The Band-Gap Studies of Short-Period CdO/MgO Superlattices.

Trends in the behavior of band gaps in short-period superlattices (SLs) composed of CdO and MgO layers were analyzed experimentally and theoretically for several thicknesses of CdO sublayers. The optical properties of the SLs were investigated by means of transmittance measurements at room temperature in the wavelength range 200-700 nm. The direct band gap of {CdO/MgO} SLs were tuned from 2.6 to 6 eV by varying the thickness of CdO from 1 to 12 monolayers while maintaining the same MgO layer thickness of 4 monolayers. Obtained values of direct and indirect band gaps are higher than those theoretically calculated by an ab initio method, but follow the same trend. X-ray measurements confirmed the presence of a rock salt structure in the SLs. Two oriented structures (111 and 100) grown on c- and r-oriented sapphire substrates were obtained. The measured lattice parameters increase with CdO layer thickness, and the experimental data are in agreement with the calculated results. This new kind of SL structure may be suitable for use in visible, UV and deep UV optoelectronics, especially because the energy gap can be precisely controlled over a wide range by modulating the sublayer thickness in the superlattices.

Electronic structure of ytterbium-implanted GaN at ambient and high pressure: experimental and crystal field studies.

The results of high-pressure low-temperature optical measurements in a diamond-anvil cell of bulk gallium nitride crystals implanted with ytterbium are reported in combination with crystal field calculations of the Yb(3+) energy levels. Crystal field analysis of splitting of the (2)F(7/2) and (2)F(5/2) states has been performed, with the aim of assigning all features of the experimental luminescence spectra. A thorough analysis of the pressure behavior of the Yb(3+) luminescence lines in GaN allowed the determination of the ambient-pressure positions and pressure dependence of the Yb(3+) energy levels in the trigonal crystal field as well as the pressure-induced changes of the spin-orbit coupling coefficient.

Crystal size and crystalline volume fraction effects on the Erbium emission of nc-Si:Er grown by r.f. sputtering.

Erbium-doped low-dimensional Si films with different microstructures were grown by reactive magnetron sputtering on glass substrates by varying the deposition parameters. Their structure and chemical composition were studied by micro-Raman and Rutherford backscattering spectrometry, respectively. In this contribution the Erbium emission is studied as a function of nanocrystalline fraction and average crystal sizes and also as a function of the matrix chemical composition. We discuss the temperature dependence of the Er3+ emission as well as the possible explanations of the low Er active fraction.

[Usefulness of electrocardiographic exercise tests for evaluation of percutaneous transluminal coronary angioplasty results]. / Przydatnosc elektrokardiograficznych testów wysilkowych dla oceny wyników przezskórnej angioplastyki tetnic wiencowych.

The value of exercise ECG (ExT) in predicting the occurrence of restenosis after successful single-vessel percutaneous transluminal coronary angioplasty (PTCA) was assessed in 94 patients (pts). There were 83 pts with complete and 11 with incomplete revascularisation. In all cases ExT were made prior to the procedure, immediately after, 3 and 6 months after PTCA. In group of 48 pts without restenosis an abnormal ExT was present in 19 (39.6%) pts immediately after PTCA and in 13 (27.1%) pts in 6 month of observation. Among 46 pts with restenosis an abnormal ExT was observed in 27 (58.7%) pts immediately after PTCA and in 42 (91.3%) pts in time of 6 months control. Four (8.7%) pts showed negative ExT despite of restenosis. After 3 months of observation multivariate analysis of 11 factors revealed 2 factors related to restenosis: ST segment depression and chest pain during ExT. The positive predictive value for restenosis was 60.5% for those factors. After 6 months of observation multivariate analysis revealed 3 factors related to restenosis: ST segment depression, double product and maximal blood pressure during ExT. The positive predictive value for restenosis was 64.7% for those factors. It is concluded that our diagnostic strategy provides a useful clinical tool for detecting patients with high risk of restenosis who may require repeated coronary angiography.

[Coronary bypass grafting after failed percutaneous angioplasty (PTCA)]. / Pilne pomostowanie tetnic wiencowych po powiklanych angioplastykach wiencowych (PTCA).

