Mo Mn Research Articles

The concentration of Mn, Cu, Zn, Co, B, Sr, Cd and Pb in alluvial soils of the Ob River (forest-steppe, southern taiga and central taiga)

Three areas of the Ob River floodplain (forest-steppe, southern taiga and central taiga) were investigated. The total amount of Mn, Cu, Zn, Co, B, Sr, Cd and Pb was identified. The same elements were identified in ammonium acetate buffer extract, 1N HCl extraction and Tamm’s and Grimm’s soil extracts. The basic amount of trace elements in the soils is in the potentially unstable form, in Tamm’s and 1N HCl extracts (up to 74% of the total amount). The geochemical spectra of the investigated elements’ concentration in the soils and meadow vegetation are given. The Ob floodplain is not polluted as it has not been affected by industry, and that is why natural mechanisms of these soils can be easily detected. The content reduction regularity of most of the trace elements and their unstable forms in the soils from the south to the north of the Ob floodplain is observed. The same regularity concerns plants in which Co, Mo, B, Sr and Cd contraction and Mn, Zn and Cu increase are detected.

Study on vacuum brazing of high purity alumina for application in proton synchrotron

The paper describes an experimental study to evaluate two different vacuum brazing processes to obtain high purity alumina (99.7%) joints suitable for application in rapid cycle proton synchrotron. Two different brazing routes, adopted for making alumina–alumina brazed joints, included (i) multi-step Mo–Mn metallization, followed by brazing with BVAg-8 alloy and (ii) advanced single-step active brazing with CuSil-ABA® alloy. Both the brazing routes yielded helium leak tight and ultra-high vacuum (pressure<10−9mbar) compatible joints. Active-brazed specimens exhibited tensile and mean flexural strengths of 62 and 110MPa, respectively. Metallized-brazed specimens, although associated with relatively lower tensile strength (35MPa) than the targeted value (>50MPa), displayed higher mean flexural strength of 149MPa. The results of the study demonstrated that active brazing is a simple and cost effective alternative to conventional multi-step metallization route for producing quality joints of high purity alumina for application in rapid cycle proton synchrotron machine.

External validation of models and simple scoring systems to predict miscarriage in intrauterine pregnancies of uncertain viability

Does a logistic regression model and scoring system to predict viability of an intrauterine pregnancy of uncertain viability (PUV) perform as well in an independent patient group as the original patient group? The model and scoring system showed good performance on external validation confirming their value for the prediction of miscarriage/viability in PUV patients up to 11-14 weeks of gestation. Several individual ultrasound and demographic factors have been described as predictors for miscarriage. A logistic regression model and simple scoring system using basic clinical and ultrasound features, such as maternal age, bleeding score, mean gestational sac diameter (MSD) and presence or absence of yolk sac, have been developed to allow patient-specific prediction of viability of PUV beyond the first trimester. Prospective observational external validation cohort study in two inner city early pregnancy assessment units over a period of 18 months. All consecutive women with a PUV were recruited. Ultrasound (mean sac diameter and presence of yolk sac) and demographic variables (maternal age, bleeding score and gestational age) were noted. The outcome measure was first trimester (11-14 week) viability. Women with unknown first trimester outcome were excluded. Receiver operating characteristic (ROC) curves and calibration plots were constructed. Test performance was compared with the original development data set. A new model and scoring system, which did not include gestational age, was built and evaluated. Of the 575 women who were recruited, first trimester outcome was known for 89.2% (n = 513). The model could only be validated in 400 patients, due to missing values in model variables and outcome. The model predicted viability with an area under the ROC curve (AUC) of 0.845 [95% confidence interval (CI), 0.806-0.884] compared with 0.774 (95% CI, 0.701-0.848) in the original study. The AUC for the scoring system was 0.832 (95% CI, 0.792-0.872) compared with 0.771 (95% CI, 0.698-0.844) from the original study data set. The new model and the scoring system, excluding gestational age, could be evaluated on 503 patients and resulted in an AUC of 0.801 (95% CI, 0.765-0.841) for the model and 0.773 (95% CI, 0.733-0.812) for the scoring system. Approximately 22% of patients could not be validated due to missing variables and for 11% of patients the first trimester outcome was unknown. Both the model and the scoring system showed excellent performance on external validation confirming their generalizability and utility in prediction of viability beyond the first trimester in clinical practice. An advantage of the mathematical models original Mo and new Mn and scoring systems original SSo and new SSn is that they can provide women with an individualized probability of the viability of their pregnancy using only demographic information, symptoms and TVS findings. Furthermore, the risk of miscarriage can be given immediately following examination. T.B. is supported by the Imperial Healthcare NHS Trust NIHR Biomedical Research Centre. This research is supported by Research Council KUL GOA MaNet, iMinds 2012, Belgian Federal Science Policy Office IUAP P719. VVB is a postdoctoral fellow of the Research Foundation - Flanders (FWO). There are no conflicts of interest.

