Green emission from ZnO–MgO nanocomposite due to Mg diffusion at the interface

International Nuclear Information System (INIS)

Sowri Babu, K.; Ramachandra Reddy, A.; Venugopal Reddy, K.

2015-01-01

The origin and electronic transitions responsible for green emission observed from ZnO–MgO nanocomposite are investigated. The photoluminescence (PL) spectrum of ZnO–MgO nanocomposite annealed at 600 °C showed only a sharp and intense UV emission peak centered at 396 nm. As the annealing temperature increased from 600 °C to 1000 °C, the green emission positioned at 503 nm is emerged and its intensity enhanced gradually and reached maximum value at 900 °C and then decreased at 1000 °C. It is observed that both UV and green emission intensities are enhanced with variation of atomic ratio (Zn/Mg=1.52, 0.50, 0.30, 0.21, 0.15). Our experiments confirmed that the enhancement of green emission intensity is due to the formation of oxygen vacancies (V o ) due to Mg doping at the interface of ZnO and MgO. This experimental observation is in good agreement with the recent theoretical predictions which states that Mg doping in ZnO lowers the formation energies of oxygen vacancies (V o ) and zinc interstitials (Zn i ) significantly. PL excitation and emission spectra analysis reveals that excited state for both UV and green emissions is same and lies 0.24 eV below the conduction band of ZnO. Hence, the green emission is attributed to the transition of an electron form the shallow donor (defect level of Zn i ) to the deep acceptor (defect level of V o ). - Highlights: • It is found that the UV emission intensity from ZnO–MgO nanocomposite enhanced with increase of Mg concentration. • The intensity of the green emission is enhanced gradually as the temperature increased from 600 °C to 900 °C and then decreased at 1000 °C. • The effect of Mg concentration, MgO, strain at the interface on green emission is investigated. • These experiments confirmed that green emission is due to the oxygen vacancies created in ZnO due to the Mg doping at the interface and it is in good agreement with the theoretical predictions. • The decrease of green emission intensity is

Characterization of Mg-containing hydroxyapatites synthesized by combustion method

Science.gov (United States)

Kaygili, Omer; Keser, Serhat; Bulut, Niyazi; Ates, Tankut

2018-05-01

In the present paper, Mg-substituted hydroxyapatites with the morphology, composed of the stacked plate- and rod-like structures, were prepared at the temperature of 600 °C by combustion method using glycerine as a fuel. A significant decrease in the crystallite size values calculated for both Scherrer and Williamson-Hall methods is found. The crystallinity, lattice parameter of a, stress and anisotropic energy density values decreased by adding of Mg, whereas the lattice strain increased. The amount of HAp phase decreases with increasing amount of Mg and the β-tricalcium phosphate content increases. Mg incorporation the apatitic structure was detected. Depending on the increase in Mg content, Ca-deficiency was observed.

Room temperature ferromagnetism in Mg-doped ZnO nanoparticles

International Nuclear Information System (INIS)

Singh, Jaspal; Vashihth, A.; Gill, Pritampal Singh; Verma, N. K.

2015-01-01

Zn 1-x Mg x O (x = 0, 0,10) nanoparticles were successfully synthesized using sol-gel method. X-ray diffraction (XRD) confirms that the synthesized nanoparticles possess wurtzite phase having hexagonal structure. Morphological analysis was carried out using transmission electron microscopy (TEM) which depicts the spherical morphology of ZnO nanoparticles. Energy dispersive spectroscopy (EDS) showed the presence of Mg in ZnO nanoparticles. Electron spin resonance (ESR) signal was found to be decreasing with increasing of Mg-doping concentration. The room temperature ferromagnetism was observed in undoped and Mg-doped ZnO nanoparticles. The increase of Mg-doping concentration resulted in decrease of saturation magnetization value which could be attributed to decrease of oxygen vacancies present in host nanoparticles

Facile fabrication of hydrophobic surfaces on mechanically alloyed-Mg/HA/TiO{sub 2}/MgO bionanocomposites

Energy Technology Data Exchange (ETDEWEB)

Khalajabadi, Shahrouz Zamani [Medical Devices and Technology Group (MEDITEG), Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Abdul Kadir, Mohammed Rafiq, E-mail: rafiq@biomedical.utm.my [Medical Devices and Technology Group (MEDITEG), Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Izman, Sudin; Mohd Yusop, Mohd Zamri [Department of Materials, Manufacturing and Industrial Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia)

2015-01-01

Highlights: • Mg/HA/TiO{sub 2}-based nanocomposite was produced using mechanical alloying. • The hydrophobic surface coverage was fabricated on the mechanical alloyed samples by annealing. • The morphological characteristics, phase evolution and wettability of nanocomposites and the hydrophobic surface coverage were investigated. • The activation energies and reaction kinetic of the powder mixture of nanocomposites were calculated. - Abstract: The effect of mechanical alloying and post-annealing on the phase evolution, microstructure, wettability and thermal stability of Mg–HA–TiO{sub 2}–MgO composites was investigated in this study. Phase evolution and microstructure analysis were performed using X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and atomic force microscopy, as well as the wettability determined by contact angle measurements with SBF. The 16-h mechanical alloying resulted in the formation of MgTiO{sub 3}, CaTiO{sub 3}, Mg{sub 3}(PO{sub 4}){sub 2} and Mg(OH){sub 2} phases and a decrease in wettability of the nanocomposites. A hydrophobic film with hierarchical structures comprising nanoflakes of MgTiO{sub 3}, nano-cuboids of CaTiO{sub 3}, microspheres of Mg{sub 3}(PO{sub 4}){sub 2} and Mg(OH){sub 2} was successfully constructed on the surface of the Mg-based nanocomposites substrates as a result of the post-annealing process. After 1-h annealing at 630 °C, the synthesized hydrophobic surface on the nanocomposite substrates decreased the wettability, as the 8-h-mechanically alloyed samples exhibited a contact angle close to 93°. The formation activation energies and reaction kinetics of the powder mixture were investigated using differential thermal analysis and thermal gravimetric analysis. The released heat, weight loss percentage and reaction kinetics increased, while the formation activation energies of the exothermic reactions decreased following an increase in the milling time.

Synthesis of Doped and non-Doped Nano MgO Ceramic Membranes

Directory of Open Access Journals (Sweden)

Shiraz Labib

2013-12-01

Full Text Available Doped and non-doped MgO coated thin films on alumina substrates were prepared using a chelating sol-gel method under controlled conditions to prepare nanomaterials with unprecedented properties. The effect of doping of ZnO on thermal, surface and structural properties was investigated using DTA-TG, BET and XRD respectively. Also microstructural studies and coating thickness measurements of MgO thin film were conducted using SEM. An increase in the thermal stability of MgO with increasing ZnO doping percent was observed. The increase of ZnO doping percent showed a marked decrease in the average particle size of MgO powder as a result of the replacement of some Mg2+ by Zn2+ which has similar ionic radius as Mg2+. This decrease in particle size of MgO was also related to the decrease of the degree of MgO crystalinity. The increase of ZnO doping also showed a marked decrease in coating thickness values of the prepared membranes. This decrease was related to the  mechanism of ZnO doping into a MgO crystal lattice.

First-principle Calculations of Mechanical Properties of Al2Cu, Al2CuMg and MgZn2 Intermetallics in High Strength Aluminum Alloys

Directory of Open Access Journals (Sweden)

LIAO Fei

2016-12-01

Full Text Available Structural stabilities, mechanical properties and electronic structures of Al2Cu, Al2CuMg and MgZn2 intermetallics in Al-Zn-Mg-Cu aluminum alloys were determined from the first-principle calculations by VASP based on the density functional theory. The results show that the cohesive energy (Ecoh decreases in the order MgZn2 > Al2CuMg > Al2Cu, whereas the formation enthalpy (ΔH decreases in the order MgZn2 > Al2Cu > Al2CuMg. Al2Cu can act as a strengthening phase for its ductile and high Young's modulus. The Al2CuMg phase exhibits elastic anisotropy and may act as a crack initiation point. MgZn2 has good plasticity and low melting point, which is the main strengthening phase in the Al-Zn-Mg-Cu aluminum alloys. Metallic bonding mode coexists with a fractional ionic interaction in Al2Cu, Al2CuMg and MgZn2, and that improves the structural stability. In order to improve the alloys' performance further, the generation of MgZn2 phase should be promoted by increasing Zn content while Mg and Cu contents are decreased properly.

Mg concentration profile and its control in the low temperature grown Mg-doped GaN epilayer

Science.gov (United States)

Liu, S. T.; Yang, J.; Zhao, D. G.; Jiang, D. S.; Liang, F.; Chen, P.; Zhu, J. J.; Liu, Z. S.; Liu, W.; Xing, Y.; Zhang, L. Q.; Wang, W. J.; Li, M.; Zhang, Y. T.; Du, G. T.

2018-01-01

In this work, the Cp2Mg flux and growth pressure influence to Mg doping concentration and depth profiles is studied. From the SIMS measurement we found that a transition layer exists at the bottom region of the layer in which the Mg doping concentration changes gradually. The thickness of transition layer decreases with the increases of Mg doping concentration. Through analysis, we found that this is caused by Ga memory effect which the Ga atoms stay residual in MOCVD system will react with Mg source, leading a transition layer formation and improve the growth rate. And the Ga memory effect can be well suppressed by increasing Mg doping concentration and growth pressure and thus get a steep Mg doping at the bottom region of p type layer.

Hydriding and dehydriding rates of Mg, Mg-10TaF5, and Mg-10NbF5 prepared via reactive mechanical grinding

Science.gov (United States)

Song, Myoung Youp; Kwak, Young Jun; Lee, Seong Ho; Park, Hye Ryoung

2015-01-01

In this work, TaF5 and NbF5 were chosen as additives to enhance the hydriding and dehydriding rates of Mg. Mg, Mg-10TaF5, and Mg-10NbF5 samples were prepared by reactive mechanical grinding. The hydriding and dehydriding properties of the samples were then examined. Mg-10TaF5 had the largest amount of hydrogen absorbed for 30 min and the highest initial dehydriding rate after incubation period, followed in order by Mg-10NbF5, and Mg. At 593 K under 12 bar H2 at the first cycle, Mg-10TaF5 absorbed 3.63 wt% H for 5 min and 4.53 wt% H for 30 min. At 593 K under 1.0 bar H2 at the first cycle, Mg-10TaF5 desorbed 0 wt% H for 2.5 min, 0.59 wt% H for 5 min, 3.42 wt% H for 30 min, and 4.24 wt% H for 60 min. The reactive mechanical grinding of Mg with TaF5 or NbF5 is believed to have facilitated the nucleation and to have decreased the diffusion distances of hydrogen atoms. These two effects are believed to have increased the hydriding and dehydriding rates of Mg. The MgF2 and Ta2H formed in Mg-10TaF5, and the MgF2, NbH2, and NbF3 formed in Mg-10NbF5 are considered to have enhanced both of these effects.

Precipitate evolution in underaged Al-Mg-Si alloy during thermal cycling between 25 deg. C and 65 deg. C

International Nuclear Information System (INIS)

Uan, J.-Y.; Cho, C.-Y.; Chen, Z.-M.; Lin, J.-K.

2006-01-01

The evolution of metastable precipitates and the aging response in underaged Al-Mg-Si alloy during environmental temperature cycling was investigated using transmission electron microscopy (TEM) and hardness tests. After the alloy underwent thermal cycling between 25 deg. C and 65 deg. C, the hardness tests revealed that hardness decreased slightly, rather than following a concave downward curve, with the cycle times. Needle-shaped G.P. zones transformed during the environmental thermal cycling. The fraction of the zones declined sharply from almost 100% to only approximately 10% after 90 cycles, accompanied by an increase in the fraction of lath-shaped precipitates and the formation of β'' precipitates in the matrix. The precipitate developed with the 25-65 deg. C cycling time as follows: needle-shaped G.P. zones → lath-shaped ppt + β'' ppt + needle-shaped G.P. zones → lath-shaped ppt + β'' ppt + rod-shaped ppt + needle-shaped G.P. zones. Therefore, three or four precipitates coexisted in the underaged alloy following prolonged cycling. The formation of a limited number of β'' precipitates and the presence of a rod-shaped phase in the alloy during environmental temperature cycling reduced the hardness as the cycle time increases

MgB2 and Mg1-xAlxB2 single crystals: high pressure growth and physical properties

International Nuclear Information System (INIS)

Karpinski, J.; Kazakov, S.M.; Jun, J.; Zhigadlo, N.D.; Angst, M.; Puzniak, R.; Wisniewski, A.

2004-01-01

Single crystals of MgB 2 have been grown with a high pressure cubic anvil technique. They grow via the peritectic decomposition of the MgNB 9 ternary nitride. The crystals are of a size up to 2 x 1 x 0.1 mm 3 with a weight up to 230 μg. Typically they have transition temperatures between 38 and 38.6 K with a width of 0.3-0.5 K. Investigations of the P-T phase diagram prove that the MgB 2 phase is stable at least up to 2190 deg. C at high hydrostatic pressure in the presence of Mg vapor under high pressure. Substitution of aluminum for magnesium in single crystals leads to stepwise decrease of T c . This indicates a possible appearance of superstructures or phases with different T c 's. The upper critical field decreases with Al doping

Effects of limestone, N, K and Mg fertilizers on Mg absorption by oats and barley

Energy Technology Data Exchange (ETDEWEB)

Alston, A M

1966-01-01

Oats grown in a pot experiment on two sandy loams were sampled at four stages of growth. Neither KCl nor MgSO/sub 4/. 7H/sub 2/O had any effect on yield but % Mg and total Mg uptake were consistently decreased by applying K and increased by applying Mg. Ca(NO/sub 3/)/sub 2/ increased % Mg more than did (NH/sub 4/)/sub 2/SO/sub 4/, but yield and total Mg uptake were higher where (NH/sub 4/)/sub 2/SO/sub 4/ was applied. The effects of fertilizers were similar on both soils. The effects of applying (NH/sub 4/)/sub 2/SO/sub 4/ and NaNO/sub 2/ to the soil on % Mg in barley were compared in a field experiment on an acid loam to which several rates of limestone had been applied. Treatments had no effect on the % Mg in grain or straw at maturity. At four earlier stages of growth (NH/sub 4/)/sub 2/SO)/sub 4/ increased % Mg in the plants more than did NaNO/sub 2/. Limestone slightly increased % Mg. Nitrification of NH/sub 4/ in the soil was rapid.

Recent water quality trends in a typical semi-arid river with a sharp decrease in streamflow and construction of sewage treatment plants

Science.gov (United States)

Cheng, Peng; Li, Xuyong; Su, Jingjun; Hao, Shaonan

2018-01-01

Identification of the interactive responses of water quantity and quality to changes in nature and human stressors is important for the effective management of water resources. Many studies have been conducted to determine the influence of these stressors on river discharge and water quality. However, there is little information about whether sewage treatment plants can improve water quality in a region where river streamflow has decreased sharply. In this study, a seasonal trend decomposition method was used to analyze long-term (1996-2015) and seasonal trends in the streamflow and water quality of the Guanting Reservoir Basin, which is located in a semi-arid region of China. The results showed that the streamflow in the Guanting Reservoir Basin decreased sharply from 1996-2000 due to precipitation change and human activities (human use and reservoir regulation), while the streamflow decline over the longer period of time (1996-2015) could be attributed to human activities. During the same time, the river water quality improved significantly, having a positive relationship with the capacity of wastewater treatment facilities. The water quality in the Guanting Reservoir showed a deferred response to the reduced external loading, due to internal loading from sediments. These results implied that for rivers in which streamflow has declined sharply, the water quality could be improved significantly by actions to control water pollution control. This study not only provides useful information for water resource management in the Guanting Reservoir Basin, but also supports the implementation of water pollution control measures in other rivers with a sharp decline in streamflow.

Influences of the quantity of Mg2Sn phase on the corrosion behavior of Mg-7Sn magnesium alloy

International Nuclear Information System (INIS)

Liu Xianbin; Shan Dayong; Song Yingwei; Chen Rongshi; Han Enhou

2011-01-01

The influence of the quantity of the Mg 2 Sn phase on the corrosion behavior of different solution temperature treated Mg-7Sn magnesium alloy has been investigated by electrochemical measurements, scanning electron microscope (SEM) observation, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. With the increase of solution temperature, the quantity of Mg 2 Sn phase decreased and the tin concentration of matrix increased. The dissolved tin in Mg matrix took part in the film formation and the constituent of film was magnesium oxide and stannic oxide. The corrosion mode and corrosion rate were associated with the quantity of Mg 2 Sn phases and tin concentration of the matrix. If most of tin was present as Mg 2 Sn, the corrosion mode was pitting corrosion and it accelerated the corrosion rate. If most of tin was dissolved in matrix, the corrosion mode was filiform corrosion and it decreased the corrosion rate. The experiment evidences demonstrated that the corrosion resistance can be improved by increasing the tin concentration of matrix and the lowest corrosion rate was observed for sample solution treated at 540 o C.

Consideration about the contamination decreasing method of a crystalline lens in head CT

International Nuclear Information System (INIS)

Yamazaki, Shoichi; Matsueda, Katsuhiro; Matsumura, Mitsumi

2002-01-01

It is effective as a method for reducing the dose of a crystalline lens when enforcing Head CT to change the height of a bed, or it inquired. As a result of measuring, the dose of a crystalline lens became a low value sharply, when the quantity of a bed was moved to the up position. When a problem does not arise in diagnosis, the dose of a crystalline lens can be decreased by inspecting in the upper part as much as possible. As a method of reducing the dose of a crystalline lens, it is very useful. (author)

In-situ thermal analysis and macroscopical characterization of Mg-xCa and Mg-0.5Ca-xZn alloy systems

Energy Technology Data Exchange (ETDEWEB)

Farahany, Saeed [Department of Materials Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Bakhsheshi-Rad, Hamid Reza, E-mail: Rezabakhsheshi@gmail.com [Department of Materials Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Idris, Mohd Hasbullah [Department of Materials Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Abdul Kadir, Mohammed Rafiq [Medical Implants Technology Group, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Department of Biomechanics and Biomedical Materials, Faculty of Biomedical Engineering and Health Sciences, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Lotfabadi, Amir Fereidouni [Department of Manufacturing and Industrial Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Ourdjini, Ali [Department of Materials Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia)

2012-01-10

Highlights: Black-Right-Pointing-Pointer The effect of Ca and Zn addition on Mg-Ca and Mg-Ca-Zn were investigated. Black-Right-Pointing-Pointer Ca and Zn addition decreased solid fraction at coherency point. Black-Right-Pointing-Pointer T{sub N}-T{sub DCP} increased by adding Ca and Zn in Mg-Ca and Mg-Ca-Zn, respectively. Black-Right-Pointing-Pointer Three reactions were detected when Zn/Ca atomic ratio less than 1.25 in Mg-Ca-Zn. Black-Right-Pointing-Pointer A new peak Mg{sub 51}Zn{sub 20} was identified in Mg-0.5Ca-9Zn in addition of other peaks. - Abstract: This research described the identification phases by thermal analysis and microscopy inspection of Mg-xCa and Mg-0.5%Ca-xZn alloys that were solidified at slow cooling rate. Analysis of cooling curve after Ca addition shows the evolution of the Mg{sub 2}Ca intermetallic phase at around 520 Degree-Sign C in addition to {alpha}-Mg phase. First derivative curves of alloys after the addition of Zn to Mg-0.5Ca alloy reveals three peaks related to {alpha}-Mg, Mg{sub 2}Ca and Ca{sub 2}Mg{sub 6}Zn{sub 3} for alloys that have Zn/Ca atomic ratio less than 1.23. The peak of Mg{sub 2}Ca reaction on the first derivative curves disappeared for alloys containing Zn/Ca ratio more than 1.23. A new peak was also observed at 330 Degree-Sign C for Mg-0.5Ca-9Zn which was identified as Mg{sub 51}Zn{sub 20}. Solid fraction at coherency point decreased with increasing Ca and Zn elements. However, coherency time and difference between the nucleation and coherency temperatures (T{sub N}-T{sub DCP}) increased by adding Ca and Zn in Mg-Ca and Mg-Ca-Zn systems.

Methyl gallate from Acer barbinerve decreases melanin synthesis in Mel-Ab cells.

Science.gov (United States)

Kim, In Wook; jeong, Hyo-Soon; Kim, Jin Kyu; Lee, Jin-Koo; Kim, Hak Rim; Yun, Hye-Young; Baek, Kwang Jin; Kwon, Nyoun Soo; Park, Kyoung-Chan; Kim, Dong-Seok

2015-01-01

Methyl gallate (MG) was isolated from the bark of Acer barbinerve, which has traditionally been used in Oriental medicine. In the present study, we examined the effects of MG on melanin synthesis in Mel-Ab melanocyte cells. MG decreased melanin pigmentation in a concentration-dependent manner, but did not directly inhibit tyrosinase activity. Further analysis showed that MG had no effect on extracellular signal-regulated kinase (ERK) activation, but induced phosphorylation of glycogen synthase kinase (GSK)3β, which is known to increase β-catenin accumulation. Accordingly, the β-catenin level was increased by MG. However, a specific GSK3β inhibitor did not rescue the MG-induced inhibition of melanogenesis. Additionally, MG decreased the protein expression of microphthalmia-associated transcription factor (MITF) and tyrosinase, which regulate melanin synthesis. Based on these results, we conclude that MG inhibits melanogenesis by decreasing the expression of MITF and tyrosinase.

Structural and transport properties of Sn-Mg alloys

International Nuclear Information System (INIS)

Meydaneri, F.; Saatci, E.; Oezdemir, M.; Ari, M.; Durmus, S.

2010-01-01

The structural and temperature dependence transport of Sn-Mg alloys have been investigated for five different samples (Pure Sn, Sn-1.0 wt % Mg , Sn-2.0 wt % Mg , Sn-6.0 wt.% Mg and Pure Mg). Scanning Electron Microscopy (SEM), x-ray diffraction (XRD) and Energy Dispersive x-ray Analysis (EDX) measurements were carried out in order to clarify the structural properties of the samples. It has been found that, the samples have tetragonal crystal symmetry except the pure Mg which has hexagonal crystal symmetry. The cell parameters decrease slightly with addition of Mg element. The SEM micrographs of the samples show that, the samples have smooth surfaces with clear grain boundary. There is no crack, porosity or defects on the surfaces. The electrical resistivity of the samples increases almost linearly with the increasing temperature, which were measured by four-point probe technique. The thermal conductivity values are in between 0.60-1.00 W/Km, which are decrease slightly with temperature and increase with composition of Mg. The thermal conductivity values of the alloys are in between the values of the pure samples. Thermal conductivity results of the alloys have been compared with available other studies and a good agreement has been seen between the results. In addition, the temperature coefficients of electrical resistivity and thermal conductivity have been determined, which are independent with the compositions of alloying elements

Sharply rising prevalence of HIV infection in Bali: a critical assessment of the surveillance data.

Science.gov (United States)

Januraga, P P; Wulandari, L P L; Muliawan, P; Sawitri, S; Causer, L; Wirawan, D N; Kaldor, J M

2013-08-01

This study critically examines serological survey data for HIV infection in selected populations in Bali, Indonesia. Sero-survey data reported by the Bali Health Office between 2000 and 2010 were collated, and provincial health staff were interviewed to gain a detailed understanding of survey methods. Analysis of time series restricted to districts that have used the same sampling methods and sites each year indicates that there has been a steady decline in HIV prevalence among prisoners, from 18.7% in 2000 to 4.3% in 2010. In contrast, HIV prevalence among women engaged in sex work increased sharply: from 0.62% in 2000 to 20.2% in 2010 (brothel based), and from 0% in 2000 to 7.2% in 2010 (non-brothel based). The highest prevalence was recorded among people who injected drugs. Recent surveys of gay men and transvestites also found high prevalences, at 18.7% and 40.9%, respectively. Review of the methodology used in the surveys identified inconsistencies in the sampling technique, sample numbers and sites over time, and incomplete recording of individual information about survey participants. Attention to methodological aspects and incorporation of additional information on behavioural factors will ensure that the surveillance system is in the best position to support prevention activities.

Influence of Microstructure on Corrosion Property of Mg-Al-Zn Alloy

International Nuclear Information System (INIS)

Lee, Jeong Ja; Na, Seung Chan; Yang, Won Seong; Hwang, WoonSuk; Jang, Si Sung; Yoo, Hwang Ryong

2006-01-01

Influence of microstructure on the corrosion property of Mg-Al-Zn Alloy was investigated using potentiodynamic polarization experiments, galvanic coupling experiments, and scanning electron microscopy in sodium chloride solutions. Pitting was the mot common form of attack in chloride solution, and filiform corrosion was also occurred in AZ91D-T4 alloy. On the contrary, filiform attack in the bulk matrix was predominant corrosion form in AZ91D-T6 alloy, and the number and size of pit were decreased than those of AZ91D-T4 alloy. Galvanic coupling effect between Mg 17 Al 12 and matrix was existed, but the propagation of galvanic corrosion was localized only near the Mg 17 Al 12 phase in AZ91D-6T alloy. The corrosion resistance of Mg-Al matrix increased with decreasing Al content in the matrix. And, it could be regarded that Al content in the matrix is decreased by precipitation of Mg 17 Al 12 curing the aging treatment and it decreases the anodic reaction rate of the matrix and galvanic effect in AZ91D-T6 alloy. It could be considered that the composition and macrostructure of surface protective layer would be varied by precipitation of Mg 17 Al 12 and subsequent decreasing of Al content in the matrix. And it would contribute the corrosion resistance of AZ91D-T6 aging alloy

Powder metallurgical low-modulus Ti-Mg alloys for biomedical applications.

Science.gov (United States)

Liu, Yong; Li, Kaiyang; Luo, Tao; Song, Min; Wu, Hong; Xiao, Jian; Tan, Yanni; Cheng, Ming; Chen, Bing; Niu, Xinrui; Hu, Rong; Li, Xiaohui; Tang, Huiping

2015-11-01

In this work, powder metallurgical (PM) Ti-Mg alloys were prepared using combined techniques of mechanical alloying and spark plasma sintering. The alloys mainly consist of super saturations of Mg in Ti matrix, and some laminar structured Ti- and Mg-rich phases. The PM Ti-Mg alloys contain a homogeneous mixtures of nanocrystalline Mg and Ti phases. The novel microstructures result in unconventional mechanical and biological properties. It has been shown that the PM Ti-Mg alloys have a much lower compression modulus (36-50GPa) compared to other Ti alloys, but still remain a very high compressive strength (1500-1800MPa). In addition, the PM Ti-Mg alloys show good biocompatibility and bioactivity. Mg can dissolve in the simulated body fluids, and induce the formation of the calcium phosphate layer. The compression modulus of PM Ti-Mg alloys decreases with the amount of Mg, while the bioactivity increases. Although the corrosion resistance of Ti-Mg alloys decreases with the content of Mg, the alloys still show good stability in simulated body fluid under electrochemical conditions. The indirect and direct cytotoxicity results show that PM Ti-Mg alloys have a good biocompatibility to NIH-3T3 cells. Therefore, the PM Ti-Mg alloys are promising candidates in biomedical applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Melting relations in the MgO-MgSiO3 system up to 70 GPa

Science.gov (United States)

Ohnishi, Satoka; Kuwayama, Yasuhiro; Inoue, Toru

2017-06-01

Melting experiments in a binary system MgO-MgSiO3 were performed up to 70 GPa using a CO2 laser heated diamond anvil cell. The quenched samples were polished and analyzed by a dualbeam focused ion beam (FIB) and a field emission scanning electron microscope (FE-SEM), respectively. The liquidus phase and the eutectic composition were determined on the basis of textual and chemical analyses of sample cross sections. Our experimental results show that the eutectic composition is the Si/Mg molar ratio of 0.76 at 35 GPa and it decreases with increasing pressure. Above 45 GPa, it becomes relatively constant at about 0.64-0.65 Si/Mg molar ratio. Using our experimental data collected at a wide pressure range up to 70 GPa together with previous experimental data, we have constructed a thermodynamic model of the eutectic composition of the MgO-MgSiO3 system. The eutectic composition extrapolated to the pressure and temperature conditions at the base of the mantle is about 0.64 Si/Mg molar ratio. The modeled eutectic composition is quite consistent with a previous prediction from ab initio calculations (de Koker et al. in Earth Planet Sci Lett 361:58-63, 2013), suggesting that the simple assumption of a non-ideal regular solution model can well describe the melting relation of the MgO-MgSiO3 system at high pressure. Our results show that the liquidus phase changes from MgO-periclase to MgSiO3-bridgmanite at 35 GPa for the simplified pyrolite composition ( 0.7 Si/Mg molar ratio), while MgSiO3-bridgmanite is the liquidus phase at the entire lower mantle conditions for the chondritic composition ( 0.84 Si/Mg molar ratio).

Radiation-induced effects in MgO single crystal by 200 keV and 1 MeV Ni ion implantation

Energy Technology Data Exchange (ETDEWEB)

Takahashi, Ryohei; Nakai, Yoshihiro; Hamaguchi, Dai [Kyoto Inst. of Tech. (Japan); and others

1997-03-01

MgO(100) single crystals were implanted with 1.0 MeV and 200 keV Ni ions between 10{sup 15} and 10{sup 17} ions/cm{sup 2} at room temperature. Before and after thermal annealing the radiation damage and the lattice location of implanted Ni ions were analyzed by using Rutherford backscattering spectrometry with channeling and optical absorption measurements. For 1.0 MeV Ni ions, the disorder of Mg atoms increased slowly with ion dose near surface region, while it increased sharply and saturated with ion dose from 2x10{sup 16} ions/cm{sup 2} near ion range. The radiation damage was recovered and implanted Ni ions diffused to the whole of crystal and occupied substitutional positions after 1400degC annealing. For 200 keV Ni ions, the disorder of Mg atoms increased with dose near ion range and had a maximum at about 5x10{sup 16} ions/cm{sup 2}. This tendency agrees with the behavior of color centers obtained from optical measurements. For thermal annealing the radiation damage did not change during 500degC annealing, but the aggregate centers appeared after 300degC annealing. (author)

A study of stability of MgH{sub 2} in Mg-8at%Al alloy powder

Energy Technology Data Exchange (ETDEWEB)

Tanniru, Mahesh; Ebrahimi, Fereshteh [Materials Science and Engineering Department, University of Florida, Gainesville, FL 32611 (United States); Slattery, Darlene K. [Florida Solar Energy Center (FSEC), Cocoa, FL (United States)

2010-04-15

To investigate the effect of Al addition on the stability of magnesium hydride, the hydrogenation characteristics of a Mg-8at%Al alloy powder synthesized using the electrodeposition technique were evaluated. The characterization of the hydrogenation behavior within the 180 C-280 C temperature range and the subsequent microstructural analysis elucidated that the amount of Al present in the hydride decreased with increasing temperature. This observation suggests that Al has very low solubility in magnesium hydride but Al can be accommodated in MgH{sub 2} by processing under non-equilibrium conditions. Pressure-composition isotherms were developed at different temperatures for the Mg-Al powder as well as pure Mg powder. The results indicate that the enthalpy of formation was slightly lower for the Mg-8at%Al powder while the enthalpy of dissociation did not change. The absence of noticeable influence of Al addition on the stability of magnesium hydride is attributed to its lack of solubility. (author)

The role of Mg in the crystallization of monohydrocalcite

Science.gov (United States)

Rodriguez-Blanco, Juan Diego; Shaw, Samuel; Bots, Pieter; Roncal-Herrero, Teresa; Benning, Liane G.

2014-02-01

Monohydrocalcite is a member of the carbonate family which forms in Mg-rich environments at a wide range of Mg/Ca ratios Mg2+aq/Ca2+aq≥0.17stock solutions. However, its crystallite and particle size are inversely proportional to these parameters. At high supersaturations (SIMHC = 3.89) nanometer-sized single crystals of monohydrocalcite form, while at low values (SIMHC = 2.43) the process leads to low-angle branching spherulites. Many carbonates produced during biomineralization form at similar conditions to most synthetic monohydrocalcites, and thus we hypothesize that some calcite or aragonite deposits found in the geologic record that have formed at high Mg/Ca ratios could be secondary in origin and may have originally formed via a metastable monohydrocalcite intermediate. High-Mg monohydrocalcite (χMgCO3 > 0.06) consists of individual nanometer-sized crystals (500 °C (Fig. 9b). Such high-Mg monohydrocalcites are uncommon in nature, but can be synthesized in the laboratory at high initial supersaturation levels (SI > 3.25). Low-Mg monohydrocalcite (χMgCO3 bonded to Mg, so it fully dehydrates at low temperatures (150-200 °C). They have the same composition as natural monohydrocalcites reported in the literature, and can be synthesized in the laboratory at lower supersaturation levels (SI relationships. Firstly, our on-line experiment shows an increase in nanocrystal sizes during the secondary crystallization of monohydrocalcite, which is coupled with a significant decrease in χMgCO3 (from ˜0.26 to ˜0.065). This corresponds to the transition from high- to low-Mg monohydrocalcite, suggesting that the former would be metastable and rapidly transforming to the latter, possibly triggered by the removal of Mg from aqueous solution. Secondly, Davis et al. (2000) determined that the solubility of Mg-calcite (Ca1-xMgxCO3; x = 0-0.20) varies by approximately half an order of magnitude depending on the Mg content of the solid (Ksp = 10-8.0-10-8.5). A similar

Structural and electronic properties of Mg and Mg-Nb co-doped TiO2 (101) anatase surface

International Nuclear Information System (INIS)

Sasani, Alireza; Baktash, Ardeshir; Mirabbaszadeh, Kavoos; Khoshnevisan, Bahram

2016-01-01

Highlights: • Formation energy of Mg and Mg-Nb co-doped TiO_2 anatase surface (101) is studied. • Effect of Mg defect to the TiO_2 anatase (101) surface and bond length distribution of the surface is studied and it is shown that Mg defects tend to stay far from each other. • Effect of Mg and Nb to the bond length distribution of the surface studied and it is shown that these defects tend to stay close to each other. • Effects of Mg and Mg-Nb defects on DSSCs using TiO_2 anatase hosting these defects are studied. - Abstract: In this paper, by using density functional theory, Mg and Nb-Mg co-doping of TiO_2 anatase (101) surfaces are studied. By studying the formation energy of the defects and the bond length distribution of the surface, it is shown that Mg defects tend to stay as far as possible to induce least possible lattice distortion while Nb and Mg defects stay close to each other to cause less stress to the surface. By investigating band structure of the surface and changes stemmed from the defects, potential effects of Mg and Mg-Nb co-doping of TiO_2 surface on dye-sensitized solar cells are investigated. In this study, it is shown that the Nb-Mg co-doping could increase J_S_C of the surface while slightly decreasing V_O_C compared to Mg doped surface, which might result in an increase in efficiency of the DSSCs compared to Nb or Mg doped surfaces.

Influence of particle size of Mg powder on the microstructure and critical currents of in situ powder-in-tube processed MgB_2 wires

International Nuclear Information System (INIS)

Kumakura, Hiroaki; Ye, Shujun; Matsumoto, Akiyoshi; Nitta, Ryuji

2016-01-01

We fabricated in situ powder-in-tube(PIT) MgB_2 wires using three kinds of Mg powders with particle size of ∼45 μm, ∼150 μm and 212∼600 μm. Mg particles were elongated to filamentary structure in the wires during cold drawing process. Especially, long Mg filamentary structure was obtained for large Mg particle size of 212∼600 μm. Critical current density, J_c, increased with increasing Mg particle size for 1 mm diameter wires. This is due to the development of filamentary structure of high density MgB_2 superconducting layer along the wires. This MgB_2 structure is similar to that of the internal Mg diffusion (IMD) processed MgB_2 wires. However, J_c of the wires fabricated with 212∼600 μm Mg particle size decreased and the scattering of J_c increased with decreasing wire diameter, while the J_c of the wires with ∼45 μm Mg particle was almost independent of the wire diameter. The cross sectional area reduction of the Mg particles during the wire drawing is smaller than that of the wire. When using large size Mg particle, the number of Mg filaments in the wire cross section is small. These two facts statistically lead to the larger scattering of Mg areal fraction in the wire cross section with proceeding of wire drawing process, resulting in smaller volume fraction of MgB_2 in the wire and lower J_c with larger scattering along the wire. SiC nano powder addition is effective in increasing J_c for all Mg particle sizes. (author)

Mg,Ca-ATPase activity under irradiation

International Nuclear Information System (INIS)

Ladutin, V.V.; Orlova, V.V.; Lob, P.A.; Gerasiminko, I.V.; Mack, E.I.

2003-01-01

Full text: The influence of different doses irradiation at the Mg,Ca-ATPase activity at the rat brain has been investigated. The analyses were made at the apparatus of LKB and Carl-Ceis-Jena firm with help of reagents of Sigma and Boehringer firm. Rats decapitated after 1, 3, 6, 24 and 48 h after action of irradiation. Dose 0.206 C/kg. Erythrocytes. 1 and 3h after irradiation influence- decrease of Mg,Ca-ATPase activity to 86-87% relatively control level, 24 and 48 h - increase of activity to the control level. Dose 0.312 C/kg. Large hemispheres. 1h - decrease of ATPase activity to 90% relatively control, 3h - increase to control level, 24h - fall to 86%, after 48h small increase to 93% relatively control. Dose 9.287 C/kg. Large hemispheres. 1h - sharp fall of Mg, Ca-ATPase activity to 67 % relatively control, increase of activity to 96% after 3h and sharp fall of activity to 64% 6h after action of irradiation. Dose 9.287 C/kg. Cerebellum. 1h - sharp decrease of ATPase activity to 80%. After 3h -sharp increase to 160% relatively control level and sharp fall of ATPase activity to 47% relatively control after 6h. The mechanism of radiation pathology of active ion transport has been discussed

Preparation and characterisation of Os doped MgB{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Grivel, J.-C., E-mail: jean@dtu.dk; Namazkar, S.; Alexiou, A.; Holte, O.J.

2014-12-15

Highlights: • Polycrystalline osmium doped MgB{sub 2} samples were prepared by solid state route. • Up to 1 at.% Mg can be replaced by Os in the MgB{sub 2} lattice. • T{sub c} decreases at a rate of 2.1 K/at.% Os upon doping. - Abstract: Polycrystalline samples with Mg{sub 1−x}Os{sub x}B{sub 2.04} nominal stoichiometry were made by reacting elemental powders at 800 °C under argon atmosphere. Based on XRD diffraction patterns, EDS analysis and magnetisation measurements, it is found that Os can replace up to about 1 at.% Mg in the MgB{sub 2} lattice. Beyond this doping level, unreacted Os and Mg-rich Mg–Os impurity phases are formed. The a-axis parameter contracts upon doping while the superconducting transition temperature decreases at a rate of 2.1 K/at.% Os substitution. At 10 K, Os doping induces an improvement of the normalised critical current density under applied magnetic fields in excess of 0.5 T, indicating a modest enhancement of flux pinning in this range.

Effect of solution concentration on sealing treatment of Mg-Al hydrotalcite film on AZ91D Mg alloy

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Qiangsheng Dong

2017-09-01

Full Text Available Cerium-based sealing treatment was developed for Mg-Al hydrotalcite film on AZ91D Mg alloy, and the influence of cerium salt solution was investigated to modify the surface integrity and corrosion resistance. Scanning electron microscope (SEM and X-ray diffraction (XRD measurements were carried out to analyze the surface morphology and phase composition. The corrosion resistance of Mg-Al hydrotalcite film after sealing treatment was evaluated by the polarization curve and electrochemical impedance spectroscopy (EIS tests. The results showed that lower concentration of Ce-containing solution was beneficial to seal the micro-cracks on Mg-Al hydrotalcite film, and improve the surface integrity and corrosion resistance; higher concentration of Ce-containing solution could seal fewer micro-cracks, and the corrosion resistance was decreased owing to the disintegration of Mg-Al hydrotalcite film.

Structural and electronic properties of Mg and Mg-Nb co-doped TiO2 (101) anatase surface

Energy Technology Data Exchange (ETDEWEB)

Sasani, Alireza [Department of Science, Karaj Islamic Azad University, Karaj, Alborz, P.O. Box 31485-313 (Iran, Islamic Republic of); Baktash, Ardeshir [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Mirabbaszadeh, Kavoos, E-mail: mirabbas@aut.ac.ir [Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, P. O. Box 15875-4413 (Iran, Islamic Republic of); Khoshnevisan, Bahram [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of)

2016-10-30

Highlights: • Formation energy of Mg and Mg-Nb co-doped TiO{sub 2} anatase surface (101) is studied. • Effect of Mg defect to the TiO{sub 2} anatase (101) surface and bond length distribution of the surface is studied and it is shown that Mg defects tend to stay far from each other. • Effect of Mg and Nb to the bond length distribution of the surface studied and it is shown that these defects tend to stay close to each other. • Effects of Mg and Mg-Nb defects on DSSCs using TiO{sub 2} anatase hosting these defects are studied. - Abstract: In this paper, by using density functional theory, Mg and Nb-Mg co-doping of TiO{sub 2} anatase (101) surfaces are studied. By studying the formation energy of the defects and the bond length distribution of the surface, it is shown that Mg defects tend to stay as far as possible to induce least possible lattice distortion while Nb and Mg defects stay close to each other to cause less stress to the surface. By investigating band structure of the surface and changes stemmed from the defects, potential effects of Mg and Mg-Nb co-doping of TiO{sub 2} surface on dye-sensitized solar cells are investigated. In this study, it is shown that the Nb-Mg co-doping could increase J{sub SC} of the surface while slightly decreasing V{sub OC} compared to Mg doped surface, which might result in an increase in efficiency of the DSSCs compared to Nb or Mg doped surfaces.

Mg-containing hydroxyapatite coatings on Ti-6Al-4V alloy for dental materials

Science.gov (United States)

Yu, Ji-Min; Choe, Han-Cheol

2018-02-01

In this study, Mg-containing hydroxyapatite coatings on Ti-6A1-4 V alloy for dental materials were researched using various experimental instruments. Plasma electrolytic oxidation (PEO) was performed in electrolytes containing Mg (symbols of specimens: CaP, 5M%, 10M%, and 20M%) at 280 V for 3 min. The electrolyte used for PEO was produced by mixing Ca(CH3COO)2·H2O, C3H7NaCaO6P, and MgCl2·6H2O. The phases and composition of the oxide films were evaluated by X-ray diffraction and field-emission scanning electron microscopy with energy dispersive X-ray spectrometry. The irregularity of the surface, pore size, and number of pores decreased as the Mg concentration increased. The ratio of the areas occupied and not occupied by pores decreased as the Mg concentration increased, with the numbers of both large and small pores decreasing with increasing Mg concentration. The number of particles on the internal surfaces of pores was increased as the Mg content increased. Mg content of all samples containing Mg ions showed higher in the pore outside than that of pore inside, whereas the Ca content was higher inside the pores. The P content of samples with the addition of Mg ions showed higher values inside the pores than outside. The Ca/P and [Mg + Ca]/P molar ratios in the PEO films decreased with Mg content. The crystallite size of anatase was increased with increasing Mg concentration in the solution.

Refinement of Mg2Si reinforcement in a commercial Al–20%Mg2Si in-situ composite with bismuth, antimony and strontium

International Nuclear Information System (INIS)

Nordin, Nur Azmah; Farahany, Saeed; Ourdjini, Ali; Abu Bakar, Tuty Asma; Hamzah, Esah

2013-01-01

Refinement by addition elements of Al–Mg 2 Si alloys is known to result in a change of primary Mg 2 Si morphology. In this paper, the effects of Bi, Sb and Sr on the characteristic parameters of Al–20%Mg 2 Si in-situ composite have been investigated by computer aided cooling curve thermal analysis and microstructural inspection. Size, density and aspect ratio measurements showed that additions of 0.4 wt.% Bi, 0.8 wt.% Sb and 0.01 wt.% Sr refined the Mg 2 Si reinforcement. Exceeding these concentrations, however, resulted in coarsening of Mg 2 Si particles with no change in the morphology. The results also showed that addition elements caused a decrease in the nucleation and growth temperatures of Mg 2 Si particles. The refining effect of Bi, Sb and Sr is likely to be related to the effect of oxide bifilms suspended in the composite melt as favored nucleation substrates for Mg 2 Si particles. - Highlight: • 0.4 wt.%, 0.8 wt.% and 0.01 wt.% is the optimum content for Bi, Sb and Sr addition. • Exceeding optimum concentration resulted in the coarsening of reinforcements. • Nucleation and growth temperatures decrease with addition of Bi, Sb and Sr. • The refining effect of Bi, Sb and Sr is likely to be related to the oxide bifilms

Mg co-ordination with potential carcinogenic molecule acrylamide: Spectroscopic, computational and cytotoxicity studies

Science.gov (United States)

Singh, Ranjana; Mishra, Vijay K.; Singh, Hemant K.; Sharma, Gunjan; Koch, Biplob; Singh, Bachcha; Singh, Ranjan K.

2018-03-01

Acrylamide (acr) is a potential toxic molecule produced in thermally processed food stuff. Acr-Mg complex has been synthesized chemically and characterized by spectroscopic techniques. The binding sites of acr with Mg were identified by experimental and computational methods. Both experimental and theoretical results suggest that Mg coordinated with the oxygen atom of Cdbnd O group of acr. In-vitro cytotoxicity studies revealed significant decrease in the toxic level of acr-Mg complex as compared to pure acr. The decrease in toxicity on complexation with Mg may be a useful step for future research to reduce the toxicity of acr.

Thermoluminescence studies of γ-irradiated ZnO:Mg"2"+ nanoparticles

International Nuclear Information System (INIS)

Pushpa, N.; Kokila, M.K.; Nagabhushana, K.R.

2016-01-01

Pure and Mg"2"+ doped ZnO nanoparticles are synthesized by solution combustion method. X-ray diffraction studies of the samples confirm hexagonal phase. Crystallite size is calculated using Scherer formula and found to be ∼30 nm for undoped ZnO and 34–38 nm for Mg"2"+ doped ZnO. A broad PL emission in the range 400–600 nm with peaks at 400, 450, 468, 483, 492, 517, 553 nm are observed in both pure and Mg"2"+ doped nanoparticles. Near band edge emission of ZnO is observed at 400 nm. The broad band emissions are due to surface defects. PL emission intensity is found to increase with Mg"2"+ concentration up to 1.5 mol% and then decreases due to concentration quenching. Samples are irradiated with γ-rays in a dose range 0.05–8 kGy. Gamma irradiation doesn’t affect PL properties. Undoped samples exhibit unstructured low intense TL glow with peak at 720 K. Whereas Mg"2"+ doped samples exhibit well structured TL glow curves with peak at ∼618 K. TL glow peak intensity of Mg"2"+ doped samples increases with Mg"2"+ concentration up to 2 mol%, thereafter decreases. TL curves of Mg"2"+ (2 mol%) doped ZnO exhibit two glows, a high intense peak at 618 K and a weak one with peak at ∼485 K. TL intensity of Mg"2"+ (2 mol%) doped ZnO samples increases with gamma dose up to 1 kGy and then decreases. Kinetic parameters of TL glows are calculated by deconvolution technique. Activation energy and frequency factor are found to be 1.5 eV and 3.38 × 10"1"1 s"−"1 respectively.

Decrease in oil prices: which consequences for the World economy and for France?

International Nuclear Information System (INIS)

Camatte, Hadrien; Darmet-Cucchiarini, Maxime; Gillet, Thomas; Masson, Emmanuelle; Meslin, Olivier; Padieu, Ysaline; Tavin, Alexandre

2016-04-01

Based of various statistics, this public publication first describes that, since summer 2014, oil price has been sharply decreasing (70 per cent) and keeping on decreasing due to a still abundant supply (with non conventional oil in the USA, and a still high production by OPEC countries) and a rather disappointing demand. It also outlines that production commitments stated by producers are still uncertain. This paper then notices that this oil price decrease could remain positive for World economy, but that some short term factors still impair these effects. This positive effect is indeed slow to appear in importing countries. Negative effects in exporting countries are emphasized by local economic policies. Moreover, there could be a transmission of this oil price decrease to the financial sphere, oil price decrease makes monetary policy more complex, and the USA are increasingly exposed to the energy sector activity. The third part shows that oil prices have positive effects on the French economy. They favour a wealth transfer from the rest of the world to the French economy, positively impacts companies margins and household purchase power on the short and medium terms, induces external effects as it also affects trade partners, and could result in an activity gain in the finance bill

The electrochemical characteristics of Mg2Ni nanocrystalline hydrogen storage alloy

International Nuclear Information System (INIS)

Zhang Ling; Zhou Xiaosong; Peng Shuming

2008-06-01

The nanocrystalline Mg 2 Ni materials were prepared by mechanical alloying. The cyclic voltametry results indicated that the potential of oxidation peak was shift as the scan rate increased and the absorption property of Mg 2 Ni prepared by mechanical alloying was increased even at ambient temperature. The absorption and desorption of hydrogen in Mg 2 Ni alloy were remarkably accelerated with the rising temperature. Small angel X-ray scattering results indicated that the Mg 2 Ni powder have 1-5 nm and 5-10 nm particle size distribution, which increased the acting sites of hydrogen absorption/desorption reaction and decreased the diffusion path of hydrogen desorption. It was induced to the enhanced performance of Mg 2 Ni nanocrystalline powder. The cycle life investigated results indicated that the activation property of Mg 2 Ni nanocrystal-line hydrogen storage alloy electrode was excellent, the capacitance maintenance ration was 66% after 200 cycles. The coating of epoxy resin on one side of the electrode had no effect on the activation property and the capacitance maintenance ration was better than the uncoating one. But the anode peak current value and the cathodic peak current value were decreased remarkably which indicated that the hydrogen absorption/desorption rate and the charge/discharge degree had decreased. (authors)

Effect of excess Mg and Excess Nb incorporation into the B-site of pyrochlore in the Pb-Mg-Nb-O system

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Mergen, A.

2002-12-01

Full Text Available In the Pb-Mg-Nb-O system, excess Mg and excess Nb incorporation into the B-site of PMN pyrochlore were investigated along the compositons of Pb1.83Mg0.29+xNb1.71-xO6.39-1.5x where x=0.1, 0.2, 0.3, 0.4, 0.522 and Pb1.83Mg0.29-xNb1.71+xO6.39+1.5x where x=0.1, 0.2, 0.29 respectively. Excess Mg incorporation led to the formation of perovskite and excess Nb resulted in formation of Pb2Nb2O7 monoclinic pyrochlore. The densities of the PMN pyrochlore-PMN perovskite mixtures decreased with an increase in Mg concentration. The relative permittivity of the mixtures increased with decreasing pyrochlore content. The effect of pyrochlore on the permittivity follows the Weiner’s mixture rule up to a pyrochlore content of 50 vol%.

Se investigó la incorporación en lugares B de pirocloro PMN de un exceso de Mg y un exceso de Nb. En el sistema Pb-Mg-Nb-O2 las composiciones analizadas fueron Pb1.83Mg0.29+xNb1.71-xO6.39-1.5x donde x=0.1, 0.2, 0.3, 0.4, 0.522 y en Pb1.83Mg0.29-xNb1.71+xO6.39+1.5x donde x= 0.1, 0.2,0.29. El exceso de Mg condujo a la formación de perovskita y el exceso de Nb resultó en la formación del pirocloro monolínico, Pb2Nb2O7. La densidad de la mezcla de PMN pirocloro-perovskita dismunuye con el aumento de la concentración de Mg. La permitividad dieléctrica de las mezclas aumenta con la disminución del contenido de pirocloro. El efecto del pirocloro sobre la permitividad sigue la regla de mezclas de Weiner hasta conenidos de pirocloro del 50%.

MgB{sub 2} superconductors for applications

Energy Technology Data Exchange (ETDEWEB)

Glowacki, B A; Majoros, M; Eisterer, M; Toenies, S; Weber, H W; Fukutomi, M; Komori, K; Togano, K

2003-05-01

The paper presents up to date results on MgB{sub 2} filamentary conductors and coated conductors from the point of view of their possible applications. Basic physical parameters of MgB{sub 2} compound relevant to conductor design are introduced. The correlation between the slope of the irreversibility line, critical temperature and critical current density is discussed with respect to the conductor performance and applicability. The possible origin of the observed anomalous decrease of ac susceptibility at 50 K in copper clad in situ powder-in-tube MgB{sub 2} wires is presented. Some numerical results on critical currents, thermal stability and ac losses of the MgB{sub 2} multifilamentary and coated conductors with magnetic cladding of their filaments are given.

