Design of Polymer Wavelength Splitter 1310 nm/1550 nm Based on Multimode Interferences

We report about design of 1x2 1310/1550 nm optical wavelength division multiplexer based on polymer waveguides. The polymer splitter was designed by using RSoft software based on beam propagation method. Epoxy novolak resin polymer was used as core waveguides layer, silicon substrate with silica layer was used as buffer layer and polymethylmethacrylate was used as protection cover layer. The simulation shows that the output energy for the fundamental mode is 67.1 % for 1310 nm and 67.8 % for 1550 nm wavelength

Design, Fabrication and Properties of Rib Poly(methylmethacrylimide) Optical Waveguides

We report about design, fabrication and properties of the polymer optical waveguides deposited on silica-on-silicon substrate. The design of the waveguides is based on a concept that geometric dimensions of the single mode polymer waveguide are determined by geometrical parameters of the silica layer. The design of the waveguides was schemed for 650 nm, 850 nm, 1310 nm and 1550 nm wavelength. The design of the presented planar waveguides was realized on the bases of modified dispersion equation while the ridge waveguides design was proposed following the Fischbeck concept. Both designs were refined applying RSoft software using beam propagation method. Proposed shapes of the waveguides were etched by standard photolithography process into the silica layers and polymer waveguide layers were subsequently deposited into the treated substrate by spin coating. Poly(methylmethacrylimide) was used as the waveguide core material and polymethylmethacrylate was used as a cover protection layer. Propagation optical loss measurements were done by using the cut-back method and the best samples had optical losses lower than 0.6 dB/cm at 650 nm, 1310 nm and 1550 nm

Optical Properties of Erbium and Erbium/Ytterbium Doped Polymethylmethacrylate

In this paper we report on the fabrication and properties of Er3 and Er3/Yb3 doped Polymethylmethacrylate (PMMA) layers. The reported layers were fabricated by spin coating on silicon or on quartz substrates. Infrared spectroscopy was used for an investigation of O-H stretching vibration. Measurement were made of the transmission spectra in the wavelength ranges from 350 to 700 nm for the Er3 doped samples and from 900 to 1040 nm for the Yb3 doped samples. The refractive indices were investigated in the spectral range from 300 to 1100 nm using optical ellipsometry and the photoluminescence spectra were measured in the infrared region

Chiral plasmonic response of 2D Ti3C2Tx flakes: realization and applications

The circularly polarized light sensitive materials response can be reached at plasmon wavelengths through the coupling of intrinsically non-chiral plasmonic nanostructure with chiral organic molecules. As a plasmonic background, the different types of metal nanoparticles of various shapes and sizes are successfully tested and an apparent circular dichroism (CD) signal is measured in both, nanoparticles suspensions and after nanoparticle immobilization in substrate. In this work, the creation of plasmon-active 2D flakes of MXenes (Ti3C2Tx) is proposed, with the apparent CD response at plasmon wavelength, through the coupling of intrinsically non-chiral flakes with helically shaped helicene enantiomers. This work provides the first demonstration of chiral and plasmon-active 2D material, which shows the absorption sensitive to light intrinsic circular polarization even in plasmon wavelengths range. The appearance of the induced CD signal is additionally confirmed by several theoretical calculations. After the experimental and theoretical confirmation of the optical chirality at plasmon wavelengths, the flakes are utilized for the polarization sensitive conversion of light to heat, as well as for polarization dependent triggering of plasmon-assisted chemical transformation

ECCO Guidelines on Therapeutics in Ulcerative Colitis: Surgical Treatment

This is the second of a series of two articles reporting the European Crohn's and Colitis Organisation [ECCO] evidence-based consensus on the management of adult patients with ulcerative colitis [UC]. The first article is focused on medical management, and the present article addresses medical treatment of acute severe ulcerative colitis [ASUC] and surgical management of medically refractory UC patients, including preoperative optimisation, surgical strategies, and technical issues. The article provides advice for a variety of common clinical and surgical conditions. Together, the articles represent an update of the evidence-based recommendations of the ECCO for UC

ECCO Guidelines on Therapeutics in Ulcerative Colitis: Medical Treatment

hese recommendations summarise the current evidence on the medical management of adult patients with UC. Gaps were iden-tified during the analysis of the data, which should be addressed by further research. Where evidence is lacking or is very weak and evidence-based recommendations cannot be given, ECCO provides alternative tools, such as Topical Reviews28,95,153–158 or Position Papers.159–161 It is important that clinicians use these guidelines within the framework of local regulations, and seek to understand and address the individual needs and expectations of every patient. We recognise that constraints on health care resources are an im-portant factor in determining whether recommendations can be implemented for patients in many countries. The recommendations outlined here should be used to inform treatment decisions and form part of an overall multidisciplinary treatment plan for patients with UC, which may also encompass psychological, nutritional, and other non-pharmacological interventions

