Opposite Pressure Research Articles

Location of trash racks on underground pressure conduits of hydroelectric stations

1. Unsubmerged tower intakes with their large height are complex in design, especially in seismic regions, and are labor-intensive in their construction and operation. 2. Submerged tower intakes are less labor-intensive and are sufficiently reliable in the case of a low rubbish content of the reservoir. 3. Bank intakes with their large depths are insufficiently reliable owing to the impossibility of using known trash-cleaning devices, and also due to the fact that the rubbish striking the inclined rack cannot slide down or be thrown off by the opposite pressure occurring upon a change in the load on the unit. 4. The underground location of trash racks with hydraulic flushing is the most promising in the case of a deep headwater tunnel.

Electrical transport in layered crystalline semiconductors GeS doped with Ag, P impurities at high pressure

A study of the transport properties of layered crystalline semiconductors GeS (undoped and doped with Ag, P impurity) under quasihydrostatic pressure using Bridgman anvil system is made for the first time. Pressure-induced effects in undoped crystals reveal initial rise in resistivity followed by two broad peaks at higher pressures. Silver doping induces only minor changes in the behaviour except removing the second peak. Phosphorous impurity is found to have drastic effect on the transport properties. Temperature dependence of the resistivity exhibits two activation energies having opposite pressure coefficients. Results are discussed in the light of intrinsic features of the layered semiconductors.

The role of shock wave in low-energy recoil atom radiation damage

Abstract A “hydrodynamic” model of displacement-spike evolution is proposed. At moderate recoil energies when the mean free path for atomic collisions is about interatomic distance, the shockwave formation is assumed to be the main mechanism of energy dissipation. It was shown that for recoil energies less than 1.5–3 keV the problem may be reduced to the problem of shock-wave propagation in an ideal gas with an initial opposite pressure. Some possible applications of the model are discussed, including calculations of threshold displacement energy and damage function, space distribution of radiation defects, and phase transitions in the displacement spike.

Mechanical interaction between the ventricles.

We investigated ventricular interaction by the use of six excised, perfused, canine hearts. In this preparation, we could change the filling pressure of the right and left ventricles independently, thereby breaking the normal series-pump arrangement. We found that mechanical ventricular interaction exists in diastole and in systole. Namely, not only decreased diastolic ventricular compliance, but also the reduced performance in either ventricle was found, when the opposite ventricular pressure was increased. Thus, when the opposite ventricular filling pressure increases, we suspect that systolic ventricular function of either ventricle will be depressed significantly by these two factors; i.e., the Frank-Starling effect due to decreased ventricular diastolic volume following decreased diastolic ventricular compliance, and the depressed systolic ventricular function. Clinically, these findings may be important in considering the mechanism of the occurrence of simultaneous reduced performance of both ventricles in cases when only one side of the ventricle is affected hemodynamically and its filling pressure is greatly increased in various pathological states such as heart failure.

Copernicus observations of C I - Pressures and carbon abundances in diffuse interstellar clouds

Using the Copernicus satellite, we observed ultraviolet absorption lines of interstellar neutral carbon atoms toward 27 stars. In addition to deriving column densities of C I (both in its ground state and the two excited fine-structure levels), we used our equivalent widths to revise the f-values of some of the C I transitions measured by other investigators. We also observed H<SUB>2</SUB> from the J = 4 level so that we could compare the rotational excitation of H<SUB>2</SUB> with the fine-structure excitation of C I. <P />From the amount of fine-structure excitation of C I in each case, we have derived information on the thermal gas pressures within the diffuse clouds. Most clouds have p/k between 10<SUP>3</SUP> cm<SUP>-3</SUP> K and 10<SUP>4</SUP> cm<SUP>-3</SUP> K, but we found that at least 6% of the C I-bearing material is at p/k &gt; 10<SUP>4</SUP> cm<SUP>-3</SUP> K, and one-third of the gas has upper limits for pressure below 10<SUP>3</SUP> cm<SUP>-3</SUP> K, assuming temperatures are not appreciably below 20 K. An analysis of radial velocities for the absorption lines showed no distinctive trends for the kinematics of high- or low-pressure gas components. From the apparent lack of acceleration of high-pressure clouds, we conclude that it is unlikely that streaming intercloud material is causing significant ram pressurization. <P />We have compared our results with the predictions for pressure fluctuations caused by supernova explosions in the theory of McKee and Ostriker. The observed lower bound for the amount of C I at higher than normal pressures (p/k &gt; 10<SUP>4</SUP> cm<SUP>-3</SUP> K) is about an order of magnitude below the prediction, which is probably a consequence of the C I-bearing clouds not responding rapidly enough to the upward jumps in intercloud pressure before they decay. At the opposite pressure extreme (p/k &lt; 10<SUP>3</SUP> cm<SUP>-3</SUP> K), we find more C I than predicted. <P />Toward most of the stars, we calculated the total abundance of atomic carbon, both ionized and neutral, based on our evaluations of the ionization equilibrium at the relevant pressures. Our observations are consistent with there being little or no depletion of carbon, except for a few stars in the Scorpius region where gaseous carbon seems to have about one-seventh its solar abundance relative to hydrogen, presumably because of condensation by grains. <P />Our observations provide useful constraints on the physical processes on the surfaces of grains. In particular, we find that grains are efficient catalysts of interstellar H<SUB>2</SUB> in the sense that at least half of the hydrogen atoms that strike grains emerge as part of H<SUB>2</SUB>.

