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The editors would like to acknowledge and thank all of those who assisted us in 2020 by providing peer review of the submitted manuscripts. Reviewers serve without pay. The time, effort and experti...

Consensus recommendations for acute acetaminophen exposure include plotting an acetaminophen concentration at ≥ 4 h post ingestion on the Rumack-Matthew nomogram to determine the need for acetylcysteine treatment. We studied the frequency of acetaminophen concentrations drawn within 4 h post ingestion and whether the Rumack-Matthew nomogram was properly used in making acetylcysteine treatment decisions.This was a retrospective, observational case series at three regional poison centers of acute acetaminophen exposures between 1/1/13 and 12/31/13. Cases were analyzed for demographics, timing of acetaminophen concentrations, and application of the Rumack-Matthew nomogram in acetylcysteine initiation or termination.1,123 cases of acute acetaminophen exposure were reviewed. Of 520 acute acetaminophen exposure cases presenting4 h post ingestion, 323 (62%) had a pre-4-hour acetaminophen concentration measured and 197 (38%) did not. Those with a known pre-4-hour acetaminophen concentration were less likely to have a 4-hour acetaminophen concentration (59% vs. 93%) or an acetaminophen concentration within 8 h (87% vs. 99%) and were more likely to be treated with acetylcysteine (29% vs. 17%) and less likely to be treated based on the Rumack-Matthew nomogram (72% vs. 97%).Patients with a known exposure time and presenting within 4 h of acetaminophen ingestion had a pre-4-hour acetaminophen concentration obtained 62% of the time. Pre-4-hour acetaminophen concentrations cannot be used to determine the need for acetylcysteine therapy and are associated with an increased likelihood of not obtaining optimally timed acetaminophen concentrations and acetylcysteine management not based on the proper application of the Rumack-Matthew nomogram. Current practice results in additional cost, unnecessary treatment, potential adverse medication effects, and the possibility of non-treatment of patients at risk of hepatotoxicity.

A general description of the basic system of ordinary differential equations of coupled transport processes is given within framework of a linear approximation and treated by tools of matrix analysis and group representation theory. It is shown that the technique of hyperdyads directly generalizes the method of simple dyadic decomposition of operators used earlier in the classical linear irreversible thermodynamics and leads to possible new applications of the concept of quasi-polynomials at descriptions of coupled transport processes.

The American College of Medical Toxicology established the Toxicology Investigators Consortium (ToxIC) Case Registry in 2010. The Registry contains all medical toxicology consultations performed at participating sites. The Registry has continued to grow since its inception, and as of December 31, 2015, contains 43,099 cases. This is the sixth annual report of the ToxIC Registry, summarizing the additional 8115 cases entered in 2015. Cases were identified by a query of the Registry for all cases entered between January 1 and December 31, 2015. Specific data reviewed for analysis included demographics (age, race, gender), source of consultation, reason for consultation, agents and agent classes involved in exposures, signs, symptoms, clinical findings, fatalities, and treatment. By the end of 2015, there were 50 active sites, consisting of 101 separate health-care facilities; 51.2 % of cases involved females. Adults between the ages of 19 and 65 made up the majority (64.2 %) of Registry cases. Caucasian race was the most commonly reported (55.6 %); 9.6 % of cases were identified as Hispanic ethnicity. Inpatient and emergency department referrals were by far the most common referral sources (92.9 %). Intentional pharmaceutical exposures remained the most frequent reason for consultation, making up 52.3 % of cases. Of these intentional pharmaceutical exposures, 69 % represented an attempt at self-harm, and 85.6 % of these were a suicide attempt. Nonopioid analgesics, sedative-hypnotics, and antidepressant agents were the most commonly reported agent classes in 2015. Almost one-third of Registry cases involved a diagnosed toxidrome (32.8 %), with a sedative-hypnotic toxidrome being the most frequently described. Significant vital sign abnormalities were recorded in 25.3 % of cases. There were 98 fatalities reported in the Registry (1.2 %). Adverse drug reactions were reported in 4.3 % of cases. Toxicological treatment was given in 65.3 % of cases, with 33.0 % receiving specific antidotal therapy. Exposure characteristics and trends overall were similar to prior years. While treatment interventions were required in the majority of cases, fatalities were rare.