Mechanical properties, corrosion, and biocompatibility of Mg-Zr-Sr-Dy alloys for biodegradable implant applications.

Science.gov (United States)

Ding, Yunfei; Lin, Jixing; Wen, Cuie; Zhang, Dongmei; Li, Yuncang

2017-11-28

This study investigates the microstructure, mechanical properties, corrosion behavior, and biocompatibility of magnesium (Mg)-based Mg1Zr2SrxDy (x = 0, 1, 1.63, 2.08 wt %) alloys for biodegradable implant applications. The corrosion behavior of the Mg-based alloys has been evaluated in simulated body fluid using an electrochemical technique and hydrogen evolution. The biocompatibility of the Mg-based alloys has been assessed using SaSO2 cells. Results indicate that the addition of Dy to Mg-Zr-Sr alloy showed a positive impact on the corrosion behavior and significantly decreased the degradation rates of the alloys. The degradation rate of Mg1Zr2Sr1.0Dy decreased from 17.61 to 12.50 mm year -1 of Mg1Zr2Sr2.08Dy based on the hydrogen evolution. The ultimate compressive strength decreased from 270.90 MPa for Mg1Zr2Sr1Dy to 236.71 MPa for Mg1Zr2Sr2.08Dy. An increase in the addition of Dy to the Mg-based alloys resulted in an increase in the volume fraction of the Mg 2 Dy phase, which mitigated the galvanic effect between the Mg 17 Sr 2 phase and the Mg matrix, and led to an increase in the corrosion resistance of the base alloy. The biocompatibility of the Mg-based alloys was enhanced with decreasing corrosion rates. Mg1Zr2Sr2.08Dy exhibited the lowest corrosion rate and the highest biocompatibility compared with the other Mg-based alloys. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.

Alterations of Mg2+ After Hemorrhagic Shock.

Science.gov (United States)

Lee, Mun-Young; Yang, Dong Kwon; Kim, Shang-Jin

2017-11-01

Hemorrhagic shock is generally characterized by hemodynamic instability with cellular hypoxia and diminishing cellular function, resulting from an imbalance between systemic oxygen delivery and consumption and redistribution of fluid and electrolytes. Magnesium (Mg) is the fourth most abundant cation overall and second most abundant intracellular cation in the body and an essential cofactor for the energy production and cellular metabolism. Data for blood total Mg (tMg; free-ionized, protein-bound, and anion-bound forms) and free Mg 2+ levels after a traumatic injury are inconsistent and only limited information is available on hemorrhagic effects on free Mg 2+ as the physiologically active form. The aim of this study was to determine changes in blood Mg 2+ and tMg after hemorrhage in rats identifying mechanism and origin of the changes in blood Mg 2+ . Hemorrhagic shock produced significant increases in blood Mg 2+ , plasma tMg, Na + , K + , Cl - , anion gap, partial pressures of oxygen, glucose, and blood urea nitrogen but significant decreases in RBC tMg, blood Ca 2+ , HCO 3 - , pH, partial pressures of carbon dioxide, hematocrit, hemoglobin, total cholesterol, and plasma/RBC ATP. During hemorrhagic shock, K + , anion gap, and BUN showed significant positive correlations with changes in blood Mg 2+ level, while Ca 2+ , pH, and T-CHO correlated to Mg 2+ in a negative manner. In conclusion, hemorrhagic shock induced an increase in both blood-free Mg 2+ and tMg, resulted from Mg 2+ efflux from metabolic damaged cell with acidosis and ATP depletion.

Concentration effect on inter-mineral equilibrium isotope fractionation: insights from Mg and Ca isotopic systems

Science.gov (United States)

Huang, F.; Wang, W.; Zhou, C.; Kang, J.; Wu, Z.

2017-12-01

Many naturally occurring minerals, such as carbonate, garnet, pyroxene, and feldspar, are solid solutions with large variations in chemical compositions. Such variations may affect mineral structures and modify the chemical bonding environment around atoms, which further impacts the equilibrium isotope fractionation factors among minerals. Here we investigated the effects of Mg content on equilibrium Mg and Ca isotope fractionation among carbonates and Ca content on equilibrium Ca isotope fractionation between orthopyroxene (opx) and clinopyroxene (cpx) using first-principles calculations. Our results show that the average Mg-O bond length increases with decreasing Mg/(Mg+Ca) in calcite when it is greater than 1/48[1] and the average Ca-O bond length significantly decreases with decreasing Ca/(Ca+Mg+Fe) in opx when it ranges from 2/16 to 1/48[2]. Equilibrium isotope fractionation is mainly controlled by bond strengths, which could be measured by bond lengths. Thus, 103lnα26Mg/24Mg between dolomite and calcite dramatically increases with decreasing Mg/(Mg+Ca) in calcite [1] and it reaches a constant value when it is lower than 1/48. 103lnα44Ca/40Ca between opx and cpx significantly increases with decreasing Ca content in opx when Ca/(Ca+Mg+Fe) ranges from 2/16 to 1/48 [2]. If Ca/(Ca+Mg+Fe) is below 1/48, 103lnα44Ca/40Ca is not sensitive to Ca content. Based on our results, we conclude that the concentration effect on equilibrium isotope fractionation could be significant within a certain range of chemical composition of minerals, which should be a ubiquitous phenomenon in solid solution systems. [1] Wang, W., Qin, T., Zhou, C., Huang, S., Wu, Z., Huang, F., 2017. GCA 208, 185-197. [2] Feng, C., Qin, T., Huang, S., Wu, Z., Huang, F., 2014. GCA 143, 132-142.

Sharply increased mass loss from glaciers and ice caps in the Canadian Arctic Archipelago.

Science.gov (United States)

Gardner, Alex S; Moholdt, Geir; Wouters, Bert; Wolken, Gabriel J; Burgess, David O; Sharp, Martin J; Cogley, J Graham; Braun, Carsten; Labine, Claude

2011-05-19

Mountain glaciers and ice caps are contributing significantly to present rates of sea level rise and will continue to do so over the next century and beyond. The Canadian Arctic Archipelago, located off the northwestern shore of Greenland, contains one-third of the global volume of land ice outside the ice sheets, but its contribution to sea-level change remains largely unknown. Here we show that the Canadian Arctic Archipelago has recently lost 61 ± 7 gigatonnes per year (Gt yr(-1)) of ice, contributing 0.17 ± 0.02 mm yr(-1) to sea-level rise. Our estimates are of regional mass changes for the ice caps and glaciers of the Canadian Arctic Archipelago referring to the years 2004 to 2009 and are based on three independent approaches: surface mass-budget modelling plus an estimate of ice discharge (SMB+D), repeat satellite laser altimetry (ICESat) and repeat satellite gravimetry (GRACE). All three approaches show consistent and large mass-loss estimates. Between the periods 2004-2006 and 2007-2009, the rate of mass loss sharply increased from 31 ± 8 Gt yr(-1) to 92 ± 12 Gt yr(-1) in direct response to warmer summer temperatures, to which rates of ice loss are highly sensitive (64 ± 14 Gt yr(-1) per 1 K increase). The duration of the study is too short to establish a long-term trend, but for 2007-2009, the increase in the rate of mass loss makes the Canadian Arctic Archipelago the single largest contributor to eustatic sea-level rise outside Greenland and Antarctica.

Structure modification of Mg-Nb films under hydrogen sorption cycles

Energy Technology Data Exchange (ETDEWEB)

Mengucci, P., E-mail: p.mengucci@univpm.it [Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Universita Politecnica delle Marche, Via Brecce Bianche, I-60131 Ancona (Italy); Barucca, G.; Majni, G. [Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Universita Politecnica delle Marche, Via Brecce Bianche, I-60131 Ancona (Italy); Bazzanella, N.; Checchetto, R.; Miotello, A. [Dipartimento di Fisica, Universita di Trento, Via Sommarive, I-38123 Povo (Italy)

2011-09-15

Research highlights: > Influence of Nb additions on the hydrogen kinetics of Mg layers. > Structure modification of the Mg matrix during hydrogen cycling. > Lattice strains induced by Nb tends to decrease during hydrogen cycling. > Nb nanoparticles form during hydrogen cycling. > Nb enhances the porous structure of the Mg layer formed during hydrogen cycling. - Abstract: In the present work we focus our attention on the structural modifications induced by repeated absorption/desorption cycles on Mg-Nb layers. Samples consisting of a 30 {mu}m thick pure Mg or Mg-5 at.% Nb doped films, coated with a 20 nm thick Pd layer were submitted to repeated H{sub 2} sorption cycles in a volumetric apparatus. Isothermal desorption analysis at 350 deg. C was performed to evaluate the amount of absorbed hydrogen. X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and electron microscopy techniques (SEM and TEM) were used for the structural characterisation of the samples. Analyses show a deep modification of the material upon cycling. The presence of Nb enhances the structural modifications and induces an initial lattice contraction of the Mg matrix that tends to decrease on cycling via the formation of Nb nanoparticles (with average size of {approx}10 nm). SEM and TEM observations performed in cross section evidenced the formation of a porous structure.

Structural, optical and magnetic characterizations of Mn-doped MgO nanoparticles

International Nuclear Information System (INIS)

Azzaza, S.; El-Hilo, M.; Narayanan, S.; Judith Vijaya, J.; Mamouni, N.; Benyoussef, A.; El Kenz, A.; Bououdina, M.

2014-01-01

Structural, optical and room temperature magnetic properties of Mn-doped MgO nanoparticles with Mn fractions (5–50 at.%), were investigated. The as-prepared pure MgO, with grain size of about 15 nm, exhibits two magnetization components, one is diamagnetic and another is superparamagnetic. After removing the diamagnetic contribution, the magnetization curve exhibits superparamagnetic behavior which may be attributed to vacancy defects. As the Mn content increases, the lattice parameter decreases, the ferromagnetism appears and the emission bands were considerably blue shifted. First principle electronic structure calculations reveal the decrease of both the gap and the Curie temperature with increasing Mn concentration. The obtained results suggest that both Mn doping and oxygen vacancies play an important role in the development of room temperature ferromagnetism. - Graphical abstract: The measured room temperature magnetization curve for the Mn doped MgO with 5 at.%, 10 at.% and 20 at.%. - Highlights: • Combination of experimental and calculation methods. • Decrease of both the gap and the Curie temperature with increasing Mn content. • Ferromagnetism in MgO originate from interactions between defects

Refinement of Mg{sub 2}Si reinforcement in a commercial Al–20%Mg{sub 2}Si in-situ composite with bismuth, antimony and strontium

Energy Technology Data Exchange (ETDEWEB)

Nordin, Nur Azmah; Farahany, Saeed, E-mail: saeedfarahany@gmail.com; Ourdjini, Ali; Abu Bakar, Tuty Asma; Hamzah, Esah

2013-12-15

Refinement by addition elements of Al–Mg{sub 2}Si alloys is known to result in a change of primary Mg{sub 2}Si morphology. In this paper, the effects of Bi, Sb and Sr on the characteristic parameters of Al–20%Mg{sub 2}Si in-situ composite have been investigated by computer aided cooling curve thermal analysis and microstructural inspection. Size, density and aspect ratio measurements showed that additions of 0.4 wt.% Bi, 0.8 wt.% Sb and 0.01 wt.% Sr refined the Mg{sub 2}Si reinforcement. Exceeding these concentrations, however, resulted in coarsening of Mg{sub 2}Si particles with no change in the morphology. The results also showed that addition elements caused a decrease in the nucleation and growth temperatures of Mg{sub 2}Si particles. The refining effect of Bi, Sb and Sr is likely to be related to the effect of oxide bifilms suspended in the composite melt as favored nucleation substrates for Mg{sub 2}Si particles. - Highlight: • 0.4 wt.%, 0.8 wt.% and 0.01 wt.% is the optimum content for Bi, Sb and Sr addition. • Exceeding optimum concentration resulted in the coarsening of reinforcements. • Nucleation and growth temperatures decrease with addition of Bi, Sb and Sr. • The refining effect of Bi, Sb and Sr is likely to be related to the oxide bifilms.

Influences of Ti4+ and Mg2+ substitutions on the properties of lithium ferrites

International Nuclear Information System (INIS)

Su Hua; Zhang Huaiwu; Tang Xiaoli; Liu Baoyuan

2009-01-01

The Ti 4+ and Mg 2+ co-substituted lithium ferrites with different compositions of Zn 0.1 Li 0.45 Mn 0.1 Fe 2.35-2x (TiMg) x O 4 (x=0.0-0.5) were prepared by the ceramic standard processing. The magnetic properties and microstructure of the samples were investigated. A single phase spinel structure was confirmed by XRD in substituting range. Sintering densities continuously decreased with the increase at x value, which was attributed to the fact that the heavier Fe 3+ ions were replaced by the relatively lighter Ti 4+ and Mg 2+ ions. However, relative density of the samples had no obvious relationship with the substituting value. Saturation magnetization continuously decreased with x value, which was attributed to the decrease of resultant magnetic moment between A and B sub-lattice. Remanence decreased monotonously with x value due to the decrease of saturation magnetization and magnetocrystalline anisotropy constant. But the effect of Ti 4+ and Mg 2+ substitutions on the Br/Bs ratio values was not obvious. Coercive force was mainly determined by the microstructure and magnetocrystalline anisotropy constant of the ferrites. In this research, with the increase of Ti 4+ and Mg 2+ substitutions, the advantageous influence by the decrease of magnetocrystalline anisotropy constant was more significant than the disadvantageous influence caused by the increase of closed pores. As a result, coercive force of the ferrites also decreased monotonously with the increase at x value.

Hydrogen sorption properties of ball-milled Mg-C nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Spassov, Tony; Zlatanova, Zlatina; Spassova, Maya; Todorova, Stanislava [Faculty of Chemistry, University of Sofia ' ' St.Kl.Ohridski' ' , 1 James Bourchier str. 1164 Sofia (Bulgaria)

2010-10-15

MgH{sub 2} 75 at.%-C 25 at.% composites are synthesized by ball milling using different kinds of carbon additives: carbon black (CB), nanodiamonds (ND) and amorphous carbon soot (AC). X-ray diffraction analysis showed that the MgH{sub 2} phase in the as-obtained composite powders is nanocrystalline (80-100 nm). The SEM observations revealed that the samples consist of 5-15 {mu}m MgH{sub 2} particles, surrounded and in some cases coated by carbon flakes. The composite containing nanodiamonds revealed strong decrease of the MgH{sub 2} decomposition temperature with more than 100 C, compared to ball-milled pure MgH{sub 2}. Important issue of the present study is also the low temperature hydriding of the ball-milled Mg-C nanocomposites, investigated by high-pressure DSC. The process starts at about 200 C for all materials studied, but the hydriding mechanism looks different for the composites with different kinds of carbon additives. Whereas for Mg-carbon black it takes place in a relatively narrow temperature range, expressed by a single exothermic peak (200-300 C) for the other two composites the hydriding is a multi-step process, featured by two overlapped exothermic peaks for Mg-nanodiamonds and by two well separated exothermic effects (at about 300 C and 400 C) for Mg-amorphous carbon soot. The observed difference in the hydriding behavior of the Mg-C composites is attributed to the different kind of carbon component, which is supposed to play a catalytic role as well as protects magnesium from oxidation. The incorporation of carbon into the MgH{sub 2} particles results in the formation of high density of defects (dislocations and grain boundaries), which is supposed to be among the most possible reasons for the decreased hydride decomposition temperature. The Mg-C nanocomposites show reproducible hydriding/dehydriding behavior (thermodynamics and kinetics) during multiple cycling. Among the composites in the present study ''Mg-carbon black

Mechanism of chromatin degradation in thymocytes of irradiated rats

International Nuclear Information System (INIS)

Zotova, R.N.; Umanskij, S.R.; Tokarskaya, V.I.

1983-01-01

A biphase change in poly (ADP-ribose) polymerase activity of the thymocyte chromatin was observed after 10 Gy irradiation of rats: during the first minutes the incorporation of 14 C-NAD increased by 40% then started decreasing to make 110, 60 and 35% after 1, 2 and 3 h, respectively. Irradiation of rat thymus chromatin in vitro sharply decreased poly (ADP-ribose) polymerase activity. The possible role of changes in the poly (ADP-ribose) synthesis in the activation of nuclear Ca/Mg-dependent endonuclease and in the postirradiation degradation of the thymocyte chromatin is discussed

Conductivity, XRD, and FTIR studies of New Mg2+-ion-conducting solid polymer electrolytes: [PEG: Mg(CH3COO)2

International Nuclear Information System (INIS)

Polu, Anji Reddy; Kumar, Ranveer; Causin, Valerio; Neppalli, Ramesh

2011-01-01

Solid polymer electrolytes based on poly (ethylene glycol) (PEG) doped with Mg(CH 3 COO) 2 have been prepared by using the solution-casting method. The X-ray diffraction patterns of PEG with Mg(CH 3 COO) 2 salt indicated a decrease in the degree of crystallinity with increasing concentration of the salt. The complexation of Mg(CH 3 COO) 2 salt with the polymer was confirmed by using Fourier transform infrared spectroscopy (FTIR) studies. The ionic conductivity was measured for the [PEG: Mg(CH 3 COO) 2 ] system in the frequency range 50 Hz - 1 MHz. The addition of Mg salt was found to improve the ionic conductivity significantly. The 15-wt-% Mg(CH 3 COO) 2 -doped system had a maximum conductivity of 1.07 x 10 -6 S/cm at 303 K. The conductance spectrum shows two distinct regions: a dc plateau and a dispersive region. The temperature dependence of the ionic conductivity reveals the conduction mechanism to be an Arrhenius-type thermally activated process.

Live Cells Decreased Methane Production in Intestinal Content of Pigs

Directory of Open Access Journals (Sweden)

Y. L. Gong

2013-06-01

Full Text Available An in vitro gas production technique was used in this study to elucidate the effect of two strains of active live yeast on methane (CH4 production in the large intestinal content of pigs to provide an insight to whether active live yeast could suppress CH4 production in the hindgut of pigs. Treatments used in this study include blank (no substrate and no live yeast cells, control (no live yeast cells and yeast (YST supplementation groups (supplemented with live yeast cells, YST1 or YST2. The yeast cultures contained 1.8×1010 cells per g, which were added at the rates of 0.2 mg and 0.4 mg per ml of the fermented inoculum. Large intestinal contents were collected from 2 Duroc×Landrace×Yorkshire pigs, mixed with a phosphate buffer (1:2, and incubated anaerobically at 39°C for 24 h using 500 mg substrate (dry matter (DM basis. Total gas and CH4 production decreased (p<0.05 with supplementation of yeast. The methane production reduction potential (MRP was calculated by assuming net methane concentration for the control as 100%. The MRP of yeast 2 was more than 25%. Compared with the control group, in vitro DM digestibility (IVDMD and total volatile fatty acids (VFA concentration increased (p<0.05 in 0.4 mg/ml YST1 and 0.2 mg/ml YST2 supplementation groups. Proportion of propionate, butyrate and valerate increased (p<0.05, but that of acetate decreased (p<0.05, which led to a decreased (p<0.05 acetate: propionate (A: P ratio in the both YST2 treatments and the 0.4 mg/ml YST 1 supplementation groups. Hydrogen recovery decreased (p<0.05 with yeast supplementation. Quantity of methanogenic archaea per milliliter of inoculum decreased (p<0.05 with yeast supplementation after 24 h of incubation. Our results suggest that live yeast cells suppressed in vitro CH4 production when inoculated into the large intestinal contents of pigs and shifted the fermentation pattern to favor propionate production together with an increased population of acetogenic

Vacuum heating evaluation for plasmas of exponentially decreasing density profile

International Nuclear Information System (INIS)

Pestehe, S.J.; Mohammadnejad, M.

2008-01-01

Ultra-short pulse lasers have opened a regime of laser-plasma interaction where plasmas have scale lengths shorter than the laser wavelength and allow the possibility of generating near-solid density plasmas. The interaction of high-intensity laser beams with sharply bounded high-density and small scale length plasmas is considered. Absorption of the laser energy associated with the mechanism of dragging electrons out of the plasma into the vacuum and sending them back into the plasma with the electric field component along the density gradient, so called vacuum heating, is studied. An exponentially decreasing electron density profile is assumed. The vector potential of the electromagnetic field propagating through the plasma is calculated and the behaviour of the electric and magnetic components of the electromagnetic field is studied. The fraction of laser power absorbed in this process is calculated and plotted versus the laser beam incidence angle, illumination energy, and the plasma scale length

The Enhancement of Mg Corrosion Resistance by Alloying Mn and Laser-Melting

Directory of Open Access Journals (Sweden)

Youwen Yang

2016-03-01

Full Text Available Mg has been considered a promising biomaterial for bone implants. However, the poor corrosion resistance has become its main undesirable property. In this study, both alloying Mn and laser-melting were applied to enhance the Mg corrosion resistance. The corrosion resistance, mechanical properties, and microstructure of rapid laser-melted Mg-xMn (x = 0–3 wt % alloys were investigated. The alloys were composed of dendrite grains, and the grains size decreased with increasing Mn. Moreover, Mn could dissolve and induce the crystal lattice distortion of the Mg matrix during the solidification process. Mn ranging from 0–2 wt % dissolved completely due to rapid laser solidification. As Mn contents further increased up to 3 wt %, a small amount of Mn was left undissolved. The compressive strength of Mg-Mn alloys increased first (up to 2 wt % and then decreased with increasing Mn, while the hardness increased continuously. The refinement of grains and the increase in corrosion potential both made contributions to the enhancement of Mg corrosion resistance.

Stress corrosion cracking and hydrogen embrittlement of an Al-Zn-Mg-Cu alloy

International Nuclear Information System (INIS)

Song, R.G.; Dietzel, W.; Zhang, B.J.; Liu, W.J.; Tseng, M.K.; Atrens, A.

2004-01-01

The age hardening, stress corrosion cracking (SCC) and hydrogen embrittlement (HE) of an Al-Zn-Mg-Cu 7175 alloy were investigated experimentally. There were two peak-aged states during ageing. For ageing at 413 K, the strength of the second peak-aged state was slightly higher than that of the first one, whereas the SCC susceptibility was lower, indicating that it is possible to heat treat 7175 to high strength and simultaneously to have high SCC resistance. The SCC susceptibility increased with increasing Mg segregation at the grain boundaries. Hydrogen embrittlement (HE) increased with increased hydrogen charging and decreased with increasing ageing time for the same hydrogen charging conditions. Computer simulations were carried out of (a) the Mg grain boundary segregation using the embedded atom method and (b) the effect of Mg and H segregation on the grain boundary strength using a quasi-chemical approach. The simulations showed that (a) Mg grain boundary segregation in Al-Zn-Mg-Cu alloys is spontaneous, (b) Mg segregation decreases the grain boundary strength, and (c) H embrittles the grain boundary more seriously than does Mg. Therefore, the SCC mechanism of Al-Zn-Mg-Cu alloys is attributed to the combination of HE and Mg segregation induced grain boundary embrittlement

Microstructure, mechanical properties, bio-corrosion properties and cytotoxicity of as-extruded Mg-Sr alloys

Energy Technology Data Exchange (ETDEWEB)

Zhao, Chaoyong [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Pan, Fusheng, E-mail: fspan@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chongqing Academy of Science and Technology, Chongqing 401123 (China); Zhang, Lei; Pan, Hucheng; Song, Kai; Tang, Aitao [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China)

2017-01-01

In this study, as-extruded Mg-Sr alloys were studied for orthopedic application, and the microstructure, mechanical properties, bio-corrosion properties and cytotoxicity of as-extruded Mg-Sr alloys were investigated by optical microscopy, scanning electron microscopy with an energy dispersive X-ray spectroscopy, X-ray diffraction, tensile and compressive tests, immersion test, electrochemical test and cytotoxicity test. The results showed that as-extruded Mg-Sr alloys were composed of α-Mg and Mg{sub 17}Sr{sub 2} phases, and the content of Mg{sub 17}Sr{sub 2} phases increased with increasing Sr content. As-extruded Mg-Sr alloy with 0.5 wt.% Sr was equiaxed grains, while the one with a higher Sr content was long elongated grains and the grain size of the long elongated grains decreased with increasing Sr content. Tensile and compressive tests showed an increase of both tensile and compressive strength and a decrease of elongation with increasing Sr content. Immersion and electrochemical tests showed that as-extruded Mg-0.5Sr alloy exhibited the best anti-corrosion property, and the anti-corrosion property of as-extruded Mg-Sr alloys deteriorated with increasing Sr content, which was greatly associated with galvanic couple effect. The cytotoxicity test revealed that as-extruded Mg-0.5Sr alloy did not induce toxicity to cells. These results indicated that as-extruded Mg-0.5Sr alloy with suitable mechanical properties, corrosion resistance and good cytocompatibility was potential as a biodegradable implant for orthopedic application. - Highlights: • Biodegradable as-extruded Mg-Sr alloys were fabricated. • Microstructure of alloys changed with increasing Sr content. • Mechanical properties of alloys could be controlled by adjusting the Sr content. • Corrosion properties of alloys decreased with increasing Sr content. • As-extruded Mg-0.5Sr alloy was potential for orthopedic application.

Multifunctional MgO Layer in Perovskite Solar Cells.

Science.gov (United States)

Guo, Xudong; Dong, Haopeng; Li, Wenzhe; Li, Nan; Wang, Liduo

2015-06-08

A multifunctional magnesium oxide (MgO) layer was successfully introduced into perovskite solar cells (PSCs) to enhance their performance. MgO was coated onto the surface of mesoporous TiO(2) by the decomposition of magnesium acetate and, therefore, could block contact between the perovskite and TiO(2). X-ray photoelectron spectroscopy and infrared spectroscopy showed that the amount of H(2)O/hydroxyl absorbed on the TiO(2) decreased after MgO modification. The UV/Vis absorption spectra of the perovskite with MgO modification revealed an enhanced photoelectric performance compared with that of unmodified perovskite after UV illumination. In addition to the photocurrent, the photovoltage and fill factor also showed an enhancement after modification, which resulted in an increase in the overall efficiency of the cell from 9.6 to 13.9 %. Electrochemical impedance spectroscopy (EIS) confirmed that MgO acts as an insulating layer to reduce charge recombination. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of the La/Mg ratio on the structure and electrochemical properties of La xMg 3- xNi 9 ( x=1.6-2.2) hydrogen storage electrode alloys for nickel-metal hydride batteries

Science.gov (United States)

Liao, B.; Lei, Y. Q.; Chen, L. X.; Lu, G. L.; Pan, H. G.; Wang, Q. D.

Effect of La/Mg ratio on the structure and electrochemical properties of La xMg 3- xNi 9 ( x=1.6-2.2) ternary alloys was investigated. All alloys are consisted of a main phase with hexagonal PuNi 3-type structure and a few impurity phases (mainly LaNi 5 and MgNi 2). The increase of La/Mg ratio in the alloys leads to an increase in both the cell volume and the hydride stability. The discharge capacity of the alloys at 100 mA/g increases with the increase of La/Mg ratio and passes though a maximum of 397.5 mAh/g at x=2.0. As the La/Mg ratio increases, the high-rate dischargeability of the alloy electrodes at 1200 mA/g HRD 1200 decreases from 66.7% ( x=1.6) to 26.5% ( x=2.2). The slower decrease of HRD 1200 (from 66.7 to 52.7%) of the alloys with x=1.6-2.0 is mainly attributed to the decrease of electrocatalytic activity of the alloys for charge-transfer reaction, the more rapid decrease of HRD 1200 of the alloys with x>2.0 is mainly attributed to the lowering of the hydrogen diffusion rate in the bulk of alloy. The cycling capacity degradation of the alloys is rather fast for practical application due to the corrosion of La and Mg and the large VH in the hydride phase.

MgB sub 2 superconductor: a review

CERN Document Server

Mollah, S; Chaudhuri, B K

2003-01-01

Synthesis, structure and properties of the most intensively studied newly discovered intermetallic binary superconductor MgB sub 2 have been reviewed up to October, 2002. It has a hexagonal unit cell with cell parameters a approx 3.1432 A and c approx 3.5193 A. MgB sub 2 bulk samples synthesized under high pressure (approx 3.5 GPa) and high temperature (approx 1000 degC) has density approx 2.63 g/cm sup 3. The normal state carriers of MgB sub 2 are holes which have been established from the positive thermoelectric power and Hall coefficient measurements. The external pressure decreases the critical temperature (T sub c) with dT sub c /dP in the range of -1 to -2 K/GPa. The T sub c decreases rapidly by the doping of Mn, Li, Co, C, Al, Ni and Fe but increases slightly by Zn doping. However, no significant change of T sub c is observed by the doping of Si and Be. It is further noticed that the anisotropic ratio gamma(= H sub c sub 2 sup a sup b /H sub c sub 2 sup c) approx 1-5 with lower critical field (H sub c ...

The effect of substrate temperature upon the compositions of Mg and Se in Zn{sub 1-x}Mg{sub x}Se{sub y}Te{sub 1-y} layer grown by MOVPE

Energy Technology Data Exchange (ETDEWEB)

Nishio, M.; Ito, R.; Tanaka, K.; Urata, K.; Nakamura, Y.; Tanaka, T. [Department of Electrical and Electronic Engineering, Graduate School of Science and Engineering, Saga University, 1 Honjo, Saga 840-8502 (Japan); Saito, K.; Guo, Q.X. [Synchrotron Light Application Center, Saga University, 1 Honjo, Saga 840-8502 (Japan)

2014-07-15

The growth of Zn{sub 1-x}Mg{sub x}Se{sub y}Te{sub 1-y} layers was performed on (100) ZnTe substrate by metalorganic vapour phase epitaxy using dimethylzinc, bis-methylcyclopentadienyl-magnesium, diethyltelluride and diethylselenide. The effects of substrate temperature upon the compositions of Mg and Se have been investigated. The Mg composition in Zn{sub 1-x}Mg{sub x}Se{sub y}Te{sub 1-y} layer is significantly enhanced at low substrate temperature. Although the Se composition decreases with decreasing the substrate temperature, Zn{sub 1-x}Mg{sub x}Se{sub y}Te{sub 1-y} layer with a relatively high Se composition of 0.3 is obtainable at a low substrate temperature as low as 380 C. For all the layers, a two-mode behaviour with ZnTe- and MgTe-like longitudinal optical phonon modes is confirmed by Raman scattering. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Effects of magnesium contents in ZnMgO ternary alloys grown by molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Hu, Sheng-Yao, E-mail: shenghu2729@yahoo.com [Department of Digital Technology Design, Tungfang Design Institute, Hunei, Kaohsiung 82941, Taiwan (China); Chou, Wu-Ching [Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Weng, Yu-Hsiang [Department of Electrical Engineering, National Taiwan Ocean University, Keelung 20224, Taiwan (China)

2015-07-05

Highlights: • ZnMgO alloys with different Mg contents have been produced by MBE. • Optical and structural properties have been measured and investigated. • Stress is tensile and is increased as the increasing of Mg contents. • The asymmetric behavior of the Raman mode was influenced due to the Mg contents. - Abstract: Ternary alloys of ZnMgO samples with different magnesium contents have been grown by molecular beam epitaxy on the sapphire substrates. Room temperature photoluminescence energy of ZnMgO shifted as high as 3.677 eV by increasing Mg contents corresponding to the higher Urbach average localization energy which indicates more randomness in the alloys with higher Mg contents. XRD results are also verified that the c-axis length decreases as the increasing Mg contents linking to the increased tensile stress produced by the Mg atoms. Raman spectra analyzed by the spatial correlation model to describe that the linewidth Γ is decreased but the correlation length L is increased as the increasing of Mg contents.

Effects of magnesium contents in ZnMgO ternary alloys grown by molecular beam epitaxy

International Nuclear Information System (INIS)

Hu, Sheng-Yao; Chou, Wu-Ching; Weng, Yu-Hsiang

2015-01-01

Highlights: • ZnMgO alloys with different Mg contents have been produced by MBE. • Optical and structural properties have been measured and investigated. • Stress is tensile and is increased as the increasing of Mg contents. • The asymmetric behavior of the Raman mode was influenced due to the Mg contents. - Abstract: Ternary alloys of ZnMgO samples with different magnesium contents have been grown by molecular beam epitaxy on the sapphire substrates. Room temperature photoluminescence energy of ZnMgO shifted as high as 3.677 eV by increasing Mg contents corresponding to the higher Urbach average localization energy which indicates more randomness in the alloys with higher Mg contents. XRD results are also verified that the c-axis length decreases as the increasing Mg contents linking to the increased tensile stress produced by the Mg atoms. Raman spectra analyzed by the spatial correlation model to describe that the linewidth Γ is decreased but the correlation length L is increased as the increasing of Mg contents

On a Heat Exchange Problem under Sharply Changing External Conditions

Science.gov (United States)

Khishchenko, K. V.; Charakhch'yan, A. A.; Shurshalov, L. V.

2018-02-01

The heat exchange problem between carbon particles and an external environment (water) is stated and investigated based on the equations of heat conducting compressible fluid. The environment parameters are supposed to undergo large and fast variations. In the time of about 100 μs, the temperature of the environment first increases from the normal one to 2400 K, is preserved at this level for about 60 μs, and then decreases to 300 K during approximately 50 μs. At the same periods of time, the pressure of the external environment increases from the normal one to 67 GPa, is preserved at this level, and then decreases to zero. Under such external conditions, the heating of graphite particles of various sizes, their phase transition to the diamond phase, and the subsequent unloading and cooling almost to the initial values of the pressure and temperature without the reverse transition from the diamond to the graphite phase are investigated. Conclusions about the maximal size of diamond particles that can be obtained in experiments on the shock compression of the mixture of graphite with water are drawn.

Short communication: Change of naturally occurring benzoic acid during skim milk fermentation by commercial cheese starters.

Science.gov (United States)

Han, Noori; Park, Sun-Young; Kim, Sun-Young; Yoo, Mi-Young; Paik, Hyun-Dong; Lim, Sang-Dong

2016-11-01

This study sought to investigate the change of naturally occurring benzoic acid (BA) during skim milk fermentation by 4 kinds of commercial cheese starters used in domestic cheese. The culture was incubated at 3-h intervals for 24h at 30, 35, and 40°C. The BA content during fermentation by Streptococcus thermophilus STB-01 was detected after 12h at all temperatures, sharply increasing at 30°C. In Lactobacillus paracasei LC431, BA was detected after 9h at all temperatures, sharply increasing until 18h and decreasing after 18h at 30 and 35°C. In the case of R707 (consisting of Lactococcus lactis ssp. lactis and Lactococcus lactis ssp. cremoris), BA increased from 6h to 15h and decreased after 15h at 40°C. The BA during STB-01 and CHN-11 (1:1; mixture of S. thermophilus, Lc. lactis ssp. lactis, Lc. lactis ssp. cremoris, Lc. lactis ssp. diacetylactis, Leuconostoc mesenteroides ssp. cremoris) fermentation was detected after 3h at 35 and 40°C, sharply increasing up to 12h and decreasing after 15h at 35°C, and after 6h, increasing up to 9h at 30°C. After 3h, it steadily decreased at 40°C. The highest amount of BA was found during the fermentation by R707 at 30°C; 15h with 12.46mg/kg. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Catalytically Enhanced Hydrogen Sorption in Mg-MgH2 by Coupling Vanadium-Based Catalyst and Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Atikah Kadri

2015-06-01

Full Text Available Mg (MgH2-based composites, using carbon nanotubes (CNTs and pre-synthesized vanadium-based complex (VCat as the catalysts, were prepared by high-energy ball milling technique. The synergistic effect of coupling CNTs and VCat in MgH2 was observed for an ultra-fast absorption rate of 6.50 wt. % of hydrogen per minute and 6.50 wt. % of hydrogen release in 10 min at 200 °C and 300 °C, respectively. The temperature programmed desorption (TPD results reveal that coupling VCat and CNTs reduces both peak and onset temperatures by more than 60 °C and 114 °C, respectively. In addition, the presence of both VCat and CNTs reduces the enthalpy and entropy of desorption of about 7 kJ/mol H2 and 11 J/mol H2·K, respectively, as compared to those of the commercial MgH2, which ascribe to the decrease of desorption temperature. From the study of the effect of CNTs milling time, it is shown that partially destroyed CNTs (shorter milling time are better to enhance the hydrogen sorption performance.

Defect Study of MgO-CaO Material Doped with CeO2

Directory of Open Access Journals (Sweden)

Han Zhang

2013-01-01

Full Text Available MgO-CaO refractories were prepared using analytical reagent chemicals of Ca(OH2 and Mg(OH2 as starting materials and CeO2 as dopant, then sintered at 1650°C for 3 h. The effect of CeO2 powders on the defect of MgO-CaO refractories was investigated. The sample characterizations were analyzed by the techniques of XRD and SEM. According to the results, with the addition of CeO2, the lattice constant of CaO increased, and the bulk density of the samples increased while apparent porosity decreased. The densification of MgO-CaO refractories was promoted obviously. In the sintering process, MgO grains grew faster than CaO, pores at the MgO-CaO grain boundaries decreased while pores in the MgO grains increased gradually, and no pores were observed in the CaO grains. The nature of the CeO2 promoting densification lies in the substitution and solution with CaO. Ce4+ approaches into CaO lattices, which enlarges the vacancy concentration of Ca2+ and accelerates the diffusion of Ca2+.

In vitro degradation and cytotoxicity of Mg/Ca composites produced by powder metallurgy.

Science.gov (United States)

Zheng, Y F; Gu, X N; Xi, Y L; Chai, D L

2010-05-01

Mg/Ca (1 wt.%, 5 wt.%, 10 wt.% Ca) composites were prepared from pure magnesium and calcium powders using the powder metallurgy method, aiming to enlarge the addition of Ca content without the formation of Mg(2)Ca. The microstructures, mechanical properties and cytotoxicities of Mg/Ca composite samples were investigated. The corrosion of Mg/Ca composites in Dulbecco's modified Eagle's medium (DMEM) for various immersion intervals was studied by electrochemical impedance spectroscopy measurements and environmental scanning electron microscope, with the concentrations of released Mg and Ca ions in DMEM for various immersion time intervals being measured. It was shown that the main constitutional phases were Mg and Ca, which were uniformly distributed in the Mg matrix. The ultimate tensile strength (UTS) and elongation of experimental composites decreased with increasing Ca content, and the UTS of Mg/1Ca composite was comparable with that of as-extruded Mg-1Ca alloy. The corrosion potential increased with increasing Ca content, whereas the current density and the impedance decreased. It was found that the protective surface film formed quickly at the initial immersion stage. With increasing immersion time, the surface film became compact, and the corrosion rate of Mg/Ca composites slowed down. The surface film consisted mainly of CaCO(3), MgCO(3)x3H(2)O, HA and Mg(OH)(2) after 72 h immersion in DMEM. Mg/1Ca and Mg/5Ca composite extracts had no significant toxicity (p>0.05) to L-929 cells, whereas Mg/10Ca composite extract induced approximately 40% reduced cell viability. Copyright (c) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Electrical transport characterization of Al and Sn doped Mg 2 Si thin films

KAUST Repository

Zhang, Bo

2017-05-22

Thin-film Mg2Si was deposited using radio frequency (RF) magnetron sputtering. Al and Sn were incorporated as n-type dopants using co-sputtering to tune the thin-film electrical properties. X-ray diffraction (XRD) analysis confirmed that the deposited films are polycrystalline Mg2Si. The Sn and Al doping concentrations were measured using Rutherford backscattering spectroscopy (RBS) and energy dispersive X-ray spectroscopy (EDS). The charge carrier concentration and the charge carrier type of the Mg2Si films were measured using a Hall bar structure. Hall measurements show that as the doping concentration increases, the carrier concentration of the Al-doped films increases, whereas the carrier concentration of the Sn-doped films decreases. Combined with the resistivity measurements, the mobility of the Al-doped Mg2Si films is found to decrease with increasing doping concentration, whereas the mobility of the Sn-doped Mg2Si films is found to increase.

High-Pressure Study of Perovskites and Postperovskites in the (Mg,Fe)GeO ₃ System

Energy Technology Data Exchange (ETDEWEB)

Stan, Camelia V.; Dutta, Rajkrishna; Cava, Robert J.; Prakapenka, Vitali B.; Duffy, Thomas S. (Princeton); (UC)

2017-06-22

The effect of incorporation of Fe²⁺ on the perovskite (Pbnm) and postperovskite (Cmcm) structures was investigated in the (Mg,Fe)GeO₃ system at high pressures and temperatures using laser-heated diamond anvil cell and synchrotron X-ray diffraction. Samples with compositions of Mg# ≥ 48 were shown to transform to the perovskite (~30 GPa and ~1500 K) and postperovskite (>55 GPa, ~1600–1800 K) structures. Compositions with Mg# ≥ 78 formed single-phase perovskite and postperovskite, whereas those with Mg# < 78 showed evidence for partial decomposition. The incorporation of Fe into the perovskite structure causes a decrease in octahedral distortion as well as a modest decrease in bulk modulus (K₀) and a modest increase in zero-pressure volume (V₀). It also leads to a decrease in the perovskite-to-postperovskite phase transition pressure by ~9.5 GPa over compositions from Mg#78 to Mg#100.

Positron annihilation study on the Fermi surface of Cd-Mg alloys

International Nuclear Information System (INIS)

Koike, Shu-ichi; Hirabayashi, Makoto; Suzuki, Toshiharu; Hasegawa, Masayuki.

1979-01-01

Angular correlation measurements of annihilation photons have been made on single crystals of the Cd-Mg alloys over all compositions. It is found that the Fermi surfaces of the alloys in the Cd-rich region distort considerably from a free-electron sphere; the 3rd band ''stars'' and the 4th band horizontal ''cigars'' around the points L do not exist in Cd, and appear at 10 at % Mg accompanying an appreciable decrease of the energy gap at L. It is proposed that changes in the 4d core states cause the sudden decrease of the energy gap. (author)

Synthesis, characterization and antibacterial property of ZnO:Mg nanoparticles

Science.gov (United States)

Kompany, A.; Madahi, P.; Shahtahmasbi, N.; Mashreghi, M.

2012-09-01

Sol-gel method was successfully used for the synthesis of ZnO nanoparticles (NPs) doped with different concentrations of Mg and the structural, optical and antibacterial properties of the nanoparticles were studied. The synthesized ZnO:Mg powders were characterized using x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transformation Infrared (FTIR) and UV-Vis spectroscopy. It was revealed that the samples have hexagonal Wurtzite structure, and the phase segregation takes place for 15% Mg content. TEM images show that the average size of the particles is about 50 nm. Also, the antibacterial activities of the nanoparticles were tested against Escherichia coli (Gram negative) cultures. ZnO:Mg nanofluid showed good antibacterial activity which increases with the increase of NPs concentration, and decreases slightly with the amount of Mg.

Synthesis, structure and electrical properties of Mg-, Ni-codoped bismuth niobates

Directory of Open Access Journals (Sweden)

M. S. Koroleva

2017-12-01

Full Text Available Mg-, Ni-codoped bismuth niobates Bi1.6Mg0.8-xNixNb1.6O7-δ (x = 0; 0.2; 0.4; 0.6; 0.8 were obtained by conventional solid-state reaction method. It was shown that the Mg atoms are distributed at the Nb sites while the Ni atoms are distributed over the Bi- and the Nb-sites, according to the results of comparison of pycnometric and X-ray density of the Bi1.6Mg0.4Ni0.4Nb1.6O7-δ pyrochlore. In this case, about 15–20% of the vacancies are formed at the Bi sites. The obtained compounds are stable up to their melting point based on the DSC analysis data. Real dielectric permittivity ε' of the Bi1.6Mg0.8-xNixNb1.6O7-δ samples decreases from 80 to 65 with the temperature decrease from 25 to 700 °C and practically does not depend on frequency in the range of 1–1000 kHz. Oxides Bi1.6Mg0.8-xNixNb1.6O7-δ behave like insulators up to 280 °C, their conductivity increases with temperature (Ea,dc ≈ 1.3 eV, dc and with the Ni content at a given temperature.

Effects of Yb on the mechanical properties and microstructures of an Al-Mg alloy

International Nuclear Information System (INIS)

Song Min; Wu Zhenggang; He Yuehui

2008-01-01

This paper reported a first study of the effects of Yb on the microstructures and mechanical properties of an extruded Al-Mg alloy. It has been shown that the addition of 0.3 wt.% Yb decreases the mechanical properties of the alloy since Mg- and Yb-containing constituents decrease the concentration of Mg solute atoms in Al matrix, and thus the solution strengthening effect. However, the addition of 1 wt.% Yb substantially improves the mechanical behavior of the alloy because the concentration of Yb solute atoms in Al matrix is high enough to generate solution strengthening effect. The improvement in the mechanical properties is due to the large work-hardening and high dislocation density caused by the interaction between dislocations and Yb and Mg solute atoms. The Yb and Mg atoms inhibit the dynamic recovery and recrystallization of the alloy, thus provide a uniformly distributed dislocation structure with high density

Interplay of Mg2+, ADP, and ATP in the cytosol and mitochondria: unravelling the role of Mg2+ in cell respiration.

Science.gov (United States)

Gout, Elisabeth; Rébeillé, Fabrice; Douce, Roland; Bligny, Richard

2014-10-28

In animal and plant cells, the ATP/ADP ratio and/or energy charge are generally considered key parameters regulating metabolism and respiration. The major alternative issue of whether the cytosolic and mitochondrial concentrations of ADP and ATP directly mediate cell respiration remains unclear, however. In addition, because only free nucleotides are exchanged by the mitochondrial ADP/ATP carrier, whereas MgADP is the substrate of ATP synthase (EC 3.6.3.14), the cytosolic and mitochondrial Mg(2+) concentrations must be considered as well. Here we developed in vivo/in vitro techniques using (31)P-NMR spectroscopy to simultaneously measure these key components in subcellular compartments. We show that heterotrophic sycamore (Acer pseudoplatanus L.) cells incubated in various nutrient media contain low, stable cytosolic ADP and Mg(2+) concentrations, unlike ATP. ADP is mainly free in the cytosol, but complexed by Mg(2+) in the mitochondrial matrix, where [Mg(2+)] is tenfold higher. In contrast, owing to a much higher affinity for Mg(2+), ATP is mostly complexed by Mg(2+) in both compartments. Mg(2+) starvation used to alter cytosolic and mitochondrial [Mg(2+)] reversibly increases free nucleotide concentration in the cytosol and matrix, enhances ADP at the expense of ATP, decreases coupled respiration, and stops cell growth. We conclude that the cytosolic ADP concentration, and not ATP, ATP/ADP ratio, or energy charge, controls the respiration of plant cells. The Mg(2+) concentration, remarkably constant and low in the cytosol and tenfold higher in the matrix, mediates ADP/ATP exchange between the cytosol and matrix, [MgADP]-dependent mitochondrial ATP synthase activity, and cytosolic free ADP homeostasis.

Dependence of magnetic anisotropy on MgO sputtering pressure in Co20Fe60B20/MgO stacks

Science.gov (United States)

Kaidatzis, A.; Serletis, C.; Niarchos, D.

2017-10-01

We investigated the dependence of magnetic anisotropy of Ta/Co20Fe60B20/MgO stacks on the Ar partial pressure during MgO deposition, in the range between 0.5 and 15 mTorr. The stacks are studied before and after annealing at 300°C and it is shown that magnetic anisotropy significantly depends on Ar partial pressure. High pressure results in stacks with very low perpendicular magnetic anisotropy even after annealing, while low pressure results in stacks with perpendicular anisotropy even at the as-deposited state. A monotonic increase of magnetic anisotropy energy is observed as Ar partial pressure is decreased.

Mg-doped ZnO thin films deposited by the atomic layer chemical vapor deposition for the buffer layer of CIGS solar cell

Energy Technology Data Exchange (ETDEWEB)

Li, Zhao-Hui [Department of Electronics Engineering, Gachon University, Soojung-gu, Seongnam city 461-701, Gyunggi-do (Korea, Republic of); Center for Photovoltaic and Solar Energy, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen city 518055 (China); Cho, Eou-Sik [Department of Electronics Engineering, Gachon University, Soojung-gu, Seongnam city 461-701, Gyunggi-do (Korea, Republic of); Kwon, Sang Jik, E-mail: sjkwon@gachon.ac.kr [Department of Electronics Engineering, Gachon University, Soojung-gu, Seongnam city 461-701, Gyunggi-do (Korea, Republic of)

2014-09-30

Highlights: • Mg-doped ZnO film as CIGS buffer was prepared by ALD process. • The grain size of ZnO-like hexagonal phase decreased with Mg content. • The transmittance and crystallinity increased but the band gap decreased with temperature. - Abstract: Mg-doped ZnO [(Zn, Mg)O] thin films were prepared by atomic layer chemical vapor deposition (ALCVD) process with different Mg content, using diethyl zinc, biscyclopentadienyl magnesium, and water as the metal and oxygen sources, respectively. The ratio of Mg to Zn was varied by changing the pulse ratio of MgCp{sub 2} to DEZn precursor to study its effect on the properties of (Zn, Mg)O thin films. From the experimental results, it was shown that the grain size of the ZnO-like hexagonal phase (Zn, Mg)O decreased as the Mg content increased. But the transmittance and optical band gap of (Zn, Mg)O films increased with the increase of the Mg content. In addition, the effect of the substrate temperature on the properties of (Zn, Mg)O films was also investigated. The deposition rate, transmittance, and crystallinity of (Zn, Mg)O films increased as the substrate temperature increased. But its band gap decreased slightly with the increase of substrate temperature.

Surface excess on MgO-doped TiO{sub 2} nanoparticles; Segregacao superficial de MgO em nanoparticulas de TiO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Gouvea, D.; Viana, B.H.; Miagava, J., E-mail: dgouvea@usp.br, E-mail: bhernardov@gmail.com, E-mail: joice.mgv@gmail.com [Universidade de Sao Paulo (USP), SP (Brazil). Dept. de Engenharia Metalurgica e de Materiais. Lab. de Processos Ceramicos

2016-10-15

Anatase has been the subject of several recent investigations partly as consequence of its interesting catalytic properties. Additives such as MgO have been introduced to improve the performance of the photocatalytic TiO{sub 2}. However, the physical-chemistry of these oxides systems and their relationship with properties are poorly understood. In this work, nanoparticles of xMgO-(1-x)TiO{sub 2} (0≤ x≤ 0.05) were synthesized by the polymeric precursor method at 500 °C for 15 h. XRD results showed that only anatase phase was obtained and the crystallite size decreases with increased MgO concentration. Magnesia surface excess was calculated by washing powders with HNO{sub 3} and the soluble Mg ions concentration determined by chemical analysis. FTIR analysis confirms that the acid washing modified the particle surface. Therefore, it is proposed that the reduction of the crystallite size occurs due to segregation of MgO on TiO{sub 2} nanoparticles surfaces. (author)

Direct observation of grafting interlayer phosphate in Mg/Al layered double hydroxides

International Nuclear Information System (INIS)

Shimamura, Akihiro; Kanezaki, Eiji; Jones, Mark I.; Metson, James B.

2012-01-01

The grafting of interlayer phosphate in synthetic Mg/Al layered double hydroxides with interlayer hydrogen phosphate (LDH-HPO 4 ) has been studied by XRD, TG/DTA, FT-IR, XPS and XANES. The basal spacing of crystalline LDH-HPO 4 decreases in two stages with increasing temperature, from 1.06 nm to 0.82 nm at 333 K in the first transition, and to 0.722 nm at 453 K in the second. The first stage occurs due to the loss of interlayer water and rearrangement of the interlayer HPO 4 2− . In the second transition, the interlayer phosphate is grafted to the layer by the formation of direct bonding to metal cations in the layer, accompanied by a change in polytype of the crystalline structure. The grafted phosphate becomes immobilized and cannot be removed by anion-exchange with 1-octanesulfonate. The LDH is amorphous at 743 K but decomposes to Mg 3 (PO 4 ) 2 , AlPO 4 , MgO and MgAl 2 O 4 after heated to 1273 K. - Graphical abstract: The cross section of the synthetic Mg, Al layered double hydroxides in Phase 1, with interlayer hydrogen phosphate Phase 2, and with grafted phosphate, Phase 3. Highlights: ► The grafting of hydrogen phosphate intercalated Mg/Al-LDH has been studied. ► The basal spacing of crystalline LDH-HPO 4 decreases in two stages with increasing temperature. ► The first decrease is due to loss of interlayer water, the second is attributed to phosphate grafting. ► The grafted interlayer phosphate becomes immobilized and cannot be removed by anion-exchange.

Magnesium absorption from mineral water decreases with increasing quantities of magnesium per serving in rats.

