Porous Glass Plates Research Articles

Laser induced structural changes in porous glass due to hot and cold compaction

A comparison is presented of the structural changes occurring in porous glass during laser-induced hot and cold compaction. The changes occurring in modified regions of different compaction processes when a porous-glass plate with a micro-region is sintered in a furnace are also compared.

Energy Conversion from Thermal Energy to Spectral-Controlled Radiation for Thermophotovoltaics using Porous Quartz Glass Media

The characteristics of energy conversion from thermal energy into near-infrared radiant energy in a superadiabatic system with stacked porous quartz glass plates were investigated using one dimensional numerical simulation to optimize the parameters of the quartz media. 56% of the input thermal energy could be converted into radiant energy in the wavelength range of less than 2.2 µm using a number of thin porous quartz glass plates with low porosity. In addition, the efficiency of energy conversion could be expected to be 63% when a non-gray foam ceramics was used as the selective emitter. Radiant energy can be converted into electric power by spectral control using low bandgap photovoltaic cells. The superadiabatic system was demonstrated to be effective for a thermophotovoltaic generation system.

Comparing Unsaturated Colloid Transport through Columns with Differing Sampling Systems

Methodological difficulties of colloid sampling in the vadose zone are limiting our knowledge regarding the relevance of colloid transport for groundwater contamination. We compared the colloid sampling efficiency of five different lysimeters in a column experiment (9 cm length, 8 cm diameter) using 59Fe‐labeled goethite: polyester membranes with a pore diameter of (i) 1.2 μm and (ii) 10 μm, (iii) porous glass plates with 16‐μm pore diameter, (iv) wick samplers, and (v) zero‐tension lysimeters. Four replications of each lysimeter type were tested with concentrations of 0.1 and 10 mg L−1 goethite. The irrigation rate was 58 mm h−1, which caused an average transport velocity of 240 mm h−1 Compared with NO3−, a tendency of accelerated transport of goethite in the sand columns was observed. The mean recovery of 59Fe for all lysimeters was 30.7 ± 6.7% for the small and 3.4 ± 3.5% for the large colloid input concentration. For the small goethite concentration, no differences between lysimeter systems were detected. In contrast, the lysimeters performed differently at large concentrations: zero‐tension and 10‐μm membrane lysimeters showed the largest (9.1 and 6.8%), wick lysimeters the smallest colloid recovery (0.7%), which was related to trapping of colloids in the wick. We conclude that membranes of 10‐μm pore size and zero‐tension lysimeters are superior for colloid sampling, but the results of the latter may be biased toward an overestimation of colloid transport because of water saturation at the lysimeter–soil interface.

Development and optimization of a lab-on-a-chip device for the measurement of trace nitrogen dioxide gas in the atmosphere

We propose the use of lab-on-a-chip technology for measuring gaseous chemical pollutants, and describe the development of a microchip for the detection of nitrogen dioxide (NO2) in air. A microchip fabricated from quartz glass has been developed for handling the following three functions, gas absorption, chemical reaction and fluorescence detection. Channels constructed in the microchip were covered with porous glass plates, allowing nitrogen dioxide to penetrate into the triethanolamine (TEA) flowing within the microchannel beneath. The nitrogen dioxide was then mixed with TEA and reacted with a suitable fluorescence reagent in the chemical reaction chamber in the microchip. The reacted solution was then allowed to flow into the fluorescence detection area to be excited by an ultraviolet light-emitting diode (UV-LED), and the fluorescence was detected using a photomultiplier tube (PMT). The reaction time, reagent concentration, pH, flow rate and other measurement conditions were optimised for analysis of nitrogen dioxide in air. Preliminary studies with standardized test solutions revealed quantitative measurements of nitrite ion (NO2-), which corresponded to atmospheric nitrogen dioxide in the range of 10-80 ppbv.

Silica-supported biomimetic membranes.