A twofold refinement of the basic mathematical model for describing a coupled heat and mass transfer taking place in porous media is presented. The common application of irreversible thermodynamics and fluctuation theory of phase transitions is proposed for calculating the moisture level and temperature. Instead of parabolic partial differential equations, hyperbolic type partial differential equations are used. The relaxation time constants, whose percolation state-dependence is also taken into account, are incorporated into this formalism. Some possible new research domains in mathematical and statistical physics are also indicated.

The convective flow in vertical cylindrical tubes is investigated and a new formula for its velocity is derived. The Ostroumov problem is briefly discussed, and the relevant fourth-order ordinary differential equation referring to this problem is solved directly in its complete form and within a frame of an allowed simplification, as well. The result obtained for the velocity function is in good qualitative agreement with earlier simulation calculations.

The Rumack-Matthew nomogram predicts the risk of hepatotoxicity following acute acetaminophen overdose based on a serum concentration obtained ≥ 4-hour post-ingestion. Some patients with low-risk concentrations at 4 hours may have subsequent values indicating increased risk (above the nomogram treatment line), especially if coingestants that slow gastrointestinal motility are involved. The treatment line currently used to identify low risk patients in the United States, Canada, and Australia begins at 150 mcg/mL (993 μmol/L) and intersects at 18.75 mcg/mL (124.1 μmol/L) 16 hours post-ingestion.To determine the incidence of nomogram line crossing after acute overdose of acetaminophen combination products containing an opioid or antihistamine.This was a prospective cohort study of hospitalized patients reported to a regional poison center (RPC) after acute overdose of a combination product containing an opioid or antihistamine. If a 4-hour acetaminophen concentration was detectable but below the nomogram treatment line, the RPC recommended repeat concentrations. Patients were entered into the study if at least one subsequent concentration was available. During follow-up calls hospital providers were queried regarding clinical features, treatment, and indicators of liver injury.Over a 4-year period 76 patients met entry criteria. 5/76 (6.6%) had measureable acetaminophen concentrations below the treatment line at or close to 4-hour post-ingestion followed by values above the line obtained at 6.5-12.5 hours. Four of the five were treated with acetylcysteine and none developed hepatotoxicity. Four of the five had clinical features reported to the RPC suggesting toxicity from the opioid or antihistamine component.After acute overdose of acetaminophen combination products, patients with detectable but non-toxic 4-hour acetaminophen concentrations should have repeat concentrations obtained in a time frame that would allow providers to initiate acetylcysteine treatment, if needed, without undue delay.

Superconducting parameters of different, almost 20 years old Y–Ba–Cu–O samples, prepared in 1987–1988 are investigated. The aim of this research is to find out how a heavy ion beam can enhance the superconducting features of very old and originally not always perfect Y-based specimens. As is observed, their electrical and magnetic characteristics are very sensitive to high-energy Bi-ion irradiation, which results in significant increase of the superconducting parameters. The most important one of them is the global critical current density which is calculated with the help of a new method on the basis of experiments. It can be increased by 18–39%, depending on the original, starting conditions of the samples before the irradiation. At the same time, the average values of intragrain critical current density grows by 37–51%. A slight increase in the critical temperature of 1–2 K was also observed. The experiments on AC susceptibility demonstrate that this irradiation causes to develop faster the total diamagnetic state and decreases the loss. The reason of these effects can be found in the better orientation of crystals, enlargement of microcrystalline aggregates, higher homogenization of the material, thus, in the increase of the superconducting component of samples due to the irradiation.

A new calculation is elaborated for the description of surface changes of temperature and matter due to coupled transport through a porous medium. It is based on a finite-size supposition (Neumann's type boundary condition) and on the solutions of parabolic type partial differential equations combined with Lambert's W-function. The boundary layer phenomena are also incorporated into the description of the general transport. The procedure leads to a direct computer simulation, providing concrete results on the real physical picture of the given problem in good agreement with some experiments analysed.

