The role of morphometric and respiratory factors in predicting the severity and evolution of urinary symptoms in patients with obstructive sleep apnea syndrome.

OBJECTIVES: To assess the severity, evolution, and behaviour of several urinary symptoms in patients with obstructive sleep apnea syndrome (OSAS) before and after the treatment with continuous positive airway pressure (CPAP). METHODS: A prospective study was performed on patients with a recent diagnosis of sleep apnea confirmed by nocturnal sleep polygraphy and absence of medical urological past history. The symptom incidence was analysed seeking predictive factors for initial nocturia, nocturnal polyuria (NP), and unfavourable International Prostate Symptoms Score (IPSS) before and after a 1-year period of treatment using a CPAP device. Morphometric variables (body mass index, BMI; neck and abdominal diameter) and functional respiratory variables (FEV1, FVC, and FEV1/FVC) were analysed. A multivariate analysis was performed with a calculation of Pearson's correlation coefficient to establish a linear relation between the variables. RESULTS: A total of 43 patients completed the two-step study (IPSS and bladder diary before and after the CPAP treatment). IPSS decreased by 3.58 points. Nocturia decreased to once per night. Neck diameter, FEV1, and FEV1/FVC significantly predicted the initial severity of some lower urinary tract symptoms (LUTS), (p=0.015, p=0.029, p=0.008, respectively). Neck diameter, abdominal perimeter, and FEV1/FVC significantly predicted the LUTS evolution throughout the study (p=0.023, p=0.007, p=0.05, respectively). CONCLUSION: Some pre-treatment morphometry and spirometry parameters such as abdominal or neck diameter, FEV1, and FEV1/FVC were predictive of the severity and evolution of LUTS in patients with OSAS.

Unravelling the polarity of InN quantum dots using a modified approach of negative-spherical-aberration imaging.

InN quantum dots (QDs) are considered to be promising nanostructures for different device applications. For any hexagonal AB-stacking semiconductor system, polarity is an important feature which affects the electronic properties. Therefore, the determination of this characteristic on any wurtzite (semi)polar III-N compound or alloy is essential for defining its applicability. In this paper, the polarity of InN QDs grown on silicon by indium droplet epitaxy plus nitridation and annealing was determined by a modified approach combining exit wave reconstruction with negative-spherical-aberration high-resolution lattice imaging using TEM. Comparing the micrographs of two QDs from the same TEM specimen with the simulated images of InN slab structures generated under the same conditions as of the experiments, it was confirmed that the QDs of the present study are N polar. Given that the settlement of material's polarity has always been a tedious, indirect and controversial issue, the major value of our proposal is to provide a straightforward procedure to determine the polar direction from atomic-resolution focal series images.

Engineering of III-Nitride Semiconductors on Low Temperature Co-fired Ceramics.

This work presents results in the field of advanced substrate solutions in order to achieve high crystalline quality group-III nitrides based heterostructures for high frequency and power devices or for sensor applications. With that objective, Low Temperature Co-fired Ceramics has been used, as a non-crystalline substrate. Structures like these have never been developed before, and for economic reasons will represent a groundbreaking material in these fields of Electronic. In this sense, the report presents the characterization through various techniques of three series of specimens where GaN was deposited on this ceramic composite, using different buffer layers, and a singular metal-organic chemical vapor deposition related technique for low temperature deposition. Other single crystalline ceramic-based templates were also utilized as substrate materials, for comparison purposes.

Inline electron holography and VEELS for the measurement of strain in ternary and quaternary (In,Al,Ga)N alloyed thin films and its effect on bandgap energy.

We present the use of (1) dark-field inline electron holography for measuring the structural strain, and indirectly obtaining the composition, in a wurtzite, 4-nm-thick InAlGaN epilayer on a AlN/GaN/AlN/GaN multinano-layer heterosystem, and (2) valence electron energy-loss spectroscopy to study the bandgap value of five different, also hexagonal, 20-50-nm-thick InAlGaN layers. The measured strain values were almost identical to the ones obtained by other techniques for similarly grown materials. We found that the biaxial strain in the III-N alloys lowers the bandgap energy as compared to the value calculated with different known expressions and bowing parameters for unstrained layers. By contrast, calculated and experimental values agreed in the case of lattice-matched (almost unstrained) heterostructures.