Optical Coherent Reflection from a Confined Colloidal Film: Modeling and Experiment.

We study the optical reflectivity of confined colloidal films as a function of the angle of incidence in an internal reflection configuration. Two effective medium models and an extended coherent-scattering model for thin colloidal films are compared against experimental measurements with gold, latex, and titanium dioxide colloids. A derivation of the coherent scattering model for confined colloidal films used in this work is presented in a comprehensive way. The model lies within the framework of the multiple-scattering theory and is valid for any angle of incidence and for colloids of small or large particles compared to the wavelength of light, however, only for small and moderately small particles' volume fraction. Reflectivity versus angle of incidence curves for an opaque colloidal film in an internal reflection configuration show the effects of two critical angles. Within the two critical angles, there is a high sensitivity to the presence of colloidal particles, while the volume of colloidal samples needed is in the microliter range. Upon comparing theory with experiment, no model fitting was done in any case. The experimental setup and its calibration procedure are discussed. The results provide physical insight into applications involving optical properties of colloidal systems.

Analytical modeling of optical reflectivity of random plasmonic nano-monolayers.

In this paper, we compare three different models that have been used to interpret reflectivity measurements of supported monolayers of nanoparticles. Two of them: (i) isotropic Maxwell Garnett and (ii) anisotropic two-dimensional-dipolar model are based on an effective-medium approach, while the third one (iii) coherent-scattering model, lies within the framework of multiple-scattering theory. First, we briefly review, on physical grounds, the foundations of each model and write down the corresponding formulas for the calculation of the reflectivity. In the two-dimensional-dipolar model, the dilute limit of the pair-correlation function (also called hole-correlation function) is always used in the calculation of the effective optical response. Then we use these formulas to plot and analyze graphs of the reflectivity of a monolayer of gold nanoparticles on a glass substrate, as a function of several relevant parameters, for two different commonly used experimental configurations. Finally, we discuss the importance of our results and how they can be used to infer the limits of validity of each model.

Prevalence and factors associated with cognitive deficit in women with gynecologic malignancies.

OBJECTIVE: Cognitive impairment has implications in counseling, treatment, and survivorship for women with gynecologic malignancies. The purpose of our study was to evaluate the prevalence and risk factors associated with cognition in women with gynecologic malignancies. METHODS: After Institutional Review Board approval, 165 women at an urban ambulatory gynecologic oncology facility were queried using a Montreal Cognitive Assessment (MoCA), Wong-Baker pain scale, neuropathy scale, Patient Health Questionnaire 9 (PHQ-9) Depression Scale, and Generalized Anxiety Disorder Scale (GAD 7). Univariate and multivariate analyses were utilized to evaluate the association of cognitive deficit with age, education, race/ethnicity, disease site, stage, treatment, pain, neuropathy, anxiety, and depression. RESULTS: The mean MoCA score for the entire cohort was 24.1 (range 13-30.) 24% of patients had MoCA scores less than 22. Low scores (<22) were associated with older age, non-white race/ethnicity, lower education level, uterine and vulvar cancers, and pain ≥5 (p<0.05). There was a trend toward lower cognition scores for women treated with both chemotherapy and radiation (p=0.10). While clinically significant pain was associated with low cognition, there was no association with use of opioid pain medication and low cognition scores. CONCLUSIONS: There was a high prevalence of cognitive deficit in women with gynecologic malignancies. The association of low cognition with report of clinically significant pain, but not with use of opioid pain medications, should be further explored. Research is needed to evaluate the impact of cognitive deficits on treatment adherence and outcomes for women with gynecologic malignancies.

Experimental Test of Reflectivity Formulas for Turbid Colloids: Beyond the Fresnel Reflection Amplitudes.

We compare light reflectivity measurements as a function of the angle of incidence for an interface between an optical glass and a turbid suspension of small particles, with theoretical predictions for the coherent reflectance calculated with different available theoretical models. The comparisons are made only in a small range of angles of incidence around the critical angle of the interface between the glass and the matrix of the colloidal suspensions. The experimental setup and its calibration procedure are discussed. We considered two Fresnel-based approximations and another two based on a multiple-scattering approach, and we present results for monodisperse latex colloidal suspensions of polymeric spherical particles in water with particle diameters of 120 and 520 nm, polydisperse titanium dioxide (rutile) particles suspensions in water with a most probable diameter of 404 nm, and suspensions of copper particles in water with diameters of 500 nm. The comparisons between experiment and theory are made without fitting any parameters.

