Retrograde Phenomena Research Articles

People living with Alzheimer's disease: Understanding the emerging phenomenon of retrograde plunge with the story theory-An inquiry method.

This study aims to (1) introduce the emergent concept of the retrograde plunge experienced by people living with Alzheimer's disease and (2) illustrate how nurses can accompany those experiencing this phenomenon, as well as their family and formal carers, using the seven-phase inquiry process proposed by Smith and Liehr. Discursive paper. After describing the phenomenon and the Story Theory, the 7-phase Inquiry Process presents the fictional story of Mrs. Lurie, a nursing home resident. Story theory allows nurses to accompany Mrs. Lurie. The emergent concept of retrograde plunge is explained. Different tools such as genograms, story paths and eco-maps are presented. This discussion demonstrates how some perspectives can contribute to a better description of the retrograde plunge phenomenon. The narrative care approach can help give voices to people experiencing retrograde phenomena. The adoption of a perspective that considers embodied language could help to better understand the needs of a person. There is a lack of consistency and uniformity regarding the understanding of the retrograde phenomenon. This impacts the quality of care for people and the scientific knowledge, research and education of healthcare professionals. This issue should be addressed in future studies. This article shows how story theory helps nurses accompany those facing a retrograde plunge phenomenon, helps them tell their own stories and finds a way to resolve the situation. This article paves the way for further developments that must now be realized by the international community of experts involved in the care of people with Alzheimer's disease, from practical, academic and research perspectives. No patient or public was involved in the design or drafting of the discursive paper. WHAT PROBLEM DID THE STUDY ADDRESS?: The retrograde plunge is a phenomenon in which people living with Alzheimer's disease return to their past lives and re-experience with certain events. The retrograde plunge is a well-known concept that is poorly described in scientific literature and is sometimes misunderstood by families and professional caregivers. This discursive article explains the retrograde plunge phenomenon experienced by people living with Alzheimer's disease. WHAT WERE THE MAIN FINDINGS?: This article demonstrates how story theory helps nurses and families support people with retrograde plunges. This highlights the lack of consistency and uniformity in this phenomenon, which has implications for the quality of care, education and research. Story theory and the seven-phase inquiry process proposed by Smith and Liehr (in Middle-range theory for nursing, Springer Publishing Company, 2023) help to better understand and explain the retrograde plunge phenomenon. WHERE AND ON WHOM WILL THE RESEARCH HAVE AN IMPACT?: This article advances nurses' knowledge in the different fields of practice, teaching and research. This article proposes links among the retrograde plunge phenomenon, embodied language and narrative care approach; this could offer further ways to develop nursing knowledge. This study has the potential to advance the knowledge of practice and education and offers new opportunities for research. There was no trial or protocol registration as this article is a discussion.

