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The authors report two cases of postanesthetic delirium in patients receiving intravenous atropine sulphate before surgery. In the first case the diagnosis of atropinic syndrome has been suggested by a cause effect relationship; in the second case the diagnosis has been supported by the prompt resolution after intravenous physostigmine salycilate administration. Since such syndrome was never observed in patients receiving atropine sulphate as i.m. premedicant, authors are prone to consider the i.m. route a safer approach to premedication with this drug.

We present the first evidence by acoustic measurements of H tunneling and trapping by O atoms in a rare-earth--hydride system. The YO{sub 0.0027}H{sub 0.016} alloy presents three new elastic-energy-loss peaks most likely due to H trapped by O between 1.4 and 330 K. The peak at the lowest temperature is due to tunneling of the trapped H; its relaxation rate strongly depends on temperature indicating a dominant contribution of multiphonon processes already at a few degrees kelvin. The other two peaks, with activation energies of 0.14 and 0.22 eV, can be attributed to jumps of H in the distorted environment of the O atom.

The anelastic relaxation is one type of mechanical response of solids in which, on applying a stress, besides the instantaneous elastic response according to Hook’s law, a retarded strain is found [1]; it is the mechanical analogue of the dielectric relaxation. However, whilst some work has been done in order to see the effect of the random interactions between dipolar impurities on dielectric relaxation, little has been done in this direction for anelastic relaxation.

An intense peak of the elastic energy loss versus temperature is found in La 2 CuO 4 at 150 K (in the LTO phase), at a vibration frequency of ∼280 Hz. From the dependence of the dissipation curve on frequency it is deduced that the relaxation rate has an activation enthalpy of 0.23 eV. The peak is ascribed to a thermally activated dynamics of the tilts of the CuO 6 octahedra which form the La 2 CuO 4 lattice, a fraction of which are supposed to be able to switch between energetically equivalent configurations. The peak is suppressed by interstitial O; this is explained by supposing that each interstitial atom can block several octahedra into a configuration that can accommodate the distortion due to its presence. Increasing the content of excess O, two new thermally activated processes develop, attributed to the hopping of interstitial O atoms which are isolated and which are paired or otherwise aggregated. The activation enthalpy for the diffusion of O at low values of δ is 0.48 eV.

Anelastic relaxation measurements were made on polycrystalline YBa 2 Cu 3 O 6+x with x close to 1. Among the three low-activation-energy processes which are present, that with the lowest activation enthalpy ( H ∼ 0.08 eV) is the most sensible to small variations of the O stoichiometry and becomes undetectable when x p z holes in the apical oxygens, which have been previously observed by X-ray absorption spectroscopy in highly doped YBa 2 Cu 3 O 6+x , and which are supposed to be far less mobile than the conducting holes.

We measured the elastic energy dissipation of Y 0.7 Pr 0.3 Ba 2 Cu 3 O 6+x between 50 and 930 K at various O concentrations. All the features observed in RBa 2 Cu 3 O 6+x were substantially reproduced in the partially Pr substituted sample. In addition, a new dissipation peak was observed around 400 K (0.7 kHz), due to a relaxation process with an activation energy of ≈0.8 eV. The peak width is about twice that of a single relaxation process, and its intensity is maximum when most of oxygen is removed from the CuO x planes. It is proposed that the process involves a configuration of three O atoms around a same Cu(1), which is supposed to be stable only in a cell containing a Pr ion.

It is reported on new anelastic relaxation measurements in ReBa 2 Cu 3 O 6+x for 0 x planes in the various phases is discussed, and the two thermally activated peaks of elastic energy dissipation observed above room temperature are interpreted in that framework. A new structural phase transition around 480 K is observed.

Acoustic emission activity during hydride formation in niobium, tantalum and vanadium was detected as a function of temperature by measuring the ringdown count rate, the total count of events and their amplitude distributions. Resonance frequency and internal friction measurements were also conducted on the same specimens to detect the occurrence of hydride precipitation and the plastic deformation phenomena accompanying the formation of the misfitting precipitates. The acoustic emission and growth of cracks within the nucleation and growth of cracks within the hydride precipitates.

