Cavity QED treatment of scattering-induced efficient free-space excitation and collection in high-Q whispering-gallery microcavities

Whispering-gallery microcavity laser possesses ultralow threshold, whereas convenient free-space optical excitation and collection suffer from low efficiencies due to its rotational symmetry. Here we analytically study a three-dimensional microsphere coupled to a nano-sized scatterer in the framework of quantum optics. It is found that the scatterer is capable of coupling light in and out of the whispering-gallery modes (WGMs) without seriously degrading their high-Q properties, while the microsphere itself plays the role of a lens to focus the input beam on the scatterer and vice versa. Our analytical results show that (1) the high-Q WGMs can be excited in free space, and (2) over 50% of the microcavity laser emission can be collected within less than ${1}^{\circ}$. This coupling system holds great potential for low threshold microlasers free of external couplers.Comment: 10 pages, 8 figure

Strongly enhanced light-matter interaction in a hybrid photonic-plasmonic resonator

We propose a hybrid photonic-plasmonic resonant structure which consists of a metal nanoparticle (MNP) and a whispering gallery mode (WGM) microcavity. It is found that the hybrid mode enables a strong interaction between the light and matter, and the single-atom cooperativity is enhanced by more than two orders of magnitude compared to that in a bare WGM microcavity. This remarkable improvement originates from two aspects: (1) the MNP offers a highly enhanced local field in the vicinity of an emitter, and (2), surprisingly, the high-\textit{Q} property of WGMs can be maintained in the presence of the MNP. Thus the present system has great advantages over a single microcavity or a single MNP, and holds great potential in quantum optics, nonlinear optics and highly sensitive biosening.Comment: 5 pages, 4 figure

Coupling of a Single Diamond Nanocrystal to a Whispering-Gallery Microcavity: Photon Transportation Benefitting from Rayleigh Scattering

We study the Rayleigh scattering induced by a diamond nanocrystal in a whispering-gallery-microcavity--waveguide coupling system, and find that it plays a significant role in the photon transportation. On one hand, this study provides a new insight into future solid-state cavity quantum electrodynamics toward strong coupling physics. On the other hand, benefitting from this Rayleigh scattering, novel photon transportation such as dipole induced transparency and strong photon antibunching can occur simultaneously. As potential applications, this system can function as high-efficiency photon turnstiles. In contrast to [B. Dayan \textit{et al.}, \textrm{Science} \textbf{319},1062 (2008)], the photon turnstiles proposed here are highly immune to nanocrystal's azimuthal position.Comment: 4 pages, 4 figure

Ultrasound-assisted degradation of a new bacterial exopolysaccharide WL-26 from Sphingomonas sp.

Ultrasonic degradation of a new exopolysaccharide WL-26 from Sphingomonas sp. was made over the frequency range 200 to 1200 Hz and polymer concentrations of 3, 5, 10 and 20 g/L using high performance anion exchange pulsed-amperometric detection chromatography (HPAEC–PAD) and infrared spectroscopy. Sonication was more efficient with less concentrated polysaccharide solutions, high ultrasonic frequency, long duration of ultrasonic irradiation and degradation continued until a limiting molecular weight was attained. Results show that HPAEC–PAD revealed WL-26 to be an acidic polysaccharide composed of rhamnose, glucose, mannose, galactose and glucuronic acid in the molar ratio of 10:9:3:1:3 distinctly different from welan gum which does not contain galactose.Key words: Exopolysaccharide WL-26, ultrasonic degradation, infrared spectroscopy

Uptake and transport of a novel anticancer drug-delivery system: lactosyl-norcantharidin-associated N-trimethyl chitosan nanoparticles across intestinal Caco-2 cell monolayers

In this paper, novel liver-targeting nanoparticles (NPs), lactosyl-norcantharidin (Lac-NCTD)-associated N-trimethyl chitosan (TMC) NPs (Lac-NCTD-TMC-NPs), were prepared using ionic cross-linkage. The physical properties, particle size, and encapsulation efficiency of the nanoparticles were then investigated. The continuous line of heterogeneous human epithelial colorectal adenocarcinoma cells (Caco-2) cell monolayer model was used to study the transport mechanism of Lac-NCTD, and the effects of factors such as time, temperature, pH level, drug concentration, enhancers, and inhibitors. This model was also used to indicate the differences among Lac-NCTD, Lac-NCTD-associated chitosan NPs (Lac-NCTD-CS-NPs), and Lac-NCTD-TMC- NPs in the absorption and transportation of membranes. Drug concentration levels were measured using high-performance liquid chromatography. Active transport and paracellular transport were suggested to be both the primary and secondary mechanisms for Lac-NCTD absorption, respectively. Lac-NCTD uptake and absorption were not controlled by pH levels, but were positively correlated to uptake time, and negatively correlated to temperature. The basolateral to apical apparent permeability coefficients (Papps) were higher than those of the apical to basolateral values. The inhibitor of P-glycoprotein and the multidrug resistance-associated protein 2 significantly enhanced the uptake amount of Lac-NCTD. Compared with Lac-NCTD, Lac-NCTD-CS-NPs and Lac-NCTD-TMC-NPs significantly enhanced drug absorption. Additionally, the latter exhibited stronger action. Lac-NCTD-NPs could penetrate the plasma membrane of Caco-2 cells and translocate into the cytoplasm and even into the nucleus. Nanoparticles were uptaken into Caco-2 cells through the endocytosis pathway

Novel norcantharidin-loaded liver targeting chitosan nanoparticles to enhance intestinal absorption

