Dental biothermophotonics: How photothermal methods are winning the race with X-rays for dental caries diagnostic needs of clinical dentistry

Recent trends in biothermophotonics of teeth are presented. The presentation is centered on the development of clinical-level frequency-domain photothermal radiometry and modulated luminescence to address issues associated with the early diagnosis of demineralization caries in human teeth. Biothermophotonic principles and applications to the detection of the carious state in human teeth as embodied by laser photothermal radiometry are presented and further supported by modulated luminescence. The emphasis is on recent developments with regard to abilities of these techniques to diagnose interproximal lesions between teeth, etching with phosphoric acid and with an artificial demineralization gel in order to simulate early demineralization, as well as demineralization and remineralization of dental crown enamel and root dentin. These are lesions which normally go undetected by X-ray radiographs. Comparisons with X rays, Micro-Computed Tomography (μ-CT) and Transverse Micro-Radiography (TMR) are discussed. A theoretical model involving coupled diffuse photon density and thermal-wave fields is developed and applied to frequency scans from demineralized artificial lesions to produce quantitative values for optical and thermophysical parameters of teeth as well as the thickness of the induced lesion.     

Ultrasonic measurement of dental enamel demineralization

The DONAR (digital ultrasonic system) has been used to continuously measure the displacement, due to etching by hydrochloric acid, of the surface of bovine enamel and to monitor the development of a demineralized layer. Conventional pulse echoes are used to measure displacements of the order of micrometres with an uncertainty no greater than 0.1 μm. The demineralized zone in one instance attained a maximum thickness of 5 μm and was much less in other experiments.     

双层材料光热偏转光谱的定量研究

从三线传热方程出发,给出了双层材料的光热偏转光谱的理论模型,讨论了光热偏转信号的特征及其在扫描成象应用中的意义.     

A two-layer model of laser interaction with skin: A photothermal effect analysis

In order to understand the photothermal effect mechanism of laser interaction with skin, we employed a two-layer model to describe the heat generation, transportation, and dispersion in the procedure of laser interaction with skin. A skin temperature distribution corresponding to the laser interaction direction is calculated to describe the time of skin gasification and the possible thermal injury. The magnitude of time is ms. This basic process provides a possible quantitative recognition of the applications of laser in clinical skin care.     

X-ray excited photoelectron spectra of LiNbO3: A quantitative analysis

X-ray excited photoelectron spectra (XPS) using monochromatized Al — K radiation ( =1,486.7 eV) have been analysed quantitatively. The intensities of the various core lines (Li(1s), O(1s), O(2s), Nb(3s), Nb(3p), Nb(3d), Nb(4s), Nb(4p)) normalized to the intensity of the Nb (3d _5/2)-line, show good agreement with those calculated with theoretical values for the photoabsorption cross section of the free atoms and the theoretical estimates of the dependance of the electron escape depth on the electron kinetic energy. From the energy loss spectra observed at the high binding energy side of the XPS core lines the energy loss function Im {–1/()} is calculated and compared to published optical data. This comparison yields directly the total electron escape depth as function of the electron energy over a large energy range.     

A simple theoretical extension to the analysis of photothermal deflection signal for low thermal diffusivity evaluation

A modified amplitude method to analyze the photothermal probe beam deflection signal for the determination of low thermal diffusivity values of materials is proposed. This simple theoretical model, which is an extension of the amplitude method proposed by Quelin et al., takes into account the dependence of the photothermal signal on the height of the probe beam above the sample surface which affects mirage measurements when the thermal diffusivity of the coupling medium is greater than that of the sample. The present work is similar to the modification to the phase method proposed by Bertolotti et al. for determination of low thermal diffusivity. The method can be applied irrespective of whether the sample is optically transparent or optically opaque and is independent of thickness.     

Microwave Induced Optical Nuclear Polarization at 75 GHz: A quantitative analysis

A quantitative analysis of Microwave Induced Optical Nuclear Polarization (MIONP) on crystals of fluorene-h₁₀ doped with phenanthrene-d₁₀ at 75 GHz and 1.4 K is presented. Two effects are studied in detail: the nuclear spin diffusion barrier and the phonon bottleneck. Experiments are presented that allow the identification of the proton spins on fluorene-h₁₀ molecules located inside the nuclear spin diffusion barrier surrounding phenanthrene-d₁₀ molecules excited in the photo-excited triplet state. Using this result the experimental values for the triplet spin-lattice relaxation (SLR) rates and the nuclear SLR rate can be related to each other without any fitting parameter. Microwave frequency and magnetic field modulation are used during MIONP to prove that the triplet SLR is phonon-bottlenecked. Subsequently a quantitative analysis of MIONP in the system fluorene-h₁₀ doped with phenanthrene-d₁₀ is obtained.     

Optical bottles: A quantitative analysis of optically confined nanoparticle ensembles in suspension

We present a novel method, an optical bottle, that uses a focused laser beam to trap and a second laser to analyze optically confined multiple nanoparticles. A theoretical framework based on the mechanical equilibrium of the optical radiation pressure produced by the focused laser beam and the osmotic pressure produced by the enriched particle concentration in the optical trap is developed for analyzing the ensemble behavior of the optically confined nanoparticles. Experiments were conducted for fluorescently labeled polystyrene nanospheres and unilamellar phospholipid vesicles to determine the optical trapping energy of individual particles as well as the osmotic compressibility of the colloids. The new method is not limited by the particle concentration and is relatively easy to implement.     

