Glass Vacuum Research Articles

Effects of fluorine on structure, structural relaxation, and absorption edge in silica glass

The effects of fluorine (F) doping on silica glass structure, structural relaxations, and vacuum ultraviolet (VUV) absorption edge were investigated by the infrared and vacuum ultraviolet absorption measurements. Linewidth of 2260 cm−1 absorption band, which is one of the good indicators of structural disorder, decreases proportionally to the fictive temperature (Tf). On the other hand, it is irrespective of F concentration. Structural relaxations are strongly stimulated by F doping. The transparency near the absorption edge depends on both F concentration and Tf. When Tf is constant, absorption edge shifts to a shorter wavelength proportionally to the F concentration. These results strongly suggest that there are two main factors that control the VUV absorption edge of F-doped silica glass; band gap widening by increasing Si–F bond and reduction of structural disorder. The latter factor is not directly caused by structural change by F doping. F enhances the structural relaxation, and it is easy to obtain samples with lower Tf, resulting in reducing structural disorder. Furthermore, a way to determine Tf of F-doped silica glass is offered.

Combined evanescent light–electrostatic atom trap of subwavelength size

A new combined evanescent light–electrostatic atom trap is proposed. Cold atoms repulse from the evanescent wave of the blue-detuned (quasi) resonant laser light formed in the total internal reflection conditions and electrostatically attract to the sharp conducting tip located close to the glass–vacuum interface. It is shown that a few milliKelvin deep and subwavelength-size traps can be formed with such an approach. These traps can be easily “scaled” by using an array of tips, which makes them a perspective object for applications in quantum computing.

Near-Field Distribution of Radial Line Slot Antenna for Surface-Wave-Coupled Plasma Generation

In plasma processing systems for large-size wafers, quick evacuation of reaction gas by making the process space narrow is urgently required to realize higher productivity and better quality for microelectronic devices. Wafers must be placed close to the antenna aperture in this case. A radial line slot antenna (RLSA) for surface-wave-coupled plasma (SWP) is a promising candidate to this end. A novel slot arrangement in the aperture, consisting of densely arrayed transverse slots, was fabricated and tested. A uniform, high-density (3×1011 cm-3) and large-area plasma at low electron temperature has already been realized in previous experiments. It dispenses with the DC magnetic fields required in ECR systems. For further development of the slot design, as well as the mechanism determination of plasma generation, in this paper we evaluate the electromagnetic near fields of SWP-RLSAs. As the first step, antennas in free space without the plasma as well as a glass vacuum window, are analyzed using a periodic array model. The predicted near-field distribution is compared with those of previous experiments and a reasonable agreement is reported.

Effect of collection, transport, processing and storage of blood specimens on the activity of lysosomal enzymes in plasma and leukocytes.

This study was designed to evaluate the effect of different conditions of collection, transport and storage on the quality of blood samples from normal individuals in terms of the activity of the enzymes ss-glucuronidase, total hexosaminidase, hexosaminidase A, arylsulfatase A and ss-galactosidase. The enzyme activities were not affected by the different materials used for collection (plastic syringes or vacuum glass tubes). In the evaluation of different heparin concentrations (10% heparin, 5% heparin, and heparinized syringe) in the syringes, it was observed that higher doses resulted in an increase of at least 1-fold in the activities of ss-galactosidase, total hexosaminidase and hexosaminidase A in leukocytes, and ss-glucuronidase in plasma. When the effects of time and means of transportation were studied, samples that had been kept at room temperature showed higher deterioration with time (72 and 96 h) before processing, and in this case it was impossible to isolate leukocytes from most samples. Comparison of heparin and acid citrate-dextrose (ACD) as anticoagulants revealed that ss-glucuronidase and hexosaminidase activities in plasma reached levels near the lower normal limits when ACD was used. In conclusion, we observed that heparin should be used as the preferable anticoagulant when measuring these lysosomal enzyme activities, and we recommend that, when transport time is more than 24 h, samples should be shipped by air in a styrofoam box containing wet ice.

Delivery of pure ozone in ultrahigh vacuum

An apparatus designed to produce and deliver pure ozone to a sample inside a metal ultrahigh vacuum apparatus is described. Ozone of 96%–97% purity is prepared in a glass vacuum system and converted to a molecular beam of known flux using an all glass doser. The storage lifetime of the O3 at Torr pressure in the glass storage vacuum system (containing a small surface area of metal) has been measured, and it is shown that the rate of O3 destruction during storage is inconsequential for hours of storage.

