Toxic encephalopathy in a clinicl case of polycythemia vera

The article deals with a clinical case description of a female patient with toxic encephalopathy against the background of Ph-negative myeloproliferative diseases. The article discusses symptoms and neuroimaging of hepatic encephalopathy developed as a result of a shunt placed after portal vein thrombosis. The issues of etiology and pathogenesis of hepatic encephalopathy, principles of therapy, as well as the unique clinical picture of nervous system damage in this condition are also discussed. Data on the role of manganese in development of toxic encephalopathy, accumulation of paramagnetic substance in the basal ganglia of the brain and development of extrapyramidal symptoms are presented. The pathogenesis of toxic damage to neurons, increase in their sensitivity to hypoxia, and the relationship with the risk of cerebrovascular disorders and development of chronic cerebral ischemia, contributing to reduction of cognitive functions, are described.

THE TECHNIQUE OF MAGNETIC RESONANCE IMAGING WITH DYNAMIC CONTRAST ENHANCEMENT WITH FOCAL BENIGN LUNG FORMATION

MRT with dynamic contrast enhancement has not found wide application in lung pathology, there are no clear recommendations for its implementation, no criteria for the goodness of the changes have been developed. The aim: of the study was to clarify the procedure for analyzing the data of DKU-MRI, the search for predictors of the quality of focal changes in the lungs. DKE-MRT performed 28 patients with verified benign changes in the lungs at a magnetic resonance tomograph of 1,5 T. As the analysis shows, the use of relative rather than absolute values with the calculation of the contrast index (CI), reflecting the degree of accumulation of a paramagnetic substance in the object of investigation relative to the main anatomical landmark-aorta, is a reliable sign of angiogenesis. In this case, it is necessary to focus on the zones of maximum intensity of the MR signal of the structure under study, the value of ROI can vary considerably. The CI in the hamartomas was 0,23–0,35. In the scar tissue, the CI values did not practically change throughout the study, being 0,21–0,25 relative to the peak density in the aorta. CI soft tissues and benign focal lesions of the lungs, the form of the curve of the paramagnetic circulation was comparable, being 0,25–0,3 relative to the peak density to the aorta. When analyzing the DKE-MRT curves, the concentration/time should be oriented to the zones of maximum intensity of the MR signal from vascular structures, focal lesions of the lungs, soft tissues of the back, while the ROI area is of no fundamental importance. As a criterion of good-quality focal formation of the lung should be guided by CI in soft tissues.

On the specific heat of compounds with spinel structure - II. Zinc ferrite, a paramagnetic compound with magnetic ion occupying the octahedral site

The representation of the lattice vibrational component of the specific heat for compounds with cubic spinel structure used in part I is applied to the paramagnetic substance ZnFe 2 O 4 Analysis of the experimental data over the temperature range 10–350 K reveals a magnetic contribution in the neighbourhood of the Néel point in reasonable agreement with the theoretical calculations of Tachiki & Yosida (1957) and an anomaly at 75 K which is attributed to transitions by the Fe 3+ ion between the two equivalent potential minima within the octahedral site. Further analysis of the tail of this anomaly, which varies inversely as the square of the temperature for almost 90 K, leads to an estimated height for the potential barrier of 14.8 ± 0.5 x 10 -3 eV.

The direct measurement of the magnetization entropy of a paramagnetic substance: thermal and magnetic properties of ferric methylammonium alum at low temperatures

A method, is described for determining the magnetization entropy of a paramagnetic sub­stance by the measurement of the heat absorbed by the sample during isothermal demagnet­izations near 1°K. The method has been used with ferric methylammonium alum, which deviates appreciably from ideal behaviour because of the large Stark splittings of the ground state of the Fe 3+ ions. The results were found to agree within the experimental error with magnetization entropies computed from the energy levels of the ferric ions in a trigonal crystalline field. The computed entropies have been used to determine the absolute tem­peratures below 1°K reached by adiabatic demagnetizations of this salt.

