scholarly journals Modulation of nickel-induced bursting with 4-aminopyridine in leech retzius nerve cells

2010 ◽  
Vol 62 (4) ◽  
pp. 1035-1045 ◽  
Author(s):  
Dhruba Pathak ◽  
S. Lopicic ◽  
Marija Bratic-Stanojevic ◽  
D. Pavlovic ◽  
P.R. Andjus ◽  
...  
Keyword(s):  
Characteristic Feature ◽  
Nerve Cells ◽  
Phase Effect ◽  
Two Phase ◽  
Cellular Basis ◽  
Paroxysmal Depolarization Shift

Paroxysmal depolarization shift has been identified as a characteristic feature of the cellular basis of epilepsy. On Na+-dependent bursting, 1 mmol/l 4-aminopyridine (4-AP) produced a two-phase effect - a significant depolarization accompanied by an increase in the frequency of bursting, followed by repolarization along with a diminished frequency of bursting. Neither 1 ?mol/l apamin nor 150 nmol/l charybdotoxin (ChTX) elicited any significant effect on either bursting or standard conditions. Our results suggest that 4-AP affects the bursting indirectly by altering the excitability of the cell. The lack of effects of apamin and ChTX is probably due to channel insensitivity to these blockers in leech.

Calculating Method for the Solid Phase Effect Coefficient of the Solid-Fluid Two Phase Flow Centrifugal Pump

2010 ◽  
Vol 29-32 ◽  
pp. 658-663
Author(s):  
Chuan Jun Li ◽  
Gang Yu ◽  
Xin Wang
Keyword(s):  
Differential Equation ◽  
Centrifugal Pump ◽  
Two Phase Flow ◽  
Solid Phase ◽  
High Accuracy ◽  
Phase Flow ◽  
Phase Effect ◽  
Two Phase ◽  
Error Band ◽  
Calculating Method

In order to acquire the solid-fluid two phase flow centrifugal pump’s slurry head according with the fact, the solid phase effect coefficient must be calculated precisely. By analysising the acting forces on the solid particle, its moving differential equation was established. And the calculating formula of the solid phase effect coefficient was deduced based on the equation. For the sake of verifying its validity, a test of contrast and comparison on the calculating slurry heads by some ways was carried out. The results shows that the relative error values of the slurry head calculated are less than 2.00% with a small and stably error band. The method has the advantage of simple calculating process, high accuracy, low randomness and good practicability.

Near Wellbore Two-Phase Effect of a Light Oil Field

2018 ◽  
Author(s):  
Zhaocong Zhou ◽  
Andrea Lamberti ◽  
Andrea Locci ◽  
Valerio Parasiliti ◽  
Paolo Prevosti ◽  
...  
Keyword(s):  
Oil Field ◽  
Phase Effect ◽  
Two Phase ◽  
Light Oil

Effect of Shock Loading on the Microstructure of Uniloy 326

1974 ◽  
Vol 32 ◽  
pp. 504-505
Author(s):  
K. P. Staudhammer ◽  
L. E. Murr
Keyword(s):  
Grain Size ◽  
Shock Loading ◽  
Current Investigation ◽  
Two Phase ◽  
05 C ◽  
Shock Deformation ◽  
Heat Treated

The effect of shock loading on a variety of steels has been reviewed recently by Leslie. It is generally observed that significant changes in microstructure and microhardness are produced by explosive shock deformation. While the effect of shock loading on austenitic, ferritic, martensitic, and pearlitic structures has been investigated, there have been no systematic studies of the shock-loading of microduplex structures.In the current investigation, the shock-loading response of millrolled and heat-treated Uniloy 326 (thickness 60 mil) having a residual grain size of 1 to 2μ before shock loading was studied. Uniloy 326 is a two phase (microduplex) alloy consisting of 30% austenite (γ) in a ferrite (α) matrix; with the composition.3% Ti, 1% Mn, .6% Si,.05% C, 6% Ni, 26% Cr, balance Fe.

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

Shock consolidation of Ni-Ti alloy powder

1986 ◽  
Vol 44 ◽  
pp. 430-431
Author(s):  
Naresh N. Thadhani ◽  
Thad Vreeland ◽  
Thomas J. Ahrens
Keyword(s):  
Alloy Powder ◽  
Amorphous Material ◽  
Ti Alloy ◽  
Two Phase ◽  
Near Surface ◽  
Optical Micrograph ◽  
Shock Compaction ◽  
Powder Particles ◽  
Ti Powder ◽  
Rapidly Solidified

A spherically-shaped, microcrystalline Ni-Ti alloy powder having fairly nonhomogeneous particle size distribution and chemical composition was consolidated with shock input energy of 316 kJ/kg. In the process of consolidation, shock energy is preferentially input at particle surfaces, resulting in melting of near-surface material and interparticle welding. The Ni-Ti powder particles were 2-60 μm in diameter (Fig. 1). About 30-40% of the powder particles were Ni-65wt% and balance were Ni-45wt%Ti (estimated by EMPA).Upon shock compaction, the two phase Ni-Ti powder particles were bonded together by the interparticle melt which rapidly solidified, usually to amorphous material. Fig. 2 is an optical micrograph (in plane of shock) of the consolidated Ni-Ti alloy powder, showing the particles with different etching contrast.

