Tunable hybridization of graphene plasmons and dielectric modes for highly confined light transmit at terahertz wavelength.

We theoretically report a novel graphene-based hybrid plasmonic waveguide (GHPW) by integrating a GaAs micro-tube on a silica spacer that is supported by a graphene-coated substrate. In comprehensive numerical simulations on guiding properties of the GHPW, it was found that the size of hybrid plasmonic mode (TM) can be reduced significantly to ~10-4(λ2/4), in conjunction with long propagation distances up to tens of micrometers by tuning the the waveguide's key structure parameters and graphene's chemical potential. Moreover, crosstalk between two adjacent GHPWs that are placed on the same substrate has been analyzed and ultralow crosstalk can be realized. The proposed scheme potentially enables realization of the various high performance nanophotonic components-based subwavelength plasmonic waveguides in terahertz domain.

Sympathetic and parasympathetic innervation in hepatocellular carcinoma.

Autonomic nervous system plays an important role in the development of multiple cancers via regulating cancer cell proliferation, differentiation, apoptosis, migration and invasion. However, no detailed studies have been performed to study the role of autonomic nerve fibers in hepatocellular carcinoma (HCC) as well as its correlation with the progression of HCC. Here, we examined the distribution of the autonomic nerve fibers and analyzed the correlation between autonomic nerve fibers and the pathological characteristics of HCC patients. The transcriptional expression of adrenergic and cholinergic receptors was evaluated in both hepatoma cell lines and primary hepatoma cells. In addition, we summarized the function of receptors for neurotransmitters in different cancers recently reported. Our findings indicate that tissue of liver cancer is innervated by both sympathetic and parasympathetic nerves and the density of the nerve fibers is associated with patients' poor prognosis. Additionally, we report that adrenergic receptors ß2 and cholinergic receptors α7, M1 and M3 are high expressed in both hepatoma cell lines and primary hepatoma cells, indicating these receptors may play essential roles in the regulation of autonomic nervous system triggered HCC.

Crystal Field Splitting is Limiting the Stability and Strength of Ultra-incompressible Orthorhombic Transition Metal Tetraborides.

The lattice stability and mechanical strengths of the supposedly superhard transition metal tetraborides (TmB4, Tm = Cr, Mn and Fe) evoked recently much attention from the scientific community due to the potential applications of these materials, as well as because of general scientific interests. In the present study, we show that the surprising stabilization of these compounds from a high symmetry to a low symmetry structure is accomplished by an in-plane rotation of the boron network, which maximizes the in-plane hybridization by crystal field splitting between d orbitals of Tm and p orbitals of B. Studies of mechanical and electronic properties of TmB4 suggest that these tetraborides cannot be intrinsically superhard. The mechanical instability is facilitated by a unique in-plane or out-of-plane weakening of the three-dimensional covalent bond network of boron along different shear deformation paths. These results shed a novel view on the origin of the stability and strength of orthorhombic TmB4, highlighting the importance of combinational analysis of a variety of parameters related to plastic deformation of the crystalline materials when attempting to design new ultra-incompressible, and potentially strong and hard solids.

Induced magnetization in La0.7Sr0.3MnO3/BiFeO3 superlattices.

Using polarized neutron reflectometry, we observe an induced magnetization of 75 ± 25 kA/m at 10 K in a La(0.7)Sr(0.3)MnO(3) (LSMO)/BiFeO(3) superlattice extending from the interface through several atomic layers of the BiFeO(3) (BFO). The induced magnetization in BFO is explained by density functional theory, where the size of band gap of BFO plays an important role. Considering a classical exchange field between the LSMO and BFO layers, we further show that magnetization is expected to extend throughout the BFO, which provides a theoretical explanation for the results of the neutron scattering experiment.

Local application of rapamycin inhibits vein graft restenosis in rabbits.

