The relation of object naming and other visual speech production tasks: A large scale voxel-based morphometric study.

We report a lesion–symptom mapping analysis of visual speech production deficits in a large group (280) of stroke patients at the sub-acute stage (<120 days post-stroke). Performance on object naming was evaluated alongside three other tests of visual speech production, namely sentence production to a picture, sentence reading and nonword reading. A principal component analysis was performed on all these tests' scores and revealed a ‘shared’ component that loaded across all the visual speech production tasks and a ‘unique’ component that isolated object naming from the other three tasks. Regions for the shared component were observed in the left fronto-temporal cortices, fusiform gyrus and bilateral visual cortices. Lesions in these regions linked to both poor object naming and impairment in general visual–speech production. On the other hand, the unique naming component was potentially associated with the bilateral anterior temporal poles, hippocampus and cerebellar areas. This is in line with the models proposing that object naming relies on a left-lateralised language dominant system that interacts with a bilateral anterior temporal network. Neuropsychological deficits in object naming can reflect both the increased demands specific to the task and the more general difficulties in language processing

Molecular phylogenetics reveal multiple tertiary vicariance origins of the African rain forest trees

Background - Tropical rain forests are the most diverse terrestrial ecosystems on the planet. How this diversity evolved remains largely unexplained. In Africa, rain forests are situated in two geographically isolated regions: the West-Central Guineo-Congolian region and the coastal and montane regions of East Africa. These regions have strong floristic affinities with each other, suggesting a former connection via an Eocene pan-African rain forest. High levels of endemism observed in both regions have been hypothesized to be the result of either 1) a single break-up followed by a long isolation or 2) multiple fragmentation and reconnection since the Oligocene. To test these hypotheses the evolutionary history of endemic taxa within a rain forest restricted African lineage of the plant family Annonaceae was studied. Molecular phylogenies and divergence dates were estimated using a Bayesian relaxed uncorrelated molecular clock assumption accounting for both calibration and phylogenetic uncertainties. Results - Our results provide strong evidence that East African endemic lineages of Annonaceae have multiple origins dated to significantly different times spanning the Oligocene and Miocene epochs. Moreover, these successive origins (c. 33, 16 and 8 million years ¿ Myr) coincide with known periods of aridification and geological activity in Africa that would have recurrently isolated the Guineo-Congolian rain forest from the East African one. All East African taxa were found to have diversified prior to Pleistocene times. Conclusion - Molecular phylogenetic dating analyses of this large pan-African clade of Annonaceae unravels an interesting pattern of diversification for rain forest restricted trees co-occurring in West/Central and East African rain forests. Our results suggest that repeated reconnections between the West/Central and East African rain forest blocks allowed for biotic exchange while the break-ups induced speciation via vicariance, enhancing the levels of endemicity. These results provide an explanation for present day distribution patterns and origins of endemicity for African rain forest trees. Moreover, given the pre-Pleistocene origins of all the studied endemic East African genera and species, these results also offer important insights for setting conservation priorities in these highly diversified but threatene

