The US Program in Ground-Based Gravitational Wave Science: Contribution from the LIGO Laboratory

Recent gravitational-wave observations from the LIGO and Virgo observatories have brought a sense of great excitement to scientists and citizens the world over. Since September 2015,10 binary black hole coalescences and one binary neutron star coalescence have been observed. They have provided remarkable, revolutionary insight into the "gravitational Universe" and have greatly extended the field of multi-messenger astronomy. At present, Advanced LIGO can see binary black hole coalescences out to redshift 0.6 and binary neutron star coalescences to redshift 0.05. This probes only a very small fraction of the volume of the observable Universe. However, current technologies can be extended to construct "3rd Generation" (3G) gravitational-wave observatories that would extend our reach to the very edge of the observable Universe. The event rates over such a large volume would be in the hundreds of thousands per year (i.e. tens per hour). Such 3G detectors would have a 10-fold improvement in strain sensitivity over the current generation of instruments, yielding signal-to-noise ratios of 1000 for events like those already seen. Several concepts are being studied for which engineering studies and reliable cost estimates will be developed in the next 5 years

Sunburn Cell Formation, Dendritic Cell Migration, and Immunomodulatory Factor Production After Solar-Simulated Irradiation of Sunscreen-Treated Human Skin Explants In Vitro

Using human skin explants, we investigated the effects of two different sunscreen preparations containing a chemical UVB filter alone [sun protection factor (SPF) 5.2] or UVA+UVB filter [SPF 6.2] on sunburn cell formation, dendritic cell (DC) migration, CD86- and CD1a-positive cell number, and tumor necrosis factor alpha (TNFα) and interleukin (IL)-1, IL-10, and IL-12 production in the skin after irradiation with different doses of solar-simulated UV radiation. Sunscreen- or placebo-treated skin explants were irradiated with solar-simulated UV radiation at 0.5, 1, and 2 minimal erythematous dose equivalents (MEDE) (as determined in an in vivo human study) multiplied by the SPF of the placebo or sunscreens. After irradiation, skin explants were floated on RMPI medium for 48 h. Cells that had emigrated and the skin explants were histologically analyzed, and the soluble mediators were measured in the supernatants by ELISA. Exposure to UV radiation led to concentration-dependent increases in sunburn cell formation and TNFα production but a concentration-dependent decrease in DC migration and CD86- and CD1a-positive cell number in the epidermis. Both chemical sunscreens protected against those alterations. The immunoprotective capacity of the sunscreens correlated with their SPF but was independent of the sunscreens' UVA protection capacity, suggesting that UVA is not a major factor for immunosuppression under the conditions used in the model. UV irradiation did not significantly affect the vitality of emigrated DC; the expression of HLA, CD80, and lag on emigrated cells; the number of CD1a-positive cells in the dermis; or the production of IL-1, IL-10, and IL-12. We conclude that our model may be useful in determining the immunoprotective capacity of sunscreens

Electron-beam lithography of cinnamate polythiophene films: conductive nanorods for electronic applications

Electron beam lithography patterns selectively cinnamate-substituted polythiophene thin films via [2+2]-cycloaddition. A nanoscale organic field effect transistor is constructed using cross-linked and doped polythiophene as electrodes.</jats:p

Small Change, Big Impact: The Shape of Precursor Polymers Governs Poly‑<i>p</i>‑phenylene Synthesis

The synthesis of unsubstituted, structurally perfect poly­(para-phenylene) (PPP) has remained elusive for many decades. By modifying our previously reported precursor route towards PPP, we were able to simplify and optimize the precursor polymer synthesis and yields, the thermal conversion process to PPP, and the resulting material properties. We describe the synthesis of unprecedented anti-dialkoxycyclohexadienylenes, polymerized via Suzuki coupling to yield linear PPP precursor polymers. Changing the geometry and overall shape of the precursor viz upon going from syn- to anti-configuration of the monomer has two important consequences: (i) formation of the precursor polymer becomes more selective since cyclization of the monomer is no longer possible and (ii) the precursor polymer adopts a “stretched” geometry and becomes more similar to the rigid-rod of PPP, impacting the aromatization process and material properties. Films of the precursor polymers are thermally aromatized via dealkoxylation to yield structurally perfect and highly ordered, insoluble PPP. Long-range ordering within the thin films, not observed for its syn-analog, is induced as evidenced by atomic force microscopy, X-ray scattering, and IR and UV–vis/photoluminescence spectroscopy. The aromatization temperature, now feasible for fabrication of plastic devices, is significantly lowered from previously reported 300 °C to below 250 °C. The kinetics of the aromatization process were monitored via time-dependent IR measurements at different annealing temperatures, showing much faster quantitative aromatization for thin layers