Determination of carbon isotopic composition of individual light hydrocarbons evolved from pyrolysis of source rocks by using GC-IRMS

The carbon isotopic composition of individual light hydrocarbons generated from source rocks that had been pyrolysed in vacuum glass tube were determined by using the GC-IRMS techniques. The results indicate that abundant CO2 in the pyrolysates has a remarkable effect on the determination of CH4δ13C. Running cryogenically with an initial temperature of −40°C can effectively eliminate the effect. In addition, it conduces to measuring the δ13C of C2+ hydrocarbons by increasing the injection volume and/or absorbing CO2 with the solution of sodium hydroxide. The above measures will help to get the carbon isotopic composition of C1–C7 components, which is of great significance for gas/source rock correlation and for study on the genesis of natural gas.

Laser Cooling and Bose-Einstein Condensation. Experimental Techniques for Bose-Einstein Condensation of Rubidium Atoms.

Experimental techniques to produce and observe a Bose-Einstein condensate of rubidium atoms are presented. The atoms are first optically cooled and trapped in an ultra-high vacuum (-10-11 torr) glass cell using a double magneto-optical trap, and then transferred to a “cloverleaf” magnetic trap. Rf-induced evaporation is performed to further cool the magnetically trapped atoms below the phase transition of Bose-Einstein condensation. The velocity distribution (inferred by absorption imaging) of the cooled atomic cloud clearly shows the expected bi-modal structure characteristic of a condensate

X-ray image analysis and ultramicroscope study of magnetic fluids used as working liquid in heat transfer experiments

Boiling characteristics of water-based and ionic magnetic fluid have been visualized using x-ray microfocus. During magnetic fluid boiling, large vapor bubbles nucleated around the vicinity of the heating surface and particles that came into contact with the heating element formed agglomerates large enough to be seen in real time x-ray images. This caused irreversible damage to the magnetic fluid heated to temperatures higher than 373 K. However, application of the magnetic field showed improvements in heat transfer characteristics and ionic magnetic fluid performed better over the water-based magnetic fluid. Ultramicroscope observations of ionic and water-based magnetic fluids heated only up to 353 K in vacuum for ten consecutive days and were found stable. However, ionic magnetic fluid heated in a vacuum glass cell at 373 K burst suggesting the accumulation of noncondense gas.

Films obtained by plasma polymerization of pyrrole

This work presents the synthesis by plasma and characterization by IR, SEM, thermogravimetry and electric conductivity of polypyrrole films, both undoped and doped in-situ with iodine. The synthesis was carried out in a vacuum glass reactor with reaction times from 60 to 300min. The plasma was produced by electric glow discharges with a resistive coupling mechanism at 13.5MHz. The films were obtained with thickness between 2.7–13.1μm at a rate of 48.2nm/min and conductivity between 10−12–10−9 S/cm. The thickness of the films doped with iodine was between 4.9–19.8μm at a rate of 64.4nm/min and conductivity between 10−9–10−3 S/cm. The electric conductivity of polypyrrole was studied as a function of its reaction time and the environmental moisture. Electron microscopy analysis and thermal decomposition were also studied to observe the morphology and the thermal stability in the films. The electric properties showed a strong dependence on the moisture, in which two regions were clearly observed. The first region predominated up to 70% of relative humidity. In this region moisture had no significant influence on the conductivity. In the second region, at more than 70% of relative humidity, moisture increased the conductivity by several orders of magnitude.

Stability of amphotericin B in an extemporaneously prepared i.v. fat emulsion.

The stability of amphotericin B in an extemporaneously prepared i.v. fat emulsion was studied. Admixtures of amphotericin B 0.5, 1, and 2 mg/mL were prepared by adding 10, 20, and 40 mL of amphotericin B 5 mg/mL to 90, 80, and 60 mL, respectively, of 20% fat emulsion. The admixtures were stored in glass vacuum containers at 20-25 degrees C and exposed to fluorescent light, 20-25 degrees C and protected from light, or 4-8 degrees C and protected from light. A sample was withdrawn from each container at 0, 4, 12, and 24 hours and at 2, 4, 7, and 15 days for analysis of amphotericin B concentration by high-performance liquid chromatography and for visual evaluations; these samples were immediately frozen until analyzed. A sample was withdrawn from one container of amphotericin B 1 and 2 mg/mL for each storage condition at 0, 7, and 15 days for immediate determination of particle-size distribution with a fluorescinated-antibody cell sorter. Amphotericin B 0.5 mg/mL in 20% fat emulsion was stable for one week under all the storage conditions. Amphotericin B in the 1- and 2-mg/mL admixtures was stable for up to four days at 20-25 degrees C exposed to fluorescent light, and for up to one week at 20-25 degrees C protected from light and at 4-8 degrees C protected from light. There was no visible evidence of incompatibility. There were no substantial changes in particle-size distribution for the 1-mg/mL admixtures; appreciable changes were detected for the 2-mg/mL admixtures. Amphotericin B 1 and 2 mg/mL was stable in 20% fat emulsion for four days at 20-25 degrees C exposed to fluorescent light and for seven days at 20-25 degrees C protected from light or at 4-8 degrees C; amphotericin B 0.5 mg/mL was stable in 20% fat emulsion for seven days under the three storage conditions.

