Semiempirical Two-Dimensional Model of the Bipolar Resistive Switching Process in Si-NCs/SiO2 Multilayers.

In this work, the SET and RESET processes of bipolar resistive switching memories with silicon nanocrystals (Si-NCs) embedded in an oxide matrix is simulated by a stochastic model. This model is based on the estimation of two-dimensional oxygen vacancy configurations and their relationship with the resistive state. The simulation data are compared with the experimental current-voltage data of Si-NCs/SiO2 multilayer-based memristor devices. Devices with 1 and 3 Si-NCs/SiO2 bilayers were analyzed. The Si-NCs are assumed as agglomerates of fixed oxygen vacancies, which promote the formation of conductive filaments (CFs) through the multilayer according to the simulations. In fact, an intermediate resistive state was observed in the forming process (experimental and simulated) of the 3-BL device, which is explained by the preferential generation of oxygen vacancies in the sites that form the complete CFs, through Si-NCs.

Digital and Analog Resistive Switching Behavior in Si-NCs Embedded in a Si/SiO2 Multilayer Structure for Neuromorphic Systems.

In this work, we report the digital and analog resistive-switching (RS) characteristics in a memristor based on silicon nanocrystals (Si-NCs) integrated into a complementary metal-oxide-semiconductor (MOS) structure. Si-NCs with a diameter of 5.48 ± 1.24 nm embedded in a SiO2/Si-NCs/SiO2 multilayer structure acts as an RS layer. These devices exhibit bipolar RS with an intermediate resistance step during SET and RESET processes, which is believed to lie in the Si-NCs layer acting as charge-trapping nodes. The endurance studies of about 70 DC cycles indicate an ON/OFF ratio of ~106 and a retention time larger than 104 s. Long-term potentiation (LTP, -2 V) and long-term depression (LTD, +4 V) are obtained by applying consecutive identical pulse voltages of 150 ms duration. The current value gradually increases/decreases (LTP/LTD) as the pulse number increases. Three consecutive identical pulses of -2 V/150 ms (LTP) separated by 5 and 15 min show that the last current value obtained at the end of each pulse train is kept, confirming an analog RS behavior. These characteristics provide a possible way to mimic biological synapse functions for applications in neuromorphic computing in Si-NCs-based CMOS structures.

Identification of Secondary Metabolites of Interest in Pleurotus djamor Using Agave tequilana Bagasse.

Agro-industrial residues represent more than 60% of organic wastes worldwide, which could be used to generate other by-products or to be incorporated into other production chains. For example, bagasse is a waste from the tequila industry in Mexico that could be implemented for mushroom cultivation. Additionally, the substrate influences the growth, development, and production of secondary metabolites of fungi. This work presents a comparative experiment that studies the metabolite production in Pleurotus djamor mushrooms on agave bagasse and barley straw (traditional substrate). The biological efficiency (BE), yield, phenolics and flavonoids, antioxidant capacity, tannins, and the identification of low molecular weight metabolites were evaluated. Five treatments were proposed according to the following mixtures of agave bagasse: barley straw: T1 (1:0), T2 (3:1), T3 (1:1), T4 (1:3), and T5 (0:1). T2 had the highest yield (13.39 ± 3.23%), BE (56.7 ± 13.71%), and flavonoids (44.25 mg rutin equivalent (RE)/g); T3 obtained the highest phenol content (230.27 mg GAE/g); and T1 the highest tannins content (0.23 mg (+) catechin equivalent (CE)/g). Finally, T1 and T5 are the ones that present the greatest number of primary metabolites, including hydroxycitric acid, 2-deoxy-D-galactose, D-mannose, paromomycin, palmitic acid, pyrrole, mannitol, and DL arabinose, while in T2, T3, and T4 only two chemical compounds were found present (palmitic acid and pyrrole in T2, silicic acid and pyrrole in T3 and 2-deoxy-D-galactose and quinoline in T4). The cultivation substrate influences the concentration of bioactive molecules in the fruiting bodies of P. djamor. Additionally, P. djamor's degradation of agave bagasse residue generates a potential application for agro-industrial residue management at a low cost.

Study of the Effect of Nitric Acid in Electrochemically Synthesized Silicon Nanocrystals: Tunability of Bright and Uniform Photoluminescence.

