Elasto-inertial microfluidic separation of microspheres with submicron resolution at high-throughput.

Elasto-inertial microfluidic separation offers many advantages including high throughput and separation resolution. Even though the separation efficiency highly depends on precise control of the flow conditions, no concrete guidelines have been reported yet in elasto-inertial microfluidics. Here, we propose a dimensionless analysis for precise estimation of the microsphere behaviors across the interface of Newtonian and viscoelastic fluids. Reynolds number, modified Weissenberg number, and modified elastic number are used to investigate the balance between inertial and elastic lift forces. Based on the findings, we introduce a new dimensionless number defined as the width of the Newtonian fluid stream divided by microsphere diameter. The proposed dimensionless analysis allows us to predict whether the microspheres migrate across the co-flow interface. The theoretical estimation is found to be in good agreement with the experimental results using 2.1- and 3.2-µm-diameter polystyrene microspheres in a co-flow of water and polyethylene oxide solution. Based on the theoretical estimation, we also realize submicron separation of the microspheres with 2.1 and 2.5 µm in diameter at high throughput, high purity (>95%), and high recovery rate (>97%). The applicability of the proposed method was validated by separation of platelets from similar-sized Escherichia coli (E.coli).

Microstructure, Tensile, and Fatigue Properties of Large-Scale Austenitic Lightweight Steel.

High-Mn lightweight steel, Fe-0.9C-29Mn-8Al, was manufactured using steelmaking, ingot-making, forging, and rolling processes. After the final rolling process, a typical austenite single phase was observed on all sides of the thick plate. The microstructural changes after annealing and aging heat-treatments were observed, using optical and transmission electron microscopy. The annealed coupon exhibited a typical austenite single phase, including annealing twins in several grains; the average grain size was 153 µm. After aging heat treatment, κ-carbide was observed within the grains and on the grain boundaries. Additionally, the effect of aging heat treatment on the mechanical properties was analyzed, using a tensile test. The fine κ-carbide that precipitated within the grains in the aged coupon improved the 0.2% offset yield and the tensile stresses, as compared to the as-annealed coupon. To estimate the applicability of high-Mn lightweight steel for low-pressure (LP) steam turbine blades, a low-cycle fatigue (LCF) test was carried out at room temperature. At a total strain amplitude of 0.5 to 1.2%, the LCF life of high-Mn lightweight steel was approximately three times that of 12% Cr steel, which is used in commercial LP steam turbine blades. The LCF behavior of high-Mn lightweight steel followed the Coffin-Manson equation. The LCF life enhancement in the high-Mn lightweight steel results from the planar dislocation gliding behavior.

Prediction of Metal Additively Manufactured Surface Roughness Using Deep Neural Network.

In recent years, manufacturing industries (e.g., medical, aerospace, and automobile) have been changing their manufacturing process to small-quantity batch production to flexibly cope with fluctuations in demand. Therefore, many companies are trying to produce products by introducing 3D printing technology into the manufacturing process. The 3D printing process is based on additive manufacturing (AM), which can fabricate complex shapes and reduce material waste and production time. Although AM has many advantages, its product quality is poor compared to conventional manufacturing systems. This study proposes a methodology to improve the quality of AM products based on data analysis. The targeted quality of AM is the surface roughness of the stacked wall. Surface roughness is one of the important quality indicators and can cause short product life and poor structure performance. To control the surface roughness, the resultant surface roughness needs to be predicted in advance depending on the process parameters. Various analysis methods such as data pre-processing and deep neural networks (DNN) combined with sensor data are used to predict surface roughness in the proposed methodology. The proposed methodology is applied to field data from operated wire + arc additive manufacturing (WAAM), and the analysis result shows its effectiveness, with a mean absolute percentage error (MAPE) of 1.93%.

An Updated Meta-Analysis of Remote Blood Pressure Monitoring in Urban-Dwelling Patients with Hypertension.

