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Sarah E Lutz, Julian R Smith, Dae Hwan Kim, Carl V L Olson, Kyle Ellefsen, Jennifer M Bates, Sunil P Gandhi, Dritan Agalliu
Lymphocytes cross vascular boundaries via either disrupted tight junctions (TJs) or caveolae to induce tissue inflammation. In the CNS, Th17 lymphocytes cross the blood-brain barrier (BBB) before Th1 cells; yet this differential crossing is poorly understood. We have used intravital two-photon imaging of the spinal cord in wild-type and caveolae-deficient mice with fluorescently labeled endothelial tight junctions to determine how tight junction remodeling and caveolae regulate CNS entry of lymphocytes during the experimental autoimmune encephalomyelitis (EAE) model for multiple sclerosis...
November 21, 2017: Cell Reports
Jean-Marc Good, Michael Mahoney, Taisuke Miyazaki, Kenji F Tanaka, Kenji Sakimura, Masahiko Watanabe, Kazuo Kitamura, Masanobu Kano
Neural circuits undergo massive refinements during postnatal development. In the developing cerebellum, the climbing fiber (CF) to Purkinje cell (PC) network is drastically reshaped by eliminating early-formed redundant CF to PC synapses. To investigate the impact of CF network refinement on PC population activity during postnatal development, we monitored spontaneous CF responses in neighboring PCs and the activity of populations of nearby CF terminals using in vivo two-photon calcium imaging. Population activity is highly synchronized in newborn mice, and the degree of synchrony gradually declines during the first postnatal week in PCs and, to a lesser extent, in CF terminals...
November 21, 2017: Cell Reports
Joseph E Thomaz, Heather E Bailey, Michael D Fayer
The structural dynamics of a series of 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (CnmimNTf2, n = 2, 4, 6, 10: ethyl-Emim; butyl-Bmim; hexyl-Hmim; decyl-Dmim) room temperature ionic liquids confined in the pores of polyether sulfone (PES 200) membranes with an average pore size of ∼350 nm and in the bulk liquids were studied. Time correlated single photon counting measurements of the fluorescence of the fluorophore coumarin 153 (C153) were used to observe the time-dependent Stokes shift (solvation dynamics)...
November 21, 2017: Journal of Chemical Physics
Stavros Amanatidis, Bruce L Yoder, Ruth Signorell
The transmission of low-energy (<1.8 eV) photoelectrons through the shell of core-shell aerosol particles is studied for liquid squalane, squalene, and di-ethyl-hexyl-sebacate shells. The photoelectrons are exclusively formed in the core of the particles by two-photon ionization. The total photoelectron yield recorded as a function of shell thicknesses (1-80 nm) shows a bi-exponential attenuation. For all substances, the damping parameter for shell thicknesses below 15 nm lies around 8 to 9 nm and is tentatively assigned to the electron attenuation length at electron kinetic energies of ≲1 eV...
June 14, 2017: Journal of Chemical Physics
Kaushik D Nanda, Anna I Krylov
We present static polarizabilities and two-photon absorption (2PA) cross sections for the low-lying electronic states of prototypical diradicals such as benzynes and analogues of m-xylylene and p-quinodimethane computed with the spin-flip equation-of-motion coupled-cluster singles and doubles (EOM-SF-CCSD) method. The static polarizabilities were calculated as analytic second derivatives of the EOM energies, and the 2PA cross sections were calculated using the expectation-value approach. We explain the trends in the nonlinear responses of the SF target states by constructing few-states models based on truncated sum-over-states expressions for these nonlinear properties...
June 14, 2017: Journal of Chemical Physics
Kajari Bera, Christopher J Douglas, Renee R Frontiera
Singlet fission generates multiple excitons from a single photon, which in theory can result in solar cell efficiencies with values above the Shockley-Queisser limit. Understanding the molecular structural dynamics during singlet fission will help to fabricate efficient organic photovoltaic devices. Here we use femtosecond stimulated Raman spectroscopy to reveal the structural evolution during the triplet separation in rubrene. We observe vibrational signatures of the correlated triplet pair, as well as shifting of the vibrational frequencies of the 1430 and 1542 cm(-1) excited state modes, which increase by more than 25 cm(-1) in 5 ps...
November 22, 2017: Journal of Physical Chemistry Letters
Andrew Sevy, Robert F Huffaker, Michael D Morse
Resonant two-photon ionization spectroscopy has been used to locate predissociation thresholds in WC, WSi, WS, WSe, and WCl, allowing bond dissociation energies to be measured for these species. Because of the high degree of vibronic congestion in the observed spectra, it is thought that the molecules dissociate as soon as the lowest separated atom limit is exceeded. From the observed predissociation thresholds, dissociation energies are assigned as D0(WC) = 5.289(8) eV, D0(WSi) = 3.103(10) eV, D0(WS) = 4.935(3) eV, D0(WSe) = 4...