Homogeneous hydroformylation of internal olefins by platinum/tin cationic complexes

Internal olefins are hydroformylated to linear aldehydes in substantial amounts with the cationic platinum/tin catalyst system PtCl(CO)(PR 3) 2 +/SnCl 2. By altering the nature of the phosphine ligand, as well as the various reaction conditions, the selectivity for terminal aldehyde production can be widely varied. Three competing processes, substrate hydroformylation, isomerization, and hydrogenation, are found to take place. The overall reaction is highly sensitive to syn gas pressure; however, total aldehyde selectivity and aldehyde linearity have opposite pressure dependences, rendering predominant normal aldehyde formation difficult.

Mechanical interactions between four heart chambers with and without the pericardium in canine hearts.

By using excised postmortem hearts obtained from 15 mongrel dogs with the pericardium intact, we investigated mechanical interactions between the four heart chambers from the standpoint of ventricular pressure-volume relationships. The interactions investigated were those between (1) the atrium and the ventricle, (2) the right ventricle and left ventricles, (3) the atrium and one ventricle vs. the other ventricle, and finally (4) the left and right atrium and the right ventricle vs. the left ventricle. For these purposes, we inserted compliant balloons into the four heart chambers without injuring the pericardium, i.e., we incised the base of the atria which was not covered with the pericardium. We obtained the right and/or left ventricular pressure-volume relationships under a constant pressure in three other heart chambers by changing the height of the reservoir connected to each balloon. As a result, both ventricular pressure-volume relationships were hardly affected by an increase in the atrial pressure ranging from 5 to 30 cm H2O with the pericardium removed, although the ventricle became less compliant due to an increase of the same magnitude of the opposite ventricular pressure. On the other hand, the effect of an increase in atrial pressure was distinct with the pericardium intact. Also, all mechanical interactions were enhanced dramatically with the intact pericardium. Thus, the pericardium plays an important role in these mechanical interactions, especially when the filling pressures of all heart chambers increase simultaneously. Clinically, these findings may be important to understanding ventricular functions as related to various heart disease-especially acute heart failure.

Secondary driving forces affecting transcapillary osmotic flows in perfused heart.

We evaluated secondary hydrostatic and osmotic pressure gradients caused by an osmotic flow across the wall of rabbit heart capillaries in vitro. Tissue fluid loss after addition of 80 mM sucrose to the Ringer perfusate depressed interstitial fluid pressure (IFP) by 13.2 +/- 1.1 cmH2O, as measured with a fine intramyocardial needle. This, plus a calculated rise in capillary pressure, caused a difference of 4.3 cmH2O in transcapillary pressures which represents 1.4% of the simultaneous and opposite osmotic pressure difference. The effect of transient-induced experimental changes in interstitial effect of transient-induced experimental changes in interstitial concentration of NaCl (main resident solute) during an osmotic transient and osmotic balance experiments using opposing transcapillary flows (Jv) and a sigma sucrose = 2.9 sigma NaCl. Long-term perfusion with solutions having abnormal concentrations of NaCl did not influence Jv, whereas inclusions of sucrose as resident solute depressed Jv by 10%. Results indicate that secondary hydrostatic and osmotic forces are small relative to the main osmotic driving force. Compliance measurements and calculations suggest that cells contribute three-fourths organ water loss during an osmotic transient, thus buffering volume, pressure, and concentration changes in the interstitial spaces.

付着形素子にみられる付着流パターンの動的挙動 （プリミティブ方程式による数値計算）

The reattaching flow pattern in a wall-reattachment fluidic amplifier is changed by activating a "Flow Control". Then, some interesting problems related with the initiation of a self-exciting pattern change due to the control flow are included in the behavior pattern. Prior to this, we had not had sufficient experimental results reflecting the dynamics of the reattaching flow. In this paper, we analyze the dynamics of this flow by a finite difference method developed from primitive Navier-Stokes equations. The important results are summerized as follows: (a) The changing processes of a reattaching flow pattern are related to pressure in the flow field. The opposite local pressure drop results from separation of the reversed flow along the opposite wall. (b) The changing processes for a short reattachment wall length may differ with the magnitude of control flow. The initiation of different processes depends on the point of the separations.

The Southern Oscillation. Part II: Associations with Changes in the Middle Troposphere in the Northern Winter

Abstract We have investigated the relationship between the extremes of the Southern Oscillation and the following quantities at 700 mb in winter, 1948/1949 to 1978/1979: eddy transfer of sensible heat, temperature, geopotential height and geostrophic wind. In the phase of the Southern Oscillation when pressures are high over the tropical South Indian Ocean and low over the tropical South Pacific Ocean, in contrast with the opposite pressure distribution, the zonal mean poleward flux of sensible heat in the quasistationary waves tends to be higher in middle latitudes; the temperatures and heights tend to be lower between 30 and 60°N with the maximum difference at 45°N; the geostrophic wind tends to be stronger south of 45°N and weaker to the north; and the transfer of sensible heat by the transient waves tends to be stronger south of 45°S, and weaker to the north. In this extreme of the Southern Oscillation the zonal mean geostrophic wind on both hemispheres is stronger in the subtropics and weaker at high...