A Comparison of Tem and Apfim to the Interpretation of Modulated Microstructures

1985 ◽  
Vol 43 ◽  
pp. 70-71
Author(s):  
M.G. Burke ◽  
M.K. Miller
Keyword(s):  
Low Temperature ◽  
Microstructural Characterization ◽  
Superlattice Reflection ◽  
High Volume ◽  
Atom Probe ◽  
Dark Field ◽  
Miscibility Gap ◽  
Second Phase ◽  
Two Phase ◽  
Probe Field

Interpretation of fine-scale microstructures containing high volume fractions of second phase is complex. In particular, microstructures developed through decomposition within low temperature miscibility gaps may be extremely fine. This paper compares the morphological interpretations of such complex microstructures by the high-resolution techniques of TEM and atom probe field-ion microscopy (APFIM).The Fe-25 at% Be alloy selected for this study was aged within the low temperature miscibility gap to form a <100> aligned two-phase microstructure. This triaxially modulated microstructure is composed of an Fe-rich ferrite phase and a B2-ordered Be-enriched phase. The microstructural characterization through conventional bright-field TEM is inadequate because of the many contributions to image contrast. The ordering reaction which accompanies spinodal decomposition in this alloy permits simplification of the image by the use of the centered dark field technique to image just one phase. A CDF image formed with a B2 superlattice reflection is shown in fig. 1. In this CDF micrograph, the the B2-ordered Be-enriched phase appears as bright regions in the darkly-imaging ferrite. By examining the specimen in a [001] orientation, the <100> nature of the modulations is evident.

A TEM study of the influence of microstructure on the superplastic behavior of a U-5.8 wt.% Nb alloy

1986 ◽  
Vol 44 ◽  
pp. 568-569
Author(s):  
G. Mackiewicz Ludtka
Keyword(s):  
Grain Size ◽  
Heating Rate ◽  
Phase Field ◽  
Single Phase ◽  
Superplastic Behavior ◽  
Two Phase ◽  
Single Phase Field

Historically, metals exhibit superplasticity only while forming in a two-phase field because a two-phase microstructure helps ensure a fine, stable grain size. In the U-5.8 Nb alloy, superplastici ty exists for up to 2 h in the single phase field (γ1) at 670°C. This is above the equilibrium monotectoid temperature of 647°C. Utilizing dilatometry, the superplastic (SP) U-5.8 Nb alloy requires superheating to 658°C to initiate the α+γ2 → γ1 transformation at a heating rate of 1.5°C/s. Hence, the U-5.8 Nb alloy exhibits an anomolous superplastic behavior.

Transition alpha structure in beta-isomorphous Nb-Hf alloys

1987 ◽  
Vol 45 ◽  
pp. 232-233
Author(s):  
R.W. Carpenter ◽  
Changhai Li ◽  
David J. Smith
Keyword(s):  
Solid Solution ◽  
Solution Phase ◽  
Miscibility Gap ◽  
Large Strains ◽  
Solid Solution Phase ◽  
Two Phase ◽  
Diffuse Intensity ◽  
Metastable Form ◽  
The Matrix ◽  
Equilibrium Morphology

Binary Nb-Hf alloys exhibit a wide bcc solid solution phase field at temperatures above the Hfα→ß transition (2023K) and a two phase bcc+hcp field at lower temperatures. The β solvus exhibits a small slope above about 1500K, suggesting the possible existence of a miscibility gap. An earlier investigation showed that two morphological forms of precipitate occur during the bcc→hcp transformation. The equilibrium morphology is rod-type with axes along <113> bcc. The crystallographic habit of the rod precipitate follows the Burgers relations: {110}||{0001}, <112> || <1010>. The earlier metastable form, transition α, occurs as thin discs with {100} habit. The {100} discs induce large strains in the matrix. Selected area diffraction examination of regions ∼2 microns in diameter containing many disc precipitates showed that, a diffuse intensity distribution whose symmetry resembled the distribution of equilibrium α Bragg spots was associated with the disc precipitate.

The brain structure and neurosecretory cells of noctuid moth Anadevidia peponis: Noctuidae

1990 ◽  
Vol 48 (3) ◽  
pp. 436-437
Author(s):  
M. Sato ◽  
Y. Ogawa ◽  
M. Sasaki ◽  
T. Matsuo
Keyword(s):  
Biological Clock ◽  
Virgin Female ◽  
Basic Structure ◽  
Fixed Time ◽  
Neurosecretory Cells ◽  
Nerve Cells ◽  
Noctuid Moth ◽  
The Right ◽  
20 Nm ◽  
The Brain

A virgin female of the noctuid moth, a kind of noctuidae that eats cucumis, etc. performs calling at a fixed time of each day, depending on the length of a day. The photoreceptors that induce this calling are located around the neurosecretory cells (NSC) in the central portion of the protocerebrum. Besides, it is considered that the female’s biological clock is located also in the cerebral lobe. In order to elucidate the calling and the function of the biological clock, it is necessary to clarify the basic structure of the brain. The observation results of 12 or 30 day-old noctuid moths showed that their brains are basically composed of an outer and an inner portion-neural lamella (about 2.5 μm) of collagen fibril and perineurium cells. Furthermore, nerve cells surround the cerebral lobes, in which NSCs, mushroom bodies, and central nerve cells, etc. are observed. The NSCs are large-sized (20 to 30 μm dia.) cells, which are located in the pons intercerebralis of the head section and at the rear of the mushroom body (two each on the right and left). Furthermore, the cells were classified into two types: one having many free ribosoms 15 to 20 nm in dia. and the other having granules 150 to 350 nm in dia. (Fig. 1).

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