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In this work, we investigate the optical properties of hafnium dioxide nanocrystals, upon X-ray irradiation, looking for spectral evolution following thermal treatments in air up to 1000 °C that modify the crystal size as well as their point defect concentrations. Radio-luminescence measurements from 10 K up to room temperature reveal a rich and evolving picture of the optical features. A complete spectral analysis of the broad luminescence spectra reveals the presence of several emission components in the visible and UV regions. The lower energy components peaking at 2.1, 2.5, and 2.9 eV are characterized by a thermal quenching energy of 0.08 eV, while the corresponding value for the UV bands at 4.1 and 4.7 eV is close to 0.23 eV. We tentatively assign the components ranging from 2 to 3 eV to the presence of optically active defects of an intrinsic nature, together with the occurrence of titanium impurities; conversely, the bands at higher energies are likely to be of an excitonic nature. The comparison with previous photo-luminescence studies allows evidencing characteristic differences between the features of luminescence emissions caused by intra-centre excitation and those occurring under ionizing irradiation. Finally, scintillation measurements in the visible range reveal the existence of a fast decay in the nanosecond time scale for the smallest hafnia nanocrystals. This study offers a clear description of HfO2 luminescence characteristics upon excitation by X-rays and can lead to a better comprehension of the structure–property relationship at the nanoscale in metal oxides. [ABSTRACT FROM AUTHOR]

BaTiO3 films are extensively used in many electrical devices, because they offer remarkable dielectric and ferroelectric properties. Here, we demonstrate a powerful, nanoparticle-based deposition route towards BaTiO3 films with systematic thickness control over a wide range up to several microns. The unusual control over the film thickness with the maintenance of crack free nanostructures, phase and ferroelectric properties of the BaTiO3 films allows us to fabricate various future devices of different thicknesses by a single deposition method. For this, films are deposited from stable dispersions of BaTiO3 nanocrystals, synthesized via an efficient microwave-assisted non-aqueous sol–gel approach. Crack-free films of controlled thickness are obtained by a carefully elaborated, alternating process of spin-coating and intermediate drying. According to X-ray diffraction and confocal Raman microscopy, the final, sintered films consist of BaTiO3 nanocrystals of about 20 nm in a hexagonal–tetragonal phase mixture. The nanoparticulate films display outstanding optical characteristics exceeding 90% transparency above 500 nm and a band gap of 3.5 eV. The latter, band gap, is larger than the classic bulk material's band gap of 3.2 eV, indicating a more electrically insulating nature of the films. Piezoresponse force microscopy gives evidence for potent ferroelectric switching. This newly accessible film processing route with wide film thickness tuning allows for desired ferroelectric response with the advantage of a wide film thickness to implicate building blocks for various applications e.g. ferroelectric random access memory devices, microelectromechanical system devices or Bragg reflectors. [ABSTRACT FROM AUTHOR]

Abstract: The contribution presents the results of investigations performed on the new class of CO2 chemoresistive materials based on rare earths oxy-carbonates. Firstly, the performance an alternative senso2r readout parameter, work function, is presented together with a comparison between the effect of the target gas, CO, and main interferent, water vapor. Afterwards, new synthesis routes, targeting the lowering of the sensitive materials costs are described together with sensing performance obtained in realistic application conditions. [Copyright &y& Elsevier]

Abstract: In this work we compare the CO2 gas sensing properties of two new materials synthesized from rare earth hydroxide (La(OH)3,Pr(OH)3) precursors, with the already reported ones for neodymium oxycarbonate, which was synthesized from the corresponding Nd(OH)3 precursor. In-situ XRD measurements show that by following similar thermal treatment, praseodymium hydroxide is transforming to the metal oxide while lanthanum hydroxide forms an oxycarbonate, like in the case of neodymium. The chemoresistive effects we found for the lanthanum oxycarbonate were even higher than the ones recorded for the neodymium oxycarbonate; for the praseodymium metal oxide we could not find any CO2 sensitivity. Accordingly, we think that the condition for CO2 sensing is the formation of the rare earth oxycarbonate. [ABSTRACT FROM AUTHOR]