Introduction: The new standards of the joint commission on accreditation of healthcare organizations specify the patient's right to appropriate assessment and management of pain. With this impetus, we looked at our own practice to see how well we assess and manage patients with pain. Methods: Patients who presented with minor nonemergent pain were interviewed on arrival, and then again before discharge, with use of a structured questionnaire. A total of 68 completed pain surveys were analyzed. Results: With use of a visual analog scale, patients rated their pain on arrival and at discharge; they also rated pain they were willing to accept when it was time for discharge. Sixty percent of the patients went home with more pain than they were willing to accept. Fifty-one percent of the patients were offered something for pain, and only half of them said the pain relief was adequate. The median time from arrival to administration of pain medication was 104 minutes. Surprisingly, the median patient satisfaction rating for overall care was "very good." Discussion: This survey revealed that acute pain conditions are underevaluated and undertreated in one fast-track setting, suggesting that ED staff need more education about the management of acute pain. It also showed that relying on patient satisfaction surveys as surrogate markers for how well we manage pain is erroneous. J Emerg Nurs 2001;27:327-34.

The most important symmetry properties of the incommensurately modulated crystal structures are investigated by use of exact symmetry theory of quasi-one-dimensional systems in the framework of group theory. It is shown that typical characteristic formulae developed for the description of scattering cross sections of one-dimensionally modulated crystals can be directly derived by the line-group technique. A symmetry analysis of static soliton structures is performed, representing a new method for the investigation of elementary excitations of crystals modulated incommensurately. It leads to the description of symmetry breaking, to the selection rules and hints at the similarity of symmetry behaviour of static and dynamic solitons. The actual formulae for Debye-Waller factors in the case of incommensurately modulated crystals are calculated and tabulated by using generating elements of the line groups concerned.

Using a new starting material of Ba2Cu3O5 and a three step heat treatment, single phase Tl2Ca1Ba2Cu2O8 high- superconducting samples have been prepared, possessing the onset- and critical temperatures K and K. The morphology dependent value of is 17 Oe, 8 Oe and 5 Oe at 77 K in the case of bulk, crushed and powdered materials, respectively. The a.c. susceptibility, r.f. susceptibility and microwave absorption properties show a significant dependence on the particle size with a sharp change in the interval between 750 μm and 1200 μm. These experiments provide characteristic parameters for intergrain material (treated as 3D Josephson network) as mm, Oe and A/cm2 at 77 K. The data are controlled by modulated microwave absorption measurements. The results obtained can be explained well both by the finite size junction model and cavity mode absorption model. The Josephson network is determined unambiguously by metallic S-N-S weak links.

Submitting high-Tcsuperconductors to the effect of a large temperature gradient and a thermal pulse, damped oscillation of d.c. and a.c. voltages is detected on the samples. It represents the appearance of a novel type of thermodynamic instability, which manifests itself in temporal fluctuation of normal-superconducting and superconducting-normal transitions of coherent domains, depending on the local structural properties of the material at a given temperature and magnetic field. The strong non-linearity of this phenomenon is attributed mainly to thermodynamic cross-effects, taking into account the dissipation of the vortex motion, too. General motion equations of irreversible thermodynamics characterize correctly the decaying behaviour of the disturbed state.

As is shown, thermally assisted vortex motion can come into being in high-T c superconductors due to the applied temperature gradient. Its behavior strongly depends on the local and global microstructure of the samples, moreover on the temperature and magnetic field. Investigation of the density, size and intensity of the pinning centers of specimens leads to the conclusion that the higher homogeneity immediately weakens and the lower one strenghtens the pinning, thus the former promotes and the latter impedes the vortex motion. The non-equilibrium experimental technique together with a.c. susceptibility measurements render possible the direct determination of the velocity of vortices. Depending on the actual microstructural state of samples it has the values between 6 × 10-2 mm/s and 18 × 10-2 mm/s in the case of Y-Ba-Cu-O specimens investigated.

