Transfer-free graphene passivation of sub 100 nm thin Pt and Pt–Cu electrodes for memristive devices

Memristive switches are among the most promising building blocks for future neuromorphic computing. These devices are based on a complex interplay of redox reactions on the nanoscale. Nanoionic phenomena enable non-linear and low-power resistance transition in ultra-short programming times. However, when not controlled, the same electrochemical reactions can result in device degradation and instability over time. Two-dimensional barriers have been suggested to precisely manipulate the nanoionic processes. But fabrication-friendly integration of these materials in memristive devices is challenging.Here we report on a novel process for graphene passivation of thin platinum and platinum/copper electrodes. We also studied the level of defects of graphene after deposition of selected oxides that are relevant for memristive switching

Relatório de Estágio

O presente documento surge como um culminar do percurso formativo da Prática Educativa Supervisionada, em contexto de Educação Pré-Escolar e Ensino do 1.º Ciclo do Ensino Básico, onde serão explicitados referentes teóricos e legais, mobilizando conhecimentos científicos, pedagógicos e didáticos, por meio a articular a teoria e a prática desenvolvida. Salienta-se a importância concebida a todo este processo, que emergiu da metodologia de investigação-ação, uma vez que possibilitou o desenvolvimento de práticas pedagógicas refletidas a partir da observação e reflexão contínua dos contextos educativos, através das grelhas de observação e diários de formação, e que impulsionou a análise das ações desenvolvidas de forma crítica e analítica. Neste sentido, e tendo em conta os desafios da atualidade que o docente tem vindo a ultrapassar para transformar os paradigmas educacionais, urge a necessidade de formar profissionais com uma nova visão abrangente no que se refere a uma perspetiva socioconstrutivista. O perfil duplo de docente abrange o desenvolvimento de profissionais que devem formar cidadão ativos na sociedade, fornecendo-lhes durante o percurso escolar, ferramentas e competências essenciais para a vida. Destaca-se, ainda, um trabalho colaborativo desenvolvido ao longo deste processo e que permitiu o crescimento a nível pessoal e profissional.This research paper results from a formative path in Supervised Educational Practice, carried out within the scope of the Master in Pre-School Education and Teaching of the 1st Cycle of the Basic Education. In this study, theoretical and legal references are explained, assembling scientific, pedagogical, and didactic knowledge to connect theory and practice. The importance of this entire process, which emerged from the action research methodology, is highlighted as it enabled the development of pedagogical practices. The study focus on the observation and continuous analysis of the educational context, through the use of observation grids and training diaries, which enhanced the analysis of the actions developed critically and analytically. In this sense and considering the current challenges that the teacher faces to transform educational paradigms, there is an urgent need to train professionals with a new comprehensive vision concerning a socio-constructivist perspective. The dual teacher profile encompasses the development of professionals who must train active citizens in society, providing them with essential tools and skills for life during their school career. It is also noteworthy the collaborative work developed throughout this process, which allowed personal and professional growth

Catalyst Interface Engineering for Improved 2D Film Lift-Off and Transfer

The mechanisms by which chemical vapor deposited (CVD) graphene and hexagonal boron nitride (h-BN) films can be released from a growth catalyst, such as widely used copper (Cu) foil, are systematically explored as a basis for an improved lift-off transfer. We show how intercalation processes allow the local Cu oxidation at the interface followed by selective oxide dissolution, which gently releases the 2D material (2DM) film. Interfacial composition change and selective dissolution can thereby be achieved in a single step or split into two individual process steps. We demonstrate that this method is not only highly versatile but also yields graphene and h-BN films of high quality regarding surface contamination, layer coherence, defects, and electronic properties, without requiring additional post-transfer annealing. We highlight how such transfers rely on targeted corrosion at the catalyst interface and discuss this in context of the wider CVD growth and 2DM transfer literature, thereby fostering an improved general understanding of widely used transfer processes, which is essential to numerous other applications.We acknowledge funding from the ERC (InsituNANO, grant 279342). R.W. acknowledges an EPSRC Doctoral Training Award (EP/M506485/1). During this work, S.T. was supported in parts by a DFG research fellowship under grant TA 1122/1-1:1. J.A.A.-W. acknowledges a Research Fellowship from Churchill College, Cambridge. Z.A.V.V. acknowledges funding from ESPRC grant EP/L016087/1. P.B. and B.S.J. thank the Danish National Research Foundation Centre for Nanostructured graphene, DNRF103, and EU Horizon 2020 “Graphene Flagship” 696656. T.J.B. and P.R.W. acknowledge financial support from EU FP7-6040007 “GLADIATOR” and Innovation Fund Denmark Da-Gate 0603-005668B. P.R.K. acknowledges a Lindemann Trust Fellowship

Outcome of experimental stroke in C57Bl/6 and Sv/129 mice assessed by multimodal ultra-high field MRI

Transgenic mice bred on C57Bl/6 or Sv/129 genetic background are frequently used in stroke research. It is well established that variations in cerebrovascular anatomy and hemodynamics can influence stroke outcome in different inbred mouse lines. We compared stroke development in C57Bl/6 and Sv/129 mice in the widely used model of transient middle cerebral artery occlusion (tMCAO) by multimodal ultra-high field magnetic resonance imaging (MRI)

