Effect Of Mn2 Research Articles

Zinc supplementation decreases galactosylation of recombinant IgG in CHO cells.

Trace element composition of culture medium can be altered to modulate glycoform of recombinant glycoproteins. In this study, we show that Zn2+ supplementation at or above 100μM decreases galactosylation of recombinant IgG expressed in Chinese Hamster Ovary cells. This decrease in galactosylation is not due to reduced galactosyltransferase expression. This effect persists upon supplementation of galactose and uridine to the culture, indicating that it may not be due to reduced UDP-Gal availability. Measurements of galactosyltransferase activity in the cell lysate show that activity decreases with increasing Zn2+/Mn2+ ratio. This suggests that one possible explanation of the effect of Zn2+ may be reduced intracellular galactosyltransferase activity due to increase in Zn2+/Mn2+ ratio. Consistent with this, the decrease in galactosylation of IgG could be reversed by supplementation of Mn2+ (a cofactor of galactosyltransferase) which increases intracellular Mn2+ content. Measurement of total intracellular Zn2+ content, however, indicates no significant upregulation of total intracellular Zn2+ content and no significant downregulation of intracellular Mn2+ content with Zn2+ supplementation. One possible explanation could be that cellular detoxification response to higher extracellular Zn2+ concentration might lead to changes in intracellular distribution of Mn2+. In this case, Zn2+ supplementation would be expected to interfere with other known effects of Mn2+. Indeed, the previously reported increase in high mannose glycans upon Mn2+ supplementation in the absence of glucose is reversed by Zn2+ supplementation. This study also suggests the use of Mn2+ supplementation as a strategy to overcome the effect of lot-to-lot variability in trace element concentrations on galactosylation.

Effect of Mn2+ ions on Structural and Magnetic properties of Co-precipitated Ni-Cr nano ferrite for Potential applications as MRI Contrast agent

Effect of Mn2+ ions on Structural and Magnetic properties of Co-precipitated Ni-Cr nano ferrite for Potential applications as MRI Contrast agent

Blue, Green and Yellow Emissions at the Same Time from Mn-doped ZnS Microbelts

We present an investigation of the morphology, structure, composition and optical properties of ZnS:Mn2+ microbelts grown by the thermal evaporation method using ZnS powder and MnCl2.4H2O powder as precursor materials. The SEM images of the products show that ZnS:Mn2+ microbelts are bigger and shorter than ZnS microbelts. EDS reveals that the composition of the microbelts include Zn, S, O, Mn and Cl elements. The atom rate of oxygen composition of the doped microbelts seem to be slightly lower than undoped ones. XRD pattern of the prepared microbelts shows that ZnO coexists with ZnS on the undoped microbelts. However, at the Mn-doped microbelts, the component phase of ZnO is disappeared. Photoluminescence spectra of undoped ZnS microbelts reveal a strong broad emission band at visible wavelength region and a weak ultraviolet band. Interestingly, when Mn2+ is doped into the microbelts, the visible emission band is separated into blue, green, and yellow bands peaking at around 442, 520 nm, and 572 nm, respectively. The effects of Mn2+ ions on the emission bands is discussed in detail.

Incorporation of Mn2+ into CdSe quantum dots by chemical bath co-deposition method for photovoltaic enhancement of quantum dot-sensitized solar cells.

A photoelectric conversion efficiency (PCE) of 4.9% was obtained under 100 mW cm−2 illumination by quantum-dot-sensitized solar cells (QDSSCs) using a CdS/Mn : CdSe sensitizer. CdS quantum dots (QDs) were deposited on a TiO2 mesoporous oxide film by successive ionic layer absorption and reaction. Mn2+ doping into CdSe QDs is an innovative and simple method—chemical bath co-deposition, that is, mixing the Mn ion source with CdSe precursor solution for Mn : CdSe QD deposition. Compared with the CdS/CdSe sensitizer without Mn2+ incorporation, the PCE was increased from 3.4% to 4.9%. The effects of Mn2+ doping on the chemical, physical and photovoltaic properties of the QDSSCs were investigated by energy dispersive spectrometry, absorption spectroscopy, photocurrent density–voltage characteristics and electrochemical impedance spectroscopy. Mn-doped CdSe QDs in QDSSCs can obtain superior light absorption, faster electron transport and slower charge recombination than CdSe QDs.

