Effect of chromosome 1B, chromosome 6B, and low temperature on the frequency of chromosome pairing at first meiotic metaphase in hexaploid triticale

1983 ◽  
Vol 25 (3) ◽  
pp. 278-282
Author(s):  
Julian B. Thomas ◽  
P. J. Kaltsikes ◽  
S. Shigenaga
Keyword(s):  
Low Temperature ◽  
Common Wheat ◽  
Chromosome Pairing ◽  
Meiotic Metaphase ◽  
The Other ◽  
Hexaploid Triticale ◽  
Other Hand

Chromosome 1B in 'Rosner' and chromosome 6B in line 125 both reduced the frequency with which chromosomes were paired at first meiotic metaphase of hexaploid triticale. On the other hand, chromosome 6B in 'Rosner' and chromosomes 1B and 6B in line 110 had no such effect. The 1B pairing suppressor in 'Rosner' was located on the short arm of the chromosome (1Bs). Between 10 and 30 °C, pairing frequency was quite stable in 'Rosner' triticale in comparison with common wheat, although the level was consistently lower in the triticale. Some reduction of pairing frequency was noted at 10 °C in 'Rosner'. This effect of low temperature did not interact with 1B dosage to cause a disproportionate decrease in pairing frequency when plants with high 1B dosage were grown at 10 °C.

THE GENOMIC ORIGIN OF THE UNPAIRED CHROMOSOMES IN TRITICALE

1976 ◽  
Vol 18 (4) ◽  
pp. 687-700 ◽  
Author(s):  
J. B. Thomas ◽  
P. J. Kaltsikes
Keyword(s):  
Meiotic Metaphase ◽  
The Other ◽  
Differential Staining ◽  
Hexaploid Triticale ◽  
Genome Chromosome ◽  
Other Hand ◽  
Telocentric Chromosomes ◽  
Telomeric Heterochromatin ◽  
Triticosecale Wittmack ◽  
Terminal Chiasmata

Differential staining of telomeric rye heterochromatin and telocentric chromosomes were used to identify chromosomes which were unpaired at first meiotic metaphase of hexaploid triticale (× Triticosecale Wittmack). Both approaches showed that it was the rye chromosomes which were seen as univalents. Differences in the rate of pairing from triticale to triticale were mostly explained by variation in the pairing of the rye genome. Within the rye genome, chromosome arms with telomeric heterochromatin showed pairing rates much lower than chromosome arms lacking heterochromatin. Wheat telocentrics and heterochromatin-free rye telocentrics which showed intermediate levels of pairing failure (65-90%), had mostly terminal chiasmata. On the other hand rye telocentrics with large heterochromatin bands on the telomeres had mostly nonterminal chiasmata and very low pairing (5-35%). It is concluded that the presence of heterochromatin on certain telomeres of rye chromosomes blocks the formation of terminal chiasmata and this results in desynapsis and univalents at MI.

Energy in Thermal Physics

2021 ◽  
pp. 1-48
Author(s):  
Daniel V. Schroeder
Keyword(s):  
Low Temperature ◽  
Molecular Level ◽  
The Other ◽  
Thermal Physics ◽  
Other Hand ◽  
Energy Flows ◽  
Basic Concepts ◽  
Simple Models

The behavior of energy in bulk-matter systems is subtle. We observe that energy flows spontaneously from high to low temperature; we refer to this flowing energy as heat; and we distinguish heat from work, the transfer of energy through mechanical or other means unrelated to temperature. On the other hand, simple models of gases and solids strongly suggest that at the molecular level all energy is purely mechanical. This introductory chapter surveys these basic concepts of thermal physics, illustrates them with a wide variety of familiar examples, and sets the stage for developing a deeper understanding.

Effects of Solid Volume Fraction on the Gelcasting of Alumina Suspensions

2007 ◽  
Vol 280-283 ◽  
pp. 1041-1044
Author(s):  
Yong Huang ◽  
Li Ming Zhang ◽  
Hai Feng Li ◽  
Tian Ma
Keyword(s):  
Low Temperature ◽  
Rheological Behavior ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
The Other ◽  
Sintered Body ◽  
Green Body ◽  
Microstructure And Properties ◽  
Other Hand ◽  
Alumina Suspensions

The effects of solid volume fraction (SVF) on the gelation of alumina suspensions for gelcasting, debonding and sintering of the green body were studied. It was found that with SVF rising, the gelation of alumina suspension delayed; and the strength of green body decreased. On the other hand, high SVF resulted in that polymerized acrylamide split at a relative low temperature. These phenomena manifest that the fast polymerization of monomers in high SVF alumina suspension was inhibited, and the flexibility of the gelcasting was improved. However, Excessive solid volume fraction was prone to a bad rheological behavior of alumina suspension, and deteriorated the microstructure and properties of sintered body.

