Showing papers on "Atmospheric pressure published in 1978"

Telemetric differential pressure sensing method

Abstract: A differential pressure sensing device is fully implanted in the body of a patient to monitor internal pressure such as intracranial pressure. A movable element in the sensor communicates with the internal pressure of the body to be measured on one side and the atmospheric pressure on the other, the latter communicated through the intact skin and a nearly coplanar membrane. The movable element's differential pressure dependent displacement changes a physical characteristic of the sensor, such as the resonant frequency of a tuned L-C circuit, and the change is detected external to the body by a radiating detector system, such as a frequency swept radio frequency oscillator, by which the internal pressure is read out.

Pressure dependence of the elastic constants of nonmetamict zircon

Abstract: The single crystal elastic constants of nonmetamict zircons have been measured as a function of pressure to 12 kb at room temperature and also as a function of temperature between 25 and 300° C at atmospheric pressure. The pressure derivatives of the elastic constants are: C 11=10.78, C 33=5.88, C 44=0.99, C 66=−0.31, C 12=3.24, C 13=6.20. The anomalous negative behaviour of C 66 versus pressure could be associated with a high pressure phase transition. The pressure and temperature derivatives of the isotropic elastic wave velocities and elastic moduli for nonmetamict zircon are calculated from the present single crystal data by the Voigt, Ruess, and Hill approximations and compared with the values of some other oxides and silicates. The pressure derivative of the isotropic adiabatic bulk modulus is relatively high (dK S/dP=6.50), and the pressure derivative of the shear modulus is relatively low, (dG/dP=0.78), compared to the corresponding values for some other oxides and silicates. The Debye temperature, ϑD, and the high temperature limit of the Gruneisen parameter, γHt, calculated from the elastic constants and their pressure derivatives, agrees well with the Debye temperature and the thermal Gruneisen parameter, γth, calculated from the thermal expansion, heat capacity, and compressibility data.

Melting and crystallization of poly(vinylidene fluride) under high pressure

Abstract: Precise melting and crystallization temperatures of extended-chain and folded-chain crystals of form I and folded-chain crystals of form II poly(vinylidene fluoride) under high pressure have been obtained by microdifferential thermal analysis (DTA). Upon heating at pressures above 4000 kg/cm2, the micro-DTA thermogram of form II crystallized from the melt at atmospheric pressure shows melting of the form II structure and the melting of the folded-chain and extended-chain crystals of form I, formed through recrystallization processes. These features were clarified by supplemental methods. The bandwidth seen in electron micrographs of the extended-chain crystal of form I obtained by crystallization under high pressure was in the range of 1500 to 2000 A. At atmospheric pressure, the extended-chain crystal of form I melted at 207°C, approximately 17°C higher than the folded-chain crystal of form I and 31°C higher than the folded-chain crystal of form II.

The self-diffusion of Ni in NiO and its relevance to the oxidation of Ni

Abstract: The tracer self-diffusion coefficient of Ni in single crystals of NiO, at atmospheric pressure of oxygen, has been measured by sectioning in the temperature range 700 to 1400° C and is given by $$D_{Ni}^* = (15{\text{ }} \pm {\text{ }}08) \times 10^{ - 2} \exp {\text{ }}\{ - 58{\text{ }} \pm {\text{ }}1{\text{ }}(kcal)/RT\} {\text{ }}cm^2 \sec ^{ - 1} $$ Hence it is argued that the breakdown in the application of Wagner's theory to the oxidation of Ni at intermediate temperatures is not an impurity effect, but a result of short-circuit diffusion Diffusion of Ni along grain boundaries in NiO at 600° C has been observed using autoradiography and the productD GB * δ estimated to be 3×10−19 cm3 sec−1 This value is reasonably consistent with estimates from oxidation kinetics, but it is not yet established that grain boundary diffusion of Ni will account completely for the kinetics of nickel oxidation at this temperature

Single diaphragm telemetric differential pressure sensing system

Abstract: A differential pressure sensing device is fully implanted in the body of a patient to monitor internal pressure such as intracranial pressure. A movable element in the sensor communicates with the internal pressure of the body to be measured on one side and the atmospheric pressure on the other, the latter communicated through the intact skin and a nearly coplanar membrane. The movable element's differential pressure dependent displacement changes a physical characteristic of the sensor, such as the resonant frequency of a tune L-C circuit, and the change is detected external to the body by a radiating detector system, such as a frequency swept radio frequency oscillator, by which the internal pressure is read out.