Between January 1991 and September 1997, in the Cardiovascular Surgery Department of the Institute of Cardiology of Jagiellonian University Medical School, 23 patients underwent emergency CABG due to acute myocardial ischaemia in result of failed PTCA. Over the same period of time invasive cardiologists performed 1883 PTCAs out of which 23 (1.2%) were emergency cardiosurgical procedures, and in 38 patients, stents were implanted in the damaged coronary arteries. The patients' age ranged from 37 to 67 years (median 52.2). In all patients good left ventricular function was preserved, median ejection fraction being 64%. Two patients required IABP to support left ventricular function. 1-4 bypass grafts were implanted (median 1.9 per patient). In one patient, internal mammary artery was collected and then implanted into anterior interventricular branch. The most common complication was myocardial infarction which occurred in 12 patients (52%). In ten patients low output was observed postoperatively. One operated patient (a female died (4.3%). The mean time of hospitalization was 11 days. Emergency myocardial revascularisation procedures performed after failed PTCA, bring higher risk of mortality and dangerous postoperative complications.

[Scintigraphic evaluation of myocardial perfusion after using TI-201 in patients before and after successful percutaneous transluminal coronary angioplasty]. / Scyntygraficzna ocena perfuzji miesnia sercowego przy uzyciu talu 210 u chorych przed i po skutecznej angioplastyce naczyn wiencowych.

We analysed 53 patients (43 men and 19 women) age 38-71. Exercise TI-201 scintigraphy was performed before PTCA, 6 to 10 days and 3 to 6 months after PTCA. Before PTCA in all the patients myocardial perfusion detects on scintigraphy were observed. The imaging performed 6 to 10 days after PTCA showed an improvement seen as a decrease in the number of ischaemic segment in 36 patients (67.9%) and total normalisation of scintigraphic picture in 12 patients. Coronary angiography performed 6 months after PTCA showed patency of the dilated vessel in 11 (91.3%) among these patients. In exercise TI-201 scintigraphy performed 3 to 6 months after PTCA normalised scan was observed in 20 patients, recurrence of stenosis was found only in 2 (10%) of those patients. In 33 patients with transient perfusion defects, angiographic restenosis was found in 22 (60%) patients. Predictive value of exercise TI-201 scintigraphy for occurrence of restenosis was established. Positive predictive value of the study performed 6 to 10 days after PTCA was 56%. Negative predictive values of such a study was 91%. Similarly, for detection of restenosis in scan performed 3 to 6 months after PTCA there was found a strong negative predictive value-90% and a weak positive predictive value-63%.

Microfocal myocardial lesions in cardiac allograft recipients.

Endomyocardial biopsy has been widely accepted as a method for diagnosing acute heart transplant rejection. However, disperse and microfocal changes due to a smaller specificity, cause difficulty in histological differential diagnosis. The purpose of the present study was to morphologically assess microfocal lesions, to determine their relative incidence and their specificity in relation to the time of onset after cardiac transplantation and to compare these data with those concerning more extensive changes. We examined 658 samples in 152 endomyocardial biopsies obtained from 45 posttransplant patients, including 311 samples identified as containing focal lesions of varying size, and 33 as containing diffuse lesions. Samples with focal and diffuse lesions (344 samples) were submitted for further studies which revealed that microfocal changes in the transplanted heart show more enhanced polymorphism in the composition of cellular infiltrates than more extensive changes. Furthermore they are frequently seen in biopsies in the first two months after transplantation and as single changes. Necrosis and cellular infiltrates at that time are more diversified than those seen in later biopsies. In our experience differential diagnosis of microfocal myocardial lesions in cardiac allograft recipients is difficult. Potentially microfocal lesions may be a result not only of acute rejection but also a result of myocardial alterations in the course of intensive therapy both in the donor and in the recipient, cold ischemia, reperfusion, and inflammation. The morphological picture in some cases is not sufficient to make an unequivocal diagnosis. This indicates the need for improvement of diagnostic methods and criteria on the one hand, and a suitable approach to the problem on the other hand. Our experience shows that a temporary solution could be establishing of a separate classification category for these types of changes and defining them as nonspecific microfocal lesions.

[Morphology of atheromatous change during and after PTCA and occurrence of restenosis]. / Morfologia zmiany miazdzycowej przed i po PTCA a wystapienie restenozy.

The frequency of restenosis incidence in a group of 72 patients after effective PTCA as well as dependence of its incidence on dilated coronary artery and morphology of sclerotic changes according to ACC/AHA classification were analyzed. The subject of analysis included also effect of the degree of residual stenosis on restenosis incidence as well as determining dependence between the degree of dissection after PTCA on restenosis rate. Restenosis was stated in 20 (20.7% percent) patients, in 26 cases (29%) among 88 dilated coronary arteries. Restenosis was more frequently observed in cases of left coronary artery dilatation. Analyzing restenosis occurrence in relation to morphology of sclerotic changes according to ACC/AHA classification its more frequent incidence in type B (35%) and type C (44%) in comparison type A--25% of this classification was observed. The percentage of residual stenosis was higher in the group of restenosis and amounted to 22.8% in comparison to the residual stenosis of 13% in the group of patients with no reported restenosis. Localized dissection can be a good predictor of results after successful PTCA. More frequent incidence of limited dissection took place in 34% of dilated coronary arteries without restenosis in relation to 20% of cases with restenosis. No evidence of dissection as well as long dissection after PTCA was associated with higher degree of restenosis. Angiographic evaluation of the morphology of sclerotic changes in view of degree of dissection after PTCA is a good predictor of results after angioplasty.

[Results and complications of PTCA]. / Wyniki i powiklania angioplastyki wiencowej.

Between January 1987 and June 1992 we performed 189 PTCA procedures in a group of 153 patients (127 men, 26 women) aged 28 to 69 years, mean 52.3. 203 coronary vessels were dilated. In 136 pts one vessel was dilated, one vessel with two narrowings were dilated in 16 pts and in 17 pts two-vessel PTCA was performed. Due to restenosis, PTCA was repeated, once in 26 pts, twice in 3 pts and three times in 1 patient. Effective dilatation was achieved in 81.8% of cases and in this number, circumflex and marginal branch of left coronary artery were successfully dilated in 90.7%, left anterior descending in 84.6%, right coronary artery in 84.2% of cases. Attempts to recanalize these vessels were effective in 52%. There were no lethal complications of PTCA, acute occlusion of artery occurred in 5.9% of dilated vessels. Emergency coronary bypass had to be performed in 5.2% pts due to acute artery occlusion. PTCA supported by surgical stand-by appears to be a safe procedure with high direct effectiveness.

[Degradation and consumption of one's own glycogen in placental tissue in pregnancy complicated by gestosis and anemia]. / Rozklad i zuzycie glikogenu wlasnego przez tkanke lozyska z ciazy powiklanej gestoza i niedokrwistoscia.

We estimated in vitro degradation and consumption of glycogen by placental tissue derived from pregnancies complicated by gestosis and anemia. Placental tissue was incubated in suitable medium. Glycogen concentration either before or after incubation was assayed. Glycogen consumption was expressed as micromoles of glucose per 1 g of wet tissue, the percentage of glycogen consumption has been shown in tables. It is concluded that in advanced gestosis and severe anemia of pregnancy the consumption of native glycogen is increased, consequently it may lead to metabolic insufficiency of human placenta.

[Effect of diseases in pregnancy on certain placental functions. Enzymatic systems degrading placental glycogen in pregnancy with gestosis]. / Ocena wplywu chorób ciezarnej na wybrane funkcje lozyska. Uklady enzymatyczne rozkladajace glikogen w lozysku od Ciezarnej z gestoza.

Pathways of human placental glycogen degradation either in normal or gestotic pregnancy were examined. Determinations of glycogen phosphorylase served as an index of glycogen cleavage in the phosphorylitic pathway. The activity of hydrolytic route was measured by estimating placental glucoamylase. Samples of placental tissue were obtained after delivery (between the 36th and the 40th week of pregnancy). In placentas derived from gestotic cases elevated activity of phosphorylase A, the decrease in phosphorylase B activity and the rise in glucoamylase were found. It suggests that gestosis may evoke certain impairment of placental glycogen metabolism deteriorating chiefly the glycogen degradation as it may be observed in hypoxic experiments.