Observations and theoretical modeling of the ionospheric disturbance waves generated by rocket launches are investigated. During the rocket passage, time rate change of total electron content (rTEC) ...enhancement with the V‐shape shock wave signature is commonly observed, followed by acoustic wave disturbances and region of negative rTEC centered along the trajectory. Ten to fifteen min after the rocket passage, delayed disturbance waves appeared and propagated along direction normal to the V‐shape wavefronts. These observation features appeared most prominently in the 2016 North Korea rocket launch showing a very distinct V‐shape rTEC enhancement over enormous areas along the southeast flight trajectory despite that it was also appeared in the 2009 North Korea rocket launch with the eastward flight trajectory. Numerical simulations using the physical‐based nonlinear and nonhydrostatic coupled model of neutral atmosphere and ionosphere reproduce promised results in qualitative agreement with the characteristics of ionospheric disturbance waves observed in the 2009 event by considering the released energy of the rocket exhaust as the disturbance source. Simulations reproduce the shock wave signature of electron density enhancement, acoustic wave disturbances, the electron density depletion due to the rocket‐induced pressure bulge, and the delayed disturbance waves. The pressure bulge results in outward neutral wind flows carrying neutrals and plasma away from it and leading to electron density depletions. Simulations further show, for the first time, that the delayed disturbance waves are produced by the surface reflection of the earlier arrival acoustic wave disturbances.
Key Points
Ionospheric TEC perturbations show features of the V‐shape shock acoustic wave, region of depletion, and the delayed disturbance waves
Simulations considering energy released by rocket exhaust reproduce the observations of ionospheric disturbance waves qualitatively
The delayed disturbance waves generated due to ground reflection of earlier acoustic waves are simulated for the first time
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
This paper discusses the relationship between the vertical ground motion and ionospheric disturbances before the Kumamoto earthquake on 16 April 2016, in Kyushu, Japan, using the vertical ground ...motion measured by slant gauges widely distributed in Kyushu, and the NmF2 observed by ionosondes in Japan and another region. We provide evidence that vertical ground motion excites internal gravity waves (IGWs) that disturb changes in the ionospheric plasma density. From the spectral analysis results of the vertical ground motion data, the summation of various period (frequency) components analyzed from the original data of the slant gauge shows a possible correlation with the change of NmF2 before the earthquake. On the other hand, the influence of the geomagnetic disturbance on vertical ground motion seems to exist. However, we cannot confirm that vertical ground motion is influenced by the geomagnetic disturbance (Kp index) and that the earthquake is triggered by the geomagnetic disturbance. There are two conditions for the vertical ground motion to disturb variations in the ionospheric plasma density: (1) The effective vertical ground motion period should be shorter than 5 h. In addition, (2) vertical ground motion should continue to exist so that wave energy can be continuously injected into the atmosphere. A possible mechanism with which to modify the ionosphere is discussed. The results of this study can provide a basis for the future ionospheric precursors of earthquakes by using the vertical ground motion.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The voltage, current, temperature, humidity, pressure, flow, and hydrogen in the high-pressure proton exchange membrane water electrolyzer (PEMWE) can influence its performance and life. For example, ...if the temperature is too low to reach the working temperature of the membrane electrode assembly (MEA), the performance of the high-pressure PEMWE cannot be enhanced. However, if the temperature is too high, the MEA may be damaged. In this study, the micro-electro-mechanical systems (MEMS) technology was used to innovate and develop a high-pressure-resistant flexible seven-in-one (voltage, current, temperature, humidity, pressure, flow, and hydrogen) microsensor. It was embedded in the upstream, midstream, and downstream of the anode and cathode of the high-pressure PEMWE and the MEA for the real-time microscopic monitoring of internal data. The aging or damage of the high-pressure PEMWE was observed through the changes in the voltage, current, humidity, and flow data. The over-etching phenomenon was likely to occur when this research team used wet etching to make microsensors. The back-end circuit integration was unlikely to be normalized. Therefore, this study used lift-off process to further stabilize the quality of the microsensor. In addition, the PEMWE is more prone to aging and damage under high pressure, so its material selection is very important.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The proton exchange membrane water electrolyzer (PEMWE) requires a high operating voltage for hydrogen production to accelerate the decomposition of hydrogen molecules so that the PEMWE ages or ...fails. According to the prior findings of this R&D team, temperature and voltage can influence the performance or aging of PEMWE. As the PEMWE ages inside, the nonuniform flow distribution results in large temperature differences, current density drops, and runner plate corrosion. The mechanical stress and thermal stress resulting from pressure distribution nonuniformity will induce the local aging or failure of PEMWE. The authors of this study used gold etchant for etching, and acetone was used for the lift-off part. The wet etching method has the risk of over-etching, and the cost of the etching solution is also higher than that of acetone. Therefore, the authors of this experiment adopted a lift-off process. Using the flexible seven-in-one (voltage, current, temperature, humidity, flow, pressure, oxygen) microsensor developed by our team, after optimized design, fabrication, and reliability testing, it was embedded in PEMWE for 200 h. The results of our accelerated aging test prove that these physical factors affect the aging of PEMWE.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The ionospheric total electron content (TEC) derived from dense ground‐based Global Navigation Satellite System receivers over the continental United States and those from global ionosphere maps are ...utilized to find the ionosphere response to the August 21, 2017 total solar eclipse. Maximum obscurations and their associated TEC major depressions appear simultaneously at midlatitudes, while major depressions elongate toward the magnetic equator with some delays in the equatorial ionization anomaly (EIA) region. The former is due to the photochemical loss process, while the latter is caused by the plasma transport of E×B drifts and lunar gravitation forces. TECs of predawn reductions, morning enhancements, afternoon reductions, and nighttime enhancements reveal that the semidiurnal lunar tide are essential. Since a solar eclipse always occurs on a new moon day, the lunar tide results in the early EIA appearance and major depressions being underestimated/diminished before and overestimated/enhanced after about 14:00 local time.
Plain Language Summary
Observations during an eclipse offer a special opportunity for studying the Earth's ionospheric response to changes in solar ionizing radiation. Although ionospheric solar eclipse signatures in many events have been studied, we report the lunar tide effect on the signatures for the first time. A total solar eclipse swept across the continental United States (CONUS) from the west to east coast on August 21, 2017. The total electron content (TEC) along seven longitudes of the US continent derived from more than 2,200 ground‐based Global Navigation Satellite System receivers in the CONUS and extracted from global ionosphere maps (GIMs) is employed to study ionospheric solar eclipse signatures. The most prominent solar eclipse signature is major depressions (MDs) in both the CONUS and GIM TECs, when the maximum obscuration occurs. TEC extrema of predawn reductions, morning enhancements, afternoon reductions, and nighttime enhancements reveal that the semidiurnal lunar tide of about 12.42‐h period is prominent. The lunar tide causes the early appearance of equatorial ionization anomalies, which further results in the MDs being weakened in the morning and enhanced in the afternoon on the solar eclipse day. The lunar tide has to be taken into consideration for studying ionospheric solar eclipse effects.
Key Points
The lunar tide results in the early appearance of the equatorial ionization anomaly on solar eclipse days
Total electron contents tend to enhance before and decrease after 14:00 local time (LT) on a solar eclipse day
The lunar tide causes major depressions being weakened before and enhanced after 14:00 LT
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Targeting the MEK/ERK pathway has been viewed as a promising strategy for cancer therapy. However, MEK inhibition leads to the compensatory PI3K/AKT activation and thus contributes to the ...desensitization of cancer cells to MEK inhibitors. The underlying molecular mechanism of this event is not yet understood. In this study, our data showed that the induction of Akt activity by MEK inhibitors was specifically observed in HER2‐positive breast cancer cells. Silence of HER2, or overexpression of HER2 kinase‐dead mutant, prevents the induction of Akt activation in response to MEK inhibition, indicating HER2 as a critical regulator for this event. Furthermore, HER2 Thr701 was demonstrated as a direct phosphorylation target of ERK1/2. Inhibition of this specific phosphorylation prolonged the dimerization of HER2 with EGFR in a clathrin‐dependent manner, leading to the enhanced activation of HER2 and EGFR tyrosine kinase and their downstream Akt pathway. These results suggest that suppression of ERK‐mediated HER2 Thr701 phosphorylation contributes to MEK inhibitor‐induced Akt activation.
MEK inhibitors suppress ERK‐mediated HER2 Thr701 phosphorylation to enhance clathrin‐dependent HER2/EGFR dimerization and subsequent Akt activation.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
SpaceX launched its Falcon Heavy demonstration mission at 20:45 UT on 6 February 2018 at NASA Kennedy Space Center in Florida. Short‐period northward propagating traveling ionospheric disturbances ...(TIDs) were observed following the shock waves in the ionospheric total electron content over East Florida‐Atlantic region. These TIDs have the periods of ~6–8 min, amplitude of ~0.05 total electron content unit, horizontal phase velocities of ~420–488 m/s, and horizontal wavelengths of ~164–240 km. They lasted for ~100 min and propagated a long distance of about 1,450 km, exhibiting a nearly coherent wave pattern and near‐constant phase velocity. The theoretical dispersion relation suggests that the short‐period TIDs were likely associated with the ducted gravity waves which became evanescent at altitudes around 170 km. Additional simulations were conducted in the Naval Research Laboratory SAMI3/ESF model using analytical expressions to approximate these gravity waves. Simulations reveal that modulations of the ionospheric electric fields through gravity wave wind dynamo perturbation can lead to weak ionospheric disturbances as observed.
Plain Language Summary
SpaceX launched its Falcon Heavy demonstration mission at 20:45 UT on 6 February 2018 at NASA Kennedy Space Center in Florida. The most powerful operational rocket consists of three Falcon‐9 nine‐engine cores in the first stage, however, produced relative weak traveling ionosphere disturbances in comparison with other Falcon‐9 launches. The weak traveling ionospheric disturbances had the short period but could travel a long distance of ~1,450 km (from off coast Florida to Lake Ontario). These characteristics suggest that the rocket induced atmospheric gravity waves that were guided along the lower thermosphere ~115–170 km altitude. The guided gravity waves may not affect the ionospheric plasma directly, but on the other hand, created electrodynamic perturbations in the ionosphere. Numerical simulations confirm that the electrodynamic perturbations could transmit to the upper part of ionosphere or even the opposite hemisphere.
Key Points
The powerful Falcon‐Heavy rocket induced surprisingly weak traveling ionospheric disturbances compared to previous Falcon‐9 rocket launches
The short‐period and long‐distance propagating TIDs likely originate from the ducted gravity waves in the lower thermosphere
Numerical simulations suggest that the ducted gravity waves induce the TIDs through electrodynamic coupling
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Abstract The capability to remotely control the release of biomolecules provides an unique opportunity to monitor and regulate neural signaling, which spans extraordinary spatial and temporal scales. ...While various strategies, including local perfusion, molecular “uncaging”, or photosensitive polymeric materials, have been applied to achieve controlled releasing of neuro-active substances, it is still challenging to adopt these technologies in many experimental contexts that require a straightforward but versatile loading-releasing mechanism. Here, we develop a synthetic strategy for remotely controllable releasing of neuro-modulating molecules. This platform is based on microscale composite hydrogels that incorporate polypyrrole (PPy) nanoparticles as photo-thermal transducers and is triggered by near-infrared-light (NIR) irradiation. Specifically, we first demonstrate the utility of our technology by recapitulating the “turning assay” and “collapse assay”, which involve localized treatment of chemotactic factors (e.g. Netrin or Semaphorin 3A) to subcellular neural elements and have been extensively used in studying axonal pathfinding. On a network scale, the photo-sensitive microgels are also validated for light-controlled releasing of neurotransmitters (e.g. glutamate). A single NIR-triggered release is sufficient to change the dynamics of a cultured hippocampal neuron network. Taking the advantage of NIR's capability to penetrate deep into live tissue, this technology is further shown to work similarly well in vivo , which is evidenced by synchronized spiking activity in response to NIR-triggered delivery of glutamate in rat auditory cortex, demonstrating remote control of brain activity without any genetic modifications. Notably, our nano-composite microgels are capable of delivering various molecules, ranging from small chemicals to large proteins, without involving any crosslinking chemistry. Such great versatility and ease-of-use will likely make our optically-controlled delivery technology a general and important tool in cell biology research.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Anticancer peptides (ACPs) are a kind of bioactive peptides which could be used as a novel type of anticancer drug that has several advantages over chemistry-based drug, including high specificity, ...strong tumor penetration capacity, and low toxicity to normal cells. As the number of experimentally verified bioactive peptides has increased significantly, various of in silico approaches are imperative for investigating the characteristics of ACPs. However, the lack of methods for investigating the differences in physicochemical properties of ACPs. In this study, we compared the N- and C-terminal amino acid composition for each peptide, there are three major subtypes of ACPs that are defined based on the distribution of positively charged residues. For the first time, we were motivated to develop a two-step machine learning model for identification of the subtypes of ACPs, which classify the input data into the corresponding group before applying the classifier. Further, to improve the predictive power, the hybrid feature sets were considered for prediction. Evaluation by five-fold cross-validation showed that the two-step model trained with sequence-based features and physicochemical properties was most effective in discriminating between ACPs and non-ACPs. The two-step model trained with the hybrid features performed well, with a sensitivity of 86.75%, a specificity of 85.75%, an accuracy of 86.08%, and a Matthews Correlation Coefficient value of 0.703. Furthermore, the model also consistently provides the effective performance in independent testing set, with sensitivity of 77.6%, specificity of 94.74%, accuracy of 88.99% and the MCC value reached 0.75. Finally, the two-step model has been implemented as a web-based tool, namely iDACP, which is now freely available at http://mer.hc.mmh.org.tw/iDACP/ .
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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