In this work, we show a correlation between the composition and the microstructural and optical properties of bright and uniform luminescent porous silicon (PSi) films. PSi films were synthesized by electrochemical etching using nitric acid in an electrolyte solution. PSi samples synthesized with nitric acid emit stronger (up to six-fold greater) photoluminescence (PL) as compared to those obtained without it. The PL peak is shifted from 630 to 570 nm by changing the concentration ratio of the HF:HNO3:(EtOH-H2O) electrolyte solution, but also shifts with the excitation energy, indicating quantum confinement effects in the silicon nanocrystals (Si-NCs). X-ray photoelectron spectroscopy analysis shows a uniform silicon content in the PSi samples that emit the strongest PL. High-resolution transmission electron microscopy reveals that the Si-NCs in these PSi samples are about ~2.9 ± 0.76 nm in size and are embedded in a dense and stoichiometric SiO2 matrix, as indicated by the Fourier transform infrared analysis. On the other hand, the PSi films that show PL of low intensity present an abrupt change in the silicon content depth and the formation of non-bridging oxygen hole center defects.

Composition-Dependent Cytotoxic and Antibacterial Activity of Biopolymer-Capped Ag/Au Bimetallic Nanoparticles against Melanoma and Multidrug-Resistant Pathogens.

Nanostructured silver (Ag) and gold (Au) are widely known to be potent biocidal and cytotoxic agents as well as biocompatible nanomaterials. It has been recently reported that combining both metals in a specific chemical composition causes a significant enhancement in their antibacterial activity against antibiotic-resistant bacterial strains, as well as in their anticancer effects, while preserving cytocompatibility properties. In this work, Ag/Au bimetallic nanoparticles over a complete atomic chemical composition range were prepared at 10 at% through a green, highly reproducible, and simple approach using starch as a unique reducing and capping agent. The noble metal nanosystems were thoroughly characterized by different analytical techniques, including UV-visible and FT-IR spectroscopies, XRD, TEM/EDS, XPS and ICP-MS. Moreover, absorption spectra simulations for representative colloidal Ag/Au-NP samples were conducted using FDTD modelling. The antibacterial properties of the bimetallic nanoparticles were determined against multidrug-resistant Escherichia coli and methicillin-resistant Staphylococcus aureus, showing a clear dose-dependent inhibition even at the lowest concentration tested (5 µg/mL). Cytocompatibility assays showed a medium range of toxicity at low and intermediate concentrations (5 and 10 µg/mL), while triggering an anticancer behavior, even at the lowest concentration tested, in a process involving reactive oxygen species production per the nanoparticle Au:Ag ratio. In this manner, this study provides promising evidence that the presently fabricated Ag/Au-NPs should be further studied for a wide range of antibacterial and anticancer applications.

Relationship of Body Mass Index and Footprint Morphology to the Actual Height of the Medial Longitudinal Arch of the Foot.

The medial longitudinal arch height of the foot is linked to individual characteristics such as sex and body mass index, and these characteristics have been shown to be associated with conditions such as flat feet. In this cross-sectional descriptive study, we examined the medial longitudinal arch morphology in an adult population to determine if there are differences related to sex and body mass index, and values were obtained for the foot posture index. Normalized anthropometric measurements and arch indices were calculated from footprints. Groups, defined by sex and body mass index, were compared, and the correlations between body mass index and the variables were determined. In the population studied (266 women and 177 men), significant differences between men and women for the foot posture index and normalized arch measurements were found. Analysis of the variables related to body mass index indicated there were significant differences in arch indices. Significant differences and positive correlations were also found between the arch index and body mass index for the left and right feet among the men and women studied. The results obtained allow us to reflect on and analyze whether the medial longitudinal arch morphology classification methods used in the clinical and research setting are adequate or whether the influence of factors such as body mass index can generate confusion.

Foot Pain and Morphofunctional Foot Disorders in Patients with Rheumatoid Arthritis: A Multicenter Cross-Sectional Study.

