In situ-formed nitrogen-doped carbon/silicon-based materials as negative electrodes for lithium-ion batteries

The development of negative electrode materials with better performance than those currently used in Li-ion technology has been a major focus of recent battery research. Here, we report the synthesis and electrochem-ical evaluation of in situ-formed nitrogen-doped carbon/SiOC. The materials were synthesized by a sol-gel pro-cess using 3-(aminopropyl)triethoxysilane (APTES), sodium citrate and glycerol. The electrochemical performance of pyrolyzed materials was studied using poly(acrylic acid) binder and commercial organic elec-trolyte. Our reported approach enables changes in both the amount of nitrogen and the morphology as a func-tion of the molar ratio of APTES:citrate and reaction time. Spherical-shaped NC/SiOC composite electrodes deliver a delithiation capacity of 622 mAh/g at 0.1 A/g and an initial coulombic efficiency of-63%, while in the large bulk material, respective values of 367 mAh/g and-55% were obtained. After 1000 charge/dis-charge cycles at 1.6 A/g, the latter material exhibits 98% of the initial capacity once it returned to lower cur-rent cycling. Overall, our results indicate that NC/SiOC materials are quite promising for electrochemical applications since both their large capacity and stability demonstrate superior performance compared to tradi-tional graphite. Moreover, our synthesis is simple and, more importantly, environmentally friendly chemicals, such as sodium citrate and glycerol, are used.Peer reviewe

A homogenization study of the effects of cycling on the electronic conductivity of commercial lithium-ion battery cathodes

State-of-the-art image acquisition, image analysis, and modern homogenization theory are used to study the effects of cycling on commercial lithium-ion battery cathodes’ ability to conduct electronic current. This framework allows for a rigorous computation of an effective, or macroscale, electronic conductivity given an arbitrarily complicated three-dimensional microstructure comprised of three different material phases, i.e., active material, binder (polymer mixed with conductive carbon black), and electrolyte. The approach explicitly takes into account the geometry and is thus a vast improvement over the commonly used Bruggeman approximation. We apply our framework to two different types of lithium-ion battery cathodes before and after cycling. This leads us to predict an appreciable decrease in the effective electronic conductivity as a direct result of cycling. In addition, we present an ad-hoc “neighbor counting” methodology which meaningfully quantifies the effect of binder detaching from the surface of the active material due to the internal mechanical stresses experienced under operating conditions, thereby supporting the results of the homogenization calculations

Measures used to assess interventions for increasing patient involvement in Danish healthcare setting: a rapid review

Objective: To identify measures used within Denmark evaluating any type of intervention designed to facilitate patient involvement in healthcare. Design: Environmental scan employing rapid review methods. Data sources: MEDLINE, PsycInfo and CINAHL were searched from 6–9 April 2021 from database inception up to the date of the search. Eligibility criteria: Quantitative, observational and mixed methods studies with empirical data on outcomes used to assess any type of intervention aiming to increase patient involvement with their healthcare. Language limitations were Danish and English. Data extraction and synthesis: Two independent reviewers extracted data from 10% of the included studies and, due to their agreement, the data from the rest were extracted by first author. Data were analysed with reference to existing categories of measuring person-centred care; findings were synthesised using narrative summaries. Adapted Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines were used to guide reporting. Results: Among 3767 records, 43 studies met the inclusion criteria, including 74 different measures used to evaluate interventions aimed at increasing patient involvement within healthcare in Danish hospital and community settings. Generic measures assessed: patient engagement (n=3); supporting self-management (n=8); supporting shared decision-making (n=9); patient satisfaction and experiences of care (n=11); health-related patient-reported outcome (n=20). Conclusions: Across Denmark, complex interventions designed to improve patient involvement with healthcare vary in their goals and content. Some targeting healthcare professionals, some patient health literacy and some service infrastructure. A plethora of measures assess the impact of these interventions on patient, professional and service delivery outcomes. Few measures assessed patient involvement directly, and it is unclear which proxy measures capture indicators of perceived involvement. Lack of conceptual clarity between intervention goals, the components of change and measures makes it difficult to see what types of intervention can best support change in services to ensure patients are more effectively involved in their healthcare

Distance-Based Access Modifiers Applied to Safety in Home Networks

Abstract. Home networks and the interconnection of home appliances is a classical theme in ubiquitous computing research. Security is a recurring concern, but there is a lack of awareness of safety: preventing the computerized house from harming the inhabitants, even in a worst-case scenario where an unauthorized user gains remote control of the facilities. We address this safety issue at the middleware level by restricting the operations that can be performed on devices according to the physical location of the user initiating the request. Operations that pose a potential safety hazard can only be performed within a physical proximity that ensures safety. We use a declarative approach integrated with an IDL language to express location-based restrictions on operations. This model has been implemented in a middleware for home audio-video devices, using infrared communication and a local-area network to implement location awareness.