Interstitial fluid pressure in rats measured with a modified wick technique

Subcutaneous interstitial fluid pressure ( P i) was measured in anesthetized rats with the “wick-in-needle” technique: A thin hypodermic needle was provided with a 2- to 4-mm-long sidehole and filled with multifilamentous nylon thread. A polyethylene tube, connecting the needle to a pressure transducer, could be compressed by a screw clamp, displacing a volume of about 0.2 μl. Compression caused a marked rise in pressure, but return to control level was obtained within 1 to 5 min. Decompression caused opposite pressure changes, confirming satisfactory fluid communication between needle and tissue fluid. Control P i (measured with saline-filled needle) ranged from −2.5 to +1.0 mm Hg, with mean values of −0.65 mm Hg (SD 0.82, n = 44) on the back and −1.2 mm Hg (SD 0.8, n = 11) on the hindlimb. Similar values were obtained with the needle filled with serum or 1% hyaluronic acid. Severe reduction of femoral arterial pressure reduced hindlimb P i gradually to −3 to −4 mm Hg in the course of 1 to 2 hr. P i was also reduced after 3–7 days of dehydration (−2 to −6 mm Hg) and rose rapidly with rehydration. Edema and a rise of hindlimb P i to positive values were observed when femoral venous pressure was increased from the control level of 3 to 12 mm Hg or more for a period of 24 hr.

Notizen: High Pressure Reactions, I Evidence for Two Concurrent Mechanisms in Lewis-Acid Catalyzed Alkylation of Aromatics with Olefins

A kinetic study was made of the primary step of the alkylation of benzene with propylene and ferric chloride as catalyst under homogeneous reaction conditions at several pressures up to 2 kbar. Initial reaction rate of cumene formation shows a minimum in the medium pressure range, thus indicating that product formation occurs via two different reaction paths with opposite pressure dependence.

Stress distribution due to a griffith crack at the interface of an elastic half plane and a rigid foundation

The stress field in a semi-infinite elastic media bonded to a rigid foundation and containing a crack at its interface is determined. Two specific problems are discussed-first when the elastic half space is under shear such that σ xv ~ P as √( x 2 + y 2) → ∞ and next when the crack is opened by equal and opposite pressure on each of its sides. The solution is obtained via Fourier transforms which lead to a simultaneous set of dual integral equations containing a trigonometric kernel. It is observed that in a small region near the ends of the crack, violent oscillations occur in both the stress and displacement components.

Primary Processes in the Vacuum Ultraviolet Photolysis of Ethyl Fluoride at 147 nm

The photolysis of C2H5F at 147 nm was studied at room temperature. The principal products include C2H3F, C2H2, C2H4, CH4, and C2H6. The principal primary photochemical reactions involve the molecular elimination of HF and H2, and, to a lesser extent, C—F and C—C bond fission. The effect of reactant and added inert gas pressure on the product yields has been investigated and it was found that the stabilization/decomposition ratio, C2H4/C2H2, displays opposite pressure dependence with ethyl fluoride and argon. This result is interpreted in terms of the higher energy transfer efficiency of the C2H5F molecule.

Activity evoked in cortical neurons and primary cutaneous afferent fibers by vibratory stimulation

N.N. VASILEVSKII, Z,A. ALEKSANYAN, and S.I. SOROKO Institute of Experimental Medicine, USSR Academy of Medical Sciences, Leningrad Vibration is a widespread form of contact stimulus. Two main hypotheses have been put forward to explain the mechanism of perception of vibration. Some authors consider that specific vibroreceptors exist (1, 2, 95 10). Scott (16), Gray and Matthews {13), Hunt and McIntyre (15), and Hunt (14) have described the high sensitivity of Paccinian corpuscles to vibratory stimulation. The opposite view, i.e., that vibration and pressure are both perceived by the same skin receptors, is also held (8, 12). Bekhterev (2) claimed that vibration may also be perceived by receptors of deep sensation located in the subcutaneous tissue, fascia, ligaments, joint capsules, and muscles. No definite conclusion regarding the mechanism of perception of vibration can be drawn from the literature, nor have the special features of the responses of central (especially cortical) neurons to vibratory stimulation yet been studied. The present investigation was therefore carried out in order to study activation of primary cutaneous afferent fibers of different modalities reacting to constant pressure and to transient light touch, and also activation of various types of cortical neurons in the projection zone of the cutaneous analyzer. Since it has now been established that the development of pathological changes fol- lowing prolonged exposure to vibratory stimulation (1) is reflex in nature, solution of the problems being studied will facilitate understanding of the pathogenesIs of vibration disease. In clinical neurology, changes in sensitivity to vibration are a differential diagnostic sign (6, 11).