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In this study, we design and test a current controller for a source of thermionic electron emission operating in an ionization vacuum gauge. We use a precise and controlled source of current to transfer the emission current from the anode, which has a high potential in the circuit, to the cathode with a low potential. This eliminates the need for galvanic isolation or sources of floating voltage, which introduce noise to the system, for supplying the cathode and the anode. We show that this has a limited effect in terms of changes in the residual gas pressure on the emission current in the range from 10−4 to 10−2 Pa. The temporal stability of the emission current was determined for reference values ranging from 1 to 4 mA for both 10-min and 2-h periods, and it was found to be lower than 6 ppm. The proposed controller can be used in apparatus to measure electron impact-induced gas ionization. [ABSTRACT FROM AUTHOR]

This article presents selected methods of converting solar energy into electricity: photovoltaic cells (PV), converters which use photon-enhanced thermionic emission (PETE), and near-field enhanced thermionic energy conversion systems (NETEC). PETE and NETEC systems are innovative solutions that use the thermionic emission phenomenon and can replace photovoltaic generation of electricity. We did a comparative analysis of such issues as: structure, principle of operation, working temperature and with particular emphasis - efficiency. A comparison of these parameters is shown in the graphs and summarized in the table. Based on the analysis, we have drawn conclusions about previous achievements and development perspectives in the field of converting methods.

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Aim: To assess correlation between exercise tolerance and Doppler-derived indices of right ventricular (RV)--pulmonary arterial coupling in patients with different location of vascular lesions causing pulmonary hypertension (PH)., Material: 45 patients: 21 with thromboembolic (TE-PH) and 24 with arterial PH defined as systolic pulmonary arterial pressure (SPAP) > 40 mm Hg. The two groups were similar as far as SPAP (74,8 +/- 15,2 vs 76.5 +/- 14,1 mm Hg, p = ns) and distance covered during 6 minute walk test (339 +/- 116 vs 320 +/- 127, p = ns) are concerned., Results: Flow velocity curve in the RV outflow tract were different in the two groups. Time from onset to peak velocity of ejection (acceleration time, AcT) as well as to midsystolic deceleration were shorter in TE-PH then in arterial PH (59.0 +/- 6.3 vs 68.1 +/- 15.4 msec, p = 0.015 and 123.8 +/- 17.9 vs 137.9 +/- 29.7 msec, p = 0.071, respectively). In the whole studied group as well as in arterial PH significant correlation between exercise tolerance and Doppler-derived indices of RV--pulmonary arterial coupling were found (r = 0.51, p < 0.001 and r = 0.72, p = < 0.001, respectively). Interestingly, no such relationship was found in TE-PH, (r = 0.16, p = ns)., Conclusion: In contrast to arterial PH, pressure wave prematurely reflected from the intraluminal thrombi seem to disturb the RV ejection pattern and its correlation with exercise tolerance in TE-PH. Whether progression or effects of treatment on arterial PH can be assessed by monitoring changes in Doppler-derived indices of RV--pulmonary arterial coupling requires further studies.

Beraprost sodium (BPS)--an orally active prostacyclin analogue--improves haemodynamic parameters and quality of life in group of patients with pulmonary arterial hypertension. Effect of long-term therapy with BPS is not well defined. This study assesses influence of long-term therapy with BPS on the survival of patients with precapillary pulmonary hypertension. Studied group consisted of 25 patients with precapillary PH (18 F, 7M, aged 34 +/- 13,9 years). Sixteen patients were diagnosed with primary PH, 3 pts had PH associated with connective tissue disease, 5 pts developed PH in course of congenital systemic to pulmonary shunt, and 1 patient suffered from inoperable chronic thromboembolic PH. At time of diagnosis 15 pts presented exercise impairment of WHO class II and 10 pts were in functional class III. All studied subjects had complete hemodynamic assessment of right heart and obtained values were used for estimation of hypothetic survival using prognostic equation proposed by D'Alonzo et al. On follow-up period patients received BPS in the highest tolerated dose (80-480 mg daily). During a follow-up period (mean: 22 months) 7 patients died. Cumulative survival rate BPS group was significantly higher in BPS group comparing to hypothetical survival at 6 months (96% (95% CI: 88-104%) vs 73% (95% CI: 67-78%), p = 0.02) and 12 months (94% (95% CI: 84-104%) vs 65% (58-71%), p = 0.01), respectively. At 18 and 24 months differences between BPS virtual and hypothetical survival were not statistically significant. There was no correlation between survival and maximal achieved dose of BPS. These results suggest, that BPS improves prognosis of patients with precapillary PH during 12 months after initiation of therapy. Later effect of BPS seems to decrease, requiring changing or intensification of therapy.

Atrial septostomy (AS) emerges as a potential therapeutic option in severe primary pulmonary hypertension (PH). AS isa transluminal intervention consisting of perforation of interatrial septum and balloon dilatation. During the procedure an atrial septal defect is created to a diameter permitting right-to-left shunt with the aim of correcting abnormal preload of both ventricles, leading to hemodynamic and functional consequences. We present two patients characterised by severe right ventricular failure. The second patient with rapid clinical deterioration required ,,rescue" rather than elective AS. Despite similar, small sizes of balloons (8 and 6 mm, respectively) used during both procedures, elective AS resulted in a significant and persistent hemodynamic (CI increased from 2.0 to 2.3 1/min/m(2)) and functional improvement while ,,rescue" AS despite short term improvement resulted in an uncontrolled systemic hypoxemia and did not prevent death 28 days after the procedure. Although AS is an invasive and palliative method, it offers persistent functional improvement in patients with primary PH. In view of poor prognosis and limited therapeutic options in Poland, elective AS should be considered as a potentially valuable intervention in patients with primary PH in our country.