Repetition of cooling and heating of high-Tc superconductors is detected to be able to result in some change of their microstructure. A non-equilibrium experimental technique provides direct measurement of the velocity of vortex motion in high-Tc Y-Ba-Cu-O superconductors. Its value falls in the interval of 8.3 X 10-2 - 16.0 X 10-2 mm/s depending on the number of the cooling or heating cycles, to which the samples are submitted. The thermal cycling created homogenization of the specimen's microstructure, and is presumed to cause this phenomenon, decreasing the number and strength of pinning centers. This supposition is proved by X-ray diffractography and transmission electron microscopy. A simple irreversible thermodynamic theory is elaborated to describe the reason, direction and dissipative character of the vortex motion.

It is shown that the line group formalism proposed is suitable to describe both commensurate and incommensurate modulations. Symmetry groups of modulated crystal lattices can completely be characterized by symmetry transformations existing in real space, without any application of the formalism based on reciprocal space. As typical examples of the method elaborated, the fundamental invariance and symmetry properties of spin density functions and the soliton lattice are determined.

As a common effect of a large and variable temperature gradient and a temperature pulse, a thermal instability of a new type has been observed in high- T c superconductors. The primary effect is the temporal change of local energy density, that causes a dynamic state of simultaneously coexisting normal and superconducting domains, establishing a spatial and temporal variation of superconducting and normal states. The fluctuation of the ratio of the superconducting and normal volume fractions can be detected by the oscillation of DC and AC voltages measured on the samples. Supposing that every jump of the AC voltage represents the transformation of a single coherent domain, it leads to the average value of the linear dimension of domains as 2.1 mm, characteristic time of the transformation as 7.5 s and velocity of the propagation of this effect as 0.3 mm/s in the case of Y 1 Ba 2 Cu 3 O 7−δ specimens. The macroscopic consequence of the thermal disturbance introduced into the sample is the appearance of a giant flux creep. Its existence is confirmed by comparison of our measurements to others, by analytical and numerical calculations of the forces acting on the vortices and by evaluation of the effect of the huge fluctuation created in the samples by our experiments.

AC susceptibility of ac has been measured simultaneously in three different ranges of Y–Ba–Cu –O ceramic samples in the presence of a large and variable temperature gradient. The results obtained for normal-superconducting or superconducting-normal transitions under the effect of the one-dimensional nonequilibrium temperature distribution reveal the vortex motion to consist of not only conventional flux expulsion (or flux penetration), but flux exchange too, appearing between different ranges of samples and between samples and their close physical environment. The thermal cycles are shown to represent a supplementary heat treatment, increasing the homogeneity of the sample and decreasing the pinning, which accelerate the process of vortex motion.

Line groups are proposed to describe the symmetry properties of systems with non-collinear magnetic structure. A general method is elaborated to obtain the irreducible representation of the symmetry groups of modulated crystals by using that of the line groups. As a demonstrative example, the stuctural phase transition leading to the modulated magnetic superstructure in MnAu2 type compounds is analyzed by the employment of the line group technique. It is shown that the Dzyaloshinskii invariant is the most general one according to the symmetry properties investigated.

A symmetry analysis based on line-group formalism is given for the YBa2Cu3O7 − xhigh temperature superconductor with 7 − x = 6.55, which gives rise to a superlattice phase. The diffuse x-ray scattering intensity curves are calculated for each allowed supersymmetry. An analysis is given for comparison of the experimental and theoretical intensity profiles.

In the thermometric mapping method a large thermal gradient is created along a high-Tcsuperconducting sample. By keeping the lower end of the specimen near liquid nitrogen temperature and by varying the top temperature from above the onset temperature down to the critical temperature, normal and superconducting domains come into being, depending on the microstructure of the specimen and actual values of the local temperature. This operation results in a spatial and temporal change of superconducting and normal states. If a thermal pulse is also applied, it leads to a thermodynamically unstable state, characterized by an oscillation of d.c. and a.c. voltages detectable on samples. The speed of propagation of this effect can be determined on the basis of average transformation times of different experiments, providing values of 0.25–0.33 mm s−1for Y–Ba–Cu–O specimens.