Optical chemosensors and reagents to detect explosives

[EN] This critical review is focused on examples reported from 1947 to 2010 related to the design of chromo-fluorogenic chemosensors and reagents for explosives (141 references). © 2012 The Royal Society of Chemistry.Financial support from the Spanish Government (project MAT2009-14564-C04) and the Generalitat Valencia (project PROMETEO/2009/016) is gratefully acknowledged. Y.S. is grateful to the Spanish Ministry of Science and Innovation for her grant.Salinas Soler, Y.; Martínez Mañez, R.; Marcos Martínez, MD.; Sancenón Galarza, F.; Costero Nieto, AM.; Parra Álvarez, M.; Gil Grau, S. (2012). Optical chemosensors and reagents to detect explosives. Chemical Society Reviews. 41(3):1261-1296. https://doi.org/10.1039/c1cs15173hS12611296413Furton, K. (2001). The scientific foundation and efficacy of the use of canines as chemical detectors for explosives. Talanta, 54(3), 487-500. doi:10.1016/s0039-9140(00)00546-4H�kansson, K., Coorey, R. V., Zubarev, R. A., Talrose, V. L., & H�kansson, P. (2000). Low-mass ions observed in plasma desorption mass spectrometry of high explosives. Journal of Mass Spectrometry, 35(3), 337-346. doi:10.1002/(sici)1096-9888(200003)35:33.0.co;2-7Walsh, M. (2001). Determination of nitroaromatic, nitramine, and nitrate ester explosives in soil by gas chromatography and an electron capture detector. Talanta, 54(3), 427-438. doi:10.1016/s0039-9140(00)00541-5Sylvia, J. M., Janni, J. A., Klein, J. D., & Spencer, K. M. (2000). Surface-Enhanced Raman Detection of 2,4-Dinitrotoluene Impurity Vapor as a Marker To Locate Landmines. Analytical Chemistry, 72(23), 5834-5840. doi:10.1021/ac0006573Yinon, J. (1982). Mass spectrometry of explosives: Nitro compounds, nitrate esters, and nitramines. Mass Spectrometry Reviews, 1(3), 257-307. doi:10.1002/mas.1280010304Mathurin, J. C., Faye, T., Brunot, A., Tabet, J. C., Wells, G., & Fuché, C. (2000). High-Pressure Ion Source Combined with an In-Axis Ion Trap Mass Spectrometer. 1. Instrumentation and Applications. Analytical Chemistry, 72(20), 5055-5062. doi:10.1021/ac000171mHallowell, S. (2001). Screening people for illicit substances: a survey of current portal technology. Talanta, 54(3), 447-458. doi:10.1016/s0039-9140(00)00543-9Vourvopoulos, G. (2001). Pulsed fast/thermal neutron analysis: a technique for explosives detection. Talanta, 54(3), 459-468. doi:10.1016/s0039-9140(00)00544-0Krausa, M., & Schorb, K. (1999). Trace detection of 2,4,6-trinitrotoluene in the gaseous phase by cyclic voltammetry. Journal of Electroanalytical Chemistry, 461(1-2), 10-13. doi:10.1016/s0022-0728(98)00162-4Steinfeld, J. I., & Wormhoudt, J. (1998). EXPLOSIVES DETECTION: A Challenge for Physical Chemistry. Annual Review of Physical Chemistry, 49(1), 203-232. doi:10.1146/annurev.physchem.49.1.203Moore, D. S. (2004). Instrumentation for trace detection of high explosives. Review of Scientific Instruments, 75(8), 2499-2512. doi:10.1063/1.1771493Martínez-Máñez, R., Sancenón, F., Hecht, M., Biyikal, M., & Rurack, K. (2010). Nanoscopic optical sensors based on functional supramolecular hybrid materials. Analytical and Bioanalytical Chemistry, 399(1), 55-74. doi:10.1007/s00216-010-4198-2Moragues, M. E., Martínez-Máñez, R., & Sancenón, F. (2011). Chromogenic and fluorogenic chemosensors and reagents for anions. A comprehensive review of the year 2009. Chemical Society Reviews, 40(5), 2593. doi:10.1039/c0cs00015aMartínez-Máñez, R., & Sancenón, F. (2005). New Advances in Fluorogenic Anion Chemosensors. Journal of Fluorescence, 15(3), 267-285. doi:10.1007/s10895-005-2626-zXu, Z., Chen, X., Kim, H. N., & Yoon, J. (2010). Sensors for the optical