Science.gov (United States)

Nakamura, Eri; Tai, Hideyuki; Uozumi, Yoshinobu; Nakagawa, Koji; Matsui, Tohru

2012-01-01

It is hypothesized that magnesium (Mg) absorption from mineral water is affected by the concentration of Mg in the water, the consumption pattern, and the volume consumed per serving. The present study examined the effect of serving volume and consumption pattern of artificial mineral water (AMW) and Mg concentration on Mg absorption in rats. Magnesium in AMW was labeled with magnesium-25 as a tracer. Each group consisted of 6 or 7 rats. In experiment 1, the rats received 1 mL of AMW containing 200 mg Mg/L at 4 times, 400 mg Mg/L twice, or 800 mg Mg/L at 1 time. In experiment 2, the rats received 1 mL of AMW containing 200 mg Mg/L or 0.25 mL of AMW containing 800 mg Mg/L at 4 times or 1 mL of AMW containing 800 mg Mg/L at 1 time. The absorption of Mg decreased with increasing Mg concentrations in the same serving volume of AMW with different serving frequencies. When the AMW containing 800 mg Mg/L was portioned into 4 servings, Mg absorption increased to the level of absorption in the group exposed to AMW containing 200 mg Mg/L served at the same frequency. These results suggest that the Mg concentration and the volume of AMW do not affect Mg absorption per se, but Mg absorption from AMW decreases when the amount of Mg in each serving is increased. Thus, frequent consumption is preferable for mineral water rich in Mg when the total consumption of mineral water is the same. Copyright © 2012 Elsevier Inc. All rights reserved.

Impact of interface manipulation of oxide on electrical transport properties and low-frequency noise in MgO/NiFe/MgO heterojunctions

International Nuclear Information System (INIS)

Li, Jian-wei; Zhao, Chong-jun; Feng, Chun; Yu, Guang-hua; Zhou, Zhongfu

2015-01-01

Low-frequency noise and magnetoresistance in sputtered-deposited Ta(5 nm)/MgO (3 nm)/NiFe(10 nm)/MgO(3 nm)/Ta(3 nm) films have been measured as a function of different annealing times at 400°C. These measurements did not change synchronously with annealing time. A significant increase in magnetoresistance is observed for short annealing times (of the order of minutes) and is correlated with a relatively small reduction in 1/f noise. In contrast, a significant reduction in 1/f noise is observed for long annealing times (of the order of hours) accompanied by a small change in magnetoresistance. After annealing for 2 hours, the 1/f noise decreases by three orders of magnitude. Transmission electron microscopy and slow positron annihilation results implicate the cause being micro-structural changes in the MgO layers and interfaces following different annealing times. The internal vacancies in the MgO layers gather into vacancy clusters to reduce the defect density after short annealing times, whereas the MgO/NiFe and the NiFe/MgO interfaces improve significantly after long annealing times with the amorphous MgO layers gradually crystallizing following the release of interfacial stress

Impact of interface manipulation of oxide on electrical transport properties and low-frequency noise in MgO/NiFe/MgO heterojunctions

Science.gov (United States)

Li, Jian-wei; Zhao, Chong-jun; Feng, Chun; Zhou, Zhongfu; Yu, Guang-hua

2015-08-01

Low-frequency noise and magnetoresistance in sputtered-deposited Ta(5 nm)/MgO (3 nm)/NiFe(10 nm)/MgO(3 nm)/Ta(3 nm) films have been measured as a function of different annealing times at 400°C. These measurements did not change synchronously with annealing time. A significant increase in magnetoresistance is observed for short annealing times (of the order of minutes) and is correlated with a relatively small reduction in 1/f noise. In contrast, a significant reduction in 1/f noise is observed for long annealing times (of the order of hours) accompanied by a small change in magnetoresistance. After annealing for 2 hours, the 1/f noise decreases by three orders of magnitude. Transmission electron microscopy and slow positron annihilation results implicate the cause being micro-structural changes in the MgO layers and interfaces following different annealing times. The internal vacancies in the MgO layers gather into vacancy clusters to reduce the defect density after short annealing times, whereas the MgO/NiFe and the NiFe/MgO interfaces improve significantly after long annealing times with the amorphous MgO layers gradually crystallizing following the release of interfacial stress.

Impact of interface manipulation of oxide on electrical transport properties and low-frequency noise in MgO/NiFe/MgO heterojunctions

Energy Technology Data Exchange (ETDEWEB)

Li, Jian-wei [School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhao, Chong-jun; Feng, Chun; Yu, Guang-hua [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhou, Zhongfu [School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China)

2015-08-15

Low-frequency noise and magnetoresistance in sputtered-deposited Ta(5 nm)/MgO (3 nm)/NiFe(10 nm)/MgO(3 nm)/Ta(3 nm) films have been measured as a function of different annealing times at 400°C. These measurements did not change synchronously with annealing time. A significant increase in magnetoresistance is observed for short annealing times (of the order of minutes) and is correlated with a relatively small reduction in 1/f noise. In contrast, a significant reduction in 1/f noise is observed for long annealing times (of the order of hours) accompanied by a small change in magnetoresistance. After annealing for 2 hours, the 1/f noise decreases by three orders of magnitude. Transmission electron microscopy and slow positron annihilation results implicate the cause being micro-structural changes in the MgO layers and interfaces following different annealing times. The internal vacancies in the MgO layers gather into vacancy clusters to reduce the defect density after short annealing times, whereas the MgO/NiFe and the NiFe/MgO interfaces improve significantly after long annealing times with the amorphous MgO layers gradually crystallizing following the release of interfacial stress.

Ethylbenzene dehydrogenation over FeOx/(Mg,Zn)(Al)O catalysts derived from hydrotalcites: Role of MgO as basic sites

KAUST Repository

Balasamy, Rabindran J.; Tope, Balkrishna B.; Khurshid, Alam; Al-Ali, Ali A S; Atanda, Luqman A.; Sagata, Kunimasa; Asamoto, Makiko; Yahiro, Hidenori; Nomura, Kiyoshi; Sano, Tsuneji; Takehira, Katsuomi; Al-Khattaf, Sulaiman S.

2011-01-01

A series of Mg3-xZnxFe0.5Al0.5 mixed oxide catalysts derived from hydrotalcites were tested in the ethylbenzene dehydrogenation to styrene in He atmosphere at 550 °C. The catalysts were prepared by coprecipitation from the nitrates of metal components followed by calcination to mixed oxides at 550 °C. A part of Mg2+ in Mg 3Fe0.5Al0.5 mixed oxide was replaced with Zn2+ to test the effect of MgO as the support. The mixed oxides were composed of periclase and spinel-type compounds with a high surface area of 100-180m2gcat-1. Mössbauer and XPS measurements indicated the presence of Fe3+ on the catalysts and H2-TPR measurement suggested that the dehydrogenation reaction is catalyzed by the reduction-oxidation between Fe3+/Fe2+. The activity of Mg3-xZnxFe0.5Al0.5 mixed oxide decreased with increasing x, indicating an important role of MgO on the activity. Both CO2-TPD measurements as well as IR measurements of adsorbed CO2 clearly indicated the presence of basic sites of Mg 2+O2- on the catalysts. It seems that the combination of Mg2+O2- and Fe3+ was essential for the catalytic activity. It is concluded that the surface base sites generated on O2- bound Mg2+ near Fe3+ sites are responsible for H+-abstraction; the dehydrogenation of ethylbenzene was initiated by the H+ abstraction on Mg2+O2- basic sites, and accelerated by the reduction-oxidation of Fe3+/Fe2+ active species. © 2011 Elsevier B.V.

Ethylbenzene dehydrogenation over FeOx/(Mg,Zn)(Al)O catalysts derived from hydrotalcites: Role of MgO as basic sites

KAUST Repository

Balasamy, Rabindran J.

2011-05-01

A series of Mg3-xZnxFe0.5Al0.5 mixed oxide catalysts derived from hydrotalcites were tested in the ethylbenzene dehydrogenation to styrene in He atmosphere at 550 °C. The catalysts were prepared by coprecipitation from the nitrates of metal components followed by calcination to mixed oxides at 550 °C. A part of Mg2+ in Mg 3Fe0.5Al0.5 mixed oxide was replaced with Zn2+ to test the effect of MgO as the support. The mixed oxides were composed of periclase and spinel-type compounds with a high surface area of 100-180m2gcat-1. Mössbauer and XPS measurements indicated the presence of Fe3+ on the catalysts and H2-TPR measurement suggested that the dehydrogenation reaction is catalyzed by the reduction-oxidation between Fe3+/Fe2+. The activity of Mg3-xZnxFe0.5Al0.5 mixed oxide decreased with increasing x, indicating an important role of MgO on the activity. Both CO2-TPD measurements as well as IR measurements of adsorbed CO2 clearly indicated the presence of basic sites of Mg 2+O2- on the catalysts. It seems that the combination of Mg2+O2- and Fe3+ was essential for the catalytic activity. It is concluded that the surface base sites generated on O2- bound Mg2+ near Fe3+ sites are responsible for H+-abstraction; the dehydrogenation of ethylbenzene was initiated by the H+ abstraction on Mg2+O2- basic sites, and accelerated by the reduction-oxidation of Fe3+/Fe2+ active species. © 2011 Elsevier B.V.

Overall evaluation of combustion and NO(x) emissions for a down-fired 600 MW(e) supercritical boiler with multiple injection and multiple staging.

Science.gov (United States)

Kuang, Min; Li, Zhengqi; Liu, Chunlong; Zhu, Qunyi

2013-05-07

To achieve significant reductions in NOx emissions and to eliminate strongly asymmetric combustion found in down-fired boilers, a deep-air-staging combustion technology was trialed in a down-fired 600 MWe supercritical utility boiler. By performing industrial-sized measurements taken of gas temperatures and species concentrations in the near wing-wall region, carbon in fly ash and NOx emissions at various settings, effects of overfire air (OFA) and staged-air damper openings on combustion characteristics, and NOx emissions within the furnace were experimentally determined. With increasing the OFA damper opening, both fluctuations in NOx emissions and carbon in fly ash were initially slightly over OFA damper openings of 0-40% but then lengthened dramatically in openings of 40-70% (i.e., NOx emissions reduced sharply accompanied by an apparent increase in carbon in fly ash). Decreasing the staged-air declination angle clearly increased the combustible loss but slightly influenced NOx emissions. In comparison with OFA, the staged-air influence on combustion and NOx emissions was clearly weaker. Only at a high OFA damper opening of 50%, the staged-air effect was relatively clear, i.e., enlarging the staged-air damper opening decreased carbon in fly ash and slightly raised NOx emissions. By sharply opening the OFA damper to deepen the air-staging conditions, although NOx emissions could finally reduce to 503 mg/m(3) at 6% O2 (i.e., an ultralow NOx level for down-fired furnaces), carbon in fly ash jumped sharply to 15.10%. For economical and environment-friendly boiler operations, an optimal damper opening combination (i.e., 60%, 50%, and 50% for secondary air, staged-air, and OFA damper openings, respectively) was recommended for the furnace, at which carbon in fly ash and NOx emissions attained levels of about 10% and 850 mg/m(3) at 6% O2, respectively.

The feasibility of tunable p-type Mg doping in a GaN monolayer nanosheet

International Nuclear Information System (INIS)

Xia, Congxin; Peng, Yuting; Wei, Shuyi; Jia, Yu

2013-01-01

Based on density functional theory, the electronic structures, formation energy and transition energy level of a p-type Mg-doped GaN nanosheet are investigated. Numerical results show that the transition energy level decreases monotonously with increasing Mg doping concentration in Mg-doped GaN nanosheet systems, which is lower than that of the Mg-doped bulk GaN case. Moreover, the formation energy calculations indicate that Mg-doped GaN nanosheet structures can be realized under N-rich experimental growth conditions

Mechanical properties and corrosion behavior of Mg-Gd-Ca-Zr alloys for medical applications.

Science.gov (United States)

Shi, Ling-Ling; Huang, Yuanding; Yang, Lei; Feyerabend, Frank; Mendis, Chamini; Willumeit, Regine; Ulrich Kainer, Karl; Hort, Norbert

2015-07-01

Magnesium alloys are promising candidates for biomedical applications. In this work, influences of composition and heat treatment on the microstructure, the mechanical properties and the corrosion behavior of Mg-Gd-Ca-Zr alloys as potential biomedical implant candidates were investigated. Mg5Gd phase was observed at the grain boundaries of Mg-10Gd-xCa-0.5Zr (x=0, 0.3, 1.2wt%) alloys. Increase in the Ca content led to the formation of additional Mg2Ca phase. The Ca additions increased both the compressive and the tensile yield strengths, but reduced the ductility and the corrosion resistance in cell culture medium. After solution heat treatment, the Mg5Gd particles dissolved in the Mg matrix. The compressive strength decreased, while the corrosion resistance improved in the solution treated alloys. After ageing at 200°C, metastable β' phase formed on prismatic planes and a new type of basal precipitates have been observed, which improved the compressive and tensile ultimate strength, but decreased the ductility. Copyright © 2015 Elsevier Ltd. All rights reserved.

Discharge behaviour of Mg-Al-Pb and Mg-Al-Pb-In alloys as anodes for Mg-air battery

International Nuclear Information System (INIS)

Wang, Naiguang; Wang, Richu; Peng, Chaoqun; Peng, Bing; Feng, Yan; Hu, Chengwang

2014-01-01

Highlights: • We investigate the effect of indium on the discharge behaviour of Mg-Al-Pb alloy. • We evaluate the performance of Mg-air batteries with Mg-Al-Pb and Mg-Al-Pb-In anodes. • We analyze the activation mechanism of Mg-Al-Pb-In alloy in the discharge process. - Abstract: The discharge behaviour of Mg-Al-Pb and Mg-Al-Pb-In alloys in 3.5 wt.% NaCl solution is investigated by electrochemical techniques, and compared with that of pure magnesium. The results show that Mg-Al-Pb-In alloy provides a more negative potential and exhibits a higher utilization efficiency in contrast with Mg-Al-Pb alloy and pure magnesium during the half-cell test at a large current density, and gives desirable discharge performance when used as anode for Mg- air battery. The peak power density of the Mg-air battery with Mg-Al-Pb-In anode is 94.5 mW cm −2 , which is comparable with those of Mg-H 2 O 2 semi-fuel batteries. Moreover, the activation mechanism of Mg-Al-Pb-In alloy during the discharge process is also analyzed

Reducing Mg acceptor activation-energy in Al(0.83)Ga(0.17)N disorder alloy substituted by nanoscale (AlN)₅/(GaN)₁ superlattice using Mg(Ga) δ-doping: Mg local-structure effect.

Science.gov (United States)

Zhong, Hong-xia; Shi, Jun-jie; Zhang, Min; Jiang, Xin-he; Huang, Pu; Ding, Yi-min

2014-10-23

Improving p-type doping efficiency in Al-rich AlGaN alloys is a worldwide problem for the realization of AlGaN-based deep ultraviolet optoelectronic devices. In order to solve this problem, we calculate Mg acceptor activation energy and investigate its relationship with Mg local structure in nanoscale (AlN)5/(GaN)1 superlattice (SL), a substitution for Al(0.83)Ga(0.17)N disorder alloy, using first-principles calculations. A universal picture to reduce acceptor activation energy in wide-gap semiconductors is given for the first time. By reducing the volume of the acceptor local structure slightly, its activation energy can be decreased remarkably. Our results show that Mg acceptor activation energy can be reduced significantly from 0.44 eV in Al(0.83)Ga(0.17)N disorder alloy to 0.26 eV, very close to the Mg acceptor activation energy in GaN, and a high hole concentration in the order of 10(19) cm(-3) can be obtained in (AlN)5/(GaN)1 SL by Mg(Ga) δ-doping owing to GaN-monolayer modulation. We thus open up a new way to reduce Mg acceptor activation energy and increase hole concentration in Al-rich AlGaN.

Reducing Mg Acceptor Activation-Energy in Al0.83Ga0.17N Disorder Alloy Substituted by Nanoscale (AlN)5/(GaN)1 Superlattice Using MgGa δ-Doping: Mg Local-Structure Effect

Science.gov (United States)

Zhong, Hong-Xia; Shi, Jun-Jie; Zhang, Min; Jiang, Xin-He; Huang, Pu; Ding, Yi-Min

2014-10-01

Improving p-type doping efficiency in Al-rich AlGaN alloys is a worldwide problem for the realization of AlGaN-based deep ultraviolet optoelectronic devices. In order to solve this problem, we calculate Mg acceptor activation energy and investigate its relationship with Mg local structure in nanoscale (AlN)5/(GaN)1 superlattice (SL), a substitution for Al0.83Ga0.17N disorder alloy, using first-principles calculations. A universal picture to reduce acceptor activation energy in wide-gap semiconductors is given for the first time. By reducing the volume of the acceptor local structure slightly, its activation energy can be decreased remarkably. Our results show that Mg acceptor activation energy can be reduced significantly from 0.44 eV in Al0.83Ga0.17N disorder alloy to 0.26 eV, very close to the Mg acceptor activation energy in GaN, and a high hole concentration in the order of 1019 cm-3 can be obtained in (AlN)5/(GaN)1 SL by MgGa δ-doping owing to GaN-monolayer modulation. We thus open up a new way to reduce Mg acceptor activation energy and increase hole concentration in Al-rich AlGaN.

The effect of the MgO buffer layer thickness on magnetic anisotropy in MgO/Fe/Cr/MgO buffer/MgO(001)

Energy Technology Data Exchange (ETDEWEB)

Kozioł-Rachwał, Anna, E-mail: a.koziolrachwal@aist.go.jp [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); Nozaki, Takayuki; Zayets, Vadym; Kubota, Hitoshi; Fukushima, Akio; Yuasa, Shinji [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Suzuki, Yoshishige [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)

2016-08-28

The relationship between the magnetic properties and MgO buffer layer thickness d was studied in epitaxial MgO/Fe(t)/Cr/MgO(d) layers grown on MgO(001) substrate in which the Fe thickness t ranged from 0.4 nm to 1.1 nm. For 0.4 nm ≤ t ≤ 0.7 nm, a non-monotonic coercivity dependence on the MgO buffer thickness was shown by perpendicular magneto-optic Kerr effect magnetometry. For thicker Fe films, an increase in the buffer layer thickness resulted in a spin reorientation transition from perpendicular to the in-plane magnetization direction. Possible origins of these unusual behaviors were discussed in terms of the suppression of carbon contamination at the Fe surface and changes in the magnetoelastic anisotropy in the system. These results illustrate a method to control magnetic anisotropy in MgO/Fe/Cr/MgO(d) via an appropriate choice of MgO buffer layer thickness d.

Enhanced mechanical properties of an Al–Si–Cu–Mg alloy at 300 °C: Effects of Mg and the Q-precipitate phase

International Nuclear Information System (INIS)

Farkoosh, A.R.; Pekguleryuz, M.

2015-01-01

Strategies to improve the strength of Al–Si alloys at elevated temperatures can follow two routes: (i) improving the age-hardening behavior and/or (ii) producing effective dispersoid strengthening. In this study, the influence of Mg (in the range of 0.3–0.7 wt%) on the precipitation characteristics and mechanical properties of the Al–7Si–0.5Cu–(Mg) alloy was investigated. Thermodynamic calculations were performed via the CALPHAD method which showed that Q-Al 5 Mg 8 Cu 2 Si 6 is the main thermodynamically stable precipitate at 300 °C. The calculations were validated by transmission electron microscopy and differential scanning calorimetry analyses. Increasing the Mg level from 0.3 wt% to the maximum solubility limit of ∼0.5 wt% increased the amount of the Q-Al 5 Mg 8 Cu 2 Si 6 precipitates at 300 °C by ∼60 wt% and significantly improved the tensile strength and creep resistance at the expense of some ductility. Mg in excess of the solubility limit was seen to remain within the microstructure in the form of the large π-Al 8 FeMg 3 Si 6 and β-Mg 2 Si intermetallics after solution treatment at 530 °C. Cracking of the brittle π-Al 8 FeMg 3 Si 6 intermetallics during deformation was accounted for the decreased ductility of the alloys at high Mg levels. It is concluded that the Mg level can be increased to 0.5 wt% in the A–7Si–0.5Cu alloys to improve strength. However, for elevated temperature applications in which both strength and ductility are required (e.g. Diesel engine), modification of the π-Al 8 FeMg 3 Si 6 intermetallics would be required to improve the ductility of the alloys with high Mg contents

In-situ synchrotron x-ray study of MgB2 formation when doped by SiC

Science.gov (United States)

Abrahamsen, A. B.; Grivel, J.-C.; Andersen, N. H.; Herrmann, M.; Häßler, W.; Birajdar, B.; Eibl, O.; Saksl, K.

2008-02-01

We have studied the evolution of the reaction xMg + 2B + ySiC → zMg1-p(B1-qCq)2 + yMg2Si in samples of 1, 2, 5 and 10 wt% SiC doping. We found a coincident formation of MgB2 and Mg2Si, whereas the crystalline part of the SiC nano particles is not reacting at all. Evidence for incorporation of carbon into the MgB2 phase was established from the decrease of the a-axis lattice parameter upon increasing SiC doping. An estimate of the MgB2 lower limit grain size was found to decrease from L100 = 795 Å and L002 = 337 Å at 1 wt% SiC to L100 = 227 Å and L002= 60 Å at 10 wt% SiC. Thus superconductivity might be suppressed at 10 wt% SiC doping due to the grain size approaching the coherence length.

The effect of impurities on the electronic properties of MgO

Energy Technology Data Exchange (ETDEWEB)

Jalili, Seifollah [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 16315-1618, Tehran (Iran, Islamic Republic of); Computational Physical Sciences Research Laboratory, Department of Nano-Science, Institute for Studies in Theoretical Physics and Mathematics (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of)], E-mail: sjalili@nano.ipm.ac.ir; Majidi, Roya [Department of Physics, Shahid Beheshti University, Tehran (Iran, Islamic Republic of)

2008-10-01

The effect of impurities on the electronic properties of MgO is investigated using the full potential linearized augmented plane-wave plus local-orbitals method based on density functional theory. The electronic band structures and density of states of MgO in the presence of Ca, Li, and Na impurities were calculated. It is found that increasing the amount of Ca impurity decreases the energy band gap and increases the width of the upper part of the valence band. Some of the considered impurities (Li and Na) change the electronic properties of MgO extensively.

The effect of impurities on the electronic properties of MgO

International Nuclear Information System (INIS)

Jalili, Seifollah; Majidi, Roya

2008-01-01

The effect of impurities on the electronic properties of MgO is investigated using the full potential linearized augmented plane-wave plus local-orbitals method based on density functional theory. The electronic band structures and density of states of MgO in the presence of Ca, Li, and Na impurities were calculated. It is found that increasing the amount of Ca impurity decreases the energy band gap and increases the width of the upper part of the valence band. Some of the considered impurities (Li and Na) change the electronic properties of MgO extensively

Decreases in soil microbial function and functional diversity in response to depleted uranium

International Nuclear Information System (INIS)

Meyer, M.C.; Paschke, M.W.; McLendon, T.

1998-01-01

A soil microcosm experiment was used to analyze effects of depleted uranium (DU) on soil function, and the concomitant changes in bacterial functional diversity. Uranium treatment levels were 0, 50, 500, 5000, 10,000 and 25,000 mg DU kg -1 soil. Three measures of soil function were made. Overall soil biological activity was assessed via measurement of soil respiration. Decomposition was assessed by measurement of mass loss of four different plant litter types: wood sticks, cellulose paper, high-N grass, and low-N grass. Mineral N availability in the microcosms was estimated using ion-exchange resin bags. Functional diversity of the microcosms was analyzed through the use of the Biolog-system of sole-C-utilization patterns. Soil respiration was the most sensitive measure of functional changes, with significant decreases observed starting at the 500 mg kg -1 treatment. No differences in N availability were observed across the U treatments. Litter decomposition was significantly decreased at the 25,000 mg kg -1 level relative to the control for all litter types except the high-N grass. Wood decomposition was reduced by 84% at the 25,000 mg kg - treatment, cellulose paper by 68%, and low-N grass by 15%. Decreases in the functional diversity of the bacterial community were related to the observed decrease in soil respiration, and to the greater effect on decomposition of the lower-quality litter types

Microstructures and Dehydrogenation Properties of Ball-milled MgH2-K2Ti6O13-Ni Composite Systems

Directory of Open Access Journals (Sweden)

ZHANG Jian

2016-11-01

Full Text Available The K2Ti6O13 whisker separate-doped and K2Ti6O13 whisker and Ni powder multi-doped MgH2 hydrogen storage composite systems were prepared by mechanical milling method. The microstructures and dehydrogenation properties of the prepared samples were characterized by some testing methods such as X-ray diffraction (XRD, scanning electron microscope (SEM and differential scanning calorimeter (DSC. The results show that the K2Ti6O13 whisker not only plays the roles in refining the MgH2 crystalline grain, but also inhibit the agglomeration of MgH2 particles in K2Ti6O13 whisker separate-doped system, which results in the decreased dehydrogenation temperature of MgH2 matrix. When the mass ratio of K2Ti6O13 to MgH2 is 3:7, the improvement effect on dehydrogenation properties of MgH2 is the most remarkable. As compared with pure ball-milled MgH2, the dehydrogenation temperature of MgH2 in K2Ti6O13 whisker separate-doped system is decreased by nearly 75℃. For K2Ti6O13 whisker and Ni powder multi-dopedsystem, the dehydrogenation temperature of MgH2 matrix is further decreased compared to K2Ti6O13 whisker separate-doped one due to the dual effects of refined MgH2 crystalline grain by K2Ti6O13 whisker and destabilized MgH2 lattice by Ni solution. As compared with pure ball-milled MgH2, the dehydrogenation temperature of MgH2 in K2Ti6O13 whisker and Ni powder multi-doped system is decreased by nearly 87℃.

Five pesticides decreased oxidation of atmospheric methane in a forest soil

DEFF Research Database (Denmark)

Priemé, Anders; Ekelund, Flemming

2001-01-01

We found that five tested pesticides (the insecticide Dimethoat 40 EC, the herbicide Tolkan, and the fungicides Tilt 250 EC, Tilt Top, and Corbel) decreased the oxidation of atmospheric methane in slurries from a Danish forest soil. Dimethoat 40 EC was the most toxic with an EC50 value (i.......e. the concentration which caused a 50% inhibition of the methane oxidation) of 10 mg active ingredient (AI) l-1, followed by Tilt 250 EC (EC50=56 mg AI l-1). EC50 of Tilt Top was 350 AI mg l-1, the value of Tolkan was 410 mg AI l-1, while Corbel had a value of 1600 mg AI l-1. Dimethoat 40 EC and Tolkan inhibited...

Formation of MgZnO alloy under thermodynamic conditions

Energy Technology Data Exchange (ETDEWEB)

Markevich, I.V.; Stara, T.R., E-mail: stara_t@ukr.net; Kuchuk, A.V.; Polishchuk, Yu.O.; Kladko, V.P.

2014-11-15

Mg{sub x}Zn{sub 1−x}O ceramics with x=0.10, 0.15, 0.20, 0.25 and 0.30 were sintered at T{sub s}=700–1250 °C. Photoluminescence (PL) and PL excitation (PLE) spectra as well as X-ray diffraction patterns were measured at 293 K. Bandgap width was evaluated from the position of PLE peak. Non-monotonous dependence of PLE peak position on T{sub s} was observed for all used x. This effect was concluded to be caused by the formation of cubic phase side by side with hexagonal one and the enhancement of this process with increasing T{sub s}, which resulted in the decrease of Mg content in the hexagonal phase at T{sub s}>1000 °C. Temperature range of 1000–1050 °C was found to be the optimum one for the formation of hexagonal MgZnO alloy at used x. It was shown that x=0.20 was the solubility limit of MgO in hexagonal Mg{sub x}Zn{sub 1−x}O ceramics.

Improved hydrogen sorption kinetics in wet ball milled Mg hydrides

Energy Technology Data Exchange (ETDEWEB)

Meng, Li

2011-05-04

In this work, wet ball milling method is used in order to improve hydrogen sorption behaviour due to its improved microstructure of solid hydrogen materials. Compared to traditional ball milling method, wet ball milling has benefits on improvement of MgH{sub 2} microstructure and further influences on its hydrogen sorption behavior. With the help of solvent tetrahydrofuran (THF), wet ball milled MgH{sub 2} powder has much smaller particle size and its specific surface area is 7 times as large as that of dry ball milled MgH{sub 2} powder. Although after ball milling the grain size is decreased a lot compared to as-received MgH{sub 2} powder, the grain size of wet ball milled MgH{sub 2} powder is larger than that of dry ball milled MgH{sub 2} powder due to the lubricant effect of solvent THF during wet ball milling. The improved particle size and specific surface area of wet ball milled MgH{sub 2} powder is found to be determining its hydrogen sorption kinetics especially at relatively low temperatures. And it also shows good cycling sorption behavior, which decides on its industrial applicability. With three different catalysts MgH{sub 2} powder shows improved hydrogen sorption behavior as well as the cyclic sorption behavior. Among them, the Nb{sub 2}O{sub 5} catalyst is found to be the most effective one in this work. Compared to the wet ball milled MgH{sub 2} powder, the particle size and specific surface area of the MgH{sub 2} powder with catalysts are similar to the previous ones, while the grain size of the MgH{sub 2} with catalysts is much finer. In this case, two reasons for hydrogen sorption improvement are suggested: one is the reduction of the grain size. The other may be as pointed out in some literatures that formation of new oxidation could enhance the hydrogen sorption kinetics, which is also the reason why its hydrogen capacity is decreased compared to without catalysts. After further ball milling, the specific surface area of wet ball milled Mg

Microstructure, mechanical properties, bio-corrosion properties and cytotoxicity of as-extruded Mg-Sr alloys.

Science.gov (United States)

Zhao, Chaoyong; Pan, Fusheng; Zhang, Lei; Pan, Hucheng; Song, Kai; Tang, Aitao

2017-01-01

In this study, as-extruded Mg-Sr alloys were studied for orthopedic application, and the microstructure, mechanical properties, bio-corrosion properties and cytotoxicity of as-extruded Mg-Sr alloys were investigated by optical microscopy, scanning electron microscopy with an energy dispersive X-ray spectroscopy, X-ray diffraction, tensile and compressive tests, immersion test, electrochemical test and cytotoxicity test. The results showed that as-extruded Mg-Sr alloys were composed of α-Mg and Mg 17 Sr 2 phases, and the content of Mg 17 Sr 2 phases increased with increasing Sr content. As-extruded Mg-Sr alloy with 0.5wt.% Sr was equiaxed grains, while the one with a higher Sr content was long elongated grains and the grain size of the long elongated grains decreased with increasing Sr content. Tensile and compressive tests showed an increase of both tensile and compressive strength and a decrease of elongation with increasing Sr content. Immersion and electrochemical tests showed that as-extruded Mg-0.5Sr alloy exhibited the best anti-corrosion property, and the anti-corrosion property of as-extruded Mg-Sr alloys deteriorated with increasing Sr content, which was greatly associated with galvanic couple effect. The cytotoxicity test revealed that as-extruded Mg-0.5Sr alloy did not induce toxicity to cells. These results indicated that as-extruded Mg-0.5Sr alloy with suitable mechanical properties, corrosion resistance and good cytocompatibility was potential as a biodegradable implant for orthopedic application. Copyright © 2016 Elsevier B.V. All rights reserved.

Regulated deficit irrigation can decrease soil CO2 emissions in fruit orchards

Science.gov (United States)

Zornoza, Raul; Acosta, José Alberto; Martínez-Martínez, Silvia; De la Rosa, Jose M.°; Faz, Angel; Pérez-Pastor, Alejandro

2016-04-01

Irrigation water restrictions in the Mediterranean area have created a growing interest in water conservation. Apart from environmental and economic benefits by water savings, regulated deficit irrigation (RDI) may contribute to reduce soil CO2 emissions and enhance C sequestration in soils, by decreasing microbial and root activity in response to decreased soil moisture levels. An experiment was established in four orchards (peach, apricot, Saturn peach and grape) to investigate the effects of regulated deficit irrigation (RDI) on soil CO2 emissions. Two irrigation treatments were assayed: full irrigation (FI), and RDI, irrigated as FI except for postharvest period (peach, apricot, Saturn peach) or post-veraison period (grape) were 50% of FI was applied. The application of deficit caused a significant decrease in CO2 emission rates, with rates in average of 90 mg CO2-C m-2 h-1, 120 mg CO2-C m-2 h-1, 60 mg CO2-C m-2 h-1 and 60 mg CO2-C m-2 h-1 lower than FI during the period when deficit was applied for peach, apricot, Saturn peach and grape. This confirms the high effectiveness of the RDI strategies not only to save water consumption but also to decrease soil CO2 emissions. However, monitoring during longer periods is needed to verify that this trend is long-term maintained, and assess if soil carbon stocks are increase or most CO2 emissions derive from root respiration. Acknowledgements This work has been funded by the European Union LIFE+ project IRRIMAN (LIFE13 ENV/ES/000539).

Molecular beam epitaxy of iodine-doped CdTe and (CdMg)Te

Energy Technology Data Exchange (ETDEWEB)

Fischer, F.; Waag, A.; Litz, Th.; Scholl, S.; Schmitt, M.; Landwehr, G. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Bilger, G. (Zentrum fuer Sonnenenergie und Wasserstofforschung, Stuttgart (Germany))

1994-08-01

The n-type doping of CdTe and (CdMg)Te by the use of the solid dopant source material ZnI[sub 2] is reported. Doping levels as high as 7x10[sup 18] cm[sup -3] have been obtained in CdTe with carrier mobilities around 500 cm[sup 2]/V[center dot]s at room temperature. For a dopant incorporation higher than 1x10[sup 19] cm[sup -3] the free carrier concentration decreases, indicating the onset of a compensation mechanism, which is observed in the case of chlorine and bromine doping, too. Preliminary experiments show that with increasing Mg concentration the free carrier concentration decreases. Nevertheless, CdMgTe with a magnesium concentration x=0.37 (band gap 2.2 eV at room temperature) can be doped up to 2x10[sup 17] cm[sup -3]. The existence of deep donor levels in this CdTe based ternary is not supposed to be the only reason for the reduction of the free carrier concentration. For high Mg support during molecular beam epitaxial (MBE) growth of wide gap (CdMg)Te layers, the ZnI[sub 2] incorporation is reduced, leading to low doping levels, too

Effects in Mg-Zn-based alloys strengthened by quasicrystalline phase

International Nuclear Information System (INIS)

Vlček, M; Čížek, J; Lukáč, F; Melikhova, O; Hruška, P; Procházka, I; Vlach, M; Stulíková, I; Smola, B; Jäger, A

2016-01-01

Magnesium Mg-based alloys are promising lightweight structural materials for automotive, aerospace and biomedical applications. Recently Mg-Zn-Y system attracted a great attention due to a stable icosahedral phase (I-phase) with quasicrystalline structure which is formed in these alloys. Positron lifetime spectroscopy and in situ synchrotron X-ray diffraction were used to study thermal stability of I-phase and precipitation effects in Mg-Zn-Y and Mg- Zn-Al alloys. All alloys containing quasicrystalline I-phase exhibit misfit defects characterized by positron lifetime of ∼ 300 ps. These defects are associated with the interfaces between I- phase particles and Mg matrix. The quasicrystalline I-phase particles were found to be stable up to temperatures as high as ∼ 370°C. The W-phase is more stable and melts at ∼ 420°C. Concentration of defects associated with I-phase decreases after annealing at temperatures above ∼ 300°C. (paper)

Role of dopants in LiF:Mg,Cu, LiF:Mg,P and LiF:Mg,Cu,P detectors

International Nuclear Information System (INIS)

Mohammadi, Kh.; Moussavi Zarandi, A.; Afarideh, H.; Shahmaleki, S.

2013-01-01

In this study, electronic structure of LiF crystal doped with Mg,Cu,P impurities was studied with WIEN2k code on the basis of FPLAPW+lo method. Results show that in Mg-doped LiF composition, an electronic trap was created with impurity concentration of 1.56% and 3.125%. In this condition, the electronic trap with increasing the percentage of the impurities up to 4.687% is annihilated. It was found, that by doping of Mg and Cu or P simultaneously, a hole-trap is created in valence band. It was realized that in LiF:Mg,Cu, LiF:Mg,P and LiF:Mg,Cu,P, Cu impurity and Li atom, have a key role in creation of levels which lead to create electronic and hole traps. Mg impurity and F atom, only have a role in creation of electronic traps. In addition, P impurity has a main role in creation of the electronic and hole traps in LiF:Mg,Cu,P. The activation energy of electronic and hole trap in LiF:Mg,Cu, LiF:Mg,P and LiF:Mg,Cu,P crystalline lattice were obtained as 0.3 and 5.5 eV, 0.92 and 3.4 eV and 0.75 and 3.1 eV, respectively. - Graphical abstract: Figure (a) and (b) shows changes in electronic structure and band gap energy of LiF crystal due to presence of Mg and Cu, Mg and P ions respectively. - Highlights: • Electronic structure of LiF, LiF:Mg,Cu, LiF:Mg,P and LiF:Mg,Cu,P materials were studied with WIEN2K code. • In LiF:Mg,Cu and LiF:Mg,Cu,P, Li atom and Cu impurity have a key role in creation of levels. • F atom and Mg impurity only have a role in creation of electronic traps. • In LiF:Mg,Cu,P, P impurity has a main role in creation of electronic and hole traps

Raman and NMR study in MgO-doped LiNbO3 crystal

International Nuclear Information System (INIS)

Hu, L.J.; Chang, Y.H.; Chang, C.S.; Yang, S.J.; Hu, M.L.; Tse, W.S.

1991-01-01

This paper reports on the MgO-doped LiNbO 3 crystal grown and studied by NMR and Raman techniques. The solubility of MgO in the LiNbO 3 crystal is as much as 30 mole %. It is shown in NMR spectra that the number of Nb 5+ cations at A-site (Li-site) decrease as Mg concentration increased when the Mg content is lower than 5 mole %. The vibration of (NbO 6 ) octahedron and translations involving Li + and Mg 2+ cations motion can be identified by replacing Nb 5+ and Li + cations with Ta 5+ and Mg 2+ cations through Raman spectra. The 115 cm -1 and 151 cm -1 peaks are due to the translational modes of Mg 2+ and Li + cations. The doping mechanisms of MgO are proposed

Insulator layer formation in MgB2 SIS junctions

International Nuclear Information System (INIS)

Shimakage, H.; Tsujimoto, K.; Wang, Z.; Tonouchi, M.

2005-01-01

The dependence of current-voltage characteristics on thin film deposition conditions was investigated using MgB 2 /AlN/NbN SIS junctions. By increasing the substrate temperature in AlN insulator deposition, the current density decreased and the normal resistance increased. The results indicated that an additional insulator layer between the MgB 2 and AlN formed, either before or during the AlN deposition. The thickness of the additional insulator layer was increased with an increase in the AlN deposition temperature. From the dependence of current density on the thickness of AlN in low temperature depositions, the thickness of the additional insulator layer was estimated to be 1-1.5 nm when the AlN insulator was deposited from 0.14 to 0.7 nm. Moreover, with the current density of MgB 2 /AlN/MgB 2 SIS junctions, further insulator layer formation was confirmed

Microstructure, mechanical properties and bio-corrosion properties of Mg-Zn-Mn-Ca alloy for biomedical application

International Nuclear Information System (INIS)

Zhang Erlin; Yang Lei

2008-01-01

Microstructure, mechanical properties and bio-corrosion properties of as-cast Mg-Zn-Mn-Ca alloys were investigated for biomedical application in detail by optical microscopy, scanning electronic microscopy (SEM), mechanical properties testing and electrochemical measurement. SEM and optical microscopy observation indicated that the grain size of the as-cast alloys significantly decreased with the increasing of Ca content up to 0.5 wt.%. Further increasing of Ca content did not refine the grain more. The phase constitute was mainly controlled by the atomic ratio of Zn to Ca. When the ratio was more than 1.0-1.2, the alloy was mainly composed of primary Mg and lamellar eutectic (α-Mg + Ca 2 Mg 6 Zn 3 ), while the alloy was composed of primary Mg and divorced eutectic (α-Mg + Mg 2 Ca + Ca 2 Mg 6 Zn 3 ) when the atomic ratio was less than 1.0-1.2. The yield strength of the as-cast alloy increased but the elongation and the tensile strength increased first and then decreased with the increasing of Ca content. It was thought that Mg 2 Ca phase deteriorated the tensile strength and ductility. Electrochemical measurements indicated that Mg 2 Ca phase improved the corrosion resistance of the as-cast alloy

Microstructures, mechanical properties and corrosion resistances of extruded Mg-Zn-Ca-xCe/La alloys.

Science.gov (United States)

Tong, L B; Zhang, Q X; Jiang, Z H; Zhang, J B; Meng, J; Cheng, L R; Zhang, H J

2016-09-01

Magnesium alloys are considered as good candidates for biomedical applications, the influence of Ce/La microalloying on the microstructure, mechanical property and corrosion performance of extruded Mg-5.3Zn-0.6Ca (wt%) alloy has been investigated in the current study. After Ce/La addition, the conventional Ca2Mg6Zn3 phases are gradually replaced by new Mg-Zn-Ce/La-(Ca) phases (T1'), which can effectively divide the Ca2Mg6Zn3 phase. The Ca2Mg6Zn3/T1' structure in Mg-Zn-Ca-0.5Ce/La alloy is favorably broken into small particles during the extrusion, resulting in an obvious refinement of secondary phase. The dynamic recrystallized grain size is dramatically decreased after 0.5Ce/La addition, and the tensile yield strength is improved, while further addition reverses the effect, due to the grain coarsening. However, the corrosion resistance of extruded Mg-Zn-Ca alloy deteriorates after Ce/La addition, because the diameter of secondary phase particle is remarkably decreased, which increases the amount of cathodic sites and accelerates the galvanic corrosion process. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mg doped InN and confirmation of free holes in InN

International Nuclear Information System (INIS)

Wang, K.; Yamaguchi, T.; Miller, N.; Mayer, M. A.; Haller, E. E.; Iwamoto, R.; Araki, T.; Nanishi, Y.; Yu, K. M.; Walukiewicz, W.; Ager, J. W. III

2011-01-01

We report a systematic investigation on Mg doped InN epilayers grown by radio-frequency plasma-assisted molecular beam epitaxy. Electrolyte capacitance voltage (ECV) combined with thermopower measurements find p-type conduction over an Mg concentration range. For InN:Mg in this p-type 'window' the Seebeck coefficients dramatically change their signs from negative to positive when the thickness of undoped InN interlayer decreases to zero. This notable sign change of Seebeck coefficient explains the previous inconsistency between ECV and thermopower results and confirms the existence of mobile holes in the InN:Mg. Taking into account the undoped InN interlayer, the hole density and mobility are extracted.

Biodegradation Resistance and Bioactivity of Hydroxyapatite Enhanced Mg-Zn Composites via Selective Laser Melting.

Science.gov (United States)

Shuai, Cijun; Zhou, Yuanzhuo; Yang, Youwen; Feng, Pei; Liu, Long; He, Chongxian; Zhao, Mingchun; Yang, Sheng; Gao, Chengde; Wu, Ping

2017-03-17

Mg-Zn alloys have attracted great attention as implant biomaterials due to their biodegradability and biomechanical compatibility. However, their clinical application was limited due to the too rapid degradation. In the study, hydroxyapatite (HA) was incorporated into Mg-Zn alloy via selective laser melting. Results showed that the degradation rate slowed down due to the decrease of grain size and the formation of protective layer of bone-like apatite. Moreover, the grain size continually decreased with increasing HA content, which was attributed to the heterogeneous nucleation and increased number of nucleation particles in the process of solidification. At the same time, the amount of bone-like apatite increased because HA could provide favorable areas for apatite nucleation. Besides, HA also enhanced the hardness due to the fine grain strengthening and second phase strengthening. However, some pores occurred owing to the agglomerate of HA when its content was excessive, which decreased the biodegradation resistance. These results demonstrated that the Mg-Zn/HA composites were potential implant biomaterials.

Effect of Al on Grain Refinement and Mechanical Properties of Mg-3Nd Casting Alloy

Science.gov (United States)

Wang, Lei; Feng, Yicheng; Wang, Liping; Chen, Yanhong; Guo, Erjun

2018-05-01

The effect of Al on the grain refinement and mechanical properties of as-cast Mg-3Nd alloy was investigated systematically by a series of microstructural analysis, solidification analysis and tensile tests. The results show that Al has an obvious refining effect on the as-cast Mg-3Nd alloy. With increasing Al content, the grain size of the as-cast Mg-3Nd alloy decreases firstly, then increases slightly after the Al content reaching 3 wt.%, and the minimum grain size of the Mg-3Nd alloy is 48 ± 4.0 μm. The refining mechanism can be attributed to the formation of Al2Nd particles, which play an important role in the heterogeneous nucleation. The strength and elongation of the Mg-3Nd alloy refined by Al also increase with increasing Al content and slightly decrease when the Al content is more than 3 wt.%, and the strengthening mechanism is attributed to the grain refinement as well as dispersed intermetallic particles. Furthermore, the microstructural thermal stability of the Mg-3Nd-3Al alloy is higher than that of the Mg-3Nd-0.5Zr alloy. Overall, the Mg-3Nd alloy with Al addition is a novel alloy with wide and potential application prospects.

The comparison of the effects of standard 20 mg atorvastatin daily and 20 mg atorvastatin every other day on serum LDL-cholesterol and high sensitive C-reactive protein levels.

Science.gov (United States)

Keleş, Telat; Akar Bayram, Nihal; Kayhan, Tuğba; Canbay, Alper; Sahin, Deniz; Durmaz, Tahir; Ozdemir, Ozcan; Aydoğdu, Sinan; Diker, Erdem

2008-12-01

In this study, we aimed at comparing the effects of standard once daily 20 mg atorvastatin treatment with that of atorvastatin 20 mg administered every other day on serum lipids and high sensitive C-reactive protein (hs-CRP) levels. Sixty-one patients with serum total cholesterol levels of above 200 mg/dl and low density lipoprotein (LDL)--cholesterol levels of above 130 mg/dl were included in this prospective, randomized study. The patients were randomized into daily treatment of 20 mg atorvastatin (standard treatment) and 20 mg atorvastatin every other day (every other day treatment) groups. Before the treatment and at each visit, serum lipids and hs-CRP levels of all the patients were measured. Statistical analyses were performed Chi-square, unpaired t and two-way repeated measurements ANOVA tests. In the every other day treatment group, there was a 36.1% reduction in LDL-cholesterol levels by the end of first month (p0.05). The LDL cholesterol levels of the group receiving 20 mg atorvastatin every day was reduced by %41 by the end of 1 month (pevery other day, there was a 21% decrease in hs-CRP levels compared to the basal measurements at the end of first month (pevery day the decrease in hs-CRP levels at the end of one month was more striking (37%, p0.05). Alternate-day dosing of atorvastatin causes a significant lipid-lowering and antiinflammatory effects similar to that of daily administration and yet may provide some cost savings.

Manganese oxide octahedral molecular sieves as insertion electrodes for rechargeable Mg batteries

KAUST Repository

Rasul, Shahid

2013-11-01

Magnesium has been inserted electrochemically into manganese oxide octahedral molecular sieves (OMS-5 MnO2) at room temperature. Discharge/charge profiles show that a large amount of Mg, i.e., 0.37 Mg/Mn can be inserted electrochemically using 1 M Mg(ClO4)2/AN electrolyte when OMS-5 is prepared in presence of acetylene black. X-ray diffraction analysis and discharge/charge profiles verify that a solid state solution reaction takes place upon Mg insertion into the host lattice with concurrent reduction of Mn4+ to Mn2+. However, upon each reduction of Mn by Mg insertion and resultant dissolution into electrolyte, decrease in the active compound occurs consequently. A low intrinsic electronic conductivity of OMS-5 was suggested to play a vital role in Mg insertion into the host. © 2013 Elsevier Ltd.

Manganese oxide octahedral molecular sieves as insertion electrodes for rechargeable Mg batteries

KAUST Repository

Rasul, Shahid; Suzuki, Shinya; Yamaguchi, Shu; Miyayama, Masaru

2013-01-01

Magnesium has been inserted electrochemically into manganese oxide octahedral molecular sieves (OMS-5 MnO2) at room temperature. Discharge/charge profiles show that a large amount of Mg, i.e., 0.37 Mg/Mn can be inserted electrochemically using 1 M Mg(ClO4)2/AN electrolyte when OMS-5 is prepared in presence of acetylene black. X-ray diffraction analysis and discharge/charge profiles verify that a solid state solution reaction takes place upon Mg insertion into the host lattice with concurrent reduction of Mn4+ to Mn2+. However, upon each reduction of Mn by Mg insertion and resultant dissolution into electrolyte, decrease in the active compound occurs consequently. A low intrinsic electronic conductivity of OMS-5 was suggested to play a vital role in Mg insertion into the host. © 2013 Elsevier Ltd.

Preparation and Hydrogen Storage Properties of Mg-Rich Mg-Ni Ultrafine Particles

Directory of Open Access Journals (Sweden)

Jianxin Zou

2012-01-01

Full Text Available In the present work, Mg-rich Mg-Ni ultrafine powders were prepared through an arc plasma method. The phase components, microstructure, and hydrogen storage properties of the powders were carefully investigated. It is found that Mg2Ni and MgNi2 could be obtained directly from the vapor state reactions between Mg and Ni, depending on the local vapor content in the reaction chamber. A nanostructured MgH2 + Mg2NiH4 hydrogen storage composite could be generated after hydrogenation of the Mg-Ni ultrafine powders. After dehydrogenation, MgH2 and Mg2NiH4 decomposed into nanograined Mg and Mg2Ni, respectively. Thermogravimetry/differential scanning calorimetry (TG/DSC analyses showed that Mg2NiH4 phase may play a catalytic role in the dehydriding process of the hydrogenated Mg ultrafine particles.

Enhanced mechanical properties of an Al–Si–Cu–Mg alloy at 300 °C: Effects of Mg and the Q-precipitate phase

Energy Technology Data Exchange (ETDEWEB)

Farkoosh, A.R., E-mail: amir.rezaeifarkoosh@mail.mcgill.ca; Pekguleryuz, M., E-mail: mihriban.pekguleryuz@mcgill.ca

2015-01-05

Strategies to improve the strength of Al–Si alloys at elevated temperatures can follow two routes: (i) improving the age-hardening behavior and/or (ii) producing effective dispersoid strengthening. In this study, the influence of Mg (in the range of 0.3–0.7 wt%) on the precipitation characteristics and mechanical properties of the Al–7Si–0.5Cu–(Mg) alloy was investigated. Thermodynamic calculations were performed via the CALPHAD method which showed that Q-Al{sub 5}Mg{sub 8}Cu{sub 2}Si{sub 6} is the main thermodynamically stable precipitate at 300 °C. The calculations were validated by transmission electron microscopy and differential scanning calorimetry analyses. Increasing the Mg level from 0.3 wt% to the maximum solubility limit of ∼0.5 wt% increased the amount of the Q-Al{sub 5}Mg{sub 8}Cu{sub 2}Si{sub 6} precipitates at 300 °C by ∼60 wt% and significantly improved the tensile strength and creep resistance at the expense of some ductility. Mg in excess of the solubility limit was seen to remain within the microstructure in the form of the large π-Al{sub 8}FeMg{sub 3}Si{sub 6} and β-Mg{sub 2}Si intermetallics after solution treatment at 530 °C. Cracking of the brittle π-Al{sub 8}FeMg{sub 3}Si{sub 6} intermetallics during deformation was accounted for the decreased ductility of the alloys at high Mg levels. It is concluded that the Mg level can be increased to 0.5 wt% in the A–7Si–0.5Cu alloys to improve strength. However, for elevated temperature applications in which both strength and ductility are required (e.g. Diesel engine), modification of the π-Al{sub 8}FeMg{sub 3}Si{sub 6} intermetallics would be required to improve the ductility of the alloys with high Mg contents.

Mechanical and corrosion properties of binary Mg-Dy alloys for medical applications

Energy Technology Data Exchange (ETDEWEB)

Yang Lei, E-mail: lei.yang@hzg.de [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Yuanding, Huang; Qiuming, Peng; Feyerabend, Frank; Kainer, Karl Ulrich; Willumeit, Regine; Hort, Norbert [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Str. 1, D-21502 Geesthacht (Germany)

2011-12-15

Microstructure, mechanical and corrosion properties of binary magnesium-dysprosium (Mg-5, 10, 15, 20 wt.% Dy) alloys were investigated for medical applications. In the as-cast condition, the distribution of Dy is quite inhomogeneous. Mg-10Dy alloy exhibits a moderate tensile and compression yield strength, and the best elongation and corrosion resistance. After T4 (solutionizing) treatment, the distribution of Dy becomes homogeneous. The tensile and compression yield strength of all Mg-Dy alloys decreases. The elongation remains unchanged, while the corrosion resistance is largely improved after T4 treatment.

