Trace Amounts Of Mg Research Articles

Mitigating ZrCr2 formation at the Cr/Zr interface through trace doping of Zn, Mg and Sn into Cr coatings: A combined first-principles computational and experimental investigation

This study investigates the suppression of ZrCr2 formation at the Cr/Zr interface by introducing trace amounts of Mg, Zn, and Sn into Cr coatings. Combining the first-principles calculation and experimental analyses, the inhibitory effects of these dopants on ZrCr2 are examined. First-principles calculations predicted that Zn, Mg, and Sn can elevate the formation energy of ZrCr2, with Mg exhibiting the most significant effect, thereby exerting an inhibitory influence on ZrCr2 formation. Experimental findings demonstrate that Sn notably inhibits ZrCr2 formation, resulting in a reduction of ZrCr2 approximately 10%. However, Zn and Mg do not exhibit a substantial inhibitory effect on ZrCr2 due to their low yield resulting from the low vaporization temperature. These results from computational simulations, alongside experimental validations, underscore promising strategies for mitigating ZrCr2 formation, offering valuable insights for enhancing performance in nuclear fuel cladding applications.

Simultaneous enhancement of strength and ductility in Al-Zn-Cu casting alloy with trace Mg addition designed by first principle calculation

The Al alloy containing 17 wt% Zn exhibits enhanced strength through Zn precipitation after casting without the need for further aging treatment. DFT (Density Functional Theory) calculations revealed that the addition of Cu and Mg elements to Al-Zn alloy has the potential to stabilize the Zn phase in the Al matrix and reduce the interface energy between the Zn precipitate and Al matrix. Based on these findings, 0.5 wt% Cu and 0.1 wt% Mg were added to the Al-17 wt% Zn alloy. The trace element level of 0.1 wt% Mg addition led to a significant increase in both yield and tensile strength, from 132 to 278 and from 248 to 310 MPa, respectively, compared to the Al-17 wt% Zn alloy with 0.5 wt% Cu. Furthermore, their ductility surpassed 11 %. The trace amount of Mg greatly increased yield and tensile strength, while Cu enhanced the ductility in the Al-Zn alloy after casting without any aging treatment.

Collagen membrane functionalized with magnesium oxide via room-temperature atomic layer deposition promotes osteopromotive and antimicrobial properties.

Artificial bone grafting materials such as collagen are gaining interest due to the ease of production and implantation. However, collagen must be supplemented with additional coating materials for improved osteointegration. Here, we report room-temperature atomic layer deposition (ALD) of MgO, a novel method to coat collagen membranes with MgO. Characterization techniques such as X-ray photoelectron spectroscopy, Raman spectroscopy, and electron beam dispersion mapping confirm the chemical nature of the film. Scanning electron and atomic force microscopies show the surface topography and morphology of the collagen fibers were not altered during the ALD of MgO. Slow release of magnesium ions promotes bone growth, and we show the deposited MgO film leaches trace amounts of Mg when incubated in phosphate-buffered saline at 37°C. The coated collagen membrane had a superhydrophilic surface immediately after the deposition of MgO. The film was not toxic to human cells and demonstrated antibacterial properties against bacterial biofilms. Furthermore, in vivo studies performed on calvaria rats showed MgO-coated membranes (200 and 500 ALD) elicit a higher inflammatory response, leading to an increase in angiogenesis and a greater bone formation, mainly for Col-MgO500, compared to uncoated collagen. Based on the characterization of the MgO film and in vitro and in vivo data, the MgO-coated collagen membranes are excellent candidates for guided bone regeneration.

Mg‐Facilitated Growth of Cubic Boron Nitride by Ion Beam‐Assisted Molecular Beam Epitaxy

Trace amounts of Mg deposited on a diamond (100) substrate surface facilitate the growth of cubic boron nitride (c‐BN) by ion beam‐assisted molecular beam epitaxy. Fourier transform infrared spectroscopy indicates that films grown with Mg are cubic, while those without Mg are either hexagonal BN or lacking measurable cubic or hexagonal signatures. Initiating the growth with 0.005 monolayer equivalent of Mg is sufficient to yield epitaxial films with >99% c‐BN. Reflection high energy electron diffraction, electron energy loss spectroscopy, and X‐Ray photoelectron spectroscopy indicate the surface of the film to be sp2‐bonded BN, consistent with the results of other groups. High‐resolution scanning transmission electron microscopy reveals c‐BN with a high density of stacking faults and twinning. A model is proposed by which Mg locally diminishes the energy barrier to dissociation of the as‐deposited sp2‐bonded BN, facilitating the nucleation of c‐BN.

