2,062 research outputs found
Silicon nitride metalenses for unpolarized high-NA visible imaging
As one of nanoscale planar structures, metasurface has shown excellent
superiorities on manipulating light intensity, phase and/or polarization with
specially designed nanoposts pattern. It allows to miniature a bulky optical
lens into the chip-size metalens with wavelength-order thickness, playing an
unprecedented role in visible imaging systems (e.g. ultrawide-angle lens and
telephoto). However, a CMOS-compatible metalens has yet to be achieved in the
visible region due to the limitation on material properties such as
transmission and compatibility. Here, we experimentally demonstrate a divergent
metalens based on silicon nitride platform with large numerical aperture
(NA~0.98) and high transmission (~0.8) for unpolarized visible light,
fabricated by a 695-nm-thick hexagonal silicon nitride array with a minimum
space of 42 nm between adjacent nanoposts. Nearly diffraction-limit virtual
focus spots are achieved within the visible region. Such metalens enables to
shrink objects into a micro-scale size field of view as small as a single-mode
fiber core. Furthermore, a macroscopic metalens with 1-cm-diameter is also
realized including over half billion nanoposts, showing a potential application
of wide viewing-angle functionality. Thanks to the high-transmission and
CMOS-compatibility of silicon nitride, our findings may open a new door for the
miniaturization of optical lenses in the fields of optical fibers,
microendoscopes, smart phones, aerial cameras, beam shaping, and other
integrated on-chip devices.Comment: 16 pages, 7 figure
Large-scale Kinetic Simulations of Colliding Plasmas within a Hohlraum of Indirect Drive Inertial Confinement Fusions
The National Ignition Facility has recently achieved successful burning
plasma and ignition using the inertial confinement fusion (ICF) approach.
However, there are still many fundamental physics phenomena that are not well
understood, including the kinetic processes in the hohlraum. Shan et al. [Phys.
Rev. Lett, 120, 195001, 2018] utilized the energy spectra of neutrons to
investigate the kinetic colliding plasma in a hohlraum of indirect drive ICF.
However, due to the typical large spatial-temporal scales, this experiment
could not be well simulated by using available codes at that time. Utilizing
our advanced high-order implicit PIC code, LAPINS, we were able to successfully
reproduce the experiment on a large scale of both spatial and temporal
dimensions, in which the original computational scale was increased by
approximately 7 to 8 orders of magnitude. When gold plasmas expand into
deuterium plasmas, a kinetic shock is generated and propagates within deuterium
plasmas. Simulations allow us to observe the entire progression of a strong
shock wave, including its initial formation and steady propagation. Although
both electrons and gold ions are collisional (on a small scale compared to the
shock wave), deuterium ions seem to be collisionless. This is because a
quasi-monoenergetic spectrum of deuterium ions can be generated by reflecting
ions from the shock front, which then leads to the production of neutrons with
unusual broadening due to beam-target nuclear reactions. This work displays an
unprecedented kinetic analysis of an existing experiment, shedding light on the
mechanisms behind shock wave formation. It also serves as a reference for
benchmark simulations of upcoming new simulation codes and may be relevant for
future research on mixtures and entropy increments at plasma interfaces
Fucoxanthin-Rich Brown Algae Extract Decreases Inflammation and Attenuates Colitis-associated Colon Cancer in Mice
Abstract Fucoxanthin is a natural carotenoid that is isolated from seaweed. We evaluated the effects of fucoxanthin-rich brown algae extract (FX-BAE) on the development of dextran sulfate sodium (DSS)-induced colitis, and colitis-associated colon cancer (CACC) in BALB/c mice. Colitis mice were given drinking water containing 3% DSS for 14 days, and fed with or without FX-BAE (1, 2.5, or 5 g/kg bodyweight/day) from day 8 to day 14. Another way, CACC mice were treated with azoxymethane (AOM) and 2% DSS, and fed with or without FX-BAE at 0.5, 1, or 2.5 g/kg every 2 days. Results revealed the disease activity index (DAI), nitric oxide (NO), malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6) were all significantly less in FX-BAE treated mice. Additionally, FX-BAE not only decreased the incidence of colonic neoplasm, but also increased superoxide dismutase (SOD) production, lymphocyte proliferation and survival rate in CACC mice
Quantum interface between frequency-uncorrelated down-converted entanglement and atomic-ensemble quantum memory
Photonic entanglement source and quantum memory are two basic building blocks
of linear-optical quantum computation and long-distance quantum communication.
In the past decades, intensive researches have been carried out, and remarkable
progress, particularly based on the spontaneous parametric down-converted
(SPDC) entanglement source and atomic ensembles, has been achieved. Currently,
an important task towards scalable quantum information processing (QIP) is to
efficiently write and read entanglement generated from a SPDC source into and
out of an atomic quantum memory. Here we report the first experimental
realization of a quantum interface by building a 5 MHz frequency-uncorrelated
SPDC source and reversibly mapping the generated entangled photons into and out
of a remote optically thick cold atomic memory using electromagnetically
induced transparency. The frequency correlation between the entangled photons
is almost fully eliminated with a suitable pump pulse. The storage of a
triggered single photon with arbitrary polarization is shown to reach an
average fidelity of 92% for 200 ns storage time. Moreover,
polarization-entangled photon pairs are prepared, and one of photons is stored
in the atomic memory while the other keeps flying. The CHSH Bell's inequality
is measured and violation is clearly observed for storage time up to 1
microsecond. This demonstrates the entanglement is stored and survives during
the storage. Our work establishes a crucial element to implement scalable
all-optical QIP, and thus presents a substantial progress in quantum
information science.Comment: 28 pages, 4 figures, 1 tabl
Prognostic value of cystatin C in patients with nasopharyngeal carcinoma: a retrospective study of 1063 patients
OBJECTIVE: Patients with nasopharyngeal carcinoma experience highly variable outcomes despite receiving similar therapeutic regimens. Identifying biomarkers that predict survival and guide individualized therapy is urgently needed. Cystatin C has been explored as a valuable prognostic marker in several malignancies. We retrospectively assessed the relationship between serum cystatin C levels and nasopharyngeal carcinoma prognosis in a large cohort of nasopharyngeal carcinoma patients receiving long-term follow-up. METHODS: A total of 1063 consecutive patients diagnosed with nasopharyngeal carcinoma from June 2006 to December 2010 were retrospectively analyzed. The serum levels of cystatin C at the time of diagnosis were collected. Receiver operating characteristic curve analysis, the Kaplan-Meier method and multivariate analyses using a Cox regression model were performed to assess the correlation of cystatin C levels with overall survival, progression-free survival, distant metastasis-free survival and loco-regional recurrence-free survival. RESULTS: The median follow-up duration was 68.3 months. The optimal cut-off value of cystatin C levels for predicting death was 0.945 mg/L. Compared with the low cystatin C group, the high cystatin C group experienced significantly shorter overall survival (hazard ratio=1.47, p=0.050), progression-free survival (hazard ratio=1.65, p=0.004), distant metastasis-free survival (hazard ratio=2.37,
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