Thixotropy and dilatancy

Clay Minerals ◽  
1966 ◽  
Vol 6 (4) ◽  
pp. 323-331 ◽  
Author(s):  
G. H. Cashen
Keyword(s):  
Water Potential ◽  
Pore Space ◽  
Matric Potential ◽  
Air Interface ◽  
Water Films ◽  
The Difference ◽  
Characteristic Features

AbstractThe matric potential of water in gels of five-sixths neutralized aluminium montmorillonite (bentonite) and aluminium kaolinite changes during periods of shear and periods of rest. Shear increases the potential of water in bentonite gels, and in kaolinite gels containing little water, but decreases the potential in kaolinite gels containing more water. All these effects can be explained by changes in the curvature of water films at the gel-air interface. The difference between thixotropic and dilatant behaviour is the increasing and decreasing of the water potential on shearing. In dilatant pastes of silt-size particles, and for which the effects of electric charges are small, the pressure deficiency can reach large values after an increase in pore space, and this suffices to explain the characteristic features of dilatant behaviour.

STUDY OF IN-MEDIUM PROPERTIES OF N*(1535) AND CHIRAL SYMMETRY FOR BARYONS THROUGH THE η-MESIC NUCLEI FORMATION AT J-PARC

2008 ◽  
Vol 23 (27n30) ◽  
pp. 2512-2515 ◽  
Author(s):  
HIDEKO NAGAHIRO ◽  
DAISUKE JIDO ◽  
SATORU HIRENZAKI
Keyword(s):  
Chiral Symmetry ◽  
Cross Sections ◽  
Optical Potential ◽  
Nuclear Medium ◽  
Nucleus Interaction ◽  
Level Crossing ◽  
Doublet Model ◽  
The Difference ◽  
Characteristic Features ◽  
Mesic Nuclei

We investigate the properties of η-nucleus interaction by postulating the N*(1535) dominance for η-N system. We evaluate the N*(1535) properties in the nuclear medium using two kinds of chiral models, and find that these two models provide qualitatively different η-nucleus optical potentials reflecting the quite distinct properties of N*(1535) in these chiral models. Especially, in the chiral doublet model, we can expect to have the level crossing between η and N*(1535)-hole which is expected to provide the characteristic features for the optical potential and the formation spectra. We find also that the difference of these models can be seen in the formation cross sections of the η mesic nuclei with (π+, p ) reaction expected to be performed at J-PARC project.

scholarly journals Squirt flow due to interfacial water films in hydrate bearing sediments

2017 ◽  
Author(s):  
Kathleen Sell ◽  
Beatriz Quintal ◽  
Michael Kersten ◽  
Erik H. Saenger
Keyword(s):  
Flow Model ◽  
Pore Space ◽  
Seismic Attenuation ◽  
Interfacial Water ◽  
Seismic Velocities ◽  
High Attenuation ◽  
Water Films ◽  
Direct Model ◽  
In Situ Experiments ◽  
Hydrate Bearing Sediments

Abstract. Sediments containing gas hydrate dispersed in the pore space are known to show a characteristic seismic anomaly which is a high attenuation along with increasing seismic velocities. Currently, this observation cannot be fully explained albeit squirt-flow type mechanisms at the microscale have been speculated to be the cause. Recent major findings from in-situ experiments coupled with high-resolution synchrotron-based X-ray micro-tomography revealed a systematic presence of thin water films between the quartz grains and the encrusting hydrate. In this study, the data was obtained from the experiments and underwent an image processing procedure to quantify the thicknesses and geometries of the aforementioned interfacial water films. Overall, the water films vary from sub-μm to a few μm in thickness where some of them are interconnected by water bridges. This geometrical analysis is then used to propose a new conceptual squirt flow model for hydrate bearing sediments. Subsequently the established model acts as a direct model input to obtain seismic attenuation. Our results support previous speculations that squirt flow can explain high attenuation at seismic frequencies in hydrate bearing sediments, but based on a conceptual squirt flow model which is different than those previously considered.

