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Authors = Stephen Foster

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16 pages, 2457 KiB  
Article
Neural Correlates of Cognitive Disengagement Syndrome Symptoms in Children: A Magnetoencephalography Study
by Xiaoqian Yu, Jing Xiang, Jeffery N. Epstein, Leanne Tamm, Josalyn A. Foster and Stephen P. Becker
Brain Sci. 2025, 15(6), 624; https://doi.org/10.3390/brainsci15060624 - 10 Jun 2025
Viewed by 621
Abstract
Background/Objectives: Despite the growing recognition of cognitive disengagement syndrome (CDS), previously termed sluggish cognitive tempo, as a distinct dimension of psychopathology, the neural correlates of CDS remain largely unknown. We investigated the neural correlates of CDS in children using whole-head magnetoencephalography (MEG). Methods [...] Read more.
Background/Objectives: Despite the growing recognition of cognitive disengagement syndrome (CDS), previously termed sluggish cognitive tempo, as a distinct dimension of psychopathology, the neural correlates of CDS remain largely unknown. We investigated the neural correlates of CDS in children using whole-head magnetoencephalography (MEG). Methods: A community-based sample of children (N = 43, ages 8–12 years) was recruited and completed self-report ratings of CDS. MEG was recorded while the children completed an adapted version of the attention network test (ANT). Results: The results indicated that higher levels of self-reported CDS symptoms were associated with larger changes in the root-mean square (ΔRMS) (incongruent—congruent trials) in M2 and M3, suggesting children with higher levels of CDS symptoms might require greater mental effort to overcome distractors during incongruent trials. The source localization analysis initially revealed a negative correlation between child self-reported CDS symptoms and ΔM2 power (incongruent—congruent trials) in the medial prefrontal cortex (mPFC), suggesting insufficient power allocation in a region critical for attentional processing. However, this association was no longer significant after controlling for ADHD status. No significant correlation was found between self-reported CDS symptoms and alerting or orienting. Conclusions: These findings provide initial evidence of the disrupted attentional processing associated with CDS in children. Further replication and extension with larger samples are warranted. Full article
(This article belongs to the Section Cognitive, Social and Affective Neuroscience)
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20 pages, 12505 KiB  
Article
Quality Investigation of Pultruded Carbon Fiber Panels Subjected to Four-Point Flexure via Fiber Optic Sensing
by Zachariah Arwood, Stephen Young, Darren Foster and Dayakar Penumadu
Materials 2025, 18(1), 166; https://doi.org/10.3390/ma18010166 - 3 Jan 2025
Viewed by 1043
Abstract
Pultruded carbon fiber-reinforced composites are attractive to the wind energy industry due to the rapid production of highly aligned unidirectional composites with enhanced fiber volume fractions and increased specific strength and stiffness. However, high volume carbon fiber manufacturing remains cost-prohibitive. This study investigates [...] Read more.
Pultruded carbon fiber-reinforced composites are attractive to the wind energy industry due to the rapid production of highly aligned unidirectional composites with enhanced fiber volume fractions and increased specific strength and stiffness. However, high volume carbon fiber manufacturing remains cost-prohibitive. This study investigates the feasibility of a pultruded low-cost textile carbon fiber-reinforced epoxy composite as a promising material in spar cap production was undertaken based on mechanical response to four-point flexure loading. As spar caps are primarily subjected to flexural loading, large-span four-point flexure was considered, and coupon testing was restricted to tensile modulus and compression strength assessment. High-resolution spatial fiber optic strain sensing was utilized to determine spatial strain distribution during four-point flexure, revealing consistent strain along the length of the part and proved to be an excellent option for process manufacturing quality examination. Additionally, holes with diameters of 2.49 mm, 5.08 mm, and 1.93 mm were drilled through the thickness of full-width parts to determine the feasibility of structural health monitoring of pultruding parts internal to wind blades via fiber optic strain sensing. Full article
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9 pages, 252 KiB  
Review
Updates on Systemic Immunomodulation in Peripheral Ulcerative Keratitis
by Arash Maleki, Tate Valerio, Yasmin Massoudi, Maria L. Ruggeri, C. Stephen Foster and Stephen D. Anesi
J. Clin. Transl. Ophthalmol. 2024, 2(4), 131-139; https://doi.org/10.3390/jcto2040011 - 23 Oct 2024
Viewed by 1939
Abstract
Peripheral ulcerative keratitis (PUK) is an inflammatory process causing thinning of the cornea, epithelial defect, and inflammatory infiltrates and is caused by several etiologies. This sight-threatening condition can indicate the presence of potentially fatal underlying systemic conditions, and, accordingly, warrants thorough investigation upon [...] Read more.
