T2 Term Research Articles

Troponin T and I Expression in Failing and Hypertrophic Heart, and during Normal Development in Human

Background and Objectives:Human Troponin T & I (TnT, TnI has several isoforms which have different functional property. This study was designed to describe the isoform expression of TnT & TnI in failing and hypertrophic human heart and during normal development. Materials and Method:Myocardium was attained from hypertrophic hearts (N=10 of TOF patients who underwent myomectomy, from failing hearts (N=10 of transplant recipients, from normal hearts (N=5 of patients in brain death and from aborted fetal hearts (N=5. After the extraction of RNA, RT-PCR was performed for TnT & TnI isoforms and GAPDH to evaluate the isoform expression qualitatively and quantitatively. Results:In terms of TnI, slow skeletal TnI was expressed more than cardiac TnI in fetal hearts(ratio of Troponin over GAPDH (R=1.3:0.5) but cardiac TnI was dom- inant in adult hearts (R=0.3:1.1 (p<0.05. Failing hearts showed similar pattern with adult hearts (R=0.3: 1.2 and hypertrophic hearts showed the intermediate pattern (R=0.9:1.3. In terms of TnT, T1 and T3 were expressed in fetal hearts (R=0.04, 0.8 but only T3 was expressed in adult hearts (R=1.1. Failing hearts and hypertrophic hearts showed similar pattern with adult hearts and no differences in the amount of expression (R=1.4, 1.3. Conclusion:There is isoform switch from fetal to adult form during development and it might be responsible for the differences of myocardial functional property between fetal and adult heart. Failing and hypertrophic hearts showed no differences with normal hearts, which means the isoform switch of TnT & I might have no significant role in functional disturbances in these conditions. (Korean Circulation J 1998;28 ( ( ( (10 : 1760-1766

Dependence of the low-temperature specific heat of YBa2Cu3O7?? on ? and magnetic field: The H1/2T term for H?0; absence of evidence for a T2 term for H=0

Specific-heat measurements with improved precision on two new samples of YBa2Cu3O7−δ with relatively low concentrations of paramagnetic centers are reported. For one sample the measurements were made for different values of δ. The data are analyzed, and the data reported earlier for another sample reanalyzed, with an improved fitting expression. In each case, the data give a well defined H1/2T term in the mixed state. No persuasive evidence for a T2 term in the superconducting state is found.

Investigation of impurity effects in La2−xSrxCu1−yMyO4 (M=Ga,Zn) by electronic specific heat

The electronic specific heat Cel was studied at T≤10K on Ga- and Zn-doped La2−xSrxCuO4 (0.16≤x≤0.22). In pure La2−xSrxCuO4 (0.16≤x≤0.22), the Cel at T<Tc contains only a T2 component but no T-linear one, which is peculiar to a clean d-wave superconductor. Partial substitution of Ga or Zn for Cu changes the T2-term of Cel into a quite different one described by the sum of a T-linear and a nearly T3 term. The coefficient of the T-linear term, γ, markedly increases with Zn-or Ga-content. The λ/λN vs. Tc/Tco relation for Zn-doped samples with x≥0.2 is in good agreement with the theoretical curve for resonant impurity scattering in a d-wave superconductor, while those for Ga-doped samples and for Zn-doped samples with x<0.2 deviate slightly from the theoretical curve. Such a deviation will be discussed in relation to the change in the magnetic properties of the present system caused by impurity-doping.

Anomalous Specific Heat Behavior of Nanocrystalline Fe at Low Temperatures

The specific heat of nanocrystalline iron with grain size of 40 nm has been measured in the low temperature range from 1.8 to 26 K. The anomalous specific heat behavior of nanocrystalline iron is compared to that of the standard bulk iron. It is found that the electronic specific heat coefficient γ obtained at low temperatures decreases by about 50%. A T2 term in the heat capacity associated with surface modes has been clearly observed. A large enhancement of the specific heat at temperatures above 16 K may be interpreted as the Einstein oscillator contributions.

Unified view on conductivity and specific heat in DCNQI-Cu systems

We point out the possibility that the coupling between d hole and Jahn-Teller distortion plays an important role for the large T-linear specific heat ( gamma ) of DCNQI-Cu; the Coulomb repulsion between d holes (U) is not important for the enhancement of gamma . On the contrary, U is the origin of the large T2 term of the electrical resistivity (A). Yet, gamma and A have a correlation (A alpha gamma 2). We present a picture in which all these facts can be explained without any contradiction. On the basis of the picture we can understand naturally the essential properties of DCNQI-Cu in the metallic phase, including the anomalous behaviour near the metal-insulator transition, although there remain many details to be confirmed with the developing experiments.

Perturbation analysis of convective heat transfer in helicoidal pipes with substantial pitch

Fully developed convective heat transfer in a coiled pipe with substantial pitch (the helicoidal pipe) is investigated by the perturbation method. The results of this study indicate that the effect of pitch on the temperature distribution appears in the second-order solution (T2 terms), and that it will rotate the high temperature contours that deviate from the outer wall, which are enhanced by increasing the Reynolds number, the Prandtl number, and the curvature of the coil. As a result, the peak of the Nusselt number along the periphery moves away from the outer wall. The results of the study also indicate that increasing pitch may slightly reduce the average Nusselt number.