Different methods of deviating efficiency exist for preparation of Hg–Ba–Ca–Cu–O high- T c superconductors. They may be divided into such fundamental groups, which lead to different kinds of Hg-based compounds having unlike macroscopic and microscopic characteristic features. This paper analyses the relationship between some efficient preparation procedures and superconducting properties of different compounds resulting from them. Not only are the effects of practical methods, which produce high-quality single-phase or nearly single-phase materials of the homologous series Hg 1 Ba 2 Ca n -1 Cu n O 2 n +2+δ investigated but the deviations from them and their influence on the developing characteristics of samples are also evaluated.

Low-frequency ac susceptibility measurements on ceramic YBCO superconductors carried out at the presence of a quasi-one-dimensional temperature gradient are compared with those made without the temperature gradient. The values of the different characteristic temperatures measured on samples without and with a temperature gradient are identical but in the second case itch characteristic temperature is a medium value. When the temperature gradient is constant on the sample the arithmetic medium value of the local temperatures is the effective characteristic temperature different phenomena.

Comparing our experimental data collected on intermediate-states instabilities in YBCO superconductors with similar data published in the literature for type-II superconductors we suggest the following: the occurrence of oscillations and limited flux jumps (initiated by external perturbations) in ceramic YBCO superconductors are in no obvious way different from that initiated by magnetic field perturbations in type-II superconductors. For this reason the validity of the adiabatic-stability conditions of the critical state determined for type-II superconductors could be extended to the instabilities in Y based superconductors.

A similarity has been shown among type I-, type II- and high-Tc superconductors with the help of certain experimental examples. According to this the electronic specific heat coefficient, GL-parameter and vortex creation energy are very flexible and sensitive to external impacts, the gap parameter, however, is rather rigid and insensitive against them.

Using the thermal scanning susceptometry, completed with the thermal pulse method, a series of hills has been observed on the susceptibility (real component) curves of Y-based ceramic superconductors. Supposing that these are the manifestations of cooperative vortices (superconducting domains promoted by the granular and defect structure of the material), the medium coherence length (ξ VG ~ 2 mm), medium correlation time (τ ~ 51.2 s), a dynamic ( z ~ 5.7) and a static ( v ~ 1.1) scaling exponents have been determined. Because the determined exponents of the instability are very similar to those predicted theoretically and verified experimentally for vortex-glass structures, we suggest that the observed fluctuations are produced by vortex-glass-like domains.

Ac surface impedances of screen printed thick films and bulk YBCO samples having a wide range of geometrical aspect-ratio are compared. It is shown that very thin (d ∼ 45 μm) samples cut from bulk pellets behave in ac magnetic fields as bulk materials with low aspect-ratio. This demonstrates that the widely accepted explanation for the observation that in ac magnetic fields applied normal to surface of a superconductor film vortex depinning occurs much more easily than in bulk superconductors is a consequence of a high aspect-ratio of the film geometry is not correct. We also show that the ac surface impedance measurement on films is equivalent to the complex susceptibility measurement on bulk samples.

Dc resistivity and ac susceptibility have been measured simultaneously on Y−Ba−Cu−O specimens under the effect of a temperature gradient. During cooling process, an intermediate (normal-superconducting) state of samples forms in the vicinity ofTc and an artificial, local, step-like change of temperature induces an oscillatory relaxation of the measured parameter. This phenomenon has been interpreted in the framework of a vortexglass model as a collective relaxation of vortices inside a domain volume defined by vortex-glass correlation length. Close to theTc the domain relaxation time and the correlation length have been determined as 51 s and 2 mm, respectively.

It is shown by electrical modelling that the appearance and type of the resistivity or conductivity peak depends only on the character (or role) of the energy source used during the normal-superconducting or superconducting-normal transition. Treating the substituting circuit as series resistors (source of constant voltage) or parallel conductors (source of constant current), the response function has a maximum in time (and accordingly by the temperature) giving the possibility for the appearance of a resistivity or conductivity peak in both the case of cooling and heating. It is also demonstrated that the existence of the spatial distribution of local inhomogeneities in the sample is equivalent to the non-uniform temporal distribution of the transition.

