Paper Supercapacitor Developed Using a Manganese Dioxide/Carbon Black Composite and a Water Hyacinth Cellulose Nanofiber-Based Bilayer Separator.

Flexible and green energy storage devices have a wide range of applications in prospective electronics and connected devices. In this study, a new eco-friendly bilayer separator and primary and secondary paper supercapacitors based on manganese dioxide (MnO2)/carbon black (CB) are developed. The bilayer separator is prepared via a two-step fabrication process involving freeze-thawing and nonsolvent-induced phase separation. The prepared bilayer separator exhibits superior porosity of 46%, wettability of 46.5°, and electrolyte uptake of 194% when compared with a Celgard 2320 trilayer separator (39%, 55.58°, and 110%). Moreover, lower bulk resistance yields a higher ionic conductivity of 0.52 mS cm-1 in comparison to 0.22 mS cm-1 for the Celgard separator. Furthermore, the bilayer separator exhibits improved mean efficiency of 0.44% and higher specific discharge capacitance of 13.53%. The anodic and cathodic electrodes are coated on a paper substrate using MnO2/CB and zinc metal-loaded CB composites. The paper supercapacitor demonstrates a high specific capacitance of 34.1 mF cm-2 and energy and power density of 1.70 µWh cm-2 and 204.8 µW cm-2 at 500 µA, respectively. In summary, the concept of an eco-friendly bilayer cellulose separator with paper-based supercapacitors offers an environmentally friendly alternative to traditional energy storage devices.

Optimal Design of Validation Experiment for Material Deterioration.

For the deterioration model of a material, it is crucial to design a validation experiment to determine the ability of the deterioration model to simulate the actual deterioration process. In this paper, a design method of a validation experiment for a deterioration model is proposed to obtain the experiment scheme with low cost and satisfactory credibility. First, a normalized area metric based on probability density functions for the deterioration model is developed for validation results quantification. Normalized area metrics of different state variables in an engineering system can be applied to a unified evaluation standard. In particular, kernel density estimation is used to obtain smooth probability density functions from discrete experimental data, which can reduce the systematic error of the validation metric. Furthermore, a design method for the validation experiment for the deterioration model is proposed, in which the number of experimental samples and observation moments in each experimental sample are design variables, while the credibility of the validation experiment is the constraint. For the experiment design, the problem with varying dimensions of design variables occurred in the optimal design. Thus, a collaborative optimization method using the Latin hypercube sampling was developed to solve this problem. Finally, the results of the two examples showed the characteristics of the proposed metric and also reflected the correlation between the design variables and experimental credibility.

Effects of Electron Irradiation and Temperature on Mechanical Properties of Polyimide Film.

Polyimide (PI) is widely deployed in space missions due to its good radiation resistance and durability. The influences from radiation and harsh temperatures should be carefully evaluated during the long-term service life. In the current work, the coupled thermal and radiation effects on the mechanical properties of PI samples were quantitatively investigated via experiments. At first, various PI specimens were prepared, and electron irradiation tests were conducted with different fluences. Then, both uniaxial tensile tests at room temperature and the dynamic mechanical analysis at varied temperatures of PI specimens with and without electron irradiation were performed. After that, uniaxial tensile tests at low and high temperatures were performed. The fracture surface of the PI film was observed using a scanning electron microscope, and its surface topography was measured using atomic force microscopy. In the meantime, the Fourier-transform infrared spectrum tests were conducted to check for chemical changes. In conclusion, the tensile tests showed that electron irradiation has a negligible effect during the linear stretching period but significantly impacts the hardening stage and elongation at break. Moreover, electron irradiation slightly influences the thermal properties of PI according to the differential scanning calorimetry results. However, both high and low temperatures dramatically affect the elastic modulus and elongation at break of PI.

Research on dual-output port on-board charging system based on CLLC resonant converter.

This paper proposes a dual-output port on-board charging system based on a CLLC resonant converter, which can realize the function of simultaneously charging high-voltage power batteries and low-voltage batteries. The system topology is composed of a front-stage PFC and a latter-stage CLLC resonant converter. The system uses a three-port transformer to couple the resonant converter, the high-voltage charging circuit, and the low-voltage charging circuit. The system also realizes soft switching through resonant components. According to the design requirements of the charging system, the control strategy of the dual-output ports is determined by analyzing the working mode and gain characteristics of the system and the dual closed-loop control structure is designed to realize the functions of power factor correction and wide-range voltage regulation. Simulation and experimental results verify the correctness of theoretical analysis and structural design.