A numerical simulation of photothermal response in laser medicine

In this paper, we reported a numerical solution of laser induced thermal effect in the bio-tissue. The model of photothermal effect and classical Pennes bio-heat transfer equation were introduced. Finite element method (FEM), which was realized by Matlab software, was used to calculate the temperature distribution. He-Ne laser (633 nm) was used to simulate the physical therapy in in vivo skin tissue. Under the cylinder coordinates, the three-dimension(3-D) geometry of tissue was reduced to two-dimension(2-D)computation. The results contained the radial, axial and temperature 3-D color plot. Combining the time animation display was possible. By changing the laser and tissue parameters we can get different results.This will be the initial and indispensable work of the non-destructive evaluation of the laser induced injury.     

Optogalvanic nonlinear hanle effect by a single frequency laser: A quantitative analysis

The optogalvanic technique combined with the excitation by means of a single-frequency dye laser has been used to investigate the nonlinear Hanle effect on a variety of atomic transitions involving various quantum numbers and selection rules. A rate equation model has been successfully applied to provide a quantitative analysis of the observed signals. Saturation and pressure broadening parameters are reported for Ne transitions at 607.4 and 603.0 nm and Ca transitions at 610.2 and 585.7 nmWork partially supported by INFN and Italian Ministery of Education     

Symbolic recurrence plots: A new quantitative framework for performance analysis of manufacturing networks

During the last years, the concept of recurrence plots has received considerable interest as a tool for analysing nonlinear and non-stationary time series. However, in the case of discrete-valued observables or variations on very different time scales, problems may occur in direct interpretations of the results of recurrence quantification analysis (RQA). As a potential solution, we suggest combining this approach with ideas from symbolic time series analysis, which allows an arbitrary static or dynamic coarse-graining of the dynamics that goes beyond recent recurrence plot based methods. As an illustrative application, we discuss how the resulting symbolic recurrence plots may be used for a quantitative investigation of the dynamics of discrete-valued inventory levels of cooperating firms in a manufacturing network. Based on discrete-event simulations, measures from traditional RQA are used to evaluate the performance of the individual firms under different production strategies as well as order policies. The results of our investigations are an important step towards an anticipative knowledge about the performance of manufacturing systems under different conditions, which is of major importance for the planning and control of both production and logistics.     

分析法布里-珀罗标准具成像不清晰现象

从干涉条纹的定域出发,定量的解释了法布里－珀罗标准具成像不清晰的原因。     

A quantitative analysis of recombination data in high magnetic fields

Magnetic field effects on the hydrogen abstraction reaction of 4-methoxybenzophenone with thiophenol in several solvents of different viscosity have been reported, and the observed magnetic field dependence was explained as caused by the Δg and a polarized initial triplet radical pair state. The present work reports a quantitative analysis of the data based on a recently derived general analytical formula. It is found that the observed magnetic field dependence can be explained as originating from an unpolarized triplet state, if both the coherent mixing caused by different g values of the two radicals and the incoherent mixing due to spin relaxation are included. Several different expressions for the magnetic field dependence of the longitudinal and transverse relaxation rates were applied. Rather surprisingly, the different models gave almost identical fits. However, the values obtained of the microscopic parameters depended significantly on the model. Physically sensible parameter values were obtained only when the complete magnetic field dependence of the two relaxation times were used. For this model it was found that both the anisotropy factor of the g tensors and the diffusion coefficient agreed with expectations.     

A quantitative analysis of the simulated annealing algorithm: A case study for the traveling salesman problem

A quantitative study is presented of the typical behavior of the simulated annealing algorithm based on a cooling schedule presented previously by the authors. The study is based on the analysis of numerical results obtained by systematically applying the algorithm to a 100-city traveling salesman problem. The expectation and the variance of the cost are analyzed as a function of the control parameter of the cooling schedule. A semiempirical average-case performance analysis is presented from which estimates are obtained on the expectation of the average final result obtained by the simulated annealing algorithm as a function of the distance parameter, which determines the decrement of the control parameter.     

A DPL model of photothermal interaction in a semiconductor material

The generalized model for plasma, thermal, and elastic waves under dual phase lag model have been applied to determine the carrier density, the displacement, the temperature, and the stresses in a semiconductor medium. Using Laplace transform and the eigenvalue approach methodology, the solutions of all variables have been obtained analytically. A semiconducting material like as silicon was considered. The results were graphically represented to show the different between the dual phase model, Lord and Shulman’s theory and the classical dynamical coupled theory.     

Thermal properties of compressed expanded graphite: photothermal measurements

The thermal diffusivity and the thermal conductivity of compressed expanded graphite (CEG) samples were investigated by photothermal measurements in two geometries differing by a place of temperature disturbance detection. This disturbance can be detected on a surface opposite to the one at which the disturbance was generated (rear detection) or on the same surface (front detection). A measurement based on the rear detection allowed us to determine the effective thermal diffusivity of the sample, while the method with front detection gives the possibility of analysis of homogeneity of the sample. It is shown that the thermal diffusivity of CEG strongly depends on its apparent density. Moreover, CEG samples reveal anisotropy of the thermal properties. The thermal diffusivity in the direction parallel to the compacting axis is lower than the one in the direction perpendicular to it. The parallel thermal diffusivity decreases with growing apparent density, while the perpendicular thermal diffusivity significantly grows when the apparent density grows. The perpendicular thermal conductivity exhibits the same behavior as the perpendicular thermal diffusivity. The parallel thermal conductivity slightly grows with growing density and then reaches a plateau. The anisotropy of CEG samples grows with growing apparent density and vanishes for low-density samples. The photothermal measurement with front signal detection revealed that the CEG samples are non-homogeneous in the direction of the compacting axis and can be modeled by a two-layer system.     

一个经典静电学问题的定量分析

从定量的角度分析了一个经典静电学问题即水珠在静电场中的运动轨迹.运用牛顿定律建立了水珠的运动学方程,并在MATLAB环境下得出方程的数值解,最后通过设计模拟实验系统验证了结果.