Glass Grid Research Articles

Vacuum measurement by carbon nanotube field emission

A vacuum measurement technology utilizing the carbon nanotube (CNT) field-emission effect has been developed and characterized. The fabricated pressure sensor is a triode type similar to a conventional ionization gauge, but has a planar structure similar to a field-emission display. Owing to the excellent field-emission characteristics of CNTs, it is possible to make a cost effective cold cathode-type ion gauge. The triode-type CNT sensor has been manufactured by a screen-printing method and by a thermal chemical-vapor deposition growth method. A modified structure with an electron filter has also been introduced and characterized so as to improve the performances, such as sensitivity and stability. A glass grid with Cr deposited by e-beam is placed on the cathode. By the voltage applied to the grid, electrons are emitted from the CNTs and they ionize gas molecules in the chamber. Two modes are available to detect the gas density in the chamber, an electron emission mode and an ionization mode. In the electron emission mode, the collector voltage is controlled to be slightly higher than the grid voltage, whereas in the ionization mode it is controlled to be lower than the grid voltage so as to obtain a large ionization ratio. The ionized molecules are gathered at the collector and the electrons return to the grid in the triode structure. The ionization ratio increases as a function of pressure in the electron emission mode. The ionization characteristics are dependent on the gas and the combination of the voltages applied to the grid and the collector. In this article, the various metrological characteristics of the developed pressure sensor utilizing CNTs are introduced.

Experimental In-Plane Behavior of Tuff Masonry Strengthened with Cementitious Matrix–Grid Composites

Tuff buildings are a significant part of the Mediterranean area and are to be preserved from a structural viewpoint especially in seismic areas. Over the past few decades, the interest in strengthening of historical tuff masonry structures has led to developing specific and noninvasive architectural and engineering strategies. In the present paper, a comprehensive experimental program on tuff masonry panels is presented; the results are intended as a contribution to the knowledge of in-plane behavior of tuff masonry strengthened with composite materials. Particularly, a cement based matrix-coated alkali resistant glass grid system (CMG) was used to strengthen tuff masonry walls; different CMG layouts were selected, and overall performances were compared with those of as-built ones. The characterization of base materials was carried out first, followed by uniaxial tests of masonry and shear tests on triplets. Finally, tuff masonry panels were subjected to diagonal compression loading under displacement control in order to measure their in-plane deformation and strength properties, including the postpeak softening regime in view of seismic applications.

Development of low pressure sensor based on carbon nanotube field emission

A newly developed low pressure detection technology using carbon nanotube (CNT) field emission effect has been designed and manufactured. The fabricated pressure sensor is of a triode type, consisting of a cathode (CNTs field emitter arrays), a grid and a collector. The principle described here is that, for a constant number of electrons available for ionization emitted from CNT arrays by a grid potential, a constant fraction of gas molecules will be ionized and the number of ions collected in a collector will be proportional to the number of gas molecules in the chamber traversed by the electrons. Due to the excellent field emission characteristics of CNT, it is possible to make a cost-effective cold cathode type ion gauge. A screen-printing method has been used to make the CNT cathode. A glass grid with Cr deposited by an e-beam has been put on the cathode with a gap of 200 µm between two electrodes. Due to the voltage applied to the grid, the electrons emitted from the CNTs ionize gas molecules in the chamber and the ionized molecules are gathered to the collector. Then, the collector voltage is made lower than the grid voltage to obtain a large ionization ratio. The current detected in the collector is proportional to the pressure in the chamber. The ionization characteristics are dependent on the gas and the voltage applied to the grid and the collector. In this paper we will show the various metrological characteristics of the home-made pressure sensor utilizing CNTs.

Ionization gauge by carbon nanotube field emission

A newly developed ionization gauge using carbon nanotube (CNT) field emission effect has been designed and manufactured. The fabricated ionization gauge is of a triode type, consisting of a cathode (carbon nanotube field emitter arrays), a grid and a collector. The principle involved here is that for a constant number of electrons available for ionization emitted from carbon nanotube arrays by the grid potential, a constant fraction of gas will be ionized and the number of ions collected in the collector will be proportional to the number of gas molecules in the chamber traversed by the electrons. Due to the excellent field emission characteristics of CNT, it is possible to make a cost effective cold cathode ionization gauge. A screen-printing method has been used to make the CNT cathode. The glass grid with Cr deposited by E-beam has been put on the cathode with a gap of 200 μm between the two electrodes. Using the voltage applied to the grid, the electrons emitted from the carbon nanotube ionize gas molecules in the chamber and the ionized molecules are gathered in the collector. At this time, the collector voltage is maintained at a lower level than that of the grid voltage to obtain a large ionization ratio. The current detected in the collector is proportional to the pressure in the chamber. The ionization characteristics are dependent on the gas and the voltage applied to the grid and collector. In this paper we have shown the various metrological characteristics of the simple pressure sensor utilizing carbon nanotube.