The anelastic relaxation spectrum of the Nb-5 at.% Ti system has been investigated for various deuterium concentrations, cD, between 0.07 and 1.76 at.% in the temperature range 1.2-300K. Three relaxation processes located around 170, 100 and 50K have been observed at a vibration frequency of 20 kHz, and a marked frequency-dependent rise of dissipation is measured below 5K. The maxima increase in height and shift in temperature with increasing deuterium content, but the shifts of the high- and low-temperature peaks are of opposite sign. The peak at the lower temperature grows with the square of cD and becomes the predominant process at higher concentrations. The relaxation processes are attributed to the stress-induced reorientation of titanium-deuterium complexes. These observations are interpreted under the assumption that interaction with Ti substitutionals shifts the energies of the trapping sites occupied by deuterium atoms randomly.

Mesures du frottement interne a la temperature de l'helium liquide dans des echantillons de Nb et Ta contenant de l'oxygene et dopes par de l'hydrogene. Interpretation des pics observes par un systeme a 2 niveaux, ces pics etant attribues a un effet tunnel de H piege par O

The effects of deuteride precipitation from Ta-D solid solution was investigated by vibration frequency and internal friction measurements in the temperature range (80–300) K. Initiation of deuteride precipitation is indicated by the inflexion of the frequency curve, whereas the onset of the dislocation-loops formation around the deuteride particles is correlated with the internal friction growth (precipitation peak). The dislocation interstitial drag model which seems to better account for the precipitation peak, is discussed. The phase diagram of the Ta-D system was determined in the range of (0.2–7.5) at.∼%.

The internal friction spectrum of Nb-Ti-H systems has been investigated from 250 to 1.4 K at frequencies ranging from 2.5 to 74.5 kHz. At intermediate temperatures two maxima have been observed which are attributed to various types of Ti m -H n complexes. At low temperatures two new peak appear whose features markedly deviate from classical behaviour.

The nature of the phase transformation occurring in YBa2Cu3O7-x at 240 K has been investigated by internal friction and frequency measurements. The hysteresis in the frequency (elastic constants) reveals a slow kinetics, and the nonrecoverable raise of dissipation around 240 K generated by thermal cycling is attributed to the nonelastic accommodation of the 2nd-phase misfitting domains. A model is proposed to interpret the observed phenomenology and the unstable enhancements of Tc above 100 K reported in the literature. According to this model, local Tc enhancements are caused by the strains generated by the 2nd-phase domains, and this explains the strong dependence of the Tc increase on the thermal hystory of the sample.

Hydrogen in solid solution in metals has a considerable mobility even at very low temperatures. In the Nb-O(N)-H and Nb-Ti-H systems new thermally activated anelastic processes were observed between 1.3 and 40 K for flexural resonance frequencies of 20 and 75 kHz. These effects are attributed to the motion of hydrogen kept in solution by the trapping centres formed by interstitial oxygen (nitrogen) and substitutional titanium. The internal friction curve of the Nb-O(N)-H system is characterized by a single relaxation time, whereas the relaxation spectrum of Nb-Ti-H, despite its simpler crystallographic symmetry, displays several components. The relaxation strength of both processes increases with increasing peak temperature.

The presence of hydrogen in Nb containing O and N interstitial impurities gives rise to a relaxation process at liquid helium temperature. The effect, studied by exciting two vibration modes of the specimen (20 and 75 kHz), can be described by a single Debye curve and is characterized by an apparent activation energy of 1.8 meV and by the rise of the relaxation strength with increase of peak temperature.

The hydride precipitation in the Nb‐H system has been studied by the acoustic‐emission technique varying the temperature between 330 and 225 K at hydrogen concentrations ranging from 3.8 to 5.8 at.%. Concomitantly, elastic‐modulus and internal‐friction measurements have been conducted in order to reveal the hydride‐precipitation temperatures and the plastic‐deformation phenomena occurring during the formation of the hydride misfitting precipitates. In the virgin material, acoustic emission is absent during evolution of the precipitation although the dislocation‐multiplication processes are operative. When, due to a severe precipitation, a certain degree of deterioration of the material has been reached, acoustic activity characterized by discrete bursts is then stimulated by the hydride formation and definitively persists also after the high‐temperature annealing. The temperatures of the onset of the acoustic emission are lower than those corresponding to the hydride precipitation and may fit a line paral...

