Search results for "spectrum"
showing 10 items of 2043 documents
Speciation and Mobility of Arsenic in Agricultural Lime
2009
Agricultural liming materials are used to correct soil acidity and to improve plant growth and microbial functionality. A relatively low-grade agricultural lime was found to contain up to 125 mg kg(-1) arsenic (As), which is above any fertilizing materials code threshold. The color of the milled material is brown due to ample oxide dendrites. Microprobe elemental maps confirmed that these accessory oxide mineral phases are responsible for the elevated As concentrations in the limestone. The black Mn-bearing dendrites contain minor amounts of As, whereas the brown Fe-bearing dendrites contain the major part of the As inventory, with an Fe/As molar ratio around 100. Because the elemental maps…
Visible-light photoelectrodegradation of diuron on WO3 nanostructures
2018
[EN] The degradation of pesticide diuron has been explored by photoelectrocatalysis (PEC) under visible light illumination using two different WO3 nanostructures, obtained by anodization of tungsten. The highest degradation efficiency (73%) was obtained for WO3 nanosheets synthesized in the presence of small amounts of hydrogen peroxide (0.05 M). For that nanostructure, the kinetic coefficient for diuron degradation was 133% higher than that for the other nanostructure (anodized in the presence of fluoride anions). These results have been explained by taking into account the different architecture and dimensions of the two WO3 nanostructures under study.
Chlorination of p-cymene by chlorine in carbon tetrachloride: Model compounds for environmental analyses
1989
p-Cymene was chlorinated by chlorine in CCl4. The products of the chlorination were separated by distillation and purified by preparative gas chromatography. The structures of chlorocompounds were confirmed by means of their NMR and mass spectra. The distillation gave as the main compounds: (2) 2-chloro-, (4) 2,3-dichloro-, (5) 2,5-dichloro-, (6) 2,3,6-trichloro-, (7) 2,3,5,6-tetrachloro-p-cymenes and as by-products: (8) 2,5,7-trichloro-p-cymene, (9) 2,6-dichloro-1-methyl-4-(1-methylethenyl)benzene (cymenene), and (10) 2,3,6-trichloro-1-methyl-4-(1-methylethenyl)benzene (cymenene).
Losing DNA methylation at repetitive elements and breaking bad
2021
Abstract Background DNA methylation is an epigenetic chromatin mark that allows heterochromatin formation and gene silencing. It has a fundamental role in preserving genome stability (including chromosome stability) by controlling both gene expression and chromatin structure. Therefore, the onset of an incorrect pattern of DNA methylation is potentially dangerous for the cells. This is particularly important with respect to repetitive elements, which constitute the third of the human genome. Main body Repetitive sequences are involved in several cell processes, however, due to their intrinsic nature, they can be a source of genome instability. Thus, most repetitive elements are usually meth…
Properties and amino acid composition of pure epoxide hydratase
1975
1. Introduction Rat liver epoxide hydratase [EC 4.2.1.631 which catalyses the conversion of epoxides to trurans-dihydro- diols has been purified to apparent homogeneity as determined by three independent criteria [l] . The preparation obtained was capable of catalysing the hydration of both styrene oxide and the 4,5- (K- region)epoxide of benzo(a)pyrene [ 11. Epoxides of polycyclic hydrocarbons have been implicated as the agents responsible for the cytotoxic and carcinogenic properties of such compounds (for reviews see [2-41). A detailed knowledge of the properties of epoxide hydratase may, therefore, contribute towards an understanding of the mechanisms of cytotoxicity and carcinogenesis.…
Red Blood Cells Polarize Green Laser Light Revealing Hemoglobin's Enhanced Non-Fundamental Raman Modes
2014
In general, the first overtone modes produce weak bands that appear at approximately twice the wavenumber value of the fundamental transitions in vibrational spectra. Here, we report the existence of a series of enhanced non-fundamental bands in resonance Raman (RR) spectra recorded for hemoglobin (Hb) inside the highly concentrated heme environment of the red blood cell (RBC) by exciting with a 514.5 nm laser line. Such bands are most intense when detecting parallel-polarized light. The enhancement is explained through excitonic theory invoking a type C scattering mechanism and bands have been assigned to overtone and combination bands based on symmetry arguments and polarization measureme…
Opals infiltrated with a stimuli-responsive hydrogel for ethanol vapor sensing
2013
We report on a novel class of optical materials for ethanol vapor sensing, based on polystyrene opals infiltrated with an innovative stimuli responsive hydrogel. We describe the fabrication process of the bare polystyrene opals and their subsequent infiltration. The optical characterization of the photonic crystal templates was performed to prove the good quality of the samples. Measurements on the infiltrated opals showed that the transmission spectra in the visible range strongly change at varying concentrations of ethanol vapor. The fabricated structures show a linear optical response in the visible range, for high values of ethanol concentration.
Effectiveness of Virtual Reality for Children and Adolescents with Autism Spectrum Disorder: An Evidence-Based Systematic Review
2018
Autism Spectrum Disorder (ASD) is a neurodevelopmental disease that is specially characterized by impairments in social communication and social skills. ASD has a high prevalence in children, affecting 1 in 160 subjects. Virtual reality (VR) has emerged as an effective tool for intervention in the health field. Different recent papers have reviewed the VR-based treatments in ASD, but they have an important limitation because they only use clinical databases and do not include important technical indexes such as the Web of Science index or the Scimago Journal & Country Rank. To our knowledge, this is the first contribution that has carried out an evidence-based systematic review includin…
Colloidal Nanoplatelet/Conducting Polymer Hybrids: Excitonic And Material Properties
2016
WOS:000370678700053 Here we present the first account of conductive polymer/colloidal nanoplatelet hybrids. For this, we developed DEH-PPV-based polymers with two different anchor groups (sulfide and amine) acting as surfactants for CdSe nanoplatelets, which are atomically flat semiconductor nanocrystals. Hybridization of the polymers with the nanoplatelets in the solution phase was observed to cause strong photoluminescence quenching in both materials. Through steady-state photoluminescence and excitation spectrum measurements, photoluminescence quenching was shown to result from dominant exciton dissociation through charge transfer at the polymer/nanoplatelet interfaces that possess a sta…
Exopeptidase digestion in combination with field desorption mass spectrometry for amino acid sequence determination
1982
Numerous studies have been devoted in the last years to the development of mass spectrometric methods for the sequence determination of peptides [ 1,2]. Most advanced among this work has been so far the rigorous chemical derivatization of oligopeptides to achieve sufficient volatility for the application of conventional (electron impact, EI) mass spectrometry [2-41. For example, the analysis by gas chromatography-mass spectrometry (GC-MS) of mixtures of oligopeptide fragments derivatized after chemical or enzymatic hydrolysis of polypeptides has been successfully used for sequence determinations [2,5]. Major limitations of this approach are that only small peptide derivatives are amenable t…