Orientation of nuclear spins in metals

In recent years, temperatures down to about 1/100-1/1000 degree absolute have been reached by means of the magnetic cooling method. This method, which was proposed by Debye and by Giauque, consists essentially of isothermal magnetization of a paramagnetic substance, followed by adiabatic demagnetization. Kürti and Simon (1935) have shown that the lowest temperatures which can be reached by this method are proportional to the interaction energy between magnetic dipoles of the substances used. Therefore, in order to reach still lower temperatures, it was proposed by these authors and by Gorter (1934) that the magnetism of atomic nuclei should be used. F. Simon (1939) has recently discussed this idea in greater detail and found that it should be possible to realize it experimentally. The question now arises of what temperatures can be reached in this way, what times will be necessary and what will be the properties of the nuclear spins at these temperatures. * In this paper we shall investigate these questions for metals. Here, the magnetic interaction between the conduction electrons and the nuclei leads to an indirect coupling between the magnetic moments of the nuclei which for many metals is considerably larger than their direct magnetic interaction. We shall show that any metal for which this is the case becomes ferromagnetic with respect to the nuclei. The Curie temperature will be of the order 10 -6 degree or less, and the temperatures reached by the magnetic cooling method will consequently be of the same order of magnitude. The attainment of such temperatures where the nuclear spins are orientated may be of great importance in nuclear physics.

On the possibility of a thermal effect accompanying sudden changes in the magneton-numbers in CuCl2 and NiSO47 H2O

1. The temperature variation of the paramagnetic susceptibility of most of the solids follows the generalised Curie lawas found first by Kamerlingh Onnes and Weiss. This gives a linear relation between 1/ψ and T. The value of C is a measure of the atomic magnetic moment, and if this moment is expressed in terms of the Weiss magneton-number p, thenwhere CM is the value of C when ψ refers to a gram-molecule. The experimental results for a paramagnetic substance are usually expressed in terms of p and θ. Weiss (1), Foex (2), Cabrera and others have found that in some substances there are discontinuities in the slope of the 1/ψ, T curve. Thus Weiss (3) finds that magnetite above its Curie point shows several sudden changes in the 1/ψ, T curve, which he has interpreted as corresponding to the magneton-numbers p = 4, 5, 6, 8,10. Similarly, for cupric chloride (anhydride) Weiss (4) gives p= 9.2 and 10, for the temperature ranges — 140° to 20° and 20° to 500° respectively. Nickel sulphate (5) has also been found to possess a transition point at about — 113°, where the p value on cooling changes from 14.6 to 18.2.

The gyromagnetic ratio for paramagnetic substances. III.—Results on salts of the rare earth group

In a previous paper (referred to in what follows as I) a method for measuring the gyromagnetic ratio for paramagnetic substances was described, together with the results of experiments on a strongly paramagnetic substance, dysprosium oxide. The ratio of the angular momentum produced by a given change of magnetic moment gives the Landé splitting factor, which in the case of the Dy +++ ion was found to be 1·28. This indicates that the magnetic moment is composed of both orbital and spin contributions, and agrees well with the theoretical value of 1·33 for the state 6 H 15/2 deduced by Hund as being the most probable for this ion. In a further contribution (II), the apparatus was used for similar measurements on some salts of the iron group, an account being given of the means used to obtain the necessary increased sensitivity. The results, taken as a whole, show that the only tenable view advanced to explain the magnetic susceptibilities of ions of this group is that of Stoner, i. e ., that the spin and orbital moments are quantised separately relative to the field axis, and further, the orbital moment may be wholly or partially suppressed by the fields of neighbouring ions. The present paper deals with measurements on some oxides of the rare earth group. The apparatus used was identical with that designed for increased sensitivity and described in II, so that no further description is necessary.

The gyromagnetic effect for paramagnetic substances. II.—Results on salts of the iron group

In a previous paper (referred to hereafter as Part I) a method for measuring the gyromagnetic ratio for paramagnetic substances was described. Owing to the smallness of the angular moment produced by a change in the magnetic moment of a paramagnetic substance, a low frequency resonance method was employed to build up the amplitude to a measurable magnitude. An account of the method of measurement and elimination of errors was given in detail. The results of experiments on one paramagnetic substance, Dy +++ in dysprosium oxide (Dy 2 O 3 ), showed the Landé splitting factor for this ion to be 1·28, which indicates that the magnetic moment arises from both orbital and spin contributions. This agrees well with the theoretical value 1·33, corresponding to the state 6 H 15/2 deduced by Hund as the most probable ground state of this ion. The present contribution deals with results on salts of the iron group. The magnetic susceptibilities range from 10 -5 to 10 -4 compared with 2·4 × 10 -4 in the case of the Dy 2 O 3 previously used. This necessitates a greater sensi­tivity than that used in Part I, and the means employed to achieve this are described below.