The relaxation of an atom pair consisting of a substitutional atom and a tetrahedral interstitial atom in the b.c.c. lattice is studied theoretically. The pair exhibits three relaxation modes: one T 2g and two E g modes. The relative relaxation magnitude of the two E g modes depends strongly on the anisotropy of the λ tensor. Experimental results of internal friction studies of Nb[sbnd]Ti[sbnd]H and V[sbnd]Ti[sbnd]H alloys are discussed in the light of the present analysis.

One struma ovarii with agregates of epithelial nests indistinguishable from Brenner tumor was studied. The presence of a communication between the nests and the follicles and the association of Brenner, mucinous and respiratory epithelium in the lining of 1 cyst in the same tumor strongly support the germ cell theory of Brenner tumors associated with teratomatous elements.

Low-temperature specific-heat measurements (0.06--2 K) on a superconducting polycrystalline NbTi/sub 0.05/ alloy show an anomaly in the presence of interstitial H and D (up to 3 at. %). The excess specific heat is roughly linear in temperature, indicating the existence of a glasslike low-energy excitation spectrum. The results raise the question as to what extent previously observed low-temperature anomalies in metallic glasses may be due to H contamination.

The anelastic relaxation spectrum between 300 and 50 K has been investigated in YBa 2 Cu 3 O 7−x in the super- and semiconducting state. In the superconductor a phase transformation has been detected at T t ≃ 240 K . The 2nd phase forming on cooling, likely has the same orthorombic symmetry (with higher distorsion) of that of the lattice and consists of a different oxygen vacancy ordering in the chains of the basal planes. The necessity of a phase diagram where the two orthorombic phases coexist in an extended region down to low temperature is pointed out. The 2nd phase is considered to contribute to the observed softening and hysteresis of frequency (elastic constants). The raise of elastic energy dissipation around T t with thermal cycling, which is not completely recoverable by the room temperature ageing, indicates the occurrence of progressive lattice damaging with cycling number, and is attributed to the non-elastic accommodation of the 2nd-phase misfitting domains. These lattice defects are identified with the additional twins, which have been reported to form and dissolve on cycling below 240 K. Other reproducible features observed in the superconducting state are dissipation maxima at 160 and 110 K, just above the critical temperature and a drastic decrease in dissipation below T c . When oxygen has been removed from the basal planes (6.2 ± 0.10 atoms per formula unit) all processes illustrated above practically disappear and a new intense thermally activated relaxation process manifests itself around 70 K (in the kHz range), attributed to the stress-induced hopping of oxygen in the basal planes. The derived diffusion coefficient is extremely high: D(T) = 4 × 104 exp (− 0.10 eV/kT ).

The anelastic relaxation at intermediate temperatures (100-200K) in metal-hydrogen crystalline systems containing trapping centres presents anomalous features like a shift of the peak temperature and a variation of its apparent activation energy with hydrogen content. New results obtained in Nb-5 at.% Ti-H, Nb-2 at.% Ti-H and Nb-0.5 at.% Ti, and the existing data, have been interpreted by a comprehensive model which assumes a distribution of the interstitial site energies according to a density of states function. The process is thought to be originated from superposition of the elementary relaxations of Ti-H pairs whose population as a function of temperature and H concentration has been calculated using Fermi-Dirac statistics. The close similarity with the relaxation recently observed in amorphous materials and A15 superconductors doped with H indicates that the present behaviour is characteristic of the hydrogenated systems.

The distribution of noninteracting interstitial atoms in a lattice containing trapping centers is studied using Fermi-Dirac statistics. Assuming that the energies of free sites and trap sites are distributed according to density-of-states functions, the populations of the various types of clusters are calculated as a function of concentration and temperature; the only form of interaction between interstitials taken into account is represented by the inhibition of some types of clusters. The results are satisfactorily applied to internal friction to explain the anomalous relaxation observed in crystalline and amorphous metal-hydrogen (deuterium) systems.

The amplitude independent internal friction has been measured in a series of vanadium-hydrogen alloys in the temperature range from 4.2 to 450°K, the vibration frequencies being included between 2 × 102 − 1 × 105 Hz. Experimental evidence has been obtained of an anelastic effect occuring near 20°K in cold-worked pure vanadium; its activation energy and its frequency factor are 0.012 eV and 5 × 107 Hz, respectively. The introduction of hydrogen in the prestrained material brings about a relaxation effect near 203°K, which is shown to be the hydrogen cold-work peak. A third relaxation effect, observed in prior annealed and then hydrogen doped vanadium, appears to be a suitable means for studying the phase diagram of V–H system.

