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Solid oxide fuel cells (SOFCs) stand out in sustainable energy systems for their unique ability to efficiently utilize hydrocarbon fuels, particularly those from carbon-neutral sources. CeO2-δ (ceria) based oxides embedded in SOFCs are recognized for their critical role in managing hydrocarbon activation and carbon coking. However, even for the simplest hydrocarbon molecule, CH4, the mechanism of electrochemical oxidation at the ceria/gas interface is not well understood and the capability of ceria to electrochemically oxidize methane remains a topic of debate. This lack of clarity stems from the intricate design of standard metal/oxide composite electrodes and the complex nature of electrode reactions involving multiple chemical and electrochemical steps. This study presents a Sm-doped ceria thin-film model cell that selectively monitors CH4 direct-electro-oxidation on the ceria surface. Using impedance spectroscopy, operando X-ray photoelectron spectroscopy, and density functional theory, it is unveiled that ceria surfaces facilitate CâH bond cleavage and that H2O formation is key in determining the overall reaction rate at the electrode. These insights effectively address the longstanding debate regarding the direct utilization of CH4 in SOFCs. Moreover, these findings pave the way for an optimized electrode design strategy, essential for developing high-performance, environmentally sustainable fuel cells.
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Chronic pain is one of the major causes of disability with a tremendous impact on an individual's quality of life and on public health. Transcutaneous vagus nerve stimulation (tVNS) is a safe therapeutic for this condition. We aimed to evaluate its effects in adults with chronic pain. A comprehensive search was performed, including randomized controlled trials published until October 2023, which assessed the effects of noninvasive tVNS. Cohen's d effect size and 95% confidence intervals (CIs) were calculated, and random-effects meta-analyses were performed. Fifteen studies were included. The results revealed a mean effect size of 0.41 (95% CI 0.17-0.66) in favor of tVNS as compared with control, although a significant heterogeneity was observed (χ2 = 21.7, df = 10, P = 0.02, I 2 = 53.9%). However, when compared with nonactive controls, tVNS shows a larger effect size (0.79, 95% CI 0.25-1.33), although the number of studies was small (n = 3). When analyzed separately, auricular tVNS and cervical tVNS against control, it shows a significant small to moderate effect size, similar to that of the main analysis, respectively, 0.42 (95% CI 0.08-0.76, 8 studies) and 0.36 (95% CI 0.01-0.70, 3 studies). No differences were observed in the number of migraine days for the trials on migraine. This meta-analysis indicates that tVNS shows promise as an effective intervention for managing pain intensity in chronic pain conditions. We discuss the design of future trials to confirm these preliminary results, including sample size and parameters of stimulation.
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Background: Evidence suggests that vagus nerve stimulation can modulate heart rate variability (HRV). However, there is a lack of mechanistic studies in healthy subjects assessing the effects of bilateral transcutaneous auricular vagus nerve stimulation (taVNS) on HRV. Our study aims to investigate how taVNS can influence the HRV response, including the influence of demographic variables in this response. Methods: Therefore, we conducted a randomized controlled study with 44 subjects, 22 allocated to active and 22 to sham taVNS. Results: Our results showed a significant difference between groups in the high-frequency (HF) metric. Active taVNS increased the HF metric significantly as compared to sham taVNS. Also, we found that age was a significant effect modifier of the relationship between taVNS and HF-HRV, as a larger increase in HF-HRV was seen in the older subjects. Importantly, there was a decrease in HF-HRV in the sham group. Conclusions: These findings suggest that younger subjects can adapt and maintain a constant level of HF-HRV regardless of the type of stimulation, but in the older subjects, only the active taVNS recipients were able to maintain and increase their HF-HRV. These results are important because they indicate that taVNS can enhance physiological regulation processes in response to external events.
