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•A perfect selective metamaterial absorber with four-pointed star prisms is proposed.•Mechanisms for the perfect spectral selectivity of the absorber are revealed.•High efficiencies ...of 92.31–77.78% are achieved at 1000 suns and 1273–1673 K.•The absorber exhibits good insensitivities to the polarization and incident angles.
Selective absorber is an important component for enhancing the solar-to-heat efficiency in high-temperature solar applications. In this paper, a selective metamaterial absorber possessing four-pointed star prisms was proposed and studied. Firstly, an optimal metamaterial absorber with perfect spectrally selective performance was obtained after optimizing the structure. It was found that the optimal absorber can achieve the high total solar absorptance of 0.958 and the low total emittance of 0.2355–0.4062, thus obtaining the high solar-to-heat efficiency of 92.31%-77.78% at 1000 suns and 1273–1673 K. Secondly, the underlying mechanisms for the good spectral selectivity of the optimal absorber were analyzed. The results showed that the high spectral absorptance in the solar spectrum owes to the impedance matching and the coupling effects of different plasmonic modes. The low spectral emittance within the mid-infrared band can be explained by the impedance mismatching. Thirdly, the effects of the geometrical parameters on the spectral selectivity of the absorber were studied, indicating that the height of the SiO2 layer above the star and the short diagonal length of the rhomb influence little on the spectral absorptance when they are in certain ranges. However, other parameters have obvious influences on the spectral absorptance. Finally, study on the effects of the polarization angle and incident angle indicated that the optimal absorber exhibits good insensitivities to the polarization angle and the incident angle. These results indicate that the proposed perfect absorber is a promising candidate for high-temperature solar applications.
Noninvasive and real‐time cuffless blood pressure (BP) measurement realizes the idea of unobtrusive and continuous BP monitoring which is essential for diagnosis and prevention of cardiovascular ...diseases associated with hypertension. In this paper, a wearable sensor patch system that integrates flexible piezoresistive sensor (FPS) and epidermal electrocardiogram (ECG) sensors for cuffless BP measurement is presented. By developing parametric models on the FPS sensing mechanism and optimizing operational conditions, a highly stable epidermal pulse monitoring method is established and beat‐to‐beat BP measurement from the ECG and epidermal pulse signals is demonstrated. In particular, this study highlights the compromise between sensor sensitivity and signal stability. As compared with the current optical‐based cuffless BP measurement devices, the sensing patch requires much lower power consumption (3 nW) and is capable of detecting subtle physiological signal variations, e.g., pre and postexercises, thus providing a promising solution for low‐power, real‐time, and home‐based BP monitoring.
A wearable sensor patch that integrates a flexible piezoresistive sensor and epidermal electrocardiogram sensors is demonstrated for extracting real‐time beat‐to‐beat blood pressure (BP) through a pulse transit time method. This sensing patch requires ultralow power consumption (3 nW) and is capable of detecting subtle physiological signal variations, e.g., pre‐ and post‐exercises, thus providing a promising solution for real‐time and home‐based BP monitoring.
