Increasing Manganese Content Research Articles

Change of Mold Slag Composition during Slab Casting of Steel with High Al Content

Three different mold slags have been sampled in dependence of time during slab casting of TRIP steel, and compositional changes have been analyzed. Mass transfer coefficients governing the decrease of silica and increase of alumina have been determined. Moreover change of manganese content was investigated in dependence of the initial manganese content of the mold powder which was close to zero for one of the powders investigated. The following findings have been revealed: Mass transfer coefficients are rising with increasing elapsed time or decreasing silica content, respectively. An initial increase of manganese content by oxidation from the steel followed by later reduction has been observed for the manganese free mold powder. For interpretation of these findings, further simulation according to an effective equilibrium reaction zone model was performed. It was revealed that the primary impact of the steel flow at the steel/slag interface close to the mold wall followed by a stratified flow is of major importance for the phenomena observed. Further results make it possible to predict the steady state composition and show that steady state silica content is nonzero in any case. Moreover, for the mold powders investigated here, it was concluded that manganese content does not decrease silica reduction.

Effect of Manganese Nutrition on Content of Nutrient and Yield of Lettuce (Lactuca Sativa L.) in Hydroponic/Wpływ Żywienia Manganem Na Zawartość Składników I Plonowanie Sałaty (Lactuca Sativa L.) W Hydroponice

Abstract The aim of conducted studies was estimation of increase manganese nutrition on content of nutrient and yielding of lettuce (Lactuca sativa L.) in hydroponic cultivation. Plants were grown in rockwool using closed system fertigation with recirculation of nutrient solution. In experiment were used nutrient solution with following nutrient contents [mg·dm-3]: N-NH4 < 10, N-NO3 150, P-PO4 50, K 150, Ca 150, Mg 50, Fe 3.00, Zn 0.44, Cu 0.03, B 0.011, pH 5.50, EC 1.8 mS·cm-1. It was studied the following manganese concentrations in nutrient solution (in [mg・dm-3]): 0.5, 4.8, 9.6, 19.2 (described as Mn-I, Mn-II, Mn-III and Mn-IV). It was found a significant influence of increasing manganese concentration applied in fertigation on the content of: N, K (for Mn-IV); P, Fe, Cu (for Mn-III and Mn-IV); Mg, Zn (for Mn-II to Mn-IV) in aboveground parts of lettuce. It was no differences in case of calcium and sodium content. Increasing concentration of manganese used to fertigation significantly influenced the content of Mn in plants. Manganese also affected on the SPAD measurement (decreasing at Mn-IV) and yielding of the plants (decreasing for Mn-II to Mn-IV comparing with Mn-I).

Cd1−xMnxTe ultrasmall quantum dots growth in a silicate glass matrix by the fusion method

In this study, we synthesized Cd1−xMnxTe ultrasmall quantum dots (USQDs) in SiO2-Na2CO3-Al2O3-B2O3 glass system using the fusion method. Growth of these Cd1−xMnxTe USQDs was confirmed by optical absorption, atomic force microscopy (AFM), magnetic force microscopy (MFM), scanning transmission electron microscopy (TEM), and electron paramagnetic resonance (EPR) measurements. The blueshift of absorption transition with increasing manganese concentration gives evidence of incorporation of manganese ions (Mn2+) in CdTe USQDs. AFM, TEM, and MFM confirmed, respectively, the formation of high quality Cd1−xMnxTe USQDs with uniformly distributed size and magnetic phases. Furthermore, EPR spectra showed six lines associated to the S = 5/2 spin half-filled d-state, characteristic of Mn2+, and confirmed that Mn2+ are located in the sites core and surface of the CdTe USQD. Therefore, synthesis of high quality Cd1−xMnxTe USQDs may allow the control of optical and magnetic properties.

