Search results for "spectrum"

Visible-Light Organophotoredox-Catalyzed Synthesis of Precursors for Horner-Type Olefinations

2018

Searching for New Physics in two-neutrino double beta decay with CUPID

2021

Abstract In the past few years, attention has been drawn to the fact that a precision analysis of two-neutrino double beta decay (2υββ) allows the study of interesting physics cases like the emission of Majoron bosons and possible Lorentz symmetry violation. These processes modify the summed-energy distribution of the two electrons emitted in 2υββ. CUPID is a next-generation experiment aiming to exploit 100Mo-enriched scintillating Li2MoO4 crystals, operating as cryogenic calorimeters. Given the relatively fast half-life of 100Mo 2υββ and the large exposure that can be reached by CUPID, we expect to measure with very high precision the 100Mo 2υββ spectrum shape, reaching great sensitivities…

Cadmium clusters in CdI2layered crystals: the influence on the optical properties

2007

The influence of overstoichiometric Cd i atoms on the optical properties of cadmium iodide layered crystals has been investigated. The results of optical absorption, luminescence, and luminescence excitation studies of CdI 2 crystals with controlled deviation from stoichiometric composition allow observing correlations between the Cd i concentration and features in absorption and emission spectra up to concentrations of 10 18 cm -3 . At higher concentrations the overstoichiometric cadmium atoms form clusters, which were observed using scanning electron microscopy. The extinction spectra of (CdI i ) n clusters are calculated in the frame of Mie theory and are found to correlate with the opti…

Quantitative Raman spectroscopy as a tool to study the kinetics and formation mechanism of carbonates

2013

We have carried out a systematic study of abiotic precipitation at different temperatures of several Mg and Ca carbonates (calcite, nesquehonite, hydrocalcite) present in carbonaceous chondrites. This study highlights the capability of Raman spectroscopy as a primary tool for performing full mineralogical analysis. The precipitation reaction and the structure of the resulting carbonates were monitored and identified with Raman spectroscopy. Raman spectroscopy enabled us to confirm that the precipitation reaction is very fast (minutes) when Ca(II) is present in the solution, whereas for Mg(II) such reactions developed at rather slow rates (weeks). We also observed that both the composition a…

Wavelength dependence of oxidative DNA damage induced by UV and visible light.

1997

DNA damage induced by UV radiation and visible light (290-500 nm) in AS52 Chinese hamster cells was analysed by an alkaline elution assay with specific repair endonucleases. Cells were exposed to extensively filtered monochrome or broad-band radiation. Between 290 and 315 nm, the ratio of base modifications sensitive to Fpg protein (i.e. 8-hydroxyguanine and formamidopyrimidines) and T4 endonuclease V (i.e. cyclobutane pyrimidine dimers) was constant (approximately 1:200), indicating that the direct excitation of DNA is responsible for both types of damage in this range of the spectrum. While the yield of pyrimidine dimers per unit dose continued to decrease exponentially beyond 315 nm, the…

Evaluating the predictive power of sun-induced chlorophyll fluorescence to estimate net photosynthesis of vegetation canopies: A SCOPE modeling study

2016

Abstract Progress in imaging spectroscopy technology and data processing can enable derivation of the complete sun-induced chlorophyll fluorescence (SIF) emission spectrum. This opens up opportunities to fully exploit the use of the SIF spectrum as an indicator of photosynthetic activity. Simulations performed with the coupled fluorescence–photosynthesis model SCOPE were used to determine how strongly canopy-leaving SIF can be related to net photosynthesis of the canopy (NPC) for various canopy configurations. Regression analysis between SIF retrievals and NPC values produced the following general findings: (1) individual SIF bands that were most sensitive to NPC were located around the fir…

Evaluation of nutritional parameters in infant formulas and powdered milk by Raman spectroscopy

2007

It has been made a critical evaluation of the application of near infrared Fourier transform-Raman spectroscopy for the simultaneous determination of the most important nutritional parameters such as energetic value, carbohydrate, protein and fat contents of infant formula and powdered milk samples based on the use of partial least squares (PLS) regression analysis. A highly heterogeneous population of 23 samples, covering a wide range of infant food formula and powdered milk, were obtained from the Spanish market. Raman spectra, obtained by excitation with a Nd:YAG laser at 1064 nm, show no disturbing fluorescence effects; therefore sample spectra can be recorded without any previous prepa…

Highly Efficient Electron Transfer in a Carbon Dot–Polyoxometalate Nanohybrid

2020

Using solar radiation to fuel catalytic processes is often regarded as the solution to our energy needs. However, developing effective photocatalysts that are active under visible light has proven to be difficult, often due to the toxicity, instability, and high cost of suitable catalysts. We engineered a novel photoactive nanomaterial obtained by the spontaneous electrostatic coupling of carbon nanodots with [P2W18O62]6-, a molecular catalyst belonging to the class of polyoxometalates. While the former are used as photosensitizers, the latter was chosen for its ability to catalyze reductive reactions such as dye decomposition and water splitting. We find the electron transfer within the na…

Low Carbohydrate Diet (SCD/GAPS) for Children with Autistic Spectrum Disorder

2019

Objective of the study was to investigate the potential of low carbohydrate diet (SCD/ and supplements in reducing some autistic spectrum disorder ASD symptoms in children.

Exceptional affinity of nanostructured organic-inorganic hybrid materials towards dioxygen: confinement effect of copper complexes

2007

We report the exceptional reactivity towards dioxygen of a nanostructured organic-inorganic hybrid material due to the confinement of copper cyclam within a silica matrix. The key step is the metalation reaction of the ligand, which can occur before or after xerogel formation through the sol-gel process. The incorporation of a Cu(II) center into the material after xerogel formation leads to a bridged Cu(I)/Cu(II) mixed-valence dinuclear species. This complex exhibits a very high affinity towards dioxygen, attributable to auto-organization of the active species in the solid. The remarkable properties of these copper complexes in the silica matrix demonstrate a high cooperative effect for O(2…