Tennis practice effects on male college students' physical function in different classes / Efeito da prática do tênis em diferentes classes sobre a função física dos estudantes universitários masculinos / Efecto de la práctica del tenis en diferentes clases sobre la función física de estudiantes universitarios varones

ABSTRACT Introduction Recent studies corroborate the statement that tennis practice affects the physical health of college students differently, depending on the evolutionary class in this sport. However, it is still necessary to consolidate a theoretical basis for college students to maximize the gain of benefits tennis practice, as a reference for teaching and updated training. Objective Provide a scientific and theoretical background to guide the physical exercise of college students. Methods An experimental study on different periods of tennis exercises in different classes during 16 weeks was carried out on 60 college students. Biological and anthropometric data were collected and statistically analyzed to verify the effects of the interventions. Maximizing results and best sports practices were discussed. Results The relatively long duration of a single exercise in tennis can improve the recovery rate of the cardiovascular response load, achieving greater gain from cardiovascular exercise. After 16 weeks of tennis exercise, both groups' progression rates significantly improved compared to college students with less practice. Conclusion Tennis exercise can improve lung function and cardiac function in male college students; the improvement in the physical function of students who practice tennis three times a week is significantly higher than male college students who practice tennis once a week. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

RESUMO Introdução Estudos recentes corroboram para a afirmativa de que prática do tênis afeta diferentemente a saúde física dos universitários, dependendo da classe evolutiva nesse esporte. Porém ainda é necessário consolidar uma base teórica para os estudantes universitários maximizarem o ganho dos benefícios da prática tênis, como uma referência para o ensino e treinamento atualizado. Objetivo Fornecer embasamento científico e teórico visando orientar o exercício físico dos estudantes universitários. Métodos Um estudo experimental sobre distintos períodos dos exercícios de tênis em diferentes turmas durante 16 semanas foi realizado em 60 universitários. Os dados biológicos e antropométricos foram coletados e analisados estatisticamente para verificar os efeitos das intervenções. Discutiu-se a maximização dos resultados e as melhores práticas esportivas. Resultados A duração relativamente longa de um único exercício no tênis pode melhorar a taxa de recuperação da carga de resposta cardiovascular, obtendo maior ganho com o exercício cardiovascular. Após 16 semanas de exercício no tênis, o índice de evolução dos dois grupos foi significativamente aprimorado em comparação com o índice evolutivo dos estudantes universitários com menor prática. Conclusão O exercício de tênis pode melhorar a função pulmonar e a função cardíaca dos estudantes universitários do sexo masculino, a melhoria da função física dos estudantes que praticam tênis três vezes por semana é significativamente superior aos estudantes universitários masculinos que praticam tênis uma vez por semana. Nível de evidência II; Estudos terapêuticos - investigação dos resultados do tratamento.

RESUMEN Introducción Estudios recientes corroboran por la afirmativa que la práctica del tenis afecta de manera diferente a la salud física de los estudiantes universitarios, dependiendo de la clase de evolución en este deporte. Sin embargo, sigue siendo necesario consolidar una base teórica para que los estudiantes universitarios aprovechen al máximo los beneficios de la práctica del tenis, como referencia para la enseñanza y la formación actualizada. Objetivo Proporcionar fundamentos científicos y teóricos para orientar el ejercicio físico de los estudiantes universitarios. Métodos Se llevó a cabo un estudio experimental sobre diferentes periodos de ejercicios de tenis en diferentes clases durante 16 semanas en 60 estudiantes universitarios. Se recogieron datos biológicos y antropométricos y se analizaron estadísticamente para verificar los efectos de las intervenciones. Se debatió sobre la maximización de los resultados y las mejores prácticas deportivas. Resultados La duración relativamente larga de un único ejercicio en tenis puede mejorar la tasa de recuperación de la carga de respuesta cardiovascular, consiguiendo una mayor ganancia del ejercicio cardiovascular. Tras 16 semanas de ejercicio de tenis, el índice de evolución de ambos grupos mejoró significativamente en comparación con el índice de evolución de los estudiantes universitarios con menos práctica. Conclusión El ejercicio de tenis puede mejorar la función pulmonar y cardiaca de los estudiantes universitarios varones, la mejora de la función física de los estudiantes que practican tenis tres veces por semana es significativamente mayor que la de los estudiantes universitarios varones que practican tenis una vez por semana. Nivel de evidencia II; Estudios terapéuticos - investigación de los resultados del tratamiento.

