Recent changes of surface particulate matter (PM) concentration in the Seoul Metropolitan Area (SMA), South Korea, are puzzling. The long-term trend of surface PM concentration in the SMA declined in ...the 2000s, but since 2012 its concentrations have tended to incline, which is coincident with frequent severe hazes in South Korea. This increase puts the Korean government's emission reduction efforts in jeopardy. This study reports that interannual variation of surface PM concentration in South Korea is closely linked with the interannual variations of wind speed. A 12-year (2004-2015) regional air quality simulation was conducted over East Asia (27-km) and over South Korea (9-km) to assess the impact of meteorology under constant anthropogenic emissions. Simulated PM concentrations show a strong negative correlation (i.e. R = -0.86) with regional wind speed, implying that reduced regional ventilation is likely associated with more stagnant conditions that cause severe pollutant episodes in South Korea. We conclude that the current PM concentration trend in South Korea is a combination of long-term decline by emission control efforts and short-term fluctuation of regional wind speed interannual variability. When the meteorology-driven variations are removed, PM concentrations in South Korea have declined continuously even after 2012.
This study aimed to clarify how masticatory muscle atrophy induced by botulinum toxin (BTX) injection affects cortical bone quality of the mandible using 3D modeling technology. A total of 39 young ...(26.9 ± 6.0 years) and 38 post-menopausal (55.3 ± 6.3 years) females were included. Computed tomography (CT) images were obtained before and after 12 months of treatment. Predictor variables were application of a stabilization splint, and/or two times of BTX injection in the bilateral temporalis and masseter muscles within a six-month interval. Outcome variables were changes in average Hounsfield units (HU) and cortical thickness of region of interest (ROI). 3D mandibular models were reconstructed using CT images, and models were used to calculate average HU and cortical thickness of ROIs, including inferior half of the lateral surface of ascending ramus, coronoid process, and temporomandibular joint condyle. Cortical bone quality at muscle insertion site was influenced by decreased muscle thickness but seemed not to be affected by decreased functional loading. Reduced functional loading seemed to influence cortical bone quality of the condyles. These effects were more remarkable in post-menopausal females. Hence, decreased masticatory muscle thickness may lead to alterations of the mandibular cortical structures, especially in post-menopausal females.
Interface modulation of nickel phosphide (Ni2P) to produce an optimal catalytic activation barrier has been considered a promising approach to enhance the hydrogen production activity via water ...splitting. Herein, heteronuclei‐mediated in situ growth of hollow Ni2P nanospheres on a surface defect‐engineered titanium carbide (Ti3C2Tx) MXene showing high electrochemical activity for the hydrogen evolution reaction (HER) is demonstrated. The heteronucleation drives intrinsic strain in hexagonal Ni2P with an observable distortion at the Ni2P@Ti3C2Tx MXene heterointerface, which leads to charge redistribution and improved charge transfer at the interface between the two components. The strain at the Ni2P@Ti3C2Tx MXene heterointerface significantly boosts the electrochemical catalytic activities and stability toward HER in an acidic medium via a combination between experimental results and theoretical calculations. In a 0.5 m H2SO4 electrolyte, the Ni2P@Ti3C2Tx MXene hybrid shows excellent HER catalytic performance, requiring an overpotential of 123.6 mV to achieve 10 mA cm−2 with a Tafel slope of 39 mV dec−1 and impressive durability over 24 h operation. This approach presents a significant potential to rationally design advanced catalysts coupled with 2D materials and transition metal‐based compounds for state‐of‐the‐art high efficiency energy conversions.
A Ni2P‐immobilized strategy by using Ti3C2Tx MXene as support is proposed. Defect‐engineering MXene induces the heteronuclei growth of nanospherical Ni2P. While surface‐anchored Ni2P nanospheres possess interfacial strain and hollow structure, the specific interface is responsible for a charge redistribution and optimizes electrochemical activity. Consequently, the hybrid catalyst exhibits low overpotential and high durability for hydrogen electrocatalysis in acidic medium.
