Effects of 17 beta-estradiol on nitric oxide and ventricular myocardium metabolism

BACKGROUND: Arrhythmias are frequent pathology in patients with chronic hemodialysis. We evaluated whether a relatively new technique, signal averaging, could be useful in predicting the development of complex arrhythmias in these patients. METHODS: Thirty-three patients, 18 male and 15 female, subjected to thrice weekly chronic hemodialytic treatment with various dialysis techniques, were studied. Exclusion criteria were the presence of antiarrhythmic and inotropic treatment. The following examinations were carried out in all patients: a Holter dynamic electrocardiography for a duration of 24 hours, begun on the day of dialysis, high resolution ECG pre- and post-dialysis to find out if there were any ventricular late potential (VLP). Four hundred beats were examined in order to obtain a background noise of less than 0.7 microV and a better definition of the signal. The following parameters were considered significant for the presence of VLP: a) filtered QRS duration > 120 msec; b) the root mean square of the signal expressed in the terminal portion of QRS (RMS) < 25 microV) high frequency low amplitude signals duration (HFLA) > 40 msec. A positive value in two of these parameters was considered indicative of the presence of VLP. In addition various pre and post-dialysis indices of dialytic efficiency and a mono and two-dimensional echocardiogram with pulsed and color Doppler were carried out. Of the 33 patients studied, ten were excluded because they presented too high a background noise at the high resolution ECG. Of the remaining 23 patients, 13 (56%) presented VLP and nine of these (69%) presented complex arrhythmias. Of the ten patients without VLP, 5 (50%) presented complex arrhythmias. The incidence of arrhythmias was highest during the last two hours of dialysis and in the two hours following it. The patients were then divided into two groups (A and B) according to the ejection fraction (EF) found at the echocardiogram. Group A was composed of 17 patients of whom 8 (47%) presented complex arrhythmias; group B (EF < 45%) was composed of the remaining six patients, who all presented complex arrhythmias. In group A nine patients (53%) out of 17 had LVP, in group B four out of six (66%) had it. All the patients except one presented an increase in the thickness of the ventricular wall and alterations of Doppler transmitral filling rate. Left ventricular hypertrophy was diagnosed in 22 out of the 23 patients. Four patients also had chronic ischaemic heart disease; of these three had LVP. There was no correlation between the presence of LVP and the hemodialytic indices and between the latter and complex arrhythmias. CONCLUSIONS: Our study showed that arrhythmias are more frequent in patients with LVP before dialysis than in those without. The difference was statistically significant (p < 0.006); the incidence of arrhythmias was higher in patients with FE < 45% (p < 0.001). The majority of patients (95%) had left ventricular hypertrophy; only four (17%) had ischaemic heart disease too. It is highly probable that the presence of LVP in our patients can be attributed to hypertension and subsequent left ventricular hypertrophy. As patients with LVP at the end of dialysis had a greater incidence of arrhythmias than those without LVP, we suggest that this method could be useful as a first screening in dialysed patients.     

OTDM transmitter using WDM-TDM conversion with an electroabsorptionwavelength converter

An all-optical multiplexing technique using wavelength division multiplexing (WDM)-time division multiplexing (TDM) conversion with an electroabsorption wavelength converter has been proposed and demonstrated. The effectiveness of this WDM-TDM conversion technique for various pulsewidth settings was experimentally investigated. The fluctuation of the signal performance, which was inevitably caused by the coherent crosstalk between adjacent pulses in the conventional optical time division multiplexing (OTDM) technique, were successfully suppressed, even in the case of wide pulse duration. High Q-factor performance has been maintained for a wide range of duty ration from 36% to 74%. By introducing this technique to the optical time division multiplexer, a highly stable and high-quality 40-Gb/s optical signal can be effectively produced without generating the short pulse or setting two tributaries at orthogonal polarization states, and without introducing high-speed electronics for signal multiplexing. The WDM-TDM conversion with an electroabsorption wavelength converter was extended to 60-Gb/s operation by using three 20-Gb/s tributaries. A clear eye opening was confirmed for a waveform after the WDM-TDM conversion of the 60-Gb/s signal     

Synthesis, Characterization, and Formation Process of Na-X Zeolite from Coal Fly Ash

Using the SiO₂ and Al₂O₃ components of the amorphous phase in coal fly ash (Fa), Fa was converted to Na-X zeolites in NaOH-NaAlO₂ solutions by stirring at 35°C for 72 hr and then aging at 85°C for a given period. The molar ratio SiO₂/Al₂O₃ of the starting materials was controlled from 2.0 to 13.2. The resulting materials were characterized by various means. Increasing the SiO₂/Al₂O₃ ratio of the starting material increased the degree of crystallinity of faujasite, exhibiting a maximum at SiO₂/Al₂O₃ = 8.0. The faujasite formed was identified as Na-X zeolite with Si/Al = 1.20. The amorphous phase in Fa was dissolved during the stirring to form a precursor of zeolite, such as amorphous aluminosilicate. The Na-X zeolite was formed by aging for 24 hr, and the degree of crystallinity of this material was increased with the increasing aging period. The cation exchange capacity and specific surface area were increased with the increasing degree of crystallinity of the Na-X zeolites.     