Peripheral ulcerative keratitis (PUK) is an inflammatory process causing thinning of the cornea, epithelial defect, and inflammatory infiltrates and is caused by several etiologies. This sight-threatening condition can indicate the presence of potentially fatal underlying systemic conditions, and, accordingly, warrants thorough investigation upon clinical presentation and immediate intervention in order to mitigate disease progression. This review aims to provide an update on the current diagnostic and management landscape for PUK, specifically with immunomodulatory methods in cases of noninfectious etiologies. A literature search was conducted to develop a nuanced, evidence-based perspective in which we present our preferred approaches. There are currently a number of viable options, following which a “stepladder” method is typically employed, where treatment methods are escalated as a result of inadequate clinical response to lower-level interventions. This method balances efficacy with the potential side effects of immunomodulatory medications. Ultimately, carefully monitored treatment regimens are needed to mitigate visual impairment in patients with PUK, and efforts must be made to achieve steroid-free remission to avoid the known side effects of long-term corticosteroid use. Full article
51 pages, 1461 KiB  
Review
Survey of Advanced Nonlinear Control Strategies for UAVs: Integration of Sensors and Hybrid Techniques
by Nadir Abbas, Zeshan Abbas, Samra Zafar, Naseem Ahmad, Xiaodong Liu, Saad Saleem Khan, Eric Deale Foster and Stephen Larkin
Sensors 2024, 24(11), 3286; https://doi.org/10.3390/s24113286 - 21 May 2024
Cited by 9 | Viewed by 3581
Abstract
This survey paper explores advanced nonlinear control strategies for Unmanned Aerial Vehicles (UAVs), including systems such as the Twin Rotor MIMO system (TRMS) and quadrotors. UAVs, with their high nonlinearity and significant coupling effects, serve as crucial benchmarks for testing control algorithms. Integration [...] Read more.
This survey paper explores advanced nonlinear control strategies for Unmanned Aerial Vehicles (UAVs), including systems such as the Twin Rotor MIMO system (TRMS) and quadrotors. UAVs, with their high nonlinearity and significant coupling effects, serve as crucial benchmarks for testing control algorithms. Integration of sophisticated sensors enhances UAV versatility, making traditional linear control techniques less effective. Advanced nonlinear strategies, including sensor-based adaptive controls and AI, are increasingly essential. Recent years have seen the development of diverse sliding surface-based, sensor-driven, and hybrid control strategies for UAVs, offering superior performance over linear methods. This paper reviews the significance of these strategies, emphasizing their role in addressing UAV complexities and outlining future research directions. Full article
(This article belongs to the Special Issue Dalian University of Technology Celebrating 75th Anniversary)
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10 pages, 534 KiB  
Article
The Sleep of Shift Workers in a UK Financial Organisation and Associations with Mental, Physical, Social and Cognitive Health
by Gaby Illingworth, William R. McMahon, Dabhnait Gartland, Stephen Pereira and Russell G. Foster
Clin. Transl. Neurosci. 2023, 7(4), 33; https://doi.org/10.3390/ctn7040033 - 23 Oct 2023
Viewed by 2250
Abstract
Shift workers are vulnerable to circadian misalignment, sleep disturbance and increased risk of impaired health. Studies concerning the sleep and health of individuals working shifts in the financial sector are lacking. We investigated sleep quality, sleep duration and associations with health in a [...] Read more.
