Optical properties of root canal irrigants in the 300–3,000-nm wavelength region

Background: The leaves of neem (Azadirachta indicia) is one of herbal medicine that recommended as an alternative material of root canal irrigants. The active ingredients of neem leaves such as alkaloids, tannins, saponins and flavonoids has been proven to have antibacterial activity against E. faecalis. The ideal properties of an alternative material of root canal irrigants is not only have antibacterial activity but also is not toxic to the tissues, but the toxicity of neem leaves remains unclear until now. Objective: The aims of this study to determine the toxicity effect of neem leaves extract in specific concentration. Methods: This research was an experimental laboratory in vitro study of baby hamster kidney fibroblast (BHK-21). The neem leaves extract was made by maceration method using ethanol 96% and certain dilution performed to obtain various concentrations. Cytotoxicity test was conducted by MTT assay and the optical density was measured using ELISA reader at wavelength of 620 nm. Then, the optical density values were calculated using the formula for determining the number of survival fibroblasts after tested. Results: The percentage of survival fibroblast at concentration of 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95, and 100% in sequence were 71.3%, 64, 2%, 62%, 60.2%, 40.1%, 36.3%, 36.7%, 29%, 28.4%, 27.5%, and 25.6% . Conclusion: The extract of neem leaves (Azadirachta indica) has cytotoxic effects at concentration of 70% up to 100%.

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Nonlinear Optical Properties of Spheroidal Metallic Inclusions in a Dielectric Medium

ISRN Nanotechnology ◽

10.5402/2011/487646 ◽

2011 ◽

Vol 2011 ◽

pp. 1-9

Author(s):

Bernard de Dormale ◽

Vo-Van Truong

Keyword(s):

Optical Properties ◽

Nonlinear Optical ◽

Symmetry Axis ◽

Rotational Symmetry ◽

Strong Dependence ◽

Wavelength Region ◽

Nonlinear Optical Properties ◽

Linear Absorption ◽

Direction Parallel ◽

Depolarization Factor

A model for linear and nonlinear optical properties of a composite material consisting of spheroidal metal inclusions embedded in a host medium has been formulated using an effective medium approach. Both aligned and randomly oriented spheroids have been considered, and the results obtained showed a considerable difference between the two situations. Numerical calculations for metallic Au inclusions in a glass matrix have shown that the linear absorption in the case of aligned spheroids with their symmetry axis parallel to the z-axis is largely dependent on the depolarization factor, exhibiting an absorption in the vicinity of 500 nm when the depolarization factor in the direction parallel to the rotational symmetry axis is small. This structure shifts progressively to higher wavelengths when this depolarization factor is increased. In the case of randomly oriented spheroids, contributions from the different particle depolarization factors are present and prominent structures in the linear absorption appear in the long wavelength region, beyond 700 nm. Nonlinear optical properties for both aligned and randomly oriented spheroids also show a strong dependence on the depolarization factor and significant enhancements of these properties can be observed, suggesting possible tailoring of composite properties for various applications.

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