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Federico Floris, Lionel Chiron, Alice Lynch, Mark P Barrow, Marc-André Delsuc, Peter B O'Connor
Two-dimensional Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (2D FT-ICR MS or 2D MS) allows data independent fragmentation of all ions in a sample, and correlation of fragment ions to their precursors without isolation prior to fragmentation. Developments in computer capabilities and implementations in FTMS over of the last decade have allowed the technique to become a useful analytical tool for bottom-up proteomics (BUP), and more recently in top-down protein analysis (TDP). In this work, a new method of TDP is developed using two-dimensional mass spectrometry, called MS/2D FT-ICR MS or MS/2DMS...
May 24, 2018: Analytical Chemistry
Pan Li, Haibo Yu, Na Liu, Feifei Wang, Gwo-Bin Lee, Yuechao Wang, Lianqing Liu, Wen Jung Li
The development of microengineered hydrogels co-cultured with cells in vitro could advance in vivo bio-systems in both structural complexity and functional hierarchy, which holds great promise for applications in regenerative tissues or organs, drug discovery and screening, and bio-sensors or bio-actuators. Traditional hydrogel microfabrication technologies such as ultraviolet (UV) laser or multiphoton laser stereolithography and three-dimensional (3D) printing systems have advanced the development of 3D hydrogel micro-structures but need either expensive and complex equipment, or harsh material selection with limited photoinitiators...
May 23, 2018: Biomaterials Science
Hanna Thomsen, Fabrice E Graf, Anne Farewell, Marica B Ericson
One pertinent complication in bacterial infection is the growth of biofilms, i.e., communities of surface-adhered bacteria resilient to antibiotics. Photodynamic inactivation has been proposed as an alternative to antibiotic treatment; however, novel techniques complementing standard efficacy measures are required. Herein, we present an approach employing multiphoton microscopy complemented with Airyscan super-resolution microscopy, to visualize the distribution of curcumin in Staphylococcus epidermidis biofilms...
May 21, 2018: Journal of Biophotonics
Giancarlo Soavi, Gang Wang, Habib Rostami, David G Purdie, Domenico De Fazio, Teng Ma, Birong Luo, Junjia Wang, Anna K Ott, Duhee Yoon, Sean A Bourelle, Jakob E Muench, Ilya Goykhman, Stefano Dal Conte, Michele Celebrano, Andrea Tomadin, Marco Polini, Giulio Cerullo, Andrea C Ferrari
Optical harmonic generation occurs when high intensity light (>1010  W m- 2 ) interacts with a nonlinear material. Electrical control of the nonlinear optical response enables applications such as gate-tunable switches and frequency converters. Graphene displays exceptionally strong light-matter interaction and electrically and broadband tunable third-order nonlinear susceptibility. Here, we show that the third-harmonic generation efficiency in graphene can be increased by almost two orders of magnitude by controlling the Fermi energy and the incident photon energy...
May 21, 2018: Nature Nanotechnology
Alexander G J Skorput, Xijing Zhang, Jonathan J Waataja, Cristina D Peterson, Maureen S Riedl, Kelley F Kitto, Hai Truong, Cecilia Huffman, Stephen R Salton, Carolyn A Fairbanks, Christopher N Honda, Lucy Vulchanova
Neuroplasticity in the dorsal horn following peripheral nerve damage contributes critically to the establishment of chronic pain. The neurosecretory protein VGF (non-acronymic) is rapidly and robustly upregulated following nerve injury, and therefore peptides generated from it are positioned to serve as signals for peripheral damage. The goal of this project was to understand the spinal modulatory effects of the C-terminal VGF derived peptide TLQP-62 at the cellular level and gain insight into the function of the peptide in the development of neuropathic pain...
May 16, 2018: Pain
Alex F Rosenthal, James S Griffin, Michael Wagner, Aaron I Packman, Oluwaseyi Balogun, George F Wells
Morphological parameters are commonly used to predict transport and metabolic kinetics in biofilms. Yet, quantification of biofilm morphology remains challenging due to imaging technology limitations and lack of robust analytical approaches. We present a novel set of imaging and image analysis techniques to estimate internal porosity, pore size distributions, and pore network connectivity to a depth of 1 mm at a resolution of 10 µm in a biofilm exhibiting both heterotrophic and nitrifying activity. Optical coherence tomography (OCT) scans revealed an extensive pore network with diameters as large as 110 µm directly connected to the biofilm surface and surrounding fluid...
