Simulated Body Fluid (SBF) has concentrations of inorganic elements nearly equal to those of human blood plasma (BP). However, there are some differences between SBF and BP which can distort the ...results of in vitro bioactivity tests. Contrary to BP, SBF has a too low concentration of (HCO3)- ions (only 4 instead of 27 mmol·dm−3) and on the contrary a higher concentration of Cl− ions (introduced by the TRIS-HCl buffer). Indeed, the main difference between SBF and BP is the presence of the TRIS buffer in SBF which is used for neutral pH maintaining. The aim of this work was to study the effect of (HCO3)- ions in non-buffered SBF on the solubility of a bioactive glass-ceramic material and the formation of a new phase on the sample surface. A highly reactive glass-ceramic scaffold derived from 45S5 bioactive glass was tested under static-dynamic conditions using SBF solution with different (HCO3)- ion concentrations (4, 20 and 27 mmol·dm−3). The results were compared with data obtained using standardized buffered SBF solution. A non-buffered SBF solution with a concentration of (HCO3)- ions closer to the real concentration in BP was shown to have the potential to replace the standardized SBF solution since the ISO 23317:2014 using SBF can give false-positive results of in vitro bioactivity tests.
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•There are differences between SBF and BP which distorts results of in vitro tests.•Main differences are presence of the TRIS buffer and low concentration of (HCO3)−.•TRIS supports dissolution of bioactive glass scaffold and precipitation of HAp.•In non-buffered SBF solutions ACP is formed.•Increasing concentration of (HCO3)- effects the amount of newly created ACP layer.
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► Ag acetylacetonate increases thermal stability by mixing with of Pt acetylacetonate. ► Heated mixture of chelates yields a residue with Ag, Pt, O and C elements. ► Co-decomposition ...of metal chelates could yield novel metal structures and alloys.
Thermal gravimetric analysis of equimolar silver(I) acetylacetonate–platinum(II) acetylacetonate mixture shows a significant increase in thermal stability of silver(I) acetylacetonate in the presence of the Pt counterpart. The heated mixture was examined by differential scanning calorimetry and complementary analyses of gaseous products, residues and sublimed fractions by Fourier transform infrared, Raman and X-ray-photoelectron spectroscopy, X-ray diffraction and scanning and high-resolution transmission electron microscopy. It is assumed that silver(I) acetylacetonate is thermally stabilized due to a week bonding with Pt chelate. An interaction between both chelates gets support from the structure of the residual powder which is composed of Ag, Pt, C and O elements and Pt oxides and contains silver nanoparticles whose decreased unit cell parameter can be due to substitution of silver by platinum.
In vitro tests that verify the ability of a material to form bone-like apatite precipitated (HAp) use a solution that imitates the inorganic part of blood plasma, simulated body fluid (SBF). During ...such tests, it is necessary to maintain a neutral pH, for which purpose the International Standards Organization recommends the TRIS (tris(hydroxymethyl)aminomethane) buffer (ISO 23,317:2014). To do this, TRIS buffer must remain inert, but, as we have previously reported, TRIS interacts with highly bioreactive materials (such as 45S5 Bioglass-derived scaffolds), thereby accelerating scaffold dissolution. In the search for an alternative to TRIS, we have also recently published results for the 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) and 3-(N-morpholino) propanesulfonic acid (MOPS) buffers, which were also unable to maintain a neutral pH in SBF. Thus, we here continue our search for a more suitable Good’s buffer by comparing BES (N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid) and TES (2-(2-hydroxy-1,1-bis(hydroxymethyl) ethyl) amino ethanesulfonic acid) with TRIS. 45S5-derived glass–ceramic scaffolds were tested under static–dynamic conditions for bone-like apatite formation using SBF + BES and SBF + TES solutions. The pH measurements, leachate analysis atomic absorption spectrophotometry (AAS) (Ca2+, SiIV), UltraViolet-Visible (UV-VIS) spectrophotometry (PO4)3−, and scaffold analysis X-Ray powder diffraction analysis (XRD), X-ray fluorescent analysis (XRF), scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS), Brunauer.Emmett.Teller specific surface area analysis (BET) all showed that both BES and TES quickly interacted with the tested material. Moreover, the kinetics of the glass–ceramic dissolution affected the crystallinity and morphology of the precipitated HAp. Based on our previous results and the present data, it appears that Good’s buffers are not suitable for the in vitro testing of bioactivity of highly bioreactive materials.
