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The addition of Ga to Nd-Fe-B sintered and die-upset magnets in order to improve thermal stability was examined. The Ga addition increases the coercivity of Nd(Fe/sub 0.72/Co/sub 0.2/B/sub 0.08/)/sub 5.6/ sintered magnets markedly. Ga addition does not enhance coercivity of sintered magnets with lower Co substitution. Ga addition increases coercivity for Nd-Fe-B die-upset magnets. No decrease in coercivity due to Co substitution of up to 20 at.% is observed for Nd/sub 14/Fe/sub 79.25/B/sub 6/Ga/sub 0.75/ die-upset magnets. This is an advantage of the die-upset magnets compared with the sintered magnets. Ga has a tendency to occur in the Nd-rich phase at higher concentrations than 2 wt.%, and Ga content in the 2/14/1 matrix is around 0.2 wt.% for Nd/sub 14/Fe/sub 79.25/BGa/sub 0.75/ die-upset magnets. For sintered magnets, Ga is distributed between the matrix and the Nd-rich phase. H/sub A/ of the 2/14/1 matrix is increased by Ga addition up to 2.5 at.%. The correlation between H/sub A/ and iH/sub c/ is not good. The Ga-containing Nd-rich phase is observed in the sintered magnets, and the role of Ga in this phase needs to be evaluated to understand coercivity enhancement by Ga addition. >

Behavioral and electroencephalographic effects of lormetazepam were investigated in rats, mice and rabbits, in comparison with those of diazepam, nitrazepam and flurazepam. Locomotor activity of mice in an open-field situation was decreased with large doses of lormetazepam and diazepam, while it was increased with nitrazepam and flurazepam. The anticonflict effect of lormetazepam in rats was much more potent than those of diazepam, nitrazepam and flurazepam. In suppressing the muricide of olfactory bulbectomized and raphe lesioned rats, lormetazepam was more potent than diazepam, nitrazepam and flurazepam. Lormetazepam, diazepam and flurazepam prevented both maximal electroshock and pentetrazol convulsions in mice, the effects on the latter being much more potent than those on the former. Lormetazepam was more potent than diazepam and flurazepam in potentiating thiopental-, ether- and ethanol anesthesia, impairing rotarod performance and in muscle relaxant activity. In conscious rabbits with chronically implanted electrodes, lormetazepam induced a drowsy EEG pattern and suppressed the EEG arousal responses not only to auditory stimulation but also to electrical stimulation of the midbrain reticular formation or hypothalamus. Lormetazepam also inhibited afterdischarges induced by electrical stimulation of the hippocampus and amygdala. These results indicate that lormetazepam has pharmacological properties characteristic of benzodiazepines and that the activity is more potent than those of diazepam, nitrazepam and flurazepam.

Piperidine is one of biogenic amines possessing nicotine-like synaptotropic actions on the nervous systems. Since piperidine produces multiplex pharmacological actions, a role for the amine as a modulator in neuroendocrine as well as neuronal functions has been supposed. In the present study, piperidine levels in the brain and peripheral organs in rats during cold exposure were examined by use of a mass fragmentographic technique and it was found that piperidine concentrations in the brain and peripheral endocrine glands significantly increased at 180 min following exposure to 4°C. The significance of the findings is discussed with respect to the neurohormone-releasing effect of piperidine.

This study investigates the possibility of glutamate and/or aspartate as an excitatory transmitter in the retinohypothalamic fibers' terminal within the anterior hypothalamus, including the suprachiasmatic nucleus (SCN). We studied the release of 3H-Glu and 3H-Asp from the SCN of rat hypothalamic slices produced by optic nerve stimulation. Stimulation of the optic nerve released 3H-Glu, 3H-Asp but not 3H-GABA, while stimulation of the SCN released all three. These releases were suppressed in both Ca2+ free Krebs and tetrodotoxin (TTX) 1 microM containing Krebs. The present result with previous electrophysiological observations strongly suggest that glutamate and/or aspartate are included in this retinohypothalamic termination, while GABA is included in intrinsic and/or extrinsic neurons of the SCN, excluding the terminal of the retinohypothalamic fibers.

