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Although the reliability of flexible electronics during bending deformation is of great interest nowadays, the mechanical reliability that has mainly been investigated is of single electronic components or simple devices, such as metal interconnect, transparent conductive electrode, or thin-film devices, rather than that of the real package sample having complex structure and various materials. This study systematically investigated the mechanical reliability of flexible Si package sample consisting of Si die, polymer bump, and polymer substrate, by using individual resistance monitoring of the metal line, bump array, and total interconnect. For the bending test, the sample consisting of only Si die and polymer substrate shows abrupt electrical resistance increase below a bending radius of 3 mm, due to cracking of the Si die. For the bending fatigue test, the electrical resistance increases after 2000 cycles in 5 mm bending radius, due to fatigue failure of the metal line and bump array. Both the maximum bendability and fatigue lifetime can be significantly improved by covering with the molding layer. Finite element method simulation is conducted to analyze the mechanical stress distribution of the flexible package with and without molding layer during bending deformation. This study based on experimental results and simulation analysis can provide helpful guidelines for the design of highly reliable flexible packages.

The Tokyo Olympics held in 1964 opened the floodgates for a sporting rivalry between North and South Korea at the height of the Cold War. Although this keen competition would not take place on the field, the two Koreas carried out an ‘ideological battle’ to woo the Korean community in Japan, who were split by the pro-North Korean organization and the pro-South Korean organization. Deeply discontented by the ban imposed on a North Korean star athlete, the North Korean contingent withdrew from the Olympics at the last minute. Meanwhile, South Korea had the best record in its Olympic history at Tokyo, but this sporting accomplishment was completely dwarfed by the startling success of its former colonizer. In the wake of the Olympics, the public antagonism towards Japan reached its climax, mainly due to the treaty between Japan and South Korea in which the South Korean government sought to receive economic assistance rather than an official apology from Japan. Under these circumstances, the two Koreas would gear up for imminent sporting wars against each other and against Japan and the Western capitalist countries by restructuring their elite sports system under the banners of Chuche ideology in North and anti-communism coupled with anti-Japanese sentiments in South.

In past decades, stretchable conductors have been investigated for a wide range of applications, and the operation strain range of such devices varies by application. To commercialize stretchable devices, it is necessary to optimize the deformation of stretchable electrodes based on a given device elongation range. Therefore, we investigated the deformation mechanics of a silver nanowire (AgNW) electrode on an elastomeric substrate depending on its junction treatment method. At low-strain ( 20%), the thermally annealed AgNW electrode rapidly increased in resistance, while the laser-welded AgNW electrode showed lower resistivity change. By in situ surface analysis and a repetitive tensile test, we observed that the thermally annealed AgNW electrode shows less cracking at low strain but the laser-welded AgNW electrode exhibits fracturing of individual nanowires at low strain. Furthermore, at high strain, laser-welded AgNWs could slide to reduce stress during elongation, resulting in a smaller change in resistance compared to that of thermally annealed AgNW electrode. These results indicate that optimization of adhesion is necessary to fabricate stretchable devices based on deformation range.

Byblos, a Lebanese City, a UNESCO world heritage and one of the oldest continuously inhabited cities, is a member of the 100 Resilient Cities project. To help mitigate its stresses and chocks, Bybl...

Alcohol overconsumption and abuse leads to alcoholic liver disease (ALD), which is a major chronic liver disease worldwide. Field water-dropwort (Oenanthe javanica (Blume) DC.) is a small perennial herb and has been cultivated in Asia for thousands of years and traditionally used to treat various diseases including hepatitis, jaundice, hypertension and polydipsia, as well as its therapeutic benefits have been recognized for centuries in Asia. Although several studies have reported that water-dropwort extracts have pharmacological effects on various diseases, the pharmacological ability of fermented field water-dropwort in ALD is not reported yet. Thus, we investigated the effect of fermented field water-dropwort extracts (FDE) on chronic plus binge ethanol-induced liver injury. C57BL/6 male mice (9 weeks old) were fed on a Lieber–DeCarli diet containing 6.6% ethanol for 10 days with parallel saline or FDE orally administered each day. Ethanol-induced hepatic triglyceride (TG) levels and the mRNA levels of TG synthesis-related genes such as sterol regulatory element binding protein 1 (SREBP1), acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) were decreased in the liver of mice with FDE administration. Moreover, FDE administered mice showed decreasing ethanol-induced oxidative stress such as increasing oxidised glutathione and lipid peroxidation in the liver. In primary hepatic cells, FDE treated cells exhibited decreased ethanol-induced lipid accumulation and the mRNA levels of TG synthesis-related genes, SREBP-1, ACC and FAS. In conclusions, FDE has the potential to be explored as a candidate treatment agent for ALD by inhibiting TG synthesis and blocking of oxidative stress.

This study monitored particulates, and volatile organic compounds (VOCs) emitted from 3-D printers using acrylonitrile-butadiene-styrene copolymer (ABS) filaments at a workplace to assess exposure before and after introducing exposure mitigation measures. Air samples were collected in the printing room and adjacent corridor, and real-time measurements of ultrafine and fine particle were also conducted. Extensive physicochemical characterizations of 3-D printer emissions were performed, including real-time (size distribution, number concentration) nanoparticle characterization, size-fractionated mass distribution and concentration, as well as chemical composition for metals by ICP-MS and VOCs by GC-FID, real-time VOC monitors, and proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS). Air sampling showed low levels of total suspended particulates (TSP, 9–12.5/m3), minimal levels (1.93–4 ppm) of total volatile organic chemicals (TVOC), and formaldehyde (2.5–21.7 ppb). Various harmful gases, such as formaldehyde, acrolein, acetone, hexane, styrene, toluene, and trimethylamine, were detected at concentrations in the 1–100 ppb by PTR-TOF-MS when air sample was collected into the Tedlar bag from the front of the 3-D printer. Ultrafine particles having an average particle size (30 nm count median diameter and 71 nm mass median diameter) increased during the 3-D printing operation. They decreased to the background level after the 3-D printing operation, while fine particles continually increased after the termination of 3-D printing to the next day morning. The exposure to 3-D printer emissions was greatly reduced after isolating 3-D printers in the enclosed space. Particle number concentration measured by real-time particle counters (DMAS and OPC) were greatly reduced after isolating 3-D printers to the isolated place.