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Purpose: The purpose of this study was to investigate the neuromodulatory effects of transauricular vagus nerve stimulation (taVNS) and determine optimal taVNS duration to induce the meaningful neuromodulatroty effects using resting-state electroencephalography (EEG). Method: Fifteen participants participated in this study and taVNS was applied to the cymba conchae for a duration of 40 min. Resting-state EEG was measured before and during taVNS application. EEG power spectral density (PSD) and brain network indices (clustering coefficient and path length) were calculated across five frequency bands (delta, theta, alpha, beta and gamma), respectively, to assess the neuromodulatory effect of taVNS. Moreover, we divided the whole brain region into the five regions of interest (frontal, central, left temporal, right temporal, and occipital) to confirm the neuromodulation effect on each specific brain region. Result: Our results demonstrated a significant increase in EEG frequency powers across all five frequency bands during taVNS. Furthermore, significant changes in network indices were observed in the theta and gamma bands compared to the pre-taVNS measurements. These effects were particularly pronounced after approximately 10 min of stimulation, with a more dominant impact observed after approximately 20-30 min of taVNS application. Conclusion: The findings of this study indicate that taVNS can effectively modulate the brain activity, thereby exerting significant effects on brain characteristics. Moreover, taVNS duration of approximately 20-30 min was considered appropriate for inducing a stable and efficient neuromodulatory effects. Consequently, these findings have the potential to contribute to research aimed at enhancing cognitive and motor functions through the modulation of EEG using taVNS. Supplementary Information: The online version contains supplementary material available at 10.1007/s13534-024-00361-8.
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Bilateral transcutaneous auricular vagus nerve stimulation (taVNS) - a non-invasive neuromodulation technique - has been investigated as a safe and feasible technique to treat many neuropsychiatric conditions. such as epilepsy, depression, anxiety, and chronic pain. Our aim is to investigate the effect of taVNS on neurophysiological processes during emotional and Go/No-Go tasks, and changes in frontal alpha asymmetry. We performed a randomized, double-blind, sham-controlled trial with 44 healthy individuals who were allocated into two groups (the active taVNS group and the sham taVNS group). Subjects received one session of taVNS (active or sham) for 60 min. QEEG was recorded before and after the interventions, and the subjects were assessed while exposed to emotional conditions with sad and happy facial expressions, followed by a Go/No-Go trial. The results demonstrated a significant increase in N2 amplitude in the No-Go condition for the active taVNS post-intervention compared to the sham taVNS after adjusting by handedness, mood, and fatigue levels (p = 0.046), significantly reduced ERD during sad conditions after treatment (p = 0.037), and increased frontal alpha asymmetry towards the right frontal hemisphere during the emotional task condition (p = 0.046). Finally, we observed an interesting neural signature in this study that suggests a bottom-up modulation from brainstem/subcortical to cortical areas as characterized by improved lateralization of alpha oscillations towards the frontal right hemisphere, and changes in ERP during emotional and Go/No-Go tasks that suggests a better subcortical response to the tasks. Such bottom-up effects may mediate some of the clinical effects of taVNS.
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Eletroencefalografia , Emoções , Estimulação do Nervo Vago , Humanos , Masculino , Feminino , Adulto , Emoções/fisiologia , Estimulação do Nervo Vago/métodos , Método Duplo-Cego , Adulto Jovem , Eletroencefalografia/métodos , Função Executiva/fisiologia , Ritmo alfa/fisiologia , Potenciais Evocados/fisiologia , Estimulação Elétrica Nervosa Transcutânea/métodos , Inibição PsicológicaRESUMO