Shift workers are vulnerable to circadian misalignment, sleep disturbance and increased risk of impaired health. Studies concerning the sleep and health of individuals working shifts in the financial sector are lacking. We investigated sleep quality, sleep duration and associations with health in a UK financial organisation. Employees (n = 178; 61% male) completed an online survey comprising the SSI, PSQI, GAD-7, PHQ-9, WAFCS, EMQ-R and BMI. Three-quarters of employees reported poor sleep quality. Poorer sleep quality and shorter sleep duration were both associated with greater anxiety and depression symptoms. However, sleep quality demonstrated greater explained variance with symptom severity (anxiety: Rs2 difference = 13.2%; depression: Rs2 difference = 21.8%). Poorer sleep quality was associated with higher BMI, greater work-to-family conflict and poorer everyday memory (rs = 0.26–0.29), while shorter sleep duration was only significantly associated with higher BMI. Sleep quality did not differ depending on the nightshift type (“permanent”/“other”). Sleep achieved was shorter than perceived sleep-need for all consecutive shift types—especially night shifts (40 min–1 h 24 min). This preliminary study suggests that sleep quality, and to a lesser extent sleep duration, are associated with a range of health outcomes for shift workers within the financial sector, highlighting the need to increase organisational awareness of the importance of sleep for employee health. Full article
(This article belongs to the Special Issue Sleep–Wake Medicine)
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26 pages, 936 KiB  
Review
A Survey: Future Smart Cities Based on Advance Control of Unmanned Aerial Vehicles (UAVs)
by Nadir Abbas, Zeshan Abbas, Xiaodong Liu, Saad Saleem Khan, Eric Deale Foster and Stephen Larkin
Appl. Sci. 2023, 13(17), 9881; https://doi.org/10.3390/app13179881 - 31 Aug 2023
Cited by 39 | Viewed by 5596
Abstract
This article presents a survey of unmanned aerial vehicle (UAV) applications in smart cities, emphasizing integration challenges. Smart cities leverage innovative technologies, including the Internet of Things (IoT) and UAVs, to enhance residents’ quality of life. The study highlights UAV applications, challenges, limitations, [...] Read more.
This article presents a survey of unmanned aerial vehicle (UAV) applications in smart cities, emphasizing integration challenges. Smart cities leverage innovative technologies, including the Internet of Things (IoT) and UAVs, to enhance residents’ quality of life. The study highlights UAV applications, challenges, limitations, and future perspectives of smart city development. Advanced control methods for maximizing UAV benefits are discussed. Control theory challenges and issues for the deployment of UAVs are addressed. By concentrating on challenges, potential applications, and advanced control techniques, this paper offers insights into UAVs’ role in shaping the future of smart cities. Full article
(This article belongs to the Special Issue IoT in Smart Cities and Homes)
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31 pages, 2325 KiB  
Review
Online Privacy Fatigue: A Scoping Review and Research Agenda
by Karl van der Schyff, Greg Foster, Karen Renaud and Stephen Flowerday
Future Internet 2023, 15(5), 164; https://doi.org/10.3390/fi15050164 - 28 Apr 2023
Cited by 11 | Viewed by 6042
Abstract
Online users are responsible for protecting their online privacy themselves: the mantra is custodiat te (protect yourself). Even so, there is a great deal of evidence pointing to the fact that online users generally do not act to preserve the privacy of their [...] Read more.
