Nanotailoring Stereolithography Resins for Unique Applications using Carbon Nanotubes

Nanostructured materials and exploiting their properties in stereolithography (SL) may open new markets for unique rapidly manufactured functional devices. Controlled amounts of multiwalled carbon nanotubes (MWCNTs) were successfully dispersed in SL epoxy-based resins and complex three-dimensional (3D) parts were successfully fabricated by means of a multi-material SL setup. The effect of the nanosized filler was evaluated using mechanical testing. Small dispersions of MWCNTs resulted in significant effects on the physical properties of the polymerized resin. A MWCNT concentration of .05 wt% (w/v) in DSM Somos® WaterShed™ 11120 resin increased the ultimate tensile stress and fracture stress an average of 17% and 37%, respectively. Electron microscopy was used to examine the morphology of the nanocomposite and results showed affinity between the MWCNTs and SL resin and identified buckled nanotubes that illustrated strong interfacial bonding. These improved physical properties may provide opportunities for using nanocomposite SL resins in end-use applications. Varying types and concentrations of nanomaterials can be used to tailor existing SL resins for particular applications.Mechanical Engineerin

Theotonio dos Santos (1936-2018), the revolutionary intellectual who pioneered dependency theory

This article analyzes the origins and development of the dependency theory through the life and work of Theotonio Dos Santos. His formative years at the academy and his early political activism in Brazil are examined, particularly, his time at the University of Brasilia with Vania Bambirra, Ruy Mauro Marini and André Gunder Frank ("the quartet"). This is followed by a discussion about their years of exile in Chile where the quartet regrouped at the Center for Socio-Economic Studies (ceso) of the University of Chile, and where they wrote their founding texts on dependency theory. Chile provided fertile ground for the development of this theory due to its intellectual climate, institutionality, and the country's political transformations in the late 1960s and early 1970s. The military overthrow of the Allende government on that fateful September 11th, 1973 forced the quartet once again into exile. The article continues with an analysis of Dos Santos' writings during his exile in Mexico and then back in Brazil. During this period he became involved with world system theory which culminated in the publication of his extensive trilogy on the contemporary crisis of capitalism and social theory

A General Modeling Approach for Shock Absorbers: 2 DoF MR Damper Case Study

A methodology is proposed for designing a mathematical model for shock absorbers; the proposal is guided by characteristic diagrams of the shock absorbers. These characteristic diagrams (Force-Displacement, Velocity-Acceleration) are easily constructed from experimental data generated by standard tests. By analyzing the diagrams at different frequencies of interest, they can be classified into one of seven patterns, to guide the design of a model. Finally, the identification of the mathematical model can be obtained using conventional algorithms. This methodology has generated highly non-linear models for 2 degrees of freedom magneto-rheological dampers with high precision (2–10% errors)

Sociedades en conflicto : movimientos sociales y movimientos armados en América Latina

América Latina consita en su geografía una paradoja que ha alimentado las diversas usinas de las ciencias sociales, en pos de una matriz explicativa: ser un continente rico en los recursos más diversos por un lado y tener las sociedades más desiguales e injustas del planeta, por el otro. La historia del continente pone en negro sobre blanco lo difícil y costoso (en vidas humanas, especialmente), que ha sido, y aún es, revertir esta situación. Allí creemos que el título de esta obra colectiva encuentra plena justificación. Esta es una puesta en común entre el grupo de trabajo del Consejo Latinoamericano de Ciencias Sociales (CLACSO) «Movimientos Sociales y Movimientos Revolucionarios en Centroamérica y el Caribe» y el Instituto de Altos Estudios Sociales y Culturales de América Latina y el Caribe de la Universidad del Norte de Colombia (UNINORTE)

Conhecimento e uso da medicina alternativa entre alunos e professores de primeiro grau Knowledge and use of alternative medicine by elementary school children and teachers

