Magnetic minerals, such as magnetite, can significantly influence 1H Nuclear Magnetic Resonance (NMR) measurements, introducing biases that can affect petrophysical interpretations in reservoir rocks. Understanding these effects is crucial for improving the accuracy of fluid content estimations in subsurface evaluations. In this study, we investigate how nanometric-sized magnetite impacts T2 relaxation times in synthesized carbonate samples with controlled porosity and magnetite concentrations. Twelve carbonate samples were synthesized with varying magnetite content (0.0 %-0.8 % wt.), ensuring a controlled environment for evaluating NMR responses. These samples underwent petrophysical (bulk volume, pore volume, grain density, and NMR), mineralogical (XRD and SEM-EDS), and magnetic (low-field magnetic susceptibility, hysteresis loop, FORC, and IRM measurements) characterization to ensure the integrity of both the synthesis and the magnetite contamination. Our findings indicate that (1) the synthesis successfully produced samples with consistent properties, showing a decrease in pore volume with increasing cementing fluid and a corresponding enhancement of magnetic properties with higher magnetite contamination; (2) 1H NMR-based porosity estimates were significantly affected by magnetite contamination, displaying a noticeable flattening of T2 relaxation curves and a reduction in relaxation times, likely due to enhanced diffusional effects; and (3) increasing magnetite concentrations induced nonlinear distortions in porosity phi NMR, leading to systematic deviations from expected values and, consequently causing porosity underestimation. These results underscore the need to account for magnetic mineral contamination in NMR analyses of carbonate reservoirs and highlight the importance of controlled research into magnetite's impact on petrophysical assessments.

Acid fracturing is a widely used technique to enhance oil recovery in carbonate reservoirs, but its effectiveness depends on several factors, including the presence of iron oxides. Magnetite, commonly found in sedimentary rocks – including carbonates that comprise over 50

Despite its advantages, conventional soil-cement has limitations in terms of mechanical strength and durability, especially in environments with high humidity or high structural demands. The development of high-performance soil-cement (HPSC) presents significantly superior mechanical properties. The decentralized production of these panels has resulted in a cost reduction of more than 40%, making them an affordable alternative for low-income communities. Even so, providing technical support for the popularization of HPSC is crucial for the advancement of civil construction and to enable the expansion of affordable and sustainable housing for vulnerable communities. This study focuses on the development of a high-performance soil-cement panel, including its manufacturing process and the materials used. The panel was produced using Yellow Argisol soil, found locally in abundant quantities, modified with sand. Measurements of flexural strength and water absorption were carried out, together with a comparison of the strength of high-performance concrete (HPC) found in the literature. The developed panels present an average flexural strength of 6.71 MPa. Additionally, water absorption reached 5.99%, indicating the high performance of this material, which is comparable to high-performance concrete but more economical and sustainable. This contribution confirms the viability of transferring HPSC technology and highlights its social impact on civil construction.

Background Magnetic bioactive glass-ceramics are a promising class of biomaterials for magnetic hyperthermia-assisted bone cancer therapy, offering the dual advantages of tumor ablation and bone tissue regeneration. However, achieving a balance between high bioactivity and enhanced saturation magnetization remains a significant challenge. Methods The primary goal was to synthesize and characterize of sub-10 nm magnetic nanoparticles coated with two bioactive glass (BG) compositions with distinct Si/Ca ratios. In vitro mineralization tests in simulated body fluid were performed up to 21 days. Apatite formation was monitored with transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and attenuated total reflectance-Fourier transform infrared spectroscopy. The iron oxides of the magnetic nanoparticles were further characterized by Mössbauer spectroscopy and magnetization measurements. Results The synthetic nano-magnetite was converted to nano-maghemite through encapsulation on preparing the BG. A gradual deposition of apatite layers on the BG shells was observed with increasing soaking time. The mag-8-BG sample exhibited the fastest mineralization kinetics and the highest saturation magnetization. Based on these results, it was selected for further assessment of magnetic hyperthermia performance under a magnetic field, and evaluation of in vitro biological properties. Conclusions The multifunctionality of mag-8-BG was confirmed, demonstrating its potential for combined medical diagnosis, hyperthermia therapy, and bone tissue engineering applications in oncology.