The density dependence of the self-diffusion coefficient of methane at −50°, 25° and 50°C

Abstract: Self-diffusion data for methane obtained by the NMR spin-echo technique are reported at −50°, 25° and 50°C over the density range 2 to 27 mol dm−3. The apparatus was calibrated using literature atmospheric pressure tracer data for water and benzene and the calibration was checked using high pressure tracer data for benzene obtained by a separate technique. The methane results are found to be somewhat lower than those of earlier workers, but are consistent with limiting values calculated using the recent numerical intermolecular potential of Matthews and Smith. The data suggest that the first “virial” coefficient in the density expansion changes sign just above −50°C, though measurements at lower densities than are accessible with the present apparatus would be needed to confirm this conclusion. Chandler's rough hard sphere model is applied to the high density data and these are consistent with there being little, if any, translational-rotational coupling for diffusive motion of CH4. A relation is established between the hard sphere diameter and temperature allowing the calculation of D for liquid and dense gaseous methane in the region 90 20 mol dm−3. A comparison is made between recent molecular dynamics calculations of D and the experimental measurements.

Apparatus and method for automatically controlling hemodialysis at a pre-selected ultrafiltration rate

Abstract: Apparatus for and method of automatically controlling the quantity and rate of liquid removed from blood during hemodialysis The apparatus supplies dialysate in a single pass system in a closed, controlled volume circuit which includes an above atmospheric pressure portion and a below atmospheric pressure portion The above atmospheric pressure portion includes a pair of chambers for alternate supply to and removal of the dialysate from the below atmospheric pressure portion which contains an artificial kidney and a third means for removing fresh dialysate from the above atmospheric pressure portion; the below atmospheric pressure portion includes means which isolates the kidney containing portion and restores pressure to spent dialysate to a pressure at least equal to or higher than the pressure of the dialysate fed into said closed circuit; the above atmospheric circuit also includes means for removing gas from the spent dialysate prior to filling the spent dialysate removal chamber before discard

Post-Viking models for the structure of the summer atmosphere of Mars

Abstract: A reference model is proposed for the structure of the Mars atmosphere up to 100-km altitude. Based on Viking data, the model incorporates the mean temperature structure, mean surface pressure, mean molecular weight and gas constant, and pressure and density profiles. Model profiles with Viking and Mars 6 data are compared, and attention is given to warm and cool models. The thermal boundary layer is considered along with the role of thermal tides.

Structure analysis of high-pressure metallic state of iodine

Abstract: The crystal structure of the high-pressure metallic state of iodine has been determined by x-ray diffraction technique ultilizing a diamond-anvil high-pressure cell combined with a position-sensitive proportional counter. Diffraction intensities measured at 206 kbar were very well interpreted by assuming the space group ${D}_{2h}^{18}$ which is the same as that at atmospheric pressure. With further increase in applied pressure, the structure will approach to a face-centered orthorhombic lattice formed by monoatomic iodine.

Catalytic synthesis of ethanol from CO and H2 under atmospheric pressure over pyrolysed rhodium carbonyl clusters on TiO2, ZrO2, and La2O3

Abstract: C2-oxygenated compounds composed mainly of ethanol were catalytically produced from CO and H2 under atmospheric pressure over pyrolysed Rh carbonyl clusters dispersed on specific metal oxides such as TiO2, ZrO2, and La2O3.

Continuous pressure cooker and cooler with controlled liquid flow

Abstract: Method and apparatus for continuously processing filled containers with liquid heat treatment mediums maintained under superatmospheric pressure by an overriding air pressure A minimum of liquid is used during processing with the liquid level being maintained above the containers at all times The liquid is controllably circulated through container filled tunnels defined within carts, from one end of the tunnel to the other, to assure equal heat treatment of all containers in the batch of containers in each tunnel The carts may either be non-agitating or agitating carts One embodiment of the continuous pressure cooker and cooler includes a pressure vessel having two pressure locks to provide a pressure cooking chamber with high pressure cooling being performed in a mini-cooler defined by the outlet pressure lock followed by additional atmospheric cooling Another embodiment of the invention comprises three pressure lock means to positively divide the pressure vessel into cooking and cooling chambers; and a third embodiment substitutes a plurality of baffles for the intermediate pressure lock thereby effectively dividing the pressure vessel into a cooking chamber and cooling chamber

Airless sprayer and pressurizing system

Abstract: An airless sprayer having the capability of replacing most if not all of the so-called aerosol sprayers with improved performance, reduced cost and elimination of potential damage to the environment from an aerosol propellant. The unit is refillable by the user at any time suiting his convenience. The liquid to be sprayed is contained in a first chamber above an internal free-floating piston powered by air pressure in a second chamber below the piston. The system includes a unique compressor unit for automatically pumping air at operating pressure into the lower chamber.