低平地地盤におけるジオシンセティックス技術の利用

This paper describes the use of geosynthetics in lowland area. Soft alluvial clay deposits in this area in 5m to 25m depth, where land subsidence occurs due to ground water pumping. As the countermeasure for differential settlement caused by soft deposit and land subsidence, geosynthetics have widely used in this lowland area. Eight case-studies are illustrated, in which prefabricated band-shaped drain, filter, polymer grid, and glass grid are used, and the results are discussed.

DETERMINATION AND CORRECTION OF THE ERRORS OF A PDS COORDINATE SYSTEM

ABSTRACT The PDS microdensitormeter has a high positional repeatability but low coordinate systematic accuracy because of the errors of the PDS mechanism. To improve the PDS coordinate system, a method to determine and correct the errors of PDS coordinate system with a glass grid is developed and applied to the PDS of Purple Mountain Observatory (PMO). With the method, the coordinate systematic errors of the PDS at PMO are reduced from ± 5 microns to ± 1 micron. The results of an astrometric application confirmed the effect of the method.

IVEM and SEM images of whole cells cultured on EHS matrix (Matrigel)

To investigate the interactions of cells with the extracellular matrix (ECM), rat lung fibroblasts (RLF) were cultured on an ECM extracted from EHS sarcoma to serve as an in vitro morphogenic model system. Surface features of RLF/EHS matrix interactions were viewed using the scanning electron microscope (SEM) and the intermediate voltage electron microscope (IVEM).For SEM, RLF were plated on EHS coated 13 mm glass coverslips at a density of 1 X 104/cm2. Coverslips were coated by spreading 25 μl of chilled EHS matrix (15 mg/ml) on the coverslip and incubating at 37° for 60 min. For IVEM, formvar coated gold grids were submerged in EHS matrix prior to polymerization. Controls consisted of cells grown on glass or gold grids minus ECM.

Apple; Mite Control, 1983

Abstract Two experimental chemicals, dicofol, and water were applied to apples on M-26 root stock for control of the twospotted spider mite. Chemicals were compared with each other and with water (check) to determine their effectiveness 1 day and 1 week after treatment. There were 4 replicates in a randomized block design. Each replicate consisted of three rows with four trees in each row. Two blocks with eight replicates in each block were adjacent to each other, separated by a buffer row of ‘Golden Delicious’ apples. All treatments were applied with a tractor mounted Kinkelder Model P-100 air-blast sprayer at 48 gal/acre on 12 July. Mites were counted one day before treatment (11 July), and one day (13 July) and one week (19 July) after treatment. Ten leaves were removed from each of four trees per replicate for each evaluation. Mites were removed from leaves with a Burney mite-brushing machine, placed on a circular glass grid plate, and counted under a dissecting scope. Pretreatment mite counts were used as a standard to determine the percentage of mortality in each plot 1 and 7 days after treatment.

The photoelectric astrolabe type II

The photoelectric astrolabe type I was made in China in 1971 [2]; and several| improved photoelectric astrolabes, of a second model, were constructed from 1972 to 1974. The principles and a description of the main parts of the new instruments are as follows: 1. (1) By means of a fused quartz mirror system and mercury horizon (shown in fig. 4), a telescope with a fixed glass grid, three photomultipliers with respective a. c. amplifiers and a time recorder, the astrolabe can determine the time of almucantar transit of a star without personal error. 2. (2) The evacuated Ritchey-Chrétien telescope has an aperture of 20 cm and a focal length of 2.4 m. 3. (3) As is expected, the vacuum telescope tube with horizintal entrance window is able to eliminate astronomical refraction, the dependence of refraction on the spectral class of the star and irregular refraction in the tube. Besides, the vacuum tube provides a stable environment for optical system, especially for mercury horizon. 4. (4) The astrolabe is equipped with high and low speed motors, as well as an automatic tracking mechanism in azimuth direction. 5. (5) In order to reduce the heat influence from the surroundings, the astrolabe is set on the first floor of the observing building, whereas the control console, electronic equipments and the operator are on the ground floor. 6. At Shanghai Observatory, observations have been carried out with the new instrument since Sep. 1974. The excellent results obtained will be published later on.

