Cryogenic and hermetically sealed packaging of photonic chips for optomechanics.

We demonstrate a hermetically sealed packaging system for integrated photonic devices at cryogenic temperatures with plug-and-play functionality. This approach provides the ability to encapsulate a controlled amount of gas into the optical package allowing helium to be used as a heat-exchange gas to thermalize photonic devices, or condensed into a superfluid covering the device. This packaging system was tested using a silicon-on-insulator slot waveguide resonator which fills with superfluid 4He below the transition temperature. To optimize the fiber-to-chip optical integration 690 tests were performed by thermally cycling optical fibers bonded to various common photonic chip substrates (silicon, silicon oxide and HSQ) with a range of glues (NOA 61, NOA 68, NOA 88, NOA 86H and superglue). This showed that NOA 86H (a UV curing optical adhesive with a latent heat catalyst) provided the best performance under cryogenic conditions for all the substrates tested. The technique is relevant to superfluid optomechanics experiments, as well as quantum photonics and quantum optomechanics applications.

Sorption of volatile organic compounds on typical carpet fibers.

Measurements of adsorption isotherms for three volatile organic compounds (VOCs) (toluene, 1,2-dichlorobenzene and 1,1,1-trichloroethane) on polyacrylonitrile carpet fibers over the temperature range 25-45 degrees C were carried out in a thermogravimetric analyzer (TGA). Linear isotherms were observed in all cases with values of the Henry coefficient ranging from 0.063 to 0.941 mm. The results of additional experiments carried out in a simple test chamber containing a single source of VOC showed that the carpet fibers acted as a significant sink causing a prolonged elevation of VOC concentration in the air within the chamber. An unsteady-state model is presented, which adequately described the adsorption and desorption phenomena occurring in the test chamber and yielded realistic values of the adsorption and desorption rate constants. There was good agreement between the equilibrium and kinetic constants obtained in the TGA and test chamber experiments.

Energy-selective filtration of dental x-ray beams.

Samarium is known for its ability to filter simultaneously low- and high-energy x-ray photons from an x-ray beam that are not useful in producing a diagnostic radiograph. This study was undertaken to determine the optimum thickness of samarium required to minimize patient exposure and exposure time. The results indicate that use of a filter thickness of 0.16 mm. minimized patient radiation exposure and permitted the use of an exposure time sufficiently short to minimize motion unsharpness. The incorporation of a 0.16 mm. samarium filter in the x-ray beam reduced exposure by about 40 percent as compared to a 2.5 mm. aluminum filter; the exposure time must be increased approximately twice to obtain optical densities equivalent to those produced with aluminum filtration.

Geroderma osteodysplastica. A report of two affected families.

This paper describes two families in which four boys and two girls were affected with geroderma osteodysplastica. The major features of this syndrome include a droopy, jowly, prematurely aged appearance that has been likened by previous authors to the dwarfs in Walt Disney's 'Snow White.' Also, their skin lacks normal elastic recoil. The bones are osteoporotic and susceptible to fractures, particularly the vertebrae, which show compression with anterior wedging and biconcavity. The findings in the present families are compared with those in the originally reported family. There was a high degree of consanguinity between the parents in both of the present families and the previous hypothesis of X-linked inheritance is questioned.

"Malignant disease in the jaws".

Radiologic interpretation of malignant disease of the oral cavity, maxilla and mandible is often difficult. This is usually due to the fact that benign osseous diseases may mimic malignant lesions. This review attempts to provide a framework of interpretive criteria for establishing a radiologic diagnosis of malignancy.