14 research outputs found
Laser-Induced Cavitation for Controlling Crystallization from Solution
We demonstrate that a cavitation bubble initiated by a Nd:YAG laser pulse
below breakdown threshold induces crystallization from supersaturated aqueous
solutions with supersaturation and laser-energy dependent nucleation kinetics.
Combining high-speed video microscopy and simulations, we argue that a
competition between the dissipation of absorbed laser energy as latent and
sensible heat dictates the solvent evaporation rate and creates a momentary
supersaturation peak at the vapor-liquid interface. The number and morphology
of crystals correlate to the characteristics of the simulated supersaturation
peak
Low-cost fluorescence microscope with microfluidic device fabrication for optofluidic applications
Optofluidic devices have revolutionized the manipulation and transportation
of fluid at smaller length scales ranging from micrometers to millimeters. We
describe a dedicated optical setup for studying laser-induced cavitation inside
a microchannel. In a typical experiment, we use a tightly focused laser beam to
locally evaporate the solution laced with a dye resulting in the formation of a
microbubble. The evolving bubble interface is tracked using high-speed
microscopy and digital image analysis. Furthermore, we extend this system to
analyze fluid flow through fluorescenceParticle Image Velocimetry (PIV)
technique with minimal adaptations. In addition, we demonstrate the protocols
for the in-house fabrication of a microchannel tailored to function as a sample
holder in this optical setup. In essence, we present a complete guide for
constructing a fluorescence microscope from scratch using standard optical
components with flexibility in the design and at a lower cost compared to its
commercial analogues.Comment: N. Nagalingam and A. Raghunathan contributed equally to this wor
Resolving Power of Visible to Near-Infrared Hybrid -Ta/NbTiN Kinetic Inductance Detectors
Kinetic Inductance Detectors (KIDs) are superconducting energy-resolving
detectors, sensitive to single photons from the near-infrared to ultraviolet.
We study a hybrid KID design consisting of a beta phase tantalum (-Ta)
inductor and a NbTiN interdigitated capacitor (IDC). The devices show an
average intrinsic quality factor of 4.3 1.3
. To increase the power captured by the light sensitive inductor,
we 3D-print an array of 150150 m resin micro lenses on the
backside of the sapphire substrate. The shape deviation between design and
printed lenses is smaller than 1m, and the alignment accuracy of this
process is m and
m. We measure a resolving power for 1545-402 nm that is limited to 4.9 by
saturation in the KID's phase response. We can model the saturation in the
phase response with the evolution of the number of quasiparticles generated by
a photon event. An alternative coordinate system that has a linear response
raises the resolving power to 5.9 at 402 nm. We verify the measured resolving
power with a two-line measurement using a laser source and a monochromator. We
discuss several improvements that can be made to the devices on a route towards
KID arrays with high resolving powers.Comment: 11 pages, 9 Figues, Journal Pape
Soleil: single-objective lens inclined light sheet localization microscopy
High-NA light sheet illumination can improve the resolution of single-molecule localization microscopy (SMLM) by reducing the background fluorescence. These approaches currently require custom-made sample holders or additional specialized objectives, which makes the sample mounting or the optical system complex and therefore reduces the usability of these approaches. Here, we developed a single-objective lens-inclined light sheet microscope (SOLEIL) that is capable of 2D and 3D SMLM in thick samples. SOLEIL combines oblique illumination with point spread function PSF engineering to enable dSTORM imaging in a wide variety of samples. SOLEIL is compatible with standard sample holders and off-the-shelve optics and standard high NA objectives. To accomplish optimal optical sectioning we show that there is an ideal oblique angle and sheet thickness. Furthermore, to show what optical sectioning delivers for SMLM we benchmark SOLEIL against widefield and HILO microscopy with several biological samples. SOLEIL delivers in 15 μm thick Caco2-BBE cells a 374% higher intensity to background ratio and a 54% improvement in the estimated CRLB compared to widefield illumination, and a 184% higher intensity to background ratio and a 20% improvement in the estimated CRLB compared to HILO illumination
Integration of Parallel Opposing Memories Underlies Memory Extinction.
