Novel Refractory Phase, Ta7Si2(SixB1–x)2

2013 ◽  
Vol 52 (19) ◽  
pp. 11295-11301 ◽  
Author(s):  
V. Romaka ◽  
V. Fosodeder ◽  
P. F. Rogl ◽  
É. C. T. Ramos ◽  
C. A. Nunes ◽  
...  
Keyword(s):  
Refractory Phase

scholarly journals The refractory phase in a reflex arc

1922 ◽  
Vol 56 (6) ◽  
pp. 426-443 ◽  
Author(s):  
E. D. Adrian ◽  
J. M. D. Olmsted
Keyword(s):  
Reflex Arc ◽  
Refractory Phase

Influence of photoperiod and gonadal status on food intake, adiposity, and gene expression of hypothalamic appetite regulators in a seasonal mammal

2007 ◽  
Vol 292 (1) ◽  
pp. R242-R252 ◽  
Author(s):  
Chantacha Anukulkitch ◽  
Alexandra Rao ◽  
Frank R. Dunshea ◽  
Dominique Blache ◽  
Gerald A. Lincoln ◽  
...  
Keyword(s):  
Gene Expression ◽  
Food Intake ◽  
Arcuate Nucleus ◽  
Leptin Receptor ◽  
Reproductive Axis ◽  
Pomc Gene ◽  
Gonadal Status ◽  
Long Photoperiod ◽  
Refractory Phase

We studied the effects of photoperiod on metabolic profiles, adiposity, and gene expression of hypothalamic appetite-regulating peptides in gonad-intact and castrated Soay rams. Groups of five to six animals were studied 6, 18, or 30 wk after switching from long photoperiod (LP: 16 h of light) to short photoperiod (SP: 8 h of light). Reproductive and metabolic indexes were measured in blood plasma. Expression of neuropeptide Y (NPY), proopiomelanocortin (POMC), and leptin receptor (ObRb) in the arcuate nucleus was measured using in situ hybridization. Testosterone levels of intact animals were low under LP, increased to a peak at 16 wk under SP, and then declined. Voluntary food intake (VFI) was high under LP in both intact and castrated animals, decreased to a nadir at 12–16 wk under SP, and then recovered, but only in intact rams as the reproductive axis became photorefractory to SP. NPY gene expression varied positively and POMC expression varied negatively with the cycle in VFI, with differences between intact and castrate rams in the refractory phase. ObRb expression decreased under SP, unrelated to changes in VFI. Visceral fat weight also varied between the intact and castrated animals across the cycle. We conclude that 1) photoperiodic changes in VFI reflect changes in NPY and POMC gene expression, 2) changes in ObRb gene expression are not necessarily determinants of changes in VFI, 3) gonadal status affects the pattern of VFI that changes with photoperiod, and 4) in the absence of gonadal factors, animals can eat less but gain adiposity.

scholarly journals Effect of external lighting on biopotential of maize leaves caused by pulsed temperature stimulation

2017 ◽  
Vol 8 (2) ◽  
pp. 179-184
Author(s):  
M. P. Motsnyj ◽  
N. P. Botsva ◽  
О. V. Elina ◽  
D. V. Chernetchenko ◽  
L. Y. Sadovskaya ◽  
...  
Keyword(s):  
Computer Software ◽  
Plant Cells ◽  
Cold Stimulation ◽  
Time Period ◽  
The Stability ◽  
Adaptive Ability ◽  
And Behavior ◽  
External Stimuli ◽  
Temperature Stimulation ◽  
Refractory Phase

Study of electrophysiological indicators of the condition and behavior of plants has become more important in the development of farming activities and the search for effective ways to improve the productivity of crops. The influence of external light on the adaptive ability of corn leaf cells to rhythmic cold stimulation was determined experimentally. The method of rhythmic cold stimulation is not adequate for the studied plants, but its application allows us to evaluate the stability of plant cells to external stimuli. The method consists in repeating irritation during the time period of less duration than the relative refractory phase, which causes a response of less than the previous amplitude. Because of this in the system there is a negative feedback that leads to stabilization of the amplitude of biopotentials that are registered. Rhythmic cold stimulation was applied to the leaf with the help of a quick-response thermostimulator. Rhythmic cold stimuli and settings of pulses were set by computer software. Cooling temperature was controlled using miniature differential thermocouple. Potentials of the leaf surface were diverted by an unpolarized macroelectrode and after a preamplifier fed to the input of the USB oscilloscope connected to the computer. Analysis of the results of experiments was performed using automated developed software. As a result, we experimentally established that rhythmic stimulation of leaves by cold leads to stabilization of responding potential. The level of stabilization depends on the frequency of cold stimuli and describes the adaptive properties of the system causing the biopotential. We found that the absence of photosynthesis when there is a deficit outdoor lighting leads to a significant increase in the average level of stabilized responses, indicating increased stability of the system to external influences. The maximum of this increase fell on the fourth day. This increase is likely to be due to the restructuring of functional ion transport through cell membranes, generating potentials registered. In the interval 4–9th days there was a significant decrease in stabilization, probably due to adaptation of plant cells to a lack of light, or depletion of ATP, which provides the active transport of ions across the cell membrane. 

