Effects of Polybutylene Succinate Content on the Rheological Properties of Polylactic Acid/Polybutylene Succinate Blends and the Characteristics of Their Fibers.

Polylactic acid (PLA) and polybutylene succinate (PBS) are gaining prominence as environmentally friendly alternatives to petroleum-based polymers due to their inherent biodegradability. For their textile applications, this research is focused on exploring the effects of PBS content on the rheological properties of PLA/PBS blends and the characteristics of PLA/PBS blend fibers. PLA/PBS blends and fibers with varying PBS contents (0 to 10 wt.%) were prepared using melt-blending and spinning methods. Uniform morphologies of the PLA/PBS blends indicated that PBS was compatible with PLA, except at 10% PBS content, where phase separation occurred. The introduction of PBS reduced the complex viscosity of the blends, influencing fiber properties. Notably, PLA/PBS fibers with 7% PBS exhibited improved crystallinity, orientation factor, and elasticity (~16.58%), with a similar tensile strength to PLA fiber (~3.58 MPa). The results suggest that an optimal amount of PBS enhances alignment along the drawing direction and improves the molecular motion in PLA/PBS blend fiber. This study highlights the potential of strategically blending PBS to improve PLA fiber characteristics, promising advancement in textile applications.

Edge-Triggered Three-Dimensional Object Detection Using a LiDAR Ring.

Autonomous driving recognition technology that can quickly and accurately recognize even small objects must be developed in high-speed situations. This study proposes an object point extraction method using rule-based LiDAR ring data and edge triggers to increase both speed and performance. The LiDAR's ring information is interpreted as a digital pulse to remove the ground, and object points are extracted by detecting discontinuous edges of the z value aligned with the ring ID and azimuth. A bounding box was simply created using DBSCAN and PCA to check recognition performance from the extracted object points. Verification of the results of removing the ground and extracting points through Ring Edge was conducted using SemanticKITTI and Waymo Open Dataset, and it was confirmed that both F1 scores were superior to RANSAC. In addition, extracting bounding boxes of objects also showed higher PDR index performance when verified in open datasets, virtual driving environments, and actual driving environments.

Study on Associating Emotions in Verbal Reactions to Facial Expressions in Dementia.

The purpose of this study was to provide basic data on cognitive therapy and to improve social support programs for the elderly with dementia by identifying the difficulties they experienced in emotional communication by identifying how they recognized emotions in verbal reactions to facial expressions using Ekman's photographs of facial expressions and comparing their responses with the general elderly population. There were 141 participants in this study. Data collection was conducted from 3 April 2019 to 30 June 2019 in Seoul, in the Gyeonggi-do and Gangwon-do provinces of South Korea. This study performed descriptive research in which subjects made participative decisions with their guardian through recruitment. The tools used in this study included a general characteristic questionnaire and the Ekman 6 facial expressions photographs tool, which underwent intensive validity studies. The collected data were analyzed using the R version 3.5.1 statistic computing platform. The ability of the elderly with dementia to associate verbal expressions with facial expressions differed from that of the general elderly population. The rates of correct associations of verbal expressions to facial expressions were similar across dementia grades. There was a significant difference in the proportion of correct associations between positive and negative emotions in the elderly with dementia compared to the general elderly population. In the elderly with dementia, pictures showing fear, anger, and disgust had higher wrong rates of incorrect answers than correct answers. The average score of elderly with dementia in associating verbal expressions with six facial expressions was 2.69, which was even lower when they were asked to associate verbal expressions with pictures showing facial expressions of anger or disgust. This study shows that elderly persons with dementia have difficulties identifying two negative emotions (anger, disgust) and find it much easier to identify a positive emotion of happiness represented by a smiling face. Since the ability of the elderly with dementia to interpret verbal expressions to facial expressions was different from that of the general elderly population, careful attention and consideration are needed to support and communicate emotions to the elderly with dementia.

