Anisotropy in nanocellular polymers promoted by the addition of needle‐like sepiolites

This work presents a new strategy for obtaining nanocellular materials with high anisotropy ratios by means of the addition of needle‐like nanoparticles. Nanocellular polymers are of great interest due to their outstanding properties, whereas anisotropic structures allow the realization of improved thermal and mechanical properties in certain directions. Nanocomposites based on poly(methyl methacrylate) (PMMA) with nanometric sepiolites are generated by extrusion. From the extruded filaments, cellular materials are produced using a two‐step gas dissolution foaming method. The effect of adding various types and contents of sepiolites is investigated. As a result of the extrusion process, the needle‐like sepiolites are aligned in the machine direction in the solid nanocomposites. Regarding the cellular materials, the addition of sepiolites allows one to obtain anisotropic nanocellular polymers with cell sizes of 150 to 420 nm and cell nucleation densities of 1013–1014 nuclei cm−3 and presenting anisotropy ratios ranging from 1.38 to 2.15, the extrusion direction being the direction of the anisotropy. To explain the appearance of anisotropy, a mechanism based on cell coalescence is proposed and discussed. In addition, it is shown that it is possible to control the anisotropy ratio of the PMMA/sepiolite nanocellular polymers by changing the amount of well‐dispersed sepiolites in the solid nanocomposites

Light transmission in nanocellular polymers: Are semi-transparent cellular polymers possible?

This work presents the light transmission through a collection of solid cellular polymers based on poly (methyl methacrylate) (PMMA) with cells sizes covering the micro and nano-scale. The obtained results showed that the behavior of light transmission when cell size is in the nano-scale is opposite to the one shown by microcellular foams or the one predicted by theoretical models of light scattering (LS). In fact, the expected trend is that a reduction of cell size increases the opacity of the samples. However, for nanocellular polymers based on amorphous polymers reducing the cell size increases the light transmission. Therefore, this result indicates that a further reduction of the cell size could result in cellular polymers optically semi-transparen

Quasiparticle energies for large molecules: a tight-binding GW approach

We present a tight-binding based GW approach for the calculation of quasiparticle energy levels in confined systems such as molecules. Key quantities in the GW formalism like the microscopic dielectric function or the screened Coulomb interaction are expressed in a minimal basis of spherically averaged atomic orbitals. All necessary integrals are either precalculated or approximated without resorting to empirical data. The method is validated against first principles results for benzene and anthracene, where good agreement is found for levels close to the frontier orbitals. Further, the size dependence of the quasiparticle gap is studied for conformers of the polyacenes ($C_{4n+2}H_{2n+4}$) up to n = 30.Comment: 10 pages, 5 eps figures submitted to Phys. Rev.

Convergent validity of two items to differentiate between active and sedentary students

Este estudio examina la validez y fiabilidad de dos ítems de actividad física (AF) incluidos en el CHIP-CE para discriminar entre escolares activos y sedentarios. Se realizó un estudio observacional-transversal, con 1.073 escolares de ambos sexos, de 10-13 años. Mediante los ítems 13 y 28 del CHIP-CE se clasificó a los escolares como activos o sedentarios. La validez convergente fue examinada utilizando como criterio variables de adiposidad, lipídicas, metabólicas, de presión arterial y de fitness. El coeficiente de correlación de Spearman entre los dos ítems fue de 0,60. Los coeficientes de correlación de Spearman entre la media de los dos items de AF y las variables de salud mostraron valores más altos con el % grasa corporal, la insulina basal, la frecuencia cardiaca de recuperación y el fitness. La escala de dos ítems extraída del CHIP-CE es un instrumento válido para clasificar a los escolares en activos o sedentarios.This study examined the validity and reliability of two physical activity Child Health and Illness Profile - Child Edition (CHIP-CE) items to differentiate between active and sedentary students. An observational cross-sectional study design was used with 1,073 students from 11 to 13 years old, from 20 schools in the province of Cuenca (Spain). Item 13 and item 28 of the CHIP-CE, a generic childhood quality of life instrument, were evaluated. Convergent validity was examined using adiposity, lipidic, metabolic, blood pressure and cardiorespiratory fitness variables as criteria. The Spearman coefficient of correlation between the two items was 0.60. The Spearman correlation coefficients between the physical activity items and the anthropometric, lipidic, metabolic, blood pressure and cardiorespiratory fitness variables showed higher values with percentage body fat, fasting insulin, recovery heart rate and cardiorespiratory fitness. Our two-item questionnaire exhibited acceptable validity and high internal consistency for classifying students as either active or sedentary.Este estudio fue financiado por la Consejería de Sanidad de Castilla-La Mancha (beca GC03060-00). Financiación adicional fue obtenida del Ministerio de Sanidad y Consumo, Instituto de Salud Carlos III, Red de Investigación en Actividades Preventivas y de Promoción de Salud (grant RD06/0018/0038)

