The synchrosqueezing transform (SST) is a novel approach for time-frequency (T-F) representation of non-stationary signals. By synchrosqueezing and reassigning the T-F spectrum of the wavelet ...transform (WT) or the short time Fourier transform (STFT) of a signal, the SST can obtain a high-resolution T-F spectrum. In the light of the superiority of S-transform (ST) over the WT and the STFT, especially, in representing a high-frequency weak-amplitude signal on its T-F spectrum, we propose a synchrosqueezing S-transform (SSST) which is realized by synchrosqueezing the spectrum of the ST. The formulas for the SSST and its inverse transform are derived. Synthetic examples show that the SSST has obviously higher resolution than the ST, and is superior to the SST like the ST to the WT. We then applied the SSST to perform the spectral decomposition of a marine seismic data for natural gas hydrate exploration. The results illustrate that the SSST can be used to well detect frequency spectral anomalies correlated with the gas hydrate and free-gas accumulations. We can also conclude that the SSST is a good potential technique to assist seismic interpretation.
Metasurface‐based lenses (metalenses) offer specific conceptual advantages compared to ordinary refractive lenses. For example, it is possible to tune the focal length of a metalens doublet by ...varying the relative angle between the two metalenses while fixing their distance, leading to an extremely compact zoom lens. An improved polarization‐insensitive design based on silicon nanocylinders on silica substrates is presented. This design is realized and characterized experimentally at 1550 nm wavelength. By varying the relative angle between the metalenses in steps of 10°, tuning of the doublet focal length is demonstrated from −54 mm to ±3 mm to +54 mm. This results in a zoom factor of an imaging system varying between 1 and 18. For positive focal lengths, the doublet focusing efficiency has a minimum of 34% and a maximum of 83%. Experiment and theory are in very good agreement.
In this work, experimental results following an optimized design of a zoom metalens doublet are presented, based on rotating two metasurfaces with respect to each other at fixed distance between them, at an operation wavelength of 1550 nm. The focal length could be adjusted from ±3 mm to ±54 mm, corresponding to extremal zoom factors of ±18× at an average focusing efficiency of 54%.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
is an increasingly important cause of invasive candidiasis. In China, relatively little is known of the molecular epidemiology of
and of its antifungal susceptibility patterns. Here we studied 411 ...non-duplicate
isolates from 411 patients at 11 hospitals participating in the National China Hospital Invasive Fungal Surveillance Net program (CHIF-NET; 2010-2014). Genotyping was performed using multilocus sequence typing (MLST) employing six genetic loci and by microsatellite analysis. Antifungal susceptibility testing was performed using Sensititre YeastOne™ YO10 methodology. Of 411 isolates, 35 sequence types (ST) were identified by MLST and 79 different genotypes by microsatellite typing; the latter had higher discriminatory power than MLST in the molecular typing of
. Using MLST, ST7 and ST3 were the most common STs (66.4 and 9.5% of all isolates, respectively) with 24 novel STs identified; the most common microsatellite types were T25 (30.4% of all isolates) and T31 (12.4%). Resistance to fluconazole (MIC > 32 μg/mL) was seen in 16.5% (68/411) of isolates whilst MICs of >0.5 μg/mL for voriconazole, >2 μg/mL for itraconazole and >2 μg/mL for posaconazole were seen for 28.7, 6.8, and 7.3% of isolates, respectively; 14.8% of all isolates cross-resistant/non-wide-type to fluconazole and voriconazole. Fluconazole resistant rates increased 3-fold over the 5-year period whilst that of isolates with non-WT MICs to voriconazole, 7-fold. All echinocandins exhibited >99% susceptibility rates against all isolates but notably one isolate exhibited multi-drug resistance to the azoles and echinocandins. The study has provided a global picture of the molecular epidemiology and drug resistance rates of
in China during the period of the study.
Large-scale trapped-ion quantum computers hold great promise to outperform classical computers and are crucially desirable for finance, pharmaceutical industry, fundamental chemistry and other ...fields. Currently, a big challenge for trapped-ion quantum computers is the poor scalability mainly brought by the optical elements that are used for optical addressing. Metasurfaces provide a promising solution due to their excellent flexibility and integration ability. Here, we propose and numerically demonstrate a scalable off-axis metalens array for optical addressing working at the wavelength of 350 nm. Metalens arrays designed for
x
linearly polarized and left circularly polarized light respectively can focus the collimated addressing beam array into a compact focused spot array with spot spacing of 5 μm, featuring crosstalk below 0.82%.