A total of 2538 quarter milk samples from 638 lactating dairy cows from 47 farms in the canton of Bern, Switzerland, were investigated for streptococci. A novel, simple and inexpensive laboratory method was used for the differentiation of Streptococcus species, and a risk factor analysis was carried out. The prevalence in the quarter milk samples was 0.2 per cent for Streptococcus agalactiae, 1.3 per cent for Streptococcus uberis, 1.3 per cent for Streptococcus dysgalactiae, 0.1 per cent for Enterococcus species and 2.9 per cent for minor Streptococcus species (designated Streptococcus-Lactococcus-Enterococcus [SLE] group). Based on the somatic cell count (SCC), S uberis and S dysgalactiae were classified as 'major' pathogens and the bacteria in the SLE group as 'minor' pathogens. For S uberis, S dysgalactiae and bacteria in the SLE group, the most significant risk factor was an intramammary infection (IMI) of a neighbouring quarter by the same pathogen. Other significant risk factors for S uberis infection were a positive California Mastitis Test (CMT) result and a SCC of more than100,000 cells/ml. Significant risk factors for IMI with S dysgalactiae were a positive CMT result, teat injury and palpable abnormalities in the udder. Infection with bacteria in the SLE group was significantly associated with a SCC of more than 100,000 cells/ml, a lactation number of more than 2, the right rear quarter (as the location of infection) and a positive CMT result. [ABSTRACT FROM AUTHOR]

Abstract: In this work the sensing of Nd2O2CO3-based chemoresistive CO2 sensor was investigated combining DRIFT and DC-resistance measurements. Besides the already reported effect of CO2 exposure, we found that exposure to CO determines comparable effects and that the presence of oxygen in the background is not important. The humidity significantly influences the response for both gases. The spectroscopic results reveal that the exposure to both CO and CO2 consumes the water-related surface species – the rooted-hydroxyls being the electrically active one – and increases the concentration of carbonates; the decrease of the rooted-hydroxyls is probably the cause of the resistance increase. [Copyright &y& Elsevier]

Intact spontaneously hypertensive rats (SHR) were studied to assess the effect of prolonged antihypertensive treatment on the elastic behaviour of the external carotid artery. Thirty-week-old SHR received the ACE inhibitor captopril, the ateriolar dilator hydralazine or their vehicle for 6 weeks. These rats were compared to normotensive, vehicle treated WKY rats. The internal diameter of the carotid artery was measured continuously in halothane-anaesthetized rats using an echo-tracking device, and intra-arterial pressure was also monitored continuously, on the controlateral side. Captopril- and hydralazinetreated SHR as well as normotensive controls had similar blood pressure values. No significant shift in the distensibility-pressure curves was observed among vehicle-treated SHR and WKY rats or the SHR which had received captopril or hydralazine. Histological examination of the carotid artery fixed ex vivo with paraformaldehyde showed a significant increase in cross-sectional area in vehicle-treated SHR as compared to their normotensive counterparts. These results therefore suggest that the elastic behaviour of elastic arteries is not necessarily altered by the structural changes developing in response to hypertension. [ABSTRACT FROM PUBLISHER]

The usefulness of exercise testing (ET) in old age is so far undefined particularly for detection of arrhythmias. We compared the diagnostic value of ET with 24-h long-term ECG recording (LT-ECG) in patients older than 70 years that were evaluated because of symptoms possibly related to arrhythmias. In 37 patients (age 72·8±2·7 years) the incidence of ventricular arrhythmias (LOWN≥1) was greater during ET (67%) than during 24-h L T-ECG recording (48%, P <0·01). Complex ventricular arrhythmias were detected in 6/37 patients (16%) by ET, in 9/37 patients (24%) by LT-ECG, in one patient (3%) by both tests and in 14/37 patients (37%) by one of the two tests, while 23/37 patients (63%) had no significant complex arrhythmias recorded by either test. During ET 12 patients (32%) showed signs of myocardial ischaemia with ST-depression ≥0·2 m V and/or increasing angina pectoris. In 42% of these patients complex ventricular arrhythmias LOWN≥3 occurred during ET. Thus both ET and LT-ECG are useful methods to uncover arrhythmias in symptomatic patients older than 70 years and have to be considered as complementary tools. [ABSTRACT FROM PUBLISHER]

Eight women and 4 men, mean age 71·1 years, examined by a clinical check-up participated in a bicycle ergometer training program (12 weeks with 3 training sessions per week). Symptom limited ergometric bicycle tests were performed before and after the training period. The training work load was continuously controlled by maintaining the training heart rate according to 60% of the maximum work load of the first test. To hold the training heart rate (HR) on a constant level the work load had to be increased systematically during the whole training period up to 180% of the level at the beginning. The working time in each training session was increased from 2 × 10 mm at the beginning up to 2 × 20 mm after the sixth week. The maximum work load (+ 16%) and the maximum oxygen uptake (+ 11%) increased significantly. The submaximal HR decreased significantly. In contrast there was no significant difference in maximum HR and maximal change of base excess between the initial exercise test and the control study at the end of the training program. This indicates that the increased exercise capacity represents a real endurance training effect and not only an increase in the degree of exhaustion. We conclude that also in healthy people between 67–76 years a significant endurance effect is possible when the training work load and training time is increased systematically according to the rules of training sciences. [ABSTRACT FROM PUBLISHER]