The latest climate models realistically simulate the present‐day climate Indo‐Pacific Warm Pool (IPWP) area, but there is considerable inter‐model spread in future projections. Here we show a strong ...negative relationship between the present‐day of IPWP area and its future change. When using this “emergent relationship” to constrain future IPWP area change, inter‐model spread of future projections is reduced by more than half compared to raw projections. This emergent constraint is found to be due to the negatively skewed distribution of sea surface temperature (SST) over the Indo‐Pacific Ocean as well as a negative SST‐shortwave radiation feedback in the western Pacific, which leads to a large IPWP expansion in climate models having a small IPWP area in the present‐day climate. This result indicates that a more accurate simulation of the IPWP area in the present‐day climate is crucial to reliable future projections of the tropical climate.
Plain Language Summary
The Indo‐Pacific Warm Pool (IPWP) is a key driver of global rainfall distribution due to its vast evaporation, deep convection, and large precipitation. Increasing of human‐induced greenhouse‐gases contributed to the observed IPWP expansion, but there is a great uncertainty in its future projections. Here, we identify multi‐model means of the latest climate models simulate the realistic IPWP in the present‐day climate and a strong negative correlation between the IPWP area in the present‐day climate and its future changes, which is an “emergent relationship.” Based on this relationship, we constrain the uncertainty of future IPWP changes by more than half the raw projections. This negative correlation is due to a negatively skewed distribution of the Indo‐Pacific Ocean sea surface temperature, leading the large IPWP expansion in climate models simulating a small IPWP in the present‐day. Thus, an improved performance of the model simulation for the IPWP in the present‐day climate is important for its reliable future projections.
Key Points
The Coupled Model Intercomparison Project Phase 6 (CMIP6) models reproduce the observed IPWP area with a large inter‐model difference, causing a great uncertainty in future projections
The negative correlation between the present‐day state and a future change provides an emergent constraint to reduce the projection uncertainty
The negatively skewed distribution of the tropical SST leads to a different increasing rates of warm pool area to global warming
The effects of exendin-4 on Sirt1 expression as a mechanism of reducing fatty liver have not been previously reported. Therefore, we investigated whether the beneficial effects of exendin-4 treatment ...on fatty liver are mediated via Sirt1 in high-fat (HF) diet-induced obese C57BL/6J mice and related cell culture models. Exendin-4 treatment decreased body weight, serum free fatty acid (FA), and triglyceride levels in HF-induced obese C57BL/6J mice. Histological analysis showed that exendin-4 reversed HF-induced hepatic accumulation of lipids and inflammation. Exendin-4 treatment increased mRNA and protein expression of Sirt1 and its downstream factor, AMPK, in vivo and also induced genes associated with FA oxidation and glucose metabolism. In addition, a significant increase in the hepatic expression of Lkb1 and Nampt mRNA was observed in exendin-4-treated groups. We also observed increased expression of phospho-Foxo1 and GLUT2, which are involved in hepatic glucose metabolism. In HepG2 and Huh7 cells, mRNA and protein expressions of GLP-1R were increased by exendin-4 treatment in a dose-dependent manner. Exendin-4 enhanced protein expression of Sirt1 and phospho-AMPKα in HepG2 cells treated with 0.4 mM palmitic acid. We also found that Sirt1 was an upstream regulator of AMPK in hepatocytes. A novel finding of this study was the observation that expression of GLP-1R is proportional to exendin-4 concentration and exendin-4 could attenuate fatty liver through activation of Sirt1.
The role of North Pacific bomb cyclones in the onset of January 2021 sudden stratospheric warming (SSW) is examined by conducting a set of numerical model experiments. The control simulation, ...initialized 10 days before the SSW onset, successfully reproduces the SSW. As this event is preceded by the bomb cyclones in the North Pacific, their impact is tested by initializing the model without them. This sensitivity experiment shows much weaker polar‐vortex deceleration than the control simulation, resulting in no distinct SSW onset. This difference is attributable to the dampened constructive linear interference between the climatological wave and the cyclone‐related wavenumber‐one anomaly in the sensitivity experiment. It weakens the vertical propagation of wavenumber‐one wave into the stratosphere, thereby reducing wave breaking in the polar stratosphere. This result suggests that bomb cyclones should be considered for better understanding SSW and improving its predictability.
Plain Language Summary
Sudden stratospheric warming (SSW) is a dramatic event characterized by abrupt warming in the polar stratosphere. During this event, the eastward winds encircling the polar stratosphere change to westward winds, due to the breaking of the upward‐propagating planetary‐scale waves. Since the SSW is often followed by unusual weather events (e.g., cold surges), an accurate prediction of SSW is important for a better weather prediction. Here, we examine the role of the rapidly developing North Pacific cyclones in initiating the 2021 SSW. A set of numerical model experiments show that without cyclones, the 2021 SSW is not initiated due to the reduced breaking of the upward‐propagating planetary‐scale waves. This result suggests that the rapidly developing North Pacific cyclones should be considered for better understanding SSW and improving its predictability.
Key Points
The 2021 SSW is successfully reproduced by a model initialized 10 days before the stratospheric warming (SSW)
The model initialized without the North Pacific bomb cyclone does not simulate the 2021 SSW
Removing the North Pacific bomb cyclone reduces the k = 1 wave propagation into the stratosphere, reducing wave breaking in the stratosphere
Wearable strain sensors are widely researched as core components in electronic skin. However, their limited capability of detecting only a single axial strain, and their low sensitivity, stability, ...opacity, and high production costs hinder their use in advanced applications. Herein, multiaxially highly sensitive, optically transparent, chemically stable, and solution‐processed strain sensors are demonstrated. Transparent indium tin oxide and zinc oxide nanocrystals serve as metallic and insulating components in a metal–insulator matrix and as active materials for strain gauges. Synergetic sensitivity‐ and stability‐reinforcing agents are developed using a transparent SU‐8 polymer to enhance the sensitivity and encapsulate the devices, elevating the gauge factor up to over 3000 by blocking the reconnection of cracks caused by the Poisson effect. Cross‐shaped patterns with an orthogonal crack strategy are developed to detect a complex multiaxial strain, efficiently distinguishing strains applied in various directions with high sensitivity and selectivity. Finally, all‐transparent wearable strain sensors with Ag nanowire electrodes are fabricated using an all‐solution process, which effectively measure not only the human motion or emotion, but also the multiaxial strains occurring during human motion in real time. The strategies can provide a pathway to realize cost‐effective and high‐performance wearable sensors for advanced applications such as bio‐integrated devices.
Multiaxially highly sensitive, optically transparent, and chemically stable strain sensors are fabricated through an all‐solution process by developing a sensitivity‐ and stability‐reinforcing agent of SU‐8 polymer and orthogonally cracked hetero‐nanocrystal solids. The sensors with a high gauge factor over 3000 successfully detect various human signals such as the pulse, the vocal movement, facial expressions, and the wrist movement.
CuO‐doped (1–x)(Na0.2K0.8)NbO3‐xBaZrO3 ceramics (0.0 ≤ x ≤ 0.06) were densified at 960°C. The ceramic with x = 0 exhibited a large sprout‐shaped strain vs electric‐field (S‐E) curve and a double ...polarization vs electric‐field (P‐E) hysteresis curve, owing to the defect polarization (PD) developed between Cu2+ ions at Nb5+ sites and oxygen vacancies. The sizes of the S‐E and P‐E loops decreased with increasing x, owing to the decrease in the number of PDs. The ceramic with x = 0.04 displayed small S‐E and P‐E curves, indicating its small dielectric loss. It exhibited large strain (0.19% at 8.0 kV/mm) at room temperature, which was maintained at 200°C. A similar strain was observed after applying 106 cycles of an electric field (3.0 kV/mm). Hence, this specimen exhibited large strain with excellent thermal and fatigue properties. Moreover, the synthesized multilayer actuator using the ceramic with x = 0.04 showed excellent vibrational properties, making it promising for applications in multilayer piezoelectric actuators.
The vagus nerve supports diverse autonomic functions and behaviors important for health and survival. To understand how specific components of the vagus contribute to behaviors and long-term ...physiological effects, it is critical to modulate their activity with anatomical specificity in awake, freely behaving conditions using reliable methods. Here, we introduce an organ-specific scalable, multimodal, wireless optoelectronic device for precise and chronic optogenetic manipulations in vivo. When combined with an advanced, coil-antenna system and a multiplexing strategy for powering 8 individual homecages using a single RF transmitter, the proposed wireless telemetry enables low cost, high-throughput, and precise functional mapping of peripheral neural circuits, including long-term behavioral and physiological measurements. Deployment of these technologies reveals an unexpected role for stomach, non-stretch vagal sensory fibers in suppressing appetite and demonstrates the durability of the miniature wireless device inside harsh gastric conditions.
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