Following the coronavirus disease-2019 pandemic, this study aimed to evaluate the overall effects of remote blood pressure monitoring (RBPM) for urban-dwelling patients with hypertension and high accessibility to healthcare and provide updated quantitative summary data. Of 2721 database-searched articles from RBPM's inception to November 2020, 32 high-quality studies (48 comparisons) were selected as primary data for synthesis. A meta-analysis was undertaken using a random effects model. Primary outcomes were changes in office systolic blood pressure (SBP) and diastolic blood pressure (DBP) following RBPM. The secondary outcome was the BP control rate. Compared with a usual care group, there was a decrease in SBP and DBP in the RBPM group (standardized mean difference 0.507 (95% confidence interval [CI] 0.339-0.675, p < 0.001; weighted mean difference [WMD] 4.464 mmHg, p < 0.001) and 0.315 (CI 0.209-0.422, p < 0.001; WMD 2.075 mmHg, p < 0.001), respectively). The RBPM group had a higher BP control rate based on a relative ratio (RR) of 1.226 (1.107-1.358, p < 0.001). RBPM effects increased with increases in city size and frequent monitoring, with decreases in intervention duration, and in cities without medically underserved areas. RBPM is effective in reducing BP and in achieving target BP levels for urban-dwelling patients with hypertension.

Strain hardening recovery mediated by coherent precipitates in lightweight steel.

We investigated the effect of κ-carbide precipitates on the strain hardening behavior of aged Fe-Mn-Al-C alloys by microstructure analysis. The κ-carbides-strengthened Fe-Mn-Al-C alloys exhibited a superior strength-ductility balance enabled by the recovery of the strain hardening rate. To understand the relation between the κ-carbides and strain hardening recovery, dislocation gliding in the aged alloys during plastic deformation was analyzed through in situ tensile transmission electron microscopy (TEM). The in situ TEM results confirmed the particle shearing mechanism leads to planar dislocation gliding. During deformation of the 100 h-aged alloy, some gliding dislocations were strongly pinned by the large κ-carbide blocks and were prone to cross-slip, leading to the activation of multiple slip systems. The abrupt decline in the dislocation mean free path was attributed to the activation of multiple slip systems, resulting in the rapid saturation of the strain hardening recovery. It is concluded that the planar dislocation glide and sequential activation of slip systems are key to induce strain hardening recovery in polycrystalline metals. Thus, if a microstructure is designed such that dislocations glide in a planar manner, the strain hardening recovery could be utilized to obtain enhanced mechanical properties of the material.

Direct observation of dislocation plasticity in high-Mn lightweight steel by in-situ TEM.

To gain the fundamental understanding of deformation mechanisms in an aluminum-containing austenitic high-Mn steel (Fe-32Mn-8.9Al-0.78 C (wt.%)), in-situ straining transmission electron microscopy (TEM) analysis is conducted. The in-situ observation during the deformation demonstrates that the plastic deformation is accommodated by the pronounced planar dislocation gliding followed by the formation of slip bands (SBs) and highly dense dislocation walls (HDDWs). Experimental evidences of the glide plane softening can be obtained from the interaction between the gliding perfect dislocations and the L'12 ordered precipitates in the austenite matrix. Furthermore, the observation of the localized cross-slip of dislocations at the slip band intersections enables to understand why slip bands are extensively developed without mutual obstructions between the slip bands. The enhanced strain hardening rate of the aluminum-containing austenitic high-Mn steels can be attributed to the pronounced planar dislocation glides followed by formation of extensive slip band which prevent premature failure by suppressing strain localization.

The influence of anonymous peers on prosocial behavior.

BACKGROUND: Peer influence on students' maladaptive behaviors has been well documented; however, the influence on positive development is less acknowledged. PURPOSE: The purpose of this study was to examine anonymous peer influence on college students' prosocial behavior, specifically behavior for the improvement of society (i.e., donating money or participating in social campaigns) via an experimental approach. The effects of indirect peer influence (IP) and direct peer influence (DP) on college students' prosocial behavior were examined. METHODS: A total of 125 college students participated in an online survey and laboratory experiment. Self-reported helping behavior, social concern goals, and empathy were measured by the online survey. In the laboratory experiments, reading of a prosocial paragraph (IP) and confederates' prosocial behavior (DP) were manipulated. Participation in a signature campaign and money donation for illness were observed. Furthermore, 19 participants among those who donated were asked about their reasons for participating in such prosocial behavior. RESULTS: Prosocial behavior of anonymous peers (confederates) exerts a profound influence on college students' participation in a signature campaign and money donation, whereas the reading of a prosocial paragraph has no effect. Furthermore, no participants reported peer influence as a reason for engaging in prosocial behavior. CONCLUSION: This finding supports and extends recent research examining the positive impacts of anonymous peers on prosocial behavior. Prosocial behavior is not only a foundational and consistent aspect of personality, as previous studies report, but is also highly malleable and unstable in response to immediate situations.

