Quartz Cylinder Research Articles

Tunable Elliptical Cylinders for Rotational Mechanical Studies of Single DNA Molecules.

The angular optical trap (AOT) is a powerful technique for measuring the DNA topology and rotational mechanics of fundamental biological processes. Realizing the full potential of the AOT requires rapid torsional control of these processes. However, existing AOT quartz cylinders are limited in their ability to meet the high rotation rate requirement while minimizing laser-induced photodamage. In this work, we present a novel trapping particle design to meet this challenge by creating small metamaterial elliptical cylinders with tunable trapping force and torque properties. The optical torque of these cylinders arises from their shape anisotropy, with their optical properties tuned via multilayered SiO 2 and Si 3 N 4 deposition. We demonstrate that these cylinders can be rotated at about 3 times the rate of quartz cylinders without slippage while enhancing the torque measurement resolution during DNA torsional elasticity studies. This approach opens new opportunities for previously inaccessible rotational studies of DNA processing.

Optical torque calculations and measurements for DNA torsional studies

The angular optical trap (AOT) is a powerful instrument for measuring the torsional and rotational properties of a biological molecule. Thus far, AOT studies of DNA torsional mechanics have been carried out using a high numerical aperture oil-immersion objective, which permits strong trapping but inevitably introduces spherical aberrations due to the glass-aqueous interface. However, the impact of these aberrations on torque measurements is not fully understood experimentally, partly due to a lack of theoretical guidance. Here, we present a numerical platform based on the finite element method to calculate forces and torques on a trapped quartz cylinder. We have also developed a new experimental method to accurately determine the shift in the trapping position due to the spherical aberrations by using a DNA molecule as a distance ruler. We found that the calculated and measured focal shift ratios are in good agreement. We further determined how the angular trap stiffness depends on the trap height and the cylinder displacement from the trap center and found full agreement between predictions and measurements. As a further verification of the methodology, we showed that DNA torsional properties, which are intrinsic to DNA, could be determined robustly under different trap heights and cylinder displacements. Thus, this work has laid both a theoretical and experimental framework that can be readily extended to investigate the trapping forces and torques exerted on particles with arbitrary shapes and optical properties.

Effect of flammable gases produced from spontaneous smoldering combustion of coal on methane explosion in coal mines

Methane released from underground coal mines forms a highly explosive mixture when combined with air, which can be aggravated by the flammable gases produced from spontaneous smoldering combustion of coal in the mines. In this work, the flammable gases from coal smoldering combustion under conditions close to those in a coal mine are experimentally characterized by a self-designed quartz cylinder. The flammable gases mainly consist of CO at the initial stage of the smoldering combustion while they are composed of CO, H2 and CH4 at temperatures above 300 °C. Then, their effect on explosion of methane-air mixtures is investigated via experiments and simulations. The explosion characteristics and flame propagation of the typical in-mine methane-air mixtures enriched by the smoldering combustion products are studied using a 20 L spherical vessel reactor and a high-speed camera. Among all the methane-air mixtures tested, the addition of the smoldering combustion products to fuel-lean methane-air mixtures most remarkably enhance methane explosion. In the simulations, a sensitivity analysis is conducted to identify the dominant elementary reactions during the explosion process. As the share of the smoldering combustion products added to the methane-air mixture increases, the dominant elementary reaction for methane consumption is found to eventually shift to enhance methane explosion by generating a high concentration of OH and O. The results of this work not only improve the understanding of methane explosion but also benefit the development of new methane explosion suppression technology for coal-mining industry.

The solubility of platinum in magmatic brines: Insights into the mobility of PGE in ore-forming environments

