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https://www.readbyqxmd.com/read/28441478/energy-transfer-kinetics-driven-by-mid-infrared-amplified-spontaneous-emissions-after-two-photon-excitation-from-xe-s0-to-the-xe-6p-1-2-0-state
#1
Shan He, Yafu Guan, Dong Liu, Xusheng Xia, Baodong Gai, Shu Hu, Jingwei Guo, Fengting Sang, Yuqi Jin
In optically pumped laser systems, rare gas lasers (RGLs) are a field of great interest for researchers. Gas laser regimes with metastable Ne, Ar, and Kr atoms have been investigated, while studies of RGLs based on metastable Xe are sparse. In this work, when a strong excitation laser (2.92 mJ/pulse, 7.44*10^5 W/cm2) was applied to excite Xe atoms from the ground state to the 6p[1/2]0 state, an interesting phenomenon emerged: An intense fluorescence of 980 nm (6p[1/2]1-6s[3/2]2) was produced. However, when the energy of excitation laser was decreased to 0...
April 25, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28440644/direct-observation-of-the-ultrafast-evolution-of-open-shell-biradical-in-photochromic-radical-dimer
#2
Yoichi Kobayashi, Hajime Okajima, Hikaru Sotome, Takeshi Yanai, Katsuya Mutoh, Yusuke Yoneda, Yasuteru Shigeta, Akira Sakamoto, Hiroshi Miyasaka, Jiro Abe
Delocalized biradicals have been extensively studied because of fundamental interests to singlet biradicals and several potential applications such as to two-photon absorption materials. However, many of the biradical studies only focus on the static properties of the rigid molecular structures. It is expected that the biradical properties of the delocalized biradicals are sensitive to the subtle changes of the molecular structures and their local environments. Therefore, the studies of the dynamic properties of the system will give further insight into stable radical chemistry...
April 25, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28438833/g-protein-gi1-exhibits-basal-coupling-but-not-preassembly-with-g-protein-coupled-receptors
#3
Alexey Bondar, Josef Lazar
The Gi/o protein family transduces signals from a diverse group of G protein-coupled receptors (GPCRs). The observed specificity of Gi/o-GPCR coupling and high rate of Gi/o signal transduction have been hypothesized to be enabled by existence of stable associates between Gi/o proteins and their cognate GPCRs in the inactive state (Gi/o-GPCR preassembly). To test this hypothesis, we applied the recently developed technique of two-photon polarization microscopy (2PPM) to Gαi1 subunits labeled with fluorescent proteins and four GPCRs (the α2A-adrenergic receptor (α2A-AR), γ-aminobutyric acid receptor B (GABAB), cannabinoid receptor type 1 (CB1R) and dopamine receptor type 2 (D2R))...
April 24, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28437951/hot-spot-relaxation-time-current-dependence-in-niobium-nitride-waveguide-integrated-superconducting-nanowire-single-photon-detectors
#4
Simone Ferrari, Vadim Kovalyuk, Wladislaw Hartmann, Andreas Vetter, Oliver Kahl, Changhyoup Lee, Alexander Korneev, Carsten Rockstuhl, Gregory Gol'tsman, Wolfram Pernice
We investigate how the bias current affects the hot-spot relaxation dynamics in niobium nitride. We use for this purpose a near-infrared pump-probe technique on a waveguide-integrated superconducting nanowire single-photon detector driven in the two-photon regime. We observe a strong increase in the picosecond relaxation time for higher bias currents. A minimum relaxation time of (22 ± 1) ps is obtained when applying a bias current of 50% of the switching current at 1.7 K bath temperature. We also propose a practical approach to accurately estimate the photon detection regimes based on the reconstruction of the measured detector tomography at different bias currents and for different illumination conditions...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437911/investigation-of-third-order-dispersion-of-long-range-surface-plasmon-polariton-waveguides-using-a-hong-ou-mandel-interferometer
#5
Takahide Sakaidani, Ryo Kobayashi, Naoto Namekata, Go Fujii, Daiji Fukuda, Shuichiro Inoue