Effects of alloying elements on defect structures in the incubation period for void swelling in austenitic stainless steels

Positron lifetime measurements were used to study the effects of alloying elements on the defect structure during the incubation period for void swelling in several fcc model alloys. Pure Ni, four model alloys (Fe–Cr–Ni, Fe–Cr–Ni–Mo–Mn, Fe–Cr–Ni–Mo–Mn–Si and Fe–Cr–Ni–Mo–Mn–Si–Ti), and four commercial alloys (SUS316LSS, SUS316SS, SUS304SS and Ti added modified SUS316SS) were irradiated with electrons and neutrons. Even at 363 and 573K to a dose of 0.2dpa, an effect of alloying elements was observed. At 363K irradiation, voids were formed only in Ni and Fe–Cr–Ni. At 573K irradiation, voids were formed in Ni and all model alloys, though the concentration depended on the alloying elements. In commercial alloys, precipitates were formed instead of vacancy clusters, which prevented void growth.

Relative effects of enthalpy and entropy on the phase stability of equiatomic high-entropy alloys

High configurational entropies have been hypothesized to stabilize solid solutions in equiatomic, multi-element alloys which have attracted much attention recently as “high-entropy” alloys with potentially interesting properties. To evaluate the usefulness of configurational entropy as a predictor of single-phase (solid solution) stability, we prepared five new equiatomic, quinary alloys by replacing individual elements one at a time in a CoCrFeMnNi alloy that was previously shown to be single-phase [1]. An implicit assumption here is that, if any one element is replaced by another, while keeping the total number of elements constant, the configurational entropy of the alloy is unchanged; therefore, the new alloys should also be single-phase. Additionally, the substitute elements that we chose, Ti for Co, Mo or V for Cr, V for Fe, and Cu for Ni, had the same room temperature crystal structure and comparable size/electronegativity as the elements being replaced to maximize solid solubility consistent with the Hume–Rothery rules. For comparison, the base CoCrFeMnNi alloy was also prepared. After three-day anneals at elevated temperatures, multiple phases were observed in all but the base CoCrFeMnNi alloy, suggesting that, by itself, configurational entropy is generally not able to override the competing driving forces that also govern phase stability. Thermodynamic analyses were carried out for each of the constituent binaries in the investigated alloys (Co–Cr, Fe–Ni, Mo–Mn, etc.). Our experimental results combined with the thermodynamic analyses suggest that, in general, enthalpy and non-configurational entropy have greater influences on phase stability in equiatomic, multi-component alloys. Only when the alloy microstructure is a single-phase, approximately ideal solid solution does the contribution of configurational entropy to the total Gibbs free energy become dominant. Thus, high configurational entropy provides a way to rationalize, after the fact, why a solid solution forms (if it forms), but it is not a useful a priori predictor of which of the so-called high-entropy alloys will form thermodynamically stable single-phase solid solutions.

Magnetic properties of R–Fe–B/Mn films with different structures

R–Fe–B/Mn films with different structures have been prepared by DC magnetron sputtering on Si (100) substrates heated at 650 °C. The influence of Mn layer on the magnetic properties of R–Fe–B film is investigated. Addition of Mn layer enhances both the coercivity and the remanence ratio of the R–Fe–B/Mn films. The improvement in the magnetic properties becomes obvious in [Pr–Fe–B(600 nm)Mo(2 nm)Mn(20 nm)] film when a 2 nm Mo as spacer layer is added, the highest coercivity H c of about 18.7 kOe is achieved in the [Pr–Fe–B(600 nm)Cu(2 nm)Mn(20 nm)] film when a 2 nm Cu as spacer layer is added. The coercivity of [Pr–Fe–B( x nm)Cu(2 nm)Mn(20 nm)Cu(2 nm)] n films decreases with increasing the period number of Mn layer for the same thickness of magnetic layer.