Study on stabilization of cubic Li7La3Zr2O12 by Ge substitution in various atmospheres

2016 ◽  
Vol 09 (06) ◽  
pp. 1642005 ◽  
Author(s):  
Masashi Kotobuki ◽  
Binngong Yan ◽  
Li Lu ◽  
Emil Hanc ◽  
Joanna Molenda
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Tetragonal Phase ◽  
The Other ◽  
Cubic Phase ◽  
Other Hand ◽  
High Temperature Xrd ◽  
Li Ion

Stabilization of high Li ion conductive cubic Li7La3Zr2O[Formula: see text] (LLZ) by Ge substitution in air, N2/O2 and N2 atmospheres are studied by high temperature XRD (HT-XRD) of Ge-added tetragonal LLZ (Ge-LLZ). A formation of low temperature cubic phase caused by CO2 absorption during storage of the Ge-LLZ is observed at about 160[Formula: see text]C in all atmospheres. Additionally, impurity formation of La2Zr2O7 and La2O3 also occurs in all atmospheres. On the other hand, stabilization of cubic phase by substitution of Ge is largely influenced by the atmosphere. The cubic phase is observed at 40[Formula: see text]C after heating Ge-LLZ to 700[Formula: see text]C in air while only tetragonal phase appeared after heating in N2/O2. It is concluded that the heating atmosphere largely influences substitution of Ge, resulting in stabilization of the high Li ion conductive cubic phase.

Role of Cl/Si Ratio in the Low-Temperature Chloro-Carbon Epitaxial Growth of SiC

2013 ◽  
Vol 740-742 ◽  
pp. 205-208
Author(s):  
Galyna Melnychuk ◽  
Siva Prasad Kotamraju ◽  
Yaroslav Koshka
Keyword(s):  
Growth Rate ◽  
Low Temperature ◽  
Epitaxial Growth ◽  
Growth Process ◽  
Growth Conditions ◽  
The Other ◽  
Additional Increase ◽  
Other Hand

In order to understand the influence of the Cl/Si ratio on the morphology of the low-temperature chloro-carbon epitaxial growth, HCl was added during the SiCl4/CH3Cl growth at 1300°C. Use of higher Cl/Si ratio allowed only modest improvements of the growth rate without morphology degradation, which did not go far beyond what has been achieved previously by optimizing the value of the input C/Si ratio. On the other hand, when the epitaxial growth process operated at too low or too high values of the input C/Si ratio, i.e., outside of the window of good epilayer morphology, any additional increase of the Cl/Si ratio caused improvement of the epilayer morphology. It was established that this improvement was due to a change of the effective C/Si ratio towards its intermediate values, which corresponded to more favorable growth conditions.

Low temperature mullite formation from sol-gel precursors by hot pressing

1994 ◽  
Vol 9 (10) ◽  
pp. 2474-2475 ◽  
Author(s):  
S.K. Pradhan ◽  
A. Chatterjee ◽  
A. Datta ◽  
M. De ◽  
D. Chakravorty
Keyword(s):  
Low Temperature ◽  
Hot Pressing ◽  
Ambient Pressure ◽  
Sol Gel ◽  
The Other ◽  
Mullite Formation ◽  
Mullite Phase ◽  
Temperature Conditions ◽  
Other Hand ◽  
Similar Growth

The mullite phase has been synthesized by subjecting a suitably chosen precursor gel to different pressure and temperature conditions. At ambient pressure mullite phase grows at a temperature of 1400 °C when the gel is heated for 2 h. At a pressure of 24 bar, on the other hand, similar growth occurs at a temperature of 750 °C for 5 min.

scholarly journals Diaqua(nitrato-κ2O,O′)bis(L-valine-κO)lead(II) nitrate at 296 K

IUCrData ◽  
2016 ◽  
Vol 1 (4) ◽  
Author(s):  
Sylvain Bernès ◽  
Laura Gasque
Keyword(s):  
Low Temperature ◽  
Bond Length ◽  
Coordination Number ◽  
Coordination Sphere ◽  
Title Complex ◽  
The Other ◽  
Methyl Group ◽  
Space Group ◽  
Polymeric Nature ◽  
Other Hand

The structure of the title complex, [Pb(NO3)(C5H11NO2)2(H2O)2]NO3, had been determined previously at 173 and 193 K, and is now reported at 296 K, in the same space group. The main difference with the low-temperature structures is that a methyl group of one valine ligand is clearly disordered over two positions, for which the occupancies converged to 0.56 (3) and 0.44 (3). Bond-length variations within the coordination sphere of PbIIas a function ofTare difficult to assess because uncertainties on these parameters are high. On the other hand, Pb...O distances above 2.9 Å cannot be assigned unambiguously to formal Pb—O bonds. As a consequence, the polymeric nature of the complex previously described at 173 K is uncertain, as well as the actual coordination number of PbII, and it is thus not possible to determine if the metal environment is holo- or hemidirected.

scholarly journals Highly Active Iminopyridyl Iron-Based Catalysts for the Polymerization of Isoprene

Molecules ◽  
2019 ◽  
Vol 24 (17) ◽  
pp. 3024 ◽  
Author(s):  
Obaid H. Hashmi ◽  
Yohan Champouret ◽  
Marc Visseaux
Keyword(s):  
Low Temperature ◽  
Electronic Properties ◽  
The Other ◽  
Co Catalysts ◽  
Highly Active ◽  
Other Hand ◽  
Iron Based ◽  
Stereo Selectivity ◽  
Iron Based Catalysts