Spectroscopic, thermal, and electrical properties of MgO/ polyvinyl pyrrolidone/ polyvinyl alcohol nanocomposites

Science.gov (United States)

Mohammed, Gh.; El Sayed, Adel M.; Morsi, W. M.

2018-04-01

In this study, we aimed to control the optical and electrical properties of polyvinyl alcohol (PVA) in order to broaden its industrial and technological applications, which we achieved by blending PVA with polyvinyl pyrrolidone (PVP) and adding sol-gel prepared MgO nanopowder. The blended film and nanocomposite films were prepared using the solution casting technique. X-ray diffraction analyses showed that the crystallite size was ∼18.4 nm for MgO and the highest degree of crystallinity (XC) in the films was about 24.34% at 1.0 wt% MgO. High resolution transmission electron microscopy determined the nanoribbon morphology of MgO. Scanning electron microscopy (SEM) indicated the uniform distribution of the MgO nanoribbons on the surfaces of the PVA/PVP films. SEM and Fourier transform infrared spectroscopy also confirmed the interaction between the blend and MgO fillers. The effects of the additives on the glass transition (Tg) and melting (Tm) temperatures were evaluated by differential thermal analysis and differential scanning calorimetry. The appearance of one melting point confirmed the miscibility of the two polymers. According to ultraviolet-visible-near infrared spectroscopy measurements, the optical properties and optical constants of PVA could be adjusted by the addition of PVP and MgO, where the optical band gap (Eg) determined for PVA increased with the PVP content, whereas it decreased to 4.8 eV as the MgO content increased. The DC conductivity (σdc) of the films increased whereas the activation energy (Ea) decreased after the addition of MgO, possibly because the nanoribbon shape fixed the preferred conducting pathways. In addition, MgO could break the H-bond in sbnd OH groups of the blends to allow the free movement of the molecular chains.

Density increment and decreased survival of rat red blood cells induced by cadmium

International Nuclear Information System (INIS)

Kunimoto, M.; Miura, T.

1986-01-01

Male Wistar rats were injected with CdCl 2 subcutaneously to examine in vivo effects of Cd on density and survival of red blood cells. During the 7 days after administration of 1.0 mg Cd/kg, the following sequence of events occurred: (1) a progressive increase in the amount of more dense red blood cells concomitant with a decrease in that of light red blood cells from the first to the third day; (2) an increase in the spleen weight at the third day; (3) a decrease in the hematocrit value and an increase in the amount of light red blood cells at the fifth day; and (4) a recovery of the hematocrit value at the seventh day. Five days after administration, the hematocrit value decreased in a dose-dependent mode and the decrease was significant at the 1% level at 1.0 and 1.5 mg Cd/kg. A highly significant splenomegaly was also observed at 0.5 to 1.5 mg Cd/kg. In order to label red blood cells in vivo, [ 3 H] diisopropylfluorophosphate ([ 3 H]DFP) was injected into rats. At Day 11, Cd at either 0.5 or 1.0 mg/kg was administered to [ 3 H]DFP-prelabeled animals. Cd administration accelerated 3 H-labeled red cell clearance from the blood. Six days after Cd administration, the radioactivity of red blood cells was 76 and 68% of the control at 0.5 and 1.0 mg Cd/kg, respectively. In vitro treatment of rat red density and accelerated in vivo clearance of red blood cells from the recipient circulation. These results show that Cd at low dose can cause anemia by increasing red cell density and by accelerating red cell sequestration, presumably in the spleen

Technical Report on the Impact of MgO on Defense Waste Processing Facility

International Nuclear Information System (INIS)

Schultz, R.L.

2000-01-01

The purpose of this study was to determine the effect(s) of removing MgO from DWPF frits to assess the impact on liquidus temperature and the durability of the glass product. Removal of MgO from the frit was hypothesized to lead to a decrease in liquidus temperature and thereby allow increased waste loading

Luminescent and structural properties of Zn_xMg_1_-_xWO_4 mixed crystals

International Nuclear Information System (INIS)

Krutyak, N.; Nagirnyi, V.; Spassky, D.; Tupitsyna, I.; Dubovik, A.; Belsky, A.

2016-01-01

The structural and luminescent properties of perspective scintillating Zn_xMg_1_-_xWO_4 mixed crystals were studied. The following characteristics were found to depend linearly on x value: the energy of several vibrational modes detected by Raman spectroscopy, the bandgap width deduced from the shift of the excitation spectrum onset of a self-trapped exciton (STE) emission, the position of thermally stimulated luminescence peaks. It is also shown that the thermal stability of the STE luminescence decreases gradually when x decreases. These data indicate that each Zn_xMg_1_-_xWO_4 mixed crystal is not a mixture of two constituents, but possesses its original crystalline structure, as well as optical and luminescent properties. - Highlights: • The structural and luminescent properties of Zn_xMg_1_-_xWO_4 were studied. • The energy of Raman modes, the bandgap width, TSL peak position linearly depend on x. • Each Zn_xMg_1_-_xWO_4 possesses its original crystalline structure.

Re-examining the 26Mg(α ,α')26Mg reaction: Probing astrophysically important states in 26Mg

Science.gov (United States)

Adsley, P.; Brümmer, J. W.; Li, K. C. W.; Marín-Lámbarri, D. J.; Kheswa, N. Y.; Donaldson, L. M.; Neveling, R.; Papka, P.; Pellegri, L.; Pesudo, V.; Pool, L. C.; Smit, F. D.; van Zyl, J. J.

2017-11-01

Background: The 22Ne(α ,n )25Mg reaction is one of the neutron sources for the s process in massive stars. The properties of levels in 26Mg above the α -particle threshold control the strengths of the 22Ne(α ,n )25Mg and 22Ne(α ,γ )26Mg reactions. The strengths of these reactions as functions of temperature are one of the major uncertainties in the s process. Purpose: Information on the existence, spin, and parity of levels in 26Mg can assist in constraining the strengths of the 22Ne(α ,γ )26Mg and 22Ne(α ,n )25Mg reactions, and therefore in constraining s -process abundances. Methods: Inelastically scattered α particles from a 26Mg target were momentum-analyzed in the K600 magnetic spectrometer at iThemba LABS, South Africa. The differential cross sections of states were deduced from the focal-plane trajectory of the scattered α particles. Based on the differential cross sections, spin and parity assignments to states are made. Results: A newly assigned 0+ state was observed in addition to a number of other states, some of which can be associated with states observed in other experiments. Some of the deduced Jπ values of the states observed in the present study show discrepancies with those assigned in a similar experiment performed at RCNP Osaka. The reassignments and additions of the various states can strongly affect the reaction rate at low temperatures. Conclusion: The number, location, and assignment of levels in 26Mg that may contribute to the 22Ne+α reactions are not clear. Future experimental investigations of 26Mg must have an extremely good energy resolution to separate the contributions from different levels. Coincidence experiments of 26Mg provide a possible route for future investigations.

Structural and magnetic properties of Mg-Zn ferrites (Mg1−xZnxFe2O4) prepared by sol-gel method

International Nuclear Information System (INIS)

Reyes-Rodríguez, Pamela Yajaira; Cortés-Hernández, Dora Alicia; Escobedo-Bocardo, José Concepción; Almanza-Robles, José Manuel; Sánchez-Fuentes, Héctor Javier; Jasso-Terán, Argentina; De León-Prado, Laura Elena; Méndez-Nonell, Juan; Hurtado-López, Gilberto Francisco

2017-01-01

In this study, the Mg 1−x Zn x Fe 2 O 4 nanoparticles (x=0–0.9) were prepared by sol-gel method. These ferrites exhibit an inverse spinel structure and the lattice parameter increases as the substitution of Zn 2+ ions is increased. At lower Zn content (0.1≤x≤0.5), saturation magnetization (Ms) increases, while it decreases at higher Zn content (x≥6). The remnant magnetization (0.17–2.0 emu/g) and coercive field (6.0–60 Oe) indicate a ferrimagnetic behavior. The average core diameter of selected ferrites is around 15 nm and the nanoparticles morphology is quasi spherical. The heating ability of some Mg 0.9 Zn 0.1 Fe 2 O 4 and Mg 0.7 Zn 0.3 Fe 2 O 4 aqueous suspensions indicates that the magnetic nanoparticles can increase the medium temperature up to 42 °C in a time less than 10 min - Highlights: • Magnetic nanoparticles of Mg 1−x Zn x Fe 2 O 4 were synthesized by sol-gel method. • Nanoparticles showing a single spinel crystalline structure were obtained. • Aqueous suspensions of Mg 0.7 Zn 0.3 Fe 2 O 4 and Mg 0.9 Zn 0.1 Fe 2 O 4 show heating ability.

Evolution of Mg-5Al-0.4Mn microstructure after rare earth elements addition

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A. Żydek

2011-04-01

Full Text Available Mg-5Al-0.4Mn-xRE (x = 0, 1, 2, 3 wt.% magnesium alloys were prepared successfully by casting method. The microstructure wasinvestigated by light microscopy. The influence of rare earth (RE elements on the area fraction of eutectic was analysed. The obtainedresults revealed that the as-cast Mg-5Al-0.4Mn alloy consist of α - Mg matrix and eutectic α + γ (where γ is Mg17Al12. However, whilerare earth elements were added to the Mg-Al type alloy, Al11RE3 precipitates were formed. The amount of the Al11RE3 precipitatesincreased with increasing addition of RE, but the amount of γ - Mg17Al12 decreased.

Defect induced ferromagnetism in MgO nanoparticles studied by optical and positron annihilation spectroscopy

Science.gov (United States)

Kumar, Nitesh; Sanyal, D.; Sundaresan, A.

2009-08-01

Positron annihilation spectroscopy has been used to explore the nature of defects and to estimate the defect concentrations in ferromagnetic MgO nanoparticles. Our experimental results show that Mg vacancies or Mg vacancy concentration are present approximately at the concentration of 3.4 × 10 16 cm -3 in the nano-crystalline MgO which is twice the value that obtained for bulk sample. This is in correlation with the decrease of the intensity of blue luminescence and the saturation magnetic moment with increasing particle size. These results clearly demonstrate that the origin of magnetic moment and thus the ferromagnetism in MgO nanoparticles is due to Mg related vacancies at the surface of the particles.

31P-NMR measurements of ATP, ADP, 2,3-diphosphoglycerate and Mg2+ in human erythrocytes.

Science.gov (United States)

Petersen, A; Kristensen, S R; Jacobsen, J P; Hørder, M

1990-08-17

Absolute 31P-NMR measurements of ATP, ADP and 2,3-diphosphoglycerate (2,3-DPG) in oxygenated and partly deoxygenated human erythrocytes, compared to measurements by standard assays after acid extraction, show that ATP is only 65% NMR visible, ADP measured by NMR is unexpectedly 400% higher than the enzymatic measurement and 2,3-DPG is fully NMR visible, regardless of the degree of oxygenation. These results show that binding to hemoglobin is unlikely to cause the decreased visibility of ATP in human erythrocytes as deoxyhemoglobin binds the phosphorylated metabolites more tightly than oxyhemoglobin. The high ADP visibility is unexplained. The levels of free Mg2+ [( Mg2+]free) in human erythrocytes are 225 mumol/l at an oxygen saturation of 98.6% and instead of the expected increase, the level decreased to 196 mumol/l at an oxygen saturation of 38.1% based on the separation between the alpha- and beta-ATP peaks. [Mg2+]free in the erythrocytes decreased to 104 mumol/l at a high 2,3-DPG concentration of 25.4 mmol/l red blood cells (RBC) and a normal ATP concentration of 2.05 mmol/l RBC. By increasing the ATP concentration to 3.57 mmol/l RBC, and with a high 2,3-DPG concentration of 24.7 mmol/l RBC, the 31P-NMR measured [Mg2+]free decreased to 61 mumol/l. These results indicate, that the 31P-NMR determined [Mg2+]free in human erythrocytes, based solely on the separation of the alpha- and beta-ATP peaks, does not give a true measure of intracellular free Mg2+ changes with different oxygen saturation levels. Furthermore the measurement is influenced by the concentration of the Mg2+ binding metabolites ATP and 2,3-DPG. Failure to take these factors into account when interpreting 31P-NMR data from human erythrocytes may explain some discrepancies in the literature regarding [Mg2+]free.

The Raman spectrum and lattice parameters of MgB2 as a function of temperature

International Nuclear Information System (INIS)

Shi Lei; Zhang Huarong; Chen Lin; Feng Yong

2004-01-01

The temperature dependences of the Raman spectrum and lattice parameters of polycrystalline MgB 2 have been investigated by means of Raman spectroscopy and x-ray diffraction. It is found that the lattice parameters show an approximately linear change with the temperature decrease, giving different thermal expansions along the a- and c-axes, which is caused by the comparatively weak metal-boron bonding in MgB 2 . The grain size of MgB 2 determined by means of x-ray diffraction is around 45 nm for both [100] and [001] directions. There is no evidence for any structural transition while the temperature changes from 300 K down to 12 K. An anomalous Raman band at 603 cm -1 is observed, which is consistent with the theoretical prediction for the E 2g in-plane boron stretching mode. The Raman frequency increases and the linewidth decreases as the temperature decreases. A possible origin of the temperature dependences of the Raman frequency and the linewidth is discussed. It is suggested that the grain size effect of MgB 2 on the nanometric scale will have a clear influence on the frequency and the linewidth of the Raman spectrum

Optical absorption and thermoluminescence in Mg O, Mg O:Ni and Mg O:Li irradiated at room temperature; Absorcion optica y termoluminiscencia en MgO, MgO:Ni y MgO:Li irradiados a temperatura ambiente

Energy Technology Data Exchange (ETDEWEB)

Delgado, L

1984-07-01

Optical absorption and thermoluminescence (TL) studies in Mg O, Mg O:Ni and Mg O:Li irradiated at room temperature are presented. In pure Mg O the thermal annihilation of Fe3+ by recombination with thermally released electrons at {approx} 90 and 175 degree centigree and the V center annealing by hole release up to 100 degree centigree cause the observed glow peaks at these temperatures. The TL excitation spectrum shows two maxima at 245 nm (electron center) and 288 nm (Fe3+). In Mg O:Ni X irradiation induces Fe{sup 2}+ {yields}- Fe{sup 3}+ and Ni{sup 2}+ {yields} Ni{sup 3}+ oxidations. Two TL emission bands centered at 110 degree centigree (red) and 80 o{sup C} (green) are assigned to electron release and their recombination at Fe{sup 3}+ and Ni{sup 3}+ respectively. In Mg O:Li two TL emission bands, one blue (430 nm) and the other red (730 nm) with excitation maxima at 245 nm (electron center) and 200 nm (hole center) respectively are observed. No V-center formation was detected in both Ni and Li doped samples. (Author) 42 refs.

Multimicronutrient supplementation in older persons decreased zinc deficiency but not serum TNF-á

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Elly Herwana

2011-08-01

Full Text Available The increase in the population of older persons needs to be accompanied by increased quality of healthcare in older persons, particularly a decrease in the incidence of infections. Impaired immune responses are common in older adults, and immune senescence likely contributes to the increased incidence of infectious diseases in the older persons. The aging process decreases the immune response and many studies have been conducted to explain the role of supplementation with various micronutrients, such as vitamin C, vitamin E, â-carotene and zinc, on the immune response. The aim of the present study was to assess the influence of 6 months of multi-micronutrient (MMN supplementation on zinc and tumor necrosis factor (TNF-á levels in older persons. A randomized controlled trial was conducted on 78 older persons, who were divided into two groups. The treatment group received MMN supplementation containing 40 mg elemental zinc, 120 mg ascorbic acid, 6 mg â-carotene, 15 mg á-tocopherol and 400 ìg folic acid and the control group 400 mg calcium carbonate. The study did not demonstrate that 6 months of MMN supplementation resulted in significant differences between both groups, with respect to total protein, albumin, globulin, and TNF-á levels. In contrast, MMN supplementation significantly decreased the proportion of older persons with zinc deficiency in the treatment group, in comparison with the control group. The present data suggest that in older persons with relatively good immune and protein status, improvement of the immune status by MMN supplementation may be difficult and at best limited.

Preparation, characterization and gas permeation study of PSf/MgO nanocomposite membrane

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S. M. Momeni

2013-09-01

Full Text Available Nanocomposite membranes composed of polymer and inorganic nanoparticles are a novel method to enhance gas separation performance. In this study, membranes were fabricated from polysulfone (PSf containing magnesium oxide (MgO nanoparticles and gas permeation properties of the resulting membranes were investigated. Membranes were prepared by solution blending and phase inversion methods. Morphology of the membranes, void formations, MgO distribution and aggregates were observed by SEM analysis. Furthermore, thermal stability, residual solvent in the membrane film and structural ruination of membranes were analyzed by thermal gravimetric analysis (TGA. The effects of MgO nanoparticles on the glass transition temperature (Tg of the prepared nanocomposites were studied by differential scanning calorimetry (DSC. The Tg of nanocomposite membranes increased with MgO loading. Fourier transform infrared (FTIR spectra of nanocomposite membranes were analyzed to identify the variations of the bonds. The results obtained from gas permeation experiments with a constant pressure setup showed that adding MgO nanoparticles to the polymeric membrane structure increased the permeability of the membranes. At 30 wt% MgO loading, the CO2 permeability was enhanced from 25.75×10-16 to 47.12×10-16 mol.m/(m².s.Pa and the CO2/CH4 selectivity decreased from 30.84 to 25.65 when compared with pure PSf. For H2, the permeability was enhanced from 44.05×10-16 to 67.3×10-16 mol.m/(m².s.Pa, whereas the H2/N2 selectivity decreased from 47.11 to 33.58.

The Microstructure and Tensile Properties of a Newly Developed Mg-Al/Mg3Sb2 In Situ Composite in As-Cast and Extruded Conditions

Science.gov (United States)

Montajabnia, A.; Pourbahari, B.; Emamy, M.

2018-04-01

The microstructures and tensile properties of Mg-x wt%Al-y wt%Sb alloys have been studied where x/y ratio was 1 and Sb(Al) contents were 5, 10, 15 and 20 wt%, respectively. The results indicated that by increasing Sb(Al) content, not only the crystals of primary Mg3Sb2 alter from small flake-like particles to polygonal or needle-like morphology, but also the eutectic structure changes from semi-continuous network in Mg-5Al-5Sb to continuous network in Mg-20Sb-20Al alloy. The results obtained from thermal analysis revealed different peaks related to the formation of Mg3Sb2 as primary phase and eutectic structure containing Mg17Al12 + Al3Mg2 intermetallic phases. Further results also revealed that Sb(Al) additions change the solidification performance of the material by depressing the Mg3Sb2 nucleation temperature, reducing solidification range and widening eutectic area. Tensile testing results showed that with the increase in Sb (Al) content, ultimate tensile strength (UTS) and elongation values of the alloys are decreased in as-cast condition. But, significant improvement in the UTS and elongation values of the extruded specimens was attributed to the severe fragmentation of intermetallic phases and well distributed fine particles in the matrix which provided proper obstacles for dislocation motion. It was interesting to note that the fracture behavior of intermetallic particles was found to be different, while Mg3Sb2 was ductile, intermetallic compounds in eutectic regions were brittle.

Mitochondrial DNA variation, but not nuclear DNA, sharply divides morphologically identical chameleons along an ancient geographic barrier.

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Dan Bar Yaacov

Full Text Available The Levant is an important migration bridge, harboring border-zones between Afrotropical and palearctic species. Accordingly, Chameleo chameleon, a common species throughout the Mediterranean basin, is morphologically divided in the southern Levant (Israel into two subspecies, Chamaeleo chamaeleon recticrista (CCR and C. c. musae (CCM. CCR mostly inhabits the Mediterranean climate (northern Israel, while CCM inhabits the sands of the north-western Negev Desert (southern Israel. AFLP analysis of 94 geographically well dispersed specimens indicated moderate genetic differentiation (PhiPT = 0.097, consistent with the classical division into the two subspecies, CCR and CCM. In contrast, sequence analysis of a 637 bp coding mitochondrial DNA (mtDNA fragment revealed two distinct phylogenetic clusters which were not consistent with the morphological division: one mtDNA cluster consisted of CCR specimens collected in regions northern of the Jezreel Valley and another mtDNA cluster harboring specimens pertaining to both the CCR and CCM subspecies but collected southern of the Jezreel Valley. AMOVA indicated clear mtDNA differentiation between specimens collected northern and southern to the Jezreel Valley (PhiPT = 0.79, which was further supported by a very low coalescent-based estimate of effective migration rates. Whole chameleon mtDNA sequencing (∼17,400 bp generated from 11 well dispersed geographic locations revealed 325 mutations sharply differentiating the two mtDNA clusters, suggesting a long allopatric history further supported by BEAST. This separation correlated temporally with the existence of an at least 1 million year old marine barrier at the Jezreel Valley exactly where the mtDNA clusters meet. We discuss possible involvement of gender-dependent life history differences in maintaining such mtDNA genetic differentiation and suggest that it reflects (ancient local adaptation to mitochondrial-related traits.

Composite Cu/Fe/MgB{sub 2} superconducting wires and MgB{sub 2}/YSZ/Hastelloy coated conductors for ac and dc applications

Energy Technology Data Exchange (ETDEWEB)

Glowacki, B A [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge (United Kingdom); Majoros, M [Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge (United Kingdom); Vickers, M [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge (United Kingdom); Eisterer, M [Atomic Institute of the Austrian Universities, A-1020 Vienna (Austria); Toenies, S [Atomic Institute of the Austrian Universities, A-1020 Vienna (Austria); Weber, H W [Atomic Institute of the Austrian Universities, A-1020 Vienna (Austria); Fukutomi, M [National Institute for Materials Science, Superconducting Materials Center, 1-2-1, Sengen, Ibaraki (Japan); Komori, K [National Institute for Materials Science, Superconducting Materials Center, 1-2-1, Sengen, Ibaraki (Japan); Togano, K [National Institute for Materials Science, Superconducting Materials Center, 1-2-1, Sengen, Ibaraki (Japan)

2003-02-01

We discuss the results of a study of MgB{sub 2} multifilamentary conductors and coated conductors from the point of view of their future dc and ac applications. The correlation between the slope of the irreversibility line induced by neutron irradiation defects and in situ structural imperfections and the critical temperature and critical current density is discussed with respect to the conductor performance and applicability. We debate the possible origin of the observed anomalous decrease of ac susceptibility at 50 K in copper clad in situ powder-in-tube MgB{sub 2} wires. Different conductor preparation methods and conductor architectures, and attainable critical current densities are presented. Some numerical results on critical currents, thermal stability and ac losses of future MgB{sub 2} multifilamentary and coated conductors with magnetic cladding of their filaments are also discussed.

Biodegradation Resistance and Bioactivity of Hydroxyapatite Enhanced Mg-Zn Composites via Selective Laser Melting

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Cijun Shuai

2017-03-01

Full Text Available Mg-Zn alloys have attracted great attention as implant biomaterials due to their biodegradability and biomechanical compatibility. However, their clinical application was limited due to the too rapid degradation. In the study, hydroxyapatite (HA was incorporated into Mg-Zn alloy via selective laser melting. Results showed that the degradation rate slowed down due to the decrease of grain size and the formation of protective layer of bone-like apatite. Moreover, the grain size continually decreased with increasing HA content, which was attributed to the heterogeneous nucleation and increased number of nucleation particles in the process of solidification. At the same time, the amount of bone-like apatite increased because HA could provide favorable areas for apatite nucleation. Besides, HA also enhanced the hardness due to the fine grain strengthening and second phase strengthening. However, some pores occurred owing to the agglomerate of HA when its content was excessive, which decreased the biodegradation resistance. These results demonstrated that the Mg-Zn/HA composites were potential implant biomaterials.

Modeling and stabilities of Mg/MgH2 interfaces: A first-principles investigation

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Jia-Jun Tang

2014-07-01

Full Text Available We have theoretically investigated the modeling and the structural stabilities of various Mg/MgH2 interfaces, i.e. Mg(101¯0/MgH2(210, Mg(0001/MgH2(101 and Mg(101¯0/MgH2(101, and provided illuminating insights into Mg/MgH2 interface. Specifically, the main factors, which impact the interfacial energies, are fully considered, including surface energies of two phases, mutual lattice constants of interface model, and relative position of two phases. The surface energies of Mg and MgH2, on the one hand, are found to be greatly impacting the interfacial energies, reflected by the lowest interfacial energy of Mg(0001/MgH2(101 which is comprised of two lowest energy surfaces. On the other hand, it is demonstrated that the mutual lattice constants and the relative position of two phases lead to variations of interfacial energies, thus influencing the interface stabilities dramatically. Moreover, the Mg-H bonding at interface is found to be the determinant of Mg/MgH2 interface stability. Lastly, interfacial and strain effects on defect formations are also studied, both of which are highly facilitating the defect formations. Our results provide a detailed insight into Mg/MgH2 interface structures and the corresponding stabilities.

Anisotropic Mg Electrodeposition and Alloying with Ag-based Anodes from Non-Coordinating Mixed-Metal Borohydride Electrolytes for Mg Hybrid Batteries

International Nuclear Information System (INIS)

Wetzel, David J.; Malone, Marvin A.; Gewirth, Andrew A.; Nuzzo, Ralph G.

2017-01-01

A highly anisotropic electrodeposition was observed using the hybrid battery electrolyte Mg(BH 4 ) 2 with LiBH 4 in diglyme. At low overpotentials high aspect ratio platelet morphologies are observed with a strong fiber texture composed of a {10-10} and a {11-20} component, the first evidence of behavior of this kind in magnesium battery electrolytes. At high overpotentials the deposit aspect ratio is indistinguishable but the texture is shown to be primarily composed of a {11-20} fiber texture. The kinetic parameters relative to the relevant crystallographic faces are extracted from electron microscopy images and compared with the observed bulk rate extracted from the electrochemical data. The use of polycrystalline Ag foil substrates with little preferred orientation at the surface allowed highly polycrystalline nucleation at lower overpotentials than that of platinum, likely due to Ag alloying with Mg. Characterization using focused ion beam (FIB) cross-sections with Auger Electron Spectroscopy (AES) elemental analysis confirm that the deposits are primarily Mg although Mg‐Ag alloys of various compositions were observed. It is proposed that the orientation at slow rates of growth is due to the underlying kinetics of adatom diffusion on Mg and that higher rates diminish the phenomenon due to decreased time for adatom diffusion and instead are governed by the rates of adatom formation or more specifically the adatom vacancy formation on the different low-index planes of Mg.

Effectiveness of Shelled Almonds in Decreasing Blood Lipid and Lipoprotein Levels of Hyperlipidemic Patients

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H Mozaffari

2008-10-01

Full Text Available Introduction: Hyperlipidemia is a risk factor for atherosclerosis and cardiovascular diseases. Nuts such as almonds are high in unsaturated lipids and antioxidants. Some studies indicate that nuts have beneficial effects on cardiovascular system. Therefore, the aim of this study was evaluation of the effectiveness of shelled almonds on reduction of blood lipid and lipoprotein levels in hyperlipidemic patients. Methods: This study was a clinical trial (before and after and was done on 30 men volunteering for the study. They consumed 60 grams shelled almonds per day for four weeks. Their blood lipid, lipoprotein, apolipoprotein and lipoprotein (a levels were measured after and before almond consumption. Results: Shelled almond consumption caused significant decrease in serum cholesterol 36.1 mg/dl, triglyceride 45.94 mg/dl, LDL-cholesterol 28.68 mg/dl and increase in HDL-cholesterol 10.64 mg/dl(p<0.001. Shelled almond consumption decreased lipoprotein (a (2.11 mg/dl, apolipoprotein B100 (8.93 mg/dl and increased apolipoprotein A (1 1.74 mg/dl levels, but this effect was insignificant statistically. Conclusion: Continuous consumption of shelled almonds has beneficial effect on blood lipids and may play a preventive role in Atherosclerosis and coronary heart diseases. We therefore suggest that a daily intake of 60 grams of almonds can be used for treatment of hyprelipidemic patients.

ß-Adrenergic Stimulation Increases RyR2 Activity via Intracellular Ca2+ and Mg2+ Regulation

Science.gov (United States)

Li, Jiao; Imtiaz, Mohammad S.; Beard, Nicole A.; Dulhunty, Angela F.; Thorne, Rick; vanHelden, Dirk F.; Laver, Derek R.

2013-01-01

Here we investigate how ß-adrenergic stimulation of the heart alters regulation of ryanodine receptors (RyRs) by intracellular Ca2+ and Mg2+ and the role of these changes in SR Ca2+ release. RyRs were isolated from rat hearts, perfused in a Langendorff apparatus for 5 min and subject to 1 min perfusion with 1 µM isoproterenol or without (control) and snap frozen in liquid N2 to capture their phosphorylation state. Western Blots show that RyR2 phosphorylation was increased by isoproterenol, confirming that RyR2 were subject to normal ß-adrenergic signaling. Under basal conditions, S2808 and S2814 had phosphorylation levels of 69% and 15%, respectively. These levels were increased to 83% and 60%, respectively, after 60 s of ß-adrenergic stimulation consistent with other reports that ß-adrenergic stimulation of the heart can phosphorylate RyRs at specific residues including S2808 and S2814 causing an increase in RyR activity. At cytoplasmic [Ca2+] adrenergic stimulation increased luminal Ca2+ activation of single RyR channels, decreased luminal Mg2+ inhibition and decreased inhibition of RyRs by mM cytoplasmic Mg2+. At cytoplasmic [Ca2+] >1 µM, ß-adrenergic stimulation only decreased cytoplasmic Mg2+ and Ca2+ inhibition of RyRs. The Ka and maximum levels of cytoplasmic Ca2+ activation site were not affected by ß-adrenergic stimulation. Our RyR2 gating model was fitted to the single channel data. It predicted that in diastole, ß-adrenergic stimulation is mediated by 1) increasing the activating potency of Ca2+ binding to the luminal Ca2+ site and decreasing its affinity for luminal Mg2+ and 2) decreasing affinity of the low-affinity Ca2+/Mg2+ cytoplasmic inhibition site. However in systole, ß-adrenergic stimulation is mediated mainly by the latter. PMID:23533585

Characterization Of Mg(OH)2 Precipitation On MSF Desalination Process

International Nuclear Information System (INIS)

Sumijanto

2000-01-01

The experiment of Mg(OH) sub.2 precipitation has been carry out. Experiment took please by heating sea water simulation with consist of 142 ppm bicarbonate and magnesium ion at temperature 40, 50, 60, 70, 80, 90, 100, 110, and 120 exp.oC respectively by using autoclave. Sampling has been done periodical for 30 minute in interval 300 minute for each temperature. The calculation of Mg(OH) sub.2 precipitation through the decreasing of magnesium concentration with analysis by AAS. From experiment data have the information that Mg(OH) sub.2 precipitation have been formed since 40 exp.oC. From time variable have been the information that the precipitation formed at 30th minute rapidly. Whether at further time the increasing of precipitation are not significant. This phenomena can explained that at each heating step from 40 exp.oC bicarbonate ion be come decomposition with the result carbonate and hydroxide ion and react with magnesium form Mg(OH) sub.2

Transformation of Mg-bearing amorphous calcium carbonate to Mg-calcite - In situ monitoring

Science.gov (United States)

Purgstaller, Bettina; Mavromatis, Vasileios; Immenhauser, Adrian; Dietzel, Martin

2016-02-01

The formation of Mg-bearing calcite via an amorphous precursor is a poorly understood process that is of relevance for biogenic and abiogenic carbonate precipitation. In order to gain an improved insight on the controls of Mg incorporation in calcite formed via an Mg-rich amorphous calcium carbonate (Mg-ACC) precursor, the precipitation of Mg-ACC and its transformation to Mg-calcite was monitored by in situ Raman spectroscopy. The experiments were performed at 25.0 ± 0.03 °C and pH 8.3 ± 0.1 and revealed two distinct pathways of Mg-calcite formation: (i) At initial aqueous Mg/Ca molar ratios ⩽ 1:6, Mg-calcite formation occurs via direct precipitation from solution. (ii) Conversely, at higher initial Mg/Ca molar ratios, Mg-calcite forms via an intermediate Mg-rich ACC phase. In the latter case, the final product is a calcite with up to 20 mol% Mg. This Mg content is significant higher than that of the Mg-rich ACC precursor phase. Thus, a strong net uptake of Mg ions from the solution into the crystalline precipitate throughout and also subsequent to ACC transformation is postulated. Moreover, the temporal evolution of the geochemical composition of the reactive solution and the Mg-ACC has no significant effect on the obtained ;solubility product; of Mg-ACC. The enrichment of Mg in calcite throughout and subsequent to Mg-ACC transformation is likely affected by the high aqueous Mg/Ca ratio and carbonate alkalinity concentrations in the reactive solution. The experimental results have a bearing on the formation mechanism of Mg-rich calcites in marine early diagenetic environments, where high carbonate alkalinity concentrations are the rule rather than the exception, and on the insufficiently investigated inorganic component of biomineralisation pathways in many calcite secreting organisms.

Effect of Adding Elements on Microstructure of Mg-3Si Alloy

Directory of Open Access Journals (Sweden)

CUI Bin

2017-03-01

Full Text Available The microstructure of alloy Mg-3Si(mass fraction/%, same as below after successive additions with different elements of Zn, Nd, Gd and Y was observed and the microstructure evolution was investigated by scanning electron microscopy and X-ray diffraction. The results show the primary Mg2Si particles co-exist with eutectic Mg2Si particles in binary alloy Mg-Si. With minor addition of Zn element, only primary Mg2Si can be found in ternary Mg-3Si-3Zn system while eutectic Mg2Si particles disappear. In quaternary alloy Mg-2.0Nd-3.0Zn-3.0Si, the addition of Nd element can effectively refine the primary Mg2Si particles and form some Mg41Nd5 particles. After continuous adding of Gd and Y elements into quaternary system, Gd5Si3 and YSi particles increase significantly in the alloy Mg-8.0Gd-4.0Y-2.0Nd-3.0Zn-3.0Si, while volume fraction of primary Mg2Si decrease significantly. Thermo-Calc calculation predicts that the Gibbs free energy for primary particles Gd5Si3, YSi is lower, and therefore Gd, Y atom and Si are more likely to form compounds. In Mg-8Gd-4Y-2Nd-3Zn-3Si alloy, room temperature Gibbs free energy for primary particles Mg2Si, Gd5Si3, YSi is -9.56×104, -8.72×104, -2.83×104J/mol, respectively, and the mass fraction of these particles is 8.07%, 5.27%, 1.40% respectively.

Adsorption of Na, Mg, and Al atoms on BN nanotubes

Energy Technology Data Exchange (ETDEWEB)

Beheshtian, Javad [Department of Chemistry, Shahid Rajaee Teacher Training University, P.O. Box: 16875-163, Tehran (Iran, Islamic Republic of); Peyghan, Ali Ahmadi, E-mail: ahmadi.iau@gmail.com [Young Researchers Club, Islamic Azad University, Islamshahr Branch, Tehran (Iran, Islamic Republic of); Bagheri, Zargham [Physics group, Science department, Islamic Azad University, Islamshahr Branch, P.O. Box: 33135-369, Islamshahr, Tehran (Iran, Islamic Republic of)

2012-12-30

Adsorption of three metals (Na, Mg, and Al) on the surface of BN nanotubes (BNNT) has been investigated by using density functional theory. Adsorption energies for Na and Al atoms have been calculated to be about - 0.22 to - 0.61 eV, respectively. Upon the metal adsorption, energy gap between highest occupied and lowest unoccupied orbitals of the tube is dramatically decreased, resulting in enhanced electrical conductivity. However, in the case of Mg atom, the low adsorption energy cannot change electronic property of the tube. The semi-conductive BNNT transform to n-type semiconductor after adsorption of Na atom. The metal adsorption modifies work function of the BNNT and consequently the field-emission current densities of metal-BNNT may be significantly enhanced. - Highlights: Black-Right-Pointing-Pointer Adsorption of Na, Mg, and Al atoms on the BN nanotubes (BNNT) was studied. Black-Right-Pointing-Pointer Adsorption energies for Na and Al atoms are about - 0.22 to - 0.61 eV, respectively. Black-Right-Pointing-Pointer Energy gap of the tube dramatically decreases upon the metals adsorption. Black-Right-Pointing-Pointer Semiconductor BNNT transform to n-type ones upon adsorption of Na and Al atoms. Black-Right-Pointing-Pointer The field-emission current densities of metal-BNNT may be significantly enhanced.

Sputter-deposited Mg-Al-O thin films: linking molecular dynamics simulations to experiments

International Nuclear Information System (INIS)

Georgieva, V; Bogaerts, A; Saraiva, M; Depla, D; Jehanathan, N; Lebelev, O I

2009-01-01

Using a molecular dynamics model the crystallinity of Mg x Al y O z thin films with a variation in the stoichiometry of the thin film is studied at operating conditions similar to the experimental operating conditions of a dual magnetron sputter deposition system. The films are deposited on a crystalline or amorphous substrate. The Mg metal content in the film ranged from 100% (i.e. MgO film) to 0% (i.e. Al 2 O 3 film). The radial distribution function and density of the films are calculated. The results are compared with x-ray diffraction and transmission electron microscopy analyses of experimentally deposited thin films by the dual magnetron reactive sputtering process. Both simulation and experimental results show that the structure of the Mg-Al-O film varies from crystalline to amorphous when the Mg concentration decreases. It seems that the crystalline Mg-Al-O films have a MgO structure with Al atoms in between.

Superconductivity of powder-in-tube MgB{sub 2} wires

Energy Technology Data Exchange (ETDEWEB)

Glowacki, B A; Evetts, J E [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge, CB3 OHE (United Kingdom); Department of Materials Science and Metallurgy, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Majoros, M [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge, CB3 OHE (United Kingdom); Institute of Electrical Engineering, Slovak Academy of Science, Dubravska Cesta 9, Bratislava (Slovakia); Vickers, M [Department of Materials Science and Metallurgy, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Shi, Y [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge, CB3 OHE (United Kingdom); McDougall, I [Oxford Instruments Plc, Eynsham, OX8 ITL (United Kingdom)

2001-04-01

A new class of 'powder-in-tube' Mg-B superconducting conductors has been prepared using two different methods: an in situ technique where an Mg + 2B mixture was used as a central conductor core and reacted in situ to form MgB{sub 2}, and an ex situ technique where fully reacted MgB{sub 2} powder was used to fill the metal tube. Conductors were prepared using silver, copper and bimetallic silver/stainless steel tubes. Wires manufactured by the in situ technique, diffusing Mg to B particles experienced {approx}25.5% decrease in density from the initial value after cold deformation, due to the phase transformation from Mg + 2({beta}-B){yields}MgB{sub 2} all with hexagonal structure. A comparative study of the intergranular current and grain connectivity in wires was conducted by AC susceptibility measurements and direct four point transport measurements. Using a SQUID magnetometer, magnetization versus magnetic field (M-H) curves of the round wires before and after sintering and reactive diffusion were measured at 5 K and in magnetic fields up to 5 T to define the J{sub cmag}. The direct current measurements were performed in self field at 4.2 K. A comparison between zero-field-cooled (ZFC) and field-cooled (FC) susceptibility measurements for sintered Ag/MgB{sub 2}, and reacted Cu/Mg + 2B conductors revealed systematic differences in the flux pinning in the wires which is in very good agreement with direct high transport current measurements. (author)

Superconductivity of powder-in-tube MgB{sub 2} wires

Energy Technology Data Exchange (ETDEWEB)

Glowacki, B.A.; Evetts, J.E. [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge, CB3 OHE (United Kingdom); Department of Materials Science and Metallurgy, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Majoros, M. [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge, CB3 OHE (United Kingdom); Institute of Electrical Engineering, Slovak Academy of Science, Dubravska Cesta 9, Bratislava (Slovakia); Vickers, M. [Department of Materials Science and Metallurgy, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Shi, Y. [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge, CB3 OHE (United Kingdom); McDougall, I. [Oxford Instruments Plc, Eynsham, OX8 ITL (United Kingdom)

2001-04-01

A new class of 'powder-in-tube' Mg-B superconducting conductors has been prepared using two different methods: an in situ technique where an Mg + 2B mixture was used as a central conductor core and reacted in situ to form MgB{sub 2}, and an ex situ technique where fully reacted MgB{sub 2} powder was used to fill the metal tube. Conductors were prepared using silver, copper and bimetallic silver/stainless steel tubes. Wires manufactured by the in situ technique, diffusing Mg to B particles experienced {approx}25.5% decrease in density from the initial value after cold deformation, due to the phase transformation from Mg + 2({beta}-B){yields}MgB{sub 2} all with hexagonal structure. A comparative study of the intergranular current and grain connectivity in wires was conducted by AC susceptibility measurements and direct four point transport measurements. Using a SQUID magnetometer, magnetization versus magnetic field (M-H) curves of the round wires before and after sintering and reactive diffusion were measured at 5 K and in magnetic fields up to 5 T to define the J{sub cmag}. The direct current measurements were performed in self field at 4.2 K. A comparison between zero-field-cooled (ZFC) and field-cooled (FC) susceptibility measurements for sintered Ag/MgB{sub 2}, and reacted Cu/Mg + 2B conductors revealed systematic differences in the flux pinning in the wires which is in very good agreement with direct high transport current measurements. (author)

Effects of strontium on microstructure and mechanical properties of as-cast Mg-5 wt.%Sn alloy

International Nuclear Information System (INIS)

Liu, Hongmei; Chen, Yungui; Zhao, Haofeng; Wei, Shanghai; Gao, Wei

2010-01-01

The strontium (Sr) addition to the Mg-5 wt.%Sn alloy results in grain refinement and the formation of a rod-shaped and a bone-shaped MgSnSr intermetallic phase which are mainly straddle on the grain boundaries. The yield strength is improved, while the tensile strength and elongation first increased, and then decreased with a large addition of Sr. Optimum mechanical properties at ambient temperature are obtained at a content of 2.14 wt.%Sr. Tensile properties of the alloys at elevated temperatures are also improved, and the decrease of strength at elevated temperature slowed down with increasing Sr addition, indicating that Sr can improve the thermal stability of Mg-Sn alloys.

Inhibition of prolyl 4-hydroxylase decreases muscle fibrosis following chronic rotator cuff tear.

Science.gov (United States)

Gumucio, J P; Flood, M D; Bedi, A; Kramer, H F; Russell, A J; Mendias, C L

2017-01-01

Rotator cuff tears are among the most frequent upper extremity injuries. Current treatment strategies do not address the poor quality of the muscle and tendon following chronic rotator cuff tears. Hypoxia-inducible factor-1 alpha (HIF-1α) is a transcription factor that activates many genes that are important in skeletal muscle regeneration. HIF-1α is inhibited under normal physiological conditions by the HIF prolyl 4-hydroxylases (PHDs). In this study, we used a pharmacological PHD inhibitor, GSK1120360A, to enhance the activity of HIF-1α following the repair of a chronic cuff tear, and measured muscle fibre contractility, fibrosis, gene expression, and enthesis mechanics. Chronic supraspinatus tears were induced in adult rats, and repaired 28 days later. Rats received 0 mg/kg, 3 mg/kg, or 10 mg/kg GSK1120360A daily. Collagen content, contractility, fibre type distribution and size, the expression of genes involved in fibrosis, lipid accumulation, atrophy and inflammation, and the mechanical properties of the enthesis were then assessed two weeks following surgical repair. At two weeks following repair, treatment groups showed increased muscle mass but there was a 15% decrease in force production in the 10 mg/kg group from controls, and no difference between the 0 mg/kg and the 3 mg/kg groups. There was a decrease in the expression of several gene transcripts related to matrix accumulation and fibrosis, and a 50% decrease in collagen content in both treated groups compared with controls. Additionally, the expression of inflammatory genes was reduced in the treated groups compared with controls. Finally, PHD inhibition improved the maximum stress and displacement to failure in repaired tendons. GSK1120360A resulted in improved enthesis mechanics with variable effects on muscle function. PHD inhibition may be beneficial for connective tissue injuries in which muscle atrophy has not occurred.Cite this article: J. P. Gumucio, M. D. Flood, A. Bedi, H. F. Kramer, A. J

In vitro degradation of pure Mg in response to glucose

Science.gov (United States)

Zeng, Rong-Chang; Li, Xiao-Ting; Li, Shuo-Qi; Zhang, Fen; Han, En-Hou

2015-08-01

Magnesium and its alloys are promising biodegradable biomaterials but are still challenging to be used in person with high levels of blood glucose or diabetes. To date, the influence of glucose on magnesium degradation has not yet been elucidated, this issue requires more attention. Herein, we present pure Mg exhibiting different corrosion responses to saline and Hank’s solutions with different glucose contents, and the degradation mechanism of pure Mg in the saline solution with glucose in comparison with mannitol as a control. On one hand, the corrosion rate of pure Mg increases with the glucose concentration in saline solutions. Glucose rapidly transforms into gluconic acid, which attacks the oxides of the metal and decreases the pH of the solution; it also promotes the absorption of chloride ions on the Mg surface and consequently accelerates corrosion. On the other hand, better corrosion resistance is obtained with increasing glucose content in Hank’s solution due to the fact that glucose coordinates Ca2+ ions in Hank’s solution and thus improves the formation of Ca-P compounds on the pure Mg surface. This finding will open up new avenues for research on the biodegradation of bio-Mg materials in general, which could yield many new and interesting results.

Influence of face-centered-cubic texturing of Co2Fe6B2 pinned layer on tunneling magnetoresistance ratio decrease in Co2Fe6B2/MgO-based p-MTJ spin valves stacked with a [Co/Pd](n)-SyAF layer.

Science.gov (United States)

Takemura, Yasutaka; Lee, Du-Yeong; Lee, Seung-Eun; Chae, Kyo-Suk; Shim, Tae-Hun; Lian, Guoda; Kim, Moon; Park, Jea-Gun

2015-05-15

The TMR ratio of Co2Fe6B2/MgO-based p-MTJ spin valves stacked with a [Co/Pd]n-SyAF layer decreased rapidly when the ex situ magnetic annealing temperature (Tex) was increased from 275 to 325 °C, and this decrease was associated with degradation of the Co2Fe6B2 pinned layer rather than the Co2Fe6B2 free layer. At a Tex above 325 °C the amorphous Co2Fe6B2 pinned layer was transformed into a face-centered-cubic (fcc) crystalline layer textured from [Co/Pd]n-SyAF, abruptly reducing the Δ1 coherence tunneling of perpendicular-spin-torque electrons between the (100) MgO tunneling barrier and the fcc Co2Fe6B2 pinned layer.

Strain effect on the adsorption, diffusion, and molecular dissociation of hydrogen on Mg (0001) surface

Energy Technology Data Exchange (ETDEWEB)

Lei, Huaping; Wang, Caizhuang; Yao, Yongxin; Hupalo, Myron [Ames Laboratory, USDOE, Ames, Iowa 50011 (United States); Wang, Yangang [Ames Laboratory, USDOE, Ames, Iowa 50011 (United States); Supercomputing Center of Computer Network Information Center, CAS, Beijing 100190 (China); McDougall, Dan; Tringides, Michael; Ho, Kaiming [Ames Laboratory, USDOE, Ames, Iowa 50011 (United States); Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States)

2013-12-14

The adsorption, diffusion, and molecular dissociation of hydrogen on the biaxially strained Mg (0001) surface have been systematically investigated by the first principle calculations based on density functional theory. When the strain changes from the compressive to tensile state, the adsorption energy of H atom linearly increases while its diffusion barrier linearly decreases oppositely. The dissociation barrier of H{sub 2} molecule linearly reduces in the tensile strain region. Through the chemical bonding analysis including the charge density difference, the projected density of states and the Mulliken population, the mechanism of the strain effect on the adsorption of H atom and the dissociation of H{sub 2} molecule has been elucidated by an s-p charge transfer model. With the reduction of the orbital overlap between the surface Mg atoms upon the lattice expansion, the charge transfers from p to s states of Mg atoms, which enhances the hybridization of H s and Mg s orbitals. Therefore, the bonding interaction of H with Mg surface is strengthened and then the atomic diffusion and molecular dissociation barriers of hydrogen decrease accordingly. Our works will be helpful to understand and to estimate the influence of the lattice deformation on the performance of Mg-containing hydrogen storage materials.

The study of a Mg-rich epoxy primer for protection of AZ91D magnesium alloy

Energy Technology Data Exchange (ETDEWEB)

Lu Xiangyu [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Zuo Yu, E-mail: zuoy@mail.buct.edu.c [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Zhao Xuhui; Tang Yuming; Feng Xingguo [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

2011-01-15

Research highlights: {yields} A Mg-rich epoxy primer was prepared by adding pure magnesium particles in epoxy coating. Cross scratch testing results showed that in 3% NaCl solution the Mg-rich primer showed better protection for AZ91D magnesium alloy than the same epoxy primer without Mg addition. {yields} The open circuit potential of AZ91D alloy in NaCl solution decreased after coated with Mg-rich coating, suggesting that cathodic protection effect of the Mg-rich coating on AZ91D alloy was present. {yields} EIS studies showed that during the immersion tests of AZ91D alloy with Mg-rich coating the magnesium particles in coating dissolved with the charge-transfer resistance R{sub ct} at the magnesium particle/coating interface decreased and the double-layer capacitance Q{sub dl} increased. While the coating resistance remained stable for a long time and corrosion of the AZ91D alloy substrate was obviously delayed. - Abstract: A Mg-rich epoxy primer was prepared by adding pure magnesium particles to an epoxy coating. The coating properties were studied with electrochemical impedance spectroscopy (EIS), scanning electronic microscopy (SEM) and X-ray diffraction (XRD). The Mg-rich primer showed better protection for AZ91D magnesium alloy than the same epoxy primer without Mg addition. The open circuit potential measurements showed cathodic protection effect of the Mg-rich primer on AZ91D alloy. Cross scratch testing showed that the Mg-rich primer provided better protection for the substrate than original epoxy coating. The precipitation of Mg(OH){sub 2} in the coating also provided some degree of barrier protection.

The study of a Mg-rich epoxy primer for protection of AZ91D magnesium alloy

International Nuclear Information System (INIS)

Lu Xiangyu; Zuo Yu; Zhao Xuhui; Tang Yuming; Feng Xingguo

2011-01-01

Research highlights: → A Mg-rich epoxy primer was prepared by adding pure magnesium particles in epoxy coating. Cross scratch testing results showed that in 3% NaCl solution the Mg-rich primer showed better protection for AZ91D magnesium alloy than the same epoxy primer without Mg addition. → The open circuit potential of AZ91D alloy in NaCl solution decreased after coated with Mg-rich coating, suggesting that cathodic protection effect of the Mg-rich coating on AZ91D alloy was present. → EIS studies showed that during the immersion tests of AZ91D alloy with Mg-rich coating the magnesium particles in coating dissolved with the charge-transfer resistance R ct at the magnesium particle/coating interface decreased and the double-layer capacitance Q dl increased. While the coating resistance remained stable for a long time and corrosion of the AZ91D alloy substrate was obviously delayed. - Abstract: A Mg-rich epoxy primer was prepared by adding pure magnesium particles to an epoxy coating. The coating properties were studied with electrochemical impedance spectroscopy (EIS), scanning electronic microscopy (SEM) and X-ray diffraction (XRD). The Mg-rich primer showed better protection for AZ91D magnesium alloy than the same epoxy primer without Mg addition. The open circuit potential measurements showed cathodic protection effect of the Mg-rich primer on AZ91D alloy. Cross scratch testing showed that the Mg-rich primer provided better protection for the substrate than original epoxy coating. The precipitation of Mg(OH) 2 in the coating also provided some degree of barrier protection.

Corrosion protection of Mg-5Li alloy with epoxy coatings containing polyaniline

International Nuclear Information System (INIS)

Shao Yawei; Huang Hui; Zhang Tao; Meng Guozhe; Wang Fuhui

2009-01-01

The protective ability of epoxy coating containing polyaniline (PANI coating) on Mg-5Li alloy in 3.5% NaCl aqueous solution has been studied by means of EIS and electrochemical noise measurements (EN). The results of EN and EIS revealed that the PANI coating protected Mg-5Li alloy from corrosion perfectly. XPS results indicated that the presence of polyaniline changed the chemical structure of the corrosion film on the alloy surface. An analysis of the electrochemical noise data based on stochastic analysis indicated that the corrosion growth probability of Mg-5Li alloy beneath the coating was decreased by the addition of polyaniline.