detection ofcyanide ion. Chem. Soc. Rev., 39(1), 127-137. doi:10.1039/b907368jNolan, E. M., & Lippard, S. J. (2008). Tools and Tactics for the Optical Detection of Mercuric Ion. Chemical Reviews, 108(9), 3443-3480. doi:10.1021/cr068000qPallavicini, P., Diaz-Fernandez, Y. A., & Pasotti, L. (2009). Micelles as nanosized containers for the self-assembly of multicomponent fluorescent sensors. Coordination Chemistry Reviews, 253(17-18), 2226-2240. doi:10.1016/j.ccr.2008.11.010Que, E. L., & Chang, C. J. (2010). Responsive magnetic resonance imaging contrast agents as chemical sensors for metals in biology and medicine. Chem. Soc. Rev., 39(1), 51-60. doi:10.1039/b914348nMohr, G. J. (2004). Tailoring the sensitivity and spectral properties of a chromoreactand for the detection of amines and alcohols. Analytica Chimica Acta, 508(2), 233-237. doi:10.1016/j.aca.2003.12.005Martínez-Máñez, R., & Sancenón, F. (2003). Fluorogenic and Chromogenic Chemosensors and Reagents for Anions. Chemical Reviews, 103(11), 4419-4476. doi:10.1021/cr010421eJ. P. Agrawal and R. D.Hodgson, Organic Chemistry of Explosives, John Wiley & Sons, Chichester, 2007, ISBN-13, 978, 0-470-02967-1, HBCumming, C. J., Aker, C., Fisher, M., Fok, M., la Grone, M. J., Reust, D., … Williams, V. (2001). Using novel fluorescent polymers as sensory materials for above-ground sensing of chemical signature compounds emanating from buried landmines. IEEE Transactions on Geoscience and Remote Sensing, 39(6), 1119-1128. doi:10.1109/36.927423Toal, S. J., & Trogler, W. C. (2006). Polymer sensors for nitroaromatic explosives detection. Journal of Materials Chemistry, 16(28), 2871. doi:10.1039/b517953jMcQuade, D. T., Pullen, A. E., & Swager, T. M. (2000). Conjugated Polymer-Based Chemical Sensors. Chemical Reviews, 100(7), 2537-2574. doi:10.1021/cr9801014Zhou, Q., & Swager, T. M. (1995). Method for enhancing the sensitivity of fluorescent chemosensors: energy migration in conjugated polymers. Journal of the American Chemical Society, 117(26), 7017-7018. doi:10.1021/ja00131a031Yang, J.-S., & Swager, T. M. (1998). Porous Shape Persistent Fluorescent Polymer Films:  An Approach to TNT Sensory Materials. Journal of the American Chemical Society, 120(21), 5321-5322. doi:10.1021/ja9742996Yang, J.-S., & Swager, T. M. (1998). Fluorescent Porous Polymer Films as TNT Chemosensors:  Electronic and Structural Effects. Journal of the American Chemical Society, 120(46), 11864-11873. doi:10.1021/ja982293qYamaguchi, S., & Swager, T. M. (2001). Oxidative Cyclization of Bis(biaryl)acetylenes:  Synthesis and Photophysics of Dibenzo[g,p]chrysene-Based Fluorescent Polymers. Journal of the American Chemical Society, 123(48), 12087-12088. doi:10.1021/ja016692oZahn, S., & Swager, T. M. (2002). Three-Dimensional Electronic Delocalization in Chiral Conjugated Polymers. Angewandte Chemie International Edition, 41(22), 4225-4230. doi:10.1002/1521-3773(20021115)41:223.0.co;2-3Amara, J. P., & Swager, T. M. (2005). Synthesis and Properties of Poly(phenylene ethynylene)s with Pendant Hexafluoro-2-propanol Groups. Macromolecules, 38(22), 9091-9094. doi:10.1021/ma051562bZhao, D., & Swager, T. M. (2005). Sensory Responses in Solution vs Solid State:  A Fluorescence Quenching Study of Poly(iptycenebutadiynylene)s. Macromolecules, 38(22), 9377-9384. doi:10.1021/ma051584yThomas III, S. W., Amara, J. P., Bjork, R. E., & Swager, T. M. (2005). Amplifying fluorescent polymer sensors for the explosives taggant 2,3-dimethyl-2,3-dinitrobutane (DMNB). Chemical Communications, (36), 4572. doi:10.1039/b508408cNarayanan, A., Varnavski, O. P., Swager, T. M., & Goodson, T. (2008). Multiphoton Fluorescence Quenching of Conjugated Polymers for TNT Detection. The Journal of Physical Chemistry C, 112(4), 881-884. doi:10.1021/jp709662wChen, S., Zhang, Q., Zhang, J., Gu, J., & Zhang, L. (2010). Synthesis of two conjugated polymers as TNT chemosensor materials. Sensors and Actuators B: Chemical, 149(1), 155-160. doi:10.1016/j.snb.2010.06.007Long, Y., Chen, H., Yang, Y., Wang, H., Yang, Y., Li, N., … Liu, F. (2009). Electrospun Nanofibrous Film Doped with a Conjugated Polymer for DNT Fluorescence Sensor. Macromolecules, 42(17), 6501-6509. doi:10.1021/ma900756wChang, C.