Utilización de la Medicina Natural y Tradicional en pacientes tratados por Ortodoncia con afecciones de la mucosa oral / Use of the natural and Traditional Medicine in patients tried by orthodontics with oral mucosa injuries

Introducción: la mayoría de las lesiones bucales en los tratamientos de Ortodoncia son resultado de una irritación mecánica que comienza en las membranas mucosas de las encías y la parte interna de los carrillos por lo que es importante su detección a tiempo. Objetivo: comparar los procederes terapéuticos más utilizados en Medicina Natural y Tradicional con la terapia convencional en pacientes con tratamiento de ortodoncia que presentan lesiones traumáticas de la mucosa oral.Material y Métodos: se realizó un estudio retrospectivo, descriptivo, en el período comprendido de enero a junio del 2006 en la clínica estomatológica Juan Manuel Márquez del municipio Playa, provincia La Habana. Se escogió una muestra al azar de 174 pacientes, que comprendió sujetos de cualquier sexo y raza, que se trataron con Fitoterapia, Apiterapia y Láser terapia específicamente, y tratamiento convencional de lesiones orales. Se evaluaron en un tiempo comprendido entre 7, 15, y 30 días midiendo la efectividad terapéutica. Para el análisis estadístico se utilizaron frecuencias absolutas y relativas. Resultados: la mayoría de los pacientes evolucionaron en un tiempo de 15 días según lo establecido en estos tipos de lesiones, La mayor efectividad fue de la terapia Láser comprobándose sus efectos bioestimulantes y reparación hística.Conclusiones: la totalidad de los pacientes tratados con Láser terapia y Fitoterapia tuvieron una evolución final satisfactoria en un término de 15 días, sin embargo algunos de los tratados con apiterapia y la técnica convencional demoraron hasta 30 días en su curación(AU)

Introduction: most of the buccal lesions in the Orthodontic's treatment are product of a mechanical irritation that begins in the mucosal membranes of the gums and internal part of the cheeks because of that is important their detection on time.Objective: to compare the most used therapeutics procedure in Traditional and Natural Medicine respecting to conventional orthodontic therapy in patients with traumatic oral mucosal injuries. Material and methods: a retrospective and descriptive trial was done during the period from January to June of the 2006 in the stomatological clinic "Juan Manuel Márquez" setting geographically in the Playa municipality, at the Havana Province. A random sample included 174 patients of any sex and race specifically treated using Physiotherapy, Apiotherapy and Laser therapy and conventional treatment of oral lesions. The therapeutic efficacy was assessed at time of 7, 15, and 30 days. Statics analysis included both relative and absolute frequencies. Results: most of the patients had an evolution time of 15 days according to establishing time in these types of lesions, the biggest effectiveness corresponding to therapy Laser being proven its effects bio-stimulant and the histic repairing. Conclusions: all the patient treated using Laser therapy and Physiotherapy had a satisfactory ending evolution in 15 days, whereas, some of patient treated with Apiotherapy and Conventional therapy delayed up to 30 days to cure(AU)

Extension of Fresnel's formulas for turbid colloidal suspensions: a rigorous treatment.

We provide new expressions for the reflection amplitudes of a half space of randomly located identical spherical particles that can be regarded as an extension of Fresnel's formulas when scattering is prominent. We derive them rigorously from Maxwell's equations by solving an integral equation for the electric field within the effective-field approximation. The integral equation is given in terms of the nonlocal conductivity tensor of an isolated sphere. Approximate expressions for the reflection amplitudes are also proposed and their accuracy is analyzed, first for the case of a self-sustained suspension of silver particles, and then for the more realistic situation of silver particles in water. In this latter case the integral equation is modified by introducing the half-space Green's function dyadic instead of the one in free-space, but the method of solution is analogous in both. This extension of Fresnel's formulas, together with the numerical comparison of the different approximations proposed here, is necessary for an accurate interpretation of reflection-spectroscopy measurements in dilute colloidal suspensions of practical interest. The connection between the nonlocal conductivity tensor and the T-matrix operator of scattering theory is also made manifest.