Wideband and compact folded loop antenna

A simple and successful design method that yields a wideband and compact antenna without a ground plane is proposed. The antenna, referred to as the folded loop antenna, can, with the right parameters, achieve wideband characteristics. Calculated and measured results agree well and more than 50% bandwidth (return loss /spl les/-10 dB) is obtained.     

Characterization and electrochemical properties of CF4 plasma-treated boron-doped diamond surfaces

The effect of CF₄ plasma etching on diamond surfaces, with respect to treatment time, was investigated using scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. SEM observations and Raman spectra indicated an increase in surface roughening on a scale of 10–20 nm, and an increase in crystal defect density was apparent with treatment time in the range of 10 s to 30 min. In contrast, alteration of the diamond surface terminations from oxygen to fluorine was found to be rather rapid, with saturation of the F/C atomic ratio estimated from XPS analysis after treatment durations of 1 min and more. The redox kinetics of Fe(CN)₆^3−/4− was also found to be significantly modified after 10 s of CF₄ plasma treatment. This behavior shows that C–F terminations predominantly affect the redox kinetics compared to the effect on the surface roughness and crystal defects. The double-layer capacitance (C_dl) of the electrolyte/CF₄ plasma-treated boron-doped diamond interface was found to show a minimum value at 1 min of treatment. These results indicate that a short-duration CF₄ plasma treatment is effective for the fabrication of fluorine-terminated diamond surfaces without undesirable surface damage.     

Comparison of activities in selective catalytic reduction of NOx by C3H8 over Co/MFI, Fe/MFI, and H/MFI zeolite catalysts

The Co/MFI(SiO₂/Al₂O₃ = 30) were prepared by a precipitation method with NaOCl in alkali solutions exhibited high activities to N₂ at 250 °C for the selective catalytic reduction (SCR) of NO_x. These catalysts showed two UV–vis bands at 700 and 400 nm, indicating the presence of octahedral Co(III) as well as tetrahedral Co(II). The high SCR activity over such Co(III, II)/MFI(30) seems to come from Co(III)---O moieties. The Co(II)MFI(30) catalysts prepared from Co(II)Cl₂ exhibited low SCR activities due to the presence of tetrahedral Co(II) ions in MFI. Less CO formation occurred over Co/MFI catalysts. The Fe/MFI(30) catalyst exhibited high activity due to the presence of some Fe---O species in MFI but more amount of CO were produced during SCR. H/MFI(30) catalyst exhibited a good SCR activity. However, more amount of carbonaceous deposits were produced on it. The correlation between acid concentration and SCR activity was discussed over H/MFIs.     

Growth of Potassium Titanate Fibers in Flowing N2 Gas

The length of potassium titanate fibers produced by several conventional methods averages 50 μm, with a maximum of 100 μm. Extremely long fibers (most >1000 μm long) were obtained by calcination in N₂ gas flowing at 5.2×10^-4 m/s.     

Radiation detector made of a high-quality polycrystalline diamond

Radiation detector was made of a high-quality CVD polycrystalline diamond composed of frost column like structure diamond grains, and induced charge distribution spectra and drift velocities were measured by using alpha particles. As a result, the CVD polycrystalline achieved maximum induced charge of 83% of HP/HT type IIa diamond. Moreover, the CVD crystal had lower charge loss on electrons compared with the HP/HT type IIa diamond. Drift velocities of electrons and holes were v_e = 7.7 × 10⁴ and v_h = 7.3 × 10⁴cm/s at an electric field of 20 kV/cm, respectively. In addition, response function measurement for 14 MeV neutrons was carried out.     

Improved direct bonding method of Nd:YVO4 and YVO4 laser crystals

We succeeded in the fabrication of bonded laser crystals composed of a neodymium-doped YVO₄ laser crystal (Nd:YVO₄) and its host crystals YVO₄ by a newly developed dry etching technique using an argon ion beam. The optical distortion caused by the bonded interface of size 5 mm × 6 mm was estimated to be 0.05λ at 633 nm. From the comparison of laser performance pumped by a laser diode, the bonded crystals could increase the laser output power by nearly twice that of the non-bonded crystals with the same degree of polarization of 99.2%. To analyze the mechanism of the enhanced reduction of the thermal load in the bonded crystals, numerical simulations with a finite-element method were also performed.