jump effect was observed in the annealed samples. A satisfactory magnetostrictive property of 1970×10 −6 was obtained under 15 MPa pre-stress after 4 h heat treatment without a further improvement for 48 h annealing, which indicates that the heat treatment for 4 h at 1000 °C is proper for the present 〈1 1 0〉 oriented TbDyFe alloy.

Measurement of liquid fuel film distribution on the cylinder liner of a sparkignition engine using the laser-induced fluorescence technique

Two-dimensional visualization of a liquid fuel film on a quartz cylinder liner wasperformed in a spark ignition engine rig. The visualization method was based onlaser-induced fluorescence and total reflection. Using a quartz cylinder linerand a special quartz prism, only the liquid fuel on the cylinder liner wasvisualized. The calibration method was developed to quantify the fuel filmthickness on the quartz cylinder liner. The calibration result showed that thefluorescence intensity increased linearly with the fuel film thickness on thequartz cylinder liner. Using this method, the wall-wetting fuel mass on thecylinder liner was quantitatively measured for different valve lifts andinjected fuel masses in the test rig. The maximum fuel film thicknesson the quartz cylinder liner was about 45 µmfor a valve lift of 8 mm and an injection duration of 10 ms.

Hot wall epitaxial growth of highly ordered organic epilayers

Hot wall epitaxy works close to thermodynamic equilibrium and is therefore most applicable for materials with Van der Waals binding character. The hot wall epitaxy system can be described as semiclosed growth reactor, consisting of a vertically mounted quartz cylinder, which is heated by three separately controllable ovens, and is closed on top by the substrate. The first oven heats the source material and controls the growth rate. The second heats the hot wall between source and substrate, which guaranties the closed character of the reactor and helps to avoid loss of valuable material. The third oven controls the substrate temperature and allows to influence the growth process on the substrate surface. We achieved crystalline perfection for C 60 layers on mica substrates and fabricated Ba-doped n-type layers with mobilities of 6000 cm 2/V s at room temperature.

The Combustion of Solid Wastes as Studied in a Fluidized Bed

An electrically heated bed of silica sand fiuidized by air and at 900°C has been used to incinerate a wide variety of solids. These included vegetables, meat, plastics, wood, rubber, car-tyres and a Polish coal, as well as two commercially produced waste fuels. Combustion of such solids always involves two, almost sequential, stages: the first is when any moisture and volatile materials are expelled; during the second, the solid remaining from the first stage (i.e. char) is burnt. Some materials float on the hot fiuidized sand, occasionally when they are not expected to float; other materials sink, often unexpectedly Likewise some particles fragment, some produce a cloud of soot, but others do not. Devolatilization times ( t d ) for the bituminous coal varied as M 2/3 , the initial mass of the particle raised to the power 2/3. This is attributed to the rate-controlling step being provision of the enthalpy of thermal decomposition by heat conduction from a particle's exterior to a shrinking core of virgin coal. A simple model for such devolatilization is presented. The char's burn-out time also depended on M 2/3 , because control is by mass transfer of O 2 from the bed to a particle's exterior. By contrast a particle of fibre fuel (mainly compressed paper) has t d approximately proportional to M , but dRDF (densified refuse-derived fuel—actually domestic refuse, extruded after being screened) has t d independent of M . The char burn-out times for these two commercial fuels (with large volatile contents) were much less than for the coal and independent of M . Car tyres and rubbers produced large quantities of soot and CO. Plastics produced no char; they evaporated and rapidly produced clouds of hydrocarbon vapour. Such a laboratory-scale fiuidized bed, held in a transparent quartz cylinder, is excellent for observing a particle whilst it burns, as well as measuring gaseous emissions, the temperature of a particle whilst it burns and also the rates of devolatilization and char burn-out.

Hot-wall-epitaxy - the method of choice for the growth of highly ordered organic epilayers

Hot Wall Epitaxy works close to thermodynamic equilibrium and is therefore most applicable for materials with Van der Waals binding character. The Hot Wall Epitaxy system can be described as semiclosed growth reactor, consisting of a vertically mounted quartz cylinder, which is heated by three separately controllable ovens, and is closed on top by the substrate. The first oven heats the source material and controls the growth rate. The second heats the hot wall between source and substrate, which guaranties the closed character of the reactor and helps to avoid loss of valuable material. The third oven controls the substrate temperature and allows to influence the growth process on the substrate surface. We achieved crystalline perfection for C 60 layers on mica substrates and fabricated Ba-doped n-type layers with mobilities of 6000 cm 2 /Vs at room temperature.