50 K anomalies in superconducting MgB{sub 2} wires in copper and silver tubes

Energy Technology Data Exchange (ETDEWEB)

Majoros, M [Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Cambridge (United Kingdom); Glowacki, B A [Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Cambridge (United Kingdom); Department of Materials Science and Metallurgy, University of Cambridge, Cambridge (United Kingdom); Vickers, M E [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge (United Kingdom)

2002-02-01

In situ and ex situ MgB{sub 2} wires were prepared by the powder-in-tube method. Copper and silver tubes were used as a cladding material. AC susceptibility measurements revealed a small anomalous decrease with onset around 50 K. This effect persisted also when the wires were ground into powders. Electron microscopy and x-ray studies were performed on copper clad samples. Spectroscopic measurements in a SEM showed that regions contained either Cu or Mg and B. X-ray diffraction gave the major crystalline phases as Cu, MgCu{sub 2} and MgB{sub 2}. Diffraction evidence for Cu substituting in the Mg position was inconclusive. (author)

Decreased stability of DNA in cells treated with alkylating agents

Energy Technology Data Exchange (ETDEWEB)

Frankfurt, O.S. (Cedars Medical Center, Miami, FL (United States))

1990-12-01

A modified highly sensitive procedure for the evaluation of DNA damage in individual cells treated with alkylating agents is reported. The new methodology is based on the amplification of single-strandedness in alkylated DNA by heating in the presence of Mg{sup 2+}. Human ovarian carcinoma cells A2780 were treated with nitrogen mustard (HN2), fixed in methanol, and stained with monoclonal antibody (MOAB) F7-26 generated against HN2-treated DNA. Binding of MOAB was measured by flow cytometry with indirect immunofluorescence. Intensive binding of MOAB to control and drug-treated cells was observed after heating in Tris buffer supplemented with MgCl{sub 2}. Thus, the presence of phosphates and MgCl{sub 2} during heating was necessary for the detection of HN2-induced changes in DNA stability. Fluorescence of HN2-treated cells decreased to background levels after treatment with single-strand-specific S{sub 1} nuclease. MOAB F7-26 interacted with single-stranded regions in DNA and did not bind to dsDNA or other cellular antigens. It is suggested that alkylation of guanines decreased the stability of the DNA molecule and increased the access of MOAB F7-26 to deoxycytidines on the opposite DNA strand.

Intra-individual comparison of different contrast media concentrations (300 mg, 370 mg and 400 mg iodine) in MDCT

Energy Technology Data Exchange (ETDEWEB)

Behrendt, Florian F.; Keil, Sebastian; Plumhans, Cedric; Guenther, Rolf W. [RWTH Aachen University, Department of Diagnostic Radiology, University Hospital, Aachen (Germany); Pietsch, Hubertus; Jost, Gregor; Sieber, Martin A.; Seidensticker, Peter [Bayer Schering Pharma AG, Berlin (Germany); Mahnken, Andreas H. [RWTH Aachen University, Department of Diagnostic Radiology, University Hospital, Aachen (Germany); RWTH Aachen University, Applied Medical Engineering, Helmholtz-Institute for Biomedical Engineering, Aachen (Germany)

2010-07-15

To compare intra-individual contrast enhancement in multi-detector-row computed tomography (MDCT) using contrast media (CM) containing 300, 370 and 400 mg iodine per ml (mgI/ml). Six pigs underwent repeated chest MDCT using three different CM (iopromide 300, iopromide 370, iomeprol 400). An identical iodine delivery (IDR) rate of 1.5 gI/s and a constant total iodine dose of 300 mg/kg body weight were used. Dynamic CT were acquired at the level of the pulmonary artery, and the ascending and descending aorta. After the time enhancement curves were computed, the pulmonary and aortic peak enhancement, time to peak and plateau time above 300 HU were calculated. Intra-individual peak contrast enhancement was significantly higher for the 300 mgI/ml contrast medium compared with the 370 and 400 mgI/ml media: pulmonary trunk 595 HU vs 516 HU (p = 0.0093) vs 472HU (p = 0.0005), and aorta 505 HU vs 454 HU (p = 0.0008) vs 439 HU (p = 0.0001), respectively. Comparison of time to peaks showed no significant difference. Plateau times were significantly longer for the 300 mgI/ml than for the 370 and 400 mgI/ml CM at all anatomical sites. Given normalised IDR and total iodine burden, the use of CM with a standard concentration with 300 mg iodine/ml provides improved contrast enhancement compared with highly concentrated CM in the chest. (orig.)

Texture development in Al-Mg alloys during high temperature annealing

International Nuclear Information System (INIS)

Saitou, T.; Inagaki, H.

2001-01-01

To clarify the effect of Mg content on annealing textures developed in Al-Mg alloys during high temperature annealing, Al-Mg alloys containing up to 9 wt.% Mg in supersaturated solid solution were cold rolled 95% and isothermally annealed at 450 C. Their textures were investigated with the orientation distribution function analysis. It was found that, in the recrystallization textures observed at complete recrystallization, addition of more than 1 wt.% Mg was sufficient to suppress the development of {100} left angle 001 right angle. With increasing Mg content, {100} left angle 001 right angle decreased remarkably, whereas {100} left angle 013 right angle and {103} left angle 321 right angle increased. Thus, {100} left angle 013 right angle and {103} left angle 321 right angle were found to be the main orientations of the recrystallization textures of Al-Mg alloys annealed at high temperatures. {100} left angle 013 right angle developed most remarkably at 4 wt.% Mg, while {103} left angle 321 right angle showed the maximum development at 7 wt.% Mg. During subsequent grain growth at 450 C, remarkable texture changes were observed only in the alloys containing Mg in the range between 2 and 4 wt.%. In these alloys, {100} left angle 013 right angle developed at the expense of {100} left angle 001 right angle at earlier stages of grain growth, whereas {103} left angle 321 right angle increased independently of these two orientations at later stages of grain growth. Reflecting these texture changes, grain growth occurred in these alloys discontinuously. Such a discontinuous grain growth with large texture changes is expected, if strong textures are already present before grain growth, and if recrystallized grains having similar orientations are distributed by forming large clusters before grain growth. (orig.)

Natural aging and plastic behavior of an Al-Mg-Si Alloy

International Nuclear Information System (INIS)

Giovachini, R; Cuniberti, A

2004-01-01

The effect of prior NA on the mechanical properties of an AlMgSi alloy submitted to artificial aging for 30 min at 180 o C was studied. The NA prior to the AA leads to decreased flow tension and increased deformation at the fracture for t NA ≤ 7 days, while this behavior seems to revert itself for greater t NA . The mechanical behavior is discussed based on the formation processes of MgSi conglomerates, pre-precipitation and precipitation. The different components of the flow tension are evaluated according to a lineal overlap (CW)

Quasicrystal-reinforced Mg alloys.

Science.gov (United States)

Kyun Kim, Young; Tae Kim, Won; Hyang Kim, Do

2014-04-01

The formation of the icosahedral phase (I-phase) as a secondary solidification phase in Mg-Zn-Y and Mg-Zn-Al base systems provides useful advantages in designing high performance wrought magnesium alloys. The strengthening in two-phase composites (I-phase + α -Mg) can be explained by dispersion hardening due to the presence of I-phase particles and by the strong bonding property at the I-phase/matrix interface. The presence of an additional secondary solidification phase can further enhance formability and mechanical properties. In Mg-Zn-Y alloys, the co-presence of I and Ca 2 Mg 6 Zn 3 phases by addition of Ca can significantly enhance formability, while in Mg-Zn-Al alloys, the co-presence of the I-phase and Mg 2 Sn phase leads to the enhancement of mechanical properties. Dynamic and static recrystallization are significantly accelerated by addition of Ca in Mg-Zn-Y alloy, resulting in much smaller grain size and more random texture. The high strength of Mg-Zn-Al-Sn alloys is attributed to the presence of finely distributed Mg 2 Sn and I-phase particles embedded in the α -Mg matrix.

Corrosion inhibition of powder metallurgy Mg by fluoride treatments.

Science.gov (United States)

Pereda, M D; Alonso, C; Burgos-Asperilla, L; del Valle, J A; Ruano, O A; Perez, P; Fernández Lorenzo de Mele, M A

2010-05-01

Pure Mg has been proposed as a potential degradable biomaterial to avoid both the disadvantages of non-degradable internal fixation implants and the use of alloying elements that may be toxic. However, it shows excessively high corrosion rate and insufficient yield strength. The effects of reinforcing Mg by a powder metallurgy (PM) route and the application of biocompatible corrosion inhibitors (immersion in 0.1 and 1M KF solution treatments, 0.1M FST and 1M FST, respectively) were analyzed in order to improve Mg mechanical and corrosion resistance, respectively. Open circuit potential measurements, polarization techniques (PT), scanning electrochemical microscopy (SECM) and electrochemical impedance spectroscopy (EIS) were performed to evaluate its corrosion behavior. SECM showed that the local current of attacked areas decreased during the F(-) treatments. The corrosion inhibitory action of 0.1M FST and 1M FST in phosphate buffered solution was assessed by PT and EIS. Under the experimental conditions assayed, 0.1M FST revealed better performance. X-ray photoelectron spectroscopy, energy dispersive X-ray and X-ray diffraction analyses of Mg(PM) with 0.1M FST showed the presence of KMgF(3) crystals on the surface while a MgF(2) film was detected for 1M FST. After fluoride inhibition treatments, promising results were observed for Mg(PM) as degradable metallic biomaterial due to its higher yield strength and lower initial corrosion rate than untreated Mg, as well as a progressive loss of the protective characteristics of the F(-)-containing film which ensures the gradual degradation process. Copyright (c) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Superconducting properties of MgB2 particle impregnated with Mg-based alloys

International Nuclear Information System (INIS)

Shimizu, Yusuke; Matsuda, Kenji; Mizutani, Manabu; Nishimura, Katsuhiko; Kawabata, Tokimasa; Ikeno, Susumu; Hishinuma, Yoshimitsu; Aoyama, Shigeki

2011-01-01

The three-dimensional penetration method combined with semi-solid casting (SS-3DPC) was utilized to prepare magnesium diboride (MgB 2 ) powder composite materials with various host materials of Mg, Mg-3%Al, Mg-3%Al-1%Zn, Mg-9%Al, and Mg-9%Al-1%Zn. X-ray diffraction measurements indicated predominant peak patterns of MgB 2 and a host alloy, implying that the host material tightly bonded MgB 2 grains without melting the MgB 2 powder. This was confirmed by SEM images. Measured electrical resistivity and magnetization versus temperature showed clear signals of superconducting transition temperature of 27-38 K for all the samples cut out from the billets. Magnetic hysteresis loop observed at 5 K enabled us to estimate a critical current density (J c ) based on the extended Bean model. Additions of aluminum and zinc elements to magnesium host-matrix were found to enhance J c and increase residual resistivity (ρ 0 ) suggesting that aluminum and zinc have an effect on pinning magnetic flux flow for J c enhancement, and scattering conduction electrons for increase of ρ 0 . (author)

Optical absorption and thermoluminescence in Mg O, Mg O:Ni and Mg O:Li irradiated at room temperature

International Nuclear Information System (INIS)

Delgado, L.

1984-01-01

Optical absorption and thermoluminescence (TL) studies in Mg O, Mg O:Ni and Mg O:Li irradiated at room temperature are presented. In pure Mg O the thermal annihilation of Fe3+ by recombination with thermally released electrons at ∼ 90 and 175 degree centigree and the V center annealing by hole release up to 100 degree centigree cause the observed glow peaks at these temperatures. The TL excitation spectrum shows two maxima at 245 nm (electron center) and 288 nm (Fe3+). In Mg O:Ni X irradiation induces Fe 2 + →- Fe 3 + and Ni 2 + → Ni 3 + oxidations. Two TL emission bands centered at 110 degree centigree (red) and 80 o C (green) are assigned to electron release and their recombination at Fe 3 + and Ni 3 + respectively. In Mg O:Li two TL emission bands, one blue (430 nm) and the other red (730 nm) with excitation maxima at 245 nm (electron center) and 200 nm (hole center) respectively are observed. No V-center formation was detected in both Ni and Li doped samples. (Author) 42 refs

The synthesis and characterization of Mg-Zn-Ca alloy by powder metallurgy process

Energy Technology Data Exchange (ETDEWEB)

Annur, Dhyah; Franciska, P.L.; Erryani, Aprilia; Amal, M. Ikhlasul; Kartika, Ika, E-mail: pepeng2000@yahoo.com [Research center for Metallurgy and Material, Indonesian Institute of Science (Indonesia); Sitorus, Lyandra S. [Sultan Ageng Tirtayasa University (Indonesia)

2016-04-19

Known for its biodegradation and biocompatible properties, magnesium alloys have gained many interests to be researched as implant material. In this study, Mg-3Zn-1Ca, Mg-29Zn-1Ca, and Mg-53Zn-4.3Ca (in wt%) were synthesized by means of powder metallurgy method. The compression strength and corrosion resistance of magnesium alloy were thoroughly examined. The microstructures of the alloy were characterized using optical microscopy, Scanning Electron Microscope, and also X-ray diffraction analysis. The corrosion resistance were evaluated using electrochemical analysis. The result indicated that Mg- Zn- Ca alloy could be synthesized using powder metallurgy method. This study showed that Mg-29Zn-1Ca would make the highest mechanical strength up to 159.81 MPa. Strengthening mechanism can be explained by precipitation hardening and grain refinement mechanism. Phase analysis had shown the formation of α Mg, MgO, and intermetallic phases: Mg2Zn11 and also Ca2Mg6Zn3. However, when the composition of Zn reach 53% weight, the mechanical strength will be decreasing. In addition, all of Mg-Zn-Ca alloy studied here had better corrosion resistance (Ecorr around -1.4 VSCE) than previous study of Mg. This study indicated that Mg- 29Zn- 1Ca alloy can be further analyzed to be a biodegradable implant material.

Differential conductance measurements of low-resistance CoFeB/MgO/CoFeB magnetic tunnel junctions

International Nuclear Information System (INIS)

Nishioka, S.; Hamada, Y.V.; Matsumoto, R.; Mizuguchi, M.; Shiraishi, M.; Fukushima, A.; Kubota, H.; Nagahama, T.; Yuasa, S.; Maehara, H.; Nagamine, Y.; Tsunekawa, K.; Djayaprawira, D.D.; Watanabe, N.; Suzuki, Y.

2007-01-01

We measured differential conductance spectra of magnetic tunnel junctions (MTJs) with thin MgO barrier and low-resistance area product. The spectra of MTJs with MgO barrier thicker than 1.05 nm were essentially the same except for slight decrease of contributions from low-energy excitations, such as magnons. The spectra of MTJ with 1.01 nm MgO barrier were thoroughly different from the MTJs with thicker barrier. The result reveals that an MTJ with very thin MgO barrier thickness has different conduction characteristics from those with thicker MgO barriers

Morphological and optical studies of zinc oxide doped MgO

Energy Technology Data Exchange (ETDEWEB)

Othman, Zayani Jaafar, E-mail: jaafar.zayani@yahoo.fr; Matoussi, Adel

2016-06-25

This paper reports morphological and optical characterizations of sintered (ZnO){sub 1−x}(MgO){sub x} composite materials. The effects of MgO doping content on these pellets properties have been analyzed. The SEM observations have shown rougher surfaces of the samples covered by grains having prismatic shapes and different sizes. From reflectance and absorption measurements, we have determined the band gap energy which tends to augment from 3.287 to 3.827 eV as the doping content increases. This widening of the optical band gap is explained by the Burstein-Moss effect which causes a significant increase of electron concentration (2.89 10{sup 18}−5.1910{sup 20} cm{sup −3}). In addition, the absorption coefficient, Urbach energy, optical constants (refractive index, extinction coefficient, dielectric constant) and dispersion parameters, such as E{sub 0} (single-oscillator energy), E{sub d} (dispersive energy) were determined of the (ZnO){sub 1−x}(MgO){sub x} composites and analyzed. - Highlights: • (ZnO){sub 1−x}(MgO){sub x} composites were synthesized by solid state sintering method. • MgO doping increased the band gap energy. • SEM observations have shown a decrease of grain sizes when the MgO doping increases. • Optical constants and dispersion parameters were determined and analyzed.

Sorption of phosphates and thiocyanates on isomorphic substituted Mg/Zn–Al-type hydrotalcites

Directory of Open Access Journals (Sweden)

RODICA PODE

2008-08-01

Full Text Available The sorption equilibriums of phosphate and thiocyanate anions on isomorphic substituted Mg/Zn–Al-type hydrotalcites were investigated in this study. Langmuir and Freundlich isotherms were used to interpret the equilibrium data for phosphate. The sorption equilibriums of phosphate on Mg3Al, Mg2ZnAl and Mg1.5Zn1.5Al hydrotalcites were well described by the Langmuir isotherm. The highest maximum sorption capacities for these adsorbents were as follows: 111, 101 and 95 mg g-1. The equilibrium constant and standard Gibbs energy changes were also calculated from the sorption data. Standard Gibbs energy changes of about –20 kJ mol-1 indicated that the process might be considered as physical adsorption. The sorption equilibriums of phosphate on isomorphic substituted samples of MgZn2Al and Zn3Al were well described by the Freundlich isotherm. Thiocyanate showed a relative low affinity for the studied materials, as indicated by both the “S”-shaped isotherms and low sorption capacities. The sorption of phosphate and thiocyanate on the investigated hydrotalcites showed a continuous decrease of the sorption capacity in the following order: Mg3Al > Mg2ZnAl > Mg1.5Zn1.5Al > MgZn2Al > Zn3Al.

Changes of Bone-Related Minerals during Denosumab Administration in Post-Menopausal Osteoporotic Patients.

Science.gov (United States)

Suzuki, Takako; Nakamura, Yukio; Kato, Hiroyuki

2017-08-13

This retrospective study included 21 patients with primary osteoporosis who were treated with the anti-resorption drug, denosumab. To date, there has been no detailed report on the changes of bone-related minerals after anti-resorption drug therapy. Twenty-one post-menopausal females were retrospectively enrolled. Serum zinc (Zn), magnesium (Mg), iron (Fe), copper (Cu), grip strength, and estimated glomerular filtration rate (eGFR) were examined at one week and 1, 2, 4, 6, 8, 10, and 12 months. Lumbar spine (L1-4) bone mineral density (L-BMD) and bilateral total hip BMD (H-BMD) were examined before and at 4, 8, and 12 months after treatment commencement. Serum Zn tended to decrease at one week and one month, and tended to increase during 10 to 12 months. Serum Cu maintained during zero to eight months, then decreased at 10 and 12 months. Serum Fe gradually increased after four months. Serum Mg sharply increased at one week, then decreased further. Grip strength increased for two months, then slightly decreased and maintained 4 to 12 months. eGFR almost maintained for zero to eight months, then slightly decreased thereafter. L-BMD values significantly increased at eight (5.8%) ( p < 0.01) and 12 months (9.8%) ( p < 0.01). H-BMD increased during the period (at 12 months: 3.7%). These results suggest that at later phases of denosumab therapy, Zn and Fe tended to increase while Mg tended to decrease, all of which are important for bone metabolism. Thus, denosumab might improve Zn and Fe metabolism, and thereby likely increase BMD. Since denosumab may not improve Mg, it is better to obtain Mg supplementation during the therapy.

The influence of yttrium (Y) on the corrosion of Mg-Y binary alloys

International Nuclear Information System (INIS)

Liu Ming; Schmutz, Patrik; Uggowitzer, Peter J.; Song Guangling; Atrens, Andrej

2010-01-01

Research highlights: → The Y-intermetallic can accelerate corrosion and Y can increase the protectiveness of the surface layer. → In 0.1 M NaCl, the corrosion rate of Mg-Y alloys increased with increasing Y due to the Y intermetallic. → In 0.1 M NaCl, there was filiform corrosion. → In 0.1 M Na 2 SO 4 , the corrosion rate of Mg-Y alloys decreased with increasing Y in the range 3-7%Y. → Hydrogen evolution was observed from particular parts of the alloy surface. - Abstract: Corrosion of Mg-Y alloys was studied using electrochemical evaluations, immersion tests and direct observations. There were two important effects. In 0.1 M NaCl, the corrosion rate increased with increasing Y content due to increasing amounts of the Y-containing intermetallic. In 0.1 M Na 2 SO 4 , the corrosion rate decreased with increasing Y content above 3%, attributed to a more protective surface film, despite the intermetallic. The corrosion rate evaluated by electrochemical impedance spectroscopy was somewhat smaller than that evaluated from H evolution as expected from the Mg corrosion mechanism. A mechanism is proposed for filiform corrosion. Direct in situ corrosion observations revealed that a predominant feature was hydrogen evolution from particular parts of the alloy surface.

Influence of Mg{sup 2+} doping on the structure and electrochemical performances of layered LiNi{sub 0.6}Co{sub 0.2-x}Mn{sub 0.2}Mg{sub x}O{sub 2} cathode materials

Energy Technology Data Exchange (ETDEWEB)

Huang, Zhenjun; Wang, Zhixing, E-mail: zxwang.csu@hotmail.com; Guo, Huajun; Li, Xinhai

2016-06-25

Introducing the Mg ion into host lattice is applied to improving the electrochemical performance of LiNi{sub 0.6}Co{sub 0.2}Mn{sub 0.2}O{sub 2}. The effect of Mg substitution for Co on the structure, morphology, electrochemical properties and Li{sup +} diffusion coefficients are investigated in details. Rietveld refinement results reveal that Mg is incorporated into the bulk lattice, which results in reduced cation mixing and expand c-lattice parameter. All Mg-doped sample exhibit better cycle and rate performances, although the Mg substitution for Co led to decreasing a part of capacity. The Li diffusion coefficients obtained by galvanostatic intermittent titration technique (GITT) are increased with increases of Mg content. - Highlights: • Mg-doped sample exhibits better electrochemical performance. • The change of crystal structure by Mg doping are studied. • The Mg doping improves the lithium ion diffusion coefficient.

The charge transfer induced by Cr doping in MgB2

International Nuclear Information System (INIS)

Zhang Huarong; Zhao Jiyin; Shi Lei

2005-01-01

Mg 1-x Cr x B 2 polycrystal bulk samples with 0 x 5% have been synthesized by a solid-state reaction and studied by X-ray diffraction, SEM and Raman spectrum. It is found that the c-axis of the lattice decreases as the Cr content increases, while the a-axis remains unchanged. Moreover, crystal grain size increases apparently with Cr doping concentration increase. The normal-state resistivity increases and the superconducting transition temperature (T c ) decreases from 38.2 K (x = 0) to 35.1 K (x 0.03) with the increase of Cr content. It is suggested that the charge transfer between the Mg-layer and the B-layer causes the decrease of the charge carrier concentration and induces the changes of T c and normal-state resistivity. On the other hand, by the Raman scattering study, it is found that the linewidth of Raman spectrum increases with the increase of Cr content, which is resulted by the competition between the electron-phonon interaction and substitution-induced disorder. The Raman peak has no evident shift due to the countervailing between the effects of the electron-phonon coupling and the grain size

Effects of Sm addition on electromagnetic interference shielding property of Mg-Zn-Zr alloys

Energy Technology Data Exchange (ETDEWEB)

Yang, Chubin [Chongqing University, College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloy, Chongqing (China); Gannan Normal University, Jiangxi Provincial Engineering Research Center for Magnesium Alloy, Ganzhou (China); Pan, Fusheng; Chen, Xianhua [Chongqing University, College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloy, Chongqing (China); Luo, Ning [Gannan Normal University, Jiangxi Provincial Engineering Research Center for Magnesium Alloy, Ganzhou (China)

2017-06-15

The electromagnetic interference (EMI) shielding of Sm-containing magnesium alloys in the 30-1500 MHz testing frequency range was investigated by coaxial cable method. The results demonstrated that Mg-3Zn alloys displayed the best electromagnetic shielding property. When 0.5 wt% of Zr was added for crystal grain refinement, the shielding effectiveness (SE) was apparently reduced. The addition of the rare earth element Sm in ZK magnesium alloys can improve the electromagnetic interference shielding of magnesium alloys. The main reason for the differences in electromagnetic interference shielding of magnesium alloys was the change in conductivity. The addition of Zr in Mg-Zn alloys can refine the grains and consequently improve the grain boundary area significantly. Therefore, the number of irregularly arranged atoms at the grain boundaries increased, decreasing the conductivity of magnesium alloys and leading to a decrease in the electromagnetic interference shielding. Following the Sm addition, the Mg-Zn-Sm phase was precipitated at the grain boundaries and in cores. The precipitation of Sm-containing rare earth phases could consume the solid-soluted Zn atoms within the Mg, resulting in an increase in electrical conductivity and electromagnetic interference shielding improvement. (orig.)

Effect of lead pollution control on environmental and childhood blood lead level in Nantong, China: an interventional study.

Science.gov (United States)

Chen, Kai; Huang, Lei; Yan, Beizhan; Li, Hongbo; Sun, Hong; Bi, Jun

2014-11-04

Children's blood lead levels and prevalence of lead poisoning in China are significantly higher than in developed countries, though a substantial decrease has been observed. Since 2011, strict lead control policies in lead-related industries have been implemented in China, but the success of these policies is unknown. In this study, we collected environmental samples, questionnaire data, and blood samples from 106 children from 1 to 14 years old, before and after implementation of lead-usage control policy in wire rope factories by local government in Zhuhang, Nantong in 2012. Results showed that, one year after the lead control, lead concentrations sharply decreased in both environmental and biological samples with a decrease of 0.43 μg/m3 (-84.3%) in ambient air samples, 0.22 mg/kg (-36.1%) in vegetable samples, 441.1 mg/kg (-43.7%) in dust samples, and 6.24 μg/dL (-51.5%) in childhood blood lead levels (BLL). This study demonstrates the success of lead control policies in promoting the prevention and control of childhood lead poisoning in Nantong, China.

Effect of Zr on the Corrosion Properties of Mg-Li-Al Alloy

International Nuclear Information System (INIS)

Kim, Soon Ho; Choi, Sang Hyun; Kim, In Bae; Kim, Kyung Hyun

1994-01-01

Effect of Zr on the electrochemical corrosion characteristics of Mg-Li-Al alloy has been investigated by means of potentiodynamic polarization study. The electrochemical behaviors were evaluated in 0.03% NaCl solution and the solution buffered with KH 2 PO 5 · NaOH at room temperature. It was found that the addition of very small quantity of Zr (0.03wt%) in Mg-Li-Al alloy increased corrosion rates and amount of corrosion products and decreased the pitting resistance of the alloy. From the results it was concluded that Zr which is added to increase the strength of Mg-Li-Al alloy is harmful to corrosion properties of the alloy

The Influence of MgH2 on the Assessment of Electrochemical Data to Predict the Degradation Rate of Mg and Mg Alloys

Directory of Open Access Journals (Sweden)

Wolf-Dieter Mueller

2014-06-01

Full Text Available Mg and Mg alloys are becoming more and more of interest for several applications. In the case of biomaterial applications, a special interest exists due to the fact that a predictable degradation should be given. Various investigations were made to characterize and predict the corrosion behavior in vitro and in vivo. Mostly, the simple oxidation of Mg to Mg2+ ions connected with adequate hydrogen development is assumed, and the negative difference effect (NDE is attributed to various mechanisms and electrochemical results. The aim of this paper is to compare the different views on the corrosion pathway of Mg or Mg alloys and to present a neglected pathway based on thermodynamic data as a guideline for possible reactions combined with experimental observations of a delay of visible hydrogen evolution during cyclic voltammetry. Various reaction pathways are considered and discussed to explain these results, like the stability of the Mg+ intermediate state, the stability of MgH2 and the role of hydrogen overpotential. Finally, the impact of MgH2 formation is shown as an appropriate base for the prediction of the degradation behavior and calculation of the corrosion rate of Mg and Mg alloys.

Structural characteristics and corrosion behavior of biodegradable Mg-Zn, Mg-Zn-Gd alloys.

Science.gov (United States)

Kubásek, J; Vojtěch, D

2013-07-01

In this research, binary Mg-Zn (up to 3 wt% Zn) and ternary Mg-Zn-Gd (up to 3 wt% Gd, 3 wt% Zn) alloys were prepared by induction melting in an argon atmosphere. The structures of these alloys were characterized using light and scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction and X-ray fluorescence. In addition, Brinell hardness measurements were taken to supplement these studies. Corrosion behavior was evaluated by immersion tests and potentiodynamic measurements in a physiological solution (9 g/l NaCl). Depending on the composition, structures of the as-cast alloys contained α-Mg dendrites, MgZn, Mg5Gd and Mg3Gd2Zn3 phases. Compared to pure Mg, zinc improved the corrosion resistance of binary Mg-Zn. Gadolinium also improved the corrosion resistance in the case of Mg-1Zn-3Gd alloy. The highest corrosion rate was observed for Mg-3Zn-3Gd alloy. Our results improve the understanding of the relationships between the structure and corrosion behavior of our studied alloy systems.

Coherent interface structures and intergrain Josephson coupling in dense MgO/Mg{sub 2}Si/MgB{sub 2} nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Ueno, Katsuya; Takahashi, Kazuyuki; Uchino, Takashi, E-mail: uchino@kobe-u.ac.jp [Department of Chemistry, Graduate School of Science, Kobe University, Nada, Kobe 657-8501 (Japan); Nagashima, Yukihito [Nippon Sheet Glass Co., Ltd., Konoike, Itami 664-8520 (Japan); Seto, Yusuke [Department of Planetology, Graduate School of Science, Kobe University, Nada, Kobe 657-8501 (Japan); Matsumoto, Megumi; Sakurai, Takahiro [Center for Support to Research and Education Activities, Kobe University, Nada, Kobe 657-8501 (Japan); Ohta, Hitoshi [Molecular Photoscience Research Center, Kobe University, Nada, Kobe 657-8501 (Japan)

2016-07-07

Many efforts are under way to control the structure of heterointerfaces in nanostructured composite materials for designing functionality and engineering application. However, the fabrication of high-quality heterointerfaces is challenging because the crystal/crystal interface is usually the most defective part of the nanocomposite materials. In this work, we show that fully dense insulator (MgO)/semiconductor(Mg{sub 2}Si)/superconductor(MgB{sub 2}) nanocomposites with atomically smooth and continuous interfaces, including epitaxial-like MgO/Mg{sub 2}Si interfaces, are obtained by solid phase reaction between metallic magnesium and a borosilicate glass. The resulting nanocomposites exhibit a semiconductor-superconducting transition at 36 K owing to the MgB{sub 2} nanograins surrounded by the MgO/Mg{sub 2}Si matrix. This transition is followed by the intergrain phase-lock transition at ∼24 K due to the construction of Josephson-coupled network, eventually leading to a near-zero resistance state at 17 K. The method not only provides a simple process to fabricate dense nanocomposites with high-quality interfaces, but also enables to investigate the electric and magnetic properties of embedded superconducting nanograins with good intergrain coupling.

Pre- and post-irradiation fading effect for LiF:Mg,Ti and LiF:Mg,Cu,P materials used in routine monitoring

International Nuclear Information System (INIS)

Carinou, E.; Askounis, P.; Dimitropoulou, F.; Kiranos, G.; Kyrgiakou, H.; Nirgianaki, E.; Papadomarkaki, E.; Kamenopoulou, V.

2011-01-01

LiF is a well-known thermoluminescent (TL) material used in individual monitoring, and its fading characteristics have been studied for years. In the present study, the fading characteristics (for a period of 150 d) of various commercial LiF materials with different dopants have been evaluated. The materials used in the study are those used in routine procedures by the Personal Dosimetry Dept. of Greek Atomic Energy Commission and in particular, LiF:Mg,Ti (MTS-N, TL Poland), LiF:Mg,Cu,P (MCP-N, TL Poland), LiF:Mg,Cu,P (MCP-Ns, thin active layer detector, TL Poland) and LiF:Mg,Cu,P (TLD100H, Harshaw). The study showed that there is a sensitivity loss in signal of up to 20 % for the MTS-N material for a 150-d period in the pre-irradiation fading phase. The MCP-N has a stable behaviour in the pre-irradiation fading phase, but this also depends on the readout system. As far as the post-irradiation fading effect is concerned, a decrease of up to 20 % for the MTS-N material is observed for the same time period. On the other hand, the LiF:Mg,Cu,P material presents a stable behaviour within ±5 %. These results show that the fading effect is different for each material and should be taken into account when estimating doses from dosemeters that are in use for >2 months. (authors)

Ultrasonic spot welding of Al/Mg/Al tri-layered clad sheets

International Nuclear Information System (INIS)

Macwan, A.; Patel, V.K.; Jiang, X.Q.; Li, C.; Bhole, S.D.; Chen, D.L.

2014-01-01

Highlights: • The optimal welding condition is achieved at 100 J and 0.1 s. • Failure load first increases and then decreases with increasing welding energy. • The highest failure load after welding is close to that of the clad sheets. • At low energy levels failure occurs in the mode of interfacial failure. • At high energy levels failure takes place at the edge of nugget region. - Abstract: Solid-state ultrasonic spot welding (USW) was used to join Al/Mg/Al tri-layered clad sheets, aiming at exploring weldability and identifying failure mode in relation to the welding energy. It was observed that the application of a low welding energy of 100 J was able to achieve the optimal welding condition during USW at a very short welding time of 0.1 s for the tri-layered clad sheets. The optimal lap shear failure load obtained was equivalent to that of the as-received Al/Mg/Al tri-layered clad sheets. With increasing welding energy, the lap shear failure load initially increased and then decreased after reaching a maximum value. At a welding energy of 25 J, failure occurred in the mode of interfacial failure along the center Al/Al weld interface due to insufficient bonding. At a welding energy of 50 J, 75 J and 100 J, failure was also characterized by the interfacial failure mode, but it occurred along the Al/Mg clad interface rather than the center Al/Al weld interface, suggesting stronger bonding of the Al/Al weld interface than that of the Al/Mg clad interface. The overall weld strength of the Al/Mg/Al tri-layered clad sheets was thus governed by the Al/Mg clad interface strength. At a welding energy of 125 J and 150 J, thinning of weld nugget and extensive deformation at the edge of welding tip caused failure at the edge of nugget region, leading to a lower lap shear failure load

Time- and sequence-dependent responses to cisplatin and radiation in the rat kidney

International Nuclear Information System (INIS)

Rongen, Eric van; Kuijpers, W.C.; Baten-Wittwer, Andrea

1991-01-01

The influence of time interval and sequence between administration of cisplatin and a radiation dose was studied in the rat kidney. Changes in glomerular function were only detected after 30 weeks following the higher drug dose (6.0 mg/kg). X-rays alone caused measurable alterations in both glomerular and tubular function after 16 weeks. In the combined treatment the influence of time and sequence was significant. If cisplatin was given at 7 to 1 days before X-rays the effect of time was minimal. Administration of cisplatin 12 h to 15 min before irradiation resulted in an increase of radiation damage with decreasing time interval. Total damage sharply decreased when both modalities were given at the same time, and decreased further with increasing time between irradiation and drug administration. (author)

Study the Effect of Mg O on the Photo catalysis of Zn O Thin Layers

International Nuclear Information System (INIS)

Zaghlool, R.A.I.M.

2011-01-01

The removal of the non-biodegradable organic chemicals is a crucial ecological problem. Dyes are an important class of synthetic organic compounds used in the textile industry and are therefore common industrial pollutants. Due to the stability of modern dyes, conventional biological treatment methods for industrial wastewater are ineffective resulting often in an intensively colored discharge from the treatment facilities. Heterogeneous photo catalysis by semiconductor films is a promising technology for the reduction of global environmental pollutants. Zn O has received much attention in the degradation and complete mineralization of environmental pollutants. In order to improve the properties of the films, several techniques such as sputtering, thermal evaporation and spray pyrolysis have been applied for the production of Zn O. Spray pyrolysis technique is preferred among these techniques. It is less expensive, simpler and more versatile than all the other techniques, which allows the possibility of obtaining large area films with the required properties for different applications. In order to improve the photo catalytic efficiency of Zn O films, the particle sizes, morphologies, surface properties, and electronic structure have to be changed. This can be done by doping with some metals. In this work, Mg was doped into Zn O thin films. Zn 1x Mg x O thin films are prepared by spray pyrolysis method on glass substrates. The deposition temperature was 500 °C. Mg concentration was varied in the range of 0.0 to 0.3 in intervals of 0.05. The pure Zn O films were polycrystalline with preferred orientation (100). Zn 1x Mg x O films become amorphous with increasing Mg concentration. The grain size decreased with increasing Mg content. Also, doping with Mg has increased the surface roughness of the films. The optical band gap of Zn 1x Mg x O changes from 3.26 to 3.48 eV with increasing Mg content. The refractive index has been decreased but the extinction coefficient

Photoluminescence of Mg_2Si films fabricated by magnetron sputtering

International Nuclear Information System (INIS)

Liao, Yang-Fang; Xie, Quan; Xiao, Qing-Quan; Chen, Qian; Fan, Meng-Hui; Xie, Jing; Huang, Jin; Zhang, Jin-Min; Ma, Rui; Wang, Shan-Lan; Wu, Hong-Xian; Fang, Di

2017-01-01

Highlights: • High quality Mg_2Si films were grown on Si (111) and glass substrates with magnetron sputtering, respectively. • The first observation of Photoluminescence (PL) of Mg_2Si films was reported. • The Mg_2Si PL emission wavelengths are almost independence on temperature in the range of 77–300 K. • The strongest PL emissions may be attributed to interstitial Mg donor level to valence band transitions. • The activation energy of Mg_2Si is determined from the quenching of major luminescence peaks. - Abstract: To understand the photoluminescence mechanisms and optimize the design of Mg_2Si-based light-emitting devices, Mg_2Si films were fabricated on silicon (111) and glass substrates by magnetron sputtering technique, and the influences of different substrates on the photoelectric properties of Mg_2Si films were investigated systematically. The crystal structure, cross-sectional morphology, composition ratios and temperature-dependent photoluminescence (PL) of the Mg_2Si films were examined using X-ray diffraction (XRD), Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and PL measurement system, respectively. XRD results indicate that the Mg_2Si film on Si (111) displays polycrystalline structure, whereas Mg_2Si film on glass substrate is of like-monocrystalline structure.SEM results show that Mg_2Si film on glass substrate is very compact with a typical dense columnar structure, and the film on Si substrate represents slight delamination phenomenon. EDS results suggest that the stoichiometry of Mg and Si is approximately 2:1. Photoluminescence (PL) of Mg_2Si films was observed for the first time. The PL emission wavelengths of Mg_2Si are almost independence on temperature in the range of 77–300 K. The PL intensity decreases gradually with increasing temperature. The PL intensity of Mg_2Si films on glass substrate is much larger than that of Mg_2Si film on Si (111) substrate. The activation energy of 18 meV is

Morphine decreases social interaction of adult male rats, while THC does not affect it.

Science.gov (United States)

Šlamberová, R; Mikulecká, A; Macúchová, E; Hrebíčková, I; Ševčíková, M; Nohejlová, K; Pometlová, M

2016-12-22

The aim of the present study was to compare effect of three low doses of morphine (MOR) and delta9-tetrahydrocannabinol (THC) on social behavior tested in Social interaction test (SIT). 45 min prior to testing adult male rats received one of the drugs or solvents: MOR (1; 2.5; 5 mg/kg); saline as a solvent for MOR; THC (0.5; 1; 2 mg/kg); ethanol as a solvent for THC. Occurrence and time spent in specific patterns of social interactions (SI) and non-social activities (locomotion and rearing) was video-recorded for 5 min and then analyzed. MOR in doses of 1 and 2.5 mg/kg displayed decreased SI in total. Detailed analysis of specific patterns of SI revealed decrease in mutual sniffing and allo-grooming after all doses of MOR. The highest dose (5 mg/kg) of MOR decreased following and increased genital investigation. Rearing activity was increased by lower doses of MOR (1 and 2.5 mg/kg). THC, in each of the tested doses, did not induce any specific changes when compared to matching control group (ethanol). However, an additional statistical analysis showed differences between all THC groups and their ethanol control group when compared to saline controls. There was lower SI in total, lower mutual sniffing and allo-grooming, but higher rearing in THC and ethanol groups than in saline control group. Thus, changes seen in THC and ethanol groups are seemed to be attributed mainly to the effect of the ethanol. Based on the present results we can assume that opioids affect SI more than cannabinoid.

Behaviour of Fe4O5-Mg2Fe2O5 solid solutions and their relation to coexisting Mg-Fe silicates and oxide phases

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Uenver-Thiele, Laura; Woodland, Alan B.; Miyajima, Nobuyoshi; Ballaran, Tiziana Boffa; Frost, Daniel J.

2018-03-01

Experiments at high pressures and temperatures were carried out (1) to investigate the crystal-chemical behaviour of Fe4O5-Mg2Fe2O5 solid solutions and (2) to explore the phase relations involving (Mg,Fe)2Fe2O5 (denoted as O5-phase) and Mg-Fe silicates. Multi-anvil experiments were performed at 11-20 GPa and 1100-1600 °C using different starting compositions including two that were Si-bearing. In Si-free experiments the O5-phase coexists with Fe2O3, hp-(Mg,Fe)Fe2O4, (Mg,Fe)3Fe4O9 or an unquenchable phase of different stoichiometry. Si-bearing experiments yielded phase assemblages consisting of the O5-phase together with olivine, wadsleyite or ringwoodite, majoritic garnet or Fe3+-bearing phase B. However, (Mg,Fe)2Fe2O5 does not incorporate Si. Electron microprobe analyses revealed that phase B incorporates significant amounts of Fe2+ and Fe3+ (at least 1.0 cations Fe per formula unit). Fe-L2,3-edge energy-loss near-edge structure spectra confirm the presence of ferric iron [Fe3+/Fetot = 0.41(4)] and indicate substitution according to the following charge-balanced exchange: [4]Si4+ + [6]Mg2+ = 2Fe3+. The ability to accommodate Fe2+ and Fe3+ makes this potential "water-storing" mineral interesting since such substitutions should enlarge its stability field. The thermodynamic properties of Mg2Fe2O5 have been refined, yielding H°1bar,298 = - 1981.5 kJ mol- 1. Solid solution is complete across the Fe4O5-Mg2Fe2O5 binary. Molar volume decreases essentially linearly with increasing Mg content, consistent with ideal mixing behaviour. The partitioning of Mg and Fe2+ with silicates indicates that (Mg,Fe)2Fe2O5 has a strong preference for Fe2+. Modelling of partitioning with olivine is consistent with the O5-phase exhibiting ideal mixing behaviour. Mg-Fe2+ partitioning between (Mg,Fe)2Fe2O5 and ringwoodite or wadsleyite is influenced by the presence of Fe3+ and OH incorporation in the silicate phases.

Solubility and release of fenbufen intercalated in Mg, Al and Mg, Al, Fe layered double hydroxides (LDH): The effect of Eudragit S 100 covering

International Nuclear Information System (INIS)

Arco, M. del; Fernandez, A.; Martin, C.; Rives, V.

2010-01-01

Following different preparation routes, fenbufen has been intercalated in the interlayer space of layered double hydroxides with Mg 2+ and Al 3+ or Mg 2+ , Al 3+ and Fe 3+ in the layers. Well crystallized samples were obtained in most of the cases (intercalation was not observed by reconstruction of the MgAlFe matrix), with layer heights ranging between 16.1 and 18.8 A. The presence of the LDH increases the solubility of fenbufen, especially when used as a matrix. The dissolution rate of the drug decreases when the drug is intercalated, and is even lower in those systems containing iron; release takes place through ionic exchange with phosphate anions from the solution. Preparation of microspheres with Eudragit S 100 leads to solids with an homogeneous, smooth surface with efficient covering of the LDH surface, as drug release was not observed at pH lower than 7. - Graphical abstract: LDHs containing Mg, Al, Fe increase fenbufen solubility, release takes place through ionic exchange with phosphate anions from the medium. Spherical solids with homogeneous, smooth surface are formed when using Eudragit S 100, efficiently covering the LDH surface. Display Omitted

In vitro study of nanostructured diopside coating on Mg alloy orthopedic implants

International Nuclear Information System (INIS)

Razavi, Mehdi; Fathi, Mohammadhossein; Savabi, Omid; Vashaee, Daryoosh; Tayebi, Lobat

2014-01-01

The high corrosion rate of Mg alloys has hindered their application in various areas, particularly for orthopedic applications. In order to decrease the corrosion rate and to improve the bioactivity, mechanical stability and cytocompatibility of the Mg alloy, nanostructured diopside (CaMgSi 2 O 6 ) has been coated on AZ91 Mg alloy using a combined micro arc oxidation (MAO) and electrophoretic deposition (EPD) method. The crystalline structure, the morphology and the composition of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical corrosion test, immersion test, and compression test were used to evaluate the corrosion resistance, the in vitro bioactivity and the mechanical stability of the samples, respectively. The cytocompatibility of the samples was tested by the cell viability and the cell attachment of L-929 cells. The results confirmed that the diopside coating not only slows down the corrosion rate, but also enhances the in vitro bioactivity, mechanical stability and cytocompatibility of AZ91 Mg alloy. Therefore, Mg alloy coated with nanostructured diopside offers a promising approach for biodegradable bone implants. - Highlights: • The diopside coating was applied on Mg alloy using the combined MAO and EPD methods. • The corrosion resistance of the diopside coated Mg alloy was noticeably improved. • The in vitro bioactivity of the diopside coated Mg alloy was considerably increased. • The mechanical stability of biodegradable Mg alloy was enhanced by diopside coating. • The cytocompatibility of the Mg alloy was improved employing diopside coating

In vitro study of nanostructured diopside coating on Mg alloy orthopedic implants

Energy Technology Data Exchange (ETDEWEB)

Razavi, Mehdi, E-mail: mehdi.razavi@okstate.edu [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); School of Materials Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); Fathi, Mohammadhossein [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of); Savabi, Omid [Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Vashaee, Daryoosh [School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); Tayebi, Lobat, E-mail: lobat.tayebi@okstate.edu [School of Materials Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078 (United States)

2014-08-01

The high corrosion rate of Mg alloys has hindered their application in various areas, particularly for orthopedic applications. In order to decrease the corrosion rate and to improve the bioactivity, mechanical stability and cytocompatibility of the Mg alloy, nanostructured diopside (CaMgSi{sub 2}O{sub 6}) has been coated on AZ91 Mg alloy using a combined micro arc oxidation (MAO) and electrophoretic deposition (EPD) method. The crystalline structure, the morphology and the composition of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical corrosion test, immersion test, and compression test were used to evaluate the corrosion resistance, the in vitro bioactivity and the mechanical stability of the samples, respectively. The cytocompatibility of the samples was tested by the cell viability and the cell attachment of L-929 cells. The results confirmed that the diopside coating not only slows down the corrosion rate, but also enhances the in vitro bioactivity, mechanical stability and cytocompatibility of AZ91 Mg alloy. Therefore, Mg alloy coated with nanostructured diopside offers a promising approach for biodegradable bone implants. - Highlights: • The diopside coating was applied on Mg alloy using the combined MAO and EPD methods. • The corrosion resistance of the diopside coated Mg alloy was noticeably improved. • The in vitro bioactivity of the diopside coated Mg alloy was considerably increased. • The mechanical stability of biodegradable Mg alloy was enhanced by diopside coating. • The cytocompatibility of the Mg alloy was improved employing diopside coating.

Effect of Al and Mg Contents on Wettability and Reactivity of Molten Zn-Al-Mg Alloys on Steel Sheets Covered with MnO and SiO2 Layers

Science.gov (United States)

Huh, Joo-Youl; Hwang, Min-Je; Shim, Seung-Woo; Kim, Tae-Chul; Kim, Jong-Sang

2018-05-01

The reactive wetting behaviors of molten Zn-Al-Mg alloys on MnO- and amorphous (a-) SiO2-covered steel sheets were investigated by the sessile drop method, as a function of the Al and Mg contents in the alloys. The sessile drop tests were carried out at 460 °C and the variation in the contact angles (θc) of alloys containing 0.2-2.5 wt% Al and 0-3.0 wt% Mg was monitored for 20 s. For all the alloys, the MnO-covered steel substrate exhibited reactive wetting whereas the a-SiO2-covered steel exhibited nonreactive, nonwetting (θc > 90°) behavior. The MnO layer was rapidly removed by Al and Mg contained in the alloys. The wetting of the MnO-covered steel sheet significantly improved upon increasing the Mg content but decreased upon increasing the Al content, indicating that the surface tension of the alloy droplet is the main factor controlling its wettability. Although the reactions of Al and Mg in molten alloys with the a-SiO2 layer were found to be sluggish, the wettability of Zn-Al-Mg alloys on the a-SiO2 layer improved upon increasing the Al and Mg contents. These results suggest that the wetting of advanced high-strength steel sheets, the surface oxide layer of which consists of a mixture of MnO and SiO2, with Zn-Al-Mg alloys could be most effectively improved by increasing the Mg content of the alloys.

The effect of changing seawater Ca and Mg concentrations upon the distribution coefficients of Mg and Sr in the skeletons of the scleractinian coral Pocillopora damicornis

Science.gov (United States)

Giri, Sharmila J.; Swart, Peter K.; Devlin, Quinn B.

2018-02-01

The skeletal composition of calcifying organisms, in particular Mg/Ca and Sr/Ca ratios, have been widely used to understand fluctuations in seawater chemistry throughout the Phanerozoic. While the success of applying these data to the geologic record depends on a knowledge of the distribution coefficients for these elements (DMg and DSr), there are scarcely any studies which have described how these values vary as a result of changing seawater Mg/Ca ratios. To address this, we have cultured the scleractinian coral, Pocillopora damicornis, in seawater with ranges of Mg and Ca concentrations. Here, we demonstrate that Mg/Ca and Sr/Ca ratios of coral skeletons correlate with total seawater Mg/Ca and Sr/Ca molar ratios, but that apparent DMg and DSr values do not remain constant across the range of experimental seawater treatments, with DMg values significantly increasing with seawater Mg/Ca ratios and DSr values significantly increasing with seawater Ca concentrations. These trends are not rate dependent and may be best explained by a Rayleigh distillation model, in which the calcifying space is semi-isolated from seawater during skeletogenesis (i.e. leaky). As there is a slight increase in DMg and decrease in DSr values between our "Jurassic" and "Modern" seawater treatments, the application of a constant distribution coefficient to estimate changes in ancient seawater chemistry may underestimate seawater Mg/Ca ratios and overestimate Sr/Ca throughout the Mesozoic and Cenozoic. We suggest that interpretations of seawater chemistry from fossil corals may be improved by using the relationships derived for skeletal and seawater Mg/Ca and Sr/Ca ratios established by our experiments, as they incorporate the effect of seawater Mg/Ca ratios on skeletal Mg/Ca and Sr/Ca ratios.

Krill oil significantly decreases 2-arachidonoylglycerol plasma levels in obese subjects

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Giordano Elena

2011-01-01

Full Text Available Abstract We have previously shown that krill oil (KO, more efficiently than fish oil, was able to downregulate the endocannabinoid system in different tissues of obese zucker rats. We therefore aimed at investigating whether an intake of 2 g/d of either KO or menhaden oil (MO, which provides 309 mg/d of EPA/DHA 2:1 and 390 mg/d of EPA/DHA 1:1 respectively, or olive oil (OO for four weeks, is able to modify plasma endocannabinoids in overweight and obese subjects. The results confirmed data in the literature describing increased levels of endocannabinoids in overweight and obese with respect to normo-weight subjects. KO, but not MO or OO, was able to significantly decrease 2-arachidonoylglycerol (2-AG, although only in obese subjects. In addition, the decrease of 2-AG was correlated to the plasma n-6/n-3 phospholipid long chain polyunsaturated fatty acid (LCPUFA ratio. These data show for the first time in humans that relatively low doses of LCPUFA n-3 as KO can significantly decrease plasma 2-AG levels in obese subjects in relation to decrease of plasma phospholipid n-6/n-3 LCPUFA ratio. This effect is not linked to changes of metabolic syndrome parameters but is most likely due to a decrease of 2-AG biosynthesis caused by the replacement of 2-AG ultimate precursor, arachidonic acid, with n-3 PUFAs, as previously described in obese Zucker rats.