Controlled optimization of Mg and Zn in Al alloys for improved corrosion resistance via uniform corrosion

The inclusion of trace amounts of Mg and Zn to Al alloys caused the development of β and τ phases at the grain boundary, resulting in the change from pitting corrosion to intergranular corrosion and therefore increased corrosion resistance.

Quantifying the effect of diagenetic recrystallization on the Mg isotopic composition of marine carbonates

The Mg and Sr isotopic compositions (δ26Mg and 87Sr/86Sr) of pore fluids and bulk carbonates from Ocean Drilling Project Site 1171 (South Tasman Rise; 2148.2m water depth) are reported, in order to evaluate the potential of diagenesis to alter carbonate-based geochemical proxies in an open marine system. Given the trace amounts of Mg in marine carbonates relative to coexisting pore fluids, diagenesis can alter carbonate δ26Mg, a promising proxy for seawater δ26Mg that may help elucidate long-term changes in the global Mg cycle. Constraints on the effect of diagenetic recrystallization on carbonate δ26Mg are therefore critical for accurate proxy interpretations. This study provides context for assessing the fidelity of geochemical proxy-reconstructions using the primary components (i.e., foraminiferal tests and nannofossils) of bulk carbonate sediments.We find that pore fluid δ26Mg values (on the DSM3 scale) at Site 1171 increase systematically with depth (from −0.72‰ to −0.39‰ in the upper ∼260m), while the δ26Mg of bulk carbonates decrease systematically with depth (from −2.23‰ to −5.00‰ in the upper ∼260m). This variability is ascribed primarily to carbonate recrystallization, with a small proportion of the variability due to down-hole changes in nannofossil and foraminiferal species composition. The inferred effect of diagenesis on bulk carbonate δ26Mg correlates with down-core changes in Mg/Ca, Sr/Ca, Na/Ca, and 87Sr/86Sr. A depositional reactive-transport model is employed to validate the hypothesis that calcite recrystallization in this system can generate sizeable shifts in carbonate δ26Mg. Model fits to the data suggest a fractionation factor and a partition coefficient that are consistent with previous work, assuming calcite recrystallization rates of ⩽7%/Ma constrained by Sr geochemistry. In addition, either partial dissolution or a distinctly different previous diagenetic regime must be invoked in order to explain aspects of the elemental chemistry and 87Sr/86Sr of relatively deep sediments from Holes A and C. This study indicates that the dynamics of a given sedimentary system can significantly alter bulk carbonate geochemistry, and presents a framework for considering the potential impact of such alteration on picked archives such as foraminiferal tests and nannofossils. Ultimately, this study contributes to the development of δ26Mg as a proxy for seawater δ26Mg by quantifying the susceptibility of carbonate δ26Mg to diagenetic alteration, particularly in sediments in open marine systems. This study suggests that because of the sensitivity of carbonate δ26Mg to diagenetic recrystallization, it can, in certain systems, be used to quantify the impact of diagenesis on carbonate-based geochemical proxies.

In Situ Observation of the Evolution of Intragranular Acicular Ferrite at Mg-containing Inclusions in 16Mn Steel

The effects of chemical compositions and austenitizing temperature on the formation of intragranular acicular ferrite (IAF) of 16Mn steel, a grade of low alloying steel with carbon content of 0.13∼0.19% and manganese content of 1.20∼1.60%, were systematically investigated. The in situ observation of the evolution of IAF at Mg-containing inclusions was carried out using a high-temperature laser scanning confocal microscopy (LSCM). The nucleation and growth of ferrites, the formation of IAF induced by inclusions, and the size of austenite grain at 1200 °C was directly observed using the LSCM. The results show that the inclusions can be transformed into MgAl2O4, Mg2SiO4 and MgO after treated by Mg. Trace amount of Mg can induce the IAF nucleation. With the increasing of Mg addition, the percentage of IAF in steel greatly increases, while the optimum content of Mg is around 0.0022 wt%. The appropriate austenitizing temperature is around 1200 °C and the optimal prior austenite grain size is about 130 µm. The temperature range for IAF transformation is around between 571 °C and 627 °C, and the time for which is about 12 s. The disregistries between MgAl2O4, MgO and α-Fe are as small as 0.6% and 4.03%, they are so small that may act as highly effective nuclei of IAF during γ → α transformation.

