Investigation of the thermal lens effect in water–ethanol mixtures: composition dependence of the refractive index gradient, the enhancement factor and the Soret effect

In this study, the application of thermal lens spectroscopy to detection of analytes in agarose gels was examined. It was found that a long-term refractive index gradient is produced in the sample, in addition to the thermally induced refractive index gradient, and gives rise to a long-term thermal lens signal. It is argued that the most likely source of the long-term signal is a concentration gradient formed in the sample. The long-term refractive index gradient results in a focusing lens, and is thus opposite to the thermal gradient. The formation of this gradient requires as much as 500 s to reach equilibrium during constant irradiation. The existence of the long-term refractive index gradient is verified by time-resolved Z-scan experiments. The signal resulting from this gradient is termed the long-term thermal lens and is shown to depend on temperature, is observed only for gelled agarose solutions, and is sensitive to anisotropies in the sample.

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SIMULTANEOUS MEASUREMENTS OF THE THERMAL DIFFUSION COEFFICIENT AND OF THE THERMAL CONDUCTIVITY OF TRANSPARENT MEDIA, BY MEANS OF A THERMAL LENS EFFECT

Le Journal de Physique Colloques ◽

10.1051/jphyscol:1972122 ◽

1972 ◽

Vol 33 (C1) ◽

pp. C1-125-C1-129 ◽

Cited By ~ 2

Author(s):

P. CALMETTES ◽

C. LAJ

Keyword(s):

Thermal Conductivity ◽

Diffusion Coefficient ◽

Thermal Diffusion ◽

Thermal Lens ◽

Thermal Diffusion Coefficient ◽

Lens Effect ◽

Simultaneous Measurements ◽

Transparent Media ◽

Thermal Lens Effect

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A Refractive INdex Gradient (RING) diagnostic for transient discharges or expansions of vapor or plasmas

IEEE Transactions on Plasma Science ◽

10.1109/27.108417 ◽

1991 ◽

Vol 19 (5) ◽

pp. 800-813 ◽

Cited By ~ 19

Author(s):

M.E. Cuneo ◽

T.R. Lockner ◽

G.C. Tisone

Keyword(s):

Refractive Index ◽

Refractive Index Gradient ◽

Index Gradient

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The Reflection of Waves at a Discontinuity in Refractive Index Gradient

Journal of Mathematics and Physics ◽

10.1002/sapm1966451162 ◽

1966 ◽

Vol 45 (1-4) ◽

pp. 162-168 ◽

Cited By ~ 2

Author(s):

R. Burman

Keyword(s):

Refractive Index ◽

Refractive Index Gradient ◽

Index Gradient ◽

Reflection Of Waves

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Comparisons between high-resolution profiles of squared refractive index gradient <i>M</i><sup>2</sup> measured by the Middle and Upper Atmosphere Radar and unmanned aerial vehicles (UAVs) during the Shigaraki UAV-Radar Experiment 2015 campaign

Annales Geophysicae ◽

10.5194/angeo-35-423-2017 ◽

2017 ◽

Vol 35 (3) ◽

pp. 423-441 ◽

Cited By ~ 5

Author(s):

Hubert Luce ◽

Lakshmi Kantha ◽

Hiroyuki Hashiguchi ◽

Dale Lawrence ◽

Masanori Yabuki ◽

...

Keyword(s):

Refractive Index ◽

Convective Cloud ◽

Upper Atmosphere ◽

Refractive Index Gradient ◽

Very High Frequency ◽

Range Resolution ◽

Mu Radar ◽

Radar Echo ◽

Index Gradient ◽

Complex Features

Abstract. New comparisons between the square of the generalized potential refractive index gradient M2, estimated from the very high-frequency (VHF) Middle and Upper Atmosphere (MU) Radar, located at Shigaraki, Japan, and unmanned aerial vehicle (UAV) measurements are presented. These comparisons were performed at unprecedented temporal and range resolutions (1–4 min and ∼  20 m, respectively) in the altitude range ∼  1.27–4.5 km from simultaneous and nearly collocated measurements made during the ShUREX (Shigaraki UAV-Radar Experiment) 2015 campaign. Seven consecutive UAV flights made during daytime on 7 June 2015 were used for this purpose. The MU Radar was operated in range imaging mode for improving the range resolution at vertical incidence (typically a few tens of meters). The proportionality of the radar echo power to M2 is reported for the first time at such high time and range resolutions for stratified conditions for which Fresnel scatter or a reflection mechanism is expected. In more complex features obtained for a range of turbulent layers generated by shear instabilities or associated with convective cloud cells, M2 estimated from UAV data does not reproduce observed radar echo power profiles. Proposed interpretations of this discrepancy are presented.

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Label-Free Digital Holo-tomographic Microscopy Reveals Virus-Induced Cytopathic Effects in Live Cells

mSphere ◽

10.1128/mspheredirect.00599-18 ◽

2018 ◽

Vol 3 (6) ◽

Cited By ~ 5

Author(s):

Artur Yakimovich ◽

Robert Witte ◽

Vardan Andriasyan ◽

Fanny Georgi ◽

Urs F. Greber

Keyword(s):

Refractive Index ◽

Vaccinia Virus ◽

Virus Type ◽

Live Cells ◽

Refractive Index Gradient ◽

Label Free ◽

Virus Infections ◽

Cytopathic Effects ◽

Infected Cells ◽

Index Gradient

ABSTRACTCytopathic effects (CPEs) are a hallmark of infections. CPEs are difficult to observe due to phototoxicity from classical light microscopy. We report distinct patterns of virus infections in live cells using digital holo-tomographic microscopy (DHTM). DHTM is label-free and records the phase shift of low-energy light passing through the specimen on a transparent surface with minimal perturbation. DHTM measures the refractive index (RI) and computes the refractive index gradient (RIG), unveiling optical heterogeneity in cells. We find that vaccinia virus (VACV), herpes simplex virus (HSV), and rhinovirus (RV) infections progressively and distinctly increased RIG. VACV infection, but not HSV and RV infections, induced oscillations of cell volume, while all three viruses altered cytoplasmic membrane dynamics and induced apoptotic features akin to those caused by the chemical compound staurosporine. In sum, we introduce DHTM for quantitative label-free microscopy in infection research and uncover virus type-specific changes and CPE in living cells with minimal interference.IMPORTANCEThis study introduces label-free digital holo-tomographic microscopy (DHTM) and refractive index gradient (RIG) measurements of live, virus-infected cells. We use DHTM to describe virus type-specific cytopathic effects, including cyclic volume changes of vaccinia virus infections, and cytoplasmic condensations in herpesvirus and rhinovirus infections, distinct from apoptotic cells. This work shows for the first time that DHTM is suitable to observe virus-infected cells and distinguishes virus type-specific signatures under noninvasive conditions. It provides a basis for future studies, where correlative fluorescence microscopy of cell and virus structures annotate distinct RIG values derived from DHTM.

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