Thallium Data Research Articles

Noninvasive assessment of changes in myocardial perfusion and ventricular performance following exercise training

Seventeen coronary patients (CAD) underwent thallium (TI-201) treadmill and radionuclide (RNV) ejection fraction supine bicycle testing before and after 5.6 ± 1.6 ( X ± SD) months of an exercise program. Thallium data were assessed both using analog images and a computerized circumferential profile technique. Patients exercised on the treadmill to a higher workload after the exercise program, but achieved a similar pressure-rate product. When interpreting the analog thallium images, only 50% agreement was obtained for the assessment of changes in myocardial perfusion (pre/post-training). The computer technique, however, had low inter-intraobserver variability (6%) and better agreement (90.5%). Using the circumferential profile method, five patients improved (a total of 11 regions) and one patient worsened (with two regions). Before the exercise program, the ejection fraction (EF) response to supine bike exercise was normal (an increase greater than 11%) in four, flat in seven, and severely abnormal (a decrease of more than 4%) in six patients. After the exercise program, even though achieving similar or higher pressure-rate products, six patients improved their EF response, nine did not change, and two worsened. Of the five patients who improved their thallium images, one improved his EF response, two remained normal, and two did not change. One patient worsened both his thallium study and the EF response after the exercise program. Changes in thallium exercise images and the EF response to supine exercise occurred in our patients after an exercise program, but were not always concordant. Indeed, of five patients with exercise-induced ischemic ST changes before and after training, the EF response improved in three whereas myocardial perfusion was unchanged. Reasons for this lack of agreement are discussed, and have been considered in the planning of a randomized trial of the effects of an exercise program on myocardial perfusion and function.

A novel synthesis and crystal data for thallium(III) oxide bromide

AbstractThallium(III) oxide bromide, TlOBr, has been prepared from thallium(I) carbonate and liquid bromine. It crystallizes in an orthorhombic unit cell with, a = 4.147(1) Å, b = 3.760(1) Å, c = 8,706(3) Å, Z = 2, space group Pmmn, and is isomorphous to InOBr (FeOCl type).

Effects of Pressure on the Superconducting Transition Temperatures of Sn, In, Ta, Tl, and Hg

Solid parahydrogen has been used as a transmitter of approximately hydrostatic pressure to study the effects of pressures up to 10 000 atmos on the superconducting transition temperatures of polycrystalline tin, indium, tantalum, thallium, and mercury. The technique which was used allowed an approximate evaluation of the effects of sample deformation and pressure gradients, and the results are considerably more accurate than the high-pressure data previously available. The transition temperature data for tin and indium showed considerable curvature when plotted vs pressure, but gave a roughly linear relationship when plotted against volume. No curvature was found for tantalum. The thallium data agree qualitatively with previous work, and show a maximum in the transition temperature vs pressure curve at about 2000 atmos. The mercury results were anomalous in that two distinct transition temperature vs pressure curves (with different zero-pressure transition temperatures) were found; one when the pressure was kept below 4000 atmos, and the other when the sample was cycled from zero to 10 000 atmos. Other experiments have shown that these results are due to two different modifications of solid mercury, each of which can exist at liquid helium temperatures.

Properties of Indium and Thallium at Low Temperatures

The pressure-volume relationships for superconductors near absolute zero are of potential interest for comparison with theories which attempt to explain the variation of the superconducting transition temperature with pressure. Such data for thallium are of special interest since the variation of transition temperature with pressure is different for thallium than for any other known pure metal. In these experiments, measurements on indium of the total compression to 10 000 atmos for various temperatures down to 4.2\ifmmode^\circ\else\textdegree\fi{}K served as a check of similar measurements on thallium. No unusual behavior was found for either metal. These results were combined with the measurement of the total thermal expansions for both metals to give isobars at both zero pressure and at 10 000 atmos pressure over the range from 4.2\ifmmode^\circ\else\textdegree\fi{} to 300\ifmmode^\circ\else\textdegree\fi{}K. The results of some low-temperature compressive testing experiments on both metals are also given, together with some indirect evidence as to the vanishing of work hardening effects at low temperature and moderate hydrostatic pressures. Finally, measurements on the electrical resistance of indium show an unexplained kink in the $R$ vs $T$ curve at about 210\ifmmode^\circ\else\textdegree\fi{}K. The effect on the electrical resistance of indium due to tensile (plastic) deformation at 4.2\ifmmode^\circ\else\textdegree\fi{}K was also measured.