Introduction to Electromagnetic Compatibility

Dramatic changes in the physical properties of composites occur when filler particles form a percolating network through the composite, particularly when the difference between the properties of the constitutive phases is large. By use of electric conductivity and dielectric properties as examples, recent studies on the physical properties of composites near percolation are reviewed. The effects of geometric factors and intrinsic properties of the fillers and the matrix, and especially of the interface between fillers and matrix, on electric and dielectric properties near percolation are discussed. Contact resistivity at the interface is less desirable for enhancing electrical conductivity. By contrast, an interface with high resistivity suppresses tunneling between adjacent fillers and leads to percolative composites with higher dielectric constant but lower dielectric loss. This review concludes with an outlook on the future possibilities and scientific challenges in the field.

Physical Properties of Composites Near Percolation

The mechanical flexibility and tunable properties of polymer-based materials make them attractive ones for a lot of applications. Exploring polymer-based dielectrics, such as ones used for capacitors and charge-storage applications, with high dielectric constant (high-j) has recently aroused considerable interest. Especially, motivated by higher function and further miniaturization of electronics, embedding (or integrating) polymer-based capacitors into the inner layers of organic printed circuit boards (PCBs) allows packaging substrate miniaturization and better electrical performance, which is a key for organic-based system-on-package technologies. But as capacitors, the relative dielectric constant j of general polymers (being good insulators) is too low (e.g., j< 5).Thus, a key issue is to substantially raise the dielectric constant of the polymers while retaining low dielectric loss. A few strategies have been developed to raise the j of polymer-based materials. A common approach is to add high-j ceramic fillers (e.g., BaTiO3) into a polymer. High loading of the ceramic fillers in the polymer composite, usually over 50 vol %, can increase j by about ten times relative to the polymer matrix, but dramatically decreases the adhesion of the composite (and increases its porosity) thus deteriorating the adaptability between the composite and the organic circuit boards. Another strategy is to fabricate percolative composite capacitors by using conductive fillers (e.g., metal particles). As the volume fraction f of the fillers increases to the vicinity of the percolation threshold fc, j of the composites can be dramatically enhanced as described by the well-known power law

High Dielectric Performance of Polymer Composite Films Induced by a Percolating Interparticle Barrier Layer

Методы подавления шумов и помех в электронных системах. (Noise reduction techniques in electronic systems)

European Union Risk Assessment Report

Interaction between Learners and Group Creativity in Art Learning: Focused on Online Teaching and Learning

Background Depression is a substantial global health problem, affecting >300 million people and resulting in 12.7% of all deaths. Depression causes various physical and cognitive problems, leading to a 5-year to 10-year decrease in life expectancy compared with the general population. Physical activity is known to be an effective, evidence-based treatment for depression. However, people generally have difficulties with participating in physical activity owing to limitations in time and accessibility. Objective To address this issue, this study aimed to contribute to the development of alternative and innovative intervention methods for depression and stress management in adults. More specifically, we attempted to investigate the effectiveness of a mobile phone–based physical activity program on depression, perceived stress, psychological well-being, and quality of life among adults in South Korea. Methods Participants were recruited and randomly assigned to the mobile phone intervention or waitlist group. Self-report questionnaires were used to assess variables before and after treatment. The treatment group used the program around 3 times per week at home for 4 weeks, with each session lasting about 30 minutes. To evaluate the program’s impact, a 2 (condition) × 2 (time) repeated-measures ANOVA was conducted, considering pretreatment and posttreatment measures along with group as independent variables. For a more detailed analysis, paired-samples 2-tailed t tests were used to compare pretreatment and posttreatment measurements within each group. Independent-samples 2-tailed t tests were conducted to assess intergroup differences in pretreatment measurements. Results The study included a total of 68 adults aged between 18 and 65 years, who were recruited both through web-based and offline methods. Of these 68 individuals, 41 (60%) were randomly assigned to the treatment group and 27 (40%) to the waitlist group. The attrition rate was 10.2% after 4 weeks. The findings indicated that there is a significant main effect of time (F1,60=15.63; P=.003; ηp2=0.21) in participants’ depression scores, indicating that there were changes in depression level across time. No significant changes were observed in perceived stress (P=.25), psychological well-being (P=.35), or quality of life (P=.07). Furthermore, depression scores significantly decreased in the treatment group (from 7.08 to 4.64; P=.03; Cohen d=0.50) but not in the waitlist group (from 6.72 to 5.08; P=.20; Cohen d=0.36). Perceived stress score of the treatment group also significantly decreased (from 2.95 to 2.72; P=.04; Cohen d=0.46) but not in the waitlist group (from 2.82 to 2.74; P=.55; Cohen d=0.15). Conclusions This study provided experimental evidence that mobile phone–based physical activity program affects depression significantly. By exploring the potential of mobile phone–based physical activity programs as a treatment option, this study sought to improve accessibility and encourage participation in physical activity, ultimately promoting better mental health outcomes for individuals with depression and stress.

