The Role of the Aryl Hydrocarbon Receptor in Vascular Factors Related to Preeclampsia in a Smoking Mouse Model.

Smoking cigarettes is known to lower the risk of preeclampsia. The objective of this study is to evaluate the effect of smoking on the expression of soluble FMS-like tyrosine kinase-1 (sFlt-1), vascular endothelial growth factor (VEGF), and endoglin (sEng)-1 and the role of the aryl hydrocarbon receptor (AhR) in pregnant mice. We developed a smoking mouse model using a gas-filling system. One or two cigarettes per day were exposed to each of the five pregnant mice for five days a week throughout pregnancy. AhR agonist and antagonist were injected. Serum levels and expression in the placenta of sFlt-1, VEGF, and sEng-1 were analyzed and compared among the cigarette smoke and no-exposure groups after delivery. Compared to the no-smoke exposure group, the serum level of sFlt-1 was significantly decreased in the two-cigarette-exposed group (p < 0.001). When the AhR antagonist was added to the two-cigarette-exposed group, sFlt-1 levels were significantly increased compared to the two-cigarette group (p = 0.002). The levels of sFlt-1 in the AhR antagonist group did not change regardless of two-cigarette exposure (p = 0.064). With the AhR agonist, sFlt-1 decreased significantly compared to the control (p = 0.001) and AhR antagonist group (p = 0.002). The sFlt-1 level was significantly decreased after the injection of the AhR agonist compared to the control group (p = 0.001). Serum levels of VEGF were significantly decreased in the one-cigarette-exposed group compared to the control group; however, there was no difference between the control and the two-cigarette-exposed groups. The placental expression of sFlt-1, VEGF, and sEng were inconsistent. This study offers insights into the potential role of AhR on antiangiogenic sFlt-1 associated with preeclampsia. It may support the invention of a new treatment strategy for preeclampsia using AhR activation.

The development, use, and challenges of electromechanical tissue stimulation systems.

BACKGROUND: Tissue stimulations greatly affect cell growth, phenotype, and function, and they play an important role in modeling tissue physiology. With the goal of understanding the cellular mechanisms underlying the response of tissues to external stimulations, in vitro models of tissue stimulation have been developed in hopes of recapitulating in vivo tissue function. METHODS: Herein we review the efforts to create and validate tissue stimulators responsive to electrical or mechanical stimulation including tensile, compression, torsion, and shear. RESULTS: Engineered tissue platforms have been designed to allow tissues to be subjected to selected types of mechanical stimulation from simple uniaxial to humanoid robotic stain through equal-biaxial strain. Similarly, electrical stimulators have been developed to apply selected electrical signal shapes, amplitudes, and load cycles to tissues, lending to usage in stem cell-derived tissue development, tissue maturation, and tissue functional regeneration. Some stimulators also allow for the observation of tissue morphology in real-time while cells undergo stimulation. Discussion on the challenges and limitations of tissue simulator development is provided. CONCLUSIONS: Despite advances in the development of useful tissue stimulators, opportunities for improvement remain to better reproduce physiological functions by accounting for complex loading cycles, electrical and mechanical induction coupled with biological stimuli, and changes in strain affected by applied inputs.

Gate Controlled Excitonic Emission in Quantum Dot Thin Films.

Formation of charged trions is detrimental to the luminescence quantum efficiency of colloidal quantum dot (QD) thin films as they predominantly undergo nonradiative recombination. In this regard, control of charged trion formation is of interest for both fundamental characterization of the quasi-particles and performance optimization. Using CdSe/CdS QDs as a prototypical material system, here we demonstrate a metal-oxide-semiconductor capacitor based on QD thin films for studying the background charge effect on the luminescence efficiency and lifetime. The concentration ratio of the charged and neutral quasiparticles in the QDs is reversibly controlled by applying a gate voltage, while simultaneous steady-state and time-resolved photoluminescence measurements are performed. Notably, the photoluminescence intensity is modulated by up to 2 orders of magnitude with a corresponding change in the effective lifetime. In addition, chip-scale modulation of brightness is demonstrated, where the photoluminescence is effectively turned on and off by the gate, highlighting potential applications in voltage-controlled electrochromics.

Telecommuting-related health outcomes during the COVID-19 pandemic in South Korea: a national population-based cross-sectional study.