Synthesis of Thermoplastic Polyurethanes Containing Bio-Based Polyester Polyol and Their Fiber Property.

Among the starting materials of thermoplastic polyurethanes (TPUs), it was confirmed that succinic acid-based polyester biopolyols having different molecular weights (Mn = 1000, 2000, and 4000) affect the physicochemical properties of the final polymer significantly. Bio-TPUs synthesized through a solvent-free one-shot polymerization process were synthesized with a polyester polyol, 1,4 butanediol (BDO), and 4,4'-methylene diphenyl diisocyanate (MDI) in a molar ratio of 1:1:2. As a control group, one typical petroleum-based TPU was synthesized and characterized along with other bio-based TPUs. Representative petroleum-based and bio-based TPUs synthesized were manufactured as monofilaments with a diameter of about 0.2 mm through an extrusion process with different draw ratios (4, 5, and 6 times). The molecular weight and structural properties of the TPUs were characterized by GPC and FT-IR analysis and thermal characterization by DSC and TGA analysis. Petroleum-based TPU and bio-based TPU having the same molecular weight soft segment (SS) tended to have similar molecular weight and hard segment (HS) content. TPUs with high HS content had excellent thermal stability, enabling stable extrusion of TPUs. In addition, it was confirmed that the bio-based TPU fibers produced in this way had a tensile strength corresponding to the physical properties of petroleum-based TPU fibers and an excellent elastic recovery rate of almost 100 %. These results indicate the application potential of bio-TPU.

Vehicle Trajectory Prediction with Lane Stream Attention-Based LSTMs and Road Geometry Linearization.

It is essential for autonomous vehicles at level 3 or higher to have the ability to predict the trajectories of surrounding vehicles to safely and effectively plan and drive along trajectories in complex traffic situations. However, predicting the future behavior of vehicles is a challenging issue because traffic vehicles each have different drivers with different driving tendencies and intentions and they interact with each other. This paper presents a Long Short-Term Memory (LSTM) encoder-decoder model that utilizes an attention mechanism that focuses on certain information to predict vehicles' trajectories. The proposed model was trained using the Highway Drone (HighD) dataset, which is a high-precision, large-scale traffic dataset. We also compared this model to previous studies. Our model effectively predicted future trajectories by using an attention mechanism to manage the importance of the driving flow of the target and adjacent vehicles and the target vehicle's dynamics in each driving situation. Furthermore, this study presents a method of linearizing the road geometry such that the trajectory prediction model can be used in a variety of road environments. We verified that the road geometry linearization mechanism can improve the trajectory prediction model's performance on various road environments in a virtual test-driving simulator constructed based on actual road data.

A comparison of meta-analysis results with and without adjustment for the healthy worker effect: cancer mortality among workers in the semiconductor industry.

OBJECTIVES: This study compared the results of meta-analysis with and without adjustment for the healthy worker effect on the association between working in the semiconductor industry and cancer mortality. METHODS: Six studies that reported standardized mortality ratios (SMRs) for cancers were selected for meta-analysis. Using a random-effects model, the SMR results from each study were combined for all cancers and leukemias to estimate the summary SMRs (95% confidence interval, CI). To adjust for the healthy worker effect, the relative standardized mortality ratio (rSMR=SMRx/SMRnot x) were calculated using observed and expected counts for the specific cause of interest (i.e., all cancers and leukemias) and the observed and expected counts for all other causes of mortality. Then, the rSMR results were combined to estimate the summary rSMRs (95% CIs). RESULTS: The SMRs for all causes of mortality among semiconductor industry workers ranged from 0.25 to 0.80, which reflects a significant healthy worker effect. A remarkable difference was found between the summary SMRs and the summary rSMRs. The summary SMR for all cancers was 0.70 (95% CI, 0.63 to 0.79) whereas the summary rSMR was 1.38 (95% CI, 1.20 to 1.59). The summary SMR for leukemia was 0.88 (95% CI, 0.72 to 1.07), and the summary rSMR was 1.88 (95% CI, 1.20 to 2.95). CONCLUSIONS: Our results suggest that adjustment for the healthy worker effect (i.e., rSMR) may be useful in meta-analyses of cohort studies reporting SMRs.

