ABSTRACT
Hierarchical structural design has been verified as a feasible strategy to fabricate effective electromagnetic wave (EMW) absorbers, so we designed hierarchical core-sheath composites with magnetic particles and dielectric layers. In this work, a hierarchical structure of carbon fiber (CF)@Fe3O4@MoS2 (CPDF7-M) was prepared by introducing Fe3O4 and depositing MoS2 layers on the surface of fibers. Due to the synergistic effects from the CF@Fe3O4 increasing the conductive and magnetic loss and the outer MoS2 layers improving the impedance matching, the optimal reflection loss (RL) value was -63.1 dB at 2.7 mm and the effective absorption bandwidth (EAB) was 9.1 GHz covering the X and Ku band. Moreover, the EAB values were adjusted with a specific MoS2 loading at different thicknesses, which provided the necessary reference for the construction of efficient and flexible absorbers in the EMW absorption fields.
ABSTRACT
Flexible dielectric and electronic materials with high dielectric constant (k) and low loss are constantly pursued. Encapsulation of conductive fillers with insulating shells represents a promising approach, and has attracted substantial research efforts. However, progress is greatly impeded due to the lack of a fundamental understanding of the polarization mechanism. In this work, a series of core-shell polymer composites is studied, and the correlation between macroscopic dielectric properties (across entire composites) and microscopic polarization (around single fillers) is investigated. It is revealed that the polarization in polymer conductor composites is determined by electron transport across multiple neighboring conductive fillers-a domain-type polarization. The formation of a core-shell filler structure affects the dielectric properties of tpolymer composites by essentially modifying the filler-cluster size. Based on this understanding, a novel percolative composite is prepared with higher-than-normal filler concentration and optimized shell's electrical resistivity. The developed composite shows both high-k due to enlarged cluster size and low loss due to restrained charge transport simultaneously, which cannot be achieved in traditional percolative composites or via simple core-shell filler design. The revealed polarization mechanism and the optimization strategy for core-shell fillers provide critical guidance and a new paradigm, for developing advanced polymer dielectrics with promising property sets.
ABSTRACT
The present study explored the moderating role of household chaos and gender in the relation between social avoidance and social adjustment among Chinese preschool migrant children. Participants were 148 children (82 boys, Mage = 62.63 months, SD = 0.05) from two kindergartens, Shanghai, People's Republic of China. Multi-source assessments included: (1) mother ratings of children's social avoidance; (2) mother ratings of families' household chaos; (3) teacher ratings of children's prosocial behavior, peer exclusion, interpersonal skills, and internalizing problems. Results showed that social avoidance significantly predicted peer exclusion among Chinese migrant preschoolers. Moreover, household chaos moderated the relationship between social avoidance and social adjustment. Specifically, at higher levels of household chaos, social avoidance was negatively associated with interpersonal skills. In contrast, social avoidance was not associated with interpersonal skills at a lower level of household chaos. In addition, social avoidance was positively associated with peer exclusion among boys but not girls. The current findings inform us of the importance of reducing household chaos to buffer the negative adjustment among socially avoidant young children who migrated from rural to urban China. The findings also highlight the need to pay particular attention to migrant socially avoidant boys' development in early childhood and the importance of considering the meaning and implication of social avoidance for migrant preschoolers in Chinese culture.
Subject(s)
East Asian People , Social Adjustment , Male , Humans , Child, Preschool , Child , China , Social Behavior , SchoolsABSTRACT
ABSTRACT Introduction: Chronic obstructive pulmonary disease (COPD) is a respiratory disease characterized by incomplete reversibility of airflow obstruction and persistent respiratory symptoms. Objective: To explore the therapeutic effect of physical exercise on patients with chronic obstructive pulmonary disease in pulmonary rehabilitation. Methods: Forty-eight experimental subjects were divided into control group, experimental group 1, and experimental group 2 for research. The control group received normal medical-related treatment without any other means of intervention. In addition to normal medical-related treatment, experimental group 1 received breathing training and educational interventions and experimental group 2 received exercise, breathing training and educational interventions. Results: The vital capacity of female subjects before and during the experiment ranged from 2.23±0.01 to 2.26±0.04, the FVC ranged from 2.00±0.02 to 2.01±0.03, the FEV1 ranged from 1.03±0.01 to 1.03±0.01,the FEV1% ranged from 55.50±1.29 to 55.25±1.71,the FEV1/FVC ranged from 51.44±0.24 to 50.84±1.00, andthe heart rate ranges from 65.00±0.82 to 65.50±1.29. Conclusions: Exercise training can increase the exercise tolerance of patients with COPD, relieve dyspnea, and improve the quality of life. Level of evidence II; Therapeutic studies - investigation of treatment results.
RESUMO Introdução: A doença pulmonar obstrutiva crônica (DPOC) é uma patologia respiratória caracterizada pela reversibilidade incompleta da obstrução ao fluxo aéreo e sintomas respiratórios persistentes. Objetivo: Explorar o efeito terapêutico do exercício físico em pacientes com doença pulmonar obstrutiva crônica sobre a reabilitação pulmonar. Métodos: Quarenta e oito participantes foram divididos em grupo controle, grupo experimental 1 e grupo experimental 2 para a realização do estudo. O grupo controle recebeu tratamento clínico normal, sem qualquer outra intervenção. Além do tratamento clínico normal, o grupo experimental 1 recebeu treinamento respiratório e intervenções educacionais e o grupo experimental 2 recebeu exercícios, treinamento respiratório e intervenções educacionais. Resultados: A capacidade vital de mulheres antes e durante o experimento variou de 2,23 ± 0,01 a 2,26 ± 0,04, a CVF variou de 2,00 ± 0,02 a 2,01 ± 0,03, o VEF1 variou de 1,03 ± 0,01 a 1,03 ± 0,01, o VEF1% variou de 55,50 ± 1,29 a 55,25 ± 1,71, a VEF1/CVF variou de 51,44 ± 0,24 a 50,84 ± 1,00, e a frequência cardíaca variou de 65,00 ± 0,82 a 65,50 ± 1,29. Conclusões: O treinamento físico pode aumentar a tolerância ao exercício de pacientes com DPOC, atenuar a dispneia e melhorar a qualidade de vida. Nível de Evidência II; Estudos terapêuticos - Investigação dos resultados do tratamento.
RESUMEN Introducción: La enfermedad pulmonar obstructiva crónica (EPOC) es una patología respiratoria caracterizada por la reversibilidad incompleta de la obstrucción del flujo aéreo y la persistencia de síntomas respiratorios. Objetivo: Explorar el efecto terapéutico del ejercicio físico en la rehabilitación pulmonar en pacientes con enfermedad pulmonar obstructiva crónica. Métodos: Cuarenta y ocho participantes fueron divididos en grupo de control, grupo experimental 1 y grupo experimental 2 para el estudio. El grupo de control recibió tratamiento clínico normal sin ninguna otra intervención. Además del tratamiento clínico normal, el grupo experimental 1 recibió entrenamiento respiratorio e intervenciones educativas y el grupo experimental 2 recibió ejercicios, entrenamiento respiratorio e intervenciones educativas. Resultados: La capacidad vital de las mujeres antes y durante el experimento osciló entre 2,23 ± 0,01 y 2,26 ± 0,04, la FVC entre 2,00 ± 0,02 y 2,01 ± 0,03, el FEV1 entre 1,03 ± 0,01 y 1, 03 ± 0,01, el FEV1% varió de 55,50 ± 1,29 a 55,25 ± 1,71, la FEV1/FVC varió de 51,44 ± 0,24 a 50,84 ± 1,00, y la frecuencia cardíaca varió de 65,00 ± 0,82 a 65,50 ± 1,29. Conclusiones: El entrenamiento físico puede aumentar la tolerancia al ejercicio en pacientes con EPOC, atenuar la disnea y mejorar la calidad de vida. Nivel de evidencia II; Estudios terapéuticos - Investigación de los resultados del tratamiento.
ABSTRACT
We adopted a person-centered approach to identify maternal feeding profiles among urban Chinese mothers of preschoolers, including two previously unexamined culturally-emphasized practices, and examine the associations between these feeding profiles and child and parent characteristics. Participants included 167 mothers and their preschoolers residing in Shanghai, China. Mothers reported on their feeding beliefs and practices, perceptions of child's body shapes, child dietary intake, and family demographic information. The hierarchical clustering method revealed 3 feeding clusters: uninvolved feeding (35.3%), concerned and restrictive feeding (21.6%), and high-pressure feeding (43.1%). Child BMI, weight status, maternal length of staying in Shanghai, maternal perceptions of child actual body shape and ideal body shape, and child unhealthy dietary intake were significantly different across the three clusters. The person-centered approach allowed for the examination of various feeding beliefs and practices simultaneously and revealed patterns of maternal feeding in Chinese families with preschoolers. Our oversampling of underweight and overweight groups of children in the present study allowed for the derivation of feeding profiles across children in all weight status groups. Moreover, the examination of whether demographic, maternal body shape perceptions, and child dietary intake differed across the clusters of mothers provided a more complete picture of family context and processes that may underlie and contribute to mothers' feeding practices, and ultimately their children's weight.
Subject(s)
Mothers , Thinness , Body Mass Index , Body Weight , Child , China , Feeding Behavior , Female , Humans , Overweight/epidemiologyABSTRACT
The Children's Sleep Habits Questionnaire (CSHQ) is widely used in clinical settings to screen for sleep problems in children aged 4-10 years. Existing studies on children in different cultures have included children across a wide age range and results have raised questions about CSHQ's psychometric quality. Our study addressed some of the limitations of existing studies by focusing on Chinese children within a much narrower age range of 4-5 years old. We tested the reliability and construct validity of the CSHQ in children living in Shanghai, China. Parents (mothers: 93%) of a random selected sample of kindergarten children aged 4-5 years (N=171; 46.8% boys; one target child per family) from Shanghai, China provided data on their children's sleep behaviors. CFA and EFA were conducted using Mplus 7.3. Weighted least squares with mean and variance adjusted (WLSMV) were used as the estimation method in Mplus, due to the ordinal nature of item responses. Our analyses showed that, similar to most existing studies, the eight subscales of CSHQ had low internal consistency, with Cronbach's alphas ranged from .11 (Night Waking) to .62 (Daytime Sleepiness). CFA failed to confirm the 8-factor structure. EFA suggested that a six-factor structure should be extracted. Subsequent CFA with a newly identified set of items from CSHQ led to the exclusion of two uninterpretable factors, leaving four factors with 28 items: Bedtime Behaviors (α=.59), Sleep Behaviors (α=.62), Morning Wakings (α=.69), and Daytime Sleepiness (α=.67). The four factors represented some improvement to the psychometric quality of the CSHQ. Based on our findings and those from other studies, we concluded that the CSHQ should be used with great caution.