Inverse Design of Valley-Like Edge States of Sound Degenerated Away from the High-Symmetry Points in a Square Lattice.

Robust edge states of periodic crystals with Dirac points fixed at the corners or centers of the Brillouin zones have drawn extensive attention. Recently, researchers have observed a special edge state associated with Dirac cones degenerated at the high symmetric boundaries of the first irreducible Brillouin zone. These nodal points, characterized by vortex structures in the momentum space, are attributed to the unavailable band crossing protected by mirror symmetry. By breaking the time reversal symmetry with intuitive rotations, valley-like states can be observed in a pair of inequivalent insulators. In this paper, an improved direct inverse design method is first applied to realize the valley-like states. Compared with the conventional strategy, the preparation of transition structures with degeneracy points is skipped. By introducing the quantitative gauge of mode inversion error, insulator pairs are directly obtained without manually tuning the structure with Dirac cone features.

[Characteristics of Heavy Metals and Other Elements in Atmospheric Dry and Wet Deposition and Health Risk Assessment of a Typical Industrial and Mining City in Central Yunnan].

In order to study the characteristics of atmospheric dry and wet deposition elements and the health risks of typical industrial and mining cities in central Yunnan, the atmospheric dry and wet depositions collected from June 2019 to July 2020 in Anning city were selected as the research object and measured. The contents of the 11 indexes TN, F, Cr, Ni, Cu, Zn, Cd, Pb, P, As, and Hg were determined, the annual atmospheric deposition flux was calculated, and the exposure risk model was used to assess the risk to human health. The results showed that:1 In addition to Cr, Ni, and As in the atmospheric dry sediments, the average contents of the elements F, Cu, Zn, Cd, Pb, and Hg were significantly higher than those of the surface soil in Anning City, which were 5.82, 3.00, 28.27, 57.53, 2.83, and 1.08 times higher, respectively. The average contents of F and total nitrogen in wet deposition exceeded the standard value of surface water V-class water. 2 The annual atmospheric deposition flux of total nitrogen was the highest, and the annual deposition flux of eight heavy metal elements from smallest to largest was Hg

MTPA control of permanent magnet synchronous motor based on dual-vector model predictive control.

The vector control of the permanent magnet synchronous motor (PMSM) is affected by cross-coupling, output delay, parameter mismatch, and other factors; thus, resulting in its poor steady-state and insufficient dynamic performance. To address these problems, the design proposed in this study adopts a model predictive current control strategy. In the traditional model predictive control, the absolute value of the difference between the predicted output current of the inverter and the reference current is used as the cost function instead of the minimum value of the valence function, i.e., the optimal solution of the system, and the best switching state is outputted. The design proposed in this study adopts the dual-vector model to predict the current control. Firstly, the reference voltage vector was predicted on basis of the deadbeat idea, which reduced the calculation burden of processor. Next, in order to further improve the stability of the system, a two-vectors duty cycle calculation method was introduced. Then, simplifies the selection range of the two voltage vectors. While ensuring the accuracy of the voltage vector, the control is reduced. Reduce the amount of calculation in the system, thereby improving its robustness. Finally, based on the principle of current vector tracking error minimization, the duration of the selected voltage vector was determined. Last but not the least, the control strategy is applied to the MTPA control to increase the operating efficiency of the control motor. The improved control strategy can effectively reduce the torque ripple and improve the dynamic and steady-state performance of the system. Simulation results verify the feasibility and effectiveness of the proposed control algorithm.

Asymmetric Synthesis of Spiro[3,2'-morpholine-oxindoles] Derivatives via the [5 + 1] Annulation Reaction.

An efficacious method in which BINOL-type chiral imidodiphosphoric acid catalyzed the asymmetric [5 + 1] annulation reaction of 2-pyrrolylphenol with 1-methylindoline-2,3-dione was established. The strategy tolerated a broad substrate scope, and 30 examples were obtained. A range of enantioenriched spiro[3,2'-morpholine-oxindole] derivatives which incorporate a tertiary stereocenter, with moderate to excellent yields (up to 96%) and enantioselectivities (up to 99%) under mild conditions, was delivered.

