Network Analysis of the Disaster Response Systems in the Waste of Electrical and Electronic Equipment Recycling Center in South Korea

Since dust and flammable gas are generated during the waste recycling process, there is always a risk of a fire accident. However, research on disaster management at recycling facilities deals only with the problem of processing systems from a technical standpoint and does not suggest concrete alternatives from a management aspect. Therefore, this study analyzed the influence of the disaster response network of a Waste of Electrical and Electronic Equipment (WEEE) recycling center at the organizational level based on the concept of the cognitive accuracy of a network considering administrative aspects. Accordingly, a survey was conducted using a structured questionnaire targeting 47 employees at the WEEE recycling center in South Korea and by applying the two-mode network analysis method using UCINET software, the centrality of the actor and the density of the network were quantitatively analyzed. Through this analysis, we confirmed that factors affecting the influence of the network exist, such that the entire network and the networks of different levels of position are different. We suggest that this can be improved by deploying safety and health management managers who perform formal tasks at the center of the network so that everyone can agree on the political approach and by empowering the safety and health management manager to conduct active education and training. Furthermore, we suggest that the network structure should be reorganized, centering on the person in charge of safety and health management to have a network system that matches each position

Estimating Electric Power Requirements for Mechanically Shredding Massage Chairs and Treadmills at a Recycling Plant

South Korea has operated under laws to collect and recycle the waste of electrical and electronic equipment (WEEE) utilizing a system based on the Extended Producer Responsibility (EPR) system since 2003. In 2020, the number of products managed by the EPR increased from 27 to 50. Among the 50 products, massage chairs and treadmills are recognized as the items avoided in recycling centers or by recyclers due to their large volume, large weight, and long disassembly times. This study was a preliminary study in which the physical shredding process for massage chairs and treadmills could be introduced, and the electrical power requirements calculated. In the methodology, Vickers hardness was measured by sampling two actual products, and the tensile and shear strength were calculated from the hardness. Based on the shear strength, the force affecting the cutter was calculated and converted into torque and horsepower. In particular, the actual specifications of the crusher, designed and operated in the recycling center, were applied to the study, and the design was based on the treatment capacity of 10 tons per hour. Conclusively, the proper electrical power for crushing the massage chair and treadmill was analyzed as 719.5 and 459.7 HP, respectively

Isolation of nb2se9 molecular chain from bulk one-dimensional crystal by liquid exfoliation

The optimum solvent for Nb2Se9 dispersion, which is a new type of one dimensional (1D) material, is investigated. Among several solvents (16 solvents in total), strong dispersion was observed in benzyl alcohol, isopropyl alcohol, isobutyl alcohol, and diacetone alcohol, which have medium dielectric constants in the range of 10 to 30 and surface tension in the range of 25 to 35 mJ m?2 . 1D Nb2Se9 chains, whose size is less than 10 nm, are well dispersed and it is possible to disperse mono-chains of 1 nm or less in a specific dispersion region. The 1D unit chain with dangling bond free surface and high volume to area ratio is expected to be used in applications that utilize the surface of the material. Such dispersion is an important first step towards various potential applications and is an indispensable scientific goal for the practical applications of Nb2Se9 . © 2018 by the authors. Licensee MDPI, Basel, Switzerlan

Engineering of a Biomimetic Pericyte-Covered 3D Microvascular Network

<div><p>Pericytes enveloping the endothelium play an important role in the physiology and pathology of microvessels, especially in vessel maturation and stabilization. However, our understanding of fundamental pericyte biology is limited by the lack of a robust <i>in vitro</i> model system that allows researchers to evaluate the interactions among multiple cell types in perfusable blood vessels. The present work describes a microfluidic platform that can be used to investigate interactions between pericytes and endothelial cells (ECs) during the sprouting, growth, and maturation steps of neovessel formation. A mixture of ECs and pericytes was attached to the side of a pre-patterned three dimensional fibrin matrix and allowed to sprout across the matrix. The effects of intact coverage and EC maturation by the pericytes on the perfused EC network were confirmed using a confocal microscope. Compared with EC monoculture conditions, EC-pericyte co-cultured vessels showed a significant reduction in diameter, increased numbers of junctions and branches and decreased permeability. In response to biochemical factors, ECs and pericytes in the platform showed the similar features with previous reports from <i>in vivo</i> experiments, thus reflect various pathophysiological conditions of <i>in vivo</i> microvessels. Taken together, these results support the physiological relevancy of our three-dimensional microfluidic culture system but also that the system can be used to screen drug effect on EC-pericyte biology.</p></div

Characterization of vascular morphological properties and comparison of EC monocultures and EC-pericyte co-cultures.

