scholarly journals PHOTOCHEMICAL SEPARATION OF MERCURY ISOTOPES: II. THE REACTION OF Hg2026(3P1) ATOMS, PHOTOEXCITED IN NATURAL MERCURY VAPOR, WITH WATER VAPOR AND OTHER HgO-FORMING SUBSTRATES

1959 ◽  
Vol 37 (1) ◽  
pp. 35-42 ◽  
Author(s):  
R. Pertel ◽  
H. E. Gunning
Keyword(s):  
Nitrous Oxide ◽  
Water Vapor ◽  
Systematic Study ◽  
Room Temperature ◽  
Marked Effect ◽  
Mercury Vapor ◽  
Flow Conditions ◽  
Simple Method ◽  
Factors Influencing ◽  
Enrichment Process

An investigation has been made of the reaction of Hg202(3P1) atoms, photoexcited in natural mercury vapor, with several HgO-forming substrates, including water vapor, nitrous oxide, and oxygen. The reactions were carried out under flow conditions at room temperature. Emphasis has been placed on the Hg202 content of the HgO product. Enrichment in Hg202 would be evidence of the primary formation of a mercury compound.In the reactions with nitrous oxide and oxygen, it was found that the HgO product contained the normal abundance of Hg202. With water vapor, a product containing up to 35% Hg202 was obtained, compared to the normal abundance of 29.8%. The addition of 1,3-butadiene to the water vapor substrate was found to have a marked effect on the enrichment in Hg202 in the HgO product. A product containing 85% Hg202 was recovered when the substrate contained 21 mole % of added butadiene. A systematic study of the effect of butadiene concentration on the enrichment reaction showed that the Hg202 content remains constant for butadiene concentrations exceeding approximately 10 mole %. The water–butadiene reaction is recommended as a simple method for preparing Hg202 from natural mercury.The factors influencing the enrichment process are discussed, together with the significance of the results with respect to the mechanisms of decomposition of the molecules studied.

Hydration Chamber for Jeolco 200 Kv Microscope

1970 ◽  
Vol 28 ◽  
pp. 542-543
Author(s):  
V. R. Matricardi ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Electron Microscope ◽  
Water Vapor ◽  
Vapor Pressure ◽  
Pressure Gradient ◽  
Room Temperature ◽  
List Type ◽  
Type Number ◽  
Equilibrium Vapor Pressure

In order to observe room temperature hydrated specimens in an electron microscope, the following conditions should be satisfied: The specimen should be surrounded by water vapor as close as possible to the equilibrium vapor pressure corresponding to the temperature of the specimen.The specimen grid should be inserted, focused and photo graphed in the shortest possible time in order to minimize dehydration.The full area of the specimen grid should be visible in order to minimize the number of changes of specimen required.There should be no pressure gradient across the grid so that specimens can be straddled across holes.Leakage of water vapor to the column should be minimized.

Warm and freeze-fracture of cotton seed radicles

1987 ◽  
Vol 45 ◽  
pp. 984-985
Author(s):  
E. L. Vigil ◽  
E. F. Erbe
Keyword(s):  
Thin Film ◽  
Water Vapor ◽  
Fracture Surface ◽  
Membrane Structure ◽  
Room Temperature ◽  
Freeze Fracture ◽  
Longitudinal Axis ◽  
Fracture Plane ◽  
Cotton Seeds ◽  
Condensed Water

In cotton seeds the radicle has 12% moisture content which makes it possible to prepare freeze-fracture replicas without fixation or cryoprotection. For this study we have examined replicas of unfixed radicle tissue fractured at room temperature to obtain data on organelle and membrane structure.Excised radicles from seeds of cotton (Gossyplum hirsutum L. M-8) were fractured at room temperature along the longitudinal axis. The fracture was initiated by spliting the basal end of the excised radicle with a razor. This procedure produced a fracture through the tissue along an unknown fracture plane. The warm fractured radicle halves were placed on a thin film of 100% glycerol on a flat brass cap with fracture surface up. The cap was rapidly plunged into liquid nitrogen and transferred to a freeze- etch unit. The sample was etched for 3 min at -95°C to remove any condensed water vapor and then cooled to -150°C for platinum/carbon evaporation.

