Ascensão e queda dos cfcs como estudo de caso : diferentes estágios de conscientização acerca de riscos químicos

Ao criar novas substâncias, todo químico precisa lidar com a possibilidade de essas substâncias oferecerem algum tipo de perigo. Este trabalho se apresenta como um estudo de caso, que pode servir aos educadores em química como motivador de reflexões a respeito do gerenciamento dos riscos ambientais inerentes à atividade dos químicos. O estudo é focado na trajetória da preparação, uso e descoberta dos riscos ambientais dos compostos conhecidos como clorofluorocarbonos (CFCs). Para isso foram consultados artigos científicos do período enfocado, além de fontes secundárias em história e em filosofia da química. Pode-se classificar as concepções dos químicos a respeito dos riscos oferecidos pelas substâncias produzidas por eles em três dimensões: individual, ambiental local e ambiental global – sendo que esta emerge definitivamente na década de 1970

Química ambiental e química verde : como se integram às áreas tradicionais da química na visão de graduandos

Este trabalho investiga as concepções de alunos de graduação em química da Universidade de São Paulo (USP) a respeito do status da Química Ambiental e da Química Verde em relação ao conjunto do conhecimento químico. O estudo foi feito através da análise de quatorze mapas conceituais produzidos por alunos do terceiro ano de graduação considerando-se as concepções manifestadas a respeito da química ambiental e da química verde, bem como as relações estabelecidas entre elas e as cinco áreas tradicionais da química. De modo geral, os alunos encontram dificuldades em expressar concepções abrangentes e integradoras a respeito de química ambiental e química verde, conforme sugerem os objetivos atuais para o ensino de química. Os resultados mostram forte influência da estrutura curricular dos diferentes cursos sobre as concepções dos alunos

Conception and parametric design workflow for a timber large-spanned reversible grid shell to shelter the archaeological site of the Roman Shipwrecks in Pisa

Reciprocal structures or nexorade are composed by the assembling of groups of three or more beams mutually connected by mono-lateral T joints in a way that any relative movement is suppressed. This kind of structures can be easily built in relatively unprepared sites, dismantled, transported and re-used even by not specialized handcraft. For these reasons, reciprocal structures have been widely used in the past for military purposes, and nowadays they seem to satisfy very well the different requirements of a quick and temporary shelter of a large archaeological area when they are shaped as grid shells. This paper proposes the design of a reversible, reciprocal framed grid shell to shelter the archaeological site of the Roman Shipwrecks in Pisa. The structure must protect excavations and archaeologists from the weather and provide an easy access to visitors. Additionally, it must allow for easy disassembling and moving to another site. The design choices aim at optimizing both structural efficiency and esthetical qualities. A parametric workflow for both the form finding and the digital fabrication processes has been developed, and a prototype of accommodative steel T-joint for timber reciprocal beams has been realized. Finally, a model using CNC-cutting tested the structural feasibility of such a design approach

Head & Neck Oncology: purpose, scope and goals-charting the future

For many years now there has been a growing frustration with the statistics of head and neck cancer. Despite the many advances in diagnosis and therapy, there has been little change in the prognosis for most cancers of the head and neck in the last 50 years, so what is the point of yet another journal? Well, it is not all bad news

Dinosaur Speed Demon: The Caudal Musculature of Carnotaurus sastrei and Implications for the Evolution of South American Abelisaurids

In the South American abelisaurids Carnotaurus sastrei, Aucasaurus garridoi, and, to a lesser extent Skorpiovenator bustingorryi, the anterior caudal ribs project at a high dorsolateral inclination and have interlocking lateral tips. This unique morphology facilitated the expansion of the caudal hypaxial musculature at the expense of the epaxial musculature. Distinct ridges on the ventrolateral surfaces of the caudal ribs of Aucasaurus garridoi are interpreted as attachment scars from the intra caudofemoralis/ilio-ischiocaudalis septa, and confirm that the M. caudofemoralis of advanced South American abelisaurids originated from a portion of the caudal ribs. Digital muscle models indicate that, relative to its overall body size, Carnotaurus sastrei had a substantially larger M. caudofemoralis than any other theropod yet studied. In most non-avian theropods, as in many extant sauropsids, the M. caudofemoralis served as the primary femoral retractor muscle during the locomotive power stroke. This large investment in the M. caudofemoralis suggests that Carnotaurus sastrei had the potential for great cursorial abilities, particularly short-burst sprinting. However, the tightly interlocking morphology of the anterior caudal vertebrae implies a reduced ability to make tight turns. Examination of these vertebral traits in evolutionary context reveals a progressive sequence of increasing caudofemoral mass and tail rigidity among the Abelisauridae of South America

Synchronous bilateral epithelial–myoepithelial carcinoma of the parotid gland: case report and review of the literature

Synchronous bilateral malignancy in the parotid glands is extremely rare. The English literature reveals nine case reports. The most common synchronous bilateral malignancies are acinic cell carcinoma. Epithelial–myoepithelial carcinoma is an uncommon neoplasm comprising 1% of all salivary gland tumours. In this case report, we describe, to our best of knowledge, the first case of a patient with a synchronous bilateral epithelial–myoepithelial carcinoma of the parotid gland. The clinical histopathological and immunohistochemical peculiarities are elucidated. Imaging studies like ultrasonography are mandatory for both parotid glands and upper necks in the clinical presence of a unilateral parotid gland tumour

Electrical Sintering of Silver Nanoparticle Ink Studied by In-Situ TEM Probing

Metallic nanoparticle inks are used for printed electronics, but to reach acceptable conductivity the structures need to be sintered, usually using a furnace. Recently, sintering by direct resistive heating has been demonstrated. For a microscopic understanding of this Joule heating sintering method, we studied the entire process in real time inside a transmission electron microscope equipped with a movable electrical probe. We found an onset of Joule heating induced sintering and coalescence of nanoparticles at power levels of 0.1–10 mW/m3. In addition, a carbonization of the organic shells that stabilize the nanoparticles were found, with a conductivity of 4 105 Sm−1