Cascade Enhancement and Efficient Collection of Single Photon Emission under Topological Protection.

High emission rate, high collection efficiency, and immunity to defects are the requirements of implementing on-chip single photon sources. Here, we theoretically demonstrate that both cascade enhancement and high collection efficiency of emitted photons from a single emitter can be achieved simultaneously in a topological photonic crystal containing a resonant dielectric nanodisk. The nanodisk excited by a magnetic emitter can be regarded as a large equivalent magnetic dipole. The near-field overlapping between this equivalent magnetic dipole and edge state enables achieving a cascade enhancement of single-photon emission with a Purcell factor exceeding 4 × 103. These emitted photons are guided into edge states with a collection efficiency of more than 90%, which is also corresponding to quantum yield due to topological antiscattering and the absence of absorption. The proposed mechanism under topological protection has potential applications in on-chip light-matter interactions, quantum light sources, and nanolasers.

Entangled dark state mediated by a dielectric cavity within epsilon-near-zero materials.

Two emitters can be entangled by manipulating them through optical fields within a photonic cavity. However, maintaining entanglement for a long time is challenging due to the decoherence of the entangled qubits, primarily caused by cavity loss and atomic decay. Here, we found the entangled dark state between two emitters mediated by a dielectric cavity within epsilon-near-zero (ENZ) materials, ensuring entanglement maintenance over an extended period. To obtain the entangled dark state, we derived an effective model with degenerate mode modulation. In the dielectric cavities within ENZ materials, the decay rate of emitters can be regarded as 0, which is the key to achieving the entangled dark state. Meanwhile, the dark state immune to cavity loss exists when two emitters are in symmetric positions in the dielectric cavity. Additionally, by adjusting the emitters to specific asymmetric positions, it is possible to achieve transient entanglement with higher concurrence. By overcoming the decoherence of the entangled qubits, this study demonstrates stable, long-term entanglement with ENZ materials, holding significant importance for applications such as nanodevice design for quantum communication and quantum information processing.

Photonic-circuited resonance fluorescence of single molecules with an ultrastable lifetime-limited transition.

Resonance fluorescence as the emission of a resonantly-excited two-level quantum system promises indistinguishable single photons and coherent high-fidelity quantum-state manipulation of the matter qubit, which underpin many quantum information processing protocols. Real applications of the protocols demand high degrees of scalability and stability of the experimental platform, and thus favor quantum systems integrated on one chip. However, the on-chip solution confronts several formidable challenges compromising the scalability prospect, such as the randomness, spectral wandering and scattering background of the integrated quantum systems near heterogeneous and nanofabricated material interfaces. Here we report an organic-inorganic hybrid integrated quantum photonic platform that circuits background-free resonance fluorescence of single molecules with an ultrastable lifetime-limited transition. Our platform allows a collective alignment of the dipole orientations of many isolated molecules with the photonic waveguide. We demonstrate on-chip generation, beam splitting and routing of resonance-fluorescence single photons with a signal-to-background ratio over 3000 in the waveguide at the weak excitation limit. Crucially, we show the photonic-circuited single molecules possess a lifetime-limited-linewidth transition and exhibit inhomogeneous spectral broadenings of only about 5% over hours' measurements. These findings and the versatility of our platform pave the way for scalable quantum photonic networks.

Neuroprotective effect of ginkgetin in experimental cerebral ischemia/reperfusion via apoptosis inhibition and PI3K/Akt/mTOR signaling pathway activation.

BACKGROUND: Ginkgetin, extracted from Ginkgo biloba L leaves, has been demonstrated to have potential anti-inflammatory and immune-suppressive properties. But the neuroprotective effect and potential mechanisms of ginkgetin on cerebral ischemia/reperfusion (IR) injury remain unclear. METHODS: In this research, we studied the neuroprotective effect of ginkgetin in the middle part of the middle cerebral artery occlusion/reperfusion rat model, by analyzing the apoptosis of brain tissues harvested from treatment groups and control groups using the terminal deoxynucleotidyl transferase dUTP nick-end labeling and apoptosis assays. In addition, we detected the association of the neuroprotective effect of ginkgetin with apoptosis inhibition via the activation of the phosphatidylinositol-3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathway using Western blot analysis. RESULTS: Our results showed that administration of ginkgetin remarkably reduced brain infarction volumes and neurologic deficits; in addition, reducing apoptotic cell numbers, downregulating the levels of cleaved caspase-3 and Bax, and upregulating the level of Bcl-2 in rats subjected to IR injury in a dose-dependent manner. Moreover, high-dose ginkgetin treatment (100 mg/kg) significantly increased the phosphorylations of Akt and mTOR. Blocking of PI3K by LY294002 clearly decreased its antiapoptotic effect and reduced both Akt and mTOR phosphorylation levels. CONCLUSIONS: Taken together, these results for the first time suggest that ginkgetin antagonizes cerebral IR-induced injury by inhibiting apoptosis in rats, and this effect was attenuated by the activation of PI3K/Akt/mTOR signaling pathway.

