Rad23 escapes degradation because it lacks a proteasome initiation region

Rad23 is an adaptor protein that binds to both ubiquitinated substrates and to the proteasome. Despite its association with the proteasome, Rad23 escapes degradation. Here we show that Rad23 remains stable because it lacks an effective initiation region where the proteasome can engage the protein and unfold it. Rad23 contains several internal, unstructured loops but these are too short to act as initiation regions. Experiments with model proteins show that internal loops must be surprisingly long to engage the proteasome and support degradation. These length requirements are not specific to Rad23 and reflect a general property of the proteasome

Non-steady wind turbine response to daytime atmospheric turbulence.

Relevant to drivetrain bearing fatigue failures, we analyse non-steady wind turbine responses from interactions between energy-dominant daytime atmospheric turbulence eddies and the rotating blades of a GE 1.5 MW wind turbine using a unique dataset from a GE field experiment and computer simulation. Time-resolved local velocity data were collected at the leading and trailing edges of an instrumented blade together with generator power, revolutions per minute, pitch and yaw. Wind velocity and temperature were measured upwind on a meteorological tower. The stability state and other atmospheric conditions during the field experiment were replicated with a large-eddy simulation in which was embedded a GE 1.5 MW wind turbine rotor modelled with an advanced actuator line method. Both datasets identify three important response time scales: advective passage of energy-dominant eddies (≈25-50 s), blade rotation (once per revolution (1P), ≈3 s) and sub-1P scale (s) response to internal eddy structure. Large-amplitude short-time ramp-like and oscillatory load fluctuations result in response to temporal changes in velocity vector inclination in the aerofoil plane, modulated by eddy passage at longer time scales. Generator power responds strongly to large-eddy wind modulations. We show that internal dynamics of the blade boundary layer near the trailing edge is temporally modulated by the non-steady external flow that was measured at the leading edge, as well as blade-generated turbulence motions.This article is part of the themed issue 'Wind energy in complex terrains'

Estabilização proteica de vinhos: avaliação de alternativas para minimizar a aplicação de bentonite

As características sensoriais de um vinho, assim como a sua estabilidade, são fatores determinantes para a aceitabilidade do vinho no mercado, face à exigência dos consumidores atuais. A desnaturação das proteínas do vinho é responsável pelo aparecimento de turvação nos vinhos brancos. Esta instabilidade proteica pode ser causada por fatores intrínsecos ou extrínsecos, como peso molecular e ponto isoelétrico das frações proteicas no vinho, força iónica, grau alcoólico e pH do vinho ou condições de armazenamento. Para prevenir a instabilidade proteica são usados vários produtos enológicos com objetivo de remover as proteínas instáveis, evitando assim a sua desnaturação/precipitação. O agente de colagem mais usado para adsorção das proteínas do vinho é a bentonite sódica. Esta possui carga elétrica negativa, com capacidade de interagir eletroestaticamente com as proteínas do vinho de carga maioritariamente positiva, conduzindo à sua floculação e consequente precipitação. Apesar da colagem com bentonite ser o método mais utilizado, apresenta algumas limitações, particularmente quando aplicada em doses elevadas. Isto sucede, porque a bentonite para além de remover proteínas pode também interagir com outros compostos, nomeadamente com os que contribuem positivamente nas características sensoriais, tais como os compostos voláteis. Assim, um dos objetivos do presente trabalho foi avaliar a aplicação de aditivos enológicos que permitam estabilizar as proteínas do vinho branco, em alternativa à bentonite. Numa fase preliminar, foram testados diferentes produtos nomeadamente bentonite, taninos enológicos, carboximetilcelusose (CMC), enzimas, gel de sílica, quitosana e manoproteínas em diferentes doses, com o intuito de avaliar o seu efeito na estabilização proteica do vinho branco. A bentonite e as manoproteínas foram os que apresentaram melhores resultados de estabilidade proteica. Considerando os resultados obtidos, foram selecionadas cinco bentonites e onze manoproteínas comerciais, para ensaios de estabilização das proteínas dum vinho branco. Foi avaliada a influência destes produtos enológicos na composição fenólica, capacidade de acastanhamento, características cromáticas e sensoriais do vinho branco. Os resultados obtidos confirmaram a eficiência da bentonite na estabilização proteica dos vinhos. Por outro lado, algumas manoproteínas estudadas também mostraram uma influência positiva na estabilização proteica do vinho. Inserido no presente estudo foi ainda efetuada uma caracterização das manoproteínas quanto à sua composição em açúcares (quantitativo e qualitativo) e o conteúdo em proteína. Com base na caracterização efetuada às manoproteínas foi possível estabelecer uma ligação entre a percentagem de manose e a sua eficiência na estabilização proteica do vinho, dependendo esta da percentagem de manose. A bentonite não influenciou a composição fenólica, mas algumas manoproteínas diminuíram os compostos fenólicos totais. Relativamente às características cromáticas as manoproteínas de um modo geral conduziram a um aumento da luminosidade (L*) e a um aumento da coordenada da cromaticidade (b*), contudo apenas um dos vinhos tratados apresentou uma variação de cor detetável pelo olho humano. Na análise sensorial, não foram detetadas diferenças significativas nos vinhos analisados, porém, após a análise de componentes principais, foi possível descriminar os vinhos em três grupos, sendo o grupo mais pontuado aquele que continha apenas vinhos tratados com manoproteínas. Estes resultados estão de acordo com a caracterização dos açúcares efetuada às manoproteínas, sugerindo que a elevada pontuação atribuída a este grupo, se encontra relacionada com a elevada percentagem em glucose. Este trabalho pode fornecer informações importantes, conducentes a alternativas eficientes na estabilização proteica de vinhos brancos e que simultaneamente incrementa as características sensoriais do vinho. The sensory characteristics of a wine, as well the stability, are determinant factors for acceptability of wine in the market, face of current consumer exigency. White wine proteins denaturation is responsible for the appearance of haze in white wine. This protein instability may be caused by intrinsic or extrinsic factors, such as molecular weight and isoelectric point of wine protein fraction, ionic strength, pH and alcohol content of wine or storage conditions. To prevent protein instability, several oenological products are used, with the aimed to remove instable proteins, preventing their denaturation/precipitation. Sodium bentonite is the most commonly fining agent used to adsorption of wine proteins. This compound has a negative electrical charge, with capacity to interact electrostatically with wine proteins charged mostly positively, leading to flocculation and consequently precipitation. Although fining with bentonite being the most commonly used method, present some limitations, particularly when applied in high doses. This occurs, because addition of bentonite remove proteins and may interact with other compounds, namely with compounds that contribute positively in sensorial characteristics, such as volatile compounds. Thus, the propose of this work was to evaluate the application of oenological additives, that enable stabilize white wine proteins, as an alternative to bentonite. In a preliminary trial, were tested different types of products, namely bentonite, oenological tannins, carboxylmethylcellulose (CMC) enzymes, silica gel, chitosan and mannoproteins with different dosage, in order to evaluate their effect in white wine proteins stabilization. Bentonite and mannoproteins presented the best results. Based on these results we select five bentonites and eleven commercial mannoproteins. In this trials, it was evaluated the influence of this oenological products in phenolic composition, browning potential, chromatic and sensory characteristics of a white wine. The results obtained confirm the efficiency of bentonite in wine protein stabilization. Moreover, some mannoproteins studied also showed a positive influence in wine protein stabilization. Inserted into this study, it was also performed a mannoprotein characterization on sugars composition (quantitative and qualitative) and protein content. Based on mannoprotein characterization, it was possible to establish a relation between percentage of mannose and its efficiency in wine protein stabilization, depending on mannose percentage. Bentonite did not influence phenolic composition, but some mannoproteins decreased the total phenolic compounds. Regarding chromatic characteristics mannoproteins generally lead to an increase in lightness (L*) and an increase in yellowness (b*), however just one treated wine showed a variation in colour detected by human eye. In sensory analyses, no significant differences were detected among the analyzed wines, however, after principal components analyses; it was possible to discriminate wines into three groups, being the high scored group, which contains just wine treated with mannoproteins. This results are in accordance with sugars characterization performed at mannoproteins, which may suggest that high score attributed at this group is related with high percentage of glucose. This work may provide important information, leading to efficient alternatives in white wine proteins stabilization, and simultaneously, increase sensory characteristics