Multiple-scattering model for the coherent reflection and transmission of light from a disordered monolayer of particles.

Using a multiple-scattering formalism, we derive closed-form expressions for the coherent reflection and transmission coefficients of monochromatic electromagnetic plane waves incident upon a two-dimensional array of randomly located spherical particles. The calculation is performed within the quasi-crystalline approximation, and the statistical correlation among the particles is assumed to be given simply by a correlation hole. In the resulting model, the size of the spheres and the angle of incidence are both unrestricted. The final formulas are relatively simple, making the model suitable for a straightforward interpretation of optical-sensing measurements.

Rigorous theoretical framework for particle sizing in turbid colloids using light refraction.

Using a non-local effective-medium approach, we analyze the refraction of light in a colloidal medium. We discuss the theoretical grounds and all the necessary precautions to design and perform experiments to measure the effective refractive index in dilute colloids. As an application, we show that it is possible to retrieve the size of small dielectric particles in a colloid by measuring the complex effective refractive index and the volume fraction occupied by the particles.

Coherent optical reflectance from a monolayer of large particles adsorbed on a glass surface.

We develop a coherent-scattering model for the reflection of light from a monolayer of large particles and low surface coverage. The model takes into account multiple scattering between particles of the monolayer and with the substrate, and it can be used around the critical angle in an internal reflection configuration. We compare the results of the model with our own reflectivity data taken with latex particles adsorbed on a glass-water interface and with a simpler effective-medium model.

Coherent reflection of light from a turbid suspension of particles in an internal-reflection configuration: Theory versus experiment.

We compare a recently developed coherent-scattering model for the reflectance of light from a turbid colloidal suspension of particles with experimental measurements. The experimental data were obtained in an internal reflection configuration around the critical angle using a glass prism in contact with a monodisperse colloidal suspension of latex particles, and a polydisperse suspension of TiO2 particles. First, we review the coherent scattering model and extend it to the case of polydisperse suspensions in an internal reflection configuration. The experimental data is then compared with results of the coherent scattering model and results obtained assuming that the colloidal system can be treated as a homogeneous medium with an effective index of refraction. We find that the experimental results are not compatible with the effective medium model. On the other hand, good fits to the experimental curves can be obtained with the coherent scattering model.

Coherent reflectance in a system of random Mie scatterers and its relation to the effective-medium approach.

We consider the coherent reflection and transmission of electromagnetic waves from a slab of a dilute system of randomly located, polarizable, spherical particles. We focus our attention on the case where the size of the spheres is comparable to the wavelength of the incident radiation. First, using wave-scattering and Mie theories, we derive expressions for the coherent fields that are transmitted and reflected by a very thin slab. Then we find the effective-current distribution that would act as a source of these fields. We conclude that if the effective currents were induced in an effective medium, this medium must possess, besides an effective electric permittivity, also an effective magnetic permeability. We find that both of these optical coefficients become functions of the angle of incidence and the polarization of the incident wave. Then we calculate the reflection coefficient of a half-space by considering a semi-infinite pile of thin slabs and compare the result with Fresnel relations. Numerical results are presented for the optical coefficients as well as for the half-space reflectance as a function of several parameters. The reflectance is compared with that obtained without considering the magnetic response. Finally, we discuss the relevance and the physics behind our results and indicate as well the measurements that could be performed to obtain an experimental verification of our theory.

Visible spectral dependence of the scattering and absorption coefficients of pigmented coatings from inversion of diffuse reflectance spectra.

A spectral-projected gradient method and an extension of the Kubelka-Munk theory are applied to obtain the relevant parameters of the theory from measured diffuse reflectance spectra of pigmented samples illuminated with visible diffuse radiation. The initial estimate of the spectral dependence of the parameters, required by a recursive spectral-projected gradient method, was obtained by use of direct measurements and up-to-date theoretical estimates. We then tested the consistency of the Kubelka-Munk theory by repeating the procedure with samples of different thicknesses.