3D simulation of conductive nanofilaments in multilayer h-BN memristors via a circuit breaker approach.

A 3D simulation of conductive nanofilaments (CNFs) in multilayer hexagonal-BN memristors is performed. To do so, a simulation tool based on circuit breakers is developed including for the first time a 3D resistive network. The circuit breakers employed can be modeled with two, three and four resistance states; in addition, a series resistance and a module to account for quantum effects, by means of the quantum point contact model, are also included. Finally, to describe real dielectric situations, regions with a high defect density are modeled with a great variety of geometrical shapes to consider their influence in the resistive switching (RS) process. The simulator has been tuned with measurements of h-BN memristive devices, fabricated with chemical-vapour-deposition grown h-BN layers, which were electrically and physically characterized. We show the formation of CNFs that produce filamentary charge conduction in our devices. Moreover, the simulation tool is employed to describe partial filament rupture in reset processes and show the low dependence of the set voltage on the device area, which is seen experimentally.

Design and fabrication of CuInS2/ZnS-based QLED for automotive lighting systems.

This work reports the design, manufacturing and numerical simulation approach of a 6-pixel (4.5 mm2/pixel) electroluminescent quantum dot light emitting device (QLED) based on CuInS2/ZnS quantum dots as an active layer. The QLED device was fabricated using a conventional multi-layer thin film deposition. In addition, the electrical I-V curves were measured for each pixel independently, observing how the fabrication process and layer thickness have an influence in the shape of the plot. This experimental device, enabled us to create a computational model for the QLED based on the Transfer Hamiltonian approach to calculate the current density J (mA cm-2), the band diagram of the system, and the accumulated charge distribution. Besides, it is worth highlighting that the simulator allows the possibility to study the influence of different parameters of the QLED structure like the junction capacitance between the distinct multilayer set. Specifically, we found that the Anode-HIL interface capacitance has a greater influence in the I-V curve. This junction capacitance plays an important role in the current density increase and the QLED turn-on value when a forward voltage is applied to the device. The simulation enabled that influence could be controlled by the selection of the optimal thickness and transport layers during the experimental fabrication process. This work is remarkable since it achieves to fit simulation and experiment results in an accurate way for electroluminescent QLED devices; particularly the simulation of the device current, which is critical when designing the automotive electronics to control these new nanotechnology lighting devices in the future.

[Potential biomarkers predictors of mortality in COVID-19 patients in the Emergency Department]. / Potenciales biomarcadores predictores de mortalidad en pacientes COVID-19 en el Servicio de Urgencias.

OBJECTIVE: Identify which biomarkers performed in the first emergency analysis help to stratify COVID-19 patients according to mortality risk. METHODS: Observational, descriptive and cross-sectional study performed with data collected from patients with suspected COVID-19 in the Emergency Department from February 24 to March 16, 2020. The univariate and multivariate study was performed to find independent mortality markers and calculate risk by building a severity score. RESULTS: A total of 163 patients were included, of whom 33 died and 29 of them were positive for the COVID-19 PCR test. We obtained as possible factors to conform the Mortality Risk Score age> 75 years ((adjusted OR = 12,347, 95% CI: 4,138-36,845 p = 0.001), total leukocytes> 11,000 cells / mm3 (adjusted OR = 2,649, 95% CI: 0.879-7.981 p = 0.083), glucose> 126 mg / dL (adjusted OR = 3.716, 95% CI: 1.247-11.074 p = 0.018) and creatinine> 1.1 mg / dL (adjusted OR = 2.566, 95% CI: 0.889- 7.403, p = 0.081) This score was called COVEB (COVID, Age, Basic analytical profile) with an AUC 0.874 (95% CI: 0.816-0.933, p <0.001; Cut-off point = 1 (sensitivity = 89.66 % (95% CI: 72.6% -97.8%), specificity = 75.59% (95% CI: 67.2% -82.8%). A score <1 has a negative predictive value = 100% (95% CI: 93.51% -100%) and a positive predictive value = 18.59% (95% CI: 12.82% -25.59%). CONCLUSIONS: Clinical severity scales, kidney function biomarkers, white blood cell count parameters, the total neutrophils / total lymphocytes ratio and procalcitonin are early risk factors for mortality. The variables age, glucose, creatinine and total leukocytes stand out as the best predictors of mortality. A COVEB score <1 indicates with a 100% probability that the patient with suspected COVID-19 will not die in the next 30 days.