Schwertmannite to jarosite conversion in the water column of an acidic mine pit lake

AbstractFerric precipitates in the water column at the San Telmo acidic mine pit lake in the Iberian Pyrite Belt, southwest Spain, have been studied by scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, X-ray fluorescence, inductively coupled plasma mass spectrometry and other complementary techniques. These Fe(III) precipitates were recovered from sediment traps which were left at different depths (25, 35, 40 and 100 m) in the lake for several months. Seasonal variations in the water chemistry were recorded to link the mineralogical findings to vertical and temporal changes in aqueous composition. The results indicate that schwertmannite is the first Fe(III) mineral to crystallize after the oxidation of Fe(II), in agreement with previous studies. Schwertmannite is kinetically favoured in comparison to other Fe(III) minerals, and it buffers the pH at 2.6–3.0. It is metastable, and alters to a (H3O+)- and (K+)-bearing jarosite (containing 58 mol.% H3O+ and 42 mol.% K+ on average) at lower pH (e.g. at pH 2.2–2.5 in the summer season), either in the water column (during settling) and/or in the benthic sediments, in a time period of weeks to months. The extent of hydronium substitution at the alkali site in the jarosite reflects the higher activity of free aqueous protons in solution (10–2.2 to 10–3.0) in comparison to the activities of K+ (10–4.5) and Na+ (10–3.2). Microscopic examination of mixed schwertmannite–jarosite precipitates found in the water column suggest that some textural and compositional features of metastable schwertmannite (e.g. the internal 'pincushion' arrangement and incorporation of trace amounts of Mg, Al, As and Pb) are conserved in the jarosite during the early stages of the mineralogical transformation, but many of these relics are lost in the later stages of crystal growth. Despite the hydronium-rich nature of the jarosite solid solution, this material is also an important sink for K+, which decreases in concentration with decreasing pH unlike most of the other major cations in the water column (notably Na+, Mg2+, Ca2+, Al3+, Fe3+, Cu2+, Zn2+). In addition to the release of Fe3+ to the aqueous solution, the conversion of schwertmannite to (H3O+, K+)-bearing jarosite consumes protons and thus may represent an additional pH control at San Telmo and other acidic mine pit lakes of the area.

LA-ICP-MS and EDS characterization of electrode/electrolyte interfaces in IT-SOFC materials

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) in combination with scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) is used for the determination of elemental spatial distribution in ceramic multi-layer systems such as those found in intermediate-temperature solid oxide fuel cells (IT-SOFCs). Because layer sintering occurs at high temperature (usually well over 1000 °C), there may be mutual diffusion of ions from one layer to another, with dramatic consequences on cell performances. In this work, two model materials have been used to test LA-ICP-MS: La0.83Sr0.17Ga0.83Mg0.17O2.83 (LSGM), one of the most promising electrolytes for IT-SOFCs, and La0.8Sr0.2MnO3 (LSM), a highly representative perovskite material, which are amply used to design electrode materials. A two-layer system screen printed onto an LSM pellet (LSM–LSGM–LSM pellet) was successively sintered at a typical processing temperature, i.e. 1300 °C, for a short time (1 h). Elemental spatial distribution was determined by line profile analyses carried out on fracture surfaces; for comparison SEM-EDS line profiles were tested on the same surface. LA-ICP-MS line profile analysis evidenced that, notwithstanding the relatively low sintering temperature and short firing time (1 h per sintering), manganese cation diffusion into LSGM is relatively abundant, in agreement with previous literature reports and present EDS results. While line scan EDS analyses are not as conclusive for Ga and Mg diffusion, LA-ICP-MS shows that both ions diffuse across both interfaces, and Ga diffuses even over very long distances into the LSM pellet; on the contrary, only trace amounts of Mg can be found far from the LSGM/LSM interface.

Al-Mg Deoxidation of High Nitrogen Steels in VIF

Abstract: The present experiment was conducted to a steel, Fe-20%Cr-10%Mn-6%Ni, in a 25kg intermediate frequency vacuum induction furnace at 1873K under protection of 0.08 MPa nitrogen gas. The inclusions in the steel were studied both before and after Al, Mg was added. The results revealed that the inclusions were removed more efficiently after treated by Al, Mg and the cleanness of metal was promoted to a higher level. The Al treated inclusions had more Mn, Cr and Fe at the core and a significant amount of Al around periphery according to line scanning analysis. After Mg was introduced, it concentrated at the surface of inclusions. The remaining Al content was as low as 0.01% which was lower than expected. The reaction between the Al and MgO crucible should be responsible for it and trace amount of Mg was found in the Al treated inclusions.