A brief overview of the long-standing and rich academic and scientific career of Professor Jos & eacute; Israel Vargas is presented, along with some of his thoughts and notable achievements since obtaining his university degree in Chemistry from Federal University of Minas Gerais (UFMG) in Belo Horizonte, Brazil. He received his doctorate from the Faculty of Physical Chemistry (1960, Cambridge University, UK), working with radiochemistry and hyperfine interactions. Six years after his return to Brazil, he began working as a leading researcher at the Centre d'Etudes Nucleaires de Grenoble, France, where he stayed until 1972. He then once more returned to Brazil and initiated a time of intense scientific activity at the Department of Chemistry, UFMG, as well as of great involvement in science and technology policy in Brazil. In 1977, he was appointed the first state secretary for Science and Technology in Minas Gerais; from 1994 to 2000, he served as the Brazilian Minister of Science, Technology, and Innovation. The present paper will highlight his key role in fostering the scientific careers of numerous young scientists and also pay him homage to recognize his significant contributions to Brazilian and French science, particularly in chemistry and physics.

Context Acid drainage (AD) production from sulfide rich materials can impact the environment, particularly the surrounding mine areas. A suitable evaluation of AD is warranted to prevent and remediate its impacts. The methods that estimate AD and its kinetics are time consuming. Aims To identify chemical and mineralogical features that influence the AD dynamics, and propose a fast method to estimate the AD generation. Methods Chemical analyses of sulfides rocks and thiomorphic soil samples included pH, contents of major elements and the acid-base accounting (ABA). Mineral identification was performed by X-ray diffractometry (XRD) and scanning electronic microscopy (SEM). The rate of sulfide oxidation in samples was evaluated through simulated weathering (SW) tests performed with different contents of H2O2, with and without CaCO3. Supernatant was drained to determine pH, acidity and S-sulfate. Key results Generation of AD was affected by carbonates and sulfides contents in samples, crystal sizes and types. Coal and thiomorfic soil produces more AD, due to framboidal pyrites and small sized sulfides. Conclusions Sulfides oxidation rate and AD generation increased from the metamorphic and igneous intrusive rocks to sedimentary-volcanic and then the supergenic geomaterials, from bigger to smaller crystal sizes. Carbonates and arsenic inhibit AD kinetics. The ABA failed to predict the AD in geomaterials, especially the ultramafic. The SW dynamic tests were suitable to assess AD kinetics and the stoichiometry of acidity production. Implications Carbonates and sulfides are important features to predict AD in several geological environments. Using H2O2 can abreviate the time consuming tests to assess the AD kinetics.

Either pressing or solvent extraction of Jatropha curcas seed oil results in great amounts of cake as a byproduct. The direct use of these fresh biomasses threats the health of mammals as they contain phorbol esters (PEs), a highly toxic class of substance. Five different treatments were bench-assayed to degrade PEs: (i) ammonium hydroxide, (ii) urea, (iii) heat, (iv) ultraviolet radiation, and (v) gamma radiation. All used methods were evaluated for their efficiency on removing PEs from the biomass resulting from deoiling seeds of J. curcas. The treatments were variably effective in reducing PEs contents to nontoxic levels. Aqueous ammonium hydroxide solution (3

The approach proposed here is focused on the separation of light fractions (corresponding to fatty acids with molecular chains between 8 to 14 carbons) from the fatty acid methyl esters (FAMES) of the biodiesel obtained by the reaction of transesterification of triacylglycerol's in the kernel gueiroba oil (Syagrus oleracea) with methanol. The whole biodiesel was fractionated through atmospheric distillation in a single glass column with thermal insulation. Such a separation produced 59.79% in volume of light biodiesel (LB), which was mixed with the standard mineral Jet-A1 kerosene (cf. ASTM, corresponding to the QAV-1, cf. the Brazilian standard of the ANP) for aviation, in the volumetric ratios LB:Jet-A1 2:98; 5:95; 10:90 and 20:80. The values of density, water content, distillation analysis, flash point, calorific value and freezing point were carefully checked for their compliance with the official recommendations for a jet fuel. It was found that the mixtures richest in the Jet-A1 mineral kerosene, that is, those containing no more than 5% LB by volume, well meet the recommended standards and are technologically viable to replace pure Jet-A1 kerosene for the propulsion of turbine aircraft.