Spin crossover in the cyanide-bridged MoVMnIII single-chain magnet containing FeII cations

A 1D Mo(V)Mn(III) chain compound balanced by {Fe[HC(3,5-Me(2)pz)(3)](2)}(2+) dications was prepared. This complex displays a typical single-chain magnet character associated with the Mo(V)Mn(III) chain and a spin crossover phenomenon arising from cationic Fe(II) subunits. The spin crossover behavior tends to slightly affect single-chain magnetic properties at low temperature.

Variations in essential and non-essential element composition and yield of silage corn fertilized with sulfur

The effect of sulfur fertilization on the silage yield and essential and non-essential element composition of silage corn was investigated at the Experimental Field of Research and Experiment Station of the Ankara University during the years 2002 and 2003. The experimental design was a randomized complete block with five replications. Sulfur was applied at 1000 (S1) and 1500 (S2) kg ha−1 as gypsum. Element concentration of the plants was measured by polarized energy dispersive X-ray fluorescence (PEDXRF). Sulfur fertilization increased S concentrations and improved silage corn yield for both years. Applied S reduced P and Mo concentrations, increased Fe and Mn concentrations, and had no significant effect on the K, Ca, Mg, Zn and Cl concentrations of silage corn. Non-essential element composition of silage corn was also influenced by S fertilization. Applied S significantly increased Sr and Pb, reduced Si, Ba and U, while had no effect on Na, Ti, Ni, Br and Rb concentrations of silage corn. In the current work, essential and non-essential element concentrations of silage corn in 2002 and 2003 years under our experimental conditions were as follows; 1.58–1.89 S, 1.07–1.046 P, 14.3–15.9 K, 8.35–9.20 Ca, 3.34–4.28 Mg, 0.26–0.53 Na, 1.36–2.46 Cl, 38.4–42.1 Si as g kg−1, and 2.06–3.13 Mo, 140–144 Fe, 6.08–17.69 Zn, 104–116 Mn, 9.37–12.2 Cu, 23.9–22.6 Ti, 2.10–2.31 Ni, 6.54–6.71 Br, 7.04–8.74 Rb, 94.8–118.8 Sr, 24.0–31.51 Ba, 1.20–2.22 Pb and 3.17–4.07 U as mg kg−1.

Mechanical behavior and microstructural analysis of alumina–titanium brazed interfaces

The ceramic–metal joints for electrical and vacuum engineering devices require high-density alumina ceramic and low glass phase content. Consequently it is necessary to introduce variations in the standard method of metallizing. Our assembly was designed to minimize the difference of thermal expansion between the alumina ceramic and titanium flanges, and was composed by alumina part/Mo–Mn film/Ag–Cu brazing alloy/Ni layer/titanium part. Its transversal section was observed by SEM and analyzed by scanning EDS. The assembly was submitted to the traction test to obtain σ × ɛ curves to study the mechanical behavior. SEM and EDS results indicated that the alumina superficial pores were filled out by molybdenum resulting in a mechanical bonded interface. In the same way, the copper from Ag–Cu brazing alloy filled in the pores of the Mo–Mn layer, modifying the original brazing alloy composition. The fracture occurred in the ceramic part and this was related to the formation of the Al 2[(Mo, Mn)O 4] 3 crystalline phase in the alumina—Mo–Mn interface, which contributes to the increase of the adherence of the metallic layer to the ceramic. The mechanical resistance of the interface between the Ag–Cu brazing alloy and Mo–Mn layer is increased by the diffusion of copper.