Effect of SiMg alloy on inclusions and microstructures of 16Mn steel

The effects of cooling methods and Mg content on the inclusions and microstructures of 16Mn steel were observed, and the mechanism of intragranular ferrite nucleation induced by Mg containing inclusions is discussed. The results show that trace amounts of Mg in steel can induce intragranular ferrite nucleation. With increasing Mg content, the percentage of intragranular ferrite increases, while the optimum Mg content is ∼0·0048 wt-%. The appropriate cooling methods are furnace cooling to 1473 plus water cooling and water cooling. The lattice disregistry among MgAl2O4, MgO and ferrite–Fe phase is very small, and there is a Si enriched zone on the inclusions, which both contribute to the nucleation of intragranular ferrite.

Surfactant Enhance DLLME/FO‐LADS: Assay of Malachite Green Level in Aquatic Environment of Trout Fish

AbstractMalachite green (MG), a traditional agent used in aquaculture although is not approved; its low cost and high efficacy make illicit use likely. We developed a small‐scale, simple, and sensitive dispersive liquid–liquid microextraction procedure for the assay of trace amounts of MG in aquatic environment of Trout fish. Fiber optic‐linear array detection spectrophotometry with charge‐coupled device detector benefiting from a microcell was used for this purpose. The method is based on enhancement effect of an anionic surfactant on the extraction of MG in to very fine multidroplets of microextraction solvent which made assisted by disperser solvent. Under the optimum conditions, the enrichment factor 77.5 was obtained from a 5‐mL water sample. The calibration graph was linear up to 5 × 10−7 mol L−1 with detection limit of 1 × 10−8 mol L−1. The relative standard deviation for seven replicate measurements of 4 × 10−7 and 5 × 10−8 mol L−1 of MG were 3.3 and 4.5%, respectively.

Determination of ketotifen by using calcein as chemiluminescence reagent

Chemiluminescence (CL) was observed when potassium hexacyanoferrate(III) reacted with the mixture of calcein and ketotifen. Interestingly, the CL intensity would be enhanced by trace amounts of Mg 2+ and the CL intensity was strongly dependent on ketotifen concentration. Based on this phenomenon, a flow injection CL method was established for the determination of ketotifen. The possible CL mechanism is proposed based on the kinetic characteristic of the CL reaction, CL spectrum, ultraviolet (UV) spectra and fluorescent spectra. The CL intensity was correlated linearly with concentration of ketotifen over the range of 6.0 × 10 −9 to 2.0 × 10 −7 g mL −1 and the detection limit was 3 × 10 −9 g mL −1. The relative standard deviation was 1.8% for 2.0 × 10 −8 g mL −1 ketotifen ( n = 11). This method was applied to the determination of ketotifen in the tablets successfully.

Microstructural Control of Nb-Si Alloy with Invariant Reactions

Various investigations have been attempted to improve the low temperature ductility of Nb-silicides by microstructural control while they show superior high temperature strength. Present authors have focused on the microstructure evolution through the eutectic and eutectoid reactions in Nb-rich portion of Nb-Si binary system, and with small amounts of additives (Zr or Mg) alloys large Nb grains with fine silicide (α-Nb 5 Si 3 ) particles have been obtained, which is attractive for high temperature use. For further understanding of this phenomenon, the present study has two objectives; one is to apply the advanced solidification technique for further microstructure control, and the other is to investigate the effect of co-existence of Zr and trace amount of Mg on the microstructure evolution during the eutectoid reaction in terms of the interfacial energy between phases. EBSD analysis revealed that uni-directionally solidified alloy show the same crystallographic orientation relationship (O.R.) between Nb and α-Nb 5 Si 3 with that in arc-melted alloy having the same composition. On the other hand, Mg-doped alloy containing Zr shows an O.R. which was not observed in previous works. This implies that Mg doping is effective to control the interfacial energy between Nb and α-Nb 5 Si 3 even in Nb-Si-Zr alloys. Two-step heat-treatment is found to be effective to obtain finer microstructure, and a further investigation on the controlling factors of eutectoid decomposition will provide a proper route to well-controlled microstructures.

Nutritional Quality of Sandbox Tree (Hura crepitansLinn.)