May 19, 2018: Biotechnology and Bioengineering
Woongkyu Park, Youjin Lee, Taehee Kang, Jeeyoon Jeong, Dai-Sik Kim
Plasmon-mediated polymerization has been intensively studied for various applications including nanolithography, near-field mapping, and selective functionalization. However, these studies have been limited from the near-infrared to the ultraviolet regime. Here, we report a resist polymerization using intense terahertz pulses and various nanoantennas. The resist is polymerized near the nanoantennas, where giant field enhancement occurs. We experimentally show that the physical origin of the cross-linking is a terahertz electron emission from the nanoantenna, rather than multiphoton absorption...
May 17, 2018: Scientific Reports
Yunfeng Wang, Wenfei Zhang, Chao-Nan Lin, Pengpeng Ren, Ying-Jie Lu, Chongxin Shan, Siu Fung Yu
Room-temperature up-conversion emission up to eight-photon absorption is demonstrated from diamond single crystals under femtosecond laser excitation for the first time. The low concentration of defects and impurities is attributed to the support of free excitons emission at 235 nm. Nonlinear optical properties are also investigated by using an open aperture Z-scan technique. The corresponding three-, five- and eight-photon absorption coefficients of the diamonds are found to be 1.8×10-2 cm3/GW2, 5×10-9 cm7/GW4 and 1...
May 17, 2018: ACS Applied Materials & Interfaces
Yu Du, Ziwei Zhuang, Jiexing He, Hongji Liu, Ping Qiu, Ke Wang
With tunable excitation light, multiphoton microscopy (MPM) is widely used for imaging biological structures at subcellular resolution. Axial chromatic dispersion, present in virtually every transmissive optical system including the multiphoton microscope, leads to focal (and the resultant image) plane separation. Here we demonstrate experimentally a technique to measure the axial chromatic dispersion in a multiphoton microscope, using simultaneous 2-color third-harmonic generation (THG) imaging excited by a 2-color soliton source with tunable wavelength separation...
May 16, 2018: Journal of Biophotonics
Shu Wang, Huiping Du, Bingbing Lin, Chenxi Liao, Xiaoqin Zhu, Xingfu Wang, Hong Chen, Shuangmu Zhuo, Liwei Jiang, Lianhuang Li, Haohua Tu, Jianxin Chen
Ischemic stroke is a leading cause of death and permanent disability worldwide. Middle cerebral artery occlusion (MCAO) of variable duration times could be anticipated to result in varying degrees of injury that evolve spatially over time. Therefore, investigations following strokes require information concerning the spatiotemporal dimensions of the ischemic core as well as of perilesional areas. In the present study, multiphoton microscopy (MPM) based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) was applied to image such pathophysiological events...
May 1, 2018: Biomedical Optics Express
Kriti Charan, Bo Li, Mengran Wang, Charles P Lin, Chris Xu
Deep tissue multiphoton imaging requires high peak power to enhance signal and low average power to prevent thermal damage. Both goals can be advantageously achieved through laser repetition rate tuning instead of simply adjusting the average power. We show that the ideal repetition rate for deep two-photon imaging in the mouse brain is between 1 and 10 MHz, and we present a fiber-based source with an arbitrarily tunable repetition rate within this range. The performance of the new source is compared to a mode-locked Ti:Sapphire (Ti:S) laser for in vivo imaging of mouse brain vasculature...
May 1, 2018: Biomedical Optics Express
J S Pedernales, M Beau, S M Pittman, I L Egusquiza, L Lamata, E Solano, A Del Campo
We introduce an exact mapping between the Dirac equation in (1+1)-dimensional curved spacetime (DCS) and a multiphoton quantum Rabi model (QRM). A background of a (1+1)-dimensional black hole requires a QRM with one- and two-photon terms that can be implemented in a trapped ion for the quantum simulation of Dirac particles in curved spacetime. We illustrate our proposal with a numerical analysis of the free fall of a Dirac particle into a (1+1)-dimensional black hole, and find that the Zitterbewegung effect, measurable via the oscillatory trajectory of the Dirac particle, persists in the presence of gravity...
April 20, 2018: Physical Review Letters
Tao Shi, Yue Chang, Juan José García-Ripoll
We study the scattering of individual photons by a two-level system ultrastrongly coupled to a waveguide. The scattering is elastic for a broad range of couplings and can be described with an effective U(1)-symmetric Hamiltonian. This simple model allows the prediction of scattering resonance line shapes, validated up to α=0.3, and close to the Toulouse point α=1/2, where inelastic scattering becomes relevant. Our predictions model experiments with superconducting circuits [P. Forn-Díaz et al., Nat. Phys...