Online users are responsible for protecting their online privacy themselves: the mantra is custodiat te (protect yourself). Even so, there is a great deal of evidence pointing to the fact that online users generally do not act to preserve the privacy of their personal information, consequently disclosing more than they ought to and unwisely divulging sensitive information. Such self-disclosure has many negative consequences, including the invasion of privacy and identity theft. This often points to a need for more knowledge and awareness but does not explain why even knowledgeable users fail to preserve their privacy. One explanation for this phenomenon may be attributed to online privacy fatigue. Given the importance of online privacy and the lack of integrative online privacy fatigue research, this scoping review aims to provide researchers with an understanding of online privacy fatigue, its antecedents and outcomes, as well as a critical analysis of the methodological approaches used. A scoping review based on the PRISMA-ScR checklist was conducted. Only empirical studies focusing on online privacy were included, with nontechnological studies being excluded. All studies had to be written in English. A search strategy encompassing six electronic databases resulted in eighteen eligible studies, and a backward search of the references resulted in an additional five publications. Of the 23 studies, the majority were quantitative (74%), with fewer than half being theory driven (48%). Privacy fatigue was mainly conceptualized as a loss of control (74% of studies). Five categories of privacy fatigue antecedents were identified: privacy risk, privacy control and management, knowledge and information, individual differences, and privacy policy characteristics. This study highlights the need for greater attention to be paid to the methodological design and theoretical underpinning of future research. Quantitative studies should carefully consider the use of CB-SEM or PLS-SEM, should aim to increase the sample size, and should improve on analytical rigor. In addition, to ensure that the field matures, future studies should be underpinned by established theoretical frameworks. This review reveals a notable absence of privacy fatigue research when modeling the influence of privacy threats and invasions and their relationship with privacy burnout, privacy resignation, and increased self-disclosure. In addition, this review provides insight into theoretical and practical research recommendations that future privacy fatigue researchers should consider going forward. Full article
(This article belongs to the Collection Information Systems Security)
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14 pages, 3413 KiB  
Article
Clinical Confirmation of Pan-Amyloid Reactivity of Radioiodinated Peptide 124I-p5+14 (AT-01) in Patients with Diverse Types of Systemic Amyloidosis Demonstrated by PET/CT Imaging
by Emily B. Martin, Alan Stuckey, Dustin Powell, Ronald Lands, Bryan Whittle, Craig Wooliver, Sallie Macy, James S. Foster, Spencer Guthrie, Stephen J. Kennel and Jonathan S. Wall
Pharmaceuticals 2023, 16(4), 629; https://doi.org/10.3390/ph16040629 - 21 Apr 2023
Cited by 19 | Viewed by 2613
Abstract
There are at least 20 distinct types of systemic amyloidosis, all of which result in the organ-compromising accumulation of extracellular amyloid deposits. Amyloidosis is challenging to diagnose due to the heterogeneity of the clinical presentation, yet early detection is critical for favorable patient [...] Read more.
There are at least 20 distinct types of systemic amyloidosis, all of which result in the organ-compromising accumulation of extracellular amyloid deposits. Amyloidosis is challenging to diagnose due to the heterogeneity of the clinical presentation, yet early detection is critical for favorable patient outcomes. The ability to non-invasively and quantitatively detect amyloid throughout the body, even in at-risk populations, before clinical manifestation would be invaluable. To this end, a pan-amyloid-reactive peptide, p5+14, has been developed that is capable of binding all types of amyloid. Herein, we demonstrate the ex vivo pan-amyloid reactivity of p5+14 by using peptide histochemistry on animal and human tissue sections containing various types of amyloid. Furthermore, we present clinical evidence of pan-amyloid binding using iodine-124-labeled p5+14 in a cohort of patients with eight (n = 8) different types of systemic amyloidosis. These patients underwent PET/CT imaging as part of the first-in-human Phase 1/2 clinical trial evaluating this radiotracer (NCT03678259). The uptake of 124I-p5+14 was observed in abdominothoracic organs in patients with all types of amyloidosis evaluated and was consistent with the disease distribution described in the medical record and literature reports. On the other hand, the distribution in healthy subjects was consistent with radiotracer catabolism and clearance. The early and accurate diagnosis of amyloidosis remains challenging. These data support the utility of 124I-p5+14 for the diagnosis of varied types of systemic amyloidosis by PET/CT imaging. Full article
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11 pages, 1198 KiB  
Article
Urban Self-Supply from Groundwater—An Analysis of Management Aspects and Policy Needs
by Stephen Foster, Ricardo Hirata, Michael Eichholz and Mohammad-Faiz Alam
Water 2022, 14(4), 575; https://doi.org/10.3390/w14040575 - 14 Feb 2022
Cited by 22 | Viewed by 4393
Abstract
The use of private water wells for self-supply in developing cities has ‘mushroomed’ during recent decades, such that it is now an important component of total water-supply, but one all too frequently overlooked in official figures. Selected global experience of the phenomenon (from [...] Read more.
