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PubMed1983

Genetics of esterases in Drosophila. VII. Genetic control of the activity level of juvenile hormone (JH)-esterase and heat resistance in D. virilis at high temperatures.

The heat-resistant subline 147S was obtained in Drosophila virilis by selecting for viability individuals of heat-sensitive stock 147. It was shown that in the heat-treated 147S pupae the activity of juvenile hormone (JH)-esterase is decreased and, consequently, the titer of juvenile hormone is increased compared with those in the control pupae. These changes are consistent with those observed earlier for resistant stock 101. Heat-resistant stocks 101 and 147S were crossed with heat-sensitive stock 147, whose heat-treated larvae show earlier activation and higher activity of JH-esterase than control larvae. The viability and electrophoretic esterase patterns were analyzed in the F1 and F2 hybrids at different temperatures. It was found that the F1 hybrid is resistant to the effect of high temperature and its activity level of JH-esterase is lower compared with controls. In the F2 hybrid, there was a 3:1 segregation of viability and a 1:2:1 segregation of the activity level of JH-esterase at high temperatures. It is concluded that the activity level of JH-esterase and heat resistance in D. virilis are monogenically controlled at high temperatures.

Animals↗
PubMed1999

Mathematical simulation of chlorophyll a fluorescence rise measured with 3-(3',4'-dichlorophenyl)-1,1-dimethylurea-treated barley leaves at room and high temperatures.

Chlorophyll a fluorescence induction (FI) measured by Plant Efficiency Analyser fluorometer at room temperature shows a typical O-J-I-P pattern which is at high temperature changed to an O-K-P pattern with a new step K. It has been suggested that the appearance of the K step reflects inhibition of an oxygen evolving complex (OEC). When FI is measured at room temperature with the photosystem II (PSII) herbicide 3-(3',4'-dichlorophenyl)-1,1-dimethylurea (DCMU), which blocks electron transport from Q(A) to Q(B) (the first and the second quinone electron acceptors in PSII, respectively), the time course of the FI shows a sigmoidal increase to the maximal fluorescence which is reached at a little longer time than that of the J step. Similarly, the FI measured at high temperature with DCMU reaches the maximal value of fluorescence at the time which is a little longer than that of the K step. On the other hand, the reversible radical pair model (RRP) describes energy utilization and electron transport up to Q(A). In this work we present the first, to our knowledge, RRP model extended by a description of the function of the donor side of PSII. Assuming the inhibition of the OEC or its full function, the extended RRP model successfully simulates the fluorescence rise measured with DCMU at high and room temperatures, respectively. The roles of the initial state of the OEC and the values of the rate constants in the extended RRP on the simulations of the fluorescence rise at room and high temperatures are also discussed.

Chlorophyll↗
PubMed2003

Engineering Deinococcus geothermalis for bioremediation of high-temperature radioactive waste environments.

Deinococcus geothermalis is an extremely radiation-resistant thermophilic bacterium closely related to the mesophile Deinococcus radiodurans, which is being engineered for in situ bioremediation of radioactive wastes. We report that D. geothermalis is transformable with plasmids designed for D. radiodurans and have generated a Hg(II)-resistant D. geothermalis strain capable of reducing Hg(II) at elevated temperatures and in the presence of 50 Gy/h. Additionally, D. geothermalis is capable of reducing Fe(III)-nitrilotriacetic acid, U(VI), and Cr(VI). These characteristics support the prospective development of this thermophilic radiophile for bioremediation of radioactive mixed waste environments with temperatures as high as 55 degrees C.

Biodegradation, Environmental↗
PubMedDate not supplied

Use of avian myeloblastosis virus reverse transcriptase at high temperature for sequence analysis of highly structured RNA.

