Search results for "Lasers"

Photon scattering as a probe of microviscosity and channel size in gels such as sickle haemoglobin.

1983

The aggregation of sickle-cell haemoglobin (HbS) is one of the most physiologically important and widely studied macromolecular gelation processes. Both the thermodynamics and kinetics of the process are important in determining the pathological consequences of deoxygenation of the red cells (and both must be understood if a rational strategy is to be developed for pharmacological intervention). We describe here a new and versatile technique for the study of the structure and formation of the HbS aggregates, that should be widely applicable to gel systems generally. We use laser autocorrelation spectroscopy to observe the diffusion of monodisperse polystyrene latex spheres in the interstice…

Using synchrotrons and XFELs for time-resolved X-ray crystallography and solution scattering experiments on biomolecules

2015

International audience; Time-resolved structural information is key to understand the mechanism of biological processes, such as catalysis and signalling. Recent developments in X-ray sources as well as data collection and analysis methods are making routine time-resolved X-ray crystallography and solution scattering experiments a real possibility for structural biologists. Here we review the information that can be obtained from these techniques and discuss the considerations that must be taken into account when designing a time-resolved experiment.

Changes in NMDA-receptor function in the first week following laser-induced lesions in rat visual cortex.

2011

Focal brain injuries are accompanied by processes of functional reorganization that partially compensate the functional loss. In a previous study, extracellular recordings at the border of a laser-induced lesion in the visual cortex of rats showed an enhanced synaptic plasticity, which was mediated by the activity of NR2B-contaning NMDA-receptors (NMDARs) shedding light on the potential cellular mechanisms underlying this reorganization. Given the potentially important contribution of NMDARs in processes of functional reorganization, in the present study, we used the same lesion model to further investigate lesion-induced changes in function and localization of NMDARs in the vicinity of the…

Wavelength tuning of femtosecond pulses generated in nonlinear crystals by using diffractive lenses

2010

We demonstrate that diffractive lenses (DLs) can be used as a simple method to tune the central wavelength of femtosecond pulses generated from second-order nonlinear optical processes in birefringent crystals. The wavelength tunability is achieved by changing the relative distance between the nonlinear crystal and the DL, which acts in a focusing configuration. Besides the many practical applications of the so-generated pulses, the proposed method might be extended to other wavelength ranges by demonstrated similar effects on other nonlinear processes, such as high-order harmonic generation.

Q-switched mode locking noise-like pulse generation from a thulium-doped all-fiber laser based on nonlinear polarization rotation

2021

Abstract Q-switched mode locking (QML) noise-like pulse (NLP) emission from an all-fiber thulium-doped laser based on the nonlinear polarization rotation effect is reported. The QML emission is obtained in a cavity with net anomalous dispersion in a pump power interval in between the CW laser threshold and the threshold of the NLP regime. Highest-energy QML pulses were observed with a repetition rate of 812 kHz with a pump power of 520 mW at the optical wavelength of 1881.09 nm. A maximum overall energy of 460 nJ at an average output power of 6.4 mW was reached, which corresponds to a burst of mode-locked noise-like sub-pulses with 8.7 ns of pulse duration within a QML envelope of 11 µs. Th…

Very high specific activity erbium 169Er production for potential receptor-targeted radiotherapy

2019

Erbium 169Er is one of the most interesting radiolanthanides for new potential receptor-targeted β− therapy applications due to its low energy β− emissions, very low intensity ɣ rays and the possibility to use 68Ga or 44Sc as companion for diagnostic in a theranostics approach. Currently it can be produced in reactors through the neutron activation of highly enriched 168Er. The low specific activity of the produced carrier-added 169Er is limiting its use for receptor-targeted therapy. Nonetheless it is used for radiosynoviorthesis of small joints. The aim of this work is to develop a new large-scale production method for the supply of very high specific activity 169Er. Highly enriched 168Er…

IRIDE: Interdisciplinary research infrastructure based on dual electron linacs and lasers

2014

This paper describes the scientific aims and potentials as well as the preliminary technical design of RUDE, an innovative tool for multi-disciplinary investigations in a wide field of scientific, technological and industrial applications. IRIDE will be a high intensity "particles factory", based on a combination of high duty cycle radio-frequency superconducting electron linacs and of high energy lasers. Conceived to provide unique research possibilities for particle physics, for condensed matter physics, chemistry and material science, for structural biology and industrial applications, IRIDE will open completely new research possibilities and advance our knowledge in many branches of sci…

Mixture and dissolution of laser polarized noble gases: Spectroscopic and imaging applications

2012

Transient Radiation Responses of Optical Fibers: Influence of MCVD Process Parameters

2012

International audience; A dedicated set of fibers elaborated via the Modified Chemical Vapor Deposition (MCVD) technique is used to study the influence of composition and drawing parameters on their responses to an X-ray pulse representative of the radiation environments associated with Megajoule class lasers. These canonical fibers were designed to highlight the impact of these parameters on the amplitude and kinetics of the transient pulsed X-ray Radiation Induced Attenuation (RIA) at room temperature. From preforms differing by their core composition, three optical fibers were elaborated by varying the tension and speed during the drawing process. No or only slight RIA change results fro…

Revisiting the metallothionein genes polymorphisms and the risk of oral squamous cell carcinoma in a Brazilian population

2020

Background Metallothioneins (MTs) gene polymorphisms have been associated with the ability of free radical scavenging and detoxification of heavy metals leading to cancer development. Our aim was to revisit, in a Brazilian population, single-nucleotide polymorphisms (SNPs) of the MT gene family previously associated with oral squamous cell carcinoma (OSCC). Material and Methods A case-control investigation with 28 OSCC patients and 45 controls was conducted, using conventional risk factors (tobacco use and alcohol consumption) as covariates. SNPs genotyping for rs8052334 (MT1B), rs964372 (MT1B), and rs1610216 (MT2A) was performed by PCR-RFLP, and SNPs for rs11076161 (MT1A) were analyzed by …