Foot problems are highly prevalent in people with rheumatoid arthritis. This study aims to explore the foot morphology, pain and function in rheumatoid arthritis patients and the relation with the time of disease debut. A cross-sectional study was designed. Footprint, the Foot Posture Index, the hallux valgus prevalence, foot pain and function in 66 rheumatoid arthritis patients and the association with time since diagnosis, were recorded. The Foot Function Index, the Manchester Foot Pain and Disability Index, the Visual Analogic Scale, and the Manchester Scale for hallux valgus were administered and analyzed in two groups, with less and more than 10 years of diagnosis of the disease. A high prevalence of pronated (right 36.8% and left 38.6%) and highly pronated (right 15.8% and left 15.8%) feet was observed, as well as an elevated percentage of low arched footprints (right 68.4 and left 66.7%) and hallux valgus (right 59.6% and left 54.4%). Hallux valgus prevalence, toe deformities and Foot Function Index (Functional limitation) factors were significantly associated with the time since RA diagnosed adjusted for the other factors. The adjusted odds ratio of Hallux valgus prevalence was 4.9 (1.2-19.7). In addition, the foot function was diminished, and foot pain was present in most participants. In conclusion, rheumatoid arthritis patients' feet showed altered morphology and function, and with longer rheumatoid arthritis history, metatarsophalangical stability and foot function, but not pain and global foot posture, were likely to deteriorate.

Spectroscopic Properties of Si-nc in SiOx Films Using HFCVD.

In the present work, non-stoichiometric silicon oxide films (SiOx) deposited using a hot filament chemical vapor deposition technique at short time and simple parameters of depositions are reported. This is motivated by the numerous potential applications of SiOx films in areas such as optoelectronics. SiOx films were characterized with different spectroscopic techniques. The deposited films have interesting characteristics such as the presence of silicon nanoclusters without applying thermal annealing, in addition to a strong photoluminescence after applying thermal annealing in the vicinity of 1.5 eV, which may be attributed to the presence of small, oxidized silicon grains (less than 2 nm) or silicon nanocrystals (Si-nc). An interesting correlation was found between oxygen content, the presence of hydrogen, and the formation of defects in the material, with parameters such as the band gap and the Urbach energies. This correlation is interesting in the development of band gap engineering for this material for applications in photonic devices.

Lateral size reduction of graphene oxide preserving its electronic properties and chemical functionality.

Graphene oxide (GO) is widely considered as a graphene precursor when chemically reduced. Nevertheless, through the precise control of two parameters: lateral size and oxidation degree, GO can be useful in many applications as modified graphene oxide or functional reduced graphene oxide. Commonly, the decrease in GO lateral size, involves a change in the C/O ratio and therefore a modification in a large number of characteristics. Here, a simple but effective approach to synthesize GO with lateral dimensions below 100 nm and without modification of its chemical, optical and electronic features is presented. The use of a sonifier at low temperature allows to rapidly reduce the lateral size in ∼82% while preserving the C/O ratio and consequently the chemical stability, the band gap, the electronic energy levels and the functionality. This method will allow several applications from biomedicine to energy, where reliable reduced size of GO is required.

Potential role of Emergency Medical System call centres in epidemiological surveillance of seasonal influenza.

OBJECTIVES: Seasonal influenza causes high morbidity worldwide and high mortality in developing countries. As a result, the development of systems for seasonal influenza surveillance has been of great interest. The aim of this study is to explore the potential role of an Emergency Medical System (EMS) call centre to complement traditional surveillance systems of seasonal influenza. METHODS: Retrospective observational study in which data on influenza from the system of Notifiable Diseases List (Spanish acronym EDO) and Sentinel Physicians Network (Spanish acronym RMC) were compared with information on calls made to the Principality of Asturias EMS call centre that covers all the region population (1,027,659 inhabitants) based on a set of specific criteria to determine differences and explore this emergency call system as a complementary epidemiological surveillance system. Cases registered by different systems have been compared to the same 68 weeks period, from week 45 of 2011 to week 8 of 2013. RESULTS: RMC reported a total of 2,354 cases of influenza, EDO 43,071 cases and EMS call centre 4,360 "case calls" out of 180,720 total emergency calls. Case series of EDO and EMS call centre have shown a positive correlation (R = 0.42, p = 0.003). Case series from EMS call centre and RMC were correlated (R = 0.38, p = 0.007). Case series from EDO and RMC have shown a strong positive correlation (R = 0.91, p < 0.001). Correlation analysis of the cases reported by the three systems have shown a significant positive correlation between them (p < 0.001). The spike of EMS calls related to the studied influenza syndrome occurs one week in advance compared to traditional epidemiological surveillance systems. CONCLUSIONS: EMS call centre data on influenza could be potentially used as a complementary surveillance system to the traditional epidemiological surveillance systems for influenza.

