Ultra-high, broadband gain in a lattice-engineered, Yb-doped double tungstate channel waveguide

150 dB/cm gain over 55 nm wavelength range between 977-1032 nm is obtained in a 47.5% Yb-doped potassium double tungstate waveguide amplifier. The dependence of luminescence lifetime and gain on Yb concentration is investigated

Towards integrated channel waveguide lasers in monoclinic double tungstates

The fabrication of lasers in monoclinic double tungstates has advanced from bulk and planar waveguide lasers toward the recent demonstration of channel waveguide lasers in the 1-μm and 2-μm wavelength regions [1-4]. Not only do these lasers provide a footprint reduction and low thresholds, but also appreciable output powers of several hundreds of milliWatts and slope efficiencies up to 71%. A drawback to these lasers is that the mirrors are not integrated, requiring the rather unstable butt-coupling of mirrors. Further integration of the lasers with on-chip mirrors [5] is naturally the next step towards integrated channel waveguide lasers in this material. Co-doped layers with different thulium doping levels of 1.5–8at.% and maximum gadolinium and lutetium doping levels, replacing all yttrium to obtain the maximum index contrast with the pure KYW substrate, are grown by liquid-phase epitaxy at 920–923°C. In this way, a refractive-index contrast of up to ~1.9×10-2 for E||Np (= transverse-magnetic, TM) polarization at 1950 nm is obtained. The layers are lapped and surface-polished to a laser-grade quality with a planar layer thickness of ~3–4.5 μm. Strip-loaded, corrugated silicon-nitride (SixNy) channel waveguides are patterned as follows: a SixNy layer with a thickness of ~400 nm is deposited onto the thulium-co-doped planar layer by PECVD. A 45-nm-thick chromium mask is subsequently sputtered onto the SixNy layer, followed by the deposition of an electron-beam-compatible resist with a thickness of ~180 nm. A corrugated channel waveguide pattern with a width of 20–30 μm, a periodicity of ~500 nm, and a duty cycle of 50% is written into the e-beam resist using a Raith 150TWO e-beam lithographic system. The channels are aligned such that the light propagates along the Ng optical axis. The pattern is developed and etched into the chromium layer by wet etching. Finally, the pattern is transferred into the SixNy layer by etching 400-nm deep using reactive ion etching. Finally, the chromium mask residue is removed. The resulting grated-waveguide structure is shown in Fig. 1. The characterization of the integrated lasers is ongoing and the results will be reported at the conference. In conclusion, SixNy layers have been deposited onto thulium-co-doped double tungstate layers and strip-loaded corrugated channel waveguides have been patterned into them using electron-beam lithography, providing on-chip integrated mirrors in a double tungstate channel waveguide configuration

Quasi-static crushing response of square hybrid carbon/aramid tube for automotive crash box application

One of the essential automotive parts is a crash box, which is essential for initial kinetic energy absorption. However, both vehicle weight and energy-absorbing performance of crash box requirements have to achieve. Recently, crash boxes made of hybrid materials have increasingly studied regarding their better crash performance and weight reduction effects compared to conventional metallic materials. Therefore, the aim of this study is to fabricate a hybrid carbon/aramid composite crash box with a hollow structure and to determine its mechanical properties under quasi-static axial compressive and tensile loading. This study shows that square hybrid carbon/aramid tubes provide an average 57.94 J energy absorption, average 0.72 kJ/kg specific energy absorption, average 62.46 kN crushing peak load, average 748.40 MPa compressive modulus and average 36.29 MPa maximum stress under quasi-static compressive loading. It is suggested that a square hybrid carbon/aramid tube could have the promising potential to replace aluminium or metallic structure to use as an automotive crash box for lightweight applications

The regulatory mechanisms of NG2/CSPG4 expression

Neuron-glial antigen 2 (NG2), also known as chondroitin sulphate proteoglycan 4 (CSPG4), is a surface type I transmembrane core proteoglycan that is crucially involved in cell survival, migration and angiogenesis. NG2 is frequently used as a marker for the identification and characterization of certain cell types, but little is known about the mechanisms regulating its expression. In this review, we provide evidence that the regulation of NG2 expression underlies inflammation and hypoxia and is mediated by methyltransferases, transcription factors, including Sp1, paired box (Pax) 3 and Egr-1, and the microRNA miR129-2. These regulatory factors crucially determine NG2-mediated cellular processes such as glial scar formation in the central nervous system (CNS) or tumor growth and metastasis. Therefore, they are potential targets for the establishment of novel NG2-based therapeutic strategies in the treatment of CNS injuries, cancer and other conditions of these types

The Pathway Coexpression Network: Revealing pathway relationships.

A goal of genomics is to understand the relationships between biological processes. Pathways contribute to functional interplay within biological processes through complex but poorly understood interactions. However, limited functional references for global pathway relationships exist. Pathways from databases such as KEGG and Reactome provide discrete annotations of biological processes. Their relationships are currently either inferred from gene set enrichment within specific experiments, or by simple overlap, linking pathway annotations that have genes in common. Here, we provide a unifying interpretation of functional interaction between pathways by systematically quantifying coexpression between 1,330 canonical pathways from the Molecular Signatures Database (MSigDB) to establish the Pathway Coexpression Network (PCxN). We estimated the correlation between canonical pathways valid in a broad context using a curated collection of 3,207 microarrays from 72 normal human tissues. PCxN accounts for shared genes between annotations to estimate significant correlations between pathways with related functions rather than with similar annotations. We demonstrate that PCxN provides novel insight into mechanisms of complex diseases using an Alzheimer's Disease (AD) case study. PCxN retrieved pathways significantly correlated with an expert curated AD gene list. These pathways have known associations with AD and were significantly enriched for genes independently associated with AD. As a further step, we show how PCxN complements the results of gene set enrichment methods by revealing relationships between enriched pathways, and by identifying additional highly correlated pathways. PCxN revealed that correlated pathways from an AD expression profiling study include functional clusters involved in cell adhesion and oxidative stress. PCxN provides expanded connections to pathways from the extracellular matrix. PCxN provides a powerful new framework for interrogation of global pathway relationships. Comprehensive exploration of PCxN can be performed at http://pcxn.org/