Time-reversed adapted-perturbation (TRAP) optical focusing onto dynamic objects inside scattering media

The ability to steer and focus light inside scattering media has long been sought for a multitude of applications. At present, the only feasible strategy to form optical foci inside scattering media is to guide photons by using either implanted or virtual guide stars, which can be inconvenient and limits the potential applications. Here we report a scheme for focusing light inside scattering media by employing intrinsic dynamics as guide stars. By adaptively time-reversing the perturbed component of the scattered light, we show that it is possible to focus light to the origin of the perturbation. Using this approach, we demonstrate non-invasive dynamic light focusing onto moving targets and imaging of a time-variant object obscured by highly scattering media. Anticipated applications include imaging and photoablation of angiogenic vessels in tumours, as well as other biomedical uses

Development and validation of stability indicating method for determination of sertraline following ICH guidlines and its determination in pharmaceuticals and biological fluids

<p>Abstract</p> <p>Background</p> <p>Sertraline is a well known antidepressant drug which belongs to a class called selective serotonin reuptake inhibitor. Most published methods do not enable studying the stability of this drug in different stress conditions.</p> <p>Results</p> <p>Two new methods were developed for the determination of sertraline (SER). Both methods are based on coupling with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) in borate buffer of pH 7.8 and measuring the reaction product spectrophotometrically at 395 nm (Method I) or spectrofluorimetrically at 530 nm upon excitation at 480 nm (Method II). The response-concentration plots were rectilinear over the range 2-24 μg/mL and 0.25-5 μg/mL for methods I and II respectively with LOD of 0.18 μg/mL and 0.07 μg/mL, and LOQ of 0.56 μg/mL and 0.21 μg/mL for methods I and II, respectively.</p> <p>Conclusion</p> <p>Both methods were applied to the analysis of commercial tablets and the results were in good agreement with those obtained using a reference method. The fluorimetric method was further applied to the in vivo determination of SER in human plasma. A proposal of the reaction pathway was presented. The spectrophotometric method was extended to stability study of SER. The drug was exposed to alkaline, acidic, oxidative and photolytic degradation according to ICH guidelines. Moreover, the method was utilized to investigate the kinetics of oxidative degradation of the drug. The apparent first order rate constant and t_1/2of the degradation reaction were determined.</p

The gluten-free diet and its current application in coeliac disease and dermatitis herpetiformis

A gluten-free diet (GFD) is currently the only available therapy for coeliac disease (CD)