Several field-based studies have proposed that late-stage magmatic aqueous brines may be responsible for the transportation and redistribution of platinum-group elements (PGE) in mafic–ultramafic igneous systems. We experimentally studied the solubility of Pt in high-temperature aqueous brines as a function of oxygen fugacity (ƒO2), temperature (T), pH and total chloride concentration (Cltotal) in a S-free system. Experiments were conducted at 800–1000 °C and 200 MPa in an externally-heated rapid-quench Molybdenum-Hafnium Carbide (MHC) pressure vessel assembly. We employed the synthetic fluid inclusion (SFI) technique to trap and sample pre-equilibrated, high-salinity brines in quartz cylinders subjected to in situ fracturing during experimental run conditions. Platinum solubility was observed to have a positive correlation with ƒO2, temperature, fluid acidity and Cltotal (salinity). A log Pt versus log ƒO2 diagram derives a weighted-error linear regression slope (m) = 0.48 ± 0.04 which demonstrates that Pt is present in the 2+ oxidation state over the studied ƒO2 range. At relatively oxidizing conditions, 1.44 log units above the Ni-NiO oxygen buffer (NNO+1.44), aqueous brines (containing 63 NaCl eq. wt.%) with a mildly acidic fluid composition (pH = 6.03) can dissolve up to ∼100 µg/g Pt at 900 °C and 200 MPa. Aqueous brines with identical fluid compositions yield a solubility of 4–13 µg/g Pt under more reducing conditions (NNO–0.41 to NNO–1.42). Thermodynamic model calculations suggest that both PtCl2 and PtCl3− are the dominant Pt(II)-chloride complexes which facilitate the transport of Pt in high-temperature aqueous vapors and brines. In fluid compositions with Cltotal >32 m (mol/kg H2O), PtCl3− complex is expected to be the dominant Pt species. In natural mafic–ultramafic systems, high-salinity, orthomagmatic aqueous brines may be important transporting agents if such magmatic fluids can participate in the dissolution of Pt-enriched base-metal sulfides or react with discrete insoluble Pt phases imposing a relatively high activity of Pt (i.e., Pt3Fe). Furthermore, precipitation of Pt from aqueous brines is promoted by a decrease in ƒO2, temperature, acidity and Cltotal.

The solubility of gold and palladium in magmatic brines: Implications for PGE enrichment in mafic-ultramafic and porphyry environments

We performed experiments to determine the solubility of Au and Pd in magmatic aqueous fluids as a function of oxygen fugacity (ƒO2), temperature (T), pH and total chloride concentration (Cltotal). Experiments were conducted at 800–1000 °C and 200 MPa in an externally-heated rapid-quench Molybdenum-Hafnium Carbide (MHC) cold-seal pressure vessel assembly. We employed a synthetic fluid inclusion (SFI) technique to entrap equilibrated, hydrothermal fluids in response to in situ fracturing of quartz cylinders at experimental run conditions. The solubility of Au and Pd both have positive relationships with ƒO2, temperature, acidity and chlorinity. Concentrated aqueous brines containing 63 wt.% NaCl can dissolve wt.% levels of Au (∼1.2 wt.%) and Pd (∼1.7 wt.%) at metal saturation in relatively oxidized conditions, 1.44 log units above the Ni-NiO oxygen buffer (NNO+1.44), and mildly acidic pH at 900 °C and 200 MPa. Thermodynamic modeling of experimental results suggests that Au is mainly transported as AuCl(aq) at high pH and low Cltotal conditions, whereas HAuCl2(aq) and potentially AuCl2(aq)− predominates at low pH and high Cltotal conditions. Results from thermodynamic modeling also suggest Pd is mobilized in significant contributions by both PdCl2(aq) and PdCl3(aq)− with the latter gaining predominance in response to increasing Cltotal. Calculated fluid/melt partition coefficients for Au and Pd in low-density, magmatic vapors at 1000 °C and 200 MPa suggest that Pd may experience fractionation from Au in porphyry Au-Cu (±Pd, Pt) systems due to the restricted compatibility of Pd in the fluid phase (requiring strongly acidic and substantially high ƒO2 conditions). Moreover, high-density, concentrated aqueous brines facilitate the compatibility of Pd in the fluid phase which may be important with respect to the formation of platinum-group element (PGE)-enriched horizons in layered mafic intrusions (e.g., J-M Reef, Stillwater Complex, U.S.A.). The potential for magmatic, near-neutral pH, high-salinity brines to dissolve significant amounts of Pd as Pd(II)-chloride complexes (∼400 to ∼900 µg/g) well below the NNO buffer suggests that such fluids may be responsible for late-stage hydrothermal remobilization of Pd within mafic-ultramafic igneous environments (e.g., Cu-Ni-PGE footwall deposits and low-sulfide PGE deposits in the Sudbury Igneous Complex, Canada).

