Debye ring diffraction elucidation of 2D photonic crystal self-assembly and ordering at the air-water interface.

We fabricate 2D photonic crystals (2DPC) by spreading a dispersion of charged colloidal particles (diameters = 409, 570, and 915 nm) onto the surface of electrolyte solutions using a needle tip flow method. When the interparticle electrostatic interaction potential is large, particles self-assemble into highly ordered hexagonal close packed (hcp) monolayers. Ordered 2DPC efficiently forward diffract monochromatic light to produce a Debye ring on a screen parallel to the 2DPC. The diameter of the Debye ring is inversely proportional to the 2DPC particle spacing, while the Debye ring brightness and thickness depends on the 2DPC ordering. The Debye ring thickness increases as the 2DPC order decreases. The Debye ring ordering measurements of 2DPC attached to glass slides track measurements of the 2D pair correlation function order parameter calculated from SEM micrographs. The Debye ring method was used to investigate the 2DPC particle spacing, and ordering at the air-solution interface of NaCl solutions, and for 2DPC arrays attached to glass slides. Surprisingly, the 2DPC ordering does not monotonically decrease as the salt concentration increases. This is because of chloride ion adsorption onto the anionic particle surfaces. This adsorption increases the particle surface charge and compensates for the decreased Debye length of the electric double layer when the NaCl concentration is below a critical value.

Does hysteroscopy affect prognosis in apparent early-stage endometrial cancer?

The objective of the study was to compare the outcome measures of patients with endometrial adenocarcinoma diagnosed by endometrial biopsy, uterine curettage, or hysteroscopy. Medical records of 392 women diagnosed with apparent early-stage endometrial adenocarcinoma were reviewed. Data concerning the mode of diagnosis, histologic type and grade, surgical stage, peritoneal washings and lymph nodes status, and patient's outcome were retrieved. During the study period, 99 (25.3%) cases were diagnosed by endometrial biopsy, 193 (49.2%) by uterine curettage, and 100 (25.5%) by hysteroscopy. There were 347 (88.5%) cases of endometrioid adenocarcinoma and 45 (11.5%) of poor histologic types, including serous papillary, clear cell, and small cell cancer. Three hundred and sixteen (80.6%) patients had stage I disease, 8 (2.0%) stage II, and 68 (17.4%) stage III. Peritoneal cytology was positive in only one case. Recurrent disease occurred in 6.9% patients, of which 50% had local recurrence and 50% had distant. Recurrent disease was found in 15.2% patients diagnosed by endometrial biopsy, in 4.7% where uterine curettage was used, and in 5% when hysteroscopy was applied. No statistically significant difference in the survival rate between the different diagnostic methods applied was found, although a higher recurrence rate was noted following endometrial biopsy. After a median follow-up time of 25 months for patients undergoing hysteroscopy, there was no difference in recurrence rates and/or overall survival compared to other diagnostic procedures implying that hysteroscopy can be safely used in the diagnosis of endometrial cancer.