Antinutrient, proximate, mineral, fatty acid, vitamin, and amino acid analyses of sandbox tree (Hura crepitans) seeds were carried out. The results of antinutrient analysis showed that H. crepitans seed contains alkaloid (5.0 +/- 0.2 mg/100 g), tannins (5.0 +/- 0.3 mg/100 g), phytate (53.0 +/- 6.0 mg/100 g), cardiac glycoside (1890.0 +/- 1.5 mg/100 g), and saponin (2.2 +/- 0.1 mg/100 g). Its trypsin inhibitor activity was found to be 30.27 +/- 1.86 TIU/mg of protein. The results of proximate analysis showed that H. crepitans seed is very rich in crude protein (25.16 +/- 0.22%), crude oil (51.43 +/- 0.22%), and energy content (2,621.891 +/- 6.357 kJ/100 g). H. crepitans seed also contains 1.85 ppm Na, 3.4 ppm K, 0.088 ppm Ca, and trace amounts of Mg, Fe, and Zn. The results also showed that H. crepitans oil contains 20.12% oleic acid, followed by stearic acid (3.0%), while linoleic acid is present at the lowest level (0.03%) among the other acids. The Hura oil has a high saponification value (127.16 +/- 0.18 mg/g) and low acid value (3.56 +/- 0.16 mg/g). The results also showed that the average molecular weight of glycerides is higher in the oil as reflected by the ester value (123.6 +/- 0.73 mg/g). The iodine value of Hura oil was found to be 65.62 +/- 0.73%. A low peroxide value (6.6 +/- 0.2 mg/g) was observed in Hura oil. The results showed that H. crepitans seed contains 328.1 IU of vitamin A/100 g, 0.398 mg of vitamin E/100 g, and 0.26 mg of vitamin K/100 g. The results also showed that H. crepitans seed is very rich in glutamate (14.41 g/100 g of protein) and deficient in cysteine (0.78 g/100 g of protein). Among the essential amino acids, arginine has the highest value (5.97 g/100 g of protein). This is followed by leucine, at 4.16 g/100 g of protein. Therefore, H. crepitans seed is a nutritionally promising seed.

Ultrastructure and elemental composition of dormant and germinating Diplodia maydis spores.

The ultrastructure of Diplodia maydis spores was studied in thin sections with a transmission electron microscope. Storage vacuoles were evenly distributed in the two cells. Some of the vacuoles that contained a dense osmiophilic sphere(s) were surrounded by a membrane, and had membranous aggregates around their periphery. The sport wall was composed of an electron-dense layer and an electron-translucent layer. An inner cytoplasmic membrane was present. Dormant and germinating spores were studied with scanning electron microscopy and also with a Si (Li) energy-dispersive X-ray analyzer. The dormant spore was ovate and usually two-celled with a central septum. Germination proceeded via a germ tube from the side of one end of the cell. Of several methods for preparation of specimens for X-ray analysis studied, freeze-dried spores mounted on carbon stubs and then further carbon coated gave the best results. X-ray analyses revealed that spore populations contained large amounts of Si, P, Cl, and K, smaller amounts of S and Ca, and trace amounts of Mg and Al. Analyses of single spores revealed high K and Cl and low P and Mg at one end of the cell with concomitant low K and Cl and high P and Mg in the central portion and other end of the cell. In two-celled germinating spores, high K and Cl occurred in the end of the nongerminating spore cell, whereas the germinating cell contained high P and Mg and low K and Cl. X-ray image maps revealed that K and Cl were located together at one end of the spore.

Molecular Properties of Post‐Mortem Muscle.

SUMMARY— Post‐mortem changes in nucleoside triphosphatase activity of bovine myosin B have been studied by using several different modifiers with either 5 mM ATP or 5 mM ITP as substrate at ionic strengths (r/2) of 0.09, 0.19, or 0.52. Enzymic activity was determined by measuring the release of inorganic phosphate. There was very little difference in enzymic activity between myosin B isolated from prerigor, rigor (24 hr post‐mortem) or post‐rigor (312 hr post‐mortem) muscle stored at either 2° or 16°C except that the specific activity of myosin B prepared from muscle stored for 12–24, hr post‐mortem was higher than activity of myosin B prepared immediately after death. This increase cannot be explained in terms of rigor shortening, but suggests that a change in myosin conformation or in the nature of the actin‐myosin interaction occurs in post‐mortem muscle. If an actin‐myosin interaction occurs during rigor mortis and if this association remains unchanged during extraction of myosin B, then the very low Mg++‐modified myosin B enzymic activities obtained at Γ/2 = 0.19 and 0.52 indicate that this interaction is not irreversible. Extraction in the absence of ATP produced a myosin B whose ATPase activity was markedly inhibited by trace amounts of Mg++. This may be due to the absence of a‐actinin in these myosin B preparations. No consistent differences in activation energies were found either at Γ/2 = 0.19 or 0.52 among the NTPase reactions of myosin B samples prepared from muscle after various times of post‐mortem storage.