Further theoretical analysis of concentration–pressure–flux waves in phloem transport systems

1978 ◽  
Vol 56 (8) ◽  
pp. 1086-1090 ◽  
Author(s):  
Jack M. Ferrier
Keyword(s):  
Hydrostatic Pressure ◽  
Water Flux ◽  
Sieve Tube ◽  
Phloem Transport ◽  
Time Dependent ◽  
Transport Systems ◽  
Flux Variation ◽  
Complex Interactions ◽  
Theoretical Results ◽  
Sugar Source

Theoretical results show that waves involving complex interactions between osmotic pressure, hydrostatic pressure, and fluxes of water and solute can occur in any phloem transport system surrounded by a semipermeable membrane. These results show that such waves can travel from sugar sink to sugar source as well as from sugar source to sugar sink. The time-dependent sugar concentration variation is shown to be caused largely by the time-dependent variation of the gradient of mass flow velocity in the sieve tube which is produced by the time-dependent variation of water flux across the membrane. This water flux variation is produced by a slight phase difference between osmotic and hydrostatic pressure variation. It is proposed that this phenomenon be called the concentration–pressure–flux (CPJ) wave.

scholarly journals Theoretical and experimental comparative studies of nonlinear optical properties for selected melaminium compounds

2010 ◽  
Vol 8 (6) ◽  
pp. 1192-1202 ◽  
Author(s):  
Marek Drozd ◽  
Mariusz Marchewka
Keyword(s):  
Optical Properties ◽  
Acetic Acid ◽  
Nonlinear Optical ◽  
Time Dependent ◽  
X Ray ◽  
Hartree Fock ◽  
Optical Applications ◽  
Experimental Values ◽  
Nonlinear Optical Applications ◽  
Theoretical Results

AbstractThe bis(melaminium) sulphate dihydrate, 2,4,6-triamine-1,3,5-triazin-1,3-ium tartrate monohydrate, 2,4,6-triamine-1,3,5-triazin-1-ium hydrogenphthalate, 2,4,6-triamine-1,3,5-triazin-1-ium acetate acetic acid solvate monohydrate, 2,4,6-triamine-1,3,5-triazin-1-ium bis(selenate) trihydrate, melaminium diperchlorate hydrate, melaminium bis(trichloroacetate) monohydrate and melaminium bis(4-hydroxybenzenesulphonate) dihydrate were discovered recently as perspective materials for nonlinear optical applications. On the basis of X-ray structures for eight melaminium compounds the time dependent Hartree Fock (TDHF) method was used for calculation of the polarizability, and first and second hyperpolarizability. Detailed directional studies of calculated hyperpolarizability for all investigated melaminium compounds are shown. The theoretical results are compared with experimental values of β.

A time-dependent mathematical expression of the münch hypothesis of phloem transport

1980 ◽  
Vol 86 (3) ◽  
pp. 493-505 ◽  
Author(s):  
K.C. Smith ◽  
C.E. Magnuson ◽  
J.D. Goeschl ◽  
D.W. DeMichele
Keyword(s):  
Mathematical Expression ◽  
Phloem Transport ◽  
Time Dependent

An Interpretation on Kinetics of Martensitic Transformation

2011 ◽  
Vol 172-174 ◽  
pp. 90-98 ◽  
Author(s):  
Tomoyuki Kakeshita ◽  
Takashi Fukuda ◽  
Yong-Hee Lee
Keyword(s):  
Magnetic Field ◽  
Hydrostatic Pressure ◽  
Martensitic Transformation ◽  
Magnetic Fields ◽  
Martensitic Transformations ◽  
Phenomenological Theory ◽  
Time Dependent ◽  
Isothermal Process ◽  
Kinetics Of ◽  
Transformation Processes

We have investigated athermal and isothermal martensitic transformations (typical displacive transformations) in Fe–Ni, Fe–Ni–Cr, and Ni-Co-Mn-In alloys under magnetic fields and hydrostatic pressures in order to understand the time-dependent nature of martensitic transformation, that is, the kinetics of martensitic transformation. We have confirmed that the two transformation processes are closely related to each other, that is, the athermal process changes to the isothermal process and the isothermal process changes to the athermal one under a hydrostatic pressure or a magnetic field. These findings can be explained by the phenomenological theory, which gives a unified explanation for the two transformation processes previously proposed by our group.