Band-like electron transport in 2D quantum dot periodic lattices: the effect of realistic size distributions.

Electron mobility in nanocrystal films has been a controversial topic in the last few years. Theoretical and experimental studies evidencing carrier transport by hopping or showing band-like features have been reported in the past. A relevant factor to analyze transport results is the progressive improvement in quantum dot superlattice fabrication, leading to better regimented structures for which band-like transport would be more relevant. This work presents an efficient model to compute temperature-dependent band-like electronic mobilities in 2D quantum dot arrays when a realistic quantum dot size distribution is considered. Comparisons with experimental results are used to estimate these size distributions, in good agreement with data of the samples.

Increasing phenolic and aromatic compounds extraction and maximizing liking of lemon verbena (Aloysia triphylla) infusions through the optimization of steeping temperature and time.

Herbal infusions are a new emerging trend among consumers, appearing in the market in many different forms. Due to intense competition, the commercial success of herbal infusions largely depends on flavour. The identification of the best combinations of steeping time and water temperature for the preparation of Aloysia triphylla infusions using a central composite design and response surface methodology was performed. The procedure aimed to maximize its antioxidant activity, phenolic and aromatic compounds, and consumers' liking of the infusions. The antioxidant activity and phenolic content were evaluated using the 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid radical cation) method and the Folin-Ciocalteu procedure. The analysis of aromatic compounds was performed based on the method of terpenic compounds. Sensory evaluation encompassed overall liking using a 9-point hedonic scale. Antioxidant activity and extraction of most phenolic compounds was higher for longer steeping times and higher temperatures, with some presenting a contrasting effect due to degradation at higher temperatures for longer steeping times. Results for terpenic compounds showed similar contrasting patterns. Based on the quadratic response surface, it was possible to predict the maximum overall liking for lemon verbena infusions prepared by brewing for 6 min at 96 ℃. Under such conditions, extraction of bioactive compounds was kept at a high level, close to the maximum attainable, while reducing the extraction of bitter compounds. These results are considered of great importance for the development of premium infusions from organic lemon verbena leaves.

Microparticles: Inflammatory and haemostatic biomarkers in Polycystic Ovary Syndrome.

Polycystic Ovary Syndrome (PCOS) is associated with a chronic low-grade inflammation and predisposition to hemostatic and atherosclerotic complications. This case-control study evaluated the microparticles (MPs) profile in patients with the PCOS and related these MPs to clinical and biochemical parameters. MPs derived from platelets (PMPs), leuckocytes (LMPs) and endothelial cells (EMPs) were evaluated, as well as MPs expressing tissue factor (TFMPs), by flow cytometry, comparing women with PCOS (n = 50) and a healthy control group (n = 50). PCOS women presented increased total MPs, PMPs, LMPs and EMPs levels when compared to control group (all p < 0.05). TFMPs was similar between the groups (p = 0.379). In conclusion, these MPs populations could be useful biomarkers for association with thrombosis and cardiovascular disease in PCOS women.

Wine phenolic compounds influence the production of volatile phenols by wine-related lactic acid bacteria.