Effectiveness of custom-made foot orthoses in patients with rheumatoid arthritis: a randomized controlled trial.

OBJECTIVE:: To determine the effect of custom-made foot orthoses versus placebo insoles on pain, disability, foot functionality, and quality of life. DESIGN:: Double-blinded randomized controlled trial. SETTING:: University Podiatric Clinical Area. SUBJECTS:: Patients with rheumatoid arthritis. INTERVENTIONS:: Patients were randomly assigned to either group A, which received custom-made foot orthoses, or group B, which received placebo, flat cushioning insoles, for three months. MAIN MEASURES:: The primary outcome was foot pain, measured by visual analog scale. Foot functionality, foot-related disability, and quality of life were measured using the Foot Function Index, the Manchester Foot Pain and Disability Index, and 12-Item Short Form Health Survey (SF-12) questionnaires, respectively, at the beginning and at days 30, 60, and 90. RESULTS:: A total of 53 patients, aged 59.21 ± 11.38 years, received either the custom-made foot orthoses ( N = 28) or the placebo ( N = 25). For the analysis of the data, only participants who had been measured at the four time points (0, 30, 60, and 90 days) were included. In group A, all variables showed statistically significant differences when comparing the initial and final measurements. Pain showed 6.61 ± 2.33 and 4.11 ± 2.66 in group A, at baseline and at 90 days, respectively, and Group B showed 6.16 ± 1.77 and 5.60 ± 2.71 at baseline and at 90 days, respectively. This was the only variable that showed statistically significant difference between groups ( P = 0.048). CONCLUSION:: The custom-made foot orthoses significantly reduced the participants' foot pain, although they did not have positive effects on disability, foot functionality, and quality of life compared with only cushioning.

Accurately Determining Proper Shoe Size in Patients With Rheumatoid Arthritis.

PURPOSE: The aim of this descriptive study was to determine whether people with rheumatoid arthritis (RA) wear adequately fitting footwear. DESIGN: This observational study was carried out in a health center between January and December 2014 in the state of A Coruña, Spain. METHOD: A total of 166 patients (47 men, 119 women) completed all stages of the research process. A validated Brannock Device was used to record foot and shoe length and width. FINDINGS: Only 64 (38.55%) participants wore shoes that met the needs and requirements of their feet, and 98 (59.03%) participants wore the incorrect shoe size, at least in one foot. CONCLUSIONS: Many patients with RA often wear shoes that are too narrow for their foot. Assessing the proper footwear fit is an important part of the clinical foot examination. CLINICAL RELEVANCE: Early detection of inappropriate shoe size in patients with RA allows rehabilitation nurses to optimize foot health.

Functionalization Effect on Polymer Nanocomposite Coatings Based on TiO2⁻SiO2 Nanoparticles with Superhydrophilic Properties.

In this study, a novel binary nanocomposite system based on TiO2-SiO2 was functionalized with trimethylolpropane triacrylate (TMPTA) and characterized by XPS and XRD. Results revealed that TiO2-SiO2 nanoparticles were covalently functionalized. Functionalized nanoparticles at low concentrations (0.1 wt % and 0.5 wt %) were dispersed in acrylic acid acting as a polymer matrix. Nanocomposite coatings analysis demonstrate to achieve superhydrophilic properties as well as very good optical characteristics. Water contact angle characterization showed the functionalization effect by achieving a superhydrophilic behavior with a contact angle less than 5°. UV-Vis measurements demonstrated high optical transmittance above 95% for the coatings. Based on the obtained results a mechanism describing the chemical interactions of the constituents responsible for the synergy in the nanocomposite as well as the morphological play role in the behavior are presented.

Hallux valgus in a random population in Spain and its impact on quality of life and functionality.

