Infrared spectra of the ammonium ion in crystals. Part VII. Existence of symmetrically trifurcated hydrogen bond in ammonium halides

1980 ◽  
Vol 58 (3) ◽  
pp. 270-282 ◽  
Author(s):  
Osvald Knop ◽  
Wolfgang J. Westerhaus ◽  
Michael Falk
Keyword(s):  
Room Temperature ◽  
Ammonium Ion ◽  
Effect Of Temperature ◽  
Hydrogen Bonding Interaction ◽  
Maximum Probability ◽  
Threefold Axis ◽  
Ammonium Halides ◽  
Bonding Interaction ◽  
Increasing Temperature

This investigation deals with the effect of temperature, between 10 and 293 K, on the ir spectrum of the NH3D+ probe ion in polycrystalline NH4SnF3, NH4CuSO3, cubic (NH4)2SiF6, and (NH4)2SnCl6. The results lead to the following conclusions. At 10 K these crystals contain symmetrically trifurcated [Formula: see text] bonds, i.e. bonds in which the N—H orientation of maximum probability is on the threefold axis. With increasing temperature these bonds lose progressively their symmetrically-trifurcated character to become highly bent, highly dynamic [Formula: see text]•bonds, and the strength of the hydrogen-bonding interaction increases. This is reflected in the decrease of the ND stretching frequency of the probe ion with increasing temperature, which is the opposite of the behaviour observed with normal (i.e. essentially straight) [Formula: see text] bonds.Re-determination of the room-temperature crystal structure of NH4CuSO3 has confirmed the correctness of the structure reported previously by Nyberg and Kierkegaard.

Infrared spectra of the ammonium ion in crystals. Part VIII. Spectroscopic criteria of highly-bent hydrogen bonds

1980 ◽  
Vol 58 (9) ◽  
pp. 867-874 ◽  
Author(s):  
Osvald Knop ◽  
Wolfgang J. Westerhaus ◽  
Michael Falk
Keyword(s):  
Low Temperature ◽  
Hydrogen Bonds ◽  
Infrared Spectra ◽  
Room Temperature ◽  
Ammonium Ion ◽  
Temperature Transition ◽  
Increasing Temperature

Available evidence suggests that (1) the stretching frequencies of highly-bent hydrogen bonds decrease with increasing temperature, regardless of whether the bonds are static or dynamic in character, to a single acceptor or to several competing acceptors; and (2) departures from symmetric trifurcation (or bifurcation) toward asymmetric situations lower the stretching frequency. In further support of these criteria isotopic probe ion spectra between 10 K and room temperature have been obtained for taurine and for trigonal (NH4)2MF6 (M = Si, Ge, Sn, Ti). Evidence of a low-temperature transition at 100(10) K in trigonal (NH4)2SnF6 is presented, and existence of the previously reported transition at 38.6 K in trigonal (NH4)2SiF6 is confirmed. Symmetry changes associated with these transitions are discussed.

Effect of Temperature on Crater Formation and Ejecta Composition in Aluminum Alloy Targets

2012 ◽  
Vol 706-709 ◽  
pp. 768-773
Author(s):  
Masahiro Nishida ◽  
Koichi Hayashi ◽  
Junichi Nakagawa ◽  
Yoshitaka Ito
Keyword(s):  
Aluminum Alloy ◽  
High Temperature ◽  
Low Temperature ◽  
Room Temperature ◽  
Effect Of Temperature ◽  
Crater Formation ◽  
Influence Of Temperature ◽  
Gas Gun ◽  
Influence Of Temperature On ◽  
Increasing Temperature

The influence of temperature on crater formation and ejecta composition in thick aluminum alloy targets were investigated for impact velocities ranging from approximately 1.5 to 3.5 km/s using a two-stage light-gas gun. The diameter and depth of the crater increased with increasing temperature. The ejecta size at low temperature was slightly smaller than that at high temperature and room temperature. Temperature did not affect the size ratio of ejecta. The scatter diameter of the ejecta at high temperature was slightly smaller than those at low and room temperatures.

The Deformation Microstructure in NI3Si Polycrystals Strained Over the Range of Temperature of Flow Stress Anomaly

1988 ◽  
Vol 133 ◽  
Author(s):  
B. Tounsia ◽  
P. Beauchamp ◽  
Y. Mishima ◽  
T. Suzuki ◽  
P. Veysslière
Keyword(s):  
Flow Stress ◽  
Slip System ◽  
Room Temperature ◽  
Peak Temperature ◽  
Effect Of Temperature ◽  
Screw Dislocations ◽  
Thermally Activated ◽  
Cube Plane ◽  
Octahedral Slip ◽  
Increasing Temperature

ABSTRACTIn order to correlate the flow stress anomaly of Ni3Si with dislocation properties, a weakbeam study ofpolycrystalline samples deformed between ambient and the peak temperature was carried out. Samples with two extreme Ni/Si ratios were tested.The most frequently activated slip system changes progressively from octahedral to cubic with increasing temperature. The transformation of superdislocations into Kear-Wilsdorf configurations gives rise to screw dislocations that are rectilinear only after deformation at room temperature. The effect of temperature is to gradually promote bending of Kear-Wisdorf configurations in the cube plane, from a few nanometers at 230°C to several tenths of micrometers at intermediate temperature. Cube slip begins to be massively activated a little below the peak temperature. It is suggested that the flow stress anomaly is controlled by progressive exhaustion of octahedral slip by thermally-activated expansion of superdislocations on the cube cross-slip plane.