-P., Chao, C.-Y., Huang, J. H., Li, A.-K., Hsu, C.-S., Lin, M.-S., … Su, A.-C. (2004). Fluorescent conjugated polymer films as TNT chemosensors. Synthetic Metals, 144(3), 297-301. doi:10.1016/j.synthmet.2004.04.003Levitsky, I. A., Euler, W. B., Tokranova, N., & Rose, A. (2007). Fluorescent polymer-porous silicon microcavity devices for explosive detection. Applied Physics Letters, 90(4), 041904. doi:10.1063/1.2432247Chen, L., McBranch, D., Wang, R., & Whitten, D. (2000). Surfactant-induced modification of quenching of conjugated polymer fluorescence by electron acceptors: applications for chemical sensing. Chemical Physics Letters, 330(1-2), 27-33. doi:10.1016/s0009-2614(00)00970-2Rose, A., Zhu, Z., Madigan, C. F., Swager, T. M., & Bulović, V. (2005). Sensitivity gains in chemosensing by lasing action in organic polymers. Nature, 434(7035), 876-879. doi:10.1038/nature03438Tamao, K., Uchida, M., Izumizawa, T., Furukawa, K., & Yamaguchi, S. (1996). Silole Derivatives as Efficient Electron Transporting Materials. Journal of the American Chemical Society, 118(47), 11974-11975. doi:10.1021/ja962829cSohn, H., Huddleston, R. R., Powell, D. R., West, R., Oka, K., & Yonghua, X. (1999). An Electroluminescent Polysilole and Some Dichlorooligosiloles. Journal of the American Chemical Society, 121(12), 2935-2936. doi:10.1021/ja983350iOhshita, J., & Kunai, A. (1998). Polymers with alternating organosilicon and π-conjugated units. Acta Polymerica, 49(8), 379-403. doi:10.1002/(sici)1521-4044(199808)49:83.0.co;2-zToal, S. J., Magde, D., & Trogler, W. C. (2005). Luminescent oligo(tetraphenyl)silole nanoparticles as chemical sensors for aqueous TNT. Chemical Communications, (43), 5465. doi:10.1039/b509404fSohn, H., Sailor, M. J., Magde, D., & Trogler, W. C. (2003). Detection of Nitroaromatic Explosives Based on Photoluminescent Polymers Containing Metalloles. Journal of the American Chemical Society, 125(13), 3821-3830. doi:10.1021/ja021214eSanchez, J. C., DiPasquale, A. G., Rheingold, A. L., & Trogler, W. C. (2007). Synthesis, Luminescence Properties, and Explosives Sensing with 1,1-Tetraphenylsilole- and 1,1-Silafluorene-vinylene Polymers. Chemistry of Materials, 19(26), 6459-6470. doi:10.1021/cm702299gSanchez, J. C., Urbas, S. A., Toal, S. J., DiPasquale, A. G., Rheingold, A. L., & Trogler, W. C. (2008). Catalytic Hydrosilylation Routes to Divinylbenzene Bridged Silole and Silafluorene Polymers. Applications to Surface Imaging of Explosive Particulates. Macromolecules, 41(4), 1237-1245. doi:10.1021/ma702274cSanchez, J. C., & Trogler, W. C. (2008). Efficient blue-emitting silafluorene–fluorene-conjugated copolymers: selective turn-off/turn-on detection of explosives. Journal of Materials Chemistry, 18(26), 3143. doi:10.1039/b802623hLiu, J., Zhong, Y., Lam, J. W. Y., Lu, P., Hong, Y., Yu, Y., … Tang, B. Z. (2010). Hyperbranched Conjugated Polysiloles: Synthesis, Structure, Aggregation-Enhanced Emission, Multicolor Fluorescent Photopatterning, and Superamplified Detection of Explosives. Macromolecules, 43(11), 4921-4936. doi:10.1021/ma902432mLu, P., Lam, J. W. Y., Liu, J., Jim, C. K. W., Yuan, W., Xie, N., … Tang, B. Z. (2010). Aggregation-Induced Emission in a Hyperbranched Poly(silylenevinylene) and Superamplification in Its Emission Quenching by Explosives. Macromolecular Rapid Communications, 31(9-10), 