Adsorption on stepped substrates

An analysis is given of the behavior of an interface above a stepped substrate in the presence of an external pinning potential for the lattice solid-on-solid (SOS) interface model in 2D. Step-free energy including step-step interaction free energy is calculated, for large step separation. It is found it vanishes at temperatures lower thanT _w (wetting transition temperature), which is different from the case having only one step on a substrate where, as it is well known, step-free energy vanishes at the wetting transition.     

Determination of phosphorous in organic compounds and metal complexes by inductively-coupled plasma atomic emission spectrometry

Phosphorus is determined by inductively-coupled plasma atomic emission spectrometry at 213.618 nm. Different types of organic and inorganic phosphorus compounds and metal complexes were examined after direct dissolution in water, aqueous ethanol or acid, or after decomposition by oxygen flask combustion or Kjeldahl digestion; results were within the usual limit of precision and accuracy for such determinations. The effect of small (<20%) ethanol concentrations in the aqueous solution on the signals obtained from a low-power (1200 W) argon plasma is examined and discussed.     

Femtosecond laser pulse train effect on Doppler profile of cesium resonance lines

We present direct observation of the velocity-selective optical pumping of the Cs ground state hyperfine levels induced by the femtosecond (fs) laser oscillator centered at either D2 (6 ²S_1/2↦6 ²P_3/2, 852 nm) or D1 (6 P_1/2, 894 nm) cesium line. We utilized previously developed modified direct frequency comb spectroscopy (DFCS) which uses a fixed frequency comb for the excitation and a weak cw scanning probe laser centered at the ¹³³Cs 6 ²S_1/2↦6 ²P_3/2 transition (D2 line) for ground levels population monitoring. The frequency comb excitation changes the usual Doppler absorption profile into a specific periodic, comblike structure. The mechanism of the velocity selective population transfer between the Cs ground state hyperfine levels induced by fs pulse train excitation is verified in a theoretical treatment of the multilevel atomic system subjected to a pulse train resonant field interaction.     

Spectrophotometric Investigation of the Celiprolol-Hydrochloride Ion-Pair

Celiprolol-hydrochloride has been determined using benzylorange and forming ion-pair. The absorbance of yellow coloured ion-pair is measured at 401 nm. Unknown concentrations of celiprolol-hydrochloride is calculated by using the calibration graph of the following calibration equation:

y = 0.1602 × + 0.0214

The conditional stability constant of the ion-pair at the optimum pH 6.2 and ionic strength 0.05 is found to be 5.63. The method is successfully applied to the determination of celiprolol-hydrochloride in pharmaceutical preparations.     

Distant measurement

Distant correlations are investigated within the framework of quantum mechanics. They are inherent to any physical situation in which two separated quantal systems are described by one composite state vector. Owing to correlations of this kind one can perform a measurement on one of the systems, thereby measuring a certain observable on the other (distant) system without interacting with it. Necessary and sufficient conditions are given for such a distant measurement to take place. It is found which are the observables that can be measured distantly, and which are the states of the distant system obtainable in this way. Solution of these problems is achieved by replacing the composite state vector by two entities equivalent to it: the reduced statistical operator of the system which is directly measured and a correlation operator. The latter gives a connection between states, observables, and probabilities of the two systems. Experimental evidence for distant measurement is discussed.     

The dynamics of the two-level system in glasses

The self-consistent system of equations for longitudinal and transversal dynamical susceptabilities of the two-level system (TLS) in metallic glasses is obtained by using the method of irreducible relaxation functions. The dynamics of TLS interacting with acoustic phonons and electrons is discussed in the weak coupling limit and in the slow-fluctuation regime.     

Controlled self-assembly of chiral gelator molecules into aligned fibers induced by nematic to smectic B phase transitions

Chiral bisoxalamide 1 shows remarkable gelling capacity of the nematic and smectic B liquid-crystalline phases of heptylcyclohexanecarboxylic acid (HCCA). Chiral nematic-containing left-handed helical fiber bundles are formed if the gelator is present in amounts higher than 0.55 wt %. With lower amounts of 1, no nematic gel forms, however, a nematic to smectic B phase transition triggers instantaneous self-assembly of gelator molecules into aligned fibers. The latter liquid crystalline gel system represents an example of controlled self-assembly induced by a liquid crystalline phase transition.     

Simultaneous Determination of Hydrochlorothiazide, Cilazapril and Its Active Metabolite Cilazaprilat in Urine by Gradient RP-LC

A rapid and simple liquid chromatographic method with UV detection has been developed for the determination of hydrochlorothiazide (HCTZ), cilazapril (CL) and its active metabolite cilazaprilat (CLT) in urine. Sample preparation for urine consisted of solid-phase extraction using styrene-divinylbenzene (SDB-2) cartridges. The chromatographic system was a Zorbax Eclipse XDB-C₁₈ column with a mixture of methanol and 10 mM phosphate buffer, pH 2.3 with gradient (20 to 60% of methanol) as mobile phase at a flow rate of 1.0 mL min^?1. The detection was performed at the wavelength of 206 nm. Enalapril maleat was used as an internal standard. The detector response was linear in the range of 2.4–30.0, 1.6–15.0 and 1.8–20.0 μg mL^?1 for HCTZ, CL and CLT, respectively. LOQ was determined to be 2.4, 1.6 and 1.8 μg mL^?1 for HCTZ, CL and CLT, respectively. Both intra- and inter-day precision were within acceptable limits. The method has been applied to urine samples obtained from three hypertensive patients after intake of HCTZ and CL therapeutic dose.     

Low-density plasma channels generated by femtosecond pulses

We present an investigation of the plasma channel formed along the trail of an intense femtosecond (fs) laser pulse propagating through helium, air and nitrogen at low pressures. The lifetime of the generated plasma channel of up to 60 μs was measured. We determined the electron-attachment mechanism as a dominant mechanism for the plasma relaxation. The initial electron densities, electron-attachment coefficients and plasma channel conductivity for different experimental conditions were obtained. PACS 52.50.Jm; 52.25.-b; 51.50.+v