Flow visualisation and evaluation studies on metalworking fluid applications in manufacturing processes : methods and results

Metalworking operations rely on the successful application of metalworking fluids (MWFs) for effective and efficient operation. Processes such as grinding or drilling often require the use of MWFs for cooling, lubrication, and chip removal. Electrochemical machining processes require electrolyte flow to operate. However, in those machining operations, a fundamental understanding of the mode of action of MWF is lacking due to the unknown flow dynamics and its interaction with the material removal during the process. Important information on the behaviour of MWFs during machining can be obtained from specific experimental flow visualisation studies. In this paper, promising flow visualisation analysis techniques applied to exemplary machining processes (grinding, sawing, drilling, and electrochemical machining) are presented and discussed. Shadowgraph imaging and flow measurements, e.g., particle image velocimetry, allow the identification of typical flow and MWF operating regimes in the different machining processes. Based on the identification of these regimes, efficient machining parameters and MWF applications can be derived. In addition, detailed experimental analyses of MWFs provide essential data for the input and validation of model development and numerical simulations within the Priority Programme SPP 2231 FluSimPro.German Research Foundation (Deutsche Forschungsgemeinschaft DFG

Modeling and simulation of the fluid flow in wire electrochemical machining with rotating tool (wire ECM)

Combining the working principle of electrochemical machining (ECM) with a universal rotating tool, like a wire, could manage lots of challenges of the classical ECM sinking process. Such a wire-ECM process could be able to machine flexible and efficient 2.5-dimensional geometries like fir tree slots in turbine discs. Nowadays, established manufacturing technologies for slotting turbine discs are broaching and wire electrical discharge machining (wire EDM). Nevertheless, high requirements on surface integrity of turbine parts need cost intensive process development and - in case of wire-EDM - trim cuts to reduce the heat affected rim zone. Due to the process specific advantages, ECM is an attractive alternative manufacturing technology and is getting more and more relevant for sinking applications within the last few years. But ECM is also opposed with high costs for process development and complex electrolyte flow devices. In the past, few studies deal with the development of a wire ECM process to meet these challenges. However, previous concepts of wire ECM were only suitable for micro machining applications. Due to insufficient flushing concepts the application of the process for machining macro geometries failed. Therefore, this paper presents the modleing and simulation of a new flushing approach for process assessment. The suitability of a rotating structured wire electrode in combination with an axial flushing for electrodes with high aspect ratios is investigated and discussed