Avian myeloblastosis virus reverse transcriptase (AMV RT) is routinely used in the sequence analysis of RNA and DNA templates. We review the various methods for dealing with secondary structures that would otherwise result in premature termination or sequence compression. Based on our experience in sequencing the 11-kb single-stranded RNA genome of lymphocytic choriomeningitis virus, we have found that raising the reaction temperature above 47 degrees C is the simplest way to overcome template secondary structure, and the use of 98% formamide gels is the simplest way to overcome product secondary structure.

Avian Leukosis Virus↗
PubMed2004

MAS-NMR at very high temperatures.

We report MAS-NMR experiments at temperatures of approx. 1200 K using a CO(2) laser as the heating device. An internal NMR thermometer based on the (7)Li T1 data of Li(0.24)La(0.54)TiO(3) is used for temperature calibration. Using this setup, temperatures as high as 1191 K could be reached under MAS conditions as confirmed by the melting of Li(2)B(4)O(7) at 1191 K which could be followed by (7)Li-MAS-NMR.

Hot Temperature↗
PubMed1977

Effect of ultra-high-temperature steam injection processing on sulfur-containing amino acids in milk.

Raw skim milk was processed by a modified No-Bac Unitherm IV System (Cherry-Burrell Corp.) at 143 C for 8 s, vacuum cooled to 71 C, collected, and cooled to 4 C. Raw and ultra-high-temperature processed skim milks were oxidized with performic acid, hydrolyzed with hydrochloric acid, and analyzed for cysteine and cystine (as cysteic acid) and methionine (as methionine sulfone) on a Beckman Automatic Amino Acid Analyzer. A loss of approximately 34% of these amino acids was observed in ultra-high-temperature processed skim milk. Sulfhydryl and disulfide groups determined with Ellman's reagent [5,5'-dithiobis(2-nitrobenzoic acid)] indicated no free sulfhydryls in raw skim milk and .07 mmole per liter in ultra-high-temperature processed skim milk. Loss in total sulfhydryl and disulfide groups was approximately 16% in ultra-high-temperature processed milk. Volatile sulfur compounds were detected by odor in the vapor collected from the vacuum chamber, but they could not be identified. Amino acid analysis of milk deposit collected from the injection section revealed .09 microgram of cysteine and cystine (as cysteic acid) per gram of deposit and no detectable methionine.

Amino Acids, Sulfur↗
PubMed2002

High temperature stabilization of DNA in complexes with cationic lipids.

The influence on the melting of calf thymus and plasmid DNA of cationic lipids of the type used in gene therapy was studied by ultraviolet spectrophotometry and differential scanning calorimetry. It was found that various membrane-forming cationic lipids are able to protect calf thymus DNA against denaturation at 100 degrees C. After interaction with cationic lipids, the differential scanning calorimetry melting profile of both calf thymus and plasmid DNA revealed two major components, one corresponding to a thermolabile complex with transition temperature, T(m(labile)), close to that of free DNA and a second corresponding to a thermostable complex with a transition temperature, T(m(stable)), at 105 to 115 degrees C. The parameter T(m(stable)) did not depend on the charge ratio, R(+/-). Instead, the amount of thermostable DNA and the enthalpy ratio Delta H((stable))/Delta H((labile)) depended upon R(+/-) and conditions of complex formation. In the case of O-ethyldioleoylphosphatidylcholine, the cationic lipid that was the main subject of the investigation, the maximal stabilization of DNA exceeded 90% between R(+/-) = 1.5 and 3.0. Several other lipids gave at least 75% protection in the range R(+/-) = 1.5 to 2.0. Centrifugal separation of the thermostable and thermolabile fractions revealed that almost all the transfection activity was present at the thermostable fraction. Electron microscopy of the thermostable complex demonstrated the presence of multilamellar membranes with a periodicity 6.0 to 6.5 nm. This periodic multilamellar structure was retained at temperatures as high as 130 degrees C. It is concluded that constraint of the DNA molecules between oppositely charged membrane surfaces in the multilamellar complex is responsible for DNA stabilization.

Animals↗
PubMed2007

Structures of the high-temperature solid phases of the odd-numbered fatty acids from tridecanoic acid to tricosanoic acid.