Highly conductive and environmentally stable gold/graphene yarns for flexible and wearable electronics.

Here, we fabricated high-performance gold/graphene yarns through a facile method by the electroless deposition of gold nanoparticles onto the surface of graphene yarns. The gold/graphene yarns are fabricated using a completely solution-based process that can be scaled up for practical applications. They possess high electrical conductivity (2.86 × 102 S cm-1) and good gravimetric specific conductivity (6.81 × 102 S cm2 g-1) as well as good reliability under 1000 bending tests with a maximum bending angle of 170° and 10 washing tests with laundry detergents. These stable conducting yarns could also be integrated into textiles and clothes in various forms to create smart fabrics and wearable devices. In addition, this facile approach is easily applicable to various graphene films and devices on soft substrates that are presently used in flexible/wearable electronics.

Comparative study of goal contents and goal characteristics between medical and business students.

PURPOSE: Medical and business are one of the most popular majors among students, and both fields require intensive training to reach certain level of expertise. During the development of professionalism, goal can become a crucial role in psychological impetus. The purpose of this study is to compare goal contents, goal characteristics, and effect of goal characteristics on student's major satisfaction between medical and business. METHODS: A total of 193 undergraduate students (97 medical students, 96 business students) answered survey questions including goal contents, goal characteristics (goal autonomy, goal attainability, social value of goal) and satisfaction on their majors. Qualitative analysis of goal contents and quantitative analysis of goal characteristics, and their effects on student major satisfaction were performed. RESULTS: Goal content analysis showed percentage of social concern goal was higher in medical students (25.8%) than business students (6.3%), whereas percentage of wealth goal was higher business students (24.0%) than medical students (3.1%). Among goal characteristics, goal attainability and social value of goal were higher in medical students than business students. In both groups, social value of goal was significantly predict major satisfaction. CONCLUSION: Goal contents and goal characteristics are different between medical and business students. Curriculum and educational interventions that concerning students' goal and developing programs to enhance students' social value of goal is necessary.

Adaptive support vector regression for UAV flight control.

This paper explores an application of support vector regression for adaptive control of an unmanned aerial vehicle (UAV). Unlike neural networks, support vector regression (SVR) generates global solutions, because SVR basically solves quadratic programming (QP) problems. With this advantage, the input-output feedback-linearized inverse dynamic model and the compensation term for the inversion error are identified off-line, which we call I-SVR (inversion SVR) and C-SVR (compensation SVR), respectively. In order to compensate for the inversion error and the unexpected uncertainty, an online adaptation algorithm for the C-SVR is proposed. Then, the stability of the overall error dynamics is analyzed by the uniformly ultimately bounded property in the nonlinear system theory. In order to validate the effectiveness of the proposed adaptive controller, numerical simulations are performed on the UAV model.

Prevalence, correlates, and comorbidity of 12-Month tobacco dependence among ever-smokers in South Korea, during 1984-2001.

The rate of dependence among ever-users of a drug indicates the risk of developing dependence once an individual has been exposed to the drug. This is the first study to investigate 12-month tobacco dependence (TD) among ever-smokers in a community-based population. Analyses were based on two national studies of representative samples aged 18-64 in 1984 (n=5,025) and in 2001 (n=6,275), conducted with household visits and face-to-face interviews. The rates of 12-month TD among ever-smokers in men showed no significant difference between 51.6% in 1984 and 50.6% in 2001. On the contrary, the rates in women significantly increased from 33.3% in 1984 to 52.8% in 2001. After adjusting for the sociodemographic variables, 'male gender' was significantly associated with 12-month TD among eversmokers in 1984, but not in 2001. 'Unmarried' was significantly associated in 2001 but not in 1984. 'Alcohol dependence' was the only psychiatric disorder associated with 12-month TD in both study years. In conclusion, 12-month TD was found in about 50% of ever-smokers, and gender differences between the rates of 12-month TD which was observed in 1984 disappeared in 2001. Individuals with 12-month TD showed higher comorbidity with alcohol dependence than ever-smokers without TD.

