Binary,ternary and quaternary complexes invloved in the systems pyridoxamine-glycine-imidazole with some bivalent metal ions

Equilibrium-based computer models using MINIQUAD-75 program were utilized to determine the stoichiometry and formation constants involved in the systems pyridoxamine(Pm)-glycine (Gly)-imidazole (lmd) with CO(II), Ni(II), Cu(II), Zn(II) and Cd(II) metal ions. The data were obtained from potentiometric pH titration of the various binary and ternary quaternary systems under physiological-like conditions (0.15 M NaNO₃-37°C). Various composition ratios of metal and ligands were used. The ligand concentrations did not exceed 4 times the concentration of metal ion in the binary systems and 4 times of the metal ions in ternary systems. In case of the quaternary systems only imidazole concentrations were two or four times the concentrations of metal ions keeping those of other ligands equal to that of metal ions. The stability constants of the quaternary species are discussed in terms of binary and ternary constants as are the effect of ring size on the stability of mixed ligand species. In addition, electrostatic as well as statistical effects also are mentioned and the biological implications of these model equilibria are described.     

OnL p -convergence rates for statistical functions with application toL-estimates

Summary A parameter which may be represented as a functionalT(F) of a distribution functionF may be estimated by the “statistical function”T(F _n ), whereF _n is the empirical distribution function. Recently, Boos and Serfling (1979, Florida State University Statistics Report No. M 499) obtained sufficient conditions for the Berry-Esseen theorem to hold forT(F _n )-T(F) and applied the results to derive rates of convergence inL _∞ forL-estimates. The present note complements their work by obtaining theL _p -rates of convergence, 1≦p<∞ forT(F _n )-T(F) and its application toL-estimates.     

Energie de cohésion des composés MAX (M ≡ Ca,Sr,Ba; A ≡ H,F; X ≡ Cl,Br,I) de structure PbFCl

The Madelung constant, the electrostatic and repulsive energies of the compounds MAX, with the PbFCI structure (D⁷_4h), are calculated and compared with the experimental cohesive energy. This calculation yields a crude estimate of the Van der Waals energy. The special case of CaHBr is discussed.     

Time domain identification of standing wave parameters in gas piping systems

A method for experimentally determining the natural frequencies and modal pressures of an air or gas piping system is presented. Such information is of interest in installations where pressure pulsations caused by pumps or compressors are of importance. In the method a time domain based technique is used which was originally developed as an alternative to frequency response methods for determining the vibration parameters (natural frequencies, modes, damping factors) of structures, to avoid difficulties often encountered in interpreting complex and non-conclusive frequency response data such as arises from systems having numerous modes, some of which may be highly damped or closely spaced in frequency. In this application, a straight steel pipe with a sound source at one end and closed at the other end was used. Two microphones were used to measure the pressure at two locations in the pipe. The free pressure response following a rapidly swept sinewave input was recorded, digitized and then used in a computational procedure based on a lumped parameter representation of the system. The natural frequencies and the corresponding modal pressure ratios at the two stations, thus obtained, are compared with mention here that although in the experiment reported here an external frequency sweep excitation was used, the technique works as well with free decay response after a system shut-off, impulse response or random responses from normal system operation.     

Broad band random excitation of a two-degree-of-freedom system with autoparametric coupling

The response of a two-degree-of-freedom system with autoparametric coupling under the action of broad band random excitation is investigated. The system corresponds to the autoparametric vibration absorber and is also typical of many common structural configurations. A method based upon the Markov vector approach, together with an approximate treatment of third and higher statistical moments, is used to derive a set of fourteen coupled non-linear equations for the first and second moments of the system responses. A numerical integration procedure is used to obtain quantitative results for the system mean and mean square responses over a range of system parameters.The results show that large random motions of the coupled system may occur when the internal detuning parameter is close to the principal internal resonance, and that these motions may give rise to a suppression effect on the random motions of the main system. A feature of the results is that under conditions of internal resonance the random motions are found to be quasi-stationary, with steady oscillatory terms in the response moments. This suggests the possibility of entrainment of regular harmonic responses by the system random motions.     

Generalized Einstein static universe

We consider the equilibrium configurations for static spherically symmetric self-gravitating perfect fluids in general relativity. The fluid obeys an equation of state which is the extreme limit allowed by Hawking's strong energy condition. The new solutions we have found are generalized Einstein static universes which have a Killing horizon similar to the one we are familiar with from the vacuum Schwarzschild solution.     

Spectrophotometric determination of epinephrine and norepinephrine with sodium periodate

A simple and accurate spectrophotometric method is described for the determination of epinephrine (EP), norepinephrine (NE) and their bitartrate salts. The method is based on the development of a red colour (lambda(max) 490 nm) with sodium periodate in aqueous alcoholic medium. The colour is stable for at least 1 hr. The molar reacting ratio of EP or NE to periodate is 1:2. The proposed method is particularly suitable for routine analysis of EP and NE injections. The interference due to the sodium metabisulphite normally used as antioxidant can be overcome by addition of acetone. Results for analysis of bulk drugs and injections agree well with those of official methods.     

Decision analysis in the energy sector

An optimization model has been developed primarily for the planning of the national energy system. It is also shown, however, that the model can be used as a tool for decision analysis.

The dynamic linear programming mini-model includes four primary energy sources and three forms of secondary energy. Decision variables include investment as well as production activities in the refining, conversion, and transmission of energy. The model contains 186 columns and 226 rows. The objective function is the discounted sum of costs of fuels, investments, operating costs, and under-utilized capacity. The model has been used to analyse decisions in the Turkish energy sector for the years 1960-1975, and possible developments for the period 1980-1995.

Through the use of this model, the underlying assumptions concerning the import prices of petroleum have been analysed, as well as the impact of a delay in the construction of a large hydro project. Furthermore, the effect of the shadow costs of foreign currency, the consequences of rapid industrialization, rapid economic growth, and substitution among fuels have been investigated. The model is currently being used for the analysis of possible nuclear strategies for Turkey.     

The transfer of momentum across surfaces drawn perpendicular to the direction of flow in gases under laminar conditions

Zusammenfassung Bei laminarer Strömung eines Gases ist die Übertragung der Bewegungsgrösse quer zu Flächen senkrecht zur Strömungsrichtung berechnet und gleich der transversalen Bewegungsgrösse quer zu Flächen, die parallel zur Strömungsrichtung laufen, gefunden worden. Daraus kann der Schluss gezogen werden, dass ein Flüssigkeitswürfel mit Seiten, die parallel zu den angegebenen Richtungen sind, statisch im Dreh-Gleichgewicht ist.