Enantioselective Domino Reaction of 3-Vinylindole and p-Quinone Methides Enabled by Chiral Imidodiphosphoric Acids: Asymmetric Synthesis of Multisubstituted 3-Indolyl Cyclopenta[b]indoles.

The development of a stereoselective method for the rapid assembly of structurally complex molecules remains fascinating and challenging in synthetic organic chemistry. Here, we report an enantioselective domino reaction between 3-vinylindole and p-quinone methide for the preparation of 3-indolyl cyclopenta[b]indoles containing multiple chiral centers. Chiral imidodiphosphoric acids enable this cascade asymmetric process, delivering a series of products with excellent yields (≤99%), enantioselectivities (≤99%), and diastereoselectivities (≤20:1 dr).

Organocatalytic Asymmetric Synthesis of Biologically Relevant 3,3- Dihydroxyphenyloxindoles via para-Quinone Methides Derived from Isatins.

The first asymmetric synthetic approach to biologically relevant 3,3-diphenyloloxindoles was developed using para-quinone methides derived from isatins and phenols. Chiral phosphoric acid efficiently catalyzed the reaction and delivered 3,3-diphenyloloxindoles under mild conditions with up to an equivalent yield and excellent enantioselectivity (up to >99% ee). The chirality was maintained in further synthesis.

Asymmetric syntheses of spiro[benzofuro-cyclopenta[1,2-b]indole-indoline] scaffolds via consecutive cyclization.

An efficient method to construct enantioenriched spiro[benzofuro-cyclopenta[1,2-b]indole-indoline] scaffolds via consecutive cyclization is described here. The new scaffolds possess five successive chiral stereogenic centers and two spiroheterocycles. A range of highly enantioenriched scaffolds has been obtained with up to 93% yield, 99% ee and >19 : 1 d.r. catalyzed by Brønsted acid catalysts.

Parameter adaptive terminal sliding mode control for Full-Bridge DC-DC converter.

The poor dynamic performance problem of a Full-Bridge converter under a traditional control strategy is investigated in this study. A new parameter adaptive terminal sliding mode control policy is developed for a Full-Bridge DC-DC converter, by combining the integral part with the power function and differential function in the design of the sliding surface. In theory, the steady-state error of the system can approach zero within a short time. To manage the un-ideal situation after using a fixed value of power γ, an improved γ adaptive algorithm is proposed. The system output is tracked and γ is adjusted in real time. The effect of the system can be guaranteed always in an optimal state. Finally, simulation results are provided to verify the performance of the proposed design method under different conditions.

Asymmetric Synthesis of 1,1,1-Triarylethanes by Chiral Imidodiphosphoric Acid Catalyzed Nucleophilic Addition of Pyrrole and Indoles to 3-Vinylindoles.

Chiral imidodiphosphoric acids were employed as efficient catalysts in the enantioselective addition reaction of pyrrole and indoles to 3-vinylindoles. A series of optically active 1,1,1-triarylethmanes bearing quaternary stereocenters were synthesized in excellent yields (up to 99% yield) and enantioselectivities (up to 98% ee). Gram-scale reactions of 1i and 2a as well as 1o and 5a demonstrated the synthetic utility of this methodology. Control experiments showed that the formation of a double H-bond between the catalyst and substrates is necessary for an excellent outcome.

Structural and sorption properties of bio-nanocomposite films based on κ-carrageenan and cellulose nanocrystals.

There is an increased interest on changing the synthetic based materials to biodegradable ones, especially with natural polymers, polysaccharides or proteins. In this research we prepared bio-nanocomposite formulations with different component concentrations and investigated their structural features, with focus on the interactions, sorption properties, and how the combination between them influences these properties. By infrared spectroscopy, principal component analysis (PCA) and two-dimensional correlation spectroscopy (2DCOS) was identified that in the blending process are involved the -SO4 and C(4)-O-S groups of ß-d-galactose, CO groups, (O=S=O) of carrageenan and -OH and CO groups from CNCs. The water uptake and water sorption properties decrease with increasing the CNCs content in the formulations from about 15% for κ to 10% for κC15 and from about 128% for κ to 115% for κC15, respectively. The increase of the CNCs content induced an increase of the water contact angle from 47° for κ to 90° for κC15, indicating once again the involvement of the free hydroxyl groups in the hydrogen bonded interactions.