Mass spectrometric study of allyl radical, allyl bromide and 1,5-hexadiene interactions with oxides; Cobalt suboxide Co3O4

1979 ◽  
Vol 44 (7) ◽  
pp. 2009-2014 ◽  
Author(s):  
Jana Nováková ◽  
Zdeněk Dolejšek
Keyword(s):  
Room Temperature ◽  
Allyl Bromide ◽  
Catalytic Properties ◽  
Mass Spectrometric Study ◽  
Spectrometric Study ◽  
Flow Conditions ◽  
Allyl Radical ◽  
Knudsen Flow ◽  
Thermally Activated ◽  
Radical Interaction

Products of (a) allyl radical interaction with unheated Co3O4, (b) thermally activated 1,5-hexadiene or thermally activated allyl bromide with unheated Co3O4, (c) moderately heated Co3O4 with unheated 1,5-hexadiene or allyl bromide were studied under Knudsen flow conditions. Cobalt suboxide Co3O4, a typical catalyst of deep oxidations yielded acrolein in reaction with allyl radicals as early as at the room temperature of the catalyst. A similar acrolein formation was also observed in the allyl radical interaction with other oxides exhibiting different catalytic properties. It appears that acrolein is in general the primary product of the allyl radical interaction with the oxides. The results are discussed and compared with previous data obtained with MoO3.

scholarly journals Synthesis and characterization of a new ZIF-67@MgAl2O4 nanocomposite and its adsorption behaviour

RSC Advances ◽  
2021 ◽  
Vol 11 (22) ◽  
pp. 13245-13255
Author(s):  
Mehdi Davoodi ◽  
Fatemeh Davar ◽  
Mohammad R. Rezayat ◽  
Mohammad T. Jafari ◽  
Mehdi Bazarganipour ◽  
...  
Keyword(s):  
Room Temperature ◽  
Magnesium Aluminate ◽  
Synthesis And Characterization ◽  
Magnesium Aluminate Spinel ◽  
Adsorption Behaviour ◽  
Zeolitic Imidazolate Framework ◽  
Simple Method

New nanocomposite of zeolitic imidazolate framework-67@magnesium aluminate spinel (ZIF-67@MgAl2O4) has been fabricated by a simple method at room temperature with different weight ratios.

scholarly journals EPR Spectra of Sintered Cd1−xCrxTe Powdered Crystals with Various Cr Content

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3449
Author(s):  
Ireneusz Stefaniuk ◽  
Werner Obermayr ◽  
Volodymyr D. Popovych ◽  
Bogumił Cieniek ◽  
Iwona Rogalska
Keyword(s):  
Curie Temperature ◽  
Room Temperature ◽  
Integral Intensity ◽  
Resonance Field ◽  
Epr Spectra ◽  
Paramagnetic Resonance ◽  
Simple Method ◽  
Paramagnetic Curie Temperature ◽  
Cr Content ◽  
Electron Paramagnetic

In this paper, we show a simple method of producing ferromagnetic materials with a Curie temperature above room temperature. The electron paramagnetic resonance (EPR) spectra of Cd1−xCrxTe (0.002 < x < 0.08) were measured with a dependence on temperature (82 K < T < 381 K). Obtained EPR lines were fitted to a Lorentz-shaped curve. The temperature dependencies of the parameters of the EPR lines, such as the peak-to-peak linewidth (Hpp), the intensity (A), as well as the resonance field (Hr), were studied. Ferromagnetism was noticed in samples at high temperatures (near room temperature). For a sample with a nominal concentration of chrome of x = 0.05, a very strong intrinsic magnetic field is observed. The value of the effective gyromagnetic factor for this sample is ge = 30 at T = 240 K. An increase of chrome concentration above x = 0.05 reduces the ferromagnetic properties considerably. Analysis of the temperature dependencies of the integral intensity of EPR spectra was carried out using the Curie–Weiss law and the paramagnetic Curie temperature was obtained.

scholarly journals Ein Wasserstoffisotopieeffekt im CuSO4 * 5H2O

1969 ◽  
Vol 24 (10) ◽  
pp. 1502-1511
Author(s):  
Karl Heinzinger
Keyword(s):  
Water Vapor ◽  
Aqueous Solutions ◽  
Separation Factor ◽  
Room Temperature ◽  
Copper Ion ◽  
Hydrogen Isotopes ◽  
Bulk Water ◽  
Water Molecules ◽  
Hydration Water ◽  
Sulfate Solutions

Abstract There are two kinds of water in CuSO4·5H2O differing by their binding in the crystal. The oxygen of four water molecules is bonded to the copper ion, that of the fifth molecule is hydrogen bonded. It is shown that the D/H ratios of these two kinds of water differ by 5.7%, the light isotope being enriched in the water molecules coordinated with the copper ion. The results show that there is no exchange of the hydrogen isotopes during the time needed for dehydration at room temperature which takes several days. The assumption has been confirmed that the water coordinated with the copper ion leaves the crystal first on dehydration at temperatures below 50 °C. Additional measurements of the separation factor for the hydrogen isotopes between water vapor and copper sulfate solutions allow conclusions on the fractionation of the hydrogen isotopes between bulk water and hydration water in aqueous solutions.