Sol-gel Auto Combustion Synthesis, Structural and Magnetic Properties of Mn doped ZnO Nanoparticles

Mn2+ doped ZnO nanoparticles were synthesized by sol–gel auto combustion technique. The effects of Mn2+ doping on the structural and magnetic properties of ZnO nanoparticles were investigated. Synthesized nanoparticles were characterized by X-ray diffraction technique (XRD), Fourier transform infrared spectroscopy (FTIR). The hexagonal wurtzite structure with single phase of Mn2+ doped ZnO nanoparticles were confirmed by XRD analysis. The average crystallite size determined by Scherrer’s formula was found in the range 14–17 nm. It is observed that the lattice parameter, volume of unit cell, X-ray density, and atomic packing fraction increase with increasing Mn2+ content. FTIR analysis revealed a slight change in main absorption band of ZnO in the frequency range of 500-1000 cm−1. Magnetic characterization was performed using vibrating sample magnetometer (VSM) and, which evidenced the properties of pure ZnO and Mn doped ZnO nanoparticles showed the diamagnetic and paramagnetic behaviour respectively.

Phosphine-Free, Highly Emissive, Water-Soluble Mn:ZnSe/ZnS Core–Shell Nanorods: Synthesis, Characterization, and in Vitro Bioimaging of HEK293 and HeLa Cells

Phosphine-free, highly luminescent one-dimensional Mn2+ ion-doped ZnSe(core)/ZnS(shell) nanorods (NRs) were synthesized by heating-up method (core) followed by hot injection route (shell). Effect of Mn2+ doping and shell thickness on structural and optical properties is reported. The NRs were formed with wurtzite-structured Mn:ZnSe core (diameter 2.52 nm) encapsulated epitaxially by a wurtzite-structured ZnS shell (thickness of 3.51 nm) with 3.1% lattice mismatch that alters the band alignment of the overall core–shell structure. A redshift was observed in optical absorption and photoluminescence (PL) emission due to an overall size increase with increasing shell thickness. Because of the reduction of defects/traps by surface passivation, the maximum photoluminescence quantum yield (QY) was obtained to be 49.35%. The exciton radiative lifetime for the core–shell NRs (1.678 ms) was more prolonged than that of the core (0.573 ms). A clear dependence of QY and lifetime was established on the Mn2+ content and...

Triangular CdS nanostructure: effect of Mn doping on photoluminescence, electron spin resonance, and magneto-optical properties

In this paper, we report synthesis and study of magneto-optic Faraday effect for dilute magnetic semiconductor nanostructure. The colloidal CdS nanocrystals were prepared via hot injection method and successfully doped with Mn2+ cations. The synthesized nanoparticles were characterized by using UV–Vis spectroscopy, X-ray diffraction, photoluminescence spectroscopy, transmission electron microscopy, and electron spin resonance spectroscopy. Systematic studies on effect of Mn2+ doping on photoluminescence, electron spin resonance, and magneto-optical properties are carried out. UV–Vis spectral analysis confirms blue shift in bandgap of CdS nanoparticles due to quantum confinement effect. The X-ray diffraction study confirms hexagonal wurtzite phase formation of CdS nanoparticles without any impurity phases. TEM analysis confirms uniform particle size, having particle size distribution around 5 nm. As-synthesized undoped CdS shows triangular-shaped nanocrystals with hexagonal structure; however, triangular shape of CdS nanoparticles is not conserved after Mn2+ doping. The photoluminescence characteristic spectra of Mn2+-doped CdS nanocrystals showed emission band at 660 nm and its intensity was found to increase with increasing Mn2+ concentration. Electron spin resonance signal, with six-line hyperfine structure splitting, confirmed doping of Mn2+ ions in CdS lattice. Magneto-optic measurements showed linear variation of Faraday rotation with respect to applied magnetic field, indicating paramagnetic behavior of Mn-doped CdS. The highest Verdet constant 24.81 deg/T cm was observed for 2% Mn-doped CdS nanocrystals, which further decreases with increasing Mn2+ concentration.