Como parte de um Projeto de Educação em Saúde, investigou-se o conhecimento e como são utilizadas as práticas populares de cura, de modo a desenvolver e ampliar na escola, as possibilidades já existentes de discussão crítica e construtiva dentro do programa de saúde. Espera-se com isso poder resgatar saberes e valorizar esse conhecimento não sistematizado, presente na prática das populações ainda de forma marginalizada e controvertida. Foram aplicados questionários entre 110 professores e 162 alunos das 1ª à 4ª séries do 1&deg; grau de quatro escolas (P.L.S.L., P.H.A., P.A.M.M. e A.M.G.) da periferia de Belo Horizonte. Sendo que, as questões apresentadas foram respondidas somente por 105 docentes. Vinte e três (32,4%) (entre 71 (67,6%)) acreditam em dons especiais de cura; dos 105 (95,4%) que responderam sobre se acham que certas doenças podem ser tratadas com remédios caseiros, somente 69 (65,7%) acreditam que sim; 54 (78,3%) dentre esses, associaram a cura da doença com a planta medicinal e 15 (21,7%) indicam o remédio sem associação com a doença; 36 (34,3%) professores citaram a doença sem relacionar as ervas medicinais. Já, 101 (62,3%) alunos acreditam que os remédios caseiros são positivos para algumas doenças. Entre os alunos e professores foram mencionadas doenças diversas, sintomas e órgãos que podem ser curados por plantas medicinais, rezas ou benzedeiras. Um pouco mais de 50% dos dois grupos de alunos (1ª, 2ª, 3ª e 4ª séries) vivem entre famílias que procuram benzedeiras como alternativa de cura. Foram indicadas pelos professores e alunos mais de 50 plantas ou composições de partes de plantas. Conclui-se, que a medicina alternativa é conhecida e utilizada pela amostra estudada.<br>The knowledge and use of popular cures was investigated as part of health education project in such a way as to develop and expand the existing possibilities for critical and constructive discussion in the school within the health program. It was hoped that this would result in the retrieval and in an increase in the value attributed to information concerning this nonsystematized knowledge present in a controversial and poorly accepted form In the practices of the population. One hundred and five teachers and 162 students of the 1st to 4th grades of the four primary schools on the outskirts of Belo Horizonte were interviewed. One hundred and five of the teachers answered the questions put. Twenty-three (32,4%) of the teachers said they believed in special cures, 69 (65,7%) thought that certain diseases could be treated with homemade remedies for these, 54 (78.3%) were able to associate a particular disease whit a particular medicinal plant and 15 (21.7%) prescribed a treatment without any association with a particular disease, 36 (34.3%) cited a disease without relating this to a particular herb. One hundred and one (62,3%) of the students believed that homemade remedies are effective for certain diseases. Amongst the teachers and students various diseases were mentioned as well as different symptoms and organs that can be cured by medicinal plants, roots or traditional healers. A little more than 50% of the two groups of students (1st and 2nd grade, 3rd and 4th grade) live in families who make use of traditional healers to provide alternative cures. More than 36 plants or preparations of parts of plants were indicated by the teachers and students. It is conclude that these individuals possess knowledge of and do in fact make use of alternative medicine

Patch grafting, strategies for transplantation of organoids into solid organs such as liver

Epithelial cell therapies have been at an impasse because of inefficient methods of transplantation to solid organs. Patch grafting strategies were established enabling transplantation of ≥107th organoids/patch of porcine GFP+ biliary tree stem/progenitors into livers of wild type hosts. Grafts consisted of organoids embedded in soft (~100 Pa) hyaluronan hydrogels, both prepared in serum-free Kubota's Medium; placed against target sites; covered with a silk backing impregnated with more rigid hyaluronan hydrogels (~700 Pa); and use of the backing to tether grafts with sutures or glue to target sites. Hyaluronan coatings (~200–300 Pa) onto the serosal surface of the graft served to minimize adhesions with neighboring organs. The organ's clearance of hyaluronans enabled restoration of tissue-specific paracrine and systemic signaling, resulting in return of normal hepatic histology, with donor parenchymal cells uniformly integrated amidst host cells and that had differentiated to mature hepatocytes and cholangiocytes. Grafts containing donor mature hepatocytes, partnered with endothelia, and in the same graft biomaterials as for stem/progenitor organoids, did not engraft. Engraftment occurred if porcine liver-derived mesenchymal stem cells (MSCs) were co-transplanted with donor mature cells. RNA-seq analyses revealed that engraftment correlated with expression of matrix-metalloproteinases (MMPs), especially secreted isoforms that were found expressed strongly by organoids, less so by MSCs, and minimally, if at all, by adult cells. Engraftment with patch grafting strategies occurred without evidence of emboli or ectopic cell distribution. It was successful with stem/progenitor organoids or with cells with a source(s) of secreted MMP isoforms and offers significant potential for enabling cell therapies for solid organs