The effect of experiment geometry on the mechanism and rate of dissolution of quartz in basanite at 0.5 GPa and 1350 °C

Mineral dissolution is an important factor in many magmatic processes such as melting, assimilation and magma mixing. Since it is not possible to determine dissolution rates or mechanisms from natural samples, experimental measurements are very useful. However, the geometry of the crystal–melt system can have a large effect on the measured rate, depending on whether the contaminated melt formed during dissolution is gravitationally stable or unstable. This study examines the effects of the crystal–melt geometry on the dissolution rate and mechanism. The experiments were performed using basanite melt and cylinders and spheres prepared from a single crystal of natural quartz. All of the experiments were performed in the piston cylinder apparatus at 0.5 GPa and 1350 °C. Four crystal–melt geometries were used: (1) quartz cylinders on top of a column of melt; (2) quartz cylinders beneath a column of basanite melt; (3) quartz cylinders in the middle of column of melt; (4) quartz spheres on top of a column of basanite melt. These geometries allow an examination of non-convective, convective and mixed non-convective/convective dissolution. Sphere experiments were included, as this has been the most commonly used geometry in previous experimental studies. In all of the experiments quartz dissolves directly into the basanite without formation of cristobalite or tridymite. Quartz on top of a column of melt dissolves at a rate almost proportional to the square root of time and forms a silica-rich compositional boundary layer that is gravitationally stable. All of the samples show well-defined compositional gradients in the boundary layer; however, the melt at the interface varies in composition with time and plots of concentration as a function of distance normalized to time show that the diffusion rate of SiO2 increases with time. These data suggest that the rate-controlling step during quartz dissolution is interface reaction rather than cation diffusion. Quartz on the bottom of a column of basanite dissolves much more quickly than in the quartz-on-top experiments and the dissolution rate is linear, due to the periodic gravitational instability and resultant convection of the boundary layer. Even though interface kinetics are the rate-controlling step in quartz dissolution, convection causes an increase in dissolution rate because it replenishes the boundary layer with new, silica-undersaturated melt, which dissolves the quartz more quickly than the contaminated melt. These data suggest that the interface reaction rate is controlled by the degree of undersaturation of the solvent melt in the dissolving component. Both quartz-in-middle and quartz sphere experiments dissolve at a rate intermediate between the two extremes and both show a power law rate. Both dissolve by a combination of convective and non-convective dissolution but the sphere experiments are affected by an additional factor. During the experiment the sphere can sink through the capsule causing forced convection which adds another complication to the interpretation of the dissolution rate data. The results of this study indicate that the choice of experiment geometry plays a major role in determining the observed dissolution rate. Mineral spheres, which have been widely used in the past, are not ideal for dissolution studies. Instead, dissolution rates and mechanisms are best determined in the absence of convection. These experiments have an additional advantage in that for diffusion-controlled dissolution, they allow determination of cation diffusivity.

The introduction of the lapidary engraving wheel in Mesopotamia

Scanning electron microscopy provides an insight into the lapidary techniques of the ancient Near East. Engraved features on quartz cylinder seals have been compared to those produced experimentally, leading to a radical reassessment of the date for the introduction of the engraving wheel.

Development of a Lean Premixed Low-Swirl Burner for Low NOx Practical Applications

Laboratory experiments have been performed to evaluate the performance of a premixed low-swirl burner (LSB) in configurations that simulate commercial heating appliances. Laser diagnostics were used to investigate changes in flame stabilization mechanism, flowfield, and flame stability when the LSB flame was confined within quartz cylinders of various diameters and end constrictions. The LSB adapted well to enclosures without generating (lame oscillations and the stabilization mechanism remained unchanged. The feasibility of using the LSB as a low NO x commercial burner has also been verified in a laboratory test station that simulates the operation of a water heater. It was determined that the LSB can generate NO x emissions < 10 ppm (at 3% O2) without significant effect on the thermal efficiency of the conventional system. Our study has demonstrated that the lean premixed LSB has commercial potential for use as a simple economical and versatile burner for many low emission gas appliances.

