Erbium-doped silicon nanocrystals grown by r.f. sputtering method: competition between oxygen and silicon to get erbium

Erbium doped micro- and nanocrystalline silicon thin films have been deposited by co-sputtering of Er and Si. Films with different crystallinity, crystallite size, hydrogen and oxygen content have been obtained in order to investigate the effect of the microstructure and composition of matrix on the near IR range at 1.54 µm Er-related photoluminescence (PL) properties. The correlation between the optical properties and microstructural parameters of the films is investigated using spectroscopic ellipsometry. It is found that the luminescent properties of these composite films can be understood on the basis of the ellipsometric analysis that reveals the films heterogeneous structure, and that Er-related PL dominates in films with 1-3 nm sized Si nanocrystals embedded in a-Si:H.INTAS Project #03-51-6486Fundação para a Ciência e a Tecnologia Project POCTI/CTM/39395/200

Interrelation between microstructure and optical properties of erbium-doped nanocrystalline thin films

Nanocrystalline silicon thin films codoped with erbium, oxygen and hydrogen have been deposited by co-sputtering of Er and Si. Films with different crystallinity, crystallite size and oxygen content have been obtained in order to investigate the effect of the microstructure on the photoluminescence properties. The correlation between the optical properties and microstructural parameters of the films is investigated by spectroscopic ellipsometry. PL response of the discussed structures covers both the visible wavelength range (a crystallite size-dependent photoluminescence detected for 5–6 nm sized nanocrystals embedded in a SiO matrix) and near IR range at 1.54 microm (Er-related PL dominating in the films with 1–3 nm sized Si nanocrystals embedded in a-Si:H). It is demonstrated that the different PL properties can be also discriminated on the basis of ellipsometric spectra

Dielectric function of nanocrystalline silicon with few nanometers (<3 nm) grain size

The dielectric function of nanocrystalline silicon (nc-Si) with crystallite size in the range of 1 to 3 nm has been determined by spectroscopic ellipsometry in the range of 1.5 to 5.5 eV. ATauc–Lorentz parameterization is used to model the nc-Si optical properties. The nc-Si dielectric function can be used to analyze nondestructively nc-Si thin films where nanocrystallites cannot be detected by x-ray diffraction and Raman spectroscopy

The structure and photoluminescence of erbium-doped nanocrystalline silicon thin films produced by reactive magnetron sputtering

We have produced and studied undoped and erbium-doped nanocrystalline silicon thin films in order to evaluate the erbium influence on the film microstructure and how this correlates with the photoluminescence properties. Films were grown by reactive RF sputtering. For the doped films metallic erbium was added to the c-Si target. The structural parameters and the chemical composition of the different samples were investigated by X-ray in the grazing incidence geometry, Raman spectroscopy, ellipsometry and Rutherford Back Scattering. The effect of the nc-Si/SiOx matrix ,i.e., nc-Si volume fraction and the presence of SiO and/or SiO2 phases, on the erbium photoluminescence efficiency is discussed.(undefined

Spectroscopic ellipsometry study of the layer structure and impurity content in Er-doped nanocrystalline silicon thin films

Er doped nc-Si thin films have been investigated by spectroscopic ellipsometry (SE). The optical response of Er ions in a nc-Si/SiO matrix has been determined by SE, and it has been used to detect Er contents as low as 0.2 at%. The complex layered nanostructure of nc-Si:Er:O has been resolved and it has been found that it is strongly influenced by the Er-doping and the oxygen in-depth distribution profile. SE results are discussed in comparison with data obtained by the standard methods of the X-ray diffraction, Rutherford backscattering and Raman spectroscopy

Behavior Change Techniques Present in Wearable Activity Trackers: A Critical Analysis

Please cite as: Mercer K, Li M, Giangregorio L, Burns C, Grindrod K Behavior Change Techniques Present in Wearable Activity Trackers: A Critical Analysis JMIR Mhealth Uhealth 2016;4(2):e40 DOI: 10.2196/mhealth.4461 PMID: 27122452 PMCID: 4917727Background: Wearable activity trackers are promising as interventions that offer guidance and support for increasing physical activity and health-focused tracking. Most adults do not meet their recommended daily activity guidelines, and wearable fitness trackers are increasingly cited as having great potential to improve the physical activity levels of adults. Objective: The objective of this study was to use the Coventry, Aberdeen, and London-Refined (CALO-RE) taxonomy to examine if the design of wearable activity trackers incorporates behavior change techniques (BCTs). A secondary objective was to critically analyze whether the BCTs present relate to known drivers of behavior change, such as self-efficacy, with the intention of extending applicability to older adults in addition to the overall population. Methods: Wearing each device for a period of 1 week, two independent raters used CALO-RE taxonomy to code the BCTs of the seven wearable activity trackers available in Canada as of March 2014. These included Fitbit Flex, Misfit Shine, Withings Pulse, Jawbone UP24, Spark Activity Tracker by SparkPeople, Nike+ FuelBand SE, and Polar Loop. We calculated interrater reliability using Cohen's kappa. Results: The average number of BCTs identified was 16.3/40. Withings Pulse had the highest number of BCTs and Misfit Shine had the lowest. Most techniques centered around self-monitoring and self-regulation, all of which have been associated with improved physical activity in older adults. Techniques related to planning and providing instructions were scarce. Conclusions: Overall, wearable activity trackers contain several BCTs that have been shown to increase physical activity in older adults. Although more research and development must be done to fully understand the potential of wearables as health interventions, the current wearable trackers offer significant potential with regard to BCTs relevant to uptake by all populations, including older adults

Acceptance of Commercially Available Wearable Activity Trackers Among Adults Aged Over 50 and With Chronic Illness: A Mixed-Methods Evaluation