Manganese substituted cobalt ferrites as efficient catalysts for H2O2 assisted degradation of cationic and anionic dyes: Their synthesis and characterization

Manganese substituted cobalt ferrites of the formula CoMnxFe2−xO4 (x=0.2, 0.4, 0.6, 0.8 and 1.0), were synthesized by means of sol–gel auto combustion method and were annealed at different temperatures. The annealed ferrite compositions were characterized using FT-IR spectroscopy, Transmission Electron Microscopy (TEM) and powder X-Ray Diffraction techniques, substantiating the formation of pure phase ferrites. The saturation magnetization values of the entire ferrite compositions displayed a decreasing trend with increasing concentration of manganese ion, implying substitution of iron ions by manganese ions in the octahedral sites of the ferrite lattice. Additionally, the catalytic properties of these ferrites were studied. For this purpose, the ferrites were employed as heterogeneous catalysts in H2O2 assisted degradation of cationic and anionic dyes. The dyes chosen were Methylene Blue (cationic dye) and Remazol Turquoise Blue (anionic dye). The catalytic degradation of both the dyes was performed in dark as well as under visible light irradiation. Over 90% of dye degradation was achieved in a time period of 40–90min in dark and within 20–30min under visible light irradiation. In all the reactions, it was observed that the presence of Mn3+ ions in the cobalt ferrite lattice significantly augmented the degradation of dyes. Further, an increase in dye degradation was observed with increase in manganese content. The increase in the catalytic efficiency of the ferrites was correlated with their cation distribution, deduced from the saturation magnetization values on the basis of Neel's two sub-lattice model.

Magnetic and thermodynamic properties of the spin-dimer systemLa2RuO5induced by Mn substitution

Magnetic properties as well as the specific heat of the spin-dimer system ${\mathrm{La}}_{2}{\mathrm{Ru}}_{1\ensuremath{-}y}{\mathrm{Mn}}_{y}{\mathrm{O}}_{5}$ were investigated for manganese concentrations $0\ensuremath{\le}y\ensuremath{\le}0.25$. The magnetic (dc) susceptibility of the unsubstituted ($y=0$) system shows a steplike decrease close to 160 K reflecting a magnetostructural transition into a dimerized ground state. With increasing manganese concentration this behavior (typical for singlet formation) becomes continuously suppressed and the susceptibility bears the signatures of the emergence of new magnetic ground states. The high-temperature Curie-Weiss susceptibility can be described by ${\mathrm{Ru}}^{4+}$ ($S=1$) and ${\mathrm{Mn}}^{4+}$ ($S=\frac{3}{2}$) spin moments, with a dramatic decrease of the Curie-Weiss temperatures by almost 30% close to $y=0.1$, indicating significant changes in the average mean magnetic exchange. Field-cooled and zero-field-cooled experiments as well as ac-susceptibility measurements provide clear evidence for the formation of a spin-glass state, well below the characteristic dimerization temperature. The relaxation dynamics can be described by a Vogel-Fulcher-Tammann behavior and indicates high fragility when characterized in terms of glassy dynamics of canonical supercooled liquids. Additional electron-spin resonance experiments indicate different spin-glass regimes and a rather dynamic nature of the dimerized phase. In the Mn-substituted compounds, a linear contribution to the heat capacity at low temperatures can be ascribed to the spin-glass formation. With increasing manganese concentration, the anomaly in the specific heat caused by the spin-singlet formation is shifted to lower temperatures and becomes continuously suppressed and smeared out. On the basis of these results, we propose a ($y,T$)-phase diagram indicating the competition of the spin-glass and the dimerized states. We stress the similarities with doped $\mathrm{Cu}\mathrm{Ge}{\mathrm{O}}_{3}$, the canonical inorganic spin-Peierls system.

Development of Lymantria dispar affected by manganese in food.

We studied the response of gypsy moth (Lymantria dispar (Linnaeus) (Lepidoptera: Lymantriidae)) to the content of manganese in food in the laboratory breeding of caterpillars. The food of the caterpillars {Betula pendula Roth (Fagales: Betulaceae) leaves} was contaminated by dipping in the solution of MnCl2 · 4H2O with manganese concentrations of 0, 0.5, 5 and 10 mg ml(-1), by which differentiated manganese contents (307; 632; 4,087 and 8,124 mg kg(-1)) were reached. Parameters recorded during the rearing were as follows: effect of manganese on food consumption, mortality and length of the development of caterpillars, pupation and hatching of imagoes. At the same time, manganese concentrations were determined in the offered and unconsumed food, excrements, and exuviae of the caterpillars, pupal cases and imagoes by using the AAS method. As compared with the control, high manganese contents in the food of gypsy moth caterpillars affected the process of development particularly by increased mortality of the first instar caterpillars (8 % mortality for caterpillars with no Mn contamination (T0) and 62 % mortality for subjects with the highest contamination by manganese (T3)), by prolonged development of the first-third instar (18.7 days (T0) and 27.8 days (T3)) and by increased food consumption of the first-third instar {0.185 g of leaf dry matter (T0) and 0.483 g of leaf dry matter (T3)}. The main defence strategy of the caterpillars to prevent contamination by the increased manganese content in food is the translocation of manganese into frass and exuviae castoff in the process of ecdysis. In the process of development, the content of manganese was reduced by excretion in imagoes to 0.5 % of the intake level even at its maximum inputs in food.