Effect of Temperature and Strain Rate on the Mechanical Properties of 99.5 Aluminium Rods Extruded by KOBO

2016 ◽  
Vol 879 ◽  
pp. 230-235
Author(s):  
Sonia Boczkal ◽  
Marzena Lech-Grega ◽  
Wojciech Szymanski ◽  
Paweł Ostachowski ◽  
Marek Lagoda
Keyword(s):  
Strain Rate ◽  
Room Temperature ◽  
High Strain ◽  
Effect Of Temperature ◽  
Recrystallization Process ◽  
Extrusion Force ◽  
Strain Rates ◽  
High Strain Rates ◽  
Constant Frequency ◽  
Increasing Temperature

In this study, aluminium rods were cold extruded in a direct process by KOBO method in two variants: variant I with varying (decreasing) frequency of die oscillations necessary to maintain a constant extrusion force, and variant II with constant frequency of die oscillations, leading to a decrease in the extrusion force. The tensile test of rods was carried out in a temperature range of 20 - 200°C and at a strain rate from 8xE10-5 to 8xE10-1 s-1. Significant differences in the elongation of the tested rods were observed. It was found that rods extruded at variable die oscillations and stretched at room temperature had similar elongation, independent of the strain rate. With the increase of temperature, the elongation of samples stretched at a low speed was growing from a value of about 8% at room temperature up to 40% at 200°C. At high strain rates, despite the increasing temperature, the elongation remained at the same level, i.e. 5-6%. In rods extruded at constant die oscillations, the elongation at a low strain rate was growing with the temperature from 10% at room temperature up to 29% at 200°C. At high strain rates, the elongation decreased from 28% at room temperature to 11% at 200°C. The results were interrelated with examinations of the structure of rods and fractures of tensile specimens. In the material extruded by KOBO method with constant die oscillations, the beginnings of the recrystallization process were observed, absent in the material extruded at variable die oscillations.

Role of natural day-length and temperature in determination of summer and winter diapause in Pieris melete (Lepidoptera: Pieridae)

2011 ◽  
Vol 102 (3) ◽  
pp. 267-273 ◽  
Author(s):  
H.J. Xiao ◽  
S.H. Wu ◽  
H.M. He ◽  
C. Chen ◽  
F.S. Xue
Keyword(s):  
Adaptive Significance ◽  
Field Conditions ◽  
Day Length ◽  
Effect Of Temperature ◽  
Path Coefficient ◽  
Path Coefficient Analysis ◽  
Summer Diapause ◽  
Increasing Temperature

AbstractUnder field conditions, the cabbage butterfly, Pieris melete, displays a pupal summer diapause in response to relatively low daily temperatures and gradually increasing day-length during spring and a pupal winter diapause in response to the progressively shorter day-length. To determine whether photoperiod is ‘more’ important than temperature in the determination of summer and winter diapause, or vice versa, the effects of naturally changing day-length and temperature on the initiation of summer and winter diapause were systematically investigated under field conditions for five successive years. Field results showed that the incidence of summer diapause significantly declined with the naturally increasing temperature in spring and summer generations. Path coefficient analysis showed that the effect of temperature was much greater than photoperiod in the determination of summer diapause. In autumn, the incidence of diapause was extremely low when larvae developed under gradually shortening day-length and high temperatures. The incidence of winter diapause increased to 60–90% or higher with gradually shortening day-length combined with temperatures between 20.0°C and 22.0°C. Decreasing day-length played a more important role in the determination of winter diapause induction than temperature. The eco-adaptive significance of changing day-length and temperature in the determination of summer and winter diapause was discussed.

