Electrochemical nucleation from molten salts—II: Time dependent phenomena in electrochemical nucleation

The double pulse potential step method has been used to investigate the kinetics of nucleation of metal deposition from molten salts and from aqueous solution. The time lag or induction period, τ₀, required for the growth of stable nuclei was determined as a function of overpotential. η. The relationship between log τ₀ and η was found to be markedly non-linear and the existing theory is re-examined and modified to allow for the effect of nucleus size and interfacial tension on the charge-transfer kinetics themselves.     

Age hardening in Cu-2.5 Wt pct Ti

Age hardening in a Cu-2.5 wt pct Ti alloy has been examined as a function of aging time at 300 and 500 °C. Yield strength results exhibited a double peak in strength at each temperature,i.e., peaks at two different times. The work-hardening rate, however, increased monotonically with aging time. Slip line measurements showed that slip became coarser with aging time but remained planar. Lack of sufficient understanding of the details of the pzecipitation reactions and also of hardening mechanisms means that a convincing explanation of the double peak in strength cannot yet be made, but research needed to correct this situation was identified.     

The effect of caffeine on the serum insulin level during intravenous glucose tolerance test in patients with chemical diabetes

A small but significant number of tritiated thymidine labelled cells were found, by autoradiography, in the glomeruli of rats with Masugi nephritis or chronic serum sickness nephritis. There were no labelled glomerular cells in sections of untreated animals. The findings favour the contention that in proliferative glomerulonephritis, glomerular hypercellularity is due to infiltration of monocytic cells into the tufts where they divide.     

Proton-decoupled 31P chemical shift imaging of the human brain in normal volunteers

Proton-decoupled, 31P three-dimensional (3-D) chemical shift imaging (CSI) spectra have been acquired from the entire human brain using a new dual tuned resonator. The resonator operates in quadrature mode to provide improved sensitivity, excellent B1 homogeneity and reduced power deposition at both frequencies. Proton-decoupled and fully NOE enhanced, 31P spectra were acquired from normal volunteers using Waltz-4 proton decoupling with continuous wave bi-level excitation applied through a second radio frequency channel. Well resolved peaks in the phosphomonoester (PME) and phosphodiester regions were obtained from nonlocalized FIDs and spectra localized with 3-D CSI without processing for resolution enhancement. pH measurements made over large regions of the brain using the P(i) resonance show no significant variations (6.9 +/- 0.02) for a single individual. The improved spectral resolution and sensitivity of the PME resonances results in more well defined metabolite images of the PME peak region.     

Grain-boundary slide-hardening in zinc bicrystals

Zinc bicrystals containing high-angle tilt boundaries, and others containing twist boundaries were subjected to constant shear stresses parallel to the boundary at temperatures in the range 20 to 300° C. At stresses both above and below that necessary to cause macroscopic slip in the constituent crystals, the grain-boundary sliding rate decreased with time. This slide-hardening at the grain-boundary was identified with the formation of asperities in the grain-boundary which were generated first near the intersection of boundary and free surface. Removal of the layer containing these asperities restored the boundary behaviour to that of a virgin bicrystal in certain cases. This leads to the conclusion that when slide-hardening occurs, the rate-limiting process for grain-boundary sliding is that associated with the deformation of the crystal regions which have been introduced into the original boundary plane by grain-boundary migration.     

Sebaceous gland inhibition from combined glucocorticoid-estrogen treatment

Sebum production in seven hirsute women was found to be markedly inhibited by low-dosage glucocorticoid therapy, usually 5 to 10 mg of prednisone daily, combined with the cyclic administration of ethinyl estradiol, either 80mug or 100mug daily, in the form of oral contraceptive medication. The average reduction of sebum secretion was 85.7%, from a pretreatment mean value of 3.07 mg of sebum to an average treatment level of 0.44 mg.     

Roughness-Induced Crack Closure: An Explanation for Microstructurally Sensitive Fatigue Crack Growth

The concept of roughness-induced crack closure is utilized to explain the role of prior austenite grain size and pearlite interlamellar spacing on near-threshold fatigue crack propagation in fully pearlitic eutectoid steel tested at low and high stress ratio in lab air and purified helium. It is shown that at low load ratios, near-threshold growth rates are significantly reduced for coarse-grained microstructures, compared to fine-grained at constant yield strength, due to roughness-induced crack closure. Using roughness-profile microscopy, it was found that fracture surface roughness near threshold scaled with grain size and inversely with yield strength, macroscopic roughnesses at threshold being considerably larger than the conventionally calculated cyclic crack tip opening displacement. Auger analysis of near-threshold corrosion products showed it to be iron oxide; the oxide thickness was seen to be decreased by increased stress ratio. The significance of this model to near-threshold fatigue crack growth behavior, in terms of load ratio, microstructure, and environment is discussed. Formerly with Carnegie-Mellon University.     

Tone-induced changes in excitability of abducens motoneurons and of the reflex path of nictitating membrane response in rabbit (Oryctolagus cuniculus).

Tested excitability of the reflex nictitating membrane (NM) response to air puff and of the abducens motoneurons (final common path) to direct electrical stimulation (measured as amplitude of the evoked NM response) in 16 New Zealand albino rabbits at various times after onset and offset of a 350-msec tone. Excitability to air puff showed a substantial increase during tone on and a gradual decrease following tone off, in agreement with J. R. Ison and D. W. Leonard (see record 1971-22356-001). Excitability of motoneurons showed a similar marked increase during tone on, a transient decrease immediately following tone off, and then a gradual decrease. It is suggested that these excitability changes, which parallel closely the interstimulus-interval conditionability function reported by I. Gormezano (1966) for the same preparation, may provide an independent measure of the "molar stimulus trace." Excitability of abducens motoneurons tested in the intertrial intervals during subsequent tone-air-puff conditioning showed no consistent changes. Surprisingly, Ss given tone-abducens nucleus shock testing developed conditioned responses. In subsequent conditioning, using standard tone-air-puff training, they showed 85% savings in acquisition relative to nonstimulated controls. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The maternal and fetal levels of human chorionic gonadotropin, human placental lactogen and prolactin during the perinatal period (author's transl)

The levels of human chorionic gonadotropin (HCG), human placental lactogen (human choriosomatomamotropin HCS) and prolactin (PRL) were determined in the serum of 72 maternity patients and the serum of the newborn infants. The determinations were done with radioimmunologic tests (RIA). These three protein hormones were also determined in the amniotic fluid and in the maternal serum from 4-6 days prior to the delivery of the infant. The concentration of HCG or HCS in the serum of the newborn infants was a mean 0.43 or 0.37% of the level in the maternal serum. The concentration of PRL in the serum of the newborn was 118% and slightly higher than in the serum of the mothers. The concentration in the amniotic fluid was 1.5% for HCG, 5.8% for HCS, and 252% for PRL, compared to the corresponding levels in the maternal serum. The fact that the hormone concentrations in the amniotic fluid are significantly higher than in the serum of the newborn suggests excretion of the hormones from the fetal circulation via the fetal liver and the fetal kidney. The high levels of PRL in the maternal and the newborn serum may be caused by the high concentrations of estrogen or progesterone. Increased during the course of the pregnancy there was a significant sex linked difference in the level of HCG in the maternal serum correlated to the sex of the newborn infant.