Combined radiometric and electrochemical study of the behaviour of Tc (vii) ions at gold and platinized surfaces in acidic media

The sorption and deposition of technetium species formed from TcO ₄ ^– at gold and platinized surfaces was followed by a coupledin situ radiometric and electrochemical technique. It was found: (i) that a layer of TcO₂ species is formed preceding the massive deposition of technetium species, and (ii) that the deposition process is not connected with hydrogen evolution or reaction with adsorbed hydrogen as has been assumed in the literature. An important new finding, the electrocatalytic reduction of ClO₄ ions at surfaces covered by technetium species, was demonstrated on the basis of a comparative study of the phenomena observed in H₂SO₄ and HClO₄ supporting electrolytes.This paper is dedicated to Professor Brian E. Conway on the occasion of his 65th birthday, and in recognition of his outstanding contribution to electrochemisty.     

Leucinosis--a case of congenital metabolic disease in a child

Trasditional Chinese medicine is based on inductive-synthetic reasoning with regard to all life processes, in contrast to the causal-analytic orientation in our Western medicine. This philosophical approach is based on a system of comparisons (equivalents), referred to as Yin and Yang. Vital functions are seen as "energizing" processes, whereby the acupuncture points and the system of meridians are seen as a means of regulation for this "energy". A disturbed balance in this energy results in illness. The therapy according to the acupuncture method is to acheive a balance in the disturbed flow of energy by means of acupuncture points. By utilizing biophysical methods of measurement, it is possible to prove that a change in this energy takes place. The complex active principle which results in the effectiveness of acupuncture includes neurophysiological, biochemical and biophysical functional processes.     

Observation of a half-quantum-flux periodicity pattern in an rf SQUID with small critical currents

We have found experimentally that rf SQUID's working in a nonhysteretic mode with small critical currents give exactly at resonance and at very low rf bias a triangular pattern with a period equal to half of one elementary quantum of magnetic flux. We discuss a possible explanation of this peculiar result.     

Pigmentary glaucoma? Relations to megalocornea

The student population at Edinburgh University was surveyed in 1974 to collect data on women's menstrual cycles and to examine sources of individual differences in reporting symptoms associated with the cycle. 2542 non-oral contraceptive (OC) users and 756 OC users provided data. Both sets of respondents were questioned about the occurrence, both premenstrually and during menstruation, of 9 symptoms. The "physical" symptoms (stomachache, backache, nausea, fainting) were more often reported during menstruation, whereas the so-called "emotional" symptoms (lethargy, irritability, depression, tension, headache) had a greater prevalence premenstrually. When the 9 menstrual symptoms were broken down by students' fields of concentration, arts students were found to report more "emotional" symptoms than those in the sciences and professions (medicine and law). Further analysis showed that only and 1st born children were slightly less likely to report symptoms than those whose nearest sibling is 7 or more years older or younger or later born children. A similar trend was found for the reporting of illness in an earlier analysis of data from this sample. When cycle length and reqularity were analyzed together, women with long and regular cycles were found to have the lowest proportion reporting symptoms during menstruating with the exception of tension, nausea, and fainting, and women with short and irregular cycles had a correspondingly high incidence of all symptoms. In addition, women with more regular cycles were more likely to report infrequent recall of dreams than those with irregular cycles. Overall, the women who are most likely to report menstrual symptoms, especially those of an "emotional" character, are more likely to report other illnesses with emotional connotations, recall their dreams more frequently, show a preference for the arts, and tend to have been brought up with older siblings. This cluster of personality attributes defines an "expressive" personaltiy in contrast to the more "controlled" style of women at the other extreme.     

Effect of prolactin suppression on gonadotrophic secretion in the puerperium

Serum levels of prolactin (PRL), FSH, LH and oestradiol-17 beta were determined by radioimmunoassay in 57 lactating women and in 20 women in whom lactation was inhibited by ergocryptine (CS-154). Women who breast fed their infants exhibited high PRL levels which abruptly declined within 48 h post-partum, and remained low for the duration of the study. Serum FSH was undetectable during the first week post-partum in lactating as well as in CB-154 treated women. Thereafter, lactating women showed increasing FSH levels which reached a maximum by the third week post-partum. These FSH values were higher in lactating women than in the CBS-154 treated group. In contrast, LH levels were higher in those women receiving CB-154. Serum oestradiol-17 beta remained in low levels throughout the study, and no difference was observed between the two groups of subjects. From these results it seems that: 1) inhibition of PRL secretion leads to a faster recovery of gonadotrophin secretion toward the "menstrual type", and 2) PRL suppression produces no effect on the ovarian oestrogen production.     

