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Summary We present a new method for segmenting phase contrast images of NIH 3T3 fibroblast cells that is accurate even when cells are physically in contact with each other. The problem of segmentation, when cells are in contact, poses a challenge to the accurate automation of cell counting, tracking and lineage modelling in cell biology. The segmentation method presented in this paper consists of (1) background reconstruction to obtain noise-free foreground pixels and (2) incorporation of biological insight about dividing and nondividing cells into the segmentation process to achieve reliable separation of foreground pixels defined as pixels associated with individual cells. The segmentation results for a time-lapse image stack were compared against 238 manually segmented images (8219 cells) provided by experts, which we consider as reference data. We chose two metrics to measure the accuracy of segmentation: the ‘Adjusted Rand Index’ which compares similarities at a pixel level between masks resulting from manual and automated segmentation, and the ‘Number of Cells per Field’ (NCF) which compares the number of cells identified in the field by manual versus automated analysis. Our results show that the automated segmentation compared to manual segmentation has an average adjusted rand index of 0.96 (1 being a perfect match), with a standard deviation of 0.03, and an average difference of the two numbers of cells per field equal to 5.39% with a standard deviation of 4.6%.

Fully fluorinated arylenevinylene polymers have been synthesized via a methodology based on the Stille cross-coupling reaction and characterized by FTIR spectroscopy and MALDI-TOF mass spectrometry. Investigation of thin film properties by cyclic voltammetry and ellipsometry shows that complete substitution of hydrogen atoms with fluorine atoms on the conjugated backbone of the poly(arylenevinylene)s results in a strong increase of the band gap.

Poly(arylenevinylene) polymers bearing fluorine atoms in the vinylene units were obtained by a Stille cross-coupling reaction of (E)-(1,2-difluoro-1,2-ethenediyl)bis(tributylstannane) with diiodoaryl derivatives. The introduction of fluorine atoms on the double bond of the stannane leads to polymers with relatively high molecular weights. Furthermore, the presence of fluorinated vinylene units changes the optical properties of the polymers and shifts the emission towards the blue region of the visible spectrum. A fluorinated analogue of MEH-PPV was obtained, and it shows photoluminescence that is considerably blueshifted, also in the solid state, relative to that found for nonfluorinated MEH-PPV and to other PPVs with fluorinated double bonds.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

A copolymer of 2,3,5,6-tetrafluoro-1,4-phenylenevinylene and 2,5-dioctyloxy-1,4-phenylenevinylene [co(TFPV-DOPV)], containing more than 60% of tetrafluorophenylenevinylene monomeric units, was synthesized by the Stille cross-coupling reaction. Its linear and nonlinear optical properties were investigated. Linear absorption and photoluminescence measurements performed on thin films and solution indicate interchain migration upon excitation. A copolymer of 2,3,5,6-tetrafluoro-1,4-phenylenevinylene and 2,5-dioctyloxy-1,4-phenylenevinylene [co(TFPV-DOPV)], containing more than 60% of tetrafluorophenylenevinylene monomeric units, was synthesized by the Stille cross-coupling reaction. Its linear and nonlinear optical properties were investigated. Linear absorption and photoluminescence measurements performed on thin films and solution indicate interchain migration upon excitation. The Z-scan technique was used to evaluate the third-order nonlinear susceptibility. A very high refractive nonlinearity was measured with a value one order of magnitude larger than that of the corresponding dialkoxy-substituted homopolymer.

Ullmann-like reductive coupling of 1,4-diiodo-2,3,5,6-tetrafluorobenzene, promoted by copper(I) thiophene-2-carboxylate in N -methylpyrrolidinone at room temperature, followed by treatment with lithium aluminum hydride in THF, allowed us to obtain fluorinated poly( para -phenylene) oligomers containing up to five aromatic rings with hydrogen atoms as terminal groups.

A straightforward and general procedure for the introduction of aryl and vinyl substituents in the 5 or 7 position of 8-hydroxyquinoline has been developed. The methodology presented is based upon the Suzuki cross-coupling reaction of aryl or vinyl halides with 5-(4,4,5,5-tetramethyl[1,3,2]dioxaborolan-2-yl)quinolin- 8-ol or 7-(4,4,5,5-tetramethyl[1,3,2]dioxaborolan-2-yl)quinolin-8- ol, respectively, that have been obtained regioselectively starting from 8-hydroxyquinoline