The pollination of Habenaria rhodocheila (Orchidaceae) in South China: When butterflies take sides.

Habenaria is one of the largest terrestrial genera in the family Orchidaceae. Most field studies on Habenaria species with greenish–white and nocturnal scented flowers are pollinated by nocturnal hawkmoths and settling moths. However, H. rhodocheila presents reddish flowers lacking a detectable scent and fails to fit the moth pollination syndrome. We investigated the pollinators, breeding system, and functional traits of H. rhodocheila in South China and found that two diurnal swallowtail butterflies Papilio helenus and Papilio nephelus (Papilionidae) were the effective pollinators. When butterflies foraged for nectar in the spur, the pollinia became attached between the palpi. A triangular projected median rostellar lobe was found at the entrance (sinus) of the spur of H. rhodocheila. This lobe divided the spur opening into two entrances forcing butterflies to enter their proboscides through the left or right side. When the projection of median rostellar lobe was removed, the site of pollinium attachment changed to the eyes of the butterflies, leading to a higher rate of pollinium removal but lower rate of pollinium deposition. Our quartz glass cylinder choice experiment suggested that visual rather than olfactory cues provided the major stimuli for butterflies to locate these flowers. Hand pollination experiments suggested this species was self‐compatible but pollinator‐dependent. However, the proportion of seeds with large embryos produced in self‐pollinated fruits was significantly lower than in cross‐pollinated fruits, indicating a significant inbreeding depression. Unlike many other orchid species, fruit set was higher than rates of pollinium removal, indicating a high level of pollination efficiency in a species with friable pollinia. Shifts from moth to butterfly pollination in the genus Habenaria parallel other orchid lineages providing insights into the potential for pollinator‐mediated floral trait selection.

Dispersion properties of artifi cial topological insulators based on an infi nite double-periodic array of elliptical quartz elements

Subject and Purpose. Special features of all-dielectric electromagnetic analogues of topological insulators (TI) in the microwave range are considered, aiming at studying the influence of geometrical and constitutive parameters of TI elements on the dispersion properties of topological insulators based on a two-dimensional double-periodic array of dielectric elements. Methods and Methodology. The evaluation of dispersion properties and electromagnetic field spatial distribution patterns for topological insulators is performed using numerical simulation programs. Results. The electromagnetic analogue of a topological insulator based on a double-periodic array of elliptical quartz cylinders has been considered. By numerical simulation, it has been demonstrated that the electromagnetic properties of the structure are controllable by changing the quartz uniaxial anisotropy direction without any changes in other parameters. A combined topological insulator made up of two adjoining ones differing in shapes of their unit cells has been considered with the numerical demonstration that frequencies of surface states are controllable by choosing the quartz uniaxial anisotropy direction. It has been shown that it is at the interface of two different in shape unit cells that the electromagnetic field concentration at a surface state frequency takes place. Conclusion. A possibility has been demonstrated of controlling microwave electromagnetic properties of topological insulators by changing their geometric parameters and permittivity of the constituents. From a practical point of view, topological insulators can be used as components of microwave transmission lines and devices featuring very small propagation loss.

Experimental study of fragmentation of fused quartz cylinders under quasi-static loading with the fractoluminescence recording

Quasi-static tests for uniaxial compression of fused silica cylinders have been carried out. The destruction process was accompanied by fractoluminescence, which is typical for quartz. Fractoluminescence was recorded by two methods: a high-speed camera, which, in addition to luminescence, recorded the entire process of destruction of the sample, and using a photomultiplier with a high time resolution to analyze the dynamics of the fragmentation process. In most experiments, two stages of destruction were recorded. Each of which was accompanied by intense fractoluminescence. A statistical analysis of the fragments mass (size) distribution and of the intervals between fractoluminescence pulses has been carried out.