BACKGROUND: The COVID-19 pandemic has profoundly affected out-of-hospital cardiac arrest (OHCA) and disrupted the chain of survival. Even after the end of the pandemic, the risk of new variants and surges persists. Analyzing the characteristics of OHCA during the pandemic is important to prepare for the next pandemic and to avoid repeated negative outcomes. However, previous studies have yielded somewhat varied results, depending on the health care system or the specific characteristics of social structures. OBJECTIVE: We aimed to investigate and compare the incidence, outcomes, and characteristics of OHCA during the prepandemic and pandemic periods using data from a nationwide multicenter OHCA registry. METHODS: We conducted a multicenter, retrospective, observational study using data from the Korean Cardiac Arrest Resuscitation Consortium (KoCARC) registry. This study included adult patients with OHCA in South Korea across 3 distinct 1-year periods: the prepandemic period (from January to December 2019), early phase pandemic period (from July 2020 to June 2021), and late phase pandemic period (from July 2021 to June 2022). We extracted and contrasted the characteristics of patients with OHCA, prehospital time factors, and outcomes for the patients across these 3 periods. The primary outcomes were survival to hospital admission and survival to hospital discharge. The secondary outcome was good neurological outcome. RESULTS: From the 3 designated periods, a total of 9031 adult patients with OHCA were eligible for analysis (prepandemic: n=2728; early pandemic: n=2954; and late pandemic: n=3349). Witnessed arrest (P<.001) and arrest at home or residence (P=.001) were significantly more frequent during the pandemic period than during the prepandemic period, and automated external defibrillator use by bystanders was lower in the early phase of the pandemic than during other periods. As the pandemic advanced, the rates of the first monitored shockable rhythm (P=.10) and prehospital endotracheal intubation (P<.001) decreased significantly. Time from cardiac arrest cognition to emergency department arrival increased sequentially (prepandemic: 33 min; early pandemic: 35 min; and late pandemic: 36 min; P<.001). Both survival and neurological outcomes worsened as the pandemic progressed, with survival to discharge showing the largest statistical difference (prepandemic: 385/2728, 14.1%; early pandemic: 355/2954, 12%; and late pandemic: 392/3349, 11.7%; P=.01). Additionally, none of the outcomes differed significantly between the early and late phase pandemic periods (all P>.05). CONCLUSIONS: During the pandemic, especially amid community COVID-19 surges, the incidence of OHCA increased while survival rates and good neurological outcome at discharge decreased. Prehospital OHCA factors, which are directly related to OHCA prognosis, were adversely affected by the pandemic. Ongoing discussions are needed to maintain the chain of survival in the event of a new pandemic. TRIAL REGISTRATION: ClinicalTrials.gov NCT03222999; https://classic.clinicaltrials.gov/ct2/show/NCT03222999.
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COVID-19 , Parada Cardíaca Extra-Hospitalar , Sistema de Registros , Humanos , Parada Cardíaca Extra-Hospitalar/epidemiologia , Parada Cardíaca Extra-Hospitalar/terapia , Parada Cardíaca Extra-Hospitalar/mortalidade , República da Coreia/epidemiologia , COVID-19/epidemiologia , Feminino , Masculino , Idoso , Pessoa de Meia-Idade , Incidência , Estudos Retrospectivos , Idoso de 80 Anos ou mais , Pandemias , Reanimação Cardiopulmonar/estatística & dados numéricosRESUMO
This study investigates the differences in peak plantar pressure between the amputated and intact limbs of transfemoral amputees when walking outdoors. Ten non-amputees (aged 24.4 ± 2.0 years, 176.9 ± 2.5 cm, 72.3 ± 7.9 kg) and six transfemoral amputees (48.5 ± 6.3 years, 173.8 ± 4.2 cm, 82.0 ± 11.9 kg) participated in the study. Over approximately 1.6 km, the participants encountered various obstacles, including stairs, uneven surfaces, hills, and level ground, both indoors and outdoors. Throughout the walking session, the peak plantar pressure in both feet was monitored using wearable insole sensors. For all terrains, the percentage asymmetry was determined. Significant changes in peak plantar pressure asymmetry were found between the intact and amputated limbs, particularly when walking on level ground indoors, uneven terrains, descending stairs, and on steep slopes outdoors (all p < 0.05). These findings highlight the greater peak plantar pressure asymmetry in transfemoral amputees when walking outside. In addition, this study revealed that not all terrains contribute uniformly to this asymmetry.