AIMS: To evaluate the effect of wine phenolic compounds on the production of volatile phenols (4-vinylphenol [4VP] and 4-ethylphenol [4EP]) from the metabolism of p-coumaric acid by lactic acid bacteria (LAB). METHODS AND RESULTS: Lactobacillus plantarum, Lactobacillus collinoides and Pediococcus pentosaceus were grown in MRS medium supplemented with p-coumaric acid, in the presence of different phenolic compounds: nonflavonoids (hydroxycinnamic and benzoic acids) and flavonoids (flavonols and flavanols). The inducibility of the enzymes involved in the p-coumaric acid metabolism was studied in resting cells. The hydroxycinnamic acids tested stimulated the capacity of LAB to synthesize volatile phenols. Growth in the presence of hydroxycinnamic acids, especially caffeic acid, induced the production of 4VP by resting cells. The hydroxybenzoic acids did not significantly affect the behaviour of the studied strains. Some of the flavonoids showed an effect on the production of volatile phenols, although strongly dependent on the bacterial species. Relatively high concentrations (1 g l(-1) ) of tannins inhibited the synthesis of 4VP by Lact. plantarum. CONCLUSIONS: Hydroxycinnamic acids were the main compounds stimulating the production of volatile phenols by LAB. The results suggest that caffeic and ferulic acids induce the synthesis of the cinnamate decarboxylase involved in the metabolism of p-coumaric acid. On the other hand, tannins exert an inhibitory effect. SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlights the capacity of LAB to produce volatile phenols and that this activity is markedly influenced by the phenolic composition of the medium.

Cell membrane damage induced by phenolic acids on wine lactic acid bacteria.

The aim of this work was to investigate the effect of phenolic acids on cell membrane permeability of lactic acid bacteria from wine. Several phenolic acids were tested for their effects on the cell membrane of Oenococcus oeni and Lactobacillus hilgardii by measuring potassium and phosphate efflux, proton influx and by assessing culture viability employing a fluorescence technique based on membrane integrity. The experimental results indicate that hydroxycinnamic acids (p-coumaric, caffeic and ferulic acids) induce greater ion leakages and higher proton influx than hydroxybenzoic acids (p-hydroxibenzoic, protocatechuic, gallic, vanillic, and syringic acids). Among the hydroxycinnamic acids, p-coumaric acid showed the strongest effect. Moreover, the exposure of cells to phenolic acids caused a significant decrease in cell culture viability, as measured by the fluorescence assay, in both tested strains. The results agree with previous results obtained in growth experiments with the same strains. Generally, phenolic acids increased the cell membrane permeability in lactic acid bacteria from wine. The different effects of phenolic acids on membrane permeability could be related to differences in their structure and lipophilic character.

Influence of phenolic acids on growth and inactivation of Oenococcus oeni and Lactobacillus hilgardii.

AIMS: To determine the effect of several wine-associated, phenolic acids on the growth and viability of strains of Oenococcus oeni and Lactobacillus hilgardii. METHODS AND RESULTS: Growth was monitored in ethanol-containing medium supplemented with varying concentrations of hydroxybenzoic acids (p-hydroxybenzoic, protocatechuic, gallic, vanillic and syringic acids) and hydroxycinnamic acids (p-coumaric, caffeic and ferulic acids). Progressive inactivation was monitored in ethanol-containing phosphate buffer supplemented in a similar manner to the growth experiments. Hydroxycinnamic acids proved to be more inhibitory to the growth of O. oeni than hydroxybenzoic acids. On the other hand, some acids showed a beneficial effect on growth of Lact. hilgardii. p-Coumaric acid showed the strongest inhibitory effect on growth and survival of both bacteria. CONCLUSIONS: Most phenolic acids had a negative effect on growth of O. oeni, for Lact. hilgardii this effect was only noted for p-coumaric acid. Generally, O. oeni was more sensitive to phenolic acid inactivation than Lact. hilgardii. SIGNIFICANCE AND IMPACT OF THE STUDY: Eight wine-derived, phenolic acids were compared for their effects on wine lactic acid bacteria. Results indicate that phenolic acids have the capacity to influence growth and survival parameters. The differences found between phenolic compounds could be related to their different chemical structures.