November 22, 2017: Journal of Physical Chemistry. A
Yongjoon Heo, Su Yeon Lee, Ji-Won Kim, Tae Yoon Jeon, Shin-Hyun Kim
Inverse opals have been used for structural coloration and photonic applications owing to their photonic bandgap properties. When the photonic structures contain planar defects, they provide defect modes, which are useful for lasing, sensing, and waveguiding. However, it remains a challenge to insert a planar defect into inverse opals in a reproducible manner. Here, we report a new method for producing planar-defect-inserted inverse opals using sequential capillary wetting of colloidal crystals and creating micropatterns through photolithography...
November 22, 2017: ACS Applied Materials & Interfaces
Luiza Filipis, Karima Ait Ouares, Philippe Moreau, Dimitrii Tanese, Valeria Zampini, Andrea Latini, Chun Bleau, Charlie Bleau, Jeremy Graham, Marco Canepari
In brain slices, resolving fast Ca(2+) fluorescence signals from submicron structures is typically achieved using two-photon or confocal scanning microscopy, an approach that limits the number of scanned points. The novel multiplexing confocal system presented here overcomes this limitation. This system is based on a fast spinning disk, a multimode diode laser and a novel high-resolution CMOS camera. The spinning disk, running at 20,000 rpm, has custom-designed spiral pattern that maximises light collection while rejecting out-of-focus fluorescence to resolve signals from small neuronal compartments...
November 22, 2017: Journal of Biophotonics
Ž Kneževic, I Ambrozova, C Domingo, M De Saint-Hubert, M Majer, I Martínez-Rovira, S Miljanic, N Mojzeszek, P Porwol, O Ploc, M Romero-Expósito, L Stolarczyk, S Trinkl, R M Harrison, P Olko
Proton beam therapy has advantages in comparison to conventional photon radiotherapy due to the physical properties of proton beams (e.g. sharp distal fall off, adjustable range and modulation). In proton therapy, there is the possibility of sparing healthy tissue close to the target volume. This is especially important when tumours are located next to critical organs and while treating cancer in paediatric patients. On the other hand, the interactions of protons with matter result in the production of secondary radiation, mostly neutrons and gamma radiation, which deposit their energy at a distance from the target...
November 18, 2017: Radiation Protection Dosimetry
Feng Liu, Jing-Min Zhao, Hui-Ying Rao, Wei-Miao Yu, Wei Zhang, Neil D Theise, Aileen Wee, Lai Wei
Objectives: Investigate subtle fibrosis similarities and differences in adult and pediatric nonalcoholic fatty liver disease (NAFLD) using second harmonic generation (SHG). Methods: SHG/two-photon excitation fluorescence imaging quantified 100 collagen parameters and determined qFibrosis values by using the nonalcoholic steatohepatitis (NASH) Clinical Research Network (CRN) scoring system in 62 adult and 36 pediatric NAFLD liver specimens. Results: Six distinct parameters identified differences among the NASH CRN stages with high accuracy (area under the curve, 0835-0...
November 20, 2017: American Journal of Clinical Pathology
Hamed Arami, Eric Teeman, Alyssa Troksa, Haydin Bradshaw, Katayoun Saatchi, Asahi Tomitaka, Sanjiv Sam Gambhir, Urs O Häfeli, Denny Liggitt, Kannan M Krishnan
Magnetic Particle Imaging (MPI) is an emerging, whole body biomedical imaging technique, with sub-millimeter spatial resolution and high sensitivity to a biocompatible contrast agent consisting of an iron oxide nanoparticle core and a biofunctionalized shell. Successful application of MPI for imaging of cancer depends on the nanoparticles (NPs) accumulating at tumors at sufficient levels relative to other sites. NPs' physiochemical properties such as size, crystallographic structure and uniformity, surface coating, stability, blood circulation time and magnetization determine the efficacy of their tumor accumulation and MPI signal generation...
November 22, 2017: Nanoscale
Bernadette M Broderick, Nicolas Suas-David, Nureshan Dias, Arthur G Suits
Isomer-specific detection and product branching fractions in the UV photodissociation of the propargyl radical is achieved through the use of chirped-pulse Fourier-transform mm-wave spectroscopy in a pulsed quasi-uniform flow (CPUF). Propargyl radicals are produced in the 193 nm photodissociation of 1,2-butadiene. Absorption of a second photon leads to H atom elimination giving three possible C3H2 isomers: singlets cyclopropenylidene (c-C3H2) and propadienylidene (l-C3H2), and triplet propargylene ((3)HCCCH)...