Direct-Chill Co-Casting of AA3003/AA4045 Aluminum Ingots via Fusion™ Technology

Laboratory-scale experiments were conducted to cast AA3003/AA4045 clad ingots via Fusion™ Technology, a novel process developed by Novelis Inc. for the production of aluminum clad materials such as brazing sheet. Experimental results were used to validate a steady-state thermofluids model of the Fusion™ Technology co-casting process. The numerical model was able to accurately predict the temperature field within the AA3003/AA4045 clad ingot as well as the shape of the AA3003 liquid sump. The model was also used to quantify the temperature, fraction solid, and velocity fields in a clad ingot cast with an asymmetrical molten metal-feeding system. Feeding of core and clad molten metals at opposite corners of the mold was found to reduce the risks of hot spots and liquid metal breakthrough from the core sump to the clad side of the Fusion™ Technology mold. The use of a diffuser for the AA3003 core molten metal and of a vertical feeding tube for the AA4045 clad produced different flow patterns and liquid sump shapes on either side of the mold. The quality of the metallurgical bond at the core/clad interface appeared good near the clad inlet and at the ingot centerline, but poor near the edges of the ingot. SEM–EDS analysis of the chemical composition across the interface showed that a 1 to 20-μm-deep penetration of silicon from the AA4045 clad into the AA3003 core had occurred at visually acceptable interfaces, whereas silicon diffusion across poor interfaces was very limited. A study of the model-predicted fraction solid history at different points along the interface indicated that reheating of the AA3003 core is not required to form a visually acceptable metallurgical bond. However, a sufficient amount of interaction time between the solid AA3003 core shell and the silicon-rich AA4045 clad liquid is required to chemically dissolve the surface of the core and form a good metallurgical bond. An approximate dissolution depth of 750 to 1000 μm was observed along the visually good interface. Partial dissolution of the Mn-rich AA3003 core led to the formation of Al(Mn,Fe)Si intermetallic particles in the AA4045 clad and an increased manganese concentration near the core/clad interface.

Prediction of Toughness through Evaluation of Alloying Elements Distribution Pattern at Heat-Affected Zone in Submerged-Arc Welding Process of API X70 Steel

Six 56" × 19.8 mm, API X70 PSL2 pipes were produced from three different plate suppliers and then three samples in pipe transverse direction and perpendicular to welding seam were taken out from welding area of each supplier. Sampling carried out from weld metal, HAZ and base metal of each sample, then all 27 prepared samples were analyzed. Afterwards the amounts of 14 alloying elements were considered. The results showed that content of Carbon, Sulfur, Boron, Phosphorous, Copper, Manganese, Aluminum, Titanium and Molybdenum have been increased in the HAZ and Silicon, Nickel, Chrome, Vanadium and Niobium decreased. So it is predicted that an increase in Carbon, Aluminum, Phosphorous, Sulfur and Boron content, also a decrease in Silicon, Chrome and Nickel will cause a drop in the HAZ toughness and an increase in Titanium, Manganese, Copper and Molybdenum content, also decrease in Vanadium and Niobium will cause a rise in HAZ toughness.