Mechanical properties of Fe–Mo–Mn–Si–C sintered steels

Four Fe–Mn–Si master alloy powders with the compositions Fe–35%Mn–14%Si, Fe–35%Mn–20%Si, Fe–45%Mn–20%Si and Fe–60%Mn–14%Si were made by the cast milling method, and used to produce Fe–Mo–Mn–Si–C sintered steels. The effects of master alloy composition and sintering atmosphere on the mechanical properties and dimensional change of the sintered steels were studied. The steels were sintered either at 1250°C for 30 min in hydrogen–30% nitrogen or at 1120°C for 30 min in hydrogen and nitrogen–10% hydrogen with different dewpoints. After transient liquid phase sintering, the ultimate tensile strength, yield strength and hardness increase and elongation decreases with increasing contents of manganese and carbon. The dewpoint of sintering atmospheres had little effect on the properties, probably as the addition of manganese and silicon was in the form of a master alloy. The highest tensile strength and smallest dimensional change were obtained in a steel with a composition of Fe–0.85%Mo–1.40%Mn–0.8%Si–0.7%C.

Nucleation and growth of α phase in hot extruded Ti–46.6Al–2Mo–1.4Mn intermetallic alloy produced by hot extrusion of elemental powders

Abstract The present study is concerned with nucleation and growth of α phase during heat treatment in Ti–Al–Mo–Mn intermetallic alloys processed by hot extrusion of elemental powders. TEM and X-ray diffraction analysis show that the microstructure of the as-hot extruded alloy consists of γ, α 2 and B2 phases. The volume fractions of α 2 and B2 phases are 16 and 20%, respectively, which shows that B2 phases that contain significant amounts of Mo have an orientation relationship with γ plates inside them. Microstructural evolution during heat treatment reveals that the α 2 phase nucleates and grows in lamellar form by edgewise and sidewise mechanism. Edgewise growth of the α 2 phase is more rapid than sidewise growth due to the coherent interface between α 2 and γ phases along the sidewise direction. Sidewise growth of the α 2 phase occurs by a ledge mechanism. It has been shown that α phase nucleates in γ plates located at the lamellar boundaries and grows along a direction that can produce an incoherent interface. γ phase present in the B2 phase affects the growth of the α phase by providing a preferential site for α growth.

Development of alumina ceramics vacuum duct for the 3 GeV-RCS of the J-PARC project

An alumina ceramics vacuum duct has been developed for the 3 GeV-RCS of J-PARC project at JAERI. There are two types of alumina ceramics vacuum ducts needed, one being 1.5 m long with a circular cross-section for use in the quadrupole magnet, the other being 3.5 m long with a 15°, bend with a race-track cross-section for use in the dipole magnet. These ducts could be manufactured by joining several duct segments of 0.5–0.8 m in length by brazing. The alumina ceramic ducts have copper stripes on the outside surface to reduce the duct impedance. One of the ends of each stripe is connected to a titanium flange by way of a capacitor so to interrupt an eddy current circuit. The copper stripes are produced by an electroforming method in which a stripe pattern formed by Mo–Mn metallization is first sintered on the exterior surface and then overlaid by PR-electroformed copper (periodic current reversal electroforming method). In order to reduce emission of secondary electrons when protons or electrons strike the surface, TiN film is coated on the inside surface of the ducts.

The Addition of Platinum and Palladium Groups to the Disulfido Ligand in Cyclopentadienyl Molybdenum-Manganese Carbonyl Complexes

The reaction of the complexes CpMoMn(CO)5(μ-S2), 2a, Cp=C5H5 and Cp*MoMn(CO)5(μ-S2), 2b, Cp*=C5Me5with (PPh3)2Pt(PhC2Ph) yielded the new bis-sulfido mixed metal complexes CpMoMn(CO)5Pt(PPh3)2(μ 3-S)2, 3a and Cp*MoMn(CO)5Pt(PPh3)2(μ 3-S)2, 3b by insertion of a platinum metal grouping into the S–S bond. A mono-phosphine complex, Cp*MoMn(CO)6Pt(PPh3)(μ 3-S)2, 4b was also isolated from the reaction of 2b with (PPh3)2Pt(PhC2Ph). Compounds 3b and 4b were both characterized crystallographically. Both complexes consist of open MoMnPt clusters with a Mo–Mn single bond, Mo–Mn=2.7570(16) A for 3b and Mo–Mn=2.7837(13) A for 4b, and two triply bridging sulfido ligands. The trimetallic complexes CpMo(O)MnPd(PBu t 3)(CO)5(μ 3-S), 5a and Cp*Mo(O)MnPd(PBu t 3)(CO)5(μ 3-S), 5b containing an oxo ligand bonded to molybdenum were obtained from the reaction of 2a–b with Pd(PBu t 3)2. The molecular structure of the 5a was also established crystallographically.