ON THE ANALYSİS OF OPERATİNG PRACTİCES OF LİQUEFİED GAS PİPELİNES

ON THE ANALYSİS OF OPERATİNG PRACTİCES OF LİQUEFİED GAS PİPELİNES

THE PROTECTION OF ENVIRONMENT IN THE PROCESS OF INSTALLATION OF KNOCKOUT POTS ON GAS PIPELINE

Improving the factors of gas pipelines and optimizing the quality of transported gas is one of the main problems of the gas industry. To overcome these problems, gas treatment and transportation technology should be improved using the latest science and technology, and the efficiency and effectiveness of existing equipment should be increased. Sources of technological losses of gas are indicated, classification of losses on sources and facilities is given, it is noted that the losses are due to the lack of modern requirements for equipment used for gas collection, treatment, transportation and storage processes and equipment and technologies used in these systems. Due to the unsatisfactory performance of these devices and equipment, a large amount of liquid phase remains in the processed gas and is transferred to the transport system along with the gas. During transport, as a result of thermobaric influence of the environment, the thermodynamic parameters of the gas change and the process of condensation of hydrocarbon condensate and water vapor into liquids, i.e. phase transitions, resulting in changes in gas density and component composition. This, in turn, leads to an disbalance between the amount of gas delivered and received. The amount of gas losses in transport systems due to phase transitions varies depending on the seasons. On the other hand, under certain thermobaric conditions, retrograde phenomena such as "reverse condensation" and "reverse evaporation" can also occur. That is, evaporation can occur when the pressure increases, and condensation can occur when the pressure decreases. Due to the fact that the composition of the product produced during the depletion of the fields is constantly changing, the maximum condensing pressure set at the beginning of the development may not be sufficient for the next period. In this case, the lower temperature of the gas enriches it with water vapor and heavy hydrocarbons. Given that the main condition for the condensation of liquid vapors in the gas depends on the degree of saturation of the gas with vapors, then changes in pressure and temperature during transportation are important. Since phase transitions due to pressure and temperature changes during transportation were observed with hydrocarbon losses, gas “losses” were assessed based on physical and chemical analysis of gas samples taken from high and low pressure gas pipelines to assess these losses. Effective and efficient methods have been extensively studied and commented on in order to improve the factors of liquefied gas pipelines and optimize the transportation process. The structure, shape and properties of liquid-added gas streams were studied as a result of phase transformations in the gas stream under the influence of pressure, temperature and surfactants. In order to improve the factors of gas pipelines, to ensure that the quality of gas meets the standards, the methods of removing the liquid phase from the gas flow are explained and the effectiveness of these methods is verified. The main reasons for the removal of liquid additives from gas pipelines from the process with the help of condensate collectors and air pollution during operation are the release of ingredients from the shut-off valves and process equipment into the atmosphere. During the operation of condensate collectors, it is important that the level of contamination from the emissions of harmful substances from all sources is within the permissible concentration limits. In order to prevent the release of waste into the atmosphere during the installation and operation of condensate collectors in gas pipelines, environmental protection measures were taken and the possibility of calculating the amount of waste released into the atmosphere through the application of the "Ecologist-2.55" program. Keywords: Separation, gas, pipeline, condensate, temperature, liquid additives, atmosphere.

Molecular Complexity of Working Fluids Dedicated to Organic Rankine Cycle (ORC)

Organic Rankine Cycle (ORC) power plants are the most well-known and mature technology used to converting low and medium-temperature heat into electricity, especially from waste heat and renewable energy sources (including geothermal and solar thermal). Despite the level of development of ORC systems available on the market, there are still many aspects in the context of improving those units – constructing economically profitable low power unit, improving efficiency, selection an appropriate working fluid, etc. This paper analyzes 17 workings fluids dedicated to ORC system and discusses an existence of low stability region in their dense vapors and its influence on some peculiarities in behaviors of selected isentropic and dry fluids. The analysis shows relation between the retrograde phenomena in the flow of ORC fluids and mechanical and thermodynamic stability parameters.

An influence of low-stability region on dense gas phenomena and their peculiarities in the ORC fluids

An existence of low stability region in the dense vapours and its influence on some peculiarities in behaviour of selected dry and isentropic ORC fluids is discussed. The retrograde phenomena in the flow of BZT fluids [1.] can be simply related to the mechanical and thermodynamic stability parameters. These new refrigerant and their properties have been analysed based on the software tools REFPROP v.9.1 [2.]. Test examples have confirmed an importance of low thermodynamic stability area in the vicinity of saturation boundary line and neighbourhood of critical point of the fluid. The analytical results have been obtained for selected pure fluids applicable in the ORC and heat pump technology such C 4 H 10 , C 6 H 5 CH 3 , C 12 H 26 , R123, R134a, R227ea, R245fa, low GWP hydrofluoroolefins (R1234xxX)and a group of linear and cyclic siloxanes.

