518 research outputs found
Load sensing surgical instruments
Force and pressure sensing technology applied to smart surgical instruments as well as implants allow to give a direct feedback of loads to the surgeon lead to better reliability and success of surgical operations. A common technology used for sensors is low-cost piezoresistive thick-film technology. However, the standard thick-film firing conditions degrade the properties of medical alloys. In order to avoid this problem, the solution is to decrease the firing temperature of thick films. This work presents the development and characterisation of low-firing thick-film systems (dielectrics, resistors and conductors), formulated to achieve chemical and thermal expansion compatibility with an austenitic stainless steel medical alloy. Adherence tests and results on electrical properties of these systems: resistance, temperature coefficient of resistance (TCR) are presented. It was found that the main issue in these systems lies in mastering the materials interactions during firing, especially at the silver-based resistor terminations. The interaction of silver, resistor and dielectric tends to give rise to highly resistive zones at the terminations, affecting reliability. This can be circumvented by post-firing the resistor terminations at a moderate temperatur
Sensors and packages based on LTCC and thick-film technology for severe conditions
Reliable operation in harsh environments such as high temperatures, high pressures, aggressive media and space, poses special requirements for sensors and packages, which usually cannot be met using polymer-based technologies. Ceramic technologies, especially LTCC (Low-Temperature Cofired Ceramic), offer a reliable platform to build hermetic, highly stable and reliable sensors and packages. This is illustrated in the present work through several such devices. The examples are discussed in terms of performance, reliability, manufacturability and cost issue
Ultra-low pressure sensor for neonatal resuscitator
AbstractA Venturi-type flow sensor has been designed and fabricated for neonatal respiratory assistance to control airway pressure and tidal volume. As the low flow range and sensing principle require the measurement of correspondingly very low pressures, a very responsive sensor, based on a polymer membrane acting onto a piezoresistive cantilever force sensor based on low-temperature co-fired ceramic (LTCC), was developed. This paper details the 3D modelling, manufacture, assembly and characterisation of the sensor. Compared to expensive and fragile MEMS-based devices, this sensor, based on LTCC, thick-film technology and polymer parts, provides an accurate and robust, yet low-cost alternative
The Water Vapor Abundance in Orion KL Outflows
We present the detection and modeling of more than 70 far-IR pure rotational
lines of water vapor, including the 18O and 17O isotopologues, towards Orion
KL. Observations were performed with the Long Wavelength Spectrometer
Fabry-Perot (LWS/FP; R~6800-9700) on board the Infrared Space Observatory (ISO)
between ~43 and ~197 um. The water line profiles evolve from P-Cygni type
profiles (even for the H2O18 lines) to pure emission at wavelengths above ~100
um. We find that most of the water emission/absorption arises from an extended
flow of gas expanding at 25+-5 kms^-1. Non-local radiative transfer models show
that much of the water excitation and line profile formation is driven by the
dust continuum emission. The derived beam averaged water abundance is
2-3x10^-5. The inferred gas temperature Tk=80-100 K suggests that: (i) water
could have been formed in the "plateau" by gas phase neutral-neutral reactions
with activation barriers if the gas was previously heated (e.g. by shocks) to
>500 K and/or (ii) H2O formation in the outflow is dominated by in-situ
evaporation of grain water-ice mantles and/or (iii) H2O was formed in the
innermost and warmer regions (e.g. the hot core) and was swept up in ~1000 yr,
the dynamical timescale of the outflow.Comment: Accepted for publication in ApJ letters [2006 August 7] (5 pages 2,
figures, not edited
Detection of water at z = 0.685 towards B0218+357
We report the detection of the H_2O molecule in absorption at a redshift z =
0.68466 in front of the gravitationally lensed quasar B0218+357. We detect the
fundamental transition of ortho-water at 556.93 GHz (redshifted to 330.59 GHz).
