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Wenfei Zhang, Yiqun Ni, Xuhui Xu, Wei Lu, Pengpeng Ren, Peiguang Yan, Chun Kit Siu, Shuangchen Ruan, Siu Fung Yu
The use of organosilane chains to link carbon nanodots (CDs) through organosilane surface functional groups is proposed to improve the efficiency of multiphoton absorption. As a result, a large absorption coefficient of 1.16 × 10(-6) cm(5) per GW(3) is obtained and four-photon luminescence under 1900 nm excitation is observed from the CDs at room temperature. Furthermore, a CD laser, which demonstrates random lasing under three-photon (i.e. 1400 nm) excitation, can be realized by sandwiching a CD film between a quartz substrate and a dielectric mirror...
April 25, 2017: Nanoscale
Zhuojun Wu, Timo Rademakers, Fabian Kiessling, Michael Vogt, Erik Westein, Christian Weber, Remco Ta Megens, Marc van Zandvoort
Multiphoton laser scanning microscopy has proven profound value for ex vivo 3D histology and in vivo imaging of motionless tissue. The development of triggering systems and fast imaging methods, combined with advanced preparation procedures solved the challenging task of intravital imaging of the fast pulsating heart and major arteries in animals and further increased the popularity of intravital multiphoton imaging in cardiovascular research. This review article will highlight the potential of multiphoton microscopy for the visualization and characterization of dynamical and structural processes involved in cardiac and vascular diseases, both in an ex vivo and an intravital animal setting...
April 18, 2017: Methods: a Companion to Methods in Enzymology
Kenneth W Dunn, Jennifer C Ryan
Hepatic solute transport is a complex process whose disruption is associated with liver disease and drug-induced liver injury. Intravital multiphoton fluorescence excitation microscopy provides the spatial and temporal resolution necessary to characterize hepatic transport at the level of individual hepatocytes in vivo and thus to identify the mechanisms and cellular consequences of cholestasis. Here we present an overview of the use of fluorescence microscopy for studies of hepatic transport in living animals, and describe how we have combined methods of intravital microscopy and digital image analysis to dissect the effects of drugs and pathological conditions on the function of hepatic transporters in vivo...
April 20, 2017: Methods: a Companion to Methods in Enzymology
Wei Ma, Liguang Xu, André F de Moura, Xiaoling Wu, Hua Kuang, Chuanlai Xu, Nicholas A Kotov
The field of chiral inorganic nanostructures is rapidly expanding. It started from the observation of strong circular dichroism during the synthesis of simple nanoparticles (NPs) and their assemblies mediated by biomolecules and expanded to sophisticated synthetic protocols involving nanostructures from metals, semiconductors, ceramics, and nanocarbons. Besides the well-established chirality transfer from bioorganic molecules, other methods to impart handedness to nanoscale matter specific to inorganic materials were discovered, including three-dimentional lithography, multiphoton chirality transfer, polarization effects in nanoscale assemblies, and others...
April 20, 2017: Chemical Reviews
Masamoto Aose, Tor H Linbo, Owen Lawrence, Tadashi Senoo, David W Raible, John I Clark
BACKGROUND: Zebrafish visual function depends on quality optics. An F3 screen for developmental mutations in the zebrafish nervous system was conducted in wild-type (wt) AB zebrafish exposed to 3 mM of N-ethyl-N-nitrosourea (ENU). RESULTS: Mutant offspring, identified in an F3 screen, were characterized by a small pupil, resulting from retinal hypertrophy or hyperplasia and a small lens. Deficits in visual function made feeding difficult after hatching at approximately 5-6 dpf (days post fertilization)...
April 19, 2017: Developmental Dynamics: An Official Publication of the American Association of Anatomists
Michael J Hickey, Zachary Chow
Regulatory T cells (Tregs) play indispensable roles in the immune system, in limiting excessive or inappropriate immune and inflammatory responses. They achieve this function via effects on other immune cells in the secondary lymphoid system, and in peripheral locations such as skin, gut and bone marrow. As for the more extensively-studied cellular players in the immune system, particularly dendritic cells and conventional T cells, in vivo imaging of Tregs via two-photon or multiphoton microscopy (MPM) has been central to the development of understanding how these cells function...
April 19, 2017: Immunology and Cell Biology
Christoph Hamsen, Karl Nicolas Tolazzi, Tatjana Wilk, Gerhard Rempe
Photon blockade is a dynamical quantum-nonlinear effect in driven systems with an anharmonic energy ladder. For a single atom strongly coupled to an optical cavity, we show that atom driving gives a decisively larger optical nonlinearity than cavity driving. This enhances single-photon blockade and allows for the implementation of two-photon blockade where the absorption of two photons suppresses the absorption of further photons. As a signature, we report on three-photon antibunching with simultaneous two-photon bunching observed in the light emitted from the cavity...