The Enhanced Hydrogen Storage Capacity of Carbon Fibers: The Effect of Hollow Porous Structure and Surface Modification.

In this study, highly porous carbon fiber was prepared for hydrogen storage. Porous carbon fiber (PCF) and activated porous carbon fiber (APCF) were derived by carbonization and chemical activation after selectively removing polyvinyl alcohol from a bi-component fiber composed of polyvinyl alcohol and polyacrylonitrile (PAN). The chemical activation created more pores on the surface of the PCF, and consequently, highly porous APCF was obtained with an improved BET surface area (3058 m2 g-1) and micropore volume (1.18 cm3 g-1) compare to those of the carbon fiber, which was prepared by calcination of monocomponent PAN. APCF was revealed to be very efficient for hydrogen storage, its hydrogen capacity of 5.14 wt% at 77 K and 10 MPa. Such hydrogen storage capacity is much higher than that of activated carbon fibers reported previously. To further enhance hydrogen storage capacity, catalytic Pd nanoparticles were deposited on the surface of the APCF. The Pd-deposited APCF exhibits a high hydrogen storage capacity of 5.45 wt% at 77 K and 10 MPa. The results demonstrate the potential of Pd-deposited APCF for efficient hydrogen storage.

Correlation between levels of airborne endotoxin and heavy metals in subway environments in South Korea.

This study aimed to evaluate the exposure levels and variation in airborne endotoxin and heavy metals such as aluminum, chromium (Cr), iron (Fe), manganese (Mn), nickel (Ni), zinc, and lead (Pb) in the three different South Korean subway environments (driver room, station office, and underground tunnel) and identify subway characteristics influencing endotoxin and heavy metals levels. Air samples were collected and analyzed using the kinetic Limulus Amebocyte Lysate assay and inductively coupled plasma mass spectrometers. The geometric mean was determined for endotoxin levels (0.693 EU/m3). It was also found that Fe (5.070 µg/m3) had the highest levels in subway environments while Pb (0.008 µg/m3) had the lowest levels. Endotoxin levels were higher in the underground tunnel and lower in the station office; the total heavy metal levels showed the same pattern with endotoxin levels. Endotoxins and total heavy metal levels were higher in the morning than at night. Positive correlations were found between endotoxin and Cr, Fe, Mn, and Ni levels. Given the correlation between airborne endotoxins and heavy metals, further studies with larger sample sizes are needed to identify the correlation between levels of airborne endotoxin and heavy metals.

Effect of the Morphology and Electrical Property of Metal-Deposited ZnO Nanostructures on CO Gas Sensitivity.

The development of a highly sensitive gas sensor for toxic gases is an important issue in that it can reduce the damage caused by unexpected gas leaks. In this regard, in order to make the sensor accurate and highly responsive, we have investigated which morphology is effective to improve the sensitivity and how the deposited nanoparticle affects the sensitivity by controlling the morphology of semiconductor oxides-either nanorod or nanoplate-and depositing metal nanoparticles on the semiconductor surface. In this study, we compared the CO gas sensitivity for sensors with different morphology (rod and plate) of ZnO nanostructure with metal nanoparticles (gold and copper) photodeposited and investigated the correlation between the gas sensitivity and some factors such as the morphology of ZnO and the properties of the deposited metal. Among the samples, Au/ZnO nanorod showed the best response (~86%) to the exposure of 100 ppm CO gas at 200 °C. The result showed that the electrical properties due to the deposition of metal species also have a strong influence on the sensor properties such as sensor response, working temperature, the response and recovery time, etc., together with the morphology of ZnO.

Cu/CuO@ZnO Hollow Nanofiber Gas Sensor: Effect of Hollow Nanofiber Structure and P-N Junction on Operating Temperature and Sensitivity.

