Kinetics of wetting of a compacted powder by aqueous solutions of surface active agents

Summary The capillary rise of aqueous solutions of anionic wetting agents into a compacted powder of an organic chromium complex is discussed on the basis of the Washburn-Rideal equation expanded to account for the porous structure parameters.At the porosity 1 —/6, corresponding to the loosest packing of monodisperse spheres the penetration rate is found to be mostly governed by the effective tensions operative at the moving three phase line of contact in case no deflocculation intervenes.

---

Zusammenfassung Der Kapillaraufstieg wässeriger Lösungen anionischer Netzmittel in gepreßtem Pulver eines organischen Chrom-Komplexes wird durch die erweiterte Gleichung vonWashburn-Rideal wiedergegeben, in der die Parameter der porösen Struktur mit einbezogen werden.Bei der Porosität 1 —/6, die der lockersten Anordnung gleichförmiger Kugeln entspricht, wird die Eindringgeschwindigkeit meistens durch die an der sich bewegenden Dreiphasengrenze wirkenden Grenzflächenspannungen bestimmt, wenn keine Peptisation eintritt.

---

---

Paper presented at the XII Intern. Congr. Fat Research, Milan, September 1974.     

Optical Gain in Laser Heterostructures with an Active Area Based on an InGaAs/InGaAlAs Superlattice

Optics and Spectroscopy - An active area based on InGaAs/InGaAlAs superlattice for laser diodes operating in the spectral range between 1535 and 1565 nm is proposed and realized practically. It is...     

Conditions of the Formation of a Shock Wave under Cavitation in Hydrocarbon Solutions

Doklady Physics - We carried out a numerical study of the appearance of a shock wave during the collapse of a bubble in a hydrocarbon aqueous solution. The conditions for the appearance of a shock...     

Kinetic analysis of MCF experiments in triple H/D/T mixtures

We report the results of an analysis of time and energy distributions of fusion products obtained in experiments on dtµ-fusion of HD molecules in triple H/D/T mixtures performed in Gatchina in 1985 and at PSI in 1989–92 with a high-pressure ionization chamber and neutron detectors. With different concentrations of tritium, 2.7 and 0.05%, it was possible to evaluate the rate of dtµ formation from the spin statesF=0 andF=1 of tµ atoms. The combined analysis of these experiments provided information about the contribution of epithermal dtµ formation to the initial part of the time spectra, which depends on the ratio of the exchange rates (_pt/_pd)^eff ·c _t/c _d=(_pt/_pd+b)·c _t/c _d, whereb is the fraction of the fast muon dt-exchange at high energy of dµ atoms     

Modeling of cavitation-bubble compression in benzene

In this study a two-dimensional model for calculating cavitation-bubble compression in benzene using a wide range of equations of state for ultrahigh pressures and temperatures is constructed. The calculations are carried out on the supercomputer of the Keldysh IAM. With the help of this model, the possibility of hits in the diamond-formation mode depending on the parameters of the external pressure and the initial bubble radius are analyzed. The dependence of the duration of the presence in the diamond-formation mode on these parameters is investigated.     

Degradation of Pt/C catalysts in start-stop cycling tests

The stability of highly disperse 50 wt % Pt catalysts deposited on carbon supports with various porosity and morphology is tested in accelerated oxidative experiments in the potential range of 1–1.5 V (RHE) in 0.1 M HClO₄ solution. The electrochemically active surface area of platinum (S _Pt) is determined based on the charge of adsorbed hydrogen by the cyclic voltammetry (CVA) method. The specific activity per mass unit (the mass catalytic activity (MCA)) and the electrochemically active surface area of the active component (surface catalytic activity (SCA)) are determined in the oxygen electroreduction reaction (OERR) by the method of rotating disk electrode (RDE). It is shown that the catalyst degradation is mainly due to the growth of Pt particles and the corrosion of the carbon support. It is found that under these cycling conditions, the rate of the S _Pt decline depends inversely on the cycle number throughout the cycling interval (up to 60000 cycles) for all catalysts, which points to the quadratic dependence of the degradation rate on S _Pt. Two regions are revealed in the MCA and SCA dependences on the cycle number, In the first region (from 0 to 8–10 thousand cycles), a sharp decrease in MCA and SCA is observed for all catalysts, which can be associated with the restructuring or passivation of the Pt particle surface due to the oxide formation on oxidative cycling. In the second region, the relative stabilization of MCA and the linear increase in SCA are observed for all catalysts without exception. The linear increase in SCA is due to the growth of Pt particles and the size effect. It is shown that carbonization of the carbon support leads to enhancement of its cycling stability.     

Calculation of the minimum scattering field of an arbitrary antenna by its directivity pattern

A rigorous statistically closed expression has been obtained to calculate the elements of the polarization scattering matrix S _p which describes the quadratically minimum scattering field of an arbitrary passive matched antenna. The elements S _p are analytically expressed only through the complex vector pattern of the antenna.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 8, pp. 1026–1035, August, 1996.     

New precision measurements of dµd fusion

A new experiment was started at PSI aiming for high-precision and complete studies of dµd fusion in D₂, HD and D₂/H₂ gas mixtures. A high-pressure ionization chamber surrounded by a set of neutron counters is used to observe dd-fusion at temperatures between 25 and 350 K. Here we report preliminary results from the first test run with pure D₂ filling.     

Predicting the solubility of xenon in n-hexane and n-perfluorohexane: a simulation and theoretical study

The solubility of xenon in n-hexane and n-perfluorohexane has been studied using both molecular simulation and a version of the SAFT approach (SAFT-VR). The calculations were performed close to the saturation line of each solvent, between 200 K and 450 K, which exceeds the smaller temperature range where experimental data are available in the literature. Molecular dynamics simulations, associated with Widom's test particle insertion method, were used to calculate the residual chemical potential of xenon in n-hexane and n-perfluorohexane and the corresponding Henry's law coefficients. The simulation results overestimate the solubility of xenon in both solvents when simple geometric combining rules are used, but are in good agreement if a binary interaction parameter is included. With the SAFT-VR approach we are able to reproduce the experimental solubility for xenon in n-hexane, using simple Lorentz-Berthelot rules to describe the unlike interaction. In the case of n-perfluorohexane as a solvent, a binary interaction parameter was introduced, taken from previous work on (xe + C₂F₆) mixtures. Overall, good agreement is obtained between the simulation, theoretical and experimental data.     

Analysis of the Internal Optical Losses of the Vertical-Cavity Surface-Emitting Laser of the Spectral Range of 1.55 µm Formed by a Plate Sintering Technique

Optics and Spectroscopy - The results of a study of internal optical losses and current injection efficiency in vertical-emitting lasers of a spectral range of 1.55 µm obtained by sintering...