March 31, 2017: Physical Review Letters
J C Loredo, M A Broome, P Hilaire, O Gazzano, I Sagnes, A Lemaitre, M P Almeida, P Senellart, A G White
A boson-sampling device is a quantum machine expected to perform tasks intractable for a classical computer, yet requiring minimal nonclassical resources as compared to full-scale quantum computers. Photonic implementations to date employed sources based on inefficient processes that only simulate heralded single-photon statistics when strongly reducing emission probabilities. Boson sampling with only single-photon input has thus never been realized. Here, we report on a boson-sampling device operated with a bright solid-state source of single-photon Fock states with high photon-number purity: the emission from an efficient and deterministic quantum dot-micropillar system is demultiplexed into three partially indistinguishable single photons, with a single-photon purity 1-g^{(2)}(0) of 0...
March 31, 2017: Physical Review Letters
Danielle M Robertson, Nathan A Rogers, W Matthew Petroll, Meifang Zhu
Pseudomonas aeruginosa is a pathogenic gram-negative organism that has the ability to cause blinding corneal infections following trauma and during contact lens wear. In this study, we investigated the directional movement and orientation of an invasive corneal isolate of P. aeruginosa in the corneal stroma during infection of ex vivo and in vivo rabbit corneas using multiphoton fluorescence and second harmonic generation (SHG) imaging. Ex vivo, rabbit corneas were subject to three partial thickness wounds prior to inoculation...
April 11, 2017: Scientific Reports
Colin Harthcock, Jie Zhang, Wei Kong, Masaaki Mitsui, Yasuhiro Ohshima
We combine results from several different experiments to investigate the photophysics of acridine (Ac) and its hydrated clusters in the gas phase. Our findings are also compared with results from condensed phase studies. Similar to measurements of Ac dissolved in hydrocarbons, the lifetime of the first electronically excited state of isolated Ac in vacuum is too short for typical resonantly enhanced multiphoton ionization (REMPI) and laser induced fluorescence (LIF) experiments, hence no signal from REMPI and LIF can be attributed to monomeric Ac...
April 7, 2017: Journal of Chemical Physics
Gislaine Vieira-Damiani, Denise Lage, Patrícia Érica Christofoletti Daldon, Caroline Romanelli Tibúrcio Alves, Maria Letícia Cintra, Konradin Metze, Javier Adur, Vitor B Pelegati, Hernandes F Carvalho, Carlos Lenz Cesar
BACKGROUND: The diagnosis of idiopathic atrophoderma of Pasini and Pierini (IAPP) relies on typical clinical features, particularly distinctive pigmented ovular/round depressed plaques. Histologic examination often reveals no obvious changes, but patterns of collagen distribution, using multiphoton imaging and second harmonic generation can help track hidden details of tissue organization contributing to atrophy. OBJECTIVE: To identify histologic features that distinguish IAPP from unaffected skin...
April 4, 2017: Journal of the American Academy of Dermatology
William D Tuttle, Adrian M Gardner, Kieran B O'Regan, William Malewicz, Timothy G Wright
We assign the 0-600 cm(-1) region of the S1← S0 transition in p-xylene (p-dimethylbenzene) using resonance-enhanced multiphoton ionization (REMPI) and zero-kinetic-energy (ZEKE) spectroscopy. In the 0-350 cm(-1) range as well as the intense origin band, there are a number of torsional and vibration-torsion (vibtor) features. The latter are discussed in more detail in Paper I [A. M. Gardner et al., J. Chem. Phys. 146, 124308 (2017)]. Here we focus on the origin and the 300-600 cm(-1) region, where vibrational bands and some vibtor activity are observed...
March 28, 2017: Journal of Chemical Physics
Adrian M Gardner, William D Tuttle, Peter Groner, Timothy G Wright
For the first time, a molecular symmetry group (MSG) analysis has been undertaken in the investigation of the electronic spectroscopy of p-xylene (p-dimethylbenzene). Torsional and vibration-torsional (vibtor) levels in the S1 state and ground state of the cation of p-xylene are investigated using resonance-enhanced multiphoton ionization (REMPI) and zero-kinetic-energy (ZEKE) spectroscopy. In the present work, we concentrate on the 0-350 cm(-1) region, where there are a number of torsional and vibtor bands and we discuss the assignment of this region...
March 28, 2017: Journal of Chemical Physics
O Friedrich, S Diermeier, L Larsson
Intensive care interventions involve periods of mechanical ventilation, sedation and complete mechanical silencing of patients. Critical illness myopathy (CIM) is an ICU-acquired myopathy that is associated with limb muscle weakness, muscle atrophy, electrical silencing of muscle and motor-proteinopathy. The hallmark of CIM is a preferential muscle myosin loss due to increased catabolic and reduced anabolic activity. The ubiquitin-proteasome pathway plays an important role, apart from recently identified novel mechanisms affecting nonlysosomal protein degradation or autophagy...