Enhancing lignin degradation by Mn2+ ion supplementation to assist enzymatic hydrolysis of cellulose in a two-stage pretreatment of bamboo

Abstract: It is of great significance to reveal a key agent to improve the efficiency of conversion of lignocellulosic biomass to fermentable sugars for the production of bioethanol. This study investigated a two-stage pretreatment of bamboo comprising a microbial treatment using Ceriporiopsis sp. followed by a hydrothermal treatment to facilitate the process with Mn2+ as an accelerator. The effects of Mn2+ nutritional addition on ligninolytic activity, lignin degradation, total weight loss, pulp yield, sugar yield and sugars in the soluble fraction were examined. The results showed that the time required for the incubations supplemented with Mn2+ to achieve sufficient lignin degradation and sugar yield from both the pulp and soluble fractions was significantly shortened, whereas all three ligninolytic activities were significantly decreased. The enzyme activity varied according to the presence of Mn2+, although the amount and species of the expressed protein are similar. Considering the cost, microbial treatment with a one-time fed-batch supply of metal nutrition (MnSO4) was the most preferable contribution to hydrothermal pretreatment, resulting in 19.7% lignin degradation, 66.7% pulp yield and 26.1% sugar yield over a period of 21 d. It was proven that microbial treatment by solid state incubation with Mn2+ nutrition has the potential to be a low-cost, environmentally friendly alternative to chemical approaches. Keywords: hydrolysis, fungi, Mn2+ ion, pretreatment, bamboo, Ceriporiopsis sp. DOI: 10.3965/j.ijabe.20171003.2991 Citation: Liu J, Gan L H, Long M N. Enhancing lignin degradation by Mn2+ ion supplementation to assist enzymatic hydrolysis of cellulose in a two-stage pretreatment of bamboo. Int J Agric & Biol Eng, 2017; 10(3): 175–184.

A novel temperature stable and high Q microwave dielectric ceramic in Li3(Mg1−xMnx)2NbO6 system

The compositions of Li3(Mg1−xMnx)2NbO6 ceramics were prepared by the conventional solid state reaction method. The effects of Mn2+ substitution on the microstructure, sintering behavior and microwave dielectric properties of Li3(Mg1−xMnx)2NbO6 ceramics were investigated systematically. The XRD patterns revealed that all the specimens sintered at 1075–1200 °C remained a single phase with orthorhombic structure. The obtained microwave dielectric properties indicated that appropriate amount of Mn2+ substitution for Mg2+ could significantly promote the grain growth and densify Li3Mg2NbO6 ceramics. The permittivity and Q × f values were strongly dependent on the bulk density and grain size, respectively. And near zero τ f values could be realized in the Li3(Mg1−xMnx)2NbO6 (0.02 ≦ x ≦ 0.08) compounds sintered at 1125 °C. To sum up, the x = 0.02 sample sintered at 1125 °C for 4 h exhibited excellent microwave dielectric properties of er ~ 15.22, Q × f ~110,582 GHz, τ f ~−4.57 ppm/°C which demonstrated that the Li3(Mg0.98Mn0.02)2NbO6 ceramic would be a novel temperature stable and high Q material for microwave device.

Effect of Mn2+ and Cu2+ co-doping on structural and luminescent properties of ZnS nanoparticles

Undoped and transition metal (Cu, Mn, Cu:Mn) doped ZnS nanoparticles are synthesized by chemical co-precipitation method via an aqueous synthesis route. Synthesized samples are characterized by various techniques for their structural and optical properties. Crystallite size obtained from X-Ray Diffraction (XRD) is 1.68, 1.87, 1.50, 1.42nm for undoped, Cu, Mn, Cu:Mn doped ZnS nanoparticles. The XRD, High Resolution Transmission Electron Microscopy, and Selected Area Electron Diffraction confirm the evolution of stable hexagonal phase of ZnS nanoparticles at low temperature. Energy Dispersive Spectroscopy confirms the doping of nanoparticles. Blue shift in UV absorbance shows the increase in optical bandgap with decrease in particle size. The Photoluminescence studies exhibit blue, yellow and red emission in visible region. Surface functionalization of nanoparticles is confirmed from Fourier Transform Infra Red spectroscopy. The present samples are tunable in wider range of emission and are prospective candidates for biological labels due to their fluorescent properties.