Atrial fibrillation (AF), the most frequent cause of cardioembolic stroke, is increasing in prevalence as the population ages, and presents with a broad spectrum of symptoms and severity. The early ...identification of AF is an essential part for preventing the possibility of blood clotting and stroke. In this work, a real-time algorithm is proposed for accurately screening AF episodes in electrocardiograms. This method adopts heart rate sequence, and it involves the application of symbolic dynamics and Shannon entropy. Using novel recursive algorithms, a low-computational complexity can be obtained. Four publicly-accessible sets of clinical data (Long-Term AF, MIT-BIH AF, MIT-BIH Arrhythmia, and MIT-BIH Normal Sinus Rhythm Databases) were used for assessment. The first database was selected as a training set; the receiver operating characteristic (ROC) curve was performed, and the best performance was achieved at the threshold of 0.639: the sensitivity (Se), specificity (Sp), positive predictive value (PPV) and overall accuracy (ACC) were 96.14%, 95.73%, 97.03% and 95.97%, respectively. The other three databases were used for independent testing. Using the obtained decision-making threshold (i.e., 0.639), for the second set, the obtained parameters were 97.37%, 98.44%, 97.89% and 97.99%, respectively; for the third database, these parameters were 97.83%, 87.41%, 47.67% and 88.51%, respectively; the Sp was 99.68% for the fourth set. The latest methods were also employed for comparison. Collectively, results presented in this study indicate that the combination of symbolic dynamics and Shannon entropy yields a potent AF detector, and suggest this method could be of practical use in both clinical and out-of-clinical settings.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Continuous monitoring of arterial blood pressure (BP) outside of a clinical setting is crucial for preventing and diagnosing hypertension related diseases. However, current continuous BP ...monitoring instruments suffer from either bulky systems or poor user-device interfacial performance, hampering their applications in continuous BP monitoring. Here, we report a thin, soft, miniaturized system (TSMS) that combines a conformal piezoelectric sensor array, an active pressure adaptation unit, a signal processing module, and an advanced machine learning method, to allow real wearable, continuous wireless monitoring of ambulatory artery BP. By optimizing the materials selection, control/sampling strategy, and system integration, the TSMS exhibits improved interfacial performance while maintaining Grade A level measurement accuracy. Initial trials on 87 volunteers and clinical tracking of two hypertension individuals prove the capability of the TSMS as a reliable BP measurement product, and its feasibility and practical usability in precise BP control and personalized diagnosis schemes development.
Atrial fibrillation (AF) is the most common and debilitating abnormalities of the arrhythmias worldwide, with a major impact on morbidity and mortality. The detection of AF becomes crucial in ...preventing both acute and chronic cardiac rhythm disorders.
Our objective is to devise a method for real-time, automated detection of AF episodes in electrocardiograms (ECGs). This method utilizes RR intervals, and it involves several basic operations of nonlinear/linear integer filters, symbolic dynamics and the calculation of Shannon entropy. Using novel recursive algorithms, online analytical processing of this method can be achieved.
Four publicly-accessible sets of clinical data (Long-Term AF, MIT-BIH AF, MIT-BIH Arrhythmia, and MIT-BIH Normal Sinus Rhythm Databases) were selected for investigation. The first database is used as a training set; in accordance with the receiver operating characteristic (ROC) curve, the best performance using this method was achieved at the discrimination threshold of 0.353: the sensitivity (Se), specificity (Sp), positive predictive value (PPV) and overall accuracy (ACC) were 96.72%, 95.07%, 96.61% and 96.05%, respectively. The other three databases are used as testing sets. Using the obtained threshold value (i.e., 0.353), for the second set, the obtained parameters were 96.89%, 98.25%, 97.62% and 97.67%, respectively; for the third database, these parameters were 97.33%, 90.78%, 55.29% and 91.46%, respectively; finally, for the fourth set, the Sp was 98.28%. The existing methods were also employed for comparison.
Overall, in contrast to the other available techniques, the test results indicate that the newly developed approach outperforms traditional methods using these databases under assessed various experimental situations, and suggest our technique could be of practical use for clinicians in the future.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Increases in interracial marriage have been interpreted as reflecting reduced social distance among racial and ethnic groups, but little is known about the stability of interracial marriages. Using ...six panels of Survey of Income and Program Participation (N = 23,139 married couples), we found that interracial marriages are less stable than endogamous marriages, but these findings did not hold up consistently. After controlling for couple characteristics, the risk of divorce or separation among interracial couples was similar to the more-divorce-prone origin group. Although marital dissolution was found to be strongly associated with race or ethnicity, the results failed to provide evidence that interracial marriage per se is associated with an elevated risk of marital dissolution.
The United States is one of the major baby-receiving countries in the world. Relatively little research has focused on why there is such a high demand for intercountry adoption. Using in-depth ...qualitative interviews with adoptive parents, the authors explored the reasons why Americans prefer to adopt foreign-born children instead of adopting minority children domestically. Other than infertility reasons, concerns about domestic adoption, and the uneven domestic supply and demand of “desirable” children, the authors’ findings suggested that there was a perception that American children available for adoption presented difficult problems whereas foreign children presented interesting challenges. The “problems” inherent in children from American foster care were confounded with race differences. Studying adoption motivations will not only help us better understand the domestic adoption situation, especially why so many Black children are left behind in foster care, it may also reveal important insights into current race relations and distances between groups in the United States.