In this work, we studied the influence of clay minerals in the formation of spinels during the calcination of galvanic sludge (GS). We obtained samples of (i) GS from the industrial district of Manaus, (ii) kaolin (Kao) and (iii) red clay (RC) from the Central Amazon. A fourth sample was prepared by mixing Kao, GS and RC in the ratio 1:1:8 (Kao+GS+RC). This mixture was ground for 15 minutes, compressed at 42 MPa into prismatic plates (60x20x7 mm3) and calcined at 950oC (PC950) and 1200oC (PC1200) for three hours. GS, Kao and RC were also calcined at 950 and 1200oC for three hours, obtaining GS950, GS1200, Kao950, Kao1200, RC950, and RC1200. The samples were submitted to XRF, XRD, Mössbauer spectroscopy, TG/DTG/DSC and SEM. The LCA was used to verify the sustainability and value of GS in clays as bricks. The results show the formation of nickel oxide and iron/nickel/chromium spinels in GS1200. The sulfate decomposition was detected in the GS with the formation of a solid solution [Fe3+]{Fe(1-y)3+, Fe(1-x)2+, Ni(x)2+, Cr(y)3+} in which [] = tetrahedral site, {} octahedral site. The LCA shows that the production of PC950 and PC1200 is feasible, reduces the use of clays and provides sustainability to a highly toxic environmental liability.

Brazil, one of the largest ore producers in the world, holds 95% of the world’s quartz reserves. The aim of this research is to enhance mitigation measures in quartz ore exploration common in the Serra do Espinhaço Meridional region through the specific study of a mining venture. The three (3) phases of the study were: (1) characterization of the project under study and evaluation of the impacts generated; (2) evaluation of the economic feasibility of using the waste as a coarse aggregate for concrete production; (3) evaluation of the technical feasibility of reusing this waste through analysis of compressive strength. The results of the study show potential negative impacts on occupational health from the piles of disposed waste, specifically silicosis, caused by silica dust dispersed in the air. In the economic analysis, a decrease of 49.05% was verified in coarse aggregate cost through the use of the residue. The compressive strength of the concrete was 26.80 MPa when quartz residue was used and 29.2 MPa when limestone was used. The quartz residue generated by the venture can be reused as aggregate for the production of concrete, generating improvements in environmental and health aspects.

The correlation between iron distribution in octahedral or tetrahedral sites in synthetic magnetite and zinc spinel ferrites and their catalytic properties were investigated in this work. The zinc-doped nanomagnetites were prepared by co-precipitation method and annealed at 420 °C. X-ray diffraction, UV-Vis, X-ray absorption and 57Fe Mössbauer spectroscopies were used to identify iron sites. The obtained results showed that ZnII replaces the relatively smaller FeIII cation in the tetrahedral sites, increasing the cubic lattice dimension, and this replacement remarkably enhances the catalytic effectiveness of the Zn-spinel ferrite towards the indigo carmine degradation compared to undoped magnetite. The indigo carmine degradation experiments were carried out using photo-Fenton method in which 50 mL of indigo carmine dye aqueous solutions (20 mg L−1, pH 3.0), 20 mg ZnxFe(3-x)O4, and 2.0 mL H2O2 (aqueous solution at 0.028 mol L−1) were placed under UV light at 25 °C. Under these experimental conditions the degradation rate of indigo carmine was superior to 98%.

This study addresses the preparation of hybrid nanoparticles comprised of magnetite (Fe3O4) cores and a surface functionalized with tetramethylammonium hydroxide (TMAOH). The stabilized core nanoparticles were subsequently coated with a polymer matrix consisting of poly(L-co-D,L lactic acid-co-trimethylene carbonate) and poly (ethylene oxide) - poly(propylene oxide) - poly(ethylene oxide) triblock copolymer. The novel core/shell hybrid nanoparticles combine the concepts of electromagnetic heating by the magnetite cores with the drug storage and release ability of the polymeric shell. These multifunctional hybrid nanoparticles are intended for hyperthermia clinical protocols in local drug delivery and medical practices in oncology. The essential physical features of these hybrid composite nanoparticles were assessed using an array of appropriate advanced characterization techniques. The equivalent average diameters of the composite nanoparticles were relatively uniform and their core/shell mass ratio was estimated through thermogravimetric analysis. The weakening of the intermolecular interactions with decreasing thickness of the coating led to a concomitant decrease in the melting temperature of the shell. The polydispersity index data from dynamic light scattering analysis enabled the conclusion that polymeric species contained in 10 mL of the polymeric matrix solution could effectively coat a maximum of core particles contained in 0.5 mL of ferrofluid.