Accurately predicting an outcome requires that animals learn supporting and conflicting evidence from sequential experience. In mammals and invertebrates, learned fear responses can be suppressed by experiencing predictive cues without punishment, a process called memory extinction. Here, we show that extinction of aversive memories in Drosophila requires specific dopaminergic neurons, which indicate that omission of punishment is remembered as a positive experience. Functional imaging revealed co-existence of intracellular calcium traces in different places in the mushroom body output neuron network for both the original aversive memory and a new appetitive extinction memory. Light and ultrastructural anatomy are consistent with parallel competing memories being combined within mushroom body output neurons that direct avoidance. Indeed, extinction-evoked plasticity in a pair of these neurons neutralizes the potentiated odor response imposed in the network by aversive learning. Therefore, flies track the accuracy of learned expectations by accumulating and integrating memories of conflicting events.S.W. was funded by a Wellcome Principal Research Fellowship (200846/Z/16/Z), by the Gatsby Charitable Foundation (GAT3237), and by the Bettencourt-Schueller Foundation. J.F. was supported by the DFG (FE 1563/1-1). G.S.X.E.J. was funded by Medical Research Council. D.D.B. funded by HHMI. G.S.X.E.J., D.D.B., and S.W. were funded by a Wellcome Collaborative Award (203261/Z/16/Z)
Nuclear accessibility of beta-actin mRNA is measured by 3D single-molecule real-time tracking
Imaging single proteins or RNAs allows direct visualization of the inner workings of the cell. Typically, three-dimensional (3D) images are acquired by sequentially capturing a series of 2D sections. The time required to step through the sample often impedes imaging of large numbers of rapidly moving molecules. Here we applied multifocus microscopy (MFM) to instantaneously capture 3D single-molecule real-time images in live cells, visualizing cell nuclei at 10 volumes per second. We developed image analysis techniques to analyze messenger RNA (mRNA) diffusion in the entire volume of the nucleus. Combining MFM with precise registration between fluorescently labeled mRNA, nuclear pore complexes, and chromatin, we obtained globally optimal image alignment within 80-nm precision using transformation models. We show that beta-actin mRNAs freely access the entire nucleus and fewer than 60% of mRNAs are more than 0.5 microm away from a nuclear pore, and we do so for the first time accounting for spatial inhomogeneity of nuclear organization
Quantifying the minimum localization uncertainty of image scanning localization microscopy
Modulation enhanced single-molecule localization microscopy (meSMLM), where emitters are sparsely activated with sequentially applied patterned illumination, increases the localization precision over single-molecule localization microscopy (SMLM). The precision improvement of modulation enhanced SMLM is derived from retrieving the position of an emitter relative to individual illumination patterns, which adds to existing point spread function information from SMLM. Here, we introduce SpinFlux: modulation enhanced localization for spinning disk confocal microscopy. SpinFlux uses a spinning disk with pinholes in its illumination and emission paths, to sequentially illuminate regions in the sample during each measurement. The resulting intensity-modulated emission signal is analyzed for each individual pattern to localize emitters with improved precision. We derive a statistical image formation model for SpinFlux and we quantify the theoretical minimum localization uncertainty in terms of the Cramér-Rao lower bound. Using the theoretical minimum uncertainty, we compare SpinFlux to localization on Fourier reweighted image scanning microscopy reconstructions. We find that localization on image scanning microscopy reconstructions with Fourier reweighting ideally results in a global precision improvement of 2.1 over SMLM. When SpinFlux is used for sequential illumination with three patterns around the emitter position, the localization precision improvement over SMLM is twofold when patterns are focused around the emitter position. If four donut-shaped illumination patterns are used for SpinFlux, the maximum local precision improvement over SMLM is increased to 3.5. Localization of image scanning microscopy reconstructions thus has the largest potential for global improvements of the localization precision, where SpinFlux is the method of choice for local refinements
Linear analytical solution to the phase diversity problem for extended objects based on the Born approximation
In this paper we give a new wavefront estimation technique that overcomes the main disadvantages of the phase diversity (PD) algorithms, namely the large computational complexity and the fact that the solutions can get stuck in a local minima. Our approach gives a good starting point for an iterative algorithm based on solving a linear system, but it can also be used as a new wavefront estimation method. The method is based on the Born approximation of the wavefront for small phase aberrations which leads to a quadratic point-spread function (PSF), and it requires two diversity images. First we take the differences between the focal plane image and each of the two diversity images, and then we eliminate the constant object, element-wise, from the two equations. The result is an overdetermined set of linear equations for which we give three solutions using linear least squares (LS), truncated total least squares (TTLS) and bounded data uncertainty (BDU). The last two approaches are suited when considering measurements affected by noise. Simulation results show that the estimation is faster than conventional PD algorithms
SOLEIL: Single-objective lens inclined light sheet localization microscopy
High-NA light sheet illumination can improve the resolution of single-molecule localization microscopy (SMLM) by reducing the background fluorescence. These approaches currently require custom-made sample holders or additional specialized objectives, which makes the sample mounting or the optical system complex and therefore reduces the usability of these approaches. Here, we developed a single-objective lens-inclined light sheet microscope (SOLEIL) that is capable of 2D and 3D SMLM in thick samples. SOLEIL combines oblique illumination with point spread function PSF engineering to enable dSTORM imaging in a wide variety of samples. SOLEIL is compatible with standard sample holders and off-the-shelve optics and standard high NA objectives. To accomplish optimal optical sectioning we show that there is an ideal oblique angle and sheet thickness. Furthermore, to show what optical sectioning delivers for SMLM we benchmark SOLEIL against widefield and HILO microscopy with several biological samples. SOLEIL delivers in 15 μm thick Caco2-BBE cells a 374% higher intensity to background ratio and a 54% improvement in the estimated CRLB compared to widefield illumination, and a 184% higher intensity to background ratio and a 20% improvement in the estimated CRLB compared to HILO illumination. Team Carlas SmithBN/Kristin Grussmayer LabTeam Michel VerhaegenImPhys/Computational Imagin