Search results for "spectrum"
showing 10 items of 2043 documents
Time-Gated Raman Spectroscopy for Quantitative Determination of Solid-State Forms of Fluorescent Pharmaceuticals
2018
Raman spectroscopy is widely used for quantitative pharmaceutical analysis, but a common obstacle to its use is sample fluorescence masking the Raman signal. Time-gating provides an instrument-based method for rejecting fluorescence through temporal resolution of the spectral signal and allows Raman spectra of fluorescent materials to be obtained. An additional practical advantage is that analysis is possible in ambient lighting. This study assesses the efficacy of time-gated Raman spectroscopy for the quantitative measurement of fluorescent pharmaceuticals. Time-gated Raman spectroscopy with a 128 X (2) X 4 CMOS SPAD detector was applied for quantitative analysis of ternary mixtures of sol…
A study on the fragmentation of sulfuric acid and dimethylamine clusters inside an Atmospheric Pressure interface Time Of Flight Mass Spectrometer
2021
Abstract. Sulfuric acid and dimethylamine vapours in the atmosphere can form molecular clusters, which participate in new particle formation events. In this work, we have produced, measured and identified clusters of sulfuric acid and dimethylamine using an electrospray ionizer coupled with a planar differential mobility analyser, connected to an atmospheric pressure interface time-of-flight mass spectrometer (ESI–DMA–APi-TOF MS). This set-up is suitable for evaluating the extent of fragmentation of the charged clusters inside the instrument. We evaluated the fragmentation of 11 negatively charged clusters both experimentally and using a statistical model based on quantum chemical data. The…
Defects in quantum ring to control high-harmonic spectrum
2017
AbstractThe high-harmonic generation from a structured quantum ring (SQR) driven by an intense laser field is presented within the single active electron approximation. The spectrum is studied by varying the symmetry of the physical system. The standard SQR (six identical and equidistant dots in a ring) presents a 60° rotational symmetry, that in this work is broken, moving or changing only one potential hole. We find that careful designed breaking of the geometrical symmetry of the SQR opens the possibility of controlling the characteristics of the harmonic lines such as intensity and polarization. HHG analysis of the emission spectrum performed through a Morlet wavelet, shows that the hig…
Comparison of metals and essential trace elements levels between Autistic Spectrum Disorders cases and their sibs in Sicily (southern Italy)
2016
Introduction: A role of metals exposure and essential trace element deficiency in Autistic Spectrum Disorders (ASD) etiology has been suggested by epidemiologic studies, but conclusive evidence on this topic is still lacking and controversial. We compared metals and essential trace element levels between cases both with their brothers and healthy children. Methods: The diagnosis of ASD were performed by ADOS and ADI-R according to DSM IV (Diagnostic and Statistical Manual of Mental Disorders) criteria. Hair samples were collected from cases and sibs by single cutting from the occipital region. The samples were cut to lengths of about 1.5–2 cm using clean stainless steel scissors. Approximat…
Interventions aimed at reducing obsessive-compulsive symptoms in people with autism spectrum disorder: A review
2021
espanolEl trastorno del espectro autista (TEA) es un trastorno del neurodesarrollo caracterizado por deficits en la comunicacion e interaccion social y por comportamientos restrictivos y repetitivos. Presenta una elevada comorbilidad con otros trastornos, de hasta un 37% con el trastorno obsesivo compulsivo (TOC) en pacientes jovenes. El TOC se caracteriza por pensamientos e ideas recurrentes que llevan a la persona a realizar acciones compulsivas para disminuir el nivel de ansiedad que estos pensamientos le generan. Este trabajo presenta una revision de los metodos psicologicos de intervencion utilizados, asi como de la efectividad de los mismos, en la reduccion de los sintomas del TOC com…
ExTTF-Based Dyes Absorbing over the Whole Visible Spectrum
2011
International audience; New push−pull dyes featuring π-extended tetrathiafulvalene (exTTF) as the donor group and tricyanofuran (TCF) as the acceptor group were synthesized and characterized. Their broad absorption covers the entire visible spectral range and enters the near-infrared region. Electrochemistry and theoretical calculations provided an understanding of these singular electronic properties. The new dyes are appealing candidates as light harvesters in photovoltaic devices.
Studies on some antimony(III) complexes with tridentate schiff base ligands
1981
Abstract The antimony(III) complexes FSb(Sab), ClSb(Sab) and ClSb(Sat) containing dianonic, potentially tridentate Schiff-base ligands with ONO(Sab 2− ) and ONS(Sat 2− ) donor atoms have been prepared and characterized. The mass spectra of these derivatives are reported. The occurrence of chelation by the tridentate ligand is inferred from the infrared data. The antimony-121 Mossbauer parameters at 4.2 K are reported. The magnitudes and the positive sign of eQV zz suggest a consistent p-character of the antimony lone-pair orbital. Observed differencies in the isomer shift and eQV zz values are discussed on the basis of the likely distribution of electron density around antimony.
Chromatographic and mass spectrometric characteristics of 20-dihydroaldosterone.
1992
The 20 alpha-reduced derivative of aldosterone, 20 alpha-dihydroaldosterone, was needed as reference compound in order to continue the studies on 18-hydroxylation in the Y-1 adrenal cell line. It was obtained by reduction of aldosterone with sodium borohydride. Analysis of the products of the reaction as methoxime trimethylsilyl (MO-TMS) derivatives by gas chromatography (GC) and GC-mass spectrometry (GC-MS) showed three possible forms of the compound. Their identification was confirmed by comparison with the products obtained by stereospecific reduction of aldosterone using 3 alpha,20 beta-hydroxysteroid dehydrogenase. Chromatographic behavior and mass spectra are given for the three forms…
Stable Green Electroluminescence from an Iridium Tris-Heteroleptic Ionic Complex
2012
An ionic tris-heteroleptic iridium complex gives green light-emitting electrochemical cells (LECs) with unprecedented performances for this part of the visible spectrum. The devices are very bright (>1000 cd m–2), efficient (∼3%), and stable (>55 h). The novel complex is prepared using a new and efficient synthetic procedure. We show that there is a mixed orbital formation originating from the two different orthometalating ligands resulting in photophysical properties that lie between those of its two bis-heteroleptic analogs. Therefore, tris-heteroleptic complexes provide new avenues for fine-tunning the emission properties and to bridge gaps between a series of bis-heteroleptic complexes.
Switch between tyrosinase and catecholoxidase activity of scorpion hemocyanin by allosteric effectors
2008
AbstractPhenoloxidases and hemocyanins have similar type 3 copper centers although they perform different functions. Hemocyanins are oxygen carriers, while phenoloxidases (tyrosinase/catecholoxidase) catalyze the initial step in melanin synthesis. Tyrosinases catalyze two subsequent reactions, whereas catecholoxidases catalyze only the second one. Recent results indicate that hemocyanins can also function as phenoloxidases and here we show for the first time that hemocyanin can be converted to phenoloxidase. Furthermore, its substrate specificity can be switched between catecholoxidase and tyrosinase activity depending on effectors such as hydroxymethyl-aminomethan (Tris) and Mg2+-ions. Thi…