Novel Synthesis of Spinel Mn x Co1−x Al2 O 4 (x = 0.0 to 1.0) Nanocatalysts: Effect of Mn2+ Doping on Structural, Morphological, and Opto-Magnetic Properties

In this present study, Mn2+doped CoAl2O4 (MnxCo1−xAl2O4; x = 0.0 to 1.0) spinel nanoparticles were synthesized by microwave combustion method using nitrates of Co, Mn, and Al as the starting materials and urea was used as the fuel. The effects of Mn2+ doping on structural, morphological, opto-magnetic and catalytic properties were studied. Powder X-ray diffraction analysis was confirmed the formation of cubic spinel aluminate structure. Debye-Scherrer’s formula was used to estimate the average crystallite size of the samples and was found to be in the range of 18.26 to 21.47 nm. It was observed that the calculated lattice parameter value is increased from 8.215 to 8.247 A with increasing the Mn2+ content due to the higher ionic radius of Mn2+ ion. High resolution scanning electron microscopy (HR-SEM) and transmission electron microscopy (HR-TEM) analysis confirmed the nano-sized particle-like morphology of the samples. Energy dispersive X-ray (EDX) results showed the pure form of spinel aluminate structure. The band gap energy (Eg) of undoped CoAl2O4 was estimated to be 3.58 eV from UV-visible diffuse reflectance spectroscopy (DRS), and the Eg values increased with increase of Mn2+ ions due to the decrease of grain size. The magnetic hysteresis (M-H) loop showed the superparamagnetic nature of the samples, and the saturation magnetization values increased with increasing Mn2+ ions, which was confirmed by vibrating sample magnetometer (VSM). All compositions of the samples were successfully tested as catalyst for the conversion of benzyl alcohol into benzaldehyde and observed good catalytic activity.

The reversibility of the inverse magnetocaloric effect in Mn2−xCrxSb0.95Ga0.05

Mn2−xCrxSb exhibits an antiferromagnetic-ferrimagnetic transition of which the temperature can be adjusted by the Cr concentration. The transition temperature is at room temperature for x = 0.13, but an additional ferromagnetic MnSb impurity phase is usually inevitable at this concentration. To suppress the occurrence of this phase unfavorable for the magnetocaloric effect, we partially replace Sb by Ga. We show that Mn2−xCrxSb0.95Ga0.05 alloys have a narrow transitional hysteresis and exhibit the inverse magnetocaloric effect. We present here results on structural, magnetic, and magnetocaloric properties using isothermal magnetization and direct adiabatic temperature-change measurements. We find in particular for the sample with x = 0.13 a nearly hysteresis-free transition with a 2 K temperature-change around room temperature making it attractive for magnetic cooling technology.

Metal-Induced Stabilization and Activation of Plasmid Replication Initiator RepB.

Initiation of plasmid rolling circle replication (RCR) is catalyzed by a plasmid-encoded Rep protein that performs a Tyr- and metal-dependent site-specific cleavage of one DNA strand within the double-strand origin (dso) of replication. The crystal structure of RepB, the initiator protein of the streptococcal plasmid pMV158, constitutes the first example of a Rep protein structure from RCR plasmids. It forms a toroidal homohexameric ring where each RepB protomer consists of two domains: the C-terminal domain involved in oligomerization and the N-terminal domain containing the DNA-binding and endonuclease activities. Binding of Mn2+ to the active site is essential for the catalytic activity of RepB. In this work, we have studied the effects of metal binding on the structure and thermostability of full-length hexameric RepB and each of its separate domains by using different biophysical approaches. The analysis of the temperature-induced changes in RepB shows that the first thermal transition, which occurs at a range of temperatures physiologically relevant for the pMV158 pneumococcal host, represents an irreversible conformational change that affects the secondary and tertiary structure of the protein, which becomes prone to self-associate. This transition, which is also shown to result in loss of DNA binding capacity and catalytic activity of RepB, is confined to its N-terminal domain. Mn2+ protects the protein from undergoing this detrimental conformational change and the observed protection correlates well with the high-affinity binding of the cation to the active site, as substituting one of the metal-ligands at this site impairs both the protein affinity for Mn2+and the Mn2+-driven thermostabilization effect. The level of catalytic activity of the protein, especially in the case of full-length RepB, cannot be explained based only on the high-affinity binding of Mn2+ at the active site and suggests the existence of additional, lower-affinity metal binding site(s), missing in the separate catalytic domain, that must also be saturated for maximal activity. The molecular bases of the thermostabilizing effect of Mn2+ on the N-terminal domain of the protein as well as the potential location of additional metal binding sites in the entire RepB are discussed.

