Excitation with Monochromatic Light of a Vibronically Broadened Molecular Band

1972 ◽  
Vol 56 (8) ◽  
pp. 4011-4019 ◽  
Author(s):  
J. A. Beswick ◽  
R. Lefebvre ◽  
A. M. Plumejeau
Keyword(s):  
Monochromatic Light ◽  
Molecular Band

Instrumentation for detecting channelling radiation in the high-voltage electron microscope

1983 ◽  
Vol 41 ◽  
pp. 318-319
Author(s):  
J. H. Butler ◽  
C. J. Humphreys
Keyword(s):  
Monochromatic Light ◽  
Incident Beam ◽  
Laboratory Frame ◽  
Relativistic Electrons ◽  
Voltage Electron ◽  
Dipole Emission ◽  
Sinusoidal Oscillations ◽  
Pass Through ◽  
Incident Beam Energy ◽  
Increasing Function

Electromagnetic radiation is emitted when fast (relativistic) electrons pass through crystal targets which are oriented in a preferential (channelling) direction with respect to the incident beam. In the classical sense, the electrons perform sinusoidal oscillations as they propagate through the crystal (as illustrated in Fig. 1 for the case of planar channelling). When viewed in the electron rest frame, this motion, a result of successive Bragg reflections, gives rise to familiar dipole emission. In the laboratory frame, the radiation is seen to be of a higher energy (because of the Doppler shift) and is also compressed into a narrower cone of emission (due to the relativistic “searchlight” effect). The energy and yield of this monochromatic light is a continuously increasing function of the incident beam energy and, for beam energies of 1 MeV and higher, it occurs in the x-ray and γ-ray regions of the spectrum. Consequently, much interest has been expressed in regard to the use of this phenomenon as the basis for fabricating a coherent, tunable radiation source.

scholarly journals Creating a ‘Molecular Band-Aid’; Blocking an Exposed Protease Target Site in Desmoplakin

2021 ◽  
Vol 11 (5) ◽  
pp. 401
Author(s):  
Catherine A. Hoover ◽  
Kendahl L. Ott ◽  
Heather R. Manring ◽  
Trevor Dew ◽  
Maegen A. Borzok ◽  
...  
Keyword(s):  
Hot Spot ◽  
Single Point ◽  
Md Simulations ◽  
Amino Acid Position ◽  
Target Site ◽  
Molecular Band ◽  
Single Point Mutation ◽  
Enzymatic Assays ◽  
Protein Levels ◽  
Clinical Variants

Desmoplakin (DSP) is a large (~260 kDa) protein found in the desmosome, a subcellular complex that links the cytoskeleton of one cell to its neighbor. A mutation ‘hot-spot’ within the NH2-terminal third of the DSP protein (specifically, residues 299–515) is associated with both cardiomyopathies and skin defects. In select DSP variants, disease is linked specifically to the uncovering of a previously-occluded calpain target site (residues 447–451). Here, we partially stabilize these calpain-sensitive DSP clinical variants through the addition of a secondary single point mutation—tyrosine for leucine at amino acid position 518 (L518Y). Molecular dynamic (MD) simulations and enzymatic assays reveal that this stabilizing mutation partially blocks access to the calpain target site, resulting in restored DSP protein levels. This ‘molecular band-aid’ provides a novel way to maintain DSP protein levels, which may lead to new strategies for treating this subset of DSP-related disorders.

scholarly journals Interfacial chemical bond and internal electric field modulated Z-scheme Sv-ZnIn2S4/MoSe2 photocatalyst for efficient hydrogen evolution

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xuehua Wang ◽  
Xianghu Wang ◽  
Jianfeng Huang ◽  
Shaoxiang Li ◽  
Alan Meng ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Electric Field ◽  
Hydrogen Evolution ◽  
Density Functional ◽  
Monochromatic Light ◽  
Density Functional Theory Calculations ◽  
Internal Electric Field ◽  
Apparent Quantum Yield ◽  
Paramagnetic Resonance ◽  
High Hydrogen

AbstractConstruction of Z-scheme heterostructure is of great significance for realizing efficient photocatalytic water splitting. However, the conscious modulation of Z-scheme charge transfer is still a great challenge. Herein, interfacial Mo-S bond and internal electric field modulated Z-scheme heterostructure composed by sulfur vacancies-rich ZnIn2S4 and MoSe2 was rationally fabricated for efficient photocatalytic hydrogen evolution. Systematic investigations reveal that Mo-S bond and internal electric field induce the Z-scheme charge transfer mechanism as confirmed by the surface photovoltage spectra, DMPO spin-trapping electron paramagnetic resonance spectra and density functional theory calculations. Under the intense synergy among the Mo-S bond, internal electric field and S-vacancies, the optimized photocatalyst exhibits high hydrogen evolution rate of 63.21 mmol∙g−1·h−1 with an apparent quantum yield of 76.48% at 420 nm monochromatic light, which is about 18.8-fold of the pristine ZIS. This work affords a useful inspiration on consciously modulating Z-scheme charge transfer by atomic-level interface control and internal electric field to signally promote the photocatalytic performance.

scholarly journals Mouse embryonic stem cell-derived cardiomyocytes cease to beat following exposure to monochromatic light: association with increased ROS and loss of calcium transients