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Amputados , Pé , Pressão , Caminhada , Humanos , Caminhada/fisiologia , Amputados/reabilitação , Masculino , Adulto , Pessoa de Meia-Idade , Pé/fisiologia , Feminino , Fenômenos Biomecânicos , Fêmur/cirurgia , Fêmur/fisiologia , Membros Artificiais , Adulto JovemRESUMO
INTRODUCTION: Although the risk of CVD is increased in cancer survivors, few studies have investigated the CVD risk in survivors of gastrointestinal (GI) cancer. Therefore, we evaluated the CVD risk using the 10-year atherosclerotic cardiovascular disease (ASCVD) risk score for GI cancer survivors and associated physical activity factors. METHODS: Using the 2014-2019 Korean National Health and Nutrition Examination Surveys, data were collected for 262 GI cancer survivors and 1,310 cancer-free controls matched at a 1:5 ratio based on age and sex. The International Physical Activity Questionnaire Short-Form was used to assess physical activity, and the Euro QoL Questionnaire 5-Dimensional Classification (EQ-5D) was used to assess the health-related quality of life. RESULTS: A multiple logistic regression analysis demonstrated a lower risk of ASCVD in GI cancer survivors than in controls (adjusted odds ratio [aOR] = 0.73, 95% confidence interval [CI] = 0.55-0.97). Moreover, the risk of having a high ASCVD score was significantly lower in individuals who performed sufficient aerobic physical activity (aOR = 0.59, 95% CI = 0.47-0.75) and those with an EQ-5D score 1 or 2 (aOR = 0.36, 95% CI = 0.20-0.65 and aOR = 0.31, 95% CI = 0.16-0.58, respectively). CONCLUSIONS: This population-based study demonstrated that engaging in sufficient physical activity can reduce the ASCVD risk among GI cancer survivors.
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Sobreviventes de Câncer , Doenças Cardiovasculares , Exercício Físico , Neoplasias Gastrointestinais , Inquéritos Nutricionais , Humanos , Masculino , Feminino , Sobreviventes de Câncer/estatística & dados numéricos , Sobreviventes de Câncer/psicologia , Pessoa de Meia-Idade , Neoplasias Gastrointestinais/psicologia , República da Coreia/epidemiologia , Doenças Cardiovasculares/epidemiologia , Idoso , Adulto , Qualidade de Vida , Fatores de Risco , Estudos de Casos e Controles , Medição de RiscoRESUMO
Metal-support interaction plays a crucial role in governing the stability and activity of atomically dispersed platinum catalysts on ceria support. The migration and aggregation of platinum atoms during the catalytic reaction leads to the redistribution of active sites. In this study, by utilizing a multimodal characterization scheme, we observed the aggregation of platinum atoms at high temperatures under reverse water gas shift reaction conditions and the subsequent fragmentation of platinum clusters, forming "single atoms" upon cooling. Theoretical simulations of both effects uncovered the roles of carbon monoxide binding on perimeter Pt sites in the clusters and hydrogen coverage in the aggregation and fragmentation mechanisms. This study highlights the complex effects of adsorbate and supports interactions with metal sites in Pt/ceria catalysts that govern their structural transformations under in situ conditions.
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OBJECTIVE: We aimed to conduct a systematic review and meta-analysis assessing the antiinflammatory effects of various VNS methods while exploring multiple antiinflammatory pathways. MATERIALS AND METHODS: We included clinical trials that used electrical stimulation of the vagus nerve and assessed inflammatory markers up to October 2022. We excluded studies lacking control groups, those with combined interventions, or abstracts without full text. We adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and the Cochrane Handbook for Systematic Reviews. For each inflammatory marker, a random-effects meta-analysis using the inverse variance method was performed. Methods used include transcutaneous auricular VNS (taVNS), transcutaneous cervical VNS (tcVNS), invasive cervical VNS (iVNS), and electroacupuncture VNS (eaVNS). Main reported outcomes included tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1ß, C-reactive protein (CRP), and IL-10. Risk of bias was evaluated using the Cochrane Collaboration Tool (RoB 2.0). RESULTS: This review included 15 studies, involving 597 patients. No statistically significant general VNS effect was observed on TNF-α, IL-6, and IL-1ß. However, CRP, IL-10, and interferon (IFN)-γ were significantly modulated by VNS across all methods. Subgroup analysis revealed specific stimulation techniques producing significant results, such as taVNS effects in IL-1ß and IL-10, and iVNS in IL-6, whereas tcVNS and eaVNS did not convey significant pooled results individually. Cumulative exposure to VNS, higher risk of bias, study design, and pulse width were identified as effect size predictors in our meta-regression models. CONCLUSIONS: Pooling all VNS techniques indicated the ability of VNS to modulate inflammatory markers such as CRP, IL-10, and IFN-γ. Individually, methods such as taVNS were effective in modulating IL-1ß and IL-10, whereas iVNS modulated IL-6. However, different VNS techniques should be separately analyzed in larger, homogeneous, and powerful studies to achieve a clearer and more consistent understanding of the effect of each VNS method on the inflammatory system.
