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Early colonoscopy in patients with acute diverticulitis may alter the working diagnosis and be of therapeutic value. The rate of cecal intubation is lower and the perforation rate appears to be higher. A clear-cut indication therefore has to be evident clinically.

Perovskites based on methylammonium lead halides, CH 3 NH 3 PbX 3 (X = Cl, Br, I), have emerged as one of the most promising materials in solar cell technology. Although the photovoltaics field has witnessed significant progress in the power conversion efficiency (PCE) of perovskite solar cells, unveiling the contribution of the various factors (i.e., energy level alignment, trap states, electron (hole) mobility, interface interactions, and morphology) affecting the observed PCEs is extremely crucial to achieve reproducible and stable devices. This work aims to understand charge transport and recombination within conventional perovskite solar cells due to modifications of the morphology, optoelectronic properties, and energy levels of the titania electron transport layer. Here, we utilize two different processing methods (i.e., solution and sputtering depositions) to yield three morphologically different titania electron transport layers (i.e., planar bulk TiO 2 , mesoporous TiO x , and sputtered TiO 2 ). We find that the most important factors affecting the PCEs in perovskite solar cells are related to trap-assisted recombination and energy level alignment due to variations in the electron transport layer/perovskite interface. Similarly, we observe that morphologies of both the electron transport layer and the perovskite active layer play a minor role on the observed PCEs.

Reaction of trifluoro-l,2,4-triazine with hexafluoropropene and caesium fluoride in the absence of solvent leads to successive replacement of fluorine by perfluoroisopropyl groups to give 5-mmo-, 35and possibly 3,6-di-, and tri-substituted derivatives. Similarly, perfluoro-2-azapropene yields 5and some 6-, 3,6-bis-, and tris-perfluorodimethylamino-derivatives. Pyrolysis of trifluoro-l,2,4-triazine at 500 "C/42 h yields trifluoro-l,3,5-triazine (32%) ; of perfluoro(tri-isopropyl-l,2,4-triazine) at 560 OC/O.26 s yields perfluoroisobutyronitrile and perfluoro-2,5-dimethylhex-3-yne ; and of perfluoro(trisdimathylamino-l,2,4-triazine) at 620 "C/2.4 s yields N,N-bis(trifluoromethy1)cyanamide and perfluorobis(dim3thylamino)acetylene.TRIFLUORO-1,2,4-TRIAZINE, readily prepared by the fluorobut-2-yne and fluoride ion,6 were less successful. vapour-phase fluorination of trichloro-l,2,4-triazine with Hexafluorocyclobutene and caesium fluoride with tripotassium fluoride,2 is a versatile and reactive com-fluoro-l,2,4-triazine yielded small amounts of a mixture pound, undergoing Diels-Alder addition with ole fin^,^ which contained by mass spectrometry, mono-, di-, and nucleophilic displacement of fluorine. Here we and tri-substituted compounds. Hexafluorobut-2-ync describe its successful perfluoroalkylation, and the and caesium fluoride yielded trace amounts of a. pyrolysis of its trisheptafluoroisopropyl and bistri-compound which may have been the trisubstituted

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