A sealed high-repetition-rate TEA CO 2 laser

Abstract: A compact atmospheric pressure CO 2 laser utilizing a double-discharge technique has been constructed and operated at repetition rates to 100 pulses/s. With the addition of small amounts of hydrogen and carbon monoxide to give a gas mixture of He:N 2 : CO 2 :CO:H 2 = 69.3:11:15:4:0.7, sealed operational lifetimes exceeding 2 \times 10^{6} pulses have been obtained. Operating in this mode, the output energy density is about 8-9 J/l at repetition frequencies of 30-40 pulses/s for input energy densities of 60-70 J/l. The operation of the sealed laser has been studied by means of mass spectroscopic measurements of the gas mixture. It has been determined that sealed operation is possible as long as the oxygen concentration is kept below 1-2 percent. It has also been found that the addition of small amounts of H 2 and CO will keep the oxygen concentration below 2 percent by reducing the CO 2 decomposition, allowing sealed operation. The experimental results are compared to the predictions of a theoretical model in which neutral and negative-ion processes have been included. The calculations indicate that when small amounts of oxygen or water are present in the discharge the negative-ion population is significantly increased and the ratio of negative-ions to electrons N_{n}/N_{e} can approach values near unity. These are the conditions under which discharge arcing was found to occur. The model also predicts that the dissociation equilibrium of the CO 2 can be controlled by the addition of the above concentrations of hydrogen and CO.

Influence of atom-atom collisions on thermal equilibrium in argon arc discharges at atmospheric pressure

Abstract: A collisional radiative model is used to obtain the number densities of the ground level and of the excited levels of neutral argon as a function of the local ne and Te values This model is first applied to a homogeneous and stationary medium for 5000K

Further studies on the pressure tolerance of deep-sea crustacea, with observations using a new high-pressure trap

Abstract: A deep-sea benthic trap is described with which amphipods (Tmetonyx cicada) were both collected and observed at their ambient pressure of 134 atm. T. cicada collected with decompression from the same depth and locality were more sensitive to subsequent recompression than those amphipods brought to the surface at their ambient pressure. T. cicada from 2700 m experience irreversible injury during decompression to atmospheric pressure. The pressure tolerance of the deep-sea mysid Gnathophausia zoea was measured and compared with the tolerance of mid-water decapods and the shallow-water Crangon crangon. G. zoea became more sensitive to high pressure with prolonged exposure to atmospheric pressure. Deep sea animals exhibit a tolerance to high pressure related to their normal ambient pressure; sensitivity to decompression is also related to normal ambient pressure.

Solubility and diffusivity of oxygen in aqueous sucrose solutions

Abstract: Solubility and diffusivity of oxygen in aqueous sucrose solutions of various concentrations were measured at temperatures from 15° to 45°C and at atmospheric pressure. The solubility of oxygen could be correlated well by the method of van Krevelen and Hoftijzer. The diffusivity of oxygen was found to be proportional to the −2/3 power of the viscosity of the solution.

Process and apparatus for the biological treatment of waste water

Abstract: Waste water to be treated is introduced into an enclosed gas tight oxygenation chamber An oxygen-containing gas is also introduced into the oxygenation chamber, at a pressure higher than atmospheric pressure, such that oxygen from the gas is dissolved in the waste water in a quantity higher than the saturation concentration value of oxygen in the waste water at atmospheric pressure, thereby superoxygenating the waste water The thus superoxygenated waste water, maintained at such pressure higher than atmospheric pressure, is then passed into an enclosed gas tight filtering chamber which is separate from the oxygenation chamber and which is also maintained at such pressure higher than atmospheric pressure No other oxygen, other than the oxygen dissolved in the waste water, is introduced into the interior of the filtering chamber The superoxygenated waste water is passed through a biological filter bed within the oxygenation chamber, thereby biologically purifying the waste water to form purified water which is then removed from the filtering chamber

The sound velocity in metastable liquid water under atmospheric pressure

Abstract: Ultrasonic sound velocity data in supercooled water are analyzed in the light of present theories. Preliminary evidence for a minimum in the sound speed versus temperature curve is shown to be consistent with available data for other thermodynamic properties. A simple two‐state mixture model combined with experimental data may be used to yield similar evidence. Sound speed data in superheated water are used to determine other thermodynamic parameters in the 100 to 170 °C temperature range under atmospheric pressure.