The hot working conditions were examined for Nd‐Fe‐B die‐upset magnets. The Nd14Fe80B6 ternary composition has the best workability (die upsetting) from stress‐strain curves for the initial stage of die upsetting at hot working temperature. The compression ratio defined as the inverse of reduction in height should be larger than 4 to have materials aligned. Alignment of c axis along the compressive stress direction is obtained, but grain coarsening occurs during die upsetting. Of several additional elements investigated, Ga is the best for enhancing the coercivity with a little sacrifice of remanence and no deterioration in hot workability. Typical magnetic properties for Nd14Fe79.25B6Ga0.75 die‐upset magnets are Br =12.4 kG, iHc =19 kOe, and (BH)max =36 MGOe. The irreversible loss after exposure up to 160 °C is under 10% (Pc =2). The iHc of powder made by crushing the die‐upset magnets is nearly independent of particle size. Decrease in iHc by pulverizing to several hundred micron is about 2 kOe. Anisotr...

Piperidine is a biogenic alicyclic amine possessing potent pharmacological activity. Interest has recently been focussed on its possible role as an endogenous hypnogenic substance. Using a mass fragmentographic technique with deuterium-labelled piperidine as an internal standard, the time relations of the change in brain levels of piperidine and the anesthetic activity of urethane were determined in mice. The brain piperidine level increased prior to the loss of the righting reflex and the elevated level declined prior to the reappearance of the reflex. The change in brain piperidine level correlated with neither that in spontaneous motility nor that in body temperature. The findings favor the idea that piperidine might at least partly regulate the level of consciousness.

A trial to make Nd-Fe-B rapidly quenched flakes anisotropic by grain growth during heat treatment in the magnetic field has been carried out. No magnetic anisotropy is observed, but the optimum heat treatment temperature is lowered by about 100°C by applying 14 kOe of magnetic field. There is, as yet, no explanation of this phenomenon. Another way of making anisotropic bonded magnets is to use pulverized powders of anisotropic dense die-upset magnets as a starting material. By examination of the process parameters for Nd-Fe-B die-upset magnets it was found from stress-strain curves that the Nd 14 Fe 80 B 6 ternary composition has the best workability and to achieve aligned material the compression ratio (defined as the inverse of reduction in height) should be larger than 4. Grain coarsening resulted in a decrease in coercivity ( i H c ) during die upsetting. Ga is the best additional element for enhancing i H c with a little sacrifice of remanence ( B r ) and no deterioration in hot workability. Further improvement of thermal stability by raising the Curie temperature ( T c ) of the Nd-Fe-B-Ga alloy can be achieved by Co substitution. The i H c of the powder made by pulverizing the die-upset magnets is nearly independent of particle size. Anisotropic bonded magnets were developed using this powder. The ( BH ) max of compression-moulded magnet with Ga addition and Co substitution, Nd 14 Fe 71.75 Co 7.5 B 6 Ga 0.075 , is 15 MGOe. The irreversible losses after exposure up to 140°C is lower than 5% ( P c =2), which is sufficient thermal stability for polymer-bonded magnets.

We discuss the inverse Sturm-Liouville problem on a finite interval by the method of transformation kernel. The τ-function, the Fredholm determinant of the transformation kernel, is explicitly written down in terms of the spectral data, from which a very explicit representation formula for the potential is deduced, and well-posedness of the inverse problem is established. The above method is also applicated to the inverse problem for Hill equations, in particular to the isospectral problem. We obtain an analog of FIT formula and a regularity theorem.

