Controlled assembly and reduction of graphene oxide networks for conductive composites

Work presented at the 2019 ACS Spring National Meeting, March 28-April 4, 2019 · Orlando, FL.Graphene has attracted enormous interest in the scientific community as the first 2D material with exceptional mechanical, electronic and thermal properties. Pristine Graphene is notoriously difficult to process for macroscale applications, to overcome this many people use graphene oxide (GO) instead. GO is water soluble and easily functionalised and so can be simply processed into various systems. GO lacks the exceptional electronic properties of graphene due to structural disorder, therefore an important area of research is on the reduction of GO, which partly restores the structure and properties of graphene. Various techniques have been developed to perform the reduction step. We report a simple approach for preparing conductive Polymer Latex-rGO composites by using a latex-assembly method. After a treatment in the oven at low T, we can reduce the GO in situ. We make use of the inherent GO properties to optimise the aqueous composite fabrication, which is scalable and adaptable, and then restore conductivity with a simple, low temperature, heating step; opening up pathways to tunable electronic composite materials on a large scale.Peer reviewe

Explosive percolation yields highly-conductive polymer nanocomposites

Explosive percolation is an experimentally-elusive phenomenon where network connectivity coincides with onset of an additional modification of the system; materials with correlated localisation of percolating particles and emergent conductive paths can realise sharp transitions and high conductivities characteristic of the explosively-grown network. Nanocomposites present a structurally- and chemically-varied playground to realise explosive percolation in practically-applicable systems but this is yet to be exploited by design. Herein, we demonstrate composites of graphene oxide and synthetic polymer latex which form segregated networks, leading to low percolation threshold and localisation of conductive pathways. In situ reduction of the graphene oxide at temperatures of <150 °C drives chemical modification of the polymer matrix to produce species with phenolic groups, which are known crosslinking agents. This leads to conductivities exceeding those of dense-packed networks of reduced graphene oxide, illustrating the potential of explosive percolation by design to realise low-loading composites with dramatically-enhanced electrical transport properties

Percolating metallic structures templated on laser-deposited carbon nanofoams derived from graphene oxide: applications in humidity sensing

Carbon nanofoam (CNF) is a low-density, high-surface-area material formed by aggregation of amorphous carbon nanoparticles into porous nanostructures. We report the use of a pulsed infrared laser to prepare CNF from a graphene oxide (GO) target material. Electron microscopy shows that the films consist of dendritic strings that form web-like three-dimensional structures. The conductivity of these structures can be modified by using the CNF as a nanostructured scaffold for gold nanoparticles deposited by sputter coating, controllably increasing the conductivity by up to 4 orders of magnitude. The ability to measure the conductivity of the porous structures allows electrochemical measurements in the environment. Upon decreasing humidity, the pristine CNF exhibits an increase in resistance with a quick response and recovery time. By contrast, the gold-sputtered CNF showed a decrease in resistance, indicating modification of the doping mechanism due to water adsorption. The sensitivity to humidity is eliminated at the percolation threshold of the metal on the CNF

Predictors of Hospitalized Exacerbations and Mortality in Chronic Obstructive Pulmonary Disease

Background and Aim Exacerbations of chronic obstructive pulmonary disease (COPD) carry significant consequences for patients and are responsible for considerable health-care costs?particularly if hospitalization is required. Despite the importance of hospitalized exacerbations, relatively little is known about their determinants. This study aimed to analyze predictors of hospitalized exacerbations and mortality in COPD patients. Methods This was a retrospective population-based cohort study.We selected 900 patients with confirmed COPD aged 35 years by simple random sampling among all COPD patients in Cantabria (northern Spain) on December 31, 2011. We defined moderate exacerbations as events that led a care provider to prescribe antibiotics or corticosteroids and severe exacerbations as exacerbations requiring hospital admission.We observed exacerbation frequency over the previous year (2011) and following year (2012). We categorized patients according to COPD severity based on forced expiratory volume in 1 second (Global Initiative for Chronic Obstructive Lung Disease [GOLD] grades 1?4). We estimated the odds ratios (ORs) by logistic regression, adjusting for age, sex, smoking status, COPD severity, and frequent exacerbator phenotype the previous year. Results Of the patients, 16.4%had 1 severe exacerbations, varying from 9.3%in mild GOLD grade 1 to 44%in very severe COPD patients. A history of at least two prior severe exacerbations was positively associated with new severe exacerbations (adjusted OR, 6.73; 95%confidence interval [CI], 3.53?12.83) and mortality (adjusted OR, 7.63; 95%CI, 3.41?17.05). Older age and several comorbidities, such as heart failure and diabetes, were similarly associated. Conclusions Hospitalized exacerbations occurred with all grades of airflow limitation. A history of severe exacerbations was associated with new hospitalized exacerbations and mortality

Aprendiendo a criar mariposas : desarrollo de zoocriaderos de mariposas en comunidades indígenas. Asociación de comunidades unidas de los ríos Isana y Surubí (ACURIS), Vaupés

