The nanocrystalline cobalt ferrites (CoFe2O4) were obtained through self-combustion and wet ferritization methods using aqueous extracts of sesame (Sesamum indicum L) seeds. The multimetallic complex ...compounds were characterized by Fourier transform infrared spectroscopy (FTIR), UV-VIS spectroscopy and thermal analysis. Phase identification, morphological evolution and magnetic properties of the obtained cobalt ferrites were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), FTIR and magnetic measurements. FE-SEM investigations revealed the particle size of CoFe2O4 obtained by wet ferritization method ranged between 3 and 20.45 nm. Their antimicrobial, anti-biofilm and cytotoxic properties were evaluated.
•CoFe2O4 were obtained by two chemical synthesis methods.•Sesame seed extract was used as gelling or chelating agent.•The morphological features of CoFe2O4 nanoparticles were evaluated.•CoFe2O4 exhibited good microbicidal and anti-biofilm features.
Knowledge of the crystallization stability of bioactive glasses (BGs) is a key factor in developing porous scaffolds for hard tissue engineering. Thus, the crystallization behavior of three ...mesoporous bioactive glasses (MBGs) in the 70SiO2-(26-x)CaO-4P2O5-xCeO2 system (x stands for 0, 1 and 5 mol. %, namely MBG(0/1/5)Ce), prepared using the sol–gel method coupled with the evaporation-induced self-assembly method (EISA), was studied. A thermal analysis of the multiple-component crystallization exotherms from the DSC scans was performed using the Kissinger method. The main crystalline phases of Ca5(PO4)2.823(CO3)0.22O, CaSiO3 and CeO2 were confirmed to be generated by the devitrification of the MBG with 5% CeO2, MBG5Ce. Increasing the ceria content triggered a reduction in the first crystallization temperature while ceria segregation took place. The amount of segregated ceria of the annealed MBG5Ce decreased as the annealing temperature increased. The optimum processing temperature range to avoid the crystallization of the MBG(0/1/5)Ce powders was established.
The interest in boron nitride (BN) materials has progressively increased due to their special properties such as high chemical stability and non-toxicity. The synthesis of the BN-based materials, ...starting from boric acid, urea (BN-u) and boric acid and melamine (BN-m) was presented. The obtained materials were characterized by BET, IR Spectroscopy, DR UV-Vis analysis, and Scanning Electron Microscopy (SEM). The synthesized BNs have a high surface area (538.0 m2/g for BN-u and 994 m2/g for BN-m) and large pore volume. However, even the material obtained starting from melamine presents a large pore volume, the pore size is higher from BN obtained from urea making it suitable for dye adsorption from wastewater. For this purpose, its performances in adsorption of Brilliant Blue FCF dye, as a model for dye molecules, were studied. The maximum adsorbed quantity of 24.8 mg/g was calculated based on Sips isotherm. The materials were also tested for CO2 adsorption, with promising results.
A major clinical challenge today is the large number of bone defects caused by diseases or trauma. The development of three-dimensional (3D) scaffolds with adequate properties is crucial for ...successful bone repair. In this study, we prepared biomimetic mesoporous bioactive glass (MBG)-based scaffolds with and without ceria addition (up to 3 mol %) to explore the biological structure and chemical composition of the marine sponge Spongia Agaricina (SA) as a sacrificial template. Micro-CT examination revealed that all scaffolds exhibited a highly porous structure with pore diameters primarily ranging from 143.5 μm to 213.5 μm, facilitating bone ingrowth. Additionally, smaller pores (< 75 μm), which are known to enhance osteogenesis, were observed. The undoped scaffold displayed the highest open porosity value of 90.83%. Cytotoxicity assessments demonstrated that all scaffolds were noncytotoxic and nongenotoxic toward osteoblast cells. Moreover, scaffolds with higher CeO
2
content promoted osteogenic differentiation of dental pulp stem cells, stimulating calcium and osteocalcin secretion. The scaffolds also exhibited antimicrobial and antibiofilm effects against
Staphylococcus aureus (S. aureus)
as well as drug delivery ability. Our research findings indicated that the combination of MBG, natural biological structure, and the addition of Ce exhibited a synergistic effect on the structure and biological properties of scaffolds for applications in bone tissue engineering.
Graphical Abstract
Several compositions in the vitreous SiO2–PbO–Na2O system, with 12.8–25mol% PbO and 21–34.6mol% Na2O were prepared by a conventional melt-quenched method. The structure of the obtained glasses was ...investigated by Infrared (IR), Raman and X-ray photoelectron spectroscopy (XPS) that have underlined the vitreous state of the samples and the differences in the structural units depending both on PbO and Na2O content. The structural units present in the glasses were evidenced by bands' deconvolution in the IR and Raman spectra. The structural correlations in this ternary system are a real challenge, as the behavior of the compositions selected in the ternary system is totally different of that of the binary systems PbO–SiO2 and Na2O–SiO2. ICP-AES results on the aqueous solutions obtained from the studied glasses have shown different chemical stability in water related with extracted ions. The results could be correlated to the glasses structure, namely to the role played of PbO in the structure.
► Glasses in the ternary system SiO2–PbO–Na2O were studied. ► Structural units were investigated by Infrared, Raman and XPS spectroscopy. ► The chemical stability was determined by ICP-AES. ► The results were correlated to the role played by PbO in the structure.