Amostras representativas dos diferentes padroes de queima das cerâmicas do sitio arqueologico Ribeirao Canoas III, localizado em Sao Goncalo do Abaete, Minas Gerais, Brasil, foram investigadas por fluorescencia de raios X por dispersao de energia (EDXRF), analise elementar por CHN, difratometria de raios X pelo metodo do po e espectroscopia Mossbauer do 57Fe nas geometrias de transmissao e de retroespalhamento de raios gama; exames fisicos foram realizados sob estereomicroscopio e microscopio optico. O teor de ferro nesses materiais cerâmicos, determinado por EDXRF, aqui expresso na forma de Fe2O3, e da ordem de 3,7 a 7,9 massa% e o teor de carbono, obtido por analise elementar CHN, e de ~0,7 a ~1,5 massa%. Os dados Mossbauer mostram que algumas especies ferruginosas apresentam ordenamento magnetico na temperatura de 25 K, revelando sextetos com linhas de ressonância muito alargadas, com campos magneticos hiperfinos atribuiveis a hematita, sugerindo tamanho medio de particulas muito pequeno. Ha tambem um sexteto com campo hiperfino proximo de 45 tesla, atribuivel a goethita, e dois dupletos devidos a Fe3+ e Fe2+. Um ensaio com ima de mao praticamente nao atrai particulas das amostras em po, indicando a ausencia de especies magneticas. A pasta cerâmica contem ainda quartzo, muscovita, rutilo, anatasio e feldspato. Dos resultados assim obtidos, e possivel tracar algumas caracteristicas gerais desses materiais, como: (i) os teores de Fe2+ apontam que as pecas foram queimadas em ambiente redutor; (ii) em um intervalo de temperatura nao inferior a 525 °C, pela ausencia de caulinita, e nao superior a 700 °C, pela ocorrencia de muscovita e pelos tracos residuais de carbono; e (iii) em fogueira a ceu aberto. Considerando-se que o campo magnetico hiperfino de ~45 tesla, das amostras RCIII.006 e RCIII.027, seja de goethita magneticamente ordenada na temperatura de 25 K, com tamanho muito pequeno de particulas, que foi termicamente protegida durante a queima, presume-se que a coccao dessas pecas cerâmicas tenha ocorrido em temperatura muito proxima de 525 °C.

The ceramic materials industry has vast potential for use of waste from industrial processes, such as iron mining tailings. The aim of this study was to test technological use of tailings samples from the dam rupture of the Samarco S.A. Company in 2015 to produce structural ceramics. Sedimentation and flotation processes were used to improve their characteristics, analyzing their chemical and mineralogical composition and granulometry. We produced 48 samples with a mixture of soil and residues in proportions of 10, 20, and 30 wt%, with sintering at 950 °C. The results showed that co-processing of iron mining tailings can be considered viable for improving certain aspects of some technological properties. The maximum amount of residue used was 30 wt% for any of the fractions used, as above this concentration the specimens lose important characteristics.

