Droplet manipulation on structured shape memory polymer surface

While methods for dynamic tuning of surface wettability to manipulate water droplets have been widely explored for many applications including digital microfluidics, those based on dynamically changeable surface morphology have remained challenging to achieve. In this work, we present a structured shape memory polymer (SMP) surface which shows dynamically tunable surface wettability through changeable surface morphology in order to manipulate water droplets. The structured SMP surface involves a SMP pillar array consisting of nanotextured small and large pillars which can change its morphology between permanent and temporary shapes upon thermomechanical loading. Specifically, the structured SMP surface dynamically creates a surface morphological gradient and changes its surface wettability during thermally induced shape recovery of the SMP pillar array. Different wetting characteristics of the structured SMP surface between permanent and temporary shapes are theoretically predicted and experimentally verified. Based on these measured wetting characteristics, the structured SMP surface is designed to demonstrate that the morphological difference between two shapes under a water droplet overcomes contact angle hysteresis, resulting in driving a water droplet, when combined with the thermal Marangoni effect

Selenocysteine modulates resistance to environmental stress and confers anti-aging effects in C. elegans

OBJECTIVE: The free radical theory of aging suggests that cellular oxidative damage caused by free radicals is a leading cause of aging. In the present study, we examined the effects of a well-known anti-oxidant amino acid derivative, selenocysteine, in response to environmental stress and aging using Caenorhabditis elegans as a model system. METHOD: The response to oxidative stress induced by H2O2 or ultraviolet irradiation was compared between the untreated control and selenocysteine-treated groups. The effect of selenocysteine on lifespan and fertility was then determined. To examine the effect of selenocysteine on muscle aging, we monitored the change in motility with aging in both the untreated control and selenocysteine-treated groups. RESULTS: Dietary supplementation with selenocysteine significantly increased resistance to oxidative stress. Survival after ultraviolet irradiation was also increased by supplementation with selenocysteine. Treatment with selenocysteine confers a longevity phenotype without an accompanying reduction in fertility, which is frequently observed in lifespan-extending interventions as a trade-off in C. elegans. In addition, the age-related decline in motility was significantly delayed by supplementation of selenocysteine. CONCLUSION: These findings suggest that dietary supplementation of selenocysteine can modulate response to stressors and lead to lifespan extension, thus supporting the free radical theory of aging

The Effect of Imbalanced Carrier Transport on the Efficiency Droop in GaInN-Based Blue and Green Light-Emitting Diodes

The effect of strongly-imbalanced carrier concentration and mobility on efficiency droop is studied by comparing the onset voltage of high injection, the onset current density of the droop, and the magnitude of the droop, as well as their temperature dependence, of GaInN-based blue and green light-emitting diodes (LEDs). An n-to-p asymmetry factor is defined as sigma(n)/sigma(p), and was found to be 17.1 for blue LEDs and 50.1 for green LEDs. Green LEDs, when compared to blue LEDs, were shown to enter the high-injection regime at a lower voltage, which is attributed to their less favorable p-type transport characteristics. Green LEDs, with lower hole concentration and mobility, have a lower onset current density of the efficiency droop and a higher magnitude of the efficiency droop when compared to blue LEDs. The experimental results are in quantitative agreement with the imbalanced carrier transport causing the efficiency droop, thus providing guidance for alleviating the phenomenon of efficiency droop.114sciescopu

Increasing trend in rhegmatogenous retinal detachment in Korea from 2004 to 2015

Background To determine the 12-year incidence of and trends in rhegmatogenous retinal detachment (RRD) requiring surgery in Korea. Methods This was a nationwide, population-based, retrospective study. We identified 53,179 patients with incident RRD requiring surgery using the Korean National Health Claims Database from 2004 to 2015. We estimated the crude incidence rates and age- and sex-standardized incidence rates per 100,000 person-years in each year during the study period. A joinpoint regression analysis was performed to determine the trend. Results The average annual incidence rate was 9.78 (95% CI: 9.70–9.86). Male patients showed an incidence rate (10.68 [95% CI: 10.57–10.80]) 1.20 times that of female patients (8.87 [95% CI: 8.76–8.98]). The incidence showed a bimodal distribution; the highest peak was in the 60–64 year age group (23.77 [95% CI: 23.18–24.35]) and the second peak was in the 20–24 year age group (7.68 [95% CI: 7.41–7.95]). An increasing trend of RRD incidence was observed in the total population throughout the study period using joinpoint analysis (annual percentage change [APC], 2.05; 95% CI: 0.7–3.4). The increasing trend was more prominent among individuals aged under 50 years (APC, 3.44; 95% CI: 2.3–4.6), while among those aged 50 years or above, the increasing incidence was observed only in male patients. Conclusions In Korea, the incidence of RRD has increased recently. People in the < 50 year age group accounted for the major part of this significant increase, which is related to the increasing incidence of myopia in the young generation in Asia.This research was supported by a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health and Welfare, Republic of Korea (Grant Number: HI19C0373)

An Annular Array MPT for Enhanced Generation of Omnidirectional SH Waves in a Plate

If guided wave transducers are fabricated in an annular array type, the excitation and measurement of target guided wave modes could be considerably enhanced (see, e.g., [1]). Accordingly, various annular array transducers have been developed, including those generating omnidirectional Lamb waves in a plate. Here, we newly consider an annular array type MPT (magnetostrictive patch transducer) to generate enhanced SH (shear-horizontal) waves in a plate. This annular array MPT is based on our earlier development of an omnidirectional SH wave MPT [2]. For wave field analysis by the annular array SH wave MPT, the strain response in a plate due to wave excitation by the MPT is calculated by using the Green’s function approach [3]. Using the analysis, an optimal configuration of the annular array MPT which can maximize the transducer output at the given frequency is determined. For the validation of numerical predictions, a series of experiments with varying frequencies were carried out and the numerical results were found to be in good agreement with the experimental results

Incremental economic burden associated with exudative age-related macular degeneration: a population-based study

Background The exudative age-related macular degeneration (AMD) causes considerable healthcare costs for patients and healthcare system, which are expected to grow as the population ages. The objective of this study was to assess the incremental economic burden of exudative AMD by comparing total healthcare costs between the exudative AMD group and non-AMD group to understand economic burden related to exudative AMD. Methods This retrospective cohort study used the National Health Insurance Service database including the entire Korean population. Exudative AMD group included individuals with at least one claim for ranibizumab and one claim using the registration code for exudative AMD (V201). Non-AMD group was defined as individuals without any claims regarding the diagnostic code of H35.3 or ranibizumab. The exudative AMD group and non-AMD group were matched using a propensity-score model. Incremental healthcare resource utilization and healthcare costs were measured during a one-year follow-up by employing econometric models: ordinary least squares (OLS) with log transformation and heteroscedastic retransformation; and generalized linear model (GLM) with a log link function and gamma distribution. Results A total of 7119 exudative AMD patients were matched to 7119 non-AMD patients. The number of outpatient visits was higher in the exudative AMD group (P-value < 0.0001), while the length of hospitalization was shorter in exudative AMD group (P-value < 0.0001). Exudative AMD patients had total costs 2.13 times (95%CI, 2.08–2.17) greater than non-AMD group using OLS, and total costs 4.06 times (95%CI, 3.82–4.31) greater than non-AMD group using GLM. Annual incremental total costs were estimated as $5519 (OLS) and$3699 (GLM). Conclusions Exudative AMD was associated with significantly increased healthcare costs compared to the non-AMD group. Attention is needed to manage the socioeconomic burden of exudative AMD.This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (grant number: NRF-2016R1C1B1009198); and the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI19C0373). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript