Investigation of thermal conductivity for liquid metal composites using the micromechanics-based mean-field homogenization theory.

For the facile use of liquid metal composites (LMCs) for soft, stretchable and thermal systems, it is crucial to understand and predict the thermal conductivity of the composites as a function of liquid metal (LM) volume fraction and applied strain. In this study, we investigated the effective thermal conductivity of LMCs based on various mean-field homogenization frameworks including Eshelby, Mori-Tanaka, differential and double inclusion methods. The double inclusion model turned out to make the prediction closest to the experimental results in a wide range of LM volume fractions. Interestingly, we found that the theoretical models based on the assumption of ideal LM dispersion and zero interfacial resistance underestimated the thermal conductivity compared to the experimental results in a low volume fraction regime. By considering the accompanied variations in the LM inclusion's aspect ratios under a typical size distribution of inclusions (∼µm), the change of effective thermal conductivity was predicted under a uniaxial 300% tensile strain. Our study will deepen the understanding of the thermal properties of LMCs and support the designs of stretchable thermal interfaces and packaging with LMCs in the future.

Epidemiological Characteristics of COVID-19 Outbreak at Fitness Centers in Cheonan, Korea.

BACKGROUND: In February 2020, a coronavirus disease 2019 (COVID-19) outbreak was reported in fitness centers in Cheonan, Korea. METHODS: From February 24 to March 13, an epidemiological investigation was conducted on the fitness center outbreak. All those who were screened were tested for severe acute respiratory syndrome coronavirus-2 (SARS CoV-2) using real-time reverse transcriptase polymerase chain reaction. Contacts were traced and self-isolated for 14 days. We determined the epidemiological characteristics of confirmed cases of SARS-CoV-2 infection, and estimated the time-dependent reproduction number to assess the transmission dynamics of the infection. RESULTS: A total of 116 cases were confirmed, and 1,687 contacts were traced. The source cases were 8 Zumba instructors who led aerobics classes in 10 fitness centers, and had the largest average number of contacts. A total of 57 Zumba class participants, 37 of their family members, and 14 other contacts were confirmed as cases. The attack rate was 7.3%. The contacts at Zumba classes and homes had a higher attack rate than other contacts. The mean serial interval (± standard deviation) were estimated to be 5.2 (± 3.8) days. The time-dependent reproduction number was estimated to be 6.1 at the beginning of the outbreak, but it dropped to less than 1, 2 days after the epidemiological investigation was launched. CONCLUSION: The results suggest that the COVID-19 outbreak was effectively contained with rigorous contact tracing, isolating, and testing in combination with social distancing without a lock-down.

Tape transfer printing of a liquid metal alloy for stretchable RF electronics.

In order to make conductors with large cross sections for low impedance radio frequency (RF) electronics, while still retaining high stretchability, liquid-alloy-based microfluidic stretchable electronics offers stretchable electronic systems the unique opportunity to combine various sensors on our bodies or organs with high-quality wireless communication with the external world (devices/systems), without sacrificing enhanced user comfort. This microfluidic approach, based on printed circuit board technology, allows large area processing of large cross section conductors and robust contacts, which can handle a lot of stretching between the embedded rigid active components and the surrounding system. Although it provides such benefits, further development is needed to realize its potential as a high throughput, cost-effective process technology. In this paper, tape transfer printing is proposed to supply a rapid prototyping batch process at low cost, albeit at a low resolution of 150 µm. In particular, isolated patterns can be obtained in a simple one-step process. Finally, a stretchable radio frequency identification (RFID) tag is demonstrated. The measured results show the robustness of the hybrid integrated system when the tag is stretched at 50% for 3000 cycles.

Comparison of clinical efficacy and safety of clopidogrel resinate with clopidogrel bisulfate in patients undergoing percutaneous coronary intervention.