In this paper, two novel liver-targeting nanoparticles, norcantharidin-loaded chitosan nanoparticles (NCTD-CS-NPs) and norcantharidin-associated galactosylated chitosan nanoparticles (NCTD-GC-NPs), were prepared using ionic cross-linkage. The physical properties, particle size, encapsulation efficiency, and drug release characteristics of the nanoparticles were investigated in vitro. To investigate the intestinal absorption mechanisms of the two preparations, a series of experiments was carried out, including in situ circulation method, in vitro everted gut sacs, and Ussing chamber perfusion technique. The absorption rate constants (Ka) of NCTD at different segments were found to be duodenum > jejunum > ileum > colon. The concentration had no distinctive effect on absorption kinetics, suggesting that drug absorption is not dose-dependent. The transport of NCTD was found to be inhibited by P-glycoprotein (P-gp) inhibitor, indicating that NCTD might be the substrate of P-gp. The order of the absorption enhancer effects were as follows: low molecular weight chitosan (CS-8kDa) > high molecular weight chitosan (CS-30kDa) > Poloxamer > sodium dodecyl sulfate (SDS) > sodium deoxycholate (SDCh). The results indicate that the chitosan nanoparticles can improve intestinal absorption of NCTD

Observation of Dirac hierarchy in three-dimensional acoustic topological insulators

Dirac cones (DCs) play a pivotal role in various unique phenomena ranging from massless electrons in graphene to robust surface states in topological insulators (TIs). Recent studies have theoretically revealed a full Dirac hierarchy comprising an eightfold bulk DC, a fourfold surface DC, and a twofold hinge DC, associated with a hierarchy of topological phases including first-order to third-order three-dimensional (3D) topological insulators, using the same 3D base lattice. Here, we report the first experimental observation of the Dirac hierarchy in 3D acoustic TIs. Using acoustic measurements, we unambiguously reveal that lifting of multifold DCs in each hierarchy can induce two-dimensional (2D) topological surface states with a fourfold DC in a first-order 3D TI, one-dimensional (1D) topological hinge states with a twofold DC in a second-order 3D TI, and zero-dimensional (0D) topological corner states in a third-order 3D TI. Our work not only expands the fundamental research scope of Dirac physics, but also opens up a new route for multidimensional robust wave manipulation

Association of left ventricular ejection fraction with contrast-induced nephropathy and mortality following coronary angiography or intervention in patients with heart failure

Background: Left ventricular ejection fraction (LVEF) is the most widely used parameter to evaluate the cardiac function in patients with heart failure (HF). However, the association between LVEF and contrast-induced nephropathy (CIN) is still controversial. Therefore, the aim of this study is to evaluate the association of LVEF with CIN and long-term mortality following coronary angiography (CAG) or intervention in patients with HF.Methods: We analyzed 1,647 patients with HF (New York Heart Association [NYHA] or Killip class >1) undergoing CAG or intervention, including 207 (12.57%) patients with reduced LVEF (HFrEF), 238 (14.45%) with mid-range LVEF (HFmrEF) and 1,202 (72.98%) with preserved LVEF (HFpEF). CIN was defined as an absolute increase of ≥0.5 mg/dL or a relative increase of ≥25% from baseline serum creatinine within 48–72 h after contrast medium exposure. Multivariable logistic regression and Cox proportional hazards regression analyses were performed to identify the association between LVEF, CIN and long-term mortality, respectively.Results: Overall, 225 patients (13.7%) developed CIN. Individuals with lower LVEF were more likely to develop CIN (HFrEF, HFmrEF and HFpEF: 18.4%, 21.8% and 11.2%, respectively; P<0.001), but without a significant trend after adjusting for the confounding factors (HFrEF vs HFpEF: odds ratio [OR] =1.01; HFmrEF vs HFpEF: OR =1.31; all P>0.05). However, advanced HF (NYHA class >2 or Killip class >1) was an independent predictor of CIN (adjusted OR =1.54, 95% confidence interval [CI], 1.07–2.22; P=0.019). During the mean follow-up of 2.3 years, reduced LVEF (HFrEF group) was significantly associated with increased mortality (HFrEF vs HFpEF: adjusted hazard ratio =2.88, 95% CI, 1.77–4.69; P<0.001).Conclusion: In patients with HF undergoing CAG or intervention, not worsened LVEF but advanced HF was associated with an increased risk of CIN. In addition, reduced LVEF was an independent predictor of long-term mortality following cardiac catheterization

Emodin Alleviates Liver Fibrosis of Mice by Reducing Infiltration of Gr1 hi

Emodin, as a major active component of Rheum palmatum L. and Polygonum cuspidatum, has been reported to have antifibrotic effect. However, the mechanism of emodin on antifibrotic effect for liver fibrosis was still obscure. In the present study, we aimed to investigate whether emodin can alleviate carbon tetrachloride- (CCl4-) induced liver fibrosis through reducing infiltration of Gr1hi monocytes. Liver fibrosis was induced by intraperitoneal CCl4 injection in mice. Mice in the emodin group received emodin treatment by gavage. Pretreatment with emodin significantly protected mice from liver inflammation and fibrosis revealed by the decreased elevation of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), as well as reduced hepatic necrosis and fibrosis by analysis of hematoxylin-eosin (HE) staining, Masson staining, α-smooth muscle actin (α-SMA), and collagen-I immunohistochemistry staining. Further, compared to CCl4 group, mice in the emodin group showed significantly less intrahepatic infiltration of Gr1hi monocytes. Moreover, emodin significantly inhibited hepatic expression of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), transforming growth factor-β1 (TGF-β1), granulin (GRN), monocyte chemoattractant protein 1 (MCP-1), and chemokine ligand 7 (CCL7), which was in line with the decreased numbers of intrahepatic Gr1hi monocytes. In conclusion, emodin can alleviate the degree of liver fibrosis by reducing infiltration of Gr1hi monocytes. These results suggest that emodin is a promising candidate to prevent and treat liver fibrosis