Alcohol dependence, mortality, and chronic health conditions in a rural population in Korea.

To determine the effects of excessive drinking and alcohol dependency on mortality and chronic health problems in a rural community in South Korea, this study represents a nested case-control study. In 1998, we conducted the Alcohol Dependence Survey (ADS), a population survey of a village in Korea. To measure the effects of alcohol on chronic health conditions and mortality over time, in 2004, we identified 290 adults from the ADS sample (N=1,058) for follow-up. Of those selected, 145 were adults who had alcohol problems, either alcohol dependence as assessed in the ADS by the Severity of Alcohol Dependence Questionnaire (N=59), or excessive drinking without dependency (N=86). Further 145 nondrinkers were identified, matching those with alcohol problems in age and sex. We revisited the village in 2004 and completed personal interviews with them. In multivariate logistic regressions, the rates of mortality and morbidity of chronic health conditions were three times greater for alcohol dependents compared with the rate for nondrinkers. Importantly, however, excessive drinking without dependency was not associated with the rates of either mortality or morbidity. Future investigations would benefit by attending more specifically to measures for alcohol dependence as well as measures for alcohol consumption.

A prospective study on changes in health status following flood disaster.

OBJECTIVE: We examined changes in general health status, the prevalence of depression and post-traumatic stress disorder (PTSD) symptoms, and the existence of pre-trauma contributing factors in an agricultural population following a massive flood. METHODS: Eighty-three of 160 residents of Garisan-ni, Inje-gun, Gangwon-do, were assessed using the Korean version of the 36-Item Short-Form Health Survey (SF-36-K) between April and June 2006, just prior to a massive flood. Among those initially assessed, 58 residents were available for follow-up 18 months after the flood. Participants completed the SF-36-K, Beck Depression Index (BDI), Minnesota Multiphasic Personality Inventory (MMPI)-PTSD, and the Korean version of the Impact of Event Scale-Revised (IES-R) to detect depression and PTSD. Trauma experiences were also assessed. Factors related to changes in health status were then analyzed. RESULTS: SF-36-K total scale scores decreased significantly, suggesting a significant reduction in health-related quality of life. The largest reductions were noted in physical and social functioning. Fifty-three percent of the subjects were at least mildly depressed, and 17% had severe depression. In addition, 22% had PTSD on both the IES-R and MMPI-PTSD. Factors that contributed to the deterioration of health status following the flood were the number of disaster events and existence of depression (as assessed by the BDI). CONCLUSION: The flood was found to lead to deterioration of health status and to provoke depression and PTSD among the agricultural population in the mountainous region. We suggest that the number of disaster event experiences and existence of depression contriuted to changes in health status after the flood.

Curriculum-based measurement in the content areas: vocabulary matching as an indicator of progress in social studies learning.

The purpose of this study was to examine the reliability and validity of curriculum-based measures as indicator of growth in content-area learning. Participants were 58 students in 2 seventh-grade social studies classes. CBM measures were student- and administrator-read vocabulary-matching probes. Criterion measures were performance on a knowledge test, the social studies subtest of the Iowa Test of Basic Skills (ITBS), and student grades. Both the student- and examiner-read measures reflected change in performance; however, only the student-read measure resulted in interindividual differences in growth rates. Significant relations were found between the growth rates generated by the student-read vocabulary measure and student course grades, ITBS scores, and growth on the knowledge test. These results support the validity of a vocabulary-matching measure as an indicator of student learning in the content areas. The results are discussed in terms of the use of CBM as a system for monitoring performance and evaluating interventions for students with learning disabilities in content-area classrooms.