922017 research outputs found
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A Novel Borinate Ester Copolymer for Poly(Frustrated Lewis Pair) Gels
No full textThe versatile chemistry of boronic acid and boronate ester containing polymers has led to key applications in drug delivery, chemical sensing, and dynamic materials. However, their use in polymeric Frustrated Lewis pair (FLP) remains unreported. In this paper we report the synthesis of a novel fluorinated borinate ester copolymer which, when combined with a suitable Lewis basic copolymer, generates polymeric FLP network capable of responsive gelation. The borinate ester moiety, bis(pentafluorophenyl)borinic acid tetrafluorophenyl ester, was affixed to a polystyrene copolymer by a two-step post-polymerisation modification, which can be easily upscaled and purified. The Gutmann-Beckett method suggests these fluorinated borinate ester moieties are amongst the most Lewis acidic boron-containing polymers reported to date. Upon mixing with a Lewis basic copolymer poly(styrene-co-p-diphenylphosphino styrene), gelation cannot be achieved due to steric hindrance around the Lewis centres. However, network formation can be triggered by addition of small molecules such as diethylazodicarboxylate (DEAD) and cyclic ethers. The physical parameters and nature of the crosslinks of the gels prepared from different crosslinkers were probed by rheology. All networks demonstrated strong elastic behaviour, corresponding to covalently crosslinked materials. DEAD crosslinked gels displayed different behaviour to those triggered by cyclic ethers, indicating that mechanism of small molecule activation also plays an important role in the mechanical properties of poly(FLP) gels
Energy consumption and performance optimisation of laser cleaning for coating removal
No full textSelective removal of coatings by lasers can facilitate the reuse of coated tools in a circular economy. In order to optimise and control the process, it is essential to study the impact of process input variables on process performance. In this paper, coating removal from tooling was carried out using a picosecond a pulsed fibre laser, in order to investigate the effects of laser pulse energy, pulse frequency, galvo scanning speed and scanning track stepover. A fractional factorial design of experiments and analysis of variance was used to optimise the process; considering cleaning rate, specific energy consumption and surface integrity as assessed by changes in surface roughness and composition of the tooling after laser cleaning. The results shows synergy between cleaning rate and specific energy with the laser pulse frequency and galvo scanning speed as the two most significant factors, while the laser pulse energy had the greatest contribution to changes in surface composition. Based on extensive experiments, the relationship between processing rate and system specific energy consumption was mathematically modelled. The paper contributes a new specific energy model for laser cleaning and provides a benchmark of the process energy requirements compared to other manufacturing processes. Additionally, the generic scientific learning from this is that the rate of energy input is a key tool for maximising cleaning rate and minimising specific energy requirements, while the intensity of energy applied, is a key metric that influences surface integrity. More complex factors, influence the surface integrity.</p
Hybrid Autoregressive Inference for Scalable Multi-hop Explanation Regeneration
No full textRegenerating natural language explanations in the scientific domain has been proposed as a benchmark to evaluate complex multi-hop and explainable inference. In this context, large language models can achieve state-of-the-art performance when employed as cross-encoder architectures and fine-tuned on human-annotated explanations. However, while much attention has been devoted to the quality of the explanations, the problem of performing inference efficiently is largely under-studied. Cross-encoders, in fact, are intrinsically not scalable, possessing limited applicability to real world scenarios that require inference on massive facts banks.To enable complex multi-hop reasoning at scale, this paper focuses on bi-encoder architectures, investigating the problem of scientific explanation regeneration at the intersection of dense and sparse models. Specifically, we present SCAR (for Scalable Autoregressive Inference), a hybrid framework that iteratively combines a Transformer-based bi-encoder with a sparse model of explanatory power, designed to leverage explicit inference patterns in the explanations. Our experiments demonstrate that the hybrid framework significantly outperforms previous sparse models, achieving performance comparable with that of state-of-the-art cross-encoders while being ≈ 50 times faster and scalable to corpora of millions of facts. Further analyses on semantic drift and multi-hop question answering reveal that the proposed hybridisation boosts the quality of the most challenging explanations, contributing to improved performance on downstream inference tasks
