A combined experimental and simulation study on thickness dependence of the emission characteristics in multicolor single layer organic light-emitting diodes

The impact of the active layer thickness on the emission characteristics of multicolor single layer organic light-emitting diodes based on poly(9-vinylcarbazole) is examined by combining experimental results with model simulations. We compare experimental electroluminescence spectra with simulations using photon-emitting point dipoles and find a very good agreement. We also simulate the location of the recombination zone, considering that the emission probability distribution has a peak located 25 nm from the cathode, which decays exponentially above and below that point. Simulated radiation patterns show that microcavity effects dominate the thickness dependent emitting properties of these devices.</p

Reflection and transmission calculations in a multilayer structure with coherent, incoherent, and partially coherent interference, using the transmission line method

A generalized transmission line method (TLM) that provides reflection and transmission calculations for a multilayer dielectric structure with coherent, partial coherent, and incoherent layers is presented. The method is deployed on two different application fields. The first application of the method concerns the thickness measurement of the individual layers of an organic light-emitting diode. By using a fitting approach between experimental spectral reflectance measurements and the corresponding TLM calculations, it is shown that the thickness of the films can be estimated. The second application of the TLM concerns the calculation of the external quantum efficiency of an organic photovoltaic with partially coherent rough interfaces between the layers. Numerical results regarding the short circuit photocurrent for different layer thicknesses and rough interfaces are provided and the performance impact of the rough interface is discussed in detail. © 2015 Optical Society of America

Co-expression of trypsin and tumour-associated trypsin inhibitor (TATI) in colorectal adenocarcinomas

Trypsin and its specific inhibitor, TATI (tumour-associated trypsin inhibitor), are expressed in normal human pancreas and in a variety of tumours. The aim of the present study was to assess the parallel expression of trypsin and TATI in colorectal cancer, in comparison with their expression in normal epithelial tissue, since proteases and their inhibitors are thought to be co-expressed in malignant neoplasms. We also assessed the possible significance of their expression as a means of differentiation between normal and malignant tissue. We examined qualitatively and semiquantitatively the immunohistochemical expression of trypsin and TATI on paraffin-embedded serial tissue sections from 91 colorectal adenocarcinomas. The reverse-transcriptase-polymerase-chain reaction (RTPCR) was also performed on fresh malignant tissue from 55 of the above adenocarcinomas. Normal and nonmalignant tissues adjacent to the tumours were also evaluated. Cytoplasmic expression of trypsin (more than 25% of the cancer cells positive) was found in 67 (73.6%) adenocarcinomas, whereas TATI was expressed in the cytoplasm of 59 (64.8%) cases studied. Statistical analysis using Spearman’s test has demonstrated a significant correlation between trypsin and TATI immunohistochemical expression (p<0.01). RT-PCR showed co-expression of trypsin and TATI mRNA in all carcinomas studied. Distinct patterns of trypsin and TATI immunohistochemical expression were observed in adjacent, non-malignant tissues, where both trypsin and TATI mRNA were also detected. Normal tissues were negative by immunohistochemistry. Our results indicate co-expression of trypsin and TATI in colorectal tumours both at the mRNA and protein level. We conclude that in colorectal neoplasms, high levels of trypsin and TATI may be important for malignant tumour formation and/or metastatic process

Neuroendocrine neoplasms of the appendix: A review of the literature

Appendiceal neuroendocrine neoplasms (ANENs) comprise rare tumors of the appendix, mainly affecting young populations and characterized by a rather favorable prognosis. The aim of this review was to summarize the current knowledge on these neoplasms, focusing on the management and followup of such patients, which still remain under debate. ANENs account for 0.16-2.3% of appendectomies and are usually diagnosed incidentally. The histopathological diagnosis includes the immunohistochemical profile of the tumor in regard to synaptophysin and chromogranin A, as well as the Ki-67 index. The surgical management of ANENs is either simple appendectomy or a more extensive oncological operation including right hemicolectomy. This depends on the stage and the presence of risk factors suggesting a more aggressive disease, such as the exact location, mesoappendiceal or lymphovascular invasion, and the proliferative rate of the tumor. Despite their indolent course, ANENs may relapse. Therefore, lifetime observation is necessary for patients with tumors &gt;2 cm and &gt;1 cm plus additional risk factors; however, more studies should be conducted in order to determine the optimal follow-up strategy. © 2018 International Institute of Anticancer Research. All Right Reserved

Update on surgical management of small bowel neuroendocrine tumors

The widespread use of endoscopy and imaging in combination with the continuous update of the staging systems for neuroendocrine tumors has led to an increase in the incidence of small intestinal neuroendocrine tumors (si-NENs) globally. Despite high survival rates, severe complications may occur even in early stages due to the anatomic location of the primary site and the desmoplastic reaction. Surgery plays a central role in the management of patients with si-NENs. Excision of locoregional disease along with extensive lymph node dissection should be performed in fit patients, even in the presence of metastases. Multimodality treatment of liver metastases includes hepatectomy, ablative techniques and liver transplantation. Hormone therapy with somatostatine analogs is of high importance for symptomatic control; special caution should be exercised both pre- and intra-operatively. A multidisciplinary approach is essential in order to provide personalized therapeutics for patients with si-NENs. Clinical research and specialization in this field should be further encouraged. © 2018 International Institute of Anticancer Research. All rights reserved