Some main features of the non-linear synthesis process are described by theoretical considerations. Results of typical preparation methods are compared to each other and to those obtained by the experiments designed specially for the study of the effect of synthesis on the superconducting properties of Hg−Ba−Ca−Cu−O compounds. As is shown, the controlled Hg-vapour pressure method, the sealed tube with phase formation procedure, the high-pressure synthesis and the freeze-drying method seem to be unambiguously reliable to provide high-quality samples. Significant deviations from these fundamental synthesis routes can lead to significant deviations of superconducting parameters.

Evaluation of the characteristic data of superconducting properties belonging to the samples prepared by different heat treatments demonstrates their strong dependence on the annealing process. It shows that the melting causes much higher superconducting parameters as compared to those produced only by long time solid state sintering even in the case of the same nominal composition.

Various changes in the microwave absorption signals of irradiated samples of different quality YBa2Cu3O7 and Tl2CaBa2Cu2O8 target materials by lowdose (1014 n/cm2) monoenergetic neutrons have been observed and studied. The irradiation induced changes of the shape of microwave absorption lines together with transport measurements show that the low-dose irradiation in poor quality samples increases, while in good quality ones, decreases the superconducting volume fraction. Low quality (non-percolative) samples are more sensitive to irradiation than the high quality ones. These observations indicate that the consequences of irradiation are determined mainly by the preirradiation structure of the samples.

Superconductors provide a wide spectrum of possibilities for sensing different physical effects and actual values or changes of physical quantities, because their fundamental properties are strongly influenced by external conditions. The development of high- T c ceramic superconductors in the form of bulk and film samples has broadened the applicability of these materials for various kinds of sensors and opened a way to design a new class of detectors. Based on some early measurements showing the strong dependence of the microwave properties of high- T c compounds on an external magnetic field, our first device application has been designed to control a thick-film microwave ring resonator by low magnetic field H . In this paper a new and sensitive magnetic-field detector is presented, which is developed from the previous work mentioned above. The quality factor Q of a high- T c superconducting ring resonator is observed to increase and then decrease with the increase of the field strength H in the low magnetic-field range. Q shows a huge change in the field interval 0–3 mT. The value of d Q /d H is 1 dB/18 μT. By using an HP Network Anlyzer of 1 V/dB for this investigation, the accuracy of the measurement of output voltage guarantees to detect the magnetic field with a sensitivity of 1–10 nT.

Different thermodynamic states can develop during the operation of sensors, namely, static equilibrium, stationary non-equilibrium and time-dependent ones, which can be caused by reversible or irreversible processes, namely, spontaneous, generated and fast ones. From the point of view of stability these states can be divided into three categories, stable, unstable and indifferent. (The strong instabilities, such as dissipation, singularities, catastrophes, bifurcation and chaos, may also be investigated by specific apparatus originating from the fundamental thermodynamics.) Certain stability problems can be solved by the method of negative or sometimes positive feedback. The disturbance of an equilibrium state can be described unambiguously by designating new parameters corresponding to the disturbed state. It is shown that the new state is characterized by series of inequalities, the terms of which can be extensive and intensive quantities, non-equilibrium deviations and thermodynamic forces or forces and currents, depending on the character of the given problem. The genuine dynamic stabilization mechanism is connected to the equalization process. It is shown that the actual decay of an external disturbance is not necessarily a monotonic process in time. Some characteristic parameters decrease, while others increase, producing the so-called oscillatory cross effects. Starting from the derivation of the entropy and conductivity matrixes, their analogous properties and role in the conservation of stability are determined. The stability of the stationary or general non-equilibrium states is investigated by variational principles, leading directly to the stability criteria. The possible applicability of the methods presented is demonstrated by various types of examples.