An analytic model of microfluidic system triggered by thermal expansion.

Microfluidics shows a great importance in fluid control in biomedicine area. Recently, a programmable soft microfluidic system for applications of pharmacology and optogenetics is reported in Cell. Based on the theory of thermal expansion, we established an analytic model to characterize the injection process of the microfluidic systems. Finite element analyses (FEA) were employed to validate this model. The comparison between the analytic model and FEA well demonstrates the practicality of the analytic model. We also make a parametric analysis of sphere radius, central angle and expandable layer thickness on the infusion volume of the system to optimize the design.

[Characterization of matrix effects in microanalysis of sulfide minerals by laser ablation-inductively coupled plasma-mass spectrometry based on an element pair method].

Matrix effect between reference materials and samples is one of the major factors affecting the accuracy of analytical results by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). However, there is no method or calculation formula to quantify matrix effect between standards and samples up to date. In this paper, the linear correlation coefficient r of the Ii/I(is-Ci)/Cis graphs of element pairs were used to characterize the matrix effect, which took the ratios of concentrations (ci/ c(is)) and intensities (Ii/Iis) of the analytical element and internal standard element as x-axis and gamma-axis, respectively. Matrix effects of 6 element pairs in 13 glass reference materials, 2 sulfide reference materials and 2 sulfide minerals using Fe as internal standard was studied, with the linear correlation coefficient r of Fe-Cu, Fe-Zn element pairs both less than 0. 999 and trace Fe--Mn, Fe--Co, Fe--Ga, Fe--Pb element pairs all better than 0.999. Matrix effects of 3 major element pairs in 2 sulfide ref- erence materials and 6 sulfide minerals using S as internal standard was also studied, with the linear correlation coefficient r of S--Fe, S--Cu, S--Zn all less than 0.999. The great majority of relative errors of EMPA analytical results for major elements in sulfide minerals were greater than 10%, whether analyzed using Fe as internal standard with glass reference materials as external standard, or S as internal standard with sulfide reference materials MASS-1, IMER-1 as external standard, respectively. But the most analytical results for trace elements calibrated by glass reference materials using Fe as internal standard were well agreed with sulfide standard MASS-1, with the relative errors less than 15%. The results showed that matrix effects existed in glass reference materials, sulfide reference materials and sulfide minerals, and it also proved a certain rationality and practicability for quantification of matrix effect using the linear correlation coefficient r of the Ii/Iis-Ci/Cis graphs by this element pair method. This study also indicated that trace elements in sulfide minerals could be calibrated using Fe as internal standard with non-matrix matched glass reference materials as external standard, especially for NIST610 contained nearly all the trace elements in sulfide minerals and with relative high concentrations of each element, which obtained analytical results agreed well with sulfide standard MASS-1.

[Comparison of FibroTouch and FibroScan for the assessment of fibrosis in chronic hepatitis B patients].

OBJECTIVE: To perform a comparative assessment of the performance of FibroTouch and FibroScan in patients with hepatitis B. METHODS: A total of 211 patients with hepatitis B, including cases of chronic hepatitis B (CHB) and of compensated cirrhosis, were enrolled for study between June and November of 2013. The patients underwent FibroScan testing (group 1) and FibroTouch testing (group 3), after which the operator examined a time motion ultrasound image from the FibroScan test and located a specific liver portion for focused FibroTouch testing (group 2). The consistency between the two tests' results was investigated by Pearson's correlation analysis, and the difference of liver stiffness between CHB patients and compensated cirrhosis patients was investigated by the two independent samples t-test or Mann-Whitney U test. RESULTS: The values of liver stiffness were 5.30 (4.30,8.65) in group 1,6.10 (4.70,8.90) in group 2, and 5.70 (4.50, 8.00) in group 3 (all P < 0.05); the Pearson correlation coefficients were all more than 0.8 (P < 0.05) and there was no statistically significant difference found between the results from FibroScan and FibroTouch.The values of liver stiffness were significantly different between the CHB patients and the compensated cirrhosis patients (P < 0.05). The rates of successful detection were 100% for FibroTouch and 97% for FibroScan. CONCLUSION: FibroTouch and FibroScan have good consistency in the evaluation of the degree of liver fibrosis. FibroTouch has a higher rate of successful detection than FibroScan.