A series of iminopyridyl-based ligands, 6-[(Ar)N=C(R)]-2-C6H5N [(Ar = 2,6-Me2-C6H3, R = Me (L1); Ar = 2,6-iPr2-C6H3, R = Me (L2); Ar = 2,6-Me2-C6H3, R = H (L3); Ar = 2,6-iPr2-C6H3, R = H (L4); Ar = 3,5-(CF3)2-C6H3, R = Me (L5); Ar = C6F5, R = Me (L6)], and their corresponding iron (II) complexes were developed to investigate their application in the controlled coordinative polymerization of isoprene. The modulation of steric and electronic properties within this family of ligands/pre-catalysts has shown to influence the stereo-selectivity and activity of the polymerization of isoprene after activation. Upon activation with various co-catalysts such as AliBu3/[Ph3C][B(C6F5)4], AlEt3/[Ph3C][B(C6F5)4] or MAO, the resulting catalysts produced polyisoprenes with an excellent conversion (>99% of 500–5000 equiv.) within less than 1 h (TOF > 500 h−1) and having a variety of stereo-/regio-regularities. The presence of electron-donating and withdrawing groups drastically impacted the activity and the stereoselectivity of the catalysts during the course of the polymerization of isoprene. When activated with AliBu3/[Ph3C][B(C6F5)4], the complexes {6-[(2,6-Me2-C6H3)N=C(Me)]-2-C6H5N}FeCl2 (C1) and {6-[(2,6-iPr2-C6H3)N=C(Me)]-2-C6H5N}FeCl2 (C2) exhibited moderate trans-1,4 selectivity (>67%) while the iron-based systems bearing related aldiminopyridyl ligands {6-[(2,6-Me2-C6H3)N=C(H)]-2-C6H5N}FeCl2 (C3) and {6-[(2,6-iPr2-C6H3)N=C(H)]-2-C6H5N}FeCl2 (C4) were found to afford significant cis-1,4 selectivity at low temperature (>86% at −40 °C). On the other hand, the ternary {6-[(3,5-(CF3)2-C6H3)N=C(Me)]-2-C6H5N}FeCl2 (C5) or {6-[(C6F5)N=C(Me)]-2-C6H5N}FeCl2 (C6)/AliBu3/[Ph3C][B(C6F5)4] catalytic combinations showed exceptional activity for the polymerization of isoprene (TOF > 1,000,000 h−1), albeit providing less stereoselectivity.

FACTORS AND PROCESSES IN THE GERMINATION OF DATURA FEROX L.

1964 ◽  
Vol 42 (9) ◽  
pp. 1189-1203 ◽  
Author(s):  
A. Soriano ◽  
R. A. Sánchez ◽  
B. A. de Eilberg
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Oxidation Product ◽  
Red Light ◽  
Storage Conditions ◽  
The Other ◽  
Metabolic Processes ◽  
Other Hand ◽  
Inhibitor Level

The germination of Datura ferox seeds is blocked immediately after ripeness by an inhibitor. The decoating of the seeds and certain storage conditions promote germination by favoring the diffusion of the inhibitor or its destruction.Seeds in which the germination blockage due to the inhibitor had been overcome behave as photoblastically positive, responding to the R–FR mechanism. During afterripening, the capacity of the skotomechanism increases as the inhibitor level decreases. The skotomechanism blockage does not disappear with low temperature or with alternating temperatures. On the other hand, high temperature reimposes this blockage.Gibberellic acid replaces the effect of red light, whereas thiourea is not effective.It is postulated, on the basis of the results obtained with this species, and the results of other authors, that the quantity of an oxidation product present, resulting from metabolic processes during storage or the action of red light, controls both germination and the possibility of germination being produced in conditions of light or darkness.

Photochemical reactions of bacteriorhodopsin in Triton X-100 solution studied by low temperature spectrophotometry

1985 ◽  
Vol 63 (7) ◽  
pp. 1891-1898 ◽  
Author(s):  
Tatsuo Iwasa ◽  
Fumio Tokunaga ◽  
Tỏru Yoshizawa
Keyword(s):  
Low Temperature ◽  
Thermal Equilibrium ◽  
Photochemical Reaction ◽  
Membrane Structure ◽  
Purple Membrane ◽  
Photochemical Reactions ◽  
The Other ◽  
Other Hand ◽  
Triton X

The photochemical reaction of purple membrane solubilized with Triton X-100 (T-BR) was investigated by low temperature spectrophotometry. The batho- and meta-intermediates of T-BR were observed to resemble bacteriorhodopsin in native purple membrane. Two photoproducts characteristic of the T-BR system were found, which were named the "490-nm complex" and the "380-nm complex". The 490-nm complex was in thermal equilibrium with T-BR in the dark. Cooling T-BR to low temperature favoured the 490-nm complex, which was photoinsensitive. On the other hand, the 380-nm complex was produced by warming the batho-intermediate and reverted to the original T-BR. The meta-intermediate of T-BR may possibly be in thermal equilibrium with the 380-nm complex. On the basis of the above results, the possible role of the membrane structure was discussed

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