Unsteady convective diffusion with interphase mass transfer

1973 ◽  
Vol 333 (1592) ◽  
pp. 115-132 ◽  
Keyword(s):  
Dispersion Model ◽  
Reaction Rates ◽  
The Other ◽  
Time Dependent ◽  
Transport Systems ◽  
Exchange Coefficient ◽  
Dispersion Coefficients ◽  
Interfacial Transport ◽  
Order Of Magnitude ◽  
Proper Values

The theory of miscible dispersion is extended to interphase transport systems. As a specific example miscible dispersion in laminar flow in a tube in the presence of interfacial transport due to an irreversible first-order reaction at the wall is analysed by an exact procedure. A new exact dispersion model which accounts for dispersion with interphase transport is derived from first principles. The new concept of an ‘exchange coefficient’ arises naturally. This coefficient depends strongly on the rate of interfacial transport. Such transport also affects the convection and dispersion coefficients significantly. A general expression is derived which shows clearly the time-dependent nature of the coefficients in the dispersion model. The complete time-dependent expression for the exchange coefficient is obtained explicitly and is independent of the velocity distribution in the flow; however, it does depend on the initial solute distribution. Because of the complexity of the problem only asymptotic large-time evaluations are made for the convection and dispersion coefficients, but these are sufficient to give useful physical insight into the nature of the problem. When the rate of the wall reaction approaches zero the exchange coefficient also approaches zero and the other two coefficients approach their proper values in the absence of interfacial transport. At the other extreme of rapid wall reaction rates, the convection coefficient is more than 50 % larger than its value in the absence of interfacial transport and the dispersion coefficient is an order of magnitude smaller than that for zero interphase transport.

Band Gap Shift of GaN under Uniaxial Strain Compression

2001 ◽  
Vol 693 ◽  
Author(s):  
H. Y. Peng ◽  
M. D. McCluskey ◽  
Y. M. Gupta ◽  
M. Kneissl ◽  
N. M. Johnson
Keyword(s):  
Shock Wave ◽  
Hydrostatic Pressure ◽  
Band Gap ◽  
Uniaxial Strain ◽  
Biaxial Stress ◽  
Time Dependent ◽  
Time Resolved ◽  
Piezoelectric Field ◽  
Slow Band ◽  
Absorption Measurements

AbstractThe band-gap shift of GaN:Mg epilayers on (0001)-oriented sapphire was studied as a function of uniaxial strain compression along the c-axis using time-resolved, optical absorption measurements in shock wave experiments. For longitudinal stresses ranging from 4 to 14 GPa, the band gap shift is approximately 0.026 eV/GPa. Combining this result with the known behavior of wurtzite GaN under hydrostatic pressure and biaxial stress, a new set of deformation potentials has been estimated: acz-D1 = -10.2 eV, act-D2 = -7.9 eV, D3 = 1.33 eV and D4 = -0.74 eV. A slow band gap shift is also observed following the immediate band gap increase upon impact. This phenomenon can be explained by a time-dependent screening of the piezoelectric field.

scholarly journals Cystine uptake by rat renal brush-border vesicles

1981 ◽  
Vol 194 (2) ◽  
pp. 443-449 ◽  
Author(s):  
P D McNamara ◽  
L M Pepe ◽  
S Segal
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Early Time ◽  
Membrane Vesicles ◽  
Time Dependent ◽  
Transport Systems ◽  
Cortical Tissue ◽  
High Affinity ◽  
Renal Cortical Tissue ◽  
Renal Brush Border

Uptake of L-cystine by brush-border membrane vesicles isolated from rat renal-cortical tissue was time-dependent and occurred in the absence of cystine reduction. A significant capacity for vesicular binding of cystine was observed. The amount bound increased with time of incubation and could be displaced by thiol reagents. At early time points, cystine uptake measured the transport of cystine into the intravesicular space. Total cystine uptake was mediated by multiple transport systems, including a low-Km high-affinity component which was shared by lysine, arginine, ornithine and glutamine and on which hetero-exchange diffusion of lysine and cystine was demonstrated.

