Search results for "Infrared"
showing 10 items of 2110 documents
Experimental FTIR-MI and Theoretical Studies of Isocyanic Acid Aggregates
2023
Homoaggregates of isocyanic acid (HNCO) were studied using FTIR spectroscopy combined with a low-temperature matrix isolation technique and quantum chemical calculations. Computationally, the structures of the HNCO dimers and trimers were optimized at the MP2, B3LYPD3 and B2PLYPD3 levels of theory employing the 6-311++G(3df,3pd) basis set. Topological analysis of the electron density (AIM) was used to identify the type of non-covalent interactions in the studied aggregates. Five stable minima were located on the potential energy surface for (HNCO)2, and nine were located on the potential energy surface for (HNCO)3. The most stable dimer (D1) involves a weak, almost linear N-H⋯N hydrog…
Co-reductive fabrication of carbon nanodots with high quantum yield for bioimaging of bacteria
2018
A simple and straightforward synthetic approach for carbon nanodots (C-dots) is proposed. The strategy is based on a one-step hydrothermal chemical reduction with thiourea and urea, leading to high quantum yield C-dots. The obtained C-dots are well-dispersed with a uniform size and a graphite-like structure. A synergistic reduction mechanism was investigated using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The findings show that using both thiourea and urea during the one-pot synthesis enhances the luminescence of the generated C-dots. Moreover, the prepared C-dots have a high distribution of functional groups on their surface. In this work, C-dots proved …
Characterization of Rabbit Mesenchymal Cell Attachment on Calcium Phosphate Surface
2014
In the current study, the effect of three different treated surfaces of hydroxyapatite and β-tricalcium phosphate on mesenchymal cell attachment has been investigated. Calcium phosphate powders have been synthesized, uniaxially pressed, polished and sintered. Mesenchymal cells have been seeded onto unpolished, polished and polished-thermally etched ceramic samples. The ceramic samples have been characterized by XRD, FTIR and SEM. Results have shown that the best cell attachment and morphology are on the unpolished surface indicating that relatively rough surface is better for cell application.
An X-ray characterization of the central region of the supernova remnant G332.5-5.6
2015
Aims. We present an X-ray analysis of the central region of supernova remnant (SNR) G332.5-5.6 through an exhaustive analysis of XMM-Netwon observations with complementary infrared observations. We characterize and discuss the origin of the observed X-ray morphology, which presents a peculiar plane edge over the west side of the central region. Methods. The morphology and spectral properties of the X-ray SNR were studied using a single full frame XMM-Netwon observation in the 0.3 to 10.0 keV energy band. Archival infrared WISE observations at 8, 12 and 24 μm were also used to investigate the properties of the source and its surroundings at different wavelengths. Results. The results show th…
A novel and inexpensive method for measuring volcanic plume water fluxes at high temporal resolution
2017
© 2017 by the authors.Water vapour (H2O) is the dominant species in volcanic gas plumes. Therefore,measurements of H2O fluxes could provide valuable constraints on subsurface degassing and magmatic processes. However, due to the large and variable concentration of this species in the background atmosphere, little attention has been devoted to monitoring the emission rates of this species from volcanoes. Instead, the focus has been placed on remote measurements of SO2, which is present in far lower abundances in plumes, and therefore provides poorer single flux proxies for overall degassing conditions. Here, we present a new technique for the measurement of H2O emissions at degassing volcano…
Metal ions modulate thermal aggregation of betalactoglobulin: a join chemical and physical characterization
2014
Abstract Molecular basis of the role played by Cu 2 + and Zn 2 + ions during the thermal aggregation processes of beta-lactoglobulin (BLG) was studied by using a joint application of different techniques. In particular, Raman spectroscopy was very useful in identifying the different effects caused by the two metals at molecular level (i.e. changes in His protonation state, disulfides bridge conformation, and micro-environment of aromatic residues), evidencing the primary importance of the protein charge distribution during the aggregation process. Both metal ions are able to act on this factor and favor the protein aggregation, but Zn 2 + is able to alter the natural conformational state of…
Preparation of 2,3-seco-5α-cholestane-2,3-diol and 4α-methyl-2,3-seco-5α-cholestane-2,3-diol and its reactions with o-nitrophenyl selenocyanate
1984
The reaction of 2,3-seco-5 alpha-cholestane-2,3-diol and 4 alpha-methyl-2,3-seco-5 alpha-cholestane-2,3-diol with o-nitrophenyl selenocyanate was studied. The diols were synthesized from cholesterol.
Optimized bath for electroless deposition of palladium on amorphous alumina membranes
2006
A new bath for the electroless deposition of palladium on anodic alumina (AA) membranes is proposed. It was found that the optimal conditions for the uniform deposition of palladium, with minimal damage to the AA membranes, were under conditions of pH 8.4 and plating times shorter than 30 min. The deposited Pd layer was detected by X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis. The morphology of the AA membrane before and after plating was examined by scanning electron microscopy (SEM). EDX analysis revealed that palladium was deposited only on the surfaces of the membrane and Sn ions, coming from the sensitizing bath, were incorporated into the palladium layer. EDTA in…
One pot light assisted green synthesis, storage and antimicrobial activity of dextran stabilized silver nanoparticles.
2014
Background Green synthesis of nanomaterials finds the edge over chemical methods due to its environmental compatibility. Herein, we report green synthesis of silver nanoparticles (Ag NPs) mediated with dextran. Dextran was used as a stabilizer and capping agent to synthesize Ag NPs using silver nitrate (AgNO3) under diffused sunlight conditions. Results UV–vis spectra of as synthesized Ag nanoparticles showed characteristic surface plasmon band in the range from ~405-452 nm. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies showed spherical Ag NPs in the size regime of ~50-70 nm. Face centered cubic lattice of Ag NPs was confirmed by powder X-ray diffraction (PXRD…
Formation and growth of palladium nanoparticles inside porous poly(4-vinyl-pyridine) monitored by operando techniques: The role of different reducing…
2017
In this work we followed the formation of palladium nanoparticles, starting from palladium (II) acetate precursor, inside a poly(4-vinylpyridine-co-divinylbenzene) polymer in presence of different reducing agents. The formation and growth of palladium nanoparticles in presence of H-2 was followed as a function of temperature by simultaneous XANES-SAXS techniques, coupled with DRIFT spectroscopy in operando conditions. It was found that the pyridyl functional groups in the polymer plays a fundamental role in the stabilization of the palladium (II) acetate precursor, as well as in the stabilization of the palladium nanoparticles. The effect of a thermal treatment in alcohol (ethanol and 2-pro…