scholarly journals Use of a heated graphite scrubber as a means of reducing interferences in UV-absorbance measurements of atmospheric ozone

2017 ◽  
Vol 10 (6) ◽  
pp. 2253-2269 ◽  
Author(s):  
Andrew A. Turnipseed ◽  
Peter C. Andersen ◽  
Craig J. Williford ◽  
Christine A. Ennis ◽  
John W. Birks
Keyword(s):  
Water Vapor ◽  
Solid Phase ◽  
Mercury Vapor ◽  
Packed Bed ◽  
The United States ◽  
Voc Adsorption ◽  
Clean Air ◽  
Smog Chambers ◽  
Equivalent Method ◽  
Ambient Measurements

Abstract. A new solid-phase scrubber for use in conventional ozone (O3) photometers was investigated as a means of reducing interferences from other UV-absorbing species and water vapor. It was found that when heated to 100–130 °C, a tubular graphite scrubber efficiently removed up to 500 ppb ozone and ozone monitors using the heated graphite scrubber were found to be less susceptible to interferences from water vapor, mercury vapor, and aromatic volatile organic compounds (VOCs) compared to conventional metal oxide scrubbers. Ambient measurements from a graphite scrubber-equipped photometer and a co-located Federal equivalent method (FEM) ozone analyzer showed excellent agreement over 38 days of measurements and indicated no loss in the scrubber's ability to remove ozone when operated at 130 °C. The use of a heated graphite scrubber was found to reduce the interference from mercury vapor to ≤ 3 % of that obtained using a packed-bed Hopcalite scrubber. For a series of substituted aromatic compounds (ranging in volatility and absorption cross section at 253.7 nm), the graphite scrubber was observed to consistently exhibit reduced levels of interference, typically by factors of 2.5 to 20 less than with Hopcalite. Conventional solid-phase scrubbers also exhibited complex VOC adsorption and desorption characteristics that were dependent upon the relative humidity (RH), volatility of the VOC, and the available surface area of the scrubber. This complex behavior involving humidity is avoided by use of a heated graphite scrubber. These results suggest that heated graphite scrubbers could be substituted in most ozone photometers as a means of reducing interferences from other UV-absorbing species found in the atmosphere. This could be particularly important in ozone monitoring for compliance with the United States (U.S.) Clean Air Act or for use in VOC-rich environments such as in smog chambers and monitoring indoor air quality.

Characterization of HfO2/Si Exposed to Water Vapor at Room Temperature

2006 ◽  
Vol 917 ◽  
Author(s):  
Carlos Driemeier ◽  
Elizandra Martinazzi ◽  
Israel J. R. Baumvol ◽  
Evgeni Gusev
Keyword(s):  
Water Vapor ◽  
Metal Oxide ◽  
Room Temperature ◽  
Gate Dielectric ◽  
Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
Dielectric Films ◽  
Nuclear Reaction Analysis ◽  
Environmental Air

AbstractHfO2-based materials are the leading candidates to replace SiO2 as the gate dielectric in Si-based metal-oxide-semiconductor filed-effect transistors. The ubiquitous presence of water vapor in the environments to which the dielectric films are exposed (e.g. in environmental air) leads to questions about how water could affect the properties of the dielectric/Si structures. In order to investigate this topic, HfO2/SiO2/Si(001) thin film structures were exposed at room temperature to water vapor isotopically enriched in 2H and 18O followed by quantification and profiling of these nuclides by nuclear reaction analysis. We showed i) the formation of strongly bonded hydroxyls at the HfO2 surface; ii) room temperature migration of oxygen and water-derived oxygenous species through the HfO2 films, indicating that HfO2 is a weak diffusion barrier for these oxidizing species; iii) hydrogenous, water-derived species attachment to the SiO2 interlayer, resulting in detrimental hydrogenous defects therein. Consequences of these results to HfO2-based metal-oxide-semiconductor devices are discussed.

Influences of water vapor on NASICON-based CO2 sensor operative at room temperature

2003 ◽  
Vol 93 (1-3) ◽  
pp. 243-249 ◽  
Author(s):  
Kenji Obata ◽  
Kengo Shimanoe ◽  
Norio Miura ◽  
Noboru Yamazoe
Keyword(s):  
Water Vapor ◽  
Room Temperature ◽  
Co2 Sensor
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