Influence of minor alloying additions on the glass-forming ability of Mg-Ni-La bulk metallic glasses

International Nuclear Information System (INIS)

Gonzalez, S.; Figueroa, I.A.; Todd, I.

2009-01-01

Bulk metallic glasses of Mg 60 Ni 23.6 Y x La (16.4-x) and Mg 65 Ni 20 Y x LaMM (15-x) with 0 ≤ x ≤ 1 at.% have been produced by injection casting. For the La-containing alloy a maximum amorphous diameter of 4 mm for x = 0.5 and 0.75 was obtained. The LaMM-containing alloy showed a maximum amorphous diameter of 2 mm for x = 0 and 0.25 but decreased to 1 mm with further Y additions. The glass-forming ability of the Mg 60 Ni 23.6 La 16.4 alloy decreased when La is partially substituted by small amounts of small atoms (Si or B) or by large atoms (Y and Si).

Evolution of Microstructure in Rolled Mg-Based Alloy. Textural Aspect / Ewolucja Mikrostruktury W Walcowanym Stopie Na Bazie Mg. Aspekt Teksturowy

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Drzymała P.

2015-12-01

Full Text Available Magnesium alloys are the lightest structural materials, which makes them particularly suitable for use in the aircraft and automotive industry. However, due to hexagonal close-packed crystal structure, resulting in insufficient number of independent slip systems, magnesium alloys exhibit poor formability at room temperature. Conventional methods of work hardening of magnesium alloys requires the temperature about 300°C, which favours simultaneously processes of thermal recovery and grain growth, but decreases beneficial microstructure strengthening effect. Thus, it is a crucial to undertake development of a technology for semi-finished magnesium alloys elements, which will ensure better mechanical properties of the final products by forming desirable microstructure. In the paper we present the development of crystallographic texture of the Mg-based alloy (Mg-AZ31 in the form of pipe extruded at 430°C and subjected to pilger rolling at relatively low temperature.

Hydrothermal replacement of calcite by Mg-carbonates

Science.gov (United States)

Jonas, Laura; Mueller, Thomas; Dohmen, Ralf

2014-05-01

phases increases with increasing distance from the unreacted calcite core, countered by a decrease of Ca incorporated. Both the coexistence of two different product phases and the distinct compositional gradient within the forming reaction rim are unequivocal signs of a chemical zonation of Ca and Mg in the fluid phase which mediates the element exchange between the reaction interface and the bulk solution. Atomic adsorption spectroscopy revealed that the Ca/Mg ratio in the reacted fluid increases as a function of time, reflecting the progressive exchange of Mg and Ca between the fluid and the solid phase. The time-dependence of the evolving Ca/Mg ratio can be fitted with a square root of time relation that indicates a transport controlled reaction. We interpret the hydrothermal replacement of calcite to operate via a dissolution/re-precipitation mechanism, whereas the reaction progress is controlled by the transport of the structure forming elements through the developing reaction rim.

Effects of aqueous extract of Hibiscus sabdariffa on renal Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase activities in Wistar rats.

Science.gov (United States)

Olatunji, Lawrence A; Usman, Taofeek O; Adebayo, Joseph O; Olatunji, Victoria A

2012-09-01

To investigate the effects of oral administration of aqueous extract of Hibiscus sabdariffa on renal Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase activities in rats. The 25 and 50 mg/(kg·d) of aqueous extracts of H. sabdariffa were respectively given to rats in the experimental groups for 28 d, and rats in the control group received an appropriate volume of distilled water as vehicle. Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase activities in the kidney were assayed by spectrophotometric method. Administrations of 25 and 50 mg/(kg·d) of aqueous extract of H. sabdariffa significantly decreased the Ca(2+)-Mg(2+)-ATPase activity in the kidney of rats (Psabdariffa may preserve the renal function despite a decreased renal Ca(2+)-Mg(2+)-ATPase activity.

Studies on Al-Mg solid solutions using electrical resistivity and microhardness measurements

Energy Technology Data Exchange (ETDEWEB)

Gaber, A.; Afify, N.; El-Halawany, S.M.; Mossad, A. [Assiut Univ. (Egypt). Dept. of Physics

1999-08-01

Al-C at% Mg alloys (C = 0.82, 1.84, 3.76, 5.74 and 12.18) have been selected for this study. From the electrical resistivity measurements it is concluded that the resistivity increment of Al-Mg alloys (in a solid solution state) is proportional to the atomic fractional constituents (Mg and Al) as {delta}{rho}{sub all} = 64.66 c(1-c) {mu}{omega} cm. In addition, both the temperature coefficient of resistivity, {alpha}{sub all} and the relaxation time of the free electrons {tau}{sub all} in the alloys diminish with increasing the solute Mg concentration. The increase of the scattering power, {eta}, with increasing C is interpreted to be due to the contribution of electron-impurity scattering. The percentage increase due to electron-impurity scattering per one atomic percent Mg has been determined as 12.99%. The Debye temperature {theta} decreases as the Mg concentration increases. The microhardness results showed that the solid solution hardening obeys the relation {delta}HV{sub s} = 135.5C{sup 0.778} MPa which is comparable to the theory of solid solution hardening for all alloys; {delta}HV{sub s} {approx} C{sup 0.5-0.67} MPa. (orig.)

Microstructure, corrosion behavior and cytotoxicity of biodegradable Mg-Sn implant alloys prepared by sub-rapid solidification.

Science.gov (United States)

Zhao, Chaoyong; Pan, Fusheng; Zhao, Shuang; Pan, Hucheng; Song, Kai; Tang, Aitao

2015-09-01

In this study, biodegradable Mg-Sn alloys were fabricated by sub-rapid solidification, and their microstructure, corrosion behavior and cytotoxicity were investigated by using optical microscopy, scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, X-ray diffraction, immersion test, potentiodynamic polarization test and cytotoxicity test. The results showed that the microstructure of Mg-1Sn alloy was almost equiaxed grain, while the Mg-Sn alloys with higher Sn content (Sn≥3 wt.%) displayed α-Mg dendrites, and the secondary dendrite arm spacing of the primary α-Mg decreased significantly with increasing Sn content. The Mg-Sn alloys consisted of primary α-Mg matrix, Sn-rich segregation and Mg2Sn phase, and the amount of Mg2Sn phases increased with increasing Sn content. Potentiodynamic polarization and immersion tests revealed that the corrosion rates of Mg-Sn alloys increased with increasing Sn content. Cytotoxicity test showed that Mg-1Sn and Mg-3Sn alloys were harmless to MG63 cells. These results of the present study indicated that Mg-1Sn and Mg-3Sn alloys were promising to be used as biodegradable implants. Copyright © 2015 Elsevier B.V. All rights reserved.

Rapidly decreased serum IgG to Campylobacter pylori following elimination of Campylobacter in histological chronic biopsy Campylobacter-positive gastritis.

Science.gov (United States)

van Bohemen, C G; Langenberg, M L; Rauws, E A; Oudbier, J; Weterings, E; Zanen, H C

1989-01-15

The anaerobic bacterium Campylobacter pylori (Cp) is thought to be associated with chronic gastritis. This paper presents clinical data underpinning this view. Five patients with histological chronic gastritis as determined by diagnostic endoscopy, which was associated with Cp as determined by positive biopsy cultures, all possessed statistically raised serum IgG ELISA titers to Cp during a longitudinal period of observation of 15 months. Treatment with the antibiotics amoxycillin (clamoxyl) or colloidal bismuth subcitrate (denol) eliminated Cp within one month. Associated with this, serum IgG ELISA titers were found to decrease sharply and rapidly. Tagamet and spiramycin had little effect. Although the data are preliminary, they support the assumed Cp involvement in chronic gastritis and suggest that specific serum IgG ELISA titers to Cp are useful parameters in monitoring disease status, exceeding bacteriological culture of biopsy specimens in speed and convenience.

Corrosion behavior of as-cast binary Mg-Bi alloys in Hank's solution

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Wei-li Cheng

2015-11-01

Full Text Available Biodegradable Mg-xBi (x = 3, 6 and 9wt.% alloys were fabricated by ingot casting, and the change of corrosion behavior of the alloys in the Hank's solution was analyzed with respect to the microstructure using optical micrograph (OM, X-ray diffraction (XRD, scanning electron microscope (SEM equipped with an energy dispersive X-ray spectrometer (EDS, electrochemical and immersion tests. The results show that the microstructures of the as-cast Mg-Bi alloys mainly consisted of dendritic ?Mg grains and Mg3Bi2 phase in common, with the secondary dendrite arm spacing (SDAS decreasing significantly from 41.2 靘 to 25.4 靘 and the fraction of Mg3Bi2 increasing from 3.1% to 10.7%. Furthermore, the corrosion rate increasing from 1.32 mm昦-1 to 8.07 mm昦-1 as the Bi content was increased from 3wt.% to 9wt.%. The reduced corrosion resistance was mainly ascribed to the increasing fraction of the second phase particles, which bring positive effects on the development of pitting.

Presence and Impact of Surface Films formed on Mg in Chloroaluminate Electrolytes.

Energy Technology Data Exchange (ETDEWEB)

Hahn, Nathan [Argonne National Lab. (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research (JCESR); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kotula, Paul G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wetzel, David J. [Argonne National Lab. (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research (JCESR); Univ. of Illinois, Urbana-Champaign, IL (United States); Malone, Marvin A. [Argonne National Lab. (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research (JCESR); Univ. of Illinois, Urbana-Champaign, IL (United States); Nuzzo, Ralph G. [Argonne National Lab. (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research (JCESR); Univ. of Illinois, Urbana-Champaign, IL (United States); Zavadil, Kevin R. [Argonne National Lab. (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research (JCESR); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-09-01

The impact of surface film formation on Mg is explored during electrodeposition and electrodissolution in two high activity, aprotic electrolytes: the all phenyl complex (APC) and the magnesium aluminum chloride complex (MACC). Where past studies have argued such films are benign, results show that interfacial films are responsible for controlling the Mg deposit structure when deposition and dissolution are conducted at the rates required for practical Mg batteries. Chronopotentiometry is shown to provide clear signatures of the impact of interfacial films on deposition and dissolution. The particular combination of cycling punctuated by periods of open circuit equilibration is shown to yield a noticeable decrease in coulombic efficiency over a 50 cycle sequence. High resolution electron imaging shows that cycling results in porosity development and accumulation of electrolyte constituents within the deposit. Reduced coulombic efficiency signaling Mg loss appears related to progressive isolation of a fraction of the deposit. Mg and electrolyte loss must be compensated for in a practical cell through the introduction of excess inventory and resulting in a reduced energy density of the system.

The Use of Mg(OH2 in the Final Peroxide Bleaching Stage of Wheat Straw Pulp

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Yan-Lan Liu

2013-11-01

Full Text Available Magnesium-based alkali is an attractive alkaline source for the peroxide bleaching of high-yield pulp. However, little information is available on Mg(OH2 application in the final peroxide bleaching stage of wheat straw pulp. The use of Mg(OH2 was demonstrated as a partial replacement for NaOH in the peroxide bleaching of a chelated oxygen-delignified wheat straw pulp. The yield, viscosity, and strength properties of bleached pulp significantly increased with increasing replacement ratio of Mg(OH2, while the chemical oxygen demand load (COD of filtrate was decreased. For similar brightness of bleached pulp at a 24% replacement ratio of Mg(OH2, the tensile and tear indices were higher, by 2.1 Nm.g-1 and 1.75 mN*m2.g-1, respectively, than that of control pulp bleached with NaOH as the sole alkaline source. When the MgSO4 was eliminated and the dosage of Na2SiO3 was decreased in the bleaching process, the tear and burst indices of the bleached pulp were also enhanced, with the brightness maintained. Scanning electron microscopy (SEM showed that more swelling occurred in the fibers of bleached pulp from the Mg(OH2-based bleaching process. Fiber analysis indicated that peroxide bleaching with Mg(OH2 increased the proportion of fiber lengths between 0.20 to 1.20 mm and 1.20 to 7.60 mm.

Annealing effect of thermal spike in MgO thin film prepared by cathodic vacuum arc deposition

Energy Technology Data Exchange (ETDEWEB)

Zhu, Daoyun, E-mail: zhudy@gdut.edu.cn [Experiment Teaching Department, Guangdong University of Technology, Guangzhou 510006 (China); State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Zhao, Shoubai [School of Physics and Electronic Engineering, Guangzhou University, Guangzhou 510400 (China); Zheng, Changxi; Chen, Dihu [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); He, Zhenhui, E-mail: stshzh@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

2013-12-16

MgO films were prepared by using pulsed cathodic vacuum arc deposition technique. The substrate bias voltage was in the range of −150 to −750 V. Film structure was investigated by X-ray diffraction (XRD). The annealing effect of thermal spike produced by the impacting of energetic ions was analyzed. The calculated results showed that the lifetime of a thermal spike generated by an energetic ion with the energy of 150 eV was less than one picosecond and it was sufficient to allow Mg{sup 2+} or O{sup 2-} to move one bond length to satisfy the intrinsic stress relief in the affected volume. The MgO(200) lattice spacings of the films deposited at different bias voltages were all larger than the ideal value of 2.1056 Å. As the bias amplitude increased the lattice spacing decreased, which indicated that the compressive stress in the film was partially relieved with increasing impacting ion energy. The stress relief also could be reflected from the film orientation with bias voltage. The biaxial elastic modulus for MgO(100), MgO(110) and MgO(111) planes were calculated and they were M{sub (100)} = 199 GPa, M{sub (110)} = 335 GPa and M{sub (111)} = 340 GPa, respectively. The M values indicated that the preferred orientation will be MgO(200) due to the minimum energy configuration when the lattice strain was large. It was confirmed by the XRD results in our experiments. - Highlights: • MgO thin films with preferred orientation were obtained by CVAD technique. • Annealing effect of a thermal spike in MgO film was discussed. • Lattice spacing of MgO film decreased with the increase of bias voltage. • Film preferred orientation changed from (200) to (220) as the bias voltage increased.

Structure and properties of Al-Mg-Li-Zr system alloys

International Nuclear Information System (INIS)

Fridlyander, I.N.; Dolzhanskij, Yu.M.; Sandler, V.S.; Tyurin, .V.; Nikol'skaya, T.I.

1977-01-01

Studied were the structure and mechanical properties of the Al-Mg-Li-Zr alloy system (including 01420 alloy) containing 1.6-5.3%Li and 1.0-8.8%Mg). Electron microscopic studies of 01420 alloy conducted after heating at 450 deg C for 4 hours revealed non-uniformly distributed precipitations of a metastable phase ZrAl 3 , having spherical and needle-like configurations. These precipitations, together with zirconium contained in the solid solution, retard recrystallization. The introduction of 0.1-0.2% Zr decreases the limiting solubility of magnesium and lithium in the aluminium solid solution and leads to the formation of disperse equilibrium (S and, possibly, γ) phases with the size of 0.1-0.5 mcm. These phases were observed in the alloys containing (>=) 4% Mg and 1.9-3.5% Li. The method of planned experiment was used to study the principles governing the variation of the mechanical properties of the alloys subjected to water hardening and after aging at 170 deg C for 16 hours. It was established that the strength properties of the hardened alloys become higher, and the relative elongation decreases with the content of lithium and especially magnesium. It would be more proper to assess strengthening in the course of aging according to variation in the yield point and hardness. The effect of aging determined by the yield point depends on the content of lithium and is practically independent of the concentration of magnesium

Dynamic Recrystallization Behavior and Corrosion Resistance of a Dual-Phase Mg-Li Alloy

Directory of Open Access Journals (Sweden)

Gang Liu

2018-03-01

Full Text Available The hot deformation and dynamic recrystallization behavior of the dual-phase Mg-9Li-3Al-2Sr-2Y alloy had been investigated using a compression test. The typical dual-phase structure was observed, and average of grain size of as-homogenized alloy is about 110 µm. It mainly contains β-Li, α-Mg, Al4Sr and Al2Y phases. The dynamic recrystallization (DRX kinetic was established based on an Avrami type equation. The onset of the DRX process occurred before the peak of the stress–strain flow curves. It shows that the DRX volume fraction increases with increasing deformation temperature or decreasing strain rate. The microstructure evolution during the hot compression at various temperatures and strain rates had been investigated. The DRX grain size became larger with the increasing testing temperature or decreasing strain rate because the higher temperature or lower strain rate can improve the migration of DRX grain boundaries. The fully recrystallized microstructure can be achieved in a small strain due to the dispersed island-shape α-Mg phases, continuous the Al4Sr phases and spheroidal Al2Y particles, which can accelerate the nucleation. The continuous Al4Sr phases along the grain boundaries are very helpful for enhancing the corrosion resistance of the duplex structured Mg-Li alloy, which can prevent the pitting corrosion and filiform corrosion.

Dynamic Recrystallization Behavior and Corrosion Resistance of a Dual-Phase Mg-Li Alloy.

Science.gov (United States)

Liu, Gang; Xie, Wen; Wei, Guobing; Yang, Yan; Liu, Junwei; Xu, Tiancai; Xie, Weidong; Peng, Xiaodong

2018-03-09

The hot deformation and dynamic recrystallization behavior of the dual-phase Mg-9Li-3Al-2Sr-2Y alloy had been investigated using a compression test. The typical dual-phase structure was observed, and average of grain size of as-homogenized alloy is about 110 µm. It mainly contains β-Li, α-Mg, Al₄Sr and Al₂Y phases. The dynamic recrystallization (DRX) kinetic was established based on an Avrami type equation. The onset of the DRX process occurred before the peak of the stress-strain flow curves. It shows that the DRX volume fraction increases with increasing deformation temperature or decreasing strain rate. The microstructure evolution during the hot compression at various temperatures and strain rates had been investigated. The DRX grain size became larger with the increasing testing temperature or decreasing strain rate because the higher temperature or lower strain rate can improve the migration of DRX grain boundaries. The fully recrystallized microstructure can be achieved in a small strain due to the dispersed island-shape α-Mg phases, continuous the Al₄Sr phases and spheroidal Al₂Y particles, which can accelerate the nucleation. The continuous Al₄Sr phases along the grain boundaries are very helpful for enhancing the corrosion resistance of the duplex structured Mg-Li alloy, which can prevent the pitting corrosion and filiform corrosion.

Influence of hydrogen impurities on p-type resistivity in Mg-doped GaN films

International Nuclear Information System (INIS)

Yang, Jing; Zhao, Degang; Jiang, Desheng; Chen, Ping; Zhu, Jianjun; Liu, Zongshun; Le, Lingcong; He, Xiaoguang; Li, Xiaojing; Zhang, Y. T.; Du, G. T.

2015-01-01

The effects of hydrogen impurities on p-type resistivity in Mg-doped GaN films were investigated. It was found that hydrogen impurities may have the dual role of passivating Mg Ga acceptors and passivating donor defects. A decrease in p-type resistivity when O 2 is introduced during the postannealing process is attributed to the fact that annealing in an O 2 -containing environment can enhance the dissociation of Mg Ga -H complexes as well as the outdiffusion of H atoms from p-GaN films. However, low H concentrations are not necessarily beneficial in Mg-doped GaN films, as H atoms may also be bound at donor species and passivate them, leading to the positive effect of reduced compensation

Effects of Cp2Mg supply on MOVPE growth behavior of InN

International Nuclear Information System (INIS)

Sugita, K.; Sasamoto, K.; Hashimoto, A.; Yamamoto, A.

2011-01-01

This report shows the effect of Cp 2 Mg supply on MOVPE growth behavior of InN. At low growth temperature (∝600 C), the formation of adducts occurred, which degenerates the crystal quality. With increasing the growth temperature, the adduct formation was suppressed because the decomposition of Cp 2 Mg was enhanced and thus the incorporation of carbon into the film was suppressed. The use of Cp 2 Mg during InN growth increases the growth rate in the lateral direction. Non-doped InN film grown on GaN buffer has an In-face of the top side. On the other hand, the inversion domains seems to be formed in the highly Mg-doped InN. Tilt distribution decreases from 65 to 30 arcmin with the increase of Cp 2 Mg/TMI molar ratio 0 to 0.06. The donor is produced in highly Mg-doped MOVPE-grown InN (Cp 2 Mg/TMI molar ratio > 0.005). Therefore, the effect of Cp 2 Mg supply on MOVPE growth behavior of InN is found to improve a macro-scale crystal quality but also produces the donor (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Laser cladding of a Mg based Mg–Gd–Y–Zr alloy with Al–Si powders

International Nuclear Information System (INIS)

Chen, Erlei; Zhang, Kemin; Zou, Jianxin

2016-01-01

Graphical abstract: A Mg based Mg–Gd–Y–Zr alloy was treated by laser cladding with Al–Si powders at different laser scanning speeds. The laser clad layer mainly contains Mg_2Si, Mg_1_7Al_1_2 and Al_2(Gd,Y) phases distributed in the Mg matrix. After laser cladding, the corrosion resistance of the Mg alloy was significantly improved together with increased microhardness in the laser clad layers. - Highlights: • A Mg based Mg–Gd–Y–Zr alloy was laser clad with Al–Si powders. • The microstructure and morphology vary with the depth of the clad layer and the laser scanning speed. • Hardness and corrosion resistance were significantly improved after laser cladding. - Abstract: In the present work, a Mg based Mg–Gd–Y–Zr alloy was subjected to laser cladding with Al–Si powders at different laser scanning speeds in order to improve its surface properties. It is observed that the laser clad layer mainly contains Mg_2Si, Mg_1_7Al_1_2 and Al_2(Gd,Y) phases distributed in the Mg matrix. The depth of the laser clad layer increases with decreasing the scanning speed. The clad layer has graded microstructures and compositions. Both the volume fraction and size of Mg_2Si, Mg_1_7Al_1_2 and Al_2(Gd,Y) phases decreases with the increasing depth. Due to the formation of these hardening phases, the hardness of clad layer reached a maximum value of HV440 when the laser scanning speed is 2 mm/s, more than 5 times of the substrate (HV75). Besides, the corrosion properties of the untreated and laser treated samples were all measured in a NaCl (3.5 wt.%) aqueous solution. The corrosion potential was increased from −1.77 V for the untreated alloy to −1.13 V for the laser clad alloy with scanning rate of 2 mm/s, while the corrosion current density was reduced from 2.10 × 10"−"5 A cm"−"2 to 1.64 × 10"−"6 A cm"−"2. The results show that laser cladding is an efficient method to improve surface properties of Mg–Rare earth alloys.

Structural and magnetic properties of Mg doped YbMnO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Sattibabu, Bhumireddi, E-mail: bsb.satti@gmail.com [School of Engineering Sciences and Technology, University of Hyderabad, Hyderabad 500046 (India); Bhatnagar, Anil K., E-mail: anilb42@gmail.com [School of Engineering Sciences and Technology, University of Hyderabad, Hyderabad 500046 (India); School of Physics, University of Hyderabad, Hyderabad 500046 (India); Rayaprol, Sudhindra [UGC-DAE CSR, Mumbai Centre, R-5 Shed, BARC, Mumbai 400085 (India); Mohan, Dasari; Das, Dibakar; Sundararaman, Mahadevan [School of Engineering Sciences and Technology, University of Hyderabad, Hyderabad 500046 (India); Siruguri, Vasudeva [UGC-DAE CSR, Mumbai Centre, R-5 Shed, BARC, Mumbai 400085 (India)

2014-09-01

We have studied the effect of Mg doping on structure and magnetism of multiferroic YbMnO{sub 3}. Room temperature neutron diffraction studies were carried out on polycrystalline Yb{sub 1−x}Mg{sub x}MnO{sub 3} (x=0.00 and 0.05) samples to determine phase formation as well as cation distribution and structural properties such as bond length and bond angles. The structural analysis shows that with Mg substitution, there is a marginal change in a and c parameters of the hexagonal unit cell, c/a ratio remains constant for x=0 and 0.05 samples. Due to changes in bond angle and bond lengths on substituting Mg, there is a slight decrease in the distortion of MnO{sub 5} polyhedra. Magnetic measurements show that the Néel temperature (T{sub N}) increases marginally from 85 K for x=0.00 to 89 K for x=0.05 sample.

Relativistic quasiparticle band structures of Mg2Si, Mg2Ge, and Mg2Sn: Consistent parameterization and prediction of Seebeck coefficients

Science.gov (United States)

Shi, Guangsha; Kioupakis, Emmanouil

2018-02-01

We apply density functional and many-body perturbation theory calculations to consistently determine and parameterize the relativistic quasiparticle band structures of Mg2Si, Mg2Ge, and Mg2Sn, and predict the Seebeck coefficient as a function of doping and temperature. The quasiparticle band gaps, including spin-orbit coupling effects, are determined to be 0.728 eV, 0.555 eV, and 0.142 eV for Mg2Si, Mg2Ge, and Mg2Sn, respectively. The inclusion of the semicore electrons of Mg, Ge, and Sn in the valence is found to be important for the accurate determination of the band gaps of Mg2Ge and Mg2Sn. We also developed a Luttinger-Kohn Hamiltonian and determined a set of band parameters to model the near-edge relativistic quasiparticle band structure consistently for all three compounds that can be applied for thermoelectric device simulations. Our calculated values for the Seebeck coefficient of all three compounds are in good agreement with the available experimental data for a broad range of temperatures and carrier concentrations. Our results indicate that quasiparticle corrections are necessary for the accurate determination of Seebeck coefficients at high temperatures at which bipolar transport becomes important.

The Influence of CuFe2O4 Nanoparticles on Superconductivity of MgB2

Science.gov (United States)

Novosel, Nikolina; Pajić, Damir; Skoko, Željko; Mustapić, Mislav; Babić, Emil; Zadro, Krešo; Horvat, Joseph

The influence of CuFe2O4 nanoparticle doping on superconducting properties of Fe-sheated MgB2 wires has been studied. The wires containing 0, 3 and 7.5 wt.% of monodisperse superparamagnetic nanoparticles (˜7 nm) were sintered at 650°C or 750°C for 1 hour in the pure argon atmosphere. X-ray diffraction patterns of doped samples showed very small maxima corresponding to iron boride and an increase in the fraction of MgO phase indicating some interaction of nanoparticles with Mg and B. Both magnetic and transport measurements (performed in the temperature range 2-42 K and magnetic field up to 16 T) showed strong deterioration of the superconducting properties upon doping with CuFe2O4. The transition temperatures, Tc, of doped samples decreased for about 1.4 K per wt.% of CuFe2O4. Also, the irreversibility fields Birr(T) decreased progressively with increasing doping. Accordingly, also the suppression of Jc with magnetic field became stronger. The observed strong deterioration of superconducting properties of MgB2 wires is at variance with reported enhancement of critical currents at higher temperatures (determined from magnetization) in bulk MgB2 samples doped with Fe3O4 nanoparticles. The probable reason for this discrepancy is briefly discussed

Dehydriding and rehydriding properties of Mg(NH2)2-LiH systems

International Nuclear Information System (INIS)

Aoki, M.; Noritake, T.; Nakamori, Y.; Towata, S.; Orimo, S.

2007-01-01

The dehydriding and rehydriding properties of the mixtures of 3Mg(NH 2 ) 2 + nLiH (n = 6, 8, and 12) were investigated by pressure-composition (p-c) isotherm and X-ray diffraction (XRD) measurements in order to clarify the effects of the LiH ratio n on the properties. The amounts of the hydrogen desorbed from the mixtures with n = 6, 8, and 12 were 5.4, 5.1, and 4.5 mass%, respectively; this indicates that the amounts on a unit mass basis decrease with increasing n. However, the molar ratios of the desorbed hydrogen to the mixtures estimated from the amounts were almost equal, and also the features of the p-c isotherms were similar to each other. Moreover, the Li 2 Mg(NH) 2 and LiH phases were observed in XRD profiles of all the mixtures after p-c isotherm measurements. These results suggest that the dehydriding reaction of the mixtures of 3Mg(NH 2 ) 2 + nLiH (n = 6, 8, and 12) under hydrogen pressure is not dominantly affected by the value of n. On the other hand, the amounts of the ammonia desorbed from the mixtures detected by mass spectroscopy decreased with increasing n

Effects of Y content on microstructures and mechanical properties of as-cast Mg-Zn-Nd

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Ti-jun Chen

2015-09-01

Full Text Available The effects of Y addition amount on the microstructures and mechanical properties of as-cast Mg-Zn-Nd alloy have been investigated by using an optical microscope, a scanning electron microscope, back-scattered electronic imaging technique, an X-ray diffractometer, a differential thermal analyzer and a universal testing machine. There are three kinds of ternary phases in the Mg-Zn-Y system alloys, such as I phase (Mg3Zn6Y, W phase (Mg3Zn3Y2 and Z or X phase (Mg12ZnY. The experimental results in the present study indicate that the Mg-Zn-RE (RE includes Y and Nd ternary phases change from the I + W phases in turn to unique W, W + Z and unique Z as the Y content increases from 0% to 3%. Simultaneously, their distribution gradually changes from small particle-like form to continuous network form. The grain size first decreases as the Y content increases from 0% to 1% Y, then increases when the Y content exceeds 1% and finally decreases again when the content exceeds 3% due to the variation of growth restriction factor caused by the increased Y element and the change of the ternary phases. The hardness continuously increases because of the increased ternary phase amount. The ultimate tensile strength and elongation first increase within the range of 0-1% Y, also due to the increased ternary phase amount and grain refinement, and then decreases because of the grain coarsening, porosity formation and continuous network distribution of the ternary phases. The grain bonding strength of the W phase-containing alloys is quite strong and the W phase is an ideal strengthening phase if a given amount of it distributes in discontinuous and small-sized form. The alloy with 1% Y only has one ternary phase of W, but has the best combination of mechanical properties. The fracture regimes of these alloys always present a transgranular mode.

Mg isotope systematics during magmatic processes: Inter-mineral fractionation in mafic to ultramafic Hawaiian xenoliths

Science.gov (United States)

Stracke, A.; Tipper, E. T.; Klemme, S.; Bizimis, M.

2018-04-01

Observed differences in Mg isotope ratios between bulk magmatic rocks are small, often on a sub per mill level. Inter-mineral differences in the 26Mg/24Mg ratio (expressed as δ26Mg) in plutonic rocks are on a similar scale, and have mostly been attributed to equilibrium isotope fractionation at magmatic temperatures. Here we report Mg isotope data on minerals in spinel peridotite and garnet pyroxenite xenoliths from the rejuvenated stage of volcanism on Oahu and Kauai, Hawaii. The new data are compared to literature data and to theoretical predictions to investigate the processes responsible for inter-mineral Mg isotope fractionation at magmatic temperatures. Theory predicts up to per mill level differences in δ26Mg between olivine and spinel at magmatic temperatures and a general decrease in Δ26Mgolivine-spinel (=δ26Mgolivine - δ26Mgspinel) with increasing temperature, but also with increasing Cr# in spinel. For peridotites with a simple petrogenetic history by melt depletion, where increasing depletion relates to increasing melting temperatures, Δ26Mgolivine-spinel should thus systematically decrease with increasing Cr# in spinel. However, most natural peridotites, including the Hawaiian spinel peridotites investigated in this study, are overprinted by variable extents of melt-rock reaction, which disturb the systematic primary temperature and compositionally related olivine-spinel Mg isotope systematics. Diffusion, subsolidus re-equilibration, or surface alteration may further affect the observed olivine-spinel Mg isotope fractionation in peridotites, making Δ26Mgolivine-spinel in peridotites a difficult-to-apply geothermometer. The available Mg isotope data on clinopyroxene and garnet suggest that this mineral pair is a more promising geothermometer, but its application is restricted to garnet-bearing igneous (garnet pyroxenites) and metamorphic rocks (eclogites). Although the observed δ26Mg variation is on a sub per mill range in bulk magmatic rocks

Chondrogenic differentiation of ATDC5-cells under the influence of Mg and Mg alloy degradation

Energy Technology Data Exchange (ETDEWEB)

Martinez Sanchez, Adela H., E-mail: adela.martinez@hzg.de [Helmholtz-Zentrum Geesthacht, Institute of Material Research, Department for Structural Research on Macromolecules, Geesthacht (Germany); Feyerabend, Frank; Laipple, Daniel; Willumeit-Römer, Regine [Helmholtz-Zentrum Geesthacht, Institute of Material Research, Department for Structural Research on Macromolecules, Geesthacht (Germany); Weinberg, Annelie [Department of Orthopedics and Orthopedic Surgery, Medical University of Graz (Austria); Luthringer, Bérengère J.C. [Helmholtz-Zentrum Geesthacht, Institute of Material Research, Department for Structural Research on Macromolecules, Geesthacht (Germany)

2017-03-01

Biodegradable magnesium (Mg)-based materials are a potential alternative to permanent implants for application in children. Nevertheless effects of those materials on growth plate cartilage and chondrogenesis have not been previously evaluated. In vitro differentiation of ATDC5 cells was evaluated under the influence of pure Mg (PMg), Mg with 10 wt% of gadolinium (Mg-10Gd) and Mg with 2 wt% of silver (Mg-2Ag) degradation products (extracts) and direct cell culture on the materials. Gene expression showed an inhibitory effect on ATDC5 mineralization with the three extracts and a chondrogenic potential of Mg-10Gd. Cells cultured in Mg-10Gd and Mg-2Ag extracts showed the same proliferation and morphology than cells cultured in growth conditions. Mg-10Gd induced an increase in production of ECM and a bigger cell size, similar to the effects found with differentiation conditions. An increased metabolic activity was observed in cells cultured under the influence of Mg-10Gd extracts, indicated by an acidic pH during most of the culture period. After 7 days of culture on the materials, ATDC5 growth, distribution and ECM synthesis were higher on Mg-10Gd samples, followed by Mg-2Ag and PMg, which was influenced by the homogeneity and composition of the degradation layer. This study confirmed the tolerance of ATDC5 cells to Mg-based materials and a chondrogenic effect of Mg-10Gd. Further studies in vitro and in vivo are necessary to evaluate cell reactions to those materials, as well as the effects on bone growth and the biocompatibility of the alloying system in the body. - Highlights: • Degradation of PMg, and Mg-2Ag do not influence ATDC5 cells growth and chondrogenic redifferentiation. • Mg-10Gd enhances fast chondrogenic redifferentiation and expression of hyperthrophic markers on ATDC5 cells. • Further evaluation of the effects of PMg, Mg-10Gd and Mg-2Ag in vivo are necessary to confirm its potential for application in growing bones.

Chondrogenic differentiation of ATDC5-cells under the influence of Mg and Mg alloy degradation

International Nuclear Information System (INIS)

Martinez Sanchez, Adela H.; Feyerabend, Frank; Laipple, Daniel; Willumeit-Römer, Regine; Weinberg, Annelie; Luthringer, Bérengère J.C.

2017-01-01

Biodegradable magnesium (Mg)-based materials are a potential alternative to permanent implants for application in children. Nevertheless effects of those materials on growth plate cartilage and chondrogenesis have not been previously evaluated. In vitro differentiation of ATDC5 cells was evaluated under the influence of pure Mg (PMg), Mg with 10 wt% of gadolinium (Mg-10Gd) and Mg with 2 wt% of silver (Mg-2Ag) degradation products (extracts) and direct cell culture on the materials. Gene expression showed an inhibitory effect on ATDC5 mineralization with the three extracts and a chondrogenic potential of Mg-10Gd. Cells cultured in Mg-10Gd and Mg-2Ag extracts showed the same proliferation and morphology than cells cultured in growth conditions. Mg-10Gd induced an increase in production of ECM and a bigger cell size, similar to the effects found with differentiation conditions. An increased metabolic activity was observed in cells cultured under the influence of Mg-10Gd extracts, indicated by an acidic pH during most of the culture period. After 7 days of culture on the materials, ATDC5 growth, distribution and ECM synthesis were higher on Mg-10Gd samples, followed by Mg-2Ag and PMg, which was influenced by the homogeneity and composition of the degradation layer. This study confirmed the tolerance of ATDC5 cells to Mg-based materials and a chondrogenic effect of Mg-10Gd. Further studies in vitro and in vivo are necessary to evaluate cell reactions to those materials, as well as the effects on bone growth and the biocompatibility of the alloying system in the body. - Highlights: • Degradation of PMg, and Mg-2Ag do not influence ATDC5 cells growth and chondrogenic redifferentiation. • Mg-10Gd enhances fast chondrogenic redifferentiation and expression of hyperthrophic markers on ATDC5 cells. • Further evaluation of the effects of PMg, Mg-10Gd and Mg-2Ag in vivo are necessary to confirm its potential for application in growing bones.

The study on binary Mg-Co hydrogen storage alloys with BCC phase

International Nuclear Information System (INIS)

Zhang Yao; Tsushio, Yoshinori; Enoki, Hirotoshi; Akiba, Etsuo

2005-01-01

Novel Mg-Co binary alloys were successfully synthesized by mechanical alloying. These alloys were studied by X-ray diffraction (XRD), transmission electron micrograph (TEM), pressure-composition-isotherms measurements (P-C-T) and differential scanning calorimetry (DSC). Both XRD Rietveld analysis and TEM observation confirmed that these binary alloys contain BCC phase and that the BCC phase existed in the range from 37 to 80 at.% Co. The lattice parameter of the BCC phase increased with the increase of the Co content from 37 to 50 at.%. When the Co content reached 50 at.%, the lattice parameter reached a maximum value, and then turned to decrease gradually with further increase of the Co content. Most of Mg-Co BCC alloys absorbed hydrogen at 373 K under 6 MPa of hydrogen pressure. The Mg 60 Co 40 alloy showed the highest hydrogen absorption capacity, about 2.7 mass% hydrogen. However, all the Mg-Co alloys studied did not desorb hydrogen at 373 K. By means of DSC measurements and in situ XRD analysis, it was found that under 4 MPa hydrogen atmosphere, Mg 50 Co 50 alloy transformed from BCC solid solution to Mg 2 CoH 5 tetragonal hydride at 413 K

Passivation kinetics of Mg-Nd-Gd-Zn-Zr (EV31A and Mg-Y-Nd-Gd-Zr (WE43C in NaOH solutions

Directory of Open Access Journals (Sweden)

Jakraphan Ninlachart

2017-09-01

Full Text Available Passivation kinetics of two Mg-RE alloys, such as Mg-Nd-Gd-Zn-Zr (EV31A, and Mg-Y-Nd-Gd-Zr (WE43C were investigated in two different heat treated conditions (solution treated and overaged in 0.01 - 1.0 M NaOH solutions under potentiostatic conditions. Negative reaction order was observed in dilute NaOH which transitioned to positive values as the passivation time increased and in the 1 M NaOH as well. The passive layers showed platelet morphology and the size of the platelets decreased with increase in the NaOH concentration. The hydrogen evolution reaction (HER kinetics was not improved on the passive layer covered surface of the Mg-RE alloys in contrast to the improvements reported on the hydroxide covered pure magnesium. The electrochemical impedance increased with increase in the NaOH concentration in the solution treated condition of both Mg-RE alloys, whereas the overaged EV31A alloy showed a reverse trend. The passive layer of EV31A showed almost 100% higher charge carrier density than the film formed on the WE43C in the overaged condition. A better passivation behavior was observed in the solution treated condition than that in the overaged condition which could be attributed to the uniform distribution of the RE elements in the solution treated specimens. The WE43C alloy revealed better corrosion resistance in the alkaline solution than the EV31A alloy.

Effect of Mg doping in ZnO buffer layer on ZnO thin film devices for electronic applications

Science.gov (United States)

Giri, Pushpa; Chakrabarti, P.

2016-05-01

Zinc Oxide (ZnO) thin films have been grown on p-silicon (Si) substrate using magnesium doped ZnO (Mg: ZnO) buffer layer by radio-frequency (RF) sputtering method. In this paper, we have optimized the concentration of Mg (0-5 atomic percent (at. %)) ZnO buffer layer to examine its effect on ZnO thin film based devices for electronic and optoelectronic applications. The crystalline nature, morphology and topography of the surface of the thin film have been characterized. The optical as well as electrical properties of the active ZnO film can be tailored by varying the concentration of Mg in the buffer layer. The crystallite size in the active ZnO thin film was found to increase with the Mg concentration in the buffer layer in the range of 0-3 at. % and subsequently decrease with increasing Mg atom concentration in the ZnO. The same was verified by the surface morphology and topography studies carried out with scanning electron microscope (SEM) and atomic electron microscopy (AFM) respectively. The reflectance in the visible region was measured to be less than 80% and found to decrease with increase in Mg concentration from 0 to 3 at. % in the buffer region. The optical bandgap was initially found to increase from 3.02 eV to 3.74 eV by increasing the Mg content from 0 to 3 at. % but subsequently decreases and drops down to 3.43 eV for a concentration of 5 at. %. The study of an Au:Pd/ZnO Schottky diode reveals that for optimum doping of the buffer layer the device exhibits superior rectifying behavior. The barrier height, ideality factor, rectification ratio, reverse saturation current and series resistance of the Schottky diode were extracted from the measured current voltage (I-V) characteristics.

Decrease of VOC emissions from vehicular emissions in Hong Kong from 2003 to 2015: Results from a tunnel study

Science.gov (United States)

Cui, Long; Wang, Xiao Liang; Ho, Kin Fai; Gao, Yuan; Liu, Chang; Hang Ho, Steven Sai; Li, Hai Wei; Lee, Shun Cheng; Wang, Xin Ming; Jiang, Bo Qiong; Huang, Yu; Chow, Judith C.; Watson, John G.; Chen, Lung-Wen

2018-03-01

Vehicular emissions are one of major anthropogenic sources of ambient volatile organic compounds (VOCs) in Hong Kong. During the past twelve years, the government of the Hong Kong Special Administrative Region has undertaken a series of air pollution control measures to reduce vehicular emissions in Hong Kong. Vehicular emissions were characterized by repeated measurement in the same roadway tunnel in 2003 and 2015. The total net concentration of measured VOCs decreased by 44.7% from 2003 to 2015. The fleet-average VOC emission factor decreased from 107.1 ± 44.8 mg veh-1 km-1 in 2003 to 58.8 ± 50.7 mg veh-1 km-1 in 2015, and the total ozone (O3) formation potential of measured VOCs decreased from 474.1 mg O3 veh-1 km-1 to 190.8 mg O3 veh-1 km-1. The emission factor of ethene, which is one of the key tracers for diesel vehicular emissions, decreased by 67.3% from 2003 to 2015 as a result of the strict control measures on diesel vehicular emissions. Total road transport VOC emissions is estimated to be reduced by 40% as compared with 2010 by 2020, which will be an important contributor to achieve the goal of total VOC emission reduction in the Pearl River Delta region. The large decrease of VOC emissions from on-road vehicles demonstrates the effectiveness of past multi-vehicular emission control strategy in Hong Kong.

Dielectric and impedance study of praseodymium substituted Mg-based spinel ferrites

Energy Technology Data Exchange (ETDEWEB)

Farid, Hafiz Muhammad Tahir, E-mail: tahirfaridbzu@gmail.com [Department of Physics, Bahauddin Zakariya, University Multan, 60800 (Pakistan); Ahmad, Ishtiaq; Ali, Irshad [Department of Physics, Bahauddin Zakariya, University Multan, 60800 (Pakistan); Ramay, Shahid M. [College of Science, Physics and Astronomy Department, King Saud University, P.O. Box 2455, 11451 Riyadh (Saudi Arabia); Mahmood, Asif [Chemical Engineering Department, College of Engineering, King Saud University, Riyadh (Saudi Arabia); Murtaza, G. [Centre for Advanced Studies in Physics, GC University, Lahore 5400 (Pakistan)

2017-07-15

Highlights: • Magnesium based spinel ferrites were successfully synthesized by sol-gel method. • Dielectric constant shows the normal spinel ferrites behavior. • The dc conductivity are found to decrease with increasing temperature. • The samples with low conductivity have high values of activation energy. • The Impedance decreases with increasing frequency of applied field. - Abstract: Spinel ferrites with nominal composition MgPr{sub y}Fe{sub 2−y}O{sub 4} (y = 0.00, 0.025, 0.05, 0.075, 0.10) were prepared by sol-gel method. Temperature dependent DC electrical conductivity and drift mobility were found in good agreement with each other, reflecting semiconducting behavior. The dielectric properties of all the samples as a function of frequency (1 MHz–3 GHz) were measured at room temperature. The dielectric constant and complex dielectric constant of these samples decreased with the increase of praseodymium concentration. In the present spinel ferrite, Cole–Cole plots were used to separate the grain and grain boundary’s effects. The substitution of praseodymium ions in Mg-based spinel ferrites leads to a remarkable rise of grain boundary’s resistance as compared to the grain’s resistance. As both AC conductivity and Cole–Cole plots are the functions of concentration, they reveal the dominant contribution of grain boundaries in the conduction mechanism. AC activation energy was lower than dc activation energy. Temperature dependence normalized AC susceptibility of spinel ferrites reveals that MgFe{sub 2}O{sub 4} exhibits multi domain (MD) structure with high Curie temperature while on substitution of praseodymium, MD to SD transitions occurs. The low values of conductivity and low dielectric loss make these materials best candidate for high frequency application.

Structural, magnetic and electrical characterization of Cd-substituted Mg ferrites synthesized by double sintering technique

Energy Technology Data Exchange (ETDEWEB)

Zahir, R. [Department of Physics, Chittagong University of Engineering and Technology, Chittagong 4349 (Bangladesh); Chowdhury, F.-U.Z, E-mail: faruque@cuet.ac.bd [Department of Physics, Chittagong University of Engineering and Technology, Chittagong 4349 (Bangladesh); Uddin, M.M. [Department of Physics, Chittagong University of Engineering and Technology, Chittagong 4349 (Bangladesh); Hakim, M.A. [Materials Science Division, Atomic Energy Center, Dhaka 1000 (Bangladesh)

2016-07-15

Cd-substituted Mg ferrites with compositional formula Mg{sub 1−x}Cd{sub x}Fe{sub 2}O{sub 4} with 0.1≤x≤0.6 in the steps of 0.1 have been synthesized by double sintering ceramic technique. The X-ray diffraction analysis has revealed that the samples crystallize in a single phase cubic spinel structure. The lattice parameter has increased with increasing Cd content in conformity with Vegard's law. The study of scanning electron microscopy has revealed that Cd substitution has increased the particle size of the ferrites increases from ~2.2 to 9.2 µm. Some probable interpretations based on literature have been discussed. The increase in particle size with increasing of Cd content has consequently resulted in the initial permeability. The Curie temperature has decreased linearly with increasing Cd content which pointed out the weakening of A-B exchange interaction. The spectra of quality factor have showed a steady bandwidth of 0.1–8 MHz, this finding makes the ferrite system suitable for broadband pulse transformer. The variation of electrical resistivity (DC and AC) has been explained on the basis of electron hopping between Fe{sup 2+}and Fe{sup 3+}. - Highlights: • Synthesis of Cd-substituted Mg ferrites by double sintering ceramic technique. • Studies of Cd substitution on the structural and magnetic properties of Mg Ferrites. • The Curie temperature decreases linearly with increasing Cd concentration. • Due to the conduction of hopping of charge carriers DC resistivity decreases.

Sol-Gel Derived Hydroxyapatite Coating on Mg-3Zn Alloy for Orthopedic Application

Science.gov (United States)

Singh, Sanjay; Manoj Kumar, R.; Kuntal, Kishor Kumar; Gupta, Pallavi; Das, Snehashish; Jayaganthan, R.; Roy, Partha; Lahiri, Debrupa

2015-04-01

In recent years, magnesium and its alloys have gained a lot of interest as orthopedic implant constituents because their biodegradability and mechanical properties are closer to that of human bone. However, one major concern with Mg in orthopedics is its high corrosion rate that results in the reduction of mechanical integrity before healing the bone tissue. The current study evaluates the sol-gel-derived hydroxyapatite (HA) coating on a selected Mg alloy (Mg-3Zn) for decreasing the corrosion rate and increasing the bioactivity of the Mg surface. The mechanical integrity of the coating is established as a function of the surface roughness of the substrate and the sintering temperature of the coating. Coating on a substrate roughness of 15-20 nm and sintering at 400°C shows the mechanical properties in similar range of bone, thus making it suitable to avoid the stress-shielding effect. The hydroxyapatite coating on the Mg alloy surface also increases corrosion resistance very significantly by 40 times. Bone cells are also found proliferating better in the HA-coated surface. All these benefits together establish the candidature of sol-gel HA-coated Mg-3Zn alloy in orthopedic application.

Effect of annealing on properties of Mg doped Zn-ferrite nanoparticles

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K. Nadeem

2015-04-01

Full Text Available A comparison of structural and magnetic properties of as-prepared and annealed (900 °C Mg doped Zn ferrite nanoparticles (Zn1−xMgxFe2O4, with x=0, 0.1, 0.2, 0.3, 0.4 and 0.5 is presented. X-ray diffraction (XRD studies confirmed the cubic spinel structure for both the as-prepared and annealed nanoparticles. The average crystallite size and lattice parameter were increased by annealing. Scanning electron microscopy (SEM images also showed that the average particle size increased after annealing. Fourier transform infrared spectroscopy (FTIR also confirmed the spinel structure for both series of nanoparticles. For both annealed and as-prepared nanoparticles, the O–Mtet.–O vibrational band shifts towards higher wave numbers with increased Mg concentration due to cationic rearrangement on the lattice sites. Magnetization studies revealed an anomalous decreasing magnetization for the annealed nanoparticles which is also ascribed to cationic rearrangement on the lattice sites after annealing. The measurement of coercivity showed a decreasing trend by annealing due to the increased nanoparticle size and better crystallinity.

Electronic structure and optical properties of Al and Mg co-doped GaN

International Nuclear Information System (INIS)

Ji Yan-Jun; Du Yu-Jie; Wang Mei-Shan

2013-01-01

The electronic structure and optical properties of Al and Mg co-doped GaN are calculated from first principles using density function theory with the plane-wave ultrasoft pseudopotential method. The results show that the optimal form of p-type GaN is obtained with an appropriate Al:Mg co-doping ratio rather than with only Mg doping. Al doping weakens the interaction between Ga and N, resulting in the Ga 4s states moving to a high energy region and the system band gap widening. The optical properties of the co-doped system are calculated and compared with those of undoped GaN. The dielectric function of the co-doped system is anisotropic in the low energy region. The static refractive index and reflectivity increase, and absorption coefficient decreases. This provides the theoretical foundation for the design and application of Al—Mg co-doped GaN photoelectric materials

Preparation and characterization of porous Mg-Zn-Ca alloy by space holder technique

Science.gov (United States)

Annur, D.; Lestari, Franciska P.; Erryani, A.; Sijabat, Fernando A.; G. P. Astawa, I. N.; Kartika, I.

2018-04-01

Magnesium had been recently researched as a future biodegradable implant material. In the recent study, porous Mg-Zn-Ca alloys were developed using space holder technique in powder metallurgy process. Carbamide (10-20%wt) was added into Mg-6Zn-1Ca (in wt%) alloy system as a space holder to create porous structure material. Sintering process was done in a tube furnace under Argon atmosphere in 610 °C for 5 hours. Porous structure of the resulted alloy was examined using Scanning Electron Microscope (SEM), while the phase formation was characterized by X-ray diffraction analysis (XRD). Further, mechanical properties of porous Mg-Zn-Ca alloy was examined through compression testing. Microstructure characterization showed higher content of Carbamide in the alloy would give different type of pores. However, compression test showed that mechanical properties of Mg-Zn-Ca alloy would decrease significantly when higher content of carbamide was added.

Influence of the Mg-content on ESR-signals in synthetic calcium carbonate

International Nuclear Information System (INIS)

Barabas, M.; Bach, A.; Mudelsee, M.; Mangini, A.

