Scalable Production of Graphene Inks via Wet‐Jet Milling Exfoliation for Screen‐Printed Micro‐Supercapacitors

The miniaturization of energy storage units is pivotal for the development of next‐generation portable electronic devices. Micro‐supercapacitors (MSCs) hold great potential to work as on‐chip micro‐power sources and energy storage units complementing batteries and energy harvester systems. Scalable production of supercapacitor materials with cost‐effective and high‐throughput processing methods is crucial for the widespread application of MSCs. Here, wet‐jet milling exfoliation of graphite is reported to scale up the production of graphene as a supercapacitor material. The formulation of aqueous/alcohol‐based graphene inks allows metal‐free, flexible MSCs to be screen‐printed. These MSCs exhibit areal capacitance (C_areal) values up to 1.324 mF cm^?2 (5.296 mF cm^?2 for a single electrode), corresponding to an outstanding volumetric capacitance (C_vol) of 0.490 F cm^?3 (1.961 F cm^?3 for a single electrode). The screen‐printed MSCs can operate up to a power density above 20 mW cm^?2 at an energy density of 0.064 µWh cm^?2. The devices exhibit excellent cycling stability over charge–discharge cycling (10 000 cycles), bending cycling (100 cycles at a bending radius of 1 cm) and folding (up to angles of 180°). Moreover, ethylene vinyl acetate‐encapsulated MSCs retain their electrochemical properties after a home‐laundry cycle, providing waterproof and washable properties for prospective application in wearable electronics.     

Defect Modulation Doping

The doping of semiconductor materials is a fundamental part of modern technology, but the classical approaches have in many cases reached their limits both in regard to achievable charge carrier density as well as mobility. Modulation doping, a mechanism that exploits the energy band alignment at an interface between two materials to induce free charge carriers in one of them, is shown to circumvent the mobility restriction. Due to an alignment of doping limits by intrinsic defects, however, the carrier density limit cannot be lifted using this approach. Here, a novel doping strategy using defects in a wide bandgap material to dope the surface of a second semiconductor layer of dissimilar nature is presented. It is shown that by depositing an insulator on a semiconductor material, the conductivity of the layer stack can be increased by 7 orders of magnitude, without the necessity of high‐temperature processes or epitaxial growth. This approach has the potential to circumvent limits to both carrier mobility and density, opening up new possibilities in semiconductor device fabrication, particularly for the emerging field of oxide thin film electronics.     

Operationalising resilience for disaster medicine practitioners: capability development through training,simulation and reflection

Cognition, Technology & Work - Resilience has in recent decades been introduced as a term describing a new perspective within the domains of disaster management and safety management. Several...     

A new technique to determine rate constants for growth and agglomeration with size- and time-dependent nuclei formation

Fluidized bed spray agglomeration is a particle size enlargement process where particles stick together with the help of spraying binder. High impact forces between particles lead to attrition. Attrition may be modeled as poly-disperse nucleation. Furthermore, particulate event like over-spray leads to the formation of particles in a wide range of volume. A new technique for the determination of agglomeration, growth and nucleation parameters is presented in this work. The model is based on a previous approach which takes mono disperse nuclei formation in the smallest class into account. Frequently in crystallization processes, nucleation is assumed to be mono-disperse. The technique presented here incorporates nuclei formation in a certain range of volume. It is quite general and applicable to consider size- and time-dependent nuclei formation. For two particular cases of growth and agglomeration including size-dependent nuclei formation, simulation data was generated by continuous feeding of nuclei in a certain range to demonstrate the capability of parameter extraction of the model. Further, the new technique is applied to extract rate constants from experimental data measured during fluidized bed spray agglomeration. This technique is also useful for the prediction of bimodal behavior of particle size distributions (PSD).     

Surface functionalization by smart coatings: Stimuli-responsive binary polymer brushes

Heterogeneous binary polymer brushes consist of an assembly of polymer chains of two incompatible polymers that are attached by one end to the surface with sufficient grafting density. They have been investigated experimentally only for a short time. Those brushes can be used in the form of ultrathin polymeric layers as a versatile tool for surface engineering to tune physico-chemical surface characteristics as wettability, surface charge, chemical composition or morphology, and furthermore to create switchable and responsive surface properties. For the fabrication of these layers “grafting-from” (as radical polymerization at the interface) and “grafting-to” (as tethering of the polymer chains from solution) methods were developed and investigated in detail.     

