Melting of large Pt@MgO(1 0 0) icosahedra.

On the basis of ab initio calculations, we present a new parametrisation of the Vervisch-Mottet-Goniakowski (VMG) potential (Vervisch et al 2002 Phys. Rev. B 24 245411) for modelling the oxide-metal interaction. Applying this model to mimic the finite temperature behaviour of large platinum icosahedra deposited on the pristine MgO(1 0 0), we find the nanoparticle undergoes two solid-solid transitions. At 650 K the 'squarisation' of the interface layer, while a full reshaping towards a fcc architecture takes place above 950 K. In between, a quite long-lived intermediate state with a (1 0 0) interface but with an icosahedral cap is observed. Our approach reproduces experimental observations, including wetting behaviour and the lack of surface diffusion.

Surface segregation of Au-Pd alloys in UHV and reactive environments: quantification by a catalytic atom probe.

The surface composition of an Au-62at%Pd alloy has been studied by means of a catalytic atom probe (CAP) before and after exposures to nitric oxide (NO) at temperatures ranging from 300 to 573K for 20min. Subsequent CAP analysis at 100K revealed a considerable surface enrichment in Pd (to approximately 80at%) after exposure at 573K. This is correlated with the occurrence of NO dissociation, and the formation of strong Pd-O bonds at the surface. Blank experiments in ultra-high vacuum reflect the surface composition of the bulk material, in excellent agreement with electron microprobe analysis. At 573K, no detectable surface segregation occurs in the absence of NO adsorption for the times and temperatures studied. However, classical Metropolis Monte-Carlo simulations performed with a semi-empirical potential on the Au(40)Pd(60) (111), (110) and (100) systems show surface enrichment of gold at equilibrium. This suggests that the temperatures of the clean surface segregation experiments are too low to reach equilibrium within times of the order of hours.

[Changes in the ACTH and cortisol values of patients with acute myocardial infarct]. / Promeni v stoinostite na AKTKh i kortizol pri bolni s ostur infarkt na miokarda.

The plasma cortisol and adrenocorticotrophic hormone (ACTH) levels were studied in 12 patients with clinical, laboratory and ECG data for acute myocardial infarction. The changes were followed up during the 1, 3, 8 and 14 day after the onset of the chest pain attack. Increased ACTH and cortisol levels were established in these patients up to the 5 day. The regulatory principle of action of the opposite relation between these two hormones as well as their 24 hour rhythm were disturbed. These stress-induced hormonal changes should be kept in mind in determining the therapeutic conduct in the patients with acute myocardial infarction.

[Continuous thoracic epidural analgesia in surgical interventions on the upper half of the abdomen--the noninvasive monitoring of the early hemodynamic changes]. / Produlzhitelna torakalna epiduralna analgeziia pri operativni namesi v gornata polovina na korema--neinvazivno monitorirane na rannite khemodinamichni promeni.

Operative interventions in the upper half of the abdomen have been performed in 32 surgical patients under thoracic epidural analgesia (TEA) with bupivacain at T4-L2 level, with the use of catheter technique. Before operation the patients were hydrated with 12.5 per cent of the circulating blood volume, calculated by nomogram. By noninvasive approach were monitored: pulse rate (PR), mean arterial pressure (MAP), minute cardiac volume (MCV), peripheral vascular resistance (PVR) and cardiac index (CI) for the following times; T0--basal preoperative value, T1--on the 5. min; T2--on the 10. min; T3--on the 15. min.; T4--on the 20 min.; T5--on the 50. min after application of bupivacain analgesia. The results were compared by variation analysis to T0. PVR was reduced with statistical significance for T2, T3 and T4 (p less than 0.01). MCV, CI and MAP tended to be reduced, while PR showed no significant changes. The results may be summarized, as follows: 1. Noninvasive monitoring of PR, MAP, MCV, CI and PVR in TEA is necessary for early detection and control of their pathologic changes; 2. The hemodynamic changes in TEA with bupivacain at T4-L2 level after premedication with vagolytic and hydration with Ringer-lactate (in amount 12.5 per cent of the circulating blood volume) are not significant and do not require additional treatment; 3, TEA at T4--L2 level allows performance of operative interventions in the upper half of the abdomen with adequate analgesia and relaxation, being particularly indicated for patients at risk.

[Changes in uricemia in acute myocardial infarct]. / Promeni v urikemiiata pri ostur miokarden infarkt.

The authors studied in dynamics the concentration of uric acid in 84 patients in the acute stage of myocardial, in 28 patients with non-stable stenocardia. The average value of uricemia, in the first 1--2 days post infarction is 6.35 +/- 2.23 mg%, considerably higher than that in case of non-stable stenocardia--4.75 +/- 1.25 mg%. In all the patients with myocardial infarction, 34.04 per cent have uricemia over 6 mg% (upper limit of the norm). The hypouricemia was normalized by the 14--15 day after the onset of infarction--4.25 mg%. The highest values of uric acid (up to 13 mg%) were found in case of severely progressing infarctions. A parallelism was established between serum concentration of uric acid and the creatinine-phosphokinase level. The possible pathogenic mechanisms of hyperuricemia in the acute stage of myocardial infarction are discussed.