Investigations into the Accuracy of the NRC Monocomparator

The NRC monocomparator is described briefly, followed by a detailed discussion of the individual factors that affect comparator measurements. The major error characteristics of the comparator are evaluated from measurements made on a precise glass grid and the resulting corrections are applied to all subsequent measurements. The paper concludes by presenting the results of the tests carried out to assess the overall performance of the NRC monocomparator. It has been proven that very high accuracy can be achieved by a simple and inexpensive instrument of the NRC monocomparator type.

Effect of Chromatographic Transport in Hexylamine on Displacement of Oil by Water in Porous Media

MICHAELS, A.S., MASSACHUSETTS INSTITUTE OF TECHNOLOGY, CAMBRIDGE, MASS. MEMBER AIME STANCELL, ARNOLD, MASSACHUSETTS INSTITUTE OF TECHNOLOGY, CAMBRIDGE, MASS. PORTER, M.C., MASSACHUSETTS INSTITUTE OF TECHNOLOGY, CAMBRIDGE, MASS. Abstract Previous laboratory studies have demonstrated that the injection of small quantities of reverse wetting agents during water displacement can increase oil recovery from unconsolidated porous media. In the present investigation, an attempt has been made to determine more fully the effects of reverse wetting treatments and to clarify the mechanism by which increased oil recovery is effected Water-oil displacements were performed in beds of 140–200 mesh silica sand. Hexylamine slugs (injected after 0.25 pore volume of water through put), when adequate in size and concentration, were effective in promoting additional oil recovery. Their effectiveness increased with the quantity of amine injected. However, slugs of sufficient size and concentration to stimulate oil production at water flow rates of 34 ft/day did not do so at 4 ft/day.Visual studies in a glass grid micromodel have shown that the stimulation of oil production, via aqueous bexylamine, is a result of transient changes in the oil wettability of the pore walls. If the am in e slug is of sufficient size and concentration to induce significant changes in the adhesion-tension, large continuous oil masses will be formed. If the superficial water velocity is high enough to result in rapid desorption of the am in e, a favorable "wettability gradient" may be established across the masses; under such conditions, high oil mobility is observed, and increased oil recovery results. Introduction It is generally agreed that the efficiency of oil displacement by water in porous media is limited in part by capillary forces which cause the retention of isolated masses of oil - resulting in the so-called "irreducible minimum oil saturation". Recent estimates indicate that there are about 220 billion bbl of petroleum in United States reservoirs which are not economically recoverable with present techniques (such as water flooding). This amounts to almost five times the known recoverable reserves. It has been recognized for some time that a suitable alteration in the water-oil interfacial tension and/or the contact angle, as measured between the water-oil interface and the solid surface, should result in better displacement efficiency. Surface active agents can be used as interfacial tension depressants to accomplish this objective, but unfortunately, the additional oil recovery is seldom commensurate with the treatment cost.In contrast to interfacial tension depressants, the effect of contact angle alterations on water- oil displacements has received relatively little attention in the literature. It is known that the wettability affects the displacement process. Displacements in water-wet systems generally result in lower residual oil saturations than those in oil-wet systems. The effect of "transient" wettability alterations concurrent with the displacement process have been investigated by Wagner, Leach and coworkers, wherein it has been demonstrated that the establishment of water- wet conditions during water flooding of oil-wet, oil-saturated porous media is accompanied by significant increase in oil displacement efficiency. Michaels and Timmins studied the effects of transient contact angle alterations resulting from chromatographic transport of reverse wetting agents through unconsolidated sand. It was demonstrated that chromatographic transport of short-chain (C4 through C8) primary aliphatic amines can improve oil recovery and that the recovery increases with the quantity of amine injected (i.e., with either the amine concentration or the volume of the slug injected). Circumstantial evidence indicated that the increased displacement efficiency resulted primarily from transient changes in wettability of the porous medium.In the present investigation, additional information has been obtained on the effects of reverse wetting treatments and the mechanism by which increased oil recovery is accomplished. SPEJ P. 231^