SUPPRESSION OF SPIN FLUCTUATIONS IN YMn2 BY HYDROSTATIC PRESSURE

1993 ◽  
Vol 07 (01n03) ◽  
pp. 826-829 ◽  
Author(s):  
E. BAUER ◽  
I.S. DUBENKO ◽  
E. GRATZ ◽  
R. HAUSER ◽  
A. MARKOSYAN ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Neutron Diffraction ◽  
Pressure Dependence ◽  
Ambient Pressure ◽  
Paramagnetic State ◽  
Spin Fluctuations ◽  
Interatomic Distances ◽  
Effective Moment ◽  
Large Pressure ◽  
Phase Compound

The cubic Laves phase compound YMn2 exhibits a huge spontaneous volume magnetostriction at the Néel temperature (TN=100 K). The magnetic moment per Mn atom is 2.7 μB at 2 K. From polarized neutron diffraction in the paramagnetic state it has been shown that the effective moment persisting above TN is reduced (1.6 μB at 120 K). The anomalously large pressure dependence of TN (dTN/dp=–35 K/kbar) is an evidence for the sensitive role played by the Mn—Mn interatomic distances. In the paramagnetic state, the influence of spin fluctuations dominates the physical properties. We have studied the effect of pressure on the resistivity up to 16 kbar. From dρ/dT we have estimated the spinfluctuation temperature as a function of pressure. The value at ambient pressure is 15 K which is in agreement with that determined in the paramagnetic Y0.9Lu0.1Mn2 compound.

Pressure Gradients Affecting the Labyrinth during Hypobaric Pressure

1997 ◽  
Vol 106 (6) ◽  
pp. 495-502 ◽  
Author(s):  
Konrád S. Konrádsson ◽  
Björn I. R. Carlborg ◽  
Joseph C. Farmer
Keyword(s):  
Cerebrospinal Fluid ◽  
Eustachian Tube ◽  
Ambient Pressure ◽  
Pressure Gradients ◽  
Cochlear Aqueduct ◽  
Fluid Compartment ◽  
Large Pressure ◽  
Fluid Compartments ◽  
Pressure Changes ◽  
Considerable Pressure

Hypobaric effects on the perilymph pressure were investigated in 18 cats. The perilymph, tympanic cavity, cerebrospinal fluid, and systemic and ambient pressure changes were continuously recorded relative to the atmospheric pressure. The pressure equilibration of the eustachian tube and the cochlear aqueduct was studied, as well as the effects of blocking these channels. During ascent, the physiologic opening of the eustachian tube reduced the pressure gradients across the tympanic membrane. The patent cochlear aqueduct equilibrated perilymph pressure to cerebrospinal fluid compartment levels with a considerable pressure gradient across the oval and round windows. With the aqueduct blocked, the pressure decrease within the labyrinth and tympanic cavities was limited, resulting in large pressure gradients toward the chamber and the cerebrospinal fluid compartments, respectively. We conclude that closed cavities with limited pressure release capacities are the cause of the pressure gradients. The strain exerted by these pressure gradients is potentially harmful to the ear.

Anomalous hydrostatic pressure dependence of the Curie temperature of the Kondo-lattice compound YbNiSn to 38 GPa

1995 ◽  
Vol 52 (22) ◽  
pp. R15699-R15702 ◽  
Author(s):  
A. L. Cornelius ◽  
J. S. Schilling ◽  
D. Mandrus ◽  
J. D. Thompson
Keyword(s):  
Hydrostatic Pressure ◽  
Curie Temperature ◽  
Pressure Dependence ◽  
Kondo Lattice

Degeneracy Factor and Pressure Dependence of Si-Induced Deep Impurity States in AlxGa1-xAs from Transport Experiments under Hydrostatic Pressure