The aim of this study was to determine the prevalence of Hallux valgus (HV) and the association between the presence thereof and quality of life, dependence for basic and instrumental activities of daily living and foot function. Prevalence study was carried out in a random population sample (n = 1837) (α = 0.05; Precision = ±2.2%). Informed consent and ethical review board were obtained (code 2008/264). We studied anthropometric variables, Charlson Comorbidity Index, function and state of foot [Foot Function index (FFI), Foot Health Status Questionnaire (FHSQ)], quality of life (SF-36), and dependence for activities of daily living (Barthel and Lawton index). Degree of HV was determined using Manchester scale. Descriptive and multivariate logistic regression analyses were performed. Hence, the prevalence of HV is 39%. Patients with HV are significantly older (64.6 ± 11.7 vs 60.1 ± 12.6 years old). HV prevalence is greater in females (48.1 vs. 28.3%), subjects with flat foot (48.1 vs. 36.1%) or hammer toes (48.2 vs. 30.9%). Moreover, with regard to the presence or not of HV, statistically significant differences were neither noted in the SF-36 questionnaire nor in the Barthel and Lawton Index. For FHSQ and FFI questionnaires, significant differences were observed between patients who presented HV and those who did not. HV is associated with age, gender, flat foot and hammer toes. The SF-36 and Barthel and Lawton questionnaires remained unaltered by the presence of HV. The presence of Hallux valgus was associated with reduced quality of life and increases foot pain, disability and functional limitation.

Flat Foot in a Random Population and its Impact on Quality of Life and Functionality.

INTRODUCTION: Flat foot is a common deformity in adults. It is characterized by medial rotation and plantar flexion of the talus, eversion of the calcaneus, collapsed medial arch and abduction of the forefoot. AIM: The aim of this study was to determine the prevalence of flat foot and its impact on quality of life, dependence, foot pain, disability and functional limitation among random population of 40-year-old and above. MATERIALS AND METHODS: A cross-sectional study in a random population sample from Cambre (A Coruña-Spain) (n=835) was performed (α =0.05; Precision=±3.4%). The diagnosis of flat foot was stablished by the study of the footprint obtained with a pedograph. Anthropometric variables were studied, Charlson's Comorbidity Index, function and state of foot (Foot Function Index (FFI), Foot Health Status Questionnaire (FHSQ)), quality of life (SF-36), and dependence for activities of daily living (Barthel and Lawton index). A logistic and linear multiple regression analysis was performed. RESULTS: The prevalence of flat foot was 26.62%. Patients with flat foot were significantly older (65.73±11.04 vs 61.03±11.45-year-old), showed a higher comorbidity index (0.92±1.49 vs 0.50±0.98), had a greater BMI (31.45±5.55 vs 28.40±4.17) and greater foot size (25.16±1.66 vs 24.82±1.65). The presence of flat foot diminishes the quality of life, as measured by the FHSQ, and foot function, measured by the FFI. The presence of flat foot does not alter the physical and mental dimension of the SF-36 or the degree of dependence. CONCLUSION: Flat foot was associated with age, Charlson's Comorbidity Index, BMI and foot size. The SF-36, Barthel and Lawton questionnaires remained unaltered by the presence of flat foot. The FHSQ and FFI questionnaires did prove to be sensitive to the presence of flat foot in a significant manner.

Podiatric medical abnormalities in a random population sample 40 years or older in Spain.

BACKGROUND: Podiatric medical abnormalities are highly prevalent, yet few random population studies exist that determine the presence of pathologic abnormalities in the feet, despite their importance. The aim of this study was to determine the prevalence of podiatric medical abnormalities in a random sample population 40 years or older. METHODS: An observational study was conducted of a random sample population (n = 1,002) located in A Coruña, Spain. Anthropometric variables, comorbidity (Charlson score), quality of life (36-item Short-Form Health Survey), and podiatric medical examination findings were studied. A descriptive analysis and multivariate logistic regression were performed. RESULTS: The most common diseases were claw toes (69.7%), hallux valgus (38%), and hallux extensus (15.8%), which increased with age and female sex. The most frequent metatarsal formula was index minus (40.9%), followed by index plus minus (35.0%). The most frequent digital formula was Egyptian foot (57.1%), followed by Greek foot (31.4%). In this study, although the presence of podiatric medical abnormalities reduced the probability of enjoying a better quality of life, it did not do so significantly. After taking into account age, sex, comorbidity, body mass index (BMI), and the presence of podiatric medical abnormalities, the variables with an independent effect that modified the physical component of quality of life were sex (female), comorbidity, and BMI. CONCLUSIONS: There was a high prevalence of podiatric medical abnormalities, which increased with age and female sex. Comorbidity, BMI, and sex modified quality of life independently of podiatric medical abnormalities.