The Effect of Temperature on the Material Damping of Graphite/Epoxy Composites in a Simulated Space Environment

1990 ◽  
Vol 112 (3) ◽  
pp. 277-279 ◽  
Author(s):  
G. T. Spirnak ◽  
J. R. Vinson
Keyword(s):  
Room Temperature ◽  
Damping Ratio ◽  
Theoretical Models ◽  
Space Environment ◽  
Effect Of Temperature ◽  
Time Cost ◽  
Material Damping ◽  
Temperature Dependent ◽  
Increasing Temperature ◽  
Free Beam

An experimental method for measuring material damping is described, which employs a free-free beam lightly supported at the nodes. A thermal space environment is simulated by measuring the material damping in air at temperatures ranging from −65°F to 225°F, and then subtracting out the effects of atmospheric damping. This method saves considerable time, cost and experimental difficulties associated with performing the experiments in a vacuum. Graphite/epoxy AS4/3501-6 composite beam specimens were tested. At room temperature, the [0°]12 composites were found to have an average damping ratio of 0.0556 percent. The [90°]12 composites were found to have an average material damping ratio of 0.55 percent. These data agree well with the theoretical models and experimental measurements performed in a vacuum. The material damping ratio is temperature dependent over the range −65°F to 225°F, increasing with increasing temperature. For the [0°]12 composite, the material damping ratio varies from 0.0397 percent at −65°F to 0.083 percent at 225°F. For the [90°]12 composite, the material damping ratio varies from 0.408 percent at −65°F to 0.860 percent at 225°F.

Determination of the Temperature and Field Dependence of the Interface Conductivity Mobility in 4H-SiC/SiO2

2006 ◽  
Vol 527-529 ◽  
pp. 1055-1058 ◽  
Author(s):  
Gary Pennington ◽  
Siddharth Potbhare ◽  
Neil Goldsman ◽  
Daniel B. Habersat ◽  
Aivars J. Lelis
Keyword(s):  
Field Dependence ◽  
Field Effect ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Charge Trapping ◽  
Device Model ◽  
Temperature Modeling ◽  
Strong Inversion ◽  
Increasing Temperature

In this work we present a comparison between the field-effect (FE) and conductivity (inv) mobilities calculated from ID-VG measurements on a 4H-SiC MOSFET. A compact device model is used to determine inv. The conductivity mobility is found to be larger than FE near room temperature, but less than FE at 500K. These results are due to a reduction in charge trapping at higher temperatures. In strong inversion, inv decreases markedly with increasing temperature. Modeling indicates that surface phonon scattering dominates in this regime.

scholarly journals The Effect of Temperature and Mo Content on the Lattice Misfit of Model Ni-Based Superalloys

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 700 ◽  
Author(s):  
Amy J. Goodfellow ◽  
Lewis R. Owen ◽  
Katerina A. Christofidou ◽  
Joe Kelleher ◽  
Mark C. Hardy ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Room Temperature ◽  
Lattice Misfit ◽  
Lattice Parameter ◽  
Lattice Parameters ◽  
Effect Of Temperature ◽  
General Decrease ◽  
Mo Content ◽  
Increasing Temperature ◽  
Mo Additions

The lattice parameters and misfit of the γ and γ′ phases in a series of model quaternary Ni-based superalloys with and without Mo additions have been determined using neutron diffraction between room temperature and 700 °C. Despite the fact that Mo is typically expected to partition almost exclusively to the γ phase and thereby increase the lattice parameter of that phase alone, the lattice parameters of both the γ and γ′ phases were observed to increase with Mo addition. Nevertheless, the effect on the γ lattice parameter was more pronounced, leading to an overall decrease in the lattice misfit with increasing Mo content. Alloys with the lowest Mo content were found to be positively misfitting, whilst additions of 5 at.% Mo produced a negative lattice misfit. A general decrease in the lattice misfit with increasing temperature was also observed.

The Worthington "ultrafree" device evaluated for determination of ultrafiltrable calcium in serum.

1981 ◽  
Vol 27 (3) ◽  
pp. 466-468 ◽  
Author(s):  
J Toffaletti ◽  
D Tompkins ◽  
G Hoff
Keyword(s):  
Human Serum ◽  
Room Temperature ◽  
Reference Intervals ◽  
Effect Of Temperature ◽  
Healthy Population ◽  
Calcium Citrate ◽  
Coefficients Of Variation ◽  
Disposable Device

Abstract We evaluated a commercially-available disposable device ("Ultrafree," Worthington Diagnostics) for the anaerobic preparation of protein-free ultrafiltrates from serum for measurement of ultrafiltrable calcium. Sufficient filtrate for the analysis is obtained with 10 min from 0.2 to 0.4 mL of serum at room temperature. We assessed these ultrafilters with regard to permeability of calcium citrate, exclusion of proteins, frequency of leakage, and effect of temperature on results. Within-run and day-to-day coefficients of variation for human serum pools were 1.2 and 1.5%, respectively. Reference intervals (in mmol/L) for total (2.16-2.58), ultrafiltrable (1.44-1.67), dialyzable (1.25-1.41), and ionized (1.04-1.25) calcium have been determined for a healthy population of 69 women and 81 men, ages to 18 to 65 years. The device appears to be the most practicable yet available for use in making this measurement.

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