Formation of Atomic Carbon Chains from Graphene Nanoribbons

The formation of one-dimensional carbon chains from graphene nanoribbons is investigated using it ab initio molecular dynamics. We show under what conditions it is possible to obtain a linear atomic chain via pulling of the graphene nanoribbons. The presence of dimers composed of two-coordinated carbon atoms at the edge of the ribbons is necessary for the formation of the linear chains, otherwise there is simply the full rupture of the structure. The presence of Stone-Wales defects close to these dimers may lead to the formation of longer chains. The local atomic configuration of the suspended atoms indicates the formation of single and triple bonds, which is a characteristic of polyynes.Comment: 4 pages, 5 figure

A study on shrinkage and warpage of rotational moulded polyethylene

Warpage and poor dimensional stability of rotomoulded products are two of the main obstacles to the use of this technique in the production of engineering parts. The knowledge of the effect of the processing conditions on the shrinkage of rotomoulded parts will allow overcoming some of the restrictions of this process. In the present work the influence of the processing conditions on the development of shrinkage and warpage of rotomoulded parts was studied. The moulding of the parts was performed using a rotational moulding machine build at the University of Minho. The shrinkage and the warpage of the moulded parts were assessed using 3D MMC (3D measuring Machine Control) equipment, and understanding the microstructural development

3 axis polymeric accelerometer and method of production

The present invention consists in a thermal accelerometer capable of detecting acceleration in multiple axes. The accelerometer is made of four microinjected polymeric parts (1, 2, 3, 4), which can be two identical top parts and two identical central parts or four different parts, which are assembled with active polymeric membranes (5, 6, 7) to construct the 3-axis acceleration sensing device. The microinjected parts provide mechanical support for the heater and temperature sensors that are placed on the membranes. The device operating gas medium is hermetically sealed by the polymer parts and electrical current applied to the heater causes the air to heat and external acceleration imposes a gradient of temperature sensed by the thermal sensing elements

Mould redesign and analysis for the production of a micro-accelerometer

In this paper we present an alternative fabrication method based on polymeric materials and technologies for three-axis thermal accelerometers. The device is composed by four microinjected parts forming an external structure responsible for the coupling and sealing of a polymeric membrane. The membrane contains and protects the heater and thermoresistors and is fabricated by microtechnologies. The fabrication process was successful although some issues were noticed in the mould during the microinjection process. Regarding the ejection side, a redesign was done to first assure the locking of the micro-parts on the movable side of the mould and second to improve the extraction of the parts avoiding its deformation. Overheating of the mould and polymer freezing on the injection nozzle were the main issues found on the injection side of the mould. Three different injection nozzle designs and two different fabrication materials were analyzed and simulated. The results show that an intermediate injection nozzle design using Ampcoloy 940® as construction material can improve the maintenance of the established temperature values for both mould and injection nozzle

Resposta da produção de matéria seca do meloeiro à omissão de micronutrientes em um solo de Juazeiro - BA.

O trabalho teve como objetivo avaliar o efeito da omissão de B, Cu, Fe, Mn e Zn em plantas de melão (Cucumis melo L.) cultivadas em vasos contendo um solo argiloso de Juazeiro-BA, em ambiente protegido. Foram testados sete tratamentos: completo, testemunha, omissão de B, de Cu, de Fe, de Mn ou de Zn, dispostos no delineamento inteiramente casualizado, com quatro repetições. Avaliou-se o peso da matéria seca da parte aérea e das raízes aos 55 dias após a emergência das plantas. A omissão de Cu e Zn, provocou uma redução significativa na produção de matéria seca da parte aérea. Não houve efeito dos tratamentos sobre a matéria seca das raízes.Suplemento. Edição de Resumos expandidos e palestras do 43. Congresso Brasileiro de Olericultura, Recife, jul. 2003