scholarly journals DINÂMICA DA ÁGUA NO SISTEMA SOLO-PLANTA NO CULTIVO DA PIMENTA TABASCO SOB DÉFICIT HÍDRICO1

Irriga ◽  
2018 ◽  
Vol 1 (01) ◽  
pp. 246
Author(s):  
Lígia Borges Marinho ◽  
José Antonio Frizzone ◽  
João Batista Tolentino Júnior ◽  
Janaina Paulino ◽  
Danilton Luiz Flumigan ◽  
...  
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Water Deficit ◽  
Water Extraction ◽  
Soil Matric Potential ◽  
Water Restriction ◽  
Matric Potential ◽  
Mato Grosso ◽  
Vegetative Phase ◽  
E Mail

DINÂMICA DA ÁGUA NO SISTEMA SOLO-PLANTA NO CULTIVO DA PIMENTA TABASCO SOB DÉFICIT HÍDRICO1  LÍGIA BORGES MARINHO2; JOSÉ ANTONIO FRIZZONE3; JOÃO BATISTA TOLENTINO JÚNIOR4; JANAÍNA PAULINO5; DANILTON LUIZ FLUMIGNAN6 E DIEGO BORTOLOTI GÓES3    (1) Artigo extraído da tese do primeiro autor (2) Departamento Tecnologia e Ciências Sociais, Universidade do Estado da Bahia, av. Edgard Chastinet, São Geraldo, CEP 48905-680, Juazeiro, BA. Fone (74) 3611-7363. E-mail: [email protected](3) Departamento de Engenharia de Biossistemas/Escola Superior de Agricultura “Luiz de Queiroz” USP, Av. Pádua Dias, 11, CEP 13.418-900, Piracicaba/SP, E-mail(s): [email protected], [email protected]; (4) Campus Curitibanos, Universidade Federal de Santa Catarina, Curitibanos, SC. [email protected] (5) Universidade Federal de Mato Grosso UFMT, campus Sinop, Avenida Alexandre Ferronato Nº 1.200. Bairro: Setor Industrial. CEP: 78.550-000,  Sinop-MT, Email: [email protected] (6) Empresa Brasileira de Pesquisa Agropecuária, Agropecuária Oeste. Rodovia BR 163, km 253, Zona Rural, 79804970 - Dourados, MS,  Email: [email protected]  1 RESUMO  O objetivo da pesquisa foi acompanhar a variação da condição hídrica do solo e da planta de pimenta ‘Tabasco’ em função dos manejos de déficits hídricos impostos e determinar seu coeficiente de estresse hídrico. O experimento foi conduzido em ambiente protegido, no Departamento de Engenharia de Biossistemas da ESALQ - USP, Piracicaba-SP, de setembro de 2009 a julho de 2010. O delineamento experimental foi blocos casualizados, com quatro repetições, utilizando-se lâminas de irrigação a 100, 80, 60 e 40% da evapotranspiração da cultura diferenciadas a partir da fase vegetativa e da fase reprodutiva. O potencial da água na folha e no solo foi aferido com a câmara de pressão e tensiômetros, respectivamente. Houve variação do potencial mátrico, da extração de água no solo e do potencial de água na folha em função das lâminas e das épocas de diferenciação. Menores potenciais mátricos foram verificados quando o déficit de irrigação foi inicializado na fase vegetativa da pimenta. Os valores de coeficiente de estresse hídrico e o potencial de água na folha, ao alvorecer, indicaram que as pimenteiras estavam sob estresse moderado e severo, sendo a época reprodutiva da pimenta Tabasco a mais sensível à restrição hídrica.Palavras-chave: Capsicum frutencens L, tensiômetro, potencial da água no solo.                                                        MARINHO, L. B.; FRIZZONE, J. A.; TOLENTINO JÚNIOR, J. B.; PAULINO, J.; FLUMIGNAN, D. L.; GÓES, D. B.WATER DYNAMICS IN SOIL-PLANT SYSTEM IN THE CULTIVATION OF PEPPER TABASCO UNDER WATER DEFICIT  2 ABSTRACT The objective of the research was to determine the change in soil water condition and in Tabasco pepper plant according to the managements of water deficits. The experiment was conducted in a greenhouse at the Department of Biosystems Engineering of ESALQ - USP, Piracicaba-SP, from September 2009 to July 2010. The experimental design was randomized blocks with four replications, using irrigation depths to 100, 80, 60 and 40% of crop evapotranspiration in the vegetative phase and reproductive phase. The soil matric potential was measured by tensiometers installed at 0-20 and 20-40 cm depth. The most negative values of matric potential occurred in treatments submitted to the greater water deficit treatments that had higher water restriction imposed by the vegetative phase. For these, greater increase in water extraction in the deepest layer (40 cm) were also found.There were differences in matric potential of the soil, in ground water extraction and in leaf water potential in relation to the water depths and differentiation phases. The deficit irrigation that started in the vegetative phase led to greater reduction in soil matric potential due to the accumulated water deficit. The pepper plants have moderate to severe sensitivity to water deficit in the soil, with a higher sensitivity of the plants when water restriction is imposed during reproductive stages than when it is imposed during growing stages. Keywords : Capsicum frutencens, tensiometer; soil water potential

