Insight into the Nonlinear Absorbance of Two Related Series of Two-Photon Absorbing Chromophores

2007 ◽  
Vol 111 (10) ◽  
pp. 1899-1906 ◽  
Author(s):  
Joy E. Rogers ◽  
Jonathan E. Slagle ◽  
Daniel G. McLean ◽  
Richard L. Sutherland ◽  
Mark C. Brant ◽  
...  
Keyword(s):  
Two Photon ◽  
Related Series ◽  
Insight Into

Discovery and Insight into One-photon and Two-photon Excited ACQ-to-AIE Conversion via Positional Isomerization

2021 ◽  
Author(s):  
Xueting Long ◽  
Jieyu Wu ◽  
Sirui Yang ◽  
Ziqi Deng ◽  
Yusen Zheng ◽  
...  
Keyword(s):  
Positional Isomers ◽  
Two Photon ◽  
Positional Isomerization ◽  
Aggregation Behaviors ◽  
Insight Into

Two positional isomers (regioisomers) through changing the substituted position of perylenetetracarboxylic diimide and benzanthrone moieties were designed and synthesized. These two regioisomers exhibit totally different aggregation behaviors. The meta (bay)-substituted...

scholarly journals Spontaneous activations follow a common developmental course across primary sensory areas in mouse neocortex

2016 ◽  
Vol 116 (2) ◽  
pp. 431-437 ◽  
Author(s):  
Charles G. Frye ◽  
Jason N. MacLean
Keyword(s):  
Calcium Imaging ◽  
Sensory Input ◽  
Primary Auditory Cortex ◽  
Developmental Trajectory ◽  
Two Photon ◽  
Developmental Progression ◽  
Sensory Modalities ◽  
Spatially Distributed ◽  
And Function ◽  
Insight Into

Spontaneous propagation of spiking within the local neocortical circuits of mature primary sensory areas is highly nonrandom, engaging specific sets of interconnected and functionally related neurons. These spontaneous activations promise insight into neocortical structure and function, but their properties in the first 2 wk of perinatal development are incompletely characterized. Previously, we have found that there is a minimal numerical sample, on the order of 400 cells, necessary to fully capture mature neocortical circuit dynamics. Therefore we maximized our numerical sample by using two-photon calcium imaging to observe spontaneous activity in populations of up to 1,062 neurons spanning multiple columns and layers in 52 acute coronal slices of mouse neocortex at each day from postnatal day (PND) 3 to PND 15. Slices contained either primary auditory cortex (A1) or somatosensory barrel field (S1BF), which allowed us to compare sensory modalities with markedly different developmental timelines. Between PND 3 and PND 8, populations in both areas exhibited activations of anatomically compact subgroups on the order of dozens of cells. Between PND 9 and PND 13, the spatiotemporal structure of the activity diversified to include spatially distributed activations encompassing hundreds of cells. Sparse activations covering the entire field of view dominated in slices taken on or after PND 14. These and other findings demonstrate that the developmental progression of spontaneous activations from active local modules in the first postnatal week to sparse, intermingled groups of neurons at the beginning of the third postnatal week generalizes across primary sensory areas, consistent with an intrinsic developmental trajectory independent of sensory input.

The spectroscopy of jet-cooled porphyrins: an insight into the vibronic structure of the Q band

2010 ◽  
Vol 14 (04) ◽  
pp. 314-323 ◽  
Author(s):  
Joseph M. Beames ◽  
Timothy D. Vaden ◽  
Andrew J. Hudson
Keyword(s):  
Laser Desorption ◽  
Electronic Transitions ◽  
Quantum Mechanical ◽  
Supersonic Expansion ◽  
Two Photon ◽  
Vibrational Levels ◽  
Inert Carrier ◽  
Mechanical Interpretation ◽  
Photon Ionization ◽  
Insight Into

We will present resonant two-photon ionization spectra for meso-tetraphenylporphyrin, H 2 TPP , measured under isolated conditions. The polycrystalline compound was vaporized, in vacuo, using both thermal and laser desorption, and seeded into a supersonic expansion of an inert-carrier gas. The molecules remain largely intact in the gaseous phase. However, the two techniques for vaporizing H 2 TPP give different internal temperatures for the isolated substrate, with greater vibrational cooling achieved using laser desorption. A comparison of the peak positions and intensities in the resonant two-photon ionization spectra of thermal- and laser-desorbed molecules provides an insight into the vibrational structure of the Q band. In particular, the greater contribution made by electronic transitions originating from higher vibrational levels in the ground state of H 2 TPP is emphasized. We conclude that vibronic coupling in the ground electronic state plays an important role in a quantum-mechanical interpretation of the Q band.

scholarly journals Distinct functional classes of excitatory neurons in mouse V1 are differentially modulated by learning and task engagement

2019 ◽  
Author(s):  
Joseph B. Wekselblatt ◽  
Cristopher M. Niell
Keyword(s):  
Temporal Dynamics ◽  
Task Engagement ◽  
Neural Responses ◽  
Two Photon ◽  
Neural Representations ◽  
Excitatory Neurons ◽  
Before And After ◽  
Functional Classes ◽  
Insight Into ◽  
And Task

AbstractLearning can cause significant changes in neural responses to relevant stimuli, in addition to modulation due to task engagement. However, it is not known how different functional types of excitatory neurons contribute to these changes. To address this gap, we performed two-photon calcium imaging of excitatory neurons in layer 2/3 of mouse primary visual cortex before and after learning of a visual discrimination. We found that excitatory neurons show striking diversity in the temporal dynamics of their response to visual stimuli during the behavior, and based on this we classified them into transient, sustained, and suppressed groups. Notably, these functionally defined cell classes exhibit different visual stimulus selectivity and modulation by locomotion, and were differentially affected by training condition. In particular, we observed a decrease in the number of transient neurons responsive during behavior after learning, while both transient and sustained cells showed an increase in modulation due to task engagement after learning. The identification of functional diversity within the excitatory population, with distinct changes during learning and task engagement, provides insight into the cortical pathways that allow context-dependent neural representations.

