Polyelectrolyte multilayer electrostatic gating of graphene field-effect transistors

We apply polyelectrolyte multilayer films by consecutive alternate adsorption of positively charged polyallylamine hydrochloride and negatively charged sodium polystyrene sulfonate to the surface of graphene field effect transistors. Oscillations in the Dirac voltage shift with alternating positive and negative layers clearly demonstrate the electrostatic gating effect in this simple model system. A simple electrostatic model accounts well for the sign and magnitude of the Dirac voltage shift. Using this system, we are able to create p-type or n-type graphene at will. This model serves as the basis for understanding the mechanism of charged polymer sensing using graphene devices, a potentially technologically important application of graphene in areas such as DNA sequencing, biomarker assays for cancer detection, and other protein sensing applications.     

An advanced prediction mechanism to analyse pore geometry shapes and identification of blocking effect in VRLA battery system

The aim of this investigation is to define a model of an alternating current impedance response that can identify the state of health of a porous electrode due to the blocked diffusion effect. To identify and simulate different pore geometries, an analytical differential equations system was studied. Standard and low performance battery products were simulated by the model and validated with electrochemical impedance spectroscopy (EIS) experimental data. The correlation between pore structure geometries and the related battery efficiency is also addressed. This investigation may clarify the possible reasons for low performance batteries. Identifying the benchmark pore geometry, parameters may be useful for the battery producers to improve the efficiency of their products. Various recovery methods are also included in this investigation to disperse the build-up of lead sulphate crystal that limits the electrolysis process in the low performance batteries.     

Microblogging

Twitter & Co. sind ein aktuelles Trendthema im Web. Dieser Beitrag stellt das Ph?nomen Microblogging vor, beschreibt, warum das Thema ein gro?es Entwicklungspotenzial aufweist und nennt zukünftige Forschungsaufgaben.     

The dank cellar of electronic texts

The dank cellar surveys rather critically the litter of casualtyelectronic editions and the false bases and limited goals thatinformed so many early—that is, current—efforts;and it points hopefully to the best early, though still inadequate,efforts to provide electronic texts responsibly and with addedscholarly value. It looks at some problems of representing Victorianfiction.     

基于以太网的仪器

将PLC或DCSI／O模块连接到以太网已经十分普遍，而将独立过程或离散传感设备连接到以太网的尝试则相对较少。但这一看法是否正在改变？     

Sensitivity analysis of a directional potential drop sensor for creep monitoring

Recent research efforts indicated that directional potential drop (PD) measurements could be exploited for in-situ creep monitoring. The present work investigates the sensitivity of such measurements with a square-electrode configuration to geometrical and material variations caused by creep. This measurement technique is based on a modification of the conventional PD technique as it measures simultaneously two resistance values in orthogonal directions. Under uniaxial stress condition, the ratio of the lateral and axial resistances is roughly proportional to the applied strain. Experimental tests showed that small anisotropic changes in the resistance ratio caused by directional effects of creep can be distinguished from potentially far larger isotropic changes caused by non-directional reversible and irreversible thermal effects. The sensitivity of the square-electrode PD sensor to geometrical and material variations was analyzed separately and the analytical predictions were validated by experimental tests in both cases. The directional PD technique was found to exhibit high sensitivity that allows the detection of elastic and plastic strains as low as 0.05%. Additional experimental results from an accelerated 400-hour creep test are presented to demonstrate the feasibility of this technique to monitor creep degradation in 304 stainless steel at 600 °C.     

‘Creating futures that would otherwise not be’ – Reflections on the Greater Helsinki Vision process and the making of metropolitan regions

In 2007, the Greater Helsinki Vision 2050 ideas competition was held and attracted international interest, with more than one hundred submissions, out of which ultimately nine were chosen as winners. The ideas competition was a voluntary joint effort of the fourteen municipalities composing the Greater Helsinki Area. In principle, the competition can be understood as the shared effort to create ‘futures that would otherwise not be’ (Albrechts). One possible future is actually the formation of a metropolitan region in Finland, which does not yet exist, at least in any formal sense. Even though it does not yet exist, the making of a metropolis is high on the agenda of many actors in Finland. This article explores the how and why of this competition, the results, the implications and its complications. For that purpose, it will develop a framework to understand the situation, addressing the particularities of the Finnish territory and policy. It will present and comment on the Greater Helsinki Vision competition and also its follow-up process. After this, the article will also reflect on the current academic and planning debate regarding metropolitan regions, their existence and function, and their ambivalences for societal and territorial development. The final conclusions will look into theoretical aspects of ‘vision making’, post-modern planning, and how a territorial response capacity can be shaped to create different futures.