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South-east Asia's diverse coastal wetlands, which span natural mudflats and mangroves to man-made salt pans, offer critical habitat for many migratory waterbird species in the East Asian–Australasian Flyway. Species dependent on these wetlands include nearly the entire population of the Critically Endangered spoon-billed sandpiper Calidris pygmaea and the Endangered spotted greenshank Tringa guttifer, and significant populations of several other globally threatened and declining species. Presently, more than 50 coastal Important Bird and Biodiversity Areas (IBAs) in the region (7.4% of all South-east Asian IBAs) support at least one threatened migratory species. However, recent studies continue to reveal major knowledge gaps on the distribution of migratory waterbirds and important wetland sites along South-east Asia's vast coastline, including undiscovered and potential IBAs. Alongside this, there are critical gaps in the representation of coastal wetlands across the protected area networks of many countries in this region (e.g. Viet Nam, Indonesia, Malaysia), hindering effective conservation. Although a better understanding of the value of coastal wetlands to people and their importance to migratory species is necessary, governments and other stakeholders need to do more to strengthen the conservation of these ecosystems by improving protected area coverage, habitat restoration, and coastal governance and management. This must be underpinned by the judicious use of evidence-based approaches, including satellite-tracking of migratory birds, ecological research and ground surveys.
We investigate the dynamics of a self-rewetting drop placed on a substrate with a constant temperature gradient via three-dimensional numerical simulations using a conservative level-set approach to track the interface of the drop. The surface tension of a so-called self-rewetting fluid exhibits a parabolic dependence on temperature with a well-defined minimum. Two distinct drop behaviours, namely deformation and elongation, are observed when it is placed at the location of the minimum surface tension. The drop spreads slightly and reaches a pseudo-steady state in the deformation regime, while it continuously spreads until breakup in the elongation regime. Theoretical models based on the forces exerted on the drop have been developed to predict the critical condition at which the drop undergoes the transition between the two regimes, and the predictions are in good agreement with the numerical results. We also investigate the effect of the initial position of the drop with respect to the location of the minimum surface tension on the spreading and migration dynamics. It is found that, at early times, the migration of the drop obeys an exponential function with time, but it diverges at the later stage due to an increase in the drop deformation.
This paper presents a novel dual-band (DB) dual-polarized (DP) shared aperture antenna with high isolation by using a combination of microstrip dipoles and dielectric resonator antennas (DRAs) for S and C bands, respectively. In the S band, two sets of proximity coupled stacked microstrip dipoles which crossed at the center are employed to achieve dual-linear polarization (DLP) and obtain desired bandwidth (BW), isolation, and pure polarization. The rectangle DRA with hybrid feed is selected as the C band element for its advantages of small base area and high isolation, and a 2 × 2 array is presented with the “pair-wise” anti-phase feed technique to achieve a low cross-polarized level. Moreover, benefited from the back feed scheme, the proposed antenna has a symmetrical structure and has the potential of expanding into a larger aperture. The proposed antenna has been manufactured and measured, and the results agree well with simulations, which prove the validity of the proposed design.
Terrorist attacks can occur anywhere. As the threat of terrorism develops, the China-Eurasia Expo held in Ürümqi, China is attracting fewer potential visitors. A nationwide survey of 2034 residents from 31 provinces and municipalities in China was conducted to examine the relation between the distance to respondents’ city of residence from Ürümqi and their levels of concern for safety and security concerning the Expo. The two were found to be positively related: the closer the respondents lived to Ürümqi, the less concerned they were with the safety and security of the Expo. This is consistent with the “psychological typhoon eye” effect, which states that people living closer to the center of an unfortunate event (whether natural or man-made hazards) are less concerned with the event’s negative consequences. This effect appears to hold for terrorism. There are implications of this finding for international counter-terrorism practice, tourism, and research.
A multilevel nonvolatile memory based on an amorphous indium–gallium–zinc oxide thin-film transistor is successfully demonstrated by using an atomic layer–deposited ZnO film as a charge trapping layer. The memory device shows a much higher erasing efficiency at a negative bias, i.e., after erasing at −13 V for 1 μs, the threshold voltage shift is as large as −7.4 V. In the case of 13 V/1 μs programming (P) and −12 V/1 μs erasing (E), the device demonstrates an ON/OFF readout drain current (IDS) ratio of ∼103 after 105 s, and a large and stable ON/OFF IDS ratio of ∼106 till 104 of P/E cycles. Furthermore, multilevel memory characteristics are also demonstrated on the device, showing an IDS ratio of >102 for 4 different states. Additionally, the device also successfully demonstrates typical synaptic behaviors, such as excitatory and inhibitory postsynaptic current with different memory times at different memory states.