Crystal structures of the high-temperature phases of odd-numbered fatty acids (C(n)H(2n-1)OOH) from tridecanoic acid (C(13)H(25)OOH) to tricosanoic acid (C(23)H(45)OOH) are presented in this article. They have been determined from high-quality X-ray powder-diffraction patterns. Two types of high-temperature phases are adopted: one monoclinic A2/a with Z=8 for the fatty acids with n=13 and n=15, denoted as C'', and one monoclinic P2(1)/a with Z=4 for the longer-chain fatty acids, denoted as C'. It appears that the packing arrangement of the alkyl chains and of the carboxyl groups is similar in all of the structures. However, the arrangement at the methyl-group interface differs between the C' and C'' forms. A survey of the intermolecular interactions involved in these polymorphs coupled with a study of the effects of temperature on the structures have led us to a better understanding of the arrangement of the molecules within the high-temperature solid phases of odd-numbered fatty acids.

Journal Article↗
PubMed2003

No mixing of superconductivity and antiferromagnetism in a high-temperature superconductor.

There is still no universally accepted theory of high-temperature superconductivity. Most models assume that doping creates 'holes' in the valence band of an insulating, antiferromagnetic 'parent' compound, and that antiferromagnetism and high-temperature superconductivity are intimately related. If their respective energies are nearly equal, strong antiferromagnetic fluctuations (temporally and spatially restricted antiferromagnetic domains) would be expected in the superconductive phase, and superconducting fluctuations would be expected in the antiferromagnetic phase; the two states should 'mix' over an extended length scale. Here we report that one-unit-cell-thick antiferromagnetic La2CuO4 barrier layers remain highly insulating and completely block a supercurrent; the characteristic decay length is 1 A, indicating that the two phases do not mix. We likewise found that isolated one-unit-cell-thick layers of La1.85Sr0.15CuO4 remain superconducting. The latter further implies that, on doping, new electronic states are created near the middle of the bandgap. These two findings are in conflict with most proposed models, with a few notable exceptions that include postulated spin-charge separation.

Journal Article↗
PubMed1999

High temperature cDNA synthesis by AMV reverse transcriptase improves the specificity of PCR.

The enzyme avian myeloblastosis virus reverse transcriptase (AMV-RT) is routinely used for cDNA synthesis, which is generally carried out at temperatures between 37 degrees C and 42 degrees C. We show that this enzyme can support cDNA synthesis, at temperatures as high as 70 degrees C. We have utilized this property of the AMV-RT to improve the specificity of polymerase chain reaction (PCR). Furthermore, this apparently thermophilic property of the enzyme, which is an important constituent of a mesophilic organism, raises intriguing questions regarding evolution of the enzyme structure.

Avian Myeloblastosis Virus↗
PubMed2005

Using geminal dicationic ionic liquids as solvents for high-temperature organic reactions.

[reaction: see text] Several organic reactions conducted at high temperatures, including the isomerization reaction, the Claisen rearrangement, and the Diels-Alder reaction, were investigated in three geminal dicationic ionic liquids with high thermal stability. High to moderate yields of the products for most entries were obtained. Advantages of these approaches are discussed. These ionic liquids were shown to be recyclable. The utility of these ionic liquid solvents for high-temperature organic reactions was demonstrated.

Anthracenes↗
PubMed2001

[Effects of high temperature and cigarette smoke on the development of nervous system in early rat embryos].

In order to explore the effect of high temperature or cigarette smoke and their combined effect on the development of nervous system in early rat embryos, pregnant rats at the 8-11th day of gestation were exposed to high temperature and water soluble substances of cigarette smoke. All indexed of embryonic nervous system development were determined with experimental treat logical methods. The results showed that following the increase of temperature or cigarette smoke exposure all indexes correlated with embryonic nervous system development and morphological differentiation were changed, with an apparent dose-effect relationship (P < 0.01). The changes were related to specific phase of embryonic development. The results showed also that the nervous system development and morphological differentiation induced by both high temperature and cigarette smoke were higher than that by any single factor.