Mathematical modeling and study of mass transfer parameters in supercritical fluid extraction of fatty acids from Trout powder

Mathematical modeling of fatty acids (FAs) extraction from Trout powder by supercritical carbon dioxide was performed in the present work. Trout powder with its low cost contains high amount of essential FAs and it is commonly available as a proper source of FAs. The effect of process parameters, such as pressure (25, 28, 31, 34 and 37 MPa) and temperature (310, 318 and 326 K) of extraction and void fraction of the bed (0.25, 0.35 and 0.45, v/v) on the yield of FAs extraction was examined in a series of experiments conducted in a laboratory scale apparatus. The results indicated a significant increase of extraction yield with an increase of pressure from 25 to 34 MPa, but working at the higher pressure (37 MPa) caused reduction of the extract. Increasing the temperature higher than 318 K revealed significant reduction of the FAs yield and increasing the bed void fraction from 0.25 to 0.45 showed enhancement of the extraction. The mathematical model was developed considering diffusion-controlled regime in the particle and film mass transfer resistance around the particle with axial dispersion of the bulk phase at dynamic conditions. Henry law was used to describe the equilibrium state of solid and fluid phases. The proposed mass balance equations were numerically solved using implicit finite difference method and the model parameters were correlated using the experimental results of the outlet FAs concentration in the oil extracted at dynamic conditions. Well-known Nelder–Mead method was applied to estimate the four parameters of the model, namely, mass transfer coefficient ( k f), axial dispersion coefficient ( D ax) in the bulk phase, effective diffusivity ( D eff) into the pores and Henry coefficient ( H). In the range of studied conditions, the higher extraction efficiency with higher pressure resulted lower correlated H, although the temperature increasing which showed a retrograde phenomena in the FAs yield, revealed H passing though a minimum.

Wax Precipitation in Gas Condensate Mixtures

Summary Wax precipitation for gas condensate fluids was studied in detail with a thermodynamic model. It was found that the precipitated wax phase can exhibit retrograde phenomena similar to that in gas condensates. As a result of pressure decrease (at a constant temperature), the amount of precipitated wax may first increase, then decrease, then increase again. The effect of pressure on wax precipitation from gas condensates was also studied. Pressure often shows an opposite effect in wax precipitation to that in liquids; however, the pressure effect is not universal. The model used in this work accounts for both the Poynting correction term and the solid-state phase transitions. Incorporation of these effects reconfirms the suitability of the multisolid phase for wax-precipitation calculations (both the onset and the amount).

Molecular and macroscopic modeling of phase separation

AbstractRecently proposed pseudoensemble Monte Carlo methods are extended in this work to map out diverse phase diagrams (projections of the phase‐coexistence hypersurface) of multicomponent mixtures required to characterize fluid‐phase equilibrium phenomena and to design separation processes. Within the pseudoensemble framework, the macroscopic models of different equilibrium processes can be readily integrated to the mathematical constraints that specify the thermodynamic state of the system. The proposed Monte Carlo methods allow, for example, the simulation of isopleths and cloud‐point lines to compare experimental to simulation data and to test molecular force fields. Applications of this approach include the study of retrograde phenomena in a model natural‐gas mixture through simulation of dewlines and coexistence lines at constant vaporization fraction. As demonstrated, pseudoensemble simulations can also be used to generate the thermodynamic data necessary to solve problems encountered in continuous and discontinuous distillation processes.

Liquid-liquid-vapour phase equilibria in the system methane + ethane + eicosane: retrograde behaviour of the heavy liquid phase

Gregorowicz, J., Smits, P.J., de Loos, Th.W. and de Swaan Arons, J., 1993. Liquid-liquid-vapour phase equilibria in the system methane + ethane + eicosane: retrograde behaviour of the heavy liquid phase. Fluid Phase Equilibria, 85: 225-238. The fluid phase behaviour of the ternary system methane + ethane + eicosane was studied experimentally with special emphasis on liquid-liquid-vapour equilibria and retrograde condensation of the second, heavier liquid phase in this region. P, T sections for mixtures of constant composition were determined according to the synthetic method for nine constant molar ratios of ethane and eicosane and different mole fractions of methane. The temperature range investigated was 290–307 K and the pressure range 5.0–6.4 MPa. Addition of methane to a binary ethane + eicosane mixture expands the three-phase curve to a region and shifts it to lower temperatures. The influence of the concentration of eicosane and of methane on the phase behaviour in the three-phase region and on retrograde phenomena is discussed.