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EMUNI, FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OILJ, PNG, SAZU, SBCE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
As a new type of two-dimensional nanomaterials, MXene has been widely investigated since its discovery at 2011 due to its excellent physical and chemical properties, such as high conductivity, good ...lubricity, electromagnetism and other special properties. Hence, in addition to the performance of the traditional two-dimensional materials, MXene has been extensively used in the fields of energy storage, catalysis, lubrication, electromagnetic shielding, sensor, water purification and so on,and certain results and progress were achieved. The latest researches of MXene at structure, property and preparation methods, as well as the related achievements in lithium ion battery, supercapacitor and others at our country and overseas in recent years were reviewed in this paper. Moreover, the shortcomings of current research were summarized, and the future research direction were prospected as well.
The physical/chemical properties and synthesis methods of nanoparticles were briefly introduced, and then the type and principle of the self-assembly of nanoparticles were discussed in detail. The ...research progress in the application of the nanoparticle self-assembly in lithium-ion batteries was summarized, and the existing problems such as the low production efficiency and high pollution in this field were also pointed out. The future works will be focused on developing approp-riate building blocks, disclosing the self-organization mechanisms and simplifying the fabrication processes, and the simultaneous yet effective adjustion of the self-assembly processes in the materials synthesis stage for advanced battery components with hierarchical structures or functions is one of the most important approaches.
Multi-wall carbon nanotube/Fe3O4 hybrids were prepared by a chemical synthesis-hydrothermal treatment method and their electromagnetic wave absorbing properties were investigated in the frequency ...range of 8.2–12.4 GHz (X band). As-prepared hybrids were characterized by transmission electron microscopy, X-ray diffraction and vibrating sample magnetometer. Results indicated that the surface of multi-wall carbon nanotubes was attached to magnetic Fe3O4 nanoparticles. The Fe3O4 content increased and the magnetism of the hybrids was enhanced by increasing the concentrations of Fe2+ and Fe3+ in solution. The minimum reflection loss (−18.22 dB, 12.05 GHz) was the lowest and the absorbing bandwidth was the widest when the concentrations of Fe2+ and Fe3+ were 0.02 and 0.04 mol/L, respectively.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Due to the extremely complex geological conditions in the Bohai Strait, active faults is very developed and earthquake activity occurs frequently. It is of great importance to evaluate the regional ...crustal stability for the planning and construction of the Trans-straits Passage. In this study, the authors carry out the evaluation by means of buffer analysis, topology analysis and overlay analysis based on ArcGIS software. The evaluation mainly analyzed six assessment factors of Bohai Strait including neotectonic activity, active faults distribution, seismicity, tectonic stress fields, Bouguer gravity anomaly and geological disasters. In brief, the crustal stability of the eastern North Yellow Sea Basin is best, while that of the Bohai Basin and southwest Bohai Strait is poor. Meanwhile, small and frequent earthquakes in the southern Strait and geological disasters developed in the northern and central Strait such as tidal ridge and shallow gas which may adversely impact on the Trans-straits Passage construction.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract Achromatic metalenses in the mid-wave infrared (3–5 μ m), known for their light weight, CMOS compatibility, and ultra-compactness, offer significant potential in astronomy, security ...inspections, and health security. However, previous endeavors have been hindered by underdeveloped material technology and relatively low efficiency. To address these challenges, this study introduces an enhanced-efficiency mid-wave infrared achromatic double-layer metalens, featuring a top-layer ZnS nanopillar array and a bottom-layer Si nanopillar array on a Si substrate. Utilizing this approach, we numerically demonstrate both polarization-insensitive and polarization-controlled varifocal broadband achromatic metalenses. For the polarization-insensitive metalens, the double-layer design provides achromatic focusing comparable to the all-Si counterpart, with a focal length of 133 µ m, a focal length shift within ± 5.5%, and Strehl ratios above 0.8. However, the average focal efficiency improves from 40.8% (all-Si) to 50.2% (double-layer). Additionally, both all-Si and double-layer polarization-controlled varifocal achromatic metalenses show similar focusing abilities, with focal lengths of about 137 and 173 µ m under X and Y linearly polarized light, respectively. Yet, the double-layer varifocal metalens achieves focal efficiencies of 46.4% and 52.7%, an improvement of 13.1% and 17.6% under X and Y linearly polarized light, respectively.
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