Heating and structural alterations in cartilage under laserradiation

The authors have developed a theoretical model to calculate the temperature field and the spatial distribution of modified cartilage following laser irradiation. The model incorporates both thermal and mass transfer in a tissue with bulk absorption of laser radiation, water evaporation from the surfaces of a slab, and temperature dependence of the diffusion coefficient. The authors propose that water undergoes a bound-to-free phase transition in cartilage heated to about 70°C and the mobility of proteoglycan units in the cartilage matrix increases. Movement of the proteoglycan units takes place only when the temperature exceeds 70°C and results in tissue denaturation. Using their model, the authors show: (1) the maximal temperature is reached not on the surface irradiated but rather at some distance below; (2) surface temperature reaches its asymptotic value quicker than the maximal temperature; and (3) the depth of the denatured tissue volume strongly depends on laser fluency, wavelength, exposure time, and cartilage thickness. The model allows for the prediction and control of temperature and depth of structural alterations during the course of laser reshaping and treatment of cartilage     

Luminescent-plasmonic core–shell microspheres,doped with Nd3+ and modified with gold nanoparticles,exhibiting whispering gallery modes and SERS activity

Multifunctional core/shell type,luminescent-plasmonic material composed of lanthanide doped microspheres(≈50 μm) and gold nanoparticles(Au NPs;≈10-20 nm) deposited onto their surface,were successfully prepared(Nd~(3+):YAS@Au).The material was synthesized to combine the luminescence properties of the Nd~(3+)-doped microspheres,i.e.whispering resonance with plasmonic activity of the surface Au NPs,i.e.surface enhanced Raman scattering(SERS) effect,within a single,micro-sized material.The luminescent-plasmonic microspheres were used as the active SERS substrate for detection of the organic probe,and for generation of Whispering Gallery Modes(WGM),which red-shift together with increasing laser power(temperature elevation).The products obtained were analysed with optical,scanning and transmission electron microscopy(SEM and TEM),as well as by Raman,absorption and photoluminescence spectroscopies.     

Migration processes in the glass forming melts of the Na<Subscript>2</Subscript>O–BaO–Ga<Subscript>2</Subscript>O<Subscript>3</Subscript>–SiO<Subscript>2</Subscript> system

The specific conductivity and tracer of diffusion of sodium and barium ions have been determined and the values of the transport numbers and correlation factor for diffusion have been calculated in two melts of the Na₂O–BaO–Ga₂O₃–SiO₂ system.     

Crystallographic data of the ternary compounds RRhGe (R=Gd-Tm) of the TiNiSi-type structure

Investigations made by powder X-ray diffraction on the new ternary TmRhGe compound and already known RRhGe compounds (R=Gd-Er) are reported. They crystallize in the well-known orthorombic TiNiSi-type structure (space group Pnma).     

Sn2P2S6 films for memory devices with nondestructive readout

The polarization switching processes of ferroelectric polycrystalline Sn₂P₂S₆ films on Al substrates were studied. The effect of full reverse spontaneous switching after the influence of a repolarizing pulse on the prepoled sample was investigated. This opens the way for making the ferroelectric memory devices with rapid nondestructive readout.     

Kinetics of structural relaxation in glasses: A hierarchical model of relaxation centers

A definition is proposed for the characteristic time of structural relaxation τ_{str. rel} in metallic glasses—the universal parameter describing the kinetics of various processes associated with the structural relaxation. The behavior of τ_{str. rel} in model situations of isothermal annealing of a glass and its heating at a constant rate is considered. In the former case, the time τ_{str. rel} is equal to the age of the sample. In the latter case, after a time, τ_{str. rel} reaches a steady-state value. This is in agreement with the τ_{str. rel} values determined from the creep rate. The kinetics of structural relaxation is analyzed with due regard for the hierarchical structure of the phase space in glasses. The kinetic equation taking into account this feature is proposed, and the results of its numerical solution are given.