The hybridization of lipid membranes with inorganic silica-based framework results in mechanically stable biomembrane mimics. This account describes three types of silica-based biomimetic membranes. As the first example, a Langmuir monolayer of dialkylalkoxysilane was polymerized and immobilized onto a porous glass plate. Permeability through the monolayer-immobilized glass was regulated by phase transition of the immobilized monolayer. In the second example, spherical vesicles covalently attached to a silica cover layer (Cerasome) were prepared. The Cerasome was stable enough to be assembled into layer-by-layer films without destruction of its vesicular structure. This material could be an example of the multicellular assembly. Mesoporous silica films densely filling peptide assemblies (Proteosilica) are introduced as the third example. The Proteosilica was synthesized as a transparent film through template sol-gel reaction using amphiphilic peptides.

Preparation of a Translucent, Conductive, Porous Nanocomposite

A translucent, conductive, porous nanocomposite was designed and prepared by depositing SnO2 on the inner surfaces of the pores of a porous glass plate and on its outer surface using a chemical vapor deposition method. The porous nanocomposite almost maintained its large surface area and pore volume because the pores remained open after they were deposited with SnO2. Conductivity between the two outer surfaces of the nanocomposite plate was confirmed for the first time.

Surface Sintering of Porous Glass Plates under Laser Radiation

The kinetics of surface sintering of flat plates of the 96SiO2 · 3.8B2O3 · 0.2Na2O (mol %) porous glass exposed to CO2 laser radiation is investigated under conditions when either the irradiation time is varied at a constant radiation power density or the radiation power density is varied at a constant irradiation time. It is established that the irradiation time is the most appropriate controlled parameter in the process of sintering. A decrease in the thickness of the porous layer sintered on the plate surface is accompanied by an increase in the radii of curvature of the interfaces of this layer.

Disjoining Pressure vs Thickness Isotherms of Thin Emulsion Films Stabilized by Proteins

In the present paper, we report measurements of the disjoining pressure vs thickness isotherms of emulsion films stabilized by proteins. A novel variant of the Mysels−Bergeron thin liquid film setup was constructed and further employed in the investigation of foam and emulsions films. The films are formed in a porous glass plate immersed in the corresponding oil phase. The disjoining pressure is directly measured by means of a pressure transducer, and the thickness is determined via light interferometry. The disjoining pressure vs thickness isotherms show different features in respect to the stabilizing protein. When the films are stabilized by bovine serum albumin (BSA) and β-lactoglobulin (BLG), a steric-like interaction comes into play being differently pronounced in the two cases. In contrast, the films stabilized with β-casein exhibit classical Derjaguin−Landau−Verwey−Overbeek (DLVO) behavior. The disjoining pressure was converted to force adopting the Derjaguin approximation, and the result is compa...

FTIR Studies of the Reaction of Gaseous NO with HNO3 on Porous Glass: Implications for Conversion of HNO3 to Photochemically Active NOx in the Atmosphere

The heterogeneous reaction of HNO3 adsorbed on porous glass surfaces with gaseous NO was investigated using transmission Fourier transform infrared (FTIR) spectroscopy at room temperature. The amount of adsorbed HNO3 varied from (4.2−110) × 1017 molecules of HNO3 on a 6 cm2 porous glass plate whose BET surface area was measured to be 28.5 ± 0.6 m2 (2σ). The initial concentration of gaseous NO varied from (0.2−6) × 1017 molecules cm-3. A rapid release of NO2 into the gas phase was observed to occur simultaneously with a decrease in adsorbed HNO3. A trace amount of gaseous HONO was also formed. The measured yields of NO2 and loss of HNO3 and NO are consistent with the net reaction 2HNO3 + NO → 3NO2 + H2O which is due to HNO3 + NO → HONO + NO2, followed by HONO + HNO3 → 2NO2 + H2O and/or 2 × (HNO3 + NO → HONO + NO2) followed by 2HONO → NO + NO2 + H2O. Both 15NO2 and 14NO2 were observed as reaction products when 15NO and 14HNO3 were used as the reagent species, indicating that some of the NO2 produced originates in HNO3. The measured decay rates for adsorbed HNO3 were first order in NO. The rates initially increase with increasing HNO3 but tend to plateau, consistent with complete surface coverage and the formation of multilayers of HNO3, perhaps in part in the pores. Extrapolation of these results to atmospheric NO levels suggests that this heterogeneous reaction may serve as a mechanism to regenerate photochemically active forms of NOx and nitrous acid from HNO3 in the atmosphere.