Se describe el trabajo desarrollado en el marco de acciones del convenio SENA-Tropenbos y la fundación Gaia Amazonas para la construcción de mariposarios, se describen generalidades de las mariposas, familias de mariposas, marco normativo sobre zoocría de mariposas y aspectos técnicos asociados a construcción de mariposariosThe work developed in the framework of actions of the SENA-Tropenbos agreement and the Gaia Amazonas foundation for the construction of butterfly farms, generalities of butterflies, butterfly families, normative framework on butterfly farming and technical aspects associated with the construction of butterflyIntroducción – Capacitación: conociendo las generalidades de las mariposas -- Familias de mariposas -- Construcción de los mariposarios -- Marco normativo sobre zoocría de mariposas -- Investigación local de Julio López en Puerto Arenal: construcción de los mariposarios -- Investigación local de mariposas -- Proyecciones -- Investigación local de Tito Hernández en la Comunidad de Camanaos: construcción de los mariposarios -- Investigación local de las mariposas -- Variedad de mariposas -- Proyecciones -- Conclusiónna40 página

Crude and adjusted odds ratios (ORs) according to previous exacerbations for the risk of hospitalized exacerbations and mortality the following year.

<p>Crude and adjusted odds ratios (ORs) according to previous exacerbations for the risk of hospitalized exacerbations and mortality the following year.</p

Crude and adjusted odds ratios (ORs) according to comorbidities for the risk of hospitalized exacerbations and mortality the following year.

<p>Crude and adjusted odds ratios (ORs) according to comorbidities for the risk of hospitalized exacerbations and mortality the following year.</p

Baseline sociodemographic, lifestyle, and clinical characteristics of the patients.

<p>Baseline sociodemographic, lifestyle, and clinical characteristics of the patients.</p

Comparison of adherence as assessed by the Test of Adherence to Inhalers and Pharmacy Refill Records, in Asthma Patients. REFARMA study

Introducción Las guías recomiendan el uso combinado del Test de Adherencia a Inhaladores (TAI) y el «% de fármaco retirado con respecto al prescrito (PRR)» para determinar la adhesión terapéutica, pero la evidencia basada en estudios comparativos es limitada. Nuestro objetivo fue determinar el nivel de adhesión mediante el TAI y PRR, así como el grado de correlación y concordancia entre ambos métodos. Métodos Estudio transversal multicéntrico, en el que se incluyeron los primeros 196 pacientes asmáticos adultos consecutivos, de los cuales 183 estaban en tratamiento de mantenimiento con glucocorticoides inhalados (GCI). Se definió «noadherencia» como un TAI < 50 o un PRR < 80% en los 12 meses previos. Resultados Se observó una correlación positiva estadísticamente significativa entre el TAI y el PRR (rho de Spearman = 0,185; p = 0,012). La prevalencia de noadherencia según el TAI fue del 73,22%; IC95% (66,54-79,91) y según el PRR fue del 57,92%; IC95% (50,50-65,35). Se obtuvo un índice kappa = 0,174 y un % de acuerdo global del 61,7%. De los 49 pacientes con máxima puntuación en el TAI (44,9%), 22 retiraron < 80% de los inhaladores. Por el contrario, 48 de los 134 pacientes que puntuaron ≤ 49 en el TAI (35,8%), retiraron ≥ 80% en farmacia. Conclusiones La adherencia sigue siendo subóptima con prevalencias de noadherencia mayores al 50%. Nuestros resultados sugieren, en consonancia con las recomendaciones de las guías, que el uso de ambos abordajes (TAI y PRR) incrementa la capacidad para identificar la baja adherencia terapéutica, comparada con la del TAI o el PRR por separado.Introduction Clinical guidelines recommend the combined use of "self-completed questionnaires such as the Test of Adherence to Inhalers (TAI)" and the pharmacy refill rate (PRR) to determine adherence, but evidence based on comparative studies to support these recommendations is limited. Our objective was to determine adherence to inhalers in asthmatic patients, using the TAI and the PRR, as well as the correlation and concordance between both methods. Methods Multicentre cross-sectional study including the first 196 consecutive adult asthmatic patients, of whom 183 were on maintenance treatment with Inhaled Corticosteroids (ICS). Nonadherence was defined as TAI < 50 or PRR < 80% in the previous 12 months. Results A statistically significant positive correlation was observed between TAI and PRR scores (Spearman's rho coefficient = 0.185; p = 0.012). Prevalence of nonadherence based on TAI was 73.22%; 95%CI (66.54-79.91) and 57.92%; 95%CI (50.50-65.35) based on PRR was. In terms of agreement, a Cohen's kappa index = 0.174 and an overall % agreement of 61.7% were obtained. Twenty-two of the 49 patients who scored 50 on TAI (44.9%) refilled < 80% of inhalers. In contrast, 48 of the 134 patients who scored ≤ 49 on TAI (35.8%) refilled ≥ 80% at the pharmacy. Conclusions Adherence remains suboptimal with prevalences of nonadherent patients > 50%. The concordance results supports, in line with guideline recommendations, that the use of both approaches (TAI and PRR) increases the ability to identify poor adherence compared to TAI or PRR alone.El estudio REFARMA ha sido financiado parcialmente por TEVA Respiratory (España) a través de la Asociación Cántabra de Investigación en Aparato Respiratorio (ACINAR). El patrocinador no tuvo ningún papel en el diseño de este estudio, ni en los análisis, la interpretación de los datos o la decisión de presentar los resultados