•Verification of using the BES and TES (amino acid based) buffers in SBF.•Comparison of amino acid buffers (buffer + NaOH) with system TRIS + HCl.•Effect of the used buffer on the formation, morphology and crystallinity of the newly formed Ca–P phase.
While the most famous historical green earth deposits in Italy and Cyprus were exceptionally rich in celadonite, the deposits near Kadaň, Czech Republic, consisted of thin Fe‐rich celadonite ...impregnations accompanied by interstratified celadonite/smectite. In superimposed tuffs, smectites become prevalent and their colour changes from forest to olive green. Powder X‐ray microdiffraction and infrared microspectroscopy permit us to distinguish between green earth minerals in microsamples taken from works of art. The Ti contents and the Fe/Mg ratios help to indicate the presence of Bohemian green earth from Kadaň. We found this material in local 18th‐century works of art and also in paintings by Anton Kern (1709–47).
Pre‐Romanesque murals at Kostoľany pod Tríbečom, Slovakia, have been investigated by portable X‐ray fluorescence and by microanalytical methods to identify painting materials (pigments and binders), ...and to explain the degradation of colours. Today, missing green and blue shades have been reconstructed according to residual concentrations of Cu, which correspond to copper chlorides—products of salt corrosion of the copper carbonates azurite and/or malachite, accelerated by micro‐organisms. As confirmed by powder X‐ray microdiffraction, original minium (Pb3O4) has been transformed to brown–black plattnerite (PbO2). In increased humidity, even insoluble pigments are washing down from the walls and the intensity of colours further diminishes.
Complexes of Co
2+
, Ni
2+
, and Cu
2+
with
N
-(phosphonomethyl)aminosuccinic acid (H
4
PMAS) of general formula Na
2
MPMAS·
n
H
2
O
M
=Co(II), Ni(II), Cu(II),
n
—number of water molecules were ...synthesized. Based on interpretation of diffusion reflectance spectroscopy, structure of all complexes is based on distorted octahedral. Analysis of IR spectra of Co(II), Ni(II), and Cu(II)
N
-(phosphonomethyl)aminosuccinates demonstrated that metal ions are coordinated to the ligand through nitrogen atom of the imino group, oxygen atoms of the α- and β-carboxyl groups as well as oxygen atom of the phosphonic group of the H
4
PMAS. We demonstrated that thermal stability of complexes increases in sequence Cu(II) < Ni(II) < Co(II), obviously as a result of change over from the dimeric to polymeric character of the initial complex. Complete decomposition of ligand occurs at these temperatures and is accompanied by release of H
2
O, CO
2
, and NO
2
. The final products of thermal decomposition of the complexes are mixtures of oxides and phosphates of respective metals.
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► Ultraviolet laser photolysis of thiirane for deposition of sulfur/polythiene composite. ► Solid state reaction between copper and photodeposited sulfur at room temperature. ► ...Formation of sub-microscopic filaments containing nanograins of copper sulfides.
Ultraviolet laser photolysis of thiirane (C
4H
2S) allows chemical vapor deposition of sulfur-containing solid which undergoes room-temperature reaction with copper and yields sub-μm-sized amorphous filamentary CuS/Cu
2S/C/H structures incorporating CuS and Cu
2S nanograins. Properties of these structures were examined by Fourier transform infrared, Raman and X-ray photoelectron spectroscopies, X-ray diffraction and by electron microscopy. The results demonstrate the occurrence of reaction between solid sulfidizing reagent and copper at room temperature.