2019 ◽  
Vol 317 (4) ◽  
pp. C725-C736
Author(s):  
Gurbind Singh ◽  
Divya Sridharan ◽  
Mahmood Khan ◽  
Polani B. Seshagiri
Keyword(s):  
Cell Biology ◽  
Fluorescent Protein ◽  
Es Cells ◽  
Monochromatic Light ◽  
Embryonic Stem ◽  
Mouse Embryonic Stem Cell ◽  
Medical Diagnostics ◽  
Calcium Transients ◽  
Egfp Expression ◽  
Mitochondrial Activity

We earlier established the mouse embryonic stem (ES) cell “GS-2” line expressing enhanced green fluorescent protein (EGFP) and have been routinely using it to understand the molecular regulation of differentiation into cardiomyocytes. During such studies, we made a serendipitous discovery that functional cardiomyocytes derived from ES cells stopped beating when exposed to blue light. We observed a gradual cessation of contractility within a few minutes, regardless of wavelength (nm) ranges tested: blue (~420–495), green (~510–575), and red (~600–700), with green light manifesting the strongest impact. Following shifting of cultures back into the incubator (darkness), cardiac clusters regained beatings within a few hours. The observed light-induced contractility-inhibition effect was intrinsic to cardiomyocytes and not due to interference from other cell types. Also, this was not influenced by any physicochemical parameters or intracellular EGFP expression. Interestingly, the light-induced cardiomyocyte contractility inhibition was accompanied by increased intracellular reactive oxygen species (ROS), which could be abolished in the presence of N-acetylcysteine (ROS quencher). Besides, the increased intracardiomyocyte ROS levels were incidental to the inhibition of calcium transients and suppression of mitochondrial activity, both being essential for sarcomere function. To the best of our knowledge, ours is the first report to demonstrate the monochromatic light-mediated inhibition of contractions of cardiomyocytes with no apparent loss of cell viability and contractility. Our findings have implications in cardiac cell biology context in terms of 1) mechanistic insights into light impact on cardiomyocyte contraction, 2) potential use in laser beam-guided (cardiac) microsurgery, photo-optics-dependent medical diagnostics, 3) transient cessation of hearts during coronary artery bypass grafting, and 4) functional preservation of hearts for transplantation.

BRIGHTNESS SCALES FOR MONOCHROMATIC LIGHT

1960 ◽  
Vol 1 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Gösta Ekman ◽  
Hannes Eisler ◽  
Teodor Künnapas
Keyword(s):  
Monochromatic Light

scholarly journals New Laboratory Data on a Molecular Band at 4429 A

2004 ◽  
Vol 616 (2) ◽  
pp. 1301-1310 ◽  
Author(s):  
M. Araki ◽  
H. Linnartz ◽  
P. Kolek ◽  
H. Ding ◽  
A. Boguslavskiy ◽  
...  
Keyword(s):  
Laboratory Data ◽  
Molecular Band

Decay of photo-induced conductivity in Sb-doped SnO2 thin films, using monochromatic light of about bandgap energy

2013 ◽  
Vol 267 ◽  
pp. 164-168 ◽  
Author(s):  
E.A. Floriano ◽  
L.V.A. Scalvi ◽  
J.R. Sambrano ◽  
A. de Andrade
Keyword(s):  
Thin Films ◽  
Monochromatic Light ◽  
Bandgap Energy ◽  
Sno2 Thin Films

Wavelength-dependent temporal properties of retinal horizontal cells in turtles

1990 ◽  
Vol 4 (05) ◽  
pp. 427-435 ◽  
Author(s):  
C.A. Dvorak ◽  
A.M. Granda
Keyword(s):  
Temporal Integration ◽  
Monochromatic Light ◽  
Maximum Amplitude ◽  
Light Response ◽  
Chelonia Mydas ◽  
Sea Turtle ◽  
Horizontal Cells ◽  
Freshwater Turtle ◽  
L Cells ◽  
Pseudemys Scripta

AbstractElectrical reponses of luminosity horizontal cells (L cells) to monochromatic stimuli were analyzed by intracellular recordings in the retinas of the freshwater turtle (Pseudemys scripta elegans) and of the sea turtle (Chelonia mydas mydas). Light intensity, duration, and wavelength were varied to assess temporal effects. For a given intensity of monochromatic light, response amplitude increased with stimulus duration until maximum amplitude occurred at a specific duration. This suprathreshold metric of temporal integration is calledhere summation time, and it is wavelength-dependent.L cells always had some level of red-sensitive cone input, although in some cells inputs from green- and blue-sensitive cones were also observed. For these latter cells, summation times were shorter for 640-nm than for 540-nm or 450-nm lights. These results were most evident in cells that received dominant inputs from blue- or green-sensitive cones.Responses of some other L cells were almost completely dominated by inputs from red-sensitive cones. Summation times of these cells were not wavelength-dependent. But when these inputs also included green-sensitive cones, shorter summation times were obtained to 640-nm light than to 540-nm light, even though dominant inputs were still from red-sensitive cones. These results, obtained from both retinal and 3,4-dehydroretinal photopigment systems, are consistent with reported observations inPseudemys scripta elegansthat show linear responses of red-sensitive cones to have shorterintegration times and times-to-peakthan green-sensitive cones.Responses from horizontal cells dominated by blue-sensitive cone inputs were the most sensitive of all; they also had the longest summation times. These results support the hypothesis that a gain in sensitivity occurs from the integration of absorbed photons over longer periods of time.These intracellular responses are of particular importance because behavioral critical durations in turtle, as defined by Bloch&'s law, are similarly wavelength-dependent.

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