Multiple scattering of light in porous glass.

Two kinds of multiple-light-scattering measurements were performed for porous glass plates of several pore radii from 0.15 to 0.50 \ensuremath{\mu}m. One is the measurement of the angular dependence of the backscattered light intensity, and the other is the measurement of the temporal profile of light pulses transmitted through the sample. The measured curves were in very good agreement with the theoretical ones based on the diffusion model in uniform scattering media, and no features specific to the local geometry of porous glass were found. The pore radius dependence of the transport mean free path ${\mathit{l}}^{\mathrm{*}}$ could be explained well by a Mie scattering calculation based on the independent scattering approximation. The transport velocity of light in the porous glasses in the measured range of the pore size calculated from the obtained values of ${\mathit{l}}^{\mathrm{*}}$ and the diffusion constants was around 60% of the phase velocity in the bulk glass.

Investigation of collecting conditions for determination of arsine in working environment of semiconductor manufacturing process.

Collecting conditions using various absorbing solutions were investigated for the determination of arsine in the working environment of semiconductor plants. Recommended procedure is as follows: the sample gas is collected by passing the gas through an impinger containing 20cm3 of 2.0w/v% potassium permanganate-0.6v/v% sulfuric acid solution at the flow rate of 1000cm3 min-1 for 30min. The impinger comprises a bent-type gas dispersion tube sintered with a porous glass plate (20mm diameter, pore size 40100μm). Following the sampling, 10cm3 of 2.5w/v% hydrogcn peroxide-0.6v/v% sulfuric acid solution is added to the absorbing solution in order to prevent the precipitation of manganese dioxide or to dissolve the precipitate already formed. Arsenic in the solution is then determined by flow injection/hydride generation-atomic absorption spectrometry according to the literature. The collection efficiency for arsine with 10 replicate determinations was 95±1% at the level of 31μgm-3. Arsine in the working environment inthe range of 8.7420 μgm-3 can be determined with 30 dm3 of the sample gas using this procedure.

Chemotaxis of bacteria in glass capillary arrays. Escherichia coli, motility, microchannel plate, and light scattering

Random and directed motility of bacterial populations were assayed by monitoring the flux of bacteria through a microchannel plate (a porous glass plate comprising a fused array of capillary tubes) separating two identical stirred chambers. Cells, washed free of growth medium by a new filtration method, were added to one chamber at a low density. Their number in the other chamber was determined from the amount of light scattered from a beam of a laser diode and recorded on a strip chart. Diffusion coefficients were computed from fluxes observed in the absence of chemical gradients, and chemotaxis drift velocities were computed from fluxes observed in their presence. Cells migrated through tubes of diam 10 microns more rapidly than through tubes of diam 50 microns, suggesting that the straight segments of their tracks were aligned with the axes of the smaller tubes. Mutants that are motile but nonchemotactic could be selected because they move through the microchannel plate in the face of an adverse gradient. Weak chemotactic responses were assessed from ratios of fluxes observed in paired experiments in which the sign of the gradient of attractant was reversed. Studies were made of wild-type Escherichia coli and mutants that are nonmotile, tumblely, smooth-swimming, aspartate-blind, or defective in methylation and demethylation. Chemotaxis drift velocities for the latter mutants (cheRcheB) were quite small.

Permeability controllable membranes. 11. Polymerized monolayers of single-, double-, and triple-chain silane amphiphiles and permeation control through the monolayer-immobilized porous glass plate in an aqueous solution

Polymerisation d'une couche monomoleculaire du distearyl silane a l'interface air-eau de la sous-phase acide et transfert du polymere sur une plaque de verre poreux auquel il est lie par les atomes de silicium. La permeation de NaCl et d'une sonde fluorescente a travers le verre est controlee par la transition de phase de la couche monomoleculaire

Porous glass plate immobilized with the adsorbed monolayer of dialkylsilane amphiphiles. Permeation control by a phase transition of the adsorbed monolayer