Physical activity and bone health in schoolchildren: the mediating role of fitness and body fat

This is the final version of the article. Available from Public Library of Science via the DOI in this record.BACKGROUND: The relationship between physical activity (PA) and bone health is well known, although the role of percent body fat (%BF) and fitness as confounders or mediators in this relationship remains uncertain. OBJECTIVE: To examine whether the association between PA and bone mineral content (BMC) is mediated by %BF and cardiorespiratory fitness (CRF). METHODS: In this cross sectional study, BMC, total %BF (by DXA), vigorous PA (VPA), CRF, age and height were measured in 132 schoolchildren (62 boys, aged 8-11 years). ANCOVA was used to test differences in BMC by %BF, CRF and VPA, controlling for different sets of confounders. Simple mediation analyses and serial multiple mediation analyses were fitted to examine whether the relationship between PA and BMC is mediated by %BF and fitness. RESULTS: Children with high %BF had higher total body BMC than their peers after controlling for all sets of confounders. Children with good CRF or VPA had significantly less total body BMC after controlling for age and sex but in children with good CRF this inverse relation disappeared after adjusting by %BF. %BF and CRF both act as a full mediator in the association between VPA and BMC, after inclusion of the potential confounders in the models. CONCLUSION: Fitness and %BF seem to have a mediator role on the relationship between physical activity and bone mass.This study was funded by grant numbers PII1I09-0259-9898 and POII10-0208-5325 from the Ministry of Education and Science - Junta de Comunidades de Castilla-La Mancha, and Ministry of Health (FIS grant number PI081297). Additional funding was provided by the Research Network on Preventative Activities and Health Promotion (RD06/0018/0038)

Simbiótico conteniendo bacillus coagulans LMG-S-24828 y prebióticos en la reducción de trastornos gastrointestinales secundarios al tratamiento farmacológico de enfermedades hematológicas crónicas. Estudio piloto

Poster [PC-353] Introducción: Algunos fármacos inhibidores de Tirosin-kinasa (ITK) utilizados en el tratamiento de la leucemia mieloide crónica, y Miglustat, un iminoazúcar empleado en enfermedades lisosomales, pueden producir trastornos gastrointestinales como diarrea, meteorismo y dolor abdominal. Estos efectos adversos disminuyen la calidad de vida relacionada con la salud y provocan abandonos del tratamiento. Algunos probióticos han demostrado mejoría de los síntomas mencionados en pacientes con trastornos funcionales digestivos. Hipótesis: El simbiótico conteniendo Bacillus coagulans LMG-S-24828 y prebióticos reduce los efectos adversos gastrointestinales asociados a la utilización de ITKs y Miglustat y mejora la adherencia al tratamiento. Objetivos: Evaluar el efecto de la administración controlada de dicho simbiótico durante un mes, sobre la calidad de vida relacionada con la salud gastrointestinal en pacientes tratados con ITKs y miglustat. Secundariamente, establecer si el simbiótico aporta ventajas en la adherencia a los tratamientos citados. Métodos: Ensayo clínico aleatorizado de diseño cruzado en el que a 9 pacientes en tratamiento con ITKs o Miglustat se les administró de forma ciega placebo o simbiótico en una dosis diaria, con una fase de “lavado” de dos meses entre la administración de cada uno. Se solicitó al paciente cumplimentar la versión validada en español del cuestionario de Calidad de Vida Gastrointestinal GIQLI (Gastrointestinal Quality of Life Index) antes de la primera dosis de cada producto y trascurrido un mes desde su inicio. Se evaluó la frecuencia de abandono del tratamiento en cada grupo. El análisis de los resultados se realizó por protocolo mediante el test no paramétrico de Mann-Whitney, considerando significación estadística las diferencias con p valor<0, 05. El protocolo fue aprobado por el Comité de Ética autonómico. Resultados: Inicialmente se reclutaron 11 pacientes procedentes de un único centro, de los que 9 (5 H/ 4M), edad media: 49 (29-79) finalizaron el estudio. Tras un mes en tratamiento con simbiótico observamos una diferencia estadísticamente significativa (p=0, 039) en la puntuación media del cuestionario GIQLI no alcanzada con placebo. Ningún paciente abandonó el tratamiento con ITKs/Miglustat, ni se observaron variaciones analíticas en los biomarcadores de la enfermedad. Conclusiones: En pacientes bajo tratamiento con ITKs o Miglustat el simbiótico mejoró significativamente los síntomas adversos gastrointestinales. Este beneficio no fue observado con placebo y no se relacionó con el grado de adherencia terapéutica

Accurate detection and quantification of SARS-CoV-2 genomic and subgenomic mRNAs by ddPCR and meta-transcriptomics analysis