BACKGROUND. Hematologic effects from rattlesnake envenomation exhibit a phenomenon of recurrent, persistent or late, new onset (late) abnormalities in some Fab antivenom-treated patients 4 or more days post-envenomation. Indicators that reliably identify or exclude those patients at risk of late hematologic effects have not been developed. METHODS. This was a retrospective, observational case series of rattlesnake bite records at two US poison centers. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for D-dimer, fibrinogen, platelets, platelet count trend, INR and PTT associated with late hematologic abnormalities, were determined. RESULTS. Three hundred seventy six cases were reviewed. Sixty cases met inclusion criteria. Overall, 17 of 60 patients (28%) had a hematologic abnormality as a result of envenomation. Eleven of 60 patients (65% of those with a hematologic abnormality; 18% overall) developed late hematologic abnormalities 4 or more days post-envenomation. Four patients had late, new onset hypofibrinogenemia and/or thrombocytopenia. All were associated with early D-dimer elevation and/or platelet rise in response to FabAV treatment, respectively. Normal hematologic parameters in the first 48 h post-envenomation and the lack of a greater than 20% rise in platelets within 4 h post-antivenom administration had a 100% NPV for late hematologic effects. CONCLUSIONS. Patients with early onset hypofibrinogenemia, a positive D-dimer, thrombocytopenia, or a 20% increase in platelet count within 4 h post-treatment had a significant likelihood of late hematologic effects. Patients in whom fibrinogen, D-dimer, INR, PTT, and platelet counts remained normal throughout the first 48 h post-envenomation, and who did not exhibit a >20% increase in platelet count within 4 h post-antivenom administration, did not develop late hematologic effects.

The ac susceptibility versus temperature of very pure Y 1.01 Ba 1.95 Cu 2.97 O x , in the presence of huge thermal gradients, has been studied. Five high quality samples are used and no fine structures, only step discontinuities for two of the five samples (presenting thermal cycling and hysteresis) have been observed. A simple model, including the necessary conditions (the existence of at least two components with different specific heat in the sample and, at least for one of them, the validity of the local heating model) for the appearance of the discontinuity is presented.

Creating substantial temperature gradient along bulk samples, gradual superconductingnormal or normal-superconducting transition has been revealed by the measurement of a.c. susceptibility. Different domains transform into superconducting or normal state depending on the local properties of the grains and islands which cause an inhomogeneous transition. Electron optical investigation of the structure of samples proves it to be a fundamental behaviour of the material. This represents an indispensable feature for designing superconducting fault current limiters or high power electric and magnetic equipments.

A brief analysis has been presented on the requirements, difficulties, needs, results and prospects concerning high current conductors produced from hightemperature superconducting materials.

The development of high temperature superconductors offers on the one hand a new possibility for building magnets due to their extremely high upper critical magnetic field, but represents on the other hand rigorous limitations because of their relatively low critical current and rigid and brittle mechanical properties. Among the practicable methods of magnet manufacture the simplest one is to use ceramic spirals with conventional electrical contacts to convey the current. As a second possibility, solenoids of traditional type can be realized, based on cut, electrically contacting rings. Both of these types can be supplied by conventional d.c. electrical treatment. These magnets can, however, create fields of only low intensity and the enormous power dissipation in the contact resistivities causes almost unsolvable cooling problems. In order to avoid these difficulties we have elaborated a new procedure for building high-Tc superconducting magnets, which seems to be more useful from the point of view of applications. They are constructed of individual rings and energized by a contactless external magnetic induction method. Subseqently, the persistent self current provides a magnetic field for every ring. Stacking the rings on top of each other allows the magnetic field strength of the solenoid-like arrangement to be increased, although the small critical current and the thickness of the rings limit its value. Further improvements may be looked for using thick film- or thin layer systems, the high critical current densities of which guarantee a radical increase in the magnetic field. Among the superconducting materials, mainly the YBaCuO and Bi(Pb)SrCaCuO compounds are worthy of consideration.

Measurements on the temperature and frequency dependence of the complex ac susceptibility of sintered Y[sub 1.01]Ba[sub 1.95]Cu[sub 2.97]O[sub x] are reported. The data are used to obtain the flux-creep activation energies at the grain boundaries in the characteristic frequency band. The found nonlinear frequency dependence of these energies can be approximated differently in the low, characteristic, and high frequency bands. The relaxation frequency of thermal fluctuation of the vortex lattice (2[pi][Gamma] [approximately] 3 [times] 10[sup 4] Hz) and the surface current density (J[sub s] = 0-10 A/cm[sup 2]) have been estimated. 20 refs., 4 figs.