https://jmir.org/api/download?alt_name=mhealth_v11i1e46286_app1.pdf&filename=43c4eb3835ddc436c0a1c8a0abe0338e.pdf

The Effectiveness of a Mobile Phone–Based Physical Activity Program for Treating Depression, Stress, Psychological Well-Being, and Quality of Life Among Adults: Quantitative Study

Epoxy/BaTiO/sub 3/ composite embedded capacitor films (ECFs) were newly designed for high dielectric constant and low tolerance (less than /spl plusmn/5%) embedded capacitor fabrication in organic substrates In terms of material formulation, ECFs were composed of specially formulated epoxy resin and latent curing agent And in terms of coating process, a comma roll coating method was used for a uniform film thickness over large area Dielectric constants of BaTiO/sub 3/ & SrTiO/sub 3/ composite ECFs were measured with MIM (metal-insulator-metal) capacitors at 100 kHz using LCR meter Dielectric constants of BaTiO/sub 3/ ECFs were larger than these of SrTiO/sub 3/ ECFs, due to the difference of permittivity of BaTiO/sub 3/ and SrTiO/sub 3/ particles Dielectric constants of BaTiO-, & SrTiO/sub 3/ ECFs at high frequency range (05/spl sim/10GHz) were measured using a cavity resonance method For both powders, dielectric constants in high frequency range were about 3/4 of the dielectric constants at 1 MHz This difference is mainly due to the decrease of dielectric constant of epoxy matrix For BaTiO/sub 3/ ECFs, there was a dielectric relaxation at 5/spl sim/9GHz presumably due to the polarization mode change of BaTiO/sub 3/ powder However in case of SrTiO/sub 3/ ECFs, there was no relaxation up to 10GHz

Epoxy/BaTiO/sub 3/ (SrTiO/sub 3/) composite films for high dielectric constant and low tolerance embedded capacitors fabrication in organic substrates

Background Depression is a severe illness that has accelerated with the spread of COVID-19 and associated lockdowns. As a result, reported physical activity has substantially decreased, further increasing depressive symptoms. Objective This study aims to explain the use of gamification principles to develop content for an interactive physical activity game for depression based on clinically proven depression diagnostic criteria. Methods We discuss related work in this field, the game design framework, the users’ depression severity, how we customize the contents accordingly, the gradual progression of the game to match exercise principles, and user flow optimization. Results We provide a brief description of each of the games developed, including instructions on how to play and design aspects for flow, audio, and visual feedback methods. Exergames (interactive physical activity–based games) stimulate certain physical fitness factors such as improving reaction time, endurance, cardiovascular fitness, and flexibility. In addition, the game difficulty progresses based on various factors, such as the user’s performance for successful completion, reaction time, movement speed, and stimulated larger joint range of motions. Cognitive aspects are included, as the user has to memorize particular movement sequences. Conclusions Mental health issues are linked to behavior and movement; therefore, future physical activity–based interactive games may provide excellent stimulation for inducing user flow, while physical activity can help train various physical fitness factors linked to depression.

Hyungsoo Kim

Papers

Interaction between Learners and Group Creativity in Art Learning: Focused on Online Teaching and Learning

The Effectiveness of a Mobile Phone–Based Physical Activity Program for Treating Depression, Stress, Psychological Well-Being, and Quality of Life Among Adults: Quantitative Study

Epoxy/BaTiO/sub 3/ (SrTiO/sub 3/) composite films for high dielectric constant and low tolerance embedded capacitors fabrication in organic substrates

Applying Gamification Principles and Therapeutic Movement Sequences to Design an Interactive Physical Activity Game: Development Study

Health Shocks and Mortgage Debt Payoff Among American Homeowners Over Age 50: A Survival Analysis