High-order dispersion of long-range surface-plasmon-polariton waveguides (LR-SPP-WGs) have been investigated using a two-photon interferometer. Since linear and even-ordered dispersions in two-photon interferometry are cancelled out by a nonlocal quantum correlation, odd-ordered dispersions of millimeter-long LR-SPP-WGs are revealed. Even under the highly dispersive condition, the indistinguishability between two photons emerged from LR-SPP-WGs was well preserved. In addition, we demonstrated a strong polarization-selection by the LR-SPP-WGs that leads to the polarization-stable and high-fidelity quantum interference...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437905/amplitude-modulation-of-femtosecond-laser-pulses-in-the-megahertz-range-for-frequency-multiplexed-two-photon-imaging
#6
Dmitri Tsyboulski, Natalia Orlova, Peter Saggau
We present a frequency-multiplexed multi-site two-photon imaging method utilizing amplitude modulation of femtosecond laser pulses in the MHz range to tag each excitation beam and the corresponding fluorescence signals with specific frequencies. The frequency tags are generated with an interferometric scheme employing acousto-optic deflectors (AODs) to achieve precise spatial overlap of femtosecond laser pulses with periodically varying phase shift. Creating matching excitation beam patterns in each interferometer arm using multiple AOD driving frequencies, and subsequently overlapping these matching patterns, results in multiple encoded excitation beams with unique beat frequencies available for scanning...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28436294/overexpression-of-vla-4-in-glial-restricted-precursors-enhances-their-endothelial-docking-and-induces-diapedesis-in-a-mouse-stroke-model
#7
Anna Jablonska, Daniel J Shea, Suyi Cao, Jeff Wm Bulte, Miroslaw Janowski, Konstantinos Konstantopoulos, Piotr Walczak
The loss of oligodendrocytes after stroke is one of the major causes of secondary injury. Glial-restricted progenitors (GRPs) have remylenating potential after intraparenchymal cerebral transplantation. The intraarterial (IA) injection route is an attractive gateway for global brain delivery, but, after IA infusion, naive GRPs fail to bind to the cerebral vasculature. The aim of this study was to test whether overexpression of Very Late Antigen-4 (VLA-4) increases endothelial docking and cerebral homing of GRPs in a stroke model...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/28434998/use-of-two-photon-microscopy-to-study-leishmania-major-infection-of-the-skin
#8
REVIEW
Matheus Batista Carneiro, Leah Shan Hohman, Jackson G Egen, Nathan C Peters
Intra-vital two-photon microscopy (2P-IVM) allows for in-situ investigation of tissue organization, cell behavior and the dynamic interactions between different cell types in their natural environment. This methodology has also expanded our understanding of the immune response against pathogens. Leishmania are protozoan intracellular parasites that have adapted to successfully establish infection within the context of an inflammatory response in the skin following transmission by the bite of an infected sand fly...
April 18, 2017: Methods: a Companion to Methods in Enzymology
https://www.readbyqxmd.com/read/28434992/promising-techniques-to-illuminate-neuromodulatory-control-of-the-cerebral-cortex-in-sleeping-and-waking-states
#9
REVIEW
Takeshi Kanda, Kaoru Ohyama, Hiroki Muramoto, Nami Kitajima, Hiroshi Sekiya
Sleep, a common event in daily life, has clear benefits for brain function, but what goes on in the brain when we sleep remains unclear. Sleep was long regarded as a silent state of the brain because the brain seemingly lacks interaction with the surroundings during sleep. Since the discovery of electrical activities in the brain at rest, electrophysiological methods have revealed novel concepts in sleep research. During sleep, the brain generates oscillatory activities that represent characteristic states of sleep...
