Low Temperature Structural Instability of Tetragonal Spinel Mn3O4

2013 ◽  
Vol 82 (3) ◽  
pp. 034707 ◽  
Author(s):  
Jae-Ho Chung ◽  
Kee Hwan Lee ◽  
Young-Sang Song ◽  
Takehito Suzuki ◽  
Takuro Katsufuji
Keyword(s):  
Low Temperature ◽  
Structural Instability ◽  
Tetragonal Spinel

Ultrasonic Study of the Low Temperature Structural Phase Transition in Yba2Cu3O7-δ. and its Dependence on Oxygen Concentration

1989 ◽  
Vol 169 ◽  
Author(s):  
J. Toulouse ◽  
X.Q. Wang ◽  
D.J.L. Hong
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Linear Relationship ◽  
Oxygen Concentration ◽  
Structural Phase Transition ◽  
Annealing Temperature ◽  
Structural Phase ◽  
Structural Instability ◽  
Second Phase ◽  
Ultrasonic Study

AbstractElastic and structural instability have been reported in YBa2Cu3O7‐δbetween 210K and 270K. We have carried out an ultrasonic study of these instabilities as a function of both oxygen concentration and annealing temperature. The results strongly indicate that an athermal (martensitic‐type) transition starts at a temperature Ts which decreases with decreasing oxygen concentration. A linear relationship between Ts and Tc suggests that the second phase formed is essential for the high Tc.

Structural instability of Sn-doped In2O3 thin films during thermal annealing at low temperature

2007 ◽  
Vol 515 (17) ◽  
pp. 6686-6690 ◽  
Author(s):  
Yanfa Yan ◽  
J. Zhou ◽  
X.Z. Wu ◽  
H.R. Moutinho ◽  
M.M. Al-Jassim
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Thermal Annealing ◽  
Structural Instability

Low-temperature Crystal Structure and 57Fe Mössbauer Spectroscopy of Sr3Sc2O5Fe2As2

2009 ◽  
Vol 64 (7) ◽  
pp. 815-820 ◽  
Author(s):  
Marcus Tegela ◽  
Inga Schellenberg ◽  
Franziska Hummel ◽  
Rainer Pöttgen ◽  
Dirk Jorendt
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Isomer Shift ◽  
Quadrupole Splitting ◽  
Spectroscopic Data ◽  
Bond Angle ◽  
Magnetic Ordering ◽  
Structural Instability ◽  
Low Temperature Crystal Structure ◽  
Tetragonal Cell

The crystal structure of the layered iron arsenide Sr3Sc2O5Fe2As2 was determined between 300 and 10 K. The lattice parameters of the tetragonal cell decrease anisotropically according to Δc/c : Δa/a ≈ 4.2, which results in a slight flattening of the As-Fe-As bond angle within the FeAs layers. No indication of a structural instability could be detected. 57Fe Mössbauer spectroscopic data show only a single signal at 4.2, 77, and 298 K, subjected to quadrupole splitting. The isomer shift increases from 0.36(1) mms−1 at 298 K to 0.49(1) mms−1 at 4.2 K. No indication for magnetic ordering was found.

scholarly journals Reduction in the structural instability of cloned eukaryotic tandem-repeat DNA by low-temperature culturing of host bacteria

2014 ◽  
Vol 96 ◽  
Author(s):  
WATCHARAPORN THAPANA ◽  
PENPORN SUJIWATTANARAT ◽  
KORNSORN SRIKULNATH ◽  
HIROHISA HIRAI ◽  
AKIHIKO KOGA
Keyword(s):  
Low Temperature ◽  
Tandem Repeat ◽  
Genomic Dna ◽  
Structural Changes ◽  
Structural Instability ◽  
Centromeric Dna ◽  
Repeat Dna ◽  
Bacterial Plasmid ◽  
Dna Fragment

SummaryFor accurate analyses of eukaryotic tandem-repeat DNA, it is often required to clone a genomic DNA fragment into a bacterial plasmid. It is, however, a serious problem that tandem-repeat DNA is frequently subjected to structural changes during maintenance or amplification in the host bacteria. Here, we show an example of a clear difference in the instability of tandem-repeat DNA between different culturing temperatures. A fragment of monkey centromeric DNA carried by pUC19 was considerably degraded by culturing bacteria at 37 °C, but the damage was reduced at 25 °C. Thus, culturing temperature is a significant factor for avoiding degradation, in addition to the genotype of the host bacteria.

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.

Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves

1984 ◽  
Vol 42 ◽  
pp. 284-285
Author(s):  
S. Edith Taylor ◽  
Patrick Echlin ◽  
May McKoon ◽  
Thomas L. Hayes
Keyword(s):  
Low Temperature ◽  
Lemna Minor ◽  
Root Tips ◽  
Tobacco Leaves ◽  
X Ray ◽  
Whole Cells ◽  
Carbon Coated ◽  
The Right ◽  
Beam Currents ◽  
The University

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.

Bulk standards for low-temperature biological x-ray microanalysis

1984 ◽  
Vol 42 ◽  
pp. 282-283
Author(s):  
P. Echlin ◽  
M. McKoon ◽  
E.S. Taylor ◽  
C.E. Thomas ◽  
K.L. Maloney ◽  
...  
Keyword(s):  
Phase Separation ◽  
Low Temperature ◽  
Analytical Method ◽  
Salt Solutions ◽  
Absolute Concentration ◽  
Cooling Process ◽  
X Ray ◽  
The Absolute ◽  
Analytical Procedures ◽  
Electrical Conductors

Although sections of frozen salt solutions have been used as standards for x-ray microanalysis, such solutions are less useful when analysed in the bulk form. They are poor thermal and electrical conductors and severe phase separation occurs during the cooling process. Following a suggestion by Whitecross et al we have made up a series of salt solutions containing a small amount of graphite to improve the sample conductivity. In addition, we have incorporated a polymer to ensure the formation of microcrystalline ice and a consequent homogenity of salt dispersion within the frozen matrix. The mixtures have been used to standardize the analytical procedures applied to frozen hydrated bulk specimens based on the peak/background analytical method and to measure the absolute concentration of elements in developing roots.

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