Analysis of the electrical field in viscosity sensors with torsionally vibrating quartz cylinders

The potential and electric fields in viscosity sensors with torsionally vibrating quartz cylinders are calculated for various sensor geometries by means of analytical solution techniques and a numerical integration method for the Laplace equation. Sensor geometries with electrodes on the surface of the cylinder and offset at a distance from the cylinder are investigated for different angular extensions of the electrodes and dielectric constants of the fluid. It is found that the electric field is more favorable for the excitation of the torsional vibration when the electrodes are located at a distance from the cylinder surface rather than on the cylinder. When the electrodes are on the surface of the cylinder, the direction of the piezoelectrically active component of the electric field is reversed in certain regions near the edges of the cylinder, which hinders the excitation of the torsional vibration. As a result of this analysis, a novel viscosity sensor with line conductor electrodes was developed and validated in our laboratory. Furthermore, this article provides a brief review of the available literature on torsionally vibrating quartz cylinder viscometers.

High‐Pressure High‐Temperature Transparent Fixed‐Bed Reactor for Operando Gas‐Liquid Reaction Follow‐up

AbstractA 3‐MPa, 350 °C fixed‐bed reactor was designed to follow‐up gas‐liquid‐solid reactions on a millimetric size heterogeneous catalyst with Raman spectroscopy. The transparent reactor is a quartz cylinder enclosed in a Joule effect heated stainless‐steel tube. A methodology to determine how to focus the microscope for liquid and solid phase characterization is presented. The setup was validated by performing diesel hydrodesulfurization on a CoMo/alumina extrudate catalyst with a conversion very close to expected values along with the acquisition of Raman spectra of the solid catalyst showing an evolution of the catalyst phase during sulfidation.

Plasmonic roller lithography

Photo roller lithography systems can generate patterns continuously over large areas by employing flexible photomasks on rotating quartz cylinders. In comparison, plasmonic lithography systems can reach deep sub-wavelength resolution utilizing evanescent waves carrying high spatial frequency components. In this work, we demonstrate a plasmonic roller system by integrating a quartz mechanical roller with a specially designed photomask based on plasmonic waveguide lithography. Deep sub-wavelength uniform patterns with high aspect ratios were printed continuously over a moving substrate. The plasmonic roller system may find practical applications in the large-scale production of electronic and photonic devices in a cost-effective way.

Evaluation of oxygen species during E–H transition in inductively coupled RF plasmas: combination of experimental results with global model

Inductively coupled RF plasmas (ICP) in oxygen at low pressure have been intensively studied as a molecular and electronegative model system in the last funding period of the Collaborative Research Centre 24 “Fundamentals of Complex Plasmas”. The ICP configuration consists of a planar coil inside a quartz cylinder as dielectric barrier which is immersed in a large stainless steel vacuum chamber. In particular, the E–H mode transition has been investigated, combining experimental results from comprehensive plasma diagnostics as input for analytical rate equation calculation of a volume averaged global model. The averaged density was determined for electrons, negative ions O−, molecular oxygen ground state O2(X3 Σg−) and singlet metastable state O2(a1 ∆g) from line-integrated measurements using 160 GHz Gaussian beam microwave interferometry coupled with laser photodetachment experiment and VUV absorption spectroscopy, respectively. Taking into account the relevant elementary processes and rate coefficients from literature together with the measured temperatures and averaged density of electrons, O2(X3 Σg−) and O2(a1 ∆g) the steady state density was calculated for O(3P), O2(b1 Σg+), O(1D), O(1S), O3, O−, O2−, and O3−, respectively. The averaged density of negative ions O− from the rate equation calculation is compared with the measured one. The normalized source and loss rates are discussed for O(3P), O2(b1 Σg+) and O−.

Destruction of Aqueous Phase Organic Pollutants Using Ultraviolet Light-Emitting Diodes and Photocatalysis