The use of private water wells for self-supply in developing cities has ‘mushroomed’ during recent decades, such that it is now an important component of total water-supply, but one all too frequently overlooked in official figures. Selected global experience of the phenomenon (from 10 cities in 3 continents) is succinctly summarized, and then analyzed from differing perspectives, before drawing recommendations on priorities for its improved management. Full article
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17 pages, 2009 KiB  
Article
Integration of Metabolomic and Clinical Data Improves the Prediction of Intensive Care Unit Length of Stay Following Major Traumatic Injury
by Animesh Acharjee, Jon Hazeldine, Alina Bazarova, Lavanya Deenadayalu, Jinkang Zhang, Conor Bentley, Dominic Russ, Janet M. Lord, Georgios V. Gkoutos, Stephen P. Young and Mark A. Foster
Metabolites 2022, 12(1), 29; https://doi.org/10.3390/metabo12010029 - 31 Dec 2021
Cited by 11 | Viewed by 2853
Abstract
Recent advances in emergency medicine and the co-ordinated delivery of trauma care mean more critically-injured patients now reach the hospital alive and survive life-saving operations. Indeed, between 2008 and 2017, the odds of surviving a major traumatic injury in the UK increased by [...] Read more.
Recent advances in emergency medicine and the co-ordinated delivery of trauma care mean more critically-injured patients now reach the hospital alive and survive life-saving operations. Indeed, between 2008 and 2017, the odds of surviving a major traumatic injury in the UK increased by nineteen percent. However, the improved survival rates of severely-injured patients have placed an increased burden on the healthcare system, with major trauma a common cause of intensive care unit (ICU) admissions that last ≥10 days. Improved understanding of the factors influencing patient outcomes is now urgently needed. We investigated the serum metabolomic profile of fifty-five major trauma patients across three post-injury phases: acute (days 0–4), intermediate (days 5–14) and late (days 15–112). Using ICU length of stay (LOS) as a clinical outcome, we aimed to determine whether the serum metabolome measured at days 0–4 post-injury for patients with an extended (≥10 days) ICU LOS differed from that of patients with a short (<10 days) ICU LOS. In addition, we investigated whether combining metabolomic profiles with clinical scoring systems would generate a variable that would identify patients with an extended ICU LOS with a greater degree of accuracy than models built on either variable alone. The number of metabolites unique to and shared across each time segment varied across acute, intermediate and late segments. A one-way ANOVA revealed the most variation in metabolite levels across the different time-points was for the metabolites lactate, glucose, anserine and 3-hydroxybutyrate. A total of eleven features were selected to differentiate between <10 days ICU LOS vs. >10 days ICU LOS. New Injury Severity Score (NISS), testosterone, and the metabolites cadaverine, urea, isoleucine, acetoacetate, dimethyl sulfone, syringate, creatinine, xylitol, and acetone form the integrated biomarker set. Using metabolic enrichment analysis, we found valine, leucine and isoleucine biosynthesis, glutathione metabolism, and glycine, serine and threonine metabolism were the top three pathways differentiating ICU LOS with a p < 0.05. A combined model of NISS and testosterone and all nine selected metabolites achieved an AUROC of 0.824. Differences exist in the serum metabolome of major trauma patients who subsequently experience a short or prolonged ICU LOS in the acute post-injury setting. Combining metabolomic data with anatomical scoring systems allowed us to discriminate between these two groups with a greater degree of accuracy than that of either variable alone. Full article
(This article belongs to the Special Issue Metabolic Alterations in Sepsis and Major Trauma)
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29 pages, 1153 KiB  
Article
Participatory Action Research for Conservation and Development: Experiences from the Amazon
by Stephen G. Perz, Marliz Arteaga, Andrea Baudoin Farah, I. Foster Brown, Elsa Renee Huaman Mendoza, Yara Araújo Pereira de Paula, Leonor Mercedes Perales Yabar, Alan dos Santos Pimentel, Sabina C. Ribeiro, Guillermo Rioja-Ballivián, Martha Cecilia Rosero Peña, L. Cecilia Sanjinez L. and N. Galia Selaya G.