834-839. doi:10.1002/marc.200900794Liu, Y., Mills, R. C., Boncella, J. M., & Schanze, K. S. (2001). Fluorescent Polyacetylene Thin Film Sensor for Nitroaromatics. Langmuir, 17(24), 7452-7455. doi:10.1021/la010696pToy, L. G., Nagai, K., Freeman, B. D., Pinnau, I., He, Z., Masuda, T., … Yampolskii, Y. P. (2000). Pure-Gas and Vapor Permeation and Sorption Properties of Poly[1-phenyl-2-[p-(trimethylsilyl)phenyl]acetylene] (PTMSDPA). Macromolecules, 33(7), 2516-2524. doi:10.1021/ma991566eSaxena, A., Fujiki, M., Rai, R., & Kwak, G. (2005). Fluoroalkylated Polysilane Film as a Chemosensor for Explosive Nitroaromatic Compounds. Chemistry of Materials, 17(8), 2181-2185. doi:10.1021/cm048319wSaxena, A., Rai, R., Kim, S.-Y., Fujiki, M., Naito, M., Okoshi, K., & Kwak, G. (2006). Weak noncovalent Si···FC interactions stabilized fluoroalkylated rod-like polysilanes as ultrasensitive chemosensors. Journal of Polymer Science Part A: Polymer Chemistry, 44(17), 5060-5075. doi:10.1002/pola.21607Toal, S. J., Sanchez, J. C., Dugan, R. E., & Trogler, W. C. (2007). Visual Detection of Trace Nitroaromatic Explosive Residue Using Photoluminescent Metallole-Containing Polymers. Journal of Forensic Sciences, 52(1), 79-83. doi:10.1111/j.1556-4029.2006.00332.xStringer, R. C., Gangopadhyay, S., & Grant, S. A. (2010). Detection of Nitroaromatic Explosives Using a Fluorescent-Labeled Imprinted Polymer. Analytical Chemistry, 82(10), 4015-4019. doi:10.1021/ac902838cLi, J., Kendig, C. E., & Nesterov, E. E. (2007). Chemosensory Performance of Molecularly Imprinted Fluorescent Conjugated Polymer Materials. Journal of the American Chemical Society, 129(51), 15911-15918. doi:10.1021/ja0748027Bunte, G., Hürttlen, J., Pontius, H., Hartlieb, K., & Krause, H. (2007). Gas phase detection of explosives such as 2,4,6-trinitrotoluene by molecularly imprinted polymers. Analytica Chimica Acta, 591(1), 49-56. doi:10.1016/j.aca.2007.02.014Zhang, X., & Jenekhe, S. A. (2000). Electroluminescence of Multicomponent Conjugated Polymers. 1. Roles of Polymer/Polymer Interfaces in Emission Enhancement and Voltage-Tunable Multicolor Emission in Semiconducting Polymer/Polymer Heterojunctions. Macromolecules, 33(6), 2069-2082. doi:10.1021/ma991913kHou, S., Ding, M., & Gao, L. (2003). Synthesis and Properties of Polyquinolines and Polyanthrazolines Containing Pyrrole Units in the Main Chain. Macromolecules, 36(11), 3826-3832. doi:10.1021/ma025768dKim, T. H., Kim, H. J., Kwak, C. G., Park, W. H., & Lee, T. S. (2006). Aromatic oxadiazole-based conjugated polymers with excited-state intramolecular proton transfer: Their synthesis and sensing ability for explosive nitroaromatic compounds. Journal of Polymer Science Part A: Polymer Chemistry, 44(6), 2059-2068. doi:10.1002/pola.21319Nie, H., Zhao, Y., Zhang, M., Ma, Y., Baumgarten, M., & Müllen, K. (2011). Detection of TNT explosives with a new fluorescent conjugated polycarbazole polymer. Chem. Commun., 47(4), 1234-1236. doi:10.1039/c0cc03659eQin, A., Lam, J. W. Y., Tang, L., Jim, C. K. W., Zhao, H., Sun, J., & Tang, B. Z. (2009). Polytriazoles with Aggregation-Induced Emission Characteristics: Synthesis by Click Polymerization and Application as Explosive Chemosensors. Macromolecules, 42(5), 1421-1424. doi:10.1021/ma8024706Kumar, A., Pandey, M. K., Anandakathir, R., Mosurkal, R., Parmar, V. S., Watterson, A. C., & Kumar, J. (2010). Sensory response of pegylated and siloxanated 4,8-dimethylcoumarins: A fluorescence quenching study by nitro aromatics. Sensors and Actuators B: Chemical, 147(1), 105-110. doi:10.1016/j.snb.2010.02.004Nguyen, H. H., Li, X., Wang, N., Wang, Z. Y., Ma, J., Bock, W. J., & Ma, D. (2009). Fiber-Optic Detection of Explosives Using Readily Available Fluorescent Polymers. Macromolecules, 42(4), 921-926. doi:10.1021/ma802460qAlbert, K. J., & Walt, D. R. (2000). High-Speed