The photocatalytic degradation of dyes (Allura Red AC and Brilliant Blue FCF) in water using ultraviolet light-emitting diodes (UV-LED) and an immobilized titanium dioxide (TiO2) as a photocatalyst was investigated using a novel bench-top Teflon® reactor. This reactor has been uniquely designed to contain low-powered UV-LEDs combined with TiO2 immobilized substrates. A sol-gel method was used to anneal TiO2 to three different substrates: standard microscope quartz slides, quartz cylinders, and borosilicate beads. Scanning electron microscopy (SEM), Raman spectroscopy, and mass comparisons techniques were performed for TiO2 characterization. High-resolution images confirmed the presence and morphology of TiO2 on the substrates. These analyses demonstrated the TiO2 coating was uniform and predominantly had the anatase crystalline phase structure. The slide had the largest individual TiO2 surface area of 0.187 mg cm−2. Results indicated the size, shape, packing, and stirring properties were factors that determine overall photocatalytic properties and degradation inside the reactor. The adjusted rate constants for an ideal completely mixed batch reactor (CMBR) were 1.69 * 10−3, 5.39 * 10−3, and 4.46 * 10−3 min−1 for the slides, beads, and cylinders, respectively. Beads were the best-performing substrate as determined by the greatest degradation rate for the model organic compound, Allura Red AC. The beads and cylinders showed 58 and 51% degradation of Allura Red AC, respectively. Actinometry experiments revealed cylinders had the largest fluence rate of 0.0782 J·L−1 s−1. Optimization of the sol-gel application method and reactor operating parameters was performed to maximize the degradation rate and the overall degradation of Allura Red AC. Electric energy per order (EEO) was calculated and optimized at 9.20, 10.5, and 12.7 kWh·m−3 order−1 for the glass beads, cylinders, and slides, respectively.

Reactor power monitoring using Cherenkov radiation transmitted through a small-bore metallic tube

The use of a small-bore highly reflective metallic tube has been demonstrated at a pool-type nuclear reactor for transmitting Cherenkov radiation emitted from a quartz cylinder placed near the reactor core. The study revealed the promising prospect of using a metallic tube to remotely make localized measurements in order to independently monitor reactor power using Cherenkov light generated in the water pool or inside an attached radiator. This study confirmed qualitatively and quantitatively that commercially available stainless steel tubes with highly reflective inner surfaces can adequately transport Cherenkov light, produced in the proximity of a SLOWPOKE-2 reactor core operated at 20 kW, with acceptable transmission losses over significant distances. It was demonstrated that this Cherenkov-based instrument has a fast response, high fidelity, and the Cherenkov-induced output current varies linearly with the reactor power. Scans in the orthogonal directions showed the possibility of using the Cherenkov-based instrument for 3-D mapping of the general gamma field around the reactor core. Analytical and numerical models were developed and validated by experiments to predict the transmission efficiency of light in the highly polished small-bore light guides. This paper provides details of calculations and experimental validation under laboratory conditions and at a pool-type SLOWPOKE-2 reactor.

High-Temperature Corrosion of Stainless Steels and Ni Alloys During Combustion of Urea–Ammonium Nitrate (UAN) Fuel

This paper reports on corrosion behavior of different materials under combustion of a nitrogen-based fuel: aqueous solution of ammonium nitrate and urea (UAN). Tested materials include stainless steels 316, 310 and nickel alloys: 600, 601, 617, 800H and RA333. The results were derived under conditions close to those in practical continuous combustion applications. The coupons were positioned in quartz cylinders at temperature 520 ± 10 °C and pressure 10 MPa in the effluent gases. The corrosion of the 316 SS fuel injection tube was tested as a function of the stages that occurred along the tube, namely: heating, ignition, and combustion. Microstructure, chemical composition, depth profile and thickness of the formed oxide scales were studied. High corrosion resistance was found for 310 SS, nickel alloys 601 and RA 333. The heaviest corrosion attack of 316 inlet tube (both general and intergranular) was observed in the area where the exothermic combustion process began.

Analysis of fluid hammer occurrence with phase change and column separation due to fast valve opening by means of flow visualization

This paper presents an experimental investigation on the fluid hammer phenomenon generated when filling a pipe line under vacuum conditions with a closed end. This physical configuration, although it can be found in many piping configurations, it is of special interest in propulsion systems of satellites during priming operation. The fluid hammer taking place here not only leads to high pressure peaks in the fluid but also to low pressures, which can cause cavitation, gas desorption and liquid column separation.The study is carried out on a facility allowing flow visualization, which is achieved by replacing the pipe closed end by a quartz cylinder drilled with the same tube inner diameter. In this way, the flow can be recorded with high speed imaging at this location. The visualizations confirm that the pressure evolution is accompanied by a complex multiphase flow pattern. First of all, a foamy mixture of non-condensable gas, vapor and liquid droplets precedes the liquid front arrival at the bottom end. During the fluid hammer compression wave, the vapor condensates and the non-condensable gas gets compressed. Afterwards, the arrival of an expansion wave induces the movement of the liquid column backwards, with the corresponding pressure drop that generates a gaseous bubble referred to as column separation. Finally, the collapse of this bubble is at the origin of the next pressure rise.