Neutron scattering and specific heat study of AlGe and AlSi alloys quenched under high pressure

Neutron scattering and specific heat measurements on pressure-quenched AlGe and AlSi alloys are reported. The neutron results corroborate earlier findings of a pronounced softening of the transverse zone boundary modes in these polycrystalline nonequilibrium alloys, reminiscent of a similar softening observed in metallic glasses. At lower frequencies, however, no pronounced glassy anomaly is found. The additional excitations seen around 9 meV in AlGe can be explained in terms of resonant modes of the heavier Ge atoms. At still lower frequencies, neutrons see only sound waves. The more sensitive specific heat technique shows the corresponding lattice T3 term and an electronic contribution which follows the classical BCS behaviour at the transition to superconductivity. Below 0.5 K, there remains a linear term about a factor of ten smaller than in typical glasses.

The change in the temperature coefficient of resistivity with Mn addition in Fe- and Co-rich amorphous alloys

Electrical resistivity studies have been carried out on a-Co80−x−yFexMnyB12Si8 alloys for 10≤x≤70 and y=0,4,8. It has been found that the decrease of temperature coefficients of resistivity (TCR) with Mn substitution is significantly more in Fe-rich alloys than in Co-rich alloys. A T2 term is not found in Co-rich alloys even up to the addition of 8 at. % of Mn. Although Fe-rich alloys show a T2 dependence for 8 at. % of Mn, a second minimum is not observed. In the absence of Mn, the substitution of Fe for Co does not decrease the TCR while in the presence of Mn, the substitution of Fe does decrease the TCR.

Transport properties and phase diagram of UNi2Si2

The resistivity and Hall coefficient of single-crystal UNi2Si2 have been studied in detail for the temperature range 4.2-300 K. The resistivity of UNi2Si2 is largely due to magnetic scattering and the phonon scattering contribution is estimated to be about 14% at room temperature. At low temperatures, the resistivity can be described by a gapped spin-wave model plus a T2 term. The temperature dependence of the Hall coefficient is accounted for by a theoretical model invoking skew scattering of conduction electrons by localized magnetic moments. Among the three magnetic phase transition temperatures, the two lower ones are found to be magnetic field dependent and shift with the field applied along the tetragonal c axis. Using the resistivity measurement in an applied magnetic field, a field-temperature phase diagram of UNi2Si2 is presented.

Low-temperature features of electron scattering in cadmium

The scattering rates nu (T) of various groups of electrons in cadmium have been measured down to 0.25 K using the radio-frequency size effect. For electrons on the third band lens of the fermi Surface nu (T) can be analyzed below about 2.5 K as the superposition of two terms, alpha T2 and beta T3. While the latter is associated with electron-phonon scattering the former component can be attributed to electron-electron scattering. On two triangular orbits in the first and second bands an apparently large T2 term is observed between 5 and 1.5 K. At lower temperatures nu (T) drops rapidly suggesting that this behaviour is due to electron-phonon scattering. An explanation for large T2 terms has been proposed by Lawrence et al. (1986) on the basis of Umklapp electron-phonon scattering together with the particular shape of the Fermi surface of cadmium. Simple calculations on these lines are shown to reproduce semi-quantitatively the observed variation of nu (T) and to aid in the interpretation of another second band orbit.

Effect of Mn and Ni on the electrical resistivity of amorphous Fe(80−x−y)NiyMnxB12Si8 alloys

Electrical resistivity studies have been carried out on a-Fe(80−x−y)NiyMnxB12Si8 alloys (0<x<5.5;20<y<50). It is found that the resistivity behavior in these alloys is different in some aspects from those that contain Cr instead of Mn. In the Cr containing alloys a T2 term in the resistivity expression is found to be dominant at temperatures above Tmin, while in Mn containing alloys the dominant term has an effective power of less than 1.5. It is conjectured that in Cr containing alloys it is the simultaneous presence of a negative T32 and a positive T2 term which leads to a second temperature minimum in resistivity at high temperature (> 100 K). In the Mn containing alloys, however, we do not find evidence for the presence of two such terms of opposite signs. It was also found that the presence of Ni increases the positive temperature coefficient of resistivity, but the increase was stronger in Mn containing alloys.

Resistivity of ferromagnetic CePt

Abstract The resistivity of CePt has been measured between 1.9 and 300 K. CePt orders ferromagnetically at 5.8 K. Its ferromagnetic state resistivity increases as T3 above a constant residual term. This correlates with a T3 term in the magnetic specific heat.