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Background/Aims: : Appropriate tissue tension and clear visibility of the dissection area using traction are essential for effective and safe endoscopic submucosal dissection (ESD). In this study, we developed a retractable robot-assisted traction device and evaluated its performance in colorectal ESD. Methods: : An experienced endoscopist performed ESD 18 times on an ex vivo porcine colon using the robot and 18 times using the conventional method. The outcome measures were procedure time, dissection speed, procedure-related adverse events, and blind dissection rate. Results: : Thirty-six colonic lesions were resected from ex vivo porcine colon samples. The total procedure time was significantly shorter in robot-assisted ESD (RESD) than in conventional ESD (CESD) (20.1±4.1 minutes vs 34.3±8.3 minutes, p<0.05). The submucosal dissection speed was significantly faster in the RESD group than in the CESD group (36.8±9.2 mm2/min vs 18.1±4.7 mm2/min, p<0.05). The blind dissection rate was also significantly lower in the RESD group (12.8%±3.4% vs 35.1%±3.9%, p<0.05). In an in vivo porcine feasibility study, the robotic device was attached to a colonoscope and successfully inserted into the proximal colon without damaging the colonic wall, and ESD was successfully performed. Conclusions: : The dissection speed and safety profile improved significantly with the retractable RESD. Thus, our robotic device has the potential to provide simple, effective, and safe multidirectional traction during colonic ESD.
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Colo , Ressecção Endoscópica de Mucosa , Duração da Cirurgia , Procedimentos Cirúrgicos Robóticos , Animais , Ressecção Endoscópica de Mucosa/instrumentação , Ressecção Endoscópica de Mucosa/métodos , Suínos , Procedimentos Cirúrgicos Robóticos/instrumentação , Procedimentos Cirúrgicos Robóticos/métodos , Colo/cirurgia , Estudos de Viabilidade , Colonoscopia/instrumentação , Colonoscopia/métodos , Neoplasias Colorretais/cirurgia , Dissecação/instrumentação , Dissecação/métodos , Desenho de EquipamentoRESUMO
Modern semiconductor fabrication is challenged by difficulties in overcoming physical and chemical constraints. A major challenge is the wet etching of dummy gate silicon, which involves the removal of materials inside confined spaces of a few nanometers. These chemical processes are significantly different in the nanoscale and bulk. Previously, electrical double-layer formation, bubble entrapment, poor wettability, and insoluble intermediate precipitation have been proposed. However, the exact suppression mechanisms remain unclear due to the lack of direct observation methods. Herein, we investigate limiting factors for the etching kinetics of silicon with tetramethylammonium hydroxide at the nanoscale by using liquid-phase transmission electron microscopy, three-dimensional electron tomography, and first-principles calculations. We reveal suppressed chemical reactions, unstripping phenomena, and stochastic etching behaviors that have never been observed on a macroscopic scale. We expect that solutions can be suggested from this comprehensive insight into the scale-dependent limiting factors of fabrication.
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The regulation of apoptosis is the primary goal of ablation therapy. Irreversible electroporation (IRE) is a promising non-thermal tissue ablation-based therapy that induces apoptosis by manipulating electrical conditions. This study aimed to investigate IRE-induced gastric tissue apoptosis in response to changes in the electric field intensity, followed by the repair process. Among the 52 rats used in this study, 24 were used to explore apoptosis, and 28 were used to study regeneration. The apoptosis-to-necrosis ratio of the electrical field strength was evaluated using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling and caspase-3 immunohistochemistry. The size of IRE-induced ulcers in the gastric tissue continuously increased with increasing electrical intensity (r2 = 0.830, p < 0.001). The level of apoptosis gradually decreased after peaking at 200 V (1000 V/cm). The size of the 400 V-ablated ulcers continued to decrease, and they were not visible by day 14. The proliferation and migration of epithelial cells with fibroblasts were observed on day 3 and augmented on day 7 post-ablation. This investigation demonstrated the biphasic activation of apoptosis with respect to the electrical field strength. Visually and histologically, IRE-induced gastric ulcers demonstrated complete tissue regeneration after two weeks.
