661 research outputs found
Compact Circularly Polarized Patch Antenna Using a Composite Right/Left-Handed Transmission Line Unit-Cell
A compact circularly polarized (CP) patch antenna using a composite right/left-handed (CRLH) transmission line (TL) unit-cell is proposed. The CRLH TL unit-cell includes a complementary split ring resonator (CSRR) for shunt inductance and a gap loaded with a circular-shaped slot for series capacitance. The CSRR can decrease the TM10 mode resonance frequency, thus reducing the electrical size of the proposed antenna. In addition, the asymmetry of the CSRR brings about the TM01 mode, which can be combined with the TM10 mode by changing the slot radius. The combination of these two orthogonal modes with 90° phase shift makes the proposed antenna provide a CP property. The experimental results show that the proposed antenna has a wider axial ratio bandwidth and a smaller electrical size than the reported CP antennas. Moreover, the proposed antenna is designed without impedance transformer, 90° phase shift, dual feed and ground via
Phase Compensation Enhancement of Photon Pair Entanglement Generated from Biexciton Decays in Quantum Dots
Exciton fine-structure splittings within quantum dots introduce phase
differences between the two biexciton decay paths that greatly reduce the
entanglement of photon pairs generated via biexciton recombination. We analyze
this problem in the frequency domain and propose a practicable method to
compensate the phase difference by inserting a spatial light modulator, which
substantially improves the entanglement of the photon pairs without any loss.Comment: 4 pages, 3 figure
Identification, isolation and in vitro antimicrobial susceptibility testing of Aeromonas veronii associated with an acute death of Channel Catfish (Ictalurus lunetas) in China
Aeromonas veronii is a common pathogen in both humans and animals. It exists in the environment we live. Many reports showed it could lead to human infection but few demonstrated its effect on aquatic animals, especially Channel Catfish (Ictalurus lunetaus). Here, A. veronii was isolated from an acute death case of Channel Catfish in Southwestern China. This Gram-negative bacillus was identified by 16S rRNA sequencing. Antimicrobial susceptibility was also conducted to guide the treatment of the disease
Metasomatized lithospheric mantle for Mesozoic giant gold deposits in the North China craton
The origin of giant lode gold deposits of Mesozoic age in the North China craton (NCC) is enigmatic because high-grade metamorphic ancient crust would be highly depleted in gold. Instead, lithospheric mantle beneath the crust is the likely source of the gold, which may have been anomalously enriched by metasomatic processes. However, the role of gold enrichment and metasomatism in the lithospheric mantle remains unclear. Here, we present comprehensive data on gold and platinum group element contents of mantle xenoliths (n = 28) and basalts (n = 47) representing the temporal evolution of the eastern NCC. The results indicate that extensive mantle metasomatism and hydration introduced some gold (<1–2 ppb) but did not lead to a gold-enriched mantle. However, volatile-rich basalts formed mainly from the metasomatized lithospheric mantle display noticeably elevated gold contents as compared to those from the asthenosphere. Combined with the significant inheritance of mantle-derived volatiles in auriferous fluids of ore bodies, the new data reveal that the mechanism for the formation of the lode gold deposits was related to the volatile-rich components that accumulated during metasomatism and facilitated the release of gold during extensional craton destruction and mantle melting. Gold-bearing, hydrous magmas ascended rapidly along translithospheric fault zones and evolved auriferous fluids to form the giant deposits in the crust
Kinetic Study on the Isothermal and Nonisothermal Crystallization of Monoglyceride Organogels
The isothermal and nonisothermal crystallization kinetics of monoglyceride (MAG) organogels were studied by pulsed nuclear magnetic resonance (pNMR) and differential scanning calorimetry (DSC), respectively. The Avrami equation was used to describe the isothermal crystallization kinetics and experimental data fitted the equation fairly well. Results showed that the crystal growth of MAG organogels was a rod-like growth of instantaneous nuclei at higher degrees of supercooling and a plate-like form with high nucleation rate at lower degrees of supercooling. The exothermic peak in nonisothermal DSC curves for the MAG organogels became wider and shifted to lower temperature when the cooling rate increased, and nonisothermal crystallization was analyzed by Mo equation. Results indicated that at the same crystallization time, to get a higher degree of relative crystallinity, a higher cooling rate was necessary. The activation energy of nonisothermal crystallization was calculated as 739.59 kJ/mol according to the Kissinger method. Therefore, as the results of the isothermal and nonisothermal crystallization kinetics for the MAG organogels obtained, the crystallization rate, crystal nucleation, and growth during the crystallization process could be preliminarily monitored through temperature and cooling rate regulation, which laid the foundation for the real industrial manufacture and application of the MAG organogels
Close-in Exoplanets as Candidates of Strange Quark Matter Objects
Since the true ground state of the hadrons may be strange quark matter (SQM),
pulsars may actually be strange stars rather than neutron stars. According to
this SQM hypothesis, strange planets can also stably exist. The density of
normal matter planets can hardly be higher than 30 g cm. As a result,
they will be tidally disrupted when its orbital radius is less than , or when the orbital period () is
less than . On the contrary, a strange planet can safely
survive even when it is very close to the host, due to its high density. The
feature can help us identify SQM objects. In this study, we have tried to
search for SQM objects among close-in exoplanets orbiting around pulsars.
Encouragingly, it is found that four pulsar planets (XTE J1807-294 b, XTE
J1751-305 b, PSR 0636 b, PSR J1807-2459A b) completely meet the criteria of
, and are thus good candidates for SQM planets.
The orbital periods of two other planets (PSR J1719+14 b and PSR J2051-0827 b)
are only slightly higher than the criteria. They could be regarded as potential
candidates. Additionally, we find that the periods of five white dwarf planets
(GP Com b, V396 Hya b, J1433 b, WD 0137-349 b, and SDSS J1411+2009 b) are less
than 0.1 days. We argue that they might also be SQM planets. It is further
found that the persistent gravitational wave emissions from at least three of
these close-in planetary systems are detectable to LISA. More encouragingly,
the advanced LIGO and Einstein Telescope are able to detect the gravitational
wave bursts produced by the merger events of such SQM planetary systems, which
will provide a unique test for the SQM hypothesis.Comment: 13 pages, 5 figures, 4 tables, comments and suggestions are welcom
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