Electromagnetic stimulation on the bone growth using backscattered electron imaging

The events at the hydroxyapatite implant material/tissue interface following electromagnetic stimulation were studied in the rabbit. Two kinds of hydroxyapatite were used: natural (NA) and synthetic (HA) both with a grain size of <50 microm. Bone defects, artificially created in rabbit tibiae, were filled with the material examined. One group of animals was exposed immediately after surgery and every 12h thereafter to 30-min treatments with electromagnetic fields (PEMFs). A second group was used as a control (untreated). Two and 4 weeks after implantation, animals were sacrificed and bone samples processed for LM, TEM and SEM using a backscatter electron detector for the evaluation of bone growth. This study indicates that HA has more osteoconductivity than NA, and shows that PEMF-treatment results in a benefit in accelerating bone formation at early time periods.     

Impedance measurement technique for high-sensitivity cell detection in microstructures with non-uniform conductivity distribution

Particle detection in microstructures is a key procedure required by modern lab-on-a-chip devices. Unfortunately, state of the art approaches to impedance measuring as applied to cell detection do not perform well in regions characterized by non-homogeneous physical parameters due, for example, to the presence of air-liquid interfaces or when the particle-electrode distance is relatively high. This paper presents a robust impedance measurement technique and a circuit for detecting cells flowing in microstructures such as microchannels and microwells. Our solution makes use of an innovative three-electrode measurement scheme with asymmetric polarization in order to increase cell detection ability in microstructures featuring large electrode distances of up to 100 μm as well as to limit signal loss due to cell position relative to the electrodes. Compared to standard techniques, numerical simulations show that, with the proposed approach, the cell detection sensitivity is increased by more than 40%. In addition, we propose a custom circuit based on division instead of difference between signals, as in standard differential circuits, so as to reduce the baseline signal drift induced by non-homogeneous conductivity. A simplified analytical model shows an increase in the signal-to-noise-ratio comprised in the range 3.9-5.9. Experimental results, carried out using an open-microwell device made with flexible printed circuit board technology, are in agreement with simulations, suggesting a six-fold increase of the signal-to-noise ratio compared to the differential measurement technique. We were thus able to successfully monitor the process of isolating K562 leukemia cells inside open-microwells determining all single-cell events with no false positive detection.     

Non-Volatile Threshold Adaptive Transistors with Embedded RRAM

We propose a novel nonvolatile threshold adaptive transistor （TAT） for neuromorphic circuits. The threshold adaptive transistor is achieved by embedding a resistive random-access memory （RRAM） material stack between the gate electrode and gate dielectric. During operation, the embedded RRAM device is kept at a high resistance state, which makes it act as a nonvolatile capacitor. The threshold could be nonlinearly adjusted by the voltage pulses applied on the gate of the transistor. We quantitatively estimate the range of the capacitance variation of the RRAM device. The threshold voltage of the TAT is simulated and shows expected variation. The simulated output of an inverter using a TAT shows a nonlinear adaptive behavior.     

Sharp a priori estimates for div–curl systems in Heisenberg groups

In this paper we prove a family of inequalities for differential forms in Heisenberg groups H¹${\mathbb{H}}^1$ and H²${\mathbb{H}}^2$, that are the natural counterpart of a class of div–curl inequalities in de Rham?s complex proved by Lanzani & Stein and Bourgain & Brezis.     

Faraday’s Form and Maxwell’s Equations in the Heisenberg Group

In this note we present a geometric formulation of Maxwell’s equations in Carnot groups (connected simply connected nilpotent Lie groups with stratified Lie algebra) in the setting of the intrinsic complex of differential forms defined by M. Rumin. Restricting ourselves to the first Heisenberg group \mathbbH¹{\mathbb{H}^{1}}, we show that these equations are invariant under the action of suitably defined Lorentz transformations, and we prove the equivalence of these equations with differential equations “in coordinates”. Moreover, we analyze the notion of “vector potential”, and we show that it satisfies a new class of 4th order evolution differential equations.     

First characterisation of rotational conformers in a chiral nitroxide by EPR spectroscopy

The detection and characterisation in liquid solution by EPR spectroscopy of the rotational conformers of a nitroxide radical containing a chiral centre is reported for the first time.     

Carrier recombination dynamics in self-ordered InAs quantum dots

Il Nuovo Cimento D - A photoluminescence study of self-ordered InAs quantum dots grown by molecular beam epitaxy on a GaAs substrate is reported. Short pulses and high excitations have been used in...     

“One pot” synthesis of 2-substituted 9-(2′-hydroxy-3′-aminopropyl)-8-azahypoxanthines and 8-azaadenines (5-substituted 3-(2′-hydroxy-3′-aminopropyl) 7-amino and 7-hydroxy-3H-1,2,3-triazolo[4,5-d]pyrimidines)

An example of the generalization of the synthesis of 8-azahypoxanthines A and 8-azaadenines B , interesting from a medicinal point of view, is presented by utilizing l-amino-2-hydroxy-3-azidopropanes.     

High-performance liquid chromatographic determination of morphine in biological samples: an overview of separation methods and detection techniques

High-performance liquid chromatogrpahy with electrochemical detection at present suits most of the needs of toxicologists for the determination of morphine and some related compounds in biological samples, although fluorescence detection is still a useful alternative. Chemiluminescence detection may be promising, but needs further optimization of its coupling with HPLC to give the best performances. Morphine detection by absorbance spectrophotometry does not seem to allow the degree of sensitivity and selectivity from matrix interferences that is required in most instances. However, this approach is useful when morphine congeners undetectable by alternative means (i.e., heroin and morphine-3-glucuronide) are to be determined or when a general toxicological screening is required.