MOEMS chip-level optical fiber interconnect

A package design, fabrication process, and assembly process to hermetically seal the microstructure area of a microoptoelectromechanical system (MOEMS) at the chip level is presented and evaluated. The packaged chip is fabricated using the Bosch deep reactive ion etching (DRIE) process on silicon on insulator (SOI) substrates. The packaging structures are formed during the batch fabrication of the MOEMS device. A hermetic seal is formed via an indium solder ring around the perimeter of the MOEMS chip that span channels etched in the silicon for optical fibers. The seal is made between the device chip, metallized optical fibers, and a cap chip with a fluxless soldering process. The integrity of the package is evaluated through die shear, fiber pull, and highly accelerated life testing (HALT).     

Vascular MADs: two novel MAD-related genes selectively inducible by flow in human vascular endothelium

Vascular endothelium is an important transducer and integrator of both humoral and biomechanical stimuli within the cardiovascular system. Utilizing a differential display approach, we have identified two genes, Smad6 and Smad7, encoding members of the MAD-related family of molecules, selectively induced in cultured human vascular endothelial cells by steady laminar shear stress, a physiologic fluid mechanical stimulus. MAD-related proteins are a recently identified family of intracellular proteins that are thought to be essential components in the signaling pathways of the serine/threonine kinase receptors of the transforming growth factor beta superfamily. Smad6 and Smad7 possess unique structural features (compared with previously described MADs), and they can physically interact with each other, and, in the case of Smad6, with other known human MAD species, in endothelial cells. Transient expression of Smad6 or Smad7 in vascular endothelial cells inhibits the activation of a transfected reporter gene in response to both TGF-beta and fluid mechanical stimulation. Both Smad6 and Smad7 exhibit a selective pattern of expression in human vascular endothelium in vivo as detected by immunohistochemistry and in situ hybridization. Thus, Smad6 and Smad7 constitute a novel class of MAD-related proteins, termed vascular MADs, that are induced by fluid mechanical forces and can modulate gene expression in response to both humoral and biomechanical stimulation in vascular endothelium.     

NOTE ON THE VAPOR ABSORPTION OF A FIRED EARTHENWARE BODY1

Specimens of an earthenware body fired at three temperatures were placed over a 10% sulphuric acid solution for 36 days and the gain in weight determined. Up to a certain limit of porosity the absorption is proportional to the porosity, but the body with the highest absorption, 20.25% took up a relatively higher amount of water. With an absorption of 8.81%, the maximum amount of water vapor taken up was 0.13%. With 10.8% absorption the water vapor taken up was 0.16 and with 20.25% absorption it reached 0.54%.     

Application of classification trees in the sensitivity analysis of probabilistic model results

The complexity of some integrated-system models necessitates using a probabilistic approach to quantify uncertainty in model projections. In this work, we demonstrate how classification trees can be used to perform sensitivity analyses on probabilistic results. The classification tree technique is applied to results from the probabilistic total system performance assessment model used in the Yucca Mountain project. The technique proves effective in delineating the variables that most influence low and high outcomes.     

Reliability assessment of delamination in chip-to-chip bonded MEMS packaging

The bond layer is often the weakest link in the reliability of chip packages in the integrated circuit (IC) industry. Micro-electrical-mechanical systems (MEMS) packages are no exception to this trend. This paper presents a nondestructive methodology for determining delamination in chip-to-chip bonded MEMS. Experimental methods are used to determine the adhesive layer strength in samples subjected to environmental testing, and the reliability of the bonding layer is investigated. A simulation is performed using inputs from scanning acoustic microscopy, and simulation model results are correlated with the experimental die shear measurements to establish the validity of the nondestructive methodology for determining adhesive layer strength.     

A QUICK METHOD OF DETERMINING THE WATER CONTENT OF CLAYS1

The water content of clay is determined by taking a representative sample of the material, weighing out 2 kg. of it and adding 4 kg. of water. The sample is blunged quickly. A 250-cc. flask is filled with the resulting slip and weighed. The amount of dry clay is determined from the relation: D= (P−250)(G/G−1) where D= weight of dry clay P= weight of slip G= specific gravity of dry clay. From this the per cent water in the moist clay is readily computed.     

Difluoromethane as Partitioning Tracer to Estimate Vadose Water Saturations

Water saturation in the vadose zone is an important parameter for many nonaqueous phase liquid (NAPL) remediation technologies. Conventional soil boring analyses may not provide accurate average water saturation data. Previous studies have shown that a partitioning interwell tracer test (PITT) can provide an accurate estimate of average subsurface NAPL saturations. The PITT is proposed as a suitable technology for estimating average subsurface water saturations. In this research, difluoromethane was evaluated as a suitable tracer compound to partition among air, water, and NAPL phases. Method of moments analyses were used to develop equations necessary to determine water saturations from difluoromethane PITT results. One-dimensional column experiments provided air-water and air-NAPL partition coefficient data for difluoromethane. Difluoromethane is shown to be a suitable tracer for use in field PITTs to predict water saturations in the vadose zone.     

Contaminated Vadose Zone Characterization Using Partitioning Gas Tracers

This paper describes laboratory research conducted to investigate the performance of partitioning tracers for the detection of nonaqueous-phase liquids (NAPLs) in vadose zones. Once evaluated, the tracers may be used for volume estimation of NAPLs and remediation performance assessment of vadose zones. These laboratory studies used glass chromatography columns packed with: (1) Ottawa sand; and then (2) in a separate experiment, soil extracted from the Chemical Waste Landfill at Sandia National Laboratories. The columns were prepared in a manner that resulted in a three-phase system of air, water, and NAPL in the columns. Conservative and partitioning gas tracers were injected into the columns, and their elution concentrations were analyzed. The method of moments was used to estimate partition coefficients between the air and NAPL phases for each of the tracers. The partition coefficients and retardation factors, also estimated during the study, are used to select appropriate tracers for NAPL detection. This research identified several suitable perfluorocarbon tracers and demonstrated the feasibility of using partitioning tracers as a tool for NAPL detection in the vadose zone.