Amostras representativas dos diferentes padrões de queima das cerâmicas do sítio arqueológico Ribeirão Canoas III, localizado em São Gonçalo do Abaeté, Minas Gerais, Brasil, foram investigadas por fluorescência de raios X por dispersão de energia (EDXRF), análise elementar por CHN, difratometria de raios X pelo método do pó e espectroscopia Mössbauer do 57Fe nas geometrias de transmissão e de retroespalhamento de raios gama; exames físicos foram realizados sob estereomicroscópio e microscópio óptico. O teor de ferro nesses materiais cerâmicos, determinado por EDXRF, aqui expresso na forma de Fe2O3, é da ordem de 3,7 a 7,9 massa% e o teor de carbono, obtido por análise elementar CHN, é de ~0,7 a ~1,5 massa%. Os dados Mössbauer mostram que algumas espécies ferruginosas apresentam ordenamento magnético na temperatura de 25 K, revelando sextetos com linhas de ressonância muito alargadas, com campos magnéticos hiperfinos atribuíveis à hematita, sugerindo tamanho médio de partículas muito pequeno. Há também um sexteto com campo hiperfino próximo de 45 tesla, atribuível à goethita, e dois dupletos devidos a Fe3+ e Fe2+. Um ensaio com ímã de mão praticamente não atrai partículas das amostras em pó, indicando a ausência de espécies magnéticas. A pasta cerâmica contém ainda quartzo, muscovita, rutilo, anatásio e feldspato. Dos resultados assim obtidos, é possível traçar algumas características gerais desses materiais, como: (i) os teores de Fe2+ apontam que as peças foram queimadas em ambiente redutor; (ii) em um intervalo de temperatura não inferior a 525 °C, pela ausência de caulinita, e não superior a 700 °C, pela ocorrência de muscovita e pelos traços residuais de carbono; e (iii) em fogueira a céu aberto. Considerando-se que o campo magnético hiperfino de ~45 tesla, das amostras RCIII.006 e RCIII.027, seja de goethita magneticamente ordenada na temperatura de 25 K, com tamanho muito pequeno de partículas, que foi termicamente protegida durante a queima, presume-se que a cocção dessas peças cerâmicas tenha ocorrido em temperatura muito próxima de 525 °C. ENGLISH: Representative samples of different firing patterns of ceramics from the Ribeirão Canoas III archaeological site, located in São Gonçalo do Abaeté, Minas Gerais, Brazil, were investigated by energy dispersive X-ray fluorescence (EDXRF), CHN elemental analysis, powder X-ray diffractometry, and Mössbauer spectroscopy of 57Fe in transmission and gamma-ray backscattering geometries; physical examinations were performed under stereomicroscope and optical microscope. The iron content in these ceramic materials, determined by EDXRF, here expressed as Fe2O3, is of the order of 3.7 to 7.9 mass% and the carbon content, obtained by CHN elemental analysis, is ~0.7 to ~1.5 mass%. Mössbauer data show that some ferruginous species exhibit magnetic ordering at the 25 K temperature, revealing sextets with very wide resonance lines, with hyperfine magnetic fields attributable to hematite, suggesting very small average particle size. There is also a sextet with a hyperfine field near 45 tesla, attributable to goethite, and two doublets due to Fe3+ and Fe2+. A hand magnet test does not attracts almost any particles from the powdered samples, indicating the absence of magnetic species. The ceramic paste also contains quartz, muscovite, rutile, anatase and feldspar. From the results thus obtained, it is possible to trace some general characteristics of these materials, such as: (i) the Fe2+ contents indicate that the pieces were burned in a reducing environment; (ii) in a temperature range not lower than 525 °C, due to the absence of kaolinite, and not higher than 700 °C, due to the occurrence of muscovite and the residual traces of carbon; and (iii) in an open fire. Considering that the hyperfine magnetic field of ~45 tesla, of samples RCIII.006 and RCIII.027, is magnetically ordered goethite at the temperature of 25 K, with very small particle size, which was thermally protected during firing, the burning of these ceramic pieces is assumed to have occurred at a temperature very close to 525 °C.