In the present contribution, the study of nanostuctured powders of Mn.sup.2+-doped ZnO with different doping concentration (1, 2, 5 at%) was approached. The samples were synthesized by sol-gel ...method, and the influence of the Mn content on the thermal behavior of the resulted gels was established by thermogravimetric and thermodifferential analysis. Based on the results obtained by thermal analysis, the gels were isothermally treated at 500 °C, 1 h. The XRD powder measurements revealed that all samples had hexagonal wurtzite structure and no other secondary phases were observed suggesting that the Mn.sup.2+ ions have substituted Zn sites. Moreover, the incorporation of Mn.sup.2+ into ZnO lattice was also confirmed by Infrared and Raman spectroscopy. Energy-dispersive X-ray analysis indicates the existence of Mn.sup.2+ in all samples, even in that with 1 at% Mn. The morphology of the samples depends on Mn.sup.2+ concentrations. A decrease in the grain size with the increase in Mn.sup.2+ concentration was observed. Mn.sup.2+-doped ZnO nanopowders with desired structure and properties as promising materials in potential piezoelectric applications, were obtained.
ZnO, Li doped, and Li, Ni co-doped ZnO powders to be later used as transparent conductive oxide thin film were prepared by heat treatment of gels obtained from alcoholic Zn(CH
3
COO)
2
·2H
2
O, LiNO
...3
·nH
2
O and NiSO
4
·6H
2
O solutions with (CH
3
CH
2
OH)
3
N as chelating agent. The properties of the powders and their thermal treatment were studied by thermogravimetric and differential thermal analysis (TG/DTA), differential scanning calorimetry, evolved gas analysis coupled with mass spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy coupled with energy-dispersive X-ray. The as-prepared gels consisted of submicron platelet-like particles and contained zinc acetate dihydrate and hydrozincite in different amount and with different preferred orientations. During annealing of the gels, zinc acetate decomposed between 110 and 350 °C with the release of CH
3
COOH, acetone and CO
2
. The N content of the chelating agent was responsible for NH
3
and NO evolution. The thermal behavior of the doped gels was similar, but there were also differences in the mass losses, amount of released gases. Based on TG/DTA data, ZnO powders were obtained from the gels by annealing both at 275 and 500 °C. After heating at 275 °C, the obtained powders consisted of spherical 1–2 micron grains of wurtzite. The inclusion of the dopants was successful according to EDX and cell parameter data. Thermal study of the powder annealed at 275 °C confirmed that they still contain some zinc acetate. In the case of the doped samples, the mass loss was smaller, since the Li and Ni dopants catalyzed the composition of zinc acetate during the previous annealing at 275 °C. After annealing the gels at 500 °C, stable undoped ZnO or doped ZnO particles were obtained.
The cobalt ferrite (CoFe2O4) and silver-cobalt ferrite (Ag-CoFe2O4) nanoparticles were obtained through self-combustion and wet ferritization methods using aqueous extracts of Hibiscus rosa-sinensis ...flower and leaf. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and magnetic measurements were used for the characterization of the obtained oxide powders. The antimicrobial activity of the cobalt ferrite and silver-cobalt ferrite nanoparticles against Gram-positive and Gram-negative bacteria, as well as fungal strains, was investigated by qualitative and quantitative assays. The most active proved to be the Ag-CoFe2O4 nanoparticles, particularly those obtained through self-combustion using hibiscus leaf extract, which exhibited very low minimal inhibitory concentration values (0.031–0.062 mg/mL) against all tested microbial strains, suggesting their potential for the development of novel antimicrobial agents.
This paper investigates in situ remineralization of the acid-etched natural enamel surface, by incubation in a phosphate solution with neutral pH, at 37 C for 4-10 days, without using any enamel ...matrix derivative (EMD). We investigated the morphology, crystallinity, chemical composition and structure of the newly grown layer onto the natural enamel surface stored in contact with artificial saliva (AS) having a composition similar to natural oral environment. The crystalline phases, crystallite size and orientation, as well as the chemical and phase composition of the remineralized dental enamel samples were studied by scanning electron microscopy coupled with energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy and X-ray diffraction. The experimental results showed that the enamel crystals grown on the demineralized enamel surface are mainly Ca-deficient apatite hexagonal structure. Fluoridated hydroxyapatite and sylvite-type KCl crystallites, which amount considerable increased in the case of sample stored in AS for 10 days, were also identified.
Aim
One of the main by-products resulted from the biodiesel industry is represented by waste glycerol which is known as a mixture between glycerol and various salts, soaps, fatty acids and other ...chemical compounds. This composition makes it very difficult to be used in other domains and the large amounts in which it is obtained raise storage and environmental problems. Within this framework, its bioconversion to other products by several microorganisms could be regarded as a most valuable and convenient alternative. In this work, the transformation of waste glycerol to carotenoid compounds, namely phytoene and β-carotene by several wild strains of halophilic microorganisms isolated from a saline lake is presented.
Methods
The structures of the investigated carotenes were analysed by FT-IR and UV–Vis spectrometry while differential scanning microcalorimetry (μDSC) evaluated the thermal behaviour of the methanol solution of the pigments obtained from microbial cultures. The growth of microorganisms was estimated by measuring optical density at 660 nm using a BMG LABTECH FLUOstar Omega microplate reader and carotenes were extracted with methanol.
Results and Conclusions
The data recorded until now revealed that the presence of waste glycerol from several sources in the composition of culture medium resulted in growing of phytoene content. These compounds are known as precursors for obtaining other carotenoid compounds either in natural synthesis or in chemical industry. In case of β-carotene, the preliminary results revealed a slow decrease of its content in the presence of waste glycerol as a major growth substrate. The presence of waste glycerol in culture medium leads to thermograms for pigments’ methanol solutions with larger thermal effects than those obtained in the absence of waste glycerol. The absorption spectra of the pigments isolated form strains LD2 and LN1-10 display a typical shape for carotenoids in the 400–500 nm wavelength range and for phytoene in the 250–300 nm wavelength range. The absorption spectra of the strains LN4-1, LC37 and LN2-5 indicate the presence of phytoene and the absence of carotenoids.
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