Microwave shielding of transparent and conducting single-walled carbon nanotube films

The authors measured the transport properties of single-walled carbon nanotube (SWCNT) films in the microwave frequency range from 10 MHz to 30 GHz by using the Corbino reflection technique from temperatures of 20-400 K. Based on the real and imaginary parts of the microwave conductivity, they calculated the shielding effectiveness for various film thicknesses. Shielding effectiveness of 43 dB at 10 MHz and 28 dB at 10 GHz are found for films with 90% optical transmittance, which suggests that SWCNT films are promising as a type of transparent microwave shielding material. By combining their data with those from the literature, the conductivity of SWCNT films was established in a broad frequency range from dc to visible.Comment: 4 pages, 4 figure

Frequency- and electric-field-dependent conductivity of single-walled carbon nanotube networks of varying density

We present measurements of the frequency and electric field dependent conductivity of single walled carbon nanotube(SWCNT) networks of various densities. The ac conductivity as a function of frequency is consistent with the extended pair approximation model and increases with frequency above an onset frequency $\omega_0$ which varies over seven decades with a range of film thickness from sub-monolayer to 200 nm. The nonlinear electric field-dependent DC conductivity shows strong dependence on film thickness as well. Measurement of the electric field dependence of the resistance R(E) allows for the determination of a length scale $L_{E}$ possibly characterizing the distance between tube contacts, which is found to systematically decrease with increasing film thickness. The onset frequency $\omega_0$ of ac conductivity and the length scale $L_{E}$ of SWCNT networks are found to be correlated, and a physically reasonable empirical formula relating them has been proposed. Such studies will help the understanding of transport properties and benefit the applications of this material system.Comment: 7 pages and 6 figure

Vascular niche IL-6 induces alternative macrophage activation in glioblastoma through HIF-2α.

Spatiotemporal regulation of tumor immunity remains largely unexplored. Here we identify a vascular niche that controls alternative macrophage activation in glioblastoma (GBM). We show that tumor-promoting macrophages are spatially proximate to GBM-associated endothelial cells (ECs), permissive for angiocrine-induced macrophage polarization. We identify ECs as one of the major sources for interleukin-6 (IL-6) expression in GBM microenvironment. Furthermore, we reveal that colony-stimulating factor-1 and angiocrine IL-6 induce robust arginase-1 expression and macrophage alternative activation, mediated through peroxisome proliferator-activated receptor-γ-dependent transcriptional activation of hypoxia-inducible factor-2α. Finally, utilizing a genetic murine GBM model, we show that EC-specific knockout of IL-6 inhibits macrophage alternative activation and improves survival in the GBM-bearing mice. These findings illustrate a vascular niche-dependent mechanism for alternative macrophage activation and cancer progression, and suggest that targeting endothelial IL-6 may offer a selective and efficient therapeutic strategy for GBM, and possibly other solid malignant tumors

Connexin32 is a Myelin-Related Protein in the PNS and CNS

We have examined the expression of a gap junction protein, connexin32 (Cx32), in Schwann cells and oligodendrocytes. In peripheral nerve, Cx32 is found in the paranodal myelin loops and Schmidt-Lanterman incisures of myelinating Schwann cells, and the levels of Cx32 protein and mRNA change in parallel with those of other myelin-related genes during development, Wallerian degeneration, and axonal regeneration. In the central nervous system, Cx32 is found in oligodendrocytes and their processes, but not in compact myelin, and the levels of Cx32 protein and mRNA increase during development in parallel with those of the other myelin genes. Thus, Cx32 is expressed as part of the myelinating phenotype of both Schwann cells and oligodendrocytes, indicating that this gap junction protein plays in important role in the biology of myelin-forming cells

2-Propyl 3,3-dibromo-2-hydroxy­pyrrolidine-1-carboxyl­ate

The title compound, C8H13Br2NO3, crystallizes as a non-merohedral twin with twin law −0.6 0 0.4/0 − 1 0 /1.6 0 0.6, and the structure has a refined twin domain ratio of 0.546 (5). The structure shows a compact conformation, with the ester unit roughly coplanar with a mean plane fitted through the non-H atoms of the pyrrolidine ring [dihedral angle = 8.23 (9)°]. In the crystal, inversion dimers linked by pairs of O—H⋯O hydrogen bonds generate an R 2 2(12) motif

Anti-malarial drug artesunate restores metabolic changes in experimental allergic asthma

The anti-malarial drug artesunate possesses anti-inflammatory and anti-oxidative actions in experimental asthma, comparable to corticosteroid. We hypothesized that artesunate may modulate disease-relevant metabolic alterations in allergic asthma. To explore metabolic profile changes induced by artesunate in allergic airway inflammation, we analysed bronchoalveolar lavage fluid (BALF) and serum from naïve and ovalbumin-induced asthma mice treated with artesunate, using both gas and liquid chromatography-mass spectrometry metabolomics. Pharmacokinetics analyses of serum and lung tissues revealed that artesunate is rapidly converted into the active metabolite dihydroartemisinin. Artesunate effectively suppressed BALF total and differential counts, and repressed BALF Th2 cytokines, IL-17, IL-12(p40), MCP-1 and G-CSF levels. Artesunate had no effects on both BALF and serum metabolome in naïve mice. Artesunate promoted restoration of BALF sterols (cholesterol, cholic acid and cortol), phosphatidylcholines and carbohydrates (arabinose, mannose and galactose) and of serum 18-oxocortisol, galactose, glucose and glucouronic acid in asthma. Artesunate prevented OVA-induced increases in pro-inflammatory metabolites from arginine–proline metabolic pathway, particularly BALF levels of urea and alanine and serum levels of urea, proline, valine and homoserine. Multiple statistical correlation analyses revealed association between altered BALF and serum metabolites and inflammatory cytokines. Dexamethasone failed to reduce urea level and caused widespread changes in metabolites irrelevant to asthma development. Here we report the first metabolome profile of artesunate treatment in experimental asthma. Artesunate restored specific metabolic perturbations in airway inflammation, which correlated well with its anti-inflammatory actions. Our metabolomics findings further strengthen the therapeutic value of using artesunate to treat allergic asthma

Immittance Matching for Multi-dimensional Open-system Photonic Crystals

An electromagnetic (EM) Bloch wave propagating in a photonic crystal (PC) is characterized by the immittance (impedance and admittance) of the wave. The immittance is used to investigate transmission and reflection at a surface or an interface of the PC. In particular, the general properties of immittance are useful for clarifying the wave propagation characteristics. We give a general proof that the immittance of EM Bloch waves on a plane in infinite one- and two-dimensional (2D) PCs is real when the plane is a reflection plane of the PC and the Bloch wavevector is perpendicular to the plane. We also show that the pure-real feature of immittance on a reflection plane for an infinite three-dimensional PC is good approximation based on the numerical calculations. The analytical proof indicates that the method used for immittance matching is extremely simplified since only the real part of the immittance function is needed for analysis without numerical verification. As an application of the proof, we describe a method based on immittance matching for qualitatively evaluating the reflection at the surface of a semi-infinite 2D PC, at the interface between a semi-infinite slab waveguide (WG) and a semi-infinite 2D PC line-defect WG, and at the interface between a semi-infinite channel WG and a semi-infinite 2D PC slab line-defect WG.Comment: 8 pages, 6 figure