Representative samples of different firing patterns of ceramics from the Ribeirao Canoas III archaeological site, located in Sao Goncalo do Abaete, Minas Gerais, Brazil, were investigated by energy dispersive X-ray fluorescence (EDXRF), CHN elemental analysis, powder X-ray diffiactometry, and Mossbauer spectroscopy of Fe-57 in transmission and gamma-ray backscattering geometries; physical examinations were performed under stereomicroscope and optical microscope. The iron content in these ceramic materials, determined by EDXRF; here expressed as Fe2O3, is of the order of 3.7 to 7.9 mass% and the carbon content, obtained by CHN elemental analysis, is similar to 0.7 to similar to 1.5 mass%. Mossbauer data show that some ferruginous species exhibit magnetic ordering at the 25 K temperature, revealing sextets with very wide resonance lines, with hyperfine magnetic fields attributable to hematite, suggesting very small average particle size. There is also a sextet with a hyperfine field near 45 tesla, attributable to goethite, and two doublets due to Fe3+ and Fe2+ . A hand magnet test does not attracts almost any particles from the powdered samples, indicating the absence of magnetic species. The ceramic paste also contains quartz, muscovite, rutile, anatase and feldspar. From the results thus obtained, it is possible to trace some general characteristics of these materials, such as: (i) the Fe2+ contents indicate that the pieces were burned in a reducing environment; (ii) in a temperature range not lower than 525 degrees C, due to the absence of kaolinite, and not higher than 700 degrees C, due to the occurrence of muscovite and the residual traces of carbon; and (iii) in an open fire. Considering that the hyperfine magnetic field of similar to 45 tesla, ofsamples RCIII.006 and RCIII.027 is magnetically ordered goethite at the temperature of 25 K with very small particle size, which was thermally protected during firing, the burning of these ceramic pieces is assumed to have occurred at a temperature very close to 525 degrees C.

Hydrogen production from water splitting is a widely used technique and hematite is one of the most used semiconductors in these processes due to its favorable characteristics such as: adequate band gap, visible light absorption, high chemical stability, abundance in nature, among others. Research on hydrogen fuel production from ammonia instead of water is still very limited. Ammonia is a contaminant normally found in wastewater and annualy tons of ammonia or effluents containing this contaminant are thrown into the environment, making it an ideal reagent to produce hydrogen in a clean environmental process. Based on this knowledge, this work proposes the comparison of the photoelectrochemical performance of hematite doped with structural cations (zinc, copper, cobalt, and nickel) in the molecular fragmentation of water and ammonia to produce hydrogen. A structural characterization of the materials used and tests for PEC activity were performed. Pure hematite doped with ammonia as a substrate presented higher electrical current and it was not activated by visible light. When under visible light hematite‐Co presented a discrete increase in the electrical current and, consequently, a small increase in the hydrogen production from water, whereas in the tests with ammonia, the copper‐doped hematite was responsible for a slight increase in the electrical current.

As far as medical applications for clinical diagnosis and therapy in oncology are concerned, the use of stables magnetic nanoparticles relies on the magnetocaloric response of their ferrofluid suspensions to an applied alternating current magnetic field. To assure their effectiveness as an advanced material for such a medical technology, some critical properties, as any tendency of the nanoparticles to self-agglomerate and of the magnetic core component to somehow change their chemical nature, must be rigorously inhibited. A sample of chemically stable nanoparticles of magnetite (Fe-2(3+) Fe2+O42-) was synthesized through the method consisting of burning a synthetic commercial maghemite (gamma Fe23+O32-) with admixed sucrose, to partially reduce Fe3+ -> Fe2+. The residual carbon, formed on burning the sucrose, tends to coat the nanoparticles and acts as a protective layer hindering the freshly synthesized hot magnetite from being promptly re-oxidized, on cooling the sample in the open-air atmosphere. As a drawback, this carbon layer tends to be a thermal insulator and must be removed, in order to make the magnetite nanoparticles able to be used as a magnetocaloric material and dissipate heat. A chemically gentle removal of the residual carbon was assayed by treating the sample with H2O2 under stirring or sonication either for 30 min or 60 min. The intrinsic atomic and crystalline structures and other essential properties of this core-shell system were assessed by gas adsorption analysis (BET), powder X-ray diffraction, Fourier-transform infrared spectrometry, Modssbauer spectroscopy and transmission electron microscopy. Theoretical analyses based on the density functional theory (DFT) were used to interpret the harmonic infrared spectra for the produced magnetite. The efficiency in removing the residual carbon layer formed on the magnetite grain surface was checked by saturation magnetization measurements and CHN elemental analysis. The heat releasing ability of the prepared magnetic sample was evaluated under an AC-induced magnetic field. These results evidenced that the treatment with H2O2 was efficient enough to remove, even though not completely, most of the residual carbon layer, which made the saturation magnetization and the heat released by the treated samples significantly greater than that of the untreated carbon-coated grains. The resulting nano magnetite was found to be a sufficiently clean material for being used for hyperthermia-based procedures, particularly for medical diagnosis and therapy, in oncology.