scholarly journals Two-Dimensional Accretion Disk Models of a Neutron Star

1998 ◽  
Vol 188 ◽  
pp. 374-375
Author(s):  
M. Fujita ◽  
T. Okuda
Keyword(s):  
Neutron Star ◽  
Electron Scattering ◽  
Radiation Transport ◽  
Compact Object ◽  
Compact Objects ◽  
High Mass ◽  
Two Dimensional ◽  
Accretion Rates ◽  
The Difference ◽  
Characteristic Features

We investigate the accretion disks around compact objects with high mass accretion rates near the Eddington's critical value ME, where radiation pressure and electron scattering are dominant. This raises next problems: (a) whether stable disks could exist in relation to the theory of thermal instabilities of the disk and (b) what characteristic features the disks have if the stable disks exist. A non-rotating neutron star with the mass M = 1.4M⊙, radius R* = 107cm and the accretion rate Mac = 2.0 and 0.5Mac (models 1 and 2) is considered as the compact object. We assume the α-model for the viscosity and solve the set of two-dimensional time-dependent hydrodynamic equations coupled with radiation transport. The numerical method used is basically the same as one described by Kley and Hensler (1987) and Kley (1989) but we include some improvements in solving the difference equations (Okuda et al. 1997). The initial configuration consists of a cold, dense, and optically thick disk which is given by the standard α-model (Shakura and Sunyaev 1973) and a rarefied optically thin atmosphere around the disk.

Soil water matric potential rather than water content determines drought responses in field-grown lupin (Lupinus angustifolius)

1998 ◽  
Vol 25 (3) ◽  
pp. 353 ◽  
Author(s):  
C.R. Jensen ◽  
V.O. Mogensen ◽  
H.-H. Poulsen ◽  
I.E. Henson ◽  
S. Aagot ◽  
...  
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Soil Water ◽  
Stomatal Closure ◽  
Soil Water Potential ◽  
Root Surface ◽  
Lupinus Angustifolius ◽  
Soil Drying ◽  
Matric Potential ◽  
Aba Content