Tornadoes occur at a high frequency in the United States compared with other natural hazards but have a substantially small footprint. A single high-intensity tornado can result in high cas...

Biomonitoring of workers is an approach of evaluating workers’ exposure to chemicals and particulate matter by measuring biomarkers of parent chemicals, their metabolites, and reaction products in workers’ biospecimens. Prerequisites for biological monitoring in the workplace include permission to enter the workplace, approval of the study plan from the IRB (Institutional Review Board), and obtaining consent from workers. Because of the complex legal process involved in biomonitoring, few studies have been conducted so far on biomonitoring of workers’ exposures to nanoparticles and other hazards from emerging materials and advanced nanotechnologies. We have developed a cell-based biomonitoring device that can evaluate acute cytotoxicity and various other effect biomakers, such as inflammation, at realistic workplace exposure. This device is based on air–liquid interphase (ALI) and can be used to evaluate cell toxicity and early effect biomarkers along adverse outcome pathways. Following exposure of A549 lung epithelial cells in ALI to workplace air for 1–2 h, the cells were processed to assess the induction of inflammatory and cell damage biomarkers. Initially, we estimated the deposition rate of nanoparticles in the transwell by exposing the cell-free ALI device to silver nanoparticle aerosols (AgNP 20–30 nm) for 2 h in the laboratory. Then A549 lung epithelial cells cultured on the transwell in the ALI device were exposed to AgNP nanoaerosols for 2 h and evaluated for cytotoxicity and induction of mRNAs of pro-inflammatory cytokines IL-1b, IL-6, and TNF-α. Then the cells in the ALI device were exposed to 3-D printer emissions at the workplace and evaluated for the same matched endpoints. The mRNA levels for IL-1b, IL-6, and TNF-α increased significantly at the end of 2-h exposure of A549 cells to the positive control AgNP aerosols. These mRNAs, as well as LDH and microprotein concentrations, increased even more after 24-h post-exposure incubation (p < 0.05). Cytotoxicity evaluation of 3-D printer emissions at 810 and 957 μg/m3, which was more than 80 times higher than the airborne total suspended particulate concentrations in the workplace air (9–12.5 μg/m3), suggested no significant acute cytotoxicity at the end of 2-h exposure to 3-D-printing emission, as well as at 24-h post-exposure incubation. Hyperspectral microscopic observation showed that 3-D printers emitted particles to be attached to A549 cells after 2-h exposure, and many particles were internalized by A549 cells after 24 h of post-exposure incubation. The mRNA expression of pro-inflammatory cytokine IL-1b and IL-6 increased significantly after 2-h exposure to 3-D printer emissions and after 24-h incubation (only IL-6). In contrast, the expression of TNF-α mRNA decreased significantly after 2 h of exposure to 3-D printers and decreased even more after 24-h post-exposure incubation. These results support the use of cell-based ALI devices for direct assessment of airborne hazards in the workplace, for probing toxicological properties of airborne contaminants using adverse molecular pathways, and for guiding study design for workplace biomonitoring. ALI devices can bridge conventional exposure assessment with cellular toxicity testing platforms for hazard and risk assessment.

This paper evaluates the NVH characteristics of an air compressor for fuel cell electric vehicles(FCEVs) by conducting experimental as well as on-road tests. For the experiment, five eddy-current-type displacement sensors measured the vibration amplitudes of the shaft at the impeller and thrust runner ends, one three-axis accelerometer measured the acceleration of the compressor housing, and one microphone placed 1 m away from the test air compressor measured the acoustic pressure during rotor speed-up and coastdown up to 100 k r/min. For the on-road test, the air compressor was installed under the stack frame of a proto-type FCEV. The stack frame supports a fuel cell stack and is fixed on the sub-frame of the FCEV. In addition to five eddy-current-type displacement sensors and one three-axis accelerometer installed in the air compressor housing, two three-axis accelerometers installed on the stack frame and the sub-frame measured their accelerations during FCEV speed-up and break-down up to 115 km/h. One microphone installed 30 cm behind the air compressor recorded the acoustic pressure. All measured displacements, accelerations, and acoustic pressures were analyzed in the frequency domain. The test results revealed that the air compressor has the highest rotor vibrational amplitude and housing acceleration at the maximum rotor speed of 100 k r/min. However, the vibrations of the air compressor are well dampened while transmitteed to the sub-frame of the FCEV.

The electro-mechanical reliability of the metal layer on flexible substrates under repetitive mechanical deformations should be guaranteed for real commercialization of flexible electronics. The mechanical and electrical properties of metal films are closely related to their microstructure, which can be changed by thermal annealing during the fabrication process. This study investigates the reliability of an annealed Cu film on flexible substrates using tensile and bending fatigue tests, comparing it with a non-annealed sample. For the tensile test, the annealed Cu film exhibits a superior stretchability due to microstructure change including large grains. For the fatigue test, however, the annealed sample reliability decreases due to the acceleration of fatigue damage formation induced by the repetitive bending deformation. This study can provide useful information for designing of highly reliable flexible electronics.