Please cite as: Mercer K, Giangregorio L, Schneider E, Chilana P, Li M, Grindrod K Acceptance of Commercially Available Wearable Activity Trackers Among Adults Aged Over 50 and With Chronic Illness: A Mixed-Methods Evaluation JMIR Mhealth Uhealth 2016;4(1):e7 DOI: 10.2196/mhealth.4225 PMID: 26818775 PMCID: 4749845Background: Physical inactivity and sedentary behavior increase the risk of chronic illness and death. The newest generation of “wearable” activity trackers offers potential as a multifaceted intervention to help people become more active. Objective: To examine the usability and usefulness of wearable activity trackers for older adults living with chronic illness. Methods: We recruited a purposive sample of 32 participants over the age of 50, who had been previously diagnosed with a chronic illness, including vascular disease, diabetes, arthritis, and osteoporosis. Participants were between 52 and 84 years of age (mean 64); among the study participants, 23 (72%) were women and the mean body mass index was 31 kg/m2 . Participants tested 5 trackers, including a simple pedometer (Sportline or Mio) followed by 4 wearable activity trackers (Fitbit Zip, Misfit Shine, Jawbone Up 24, and Withings Pulse) in random order. Selected devices represented the range of wearable products and features available on the Canadian market in 2014. Participants wore each device for at least 3 days and evaluated it using a questionnaire developed from the Technology Acceptance Model. We used focus groups to explore participant experiences and a thematic analysis approach to data collection and analysis. Results: Our study resulted in 4 themes: (1) adoption within a comfort zone; (2) self-awareness and goal setting; (3) purposes of data tracking; and (4) future of wearable activity trackers as health care devices. Prior to enrolling, few participants were aware of wearable activity trackers. Most also had been asked by a physician to exercise more and cited this as a motivation for testing the devices. None of the participants planned to purchase the simple pedometer after the study, citing poor accuracy and data loss, whereas 73% (N=32) planned to purchase a wearable activity tracker. Preferences varied but 50% felt they would buy a Fitbit and 42% felt they would buy a Misfit, Jawbone, or Withings. The simple pedometer had a mean acceptance score of 56/95 compared with 63 for the Withings, 65 for the Misfit and Jawbone, and 68 for the Fitbit. To improve usability, older users may benefit from devices that have better compatibility with personal computers or less-expensive Android mobile phones and tablets, and have comprehensive paper-based user manuals and apps that interpret user data. Conclusions: For older adults living with chronic illness, wearable activity trackers are perceived as useful and acceptable. New users may need support to both set up the device and learn how to interpret their data

Surface Texturing of n- and p-Doped c-Si Using a Novel Plasma Chemical Texturing Process

Abstract n- and p-doped c-Si (100) are textured by a SF 6 /O 2 plasma chemical etching, under conditions avoiding ion bombardment. The study of the effects of plasma parameters on morphology and on surface reflectance of textured c-Si reveals a strong impact of silicon doping on texturing characteristics. SF 6 /O 2 plasma etches anisotropically n-type c-Si creating a square-based hillock-like morphology with a surface reflectivity of 6%. Conversely, for p-type Si, a H 2 plasma pretreatment is necessary to activate silicon etching and obtain a nano-textured surface with a reflectivity of 16%

Updated distribution of Osmoderma eremita in Abruzzo (Italy) and agro-pastoral practices affecting its conservation (Coleoptera: Scarabaeidae)

New records of Osmoderma eremita (Scopoli, 1763) (Coleoptera: Scarabaeidae: Cetoniinae) are reported for Abruzzo (Italy), together with a review of its distribution in this region. O. eremita is a saproxylic beetle dependent on the presence of hollow deciduous trees with abundant wood mould in their cavities. The major threats for the species are habitat loss and fragmentation. EU Habitats Directive requests to the member States its protection and the monitoring of its conservation status. Detection of its occurrence is the first step to protect the species. The surveys have been carried out in ten sites of Abruzzo by using black cross-windows traps baited with specific pheromone. The species has been recorded for the first time in the Sant'Antonio forest and its presence is confirmed in the Peligna Valley, after a decade. The populations seem to be confined to small patches of suitable habitats. At local level, the abandonment of the pollarding practice (willow and beech forests) and the use of pollarded trees as biomass for fuel are the major threats for this species. Indeed some key actions, such as the protection of old hollow trees and the continuation of pollarding practice in rural landscape, could be key factors for the conservation strategies of the species in the study area

INTEGRATED APPROACH COMBINING DIRECT SURVEY AND OBSERVATION IN DAMAGE ANALYSIS IN CASE OF SOIL SETTLEMENT

Nowadays, different methods are used to study historical masonry buildings. Among these, for the study of architectures with complex geometry, the effectiveness of an integrated approach, that is a method of analysis combining different disciplines, is increasingly evident.The aim of this paper is to show the importance of combining direct observation with structural analysis in order to understand the level of safety in buildings with composite geometries.This paper describes the analysis executed in the XX century parish church of San Bernardino in Sesto Calende (Va), which displays serious cracks and damage caused by soil settlements.The integrated approach starts with historical analysis, by consulting all available documents and drawings. To understand the geometry of the structure a new survey has been made and a three-dimensional digital representation was modeled, by which better deriving the weight of all the elements in the construction, and to find the correct actions and thrust on arches, columns, bases and foundation. All this data was used in the structural analysis based on the static method of limit analysis. For the material behavior the model proposed by J. Heyman (1966) is used, considering the “no tension” failure criterion. The static theorem of minimum reactions for settled states enunciated by M. Como (2010) is employed for the analysis of soil settlement effects on the building’s response.The work shows how direct survey of geometry and damage of a complex building has an effective importance in the structural analysis to ensure Cultural Heritage preservation and safety.</p