BACKGROUND: Telecommuting has expanded greatly during the COVID-19 pandemic. Since the advent of remote working from home, there has been an ongoing controversy about the positive or negative health-related impact of telecommuting. This study aimed to investigate change in the occupational health risk in South Korean workers involved in telecommuting during the pandemic period compared to daily commuters. METHODS: A population-based cross-sectional study of South Korean workers using the secondary data from the 6th Korean Working Conditions Survey (2020-2021) was designed. A total of 12,354 white-collar wage employees were selected as the study sample. Telecommuting, depression, anxiety, insomnia, fatigue, musculoskeletal pain, headache-eye strain, absenteeism, and presenteeism were measured by self-reported data. Multiple logistic regression models, including gender stratification analysis, were used to estimate the adjusted odds ratio (AOR) with a 95% confidence interval (CI) for the health outcomes of telecommuters. RESULTS: Among the study population, 338 males and 318 females were reported to be telecommuters. The entirely adjusted regression model showed a positive association between telecommuting and anxiety (AOR = 2.82; 95% CI, 1.93-4.10), insomnia (AOR = 1.93; 95% CI, 1.27-2.92), fatigue (AOR = 1.76; 95% CI, 1.30-2.37), musculoskeletal pain (AOR = 1,76; 95% CI, 1.33-2.32), headache-eye strain (AOR = 1.94; 95% CI, 1.48-2.54), presenteeism (AOR = 1.66; 95% CI, 1.20-2.28) respectively. Gender difference was identified in that only female telecommuters had a higher risk of depression (AOR = 1.62; 95% CI, 1.04-2.53) and insomnia (AOR = 2.07; 95% CI, 1.26-3.41) than daily commuters in the adjusted model. CONCLUSION: Telecommuting was significantly associated with an increased risk of various health problems among South Korean workers and females were identified as a more vulnerable group. Although further research is required to ascertain the causal relationship, public health intervention should be considered to prevent the negative effects of telecommuting.

Microscale optoelectronic infrared-to-visible upconversion devices and their use as injectable light sources.

Optical upconversion that converts infrared light into visible light is of significant interest for broad applications in biomedicine, imaging, and displays. Conventional upconversion materials rely on nonlinear light-matter interactions, exhibit incidence-dependent efficiencies, and require high-power excitation. We report an infrared-to-visible upconversion strategy based on fully integrated microscale optoelectronic devices. These thin-film, ultraminiaturized devices realize near-infrared (∼810 nm) to visible [630 nm (red) or 590 nm (yellow)] upconversion that is linearly dependent on incoherent, low-power excitation, with a quantum yield of ∼1.5%. Additional features of this upconversion design include broadband absorption, wide-emission spectral tunability, and fast dynamics. Encapsulated, freestanding devices are transferred onto heterogeneous substrates and show desirable biocompatibilities within biological fluids and tissues. These microscale devices are implanted in behaving animals, with in vitro and in vivo experiments demonstrating their utility for optogenetic neuromodulation. This approach provides a versatile route to achieve upconversion throughout the entire visible spectral range at lower power and higher efficiency than has previously been possible.

Novel Dual-Curing Process for a Stereolithographically Printed Part Triggers a Remarkably Improved Interlayer Adhesion and Excellent Mechanical Properties.

Stereolithography (SL) is widely used because of its numerous advantages over other three-dimensional printing (3DP) techniques. However, SL is a layer-by-layer process, where interlayer adhesion between adjacent layers becomes more brittle than the intralayer adhesion, common to all 3DP process. Here, we report a facile method to strengthen the interlayer adhesion for SL. By the addition of monomers with thermally curable functional groups (epoxy or hydroxyl groups), thermal post-curing induces chemical reactions between them in adjacent layers after the photoinitiated printing process. It leads to fully 3D cured objects with enhanced interlayer bonding and substantially improved mechanical properties, but not a significant change in the dimensional stability. This approach can expand the use of 3DP techniques in load-bearing applications that require mechanically robust printed objects with precise dimensions.

Graded-Index Fluoropolymer Antireflection Coatings for Invisible Plastic Optics.

