Facing the challenge of biosample imaging by FTIR with a synchrotron radiation source

FTIR synchrotron radiation microspectroscopy is a powerful molecular probe of biological samples at cellular resolution. Here it is discussed how an optimized combination of IR instrumentation (FPA detectors) and SR optical systems could reach the expected advantages of a SR-based system

Facing the challenge of biosample imaging by FTIR with a synchrotron radiation source

Fourier-transform infrared (FTIR) synchrotron radiation (SR) microspectroscopy is a powerful molecular probe of biological samples at cellular resolution (10 microm). As the brilliance of SR is 100-1000 times higher than that of a conventional Globar source, FTIR microscopes are now available in almost all advanced SR facilities around the world. However, in spite of this superior performance, the expected advances in IR SR microscopy have not yet been realised, particularly with regard to bio-analytical studies of single cells and soft tissues. In recent decades solid-state array detectors have revolutionized the fields of molecular spectroscopy and chemical imaging, and now new IR focal plane array detectors implemented at ultra-bright SR facilities will extend the performance and overcome the existing limitations, possibly allowing IR SR instrumentation to achieve the highest sensitivity and resolution of molecular imaging. The impact of IR imaging on large tissue area and the complexity of the analysis are discussed. In view of the high brilliance of SR sources, a comparison of published microscope images is given. Finally, it is briefly outlined how an optimized combination of IR instrumentation and SR optical systems could reach the expected advantages of a SR-based FTIR imaging system

Proximity array device: a novel photon detector working in long wavelengths

We present here an innovative photon detector based on the proximity junction array device (PAD) working at long wavelengths. We show that the vortex dynamics in PAD undergoes a transition from a Mott insulator to a vortex metal state by application of an external magnetic field. The PAD also evidences a Josephson I-V characteristic with the external field dependent tunneling current. At high applied currents, we observe a dissipative regime in which the vortex dynamics is dominated by the quasi-particle contribution from the normal metal. The PAD has a relatively high photo-response even at frequencies below the expected characteristic frequency while, its superconducting properties such as the order parameter and the Josephson characteristic frequency can be modulated via external fields to widen the detection band. This device represents a promising and reliable candidate for new high-sensitivity long-wavelength detectors. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Transcriptional modulations induced by proton irradiation in mice skin in function of adsorbed dose and distance

Hadron therapy by proton beams represents an advanced anti-cancer strategy due to its highly localized dose deposition allowing a greater sparing of normal tissue and/or organs at risk compared to photon/electron radiotherapy. However, it is not clear to what extent non-targeted effects such as transcriptional modulations produced along the beamline may diffuse and impact the surrounding tissue. In this work, we analyze the transcriptome of proton-irradiated mouse skin and choose two biomarker genes to trace their modulation at different distances from the beam's target and at different doses and times from irradiation to understand to what extent and how far it may propagate, using RNA-Seq and quantitative RT-PCR. In parallel, assessment of lipids alteration is performed by FTIR spectroscopy as a measure of tissue damage. Despite the observed high individual variability of expression, we can show evidence of transcriptional modulation of two biomarker genes at considerable distance from the beam's target where a simulation system predicts a significantly lower adsorbed dose. The results are compatible with a model involving diffusion of transcripts or regulatory molecules from high dose irradiated cells to distant tissue's portions adsorbing a much lower fraction of radiation

High-Temperature Evolution of Point Defect Equilibria in Hydrous Forsterite Synthesized at 1100 C and up to 4 GPa

Water distribution in the deep Earth represents one of the most important topics in the field of geodynamics due to its large impact on the physical and chemical properties of the Earth’s mantle, such as electrical conductivity, seismic anisotropy, di usion, and rheology. In this study, we synthesized hydrous forsterite at 1100 C and up to 4 GPa with either a piston-cylinder or multianvil apparatus. As a starting material, we used synthetic forsterite, unbu ered by SiO2, obtained by thermo-mechanical activation of talc and magnesium carbonate hydroxide. Hydration was carried out using liquid H2O as hydrogen source. Samples were polycrystalline in an e ort to distribute H2O throughout the sample both rapidly and homogeneously. Using the Paterson calibration, we observed total water content concentrations ranging between 100 and 500 ppm wt H2O. Multiple absorption bands are found in the frequency range between 3400 and 3650 cm1, identifying at least seven peaks in all samples. Vibrational bands were centered at 3476, 3535, 3550, 3566, 3578, 3605, and 3612 cm1, in good agreement with experimental studies conducted on both hydrous forsterite and single crystals of olivine. The stronger OH stretching peaks can be attributed to vibrational modes associated with the hydrogarnet defect 4Hx Si in which four protons occupy a vacant tetrahedral site. None of the OH bands observed are found at frequencies associated with hydrogen occupying vacant octahedral sites. High-temperature FTIR spectroscopy was used to evaluate the evolution of IR spectra as a function of temperature, up to 500 C. The complete reversibility of peak absorption vs. temperature in the OH stretching region confirms that no water loss occurred during heating. We observe an overall a decrease in total absorption with increasing temperature, and a prominent decrease in the relative intensities of the higher frequency bands (>3600 cm1) with respect to lower frequency bands. We have assigned a series of equilibrium expressions based on the variation of relative peak areas with temperature and find that enthalpies of these processes range between 0.047–0.068 eV (4.5–6.5 kJ/mol), very low in comparison to activation energies observed for electrical conduction in hydrous olivine. Major changes in the vibrational spectrum are expected to be related to configurational changes of the same fully protonated hydrogarnet defect species. However, the complexity of the FTIR spectra may also be related to partially protonated defects, such as the associate defect 3H0Si + H i generated by a dissociation reaction of the hydrogarnet species.Publishedid 5743V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcaniciJCR Journa

OPTICAL PERFORMANCES OF SINBAD, THE INFRARED BEAMLINE AT DAFNE

SINBAD (Synchrotron Infrared Beamline At DANE) is the first Italian synchrotron radiation beamline operating in the infrared range. It collects the radiation emitted by DANE, an electron–positron collider designed to work at 0.51 GeV with a beam current I1 A. The actual performances of the beamline, in terms of brilliance gain with respect to blackbodies and polarization properties, are presented and discussed. Finally, the stability of the SINBAD source, a critical issue for Fourier-transform infrared spectroscopy, is discussed

The diffusion kinetics of CO2 in cordierite: an HT-FTIR microspectroscopy study

In this study, we describe the first FTIR measurements of CO2 desorption from cordierite, a microporous mineral stable up to high T conditions. To this purpose, we collected isothermal heating data on several (001) oriented sections of a well-characterized CO2-rich sample. Single-crystal slabs were heat-treated up to 1000 °C, and the intensity of the ν3 antisymmetric stretching mode of CO2 at 2348 cm−1 was monitored as a function of time. The experimental data were modeled by using the mono-dimensional plane-sheet diffusion formalism; diffusion coefficients were plotted in the Arrhenius space and activation energies were calculated. Final data are as follows: −logD0 = 4.2 ± 0.5 m2/s and Ea = 208 ± 11 kJ/mol. Comparison with diffusion data from the literature (Lepezin and Osorgin in Rossijskaa Akademia Nauk 339:658–661, 1994) shows that at 800 °C H2O diffuses almost two orders of magnitude faster than CO2 along the structural channels of cordierite, with the difference in diffusion coefficients increasing at lower temperatures, and this implies that at lower temperatures H2O mobility is more favored compared to CO2. Therefore, the volatile contents measured in exhumed rocks may not reflect the H2O/CO2 ratio upon cordierite crystallization, and this could significantly affect the thermodynamic calculations for fluid activities or peak metamorphic conditions