April 20, 2017: Neuroscience Research
https://www.readbyqxmd.com/read/28434219/a-hydrogen-peroxide-responsive-nanoprobe-assists-circulating-tumor-cell-identification-and-colorectal-cancer-diagnosis
#10
Chunting Li, Ruijun Pan, Peiyong Li, Qinghua Guan, Junping Ao, Kai Wang, Li Xu, Xiaofei Liang, Xin Jin, Chuan Zhang, Xinyuan Zhu
In clinic, numeration of circulating tumor cells (CTCs) plays a critical role in cancer diagnosis and treatment but conventional CTC identification and counting that rely on specific antibodies to characterize cell's surface antigens are costive and with limitations. Importantly, false positive or negative results may be occurred due to the high heterogeneity and epithelial-mesenchymal transition (EMT) of CTCs. Herein we demonstrated a novel and effective CTC detecting nanoprobe that could rapidly response to the high level of endogenous H2O2 of CTCs and report the signal through fluorescence emission...
April 22, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28432298/endogenous-two-photon-excited-fluorescence-imaging-characterizes-neuron-and-astrocyte-metabolic-responses-to-manganese-toxicity
#11
Emily Stuntz, Yusi Gong, Disha Sood, Volha Liaudanskaya, Dimitra Pouli, Kyle P Quinn, Carlo Alonzo, Zhiyi Liu, David L Kaplan, Irene Georgakoudi
As neurodegenerative conditions are increasingly linked to mitochondrial dysfunction, methods for studying brain cell metabolism at high spatial resolution are needed to elucidate neurodegeneration mechanisms. Two-photon excited fluorescence (TPEF) imaging is a non-destructive, high-resolution technique for studying cell metabolism via endogenous fluorescence of reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) and flavin adenine dinucleotide (FAD). We employed TPEF to study the metabolism of primary rat astrocyte and neuronal cultures under normal growth conditions and in response to manganese (Mn) treatment...
April 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28432140/visually-evoked-3-5-hz-membrane-potential-oscillations-reduce-the-responsiveness-of-visual-cortex-neurons-in-awake-behaving-mice
#12
Michael C Einstein, Pierre-Olivier Polack, Duy T Tran, Peyman Golshani
Low frequency membrane potential (Vm) oscillations were once thought to only occur in sleeping and anesthetized states. Recently, low frequency Vm oscillations have been described in inactive awake animals, but it is unclear if they shape sensory processing in neurons and whether they occur during active awake behavioral states. To answer these questions, we performed two-photon guided whole-cell Vm recordings from primary visual cortex layer 2/3 excitatory and inhibitory neurons in awake mice during passive visual stimulation and performance of visual and auditory discrimination tasks...
April 21, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28424320/trpa1-expression-and-its-functional-activation-in-rodent-cortex
#13
Ehsan Kheradpezhouh, Julian M C Choy, Vincent R Daria, Ehsan Arabzadeh
TRPA1 is a non-selective cation channel involved in pain sensation and neurogenic inflammation. Although TRPA1 is well established in a number of organs including the nervous system, its presence and function in the mammalian cortex remains unclear. Here, we demonstrate the expression of TRPA1 in rodent somatosensory cortex through immunostaining and investigate its functional activation by whole-cell electrophysiology, Ca(2+) imaging and two-photon photoswitching. Application of TRPA1 agonist (AITC) and antagonist (HC-030031) produced significant modulation of activity in layer 5 (L5) pyramidal neurons in both rats and mice; AITC increased intracellular Ca(2+) concentrations and depolarized neurons, and both effects were blocked by HC-030031...
April 2017: Open Biology
https://www.readbyqxmd.com/read/28422102/shaping-up-two-photon-imaging-in-vivo
#14
Dustin M Graham
No abstract text is available yet for this article.
April 19, 2017: Lab Animal
https://www.readbyqxmd.com/read/28421209/excitation-dynamics-involving-homogeneous-multistate-interactions-one-and-two-color-vmi-and-rempi-of-hbr
#15
Helgi Rafn Hróðmarsson, Andreas Kartakoullis, Dimitris Zaouris, Pavle Glodic, Huasheng Wang, Peter C Samartzis, Ágúst Kvaran
Velocity map imaging (VMI) data and mass resolved REMPI spectra are complementarily utilized to elucidate the involvement of homogeneous multistate interactions in excited state dynamics of HBr. The H(1)Σ(+)(v' = 0) and E(1)Σ(+)(v' = 1) Rydberg states and the V(1)Σ(+)(v'= m + 7) and V(1)Σ(+)(v'= m + 8) ion-pair states are explored as a function of rotational quantum number in the two-photon excitation region of 79 100-80 700 cm(-1). H(+) and Br(+) images were recorded by one- as well as two-color excitation schemes...