The present study was conducted to evaluate the effects of glucose, soya oil or glutamine on jejunal morphology, protein metabolism and protein expression of the mammalian target of rapamycin complex 1 (mTORC1) signalling pathway in jejunal villus or crypt compartment of piglets. Forty-two 21 d-weaned piglets were randomly allotted to one of the three isoenergetic diets formulated with glucose, soya oil or glutamine for 28 d. On day 14 or 28, the proteins in crypt enterocytes were analysed with isobaric tags for relative and absolute quantification and proteins involved in mTORC1 signalling pathway in villus or crypt compartment cells were determined by Western blotting. Our results showed no significant differences (P > 0·05) in jejunal morphology among the three treatments on day 14 or 28. The differentially expressed proteins mainly took part in a few network pathways, including antimicrobial or inflammatory response, cell death and survival, digestive system development and function and carbohydrate metabolism. On day 14 or 28, there were higher protein expression of eukaryotic initiation factor-4E binding protein-1 in jejunal crypt compartment of piglets supplemented with glucose or glutamine compared with soya oil. On day 28, higher protein expression of phosphor-mTOR in crypt compartment was observed in piglets supplemented with glucose compared with the soya oil. In conclusion, the isoenergetic glucose, soya oil or glutamine did not affect the jejunal morphology of piglets; however, they had different effects on the protein metabolism in crypt compartment. Compared with soya oil, glucose or glutamine may be better energy supplies for enterocytes in jejunal crypt compartment.
Metal oxides are promising candidates as the anodes of next-generation lithium ion batteries. However, the low electronic conductivities hinder their practical applications. Herein, through a facile calcination process using ammonium bicarbonate (NH4HCO3) as the N source, the nitrogen heteroelement was introduced into the ZnO/CoO micro-/nanospheres, which greatly improves the conductivity of the composites. As the lithium-ion battery anode, the N-doped ZnO/CoO micro-/nanosphere demonstrates much enhanced electrochemical performance. It displays a high initial capacity of 911.8 mA h/g at a current density of 0.2 A/g and long-term cycling stability, with a reversible capacity of 977.8 mA h/g remained after 500 cycles at a current density of 1 A/g. Furthermore, the N-doped ZnO/CoO composite presents an outstanding rate performance, with 605 mA h/g remained even at 5 A/g. The excellent electrochemical properties make N-doped ZnO/CoO micro-/nanospheres a promising candidate as high-performance anodes for next-generation rechargeable LIBs.
A varactor-based fully reconfigurable microstrip bandpass-to-bandpass-with-embedded-stopband filter is presented in this paper. This filter offers wide center frequency and bandwidth tuning flexibility under both bandpass mode and bandpass-with-embedded-stopband mode. The entire tuning ability is based on multiple mode resonator theory and external quality factor tuning structure for bandpass mode and the introduction of transmission zeros (TZs) for bandpass-with-embedded-stopband mode. Under the bandpass mode, the center frequency tuning range is 0.96–1.45 GHz and the bandwidth can be tuned from 0.09 to 1.41 GHz with a fixed center frequency at 1.22 GHz. Under bandpass-with-embedded-stopband mode, the center frequency and bandwidth can be tuned from 0.94 to 1.61 GHz and 0.2–0.33 GHz, respectively. Good agreements are shown between simulated and measured results.
This paper proposes a new radar cross section (RCS) reduced microstrip antenna incorporating 475 square slots on the patch. The proposed antenna achieves wideband RCS reduction with radiation performance sustained. The modified and reference antenna are simulated and analyzed in radiating and scattering mode, respectively. Prototypes of two antennas are fabricated and measured. Compared with the reference antenna, the simulated result shows the modified antenna RCS reduced in the frequency range 1.1–2.6 GHz, which contains the in-band and out-of-band frequency band simultaneously. And the maximum RCS reduction is 7.6dB at the frequency of 1.19GHz. Besides, the modified antenna can achieve the antenna RCS reduction in the case of oblique incidence. The prototypes of two antennas are fabricated and measured, and the accuracy of the simulation is proved by the measured result. Due to its advantages of simplicity, wideband RCS reduced, broad-angle RCS reduced, the method in this paper is suitable for wideband antenna RCS reduction in space-limited environment.