Manganese Influence on Chromium Distribution in High-Chromium Cast Irons

Abstract It is shown that chromium distribution in the metal base of high-chromium cast irons depends on manganese content. According to the X-ray micro-spectral analysis data with the increase of manganese content from 0.72 to 6.49% chromium content decreased in the near-carbide zones. At the same time chromium content in carbides increased. This process obtained particularly strong development inside eutectic colonies of carbides. As a result of it, when total chromium content in the alloy has been 23%, its concentration in the local zones was 12,3%, thus the necessary level of corrosion resistance has not been provided. The minimal chromium content has to amount 23.2%, at 6.49% Mn and 2.2...2.5% C in order to provide corrosion resistance of high-chromium cast irons

Structural, morphological, dielectrical and magnetic properties of Mn substituted cobalt ferrite

The Co1−xMnxFe2O4 (0 ≤ x ≤ 0.5) ferrite system is synthesized by using an auto combustion technique using metal nitrates. The influence of Mn substitution on the structural, electrical, impedance and magnetic properties of cobalt ferrite is reported. X-ray diffraction patterns of the prepared samples confirm that the Bragg's peak belongs to a spinel cubic crystal structure. The lattice constant of cobalt ferrite increases with the increase in Mn content. The microstructural study is carried out by using the SEM technique and the average grain size continues to increase with increasing manganese content. AC conductivity analysis suggests that the conduction is due to small polaron hopping. DC electrical resistivity decreases with increasing temperature for a Co1−xMnxFe2O4 system showing semiconducting behavior. The activation energy is found to be higher in the paramagnetic region than the ferromagnetic region. Curie temperature decreases with Mn substitution in the host ferrite system. Dielectric dispersion having Maxwell—Wagner-type interfacial polarization has been observed for cobalt ferrite samples. Magnetic properties have been studied by measuring M—H plots. The saturation and remanent magnetization increases with Mn substitution.

Structural and electrochemical characterization of Li1.2Ni x Co x Mn0.8 − 2x O2 (x = 0.128, 0.16, and 0.2) as cathode materials for lithium-ion batteries

Li1.2NixCoxMn0.8 − 2xO2 (x = 0.128, 0.16, and 0.2) cathode materials have been synthesized by a simple carbonate precipitation method followed by high-temperature calcination. The effects of the transition metal content on the structure, physical property, and electrochemical performance of the samples have been investigated. As the manganese content increases, we observed not only a well-ordered layered structure and uniform morphology but also remarkable improvements in capacity and better cycling properties.

Maneb causes pro-oxidant effects in the hippocampus of Nrf2 knockout mice

The effects of maneb were investigated in C57BL/6 Nrf2 wildtype and knockout mice. Treated KO mice showed significant weight loss as compared to WT counterparts. ICPAAS analysis demonstrated a significant increase in manganese concentration in the tissues of treated KO mice as compared to WT. Biochemical analysis revealed significant decreases of antioxidants including glutathione, glutathione reductase and heme oxygenase-1. Levels of TBARS were significantly increased in hippocampal tissue in Nrf2 KO mice at the 30 and 60mg doses. qPCR demonstrated that the only gene mediated by the Nrf2 transcription pathway that was significantly modulated by at least 1.5 fold was glutathione peroxidase 4. GPX4 was significantly upregulated in Nrf2 WT mice treated with 30mg/kg maneb and significantly downregulated in Nrf2 KO mice treated with the same dose. Microscopy revealed neuronal pyknosis and eosinophilia of the cytoplasm in the hippocampi of both WT and KO animals treated with 60mg/kg maneb.

Effect of Manganese on Microstructure and Mechanical Properties of Cast High Alloyed CrMnNi‐N Steels

The effect of the manganese content (0–11%) on the transformation temperatures, the mechanical properties and microstructure development of five highly alloyed 14Cr–XMn–6Ni cast stainless steels with 0.1% nitrogen was studied. The examinations reveal that the Ms, As, and Af temperatures decrease with increasing manganese contents. As a result of low austenite stability, room temperature austenitic‐martensitic as‐cast microstructure was formed at manganese contents between 0 and 3%. At manganese levels of 6% and higher a fully austenitic as‐cast microstructure was observed. The temperature dependence of tensile properties in alloys was explained on the basis of varying contributions to the strength and ductility of deformation‐induced martensite and twin formation mechanisms. All investigated cast steel alloys achieved yield strengths above 200 MPa at room temperature. The increased proof stress is caused by solid solution strengthening due to the addition of nitrogen and manganese as well as phase hardening by as‐quenched martensite.