The measurement of the ac susceptibility of high- T c superconductors submitted to a large temperature gradient provides information on the inhomogeneous and gradual nature of the superconducting-normal (S-N)and normal-superconducting (N-S) transitions. The variation of the gradient applied to the samples represents the essence of the thermometric mapping method (TMM). As a consequence, the borderline between the superconducting and normal states continuously sweeps the whole specimen, resulting in a huge broadening of the transition, and so its nonlinear fine structure can be observed. Since the details of the S-N or N-S transitions change due to the thermal cycling, its effect can be detected by the sensitive TMM. The experimental results reflect the deviations occurring in the behaviour of the samples and consequently in the properties of the gradual transition caused by the thermal cycles. In this way, the TMM is able to trace the effect of thermal cycling on the local superconducting properties of the materials.

Structural differences between the 1-2-3 type and 1-2-4 type high temperature superconductors were studied by comparing their151Eu and57Fe Mossbauer spectra. The similarities between the corresponding Mossbauer parameters of Eu Mossbauer spectra of 1-2-3 and 1-2-4 compounds demonstrate that the Eu state can be considered to be identical in both perovskites. The changes in the Fe Mossbauer parameters of 1-2-4 type superconductor compared to those of 1-2-3 type compound can be associated with structural differences.

119Sn Mossbauer spectroscopy was used to study an 1-2-4 type material of composition of SnSr2Ca0.5Y0.5Cu3O8+d as well as the precursor SnO. The Mossbauer parameters of the precursor differed from those of the 1-2-4 material. With the 1-2-4 material an abrupt break-down was observed in the electrical resistivity curve at 76 K. No corresponding change could be shown in the Mossbauer parameters.

A novel type of thermoelectromotive hybrid sensor has been developed to detect the position of a liquid level. This sensor utilizes the high thermoelectromotive force (t.e.m.f.) of semiconductors combined with the switching property of new high-Tc materials. The recent highest Tc of about 125 K offers the possibility of detecting the level of a liquid with a boiling point below this value. A markedly enhanced sensitivity of these semiconductor-superconductor hybrid sensors, i.e., up to a few mV/K, compared to those based merely on the t.e.m.f. of a high-Tc material (10−3 times the t.e.m.f. of a semiconductor) is reached by utilizing the high t.e.m.f. of the Si with proper carrier concentration. The prototype hybrid sensor is constructed by combining a high-Tc thick-film conducting line and Si sheet and connecting them electrically in parallel. Sensor output signals even up to volts have been measured. The liquid-level measuring accuracy is about 1 mm.

The real states, processes and stability relations of the operation of sensors have been described by irreversible thermodynamic methods. It has been realized with the help of extensive and intensive parameters, using fundamental properties of the entropy function. General form of thermodynamic motion equations, reasons of irreversibility and non-linearity, authentic non-linear source density functions and variational principles have been given. The causes of ceasing stability and arising unstable states have also been shown. Conditions for strongly non-linear and unstable phenomena (singularity, catastrophe and chaos) have been analysed too. The validity of the theory presented has been demonstrated by specific examples.

Superconducting thick films with the nominal composition of Bi1.9Pb0.4Sr1.9Ca2.1Cu3.2O10 were prepared by the screen-printing method, using an oxalate synthesis for making the paste, and different heat treatments for final samples. A large difference in the structural and superconducting properties between the unmelted and melted samples, and small deviations between the melted and variously annealed specimens were observed. In the first case, the structure is determined by randomly distributed small microcrystals, while in the second, by highly orientated big ones, which results in dissimilar electrical and magnetic features. Therefore the magnetic moment and superconducting material ratio are bigger in the unmelted samples, but in the melted ones, the superconductivity can be characterized by much higher electrical and magnetic parameters. In particular, the transport critical current has conspicuously greater values in the melted as compared to the unmelted samples. In some melted specimens a hyperdiamagnetic signal has been found up to 242 K, induced by the fine details of the preparation technique. The simplest possible reason for this is the diamagnetic Cu−O content in the samples.