Multi-dimensional microwave sensing using graphene waveguides

This paper presents an electrolytically gated broadband microwave sensor where atomically-thin graphene layers are integrated into coplanar waveguides and coupled with microfluidic channels. The interaction between a solution under test and the graphene surface causes material and concentration-specific modifications of graphene's DC and AC conductivity. Moreover, wave propagation in the waveguide is modified by the dielectric properties of materials in its close proximity via the fringe field, resulting in a combined sensing mechanism leading to an enhanced S-parameter response compared to metallic microwave sensors. The possibility of further controlling the graphene conductivity via an electrolytic gate enables a new, multi-dimensional approach merging chemical field-effect sensing and microwave measurement methods. By controlling and synchronizing frequency sweeps, electrochemical gating and liquid flow in the microfluidic channel, we generate multidimensional datasets that enable a thorough investigation of the solution under study. As proof of concept, we functionalize the graphene surface in order to identify specific single-stranded DNA sequences dispersed in phosphate buffered saline solution. We achieve a limit of detection of ~1 attomole per litre for a perfect match DNA strand and a sensitivity of ~3 dB/decade for sub-pM concentrations. These results show that our devices represent a new and accurate metrological tool for chemical and biological sensing

Improving Neurosurgery Education Using Social Media Case-Based Discussions: A Pilot Study.

BACKGROUND: The increasing shift toward a more generalized medical undergraduate curriculum has led to limited exposure to subspecialties, including neurosurgery. The lack of standardized teaching may result in insufficient coverage of core learning outcomes. Social media (SoMe) in medical education are becoming an increasingly accepted and popular way for students to meet learning objectives outside formal medical school teaching. We delivered a series of case-based discussions (CbDs) over SoMe to attempt to meet core learning needs in neurosurgery and determine whether SoMe-based CbDs were an acceptable method of education. METHODS: Twitter was used as a medium to host 9 CbDs pertaining to common neurosurgical conditions in practice. A sequence of informative and interactive tweets were formulated before live CbDs and tweeted in progressive order. Demographic data and participant feedback were collected. RESULTS: A total of 277 participants were recorded across 9 CbDs, with 654,584 impressions generated. Feedback responses were received from 135 participants (48.7%). Participants indicated an increase of 77% in their level of knowledge after participating. Of participants, 57% (n = 77) had previous CbD experience as part of traditional medical education, with 62% (n = 84) receiving a form of medical education previously through SoMe. All participants believed that the CbDs objectives were met and would attend future sessions. Of participants, 99% (n = 134) indicated that their expectations were met. CONCLUSIONS: SoMe has been shown to be a favorable and feasible medium to host live, text-based interactive CbDs. SoMe is a useful tool for teaching undergraduate neurosurgery and is easily translatable to all domains of medicine and surgery

Crystal Orientation Dependent Oxidation Modes at the Buried Graphene-Cu Interface.

We combine spatially resolved scanning photoelectron spectroscopy with confocal Raman and optical microscopy to reveal how the oxidation of the buried graphene-Cu interface relates to the Cu crystallographic orientation. We analyze over 100 different graphene covered Cu (high and low index) orientations exposed to air for 2 years. Four general oxidation modes are observed that can be mapped as regions onto the polar plot of Cu surface orientations. These modes are (1) complete, (2) irregular, (3) inhibited, and (4) enhanced wrinkle interface oxidation. We present a comprehensive characterization of these modes, consider the underlying mechanisms, compare air and water mediated oxidation, and discuss this in the context of the diverse prior literature in this area. This understanding incorporates effects from across the wide parameter space of 2D material interface engineering, relevant to key challenges in their emerging applications, ranging from scalable transfer to electronic contacts, encapsulation, and corrosion protection

Frequent attendance at the emergency department shows typical features of complex systems : analysis of multicentre linked data

Objective: Frequent attendance at the ED is a worldwide problem. We hypothesised that frequent attendance could be understood as a feature of a complex system comprising patients, healthcare and society. Complex systems have characteristic statistical properties, with stable patterns at the level of the system emerging from unstable patterns at the level of individuals who make up the system. Methods: Analysis of a linked dataset of routinely collected health records from all 13 hospital trusts providing ED care in the Yorkshire and Humber region of the UK (population 5.5 million). We analysed the distribution of attendances per person in each of 3 years and measured the transition of individual patients between frequent, infrequent and non-attendance. We fitted data to power law distributions typically seen in complex systems using maximum likelihood estimation. Results: The data included 3.6 million attendances at EDs in 13 hospital trusts. 29/39 (74.3%) analyses showed a statistical fit to a power law; 2 (5.1%) fitted an alternative distribution. All trusts’ data fitted a power law in at least 1 year. Differences over time and between hospital trusts were small and partly explained by demographics. In contrast, individual patients’ frequent attendance was unstable between years. Conclusions: ED attendance patterns are stable at the level of the system, but unstable at the level of individual frequent attenders. Attendances follow a power law distribution typical of complex systems. Interventions to address ED frequent attendance need to consider the whole system and not just the individual frequent attenders

Tunable Anion-Selective Transport through Monolayer Graphene and Hexagonal Boron Nitride.