The impact of color combinations on the legibility of text presented on LCDs

The paper investigates the impact of text and background color combinations on the legibility of text presented on LCDs. The legibility of 56 elementary color combinations was tested by 308 participants. The first task required the participants to identify 21 uppercase alphabetic characters selected and presented in conformance with a Snellen chart in various color combinations. For each color combination, the number of correctly identified characters was recorded as a visual performance measure. In the second task, participants subjectively rated the legibility of color combinations on a ten-point Likert scale. The results show that neither the Le Courier legibility table nor the CRT legibility table is appropriate for LCDs. A new legibility table is proposed for LCDs where the highest ranked are contrastive color combinations with positive polarity whereas for CRT displays, the highest ranked are contrastive color combinations with negative polarity. The findings of this study can be used to determine the best possible color combinations when developing content displayed on LCDs.     

On the reuse and recommendation of model refactoring specifications

Refactorings can be used to improve the structure of software artefacts while preserving the semantics of the encapsulated information. Various types of refactorings have been proposed and implemented for programming languages (e.g., Java or C#). With the advent of (MDSD), a wealth of modelling languages rises and the need for restructuring models similar to programs has emerged. Since parts of these modelling languages are often very similar, we consider it beneficial to reuse the core transformation steps of refactorings across languages. In this sense, reusing the abstract transformation steps and the abstract participating elements suggests itself. Previous work in this field indicates that refactorings can be specified generically to foster their reuse. However, existing approaches can handle certain types of modelling languages only and solely reuse refactorings once per language. In this paper, a novel approach based on role models to specify generic refactorings is presented. Role models are suitable for this problem since they support declaration of roles which have to be played in a certain context. Assigned to generic refactoring, contexts are different refactorings and roles are the participating elements. We discuss how this resolves the limitations of previous works, as well as how specific refactorings can be defined as extensions to generic ones. The approach was implemented in our tool Refactory based on the (EMF) and evaluated using multiple modelling languages and refactorings. In addition, this paper investigates on the recommendation of refactoring specifications. This is motivated by the fact that language designers have many possibilities to enable refactorings in their modelling languages with regard to the language structures. To overcome this problem and to support language designers in deciding which refactorings to enable, we propose a solution and a prototypical implementation.     

simpA: An agent-oriented approach for programming concurrent applications on top of Java

More and more aspects of concurrency and concurrent programming are becoming part of mainstream programming and software engineering, due to several factors such as the widespread availability of multi-core/parallel architectures and Internet-based systems. This leads to the extension of mainstream object-oriented programming languages and platforms-Java is a main example-with libraries providing fine-grained mechanisms and idioms to support concurrent programming, in particular for building efficient programs. Besides this fine-grained support, a main research goal in this context is to devise higher-level, coarse-grained abstractions that would help building concurrent programs, as pure object-oriented abstractions help building large component-based programs. To this end, in this paper we present simpA, a Java-based framework that provides programmers with agent-oriented abstractions on top of the basic OO layer, as a means to organize and structure concurrent applications. We first describe the application programming interface (API) and annotation framework provided to Java programmers for building simpA applications, and then we discuss the main features of the approach from a software engineering point of view, by showing some programming examples. Finally, we define an operational semantics formalizing the main aspects of this programming model.     

Accurate multi-robot targeting for keyhole neurosurgery based on external sensor monitoring

Robotics has recently been introduced in surgery to improve intervention accuracy, to reduce invasiveness and to allow new surgical procedures. In this framework, the ROBOCAST system is an optically surveyed multi-robot chain aimed at enhancing the accuracy of surgical probe insertion during keyhole neurosurgery procedures. The system encompasses three robots, connected as a multiple kinematic chain (serial and parallel), totalling 13 degrees of freedom, and it is used to automatically align the probe onto a desired planned trajectory. The probe is then inserted in the brain, towards the planned target, by means of a haptic interface. This paper presents a new iterative targeting approach to be used in surgical robotic navigation, where the multi-robot chain is used to align the surgical probe to the planned pose, and an external sensor is used to decrease the alignment errors. The iterative targeting was tested in an operating room environment using a skull phantom, and the targets were selected on magnetic resonance images. The proposed targeting procedure allows about 0.3 mm to be obtained as the residual median Euclidean distance between the planned and the desired targets, thus satisfying the surgical accuracy requirements (1 mm), due to the resolution of the diffused medical images. The performances proved to be independent of the robot optical sensor calibration accuracy.