Two-phase multicomponent filtration: instabilities, autowaves and retrograde phenomena

The different modifications of the models of two-phase multicomponent filtration (Collins 1961; Nikolaevsky et al. 1968) enable one to study the dynamics of filtration flows, taking into account phase transitions. The equations of multicomponent filtration are quite complicated and only in a few individual cases do they allow for an exact solution. The most frequently used of these appears to be the solution of the stationary problem of the flow of a multicomponent mixture toward a well or a system of wells (Khristianovich 1941). In the present paper we show that at certain values of pressure, temperature and composition of the multicomponent mixture a stationary solution of the problem may not exist. The absence of a stationary solution is related to the possibility of a spatially homogeneous solution losing its stability under a perturbation (Mitlin 1986a, 1987b). We obtain an analytical criterion for instability. As an illustration, we present the results of the numerical solution of the planar linear problem of the evolution of a multicomponent system whose pressure and composition are perturbed with respect to their constant values, which are equal at both ends. We have done a numerical analysis of the plane-radial problem of the operation of a gas–condensate well with different mass fluxes, applying the conditions of a real deposit. There are several ranges of flux where the flow becomes pulsating. It is shown that the time within which the stationary solution sets in is a non-monotonic function of flux and on approaching the stability limit diverges in inverse proportion to the undercriticality of debit. We have analysed the connection between the observed instabilities and the thermodynamics of two-phase multicomponent mixtures. It is shown that the instabilities are associated with the system entering the region of retrograde condensation. We discuss the relation of retrograde phenomena to the effect of negative volume of heavy components and, as a consequence, to the negative compressibility of an individual volume of a two-phase mixture moving in a porous medium. It is shown that the observed autowave modes are relaxation oscillations in a distributed system. By using the method of perturbations in the interphase equilibrium time, we have analysed the loss of stability in a more general – non-equilibrium – model. We show that the instabilities are generated according to the Landau–Hopf scenario and calculate the period of auto-oscillations. The one-mode approximation of the theory leads to the Van der Pol equation. In conclusion we present an experimental confirmation of the theory.

Visual Investigation of Retrograde Phenomena and Gas Condensate Flow in Porous Media

The mechanism of retrograde condensation and the flow of gas-condensate in horizontal porous media under simulated reservoir conditions were visually studied. Two-dimensional glass micromodels with homogeneous pore structures, as well as heterogeneous patterns, reproduced from real rock micrographs were employed in this study. Depletion tests were carried out using synthetic multicomponent hydrocarbon gas mixtures and also a North Sea gas condensate. The multiphase flow behaviour of the tested systems, as observed and recorded on video, is presented here along with the measured data. In water-wet pores, condensate was observed to be formed as a continuous thin film on connate water, which was the preferred site for condensation. Pressure reduction below the system cricondenbar resulted in the growth of the condensate almost exclusively on water rings at pore throats and dead end pores. The condensate was observed to flow through thin films even at low saturations, with little contribution to the condensate recovery. The rate of pressure depletion influenced the gas flow shear and was found to strongly affect the condensate propagation. Local instabilities could promote significant condensate movement in pore sections which would only be retarded further downstream by capillary effects diminishing the condensate recovery. Relative permeability-saturation relation-ships for gas-condensate flow should not be expected to take the same form as the oil-gas relative permeability for solution gas or external gas drive.

Contact metamorphism of pelitic, psammitic and calcareous sediments in the Southern Highlands of New South Wales

