Third order nonlinear optics in Ag nanocubes: local and nonlocal optical responses as a function of excitation wavelength and particle size.

Colloidal silver nanocubes in solution were analyzed by the Z-scan technique in the resonant and non-resonant regimes. Three different systems with particle sizes of 56, 99 and 215 nm, and concentrations of 0.378, 0.831 and 0.715 mg/mL, respectively, were obtained by the polyol method. Nonlinear excitation of the samples was performed with laser pulses of 26 ps, at a repetition rate of 10 Hz, and using three different wavelenghts (355, 532 and 1064 nm), exciting only the electronic part of the optical nonlinearity, and avoiding induced thermal loading of the samples. Whenever observable, samples showed saturable absorption for all wavelengths, which was dependent, in general, on concentration and incident intensity. For samples featuring sizes of 55 and 99 nm, saturable absorption could be observed for wavelengths close to their dipolar surface plasmon resonances; while, for samples with sizes of 99 and 215 nm, saturable absorption and positive nonlinear optical refraction (only for size of 215 nm) could be observed at 1064 nm. Besides, for some samples, nonlinear optical response followed the incident intensity profile at wavelengths close to resonance. On the contrary, for wavelengths out of resonance, the nonlinear optical behavior showed to be nonlocal, ie, its profile was narrower than the incident one.

Nonlocal nonlinear refraction in Hibiscus sabdariffa with large phase shifts.

In this work we present a study of nonlinear optical properties in organic materials (hibiscus sabdariffa). Our results demonstrate that the medium exhibits a highly nonlocal nonlinear response. We show preliminary numerical results of the transmittance as nonlocal response by considering, simultaneously, the nonlinear absorption and refraction in media. Numerical results are accord to measurement obtained by Z- scan technique where we observe large phase shifts. We also analyze the far field diffraction ring patterns of the sample.

The need for re-TUR of the bladder in non-muscle invasive bladder cancer: risk factors of tumor persistence in re-TUR specimens.

AIM: This study evaluated the need for re-TUR of the bladder in non-muscle invasive bladder cancer (NMIBC) with complete transurethral resection (TUR) and examined the risk factors for disease occurrence in re-TUR of the bladder. METHODS: A cohort of 211 patients diagnosed consecutively of NMIBC (July 2009 to October 2011) underwent re-TURB 4-6 weeks after the initial TURB. Association with tumor presence in re-TURB of the following parameters was analyzed: sex, primary/recurrent, number, size, stage, grade, association of carcinoma in situ, early instillation of Mitomycin C, and its classification according to the EORTC risk groups. RESULTS: Fifty-seven (27%) cases exhibited residual tumors in the re-TURB and understaging was observed in 3 (1.4%) patients. The EORTC classified 151 (71.6%) patients as high risk; 124 (58.7%) patients received postoperative instillations of Mitomycin C. 31.8% of high risk patients exhibited tumors in the re-TUR compared to 14% of the low/intermediate risk (P<0.05). A total of 19.4% of patients with early instillation of Mitomycin C had tumor in re-TURB compared to 38.4% of patients without it (P<0.05). Multivariate analysis showed that high-risk tumors behaved as an independent risk factor for the tumor presence in re-TURB (HR=12.65, P=0.008), but early postoperative instillation of Mitomycin C was a protective factor (HR=2.16, P=0.02). The limitations of the study are the absence of randomization and its unicentric character. CONCLUSION: Patients who were at a high risk of tumor recurrence and/or progression according to the EORTC classification exhibited a higher percentage of tumors in re-TURB. Therefore, these patients are optimal candidates for re-TURB.