Fluorescence Detection of Explosives-like Vapors. Analytical Chemistry, 72(9), 1947-1955. doi:10.1021/ac991397wGao, D., Wang, Z., Liu, B., Ni, L., Wu, M., & Zhang, Z. (2008). Resonance Energy Transfer-Amplifying Fluorescence Quenching at the Surface of Silica Nanoparticles toward Ultrasensitive Detection of TNT. Analytical Chemistry, 80(22), 8545-8553. doi:10.1021/ac8014356Fang, Q., Geng, J., Liu, B., Gao, D., Li, F., Wang, Z., … Zhang, Z. (2009). Inverted Opal Fluorescent Film Chemosensor for the Detection of Explosive Nitroaromatic Vapors through Fluorescence Resonance Energy Transfer. Chemistry - A European Journal, 15(43), 11507-11514. doi:10.1002/chem.200901488Geng, J., Liu, P., Liu, B., Guan, G., Zhang, Z., & Han, M.-Y. (2010). A Reversible Dual-Response Fluorescence Switch for the Detection of Multiple Analytes. Chemistry - A European Journal, 16(12), 3720-3727. doi:10.1002/chem.200902721Yang, J., Aschemeyer, S., Martinez, H. P., & Trogler, W. C. (2010). Hollow silica nanospheres containing a silafluorene–fluorene conjugated polymer for aqueous TNT and RDX detection. Chemical Communications, 46(36), 6804. doi:10.1039/c0cc01906bFeng, J., Li, Y., & Yang, M. (2010). Conjugated polymer-grafted silica nanoparticles for the sensitive detection of TNT. Sensors and Actuators B: Chemical, 145(1), 438-443. doi:10.1016/j.snb.2009.12.056Tao, S., Shi, Z., Li, G., & Li, P. (2006). Hierarchically Structured Nanocomposite Films as Highly Sensitive Chemosensory Materials for TNT Detection. ChemPhysChem, 7(9), 1902-1905. doi:10.1002/cphc.200600185Tao, S., Yin, J., & Li, G. (2008). High-performance TNT chemosensory materials based on nanocomposites with bimodal porous structures. Journal of Materials Chemistry, 18(40), 4872. doi:10.1039/b802486cTao, S., Li, G., & Zhu, H. (2006). Metalloporphyrins as sensing elements for the rapid detection of trace TNT vapor. Journal of Materials Chemistry, 16(46), 4521. doi:10.1039/b606061gTao, S., & Li, G. (2007). Porphyrin-doped mesoporous silica films for rapid TNT detection. Colloid and Polymer Science, 285(7), 721-728. doi:10.1007/s00396-007-1643-7Yildirim, A., Budunoglu, H., Deniz, H., O. Guler, M., & Bayindir, M. (2010). Template-Free Synthesis of Organically Modified Silica Mesoporous Thin Films for TNT Sensing. ACS Applied Materials & Interfaces, 2(10), 2892-2897. doi:10.1021/am100568cLi, H., Wang, J., Pan, Z., Cui, L., Xu, L., Wang, R., … Jiang, L. (2011). Amplifying fluorescence sensing based on inverse opal photonic crystal toward trace TNT detection. J. Mater. Chem., 21(6), 1730-1735. doi:10.1039/c0jm02554bTao, S., Li, G., & Yin, J. (2007). Fluorescent nanofibrous membranes for trace detection of TNT vapor. Journal of Materials Chemistry, 17(26), 2730. doi:10.1039/b618122hNaddo, T., Che, Y., Zhang, W., Balakrishnan, K., Yang, X., Yen, M., … Zang, L. (2007). Detection of Explosives with a Fluorescent Nanofibril Film. Journal of the American Chemical Society, 129(22), 6978-6979. doi:10.1021/ja070747qContent, S., Trogler, W. C., & Sailor, M. J. (2000). Detection of Nitrobenzene, DNT, and TNT Vapors by Quenching of Porous Silicon Photoluminescence. Chemistry - A European Journal, 6(12), 2205-2213. doi:10.1002/1521-3765(20000616)6:123.0.co;2-aKang, J., Ding, L., Lü, F., Zhang, S., & Fang, Y. (2006). Dansyl-based fluorescent film sensor for nitroaromatics in aqueous solution. Journal of Physics D: Applied Physics, 39(23), 5097-5102. doi:10.1088/0022-3727/39/23/030Zhang, S., Lü, F., Gao, L., Ding, L., & Fang, Y. (2007). Fluorescent Sensors for Nitroaromatic Compounds Based on Monolayer Assembly of Polycyclic Aromatics. Langmuir, 23(3), 1584-1590. doi:10.1021/la062773sHe, G., Zhang, G., Lü, F., & Fang, Y. (2009). Fluorescent Film Sensor for Vapor-Phase Nitroaromatic Explosives via Monolayer Assembly