Integrated optical device for Structured Illumination Microscopy

Structured Illumination Microscopy (SIM) is a key technology for high resolution and super-resolution imaging of biological cells and molecules. The spread of portable and easy-to-align SIM systems requires the development of novel methods to generate a light pattern and to shift it across the field of view of the microscope. Here we show a miniaturized chip that incorporates optical waveguides, splitters, and phase shifters, to generate a 2D structured illumination pattern suitable for SIM microscopy. The chip creates three point-sources, coherent and controlled in phase, without the need for further alignment. Placed in the pupil of a microscope's objective, the three sources generate a hexagonal illumination pattern on the sample, which is spatially translated thanks to thermal phase shifters. We validate and use the chip, upgrading a commercial inverted fluorescence microscope to a SIM setup and we image biological sample slides, extending the resolution of the microscope. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreemen

A computational approach to the characterization of a microfluidic device for continuous size-based inertial sorting

The application of fully-inertial size-based microfluidic filtration technologies for particle separation is an attractive tool, which not only offers label-free control of the microenvironment during separation, but also facilitates integration and automation for high throughput sample processing. In this work, we exploit 3D computational fluid dynamics (CFD) simulations based on the lattice Boltzmann method to evaluate the performance of a microfluidic device specifically designed to trap and extract particles by inertial focusing and microscale vortices. The device geometry consists of a straight microchannel, followed downstream by a microchamber with outlets for continuous size-based separation. Simulations were carried out to characterize the flow properties of the microfluidic device. Here, the influence of the Reynolds number (Re), the chamber dimensions and the outlet channels aspect ratio on the streamtracer distribution were studied. In order to support the simulation results, some preliminary experimental validations have been conducted, finding that the model can accurately characterize the flow in the studied geometry. The results of the simulations and experiments presented in this paper can be very useful to support the design of continuous-flow particle sorting lab-on-a-chip (LOC) devices

Yield stress “in a flash”: investigation of nonlinearity and yielding in soft materials with an optofluidic microrheometer

Yield stress materials deform as elastic solids or flow as viscous liquids, depending on the applied stress, which also allows them to trap particles below a certain size or density threshold. To investigate the conditions for such a transition at the microscale, we use an optofluidic microrheometer, based on the scattering of an infrared beam onto a microbead, which reaches forces in the nN scale. We perform creep experiments on a model soft material composed of swollen microgels, determining the limits of linear response and yield stress values, and observe quantitative agreement with bulk measurements. However, the motion of the microbead, both below and above yielding, reflects distinctive microscale features of the surrounding material, whose plastic rearrangements were investigated by us using small, passive tracers

Bose-Einstein correlations in ultrarelativistic heavy ion collisions

Results from the analysis of Bose-Einstein correlations of negative pions produced in central collisions of S + S, S + Ag, S + Au and O + Au at 200 GeV/N in a wide rapidity range 0.5 < y < 4.0 are presented. At mid-rapidity a transverse source size significantly larger than the projectile radius is observed in central S + Ag and O + Au collisions. A strong dependence of transverse and longitudinal sizes with rapidity, rapidity density and total multiplicity is observed. For S + S and S + Au the midrapidity correlation functions can not be fitted with a Gaussian parametrization. © 1991

Production of pi0 and η mesons up to high transverse momentum in pp collisions at 2.76 TeV

The invariant differential cross sections for inclusive Ï0 and η mesons at midrapidity were measured in pp collisions at s=2.76 TeV for transverse momenta 0.4 < pT< 40 GeV/c and 0.6 < pT< 20 GeV/c, respectively, using the ALICE detector. This large range in pT was achieved by combining various analysis techniques and different triggers involving the electromagnetic calorimeter (EMCal). In particular, a new single-cluster, shower-shape based method was developed for the identification of high-pT neutral pions, which exploits that the showers originating from their decay photons overlap in the EMCal. Above 4 GeV/c, the measured cross sections are found to exhibit a similar power-law behavior with an exponent of about 6.3. Next-to-leading-order perturbative QCD calculations differ from the measured cross sections by about 30% for the Ï0, and between 30â50% for the η meson, while generator-level simulations with PYTHIA 8.2 describe the data to better than 10â30%, except at pT< 1 GeV/c. The new data can therefore be used to further improve the theoretical description of Ï0 and η meson production

Direct photon production at low transverse momentum in proton-proton collisions at root s=2.76 and 8 TeV

Measurements of inclusive and direct photon production at midrapidity in pp collisions at s=2.76 and 8 TeV are presented by the ALICE experiment at the LHC. The results are reported in transverse momentum ranges of 0.4&lt;10 GeV/c and 0.3&lt;16 GeV/c, respectively. Photons are detected with the electromagnetic calorimeter (EMCal) and via reconstruction of e+e- pairs from conversions in the ALICE detector material using the central tracking system. For the final measurement of the inclusive photon spectra the results are combined in the overlapping pT interval of both methods. Direct photon spectra, or their upper limits at 90% C.L. are extracted using the direct photon excess ratio Rγ, which quantifies the ratio of inclusive photons over decay photons generated with a decay-photon simulation. An additional hybrid method, combining photons reconstructed from conversions with those identified in the EMCal, is used for the combination of the direct photon excess ratio Rγ, as well as the extraction of direct photon spectra or their upper limits. While no significant signal of direct photons is seen over the full pT range, Rγ for pT&gt;7 GeV/c is at least one σ above unity and consistent with expectations from next-to-leading order pQCD calculations

Direct photon production at low transverse momentum in proton-proton collisions at root s=2.76 and 8 TeV

Measurements of inclusive and direct photon production at midrapidity in pp collisions at 1as = 2.76 and 8 TeV are presented by the ALICE experiment at the LHC. The results are reported in transverse momentum ranges of 0.4 7 GeV/c is at least one \u3c3 above unity and consistent with expectations from next-to-leading order pQCD calculations

Production of pi(0) and eta mesons up to high transverse momentum in pp collisions at 2.76 TeV

The invariant differential cross sections for inclusive pi(0) and eta mesons at midrapidity were measured in pp collisions at root s = 2.76 TeV for transverse momenta 0.4 < pT < 40 GeV/c and 0.6 < pT < 20 GeV/c, respectively, using the ALICE detector. This large range in pT was achieved by combining various analysis techniques and different triggers involving the electromagnetic calorimeter (EMCal). In particular, a newsingle-cluster, shower-shape based method was developed for the identification of high-pT neutral pions, which exploits that the showers originating from their decay photons overlap in the EMCal. Above 4 GeV/c, the measured cross sections are found to exhibit a similar power-law behavior with an exponent of about 6.3. Next-to-leading-order perturbative QCD calculations differ from the measured cross sections by about 30% for the pi(0), and between 30-50% for the. meson, while generator-level simulations with PYTHIA 8.2 describe the data to better than 10-30%, except at pT < 1 GeV/c. The new data can therefore be used to further improve the theoretical description of pi(0) and eta meson production