Search results for " infrared spectroscopy"
showing 10 items of 438 documents
Intercomparison of volcanic gas monitoring methodologies performed on Vulcano Island, Italy
2004
[1] Volcanic gas emissions from fumaroles on the rim of La Fossa crater, Vulcano Island, Italy, were measured simultaneously using direct sampling (for H2O, CO2, total sulfur, HCl and HF), filter packs (for SO2, HCl, HF) and short-path active-mode FTIR measurements (for H2O, CO2, SO2, HCl and HF) in an intercomparison study in May 2002. The results show that Cl/F ratios were in good agreement between all three methods, and that FTIR and direct sampling determined comparable proportions of CO2 and H2O. Amounts of total S observed in direct sampling data were approximately double the amounts of SO2 measured with filter packs and FTIR. This difference could be attributed either to the fact FTI…
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.
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…
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…
Sequential dissociation of insulin amyloids probed by high pressure Fourier transform infrared spectroscopy
2012
High Pressure (HP) Fourier Transform Infrared Spectroscopy (FTIR) has been here employed to investigate the thermodynamic stability of bovine pancreatic insulin (BPI) amyloids. Once the aggregation reaction has started, the backbone arrangement of the proteins forming the amyloid is known to reach a stationary phase in few hours; after this time the infrared absorption of fibrils becomes stable. It is here shown how the further stabilization of the structure during the stationary phase can be probed via FTIR spectroscopy, through the observation of the high pressure behaviour of fibrils formed at different maturation stages. We report on the high pressure fragmentation of insulin amyloids, …
FTIR analysis of the high pressure response of native insulin assemblies
2013
It is widely recognized that a central role in conferring stability to the structure of proteins against misfolding and aggregation is played by the formation of oligomers. The case of insulin is prototypical in this respect: in our body it is stored up in stable inactive hexameric assemblies whereas only in its monomeric form it recovers the role of regulating carbohydrate and fat metabolism. In the present paper, exploiting the optimal coupling between FTIR spectroscopy and diamond anvil cell technique, we probe the stability of different insulin oligomeric forms under high pressure, namely over the ranges 0-15 kbar for water solution and 0-80 kbar for dry powder. Results obtained show di…
Structural characterization and optical constants of p-toluene sulfonic acid doped polyaniline and its composites of chitosan and reduced graphene-ox…
2020
Para-Toluene sulfonic acid doped polyaniline (PANI), PANI/chitosan composites, PANI/reduced graphene-oxide composites and a ternary composite comprising of PANI, chitosan and reduced graphene-oxide have synthesised via oxidative polymerisation of aniline by Ammonium peroxydisulfate (APS). FTIR, XRD, FESEM and UV-VIS techniques were performed for the confirmation of the successful synthesis. The fundamental optical parameters such as, complex refractive index, complex dielectric constants and optical conductivity of the PANI and the composites were investigated in the UV-VIS-NIR range. The results show a clear dependence on the constituent component such as sulphur as well as the absorbance …
Challenges in the use of Near Infrared Spectroscopy for improving wood quality: A review
2018
Aims of study: Forestry-related companies require quality monitoring methods capable to pass a large number of samples. This review paper is dealing with the utilization of near infrared (NIR) technique for wood analysis.Area of study: We have a global point of view for NIR applications and characterization of different kind of wood species is considered.Material and methods: NIR spectroscopy is a fast, non-destructive technique, applicable to any biological material, demanding little or no sample preparation. NIR spectroscopy and multivariate analysis serve well in laboratories where the conditions are controlled. The main challenges to NIR spectroscopy technique in field conditions are mo…
Towards a Rapid Screening of Liver Grafts at the Operating Room Using Mid-Infrared Spectroscopy
2020
The estimation of steatosis in a liver graft is mandatory prior to liver transplantation, as the risk of graft failure increases with the level of infiltrated fat. However, the assessment of liver steatosis before transplantation is typically based on a qualitative or semiquantitative characterization by visual inspection and palpation and histological analysis. Thus, there is an unmet need for transplantation surgeons to have access to a diagnostic tool enabling an in situ fast classification of grafts prior to extraction. In this study, we have assessed an attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopic method compatible with the requirements of an operatio…