WIRELESS AND BATTERYLESS SURFACE ACOUSTIC WAVE SENSORS FOR HIGH TEMPERATURE ENVIRONMENTS

International audienceSurface acoustic wave (SAW) devices are widely used as filter, resonator or delay line in electronic systems in a wide range of applications: mobile communication, TVs, radar, stable resonator for clock generation, etc. The resonance frequency and the delay line of SAW devices are depending on the properties of materials forming the device and could be very sensitive to the physical parameters of the environment. Since SAW devices are more and more used as sensor for a large variety of area: gas, pressure, force, temperature, strain, radiation, etc. The sensors based SAW present the advantage to be passive (batteryless) and/or wireless. These interesting properties combined with a small size, a low cost radio request system and a small antennas when operating at high frequency, offer new and exiting perspectives for wireless measurement processes and IDTAG applications. When the materials constituting the devices are properly selected, it becomes possible to use those sensors without embedded electronic in hostile environments (as high temperature, nuclear site, …) where no solutions are currently used. General principle of the SAW sensor in wired and wireless configurations will be developed and a review of recent works concerning the field of high temperature applications will be presented with specific attention given to the choice of materials constituting the SAW device

NPY Y1 receptor is not involved in the hemodynamic response to an acute cold pressor test in mice

The vasoconstrictor neuropeptide Y (NPY) has been shown to down-regulate tyrosine hydroxylase expression in cultured adrenal chromaffin cells, which probably accounts for the higher plasma resting norepinephrine (NE) and epinephrine (E) concentrations observed in Y1 knock-out mice (Y1-/-) than in wild-type mice (Y1+/+). The aim of this work was to study the hemodynamic response of Y1-/- mice to an acute stimulation of the sympathetic nervous system (cold pressor test, CPT). Plasma catecholamine concentrations were higher in Y1-/- mice than in wild-type animals at the end of the CPT. The CPT-induced increase in mean arterial blood pressure (MAP) and heart rate (HR) was similar in both genotypes. Independently of the genotype, females had significantly slower HR than males throughout the 15 min duration of the CPT. There was no difference in the sensitivity of the baroreceptor reflex, as reflected by the change in HR divided by the concurrent change in MBP between Y1-/- and Y1+/+ mice. In conclusion, mice lacking the Y1 receptor can maintain normal hemodynamic response to an acute activation of the sympathetic system, albeit at the expense of increased catecholamine discharge.http://www.sciencedirect.com/science/article/B6T0M-4MT54Y4-3/1/f346666c9ec021eeffb80529f17474d

Impaired Interleukin-1β and c-Fos Expression in the Hippocampus Is Associated with a Spatial Memory Deficit in P2X7 Receptor-Deficient Mice

Recent evidence suggests that interleukin-1β (IL-1β), which was originally identified as a proinflammatory cytokine, is also required in the brain for memory processes. We have previously shown that IL-1β synthesis in the hippocampus is dependent on P2X7 receptor (P2X7R), which is an ionotropic receptor of ATP. To substantiate the role of P2X7R in both brain IL-1β expression and memory processes, we examined the induction of IL-1β mRNA expression in the hippocampus of wild-type (WT) and homozygous P2X7 receptor knockout mice (P2X7R−/−) following a spatial memory task. The spatial recognition task induced both IL-1β mRNA expression and c-Fos protein activation in the hippocampus of WT but not of P2X7R−/− mice. Remarkably, P2X7R−/− mice displayed spatial memory impairment in a hippocampal-dependant task, while their performances in an object recognition task were unaltered. Taken together, our results show that P2X7R plays a critical role in spatial memory processes and the associated hippocampal IL-1β mRNA synthesis and c-Fos activation