Scaling of the magnetoresistance of UBe13 under pressure

We report magnetoresistance measurements of the heavy electron compound UBe13 above the superconducting transition temperature Tc and below 4 K for pressures P up to 19 kbar and for magnetic fields H up to 9 T. We observe strong negative magnetoresistance at all pressures and temperatures. The resistivity ρ is quadratic in temperature T from Tc up to a maximum temperature of 1 K at 1 bar increasing to 2 K at 19 kbar. The slope of the T2 term decreases with both H and with P. We find that δ(H)≡−[ρ(H)−ρ(0)]/ρ(0) for a given pressure scales as a function of H/T and exhibits power-law behavior over one decade with an exponent of 1.7. In addition, δ(H) at high pressure shows this same power law over a more limited H/T range.

Magnetoresistance and upper critical magnetic field of UBe13 under pressure

We have investigated the effects of pressure on the magnetoresistance and the upper critical magnetic field of the heavy electron compound UBe13. Both the superconducting transition temperature and the upper critical field decrease under hydrostatic pressure. The low temperature magnetoresistance remains large and negative under pressure. The temperature region over which the resistivity has a T2 temperature dependence increases with both magnetic field and with pressure. At a fixed magnetic field, the coefficient of the T2 term in the resistivity decreases strongly with pressure. UBe13 is found to have a pressure independent intrinsic residual resistivity of 18 μΦcm.

Field dependence of the T2 term of the resistivity in UPt3

High field measurements on UPt3 (H ≦ 21 T) were performed in order to study at constant field the field dependence A(H) of the T2 term of the resistivity. Assuming a scaling of A(H) by the square γ2 of the linear temperature term of the specific heat, the increase of the localization of the heavy f particles on approaching the metamagnetic transition is supported. Comparison is made with localized Fermi liquid models and with results obtained on CeCu6, CeAl3 and CeRu2Si2.

CeCu2Ge2: Magnetic order in a Kondo lattice

Magnetic, calorimetric and transport measurements characterize CeCu2Ge2 as a Kondo-lattice system which orders antiferromagnetically below TN = (4.15 ± 0.05) K. The low-temperature specific heat shows a magnon-derived T3 term and, in addition, an electronic contribution γ(T)T. γ(T) extrapolates to 0.1 J/K2mol as T → 0 and assumes a large maximum of 0.22 J/K2mol at T = 0.45 K.

The Thermal Expansion and Heat Capacity of Ni3Al

The measured heat capacity Cp of a stoichiometric sample of Ni3Al from 0.5 to 15 K is qualitatively similar to earlier data: Cp≈8.9×10-3T+1944(T/470)3+0(T5) J/g.at K. The linear expansivity α can be represented by α≈-0.12T+0.0013T3 (×10-8 K-1) from 10 to 30 K but shows a marked decrease in α/T below 10 K and a jump of +10×10-8 K-1 above Tc≈41 K. The T and T3 terms lead to Grüneisen parameters γT≈-0.5 and γT3≈2.5 respectively.

Toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin in cold-adapted rats.

The toxicity of 60 micrograms/kg 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) given IP in corn oil/5% acetone was examined in male Sprague-Dawley rats adapted to 25 degrees C or 4 degrees C ambient temperature. Cold exposure significantly reduced mean time to death and tended to increase mortality. Body weight at the time of death was reduced at both ambient temperatures to about the same extent. Thus, the rate of body weight loss was about twice as fast in non-survivors at 4 degrees C than at 25 degrees C. There was a continuous decrease in feed intake of the non-survivors at 25 degrees C until death. However, no reduction in feed intake occurred in any of the rats at 4 degrees C ambient temperature. At 14 days after dosing all TCDD-dosed animals were hypothyroid in terms of T4 but essentially euthyroid in terms of T3. Oxygen consumption at 10 days after dosing was reduced to the same extent in all TCDD-dosed rats without regard to survival status. By day 20 after TCDD dosage, survivors increased their oxygen consumption at both ambient temperatures to nearly control levels whereas non-survivors were unable to do so. Body temperature of all animals remained within normal range except for the non-survivors, which showed reduced rectal temperature shortly before death.(ABSTRACT TRUNCATED AT 250 WORDS)

Transport and magnetic measurements on UPt3

Experiments on the normal phase of UPt3 show a large positive magnetoresistivity, almost temperature-independent, linear in field, and a positive thermoelectric power which is not linear in temperature as T→0. The superconducting phase is characterized by a high thermal conductivity with a strong T2 term, by a coherence length smaller than the mean free path, and by lower and upper critical fields H(0)c1∼60 Oe and Hc2(0)∼26 kOe.

Thickness effects and the T2dependence of the resistivity of aluminium

A collation of data on the resistivity of aluminium foils is presented. The T2 term caused by the surface, which is now well established, is examined and found to exist over a large range in sample thickness and observational temperature. Contrary to previous assertions, the magnitude of this T2 term does not appear to vary simply as the inverse of the sample thickness. It is suggested that there are two ways in which a surface-caused T2-like term may arise. In metals with simple Fermi surfaces conventional surface scattering theories yield such a term from a combination of a bulk T5 term and surface scattering. By contrast, for a metal such as aluminium with a disconnected Fermi surface an extra T2 term arising directly from surface scattering processes may appear.