Ideality of water vapour and its adsorption on the glass surfaces of a conventional glass vacuum apparatus at 295 K between 0 and 10 Torr

The properties of water vapour have been investigated quantitatively between 0 and 10 Torr and at ambient temperature (295 K). Provided a satisfactory correction for surface adsorption is made, the deviation from ideal gas behaviour is not detectable within the accuracy of the corrected pressures (±3%). This is consistent with theoretical modelling calculations and also with experiments made at higher temperatures when they are extrapolated to ambient temperature. There was considerable adsorption of water vapour onto the glass of the apparatus which had previously been in constant use, up to ca. 20 monolayers and taking place in two distinct rate processes that were completed in ca. 5 and ca. 30 min. Very much less adsorption occurred on new Pyrex glass (ca. 1 monolayer). It was also shown that the measured equilibrium vapour pressures in the range 0–10 Torr were directly proportional (±8%) to the amount of water admitted.Both results are important in confirming the validity of the vacuum apparatus measurements when used to study rates of water release such as the dehydrations of solids which depend on this relationship. However as a consequence of water vapour adsorption, apparent yields were less by 32% than the values calculated using the ideal gas equation. Yield determinations therefore cannot be based on pressure and apparatus volume but must be obtained by direct calibration.

Stability of melatonin in aqueous solution

Melatonin solutions are frequently used in human, animal, and in vitro research. Generally, fresh solutions are prepared, for fear of instability of melatonin in solution. We tested the high-performance liquid chromatography (HPLC) stability of melatonin in aqueous solutions stored room temperature, 4 degrees C, and -70 degrees C for up to 6 months. Solutions were prepared in a laminar flow hood using sterile technique, directly into sterile, pyrogen-free glass vacuum vials for storage. Different concentrations were tested (1.0-113.0 micrograms/ml). There was no loss of potency as assessed by HPLC, and the preparations remained sterile and pyrogen-free. We conclude that melatonin solutions may be prepared in batches maintained in sterile, pyrogen-free vials at 4 degrees C or at -70 degrees C until use within 6 months. This method will save on research time used for preparation of fresh solutions and will reduce the number of dose validation tests for each new experiment.

The production of a flow of laser-induced aerosol in carbon disulphide vapour

The properties of a laser-induced aerosol formed in carbon disulphide vapour are discussed. It is shown that it is possible to transport such an aerosol through a glass vacuum system by introducing a pressure gradient across the production cell.

Effect of pressure-induced stress on the design of shaped-glass evacuated solar collectors

Shaped-glass evacuated solar collectors have the lower portion of the tubular glass vacuum envelope shaped and inside surface mirrored to concentrate sunlight onto an absorber tube in the vacuum. Upon evacuation, stresses are set up in the glass. The maximum surface tensile stress possible in glass, while keeping the probability of fracture small, is of the order of 7 MPa. This low maximum tensile stress places severe limitations on the amount the lower portion of the cross section of a cylindrical glass evacuated solar collector can deviate from circular to provide the concentration. Equations are developed for determining stress in the glass. Results of stress calculations leading to parameters for collector design are presented.

Potential Sampling Error: Trace Metal Adsorption on Vacuum Porous Cup Samplers

AbstractThe adsorption of trace metals on ceramic, polytetrafluoroethylene (PTFE or Teflon), fritted glass, and stainless steel vacuum pore‐water samplers and silica packing material used to seat samplers was evaluated with respect to potential sampling errors. A solution containing radio‐labeled Cd+2, Co+2, Cr+3, and Zn+2 and a mix of ions typically found in soil solutions was used to assess specific absorption of inorganics to porous cups of samplers and to silica. Four sets of samplers were cleaned with acid or water and then treated with a solution containing trace metals at concentrations near primary or secondary drinking‐water standards or one order of magnitude lower for 2 or 7 d. After treatment, the samplers were rinsed with 10 or 30 pore volumes (PV) of simulated soil solution and radioassayed. Duplicate silica samples were treated with the high‐trace‐metal solution adjusted to a pH of 4, 6, or 8 for a 5‐d period, rinsed with simulated soil solution, and radioassayed. Adsorption was greatest on samplers treated with high trace‐meal concentrations and samplers cleaned with water. Desorption of both Co and Zn occurred with the 30‐PV soil solution rinse for all sampler types except stainless steel. The general pattern of metal adsorption on samplers was ceramic > stainless steel >> fritted glass = PTFE. The general order that trace metal adsorbed to samplers and silica was Zn >> Co > Cr > Cd. At pH values of 6 to 8, trace‐metal adsorption on silica (mass of adsorbent/mass of adsorbate) was similar to or greater than that observed for ceramic samplers. This study shows that adsorption‐desorption processes can cause sampling error when analysis of trace metals at microgram‐per‐liter concentration levels is necessary.