Drought responses in leaves of lupin (Lupinus angustifolius L., cv. Polonez) were investigated in plants grown in lysimeters either in a sand or in a loam soil in the field. Abscisic acid (ABA) content, water potential (ψl) and conductance to water vapour (gH2O) were determined in leaves of both irrigated plants and in plants exposed to gradual soil drying. Amorning-peak of leaf ABA content was found in both fully watered and droughted plants. During soil drying which, on both soils types, only decreased soil water potential of the upper soil layers, mid-day leaf ABA content increased relative to that in fully irrigated plants before any appreciable decreases occurred in ψl. In the part of the soil profile from which water was taken up (0–60 cm depth), gH2O decreased when the relative available soil water content (RASW) on sand was below 12% and RASW on loam, below 30%. At this point the average soil water matric potential (ψsoil) on sand was less than –0.13 MPa and the fraction of roots in ‘wet’ soil was 0.12, while on loam, the fraction of roots in ‘wet’ soil was 0.44 while y soil was similar to that on sand. A critical leaf ABA content of 300–400 ng/g FW was associated with the onset of stomatal closure on both soil types. We suggest that the initial stomatal closure is controlled by ABA which originates from the roots where its production is closely related to ψsoiland the water potential of the root surface and that ψsoil is a more important parameter than RASW or the fraction of roots in ‘wet’ soil for affecting leaf gas exchange. Further drying on both soils led to further increases in leaf ABA and declines in ψl and gH2O. In order to gain further insight, experiments should be designed which combine signalling studies with simulation studies, which take account of soil water potential, root contact area and water flux when calculating the water status at the root surface in the soil-plant-atmosphere-continuum.

Corrigenda - Measurement of the total water potential of aqueous solutions of polyethylene glycol - A comparison between osmometer, thermocouple psychrometer and equilibrated soil cores

Soil Research ◽  
1993 ◽  
Vol 31 (1) ◽  
pp. 1
Author(s):  
IM Wood ◽  
IK Dart ◽  
HB So
Keyword(s):  
Polyethylene Glycol ◽  
Water Potential ◽  
Close Correlation ◽  
Ease Of Use ◽  
Effect Of Temperature ◽  
Soil Cores ◽  
Total Water ◽  
Matric Potential ◽  
Thermocouple Psychrometer ◽  
Water Potentials

This study examined two polyethylene glycol (PEG) polymers (PEG 6000 and PEG 10000) and compared measurements of water potential obtained with a thermocouple osmometer and thermocouple psychrometers at three temperatures (15, 25 and 35�C) and five osmdalities (50, 100, 200, 300 and 400 g/1000 g water). These were then compared with estimates of matric potential of three soils brought to equilibrium with PEG solutions of the same osmolalities. At the same osmolality and temperature the two PEG polymers gave essentially the same water potential. There was a significant effect of temperature on water potential which corresponded closely with changes in specific gravity of the PEG solution. There was a close correlation between the measurements of water potential of the PEG solutions obtained with the osmometer and the psychrometers (R = 0.99). However, the psychrometer gave increasingly lower values than the osmometer as water potential decreased. The differences in the measurements between the two methods are thought to be the result of design and calibration differences. The ease of use of the osmometer is such that it is recommended for routine use. The water potentials of the soil cores brought to equilibrium with the PEG 10 000 solution were linearly related to the water potentials of the PEG solutions estimated from both the osmometer and psychrometers (R2 = 0.84). However, there were clear deviations from a 1:l relationship. It was concluded that the results from the soil cores could not be used to determine which of the two instruments gave the more accurate measurement of water potential of PEG solutions.

What is the role of tortuosity in the Kozeny-Carman equation?

2017 ◽  
Vol 5 (1) ◽  
pp. SB57-SB67 ◽  
Author(s):  
Nattavadee Srisutthiyakorn ◽  
Gerald M. Mavko
Keyword(s):  
Porous Media ◽  
Pore Space ◽  
Flow Simulation ◽  
Weighted Average ◽  
Rock Physics ◽  
Sample Length ◽  
Pore Throat ◽  
Binary Images ◽  
The Difference ◽  
Definition Of

