Nano-structuring of sputtered gold layers on glass by annealing

The crystalline structure and surface morphology of gold nano-structures prepared by sputtering on a glass substrate are studied. The properties of the gold nano-structures were determined at room temperature and after annealing at 300 °C. XRD analysis provided information about the gold crystalline structure. Significant difference in the dependence of the lattice parameter on the sputtering time was found between the as-sputtered and annealed samples. By the XRD method the texture, crystallite size and lattice stress were also determined. With increasing sputtering time the layer thickness and the size of crystallites increased. Another rapid enlargement of the crystallites is observed after annealing. On the as-sputtered samples the value of micro-deformation depends on the structure thickness. After annealing, however, the micro-deformation is nearly constant regardless of the sputtering time. On both, the as-sputtered and the annealed samples the gold crystallites are preferentially [111] oriented. After the annealing significant changes in the structure surface morphology and a dramatic increase of the surface roughness are observed due to a structure relaxation at increased temperature.     

The Status of Music: A Multicolor Sub/millimeter MKID Instrument

We report on the recent progress of the Multicolor Submillimeter (kinetic) Inductance Camera, or MUSIC. MUSIC will use antenna-coupled Microwave Kinetic Inductance Detectors to observe in four colors (150 GHz, 230 GHz, 290 GHz and 350 GHz) with 2304 detectors, 576 per band, at the Caltech Submillimeter Observatory. It will deploy in 2012. Here we provide an overview of the instrument, focusing on the array design. We have also used a pathfinder demonstration instrument, DemoCam, to identify problems in advance of the deployment of MUSIC. In particular, we identified two major limiters of our sensitivity: out-of-band light directly coupling to the detectors (i.e. not through the antenna), effectively an excess load, and a large 1/f contribution from our amplifiers and electronics. We discuss the steps taken to mitigate these effects to reach background-limited performance (BLIP) in observation.     

Grafting of gold nanoparticles and nanorods on plasma-treated polymers by thiols

Grafting of gold nanoparticles and nanorods on the surface of polymers, modified by plasma discharge, is studied with the aim to create structures with potential applications in electronics or tissue engineering. Surfaces of polyethyleneterephthalate and polytetrafluoroethylene were modified by plasma discharge and subsequently, grafted with 2-mercaptoethanol, 4,4′-biphenyldithiol, and cysteamine. The thiols are expected to be fixed via one of –OH, –SH or –NH₂ groups to reactive places on the polymer surface created by the plasma treatment. “Free” –SH groups are allowed to interact (graft) with gold nanoparticles and nanorods. Gold nano-objects were characterized before grafting by transmission electron microscopy and UV–Vis spectroscopy. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and electrokinetic analysis (zeta potential determination) were used for the characterization of polymer surface at different modification phases. It was proved by FTIR and XPS measurements that the thiols were chemically bonded on the surface of the plasma-treated polymers, and they mediate subsequent grafting of the gold nano-objects. On the surfaces, modified polymers were indicated some objects by AFM, size of which was dramatically larger in comparison with that of original nanoparticles and nanorods. This result and the other results of UV–Vis spectroscopy indicate an aggregation of deposited gold nano-objects.     

The descriptive epidemiology of local restaurant smoking regulations in Massachusetts: an analysis of the protection of restaurant customers and workers

Objectives: To describe the range of restaurant smoking regulations in the 351 cities and towns in Massachusetts, and to analyse the level of protection from secondhand smoke exposure guaranteed by these regulations. Design: We obtained the local restaurant smoking regulations for each town, analysing them in terms of the protection of restaurant workers, bar workers, and adult and youth restaurant customers. Main outcome measure: The percentage of restaurant patrons and workers and bar workers who are protected from secondhand smoke exposure by the current smoking regulations in Massachusetts. Results: As of June 2002, 225 towns had local restaurant smoking regulations. Of these, 69 (30.7%) do not allow smoking in restaurants, 10 (4.4%) restrict smoking to adult only restaurants, 64 (28.4%) restrict smoking to enclosed, separately ventilated areas, and 82 (36.4%) restrict smoking to areas that need not be enclosed and separately ventilated. Of the 174 towns that, at a minimum, restrict smoking to bar areas or separately ventilated areas, 35 (20.1%) allow variances. Overall, 60 towns, covering only 17.7% of the population, completely ban smoking in restaurants. As a result, 81.3% of adult restaurant customers, 81.2% of youth customers, 82.3% of restaurant workers, and 87.0% of bar workers are not guaranteed protection from secondhand smoke in restaurants. Conclusions: Despite the widespread adoption of local restaurant smoking regulations in Massachusetts, the majority of restaurant customers and workers remain unprotected from secondhand smoke exposure. In light of this, public health practitioners must stop compromising the protection of customers and workers from secondhand smoke exposure in restaurants.     

Performance characteristics of a compact position-sensitive LSO detector module

We assembled a compact detector module comprised of an array of small, individual crystals of lutetium oxyorthosilicate:Ce (LSO) coupled directly to a miniature, metal-can, position-sensitive photomultiplier tube (PSPMT). We exposed this module to sources of 511-keV annihilation radiation and beams of 30- and 140-keV photons and measured spatial linearity; spatial variations in module gain, energy resolution, and event positioning; coincidence timing; the accuracy and sensitivity of identifying the crystal-of-first-interaction at 511 keV; and the effects of intercrystal scatter and LSO background radioactivity. The results suggest that this scintillator/phototube combination should be highly effective in the coincidence mode and can be used, with some limitations, to image relatively low-energy single photon emitters. Photons that are completely absorbed on their first interaction at 511 keV are positioned by the module at the center of a crystal. Intercrystal scatter events, even those that lead to total absorption of the incident photon, are placed by the module in a regular "connect-the-dot" pattern that joins crystal centers. As a result, the accuracy of event positioning can be made to exceed 90%, though at significantly reduced sensitivity, by retaining only events that occur within small regions-of-interest around each crystal center and rejecting events that occur outside these regions in the connect-the-dot pattern.