Assessing the environmental and economic performance of alternative car chassis

The main objective of this study is to evaluate the life cycle environmental and economic performance of a car multimedia chassis containing metallic parts, and compare it with new, totally plastic, chassis designs. The Life Cycle Assessment and Life Cycle Costing methodologies were applied. All systems boundaries consider material and parts production, and the use and End of Life (EoL) phases of the chassis. The results showed that the former system has a higher environmental impact, the material production being the main contributor followed by the use phase, and Fossil depletion the most burdensome impact category. All total plastic scenarios enable approximately 40% weight reduction, mitigating both the Global Warming Potential and the Cumulative Energy Demand environmental impacts until the end of the use phase. However, this result is inverted including the EoL phase, as recycling the metal is more favourable than incinerating the polymer and recovering energy. All TPC scenarios present a higher cost. Although their assembly and use phases costs are lower than the corresponding BSL ones, this does not mitigate the higher material and production costs. Again, at EoL, recycling the metal is more cost favourable. The present work evidences that to make sustainable decisions environmental and economic considerations should be concurrently contemplated in product development.The present work was partially financed by the Portuguese Incentive System for Research and Technological Development, as co-promotion Project nº 36265/2013 (Project HMIExcel – 2013-2015). The authors thank the support of the Bosch Car Multimedia Portugal, S.A. company throughout the inventory phase of the study. Two of the authors (CAB, AJP) acknowledge the funding received from FCT, the Portuguese Foundation for Science and Technology, through project UID/CTM/50025/2013 and from the COMPETE 2020 Programme under project POCI-01-0145-FEDER-00768

Item response theory analysis of the recoded Internet Gaming Disorder Scale-Short-Form (IGDS9-SF)

Based on the nine criteria for Internet gaming disorder (IGD) in DSM-5, the Internet Gaming Disorder Scale 9-Short Form (IGDS9-SF; Pontes and Griffiths 2015) is the most widely used questionnaire for assessing IGD. The present study examined support for the unidimensional factor structure of the instrument, with a group of 868 adolescent and adult gamers from the USA, with criteria recoded as present or absent. The two-parameter logistic model (2PLM) was used to examine the item response theory properties of the criteria included in the measure. Confirmatory factor analysis supported the one-factor model. The 2PLM analysis indicated that all the criteria were strong discriminators of high and low latent IGD. Furthermore, the items measured more of the GAD dimension and with more precision from around +2 SD from the mean trait level. The implications of the findings for interpreting the IGDS9-SF scores for clinical practice are discussed

Intervalo e número de aplicações do acibenzolar-s-metil no manejo da mancha bacteriana em tomate para processamneto industrial.

Esse trabalho objetivou avaliar o efeito do intervalo entre aplicações (4, 7, 10 e 14 dias) e do número de aplicações (4,6, 8 e 10) do ASM na eficiência de controle da doença em campo e na produtividade final, bem como na relação beneficio/custo dos tratamentos.Suplemento. Edição dos resumos do 44º Congresso Brasileiro de Fitopatologia, 2011, Bento Gonçalves. Resumo 318

Uni- and biaxial impact behavior of double-gated nanoclay-reinforced polypropylene injection moldings

Polypopylene/nanoclay three-dimensional parts were produced without intermediate steps by direct injection molding to explore the influence of flow features and nanoclay incorporation in their impact performance. The nanocomposite was obtained by direct compounding of commercial PP with nanoclay masterbatch. The as-molded morphology was analyzed by X-ray and TEM analyses in terms of skin-core structure and nanoclay particle dispersion. The nanoclay particles induced the reduction of b-form spherulites, a known toughener. The impact behavior was assessed in tensile and biaxial modes. The PP nanocomposite molding toughness was practically unaffected by the processing melt temperature and flow rate. Conversely the nanoclay presence is influent in the impact performance. Under biaxial stress impact, the regions close to weld lines are tougher than the bulk and the fracture develops with main crack paths along the flow direction and the weld line. Cracking along the weld line results from less macromolecular interpenetration and chain entanglement, and unfavorable nanoparticle orientation. It seems that a failure mechanism which involves nanoclay delamination and multiple matrix crazing explains the toughening of PP in the directions where the nanoparticle orientation with respect to loading is adequate.Contract grant sponsors: CONICET, ANPCyT from Argentina, MINCyT (Argentina) - FCT (Portugal), Universities Nacional de Mar del Plata and Minho