Hydraulic tortuosity is an important parameter in characterizing fluid-flow heterogeneity in porous media. The most basic definition of tortuosity is the ratio of the average flow path length to the sample length. Although this definition seems straightforward, the lack of understanding and the lack of proper ways to measure tortuosity make it one of the most abused parameters in rock physics. Hydraulic tortuosity is often treated merely as a fitting factor, or worse, it is neglected by being combined with a geometric factor in the Kozeny-Carman (KC) equation. Often, the tortuosity is obtained from laboratory measurements of porosity, permeability, and specific surface area by inverting the KC equation. This approach has a major pitfall because it treats tortuosity as a fitting factor, and the inverted tortuosity is often unphysically high. In contrast, we obtained the tortuosity from 3D segmented binary images of porous media using streamlines extracted from a local flux, the output from the lattice Boltzmann method (LBM) flow simulation. After obtaining streamlines from each sample, we calculated the distribution of tortuosities and flux-weighted average tortuosity. With the tortuosity measurement from streamlines, every parameter in the KC equation can be measured accurately from 3D segmented binary images. We found, however, that the KC equation is still missing some important geometric information needed to predict permeability. With known parameters and without a fitting factor, the KC equation predicts permeability higher by one to two orders of magnitude than that predicted by the LBM. We searched for a missing parameter by exploring various concepts such as connected pore space and pore throat distribution. We found that the connected pore space does not contribute to the difference between the KC permeability and LBM permeability, whereas, as we learn with sinusoidal pipe examples, the pore throat distribution captures what is missing from the KC equation.

Evaporation from porous media as influenced by osmotic potential

2020 ◽  
Author(s):  
Adil Salman ◽  
Deep Joshi ◽  
Mahyar Naseri ◽  
Wolfgang Durner
Keyword(s):  
Porous Media ◽  
Water Potential ◽  
Osmotic Potential ◽  
Soil Surface ◽  
Natural Soil ◽  
Total Water ◽  
Matric Potential ◽  
Model Calculations ◽  
Two Stages ◽  
Saline Solutions

<p>The measurement of the water potential is important to characterize solute transport in soil and water uptake by plants. Many researchers have characterized the matric potential and its impact on evaporation from porous media. However, only few studies have been carried out to characterize the effect of the osmotic potential. In this study, we investigated the simultaneous influences of the osmotic and matric potentials on the evaporation from soil. Our hypothesis was that both potential components affect the two stages of evaporation and that the osmotic potential in direct vicinity of the soil surface is a controlling variable. To meet our objective, we performed evaporation experiments on columns filled with pure quartz sand and natural soil materials with different textures, under climate-controlled laboratory conditions. The soils were initially saturated with different concentrations of saline solutions and evaporation from each column was measured daily. Our results show that the osmotic potential reduced the amount of evaporated water from the investigated porous media. The amount of reduction due to the osmotic potential is compared with model calculations that consider the total water potential at the soil surface.</p>

Viewpoint: Consideration of apoplastic water in plant organs: a reminder

2005 ◽  
Vol 32 (6) ◽  
pp. 561 ◽  
Author(s):  
Ian F. Wardlaw
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Solute Concentration ◽  
Pressure Chamber ◽  
Dilution Method ◽  
Water Fraction ◽  
Thermocouple Psychrometer ◽  
Relative Water ◽  
Cell Turgor ◽  
The Difference

The importance of apoplastic water was confirmed for the leaves of a range of species by a comparison of tissue solute concentrations determined by the extrapolation of water potential isotherms to 100% relative water content (symplastic solute concentration at full turgor) and concentrations derived more directly from frozen / thawed tissue, where there is dilution of the symplastic water fraction by the apoplastic water fraction. A thermocouple psychrometer was used for both water potential and solute potential measurements. Parallel measurements of the apoplastic water content, estimated by the extrapolation of pressure–volume curves to zero (1 / water potential) with a pressure chamber and measurements based on the dilution method, with a thermocouple psychrometer, showed that the two methods gave similar results. This lends support to the conclusion that water is lost from the symplast and not from the apoplast of leaves when these are subjected to increasing pressure in a pressure chamber. However, where tissues or organs are air-dried the loss of water occurs from both the symplast and apoplast. The overall data support the conclusion that the apoplastic water should not be ignored in plant water relations studies, particularly when estimating cell turgor indirectly from the difference between water potential and cell solute concentration based on the analysis of frozen / thawed tissue.

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