Experimental determination of the retention time of reduced temperature of gas–vapor mixture in trace of water droplets moving in counterflow of combustion products

We have experimentally studied temporal variation of the temperature of gas–vapor mixture in the trace of water droplets moving in the counterflow of high-temperature combustion products. The initial gas temperature was within 500–950 K. The water droplet radius in the aerosol flow varied from 40 to 400 μm. The motion of water droplets in the counterflow of combustion products in a 1-m-high hollow quartz cylinder with an internal diameter of 20 cm was visualized by optical flow imaging techniques (interferometric particle imaging, shadow photography, particle tracking velocimetry, and particle image velocimetry) with the aid of a cross-correlation complex setup. The scale of temperature decrease in the mixture of combustion products and water droplets was determined for a pulsed (within 1 s) and continuous supply of aerosol with various droplet sizes. Retention times of reduced temperature (relative to the initial level) in trace of water droplets (aerosol temperature trace) are determined. A hypothesis concerning factors responsible for the variation of temperature in the trace of droplets moving in the counterflow of combustion products is experimentally verified.

Effects of Arrangement of UV Light-Emitting Diodes on the Inactivation Efficiency of Microorganisms in Water.

Ultraviolet light-emitting diodes (UV-LEDs) offer high flexibility in the reactor design for water disinfection. To specify the key design factors affecting the performance of a reactor, we examined how the arrangement of UV-LEDs in a cylindrical reactor affects the inactivation efficiency of Escherichia coli and coliphage Qβ. A ring-shaped UV-LED apparatus, composed of two units containing ten 285-nm UV-LEDs each, were attached to a quartz cylinder, and microbial suspensions flowed through the cylinder for single pass at altered flow rates. The distance between the two units, L, was altered to examine its effects on inactivation efficiencies. Over 4 log inactivation of E.coli was achieved at 800mLmin-1 regardless of the L values, suggesting that the apparatus has a high potential to disinfect water. The inactivation at L=20mm was significantly higher than that at L=0 in all cases tested (ANOVA, P<0.05), while this was not true when L was extended to 40 and 60 mm. Therefore, a separate arrangement of UV-LEDs at a certain distance can improve the efficiency, and the distance matters to enhance the performance. This study involves a design concept on how to arrange UV-LEDs in a water disinfection apparatus.

X-BAND APERTURE ANTENNA WITH HYBRID DIELECTRIC INSERTS

An X-band radiator as an open-ended waveguide with a hybrid dielectric insert is proposed. The insert is in the form of a parallelepiped, which fills the entire cross section of the waveguide and constitutes a Teflon matrix with local inhomogeneities in the form of dielectric cylinders with a different permittivity. The design allows for forming various near-field distributions and, hence, the radiator performance by means of definite combinations of the local inhomogeneities can be modified. A number of configurations in the location of air and quartz cylinders are investigated. The calculated and experimental results are in good agreement. The proposed approach to the near-field formation of the aperture antenna is promising, because the variety of possible configurations in the location of local inhomogeneities with different permittivity provides new opportunities in terms of designing both single radiators and antenna arrays.

Extraction characteristics of a low-energy ion beam system with a remote plasma chamber.

Low-energy argon beams were extracted from a dual-chamber ion source system. The first chamber is a quartz cylinder where dense inductively coupled plasmas were produced using 13.56 MHz radio frequency (rf) power. The discharge was driven into an adjacent chamber which acts as a reservoir for ion beam extraction using a dual-electrode extractor configuration. Extraction of ions from the second chamber with energies in the 100 eV range was achieved while minimizing fluctuations induced by the rf signal. A custom-built retarding potential analyzer was used to analyze the effectiveness of ion beam transport using the remote plasma chamber. Well-defined beams were extracted between 60 and 100 V extraction potentials at 50-100 W rf powers. An increase in rf power resulted in an increase in average ion energy, increase in ion current density while the energy spread remains constant.