This paper proposes a microstrip antenna with reduced in-band and out-of-band radar cross-section (RCS) by subtracting the area of weak scattered current on the ground plane. Fourteen square slots were subtracted from the ground plane, reducing in-band and out-of-band RCS while maintaining radiation performance. Modified and reference antenna surface current distributions were simulated and analyzed in radiating and scattering modes. Two antenna prototypes were fabricated and measured to verify the simulation. The proposed antenna RCS was reduced compared with the reference antenna in the frequency range 1–4.4 GHz, including in-band and out-of-band frequency bands. Maximum in-band and out-of-band RCS reduction was 16.3 dBsm at the working frequency, and 19.3 dBsm at 3.4 GHz, respectively
To understand better the microbial functional populations which are involved in methanogenesis and denitrification in paddy soils with rice straw (RS) and/or nitrogen fertiliser (potassium nitrate, N) application, the dynamics of methanogens and the denitrifying community were monitored simultaneously during the incubation period. The results show that the community structure of methanogens remained relatively stable among treatments based on 16S rDNA analysis, but fluctuated based on 16S rRNA. The Methanocellaceae and Methanosarcinaceae dominated all treatments at 16S rDNA and 16S rRNA level, respectively. RS+N increased the relative abundance of Methanosaetaceae at the 16S rRNA level, while there was an increasing trend in that Methanomicrobiaceae following RS addition at the 16S rDNA level. RS and/or N did not significantly change the diversity of methanogens targeting both 16S rDNA and 16S rRNA. RS and RS+N increased copy numbers of methanogens targeting both 16S rDNA and 16S rRNA analyses. The community structure and abundance of nirS and nosZ-containing denitrifiers, and the diversity of nirS-containing denitrifiers was significantly altered only by the N treatment. These results indicate that the community structure, diversity and abundance of methanogens respond differently to RS addition at the 16S rDNA and 16S rRNA levels.
In this study, a new microstrip patch antenna with wideband radar cross-section (RCS) reduction is presented. The RCS of the proposed antenna was reduced by subtracting the current-direction slots of the patch, with the radiation performance sustained not only for the current-direction subtraction, but also for the no modification in the ground plane. Modified and reference antenna were fabricated and measured. The simulation and measurement results showed that the modified antenna reduced the in-band and out-band RCS simultaneously with no detriment to the radiation performance. In the frequency band from 3.9 to 8.1 GHz, the RCS of the modified antenna was reduced in the whole band compared with the RCS of the reference antenna. The maximum RCS reduction was 7 dB at a frequency of 6.7 GHz.
In this paper, a metasurface-based aperture-coupled circularly polarized (CP) antenna with wideband and high radiation gain is proposed and analyzed. The proposed antenna is comprised of coplanar waveguide coupling with 4 × 4 corner truncated square patches, which show compact size and low profile. The mechanism of the CP antenna is analyzed theoretically based on the mode analysis and equivalent circuit analysis. The parameters of feeding structure and truncated corner are studied and optimized to achieve wide impedance bandwidth (BW) and axial ratio (AR) BW. Finally, an overall size of 38.8 mm × 38.8 mm × 3.5 mm (0.71λ0 × 0.71λ0 × 0.064λ0 at 5.5 GHz) CP antenna is proposed and fabricated. The simulated results demonstrate that over 41.7% impedance BW (S11 < −10 dB) of 4.55–6.95 GHz and 3 dB AR BW of 5.05–6.15 GHz (fractional BW is about 19.6%) are achieved. In addition, the antenna yielded a broadside CP radiation with a high gain average about 7.5 dBic. Experimental results are in good agreement with the simulated ones.
A wideband and high-efficiency polarization conversion metasurface (PCM) is proposed and applied to reduce radar cross section (RCS). The proposed PCM unit is composed of two oblique asymmetry triangle split rings, which generate multiple plasmon resonances. Simulated and measured results demonstrate that it achieves polarization conversion over 90% from 9.24 to 17.64 GHz. Besides square checkerboard, the proposed PCM units and mirror units are arranged in triangle checkerboard. The mechanisms of both checkerboard PCMs are analyzed based on standard array theory, including the relationship between RCS reduction value and polarization conversion ratio value. The derived formulas provide a guideline to design checkerboard structure based on PCM. Simulated results demonstrate that both checkerboard PCMs achieve over 62% relative bandwidth of 10 dB RCS reduction under normal incidence with respect to the equal-sized metallic plate, which also means that the triangle one could be an alternative solution to reduce RCS. To verify the analyzed and simulated results, the fabricated sample and measured results of both checkerboard PCMs are presented. Good agreements are achieved between measurements, simulations and numerical analysis.
Astrophysical collisionless shocks are amazing phenomena in space and astrophysical plasmas, where supersonic flows generate electromagnetic fields through instabilities and particles can be accelerated to high energy cosmic rays. Until now, understanding these micro-processes is still a challenge despite rich astrophysical observation data have been obtained. Laboratory astrophysics, a new route to study the astrophysics, allows us to investigate them at similar extreme physical conditions in laboratory. Here we will review the recent progress of the collisionless shock experiments performed at SG-II laser facility in China. The evolution of the electrostatic shocks and Weibel-type/filamentation instabilities are observed. Inspired by the configurations of the counter-streaming plasma flows, we also carry out a novel plasma collider to generate energetic neutrons relevant to the astrophysical nuclear reactions.