The form of online teaching in the information age has become the mainstream of the construction of civil aviation professional English courses in Civics. In this paper, the digital resource module ...for the English course Civics for Civil Aviation Professionals is screened out by combining it with the teaching design of the Civics course for civil aviation English courses. With the help of the subtitle text selection method and the semi-supervised model of S4VM to label the teaching resources of the English course Civics, the CUMPF model is used to recommend the teaching resources of the English course Civics. Collecting and organizing the online learning behavior data of flipped classrooms to explore the influence of long and short-acting course resource design factors on the continuity of online learning, and recommending teaching resources based on the analysis results. The results of the effectiveness of the construction of the civil aviation professional English course’s Civic and political construction are analyzed from the degree of integration of the course’s Civic and political elements as well as from the four dimensions of course background, course guarantee, course implementation, and course effect, respectively. The integration degree of English course Civics resources for civil aviation majors is the best, which can reach up to 3.9315. The overall construction scores of the English course Civics are 0.907, 0.809, 0.744, and 0.768. The construction of the course implementation dimension needs to be improved, and the teaching materials of the English course Civics need to be improved in terms of writing and design. Civil aviation majors can benefit from the study’s ability to check and fill in the gaps in the Civics and Politics of English course construction.
Inspired by the hierarchical micro/nanoscale structure and interfacial interactions of natural nacre, a variety of bioinspired layered materials were designed and prepared. However, the mechanical ...properties of the material were low according to the single interface interaction. In this study, we demonstrated strong and tough ternary bioinspired artificial nacre through synergistic toughening of graphene oxide (GO) and nanocellulose (CNF). Furthermore, the composites also realized a combination of multiple interfacial crosslinking strategies, including hydrogen bonding, ionic bonding and covalent bonding, which greatly improved the mechanical properties of the materials. The tensile strengths and toughnesses of the ternary bioinspired composites reached 528 MPa and 7.3 MJ/m3, which were 3.9 and 4.1 times that of natural nacre, respectively. In addition to their excellent tensile strengths and toughnesses, the composites also had good electrical properties with a conductivity of 56.2 S cm−1. This bioinspired ternary artificial nacre, with excellent mechanical and electrical properties, has potential applications in aerospace engineering, flexible electrodes, artificial muscles and tissue engineering.
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•In this work, graphene oxide/nanocellulose/polydopamine ternary bioinspired artificial nacre was prepared.•The ternary artificial nacre obtained through synergistic interface interactions has excellent mechanical properties.•Copper ions play a role in increasing mechanical properties and electrical conductivity in composites.
Ovarian cancer (OC) is one of the most commonplace gynecological malignancies. This study explored the effects of resveratrol (RES) on OC cell proliferation and apoptosis. Proliferation activity was ...measured for A2780 cells treated with RES for 24 h and 48 h at concentrations of 0, 10, 25, 50, 75, 100, 150, 200, and 300 µM. RNA sequencing (RNA-seq) was performed to analyze the circular RNA (circRNA), microRNA (miRNA), and messenger RNA (mRNA) expression spectrum. The differentially expressed genes included 460 circRNAs, 1988 miRNAs, and 1671 mRNAs, and they were subjected to analyses including Gene Ontology, the Kyoto Encyclopedia of Genes and Genomes (KEGG), and Reactome enrichment. We selected signaling pathways enriched in the cell processes by mRNA KEGG, comprehensively analyzed the circRNA-miRNA-mRNA regulatory network, and verified several miRNAs expressed in the regulatory network diagram using the quantitative real-time polymerase chain reaction. The data showed that the cell proliferation of A2780 cells treated with RES for 24 h or 48 h decreased with increasing concentrations of RES. The circRNA-miRNA-mRNA regulatory network that we constructed provides new insights into the ability of RES to inhibit cell proliferation and promote apoptosis in A2780 cells.
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