Syntheses and reactivity of the diselenido molybdenum-manganese complex CpMoMn(CO)5(mu-Se2).

Reaction of CpMoMn(CO)(8) with elemental selenium and Me(3)NO in the absence of light yielded the diselenido complex CpMoMn(CO)(5)(mu-Se(2)), 2. Compound 2 contains a bridging diselenido ligand lying perpendicular to the Mo-Mn bond, Mo-Mn = 2.8421(10) A. In the presence of room light, the reaction yielded the tetranuclear metal complex Cp(2)Mo(2)Mn(2)(CO)(7)(mu(3)-Se)(4), 3 (36% yield), and 2 (7% yield). Compound 2 reacted with ethylene to yield the ethanediselenato complex CpMoMn(CO)(5)(mu-SeCH(2)CH(2)Se), 4, by insertion of ethylene into the Se-Se bond. Compound 2 also reacted with (PPh(3))(2)Pt(PhC(2)Ph) and CpCo(CO)(2) to yield the complexes CpMoMnPt(PPh(3))(2)(CO)(5)(mu(3)-Se)(2), 5, and Cp(2)CoMoMn(CO)(5)(mu(3)-Se)(2), 6, respectively, by insertion of the metal groupings CpCo and Pt(PPh(3))(2) into the Se-Se bond of 2. The oxo compound Cp(2)CoMo(O)Mn(CO)(5)(mu(3)-Se)(2), 7, was obtained from 6 by decarbonylation at molybdenum by using Me(3)NO. The molecular structures of the complexes 2-7 were established by single-crystal X-ray diffraction analyses.

Fracture behavior and reliability of brazed alumina joints via Mo–Mn process and active metal brazing

Alumina/alumina and alumina/kovar/alumina joints were produced via two joining techniques: (i) a moly-manganese process and (ii) active metal brazing. These joints were heat treated at 400 °C for 100 h to evaluate their fracture strength, fracture behavior, and high-temperature reliability. Depending on the joining methods employed, the optimum microstructure of ceramics for joining is different. It was found in most cases, that the active metal brazing resulted in superior joint strength and reliability over the moly-manganese process. The fracture strength and reliability of alumina/kovar/alumina joints were lower than those of alumina/alumina joints and showed different fracture behaviors. After heat treatment, fracture strength and reliability decreased due to the formation of brittle phases at the joint interface. The fraction of brittle debonding at the interface increased with heat treatment, while that of fracture within the alumina decreased.

The austempering kinetics and mechanical properties of an austempered Cu–Ni–Mo–Mn alloyed ductile iron

Measurements of austempering kinetics and mechanical properties are presented as a function of austempering time over the range 1–4320 min for different combinations of austempering temperature (275, 315, 370 and 400 °C) and austenitizing temperature (870, 900 and 950 °C) for a ductile iron of composition 3.5% C, 2.6% Si, 0.48% Cu, 0.96% Ni, 0.27% Mo and 0.25% Mn. The austempering kinetics are used to calculate processing windows for the three austenitizing temperatures. The mechanical properties are analysed to show that the processing windows accurately predict the austempering times over which the mechanical properties satisfy the ASTM standard. The analysis shows the role of austenitizing temperature, austempering temperature and time in optimizing the mechanical properties.

Novel heterobimetallic complexes with S 2CPR 3(κ- S,S′)(κ- S,C,S′) bridges. X-Ray structure of [MnMo(CO) 6(μ-Br)-(μ-S 2CP iPr 3)

Reaction of fac-[Mn(CO) 3(S 2CPR 3)(Br)] with [Mo(CO) 3(NCMe) 3] produces a member of a novel class of heterodinuclear complex [MnMo(CO) 6(μ-Br)(μ-S 2CPR 3)] (R = Cy, iPr), which contains S 2CPR 3 bridging ligands, acting as an (κ- S,S′) chelate towards Mn, and as an (κ- S,C,S′) pseudoallyl group to Mo, without a direct MoMn bond. One carbonyl group in [MnMo(CO) 6(μ-Br)(μ-S 2CPR 3)] can be easily displaced at room temperature by neutral ligands such as PEt 3 and P(OMe) 3, affording pentacarbonyl complexes, [MnMo(CO) 5(L)(μ-Br)(μ-S 2CPR 3].