An acoustical technique is proposed for determining the thermal diffusivity in solids and the relative difference between the molar heat capacities at constant pressure and at constant volume. The method, which consists essentially of measuring the damping of freely vibrating bars, allows determination of the thermal diffusivity with an accuracy better than ±5% and has the advantage of not requiring a heat source. It also largely eliminates the complications of precise temperature measurements and insulation of specimen holders. Results are given for tantalum and vanadium over the temperature range 60–300 K.

The internal friction of deuterium-doped vanadium has been investigated in the temperature range from 65 to 350 K. At low deuterium concentrations (≦0.18 at.−%) a relaxation effect has been observed near 90 K; its activation energy and its limiting relaxation tiem are 0.17 eV and 2×10−12 sec, respectively. A second internal friction peak (precipitation peak) appears in more heavily doped samples; the position of this second peak shifts to higher temperatures as the deuterium content is increased. Possible mechanisms for the two peaks are discussed. The phase diagram of the vanadium-deuterium system at low temperatures has been deduced from the correlation between the deuterium concentration and the position of the precipitation peak.

The diffusion coefficient of interstitial oxygen atoms in tantalum has been determined by measurements of the elastic energy dissipation as a function of the temperature. The relaxation peak related to this process was found with its maximum at 346 °C for a vibration frequency of about 20 kHz. The analysis of the experimentl data give an activation energyW=1.19 eV and a diffusion constantD 0=1.9 · 10−2 cm2/s, in very good agreement with some previous results obtained at very low frequencies. A description of the new features of the experimental technique is also given. Был определен козффициент диффуэии внутренних атомов кислорода в тантале, путем иэмерений упругой знергетической диссипации, как функции температуры. Был обнаружен релаксационный пик, свяэанный с зтим процессом, с максимумом при 346 °С для частоты колебаний около 20 kHz. Аналиэ зкспериментальных данных дает знергию активацииW=1.19 зВ и постоянную диффуэииD 0=1.9·10−2 см2/сек, что находится в очень хорощем согласии с некоторыми предыдушими реэультатами, полученными при очень ниэких частотах. Также приводится описание новых особенностей зкспериментальной техники.

The internal friction has been measured as a function of temperature in a series of tantalum-hydrogen alloys with atomic ratios varying from H/Ta⩽0.005 to 0.17. The temperature of the measurements cover the range (78÷450) °K; the vibration frequencies are included between 1.5·102 Hz and 1.0·105 Hz. Two anelastic relaxation peaksP1 andP2 have been observed near 100 °K and in the range (180÷300) °K, respectively. The behaviour of these peaks has been studied in connection with the phase compositions of the Ta-H system. The second relaxation effectP2 is found to be a suitable tool for investigating the phase diagram of the system; its activation energy is (0.38±0.05) eV and its limiting relaxation time 2·10−14 s.

Internal friction measurements in the kHz range have been performed on Ta containing D, O, and N at liquid-helium temperature. A relaxation process is observed below 60 K showing a sharp discontinuity in the slope at the normal-superconductor transition temperature. The process is interpreted as relaxation of a two-level system consisting of O (N)-D complexes interacting mainly with the conduction electrons.

The presence of hydrogen in niobium containing 5 at. % alloying titanium gives rise to new relaxation processes at liquid helium temperatures. The effects have been studied for two H concentrations (0.08 and 0.48 at. %), and by exciting two resonance modes of the specimen (20 and 74.5 kHz). The temperatures at which the processes occur are independent of H content and their intensities increase with increase of the H concentration. At the lower resonance frequency the peaks shift towards lower temperatures and their intensities markedly decrease. This latter behavior may be explained by a delocalized tunneling model for hydrogen trapped by Ti.

The Au-0.03at% Fe/Chrornel P thermocouple was calibrated between 1 and 300 K to monitor the temperature of freely vibrating specimens in measurements of elastic energy dissipation. In the intermediate temperature range (50–23 K) the calibration points were obtained by means of a miniature sealed cell containing oxygen, which gave three fixed points: the O 2 triple point, 54.3610 K; the β-γ transition, 43.802 K; and the α-β transition, 23.873 K.