1989-01-01

Carbonate crystals doped with various concentrations of Mg 2+ -ions have been grown by a gel-diffusion method. An increase of the Mg/Ca-ratio to more than about 1 caused a phase change in the crystal lattice from calcite to aragonite. The properties of the ESR-signals of the synthetic carbonates were studied and compared with natural marine carbonates. The following results were derived: (a) In the presence of Mg 2+ -ions the synthetic carbonates display the same ESR-signals as natural calcites of marine origin with similar properties (thermal stability, radiation sensitivity). (b) The saturation value of the signal at g=2.0006 in synthetic calcites was found to be strongly related with the Mg-content in the crystals. (c) The signal at g=2.0036 (axial symmetry) which is present in calcite was not influenced by the Mg-concentration. Its saturation value decreases when the crystal phase changed from calcite to aragonite and in complement the signal at g=2.0031 appeared. (d) The signals at g=2.0057 and g=2.0031 are most probably not of organic origin. (author)

Performance of Mg-14Li-1Al-0.1Ce as anode for Mg-air battery

Energy Technology Data Exchange (ETDEWEB)

Ma, Yibin; Li, Deyu [School of Chemical Engineering and Technology, Harbin Institute of Technology, West Street No. 92, Harbin 150001 (China); Li, Ning [School of Chemical Engineering and Technology, Harbin Institute of Technology, West Street No. 92, Harbin 150001 (China); Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, Harbin Engineering University, Harbin 150001 (China); Zhang, Milin; Huang, Xiaomei [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, Harbin Engineering University, Harbin 150001 (China)

2011-02-15

In this research, a new Mg-air battery based on Mg-14Li-1Al-0.1Ce was prepared and the battery performance was investigated by constant current discharge test. The corrosion behavior of Mg, AZ31 and Mg-Li-Al-Ce were studied by self-corrosion rate measurement and potentiodynamic polarization measurement. The characteristics of Mg-Li-Al-Ce after discharge were investigated by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that Mg-Li-Al-Ce is more active than Mg and AZ31. The self-corrosion rate is found to be in the order: Mg-Li-Al-Ce < Mg < AZ31. It has been observed that the Mg-air battery based on Mg-Li-Al-Ce offers higher operating voltage, anodic efficiency and capacity than those with Mg and AZ31. SEM and EIS results show that the discharge product of Mg-Li-Al-Ce is loosely adhered to the alloy surface, and thus Mg-Li-Al-Ce could keep high discharge activity during discharge. (author)

Mifepristone 5 mg versus 10 mg for emergency contraception: double-blind randomized clinical trial

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Carbonell JL

2015-01-01

Full Text Available Josep Lluis Carbonell,1 Ramon Garcia,2 Adriana Gonzalez,2 Andres Breto,2 Carlos Sanchez2 1Mediterranea Medica Clinic, Valencia, Spain; 2Eusebio Hernandez Gynecology and Obstetrics Teaching Hospital, Havana, Cuba Purpose: To estimate the efficacy and safety of 5 mg and 10 mg mifepristone for emergency contraception up to 144 hours after unprotected coitus. Methods: This double-blind randomized clinical trial was carried out at Eusebio Hernandez Hospital (Havana, Cuba. A total of 2,418 women who requested emergency contraception after unprotected coitus received either 5 mg or 10 mg mifepristone. The variables for assessing efficacy were the pregnancies that occurred and the fraction of pregnancies that were prevented. Other variables assessed were the side effects of mifepristone, vaginal bleeding, and changes in the date of the following menstruation. Results: There were 15/1,206 (1.2% and 9/1,212 (0.7% pregnancies in the 5 mg and 10 mg group, respectively (P=0.107. There were 88% and 93% prevented pregnancies in the 5 mg and 10 mg group, respectively. The side effect profiles were similar in both groups. Delayed menstruation ≥7 days was experienced by 4.9% and 11.0% of subjects in the 5 mg and 10 mg group, respectively (P=0.001. There was a significant high failure rate for women weighing >75 kg in the 5 mg group. Conclusion: It would be advisable to use the 10 mg dose of mifepristone for emergency contraception as there was a trend suggesting that the failure rate of the larger dose was lower. Keywords: mifepristone, emergency contraception

Chondrogenic differentiation of ATDC5-cells under the influence of Mg and Mg alloy degradation.

Science.gov (United States)

Martinez Sanchez, Adela H; Feyerabend, Frank; Laipple, Daniel; Willumeit-Römer, Regine; Weinberg, Annelie; Luthringer, Bérengère J C

2017-03-01

Biodegradable magnesium (Mg)-based materials are a potential alternative to permanent implants for application in children. Nevertheless effects of those materials on growth plate cartilage and chondrogenesis have not been previously evaluated. In vitro differentiation of ATDC5 cells was evaluated under the influence of pure Mg (PMg), Mg with 10wt% of gadolinium (Mg-10Gd) and Mg with 2wt% of silver (Mg-2Ag) degradation products (extracts) and direct cell culture on the materials. Gene expression showed an inhibitory effect on ATDC5 mineralization with the three extracts and a chondrogenic potential of Mg-10Gd. Cells cultured in Mg-10Gd and Mg-2Ag extracts showed the same proliferation and morphology than cells cultured in growth conditions. Mg-10Gd induced an increase in production of ECM and a bigger cell size, similar to the effects found with differentiation conditions. An increased metabolic activity was observed in cells cultured under the influence of Mg-10Gd extracts, indicated by an acidic pH during most of the culture period. After 7days of culture on the materials, ATDC5 growth, distribution and ECM synthesis were higher on Mg-10Gd samples, followed by Mg-2Ag and PMg, which was influenced by the homogeneity and composition of the degradation layer. This study confirmed the tolerance of ATDC5 cells to Mg-based materials and a chondrogenic effect of Mg-10Gd. Further studies in vitro and in vivo are necessary to evaluate cell reactions to those materials, as well as the effects on bone growth and the biocompatibility of the alloying system in the body. Copyright © 2016 Elsevier B.V. All rights reserved.

A computational study on the electronic and field emission properties of Mg and Si doped AlN nanocones

Science.gov (United States)

Saedi, Leila; Soleymanabadi, Hamed; Panahyab, Ataollah

2018-05-01

Following an experimental work, we explored the effect of replacing an Al atom of an AlN nanocone by Si or Mg atom on its electronic and field emission properties using density functional theory calculations. We found that both Si-doping and Mg-doping increase the electrical conductivity of AlN nanocone, but their influences on the filed emission properties are significantly different. The Si-doping increases the electron concentration of AlN nanocone and results in a large electron mobility and a low work function, whereas Mg-doping leads to a high hole concentration below the conduction level and increases the work function in agreement with the experimental results. It is predicted that Si-doped AlN nanocones show excellent filed emission performance with higher emitted electron current density compared to the pristine AlN nanocone. But the Mg-doping meaningfully decreases the emitted electron current density from the surface of AlN nanocone. The Mg-doping can increase the work function about 41.9% and the Si-doping can decrease it about 6.3%. The Mg-doping and Si-doping convert the AlN nanocone to a p-type and n-type semiconductors, respectively. Our results explain in a molecular level what observed in the experiment.

Maintenance on naltrexone+amphetamine decreases cocaine-vs.-food choice in male rhesus monkeys.

Science.gov (United States)

Moerke, Megan J; Banks, Matthew L; Cheng, Kejun; Rice, Kenner C; Negus, S Stevens

2017-12-01

Cocaine use disorder remains a significant public health issue for which there are no FDA-approved pharmacotherapies. Amphetamine maintenance reduces cocaine use in preclinical and clinical studies, but the mechanism of this effect is unknown. Previous studies indicate a role for endogenous opioid release and subsequent opioid receptor activation in some amphetamine effects; therefore, the current study examined the role of mu-opioid receptor activation in d-amphetamine treatment effects in an assay of cocaine-vs-food choice. Adult male rhesus monkeys with double-lumen intravenous catheters responded for concurrently available food pellets and cocaine injections (0-0.1mg/kg/injection) during daily sessions. Cocaine choice and overall reinforcement rates were evaluated during 7-day treatments with saline or test drugs. During saline treatment, cocaine maintained a dose-dependent increase in cocaine-vs.-food choice. The mu-opioid receptor agonist morphine (0.032-0.32mg/kg/h) dose-dependently increased cocaine choice and decreased rates of reinforcement. A dose of the mu-selective opioid receptor antagonist naltrexone (0.0032mg/kg/h) that completely blocked morphine effects had no effect on cocaine choice when it was administered alone, but it enhanced the effectiveness of a threshold dose of 0.032mg/kg/h amphetamine to decrease cocaine choice without also enhancing nonselective behavioral disruption by this dose of amphetamine. Conversely, the kappa-selective opioid antagonist norbinalorphimine did not enhance amphetamine effects on cocaine choice. These results suggest that amphetamine maintenance produces mu opioid-receptor mediated effects that oppose its anti-cocaine effects. Co-administration of naltrexone may selectively enhance amphetamine potency to decrease cocaine choice without increasing amphetamine potency to produce general behavioral disruption. Copyright © 2017 Elsevier B.V. All rights reserved.

Electronic structure of ferromagnet-insulator interfaces: Fe/MgO and Co/MgO

Energy Technology Data Exchange (ETDEWEB)

Mueller, M.

2007-07-11

In this thesis the electronic structure of Fe/MgO{sub x} and Co/MgO{sub x} ferromagnet-insulator interfaces, representing material systems which are widely used in magnetic tunnel junctions, is studied by means of spin- and angle-resolved photoemission spectroscopy. The photoemission studies focus particularly on the response of the ferromagnetic electronic system in contact with MgO of varying stoichiometries, as this reflects the mechanisms of metal-oxide bonding at real ferromagnet-insulator interfaces. The correlation between chemical bonding and electronic structure formation is analyzed by combining information from core- and valence-band photoemission spectroscopy. The spectral features are compared to band structure calculations, which are performed using the SPR-KKR method. The Fe/MgO and Co/MgO systems are prepared by molecular beam epitaxy under ultrahigh vacuum conditions on well-defined (4 x 6) GaAs(001) substrates. A structural analysis by means of low-energy electron diffraction (LEED) reveals their body-centered cubic crystalline structure, whereas the chemical characterization by Auger electron spectroscopy is used to quantify the chemical environment at the sample surfaces. The magnetic analysis, using the magneto-optical Kerr effect, reveals the uniaxial anisotropy of the ferromagnetic layers. A crucial parameter is given by the MgO degree of oxidation, which is addressed by means of core-level spectroscopy and quantified by suitable fitting procedures of the Mg 2p core level. The results of the photoemission experiments show, that the electronic structure of the Fe/MgO and Co/MgO ferromagnet/insulator interfaces and, consequently, the interfacial spin polarization are sensitively controlled by the interface chemistry. In particular, three distinct scenarios are identified: the nearly stoichiometric, the oxygen-deficient and the over-oxidized ferromagnet/MgO interface. Each case is defined by innate characteristics of the electronic structure at

Oxytocin decreases cocaine taking, cocaine seeking, and locomotor activity in female rats.

Science.gov (United States)

Leong, Kah-Chung; Zhou, Luyi; Ghee, Shannon M; See, Ronald E; Reichel, Carmela M

2016-02-01

Oxytocin has been shown to decrease cocaine taking and seeking in male rats, suggesting potential treatment efficacy for drug addiction. In the present study, we extended these findings to the assessment of cocaine seeking and taking in female rats. Further, we made direct comparisons of oxytocin's impact on cocaine induced locomotor activity in both males and females. In females, systemic oxytocin (0.3, 1.0, 3.0 mg/kg) attenuated lever pressing for cocaine during self-administration and oxytocin (1.0 mg/kg) attenuated cue-induced cocaine seeking following extinction. Cocaine increased baseline locomotor activity to a greater degree in females relative to males. Oxytocin (0.1, 0.3, 1.0, and 3.0 mg/kg) reduced cocaine-induced locomotor activity in females, but not significantly in males. These data illustrate sex similarities in oxytocin's attenuation of cocaine seeking, but sex differences in cocaine-induced locomotor effects. While reductions in cocaine seeking cannot be attributed to a reduction in locomotor activity in males, attenuation of locomotor function cannot be entirely ruled out as an explanation for a decrease in cocaine seeking in females suggesting that oxytocin's effect on cocaine seeking may be mediated by different mechanisms in male and females. PsycINFO Database Record (c) 2016 APA, all rights reserved.

FRACTIONAL RECRYSTALLIZATION KINETICS IN DIRECTLY COLD ROLLED Al-Mg, Al-Mg-Sc AND Al-Mg-Sc-Zr ALLOY

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M. S. Kaiser

2014-12-01

Full Text Available The evaluation of texture as a function of recrystallization has been characterized for directly cold rolled Al-6Mg, Al-6Mg-0.4Sc and Al-6Mg-0.4Sc-0.2Zr alloys. Samples were annealed isothermally at 400 °C for 1 to 240 minutes to allow recrystallization. Recrystallization kinetics of the alloys is analyzed from the micro-hardness variation. Isothermally annealed samples of aluminum alloys were also studied using JMAK type analysis to see if there exists any correlation between the methods. Recrystallization fraction behavior between two methods the scandium added alloys show the higher variation due to precipitation hardening and higher recrystallization behavior. The scandium and zirconium as a combined shows the more variation due to formation of Al3(Sc, Zr precipitate. From the microstructure it is also observed that the base Al-Mg alloy attained almost fully re-crystallized state after annealing at 400 °C for 60 minutes

Reactive wetting of amorphous silica by molten Al–Mg alloys and their interfacial structures

Energy Technology Data Exchange (ETDEWEB)

Shi, Laixin [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China); School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Shen, Ping, E-mail: shenping@jlu.edu.cn [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China); Zhang, Dan [Editorial Office, Journal of Bionic Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China); Jiang, Qichuan [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China)

2016-07-30

Highlights: • The wettability improves with increasing Mg concentration and temperature. • Reaction product zone consists of layered structures relating with Mg concentration. • Formation of MgAl{sub 2}O{sub 4} and MgO at the interface does not promote the wettability. • Formation of Mg{sub 2}Si plays a dominant role in promoting the wettability. • Anomalous recession of the triple line was mainly due to diminishing Mg in the alloy. - Abstract: The reactive wetting of amorphous silica substrates by molten Al–Mg alloys over a wide composition range was studied using a dispensed sessile drop method in a flowing Ar atmosphere. The effects of the nominal Mg concentration and temperature on the wetting and interfacial microstructures were discussed. The initial contact angle for pure Al on the SiO{sub 2} surface was 115° while that for pure Mg was 35° at 1073 K. For the Al–Mg alloy drop, it decreased with increasing nominal Mg concentration. The reaction zone was characterized by layered structures, whose formation was primarily controlled by the variation in the alloy concentration due to the evaporation of Mg and the interfacial reaction from the viewpoint of thermodynamics as well as by the penetration or diffusion of Mg, Al and Si from the viewpoint of kinetics. In addition, the effects of the reaction and the evaporation of Mg on the movement of the triple line were examined. The spreading of the Al–Mg alloy on the SiO{sub 2} surface was mainly attributed to the formation of Mg{sub 2}Si at the interface and the recession of the triple line to the diminishing Mg concentration in the alloy.

Catalytic properties of pure and K+-doped Cu O/Mg O system towards 2-propanol conversion

International Nuclear Information System (INIS)

El-Molla, S. A.; Amin, N. H.; Hammed, M. N.; Sultan, S. N.; El-Shobaky, G. A.

2013-01-01

Cu O/Mg O system having different compositions was prepared by impregnation method followed by calcination at 400-900 C. The effect of Cu O content, calcination temperature and doping with small amounts of K + species (1-3 mol %) on physicochemical, surface and catalytic properties of the system were investigated using X-ray diffraction, adsorption of N 2 at - 196 C, and conversion of isopropyl alcohol at 150-400 C using a flow technique. The results revealed that the solids having the formulae 0.2 and 0.3 Cu O/Mg O calcined at 400 C consisted of nano sized Mg O and Cu O as major phases together with Cu 2 O as minor phase. The Bet-surface areas of different absorbents are decreased by increasing Cu O content, calcination temperature and K + -doping. Mg O-support material showed very small catalytic activity in 2-propanol conversion. The investigated system behaved as selective catalyst for dehydrogenation of 2-propanol with selectivity >80%. The catalytic activity increased by increasing Cu O content and decreased by increasing the calcination temperature within 400-900 C. K + -doping increased the catalytic activity and catalytic durability. (Author)

Investigation of the 26Mg(d, p)27Mg reaction

NARCIS (Netherlands)

Meurders, F.; Steld, A. van der

1974-01-01

The angular distributions of 31 protons groups from the 26Mg(d, p)27Mg reaction have been measured at Ed = 12.0 MeV with a split-pole magnetic spectrograph. Excitation energies have been determined for 29 bound states. Three new levels have been found. A DWBA analysis yields ln values for 19 levels;

Research of acceptor impurity thermal activation in GaN: Mg epitaxial layers

Directory of Open Access Journals (Sweden)

Aleksandr V. Mazalov

2016-06-01

The effect of thermal annealing of GaN:Mg layers on acceptor impurity activation has been investigated. Hole concentration increased and mobility decreased with an increase in thermal annealing temperature. The sample annealed at 1000 °C demonstrated the lowest value of resistivity. Rapid thermal annealing (annealing with high heating speed considerably improved the efficiency of Mg activation in the GaN layers. The optimum time of annealing at 1000 °C has been determined. The hole concentration increased by up to 4 times compared to specimens after conventional annealing.

Preparation of MgB2 superconducting microbridges by focused ion beam direct milling

Science.gov (United States)

Zhang, Xuena; Li, Yanli; Xu, Zhuang; Kong, Xiangdong; Han, Li

2017-01-01

MgB2 superconducting microbridges were prepared by focused ion beam (FIB) direct milling on MgB2 films. The surface topography of the microbridges were observed using SEM and AFM and the superconductivity was measured in this paper. Lots of cracks and holes were found near the milled area. And the superconducting transition temperature was decreased a lot and the bridges prepared were not superconducting due to ion damage after milled with large dose. Through these works, we explored the effect regular of FIB milling and experimental parameters on the performance of microbridges.

Post-fusion treatment with MG132 increases transcription factor expression in somatic cell nuclear transfer embryos in pigs.

Science.gov (United States)

You, Jinyoung; Lee, Joohyeong; Kim, Jinyoung; Park, Junhong; Lee, Eunsong

2010-02-01

The objective of this study was to examine the effect of post-fusion treatment of somatic cell nuclear transfer (SCNT) oocytes with the proteasomal inhibitor MG132 on maturation promoting factor (MPF) activity, nuclear remodeling, embryonic development, and gene expression of cloned pig embryos. Immediately after electrofusion, SCNT oocytes were treated with MG132 and/or caffeine for 2 hr, vanadate for 0.5 hr, or vanadate for 0.5 hr followed by MG132 for 1.5 hr. Of the MG132 concentrations tested (0-5 microM), the 1 microM concentration showed a higher rate of blastocyst formation (25.9%) than 0 (14.2%), 0.5 (16.9%), and 5 microM (16.9%). Post-fusion treatment with MG132, caffeine, and both MG132 and caffeine improved blastocyst formation (22.1%, 21.4%, and 24.4%, respectively), whereas vanadate treatment inhibited blastocyst formation (6.5%) compared to the control (11.1%). When examined 2 hr after fusion and 1 hr after activation, MPF activity remained at a higher (P fusion with caffeine and/or MG132, but it was decreased by vanadate. The rate of oocytes showing premature chromosome condensation was not altered by MG132 but was decreased by vanadate treatment. In addition, formation of single pronuclei was increased by MG132 compared to control and vanadate treatment. MG132-treated embryos showed increased expression of POU5F1, DPPA2, DPPA3, DPPA5, and NDP52l1 genes compared to control embryos. Our results demonstrate that post-fusion treatment of SCNT oocytes with MG132 prevents MPF degradation and increases expression of transcription factors in SCNT embryos, which are necessary for normal development of SCNT embryos. (c) 2009 Wiley-Liss, Inc.

Preliminary study of the characteristics of a high Mg containing Al-Mg-Si alloy

International Nuclear Information System (INIS)

Yan, F; McKay, B J; Fan, Z; Chen, M F

2012-01-01

An Al-20Mg-4Si high Mg containing alloy has been produced and its characteristics investigated. The as-cast alloy revealed primary Mg 2 Si particles evenly distributed throughout an α-Al matrix with a β-Al 3 Mg 2 fully divorced eutectic phase observed in interdendritic regions. The Mg 2 Si particles displayed octahedral, truncated octahedral, and hopper morphologies. Additions of Sb, Ti and Zr had a refining influence reducing the size of the Mg 2 Si from 52 ± 4 μm to 25 ± 0.1 μm, 35 ± 1 μm and 34 ± 1 μm respectively. HPDC tensile test samples could be produced with a 0.6 wt.% Mn addition which prevented die soldering. Solution heating for 1 hr was found to dissolve the majority of the Al 3 Mg 2 eutectic phase with no evidence of any effect on the primary Mg 2 Si. Preliminary results indicate that the heat treatment has a beneficial effect on the elongation and the UTS.

A Computational Investigation of Precipitates in Mg-RE Alloys With Applications To Mg-X Systems

Science.gov (United States)

Issa, Ahmed

Increasing fuel efficiency in transportation vehicles is a major policy goal for both government and auto and aerospace manufacturers. Lightweight structural materials, such as magnesium alloys, hold great promise in enabling such fuel efficiency gains. Understanding the controlling factors in Mg alloy strengthening is crucial for the rational design of structurally strong and inexpensive Mg alloys. In this work, we seek to understand the energetic underpinnings giving rise to a class of remarkably strong Mg alloys: Mg-RE systems. We use first-principles methods to efficiently explore seventeen Mg-RE systems, drawing out broad patterns and distilling our knowledge into simple design rules for Mg alloys. We begin by investigating the controlling factors for the Mg-strengthening prismatic plate precipitates in Mg-RE systems, discovering the critical role of strain in such systems. We then proceed to investigate the surprising role of interfacial energies in determining the course of the Mg-RE precipitation reactions. Using strain and interfacial energies, we construct a phase-field model which accurately depicts the precipitate morphology as a function of time and size in a Mg-Nd system. Finally, we combine our gained insights to implement a computational alloy design scheme on a large portion of the periodic table where we seek Mg-strengthening solutes. Our work advances the understanding of strengthening in Mg alloys and lays the groundwork for full scale computational alloy design.

The response of soil and stream chemistry to decreases in acid deposition in the Catskill Mountains, New York, USA.

Science.gov (United States)

McHale, Michael R; Burns, Douglas A; Siemion, Jason; Antidormi, Michael R

2017-10-01

The Catskill Mountains have been adversely impacted by decades of acid deposition, however, since the early 1990s, levels have decreased sharply as a result of decreases in emissions of sulfur dioxide and nitrogen oxides. This study examines trends in acid deposition, stream-water chemistry, and soil chemistry in the southeastern Catskill Mountains. We measured significant reductions in acid deposition and improvement in stream-water quality in 5 streams included in this study from 1992 to 2014. The largest, most significant trends were for sulfate (SO 4 2- ) concentrations (mean trend of -2.5 μeq L -1 yr -1 ); hydrogen ion (H + ) and inorganic monomeric aluminum (Al im ) also decreased significantly (mean trends of -0.3 μeq L -1 yr -1 for H + and -0.1 μeq L -1 yr -1 for Al im for the 3 most acidic sites). Acid neutralizing capacity (ANC) increased by a mean of 0.65 μeq L -1 yr -1 for all 5 sites, which was 4 fold less than the decrease in SO 4 2- concentrations. These upward trends in ANC were limited by coincident decreases in base cations (-1.3 μeq L -1 yr -1 for calcium + magnesium). No significant trends were detected in stream-water nitrate (NO 3 - ) concentrations despite significant decreasing trends in NO 3 - wet deposition. We measured no recovery in soil chemistry which we attributed to an initially low soil buffering capacity that has been further depleted by decades of acid deposition. Tightly coupled decreasing trends in stream-water silicon (Si) (-0.2 μeq L -1 yr -1 ) and base cations suggest a decrease in the soil mineral weathering rate. We hypothesize that a decrease in the ionic strength of soil water and shallow groundwater may be the principal driver of this apparent decrease in the weathering rate. A decreasing weathering rate would help to explain the slow recovery of stream pH and ANC as well as that of soil base cations. Published by Elsevier Ltd.

The role of MgO content in ex situ MgB₂ wires

DEFF Research Database (Denmark)

Kovac, P.; Hugek, I.; Meligek, T.

2004-01-01

An experimental study of the effect of MgO content in the MgB2 powder used for ex situ made composite wires was carried out. Two single-core MgB2/Fe/Cu wires were made using commercial MgB2 powders from Alfa Aesar containing different fraction of MgO. Critical temperature and critical currents of...

Properties of mechanically alloyed Mg-Ni-Ti ternary hydrogen storage alloys for Ni-MH batteries

Science.gov (United States)

Ruggeri, Stéphane; Roué, Lionel; Huot, Jacques; Schulz, Robert; Aymard, Luc; Tarascon, Jean-Marie

MgNiTi x, Mg 1- xTi xNi and MgNi 1- xTi x (with x varying from 0 to 0.5) alloys have been prepared by high energy ball milling and tested as hydrogen storage electrodes. The initial discharge capacities of the Mg-Ni-Ti ternary alloys are inferior to the MgNi electrode capacity. However, an exception is observed with MgNi 0.95Ti 0.05, which has an initial discharge capacity of 575 mAh/g compared to 522 mAh/g for the MgNi electrode. The Mg-Ni-Ti ternary alloys show improved cycle life compared to Mg-Ni binary alloys with the same Mg/Ni atomic ratio. The best cycle life is observed with Mg 0.5Ti 0.5Ni electrode which retains 75% of initial capacity after 10 cycles in comparison to 39% for MgNi electrodes, in addition to improved high-rate dischargeability (HRD). According to the XPS analysis, the cycle life improvement of the Mg 0.5Ti 0.5Ni electrode can be related to the formation of TiO 2 which limits Mg(OH) 2 formation. The anodic polarization curve of Mg 0.5Ti 0.5Ni electrode shows that the current related to the active/passive transition is much less important and that the passive region is more extended than for the MgNi electrode but the corrosion of the electrode is still significant. This suggests that the cycle life improvement would be also associated with a decrease of the particle pulverization upon cycling.

Effect of naftopidil on brain noradrenaline-induced decrease in arginine-vasopressin secretion in rats

Directory of Open Access Journals (Sweden)

Masaki Yamamoto

2016-09-01

Full Text Available Naftopidil, an α1-adrenoceptor antagonist, has been shown to inhibit nocturnal polyuria in patients with lower urinary tract symptom. However, it remains unclear how naftopidil decreases nocturnal urine production. Here, we investigated the effects of naftopidil on arginine-vasopressin (AVP plasma level and urine production and osmolality in rats centrally administered with noradrenaline (NA. NA (3 or 30 μg/kg was administered into the left ventricle (i.c.v. of male Wistar rats 3 h after naftopidil pretreatment (10 or 30 mg/kg, i.p.. Blood samples were collected from the inferior vena cava 1 h after NA administration or 4 h after peritoneal administration of naftopidil; plasma levels of AVP were assessed by ELISA. Voiding behaviors of naftopidil (30 mg/kg, i.p.-administered male Wistar rats were observed during separate light- and dark cycles. Administration of NA decreased plasma AVP levels and elevated urine volume, which were suppressed by systemic pretreatment with naftopidil (30 mg/kg, i.p.. Urine osmolality decreased 1 h after NA administration. However, naftopidil by itself had no effect on plasma AVP levels or urodynamic parameters during light- and dark cycles. Our findings suggest that systemic administration of naftopidil could prevent central noradrenergic nervous system-mediated decline in AVP secretion and increase in urine production in rats.

Raman spectra of MgSiO3 . 10% Al2O3-perovskite at various pressures and temperatures

International Nuclear Information System (INIS)

Liu Lingun; Irifune, T.

1995-01-01

Variations of Raman spectra of MgSiO 3 . 10% Al 2 O 3 -perovskite were investigated up to about 270 kbar at room temperature and in the range 108-425 K at atmospheric pressure. Like MgSiO 3 -perovskite, the Raman frequencies of MgSiO 3 . 10% Al 2 O 3 -perovskite increase nonlinearly with increasing pressure and decrease linearly with increasing temperature within the experimental uncertainties and the range investigated. A comparison of these data with those of MgSiO 3 -perovskite suggests that MgSiO 3 . 10% Al 2 O 3 -perovskite is slightly more compressible than MgSiO 3 -perovskite, and that the volume thermal expansion for MgSiO 3 . 10% Al 2 O 3 -perovskite is also slightly greater than that for MgSiO 3 -perovskite. (orig.)

Structural and magnetic properties of Mg-Zn ferrites (Mg{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}) prepared by sol-gel method

Energy Technology Data Exchange (ETDEWEB)

Reyes-Rodríguez, Pamela Yajaira, E-mail: pamela2244_4@hotmail.com [Cinvestav-Unidad Saltillo, Av. Industrial Metalúrgica #1062, Parque Industrial Saltillo-Ramos Arizpe, CP 25900, México (Mexico); Cortés-Hernández, Dora Alicia; Escobedo-Bocardo, José Concepción; Almanza-Robles, José Manuel; Sánchez-Fuentes, Héctor Javier; Jasso-Terán, Argentina; De León-Prado, Laura Elena [Cinvestav-Unidad Saltillo, Av. Industrial Metalúrgica #1062, Parque Industrial Saltillo-Ramos Arizpe, CP 25900, México (Mexico); Méndez-Nonell, Juan [Centro de Investigación en Materiales Avanzados, Ave. Miguel Cervantes #120, Complejo Industrial Chihuahua, CP 31109 Chihuahua, México (Mexico); Hurtado-López, Gilberto Francisco [Centro de Investigación en Química Aplicada, Blvd. Enrique Reyna Hermosillo #140, CP 25294 Saltillo, Coahuila, México (Mexico)

2017-04-01

In this study, the Mg{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} nanoparticles (x=0–0.9) were prepared by sol-gel method. These ferrites exhibit an inverse spinel structure and the lattice parameter increases as the substitution of Zn{sup 2+} ions is increased. At lower Zn content (0.1≤x≤0.5), saturation magnetization (Ms) increases, while it decreases at higher Zn content (x≥6). The remnant magnetization (0.17–2.0 emu/g) and coercive field (6.0–60 Oe) indicate a ferrimagnetic behavior. The average core diameter of selected ferrites is around 15 nm and the nanoparticles morphology is quasi spherical. The heating ability of some Mg{sub 0.9}Zn{sub 0.1}Fe{sub 2}O{sub 4} and Mg{sub 0.7}Zn{sub 0.3}Fe{sub 2}O{sub 4} aqueous suspensions indicates that the magnetic nanoparticles can increase the medium temperature up to 42 °C in a time less than 10 min - Highlights: • Magnetic nanoparticles of Mg{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} were synthesized by sol-gel method. • Nanoparticles showing a single spinel crystalline structure were obtained. • Aqueous suspensions of Mg{sub 0.7}Zn{sub 0.3}Fe{sub 2}O{sub 4} and Mg{sub 0.9}Zn{sub 0.1}Fe{sub 2}O{sub 4} show heating ability.

Investigation of the 24Mg(d, p)25Mg reaction

NARCIS (Netherlands)

Meurders, F.; Korte, G. de

1975-01-01

Abstract Proton angular distributions from the 24Mg(d, p)25Mg reaction at Ed = 12.0 MeV have been measured with a split-pole magnetic spectrograph for Ex < 6 MeV at an average resolution (FWHM) of 7 keV. New ln values have been determined for three levels. A DWBA analysis yielded spectroscopic

Atomic structure of pyramidal defects in GaN:Mg: Influence of annealing

Energy Technology Data Exchange (ETDEWEB)

Liliental-Weber, Z.; Tomaszewicz, T.; Zakharov, D.; O' Keefe, M. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Hautakangas, S.; Saarinen, K. [Materials Science and Engineering, University of California, Berkeley, Berkeley, CA 94720 (United States); Freitas, J.A.; Henry, R.L. [ESTD-Electronic Materials Branch, Naval Research Laboratory, Washington, D.C. 20375 (United States)

2006-05-15

The atomic structure of the characteristic defects (Mg-rich hexagonal pyramids) in p-doped bulk and MOCVD GaN:Mg thin films grown with Ga polarity was determined at atomic resolution by direct reconstruction of the scattered electron wave in a transmission electron microscope. Small cavities were present inside the defects, confirmed also with positron annihilation. The inside walls of the cavities were covered by GaN of reverse polarity compared to the matrix. Annealing of the MOCVD layers lead to slight increase of the defect size and an increase of the room temperature photoluminescence intensity. Positron annihilation confirms presence of vacancy clusters of different sizes triggered by the Mg doping in as-grown samples and decrease of their concentration upon annealing at 900 and 1000 C. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Formation and Corrosion Resistance of Mg-Al Hydrotalcite Film on Mg-Gd-Zn Alloy

Science.gov (United States)

Ba, Z. X.; Dong, Q. S.; Kong, S. X.; Zhang, X. B.; Xue, Y. J.; Chen, Y. J.

2017-06-01

An environment-friendly technique for depositing a Mg-Al hydrotalcite (HT) (Mg6Al2(OH)16-CO3ṡ4H2O) conversion film was developed to protect the Mg-Gd-Zn alloy from corrosion. The morphology and chemical compositions of the film were analyzed by scanning electronic microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Raman spectroscopy (RS), respectively. The electrochemical test and hydrogen evolution test were employed to evaluate the biocorrosion behavior of Mg-Gd-Zn alloy coated with the Mg-Al HT film in the simulated body fluid (SBF). It was found that the formation of Mg-Al HT film was a transition from amorphous precursor to a crystalline HT structure. The HT film can effectively improve the corrosion resistance of magnesium alloy. It indicates that the process provides a promising approach to modify Mg-Gd-Zn alloy.

Photoluminescence of Mg{sub 2}Si films fabricated by magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Liao, Yang-Fang [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); School of Physics and Electronic Science of Guizhou Normal University, Guiyang 550001 (China); Xie, Quan, E-mail: qxie@gzu.edu.cn [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); Xiao, Qing-Quan [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); Engineering Center for Avionics Electrical and Information Network of Guizhou Provincial Colleges and Universities, Anshun 561000 (China); Chen, Qian; Fan, Meng-Hui [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); Xie, Jing [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); School of Physics and Electronic Science of Guizhou Normal University, Guiyang 550001 (China); Huang, Jin; Zhang, Jin-Min; Ma, Rui; Wang, Shan-Lan; Wu, Hong-Xian; Fang, Di [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China)

2017-05-01

Highlights: • High quality Mg{sub 2}Si films were grown on Si (111) and glass substrates with magnetron sputtering, respectively. • The first observation of Photoluminescence (PL) of Mg{sub 2}Si films was reported. • The Mg{sub 2}Si PL emission wavelengths are almost independence on temperature in the range of 77–300 K. • The strongest PL emissions may be attributed to interstitial Mg donor level to valence band transitions. • The activation energy of Mg{sub 2}Si is determined from the quenching of major luminescence peaks. - Abstract: To understand the photoluminescence mechanisms and optimize the design of Mg{sub 2}Si-based light-emitting devices, Mg{sub 2}Si films were fabricated on silicon (111) and glass substrates by magnetron sputtering technique, and the influences of different substrates on the photoelectric properties of Mg{sub 2}Si films were investigated systematically. The crystal structure, cross-sectional morphology, composition ratios and temperature-dependent photoluminescence (PL) of the Mg{sub 2}Si films were examined using X-ray diffraction (XRD), Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and PL measurement system, respectively. XRD results indicate that the Mg{sub 2}Si film on Si (111) displays polycrystalline structure, whereas Mg{sub 2}Si film on glass substrate is of like-monocrystalline structure.SEM results show that Mg{sub 2}Si film on glass substrate is very compact with a typical dense columnar structure, and the film on Si substrate represents slight delamination phenomenon. EDS results suggest that the stoichiometry of Mg and Si is approximately 2:1. Photoluminescence (PL) of Mg{sub 2}Si films was observed for the first time. The PL emission wavelengths of Mg{sub 2}Si are almost independence on temperature in the range of 77–300 K. The PL intensity decreases gradually with increasing temperature. The PL intensity of Mg{sub 2}Si films on glass substrate is much larger than that of Mg

Laser cladding of a Mg based Mg–Gd–Y–Zr alloy with Al–Si powders

Energy Technology Data Exchange (ETDEWEB)

Chen, Erlei [School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Zhang, Kemin, E-mail: zhangkm@sues.edu.cn [School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Zou, Jianxin [National Engineering Research Center of Light Alloys Net Forming & School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

2016-03-30

Graphical abstract: A Mg based Mg–Gd–Y–Zr alloy was treated by laser cladding with Al–Si powders at different laser scanning speeds. The laser clad layer mainly contains Mg{sub 2}Si, Mg{sub 17}Al{sub 12} and Al{sub 2}(Gd,Y) phases distributed in the Mg matrix. After laser cladding, the corrosion resistance of the Mg alloy was significantly improved together with increased microhardness in the laser clad layers. - Highlights: • A Mg based Mg–Gd–Y–Zr alloy was laser clad with Al–Si powders. • The microstructure and morphology vary with the depth of the clad layer and the laser scanning speed. • Hardness and corrosion resistance were significantly improved after laser cladding. - Abstract: In the present work, a Mg based Mg–Gd–Y–Zr alloy was subjected to laser cladding with Al–Si powders at different laser scanning speeds in order to improve its surface properties. It is observed that the laser clad layer mainly contains Mg{sub 2}Si, Mg{sub 17}Al{sub 12} and Al{sub 2}(Gd,Y) phases distributed in the Mg matrix. The depth of the laser clad layer increases with decreasing the scanning speed. The clad layer has graded microstructures and compositions. Both the volume fraction and size of Mg{sub 2}Si, Mg{sub 17}Al{sub 12} and Al{sub 2}(Gd,Y) phases decreases with the increasing depth. Due to the formation of these hardening phases, the hardness of clad layer reached a maximum value of HV440 when the laser scanning speed is 2 mm/s, more than 5 times of the substrate (HV75). Besides, the corrosion properties of the untreated and laser treated samples were all measured in a NaCl (3.5 wt.%) aqueous solution. The corrosion potential was increased from −1.77 V for the untreated alloy to −1.13 V for the laser clad alloy with scanning rate of 2 mm/s, while the corrosion current density was reduced from 2.10 × 10{sup −5} A cm{sup −2} to 1.64 × 10{sup −6} A cm{sup −2}. The results show that laser cladding is an efficient method to improve

Improved CO_2 adsorption capacity and cyclic stability of CaO sorbents incorporated with MgO

International Nuclear Information System (INIS)

Farah Diana Mohd Daud; Kumaravel Vignesh; Srimala Sreekantan; Abdul Rahman Mohamed

2016-01-01

Calcium oxide (CaO) sorbents incorporated with magnesium oxide (MgO) were synthesized using a co-precipitation route. The sorbents were prepared with different MgO concentrations (from 5 wt% to 30 wt%). The as-prepared sorbents were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and BET surface area analysis techniques. The sintering effect of CaO sorbents was decreased after the incorporation of MgO. The sorbents with 5 wt% and 10 wt% of MgO retained their CO_2 adsorption capacity over multiple cycles. Most importantly, CaO with 10 wt% MgO showed constant CO_2 adsorption capacity over 30 carbonation cycles. The results revealed that CaO with 10 wt% MgO is sufficient to produce sorbents with high surface area, good structural stability and enhanced CO_2 adsorption capacity. (authors)

Effects of Ca on microstructure, mechanical and corrosion properties and biocompatibility of Mg-Zn-Ca alloys.

Science.gov (United States)

Yin, Ping; Li, Nian Feng; Lei, Ting; Liu, Lin; Ouyang, Chun

2013-06-01

Zn and Ca were selected as alloying elements to develop an Mg-Zn-Ca alloy system for biomedical application due to their good biocompatibility. The effects of Ca on the microstructure, mechanical and corrosion properties as well as the biocompatibility of the as-cast Mg-Zn-Ca alloys were studied. Results indicate that the microstructure of Mg-Zn-Ca alloys typically consists of primary α-Mg matrix and Ca₂Mg₆Zn₃/Mg₂Ca intermetallic phase mainly distributed along grain boundary. The yield strength of Mg-Zn-Ca alloy increased slightly with the increase of Ca content, whilst its tensile strength increased at first and then decreased. Corrosion tests in the simulated body fluid revealed that the addition of Ca is detrimental to corrosion resistance due to the micro-galvanic corrosion acceleration. In vitro hemolysis and cytotoxicity assessment disclose that Mg-5Zn-1.0Ca alloy has suitable biocompatibility.

Microstructure and Corrosion Resistance Property of a Zn-AI-Mg Alloy with Different Solidification Processes

Directory of Open Access Journals (Sweden)

Jiang Guang-rui

2017-01-01

Full Text Available Zn-Al-Mg alloy coating attracted much attention due to its high corrosion resistance properties, especially high anti-corrosion performance at the cut edge. As the Zn-Al-Mg alloy coating was usually produced by hot-dip galvanizing method, solidification process was considered to influence its microstructure and corrosion properties. In this work, a Zn-Al-Mg cast alloy was melted and cooled to room temperature with different solidification processes, including water quench, air cooling and furnace cooling. Microstructure of the alloy with different solidification processes was characterized by scanning electron microscopy (SEM. Result shows that the microstructure of the Zn-Al-Mg alloy are strongly influenced by solidification process. With increasing solidification rate, more Al is remained in the primary crystal. Electrochemical analysis indicates that with lowering solidification rate, the corrosion current density of the Zn-Al-Mg alloy decreases, which means higher corrosion resistance.

Frequency and severity of reactions to a 325-mg aspirin dose during desensitization.

Science.gov (United States)

Schuler, Charles F; Baldwin, James L; Baptist, Alan P

2017-03-01

The frequency with which patients with aspirin-exacerbated respiratory disease (AERD) react to 325 mg of aspirin during aspirin desensitization, or fail to react at all, is not fully known. To determine the rate and type of reaction at 325 mg of aspirin during desensitization. A retrospective study of 104 patients who underwent aspirin desensitization from 2010 to 2016 was performed. A standard desensitization protocol (starting at 20-40 mg, progressing through 325 mg, and extinguishing reactions by dose repetition) was used. Reactions were defined by upper respiratory tract symptoms, lower respiratory tract symptoms, and/or forced expiratory volume in 1 second decrease of 15% or greater. Patients who did and did not react were compared by logistic regression. Eighty-four patients reacted (81%) and 20 did not (19%). Seventy-seven patients who had a provoking reaction at 162 mg of aspirin or less subsequently extinguished their reactions before they reached a dose of 325 mg and had no problems at that dose; one subsequent 325-mg reaction occurred during a protocol violation. One initial provoking reaction to 325 mg occurred. Both 325-mg reactions were mild, and neither met the forced expiratory volume in 1 second criterion for a clinically meaningful change. The remaining 5 patients could not complete the protocol because of persistent reactions or social reasons. Reactors were more likely to have had asthma for more than 10 years than nonreactors (odds ratio, 3.2; 95% confidence interval, 1.0-10.3; P = .05). During aspirin desensitization for AERD, provoking reactions at the 325-mg dose are rare (1%) and mild. Patients who react at 162 mg or less and extinguish their reactions may be able to administer the 325-mg dose at home. Copyright © 2016 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Effect of different seawater Mg

NARCIS (Netherlands)

Mewes, A.; Langer, G.; de Nooijer, L.J.; Bijma, J.; Reichart, G.J.

2014-01-01

Magnesium, incorporated in foraminiferal calcite (Mg/CaCC), is used intensively to reconstruct past seawater temperatures but, in addition to temperature, the Mg/CaCC of foraminiferal tests also depends on the ratio of Mg and Ca in seawater (Mg/CaSW). The physiological mechanisms responsible for

Characterization of Hf/Mg co-doped ZnO thin films after thermal treatments

Energy Technology Data Exchange (ETDEWEB)

Li, Chih-Hung; Chung, Hantsun [Graduate Institute of Applied Mechanics, National Taiwan University, Taipei 10617, Taiwan (China); Chen, Jian-Zhang, E-mail: jchen@ntu.edu.tw [Graduate Institute of Applied Mechanics, National Taiwan University, Taipei 10617, Taiwan (China); Cheng, I-Chun, E-mail: iccheng@ntu.edu.tw [Graduate Institute of Photonics and Optoelectronics, Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

2014-11-03

Rf-sputtered Mg{sub 0.05}Zn{sub 0.95}O thin films become amorphous/nanocrystalline with the addition of hafnium oxide. All films (thickness: ∼ 100 nm) sputter-deposited from Hf{sub x}Mg{sub 0.05}Zn{sub 0.95−x}O targets are highly transparent (> 80%) from 400 to 800 nm. The Tauc bandgap ΔE (eV) increases with the Hf content. However, the bandgap decreases after thermal treatment. The reduction in the bandgap is positively correlated with the Hf content and annealing temperature. The residual stresses of films sputtered from Mg{sub 0.05}Zn{sub 0.95}O and Hf{sub 0.025}Mg{sub 0.05}Zn{sub 0.925}O targets are determined based on X-ray diffraction (XRD) data using a bi-axial stress model. The residual stresses of as-deposited films are compressive. As the annealing temperature increases, the residual stresses are relaxed and even become tensile. The bandgap narrowing after thermal treatment is attributed to the stress relaxation that changes the repulsion between the oxygen 2p and zinc 4s bands. Slight grain growth may also result in bandgap reduction because bandgap modification caused by the quantum confinement effect becomes significant in amorphous/nanocrystalline materials. The amorphous thin films reveal good thermal stability after 600 °C annealing for up to 2 h, as evidenced by the XRD and transmission spectra. - Highlights: • Thin films are sputtered from Hf{sub x}Mg{sub 0.05}Zn{sub 0.95−x}O targets at room temperature. • Bandgap increases with Hf content but decreases with post-annealing temperature. • Bandgap narrowing after annealing partly results from the relaxation of stresses. • Bandgap narrowing partly results from quantum confinement effect by nanomaterials. • Hf doping increases resistivity due to the lattice disorder and enlarged bandgap.

Decay of a Jπ=36+ Resonance in the 24Mg+24Mg Reaction

International Nuclear Information System (INIS)

Salsac, M.-D.; Haas, F.; Courtin, S.

2005-01-01

For the 24 Mg+ 24 Mg reaction, striking narrow and correlated resonance structures have been observed previously in the excitation functions of the elastic and low-lying channels. In our study we have decided to focus on the resonance at E C M =45.7 MeV, which is known to have J π =36 + . Despite the very high excitation energy(∼60 MeV) in the 48 Cr composite system, this resonance has a narrow total width of 170 keV. To determine precisely which states in the inelastic 24 Mg channels carry away the resonance flux, an experiment, on the 24 Mg + 24 Mg reaction at energies On and OFF resonance, has been performed at the Legnaro Tandem accelerator using the Prisma fragment spectrometer associated with the CLARA γ array

Enhanced Performance of Mg0.1Zn0.9O UV Photodetectors Using Photoelectrochemical Treatment and Silica Nanospheres

Directory of Open Access Journals (Sweden)

Hsin-Ying Lee

2014-01-01

Full Text Available The Mg0.1Zn0.9O films were grown using atomic layer deposition (ALD system and applied to metal-semiconductor-metal ultraviolet photodetectors (MSM-UPDs as an active layer. To suppress the dangling bonds on the Mg0.1Zn0.9O surface, the photoelectrochemical (PEC treatment was used to passivate the Mg0.1Zn0.9O surface, which could reduce the dark current of the MSM-UPDs about one order. Beside, to increase more incident light into the Mg0.1Zn0.9O active layer of the MSM-UPDs, the 500-nm-diameter silica nanospheres were spin-coated on the Mg0.1Zn0.9O active layer to improve the antireflection capability at the wavelength of 340 nm. The reflectivity of the Mg0.1Zn0.9O films with silica nanospheres antireflection layer decreased about 7.0% in comparison with the Mg0.1Zn0.9O films without silica nanospheres. The photocurrent and UV-visible ratio of the passivated Mg0.1Zn0.9O MSM-UPDs with antireflection layer were enhanced to 5.85 μA and 1.44×104, respectively, at the bias voltage of 5 V. Moreover, the noise equivalent power and the specific detectivity of the passivated Mg0.1Zn0.9O MSM-UPDs with antireflection layer were decreased to 2.60×10-13 W and increased to 1.21×1012 cmHz1/2W−1, respectively, at the bias voltage of 5 V. According to the above mentions, the PEC treatment and silica nanospheres antireflection layer could effectively enhance the performance of Mg0.1Zn0.9O MSM-UPDs.

Expansion during the formation of the magnesium aluminate spinel (MgAl(2)O(4)) from its basic oxide (MgO and Al(2)O(3)) powders

Science.gov (United States)

Duncan, Flavia Cunha

The extraordinary expansion during the reaction sintering of the magnesium aluminate spinel (MgAl2O4) from its basic oxide (MgO and Al2O3) powders was studied. Experimental series of different size fractions of the reacting materials were formulated to produce the Mg-Al spinel. After batches were prepared, specimens were compacted and fired in air from 1200° to 1700°C for a fixed firing time. A separate set of specimens was fired as a function of time to determine the reaction kinetic parameters. Dimensional changes confirmed that extraordinary expansions of three to four times greater than the prediction from the reaction of solids occur. The solid-state reactions were monitored by X-ray diffraction. The activation energy of the spinel reaction formation was determined to be 280 +/- 20 kJ/mol. It is believed to be associated with the diffusivity of Mg 2+ in either magnesia or spinel during the development of the final spinel structure. New porosity developed in the compacts during the reaction formation of spinel. Scanning electron microscopy confirmed that the magnesia evaporated leaving behind porous magnesia grains, condensed on the alumina particles and reacted to form a shell of spinel. Hollow spinel particles resulted from the original particles of alumina. These porosities generated within the reacting materials influenced the expansions. Final volumetric expansion could potentially reach 56% as a result of the reaction of solids and the porosity generation within MgO and Al2O3. Models of a single alumina particle with and without development of internal porosity were developed. 3-D arrangements of particles showed additional porosity, influencing on the expansions. The decrease in porosity of some specimens fired at higher temperatures indicated that sintering and densification occur simultaneously with the reaction formation of spinel. The decrease in the interparticle porosity limits the full expansion of the particulates to levels lower than the

Dehydriding reaction of Mg(NH2)2-LiH system under hydrogen pressure

International Nuclear Information System (INIS)

Aoki, M.; Noritake, T.; Kitahara, G.; Nakamori, Y.; Towata, S.; Orimo, S.

2007-01-01

The dehydriding and structural properties of the 3Mg(NH 2 ) 2 + 12LiH system under hydrogen pressure were investigated using the pressure-composition (p-c) isotherm measurement and X-ray diffraction (XRD) analysis. Two distinct regions, a plateau region and a sloping region, can be seen on the p-c isotherms and the amount of the desorbed hydrogen at 523 K was 4.9 mass%. The enthalpy of hydrogenation calculated using a van't Hoff plot was -46 kJ/mol H 2 . The dehydriding reaction was proposed for the 3Mg(NH 2 ) 2 + 12LiH system based on the obtained p-c isotherms and XRD profiles and chemical valences of Li, Mg, N, and H. In the plateau region on the p-c isotherm, Mg(NH 2 ) 2 , Li 4 Mg 3 (NH 2 ) 2 (NH) 4 (tetragonal), and LiH phases coexist and the molar ratio of the Li 4 Mg 3 (NH 2 ) 2 (NH) 4 phase increases (while those of Mg(NH 2 ) 2 and LiH phases decrease) with the amount of the desorbed hydrogen. On the other hand, the mixture of Li 4+x Mg 3 (NH 2 ) 2-x (NH) 4+x + (8-x)LiH (0 ≤ x ≤ 2) is formed and the lattice volume of the Li 4+x Mg 3 (NH 2 ) 2-x (NH) 4+x phase continuously increases with the amount of the desorbed hydrogen in the sloping region on the p-c isotherm

The microstructure of mechanically alloyed Al-Mg determined by X-ray diffraction peak profile analysis

Energy Technology Data Exchange (ETDEWEB)

Gubicza, J.; Kassem, M.; Ribarik, G.; Ungar, T

2004-05-15

The effect of the nominal Mg content and the milling time on the microstructure and the hardness of mechanically alloyed Al-rich Al-Mg solid solutions is studied. The crystallite size distribution and the dislocation structure are characterized by X-ray diffraction (XRD) peak profile analysis and the hardness is obtained from depth-sensing indentation tests. Magnesium gradually goes into solid solution during ball milling and after 3 h an almost complete solid solution is attained. With increasing milling time, the Mg concentration in solid solution, the dislocation density and the hardness increase, whereas the crystallite size decreases. A similar tendency of these parameters is observed at a particular duration of ball milling with increasing nominal Mg content. After 3 h milling there are no changes in both the microstructure and the hardness.

Mg-Ca Alloys Produced by Reduction of CaO: Understanding of ECO-Mg Alloy Production

Science.gov (United States)

Jung, In-Ho; Lee, Jin Kyu; Kim, Shae K.