Multi-component perovskite-type oxides CaCu3V4−xMnxO12: Synthesis and electronic properties

New multi-component perovskite-type oxides CaCu3V4−xMnxO12 with 0.5≤x≤2.0 have been synthesized at high pressures (P=8.0–9.0GPa) and high temperatures (T=1000–1300°C). Their crystal structure and grain sizes were evaluated by X-ray diffraction and scanning electron microscopy, respectively. Using ab initio calculations we studied the electronic and magnetic properties of CaCu3V3MnO12 and CaCu3V2Mn2O12 in comparison with CaCu3V4O12 and CaCu3Mn4O12. Within the GGA+U approximation, a phase transition from ferrimagnetic half-metal to ferrimagnetic semiconductor was predicted for CaCu3V4−xMnxO12 with increasing manganese concentration. The magnetic couplings for CuV and CuMn are antiferromagnetic, while MnMn, CuCu, and CuV are coupled ferromagnetically.

Sorption of As(III) and As(V) on chemically synthesized manganese dioxide

Sorption of As(III) and As(V) on manganese dioxide was studied by batch equilibration method using 76As radioactive tracer. Manganese dioxide was prepared by two different methods viz. reacting (a) KMnO4 solution with MnSO4 solution, and (b) KMnO4 solution with concentrated hydrochloric acid. Manganese dioxide was characterized by zeta potential measurement, surface area measurement, thermogravimetry (TG), differential thermal analysis (DTA) and X-ray diffraction (XRD) techniques. Point of zero charge (PZC) for manganese dioxide was between pH 3 and 4. Radioactive tracer (76As) was prepared by neutron irradiation of arsenious oxide in self serve facility of CIRUS reactor followed by conversion to As(III) and As(V), by appropriate chemical methods. Sorption of As(III) and As(V) were studied separately, between pH 1 to 11, using (i) freshly prepared, (ii) air-dried and (iii) aged manganese dioxide. Sorption of As(III) and As(V) on freshly prepared as well as aged manganese dioxide, from both the methods was greater than 98% between pH 1 to 9 and decreased above pH 9. Percentage sorption was comparable for manganese dioxide prepared by both the methods in different batches. Sorption capacity was ∼2 mg g−1 for both As(III) and As(V). Arsenic was desorbed from the manganese dioxide by 0.1 M sodium hydroxide and oxidation state of desorbed arsenic was determined by solvent extraction method. It was found that the desorbed arsenic was present in As(V) oxidation state, independent of the initial oxidation states. This simple and direct chemical evidence, establishing that As(III) is converted to As(V) by manganese dioxide, is reported for the first time. Sorption of As(III) and As(V) on manganese dioxide did not cause an increase in manganese concentration above solubility limit confirming that Mn2+, formed during oxidation of As(III) to As(V), was re-adsorbed.

박육주철의 공정 셀 수와 칠 깊이에 미치는 두께, 기본 원소 및 접종제 첨가 원소의 영향

The effects of thickness, base element and additive to inoculant on the number of eutectic cells and chill depth of thin-section gray cast iron were investigated. Meanwhile the number of eutectic cells increased by inoculation, chill depth decreased. The former decreased and the latter increased by holding the melt at the temperature range between 1,450 and <TEX>$1,500^{\circ}C$</TEX>. The former was more for the thinner casting with the thickness of 5 mm than the other. The result of thermal analysis coincided well with the change of macrostructure. The former increased and the latter decreased with the increased contents of carbon, silicon and the silicon content by inoculation. The former decreased and the latter increased with increased manganese content. The number of eutectic cells decreased as the amounts of rare earth and the bismuth added to this inoculant increased. With the addition of sulfur of 0.10 wt% of the weight of this inoculant, the maximum number of eutectic cells was obtained.

New observation of morphology of Li[Fe1−xMnx]PO4 nano-fibers (x=0, 0.1, 0.3) as a cathode for lithium secondary batteries by electrospinning process

The key issue with lithium iron phosphate (LiFePO4) is poor ionic conductivity. Electrospinning is one of the best way to increase a surface area. Therefore, electrospinning was presently adopted to solve the kinetic problems associated with the solid-state diffusion of Li+ intercalation. In this work, nano-fibers of Li[Fe1−xMnx]PO4 (x=0, 0.1, 0.3) were prepared from sol–gel precursor by electrospinning. After calcinations of the precursor nano-fibers at 800°C, Li[Fe1−xMnx]PO4 nano-fibers (x=0, 0.1, 0.3) with a diameter of 100–500nm were successfully obtained. X-ray diffraction (XRD), videoscope, field emission scanning electron microscope (FE-SEM) and atomic force microscopy (AFM) analyses were performed to characterize the properties of the prepared materials. The purpose of the present study is to investigate the morphology change of nano-sized Li[Fe1−xMnx]PO4 (x=0, 0.1, 0.3) obtained through electrospinning. Li[Fe1−xMnx]PO4 (x=0.1, 0.3) nano-fibers displayed a rough surface due to the increased manganese content. To the best of our knowledge, this is the first report of its kind.

