16 research outputs found
Wide range and tunable linear TMR sensor using two exchange pinned electrodes
A magnetic tunnel junction sensor is proposed, with both the detection and
the reference layers pinned by IrMn. Using the differences in the blocking
temperatures of the IrMn films with different thicknesses, crossed anisotropies
can be induced between the detection and the reference electrodes. The pinning
of the sensing electrode ensures a linear and reversible output. It also allows
tuning both the sensitivity and the linear range of the sensor. The authors
show that the sensitivity varies linearly with the ferromagnetic thickness of
the detection electrode. It is demonstrated that an increased thickness leads
to a rise of sensitivity and a reduction of the operating range
Polarity of T Cell Shape, Motility, and Sensitivity to Antigen
AbstractT cell activation requires contact with APCs. We used optical techniques to demonstrate T cell polarity on the basis of shape, motility, and localized sensitivity to antigen. An intracellular Ca2+ clamp showed that T cell shape and motility are extremely sensitive to changes in [Ca2+]i (Kd = 200 nM), with immobilization and rounding occurring via a calcineurin-independent pathway. Ca2+-dependent immobilization prolonged T cell contact with the antigen-presenting B cell; buffering the [Ca2+]i signal prevented the formation of stable cell pairs. Optical tweezers revealed spatial T cell sensitivity to antigen by controlling placement on the T cell surface of either B cells or α-CD3 MAb-coated beads. T cells were 4-fold more sensitive to contact made at the leading edge of the T cell compared with the tail. We conclude that motile T cells are polarized antigen sensors that respond physically to [Ca2+]i signals to stabilize their interaction with APCs
On the control of spin flop in synthetic antiferromagnetic films
International audienc
Sugar-Based Polyamides: Self-Organization in Strong Polar Organic Solvents
Periodic patterns resembling spirals
were observed to form spontaneously
upon unassisted cooling of d-glucaric acid- and d-galactaric acid–based polyamide solutions in <i>N</i>-methyl-<i>N</i>-morpholine oxide (NMMO) monohydrate. Similar
observations were made in d-galactaric acid-based polyamide/ionic
liquid (IL) solutions. The morphologies were investigated by optical,
polarized light and confocal microscopy assays to reveal pattern details.
Differential scanning calorimetry was used to monitor solution thermal
behavior. Small- and wide-angle X-ray scattering data reflected the
complex and heterogeneous nature of the self-organized patterns. Factors
such as concentration and temperature were found to influence spiral
dimensions and geometry. The distance between rings followed a first-order
exponential decay as a function of polymer concentration. Fourier-Transform
Infrared Microspectroscopy analysis of spirals pointed to H-bonding
between the solvent and the pendant hydroxyl groups of the glucose
units from the polymer backbone. Tests on self-organization into spirals
of ketal-protected d-galactaric acid polyamides in NMMO monohydrate
confirmed the importance of the monosaccharide’s pendant free
hydroxyl groups on the formation of these patterns. Rheology performed
on d-galactaric-based polyamides at high concentration in
NMMO monohydrate solution revealed the optimum conditions necessary
to process these materials as fibers by spinning. The self-organization
of these sugar-based polyamides mimics certain biological materials
A genetically encoded, fluorescent indicator for cyclic AMP in living cells.
Cyclic AMP controls several signalling cascades within cells, and changes in the amounts of this second messenger have an essential role in many cellular events. Here we describe a new methodology for monitoring the fluctuations of cAMP in living cells. By tagging the cAMP effector protein kinase A with two suitable green fluorescent protein mutants, we have generated a probe in which the fluorescence resonance energy transfer between the two fluorescent moieties is dependent on the levels of cAMP. This new methodology opens the way to the elucidation of the biochemistry of cAMP in vivo