Synthesis, structure, and field emission properties of sulfur-doped nanocrystalline diamond

The synthesis and properties of sulfur-doped nanocrystalline diamond films were investigated. The films were deposited by hot-filament chemical vapor deposition on Mo substrates using methane, hydrogen, and hydrogen disulfide. The nanocrystalline nature of the material arises from the induction of continuous secondary nucleation in the chemical vapor deposition environment. Complementary characterization tools were employed in order to obtain a comprehensive and coherent understanding of the correlations between the structural and electronic properties. In particular, sulfur-doped nanocrystalline diamond films show n-type Hall conductivity, enhanced field emission properties, and insensitivity to ion radiation. It was found that n-type doping of the tetragonally-bonded carbon matrix together with a nano network of trigonally-bonded carbon are crucial elements for enhanced field emission from nanocrystalline diamond. These conclusions and the corresponding supporting evidence are discussed.     

Patterns of international scientific co-operation in Puerto Rico

Scientific activity has been increasing in Puerto Rico in recent years, a development mirrored not only by the amount of papers published, but by the international links established for scientific co-operation. The purpose of the present study is to identify and discuss the patterns of such co-operation, along with the trends in scientific research conducted in that context at Puerto Rican institutions. The methodology includes an analysis of the main areas of research addressed, defined as the area of specialization of the journals publishing papers indexed in the Science Citation Index (CD-ROM version) from 1980 to 1999. A total of 7271 studies, appearing in 1240 scientific journals, were selected to study the co-operation established between Puerto Rican institutions and organizations in other countries. The findings showed a high rate of international co-operation: 46.07% of the papers published were co-authored by researchers from other countries. The country accounting for the highest percentage of joint research was the USA, followed by Germany, United Kingdom, Canada and Italy. The close relationship between the Puerto Rican and US scientific systems is not unusual, inasmuch as the economic and socio-political bonds between them play an essential role in Puerto Rican scientific activity. The results also revealed substantial differences between the nineteen eighties and the nineties in terms of the nature of the links established, as well as growing internationalization of scientific research conducted on the island over the twenty-year period studied.     

Thermophysical Analysis of Sandstone by Pulse Transient Method

Stones belong to porous materials where water in pores plays an important role during the freeze–thaw process. A thermophysical analysis based on the pulse transient method has been used to study an ageing cycle, namely the freeze–thaw cycle. Thermophysical analysis is based on measuring the thermophysical properties under specific thermodynamic conditions. The transient method determines the specific heat, thermal diffusivity, and thermal conductivity by a single measurement. A specimen of Sander sandstone was analyzed in both dry and water-saturated states. Typical anomalies of all thermophysical parameters at the freeze–thaw point as well as differences for the dry and saturated states were found. The changes of thermophysical parameters measured when using freeze–thaw cycles correspond to stone ageing. The freeze–thaw cycle can often be encountered in building physics, concrete construction, etcPaper presented at the Seventh Asian Thermophysical Properties Conference, August 23–28, 2004, Hefei and Huangshan, Anhui, P. R. China.     

Natural frequencies of a flat viaduct road part simply supported on two ends

Viaduct roads have wide application in big cities with high traffic loads, in order to decrease traffic density and to connect subways to highways. Viaduct roads are constructed using steel structures instead of concrete ones in areas of earthquake risks. The low weight of steel structures however causes problems such as vibration and noise. There is increasing demand especially in populated areas to suppress vibration and noise on highway roads for reducing noise-related environmental pollution. In this study, bending vibrations of rectangular plate viaduct roads, which are supported by six fixed elements of rectangular cross-sectional elements are considered. Natural frequencies are obtained using the Rayleigh-Ritz technique, finite elements analysis, experimentally and neural networks (NN).     

Thermal-induced evolution of secondary phases in Cr–Mo–V low alloy steels

Four low alloy steels with different contents of molybdenum and vanadium were investigated. The steels were annealed at 773, 793, 853, 873, 933, 973, and 993 K for 500, 1000, 3000, and 10000 h. Techniques of transmission electron microscopy and thermodynamic calculations (ThermoCalc) were used to characterise influence of the steel bulk composition and the annealing conditions on evolution of carbides M₃C, M₂C, M₇C₃, M₂₃C₆, M₆C, and MC (M=metallic element). Changes in structure types and metal compositions of the carbides were characterised in detail. The work was done with the intention to obtain more information about the secondary phase evolution in low alloy steels used in energy industries.