Pharmacokinetics of midazolam in CYP3A4- and CYP3A5-genotyped subjects

Objective: We investigated whether differences in pharmacokinetics of midazolam, a CYP3A probe, could be demonstrated between subjects with different CYP3A4 and CYP3A5 genotypes. Methods: Plasma concentrations of midazolam, and of total (conjugated + unconjugated) 1′OH-midazolam, and 4′OH-midazolam were measured after the oral administration of 7.5mg or of 75µg of midazolam in 21 healthy subjects. Results: CYP3A5*7, CYP3A4*1E, CYP3A4*2, CYP3A4*4, CYP3A4*5, CYP3A4*6, CYP3A4*8, CYP3A4*11, CYP3A4*12, CYP3A4*13, CYP3A4*17 and CYP3A4*18 alleles were not identified in the 21 subjects. CYP3A5*3, CYP3A5*6, CYP3A4*1B and CYP3A4*1F alleles were identified in 20, 1, 4 and 2 subjects, respectively. No statistically significant differences were observed for the AUCinf values between the different genotypes after the 75-µg or the 7.5-mg dose. Conclusion: Presently, CYP3A4 and CYP3A5 genotyping methods do not sufficiently reflect the inter-individual variability of CYP3A activit

Study of tantalum and iridium as adhesion layers for Pt/LGS high temperature SAW devices

International audienceIn this paper, we report on the use of tantalum and iridium as adhesion layers for platinum electrodes used in high temperature SAW devices based on langasite substrates (LGS). Unlike iridium, tantalum exhibits a great adhesive strength, and a very low mobility through the Pt film, ensuring a device lifetime of at least half an hour at 1000°C. The latter is limited by morphological modifications of platinum, starting by the apparition of crystallites on the surface, and followed by important terracing and breaking of the film continuity. SNMS and XRD measurements allowed us to show that these phenomena are likely intrinsic to platinum film, whatever be the nature of the adhesion layer. Finally, after having outlined a possible scenario leading to this deterioration, we consider some solutions that could replace platinum in order to increase the lifetime of LGS-based SAW devices in high temperatures conditions

On the motivations for Merleau-Ponty’s ontological research

This paper attempts to clarify Merleau-Ponty’s later work by tracing a hitherto overlooked set of concerns that were of key consequence for the formulation of his ontological research. I argue that his ontology can be understood as a response to a set of problems originating in reflections on the intersubjective use of language in dialogue, undertaken in the early 1950s. His study of dialogue disclosed a structure of meaning-formation and pointed towards a theory of truth (both recurring ontological topics) that post-Phenomenology premises could not account for. A study of dialogue shows that speakers’ positions are interchangeable, that speaking subjects are active and passive in varying degrees, and that the intentional roles of subjects and objects are liable to shift or ‘transgress’ themselves. These observations anticipate the concepts of ‘reversibility’ and ‘narcissism’, his later view of activity and passivity, and his later view of intentionality, and sharpened the need to adopt an intersubjective focus in ontological research

Oral administration of a low dose of midazolam (75μg) as an in vivo probe for CYP3A activity

Objective: We investigated whether the oral administration of a low dose (75µg) of midazolam, a CYP3A probe, can be used to measure the in vivo CYP3A activity. Methods: Plasma concentrations of midazolam, 1′OH-midazolam and 4′OH-midazolam were measured after the oral administration of 7.5mg and 75µg midazolam in 13 healthy subjects without medication, in four subjects pretreated for 2days with ketoconazole (200mg b.i.d.), a CYP3A inhibitor, and in four subjects pretreated for 4days with rifampicin (450mg q.d.), a CYP3A inducer. Results: After oral administration of 75µg midazolam, the 30-min total (unconjugated + conjugated) 1′OH-midazolam/midazolam ratios measured in the groups without co-medication, with ketoconazole and with rifampicin were (mean±SD): 6.23±2.61, 0.79±0.39 and 56.1±12.4, respectively. No side effects were reported by the subjects taking this low dose of midazolam. Good correlations were observed between the 30-min total 1′OH-midazolam/midazolam ratio and midazolam clearance in the group without co-medication (r2=0.64, P<0.001) and in the three groups taken together (r2=0.91, P<0.0001). Good correlations were also observed between midazolam plasma levels and midazolam clearance, measured between 1.5h and 4h. Conclusion: A low oral dose of midazolam can be used to phenotype CYP3A, either by the determination of total 1′OH-midazolam/midazolam ratios at 30min or by the determination of midazolam plasma levels between 1.5h and 4h after its administratio