For the fast and easy detection of carbon monoxide (CO) gas, it was necessary to develop a CO gas sensor to operate in low temperatures. Herein, a novel Cu/CuO-decorated ZnO hollow nanofiber was prepared with the electrospinning, calcination, and photodeposition methods. In the presence of 100 ppm CO gas, the Cu/CuO-photodeposited ZnO hollow nanofiber (Cu/CuO@ZnO HNF) showed twice higher sensitivity than that of pure ZnO nanofiber at a relatively low working temperature of 300 °C. The hollow structure and p-n junction between Cu/CuO and ZnO would be considered to contribute to the enhancement of sensitivity to CO gas at 300 °C due to the improved specific surface area and efficient electron transfer.

The Morphological Effects of ZnO Upon the Antimicrobial and Deodorant Activities of Polyethylene Terephthalate/ZnO Composite Filaments.

In this study, the morphological effects of ZnO on the antimicrobial and deodorant activities of synthetic fibers were investigated. Three different polyethylene terephthalate (PET)/ZnO filaments were prepared by incorporating various ZnO nanostructures (rods, plates, and spheres) into PET filaments via a melt-spinning process. The antimicrobial activity of the as-prepared fibers was evaluated by the shake-flask method using two types of bacteria (Staphylococcus aureus and Klebsiella pneumoniae). The deodorant activity of the as-prepared fibers was evaluated by the gas detection tube method. All the PET/ZnO filaments exhibited excellent antimicrobial activity with a bacterial reduction value of 99.9%. The PET/ZnO rod filament showed the best deodorant performance of 60.0%. Both the antimicrobial and deodorant activities of the PET/ZnO filaments were influenced by the morphology of ZnO. However, the morphology of ZnO had a different effect on each functionality of the PET/ZnO filaments. The antimicrobial activity of the PET/ZnO filaments was mainly affected by the physical properties of ZnO rather than its morphology. By contrast, the deodorant activity of the PET/ZnO filaments was highly influenced by the morphology of ZnO.

Pulmonary Function Impairment From Exposure to Mixed Organic Solvents in Male Shipyard Painters.

OBJECTIVES: This study aimed to examine the effects of chronic exposure to organic solvents on lung function in a shipyard painters. METHODS: Male workers in the shipyard painting department were selected as the organic solvents exposure group. Exposure was classified according to the type of work usually performed, and the cumulative exposure index was obtained using the results of biological monitoring. These were then used to divide the exposure group into low-exposure and high-exposure groups, and the dose-response relationships were examined for decreased lung function. For ventilation indices, we obtained the forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), the FEV1/FVC ratio, and the maximal mid-expiratory flow (MMF) from the forced expiratory flow-volume curve and also calculated these as percentages of the predicted values. RESULTS: FVC and FEV1 showed no significant differences among the control, and low-exposure and high-exposure groups, but FEV1 as a percentage of its predicted value (%FEV1) decreased with increasing exposure at 90.0%, 90.9%, and 90.0% in the control, low-exposure, and high-exposure groups, respectively. MMF% predicted also decreased significantly at 98.5%, 90.1%, and 88.4% in the control, low-exposure, and high-exposure group, respectively, indicating that workers exposed to organic solvents showed obstructive respiratory disease. CONCLUSION: Exposure to organic solvents is associated with obstructive pulmonary dysfunction rather than restrictive pulmonary dysfunction.

Colorimetric hydrogen gas sensor based on PdO/metal oxides hybrid nanoparticles.