OBJECTIVE: A new polymeric salt form of clopidogrel, clopidogrel resinate (CR), is a resinate complex of the (+)-clopidogrel optical isomer wherein the (+)-clopidogrel isomer binds to a water-soluble cation exchange resin via sulfonic acid groups. CR was approved for marketing by the Korean Food and Drug Administration based on a Phase I bioequivalence study. However, no data are available regarding its impact on adverse clinical outcomes in patients undergoing percutaneous coronary intervention (PCI). METHODS: Clopidogrel bisulfate (CB) was used exclusively from January 2004 through April 2010, after which CR was exclusively administered from May 2010 through September 2011, in 8 centers. We categorized the overall population (N = 10,487) into two groups according to the prescribed clopidogrel type: CB (n = 9,127) or CR (n = 1,360). To minimize the covariate imbalance and confounding in comparing CB and CR, we used a multivariable Cox proportional hazard regression model and the propensity score (PS) method to identify a 1:1 matched cohort (n = 2,470). We compared cumulative adverse outcomes during a 1-year follow-up after PCI in the overall population and in the PS-matched cohort. RESULTS: In the overall population, there is no difference in the 1-year cumulative event rates between the two groups (CB : CR) : composite of any death, nonfatal myocardial infarction or stroke (6.0 % vs. 6.0 %, adjusted HR, 0.82; 95 % CI, 0.61-1.11, p = 0.57), stent thrombosis (0.4 % vs. 0.2 %; adjusted HR, 0.40; 95 % CI, 0.09-1.72, p = 0.31), and bleeding (0.9 % vs. 0.6 %; adjusted HR, 0.67; 95 % CI, 0.28-1.58, p = 0.22). In the PS-matched cohort, the overall findings were consistent. CONCLUSIONS: In this large real-world PCI population, CR was as effective and as safe as CB in preventing adverse clinical outcomes.

Major depressive disorder, panic disorder, and post-traumatic stress disorder in Korean subway drivers.

PURPOSE: The purposes of this study are to investigate the prevalence of major depressive disorder, panic disorder, and post-traumatic stress disorder (PTSD) in Korean subway drivers, and find the association between these disorders and the drivers' person-under-train (PUT) experiences. METHODS: A total of 826 subway drivers who participated in a cross-sectional work and health survey were included for this study. The Korean version of the Composite International Diagnostic Interview 2.1 was applied to assess major depressive disorder, panic disorder, and PTSD. The date of PUT, whether victim died, and how many PUTs the drivers experienced were asked using a structured questionnaire. RESULTS: The standardized prevalence ratios (SPRs) for lifetime prevalence of panic disorder and PTSD in subway drivers were 13.3 (95 % confidence interval [CI] 6.6-22.4) and 2.1 (95 % CI 1.1-3.4), respectively. In lifetime prevalence, after adjusting for age, education, income, and working career, the drivers who experienced PUT had significantly higher risks for panic disorder (odds ratio [OR] = 4.2, 95 % CI 1.2-16.6) and PTSD (OR = 4.4, 95 % CI 1.3-16.4). In 1-year prevalence, the drivers who experienced PUT had a significantly higher risk for PTSD (OR = 11.7, 95 % CI 1.9-225.8). There was no significant value of SPR and OR in major depressive disorder. CONCLUSIONS: This study suggests that Korean subway drivers are at higher risk for panic disorder and PTSD compared to the general population, and PUT experience is associated with panic disorder and PTSD. Drivers who have experienced PUT should be treated quickly, sympathetically, and sensitively by a psychological professional and their colleagues, so they can return to work soon.

Secretome analysis of Magnaporthe oryzae using in vitro systems.

Magnaporthe oryzae is a devastating blast fungal pathogen of rice (Oryza sativa L.) that causes dramatic decreases in seed yield and quality. During the early stages of infection by this pathogen, the fungal spore senses the rice leaf surface, germinates, and penetrates the cell via an infectious structure known as an appressorium. During this process, M. oryzae secretes several proteins; however, these proteins are largely unknown mainly due to the lack of a suitable method for isolating secreted proteins during germination and appressoria formation. We examined the secretome of M. oryzae by mimicking the early stages of infection in vitro using a glass plate (GP), PVDF membrane, and liquid culture medium (LCM). Microscopic observation of M. oryzae growth revealed appressorium formation on the GP and PVDF membrane resembling natural M. oryzae-rice interactions; however, appresorium formation was not observed in the LCM. Secreted proteins were collected from the GP (3, 8, and 24 h), PVDF membrane (24 h), and LCM (48 h) and identified by two-dimensional gel electrophoresis (2DE) followed by tandem mass spectrometry. The GP, PVDF membrane, and LCM-derived 2D gels showed distinct protein patterns, indicating that they are complementary approaches. Collectively, 53 nonredundant proteins including previously known and novel secreted proteins were identified. Six biological functions were assigned to the proteins, with the predominant functional classes being cell wall modification, reactive oxygen species detoxification, lipid modification, metabolism, and protein modification. The in vitro system using GPs and PVDF membranes applied in this study to survey the M. oryzae secretome, can be used to further our understanding of the early interactions between M. oryzae and rice leaves.

Diffusion-weighted imaging and FDG PET/CT: predicting the prognoses with apparent diffusion coefficient values and maximum standardized uptake values in patients with invasive ductal carcinoma.