Contact metamorphism has been recognized along a 4 km wide belt adjacent to the shallow‐dipping eastern margin of the Arthursleigh Tonalite, an Early Devonian pluton of the Marulan Batholith, eastern New South Wales. In Ordovician psammitic and pelitic rocks three zones of progressive contact metamorphism range from muscovite + biotite + chlorite assemblages in the outer zone to K‐feldspar + cordierite assemblages adjacent to the pluton and in metasedimentary xenoliths. Retrograde phenomena include extensive replacement of metamorphic minerals by ‘sericite’ and chlorite. Calcareous metasediments adjacent to the tonalite typically contain assemblages of quartz + calcic plagioclase + ferrosalite + sphene, or wollastonite + calcite + diopside with minor grossularite and vesuvianite. Thermal effects in volcanic rocks along the western margin of the pluton are confined to recrystallization of the groundmass. The regional geology indicates confining pressures of approximately 1 kbar at the time of emplacement of the tonalite. Contact metamorphic temperatures were estimated from two‐feldspar geothermometry to attain a maximum of approximately 590°C for rocks in the innermost zone of the aureole and 700°C for the xenoliths. Fluid compositions attending progressive contact metamorphism were water‐rich (Xco2<0.2) and, during cooling, these fluids probably account for the extensive retrograde hydration observed in the aureole.

Assessment of esophageal transit of liquid.

We note with interest the report by Ham et al. (1985) comparing methods for the analysis of liquid-radionuclide esophageal transit studies, with emphasis on functional images. These included condensed images with a temporal and a spatial dimension, and images displaying quantitative parameters derived from the original dynamic information on a pixel-to-pixel basis. A number of techniques being possible, such comparative investigations are surely warranted. We too have evaluated several methods (Klein 1983; Klein and Wald 1984) and, like Ham et al., have shown that condensed images (adapted from Svedberg 1982) are useful for depicting intraesophageal retrograde motion and other phenomena. We have favored supplementing these quantitatively derived but qualitatively evaluated functional images with objective quantitative measurements of global esophageal transit. Our analysis of a swallow of liquid draws on a model of rapid and residual components, the latter component remaining stable in amount until the subject's second swallow. A finite residual component complicates the calculation of transit parameters, as does retrograde motion, when individual regions of the esophagus are assessed. By resolving the two components and by examining the whole organ, these problems can be obviated (Klein and Wald 1985a). Our quantitative parameters include (1) the mean transit time of the rapid component and (2) the residual fraction. The mean transit time is computed from the appropriate curve using the same area-over-height formula (Zierler 1965) that Ham et al. (1985) applied regionally in one of their functional images. The residual fraction is the percentage of the total dose that constitutes the residual component. We have found a high residual fraction that persists during multiple swallows to be the most sensitive index of abnormality (Klein and Wald 1984). A similar observa-

Improved High Pressure Capillary Tube Viscometer

Published in Petroleum Transactions, AIME, Volume 216, 1959, pages 85–91. Abstract An apparatus and a procedure for determining the viscosity behavior of hydrocarbons at pressures up to 10,000 psia and temperatures between 77 and 400°F are described. The equipment is suitable for measuring viscosity of either the liquid or vapor phases or the fluid above the two-phase envelope for systems exhibiting retrograde phenomena, according to the phase state of the system within these ranges of temperature and pressure. Equations are developed for calculation of viscosity from the experimental measurements, and new data for the viscosities of ethane and propane at 77°F are reported. Introduction With the advent of higher pressures and temperatures in industrial processes and deep petroleum and natural gas reservoirs, demand has increased for accurate values of physical properties of hydrocarbons under these conditions. Proportionately, more frequent occurrence of natural gas and condensate-type fluids is encountered as fluid hydrocarbons are discovered at greater depths. This increases the importance, to the reservoir engineer, of being able to predict accurately the physical properties of light hydrocarbon systems in the dense-gas and light-liquid phase states. Reliable gas viscosity data are limited primarily to measurements made on pure components near ambient temperature and at low pressures. Few investigations have been reported for high pressures, and except for methane, data on light hydrocarbons are subject to question. This is demonstrated by the large discrepancy between sets of data on the same component reported by different investigators. For mixtures in the dense gas and light liquid regions and for fluids exhibiting retrograde behavior there are very few published experimental data. Viscosity data for methane have been reported by Bicher and Katz, Sage and Lacey, Comings, et al, Golubev, and Carr, with good agreement among the last three sets of data. Comings, Golubev and Carr utilized capillary tube instruments for which the theory of fluid flow is well established. The theory permits calculation of the viscosity directly from the experimental data and dimensions of the instrument alone.