We have synthesized new colorimetric hydrogen-sensing materials, PdO/metal oxide hybrid nanoparticles, in which palladium oxide was loaded upon surface of substrate materials via an acid-base reaction between a H2PdCl4 solution and substrate materials, ZnO, MgO, TiO2, and SiO2 respectively at 25 °C. The colorimetric hydrogen gas sensing properties of all the samples, PdO/ZnO, PdO/MgO, PdO/TiO2 and PdO/SiO2, were characterized and compared in order to investigate how hydrogen gas sensitivity would be affected by surface property of substrate materials. It was confirmed that the amount of the loaded PdO, which was thought to be closely related with the colorimetric hydrogen sensitivity, was quite different according to the substrate materials and was increased with increasing of the basicity of substrate materials (ZnO > MgO > TiO2 > SiO2). Consequently, among the PdO/metal oxide hybrid nanoparticles, the largest amount of PdO was observed to be loaded on ZnO substrate nanoparticles due to its highest basicity. The best colorimetric hydrogen gas sensing properties (color difference, ΔE = 71.57) was observed in PdO/ZnO hybrid nanoparticles, showing the most prominent color change from brown to black, when the sample was exposed to hydrogen gas of 4 vol% balanced with nitrogen for 2 min.

Global hemostatic assay of different target procoagulant activities of factor VIII and factor IX.

BACKGROUND: Korean National Health Insurance reimburses factor VIII (FVIII) and factor IX (FIX) clotting factor concentrate (CFC) infusions to discrepant activity levels, allowing elevation of FVIII activity to 60 IU/dL and FIX to 40 IU/dL. We aimed to assess hemostatic response to these target levels using global hemostatic assays. METHODS: We enrolled 34 normal healthy men, 34 patients with hemophilia A, and 36 with hemophilia B, with residual factor activity of 3 IU/dL or less and without inhibitors. Patients with hemophilia A and B received injected CFCs according to reimbursement guidelines. Fifteen minutes after injection, we assessed hemostatic response with global hemostatic assays: thrombin generation assay (TGA), thromboelastography (TEG), and clot waveform analysis (CWA). RESULTS: Normal healthy men and patients with hemophilia A and B were 36.7, 37.2, and 35.1 years old, respectively. FVIII and recombinant FIX concentrate doses were 28.8 IU/kg and 43.6 IU/kg. Post-infusion FVIII activity rose from 0.5 IU/dL to 69.4 IU/dL, while FIX activity rose from 1.4 IU/dL to 46.8 IU/dL. Post-infusion peak thrombin concentrations in hemophilia A and B were 116.6 nM/L and 76.4 nM/L (P<0.001). Post-infusion endogenous thrombin potential (ETP) in hemophilia A and B was 1349.8 nM/min and 915.6 nM (P<0.001). TEG index of hemophilia A and B was 0.11 and -0.51 (P=0.006). CONCLUSION: Current reimbursed doses for FIX concentrates are insufficient to achieve hemostatic responses comparable to those after reimbursed doses for FVIII concentrates in terms of peak thrombin concentration, ETP, and TEG index.

Seasonality in airborne bacterial, fungal, and (1→3)-ß-D-glucan concentrations in two indoor laboratory animal rooms.

AIMS: The purpose of this study was to assess the temporal changes in the concentrations of bioaerosols in a laboratory mouse room (LMR) and laboratory rabbit room (LRR), and to determine environmental factors associated with the culturable bacteria, fungi and (1→3)-ß-D-glucan concentrations. METHOD: The concentrations of culturable airborne bacteria, fungi and (1→3)-ß-D-glucan in the LMR and LRR were sampled once a month from March 2011 to February 2012. A single-stage viable cascade impactor was used to sample bacteria and fungi, while a two-stage cyclone bioaerosol sampler was used to collect airborne (1→3)-ß-D-glucan. RESULTS: The culturable bacterial concentrations in the LMR showed a gradual increase during the summer. The culturable fungal concentrations showed similar seasonal patterns of change in the LMR and LRR with a noticeable increase during the summer. The (1→3)-ß-D-glucan concentrations were highest during the warmer spring and summer months. Relative humidity (RH) was the environmental factor most associated with the concentrations of culturable bacteria and fungi. The overall airborne microbe concentrations were significantly higher in the LRR than in the LMR. CONCLUSIONS: Airborne microbe concentrations in the LMR and LRR varied greatly depending on season, and these changes were affected by environmental factors.