Rodent models of focal cerebral ischemia: procedural pitfalls and translational problems

Rodent models of focal cerebral ischemia are essential tools in experimental stroke research. They have added tremendously to our understanding of injury mechanisms in stroke and have helped to identify potential therapeutic targets. A plethora of substances, however, in particular an overwhelming number of putative neuroprotective agents, have been shown to be effective in preclinical stroke research, but have failed in clinical trials. A lot of factors may have contributed to this failure of translation from bench to bedside. Often, deficits in the quality of experimental stroke research seem to be involved. In this article, we review the commonest rodent models of focal cerebral ischemia - middle cerebral artery occlusion, photothrombosis, and embolic stroke models - with their respective advantages and problems, and we address the issue of quality in preclinical stroke modeling as well as potential reasons for translational failure

Deep-learning based classification of a tumor marker for prognosis on Hodgkin's disease

Purpose: Hodgkin's disease is a common malignant disorder in adolescent patients. Although most patients are cured, approximately 10%–15% of patients experience a relapse or have resistant disease. Furthermore, there are no definitive molecular predictors for early identification of patients at high risk of treatment failure to first line therapy. The aim of this study was to evaluate the deep learning-based classifier model of medical image classification to predict clinical outcome that may help in appropriate therapeutic decisions. Methods: Eighty-three FFPE biopsy specimens from patients with Hodgkin's disease were stratified according to the patient's qPET scores, stained with picrosirius red dye and digitalized by whole slide image scanning. The resulting whole slide images were cut into tiles and annotated by two classes based on the collagen fibers' degree of coloring with picrosirius red. The neural network (YOLOv4) was then trained with the annotated data. Training was performed with 30 cases. Prognostic power of the weakly stained picrosirius red fibers was evaluated with 53 cases. The same neural network was trained with MMP9 stained tissue slides from the same cases and the quantification results were compared with the variant from the picrosirius red cases. Results: There was a weak monotonically increasing relationship by parametric ANOVA between the qPET groups and the percentages of weakly stained fibers (p = .0185). The qPET-positive cases showed an average of 18% of weakly stained fibers, and the qPET-negative cases 10%–14%. Detection performance showed an AUC of 0.79. Conclusions: Picrosirius red shows distinct associations as a prognostic metric candidate of disease progression in Hodgkin's disease cases using whole slide images but not sufficiently as a prognostic device

Die demografische Herausforderung Ein Ueberblick ueber die Bevoelkerungsproblematik und ihre gesellschaftlichen und oekonomischen Konsequenzen

'Waehrend die Weltbevoelkerung weiter steigt und 2050 fast 9 1/2 Mrd. erreichen wird (z.Zt. 6 Mrd.), nimmt sie in vielen Industrielaendern ab, vor allem in Europa und Japan. In der EU wird die Bevoelkerung ab 2015 schrumpfen. Bis 2050 werden dort 40 Mio. Menschen weniger leben als heute. In Deutschland koennte die Bevoelkerung in den kommenden 50 Jahren um 12 auf rund 70 Mio. sinken. Zudem droht die Ueberalterung der Gesellschaften. In manchen Industrielaendern wird in wenigen Dekaden den Erwerbstaetigen die gleiche Anzahl an Rentnern gegenueberstehen. In vielen Industrielaendern kommt es zu einem gravierenden Mangel an Nachwuchs und an Fachkraeften. Ab 2020 duerfte das Erwerbspersonenpotenzial in Deutschland um durchschnittlich gut 1 Prozent p.a. zurueckgehen. Eine aehnliche Entwicklung ist auch in Europa insgesamt zu erwarten. Bei zunehmendem Durchschnittsalter der Beschaeftigten waechst die Gefahr einer Erosion der Wissensbasis und eines Verlustes an Innovationsfaehigkeit. Das Wachstumspotenzial duerfte bis 2050 in Europa auf 1 bis 1 1/2 Prozent zurueckgehen. Die demografische Entwicklung verstaerkt den Wandel der Nachfragestruktur. Zu den Gewinnern zaehlt der Gesundheitssektor (Pharma, Biotech, Medizintechnik, Gesundheitsdienste), waehrend der Wohnungsbau zu den Verlierern gehoert. Die umlagefinanzierten Sozialsysteme geraten unter Druck. Steigt der Altenquotient um 100 Prozent - wie fuer Europa prognostiziert - bedeutet dies, dass c.p. das Rentenniveau halbiert oder der Beitragssatz verdoppelt werden muesste. Daher ist mehr private Vorsorge notwendig. Die weltweit divergierenden demografischen Trends werden zu massiven internationalen Kapitalbewegungen fuehren. Aufgrund eines geringeren globalen Trendwachstums werden die Renditen von Aktien und Anleihen sinken. Die internationalen Wanderungen werden betraechtlich zunehmen. In Europa duerfte es zur Zuwanderung aus dem Nahen Osten und Nordafrika kommen.' (Autorenreferat)SIGLEAvailable from Deutsche Bank Research, Frankfurt am Main (DE) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman