The devastating Hunga Tonga-Hunga Ha’apai underwater volcano erupted at ~04:15 UT on 15 January 2022. We captured the waves that erupted from the volcano propagating in the ionosphere by monitoring ...total electron content (TEC) perturbations utilizing ground-based global navigation satellite system (GNSS) receivers that receive electromagnetic signals transmitted from the geostationary satellites operated by the BeiDou Navigation Satellite System (BDS). Meanwhile, ground barometers detected unusual enhancements of air pressure traveling in the troposphere. A novel phenomenon shows that the waves can individually propagate with a speed of ~335 m/s in the ionosphere, which is faster than its’ ~305 m/s in the troposphere. We further examined multiple geophysical data at the particular site of the novel instrumental array. Analytical results show that the pressure enhancements traveling in the troposphere not only downward trigger ground vibrations mainly in the horizontal components without obvious time difference, but also upward, leading the secondary TEC perturbations with a ~12-min delay.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Intense eruptions of the Tonga volcano activated prominent traveling atmospheric disturbances (TADs) at 04:05UT on 15 January 2022. Himawari‐8 satellite images depict that TADs of the tropospheric ...Lamb wavefront propagate with a speed of 315 m/s and arrive in Taiwan at 11:30UT. Networks of 98 barometers, 28 tide gauges, an ionosonde, and 10 magnetometers are used to study the responses of magnetic fields to TADs in Taiwan. The horizontal components in magnetic field changes of the Taiwan magnetometers all point toward and away from the Tonga volcano at 11:00–12:00UT upon the tropospheric Lamb wavefront arrival and at 22:00–23:00UT when the thermospheric Lamb wavefront with speeds of 487 m/s coming, respectively. Analyses of the raytracing and beamforming techniques on the horizontal components in magnetic field changes of 69 INTERMAGNET magnetometers show that both tropospheric and thermospheric Lamb waves efficiently activate traveling ionospheric disturbances and modify ionospheric currents of the globe.
Plain Language Summary
At 04:05UT on 15 January 2022, intense Tonga volcanic eruptions induce prominent atmospheric disturbances and tsunami waves. Himawari‐8 meteorological satellite images depict the induced upper‐level tropospheric disturbances with horizontal speeds of about 315 m/s at 8.2 km altitude in the Lamb wave mode travel worldwide. Upon the traveling atmospheric disturbances (TADs) of the tropospheric Lamb wavefront arriving in Taiwan at 11:30UT, 98 ground‐based barometers register increases and reach peaks at about 11:50UT in the atmospheric pressure; 28 tide gauges record enhancements and maximums of sea level fluctuations at about 14:30–17:30UT; and a local ionosonde observes that the ionosphere reaches the highest altitude at 14:30UT. The changes of the horizontal component of the Earth's magnetic fields measured by 10 Taiwan magnetometers almost all point exactly toward the Tonga volcano upon the tropospheric Lamb wavefront arrival at 11:00–12:00UT, and away from the volcano at 22:00–23:00UT, which suggests a 487 m/s TAD (or thermospheric Lamb wavefront) at about 130 km altitude also being activated. The horizontal components in magnetic field changes of 69 INTERMAGNET magnetometers show that both tropospheric and thermospheric Lamb waves triggered by Tonga volcanic eruptions are very powerful, and can induce intense dynamo currents and electric fields on the globe.
Key Points
Tropospheric and thermospheric Lamb waves of the Tonga volcanic eruption activate dynamo currents and electric fields
Traveling atmospheric disturbances of the Tonga volcanic eruption significantly uplift the ionosphere
Tropospheric Lamb waves of the Tonga volcanic eruption modulate ground‐based air pressures and sea levels
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
This research aims to study two historical tsunamis that occurred in Taiwan during the 18th century and to reconstruct the incidents. The 1781 Jiateng Harbor flooding, recorded by the Chinese ...historical document entitled “Taiwan Interview Catalogue” took place on the southwest coast of Taiwan. In contrast, the 1782 tsunami was documented in foreign languages, with uncertainties about the actual time. These two events seem to be close enough in time and location that, to some researchers, they are considered as the same event. Reasoning these historical events requires carefully examining the literature records and performing the scenarios that match the descriptions. The impact intensity analysis (IIA) is employed to locate possible regions of tsunami sources in order to reproduce the events. Numerical simulations based on the Cornell Multi-grid Coupled Tsunami Model (COMCOT) analyze the influence of different types of tsunamis generated by both submarine mass failures and seismic activities. Numerical results indicate that the source of the 1781 Jiateng Harbor flooding is located very possibly on the south-southwestern side of Taiwan. However, simulation results and historical records put the existence of the 1782 tsunami in doubt, and the possibility of storm surges could not be ruled out.
Abstract
The rotation of a C = C bond in an alkene can be efficiently accelerated by creating the high-strain ground state and stabilizing the transition state of the process. Herein, the synthesis, ...structures, and properties of several highly twisted alkenes are comprehensively explored. A facile and practical synthetic approach to target molecules is developed. The twist angles and lengths of the central C = C bonds in these molecules are 36–58° and 1.40–1.43 Å, respectively, and confirmed by X-ray crystallography and DFT calculations. A quasi-planar molecular half with the π-extended substituents delivers a shallow rotational barrier (down to 2.35 kcal/mol), indicating that the rotation of the C = C bond is as facile as that of the aryl-aryl bond in 2-flourobiphenyl. Other versatile and unique properties of the studied compounds include a broad photoabsorption range (from 250 up to 1100 nm), a reduced HOMO-LUMO gap (1.26–1.68 eV), and a small singlet-triplet energy gap (3.65–5.68 kcal/mol).
High-spin, late transition metal imido complexes have attracted significant interest due to their group transfer reactivity and catalytic C-H activation of organic substrates. Reaction of a new ...two-coordinate iron complex, Fe{N(
t
Bu)Dipp}
2
(
1
, Dipp = 2,6-diisopropylphenyl), with mesitylazide (MesN
3
) afforded a three-coordinate Fe-imidyl complex, Fe{N(
t
Bu)Dipp}
2
(&z.dbd;NMes) (
2
). X-ray crystallographic characterization of single crystals of
2
showed a long Fe-N distance of 1.761(1) Å. Combined magnetic and spectroscopic (Mössbauer and X-ray absorption near edge structure spectroscopy, XANES) characterization of
2
suggests that it has an
S
= 2 ground state comprising an
S
= 5/2 Fe(
iii
) center antiferromagnetically coupled to an
S
= 1/2 imidyl ligand. Reaction of
1
and 1-azidoadamantane (AdN
3
) generated a putative, transient Fe{N(
t
Bu)Dipp}
2
(&z.dbd;NAd) (
3′
) complex that yielded an intramolecular C-H amination product, Fe{N(
t
Bu)Dipp}{κ
2
-
N
,
N
′-&cmb.b.line;N(CMe
2
CH
2&cmb.b.line;
NHAd)Dipp} (
3
). Quantum mechanical calculations further confirmed the spectroscopic assignment of
2
and
3′
, as well as the differences in their stability and reactivity. Importantly, imidyl radical delocalization onto the mesityl ring significantly increased the stability of
2
and reduced its reactivity toward potential hydrogen atom transfer (HAT) reagents. In contrast, quantum mechanical calculations of
3′
revealed that the radical was solely localized on the imidyl N, leading to a high reactivity toward the proximal C-H bond of the N(
t
Bu)Dipp
−
ligand.
A stable three-coordinate Fe imido radical (
i.e.
imidyl) complex can be stabilized
via
N radical delocalization onto the aryl imido substituent.
Full text
Available for:
IJS, KILJ, NUK, UL, UM, UPUK
•A DNN-based system for identifying ECG signals is presented.•ECG segments are directly used as input to the system.•A heuristic is proposed to select the most useful ECG leads.•Features of different ...scales are extracted for effective discrimination.
The standard 12-lead electrocardiogram (ECG) records the heart’s electrical activity from electrodes on the skin, and is widely used in screening and diagnosis of the cardiac conditions due to its low price and non-invasive characteristics. Manual examination of ECGs requires professional medical skills, and is strenuous and time consuming. Recently, deep learning methodologies have been successfully applied in the analysis of medical images. In this paper, we present an automated system for the identification of normal and abnormal ECG signals. A multi-channel multi-scale deep neural network (DNN) model is proposed, which is an end-to-end structure to classify the ECG signals without any feature extraction. Convolutional layers are used to extract primary features, and long short-term memory (LSTM) and attention are incorporated to improve the performance of the DNN model. The system was developed with a 12-lead ECG dataset provided by the Kaohsiung Medical University Hospital (KMUH). Experimental results show that the proposed system can yield high recognition rates in classifying normal and abnormal ECG signals.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Gold-catalyzed nitrone oxidations of 1,5-allenynes are postulated to involve the formation of gold-enolate containing all carbon 1,3-dipole-like species Int-4, further yielding 1-naphthols fused with ...a nitroxy ring. 1,5-Allenynes bearing internal alkynes (R = aryl and alkyl) afford 1-naphthols bearing 3,4-fused nitroxy rings, whereas their terminal alkyne analogous (R = H) deliver 1-naphthols with 2,3-fused nitroxy rings. Our DFT study confirms the intermediacy of α-oxo-gold carbenes that trap the tethered allenes to generate gold-containing 1,3-dipole-like species before 3 + 3-annulations with a second nitrone. Our preliminary results indicate that quinoline oxides also generate similar gold-enolate containing 1,3-dipole-like intermediates Int-4 for further 3 + 3-annulations.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
This study is based on
Flammulina velutipes
(enoki mushroom) cultivation farm and considers the existing equipment conditions. As a large number of autoclaves are commonly used for pretreatment and ...sterilization of bulk bags in mushroom cultivation farms, this situation has been integrated into the research design. Actually, most of the enoki mushroom fiber is insoluble dietary fiber (IDF), which is not in favor of its development. Conversion of insoluble dietary fiber (IDF) to soluble dietary fiber (SDF) is a regular method for better use of dietary fiber in the food industry. Here, autoclaving treatment was conducted for 10 min, and then combined with the enzymatic hydrolysis and adjusting the solid–liquid ratio to 20% (w v
–1
), the extraction rate of enoki mushroom SDF increased from 7.55 to 11.48 mass%, which is the best conversion ratio; it was also found that its glucose content increased by 1.82 mg g
–1
. Furthermore, through the analysis of liquid chromatography, microstructure, and specific functional groups, it was confirmed that autoclaving pretreatment combined with the use of enzymatic hydrolysis can convert the almost cellulose structure of enoki mushroom into natural additives of SDF and IDF; they can be extensively used in food processing. In addition, a scanning rate of 4 °C min
–1
was selected as the reference benchmark for comparing the thermal stability and characteristics. From the perspective of the onset temperature of the crystallization reaction, IDF is approximately 220 °C, while SDF begins to exhibit a crystallization exothermic reaction at around 230 °C. In terms of thermal decomposition reaction, SDF has a higher onset temperature of exothermic decomposition above 280 °C, while IDF is only around 270 °C. The enthalpy of exothermic decomposition is also different between the two, with SDF having a value approximately twice that of IDF (27 kJ kg
–1
) Overall, using autoclaving combined with enzymatic extraction, the issues with products with unsalable period and poor selling appearance can be solved, and the high-quality dietary fiber also can be used for food additives, realizing agricultural waste reduction and added value to circular economy for SDG12 by responsible consumption and production.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The 28 September 2018 magnitude Mw7.8 Palu, Indonesia earthquake (0.178° S, 119.840° E, depth 13 km) occurred at 10:02 UTC. The major earthquake triggered catastrophic liquefaction, landslides, and a ...near-field tsunami. The ionospheric total electron content (TEC) derived from records of 5 ground-based global navigation satellite system (GNSS) receivers is employed to detect tsunami traveling ionospheric disturbances (TTIDs). In total, 15 TTIDs have been detected. The ray-tracing and beamforming techniques are then used to find the TTID source location. The bootstrap method is applied in order to further explore the possible location of the tsunami source based on results of the two techniques, which show the beamforming technique has a slightly better performance on finding possible locations of the tsunami source. Meanwhile, the circle method is employed to examine tsunami signatures of the sea-surface height and video records, and find possible tsunami origin locations. The coincidence of the TTID source location and the tsunami location shows that the ionospheric TEC recorded by local ground-based GNSS receivers can be used to confirm the tsunami occurrence, find the tsunami location, and support the tsunami early warning.
A series of di-nuclear metal acetate complexes 1–6 incorporated by nitrogen heterocycle-containing salen-type ligands have been synthesized, structurally characterized and performed as catalysts to ...prepare biodegradable polycarbonates and polyesters. Their catalytic performances for copolymerization of carbon dioxide-epoxides or cyclic anhydride-epoxides were systematically examined. Bimetallic nickel(II) complexes 1, 2 and 5 were active catalysts for the alternating copolymerization of cyclohexene oxide (CHO) with CO2; di-nickel complex 1 was shown to be the most effective and selective, leading to obtaining poly(cyclohexene carbonate)s with the best efficiency among them. Moreover, complex 1 was also found to be versatile for the ring-opening copolymerization of CO2 with different cyclic epoxides to give the corresponding polycarbonates. Additionally, di-cobalt(II) analogs 3, 4 and 6 were efficient catalysts for the alternating copolymerization of CHO and phthalic anhydride (PA) under mild conditions. Based on the results of catalytic studies, complex 3 was demonstrated to be the most active one CHO-PA copolymerization, producing the polymeric products with a “controlled” manner involving controllable molecular weights and narrow polydispersity. Interestingly, Co complex 3 was also able to catalyze the copolymerization of PA with 4-vinyl-1,2-cyclohexene oxide to obtain the associated polyester with the vinyl functionality on the side chains, which was further functionalized with tertiary amine moieties via thiol-ene click functionalization and converted to nanofibers through electrospinning. Due to the incorporation of polar groups, the resulting tertiary amine-modified polyester nanofibers that exhibit an improved hydrophilic property relative to their un-modified counterpart have been considered to have high potential to be utilized as a new functional fiber material.
New bimetallic bis(benzotriazole iminophenolate) or bis(benzothiazole iminophenolate) nickel and cobalt complexes were developed for versatile ROCOP of internal epoxides with CO2 or phthalic anhydride (PA). Particularly, di-Co complex 3 was able to copolymerize 4-vinyl-1,2-cyclohexene oxide with PA to afford the vinyl-functionalized polyester, which could be further utilized for the preparation of hydrophilic nanofiber via functional modification and electrospinning. Display omitted
•Well-defined dinuclear Ni and Co catalysts bearing BiIBT(h)P ligands were developed.•Versatile catalysis for ROCOP of cyclic epoxides with CO2 or PA was studied.•Di-Ni 1 could efficiently catalyze CO2-copolymerization of CHO, VCHO or CPO.•Alternating poly(PA-alt-VCHO)s were prepared on PA/VCHO copolymerization by di-Co 3.•The functionalized poly(PA-alt-VCHO) could be converted to NFMs via electrospinning.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