Self-report measures of secure attachment in adulthood: A systematic review:Self-report adult secure attachment measures
No full textBackground: Secure attachment in adulthood is associated with many markers of adaptive functioning. Valid and reliable self-report measures of attachment security could provide a practical tool to help advance strengths-based research and clinical work. Previous reviews have not specifically examined the psychometric properties of self-report instruments with respects to secure attachment, or systematically appraised the methodological quality of relevant validation studies. Method: A systematic review was completed in accordance with the COSMIN guidelines for reviews of patient-reported outcome measures. The methodological quality of individual studies was evaluated, and results were rated against criteria for good measurement properties. Results: 40 studies were included in the review, which collectively reported on 24 self-report instruments. The methodological quality of individual studies was variable, and no single instrument was identified as having sufficient evidence of a range of psychometric properties. However, the Attachment Style Questionnaire – Short Form (ASQ-SF), the Cartes-Modèles Individuels de Relations (CAMIR), Cartes-Modèles Individuels de Relations-Reduced (CAMIR-R), and the Psychological Treatment Inventory – Attachment Style Scales (PTI-ASS) had the most robust evidence for the properties assessed.Conclusion: Existing self-report measures assessing adult secure attachment have limited psychometric support. More methodologically robust studies of content validity, reliability, measurement invariance, and construct validity in particular are needed. <br/
Design of Flexible Meander Line Antenna for Healthcare for Wireless Medical Body Area Networks
No full texta flexible meander line monopole antenna (MMA) is presented in this paper. The antenna can be worn for on-and off-body applications. The overall dimension of the MMA is 37 mm 50 mm 2.37 mm3. The MMA was manufactured and measured, and the results matched with simulation results. The MMA design shows a bandwidth of up to 1282.4 (450.5) MHz and provides gains of 3.03 (4.85) dBi in the lower and upper operating bands, respectively, showing omnidirectional radiation patterns in free space. While worn on the chest or arm, bandwidths as high as 688.9 (500.9) MHz and 1261.7 (524.2) MHz, and the gains of 3.80 (4.67) dBi and 3.00 (4.55) dBi were observed. The experimental measurements of the read range confirmed the results of the coverage range of up to 11 meters
Impact of migrant and returning farmer professionalization on food production diversity
No full textSince the 2000s, there has been an increasing number of returning and migrant farmers across China. In 2012, China initiated a program for fostering professional farmers, which has caused greater changes for farmers and led to an agricultural shift towards commercial production. Migration has been recognized as a crucial factor affecting the diversity of agricultural production. However, scant attention has been paid to how different types of farmers influence agricultural diversification. Therefore, this study examines the influence of migrant farmers, returning farmers, and local non-migrant farmers on food production diversity. This study collected farm-level data on food production and farmers’ characteristics and applied a negative binomial regression model to estimate the impacts of different types of farmers on agricultural development. The results show that farms operated by migrant farmers had a significantly lower level of food production diversity while farms operated by returning farmers had no significant difference in food production diversity, using farms operated by local non-migrant farmers as the reference category. The variation in agricultural production diversity lies in differences in food production purposes, agricultural and market skills, and various risk-related capacities among the different types of farmers. Farm-level production specialization does not necessarily reduce food diversity and agrobiodiversity at the rural community and regional level
Approximation of Wave Packets on the Real Line
No full textIn this paper we compare three different orthogonal systems in L2(R) which can be used in the construction of a spectral method for solving the semi-classically scaled time dependent Schrödinger equation on the real line, specifically, stretched Fourier functions, Hermite functions and Malmquist–Takenaka functions. All three have banded skew-Hermitian differentiation matrices, which greatly simplifies their implementation in a spectral method, while ensuring that the numerical solution is unitary – this is essential in order to respect the Born interpretation in quantum mechanics and, as a byproduct, ensures numerical stability with respect to the L2(R) norm. We derive asymptotic approximations of the coefficients for a wave packet in each of these bases, which are extremely accurate in the high frequency regime. We show that the Malmquist–Takenaka basis is superior, in a practical sense, to the more commonly used Hermite functions and stretched Fourier expansions for approximating wave packets