Plastic optics are used in an ever-expanding range of applications and yet a durable, high performance antireflection (AR) coating remains elusive for this material class. Here, we introduce a sacrificial porogen approach to produce ultralow refractive index nanoporous fluoropolymer AR coatings via thermal coevaporation of Teflon AF and the small molecule N, N'-bis(3-methylphenyl)- N, N'-diphenylbenzidine (NPD). Using this approach, we demonstrate a five-layer, step-graded AR coating that reduces the solar spectrum-averaged (400 < λ < 2000 nm) reflectance of acrylic plastic to <0.5% for incidence angles up to 40° and withstands over 3 months of outdoor rooftop exposure with minimal degradation. A trilayer coating optimized for the visible range yields luminous reflectivity down to ∼0.1%, effectively rendering double-side coated acrylic plastic invisible under room lighting conditions. Strong adhesion to most optical plastics, an outstanding combination of mechanical, chemical, and environmental durability, and compatibility with commercial vacuum coating systems should enable this AR technology to find widespread practical use.

Microwave Absorption and Shielding Property of Fe-Si-Al Alloy/MWCNT/Polymer Nanocomposites.

In recent years, there has been an increasing demand for electromagnetic interference (EMI) shielding with the development of advanced electronic devices and communication instruments because high-frequency microwaves generate undesired noise, which can affect the proper operation of commercial, military, and scientific electronic devices as well as the health of our human body. In this study, we investigated the effect of multiwalled carbon nanotube (MWCNT) addition to the Fe-Si-Al alloy (Sendust)/polymer blend on the electromagnetic wave absorption and electromagnetic interference (EMI) shielding. Ternary composites (flaky Fe-Si-Al alloy (Sendust)/MWCNTs/polymer) were fabricated using a twin-screw internal mixer and a roll-milling machine. The flaky Sendust alloy particles were well oriented in the roll-milling direction at a thickness of 1 mm, and MWCNTs were also well dispersed. The addition of MWCNTs increases the dielectric loss of the composite by increasing the interfacial polarizations and dipolar polarizations and generating conductive paths. The reflection loss reached -17 dB at 4.5 GHz with 5 wt % MWCNT addition, but the power loss in the near field rises more rapidly with MWCNT addition. The absorption efficiency of the ternary composite (Sendust/MWCNTs/polymer) was significantly increased compared to the binary composite (Sendust/polymer) due to dielectric property enhancement by MWCNT addition. The total shielding effectiveness (SE) value increased with the amount of MWCNT. The ternary hybrid composites are light but exhibit a high SE in a wide frequency range. Thus, they are appropriate for the production of light and thin-film materials that are suitable for electromagnetic wave absorption and EMI shielding.

Efficient Upper-Excited State Fluorescence in an Organic Hyperbolic Metamaterial.

Upper-excited state emission is not usually observed from molecules owing to competition with much faster nonradiative relaxation pathways; however, it can be made more efficient by modifying the photonic density of states to enhance the radiative decay rate. Here, we show that embedding the small molecule zinc tetraphenylporphyrin (ZnTPP) in a hyperbolic metamaterial enables an ∼18-fold increase in fluorescence intensity from the second singlet excited state ( S2) relative to that from the lowest singlet excited state ( S1). By varying the number of periods in the HMM stack, we are able to systematically tune the ZnTPP fluorescence spectrum from red (dominated by emission from S1) to blue (dominated by emission from S2) with an instrument-limited decay lifetime <10 ps. Our results are consistent with a broadband Purcell enhancement in the radiative rate of both transitions predicted via transfer matrix modeling and point to a general opportunity to harness upper-excited states for spectrally tunable, ultrafast fluorescence via radiative decay engineering.

Fracture Mechanism Change at a Heterogeneous Polymer-Polymer Interface Reinforced with in Situ Graft Copolymers.

Dynamic secondary-ion mass spectroscopy (DSIMS) was used to investigate the change in the failure mechanism at a heterogeneous polymer-polymer interface (polystyrene (PS)/polyamide (nylon 6, Ny6)) reinforced with in situ graft copolymers produced by the reaction between Ny6 molecules and poly(styrene- co-maleic anhydride) at the interface. The variation in fracture toughness with bonding time and temperature has been explained by two different failure mechanisms: adhesive failure at the interface for short bonding times and when the bonding temperature is low and cohesive failure between chains at the interface and bulk PS for longer bonding times and when the bonding temperature is high. DSIMS results provide the direct experimental evidence that the nonreactive molecules (PS) diffuse away from the high-potential interface, which induces the cohesive failure in the bulk of the nonreactive molecules (PS) after long annealing times. The change in the adhesion strength with temperature could also cause a change in the failure mechanism. Common features of the fracture mechanisms at heterogeneous interfaces reinforced by the in situ graft copolymers are outlined, which are independent of the polymer crystallinity.