Theoretical insight into the photophysical properties of long-lifetime Ir(iii) and Rh(iii) complexes for two-photon photodynamic therapy

2019 ◽  
Vol 21 (16) ◽  
pp. 8394-8401 ◽  
Author(s):  
Xue Yin ◽  
Xiao-Yong Lai ◽  
Xin Wang ◽  
Ying-Tao Liu
Keyword(s):  
Photodynamic Therapy ◽  
Photophysical Properties ◽  
Deep Penetration ◽  
Two Photon ◽  
Minimal Damage ◽  
Long Lifetime ◽  
Theoretical Insight ◽  
Insight Into

Two-photon photodynamic therapy (TP-PDT) plays crucial roles in curing tumors because it involves deep penetration of drugs into the tissue and has minimal damage to the surrounding cells.

THEORETICAL STUDIES ON LINEAR AND NONLINEAR OPTICAL CHARACTERIZATION AND OPTICAL LIMITING PROPERTY OF Pb(II), In(III) CHLORIDE, Ni(II) METALLATED 1,4,8,11,15,18,22,25-OCTAALKYLPHTHALOCYANINES

2007 ◽  
Vol 16 (02) ◽  
pp. 247-254 ◽  
Author(s):  
ASLI KARAKAS ◽  
AYHAN ELMALI
Keyword(s):  
Nonlinear Optical ◽  
Optical Limiting ◽  
Photon Absorption ◽  
Third Order ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Optical Limiter ◽  
Limiting Property ◽  
Insight Into ◽  
Good Agreement

To provide an insight into the optical limiting (OL) behavior of a series of 3 metallated 1,4,8,11,15,18,22,25-octaalkylphthalocyanines; the third-order nonlinear optical (NLO) properties, one-photon absorption (OPA) and two-photon absorption (TPA) characterizations have been theoretically investigated by means of AM1, ZINDO and configuration interaction (CI) methods. The highest values for the TPA cross-section (δ(ω)) are exhibited by derivatives metallated with indium and lead. It is also seen that the nickel-metallated compound might be a passive optical limiter of the series, indicating the weakest δ(ω) and second hyperpolarizability (γ). Our calculated results are in good agreement with the previous experimental observations on the examined molecules.

scholarly journals A novel spheroid model for preclinical intercellular nanophotosensitizer-mediated tumor study

2018 ◽  
pp. 14-20
Author(s):  
YuS Maklygina ◽  
ID Romanishkin ◽  
AV Ryabova ◽  
IV Yakavec ◽  
L Bolotin ◽  
...  
Keyword(s):  
Cell Cultures ◽  
3D Structure ◽  
3D Cell Culture ◽  
3D Models ◽  
Fluorescence Signal ◽  
Phenotypic Properties ◽  
Two Photon ◽  
Tumor Study ◽  
Photon Excitation ◽  
Insight Into

Aluminum phthalocyanine nanoparticles (NP AlPc) possess the features that make them a promising photosensitizer. In particular, AlPc NPs do not fluoresce in free nanoform, fluoresce weakly in normal tissue, strongly in tumors and very strongly in macrophages. Also, such particles fluoresce and become phototoxic when contacting certain biocomponents. The type of biocomponents that bind to AlPc NPS defines intensity, lifetime, and spectral distribution of the fluorescence. This study aimed to investigate the peculiarities of nanophotosensitizer capturing in 3D models of cell cultures. The data obtained demonstrate that AlPc NPs are captured by cells inside the spheroid in the course of the first hour, as the fluorescent signal's growth shows. Having analyzed the fluctuations of the fluorescence signal of AlPc NPs inside a spheroid, we have also discovered that the cellular 3D models are heterogeneous. Laser irradiation (two-photon excitation at λ = 780/390 nm) resulted in photobleaching of fluorescence, which is probably associated with AlPc NP deactivation. Thus, the created model comprised of a 3D cell culture and AlPc NPs provides a better insight into metabolic processes in cells than monolayer 2D cell cultures. Besides, the model allows to evaluate the photodynamic effect depending on phenotypic properties of various areas in the heterogeneous 3D-structure.

scholarly journals Representation of Visual Landmarks in Retrosplenial Cortex

2019 ◽  
Author(s):  
Lukas F. Fischer ◽  
Raul Mojica Soto-Albors ◽  
Friederike Buck ◽  
Mark T. Harnett
Keyword(s):  
Visual Information ◽  
Receptive Fields ◽  
Spatial Relationship ◽  
Retrosplenial Cortex ◽  
Task Engagement ◽  
Reference Points ◽  
Behavioral Task ◽  
Motor Responses ◽  
Two Photon ◽  
Insight Into

AbstractThe process by which visual information is incorporated into the brain’s spatial framework to represent landmarks is poorly understood. Studies in humans and rodents suggest that retrosplenial cortex (RSC) plays a key role in these computations. We developed an RSC-dependent behavioral task in which head-fixed mice learned the spatial relationship between visual landmark cues and hidden reward locations. Two-photon imaging revealed that these cues served as dominant reference points for most task-active neurons and anchored the spatial code in RSC. Presenting the same environment but decoupled from mouse behavior degraded encoding fidelity. Analyzing visual and motor responses showed that landmark codes were the result of supralinear integration. Surprisingly, V1 axons recorded in RSC showed similar receptive fields. However, they were less modulated by task engagement, indicating that landmark representations in RSC are the result of local computations. Our data provide cellular- and network-level insight into how RSC represents landmarks.

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