2,930 research outputs found
The Search for an Epoxide Precursor in Trimethylenemethane (TMM) Cycloaddition Reactions
Trimethylenemethane (TMM) cycloaddition is a Pd(0)-catalyzed process in which new carbon rings are formed, which can be potentially useful in synthetic organic processes. The epoxide starting material (trimethyl(2-oxiranyl-2-propenyl)silane) was created in a three-step process from propargyl alcohol. This molecule was subjected to various reaction conditions in order to test the theoretical assumptions of the reaction mechanism. Efforts to characterize the product(s) are ongoing
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Trafficking in Women and Children: The U.S. and International Response - Updated July 10, 2003
CRSdoc2TraffickWomenChildren10July03.pdf: 399 downloads, before Oct. 1, 2020
Trafficking in Women and Children: The U.S. and International Response - Updated March 26, 2004
CRSdoc3traffickingupdateRL30545.pdf: 1142 downloads, before Oct. 1, 2020
Observational Studies of Proto-Planetary Nebulae at the Valparaiso University Observatory
We are observing the light variation with time of a sample of 26 proto-planetary nebulae (PPNe) using Valparaiso University’s 16-inch computer-controlled reflector telescope and CCD digital camera. PPNe are evolved stars late in their lifetime, in between the red giant and planetary nebula phase. The resulting images are analyzed and properly calibrated to produce quantitative measurements of light intensity with respect to time. We are particularly analyzing nine PPNe and their light variations through time to quantify variability and search for periods to their variability. Of the nine, all are variable over a range of 10-50%. Five demonstrate an approximate cyclical variability with preliminary period values of 45-120 days. One is possibly cyclical, and three display short-term variations on the order of a few days. Future studies will refine the current results and attempt to find periodicity to more PPNe
The microflown, from die to product
This article reports on various steps to transform a concept to a product. A sound intensity probe based on a micro-machined acoustic sensor "the Microflown" is used as an example. Requirements for the micromachined part are simplicity and uncomplicated processing to reach a high throughput. For monitoring the quality, simple and reliable characterisation tools should be designed as well. To gain credibility independent labs should test the product. The product should offer a complete solution that competes in overall costs and performance, and it must be possible to connect it into existing systems
Characterizing the Frequency and Seasonal Dependence of the Sea Breeze in Houston, Texas and Its Impact on Surface Ozone
Sea breezes arise from temperature differences between land and an adjacent body of water, forming a thermally direct circulation within the boundary layer. During summer, the resulting circulation carries air offshore during the nighttime and early morning and onshore during the afternoon. Banta et al. [2005] noted the impact of recirculation of pollution on high ozone events in Houston. This study characterizes the frequency of flow reversals that accompany the arrival of sea breeze fronts in Houston and the seasonal dependence of that frequency. Furthermore, we quantitatively analyze the effect of the sea breeze on ozone concentrations in the Houston area
UV Emission line shifts of symbiotic binaries
Relative and absolute emission line shifts have been previously found for
symbiotic binaries, but their cause was not clear. This work aims to better
understand the emission line shifts. Positions of strong emission lines were
measured on archival UV spectra of Z And, AG Dra, RW Hya, SY Mus and AX Per and
relative shifts between the lines of different ions compared. Profiles of lines
of RW Hya and Z And were also examined. The reality of the relative shift
between resonance and intercombination lines of several times ionised atoms was
clearly shown except for AG Dra. This redshift shows a well defined variation
with orbital phase for Z And and RW Hya. In addition the intercombination lines
from more ionised atoms and especially OIV are redshifted with respect to those
from less ionised atoms. Other effects are seen in the profiles. The
resonance-intercombination line shift variation can be explained in quiescence
by P Cygni shorter wavelength component absorption, due to the wind of the cool
component, which is specially strong in inferior conjunction of this cool
giant. The velocity stratification permits absorption of line emission. The
relative intercombination line shifts may be connected with varying occultation
of line emission near an accretion disk, which is optically thick in the
continuum.Comment: 14 pages, 11 figures, to appear in A&
The black silicon method V: a study of the fabrication of movable structure for micro electromechanical systems
This paper presents a study of various well-known release techniques (bulk- and surface-micromachining) for the fabrication of movable silicon micromechanical structures. Their pro's and con's will be discussed. Further, a detailed study of a new self-aligned plasma technique is presented which uses silicon on insulator wafers (SOI). It has the ability to etch, release, and passivate MEMS in one ME run. Therefore, MEMS can be fabricated quickly, accurate, and at low costs
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Trafficking in Women and Children: The U.S. and International Response - Updated August 1, 2001
CRSdoc1TraffickingWomen0801.pdf: 3541 downloads, before Oct. 1, 2020
A microsieve for leukocyte depletion of erythrocyte concentrates
A new ultra thin filtration membrane has been used for leukocyte removal from erythrocyte concentrates. This filtration membrane, an Aquamarijn Microsieve(R), has a high pore density and a narrow pore size distribution and shows good separation behaviour. The low surface roughness of the microsieve will contribute to the biocompatibility and will reduce cell rupture, in particular hemolysis, during filtration. In this paper a brief overview of the effects that occur during filtration will be given. Also the results of the experiments of leukocyte removal from erythrocyte concentrates will be discusse
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