Metal dimer chemistry: Me 3NO induced substitution reactions of (η 5-C 5H 5)MoMn(CO) 8. X-ray structure determination of (η 5-C 5H 5)MoMn(CO) 7[P(OMe) 3

Reaction of (η 5-C 5H 5)MoMn(CO) 8 ( 1) with P(OMe) 3 and t-BuNC in the presence of Me 3NO results in facile MoMn bond cleavage products as well as the synthesis of (η 5-C 5H 5)Mo(CO) 3Mn(CO) 4[P(OMe 3)] ( 3) in which the P(OMe) 3 occupies a site trans to the MoMn bond. The crystal structure of 3 is reported (space group P2 1/ c, a=13.064(4), b=7.1325(8), c=22.227(5) Å β=104.91(1)°. Final R and R w, values were 0.058 and 0.048 ( w= Kσ 2( F)). The non-bridged MoMn bond length is the largest reported to date (3.112(1) Å) and the equatorial MnCO bond lengths are longer than those in the patent unsubstituted dimer ( 1).

Effect of Ni coating on MoMn layer in the production of metal-ceramic seals

Effect of Ni coating on MoMn layer in the production of metal-ceramic seals

Allyl and μ-allyl complexes from reactions of a hydrido-bridged molybdenum-manganese complex with dienes: Crystal structures of (η-C 5H 5)(CO) 2Mo(μ-PPh 2)Mn(η 3-C 3H 5)(CO) 3 and (η-C 5H 5)(CO)Mo(μ-σ:η 4-C 5H 9)(μ-PPh 2)Mn(CO) 3

The complex (η-C 5H 5)(CO) 2Mo(μ-H)(μ-PPh 2)Mn(CO) 4 reacts under photolysis with the dienes allene, 1,1-dimethylallene, 1,3-butadiene and 2-methyl- 1,3-butadiene to give heterodimetallic allyl complexes in which the allyl ligand is bonded to either the Mn atom, the Mo atom or, alternatively, to both metal atoms. The crystal structure of two of these complexes, (η-C 5H 5)(CO) 2Mo(μ-PPh 2)Mn(η 3-C 3H 5)(CO) 3 and (η-C 5H 5)(CO)Mo(μ-σ: η 4-C 5H 9)(μ-PPh 2)Mn(CO) 3, have been determined by X-ray diffraction. In the former the allyl ligand is η 3bonded to the manganese atom, which is also coordinated by three CO groups, the bridging PPh 2 group and the Mo atom [MoMn = 3.038(1) Å]. In the latter complex the syn-CH 3CHC(CH 3)CH 2 allyl ligand is η 3bonded to the Mo atom and also via coordination of one CH bond of the CH 2 group to the Mn atom. The Mo atom is additionally coordinated by an η-C 5H 5 ligand, a CO group, the PPh 2 group and the Mn atom [MoMn = 2.800(1) Å]. In the presence of CO, the μ-allyl complexes are in equilibrium in solution with complexes of proposed formula (η-C 5H 5)(CO)(η 3-allyl)Mo(μ-PPh 2)Mn(CO) 4, containing the allyl ligand bonded exclusively to the Mo atom, but these latter complexes lose CO and revert to the μ-allyl complexes readily on attempted isolation. The μ-allyl complex (η-C 5H 5)(CO)Mo(μ-σ: η 4-C 4H 7)Mn(CO) 3 gives a 1:1 adduct with P(OMe) 3 in which the coordination of the allyl CH bond to the Mn atom is replaced by bonding of the P(OMe) 3 group. The μ-allyl complexes can be deprotonated with LIBu n giving anionic species which are postulated to contain μ-allylidene ligands. One such species, [(η-C 5H 5)(CO)Mo(μ-σ:η 3-CH 3CHCHCH)(η-PPh 2)Mn(CO) 3] −, has been reacted with CD 3COOD to regenerate the corresponding allyl complex; the added deuterium atom is located exclusively at the site involved in the interaction with the Mn atom.