Membranes that selectively filter for both anions and cations are central to technological applications from clean energy generation to desalination devices. 2D materials have immense potential as these ion-selective membranes due to their thinness, mechanical strength, and tunable surface chemistry; however, currently, only cation-selective membranes have been reported. Here we demonstrate the controllable cation and anion selectivity of both monolayer graphene and hexagonal boron nitride. In particular, we measure the ionic current through membranes grown by chemical vapor deposition containing well-known defects inherent to scalably produced and wet-transferred 2D materials. We observe a striking change from cation selectivity with monovalent ions to anion selectivity by controlling the concentration of multivalent ions and inducing charge inversion on the 2D membrane. Furthermore, we find good agreement between our experimental data and theoretical predictions from the Goldman-Hodgkin-Katz equation and use this model to extract selectivity ratios. These tunable selective membranes conduct up to 500 anions for each cation and thus show potential for osmotic power generation

A Peeling Approach for Integrated Manufacturing of Large Mono-Layer h-BN Crystals

Hexagonal boron nitride (h-BN) is the only known material aside from graphite with a structure composed of simple, stable, non-corrugated atomically thin layers. While historically used as lubricant in powder form, h-BN layers have become particularly attractive as an ultimately thin insulator, barrier or encapsulant. Practically all emerging electronic and photonic device concepts rely on h-BN exfoliated from small bulk crystallites, which limits device dimensions and process scalability. We here focus on a systematic understanding of Pt catalysed h-BN crystal formation, in order to address this integration challenge for mono-layer h-BN via an integrated chemical vapour deposition (CVD) process that enables h-BN crystal domain sizes exceeding 0.5 mm and a merged, continuous layer in a growth time less than 45 min. Theprocess makes use commercial, reusable Pt foils, and allows a delamination process for easy and clean h-BN layer transfer. We demonstrate sequential pick-up for the assembly of graphene/h-BN heterostructures with atomic layer precision, while minimizing interfacial contamination. The approach can be readily combined with other layered materials and enables the integration of CVD h-BN into high quality, reliable 2D material device layer stacks

The 10‐year trajectory of aggressive behaviours in autistic individuals

Background: Aggressive behaviours are common in people with neurodevelopmental conditions, contributing to poorer quality of life and placement breakdown. However, there is limited empirical research documenting the prevalence and persistence of aggressive behaviours in autism. In this longitudinal study, aggressive behaviours were investigated in a sample of autistic individuals over 10 years. Methods: Caregivers of autistic individuals, both with and without intellectual disability, completed questionnaires relating to the presence of aggressive behaviours at T1 [N = 229, mean age in years 11.8, standard deviation (SD) 5.9], T2 (T1 + 3 years, N = 81, mean age in years 15.1, SD 5.9) and T3 (T1 + 10 years, N = 54, mean age in years 24.5, SD 8.1). Analyses examined the presence and persistence of aggressive behaviours and the predictive value of established correlates of aggression. Results: Aggressive behaviours were common at baseline (61.6%) but only persistent in 30% of the sample over 10 years. Higher composite scores of overactivity and impulsivity at T1 were significantly associated with the persistence of aggressive behaviours at T2 (P = 0.027) and T3 (P = 0.012) with medium effect size. Conclusions: Aggressive behaviours are common in autism, but reduce with age. Behavioural correlates of attention deficit hyperactivity disorder (ADHD) predict the presence and persistence of aggressive behaviour and as such may be useful clinical indicators to direct proactive intervention resources to ameliorate aggressive behaviours

A Deep Learning Approach to Classify Surgical Skill in Microsurgery Using Force Data from a Novel Sensorised Surgical Glove

Microsurgery serves as the foundation for numerous operative procedures. Given its highly technical nature, the assessment of surgical skill becomes an essential component of clinical practice and microsurgery education. The interaction forces between surgical tools and tissues play a pivotal role in surgical success, making them a valuable indicator of surgical skill. In this study, we employ six distinct deep learning architectures (LSTM, GRU, Bi-LSTM, CLDNN, TCN, Transformer) specifically designed for the classification of surgical skill levels. We use force data obtained from a novel sensorized surgical glove utilized during a microsurgical task. To enhance the performance of our models, we propose six data augmentation techniques. The proposed frameworks are accompanied by a comprehensive analysis, both quantitative and qualitative, including experiments conducted with two cross-validation schemes and interpretable visualizations of the network’s decision-making process. Our experimental results show that CLDNN and TCN are the top-performing models, achieving impressive accuracy rates of 96.16% and 97.45%, respectively. This not only underscores the effectiveness of our proposed architectures, but also serves as compelling evidence that the force data obtained through the sensorzsed surgical glove contains valuable information regarding surgical skill

Isolation of human intrahepatic leukocytes for phenotypic and functional characterization by flow cytometry

With the growing appreciation of tissue-resident immunity, studying tissue-specific immune cells contributing to both homeostasis and disease is imperative. Here, we provide a protocol for the isolation of human intrahepatic leukocytes (IHL) maximizing viability, purity, and yield. Our protocol is scalable by tissue weight, allowing for reproducible and efficient IHL liberation suitable for functional characterization, cell isolation, and profiling by flow (or mass) cytometry. Furthermore, we provide a "guide" to determine an expected IHL yield per gram of tissue processed. For complete details on the use and execution of this protocol, please refer to Stegmann et al. (2016), Pallett et al. (2017), Easom et al. (2018), Swadling et al. (2020), Pallett et al. (2020), and Zakeri et al. (2022)