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Iatrogenic stomach perforation is a detrimental, irreversible, and fatal condition. Traditional surgery and endoscopic suturing clips and devices have been introduced to seal holes and prevent sepsis and disease progression. However, the development of endoscopic devices for perforations remains challenging, with no standard device available. This study investigates the superficial layer approximation strengths of the newly designed ENDOCRAB system for gastric wall defects. Thirty porcine stomachs were prepared ex vivo for the perforation model and distributed equally into three groups: ENDOCRAB system, Through-the-Scope Clip (TTSC), and hand suturing (HS). Both ENDOCRAB and TTSC achieved mucosal-submucosal layer apposition, whereas HS allowed a full-thickness layer. Their air leakage pressure and procedural duration were measured. The analysis of air-leakage pressure demonstrated comparable suture strength between ENDOCRAB (118.5 ± 41.7 mmHg) and HS (127.4 ± 30.2 mmHg, P = 0.812), but inferior strength with TTSC (73.6 ± 21.6 mmHg, P = 0.012). HS achieved the shortest procedural duration, whereas ENDOCRAB and TTSC showed no significant differences. The ENDOCRAB system showed significantly greater strength than the TTSC, was comparable to HS in strength, and required a procedural duration similar to that of the TTSC. Furthermore, long-term in vivo experiments and histological evaluations are essential.
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Cirurgia Endoscópica por Orifício Natural , Gastropatias , Suínos , Animais , Estômago/cirurgia , Técnicas de Sutura , Instrumentos CirúrgicosRESUMO
BACKGROUND: Endoscopic submucosal dissection (ESD) is the standard treatment for early malignant stomach lesions. However, this procedure is technically demanding and carries a high complication risk. The level of difficulty in performing ESD is influenced by the location of the lesion. In our study, we aimed to investigate and analyze the effectiveness of robot-assisted ESD for lesions situated in challenging locations within the stomach. METHODS: We developed a gastric simulator that could be used to implement various gastric ESD locations. An EndoGel (Sunarrow, Tokyo, Japan) was attached to the simulator for the dissection procedures. Robot-assisted or conventional ESD was performed at challenging or easy locations by two ESD-trainee endoscopists. RESULTS: The procedure time was remarkably shorter for robotic ESD than conventional dissection at challenging locations (6.2 vs. 10.2 min, P < 0.05), mainly due to faster dissection (220.3 vs. 101.9 mm2/min, P < 0.05). The blind dissection rate was significantly lower with robotic ESD than with the conventional method (17.6 vs. 35.2%, P < 0.05) at challenging locations. CONCLUSION: The procedure time was significantly shortened when robot-assisted gastric ESD procedures were performed at challenging locations. Therefore, our robotic device provides simple, effective, and safe multidirectional traction for endoscopic submucosal dissection at challenging locations, thereby reducing difficulty of the procedure.
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Ressecção Endoscópica de Mucosa , Robótica , Neoplasias Gástricas , Humanos , Mucosa Gástrica/cirurgia , Mucosa Gástrica/patologia , Ressecção Endoscópica de Mucosa/métodos , Neoplasias Gástricas/cirurgia , Neoplasias Gástricas/patologia , Resultado do TratamentoRESUMO
Many quantum dot light-emitting diodes (QLEDs) utilize ZnO nanoparticles (NPs) as an electron injection layer (EIL). However, the use of the ZnO NP EIL material often results in a charge imbalance within the quantum dot (QD) emitting layer (EML) and exciton quenching at the interface of the QD EML and ZnO NP EIL. To overcome these challenges, we introduced an arginine (Arg) interlayer (IL) onto the ZnO NP EIL. The Arg IL elevated the work function of ZnO NPs, thereby suppressing electron injection into the QD, leading to an improved charge balance within the QDs. Additionally, the inherent insulating nature of the Arg IL prevented direct contact between QDs and ZnO NPs, reducing exciton quenching and consequently improving device efficiency. An inverted QLED (IQLED) utilizing a 20 nm-thick Arg IL on the ZnO NP EIL exhibited a 2.22-fold increase in current efficiency and a 2.28-fold increase in external quantum efficiency (EQE) compared to an IQLED without an IL. Likewise, the IQLED with a 20 nm-thick Arg IL on the ZnO NP EIL demonstrated a 1.34-fold improvement in current efficiency and a 1.36-fold increase in EQE compared to the IQLED with a 5 nm-thick polyethylenimine IL on ZnO NPs.