Plasma membrane mediated thymidine transport in AKR spleen cells

1980 ◽  
Vol 58 (12) ◽  
pp. 1405-1413 ◽  
Author(s):  
Phyllis R. Strauss ◽  
James M. Sheehan ◽  
Judith Taylor
Keyword(s):  
Inbred Mouse ◽  
Lymphoid Cells ◽  
Time Dependent ◽  
Transport Systems ◽  
Mouse Strains ◽  
Spleen Cells ◽  
Con A ◽  
Thymidine Transport ◽  
Akr Mice

In this paper we characterize the thymidine transport systems in nonadherent spleen cells from normal leukemic (AKR) mice and from AKR mice which have been stimulated in vivo with concanavalin A (Con A). We have shown that splenic lymphocytes from normal AKR mice transport thymidine (two kinetic components, Km values of 34 μM and 1.6 mM) whereas lymphoid cells from C57L/J and outbred (CD-1) mice do not. Following Con A stimulation of AKR mice, three components (Km values of 6 μM, 212 μM, and millimolar range) were observed. The current data should be compared with previously published results for splenocytes from Con A stimulated CD-1 mice. Although those cells transport thymidine with two kinetic components (Km values of 160 μM and 4 mM), they lacked the lowest Km system present in AKR splenocytes.Thymidine transport was also examined in lymphocytes from several AK × L recombinant inbred mouse strains derived from the cross AKR/J × C57L/J. Two strains which lacked MuLV did not show time-dependent thymidine translocation whereas two strains which possessed MuLV demonstrated time-dependent thymidine translocation. Moreover, cells from the congenic strain L.AKR-Akv-2, which carried the Akv-2 genome on a C57L background, also showed thymidine transport. Thus a unique ability to transport thymidine can be correlated with the presence of the murine leukemia virus genome.

scholarly journals A Model of Icicle Growth

1988 ◽  
Vol 34 (116) ◽  
pp. 64-70 ◽  
Author(s):  
Lasse Makkonen
Keyword(s):  
Computer Model ◽  
Liquid Water ◽  
Water Flux ◽  
Laboratory Data ◽  
Time Dependent ◽  
Atmospheric Conditions ◽  
Model Based ◽  
Complicated Process

AbstractA theory of icicle growth is presented. It is shown that icicles elongate as hollow tubes of ice with liquid water trapped inside the tip. A time-dependent computer model based on the theory shows that the growth of an icicle is a complicated process, which is very sensitive to the atmospheric conditions and water flux. The shape and weight of icicles predicted by the model agree well with laboratory data.

scholarly journals Eulerian time-stepping schemes for the non-stationary Stokes equations on time-dependent domains

2022 ◽  
Author(s):  
Erik Burman ◽  
Stefan Frei ◽  
Andre Massing
Keyword(s):  
Parabolic Equation ◽  
Stokes Equations ◽  
A Priori ◽  
Time Dependent ◽  
Numerical Examples ◽  
Time Stepping ◽  
Discretisation Error ◽  
Moving Domains ◽  
Theoretical Results ◽  
Norm Error

AbstractThis article is concerned with the discretisation of the Stokes equations on time-dependent domains in an Eulerian coordinate framework. Our work can be seen as an extension of a recent paper by Lehrenfeld and Olshanskii (ESAIM: M2AN 53(2):585–614, 2019), where BDF-type time-stepping schemes are studied for a parabolic equation on moving domains. For space discretisation, a geometrically unfitted finite element discretisation is applied in combination with Nitsche’s method to impose boundary conditions. Physically undefined values of the solution at previous time-steps are extended implicitly by means of so-called ghost penalty stabilisations. We derive a complete a priori error analysis of the discretisation error in space and time, including optimal $$L^2(L^2)$$ L 2 ( L 2 ) -norm error bounds for the velocities. Finally, the theoretical results are substantiated with numerical examples.

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