Effect of maternal pregnancy-induced hypertension on neonatal immunity.

OBJECTIVE: To explore the effect of pregnancy-induced hypertension (PIH) on immune system of neonate. Materials and Methods Sixty neonates whose mothers suffered from PIH were selected and divided into preeclampsia group (n=28) and gestational hyperten sion (GH) group (n=32) according to severity of mother's condition. Thirty neonates having healthy mothers were enrolled as control group. The base clinical characteristics of neonates were collected and umbilical vein blood was drawn to detect the distribution of lymphocyte antigen, immune globulin, and complement level. RESULTS: The gestational week, birth weight, head circumference, and one minute Apgar score of both PIH groups were lower than those of control group, and preeclampsia group was lower than GH group (p < 0.05). There was significant difference between preeclampsia group and control group in blood, routine and blood glucose levels Concerning blood glucose levels, both PIH groups were lower than control group, and preeclampsia group was lower than GH group (p < 0.05). Content of IgG and complement C4 of GH group was lower than those of control group; IgG level of preeclampsia group was also lower than GH group (p < 0.05). CONCLUSIONS: PIH of pregnant mother affects the immunity of neonate, and more severe PIH will more negatively affect immunity of neonate.

[A New Calibrated Model of Coal Calorific Value Detection with LIBS].

A set of coal samples were used for laser-induced breakdown spectroscopy (LIBS) experiment to measure the coal calorific value. Traditional channel normalization method didn't consider the physical / chemical mechanism of coal, which would limit the model in precision, accuracy and repeatability. Thus a new calibrated model based on the kinds of the effects of spectral deviation was proposed in this paper. The model selected 19 groups of coal samples, where the random 15 groups were used to establish quantitative analysis model of calorific value while the remaining four for inspection and evaluation. The model based on spectral deviation factors, and the transmission theory combined with the stark broadening formula was used to deduce the absorption effect mechanism and the deviation correction method under the condition of LIBS. The mutual interference between elements and the mechanism of matrix effect were being analyzed while K coefficient method was used to correct mutual interference between the elements in the LIBS. The establishment of numerical model with the electron density, the plasma temperature and the element concentration was used to deeply corrected spectrum deviation caused by matrix effect. Thus taking into consideration of the effect of self-absorption, interfere of inter-elements and matrix effect, the calibration model was established, while R2=0.967, RMSEP=0.49 MJ·kg-1, RMSE=0.45 MJ·kg-1, MRE=2.42%, ARE=1.64%, RSD=5.79% and RSDP=8.10%. Compared with the 0.405, 8.28 MJ·kg-1, 4.14 MJ·kg-1, 22.85%, 52.48%, 18.28% and 32.85% of traditional channel normalized-multiple linear regression method, it demonstrated that the precision and accuracy have been improved significantly and model has good application value.

Therapeutic effect of okra extract on gestational diabetes mellitus rats induced by streptozotocin.

OBJECTIVE: To explore the effect of okra extract on gestational diabetes mellitus (GDM) rats and its probable molecular mechanism. METHODS: A total of 30 female SD rats were caged with male rats for pregnancy, 27 pregnant rats were obtained and weighed. The pregnant rats were equally randomized into the control group, GDM group and intervention group. Once the pregnancy was verified, GDM group and intervention group were given 45 mg/kg streptozotocin by peritoneal injection for inducing GDM, control group was given equal volume of citrate buffer. Once the model was established successfully, intervention group was administered orally the solution containing 200 mg/kg/d okra extract, the other groups were given the diet and water only. On the 19th day of pregnancy, the blood samples and fetal rats of all groups were collected, fetal rats weight and placental weight was recorded and the serum glucose, lipids, serum insulin and C-peptide of pregnant rats before the delivery were determined. RESULTS: The pregnant rats weight before the delivery, fetal rats weight and placental weight of GDM group were lower than control group and intervention group (P < 0.05). After the treatment of okra extract, serum glucose and lipids levels of intervention group were both improved significantly (P < 0.05), especially, the FBG, HDL, FINS, serum m insulin and hepatic glycogen levels were equivalent to control group (P > 0.05). Antioxidant enzymes levels of GDM group in liver and pancreas tissues were lower than the other groups, and after treatment of okra extract, antioxidant enzymes levels in liver and pancreas tissues were equivalent to control group (P > 0.05). CONCLUSIONS: Okra extract, rich in antioxidant substances, could avoid the excessive consuming of antioxidant enzymes, then, suppresses the oxidative stress and insulin resistance, thereby improving blood glucose level of GDM rats.