The first measurement of anelastic relaxation in a vibrating sample of YBa/sub 2/Cu/sub 3/O/sub 7-//sub x/ is reported. A marked drop in the dissipation is observed below T/sub c/, from which a strong electron-phonon interaction is inferred. It is found that the Bardeen-Cooper-Schrieffer theory with a gap of ..delta../k/sub B/ = 240 K can explain this drop. The data also suggest the occurrence of a phase transition at 235 K.

Electrical resistance measurements have been conducted in YBa2Cu3O7-x in the temperature range 80–350 K before and after the metal to semiconductor-like transition induced by vacuum annealings at 570 and 640°C. In the semiconducting phase (7 - x = 6.2 ± 0.2), the temperature dependence of resistivity closely follows the exponential law of classical semiconductors with an energy gap Eg = 0.77 eV.

Deuterium trapped by oxygen (nitrogen) in niobium gives rise to two anelastic relaxation processes at 1.5 and 4 K at 20 kHz. The process at higher temperature and the analogous one observed in Nb-O(N)-H have been interpreted in terms of a two-level tunneling system (TLS) interacting with phonons or electrons. Two-phonon and electron interactions in the superconducting state give nearly equivalent fits to the data. In both cases the tunneling matrix element is found to be about 0.9 MeV without appreciable isotope effect; the coupling parameters of the TLS to electrons and phonons have also been estimated.

Internal friction and resonant frequency measurements have been carried out in $\mathrm{Y}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}x}$; after oxygen outgassing the material becomes semiconducting Y${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6}$ and the anelastic processes observed in the superconducting samples are suppressed. Instead, a new intense effect appears: The process is thermally activated (shifting from 56 to 75 K when the frequency changes from 1.1 to 17.4 kHz) with an activation energy ${E}_{s}=0.11$ eV, and is only 25% broader than a single relaxation time process. It is attributed to the stress-induced hopping of residual free oxygen and the derived diffusion coefficient is $D=4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}\mathrm{exp}(\ensuremath{-}0.11 \frac{\mathrm{eV}}{\mathrm{kT}})$ ${\mathrm{cm}}^{2}$/sec, which extrapolated to room temperature is comparable with that of hydrogen in transition metals.

The effect is studied of repeated thermal cyclings on the acoustic activity of the Nb-H system during hydride precipitation.

The mobility of hydrogen and its isotopes in metals has been the object of investigation for several years, whereas the diffusion studies of H in doped semiconductors started more recently. Although the H diffusion coefficient in metals may be several orders of magnitudes higher than in semiconductors, the dynamics of H in metals and semiconductors presents many common features, like precipitation, trapping by heavier impurities and, as indicated by recent results, quantum tunneling at low temperature.In boron doped silicon, the relaxation rates τ−1(T) of H around B obtained from anelastic relaxation were joined with those from infrared absorption: the remarkably wide range obtained (11 decades) clearly shows a deviation of τ−1(T) from the classical dependence at low temperature. However, the results obtained and their analysis do not allow yet to draw conclusions on the mechanism governing the H(D) dynamics.Recently, the investigation of the dynamics of H(D) in GaAs doped with Zn revealed a dissipation peak at 20 K in the kHz range. This relaxation has the highest rate found for H in a semiconductor: more than 15 orders of magnitude higher than in all the other semiconductors measured so far. The analysis of the dissipation curves clearly indicates that the nature of the H reorientation is quantistic.In metals two regimes of the H mobility are observed: hopping with deviations from a classical Arrhenius motion, and a much faster tunneling within few close sites. In the latter regime the H dynamics does not consist of jumps but of transitions between the quantized energy levels of the tunnel systems. The types of interactions assisting the H transitions and the geometry of the tunnel systems are an open problem: although the two-level tunnel system (TLS) has been widely used to explain neutron diffusion, specific heat, and acoustic spectroscopy results in interstitial solutions (NbOxHy), recently this model has appeared not to be valid in substitutional solutions (NbZrxHy, NbTixHy) where the tunnel systems have a higher symmetry. The four-level systems seem to be more appropriate, although the corresponding model has not been developed as much as the TLS yet.