1991 ◽  
Vol 38-41 ◽  
pp. 857-862 ◽  
Author(s):  
S. Azema ◽  
V. Mosser ◽  
Jean Camassel ◽  
R. Piotrzkowski ◽  
Jean-Louis Robert ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Pressure Dependence ◽  
Deep Impurity ◽  
Impurity States

Temperature Dependence of the Intervalley Deformation Potential of GaAs/AlAs Superlattices Under Hydrostatic Pressure

1997 ◽  
Vol 499 ◽  
Author(s):  
S. Guha ◽  
Q. Cai ◽  
M. Chandrasekhar ◽  
H. R. Chandrasekhar ◽  
Hyunjung Kim ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Temperature Dependence ◽  
Pressure Dependence ◽  
Type I ◽  
Type Ii ◽  
Deformation Potential ◽  
Intervalley Scattering

ABSTRACTWe have studied the pressure dependence of the type-I and type-II transitions in (GaAs)m/(AlAs)m superlattices by photoluminescence (PL) spectroscopy. From the study of PL linewidths of the type-I exciton as a function of pressure and temperature, we determine the intervalley deformation potential. Beyond the type-I and type-II crossover, the PL linewidth increases both as a function of pressure and temperature. We find that the electron-phonon deformation potential for Γ-X intervalley scattering varies with temperature.

Hydrostatic Pressure Dependence of TCfor SASD Type Crystals

2005 ◽  
Vol 317 (1) ◽  
pp. 115-118 ◽  
Author(s):  
I. E. Lipiński ◽  
J. Kuriata ◽  
N. A. Korynevskii
Keyword(s):  
Hydrostatic Pressure ◽  
Pressure Dependence

scholarly journals Updated definitions on piezophily as suggested by hydrostatic pressure dependence on temperature

2020 ◽  
Author(s):  
Alberto Scoma
Keyword(s):  
Hydrostatic Pressure ◽  
Deep Sea ◽  
Ambient Pressure ◽  
Environmental Parameters ◽  
Microbial Life ◽  
Deep Waters ◽  
Microbial Response ◽  
Definition Of ◽  
Substrate Ph ◽  
Cell Functionality

AbstractMicrobial preference for elevated hydrostatic pressure (HP) is a recognized key feature of environmental and industrial processes. HP effects on macromolecules and, consequently, cell functionality has been accurately described in the last decades. While there is little debate about the importance of HP in shaping microbial life, a systematic definition of microbial preference for increased HP is missing. The lack of a consensus about ‘true’ piezophiles, and ‘low’ or ‘high’ HP levels, has deleterious repercussions on microbiology and biotechnology. As certain levels are considered ‘low’ they are not applied to assess microbial activity. Most microorganisms collected in deep waters or sediments have not been tested (nor isolated) using the corresponding HP at which they were captured. Microbial response to HP is notoriously dependent on other environmental parameters, most notably temperature, but also on availability of nutrients, growth substrate, pH and salinity. This implies that countless isolates retrieved from ambient pressure conditions may very well require increased HP to grow optimally, as already demonstrated in both Archaea and Bacteria.In the present study, I collected the data from described piezophilic isolates and used the fundamental correlation existing between HP and temperature, as first suggested in seminal works by Yayanos, to update the definition of piezophiles. Thanks to the numerous new piezophilic isolates available since such seminal studies, the present analysis brings forward updated definitions which concern 1) the actual beginning of the piezosphere, the area in the deep sea where piezophiles thrive; 2) the HP thresholds which should be considered low, medium and high HP, and their implications for experimental design in Microbiology; and 3) the nature of obligate piezophiles and their location in the deep sea.

Neutron-diffraction studies and interatomic distances in CaPr doped NdBa2Cu3O7−δ

1996 ◽  
Vol 269 (3-4) ◽  
pp. 231-241 ◽  
Author(s):  
P Lundqvist ◽  
C Tengroth ◽  
Ö Rapp ◽  
R Tellgren ◽  
Z Hegedüs
Keyword(s):  
Neutron Diffraction ◽  
Interatomic Distances
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