Crystallizing Y2Si2O7 at the grain boundaries of a Si3N4 ceramic

1988 ◽  
Vol 46 ◽  
pp. 608-609
Author(s):  
G. E. Hiltnas ◽  
W. E. Lee
Keyword(s):  
High Temperature ◽  
Grain Boundaries ◽  
Sintered Specimen ◽  
Sintering Process ◽  
Si3n4 Ceramic ◽  
High Temperature Properties ◽  
Growth Defects ◽  
Simple Growth ◽  
Refractory Phase

Improving the high temperature properties of Si3N4 containing glass at the grain boundaries may be possible by crystallizing the glass to a refractory phase as first suggested by Tsuge et al. AEM has recently been used to examine the morphology of cordierite (Mg2Al4Si5O18) and garnet (Y3Al5O12) crystallized at the grain boundaries of SiAlON ceramics. We present here results of an AEM investigation of the morphology of Y2Si2O7 crystallized from a 6 weight % Y2O3-Si3N4 ceramic.Bars were isostatically pressed and then sintered at 2140°C for 2 hours in 50 atm N2. Crystallization was at 1500°C in 50 atm N2 for various times up to 20 hours. Microscopy samples were prepared using conventional techniques and examined in a JEOL 200CX AEM.The microstructure of an as-sintered specimen is shown in Figure 1. A few of the hexagonal β-Si3N4 grains contain dislocations (arrowed). These are most likely simple growth defects from the a →β-Si3N4 solution-reprecipitation sintering process.

Kinematics of Pectoral Fin Propulsion in Cymatogaster Aggregata

1973 ◽  
Vol 59 (3) ◽  
pp. 697-710 ◽  
Author(s):  
P. W. WEBB
Keyword(s):  
Swimming Speed ◽  
Performance Test ◽  
Beat Frequency ◽  
The Body ◽  
Fish Swimming ◽  
Pectoral Fin ◽  
Caudal Fin ◽  
Lift Forces ◽  
Time Of Year ◽  
Refractory Phase

1. The kinematics of pectoral-fin propulsion have been measured for Cymatogaster aggregata, 14·3 cm in length, during an increasing-velocity performance test. Acclimation and test temperature was 15 °C, similar to the fishes' normal environmental temperature for the time of year of the tests. 2. Locomotion was in the labriform mode. Within this mode two pectoral-fin patterns were observed, differing only in the details of fin kinematics. These differences resulted from the length of the propagated wave passed over the fin. At low swimming speeds, up to about 2 L/sec, the wavelength was relatively short, approximately twice the length of the trailing edge of the fin. At higher speeds, a wave of very much longer wavelength was passed over the fin. 3. The pectoral fin-beat cycle was divisible into abduction, adduction and refractory phases. Abduction and adduction phases were of equal duration, and the proportion of time occupied by these phases increased with swimming speed. The duration of the refractory phase decreased with increasing speed. 4. The kinematics indicated that thrust was generated throughout abduction and adduction phases, together with lift forces that cancelled out over a complete cycle. As a result of lift forces and the refractory phase the body moved in a figure-8 motion relative to the flow. 5. Pectoral fin-beat frequency and amplitude increased with swimming speed, and the product of frequencyxamplitude was linearly related to swimming speed. 6. Interactions between pectoral fin-beat frequency, amplitude, refractory phase and kinematic patterns were interpreted as a mechanism to permit the propulsive muscles to operate at optimum efficiency and power output over a wider range of swimming speeds than would otherwise be possible. 7. Pectoral-fin propulsion was augmented by caudal-fin propulsion only at swimming speeds greater than 3·4 L/sec. 8. The mean 45 min critical swimming speed was 3·94 L/sec, and compares favourably with similar levels of activity for fish swimming by means of body and caudal-fin movements.

Causes of the refractory-phase formation during melting of Al-Nb-Si master alloys

2010 ◽  
Vol 2010 (1) ◽  
pp. 1-5
Author(s):  
I. A. Pan’kov ◽  
V. M. Chumarev ◽  
V. P. Mar’evich ◽  
N. I. Sel’menskikh ◽  
L. Yu. Udoeva ◽  
...  
Keyword(s):  
Phase Formation ◽  
Master Alloys ◽  
Refractory Phase

scholarly journals A phenomenon in vision similar to refractory phase.

1926 ◽  
Vol 36 (2) ◽  
pp. 1-17 ◽  
Author(s):  
Roland C. Travis
Keyword(s):  
Refractory Phase
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