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Evaluation of the insulating properties of polymers, such as the dielectric constant and dissipation factor, is crucial in electronic devices, including field-effect transistors and wireless communication applications. This study applies density functional theory (DFT) to predict the dielectric constant of soluble polyimides (SPIs). Various SPIs containing trifluoromethyl groups in the backbone with different pendant types, numbers, and symmetries are successfully synthesized, and their dielectric constants are evaluated and compared with the DFT-estimated values. Two types of DFT-optimized SPIs, single-chain and stacked-chain models, are used to describe the local geometries of the SPIs. In addition, to reveal the relationship between the molecular structure and dielectric constant, further investigations are conducted by considering the dielectric constant of composing ionic and electronic components. The DFT-estimated static dielectric constant of the single-chain model accurately reproduces the corresponding experimental value with at least 80% accuracy. Our approach provides a rational and accelerated strategy to evaluate polymer insulators for electronic devices based on cost-effective DFT calculations.
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Objective: Post-stroke shoulder pain (PSSP) is a common complication that limits the range of motion (ROM) of the shoulder, the patient's rehabilitation and in turn, affects the patients' quality of life (QOL). Several treatment modalities such as sling, positioning, strapping, functional electrical stimulation (FES), and nerve block have been suggested in literatures, however none of the treatments had long-term effects for PSSP. In this study, the authors evaluated clinical efficacy of pulsed radiofrequency (PRF) neuromodulation on the suprascapular nerve for PSSP, and suggested it as a potential treatment with long-term effect. Methods: This retrospective case series was conducted at a single center, a private practice institution. From 2013 to 2021, 13 patients with PSSP underwent PRF neuromodulation of the suprascapular nerve. The primary outcome measure was the visual analog scale (VAS) score. The secondary outcome measurements included the shoulder ROM, disability assessment scale (DAS), modified Ashworth scale (mAS), modified Rankin scale (mRS), and EuroQol-5 dimension-3L questionnaire (EQ-5D-3L) scores. These parameters were evaluated before PRF modulation, immediately after PRF modulation, and every three months until the final follow-up visit. Results: Six men and seven women were enrolled, and all patients were followed-up for a minimum of 12 months. The mean VAS score was 7.07 points before PRF neuromodulation and 2.38 points immediately post-procedure. Shoulder ROM for abduction and flexion, DAS for pain, mRS, and EQ-5D-3L demonstrated marked improvement. No complications were reported. Conclusion: PRF neuromodulation of the suprascapular nerve is an effective modality in patients with PSSP, and has long-term effect of pain relief, improvement of QOL.
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Gait event detection is essential for controlling an orthosis and assessing the patient's gait. In this study, patients wearing an electromechanical (EM) knee-ankle-foot orthosis (KAFO) with a single IMU embedded in the thigh were subjected to gait event detection. The algorithm detected four essential gait events (initial contact (IC), toe off (TO), opposite initial contact (OIC), and opposite toe off (OTO)) and determined important temporal gait parameters such as stance/swing time, symmetry, and single/double limb support. These gait events were evaluated through gait experiments using four force plates on healthy adults and a hemiplegic patient who wore a one-way clutch KAFO and a pneumatic cylinder KAFO. Results showed that the smallest error in gait event detection was found at IC, and the largest error rate was observed at opposite toe off (OTO) with an error rate of -2.8 ± 1.5% in the patient group. Errors in OTO detection resulted in the largest error in determining the single limb support of the patient with an error of 5.0 ± 1.5%. The present study would be beneficial for the real-time continuous monitoring of gait events and temporal gait parameters for persons with an EM KAFO.