In this paper, a high gain broadband low profile microstrip antenna with the dual-layered substrate and four parasitic metal elements is presented. The proposed microstrip antenna is mainly composed of four parts: four circular parasitic metal patches with dual arced breaches, a rectangular metal patch sandwiched between substrates, a square ground plane, and two-square substrates. The circular parasitic elements are the main radiation structure and determine the characteristics of the proposed antenna are closely related to the parasitic elements. The proposed antenna has been fabricated for experimental measurement. The reflection coefficient, radiation pattern, radiation efficiency, and gain have been studied in detail. The simulated and measured impedance bandwidth is 27.0% (3.30–4.33 GHz), the maximum realized peak gain reaches up to 6.52 dBi at the frequency of 3.65 GHz. The radiation pattern has a single peak which is perpendicular to the surface of the substrate. The proposed antenna is suitable to be applied in the 5G mobile or WiMAX wireless communication. Dual antenna with a pair of parasitic elements has been investigated numerically to explain the principle of the proposed antenna.
A non-precious metal catalytic system of Fe-doped Ta2O5 is developed by pulsed laser deposition toward efficient oxygen evolution reaction (OER). The optimal Fe concentration is determined to be 5 at.% for optimized OER activity via a series of electrochemical characterizations. The 5 at.% Fe-doped Ta2O5 nanolayer possesses a low onset overpotential of 0.22 V, an overpotential of 0.38 V at 10 mA/cm2 and a Tafel slope of 54 mV/dec. Comprehensive first-principles calculations attribute the enhanced OER activity to the substitutional FeTa dopants, which generate a new active OER site on surface and simultaneously accelerate electron transfer over oxygens.
In this paper, a coplanar waveguide (CPW)-fed dual-band uniplanar tri-polarization reconfigurable antenna based on the PIN diode switch is proposed. The proposed antenna can be reconfigured between the linear polarization (LP) and the circular polarization (CP) mode, including both the right-handed circular polarization and left-handed circular polarization simultaneously within the dual operating bands. The central frequencies of the bands are 2.63 and 4.42 GHz, respectively, and the overlapped operating bandwidth is 17.8 and 3.40%. The proposed reconfigurable antenna is a closed-slot antenna fed by the CPW transmission line and the reconfigurable mechanism is to regulate the T-shaped driven stub through switching the PIN diodes on and off. The scattering parameters, axial ratio, radiation pattern, gain, and the radiation efficiency of the proposed antenna are all investigated in the following. The optimized antenna has been fabricated to experimental test, the simulated and the measured results agree well with each other. The lower frequency band of the proposed antenna covers the 2.40 GHz WLAN specification and the upper band can be used for the 5 G communication (4.40–4.50 GHz); therefore it is suitable to be applied in the mobile wireless communication.
In this study, a dual-layered polarization and frequency reconfigurable microstrip antenna is proposed based on sequential mechanical axial rotation of the circular metal radiator. The antenna can be reconfigured among three different polarized modes, including the linear polarization (LP), left-handed circular polarization and right-handed circular polarization in the band from 4.68 to 4.80 GHz (2.53%). The resonance frequency of the proposed antenna with the same LP mode could also be tuned in the range from 4.70 to 5.03 GHz by mechanical rotation of the breach-truncated circular metal radiator as well as the circular substrate. Furthermore, the polarization characteristic and frequency can be reconfigured, respectively, as the circular radiator is taken an axial rotation with an angle of 360°. The presented antenna in the four different states has been numerically simulated and fabricated for the experimental measurement, the investigated characteristics includes the port reflection coefficient, axial ratio, radiation pattern, gain, and the radiation efficiency. The simulated and test results agreed well with each other. This antenna enriches the novel mechanical reconfigurable method except for the popular electrical approach.
This article outlines the evolution of a rescue team in responding to adenovirus prevention with a deployable field hospital. The local governments mobilized a shelter hospital and a rescue team consisting of 59 members to assist with rescue and response efforts after an epidemic outbreak of adenovirus. We describe and evaluate the challenges of preparing for deployment, field hospital maintenance, treatment mode, and primary treatment methods. The field hospital established at the rescue scene consisted of a medical command vehicle, a computed tomography shelter, an X-ray shelter, a special laboratory shelter, an oxygen and electricity supply vehicle, and epidemic prevention and protection equipment. The rescue team comprised paramedics, physicians, X-ray technicians, respiratory therapists, and logistical personnel. In 22 days, more than 3000 patients with suspected adenovirus infection underwent initial examinations. All patients were properly treated, and no deaths occurred. After emergency measures were implemented, the spread of adenovirus was eventually controlled. An emergency involving infectious diseases in less-developed regions demands the rapid development of a field facility with specialized medical personnel when local hospital facilities are either unavailable or unusable. An appropriate and detailed prearranged action plan is important for infectious diseases prevention. (Disaster Med Public Health Preparedness. 2018;12:109–114)