Intraterminal free Ca2+ concentration modulates the subsequent release of neurotransmitters. Depolarization of synaptosomes with 29 mM K+ augments cytosolic free Ca2+ concentration, which is triphasic, the peak times being at 10, 60, and 180 s. We examined the characteristics of each elevation of cytosolic free Ca2+ concentration in rat brain synaptosomes which had been preincubated for 3 min with a Ca2+-channel blocker, such as La3+, diltiazem, nifedipine, or verapamil, and under conditions of hypoxia or acidosis. The concentration of free Ca2+ in the quin-2-loaded rat brain synaptosomes was detected fluorometrically. All these elevations were suppressed in the presence of 200 microM EGTA or 100 microM La3+. At the first phase, the elevation of cytosolic free Ca2+ concentration with high K+ stimuli was significantly inhibited by La3+ (20 microM) or by acidosis (pH 6.7). On the other hand, diltiazem, which is a more potent blocker of the release of Ca2+ from the mitochondria, inhibited the increasing cytosolic free Ca2+ concentration at the third phase in a concentration-dependent manner. Hypoxia also showed inhibition at the third phase. These results suggest that the augmentation of high K+-evoked cytosolic free Ca2+ concentration may be due to the influx of extracellular Ca2+. The increase in cytosolic free Ca2+ concentration at the third phase is no doubt linked to the mitochondrial function.

Bilateral olfactory bulbectomy of the rat caused marked changes of noradrenaline level in several brain regions accompanied with the development of mouse-killing behavior (muricide). Noradrenaline level increased in the medial amygdala, ventromedial and lateral hypothalamus in muricidal olfactory bulbectomized rats (OB rats) but not in non-muricidal OB rats, while dopamine level decreased in the lateral hypothalamus in muricidal OB rats. Acute administrations of desipramine not only suppressed muricide of OB rats but normalized noradrenaline change in ventromedial hypothalamus and dopamine change in lateral hypothalamus. Chronic administration of desipramine also suppressed muricide and normalized noradrenaline changes in ventromedial and lateral hypothalamus and medial amygdala. These findings suggest that the increase in noradrenaline levels in the medial amygdal, ventromedial and lateral hypothalamus may be important for the induction of muricide in OB rats, and muricide was suppressed by desipramine in accordance with the normalization of increased noradrenaline levels, and that the change in dopaminergic function in the lateral hypothalamus may also be important for this muricide.

The mechanism eliciting mouse-killing behavior (muricide), induced by bilateral olfactory bulbectomy, has been shown to involve the brain noradrenergic system; this is because muricide is specifically inhibited by the drugs which potentiate the activity of catecholaminergic neurons such as tricyclic antidepressants. Our previous reports also demonstrated that the hypothalamic noradrenaline (NA) contents increased in the rats which exhibited muricide. To further examine the hypothalamic noradrenergic function in muricide, a push-pull perfusion technique was applied for direct measurement of NA release from the lateral (LH) and ventromedial (VMH) hypothalamus in freely moving rats. Subsequently, the perfusates, including catecholamines and their metabolites were measured by means of high-performance liquid chromatography with electrochemical detection (HPLC-ECD). Three days after olfactory bulbectomy, 67% of the rats elicited muricide and NA release from LH tended to decrease. Moreover, 7 days after olfactory bulbectomy, most of the rats elicited muricide and NA release from LH was significantly decreased, but not from VMH. On the other hand, dopamine (DA) release from VMH without LH conversely increased on the 7th day after olfactory bulbectomy. These results suggest that the dysfunction of the noradrenergic system caused by the decrease in NA release from LH played an important role for the incidence of muricide.

A specific and sensitive method for analysis of brain pyrrolidine, a volatile amine with potent synaptotropic actions on the peripheral and central nervous systems, was devised. The method involves the isolation of volatile amines by steam distillation and the qualification and quantification of pyrrolidine by gas chromatography/mass spectrometry (gcms) including a selected ion monitoring technique with deuterium-labeled pyrrolidine as an internal standard. The lower limit of quantification for the method was 2 pmol, and the mean concentration of pyrrolidine in the rat whole brain was determined to be 95 pmol/g of tissue.