Sustainability 2022, 14(1), 233; https://doi.org/10.3390/su14010233 - 27 Dec 2021
Cited by 14 | Viewed by 7615
Abstract
Research that features participation and action orientation, such as participatory action research (PAR), is especially valuable in contexts where there is rapid change, high social inequality, and great uncertainty about the future, which drives stakeholder demands for information to support their goals. The [...] Read more.
Research that features participation and action orientation, such as participatory action research (PAR), is especially valuable in contexts where there is rapid change, high social inequality, and great uncertainty about the future, which drives stakeholder demands for information to support their goals. The Amazon offers such a context, for it is a region where diverse stakeholders engage in contestation over environmental governance to address issues such as climate change to achieve conservation and sustainable development. Stakeholder mobilization has changed the terms by which research is conducted, from the definition of priority topics to the application of findings. Due to stakeholder mobilization, more and more research in the Amazon is now necessarily participatory, for stakeholders routinely issue demands about how the research will be conducted and for what purpose. In this paper, we provide an overview of several experiences of implementing methods such as PAR by different teams or networks, focusing on the complementary contributions of outside researchers and local stakeholders. The heart of the paper reports on three broad types of experiences focusing on conservation and development in the Amazon: (1) participatory data collection for co-production of knowledge for environmental governance, (2) inclusive environmental monitoring systems, and (3) innovative models of knowledge exchange to facilitate collective action. Within each type, we report multiple experiences with distinct approaches to participation and action in research. These experiences constitute models that can be replicated in other places for broader impact to support conservation and development. Full article
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10 pages, 1229 KiB  
Article
Institutional Issues around Agricultural Land-Use Control for Groundwater Conservation—A Long-Term Perspective
by Stephen Foster and John Chilton
Water 2021, 13(17), 2417; https://doi.org/10.3390/w13172417 - 2 Sep 2021
Cited by 3 | Viewed by 3024
Abstract
Key aspects of policy development and implementation for the control of agricultural land use to conserve groundwater are overviewed. This is one of today’s greatest environmental challenges and one on which only limited progress has been made internationally. For this purpose, the objectives [...] Read more.
Key aspects of policy development and implementation for the control of agricultural land use to conserve groundwater are overviewed. This is one of today’s greatest environmental challenges and one on which only limited progress has been made internationally. For this purpose, the objectives of agricultural land-use control in defined areas are either to reduce diffuse pollution of groundwater and/or to regulate excessive abstraction for crop irrigation to sustain groundwater resources. Progress on both of these fronts has been assessed from the published work, and the lessons learnt are summarised for global application. Full article
(This article belongs to the Section Water Resources Management, Policy and Governance)
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8 pages, 871 KiB  
Perspective
Global Policy Overview of Groundwater in Urban Development—A Tale of 10 Cities!
by Stephen Foster
Water 2020, 12(2), 456; https://doi.org/10.3390/w12020456 - 8 Feb 2020
Cited by 49 | Viewed by 5907
Abstract
Urbanisation is the predominant global phenomenon of our time. This overview provides an assessment of the trends in both public and private use of groundwater for urban water-supply in 10 developing cities and their policy implications, which is based on the global experience [...] Read more.
Urbanisation is the predominant global phenomenon of our time. This overview provides an assessment of the trends in both public and private use of groundwater for urban water-supply in 10 developing cities and their policy implications, which is based on the global experience during 2001–2012 of the World Bank—Groundwater Management Advisory Team (a multi-disciplinary team of groundwater specialists working long-term for the World Bank, with special funding principally from the Netherlands Government supplemented by the United Kingdom and Denmark), together with subsequent follow-up enquiries. The strategic assessment analyses both the benefits to water users and the broader community of groundwater use, and the associated risks in terms of (a) compromising resource sustainability, (b) impacting the built infrastructure, (c) public-health hazards arising from widespread groundwater pollution and (d) the economic distortion of water-sector investments. Full article
(This article belongs to the Special Issue Urban Hydrogeology Studies)
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22 pages, 7333 KiB  
Article
Smart Adhesive Joint with High-Definition Fiber-Optic Sensing for Automotive Applications
by Stephen Young, Dayakar Penumadu, Darren Foster, Hannah Maeser, Bharati Balijepalli, Jason Reese, Dave Bank, Jeff Dahl and Patrick Blanchard
Sensors 2020, 20(3), 614; https://doi.org/10.3390/s20030614 - 22 Jan 2020
Cited by 18 | Viewed by 3914
Abstract
Structural health monitoring of fiber-reinforced composite-based joints for automotive applications during their manufacturing and on-demand assessment for its durability in working environments is critically needed. High-definition fiber-optic sensing is an effective method to measure internal strain/stress development using minimally invasive continuous sensors. The [...] Read more.