Excess manganese differentially inhibits photosystem I versus II in Arabidopsis thaliana.

The effects of exposure to increasing manganese concentrations (50–1500 µM) from the start of the experiment on the functional performance of photosystem II (PSII) and photosystem I (PSI) and photosynthetic apparatus composition of Arabidopsis thaliana were compared. In agreement with earlier studies, excess Mn caused minimal changes in the PSII photochemical efficiency measured as Fv/Fm, although the characteristic peak temperature of the S2/3QB – charge recombinations was shifted to lower temperatures at the highest Mn concentration. SDS-PAGE and immunoblot analyses also did not exhibit any significant change in the relative abundance of PSII-associated polypeptides: PSII reaction centre protein D1, Lhcb1 (major light-harvesting protein of LHCII complex), and PsbO (OEC33, a 33kDa protein of the oxygen-evolving complex). In addition, the abundance of Rubisco also did not change with Mn treatments. However, plants grown under excess Mn exhibited increased susceptibility to PSII photoinhibition. In contrast, in vivo measurements of the redox transients of PSI reaction centre (P700) showed a considerable gradual decrease in the extent of P700 photooxidation (P700+) under increased Mn concentrations compared to control. This was accompanied by a slower rate of P700+ re-reduction indicating a downregulation of the PSI-dependent cyclic electron flow. The abundance of PSI reaction centre polypeptides (PsaA and PsaB) in plants under the highest Mn concentration was also significantly lower compared to the control. The results demonstrate for the first time that PSI is the major target of Mn toxicity within the photosynthetic apparatus of Arabidopsis plants. The possible involvement mechanisms of Mn toxicity targeting specifically PSI are discussed.

Manganese-based regenerable sorbents for high temperature H2S removal

A series of sorbents with different manganese contents have been prepared by co-precipitation method for 850°C regenerative H2S removal. The sulfur capacity increased linearly with the increase of manganese content. The performance of sorbents prepared by co-precipitation of Mn nitrate and Al nitrate appears to be stable over five sulfidation–regeneration cycles. Al2O3 plays an important role in the performance of sorbents and the recovery of elemental sulfur in O2 regeneration. With increasing Mn content in the sorbent, increasing O2 concentration in the regeneration gas or increasing total regeneration gas flow rate, the recovery of elemental sulfur decreased. Elemental sulfur is the only product with SO2 regeneration. The sorbents cannot be completely regenerated with SO2 under the conditions used. The sorbents, however, can be completely regenerated by steam. The main product for steam regeneration is H2S. Steam regeneration results in less sintering than O2 regeneration.

Influence of Mn doping on structural and optical properties of ZnO nano thin films synthesized by sol–gel technique

Undoped and Mn-doped ZnO samples with different percentages of Mn content (1, 5 and 10 at%) were synthesized by a dip-coating sol–gel method. We have studied the structural, chemical and optical properties of the samples by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-visible spectroscopy. The XRD spectra show that all the samples are hexagonal wurtzite structures. We note that doping favors c-axis orientation along (002) planes. Up to 5 at% of Mn doping level, the c-axis lattice parameter shifts towards higher values with the increase of manganese content in the films. The expansion of the lattice constant of ZnO–Mn indicates that Mn is really doped into the ZnO. The SEM investigations of all samples revealed that the crystallites are of nanometer size. The surface quality of the ZnO–Mn film increases with Mn doping but no significant change of the grain size is observed from SEM images. The transmittance spectra show that the transparency of all the samples is greater than 85 %. We note, also, that a small doping (1 %) lowered the refractive index while the thickness of the layers and the gap increase. However, on raising the proportion of Mn beyond 5 %, practically the same values of index and gap as pure ZnO are found.