The line is highly optically thick and relatively wide (15 km/s FWHM), with a
profile that is similar to that of the previously detected CO(2--1) and
HCO^+(2--1) optically thick absorption lines toward this quasar. From the
measured level of the continuum at 330.59 GHz, which corresponds to the level
expected from the power-law spectrum already
observed at lower frequencies, we deduce that the filling factor of the H_2O
absorption is large. It was already known from the high optical thickness of
the CO, ^{13}CO and C^{18}O lines that the molecular clouds entirely cover one
of the two lensed images of the quasar (all its continuum is absorbed); our
present results indicate that the H_2O clouds are covering a comparable
surface. The H_2O molecules are therefore not confined to small cores with a
tiny filling factor, but are extended over parsec scales. The H_2O line has a
very large optical depth, and only isotopic lines could give us the water
abundance. We have also searched for the 183 GHz line in absorption, obtaining
only an upper limit; this yields constraints on the excitation temperature.Comment: 4 pages, 3 figures, accepted in ApJ Letter
Selective Methylation of Arenes: A Radical CâH Functionalization/CrossâCoupling Sequence
A selective, nonchelationâassisted methylation of arenes has been developed. The overall transformation, which combines a CâH functionalization reaction with a nickelâcatalyzed crossâcoupling, offers rapid access to methylated arenes with high para selectivity. The reaction is amenable to lateâstage methylation of smallâmolecule pharmaceuticals
TIMASSS : The IRAS16293-2422 Millimeter And Submillimeter Spectral Survey: Tentative Detection of Deuterated Methyl Formate (DCOOCH3)
High deuterium fractionation is observed in various types of environment such
as prestellar cores, hot cores and hot corinos. It has proven to be an
efficient probe to study the physical and chemical conditions of these
environments. The study of the deuteration of different molecules helps us to
understand their formation. This is especially interesting for complex
molecules such as methanol and bigger molecules for which it may allow to
differentiate between gas-phase and solid-state formation pathways. Methanol
exhibits a high deuterium fractionation in hot corinos. Since CH3OH is thought
to be a precursor of methyl formate we expect that deuterated methyl formate is
produced in such environments. We have searched for the singly-deuterated
isotopologue of methyl formate, DCOOCH3, in IRAS 16293-2422, a hot corino
well-known for its high degree of methanol deuteration. We have used the
IRAM/JCMT unbiased spectral survey of IRAS 16293-2422 which allows us to search
for the DCOOCH3 rotational transitions within the survey spectral range (80-280
GHz, 328-366 GHz). The expected emission of deuterated methyl formate is
modelled at LTE and compared with the observations.} We have tentatively
detected DCOOCH3 in the protostar IRAS 16293-2422. We assign eight lines
detected in the IRAM survey to DCOOCH3. Three of these lines are affected by
blending problems and one line is affected by calibration uncertainties,
nevertheless the LTE emission model is compatible with the observations. A
simple LTE modelling of the two cores in IRAS 16293-2422, based on a previous
interferometric study of HCOOCH3, allows us to estimate the amount of DCOOCH3
in IRAS 16293-2422. Adopting an excitation temperature of 100 K and a source
size of 2\arcsec and 1\farcs5 for the A and B cores, respectively, we find that
N(A,DCOOCH3) = N(B,DCOOCH3) ~ 6.10^14 /cm2. The derived deuterium fractionation
is ~ 15%, consistent with values for other deuterated species in this source
and much greater than that expected from the deuterium cosmic abundance.
DCOOCH3, if its tentative detection is confirmed, should now be considered in
theoretical models that study complex molecule formation and their deuteration
mechanisms. Experimental work is also needed to investigate the different
chemical routes leading to the formation of deuterated methyl formate
Large Scale In Silico Screening on Grid Infrastructures
Large-scale grid infrastructures for in silico drug discovery open
opportunities of particular interest to neglected and emerging diseases. In
2005 and 2006, we have been able to deploy large scale in silico docking within
the framework of the WISDOM initiative against Malaria and Avian Flu requiring
about 105 years of CPU on the EGEE, Auvergrid and TWGrid infrastructures. These
achievements demonstrated the relevance of large-scale grid infrastructures for
the virtual screening by molecular docking. This also allowed evaluating the
performances of the grid infrastructures and to identify specific issues raised
by large-scale deployment.Comment: 14 pages, 2 figures, 2 tables, The Third International Life Science
Grid Workshop, LSGrid 2006, Yokohama, Japan, 13-14 october 2006, to appear in
the proceeding
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