Des couches monomoleculaires adsorbees d'amphiphiles dialkylsilanes, sont immobilisees dans une plaque de verre poreux (diametre moyen des pores: 10 nm). La vitesse de permeation d'une solution de NaCl, a travers la plaque poreuse contenant les amphiphiles est inferieure a celle de la plaque de verre poreux non traite: elle peut etre controlee par l'etat des couches monomoleculaires immobilisees dans les pores

Permeation control by a phase transition of the dialkylsilane monolayer immobilized on a porous glass plate

The polymeric monolayer of dialkylsilane amphiphiles was covalently bonded onto a porous glass plate by the Langmuir–Blodgett technique, and the permeability of NaCl could be controlled by the phase transition of the immobilized monolayer.

The Electronic Absorption Spectra of UV Irradiated Anilines Adsorbed on Porous Vycor Glass

Abstract Cation radicals of aniline and its derivatives were formed on porous Vycor glass plates by UV-irradiation. One of the absorption bands appearing in the visible region is assigned to the transition to the first excited state of the cation radical by comparison with the reported photoelectron spectrum. The charge resonance band of the dimer cation was also observed in the near infrared region in most cases.

Radiationless transitions in the excited aromatics—oxygen systems adsorbed on porous glass at low temperature

The efficiency of fluorescence quenching by oxygen has been extensively studied for a number of aromatic hydrocarbons adsorbed on porous Vycor glass plates immersed in liquid oxygen at 77 K. Quite unexpected is the fact that the fluorescences of most aromatic hydrocarbons were detectably strong even in the presence of liquid oxygen. It has been found that the intrinsic rate constants for the oxygen-enhanced radiationless transitions in the excited aromatics—oxygen pairs are reasonably explained by taking account of the Franck—Condon factors, the location of the second triplet states, and the symmetries of the related electronic states. It has been concluded that in some aromatics, the radiationless transition from the excited singlet state to the second triplet state (S 1 → T 2) is possible, leading to high intrinsic quenching rate constants by large Franck—Condon factors. In other aromatics, the major process is S 1 → T 1 and the rate constants in these cases depend on the symmetry of the S 1 and T 1 electronic wave functions. A relatively strong phosphorescence of benzophenone has also been observed in the presence of liquid oxygen. The results of the phosphorescence quenching efficiencies for benzophenone and naphthalene by oxygen are also discussed.

Diffusion and Color Development of the Polyphenylmethane Indicators Adsorbed on Porous Glass Plates

シクロヘキサン溶媒中で,多孔性ガラスプレートに吸着したテトラベース,ロイコマラカイトグリーソあるいはロイコクリスタルバイオレットの発色現象について分光学的研究を行なった。プレートとしては,原プレートならびにそれに酸化アルミニウムや酸化ニヅケルをそれぞれ沈積したプレートの3種を用いた。吸着した指示薬分子のごく少ない一部が表面と反応し,それぞれのカルボニウムイオソに変化して発色することを確かめた。発色量は時間とともに増加する。発色速度を定量的に検討した結果,つぎのようなモデルに基づく半無限一次元の拡散律速として考えうることが明らかになった。すなわち指示薬の吸着は最初短時間のうちに終了し,プレート外表面近くに一定濃度のうすい初期吸着層が形成する。吸着した指示薬はその後プレート内部に徐々に拡散していき,拡散した分子のうち一定の割合だけが発色にあずかるというモデルである。40,50および60℃ におけるすべて実験値はこのモデルから導かれた理論式m2=k2tによく一致した。ここにmは発色量,tは時間,kは見かけの速度定数であり,k=kao1D1/2/hπ1/2である。Kは表面反応率,ao1は吸着量aoにほぼ等しく,Dは拡散定数,hは初期吸着層の厚さである。各定数の数値的評価からも拡散モデルの妥当性を実証し得た。各種のプレートと各種の指示薬とを組み合わせた実験から,それぞれの発色速度,活性化エネルギーを比較検討し,表面の酸化性および拡散機構などについて考察した。分光学的方法はこのような表面反応や拡散現象を究明するための有効な手段であるといいうる。