April 7, 2017: Acta Physiologica
Ke Wang, Wenhui Wen, Yuxin Wang, Kai Wang, Jiexing He, Jiaqi Wang, Peng Zhai, Yanfu Yang, Ping Qiu
To enhance signal levels in multiphoton microscopy (MPM) at the deep-tissue excitation window (1600-1820 nm) with oil immersion, we demonstrate: First, the absorption spectra of several commonly immersion oils are characterized, which were unknown before. Second, new material with lower absorption based on mixing is proposed. Third, optimal selection of excitation wavelength within this window is proposed based on absorption spectra characterization. Second and third harmonic generation imaging of mouse tissue corroborate our selection: 1600-nm excitation leads to notable orders-of-magnitude increase in MPM signal, compared with 1700-nm excitation, enabling 200-µm imaging depth of mouse skin while 1700-nm excitation could resolve virtually no structure...
March 20, 2017: Optics Express
Naoya Matsumoto, Alu Konno, Yasushi Ohbayashi, Takashi Inoue, Akiyuki Matsumoto, Kenji Uchimura, Kenji Kadomatsu, Shigetoshi Okazaki
We demonstrate that high-quality images of the deep regions of a thick sample can be obtained from its surface by multi-focal multiphoton microscopy (MMM). The MMM system incorporates a spatial light modulator to separate the excitation beam into a multi-focal excitation beam and modulate the pre-distortion wavefront to correct spherical aberration (SA) caused by a refractive index mismatch between the immersion medium and the biological sample. When fluorescent beads in transparent epoxy resin were observed using four SA-corrected focal beams, the fluorescence signal of the obtained images was ~52 times higher than that obtained without SA correction until a depth of ~1100 μm, similar to the result for single-focal multiphoton microscopy (SMM)...
March 20, 2017: Optics Express
Wei Liu, Shih-Hsuan Chia, Hsiang-Yu Chung, Rüdiger Greinert, Franz X Kärtner, Guoqing Chang
We demonstrate an energy scalable approach to implement ultrafast fiber laser sources suitable for deep tissue multi-photon microscopy imaging. Enabled by fiber-optic nonlinearities (dominated by self-phase modulation), these unique ultrafast sources produce nearly transform-limited pulses of 50-90 fs in duration with the center wavelength tunable in the wavelength range of 1030-1215 nm. The resulting pulse energy can be scaled up to 20 nJ by optimizing fiber dispersion, shortening fiber length, and using large-mode-area fibers...
March 20, 2017: Optics Express
Stefano Protti, Angelo Albini, Radhika Viswanathan, Alexander Greer
This review covers photochemical approaches aimed at supplementing surgical instruments with hand-held photodynamic therapy (PDT) instruments. PDT is not widely used in hospitals, because of the laser equipment and expertise needed, and because insurance policies often do not cover the procedure. Accordingly, this review focuses on advances in photochemistry, photophysics, nanotechnology and miniaturization techniques that may likely inspire the use of hand-held instruments in PDT. A takeaway point is that the advent of photochemical scalpels or lancets that deliver reactive oxygen species (ROS) on site may better equip medical practitioners and allow for eradication of tumors or infections in general...
April 4, 2017: Photochemistry and Photobiology
D Barlerin, G Bessière, J Domingues, M Schuette, C Feuillet, A Peixoto
Multiphoton microscopy has revealed important insights into cellular behavior in vivo. However, its application in infectious settings often encounters technical, safety and regulatory limitations that prevent its wider use with highly virulent human pathogens. Herein, we present a method that renders multiphoton microscopy in vivo compatible with biosafety level 3 regulations and present an example of its application and potential to visualize a Mycobacterium tuberculosis infection of the mouse lung.
April 3, 2017: Scientific Reports
Martin Kuss-Petermann, Margherita Orazietti, Markus Neuburger, Peter Hamm, Oliver S Wenger
The photochemistry of a molecular pentad composed of a central anthraquinone (AQ) acceptor flanked by two Ru(bpy)3(2+) photosensitizers and two peripheral triarylamine (TAA) donors was investigated by transient IR and UV-vis spectroscopies in the presence of 0.2 M p-toluenesulfonic acid (TsOH) in deaerated acetonitrile. In ∼15% of all excited pentad molecules, AQ is converted to its hydroquinone form (AQH2) via reversible intramolecular electron transfer from the two TAA units (τ = 65 ps), followed by intermolecular proton transfer from TsOH (τ ≈ 3 ns for the first step)...
March 31, 2017: Journal of the American Chemical Society
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