BACKGROUND: FDG PET/CT and DWI are both functional modalities that indirectly represent the biological characteristics of cancer, but there are few studies exploring the association between the two modalities and prognostic factors. Our study attempted to evaluate the mutual association by comparing the prognostic factors, SUV(max) value of PET/CT, and ADC values associated with diffusion imaging in invasive ductal carcinoma (IDC) patients. METHODS: Patients with pathologically confirmed IDC were recruited. There were 118 patients who underwent MRI, including DWI, FDG PET/CT, and immunohistochemical staining of the surgical specimen. Histologic analysis was done on tumor size, lymph node metastasis, expression of estrogen receptors (ER), progesterone receptors (PR), human epidermal growth factor receptor 2 (HER2), Ki-67, and epidermal growth factor receptors (EGFR). The relationship among ADC values, SUV(max) and prognostic factors were evaluated. RESULTS: There was significant association between the ADC value and ER-positive and HER2-negative expression. Significant associations were noted between SUV(max) and tumor size, lymph node metastasis, histologic grade, ER and PR expression, EGFR and Ki-67. However, there was no significant correlation between the ADC value and SUV(max). CONCLUSIONS: Even though there was no correlation between ADC and SUV(max), both indexes are useful for predicting the prognosis of IDC.

Comparative efficacy and safety of fimasartan in patients with hypertension: A network meta-analysis of randomized controlled trials.

Hypertension is a prevalent risk factor for cardiovascular disease. Angiotensin II receptor blockers are widely prescribed to patients with hypertension, while new drugs are continuously developed. However, data on comparative efficacy and safety of novel agents, such as fimasartan, are scarce. Here, we aimed to collect clinical evidence on different angiotensin II receptor blockers using a network meta-analysis. Randomized controlled trials whose follow-up time is within 12 weeks were identified from eight databases via a systematic literature review. Of the 7909 possibly relevant studies, 61 studies with 14,249 adult patients were included in the analysis. These studies were further subjected to quality appraisal using Cochran's Risk of Bias, and sitting systolic blood pressure was considered the primary endpoint. A Bayesian random effect generalized linear model was used for the network meta-analysis, and the treatment rank probability was determined. Olmesartan (standardized mean difference -0.987 [-1.29, -0.729]) and fimasartan (standardized mean difference -0.966 [-1.21, -0.745]) showed the highest rank probabilities (37% and 35%) in the 4-week group, considering the primary endpoint. Furthermore, the odds ratio of adverse events for all agents did not differ significantly from that of the placebo. The treatment rank of angiotensin II receptor blockers varied depending on the outcome type and follow-up period considerably. Fimasartan rapidly lowered blood pressure in 4 weeks, which was further maintained until 12 weeks, indicating its competent efficacy and tolerability. Our findings may help medical practitioners and patients to select the best angiotensin II receptor blocker against hypertension.

Platform Design and Preliminary Test Result of an Insect-like Flapping MAV with Direct Motor-Driven Resonant Wings Utilizing Extension Springs.

In this paper, we propose a platform for an insect-like flapping winged micro aerial vehicle with a resonant wing-driving system using extension springs (FMAVRES). The resonant wing-driving system is constructed using an extension spring instead of the conventional helical or torsion spring. The extension spring can be mounted more easily, compared with a torsion spring. Furthermore, the proposed resonant driving system has better endurance compared with systems with torsion springs. Using a prototype FMAVRES, it was found that torques generated for roll, pitch, and yaw control are linear to control input signals. Considering transient responses, each torque response as an actuator is modelled as a simple first-order system. Roll, pitch, and yaw control commands affect each other. They should be compensated in a closed loop controller design. Total weight of the prototype FMAVRES is 17.92 g while the lift force of it is 21.3 gf with 80% throttle input. Thus, it is expected that the new platform of FMAVRES could be used effectively to develop simple and robust flapping MAVs.

A Wearable Textile-Embedded Dielectric Elastomer Actuator Haptic Display.

With advances in mobile computing and virtual/augmented reality technologies, communicating through touch using wearable haptic devices is poised to enrich and augment current information delivery channels that typically rely on sight and hearing. To realize a wearable haptic device capable of effective data communication, both ergonomics and haptic performance (i.e., array size, bandwidth, and perception accuracy) are essential considerations. However, these goals often involve challenging and conflicting requirements. We present an integrated approach to address these conflicts, which includes incorporating multilayered dielectric elastomer actuators, a lumped-parameter model of the skin, and a wearable frame in the design loop. An antagonistic arrangement-consisting of an actuator deforming the skin-was used to achieve effective force transmission while maintaining a low profile, and the effect of the wearable frame and structure was investigated through lumped-model analysis and human perception studies.