Carbon nanotube composites multi-sensing characteristics based on electrical impedance properties.

CNT composites demonstrate sensory materials properties such as piezoresistivity, chemical and bio selectivity and they can detect structural deterioration, chemical contamination and bio signal by means of their impedance measurement (resistance and capacitance). In this study, electrical impedance characteristics of CNT composite electrodes are studied to simultaneously detect mechanical and chemical symptoms in engineering applications. We measured variations of electrical resistance and capacitance values of CNT composite electrodes under static load for mechanical sensing behavior and under the change of buffer solution amount for chemical sensing behavior. At the mechanical sensing behavior test, the resistance values changed quite linearly under bending and compression loads while the capacitance value varied within small range with invalid relationship to the loads. At the chemical sensing behavior investigation, the electrode's capacitance showed drastic change while the resistance value only changed within few percent range. The independently changing pattern of electrical impedance parameters according to mechanical strain and chemical effect can provide new opportunities to design a novel multifunctional sensor that can simultaneously monitor mechanical and chemical behaviors of a target system.

The bulk piezoresistive characteristics of carbon nanotube composites for strain sensing of structures.

The bulk piezoresistivity of carbon nanotube (CNT) in polymer matrix was discussed to develop a strain sensor for engineering applications. The polymer improves interfacial bonding between the nanotubes and the CNT composite and that enhances the strain transfer, repeatability, and linearity of the sensor. The largest contribution of piezoresistivity of the sensor may come from slippage of overlaying or bundled nanotubes in the matrix, from a macroscopic point of view. Nano interfaces of CNTs in a matrix polymer also contribute to the linear strain response compared to other micro size carbon filler. The strain sensor had a low bandwidth and adequate strain sensitivity. The nanocomposite strain sensor is particularly useful for detecting large strains which can monitor strain and stress on a structure with simple electric circuit for strain monitoring of structures.

Heterostructured nanohybrid of zinc oxide-montmorillonite clay.

We have synthesized heterostructured zinc oxide-aluminosilicate nanohybrids through a hydrothermal reaction between the colloidal suspension of exfoliated montmorillonite nanosheets and the sol solution of zinc acetate. According to X-ray diffraction, N2 adsorption-desorption isotherm, and field emission-scanning electron microscopic analyses, it was found that the intercalation of zinc oxide nanoparticles expands the basal spacing of the host montmorillonite clay, and the crystallites of the nanohybrids are assembled to form a house-of-cards structure. From UV-vis spectroscopic investigation, it becomes certain that calcined nanohybrid contains two kinds of the zinc oxide species in the interlayer space of host lattice and in mesopores formed by the house-of-cards type stacking of the crystallites. Zn K-edge X-ray absorption near-edge structure/extended X-ray absorption fine structure analyses clearly demonstrate that guest species in the nanohybrids exist as nanocrystalline zinc oxides with wurzite-type structure.

Trivalent atom contribution on solid-solid transformation of Ga13 polycation intercalated clay into sodalite investigated by X-ray absorption spectroscopy.

Solid-solid transformation mechanism of Ga Keggin-type ion intercalated clay into sodalite has been clarified by X-ray diffraction (XRD), FT-IR spectroscopy, and X-rayabsorption spectroscopy (XAS). To follow the structural evolution precisely by XANES and EXAFS, the XAS active element containing polycation [Ga13O4(OH)24(H2O)12]7+ was intercalated into montmorillonite (MMT). FT-IR and XAS spectra confirm that the formation of sodalite framework is initiated by the delocalized rearrangement between silicate networks and collapsed interlayered Ga species, and is followed by the incorporation of Al in the octahedral sheet of clay (MMT). According to the XAS studies, it is found that the formation of Ga(Al)-O-Si species is strongly influenced by the trivalent cations, which are rapidly changed in the environment, followed by reaction with the silicate network of clay during the solid-solid transformation.