Methods for diagnosing bile acid malabsorption: a systematic review

Background: Bile acid malabsorption (BAM) and bile acid-related diarrhea represent an under-recognized cause of chronic diarrhea mainly because of limited guidance on appropriate diagnostic and laboratory tests. We aimed to perform a systematic review of the literature in order to identify and compare the diagnostic accuracy of different diagnostic methods for patients with BAM, despite a proven gold standard test is still lacking. Methods: A PubMed literature review and a manual search were carried out. Relevant full papers, evaluating the diagnostic accuracy of different methods for BAM, were assessed. Available data were analyzed to estimate the sensitivity and specificity of each published test. Results: Overall, more than one test was considered in published papers on BAM. The search strategy retrieved 574 articles; of these, only 16 were full papers (with a total of 2.332 patients) included in the final review. Specifically, n = 8 studies used 75Selenium-homotaurocholic-acid-test (75SeHCAT) with a < 10% retention threshold; n = 8 studies evaluated fasting serum 7-α-hydroxy-4-cholesten-3-one (C4); n = 3 studies involved total fecal bile acid (BA) excretion over 48 h; n = 4 studies assessed fibroblast growth factor 19 (FGF19). 75SeHCAT showed an average sensitivity and specificity of 87.32 and 93.2%, respectively, followed by serum C4 (85.2 and 71.1%) and total fecal BA (66.6 and 79.3%). Fasting serum FGF19 had the lowest sensitivity and specificity (63.8 and 72.3%). All the extracted data were associated with substantial heterogeneity. Conclusions: Our systematic review indicates that 75SeHCAT has the highest diagnostic accuracy for BAM, followed by serum C4 assay. The diagnostic yield of fecal BA and FGF19 assays is still under investigation. Our review reinforces the need for novel biomarkers aimed to an objective detection of BAM and therefore improving the management of this condition

Methods for diagnosing bile acid malabsorption: a systematic review

Background: Bile acid malabsorption (BAM) and bile acid-related diarrhea represent an under-recognized cause of chronic diarrhea mainly because of limited guidance on appropriate diagnostic and laboratory tests. We aimed to perform a systematic review of the literature in order to identify and compare the diagnostic accuracy of different diagnostic methods for patients with BAM, despite a proven gold standard test is still lacking. Methods: A PubMed literature review and a manual search were carried out. Relevant full papers, evaluating the diagnostic accuracy of different methods for BAM, were assessed. Available data were analyzed to estimate the sensitivity and specificity of each published test. Results: Overall, more than one test was considered in published papers on BAM. The search strategy retrieved 574 articles; of these, only 16 were full papers (with a total of 2.332 patients) included in the final review. Specifically, n = 8 studies used 75Selenium-homotaurocholic-acid-test (75SeHCAT) with a < 10% retention threshold; n = 8 studies evaluated fasting serum 7-\u3b1-hydroxy-4-cholesten-3-one (C4); n = 3 studies involved total fecal bile acid (BA) excretion over 48 h; n = 4 studies assessed fibroblast growth factor 19 (FGF19). 75SeHCAT showed an average sensitivity and specificity of 87.32 and 93.2%, respectively, followed by serum C4 (85.2 and 71.1%) and total fecal BA (66.6 and 79.3%). Fasting serum FGF19 had the lowest sensitivity and specificity (63.8 and 72.3%). All the extracted data were associated with substantial heterogeneity. Conclusions: Our systematic review indicates that 75SeHCAT has the highest diagnostic accuracy for BAM, followed by serum C4 assay. The diagnostic yield of fecal BA and FGF19 assays is still under investigation. Our review reinforces the need for novel biomarkers aimed to an objective detection of BAM and therefore improving the management of this condition

Biopsy sampling in upper gastrointestinal endoscopy - a survey from ten tertiary referral centres across Europe

BACKGROUND: Guidelines give robust recommendations on which biopsies should be taken when there is endoscopic suggestion of gastric inflammation. Adherence to these guidelines often seems arbitrary. This study aimed to give an overview on current practice in tertiary referral centres across Europe. METHODS: Data was collected at ten tertiary referral centres. Demographic data, the indication for each procedure, endoscopic findings and the number and sampling site of biopsies were recorded. Findings were compared between centres and factors influencing the decision to take biopsies explored. RESULTS: Biopsies were taken in 56.6% of 9425 procedures, with significant variation between centres (p&lt;0.001). Gastric biopsies were taken in 43.8% of all procedures. Sampling location varied with the procedure indication (p&lt;0.001) without consistent pattern across the centres. Fewer biopsies were taken in centres which routinely applied the updated Sydney classification for gastritis assessment (46.0%), compared to centres where this was done only upon request (75.3%, p&lt;0.001). This was the same for centres stratifying patients according to the OLGA system (51.8% vs 73.0%, p&lt;0.001). More biopsies were taken in centres following the MAPS guidelines on stomach surveillance (68.1% vs 37.1%, p&lt;0.001). Biopsy sampling was more likely in younger patients in 8 centres (p&lt;0.05), but this was not true for the whole cohort (p=0.537). The percentage of procedures with biopsies correlated directly with additional costs charged in case of biopsies (r=0.709, p=0.022). CONCLUSION: Adherence to guideline recommendations for biopsy sampling at gastroscopy was inconsistent across the participating centres. Our data suggest that instead centre-specific policies are applied.</p