of Oligo(diphenylsilane) on Glass Plate Surfaces. Chemistry of Materials, 21(8), 1494-1499. doi:10.1021/cm900013fGoodpaster, J. V., & McGuffin, V. L. (2001). Fluorescence Quenching as an Indirect Detection Method for Nitrated Explosives. Analytical Chemistry, 73(9), 2004-2011. doi:10.1021/ac001347nHughes, A. D., Glenn, I. C., Patrick, A. D., Ellington, A., & Anslyn, E. V. (2008). A Pattern Recognition Based Fluorescence Quenching Assay for the Detection and Identification of Nitrated Explosive Analytes. Chemistry - A European Journal, 14(6), 1822-1827. doi:10.1002/chem.200701546Malashikhin, S., & Finney, N. S. (2008). Fluorescent Signaling Based on Sulfoxide Profluorophores: Application to the Visual Detection of the Explosive TATP. Journal of the American Chemical Society, 130(39), 12846-12847. doi:10.1021/ja802989vFocsaneanu, K.-S., & Scaiano, J. C. (2005). Potential analytical applications of differential fluorescence quenching: pyrene monomer and excimer emissions as sensors for electron deficient molecules. Photochemical & Photobiological Sciences, 4(10), 817. doi:10.1039/b505249aLee, Y. H., Liu, H., Lee, J. Y., Kim, S. H., Kim, S. K., Sessler, J. L., … Kim, J. S. (2010). Dipyrenylcalix[4]arene-A Fluorescence-Based Chemosensor for Trinitroaromatic Explosives. Chemistry - A European Journal, 16(20), 5895-5901. doi:10.1002/chem.200903439Jian, C., & Seitz, W. R. (1990). Membrane for in situ optical detection of organic nitro compounds based on fluorescence quenching. Analytica Chimica Acta, 237, 265-271. doi:10.1016/s0003-2670(00)83928-8Vijayakumar, C., Tobin, G., Schmitt, W., Kim, M.-J., & Takeuchi, M. (2010). Detection of explosive vapors with a charge transfer molecule: self-assembly assisted morphology tuning and enhancement in sensing efficiency. Chemical Communications, 46(6), 874. doi:10.1039/b921520dZyryanov, G. V., Palacios, M. A., & Anzenbacher, P. (2008). Simple Molecule-Based Fluorescent Sensors for Vapor Detection of TNT. Organic Letters, 10(17), 3681-3684. doi:10.1021/ol801030uCavaye, H., Shaw, P. E., Wang, X., Burn, P. L., Lo, S.-C., & Meredith, P. (2010). Effect of Dimensionality in Dendrimeric and Polymeric Fluorescent Materials for Detecting Explosives. Macromolecules, 43(24), 10253-10261. doi:10.1021/ma102369qPonnu, A., & Anslyn, E. V. (2010). A fluorescence-based cyclodextrin sensor to detect nitroaromatic explosives. Supramolecular Chemistry, 22(1), 65-71. doi:10.1080/10610270903378032Zhang, C., Che, Y., Yang, X., Bunes, B. R., & Zang, L. (2010). Organic nanofibrils based on linear carbazole trimer for explosive sensing. Chemical Communications, 46(30), 5560. doi:10.1039/c0cc01258kLi, Z., Dong, Y. Q., Lam, J. W. Y., Sun, J., Qin, A., Häußler, M., … Tang, B. Z. (2009). Functionalized Siloles: Versatile Synthesis, Aggregation-Induced Emission, and Sensory and Device Applications. Advanced Functional Materials, 19(6), 905-917. doi:10.1002/adfm.20

Analysis of events with b-jets and a pair of leptons of the same charge in pp collisions at √s=8 TeV with the ATLAS detector

An analysis is presented of events containing jets including at least one b-tagged jet, sizeable missing transverse momentum, and at least two leptons including a pair of the same electric charge, with the scalar sum of the jet and lepton transverse momenta being large. A data sample with an integrated luminosity of 20.3 fb−1 of pp collisions at √s=8 TeV recorded by the ATLAS detector at the Large Hadron Collider is used. Standard Model processes rarely produce these final states, but there are several models of physics beyond the Standard Model that predict an enhanced rate of production of such events; the ones considered here are production of vector-like quarks, enhanced four-top-quark production, pair production of chiral b′-quarks, and production of two positively charged top quarks. Eleven signal regions are defined; subsets of these regions are combined when searching for each class of models. In the three signal regions primarily sensitive to positively charged top quark pair production, the data yield is consistent with the background expectation. There are more data events than expected from background in the set of eight signal regions defined for searching for vector-like quarks and chiral b′-quarks, but the significance of the discrepancy is less than two standard deviations. The discrepancy reaches 2.5 standard deviations in the set of five signal regions defined for searching for four-top-quark production. The results are used to set 95% CL limits on various models

Incorporating a prognostic representation of marine nitrogen fixers into the global ocean biogeochemical model HAMOCC

Nitrogen (N2) fixation is a major source of bioavailable nitrogen to the euphotic zone, thereby exerting an important control on ocean biogeochemical cycling. This paper presents the incorporation of prognostic N2 fixers into the HAMburg Ocean Carbon Cycle model (HAMOCC), a component of the Max Planck Institute Earth System Model (MPI‐ESM). Growth dynamics of N2 fixers in the model are based on physiological characteristics of the cyanobacterium Trichodesmium. The applied temperature dependency confines diazotrophic growth and N2 fixation to the tropical and subtropical ocean roughly between 40°S and 40°N. Simulated large‐scale spatial patterns compare well with observations, and the global N2 fixation rate of 135.6 Tg N yr−1 is within the range of current estimates. The vertical distribution of N2 fixation also matches well the observations, with a major fraction of about 85% occurring in the upper 20 m. The observed seasonal variability at the stations BATS and ALOHA is reasonably reproduced, with highest fixation rates in northern summer/fall. Iron limitation was found to be an important factor in controlling the simulated distribution of N2 fixation, especially in the Pacific Ocean. The new model component considerably improves the representation of present‐day N2 fixation in HAMOCC. It provides the basis for further studies on the role of diazotrophs in global biogeochemical cycles, as well as on the response of N2 fixation to changing environmental conditions

Morphing in nature and beyond: a review of natural and synthetic shape-changing materials and mechanisms

Shape-changing materials open an entirely new solution space for a wide range of disciplines: from architecture that responds to the environment and medical devices that unpack inside the body, to passive sensors and novel robotic actuators. While synthetic shape-changing materials are still in their infancy, studies of biological morphing materials have revealed key paradigms and features which underlie efficient natural shape-change. Here, we review some of these insights and how they have been, or may be, translated to artificial solutions. We focus on soft matter due to its prevalence in nature, compatibility with users and potential for novel design. Initially, we review examples of natural shape-changing materials—skeletal muscle, tendons and plant tissues—and compare with synthetic examples with similar methods of operation. Stimuli to motion are outlined in general principle, with examples of their use and potential in manufactured systems. Anisotropy is identified as a crucial element in directing shape-change to fulfil designed tasks, and some manufacturing routes to its achievement are highlighted. We conclude with potential directions for future work, including the simultaneous development of materials and manufacturing techniques and the hierarchical combination of effects at multiple length scales.</p