Stable hysteretic reflection of light at a nonlinear interface

We have observed a hysteretic (bistable) reflection of a Gaussian laser beam at the interface between glass and a liquid solution of polystyrene microspheres as nonlinear medium with both branches of the hysteretic curve being stable, in contrast to the results of previous experiments.     

Laser heating of optically thin samples

Summary A mathematical model able to describe the temperature profiles generated in a thin film by the steady-state illumination by a Gaussian laser beam is presented. The film is supposed to be made by a weakly absorbing liquid sample bounded by two parallel transparent plates, the cell walls, whose thermal exchange to the surrounding ambient may be assumed to be linear with the temperature difference. An analytical solution of the problem is presented in form of Hankel transform and a matrix numerical approach to the computation of the temperature profiles is reported. It is particularly well suited to a computer implementation and allows one to get very accurate results in very short computing times. The influence of the heat exchange coefficient to the ambient is shown in an example. A check of the method accuracy is performed by comparison with literature results in the particular case of infinite heat exchange coefficient. To speed up publication, the authors of this paper have agreed to not receive the proofs for correction.     

Laser induced thermal profiles in thermally and optically thin films

The temperature field generated by the weak absorption of a gaussian laser beam in an optically and thermally thin film bounded by two transparent plates is discussed. An analytical solution of the problem is presented together with an algorithm for the numerical integration. The influence of the finite thermal conductivity of the plates is shown in an example.     

Diffraction patterns of laser beams with thermal self-phase modulation by optically thin films

Summary A mathematical model of the far-field diffraction pattern of a laser beam with laser heating self-phase modulation through an optically thin film is presented. We deal with the steady-state temperature field generated by the weak absorption of a laser beam in an optically and thermally thin film bounded by two transparent plates, the cell walls, whose thermal exchange to the surrounding ambient has been assumed to be linear in the temperature difference to the ambient. These hypotheses describe the application of the steady-state ?thermal lens? spectroscopy to the detection of the optical or thermal properties of liquid samples. We give a very simple expression for the diffracted intensity that appears suitable for fast computer calculations. The good accuracy of the technique is shown by comparison with the results given by more intricate approaches. To speed up publication, the authors of this paper have agreed to not receive the proofs for correction.     

Photoacoustic monitoring of damage in ion implanted and annealed si layers

The photoacoustic technique has been used to characterize ion implanted Si layers, as a function of the implantation conditions of ion dose and energy and of thermal annealing conditions, through the determination of the material thermal conductivity and optical absorption coefficient. It was found that the technique can discriminate between amorphous material obtained under different implantation conditions. Regarding the annealed samples, different results have been obtained for amorphous as-implanted, fine grain polycrystalline, highly defective single crystalline and defect-free single crystalline materials.     

Anti-Inflammatory Activity of a CB2 Selective Cannabinoid Receptor Agonist: Signaling and Cytokines Release in Blood Mononuclear Cells

The endocannabinoid system (ECS) exerts immunosuppressive effects, which are mostly mediated by cannabinoid receptor 2 (CBR2), whose expression on leukocytes is higher than CBR1, mainly localized in the brain. Targeted CBR2 activation could limit inflammation, avoiding CBR1-related psychoactive effects. Herein, we evaluated in vitro the biological activity of a novel, selective and high-affinity CBR2 agonist, called JT11, studying its potential CBR2-mediated anti-inflammatory effect. Trypan Blue and MTT assays were used to test the cytotoxic and anti-proliferative effect of JT11 in Jurkat cells. Its pro-apoptotic activity was investigated analyzing both cell cycle and poly PARP cleavage. Finally, we evaluated its impact on LPS-induced ERK1/2 and NF-kB-p65 activation, TNF-α, IL-1β, IL-6 and IL-8 release in peripheral blood mononuclear cells (PBMCs) from healthy donors. Selective CB2R antagonist SR144528 and CBR2 knockdown were used to further verify the selectivity of JT11. We confirmed selective CBR2 activation by JT11. JT11 regulated cell viability and proliferation through a CBR2-dependent mechanism in Jurkat cells, exhibiting a mild pro-apoptotic activity. Finally, it reduced LPS-induced ERK1/2 and NF-kB-p65 phosphorylation and pro-inflammatory cytokines release in human PBMCs, proving to possess in vitro anti-inflammatory properties. JT11 as CBR2 ligands could enhance ECS immunoregulatory activity and our results support the view that therapeutic strategies targeting CBR2 signaling could be promising for the treatment of chronic inflammatory diseases.     

Growth and characterization of infinite-layer films deposited by pulsed-laser deposition

Summary The increasing interest for infinite-layer materials is due essentially to the possibility of studying the simplest high-T _c superconductors parent structure. The usual method to produce this material is high-pressure synthesis. In this paper we report on this new material deposited by pulsed laser deposition and on the possibility to create infinite-layer superconducting films. Paper presented at the ?VII Congresso SATT?, Torino, 4–7 October 1994.     

Simultaneous heat capacity and thermal-diffusivity photoacoustic measurement at liquid-crystal phase transitions

Summary The photoacoustic-technique application to the simultaneous characterization of the thermal diffusivity, specific-heat capacity and thermal conductivity of a liquid crystal at a phase transition is presented for the first time. The first two parameters show a critical decrease and increase, respectively, while the third one does not exhibit any critical behaviour. To speed up publication, the authors of this paper have agreed to not receive the proofs for correction.     

Nonlinear absorption in ionic crystals determined by pulsed photothermal deflection

Intensity-induced nonlinear absorption in several ionic crystals have been investigated at 308 nm by pulsed phototermal deflection in the prebreakdown region. The main mechanism of energy deposition is two or three photon absorption.     

Simultaneous determination of specific heat,thermal conductivity and thermal diffusivity at low temperature via the photopyroelectric technique

The photopyroelectric effect has been used to measure simultaneously specific heat (c), thermal conductivity (k) and thermal diffusivity () at low temperatures. A calibration procedure which allows the use of a pyroelectric transducer at low temperatures is described. Simultaneous measurements of c, k, and over a high T _c superconducting phase transition are reported.