Correlation of crystal structure and microwave dielectric characteristics of temperature stable Zn1−xMnxZrNb2O8 (0.02≤x≤0.1) ceramics

Wolframite-structured Zn1−xMnxZrNb2O8 (x=0.02, 0.04, 0.06, 0.08, 0.10) ceramics were synthesized by the conventional solid-state method. The effects of Mn2+ substitution on the crystal structure, crystal chemistry and microwave dielectric properties of ZnZrNb2O8 were investigated. Bond ionicity, lattice energy and thermal expansion of the ceramics were calculated by the complex chemical bond theory, which were used to investigate the correlation between intrinsic factors and microwave dielectric properties. The εr values were dependent on the electronic oxide polarizabilities of Zn1−xMnxZrNb2O8 ceramics. The Q·f values decreased from 51,300 to 44,900GHz, which could be explained in terms of packing fraction and lattice energy. The τf values were shifted to positive direction with the increase of Mn2+ contents, which indicated that the distortion of the [BO6] octahedral was closely related to τf values. In addition, thermal expansion coefficient also affected the temperature stability of ceramics. Typically, an excellent microwave dielectric property was obtained in the Zn0.9Mn0.1ZrNb2O8 with a εr of 29.43, an appropriate Q·f of 44,900GHz and a near zero τf of −5.61ppm/°C.

The impact of manganese on biofilm development of Bacillus subtilis.

Bacterial biofilms are dynamic and structurally complex communities, involving cell-to-cell interactions. In recent years, various environmental signals that induce the complex biofilm development of the Gram-positive bacterium Bacillus subtilis have been identified. These signalling molecules are often media components or molecules produced by the cells themselves, as well as those of other interacting species. The responses can also be due to depletion of certain molecules in the vicinity of the cells. Extracellular manganese (Mn2+) is essential for proper biofilm development of B. subtilis. Mn2+ is also a component of practically all laboratory biofilm-promoting media used for B. subtilis. Comparison of complex colony biofilms in the presence or absence of supplemented Mn2+ using microarray analyses revealed that genes involved in biofilm formation are indeed downregulated in the absence of Mn2+. In addition, Mn2+ also affects the transcription of several other genes involved in distinct differentiation pathways of various cellular processes. The effects of Mn2+ on other biofilm-related traits like motility, antimicrobial production, stress and sporulation were followed using fluorescent reporter strains. The global transcriptome and morphology studies highlight the importance of Mn2+ during biofilm development and provide an overview on the expressional changes in colony biofilms in B. subtilis.

Investigation of optical, structural properties of Eu3+ by Mn2+ in barium alumino borosilicate glasses

The Mn2+ ions doped Eu2O3BaOAl2O3B2O3SiO2 glasses are synthesized by conventional melt quenching method. The effect of Mn2+ ions on spectroscopic, structural properties of Eu3+ ions in glass networks is analysed. An analysis of XRD traces evidently suggests the glassy nature of the prepared samples. The UV–Vis absorption and the luminescence spectra have been used to study the variations in the optical character of Eu3+ ions. In luminescence spectra five bands can be observed at about 578, 590, 612, 653 and 702 nm as a result of transitions of Eu3+ ions from 5D0→7F0, 1, 2, 3, 4 respectively. By gradual increment of MnO mol% in the glass matrix, the strong variation in the intensity of emission band are observed at about 612 nm (5D0→7F2). The non-radiative energy transfer (Mn2+ ↔ Eu3+) and concentration quenching are observed in the prepared glasses. The ESR spectra exhibit a sixtet hyperfine structure centered at g = ∼2.0047 which suggests that manganese ions predominantly occupy octahedral positions.