Animals↗
PubMed2006

Unusual high-temperature structural behaviour in ferroelectric Bi2WO6.

The crystal structure of Aurivillius phase ferroelectric Bi2WO6 has been studied in detail as a function of temperature by using high-resolution powder neutron diffraction. In agreement with an earlier study, a transition from space group P2(1)ab to B2cb occurs at about 660 degrees C. This transition corresponds to the loss of one octahedral tilt mode within the perovskite-like WO4 layer of the structure. A second, reconstructive, phase transition occurs around 960 degrees C, corresponding to the ferroelectric Curie point; in contrast to previous suggestions, the structure of this high-temperature phase contains layers of stoichiometry WO4, with WO6 octahedra sharing edges and corners, and with the fluorite-like Bi2O2 layers remaining essentially unchanged. This structure is closely related to that of the ambient temperature phase of lanthanide-doped derivatives, for example, Bi0.7Yb1.3WO6 recently reported. This phase-transition behaviour is in stark contrast to that of other members of the Aurivillius family, such as SrBi2Ta2O9 and Bi4Ti3O12, which retain the archetypal Aurivillius connectivity at all temperatures.

Journal Article↗
PubMed1980

Ternary transition metal phosphides: High-temperature superconductors.

Two systems of ternary transition metal phosphides with the ordered Fe(2)P-type hexagonal structure are reported. They have the general formula MRuP and MOsP, in which M can be Ti, Zr, or Hf. An onset of the superconducting transition temperature as high as 13.0 K is reported for the ZrRuP compound.

Journal Article↗
PubMed2002

Influence of the irradiation temperature on the dosimetric and high temperature TL peaks of Al2O3:C.

The TL glow curves of Al2O3:C crystals have been investigated as a function of the irradiation temperature. The nature of the observed TL peaks has been studied by optical annealing. The filling of traps was found strongly dependent on the irradiation temperature in the case of UV exposure, which has been explained by the temperature dependence of the photoionisation of F centres. This latter phenomenon could have a part in the luminescence quenching and UV bleaching of F centres.

Aluminum Oxide↗
PubMed2006

High-temperature slow relaxation of the magnetization in Ni10 magnetic molecules.

We investigate a family of molecular crystals containing noninteracting Ni10 magnetic molecules. We find slow relaxation of the magnetization below a temperature as high as 17 K and we show that this behavior is not associated with an anisotropy energy barrier. Ni10 has a characteristic magnetic energy spectrum structured in dense bands, the lowest of which makes the crystal opaque to phonons of energy below about 1 meV. We ascribe the nonequilibrium behavior to the resulting resonant trapping of these low-energy phonons. Trapping breaks up spin relaxation paths leading to a novel kind of slow magnetic dynamics which occurs in the lack of anisotropy, magnetic interactions and quenched disorder.

Journal Article↗
PubMed2006

Multiple parameter vector bending and high-temperature sensors based on asymmetric multimode fiber Bragg gratings inscribed by an infrared femtosecond laser.

We present a multiple parameter integrated fiber sensor that can detect vector bending and ambient temperature simultaneously with a single asymmetric multimode fiber Bragg grating. Multimode Bragg gratings were fabricated in an all-silica core fiber by an infrared femtosecond laser, which showed multiple transmission dips in the transmission spectrum. Bending and ambient temperature fluctuations affect the shapes of multiple transmission dips in different ways. In bending, different dips have different sensitivities. On the other hand, temperature fluctuations tended to influence the dips uniformly across different dips. By analyzing the changing spectrum of dips, one can distinguish the changes induced by bending or temperature fluctuations. Furthermore, the high thermal stability of Bragg gratings inscribed by an infrared femtosecond laser can make this double parameter fiber sensor work in very harsh, high-temperature environments.

Journal Article↗