Significantly Enhanced Thermal Conductivity of hBN/PTFE Composites: A Comprehensive Study of Filler Size and Dispersion.

High-temperature polymers are attractive for applications in extreme temperatures, where they maintain their mechanical flexibility and electrical insulating properties. However, their heat dissipation capability is limited due to their intrinsically low thermal conductivities. Hexagonal boron nitride (hBN) is a chemically inert, thermally stable, and electrically insulative compound with a high thermal conductivity, making it an ideal candidate as a filler within a high-temperature polymer matrix to increase the thermal conductivity. This study evaluates the effect of filler size and dispersion on thermal conductivity by producing homogeneous composite samples using a combination of solvent mixing and resonant acoustic mixing (RAM). We carefully characterized our samples, including the spread of the size distribution, and observed that the smaller sized hBN centered around 5 µm was able to integrate more seamlessly into the polytetrafluoroethylene (PTFE) matrix with particle size in the 15 µm range and hence outperformed 30 µm, in contrast to the conventional wisdom, which asserts that larger fillers universally perform better than smaller ones. Our thermal conductivity of hBN/PTFE composites at 30 wt % is 2× higher than the literature values. Notably, we reached the record-high value of 3.5 W/m K at 40 wt % with an onset of percolation at 20 wt %, attributed to optimized hBN dispersion that facilitates the formation of thermal percolation. Our findings provide general guidelines to enhance the thermal conductivity of polymer composites for thermal management, ranging from power transmission to microelectronics cooling.

Effect of high cyclic hydrostatic pressure on osteogenesis of mesenchymal stem cells cultured in liquefied micro-compartments.

Bone resident cells are constantly subjected to a range of distinct mechanical loadings, which generates a complex microenvironment. In particular, hydrostatic pressure (HP) has a key impact on modulation of cell function and fate determination. Although HP is a constant mechanical stimulus, its role in regulating the osteogenesis process within a defined 3D microenvironment has not been comprehensively elucidated. Perceiving how environmental factors regulate the differentiation of stem cells is essential for expanding their regenerative potential. Inspired by the mechanical environment of bone, this study attempted to investigate the influence of different ranges of cyclic HP on human adipose-derived mesenchymal stem cells (MSCs) encapsulated within a compartmentalized liquefied microenvironment. Taking advantage of the liquefied environment of microcapsules, MSCs were exposed to cyclic HP of 5 or 50 MPa, 3 times/week at 37 °C. Biological tests using fluorescence staining of F-actin filaments showed a noticeable improvement in cell-cell interactions and cellular network formation of MSCs. These observations were more pronounced in osteogenic (OST) condition, as confirmed by fluorescent staining of vinculin. More interestingly, there was a significant increase in alkaline phosphatase activity of MSCs exposed to 50 MPa magnitude of HP, even in the absence of osteoinductive factors. In addition, a greater staining area of both osteopontin and hydroxyapatite was detected in the 50 MPa/OST group. These findings highlight the benefit of hydrostatic pressure to regulate osteogenesis of MSCs as well as the importance of employing simultaneous biochemical and mechanical stimulation to accelerate the osteogenic potential of MSCs for biomedical purposes.

Emerging modulators for osteogenic differentiation: a combination of chemical and topographical cues for bone microenvironment engineering.

Bone presents an intrinsic ability for self-regeneration and repair, however critical defects and large fractures require invasive and time-consuming clinical interventions. As an alternative to current therapy, bone tissue engineering (BTE) has primarily aimed to recreate the bone microenvironment by delivering key biomolecules and/or by modification of scaffolds to guide cell fate towards the osteogenic lineage or other phenotypes that may benefit the bone regeneration mechanism. Considering that bone cells communicate, in their native microenvironment, through biochemical and physical signals, most strategies fail when considering only chemical, geometrical or mechanical cues. This is not representative of the physiological conditions, where the cells are simultaneously in contact and stimulated by several cues. Therefore, this review explores the synergistic effect of biochemical/physical cues in regulating cellular events, namely cell adhesion, proliferation, osteogenic differentiation, and mineralization, highlighting the importance of the combined modifications for the development of innovative bone regenerative therapies.

Evaluación de la producción científica de las revistas del área de la salud existentes en la región caribe colombiana indexadas en Publindex -Colciencias, Colombia, 2010 - 2015 / Evaluation of scientific production of Journal existing area of Health in the Colombian Caribbean region, indexed in Publindex -Colciencias, Colombia, 2010-2015

Resumen Evaluar la producción científica de las revistas del área de la salud existentes en la región Caribe colombiana en el periodo 2010 - 2015 indexadas en Publindex - Colciencias, actualización 2014-2. A través de un análisis bibliométrico de carácter retrospectivo y descriptivo se hizo la revisión de artículos publicados en las revistas Ciencia y Salud Virtual, Ciencias Biomédicas, Dua%ary, Psicogente, Psicología desde el Caribe y Salud Uninorte. Lo anterior permitió encontrar para el total de las revistas: 75 ediciones, 631 manuscritos, 2117 autores y 221 instituciones; así mismo, se pudo registrar que tres de esas publicaciones disminuyeron su periodicidad en los últimos cinco años. Los resultados obtenidos en este estudio coinciden con la clasificación otorgada a cada una de las revistas por Publindex-Colciencias 2014-2, y se revalida con la mayor participación de países e instituciones de afiliación.

Abstract To evaluate the scientific production of health journals in the Colombian Caribbean region in the period 2010-2015, indexed in Publindex - Colciencias, update 2014-2. Through a bibliometric, analysis of a retrospective and descriptive character was made the review of articles published in the journals: Science and Virtual Health, Biomedical Sciences, Duazary, Psychogenic, Psychology from the Caribbean and Health Uninorte. The total number of journals was 75 editions, 631 manuscripts, 2117 authors and 221 institutions, as well as the fact that three of these journals decreased in the last five years. The results obtained in the study coincide with the classification given to each of the journals by Publindex-Colciencias 2014-2 and is revalidated with the greater participation of countries and affiliation institutions.

Mensuração e classificação dos tecidos moles: revisão de literatura e aplicação clínica / Measurement and classification of soft tissues: literature review and clinical application

A papila interdental e o comportamento dos tecidos moles peri-implantares são considerados um ponto crítico para o sucesso estético em osseointegração e geralmente apresenta-se como um desafio clínico. O presente artigo tem o objetivo de revisar as classificações propostas na literatura em relação ao comportamento do tecido gengival e perimplantar. Foi realizada uma pesquisa no banco de dados Medline entre 1985 a 2005, tendo sido selecionados 8 artigos. Os métodos foram aplicados e comparados destacando suas vantagens e desvantagens no uso clínico. Os métodos descritos são específicos e com finalidades distintas. Os métodos são eficazes, visto que todos possibilitam uma medida fácil e prática dos tecidos, podendo comparar o início e o fim do tratamento, além de uma melhor comunicação entre os clínicos.

The interdental papilla and the behavior of soft peri-implant tissues are considered a critical point for the aesthetic success in osseointegration and generally it is presented as a clinical challenge. The present article has the objective to revise the classifications proposals in literature in relation to the behavior of the gingival and to peri-implant tissues. A Medline research was made between 1985 and 2005, and 8 articles were selected. All the methods had been evaluated through a comparative analysis detaching its advantages and disadvantages in the clinical use. The methods described are specific with different purposes. All the methods are efficient (for distinct ends) when are carried through correctly, since all make possible an easy and practical measure of papilla, being able to compare the beginning and end of the treatment beyond one better communication between the clinical.