Porous Mn-doped ZnO nanoparticles for enhanced solar and visible light photocatalysis

Porous Mn-doped ZnO (ZnO:Mn) nanoparticles with an average diameter of ca. 21nm were prepared by a simple and cheap solvothermal process involving no templates, post-synthetic annealing or etching. The particles produced were characterized by XRD, Raman spectroscopy, SEM, TEM, XPS, diffuse reflectance spectroscopy and BET surface area measurements and the effects of Mn2+-doping on the structural, optical and photocatalytic properties of ZnO particles were investigated. The particles doped with 3mol% Mn2+ were found to exhibit the highest catalytic activity toward the photodegradation of the Orange II dye under solar light irradiation. Our results demonstrate that Mn2+-doping shifts the optical absorption to the visible region, increases the specific surface area of the photocatalyst and reduces the recombination of electron-hole pairs. The influence of various operational parameters (amount of catalyst, concentration of dye and pH) on the photodegradation and the photocatalytic mechanism were studied. Finally, we demonstrated that the ZnO:Mn photocatalyst is stable and can be easily recycled up to ten times without any significant decrease in photocatalytic activity.

Evaluation of anti-proliferative and proapoptotic effects of Mn2+ complex of the N, N′-dipyridoxyl (1, 2-diaminobenzene) schiff base against human breast cancer cells (MCF7)

Evaluation of anti-proliferative and proapoptotic effects of Mn2+ complex of the N, N′-dipyridoxyl (1, 2-diaminobenzene) schiff base against human breast cancer cells (MCF7)

Li2O[sbnd]LiF[sbnd]ZnF2[sbnd]B2O3[sbnd]P2O5: MnO glasses – Thermal, structural, optical and luminescence characteristics

Here, we present results pertaining to thermal, structural, optical and photoluminescence properties of Li2OLiFZnF2B2O3P2O5: (0.1–1.5mol.%) MnO glasses. DTA profiles revealed a change in glass transition temperature with the addition of MnO suggesting an increase in glass stability. The modifications in structural units are interpreted from FTIR and Raman spectral profiles, which confirm the formation of stable POB bonds. The host Li2OLiFZnF2B2O3P2O5 (labelled as LZBP) glass exhibits emission in the blue region on excitation with 361nm. The red shift in optical absorption edge and decrease in energy of band gap as a function of MnO concentration is analysed from Tauc’s plot. The nature of local symmetry around manganese ions in LZBP matrix has been understood by evaluating the crystal field strength (Dq) and Racah inter-electronic repulsion parameters (B &C) from absorption spectrum and electron-lattice interaction energy (Sħω) factor from emission spectrum. The emission spectra of (0.1–1.5mol.%) Mn2+: LZPB glasses have shown broad band at 613nm assigned to electronic transition 4T1g(G)→6A1g(S) displaying orange-red emission upon excitation at 413nm. Octahedral coordination of Mn2+ ions has been estimated from the position of emission in luminescence spectra. The effect of Mn2+ concentration on emission properties has been discussed from lifetime curves and energy level scheme.

Mössbauer studies on Mn substituted CoFe2O4/SiO2 nanocomposites synthesized by sol–gel method

Mn-substituted CoFe2O4 nanoparticles dispersed in SiO2 matrix (Co1−xMnxFe2O4/SiO2) were synthesized by a sol–gel method. The effects of Mn2+ content and annealing temperature on their structural and magnetic properties as well as cation distribution were studied in detail by X-ray diffraction, vibrating sample magnetometer and Mössbauer spectroscopy at room temperature. The results show that the Co1−xMnxFe2O4 in the samples annealed at above 700°C exhibits cubic spinel structure. The lattice constant of Co1−xMnxFe2O4 nanoparticles increases with increasing Mn2+ content because of the substitution of Co2+ ion with a small ionic radius by Mn2+ ion with a relatively large ionic radius and most of Mn2+ ions tend to substitute Co2+ ions at octahedral B sites. The saturation magnetization, coercivity and hyperfine fields for Co1−xMnxFe2O4/SiO2 nanocomposites increase with increasing Mn2+ content when x≤0.2, and then decrease for higher Mn2+ content, these changes are strongly dependent on the cation distribution. Furthermore, with increasing annealing temperature, the crystallite size, saturation magnetization and coercivity of the samples increase, the sample transfers from the mixed state of superparamagnetic and magnetic order to the completely magnetic order and Mn2+ ions migrate from the tetrahedral A sites to octahedral B sites.