Blood viscometer with vacuum glass suction tube and needle.

A new type of viscometer for measuring human blood viscosity is made by using a vacuum glass tube and a capillary needle. This new viscometer needs a volume of only about 5 × 10–6–8 × 10–6 m3 of blood. Simple handling, quick measurement and accurate results in a wide shear rate range are its superior features. Additionally, the whole measuring set with the viscometer is easy to use and to carry, and it is not expensive.By using various standard-viscosity Newtonian liquids, it is confirmed experimentally that this viscometer is sufficiently accurate in the range of less than about 10–2 Pa·s. The viscosity of fresh human blood collected in a hospital is measured by the new viscometer and it is confirmed that the viscosity value obtained is reasonable by comparing it with that by a traditional measuring method. Further, it is shown that the new viscometer can measure the viscosities of other liquids which have complex properties.

AMS carbon-14 dating of ice: progress and future prospects

The “sublimation technique” for the recovery of carbon dioxide from ice samples and the conversion of the recovered carbon dioxide into graphite for AMS dating will be described, together with its use in some applications. The technique involves placing the ice sample in a carefully degassed glass vacuum system, “cleaning” the ice by removing the outer few millimeters by sublimation, then subliming the ice completely using infrared lamps as an energy source. The gases evolved from the subliming ice first pass through a trap at − 80°C to remove water. The remaining gases pass through a trap immersed in liquid nitrogen where the carbon dioxide is recovered. The gases which pass the liquid nitrogen trap are trapped on molecular sieve held at liquid nitrogen temperatures. In our apparatus we can sublime a 3 kg sample of ice core in 18 hours. We measure the quantity of water sublimed, the amount of air and carbon dioxide recovered and the 14C content of the carbon dioxide. From these data we can calculate the altitude of the ice sheet and the CO 2 concentration of the atmosphere at the time given by our 14C date. We have run ice samples as small as 1 kg in the “bomb pulse” zone where the activity is high and the spatial resolution in the ice core is of concern. The future prospects for the technique look promising and we ultimately hope to be able to date polar ice cores back in time as far as is achieved by AMS dating of more conventional materials.

Quasiequilibrium determination of high-T c superconductor transition temperatures

A fast and inexpensive method for making accurate determinations of transition temperatures above 77 K in superconducting oxides is presented. The technique is based upon cooling in liquid nitrogen, then warming the sample in the vapors above the liquid level inside a standard glass or stainless steel vacuum bottle. Proper sample support and placement of the thermocouple, key elements in this technique, are discussed. Once pads have been placed on the sample, Tc can be determined, to an accuracy of ±1 K, within 15 min. Due to its speed, accuracy, and low cost, this technique is well suited for application in an advanced undergraduate laboratory experiment.

Line broadening studies in low energy plasma focus

Optical emission spectroscopic studies were carried out to characterise the plasma leading to the estimation of two plasma parameters, electron density and temperature. These experiments were conducted on a 2 kJ plasma device which is equipped with squirrel cage electrode configuration enclosed in a glass vacuum chamber filled with hydrogen at a pressure of 5 mbar. Spectral emissions obtained from each flash were photographed in the region of 4000–6000 A using one metre Czerny-Turner spectrograph cum monochromator. Detailed examination of the observed features showed that theH β andH λ lines of hydrogen showed significant broadening of the order of 35 A FWHM which is due to Stark effect expected in high density plasmas. Further several atomic lines of Cu and Zn from the electrode material (brass) showed broadening which was due to quadratic Stark effect. A comparative study of the broadening of lines obtained in DC arc, hollow cathode and plasma focus was made. Electron density from Stark broadened hydrogen lines and quadratic Stark Coefficient C4 for the CuI and ZnI lines were evaluated. The excitation temperature was determined from the line intensity ratio method using CuI lines.

ガラス密封セルによるガリウム三重点の実現

A sealed glass cell was developed for the precise realization of the triple point of gallium.The triple point of gallium, one of the most important fixed points for platinum resistance thermometry at room temperatures, has been realized by plastic cells. It is because of the increase in volume of gallium on solidification, and the plastic cell is not suitable for a leakage-free triple-point cell. Those problems are solved by adopting a vacuum glass cell with a teflon container.The triple-point temperatures of gallium realized by the developed cell are found to be constant for about two months within ±0.04mK. The average temperatures measured by two standard platinum resistance thermometers are 29.77367°C and 29.77361°C by the representation of the International Practical Temperature Scale of 1968. The differences of the triple-point temperatures between the present sealed glass cell and the conventional plastic cell are also discussed.