Morphology-driven electrical and optical properties in graded hierarchical transparent conducting Al:ZnO

Graded Al-doped ZnO layers, constituted by a mesoporous forest like system evolving into a compact transparent conductor, were synthesized by Pulsed Laser Deposition with different morphology to study the correlation with functional properties. Morphology was monitored by measuring the resulting surface roughness and its effects on electrical conductivity (especially carrier mobility, which significantly decreases with increasing roughness) allow to discuss the limitations in conduction mechanisms. Significant changes in light scattering capability due to variations in morphology are also investigated and discussed to study the correlation between morphology and functional properties.Comment: 11 pages, 4 figure

Structure-dependent optical and electrical transport properties of nanostructured Al-doped ZnO

The structure-property relation of nanostructured Al-doped ZnO thin films has been investigated in detail through a systematic variation of structure and morphology, with particular emphasis on how they affect optical and electrical properties. A variety of structures, ranging from compact polycristalline films to mesoporous, hierarchically organized cluster assemblies, are grown by Pulsed Laser Deposition at room temperature at different oxygen pressures. We investigate the dependence of functional properties on structure and morphology and show how the correlation between electrical and optical properties can be studied to evaluate energy gap, conduction band effective mass and transport mechanisms. Understanding these properties opens the way for specific applications in photovoltaic devices, where optimized combinations of conductivity, transparency and light scattering are required.Comment: 8 pages, 9 figure

Tuning of Electrical and Optical Properties of Highly Conducting and Transparent Ta-Doped TiO2 Polycrystalline Films

We present a detailed study on polycrystalline transparent conducting Ta-doped TiO2 films, obtained by room temperature pulsed laser deposition followed by an annealing treatment at 550°C in vacuum. The effect of Ta as a dopant element and of different synthesis conditions are explored in order to assess the relationship between material structure and functional properties, i.e. electrical conductivity and optical transparency. We show that for the doped samples it is possible to achieve low resistivity (of the order of 5×10-4 Ωcm) coupled with transmittance values exceeding 80% in the visible range, showing the potential of polycrystalline Ta:TiO2 for application as a transparent electrode in novel photovoltaic devices. The presence of trends in the structural (crystalline domain size, anatase cell parameters), electrical (resistivity, charge carrier density and mobility) and optical (transmittance, optical band gap, effective mass) properties as a function of the oxygen background pressures and laser fluence used during the deposition process and of the annealing atmosphere is discussed, and points towards a complex defect chemistry ruling the material behavior. The large mobility values obtained in this work for Ta:TiO2 polycrystalline films (up to 13 cm2V-1s-1) could represent a definitive advantage with respect to the more studied Nb-doped TiO2

Scoliosis in patients with Prader Willi Syndrome – comparisons of conservative and surgical treatment

In children with Prader Willi syndrome (PWS), besides growth hormone (GH) therapy, control of the food environment and regular exercise, surgical treatment of scoliosis deformities seems the treatment of choice, even though the risks of spinal surgery in this specific population is very high. Therefore the question arises as to whether the risks of spinal surgery outweigh the benefits in a condition, which bears significant risks per se. The purpose of this systematic review of the Pub Med literature was to find mid or long-term results of spinal fusion surgery in patients with PWS, and to present the conservative treatment in a case study of nine patients with this condition

Prader-Willi syndrome: A primer for clinicians

The advent of sensitive genetic testing modalities for the diagnosis of Prader-Willi syndrome has helped to define not only the phenotypic features of the syndrome associated with the various genotypes but also to anticipate clinical and psychological problems that occur at each stage during the life span. With advances in hormone replacement therapy, particularly growth hormone children born in circumstances where therapy is available are expected to have an improved quality of life as compared to those born prior to growth hormone

Evaluation of noninvasive exercise cardiac output determination in chronic heart failure patients: a proposal of a new diagnostic and prognostic method

Peak oxygen consumption (VO 2) and various parameters of cardiopulmonary response to exercise are of important prognostic value in chronic heart failure patients. However, all the available parameters only indirectly reflect left-ventricular dysfunction and hemodynamic adaptation to an increased demand. Noninvasive assessment of cardiac output, especially during an incremental exercise test, would allow the direct measurement of cardiac reserve and may become the gold standard for prognostic evaluation of chronic heart failure patients

Tuning Hierarchical Cluster Assembly in Pulsed Laser Deposition of Al-doped ZnO

The synthesis of hierarchically assembled Al-doped ZnO layers by Pulsed Laser Deposition (PLD) at room temperature was investigated. PLD was performed in a background pressure of 100 Pa O2 to deposit clusters in a low energy regime and obtain nano- and mesostructures resulting from a hierarchical assembly of nanoclusters. We here analyzed the effects of varying the gas flow rate on mesoscale morphology, mass density and optical properties. The variation of the target-to-substrate distance was also investigated, identifying its effects on mass density and film morphology. The optimization of optical properties in terms of transparency and light scattering capability is of potential interest for photovoltaic applications

A simple toll to predict excercise capacity in obese patients with ischemic heart disease

Objective: To define an equation that predicts exercise capacity taking into account body mass index (BMI). Design: Retrospective analysis and validation study of a multidisciplinary programme aimed at weight loss and physical rehabilitation. Setting: Tertiary referral hospital. Patients and methods: 372 consecutive obese participants (249 men) with stable ischaemic heart disease, aged mean 60.1 (SD 8.7) years, underwent a treadmill exercise test. BMI was 37.8 (4.5) kg/m2. In the validation study the model was tested in 87 patients with similar characteristics. Results: Mean exercise intensity was 6.6 (SD 2.4) metabolic equivalents (METs). Multivariate linear regression analysis defined two simple models that considered exercise intensity as the dependent variable and a set of independent variables such as anthropometric measures, age and sex in the first one, plus associated clinical conditions and drug treatment in the second one. The correlation coefficients of the two models were R = 0.630 and R = 0.677, respectively. Age, BMI and sex were the strongest predictors of exercise capacity. The first derived equation efficiently predicted exercise capacity: in the validation study predicted exercise intensity was 6.3 (1.6) METs and attained exercise intensity was 6.3 (2.4) METs (p = 0.903) with a highly significant correlation (R = 0.534, p < 0.001 ). Conclusion: BMI is an important determinant of exercise capacity of obese people with ischaemic heart disease. The use of a simple equation may help in predicting exercise capacity, in individualising exercise protocol and in setting up rehabilitation programs for obese patients