Super-quadratic behavior of luminescence decay excited by energy-transfer upconversion

For several decades, energy-transfer upconversion (ETU) in rare-earth-ion doped systems [1,2] has attracted much attention, firstly, because of the fundamental interest in the physical nature of this process and, secondly, because of very practical considerations, namely the demonstration of near-infrared pumped visible light sources and, in reverse, the detrimental influence of ETU on the efficiency of infrared emitting systems.\ud We investigate fundamentally the behavior of infrared luminescence emitted directly from a metastable level and visible luminescence emitted after ETU from this level to higher-lying levels. Although these two luminescences are connected by the same metastable level and influenced by the same ETU process, the infrared luminescence probes all ions, while the visible luminescence probes only the class of ions susceptible to ETU [3]. A simple analytical model [4] predicts that such luminescence decay curves exhibit a super-quadratic dependence of upconversion on direct luminescence decay.\ud The Nd3+ ion can serve as a model system for such investigations. It exhibits strong ETU from the metastable 4F3/2 level. When doped into oxide matrices, the 4F3/2 level is the only metastable level. The Nd3+ energy levels excited by ETU decay by fast multiphonon relaxation and, hence, the weak visible fluorescence emitted from these levels represents a quasi instantaneous reaction on the dynamics of the 4F3/2 level. Experimental results obtained after pulsed laser excitation of Nd3+-doped oxide host materials show indeed a super-quadratic behavior of upconversion versus direct luminescence decay, in accordance with the model predictions [4].\ud \ud [1] F. Auzel, Proc. IEEE 1973, 6, 758\ud [2] J.C. Wright, Top. Appl. Phys. 1976, 15, 239\ud [3] M. Pollnau, D.R. Gamelin, S.R. Lüthi, H.U. Güdel, M.P. Hehlen, Phys. Rev. B 2000, 61, 3337\ud [4] M. Pollnau, J. Alloys Compd. 2002, 341, 5

Superquadratic behavior of upconversion luminescence transients in rare-earth-ion doped laser crystals

Inhomogeneous active-ion distributions in laser materials lead to strong deviations of upconversion versus direct luminescence transients from the quadratic law of energy-transfer upconversion. Measured luminescence decay curves in LaSc3(BO3)4:Nd3+ and GdVO4:Nd3+ confirm experimentally the predicted deviations. Differences in energy migration within the metastable level of Nd3+ are identified

ALP-Based Biosensors Employing Electrodes Modified with Carbon Nanomaterials for Pesticides Detection

Due to the growing presence of pesticides in the environment and in food, the concern of their impact on human health is increasing. Therefore, the development of fast and reliable detection methods is needed. Enzymatic inhibition-based biosensors represent a good alternative for replacing the more complicated and time-consuming traditional methods (chromatography, spectrophotometry, etc.). This paper describes the development of an electrochemical biosensor exploiting alkaline phosphatase as the biological recognition element and a chemically modified glassy carbon electrode as the transducer. The biosensor was prepared modifying the GCE surface by a mixture of Multi-Walled-Carbon-Nanotubes (MWCNTs) and Electrochemically-Reduced-Graphene-Oxide (ERGO) followed by the immobilization of the enzyme by cross-linking with bovine serum albumin and glutaraldehyde. The inhibition of the biosensor response caused by pesticides was established using 2-phospho-L-ascorbic acid as the enzymatic substrate, whose dephosphorylation reaction produces ascorbic acid (AA). The MWCNTs/ERGO mixture shows a synergic effect in terms of increased sensitivity and decreased overpotential for AA oxidation. The response of the biosensor to the herbicide 2,4-dichloro-phenoxy-acetic-acid was evaluated and resulted in the concentration range 0.04-24 nM, with a limit of the detection of 16 pM. The determination of other pesticides was also achieved. The re-usability of the electrode was demonstrated by performing a washing procedure