November 22, 2017: Physical Chemistry Chemical Physics: PCCP
Steven Lukman, Johannes M Richter, Le Yang, Pan Hu, Jishan Wu, Neil C Greenham, Andrew J Musser
Singlet fission offers the potential to overcome thermodynamic limits in solar cells by converting the energy of a single absorbed photon into two distinct triplet excitons. However, progress is limited by the small family of suitable materials, and new chromophore design principles are needed. Here, we experimentally vindicate the design concept of diradical stabilisation, in a tuneable family of functionalised zethrenes. All molecules in the series exhibit rapid formation of a bound, spin-entangled triplet-pair state TT...
November 22, 2017: Journal of the American Chemical Society
Mayank Puri, Vivian E Ferry
Chiral semiconductor nanocrystals, or quantum dots (QDs), are promising materials for applications in biological sensing, photonics, and spin-polarized devices. Many of these applications rely on large dissymmetry, or g-factors, the difference in absorbance between left- and right-handed circularly polarized light compared to the unpolarized absorbance. The majority of chiral QDs, specifically CdSe, reported to date have used thiolated amino acid ligands to introduce chirality onto the nanoparticles, but these systems have ultimately reported small g-factors of ∼2 × 10(-4)...
November 22, 2017: ACS Nano
Kallol Roy, Tanweer Ahmed, Harshit Dubey, T Phanindra Sai, Ranjit Kashid, Shruti Maliakal, Kimberly Hsieh, Saquib Shamim, Arindam Ghosh
Van der Waals hybrids of graphene and transition metal dichalcogenides exhibit an extremely large response to optical excitation, yet counting of photons with single-photon resolution is not achieved. Here, a dual-gated bilayer graphene (BLG) and molybdenum disulphide (MoS2 ) hybrid are demonstrated, where opening a band gap in the BLG allows extremely low channel (receiver) noise and large optical gain (≈10(10) ) simultaneously. The resulting device is capable of unambiguous determination of the Poissonian emission statistics of an optical source with single-photon resolution at an operating temperature of 80 K, dark count rate 0...
November 22, 2017: Advanced Materials
Kyoungjune Pak, Keunyoung Kim, Myung Jun Lee, Jae Meen Lee, Bum Soo Kim, Seong-Jang Kim, In Joo Kim
OBJECTIVES: Olfactory dysfunction in Parkinson's disease is usually prodromal to other symptoms. In this study, we aimed to explore the association of olfactory function with the availabilities of striatal dopamine transporter (DAT) in healthy subjects. METHODS: Data used in the preparation of this article were obtained from Parkinson's Progression Markers Initiative database ( ). The study population consisted of healthy controls with screening (123)I-FP-CIT single photon emission tomography (SPECT)...
November 21, 2017: European Radiology
Fan-Li Meng, Jiao-Jiao Wu, Er-Fei Zhao, Yan-Zhen Zheng, Mei-Lan Huang, Li-Ming Dai, Xia Tao, Jian-Feng Chen
Integration of the upconversion effect in perovskite solar cells (PSCs) is a facile approach towards extending the spectral absorption from the visible to the near infrared (NIR) range and reducing the non-absorption loss of solar photons. However, the big challenge for practical application of UCNCs in planar PSCs is the poor compatibility between UCNCs and the perovskite precursor. Herein, we have subtly overcome the tough compatibility issue using a ligand-exchange strategy. For the first time, β-NaYF4:Yb,Er UCNCs have been embedded in situ into a CH3NH3PbI3 layer to fabricate NIR-enabled planar PSCs...
November 22, 2017: Nanoscale
Kai Liu, Amir Mokhtare, Xiaozheng Xue, Edward P Furlani
We study the field-directed self-assembly and photothermal behavior of one-dimensional (1D) chains of core-shell Fe3O4@Au magnetic-plasmonic nanoparticles. Monte Carlo analysis is used to predict the self-assembly of the nanoparticles when they are subjected to a uniform magnetic field and confined to a fluidic nanochannel. A coupled photonic and thermodynamic analysis is performed to analyze the optical and photothermal properties of the 1D chain structures. We show for the first time that the assembled chain structures exhibit a pronounced dip in their absorption spectrum at a wavelength that is strongly sensitive to changes in the refractive index of the surrounding medium...
November 22, 2017: Physical Chemistry Chemical Physics: PCCP
Mingdao Zhang, Gang Wang, Danxia Zhao, Chengyan Huang, Hui Cao, Mindong Chen
Over the past five years, perovskite solar cells (PSCs) have gained intense worldwide attention in the photovoltaic community due to their low cost and high power conversion efficiencies (PCEs). One of the most significant issues in achieving high PCEs of PSCs is the development of suitable low-cost hole-transporting materials (HTMs). Here, we put forward a new concept of HTMs for PSCs: a 3D structure with a core of coplanar quinolizino acridine, derived from the conventional concept of 2D triphenylamine HTMs...
November 1, 2017: Chemical Science
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