A Fast-Response High Spatial Resolution Total Temperature Probe Using a Pulsed Heating Technique

This paper discusses the operation of a fast-response total temperature probe based on transient thin film heat flux gage technology. The probe utilizes two thin film gages located close to the stagnation point of a hemispherically blunted fused quartz cylinder. Development of the present total temperature probe was motivated by the need for a fast-response device with a high spatial resolution. The diameter of the probe was 2.8 mm and the two films were separated by a distance of less than 1 mm. Measurement of the flow total temperature requires the films to operate at different temperatures. In the present work, the temperature difference was generated using a current pulse (approximately 70 mA with a duration of around 1 s) to heat one of the thin film resistance gages. With this technique, temperature differences between the hot and cold films of around 120 K were achieved. The interpretation of the transient surface temperature measurements is discussed, and the validity and utility of the technique are demonstrated with reference to total temperature and convective heat transfer coefficient measurements in a compressible free jet. The results demonstrate that accurate total temperature and convective heat transfer coefficient measurements with high spatial and temporal resolution can be obtained with the present device.

METHODS OF ENGRAVING MESOPOTAMIAN CYLINDER SEALS: EXPERIMENTAL CONFIRMATION*

Previous observations of the intaglios on quartz cylinder seals from Western Asia suggested that they had been engraved by one or more of four basic techniques, that is, micro‐chipping, filing, drilling and wheel‐cutting. In this paper we test our earlier observations and interpretations experimentally. Examination and comparison of experimentally engraved features with the seal intaglios was made directly with a binocular microscope and also by examination of impressions with a scanning electron microscope. Successful replication was achieved using tools of flint, chalcedony, copper, bronze and iron together with quartz and emery abrasives.

Double-Mirror Peripheral Vitrectomy Lens

Many surgeons use prism lenses to see the periphery of the fundus during vitrectomy; however, chromatic aberrations in higher-power prismatic lenses cause blurring of the peripheral image. For better visualization of the periphery of the fundus, we developed a new contact lens, the double-mirror peripheral vitrectomy lens. The new lens is a quartz cylinder with two mirrors, and it provides a crisp, clear, upright image of much more of the peripheral fundus than is visible through conventional prism lenses. The new lens also provides a wider area of view than conventional prism lenses.

Low-field aspects of magnetic-flux dynamics of inhomogeneous superconductors

Material is presented showing that certain inhomogeneous superconducting samples, including both low-T c and high-T c compounds, respond to weak changes in applied magnetic field in a way which in suitable designs makes them usable as simple quantum interferometers. Usually, S uperconducting QU antum I nterference D evices (SQUIDs) are considered to consist of a superconducting loop with one or two well-defined Josephson junctions. Here we demonstrate that an anodized niobium tube, which consists of an inhomogeneous niobium thin film covering a quartz cylinder has a typical SQUID-like response, when operated as a radio-frequency (RF) SQUID. The physical background appears to be that very small changes in applied magnetic field can induce macroscopic changes in the flux configuration in an inhomogeneous superconductor, where the critical current density is a rapidly varying function of both position and field. The effect is directly demonstrated by comparing the shielding properties of high-quality epitaxial films and low critical current density inhomogeneous films of the high temperature superconductor YBa 2Cu 3O 7−x. The shielding properties have been measured by using a simple set-up including an RF-SQUID made out of ceramic YBa 2Cu 3O 7−x, the sample, and a small field coil, operated in a well-shielded environment.

Surface roughness effects on cylindrical grazing incidence x-ray optics for transition radiation

Quartz and nickel cylinders were used as grazing incidence x-ray optics for transition radiation (TR) from Al, Ti, and Cu foil stacks. The cylinders were used to direct the otherwise diverging TR to a small spot (1 mm diameter), with measured fluxes of up to 330 W/A cm2 averaged over the spot area. Computer simulations were performed and compared to the measured results. It was found that including surface roughness effects in the form of a Debye–Waller reduction factor on the reflectivity was necessary to get good agreement between the simulations and experimental results in certain cases, but not in others. A simple heuristic model which can be used to determine when roughness effects are important is presented. Use of this model in conjunction with the computer simulations accurately predicts the measured results, and further suggests the use of different optic materials at different x-ray wavelengths.

Observation of the focusing of x-ray transition radiation using cylindrical optics

We have measured the profile of x rays generated by a transition radiator and focused by simple cylindrical optics. Soft x rays with photon energies between 1 and 4 keV were generated by a 93-MeV electron beam striking a stack of eight foils of 3.5-μm-thick mylar. These x rays were emitted in an annular cone and were collected by a quartz cylinder which focused the x rays to a 0.5-mm-diam spot at a distance of 1.35 m from the transition radiator.