Structural health monitoring of fiber-reinforced composite-based joints for automotive applications during their manufacturing and on-demand assessment for its durability in working environments is critically needed. High-definition fiber-optic sensing is an effective method to measure internal strain/stress development using minimally invasive continuous sensors. The sensing fiber diameters are in the same order of magnitude when compared to reinforcement (glass, basalt, or carbon fibers) used in polymer composites. They also offer a unique ability to monitor the evolution of residual stresses after repeated thermal exposure with varying temperatures for automotive components/joints during painting using an electrophoretic painting process. In this paper, a high-definition fiber-optic sensor utilizing Rayleigh scattering is embedded within an adhesive joint between a carbon fiber-reinforced thermoset composite panel and an aluminum panel to measure spatially resolved strain development, residual strain, and thermal expansion properties during the electrophoretic paint process-simulated conditions. The strain measured by the continuous fiber-optic sensor was compared with an alternate technique using thermal digital image correlation. The fiber-optic sensor was able to identify the spatial variation of residual strains for a discontinuous carbon fiber-reinforced composite with varying local fiber orientations and resin content. Full article
(This article belongs to the Section Physical Sensors)
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25 pages, 9814 KiB  
Article
Functionalized Cellulose Nanocrystal Nanocomposite Membranes with Controlled Interfacial Transport for Improved Reverse Osmosis Performance
by Ethan D. Smith, Keith D. Hendren, James V. Haag, E. Johan Foster and Stephen M. Martin
Nanomaterials 2019, 9(1), 125; https://doi.org/10.3390/nano9010125 - 20 Jan 2019
Cited by 46 | Viewed by 7704
Abstract
Thin-film nanocomposite membranes (TFNs) are a recent class of materials that use nanoparticles to provide improvements over traditional thin-film composite (TFC) reverse osmosis membranes by addressing various design challenges, e.g., low flux for brackish water sources, biofouling, etc. In this study, TFNs were [...] Read more.
Thin-film nanocomposite membranes (TFNs) are a recent class of materials that use nanoparticles to provide improvements over traditional thin-film composite (TFC) reverse osmosis membranes by addressing various design challenges, e.g., low flux for brackish water sources, biofouling, etc. In this study, TFNs were produced using as-received cellulose nanocrystals (CNCs) and 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanocrystals (TOCNs) as nanoparticle additives. Cellulose nanocrystals are broadly interesting due to their high aspect ratios, low cost, sustainability, and potential for surface modification. Two methods of membrane fabrication were used in order to study the effects of nanoparticle dispersion on membrane flux and salt rejection: a vacuum filtration method and a monomer dispersion method. In both cases, various quantities of CNCs and TOCNs were incorporated into a polyamide TFC membrane via in-situ interfacial polymerization. The flux and rejection performance of the resulting membranes was evaluated, and the membranes were characterized via attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The vacuum filtration method resulted in inconsistent TFN formation with poor nanocrystal dispersion in the polymer. In contrast, the dispersion method resulted in more consistent TFN formation with improvements in both water flux and salt rejection observed. The best improvement was obtained via the monomer dispersion method at 0.5 wt% TOCN loading resulting in a 260% increase in water flux and an increase in salt rejection to 98.98 ± 0.41% compared to 97.53 ± 0.31% for the plain polyamide membrane. The increased flux is attributed to the formation of nanochannels at the interface between the high aspect ratio nanocrystals and the polyamide matrix. These nanochannels serve as rapid transport pathways through the membrane, and can be used to tune selectivity via control of particle/polymer interactions. Full article
(This article belongs to the Special Issue Cellulose Nanomaterials)
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