Impact of solid-electrolyte interphase reformation on capacity loss in silicon-based lithium-ion batteries

High-density silicon composite anodes show large volume changes upon charging/discharging triggering the reformation of the solid electrolyte interface (SEI), an interface initially formed at the silicon surface. The question remains how the reformation process and accompanied material evolution, in particular for industrial up-scalable cells, impacts cell performance. Here, we develop a correlated workflow incorporating X-ray microscopy, field-emission scanning electron microscopy tomography, elemental imaging and deep learning-based microstructure quantification suitable to witness the structural and chemical progression of the silicon and SEI reformation upon cycling. The nanometer-sized SEI layer evolves into a micron-sized silicon electrolyte composite structure at prolonged cycles. Experimental-informed electrochemical modelling endorses an underutilisation of the active material due to the silicon electrolyte composite growth affecting the capacity. A chemo-mechanical model is used to analyse the stability of the SEI/silicon reaction front and to investigate the effects of material properties on the stability that can affect the capacity loss

Impact of solid-electrolyte interphase reformation on capacity loss in silicon-based lithium-ion batteries

High-density silicon composite anodes show large volume changes upon charging/discharging triggering the reformation of the solid electrolyte interface (SEI), an interface initially formed at the silicon surface. The question remains how the reformation process and accompanied material evolution, in particular for industrial up-scalable cells, impacts cell performance. Here, we develop a correlated workflow incorporating X-ray microscopy, field-emission scanning electron microscopy tomography, elemental imaging and deep learning-based microstructure quantification suitable to witness the structural and chemical progression of the silicon and SEI reformation upon cycling. The nanometer-sized SEI layer evolves into a micron-sized silicon electrolyte composite structure at prolonged cycles. Experimental-informed electrochemical modelling endorses an underutilisation of the active material due to the silicon electrolyte composite growth affecting the capacity. A chemo-mechanical model is used to analyse the stability of the SEI/silicon reaction front and to investigate the effects of material properties on the stability that can affect the capacity loss

Fast Message Franking: From Invisible Salamanders to Encryptment

Message franking enables cryptographically verifiable reporting of abusive content in end-to-end encrypted messaging. Grubbs, Lu, and Ristenpart recently formalized the needed underlying primitive, what they call compactly committing authenticated encryption (AE), and analyzed the security of a number of approaches. But all known secure schemes are still slow compared to the fastest standard AE schemes. For this reason Facebook Messenger uses AES-GCM for franking of attachments such as images or videos. We show how to break Facebook’s attachment franking scheme: a malicious user can send an objectionable image to a recipient but that recipient cannot report it as abuse. The core problem stems from use of fast but non-committing AE, and so we build the fastest compactly committing AE schemes to date. To do so we introduce a new primitive, called encryptment, which captures the essential properties needed. We prove that, unfortunately, schemes with performance profile similar to AES-GCM won’t work. Instead, we show how to efficiently transform Merkle-Damgärd-style hash functions into secure encryptments, and how to efficiently build compactly committing AE from encryptment. Ultimately our main construction allows franking using just a single computation of SHA-256 or SHA-3. Encryptment proves useful for a variety of other applications, such as remotely keyed AE and concealments, and our results imply the first single-pass schemes in these settings as well

Hemodynamic, ventilator, and ECG changes in pediatric patients undergoing extraction

Background: Dental treatment induces pain anxiety and fear. This study was conducted to assess the changes in hemodynamic, ventilator, and electrocardiograph changes during extraction procedure among 12-15-year-old children and compare these changes with anxiety, fear, and pain. Materials and Methods: A purposive sample of 60 patients selected based on inclusion and exclusion criteria underwent study procedure in the dental OPD of a medical college and hospital. The anxiety, fear, and pain were recorded by dental anxiety scale, dental fear scale, and visual analogue scale, respectively, before the start of the procedure. The systolic blood pressure, diastolic blood pressure, heart rate, oxygen saturation, and electrocardiogram changes were monitored during the extraction procedure. The recording was taken four times (preinjection phase, injection, extraction, and postextraction) and was analyzed. Results: At the preinjection phase the mean vales were systolic blood pressure (128 ± 11.2), diastolic blood pressure (85.7 ± 6.3), heart rate (79.7 ± 9.3), and oxygen saturation (97.9 ± 5.8). These values increased in injection phases and decreased in extraction phase and the least values were found after 10 min of procedure and this relation was significant for all parameters except oxygen saturation (P = 0.48, NS). ECG abnormalities were seen among 22 patients and were significant before and after injection of Local anesthetic (P = 0.0001, S). Conclusions: Anxiety, fear, and pain have an effect on hemodynamic, ventilator, and cardiovascular parameters during the extraction procedure and hence behavioral management has to be emphasized among children in dental clinics

Design and Analysis of FPGA-based PUFs with Enhanced Performance for Hardware-oriented Security

This article presents a thorough analysis of two distinct Physically Unclonable Functions (PUF), namely RO-PUF (Ring oscillator-based PUF) and RS-LPUF (RS Latch-based PUF), prototyped on FPGA. It is shown that the implemented PUFs possess significantly enhanced performance when compared to the state of the art. It is also identified that the enhancements are achieved through the incorporation of Programmable Delay Lines of FPGA Lookup Tables, the Temporal Majority Voting (TMV) scheme, and placed macro techniques for routing and placements of PUF units. The prototypes developed on Xilinx Artix-7 FPGAs are used for validation over the rated temperature range of 0-85° C with ±5% variation in the supply voltage. The proposed schemes when evaluated experimentally also achieve good uniformity, bit-aliasing, uniqueness, and reliability. Finally, it is shown that the proposed designs outperform the existing conventional PUFs in the area and speed tradeoff. </jats:p