OBJECTIVE: The aim of this study was to investigate whether local application of rapamycin reduced neointimal formation in a rabbit model of venous disease. METHODS: Each rabbit (n = 30; 2.5-3.5 kg) received a treated and a control graft. For the treated graft, 0.3 rapamycin mg was applied locally in Pluronic gel. The control graft received only the Pluronic gel. Grafts were harvested at 28 days for morphometric, immunohistochemical, and flow cytometry analysis. RESULTS: In the control group, the intimal thickness was 63.72 ± 14.0 µm; in treated group, it was 77.76 ± 14.9 µm (P < .05). Immunohistochemically, proliferation cell nuclear antigen-positive cells were present in the control group and in the treatment group but not in normal external jugular veins. The control group showed much stronger expression than the treatment group (P < .05). Flow cytometry showed, among the control group, decreased G(0)G(1)-stage cells and increased S/G(2)M-stage cells. Among the treatment group, S/G(2)M stage cells were decreased compared with the control. The progression indexes of the control and treatment groups were 29.3 ± 7.15 and 20.1 ± 9.48, respectively, a remarkable decrease (P < .05). Proliferating cells in the control group were apparently inhibited by rapamycin. The treatment group showed positive staining for P27(kip1), but neither the control group nor the normal external jugular veins showed positive results (P < .05). The degree of reduction in intimal thickness and inhibition of proliferating cells in the treatment group correlated with the expression of P27(kip1). CONCLUSIONS: We observed that perivascular application of rapamycin inhibited neointimal hyperplasia of vein grafts in a rabbit model, an effect that appeared to result from increased P27(kip1) expression.

Intrinsic dipole-field-driven mesoscale crystallization of core-shell ZnO mesocrystal microspheres.

Novel uniform-sized, core-shell ZnO mesocrystal microspheres have been synthesized on a large scale using a facile one-pot hydrothermal method in the presence of the water-soluble polymer poly(sodium 4-styrenesulfonate). The mesocrystal forms via a nonclassical crystallization process. The intrinsic dipole field introduced by the nanoplatelets as a result of selective adsorption of the polyelectrolyte on some polar surfaces of the nanoparticles acts as the driving force. In addition, it plays an important role throughout the mesoscale assembly process from the creation of the bimesocrystalline core to the apple-like structure and finally the microsphere. Our calculation based on a dipole model confirms the dipole-field-driven mechanism forming the apple-like structure.

Activator protein-1 transcription factor mediates bombesin-stimulated cyclooxygenase-2 expression in intestinal epithelial cells.

Colorectal carcinogenesis is a complex, multistep process involving genetic alterations and progressive changes in signaling pathways regulating intestinal epithelial cell proliferation, differentiation, and apoptosis. Although cyclooxygenase-2 (COX-2), gastrin-releasing peptide (GRP), and its receptor, GRP-R, are not normally expressed by the epithelial cells lining the human colon, the levels of all three proteins are aberrantly overexpressed in premalignant adenomatous polyps and colorectal carcinomas of humans. Overexpression of these proteins is associated with altered epithelial cell growth, adhesion, and tumor cell invasiveness, both in vitro and in vivo; however, a mechanistic link between GRP-R-mediated signaling pathways and increased COX-2 overexpression has not been established. We report that bombesin, a homolog of GRP, potently stimulates the expression of COX-2 mRNA and protein as well as the release of prostaglandin E(2) from a rat intestinal epithelial cell line engineered to express GRP-R. Bombesin stimulation of COX-2 expression requires an increase in [Ca(2+)](i), activation of extracellular signal-regulated kinase (ERK)-1 and -2 and p38(MAPK), and increased activation and expression of the transcription factors Elk-1, ATF-2, c-Fos, and c-Jun. These data suggest that the expression of GRP-R in intestinal epithelial cells may play a role in carcinogenesis by stimulating COX-2 overexpression through an activator protein-1-dependent pathway.

[Influence of lead on activity of nitric oxide synthase in neurons and vessel smooth muscle of small intestine in rats].

The beta-NADPH histochemical method was used to study the effect of lead on activity of nitric oxide synthase(NOS) in neurons and vessel smooth muscles of intestinal wall in rats. The results showed that the number of NOS positive neurons and fibers was decreased and degenerative changes of some NOS positive neurons were found after the lead acetate intraperitoneal injection. The activity of NOS in the vessel smooth muscles was reduced. It suggests that lead colic may be induced by reduction of NO in the neurons which innervate the gut smooth muscles.