April 19, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28420873/viewing-immune-regulation-as-it-happens-in-vivo-imaging-for-investigation-of-regulatory-t-cell-function
#16
REVIEW
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
https://www.readbyqxmd.com/read/28419303/tumor-microtubes-convey-resistance-to-surgical-lesions-and-chemotherapy-in-gliomas
#17
Sophie Weil, Matthias Osswald, Gergely Solecki, Julia Grosch, Erik Jung, Dieter Lemke, Miriam Ratliff, Daniel Hänggi, Wolfgang Wick, Frank Winkler
Background: Primary and adaptive resistance against chemo- and radiotherapy, and local recurrence after surgery limit the benefits from these standard treatments in glioma patients. Recently we found that glioma cells can extend ultra-long membrane protrusions, "tumor microtubes" (TMs), for brain invasion, proliferation, and interconnection of single cells to a syncytium that is resistant to radiotherapy. We wondered whether TMs also convey resistance to the other two standard treatment modalities...
April 17, 2017: Neuro-oncology
https://www.readbyqxmd.com/read/28414951/development-of-a-two-photon-fluorescent-turn-on-probe-with-far-red-emission-for-thiophenols-and-its-bioimaging-application-in-living-tissues
#18
Huiming Shang, Hua Chen, Yonghe Tang, Yanyan Ma, Weiying Lin
Thiophenol is a highly toxic compound which is essential in the field of organic synthesis and drug design. However, the accumulation of thiophenols in the environment may cause serious health problems for human bodies ultimately. Therefore, it is critical to develop efficient methods for visualization of thiophenol species in biological samples. In this work, an innovative two-photon fluorescent turn-on probe FR-TP with far-red emission for thiophenols based on FR-NH2 fluorophore and 2,4-dinitrophenylsulfonyl recognition site was reported...
April 14, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28411804/carrot-derived-carbon-dots-modified-with-polyethyleneimine-and-nile-blue-for-ratiometric-two-photon-fluorescence-turn-on-sensing-of-sulfide-anion-in-biological-fluids
#19
Hui Jin, Rijun Gui, Yanfeng Wang, Jie Sun
In this article, a facile and green synthesis of carbon dots (CDs) was developed by using natural carrot as new carbon source. After direct hydrothermal carbonization for 5h at 180°C, CDs were prepared facilely. Then, CDs were conjugated with polyethyleneimine (PEI) and Nile Blue (NB) chloride to produce CDs/PEI/NB nanocomposites under electrostatic interactions. Upon excitation at 800nm, two-photon fluorescence (TPF) of the nanocomposites was observed, with TPF peaks of CDs at 415nm and NB at 675nm. The addition of Cu(2+) could lead to TPF quenching of CDs via inner filter effect, but hardly any impacted on TPF of NB...
July 1, 2017: Talanta
https://www.readbyqxmd.com/read/28411609/two-photon-absorption-spectroscopy-of-trans-stilbene-cis-stilbene-and-phenanthrene-theory-and-experiment
#20
Marc de Wergifosse, Amanda L Houk, Anna I Krylov, Christopher G Elles
Two-photon absorption (2PA) spectroscopy provides complementary, and sometimes more detailed, information about the electronic structure of a molecule relative to one-photon absorption (1PA) spectroscopy. However, our understanding of the 2PA processes is rather limited due to technical difficulties in measuring experimental 2PA spectra and theoretical challenges in computing higher-order molecular properties. This paper examines the 2PA spectroscopy of trans-stilbene, cis-stilbene, and phenanthrene by a combined experimental and theoretical approach...
April 14, 2017: Journal of Chemical Physics
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