Digitalization technologies for industrial sustainability

Digital technologies are shown to perform a potential role in developing a resource efficient industrial base. The effective adoption of them can help to deliver reduced costs and improve the flexibility and sustainability of manufacturing systems. However, these positive benefits are far from guaranteed and the way in which digital technologies favor the transition towards sustainable manufacturing systems has not been analyzed in detail yet, so more conceptual and empirical investigations are required in this field. This paper develops a conceptual framework, which explains the potential significance of using digital technologies toward efficiency, resilience and sustainability. It also includes evidence from various case studies, which illustrate the core technologies which can potentiality contribute to a sustainable industrial future. The findings show some impressive results concerning the sustainable implications of the digitalization of manufacturing processes. If the predicted benefits can be achieved through digital technologies, they could massively impact on sustainability. \ua9 2019 The Authors. Published by Elsevier B.V

Peaked T - Waves and Sinus Arrhythmia Before Prolonged Sinus Pauses and Atrioventricular Block in Guillain-Barre Syndrome

An 18-year-old woman presented with a rapidly progressive ascending flaccid paralysis and numbness requiring mechanical ventilation after an upper respiratory infection. Guillain-Barre Syndrome was diagnosed based on albumino-cytologic dissociation in the cerebrospinal fluid (elevated proteins with normal white blood cell count) and a demyelinating sensory-motor polyneuropathy pattern on the electromyogram. She was initially treated with intravenous immunoglobulin, but later required plasmapheresis for non-resolution of symptoms

Investigation on Self-Admitted Technical Debt in Open-Source Blockchain Projects

Technical debt refers to decisions made during the design and development of software that postpone the resolution of technical problems or the enhancement of the software's features to a later date. If not properly managed, technical debt can put long-term software quality and maintainability at risk. Self-admitted technical debt is defined as the addition of specific comments to source code as a result of conscious and deliberate decisions to accumulate technical debt. In this paper, we will look at the presence of self-admitted technical debt in open-source blockchain projects, which are characterized by the use of a relatively novel technology and the need to generate trust. The self-admitted technical debt was analyzed using NLP techniques for the classification of comments extracted from the source code of ten projects chosen based on capitalization and popularity. The analysis of self-admitted technical debt in blockchain projects was compared with the results of previous non-blockchain open-source project analyses. The findings show that self-admitted design technical debt outnumbers requirement technical debt in blockchain projects. The analysis discovered that some projects had a low percentage of self-admitted technical debt in the comments but a high percentage of source code files with debt. In addition, self-admitted technical debt is on average more prevalent in blockchain projects and more equally distributed than in reference Java projects.If not managed, the relatively high presence of detected technical debt in blockchain projects could represent a threat to the needed trust between the blockchain system and the users. Blockchain projects development teams could benefit from self-admitted technical debt detection for targeted technical debt management

One, no one and one hundred thousand events: Defining and processing events in an inter-disciplinary perspective

We present an overview of event definition and processing spanning 25 years of research in NLP. We first provide linguistic background to the notion of event, and then present past attempts to formalize this concept in annotation standards to foster the development of benchmarks for event extraction systems. This ranges from MUC-3 in 1991 to the Time and Space Track challenge at SemEval 2015. Besides, we shed light on other disciplines in which the notion of event plays a crucial role, with a focus on the historical domain. Our goal is to provide a comprehensive study on event definitions and investigate which potential past efforts in the NLP community may have in a different research domain. We present the results of a questionnaire, where the notion of event for historians is put in relation to the NLP perspective

Sustainability in Blockchain Development: A BERT-Based Analysis of Ethereum Developer Discussions

Blockchain technology faces significant challenges related to sustainability, including issues with optimisation, as well as high energy and gas consumption - factors that developers may sometimes neglect. We introduce a methodology to analyse the key sustainability topics discussed by Go-Ethereum developers, using thematic analysis of their issues and comments from Github. Our approach uses the BERT model to conduct an in-depth topic analysis, enabling us to study the underlying themes and trends in developer's conversations regarding energy use and sustainability. We assess the sustainability of the identified topics using the five dimensions outlined in the Sustainability Awareness Framework (SusAF): economic, social, individual, environmental, and technical. Our goal is to shed light on how much attention developers pay to sustainability and energy consumption issues. The findings from this qualitative analysis aim to encourage technologists to incorporate these considerations into their future projects, in order to achieve better outcomes in terms of sustainability and reduced consumption