April 13, 2018: Physical Review Letters
Samuel A Manning, Lucas G Dent, Shu Kondo, Ziqing W Zhao, Nicolas Plachta, Kieran F Harvey
The Hippo pathway is an evolutionarily conserved signaling network that integrates diverse cues to control organ size and cell fate. The central downstream pathway protein in Drosophila is the transcriptional co-activator Yorkie (YAP and TAZ in humans), which regulates gene expression with the Scalloped/TEA domain family member (TEAD) transcription factors [1-8]. A central regulatory step in the Hippo pathway is phosphorylation of Yorkie by the NDR family kinase Warts, which promotes Yorkie cytoplasmic localization by stimulating association with 14-3-3 proteins [9-12]...
April 24, 2018: Current Biology: CB
Yanyang Chen, Yasaman Jami-Alahmahdi, Kiran Sagar Unikela, Graham J Bodwell, Travis D Fridgen
1,1,9,9-Tetramethyl[9](2,11)teropyrenophane (TM9TP), a belt-shaped molecule, has a sizable cavity that molecules or ions could occupy. In this study, the question of whether TM9TP forms gas phase ion-molecule complexes with metal cations (K+, Rb+, Cs+) situated inside or outside the TM9TP cavity was addressed using both experimental and computational methods. Complexes were trapped in a Fourier transform ion cyclotron resonance mass spectrometer and their structures were explored by some novel physical chemistry/mass spectrometry methods...
May 9, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
H H Jen
We theoretically investigate the far-field scattering properties of multiphoton super- and subradiant states which can be prepared by multiphoton excitations with orbital angular momentum (OAM). Due to multiphoton interference, the far-field patterns of the subradiant modes show directional scattering along the excitation direction or transverse scattering with number of peaks equal to the number of atoms. When more atoms are involved, we consider structures of stacked and concentric rings, which respectively show enhanced directional scattering and smoothed emission patterns...
May 8, 2018: Scientific Reports
Guangxue Feng, Bin Liu
Theranostic nanolights refer to luminescent nanoparticles possessing both imaging and therapeutic functions. Their shape, size, surface functions, and optical properties can be precisely manipulated through integrated efforts of chemistry, materials, and nanotechnology for customized applications. When localized photons are used to activate both imaging and therapeutic functions such as photodynamic or photothermal therapy, these theranostic nanolights increase treatment efficacy with minimized damage to surrounding healthy tissues, which represents a promising noninvasive nanomedicine as compared to conventional theranostic approaches...
May 7, 2018: Accounts of Chemical Research
Jens Balke, Pierre Volz, Falko Neumann, Robert Brodwolf, Alexander Wolf, Hannah Pischon, Moritz Radbruch, Lars Mundhenk, Achim D Gruber, Nan Ma, Ulrike Alexiev
Nanoparticles hold a great promise in biomedical science. However, due to their unique physical and chemical properties they can lead to overproduction of intracellular reactive oxygen species (ROS). As an important mechanism of nanotoxicity, there is a great need for sensitive and high-throughput adaptable single-cell ROS detection methods. Here, fluorescence lifetime imaging microscopy (FLIM) is employed for single-cell ROS detection (FLIM-ROX) providing increased sensitivity and enabling high-throughput analysis in fixed and live cells...
May 4, 2018: Small
Aaron W Harrison, Scott H Kable
The Norrish Type I photodissociation of two aliphatic aldehydes, propanal and isobutanal, has been investigated using velocity-map imaging. The HCO photoproduct of this reaction was probed using a 1+1 resonance-enhanced multiphoton ionization scheme via the 3p2 Π Rydberg state. The velocity map images of HCO+ were collected across a range of photolysis energies for both species from 30 500 to 33 000 cm-1 (λ = 312-327 nm). The corresponding translational energy distributions show that the majority of the available energy goes into the translational motion of the products (55%-68%) with this fraction increasing as the T1 barrier is approached...
April 28, 2018: Journal of Chemical Physics
Nikolaos Liaros, Samuel R Cohen, John T Fourkas
The concept of a 2-beam action (2-BA) spectroscopy was recently introduced as a method for determining the order of effective nonlinear absorption in multiphoton photoresists. Here we demonstrate that the 2-BA approach can be extended to any measureable observable generated by linear and/or nonlinear absorption. As an example, 2-beam constant-amplitude photocurrent spectroscopy is used to study absorption of a tightly focused, mode-locked or continuous-wave, 800 nm laser by a GaAsP photodiode. The effective order of the absorption process can be measured at any desired value of the photocurrent or photovoltage...
April 16, 2018: Optics Express
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