SARS-CoV-2 replication requires the synthesis of a set of structural proteins expressed through discontinuous transcription of ten subgenomic mRNAs (sgmRNAs). Here, we have fine-tuned droplet digital PCR (ddPCR) assays to accurately detect and quantify SARS-CoV-2 genomic ORF1ab and sgmRNAs for the nucleocapsid (N) and spike (S) proteins. We analyzed 166 RNA samples from anonymized SARS-CoV-2 positive subjects and we observed a recurrent and characteristic pattern of sgmRNAs expression in relation to the total viral RNA content. Additionally, expression profiles of sgmRNAs, as determined by meta-transcriptomics sequencing of a subset of 110 RNA samples, were highly correlated with those obtained by ddPCR. By providing a comprehensive and dynamic snapshot of the levels of SARS-CoV-2 sgmRNAs in infected individuals, our results may contribute a better understanding of the dynamics of transcription and expression of the genome of SARS-CoV-2 and facilitate the development of more accurate molecular diagnostic tools for the stratification of COVID-19 patients

Un simbiótico conteniendo bacillus coagulans LMG-S-24828 reduce los síntomas gastrointestinales secundarios al tratamiento farmacológico de enfermedades hematológicas crónicas. Estudio multicéntrico

PB-062 Introducción: La presencia de blastos permite diagnosticar, en muchas ocasiones, una neoplasia hematológica dentro de un amplio abanico de posibilidades diagnósticas, siendo el ejemplo clásico el de las leucemias agudas. Además, apoyando al examen morfológico, la citometría de flujo es de gran utilidad para el diagnóstico y la clasificación de estas neoplasias. Existen otras enfermedades no neoplásicas que se manifiestan con células inmaduras, por ello presentamos el caso de una lactante de 19 meses con hepatoesplenomegalia, presencia de blastos con diagnóstico inicial de leucemia aguda que no se confirma tras un estudio completo. Métodos y Resultados: Presentamos una lactante de 19 meses que acude por fiebre de 15 días de predominio nocturno, máximo 39,5ºC, distensión abdominal y desde dos semanas antes de ingreso coincidiendo con reinicio de fiebre, mayor aumento del perímetro abdominal. Se realiza ecografía abdominal con esplenomegalia de 10,7 cm, bazo accesorio de 1,6x1,5 cm. A la exploración se objetiva palidez cutánea, abdomen distendido, no doloroso y marcada hepatoesplenomegalia. ..

Mechanical Properties of PMMA-Sepiolite Nanocellular Materials with a Bimodal Cellular Structure

Bimodal cellular poly(methyl methacrylate) with micron and nano sized (300 to 500 nm) cells with up to 5 weight percent of sepiolite nanoparticles and porosity from 50 weight percent to 75 weight percent are produced by solid state foaming. Uniaxial compression tests are performed to measure the effect of sepiolite concentration on the elastic modulus and the yield strength of the solid and cellular nanocomposites. Single edge notch bend tests are conducted to relate the fracture toughness of the solid and cellular nanocomposites to sepiolite concentration. The relative modulus is independent of sepiolite content to within material scatter when considering the complete porosity range. In contrast, a mild enhancement of the relative modulus is observed by the addition of sepiolite particles for the foamed nanocomposites with a porosity close to 50 percent. The relative compressive strength of the cellular nanocomposites mildly decreases as a function of sepiolite concentration. A strong enhancement of the relative fracture toughness by the addition of sepiolites is observed. The enhancement of the relative fracture toughness and the relative modulus (at 50 percent porosity) can be attributed to an improved dispersion of the particles due to foaming and the migration of micron sized aggregates from the solid phase to the microcellular pores during foaming

Temperature Dependent Zero-Field Splittings in Graphene

Graphene is a quantum spin Hall insulator with a 45 $\mu$eV wide non-trivial topological gap induced by the intrinsic spin-orbit coupling. Even though this zero-field spin splitting is weak, it makes graphene an attractive candidate for applications in quantum technologies, given the resulting long spin relaxation time. On the other side, the staggered sub-lattice potential, resulting from the coupling of graphene with its boron nitride substrate, compensates intrinsic spin-orbit coupling and decreases the non-trivial topological gap, which may lead to the phase transition into trivial band insulator state. In this work, we present extensive experimental studies of the zero-field splittings in monolayer and bilayer graphene in a temperature range 2K-12K by means of sub-Terahertz photoconductivity-based electron spin resonance technique. Surprisingly, we observe a decrease of the spin splittings with increasing temperature. We discuss the origin of this phenomenon by considering possible physical mechanisms likely to induce a temperature dependence of the spin-orbit coupling. These include the difference in the expansion coefficients between the graphene and the boron nitride substrate or the metal contacts, the electron-phonon interactions, and the presence of a magnetic order at low temperature. Our experimental observation expands knowledge about the non-trivial topological gap in graphene.Comment: Main text with figures (20 pages) and Supplementary Information (14 pages) Accepted in Phys. Rev.