<p>(A) The 3D confocal image sectioned along the lines that divide the width of ROI into three equal parts. Cross sectional view of each portion clearly shows lumen formation of the blood vessel network (white arrows). (B) Vessel widths were measured along the sectioned lines. When two cells were cultured together, vessel width decreased significantly. The width of the pericyte-covered vessel increased again at the point region. (C, D) The numbers of junctions and branches increased significantly under co-culture conditions. The protective effect of pericytes from vessel dilation was significant when compared with the EC-only vessel at day 7 (E) and the pericyte-covered vessel at day 11 (F). CD31 (red) shows staining of ECs and α-SMA (green) shows staining of pericytes. Scale bar, 200 μm (A, B) or 100 μm (E, F) (n = 28 for EC monocultures, n = 26 for EC-pericyte co-cultures. *** p < 0.001).</p

Morphology of pericytes covering the abluminal surface of the blood vessel and their effect on PECAM-1 expression.

<p>(A) The confocal micrograph shows that pericytes are evenly distributed on the blood vessel network while covering the vessel. (B) Intact covering of the vessel with pericyte processes, as well as lumen formation of the blood vessel, can be observed based on the enlarged image of the white dotted box in (A). (C, D) PECAM-1 expression is broken occasionally in EC-only blood vessels (C) compared with continuous expression in pericyte-covered vessels. Microvascular networks were stained with anti-CD31 (red), the nucleus with Hoechst 33342 (blue), and pericytes with α-SMA (green). Scale bars, 100 μm (A, C, D) or 50 μm (B)</p

Effect of VEGF-A, TNFα and IL-1α on EC-pericyte association.

<p>Representative confocal images showed contrasting morphology of the blood vessels in response to different biochemical factors. In comparison with the control condition (A), VEGF-A (100ng/ml) treated vessels were dilated and pericytes showed contracted morphology (B). Inflammatory cytokines TNFα (10 ng/ml) (C) and IL-1α (10 ng/ml) (D) treated pericytes showed both distinct filopodia growth, but in different morphology. Scale bar 50 μm.</p

Basement membrane deposition of EC and EC-pericyte conditions.

<p>Immunofluorescent images show collagen IV (A, B) and laminin (C, D) deposition along the vascular abluminal surfaces. The fluorescent intensity of the basement membrane is significantly higher in pericyte-covered blood vessels (B, D) compared with EC-only vessels when stained and imaged under the same conditions. Scale bar, 100 μm.</p

Single-Chain Atomic Crystals as Extracellular Matrix-Mimicking Material with Exceptional Biocompatibility and Bioactivity

© 2018 American Chemical Society. In this study, Mo 3 Se 3- single-chain atomic crystals (SCACs) with atomically small chain diameters of ∼0.6 nm, large surface areas, and mechanical flexibility were synthesized and investigated as an extracellular matrix (ECM)-mimicking scaffold material for tissue engineering applications. The proliferation of L-929 and MC3T3-E1 cell lines increased up to 268.4 ± 24.4% and 396.2 ± 8.1%, respectively, after 48 h of culturing with Mo 3 Se 3- SCACs. More importantly, this extremely high proliferation was observed when the cells were treated with 200 μg mL -1 of Mo 3 Se 3- SCACs, which is above the cytotoxic concentration of most nanomaterials reported earlier. An ECM-mimicking scaffold film prepared by coating Mo 3 Se 3- SCACs on a glass substrate enabled the cells to adhere to the surface in a highly stretched manner at the initial stage of cell adhesion. Most cells cultured on the ECM-mimicking scaffold film remained alive; in contrast, a substantial number of cells cultured on glass substrates without the Mo 3 Se 3- SCAC coating did not survive. This work not only proves the exceptional biocompatible and bioactive characteristics of the Mo 3 Se 3- SCACs but also suggests that, as an ECM-mimicking scaffold material, Mo 3 Se 3- SCACs can overcome several critical limitations of most other nanomaterials