Surface-induced liquid-gas transition in salt-free solutions of model charged colloids.

We report a novel phenomenon of a surface-induced phase transition in salt-free solutions of charged colloids. We develop a theory of this effect and confirm it by Molecular Dynamics simulations. To describe the colloidal solution we apply a primitive model of electrolyte with a strong asymmetry of charge and size of the constituent particles - macroions and counterions. To quantify interactions of the colloidal particles with the neutral substrate we use a short-range potential which models dispersion van der Waals forces. These forces cause the attraction of colloids to the surface. We show that for high temperatures and weak attraction, only gradual increase of the macroion concentration in the near-surface layer is observed with increase of interaction strength. If however temperature drops below some threshold value, a new dense (liquid) phase is formed in the near-surface layer. It can be interpreted as a surface-induced first-order phase transition with a critical point. Using an appropriately adopted Maxwell construction, we find the binodal. Interestingly, the observed near-surface phase transition can occur at the absence of the bulk phase transition and may be seemingly classified as prewetting transition. The reported effect could be important for various technological applications where formation of colloidal particle layers with the desired properties is needed.

Electrode screening by ionic liquids.

In this work we are concerned with the short-range screening provided by the ionic liquid dimethylimidazolium chloride near a charged wall. We study the free energy profiles (or potentials of mean force) for charged and neutral solutes as a function of distance from a charged wall. Four different wall charge densities are used in addition to a wall with zero charge. The highest magnitude of the charge densities is ±1 e nm(-2) which is close to the maximum limit of charge densities accessible in experiments, while the intermediate charges ±0.5 e nm(-2) are in the range of densities typically used in most of the experimental studies. Positively and negatively charged solutes of approximately the size of a BF ion and a Cl(-) ion are used as probes. We find that the ionic liquid provides excellent electrostatic screening at a distance of 1-2 nm. The free energy profiles show minima which are due to layering in the ionic liquid near the electrodes. This indicates that the solute ions tend to displace ionic liquid ions in the layers when approaching the electrode. The important role of non-electrostatic forces is demonstrated by the oscillations in the free energy profiles of uncharged solutes as a function of distance from the wall.

Comparative analysis of electrophysiologic effect of metoprolol and disopyramide, acting alone or in combination in patients with supraventricular tachycardia and Wolff-Parkinson-White syndrome.

In the aim of determining an electrophysiologic effect of disopyramide and metoprolol at alone therapy and in combination in patients with supraventricular tachycardia on the background of Wolff-Parkinson-White syndrome 23 persons were examined. All patients were subjected to an intracardiac electrophysiological testing; in its process metoprolol in the dosage of 0.2 mg/kg of body weight, disopyramide in the dosage of 2 mg/kg per body weight both separately and in combination were controlled. It was identified that metoprolol and disopyramide are an effective antiarrhythmic preparates applied for arresting and prevention of reciprocating orthodromic tachycardias in patients with Wolff-Parkinson-White syndrome.

Comparative analysis of anti-arrhythmic effect of propranolol and metoprolol in patients with supraventricular tachyarrhythmias.

Eighty-seven patients with paroxysmal tachydysrhythmias were submitted to clinical and laboratory evaluation and electrophysiologic studies were performed during the 3rd, 6th and 12th months of the therapy with propranolol or metoprolol. Metoprolol did not induce any significant change in sinoatrial correct time, in sinoatrial recovery time or in corrected sinoatrial recovery time. It decreases significantly the effective and functional AV refractory periods as well as increases the effective refractory period of the additional pathway. The mechanism of tachycardia preventing an involvement of the additional pathway in retrograde direction consists in the appearance of a block in the indicated additional pathway. The results of the humoral aspects are the following: propranolol inhibits the functions of the thyroid and sexual glands both in acute tests and in tests performed during the 3rd, 6th and 12th month of therapy; metoprolol has no significant effect on the functions of the thyroid and sexual glands; apparently, it influences the cardiac conduction system and myocardium directly.

[Ventricular tachycardia: the role of adrenergic stimulation in the prognosis of fatal arrhythmia]. / Zheludochkovye takhikardii: rol' adrenergicheskoi stimuliatsii v prognozirovanii fatal'nykh aritmii.

A new method for appraising the individual efficacy of an antiarrhythmic agent is described. It is based on paired administration of isoprenaline and testing antiarrhythmics for maximum activity. The possibility of provoking ventricular tachycardia by isoprenaline made it possible to identify a contingent of patients with "catecholamine-sensitive" or "variable" tachycardia. The prognosis of "catecholamine-sensitive" ventricular tachycardia proved to be the worst in groups of patients with ischemic heart disease attended by postinfarction cardiosclerosis and in patients with arrhythmogenic dysplasia of the right ventricle.

[The use of obzidan and metoprolol in patients with supraventricular systolic tachyarrhythmias]. / Primenenie obzidana i metoprolola u bol'nykh s supraventrikuliarnymi takhisistolicheskimi aritmiiami.

Having analyzed the electrophysiological mechanisms and state of humoral regulatory substances in 87 patients with paroxysmal disorders of the cardiac rhythm the authors determined the antiarrhythmic action of two beta-blockaders: obsidan and metoprolol. They found a reduction of the sinus node function under the effect of obsidan and to a lesser degree under the effect of metoprolol. Metoprolol produced a high antiarrhythmic effect, particularly in supraventricular tachycardias with participation of abnormal conduction pathways.

[Electric stimulation of the heart in ventricular tachycardia: achievements and prospects]. / Elektricheskaia stimuliatsiia serdtsa pri zheludochkovoi takhikardii: dostizheniia i perspektivy.

Cardiac electrostimulation was conducted in 19 patients to prevent and control paroxysmal ventricular tachycardia. In 8 of those, an attempt was made to prevent tachycardia by continuous endocardial ventricular stimulation in the demand regimen. In 11 patients, a radio-frequency stimulator was implanted, its electrode positioned in the right ventricle to control current tachycardiac attacks. A 3-5-second stimulation at frequencies of 180-220 impulses per minute was sufficient to control the attack in 8 of the patients, while programmed ventricular stimulation only was needed to produce the effect in 3 patients.

[Diagnostic significance of frequent atrial stimulation against a background of drug denervation in the sick sinus syndrome]. / Diagnosticheskoe znachenie chastoi stimuliatsii predserdii na fone medikamentoznoi denervatsii pri sindrome slabosti sinusovogo uzla.

The aim of the present paper is to verify the diagnostic potentialities of frequent atrial stimulations during functional autonomous block. 31 patients (15 males and 16 females) aged 36-65 years were examined. The diagnosis of sick sinus syndrome (SSS) was made according to history data, clinical manifestations of the disease, and ECG data of SSS. All the patients underwent the electrophysiologic study (EPS) in which sinus nodal recovery time and corrected sinus nodal recovery time were determined before and after the functional autonomous block. All the patients were divided into 6 groups according to the findings. This trial was found to increase the diagnostic potential of EPS in the diagnosis of SSS.