2017-04-01

There have been long debates about the environment conscious (ECO) Mg technology which utilizes CaO to produce Ca-containing Mg alloys. Two key process technologies of the ECO-Mg process are the chemical reduction of CaO by liquid Mg and the maintenance of melt cleanliness during the alloying of Ca. Thermodynamic calculations using FactSage software were performed to explain these two key issues. In addition, an experimental study was performed to compare the melt cleanliness of the Ca-containing Mg alloys produced by the conventional route with metallic Ca and the ECO-Mg route with CaO.

The catalytic destruction of antibiotic tetracycline by sulfur-doped manganese oxide (S-MgO) nanoparticles.

Science.gov (United States)

Moussavi, Gholamreza; Mashayekh-Salehi, Ali; Yaghmaeian, Kamyar; Mohseni-Bandpei, Anoshiravan

2018-03-15

The present study evaluates the efficacy of S-doped MgO (S-MgO) as compared with the plain MgO as a catalyst for destructive removal of tetracycline (TTC) in aqueous solutions. The S-MgO had around 6% S in its structure. Doping MgO with S caused increase in surface oxygen vacancy defects. Adding S-MgO (12 g/L) to a TTC aqueous solution (50 mg/L) caused removal of around 99% TTC at the neutral pH (ca. 5.1) and a short reaction time of 10 min. In comparison, plain MgO could remove only around 15% of TTC under similar experimental conditions. Diffusing O 2 into the TTC solution under the reaction with S-MgO resulted in a considerable improvement of TTC removal as compared to diffusing N 2 . Complete removal of TTC and 86.4% removal of its TOC could be obtained using 2 g/L S-MgO nanoparticles. The removal of TTC increased with the increase in solution temperature. The presence of nitrate, sulfate and chloride did not considerably affect the removal of TTC using S-MgO while TTC removal significantly decreased at the presence of bicarbonate and phosphate. The S-MgO was a stable and reusable catalyst exhibiting much higher catalytic activity than plain MgO for the TTC destruction. Accordingly, S-MgO is an emerging and efficient catalyst for catalytic decomposition and mineralization of such pharmaceutical compounds as TTC under atmospheric temperature and pressure. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hydrothermal synthesis and corrosion behavior of the protective coating on Mg-2Zn-Mn-Ca-Ce alloy

Directory of Open Access Journals (Sweden)

Dan Song

2016-12-01

Full Text Available Protective coatings were synthesized on the Mg-2Zn-Mn-Ca-Ce Mg alloy through the hydrothermal method with de-ionized water as the reagent. The coatings were composed of Mg hydroxide, generally uniform and compact. Hydrogen evolution tests and electrochemical tests in the Hanks’ solution demonstrated that the Mg(OH2 coatings effectively decreased the bio-degradation rate of the Mg alloy substrate. Microstructure observation showed that the coating formation on the secondary phases was more difficult than that on the α-Mg matrix, which led to micro cracks and pores on the secondary phases after drying. Over synthesizing time, the coating layer on secondary phases gradually becomes more compact and uniform. Meanwhile, owing to the thicker and more compact coatings, the corrosion resistance and protective efficiency were significantly improved with longer synthesizing time as well.

Positron annihilation study of formation of Mg vacancy in MgO

International Nuclear Information System (INIS)

Mizuno, M.; Araki, H.; Shirai, Y.; Inoue, Y.; Sugita, K.; Mizoguchi, T.; Tanaka, I.; Adachi, H.

2004-01-01

We have investigated the formation of Mg vacancy induced by ultra-dilute trivalent impurities in MgO by a combination of positron annihilation measurement and theoretical calculations of positron lifetimes. The undoped MgO yields the shortest positron lifetime of 130 ps that is shorter than that of 166 ps previously reported using a single crystal sample. The positron lifetime of the doped samples increases with the increase of the Al or Ga dopant concentration and is saturated at around 170 ps. This result indicates that the previously reported value of 166 ps is ascribed to not the bulk but the vacancy state induced by impurities. The experimental bulk lifetime of 130 ps, which is obtained by employing trapping model, is well reproduced by the theoretical calculation using the semiconductor model. The calculated defect lifetime is about 20 ps longer than the experimental value. This may be due to the lattice relaxation around Mg vacancy associated with the trapping of positrons. (orig.)

Positron annihilation study of formation of Mg vacancy in MgO

Energy Technology Data Exchange (ETDEWEB)

Mizuno, M.; Araki, H.; Shirai, Y. [Science and Technology Center for Atoms, Molecules and Ions Control, Osaka Univ., Osaka (Japan); Inoue, Y.; Sugita, K. [Dept. of Materials Science and Engineering, Osaka Univ., Osaka (Japan); Mizoguchi, T.; Tanaka, I.; Adachi, H. [Dept. of Materials Science and Engineering, Kyoto Univ., Kyoto (Japan)

2004-07-01

We have investigated the formation of Mg vacancy induced by ultra-dilute trivalent impurities in MgO by a combination of positron annihilation measurement and theoretical calculations of positron lifetimes. The undoped MgO yields the shortest positron lifetime of 130 ps that is shorter than that of 166 ps previously reported using a single crystal sample. The positron lifetime of the doped samples increases with the increase of the Al or Ga dopant concentration and is saturated at around 170 ps. This result indicates that the previously reported value of 166 ps is ascribed to not the bulk but the vacancy state induced by impurities. The experimental bulk lifetime of 130 ps, which is obtained by employing trapping model, is well reproduced by the theoretical calculation using the semiconductor model. The calculated defect lifetime is about 20 ps longer than the experimental value. This may be due to the lattice relaxation around Mg vacancy associated with the trapping of positrons. (orig.)

Development of MgB2 superconductor wire with high critical current

International Nuclear Information System (INIS)

Kim, Chan Joong; Jun, Byung Hyuk; Park, Soon Dong; Kim, Nam Kyu; Kim, Yi Jeong; Yi, Ji Hye; Lee, Ji Hyun; Tan, Kai Sin

2009-07-01

The MgB 2 superconductor with smaller grain size could improve its critical properties by providing flux pinning centers with high grain boundary density. The effects of C doping such as charcoal, paper ash and glycerin on the superconducting properties was investigated for in situ processed MgB 2 samples using low purity semi-crystalline B powder. The results show a decrease in Tc and an enhancement of Jc at high fields for the C-doped samples as compared to the un-doped samples. A combined process of a mechanical ball milling and liquid glycerin (C 3 H 8 O 3 ) treatment of B powder has been conducted to enhance the superconducting properties of MgB 2 . The mechanical ball milling was effective for grain refinement, and a lattice disorder was easily achieved by glycerin addition. With the combined process, the critical properties was further increased due to a higher grain boundary density and a greater C substitution. To get fine grain structure of MgB 2 with high critical current properties, mechanical milling for as-received B powder and low temperature solid-state reaction of 550 or 600 .deg. C were attempted to in situ powder-in-tube processed MgB 2 /Fe wires. The critical current properties of the MgB 2 wires using the milled B powder were enhanced due to a smaller grain size and an increased volume of the superconducting phase. The solid-state reaction of a low temperature process for the samples using the milled B powder resulted in a poorer crystallinity with a smaller grain size, which improved superconducting properties. We established the system to measure the transport current properties of the MgB 2 wires. The field dependence of the transport Jc was evaluated for the MgB 2 wires heat-treated at different heat treatment conditions using ball-milled and glycerin-treated B powder. The MgB 2 magnet was developed and the AC loss of MgB 2 wire was also investigated. A conduction cooling device to cool the MgB 2 coil down to 4 K has been fabricated and the

Improved dehydriding property of polyvinylpyrrolidone coated Mg-Ni hydrogen storage nano-composite prepared by hydriding combustion synthesis and wet mechanical milling

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Linglong Yao

2018-02-01

Full Text Available In this work, polyvinylpyrrolidone (PVP coated Mg95Ni5 nano-composites were prepared by hydriding combustion synthesis (HCS plus wet mechanical milling (WM with tetrahydrofuran (THF and donated as WM-x wt% PVP (x = 1, 3, 5 and 7 respectively. The phase compositions, microstructures and dehydriding property, as well as the co-effect of PVP and THF were investigated in detail. XRD results showed that the average crystal size of MgH2 in the milled Mg95Ni5 decreased from 23 nm without PVP to 18 nm with 1 wt% PVP. The peak temperature of dehydrogenation of MgH2 in the milled Mg95Ni5 decreased from 293.0 °C without THF to 250.4 °C with THF. The apparent activation energy for decomposition of MgH2 in WM-7 wt% PVP was estimated to be 66.94 kJ/mol, which is 37.70 kJ/mol lower than that of milled Mg95Ni5 without THF and PVP. PVP and THF can facilitate the refinement of particle size during mechanical milling process. Attributed to small particle sizes and synergistic effect of PVP and THF, the composites exhibit markedly improved dehydriding properties. Keywords: Mg-Ni-PVP, Composite, Mg-based alloy, Wet mechanical milling, Dehydriding temperature

Synthesis of Mg(OH)2, MgO, and Mg nanoparticles using laser ablation of magnesium in water and solvents

Energy Technology Data Exchange (ETDEWEB)

Tran, P.X.; Howard, B.H.; Martello, D.V.; Soong, Y.; Chyu, M.K.

2008-01-01

laser ablation of magnesium in deionized water (OW), solutions of OW and sodium dodecyl sulfate (50S) with different concentrations, acetone and 2-propanol has been conducted, The results showed that ablation in acetone and 2-propanol yielded MgO and Mg nanocrystallites as isolated particles and agglomerated chains probably intermixed with organic residues resulting from the alterationj decomposition of the solvents under the high-energy conditions. Brucite-like Mg(OH)2 particles were mainly produced by laser ablation of Mg in either OW or OW~SOS solutions. Ablation in OW yielded particles of fiber-like shapes having a diameter of about 5-lOnm and length as long as 150nm. Materials produced in DW-SOS solutions were composed of various size and shape particles, Some had rough surfaces with irregular shapes. Small particles were about 20-30nm and larger particles were about 120 nm. Particles with rod-like, triangular, and plate-like shapes were also observed.

Synthesis of Mg(OH) 2, MgO, and Mg nanoparticles using laser ablation of magnesium in water and solvents

Science.gov (United States)

Phuoc, Tran X.; Howard, Bret. H.; Martello, Donald V.; Soong, Yee; Chyu, Minking K.

2008-11-01

Laser ablation of magnesium in deionized water (DW), solutions of DW and sodium dodecyl sulfate (SDS) with different concentrations, acetone and 2-propanol has been conducted. The results showed that ablation in acetone and 2-propanol yielded MgO and Mg nanocrystallites as isolated particles and agglomerated chains probably intermixed with organic residues resulting from the alteration/decomposition of the solvents under the high-energy conditions. Brucite-like Mg(OH) 2 particles were mainly produced by laser ablation of Mg in either DW or DW-SDS solutions. Ablation in DW yielded particles of fiber-like shapes having a diameter of about 5-10 nm and length as long as 150 nm. Materials produced in DW-SDS solutions were composed of various size and shape particles. Some had rough surfaces with irregular shapes. Small particles were about 20-30 nm and larger particles were about 120 nm. Particles with rod-like, triangular, and plate-like shapes were also observed.

Composition dependency of the glass forming ability (GFA) in Mg-Ni-Si system by mechanical alloying

International Nuclear Information System (INIS)

Xie Haowen; Lin Jianguo; Li Yuncang; Hodgson, Peter D.; Wen Cuie

2007-01-01

The pure elemental powder mixtures with the compositions of Mg 65 Ni x Si 35-x (x = 10, 20, 25, 33 at.%) were subject to high-energy ball mill, and the structures of the mixtures at different intervals of milling were characterised by X-ray diffraction (XRD). The compositional dependency of the glass forming ability (GFA) in Mg-Ni-Si system was evaluated based on the experimental results and the theoretical calculation. The compositional dependency of GFA in Mg-Ni-Si system can be understood well by comparing the enthalpies of the crystalline and amorphous phases based on the Miedema's theory for the formation enthalpy of alloys. Increasing the Ni/Mg ratio and/or decreasing Si content can improve the amorphous formability. The calculation results might be of great help in optimising the composition with high GFA in Mg-Ni-Si system

Heterotopic cardiac transplantation decreases the capacity for rat myocardial protein synthesis

International Nuclear Information System (INIS)

Klein, I.; Samarel, A.M.; Welikson, R.; Hong, C.

1991-01-01

Heterotopic cardiac isografts are vascularly perfused hearts that maintain structural and functional integrity for prolonged periods of time. When placed in an infrarenal location, the heart is hemodynamically unloaded and undergoes negative growth, leading to cardiac atrophy. At 7 and 14 days after transplantation, the transplanted heart was decreased in size compared with the in situ heart (p less than 0.001). To assess the possible mechanism(s) to account for this reduction in size we studied in vivo rates of total left ventricular (LV) protein synthesis, total LV RNA content, and 18S ribosomal RNA content by nucleic acid hybridization. The LV protein synthetic rate was 4.7 and 5.3 mg/day in the in situ heart and was significantly decreased to 2.9 and 2.7 mg/day in the transplanted hearts at 7 and 14 days, respectively. LV RNA content of the transplant declined to 53% and 48% of the in situ value at 7 and 14 days, respectively. Hybridization studies revealed that LV 18S ribosomal subunit content was reduced proportionately to total RNA in the heterotopic hearts. As a result of these changes, there was no significant difference in the efficiency of total LV protein synthesis between the in situ and transplanted hearts. The present studies demonstrate that the hemodynamic unloading and cardiac atrophy that is characteristic of heterotopic cardiac transplantation is accompanied by a decrease in LV total RNA content and 18S RNA, resulting in a decreased capacity for myocardial protein synthesis

Cannabidiol Oil for Decreasing Addictive Use of Marijuana: A Case Report.

Science.gov (United States)

Shannon, Scott; Opila-Lehman, Janet

2015-12-01

This case study illustrates the use of cannabidiol (CBD) oil to decrease the addictive use of marijuana and provide anxiolytic and sleep benefits. Addiction to marijuana is a chronic, relapsing disorder, which is becoming a prevalent condition in the United States. The most abundant compound in the marijuana, which is called tetrahydrocannabinol (THC), has been widely studied and known for its psychoactive properties. The second most abundant component-CBD-has been suggested to have the medicinal effects of decreasing anxiety, improving sleep, and other neuro-protective effects. The mechanism of action for CBD has been suggested to be antagonistic to the psychoactive properties of THC in many locations within the central nervous system. Such action raises the issue of whether it might be beneficial to use CBD in isolation to facilitate withdrawal of marijuana use. The specific use of CBD for marijuana reduction has not been widely studied. The patient was a 27-y-old male who presented with a long-standing diagnosis of bipolar disorder and a daily addiction to marijuana use. In the described intervention, the only change made to the patient's treatment was the addition of CBD oil with the dosage gradually decreasing from 24 to 18 mg. With use of the CBD oil, the patient reported being less anxious, as well as settling into a regular pattern of sleep. He also indicated that he had not used any marijuana since starting the CBD oil. With the decrease in the dosage to 18 mg, the patient was able to maintain his nonuse of marijuana.

Antibacterial biodegradable Mg-Ag alloys

Directory of Open Access Journals (Sweden)

D Tie

2013-06-01

Full Text Available The use of magnesium alloys as degradable metals for biomedical applications is a topic of ongoing research and the demand for multifunctional materials is increasing. Hence, binary Mg-Ag alloys were designed as implant materials to combine the favourable properties of magnesium with the well-known antibacterial property of silver. In this study, three Mg-Ag alloys, Mg2Ag, Mg4Ag and Mg6Ag that contain 1.87 %, 3.82 % and 6.00 % silver by weight, respectively, were cast and processed with solution (T4 and aging (T6 heat treatment.The metallurgical analysis and phase identification showed that all alloys contained Mg4Ag as the dominant β phase. After heat treatment, the mechanical properties of all Mg-Ag alloys were significantly improved and the corrosion rate was also significantly reduced, due to presence of silver. Mg(OH2 and MgO present the main magnesium corrosion products, while AgCl was found as the corresponding primary silver corrosion product. Immersion tests, under cell culture conditions, demonstrated that the silver content did not significantly shift the pH and magnesium ion release. In vitro tests, with both primary osteoblasts and cell lines (MG63, RAW 264.7, revealed that Mg-Ag alloys show negligible cytotoxicity and sound cytocompatibility. Antibacterial assays, performed in a dynamic bioreactor system, proved that the alloys reduce the viability of two common pathogenic bacteria, Staphylococcus aureus (DSMZ 20231 and Staphylococcus epidermidis (DSMZ 3269, and the results showed that the killing rate of the alloys against tested bacteria exceeded 90%. In summary, biodegradable Mg-Ag alloys are cytocompatible materials with adjustable mechanical and corrosion properties and show promising antibacterial activity, which indicates their potential as antibacterial biodegradable implant materials.

Study on the effect of the metal–support (Fe-MgO and Pt-MgO) interaction in alcohol-CVD synthesis of carbon nanotubes

International Nuclear Information System (INIS)

Steplewska, Anna; Borowiak-Palen, Ewa

2011-01-01

This study presents the effect of the metal–support interaction in two systems: (1) iron particle, and (2) platinum particles, being supported on magnesium oxide (MgO) nanopowder in alcohol-CVD process for carbon nanotubes (CNTs) growth. The employment of the different metals but the same substrate (with equal molar ratio) resulted in the synthesis of single-walled CNTs (SWCNTs) or double-walled CNTs (DWCNTs), using iron and platinum, respectively. Furthermore, along with the prolongation of the process time, the decrease of the mean nanotubes diameter in case of iron-catalyzed materials was detected. Interestingly, the extention of the growth time in the synthesis using Pt/MgO resulted in the synthesis of the thicker mean nanotubes diameter. However, for both applied catalytic systems the reduction of the diameter distribution of the tubes and the increase of relative purity of the samples upon the growth time increase were detected.

Study on the effect of the metal-support (Fe-MgO and Pt-MgO) interaction in alcohol-CVD synthesis of carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Steplewska, Anna, E-mail: asteplewska@zut.edu.pl; Borowiak-Palen, Ewa [West Pomeranian University of Technology, Centre of Knowledge Based Nanomaterials and Technologies, Institute of Chemical and Environment Engineering (Poland)

2011-05-15

This study presents the effect of the metal-support interaction in two systems: (1) iron particle, and (2) platinum particles, being supported on magnesium oxide (MgO) nanopowder in alcohol-CVD process for carbon nanotubes (CNTs) growth. The employment of the different metals but the same substrate (with equal molar ratio) resulted in the synthesis of single-walled CNTs (SWCNTs) or double-walled CNTs (DWCNTs), using iron and platinum, respectively. Furthermore, along with the prolongation of the process time, the decrease of the mean nanotubes diameter in case of iron-catalyzed materials was detected. Interestingly, the extention of the growth time in the synthesis using Pt/MgO resulted in the synthesis of the thicker mean nanotubes diameter. However, for both applied catalytic systems the reduction of the diameter distribution of the tubes and the increase of relative purity of the samples upon the growth time increase were detected.

Structural and physical properties of Mg3-xZnxSb2 (x=0-1.34)

International Nuclear Information System (INIS)

Ahmadpour, Faraz; Kolodiazhnyi, Taras; Mozharivskyj, Yurij

2007-01-01

The Mg 3-x Zn x Sb 2 phases with x=0-1.34 were prepared by direct reactions of the elements in tantalum tubes. According to the X-ray single crystal and powder diffraction, the Mg 3-x Zn x Sb 2 phases crystallize in the same P3-bar m1 space group as the parent Mg 3 Sb 2 phase. The Mg 3-x Zn x Sb 2 structure is different from the other substituted structures of Mg 3 Sb 2 , such as (Ca, Sr, Ba) Mg 2 Sb 2 or Mg 5.23 Sm 0.77 Sb 4 , in a way that in Mg 3-x Zn x Sb 2 the Mg atoms on the tetrahedral sites are replaced, while in the other structures Mg on the octahedral sites is replaced. Thermoelectric performance for the two members of the series, Mg 3 Sb 2 and Mg 2.36 Zn 0.64 Sb 2 , was evaluated from low to room temperatures through resistivity, Seebeck coefficient and thermal conductivity measurements. In contrast to Mg 3 Sb 2 which is a semiconductor, Mg 2.36 Zn 0.64 Sb 2 is metallic and exhibits an 18-times larger dimensionless figure-of-merit, ZT, at room temperature. However, thermoelectric performance of Mg 2.36 Zn 0.64 Sb 2 is still poor and it is mostly due to its large electrical resistivity. - Graphical abstract: The Mg atoms in Mg 3 Sb 2 were successfully substituted with Zn, with Zn going exclusively into the tetrahedral sites. Zn substitution increases the electrical conductivity in Mg 2.36 Zn 0.64 Sb 2 by closing the band gap. This change combined with a decrease in the thermal conductivity improves the ZT value

Effect of combination tablets containing amlodipine 10 mg and irbesartan 100 mg on blood pressure and cardiovascular risk factors in patients with hypertension

Directory of Open Access Journals (Sweden)

Yagi S

2015-01-01

Full Text Available Shusuke Yagi,1 Akira Takashima,1 Minoru Mitsugi,2 Toshihiro Wada,2 Junko Hotchi,1 Ken-ichi Aihara,3 Tomoya Hara,1 Masayoshi Ishida,1 Daiju Fukuda,4 Takayuki Ise,1 Koji Yamaguchi,1 Takeshi Tobiume,1 Takashi Iwase,1 Hirotsugu Yamada,1 Takeshi Soeki,1 Tetsuzo Wakatsuki,1 Michio Shimabukuro,4 Masashi Akaike,5 Masataka Sata11Department of Cardiovascular Medicine, Graduate School of Health Biosciences, University of Tokushima, Tokushima, 2Department of Internal Medicine, Shikoku Central Hospital, Shikokuchuo, 3Department of Medicine and Bioregulatory Sciences, 4Department of Cardio-Diabetes Medicine, 5Department of Medical Education, Graduate School of Health Biosciences, University of Tokushima, Tokushima, JapanBackground: Hypertension is one of the major risk factors for cardiovascular and cerebrovascular disease and mortality. Patients who receive insufficient doses of antihypertensive agents or who are poorly adherent to multidrug treatment regimens often fail to achieve adequate blood pressure (BP control. The aim of this study was to determine the efficacy of an angiotensin II receptor blocker (ARB and calcium channel blocker (CCB combination tablet containing a regular dose of irbesartan (100 mg and a high dose of amlodipine (10 mg with regard to lowering BP and other risk factors for cardiovascular disease.Methods: We retrospectively evaluated data from 68 patients with essential hypertension whose treatment regimen was changed either from combination treatment with an independent ARB and a low-dose or regular-dose CCB or from a combination tablet of ARB and a low-dose or regular-dose CCB to a combination tablet containing amlodipine 10 mg and irbesartan 100 mg, because of incomplete BP control. Previous treatments did not include irbesartan as the ARB.Results: The combination tablet decreased systolic and diastolic BP. In addition, it significantly decreased serum uric acid, low-density lipoprotein cholesterol, and increased high

Structural and optical properties of Mg doped ZnS quantum dots and biological applications

Science.gov (United States)

Ashokkumar, M.; Boopathyraja, A.

2018-01-01

Zn1-xMgxS (x = 0, 0.2 and 0.4) quantum dots (QDs) were prepared by co-precipitation method. The Mg dopant did not modify the cubic blende structure of ZnS QDs. The Mg related secondary phase was not detected even for 40% of Mg doping. The size mismatch between host Zn ion and dopant Mg ion created distortion around the dopant. The creation of distortion centres produced small changes in the lattice parameters and diffraction peak position. All the QDs showed small sulfur deficiency and the deficiency level were increased by Mg doping. Band gap of the QD was decreased due to the dominated quantum confinement effect over compositional effect at initial doping of Mg. But at higher doping the band gap was increased due to compositional effect, since there was no change in average crystallite size. The prepared QDs had three emission bands in the UV and Visible regions corresponding to near band edge emission and defect related emissions. The electron transport reaction chain which forms free radicals was broken by sulfur vacancy trap sites. Therefore, the ZnS QDs had better antioxidant activity and the antioxidant behaviour was enhanced by Mg doping. The enhanced UV absorption and emission of 20% of Mg doped ZnS QDs let to maximize the zone of inhibition against E. Coli bacterial strain.

Effect of Ce on Casting Structure of Near-rapidly Solidified Al-Zn-Mg-Cu Alloy

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HUANG Gao-ren

2017-11-01

Full Text Available Through using XRD,DSC,SEM,EDS and other modern analysis methods, the effects of rare earth element Ce on microstructure and solidification temperature of Al-Zn-Mg-Cu under different cooling rates were studied, the principle of Ce on grain refining and melt cleaning of alloys was analyzed and discussed. The results show that MgZn2 phase and α-Al matrix are the main precipitations, Al,Cu,Mg and other elements dissolve in MgZn2 phase, a new phase Mg(Zn, Cu, Al2 is formed, solute elements in the grain boundary have higher concentration, eutectic reaction takes place between MgZn2 and α-Al, lamellar eutectic structure is generated. The addition of Ce decreases the dendritic arm spacing,reduces the layer spacing between eutectic phases and refines the eutectic structure and the grain significantly, and inhibits the appearance of the impurity phase Al7Cu2Fe in aluminum alloys. The addition of Ce also reduces the precipitation temperature of α-Al matrix and eutectic phase by 6.4℃ and 5.6℃ respectively.

Hydrodechlorination of Tetrachloromethane over Palladium Catalysts Supported on Mixed MgF2-MgO Carriers

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Magdalena Bonarowska

2016-11-01

Full Text Available Pd/MgO, Pd/MgF2 and Pd/MgO-MgF2 catalysts were investigated in the reaction of CCl4 hydrodechlorination. All the catalysts deactivated in time on stream, but the degree of deactivation varied from catalyst to catalyst. The MgF2-supported palladium with relatively large metal particles appeared the best catalyst, characterized by good activity and selectivity to C2-C5 hydrocarbons. Investigation of post-reaction catalyst samples allowed to find several details associated with the working state of hydrodechlorination catalysts. The role of support acidity was quite complex. On the one hand, a definite, although not very high Lewis acidity of MgF2 is beneficial for shaping high activity of palladium catalysts. The MgO-MgF2 support characterized by stronger Lewis acidity than MgF2 contributes to very good catalytic activity for a relatively long reaction period (~5 h but subsequent neutralization of stronger acid centers (by coking eliminates them from the catalyst. On the other hand, the role of acidity evolution, which takes place when basic supports (like MgO are chlorided during HdCl reactions, is difficult to assess because different events associated with distribution of chlorided support species, leading to partial or even full blocking of the surface of palladium, which plays the role of active component in HdCl reactions.

Catalytic properties of pure and K{sup +}-doped Cu O/Mg O system towards 2-propanol conversion

Energy Technology Data Exchange (ETDEWEB)

El-Molla, S. A.; Amin, N. H.; Hammed, M. N.; Sultan, S. N. [Ain Shams University, Faculty of Education, Chemistry Department, Roxy, Heliopolis, Cairo 11757 (Egypt); El-Shobaky, G. A., E-mail: saharelmolla@yahoo.com [National Research Center, Dokki, Cairo (Egypt)

2013-08-01

Cu O/Mg O system having different compositions was prepared by impregnation method followed by calcination at 400-900 C. The effect of Cu O content, calcination temperature and doping with small amounts of K{sup +} species (1-3 mol %) on physicochemical, surface and catalytic properties of the system were investigated using X-ray diffraction, adsorption of N{sub 2} at - 196 C, and conversion of isopropyl alcohol at 150-400 C using a flow technique. The results revealed that the solids having the formulae 0.2 and 0.3 Cu O/Mg O calcined at 400 C consisted of nano sized Mg O and Cu O as major phases together with Cu{sub 2}O as minor phase. The Bet-surface areas of different absorbents are decreased by increasing Cu O content, calcination temperature and K{sup +}-doping. Mg O-support material showed very small catalytic activity in 2-propanol conversion. The investigated system behaved as selective catalyst for dehydrogenation of 2-propanol with selectivity >80%. The catalytic activity increased by increasing Cu O content and decreased by increasing the calcination temperature within 400-900 C. K{sup +}-doping increased the catalytic activity and catalytic durability. (Author)

Glutamate decarboxylase and. gamma. -aminobutyric acid transaminase activity in brain structures during action of high concentrated sulfide gas on a background of hypo- and hypercalcemia

Energy Technology Data Exchange (ETDEWEB)

Kadyrov, G.K.; Aliyev, A.M.

Activity of the following enzymes was studied on the background of hypo- and hypercalcemia and exposure to high concentration of sulfide gas: glutamate decarboxylase (GDC) and {gamma}-aminobutyric acid transaminase (GABA-T). These enzymes regulate metabolism of GABA. The results showed that a 3.5 hr exposure to sulfide gas at a concentration of 0.3 mg/1 led to significantly increased activity of GDC in cerebral hemispheres, cerebellum and in brain stem. Activity of GABA-T dropped correspondingly. On the background of hypercalcemia induced by im. injection of 10% calcium gluconate (0.6 m1/200 g body weight of experimental rats) the negative effect caused by the exposure to sulfide gas was diminished. Under conditions of hypocalcemia (im. injection of 10 mg/200 g body weight of sodium oxalate), exposure to sulfide gas led to a significantly decreased activity of GDC and GABA-T in the hemispheres and in the brain stem, but in the cerebellum the activity of GDC increased sharply while that of GABA-T decreased correspondingly. 8 refs.

Changes in Periodontal Parameters and C-Reactive Protein After Pregnancy.

Science.gov (United States)

Raga, Lucía Gil; Mínguez, Ignacio; Caffesse, Raul; Llambés, Fernando

2016-12-01

This study assesses hormonal, inflammatory, and periodontal changes in pregnant women and postpartum in the absence of periodontal treatment, and seeks to determine any correlations among these parameters. A longitudinal, observational study of 117 pregnant women (aged 23 to 42 years) was undertaken in a private gynecologic center between weeks 32 and 35 of pregnancy and 6 to 8 weeks after delivery. Levels of progesterone and C-reactive protein (CRP) in plasma were determined, as well as periodontal indices, including: 1) plaque index (PI); 2) bleeding on probing (BOP); 3) probing depth (PD); and 4) clinical attachment level (CAL). Postpartum progesterone and CRP declined sharply from 90.85 ± 42.51 ng/mL and 3.73 ± 4.01 mg/L to 0.77 ± 1.43 ng/mL and 1.43 ± 1.67 mg/L, respectively. There was also a significant improvement in all periodontal indices (P 6 mm decreased significantly (P periodontal treatment. Decrease in CRP was related to an improvement in periodontal bleeding.

Damage accumulation in MgO irradiated with MeV Au ions at elevated temperatures

Energy Technology Data Exchange (ETDEWEB)

Bachiller-Perea, Diana, E-mail: dianabachillerperea@gmail.com [Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Univ. Paris-Sud, CNRS-IN2P3, Université Paris-Saclay, 91405, Orsay Cedex (France); Centro de Micro-Análisis de Materiales, Universidad Autónoma de Madrid, C/Faraday 3, 28049, Madrid (Spain); Dpto. de Física Aplicada, Universidad Autónoma de Madrid, Ciudad Universitaria de Cantoblanco, 28049, Madrid (Spain); Debelle, Aurélien, E-mail: aurelien.debelle@u-psud.fr [Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Univ. Paris-Sud, CNRS-IN2P3, Université Paris-Saclay, 91405, Orsay Cedex (France); Thomé, Lionel [Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Univ. Paris-Sud, CNRS-IN2P3, Université Paris-Saclay, 91405, Orsay Cedex (France); Behar, Moni [Instituto de Física, Universidade Federal do Rio Grande do Sul, C.P. 15051, 91501-970, Porto Alegre, RS (Brazil)

2016-09-15

The damage accumulation process in MgO single crystals under medium-energy heavy ion irradiation (1.2 MeV Au) at fluences up to 4 × 10{sup 14} cm{sup −2} has been studied at three different temperatures: 573, 773, and 1073 K. Disorder depth profiles have been determined through the use of the Rutherford backscattering spectrometry in channeling configuration (RBS/C). The analysis of the RBS/C data reveals two steps in the MgO damage process, irrespective of the temperature. However, we find that for increasing irradiation temperature, the damage level decreases and the fluence at which the second step takes place increases. A shift of the damage peak at increasing fluence is observed for the three temperatures, although the position of the peak depends on the temperature. These results can be explained by an enhanced defect mobility which facilitates defect migration and may favor defect annealing. X-ray diffraction reciprocal space maps confirm the results obtained with the RBS/C technique. - Highlights: • High-temperature MeV-ion irradiated MgO exhibits a two-step damage process. • The occurrence of the second step is delayed with increasing temperature. • The damage level decreases with increasing temperature. • A shift of the damage peak is observed with increasing fluence. • A high defect mobility at high temperatures in MgO is clearly evidenced.

Intrinsic Conductivity in Magnesium-Oxygen Battery Discharge Products: MgO and MgO2

DEFF Research Database (Denmark)

Smith, Jeffrey G.; Naruse, Junichi; Hiramatsu, Hidehiko

2017-01-01

Nonaqueous magnesium–oxygen (or “Mg-air”) batteries are attractive next generation energy storage devices due to their high theoretical energy densities, projected low cost, and potential for rechargeability. Prior experiments identified magnesium oxide, MgO, and magnesium peroxide, MgO2...

DC conductivity and Seebeck coefficient of nonstoichiometric MgCuZn ferrites

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Madhuri W.

2017-02-01

Full Text Available Nonstoichiometric series of Mg0.5−xCuxZn0.5Fe1.9O4−δ where x = 0.0, 0.1, 0.15, 0.2 and 0.25 has been synthesized by conventional solid state reaction route. The single phase spinel structure of the double sintered ferrites was confirmed by X-ray diffraction patterns (XRD. The ferrite series was studied in terms of DC electrical conductivity and thermoelectric power in the temperature ranging from room temperature to 300 °C and 400 °C, respectively. It was observed that DC electrical conductivity and Seebeck coefficient α decreased with the increase in x. DC electrical conductivity was found to decrease by about 4 orders. All the compositions showed a negative Seebeck coefficient exhibiting n-type semiconducting nature. From the above experimental results, activation energy and mobility of all the samples were estimated. Small polaron hopping conduction mechanism was suggested for the series of ferrites. Owing to their low conductivity the nonstoichiometric MgCuZn ferrites are the best materials for transformer core and high definition television deflection yokes.

Decreased RECQL5 correlated with disease progression of osteosarcoma

International Nuclear Information System (INIS)

Wu, Junlong; Zhi, Liqiang; Dai, Xin; Cai, Qingchun; Ma, Wei

2015-01-01

Human RecQ helicase family, consisting of RECQL, RECQL4, RECQL5, BLM and WRN, has critical roles in genetic stability and tumorigenesis. Although RECQL5 has been reported to correlate with the susceptibility to malignances including osteosarcoma, the specific effect on tumor genesis and progression is not yet clarified. Here we focused on the relationship between RECQL5 expression and osteosarcoma disease progression, and further investigated the function of RECQL5 on MG-63 cell proliferation and apoptosis. By immunohistochemical analysis, qRT-PCR and western blot, we found that RECQL5 expression was downregulated in osteosarcoma tissues and cells. Patients with advanced tumor stage and low grade expressed lower RECQL5. To construct a stable RECQL5 overexpression osteosarcoma cell line (MG-63-RECQL5), RECQL5 gene was inserted into the human AAVS1 safe harbor by CRISPR/Cas9 system. The overexpression of RECQL5 was verified by qRT-PCR and western blot. Cell proliferation, cell cycle and apoptosis assay revealed that RECQL5 overexpression inhibited proliferation, induced G1-phase arrest and promoted apoptosis in MG-63 cells. Collectively, our results suggested RECQL5 as a tumor suppressor in osteosarcoma and may be a potential therapeutic target for osteosarcoma treatment. - Highlights: • The expression of RECQL5 was downregulated in osteosarcoma tissues and cells. • Decreased RECQL5 correlated with osteosarcoma Enneking surgical classification. • We constructed a stable RECQL5 overexpression cell line by CRISPR/Cas9 system. • RECQL5 overexpression inhibited proliferation of MG-63 cells. • RECQL5 overexpression promoted apoptosis of MG-63 cells.

Decreased RECQL5 correlated with disease progression of osteosarcoma

Energy Technology Data Exchange (ETDEWEB)

Wu, Junlong; Zhi, Liqiang; Dai, Xin; Cai, Qingchun; Ma, Wei, E-mail: doctormawei@163.com

2015-11-27

Human RecQ helicase family, consisting of RECQL, RECQL4, RECQL5, BLM and WRN, has critical roles in genetic stability and tumorigenesis. Although RECQL5 has been reported to correlate with the susceptibility to malignances including osteosarcoma, the specific effect on tumor genesis and progression is not yet clarified. Here we focused on the relationship between RECQL5 expression and osteosarcoma disease progression, and further investigated the function of RECQL5 on MG-63 cell proliferation and apoptosis. By immunohistochemical analysis, qRT-PCR and western blot, we found that RECQL5 expression was downregulated in osteosarcoma tissues and cells. Patients with advanced tumor stage and low grade expressed lower RECQL5. To construct a stable RECQL5 overexpression osteosarcoma cell line (MG-63-RECQL5), RECQL5 gene was inserted into the human AAVS1 safe harbor by CRISPR/Cas9 system. The overexpression of RECQL5 was verified by qRT-PCR and western blot. Cell proliferation, cell cycle and apoptosis assay revealed that RECQL5 overexpression inhibited proliferation, induced G1-phase arrest and promoted apoptosis in MG-63 cells. Collectively, our results suggested RECQL5 as a tumor suppressor in osteosarcoma and may be a potential therapeutic target for osteosarcoma treatment. - Highlights: • The expression of RECQL5 was downregulated in osteosarcoma tissues and cells. • Decreased RECQL5 correlated with osteosarcoma Enneking surgical classification. • We constructed a stable RECQL5 overexpression cell line by CRISPR/Cas9 system. • RECQL5 overexpression inhibited proliferation of MG-63 cells. • RECQL5 overexpression promoted apoptosis of MG-63 cells.

Express penetration of hydrogen on Mg(10͞13) along the close-packed-planes.

Science.gov (United States)

Ouyang, Liuzhang; Tang, Jiajun; Zhao, Yujun; Wang, Hui; Yao, Xiangdong; Liu, Jiangwen; Zou, Jin; Zhu, Min

2015-06-01

Metal atoms often locate in energetically favorite close-packed planes, leading to a relatively high penetration barrier for other atoms. Naturally, the penetration would be much easier through non-close-packed planes, i.e. high-index planes. Hydrogen penetration from surface to the bulk (or reversely) across the packed planes is the key step for hydrogen diffusion, thus influences significantly hydrogen sorption behaviors. In this paper, we report a successful synthesis of Mg films in preferential orientations with both close- and non-close-packed planes, i.e. (0001) and a mix of (0001) and (10͞13), by controlling the magnetron sputtering conditions. Experimental investigations confirmed a remarkable decrease in the hydrogen absorption temperature in the Mg (10͞13), down to 392 K from 592 K of the Mg film (0001), determined by the pressure-composition-isothermal (PCI) measurement. The ab initio calculations reveal that non-close-packed Mg(10͞13) slab is advantageous for hydrogen sorption, attributing to the tilted close-packed-planes in the Mg(10͞13) slab.

HRTEM characterization of melt-spun Al-Si-Cu-Mg alloys solidified at different rates

International Nuclear Information System (INIS)

Alfonso, Ismeli; Maldonado, Cuauhtemoc; Medina, Ariosto; Gonzalez, Gonzalo; Bejar, Luis

2006-01-01

Six quaternary alloys Al-6Si-3Cu-xMg (x = 0.59, 3.80 and 6.78 wt.%) were produced by melt spinning using two different tangential speeds of the copper wheel (30 and 45 ms -1 ), and characterized using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and microhardness. At 30 ms -1 , XRD and TEM investigations revealed the presence of Al 2 Cu (θ) for the alloy with 0.59%Mg and Al 5 Cu 2 Mg 8 Si 6 (Q) for the alloys with 3.80 and 6.78%Mg. The increase in microhardness of the alloys with higher Mg content is attributed to the presence of nanosized a-Al particles and a higher content of Q nanoparticles. At 45 ms -1 the alloying element content in solid solution is increased due to the fact that the quantity of free second phases (θ and Q nanoparticles) has decreased. For this rotation speed, amorphous regions of α -Al were observed, increasing microhardness compared to the 30 ms -1 ribbons

Effects of Be, Sr, Fe and Mg interactions on the microstructure and mechanical properties of aluminum based aeronautical alloys

Science.gov (United States)

Ibrahim, Mohamed Fawzy

The present work was carried out on a series of heat-treatable aluminum-based aeronautical alloys containing various amounts of magnesium (Mg), iron (Fe), strontium (Sr) and beryllium (Be). Tensile test bars (dendrite arm spacing ~ 24mum) were solutionized for either 5 or 12 hours at 540°C, followed by quenching in warm water (60°C). Subsequently, these quenched samples were aged at 160°C for times up to 12 hours. Microstructural assessment was performed. All heat-treated samples were pulled to fracture at room temperature using a servo-hydraulic tensile testing machine. The results show that Be causes partial modification of the eutectic silicon (Si) particles similar to that reported for Mg addition. Addition of 0.8 wt.% Mg reduced the eutectic temperature by ~10°C. During solidification of alloys containing high levels of Fe and Mg, without Sr, a peak corresponding to the formation of a Be-Fe phase (Al8Fe2BeSi) was detected at 611°C. The Be-Fe phase precipitates in a script-like morphology. A new quinary eutectic-like reaction was observed to take place near the end of solidification of high Mg, high Fe, Be-containing alloys. This new reaction is composed mainly of fine particles of Si, Mg2Si, pi-Al 8Mg3FeSi6 and (Be-Fe) phases. The volume fraction of this reaction decreased with the addition of Sr. The addition of Be has a noticeable effect on decreasing the beta-phase length, or volume fraction, this effect may be limited by adding Sr. Beryllium addition also results in the precipitation of the beta-phase in a nodular form, which reduces the harmful effects of these intermetallics on the alloy mechanical properties. Increasing both Mg and Fe levels led to an increase in the amount of the pi-phase; increasing the iron content led to an increase in the volume fraction of the partially soluble beta- and pi-phases, while Mg2Si particles were completely dissolved. The beta-phase platelets were observed to undergo changes in their morphology due to the

Decreased arachidonic acid content and metabolism in tissues of NZB/W F1 females fed a diet containing 0.45% dehydroisoandrosterone (DHA)

International Nuclear Information System (INIS)

Matsunaga, A.; Cottam, G.L.

1987-01-01

A diet containing 0.45% DHA fed to NZB/W mice, a model of systemic lupus erythematosus, delays the time of onset, improves survival and decreases the formation of antibodies to ds-DNA. Essential fatty acid-deficient diets or inclusion of eicosapentaenoic acid have similar beneficial effects and led them to investigate arachidonic acid metabolism in response to feeding DHA. The arachidonic acid content of plasma cholesteryl ester decreased from 37.4 +/- 2.2 to 28.2 +/- 1.3 mg%. In total liver phospholipid the value decreased from 18.1 +/- 0.52 to 13.7 +/- 1.3 mg%, in total kidney phospholipid the value decreased from 24.10 +/- 0.87 to 20.7 +/- 0.32 mg% and in resident peritoneal macrophages the value decreased from 15.4 +/- 4.6 to 3.6 +/- 1.4 mg%. The metabolism of exogenous [1- 14 C]arachidonic acid by resident peritoneal macrophages in response to Zymosan stimulation for 2 hr was examined by extraction of metabolites and separation by HPLC. Cells isolated from DHA-fed animals produced less PGE2 than controls, yet similar amounts of 6-keto PGF1α were produced. Arachidonic acid metabolites have significant effects on the immune system and may be a mechanism involved in the benefits obtained by inclusion of DHA in the diet

Effects of glucose doping on the MgB{sub 2} superconductors using cheap crystalline boron

Energy Technology Data Exchange (ETDEWEB)

Parakkandy, Jafar Meethale [Department of Physics and Astronomy, College of Science, PO Box 2455, King Saud University, Riyadh 11451,Saudi Arabia (Saudi Arabia); Shahabuddin, Mohammed, E-mail: mshahab@ksu.edu.sa [Department of Physics and Astronomy, College of Science, PO Box 2455, King Saud University, Riyadh 11451,Saudi Arabia (Saudi Arabia); Shah, M. Shahabuddin; Alzayed, Nasser S.; Qaid, Salem A.S.; Madhar, Niyaz Ahmad; Ramay, Shahid M. [Department of Physics and Astronomy, College of Science, PO Box 2455, King Saud University, Riyadh 11451,Saudi Arabia (Saudi Arabia); Shar, Muhammad Ali [Mechanical Engineering Department, College of Engineering, P.O. Box 800, King Saud University, Riyadh 11421 (Saudi Arabia)

2015-12-15

Highlights: • First report on glucose doped MgB{sub 2} superconductor by single step dry mixing approach. • Cheap crystalline boron used for the sample preparation. • Microstructure and superconducting properties of the superconductors are discussed. • Less degradation in low field critical current density observed. • MgB{sub 2} with 2 at. % glucose doped showed the highest J{sub c}, ≈ 2 × 10{sup 4}A/cm{sup 2} for 20 K at 3 T. - Abstract: We report the effect of glucose (C{sub 6}H{sub 12}O{sub 6}) doping on the structural and electromagnetic properties of MgB{sub 2} superconductor fabricated by dry mixing using planetary ball milling. Herein, as-prepared bulk polycrystalline Mg (B{sub 1–x}C{sub x}) {sub 2} samples with different doping levels (x = 0, 2, 4, and 6 at. %) were systematically studied by X-ray diffraction, magnetic and resistivity measurements, and microstructure analysis. When carbon doped, the reduction in critical transition temperature and shrinkage in a-lattice were obviously observed. This resulted in structural distortion of the MgB{sub 2} lattice, and thereby, enhanced an impurity scattering. In addition to these, upper critical field and high-field critical current densities were also enhanced. On the other hand, both pinning force and low-field critical current density are decreased. The high field enhancement and low field degradation are due to increase in impurity scattering and decrease in pinning force respectively.

Grain refining mechanism of Al-containing Mg alloys with the addition of Mn-Al alloys

International Nuclear Information System (INIS)

Qin, Gaowu W.; Ren Yuping; Huang Wei; Li Song; Pei Wenli

2010-01-01

Graphical abstract: Display Omitted Research highlights: The ε-AlMn phase acts as the heterogeneous nucleus of α-Mg phase during the solidification of the AZ31 Mg alloy, not the γ-Al 8 Mn 5 phase. The grain refinement effect is very clear with the addition of only 0.5 wt% Mn-28Al alloy (pure ε-AlMn). The grain refinement does not deteriorate up to the holding time of 60 min at 740 o C. - Abstract: The effect of manganese on grain refinement of Al-containing AZ31 Mg alloy has been investigated by designing a series of Mn-Al alloys composed of either pure ε-AlMn, γ 2 -Al 8 Mn 5 or both of them using optical microscopy and X-ray diffraction. It is experimentally clarified that the grain refinement of the AZ31 Mg alloy is due to the existence of the ε-AlMn phase in the Mn-Al alloys, not the γ 2 -Al 8 Mn 5 phase. The grain size of AZ31 Mg alloy is about 91 μm without any addition of Mn-Al alloys, but remarkably decreases to ∼55 μm with the addition of either Mn-34 wt% Al or Mn-28 wt% Al. With a minor addition of 0.5 wt% Mn-28Al alloy, the grain size of AZ31 alloy decreases to ∼53 μm, and the Mn-28Al alloy can be active as grain refiner for holding time up to 60 min for the melt AZ31 alloy at 750 o C.

Corrosion analysis of AlMg2 and AlMgSi using electrochemical method

International Nuclear Information System (INIS)

Dian A; Maman Kartaman; Rosika K; Yanlinastuti

2014-01-01

Corrosion test of cladding materials and structures of research reactor fuel, AlMgSi and AlMg2 have been performed in demineralized water of pH 2 and 6.7 using an electrochemical method. Corrosion phenomenon is affected by several factor such as composition and condition of solution. The purpose of this activity is to investigate the corrosion phenomena through the determination of the parameters of corrosion and polarization curve. The materials used are AlMg2 and AlMgSi alloy in circular dish shape with an area of 1 Cm"2. Preparation of the test sample is performed through several stages polishing, cleaning and drying procedures followed ASTM G3. The electrochemical method is done by measuring the open circuit potential (OCP), polarization resistance and potentiodynamic in demineralized water of pH 2 and pH 6.7 at temperature of 25°C. The results of the OCP is the corrosion potential (Ecorr) of AlMg2 and AlMgSi each of -906.1 mV and -619.8 mV at pH 2 and -868.6 and -756.7 mV at pH 6.7 mV. The results of measurements by polarization resistance technique showed that the corrosion rate of AlMg2 and AlMgSi in safe category (<2 mpy) at pH 6.7 and at pH 2 corrosion rate increased significantly, but still in the lightweight category (<20 mpy). Potentiodynamic curves showed that the passivation at pH 6.7 is very low while the passivation at pH 2 occurs within a relatively short range potential and followed events corroded. (author)

Aspirin decreases platelet uptake on Dacron vascular grafts in baboons

International Nuclear Information System (INIS)

Mackey, W.C.; Connolly, R.J.; Callow, A.D.

1984-01-01

The influence of a single dose of aspirin (5.4-7.4 mg/kg) on platelet uptake on 4-mm Dacron interposition grafts was studied in a baboon model using gamma camera scanning for 111-Indium labeled platelets. In vitro assessment of platelet function after aspirin administration revealed that in the baboon, as in the human, aspirin abolished arachidonic acid-induced platelet aggregation, prolonged the lag time between exposure to collagen and aggregation, and decreased plasma thromboxane B2 levels. Aspirin also prolonged the template bleeding time. Scans for 111-Indium labeled platelets revealed that pretreatment with a single dose of aspirin decreased platelet uptake on 4-mm Dacron carotid interposition grafts. This decrease in platelet uptake was associated with a significant improvement in 2-hour graft patency and with a trend toward improved 2-week patency

The influence of metal Mg on micro-morphology and crystallinity of spherical hexagonal boron nitride

Energy Technology Data Exchange (ETDEWEB)

Zhang, Ning, E-mail: zhangning5832@163.com; Liu, Huan; Kan, Hongmin; Wang, Xiaoyang; Long, Haibo; Zhou, Yonghui

2015-08-15

Highlights: • The action mechanism of Mg to the synthesis of spherical BN was explored. • The influence of Mg content on the crystallinity of h-BN powders was studied. • Even if not added any template, the spherical h-BN could be prepared. - Abstract: This search used the boric acid and borax as a source of boron, urea as a nitrogen source, Mg as metal catalyst, and thus prepared different micro-morphology and crystallinity hexagonal boron nitride powders under a flowing ammonia atmosphere at a nitriding temperature of 750 °C. The effect of Mg content on the crystallinity and micro-morphology of hexagonal boron nitride powders was studied, and the Mg action mechanism was explored. Without the added surfactant, the graphitization index (GI) was 6.87, and the diameter of the spherical h-BN was bigger. When the added Mg were 0.1 g, 0.3 g, 0.5 g and 0.7 g, the (GI) decreased to 6.04, 5.67, 4.62 and 4.84, respectively. When the Mg content was higher (0.9 g), GI value increased rapidly, and the crystallinity became bad. When the Mg content was 0.5 g, the dispersion of h-BN powders was at its optimum and refinement apparently, and the crystallinity at its highest.

The effect of Mg doping on the Raman spectra of LiNbO3 crystals

International Nuclear Information System (INIS)

Lengyel, K.; Kovacs, L.; Peter, A.; Polgar, K.; Corradi, G.; Bourson, P.

2007-01-01

LiNbO 3 :Mg crystals doped with 0-8 mol% Mg with stoichiometric, intermediate and congruent compositions were systematically investigated by Raman spectroscopy in backscattering y(zx)y and y(zz)y geometries. The halfwidths of E(TO 3 ) - E(TO 9 ) and A 1 (TO 1 ) - A 1 (TO 4 ) bands, which have a significant composition dependence for undoped LiNbO 3 crystals, show only weak Mg-concentration dependence below the photorefractive threshold. This is a consequence of the counteracting effect of the decreasing amount of Nb ions at Li-ion sites (Nb Li ) and increasing amount of Mg ions at Li-ion sites (Mg Li ). The halfwidths of these bands, however, increase linearly with growing Mg content for samples above the threshold, irrespective of the Li/Nb ratio. The same effect was observed in the Mg dependence of the position and halfwidth of the two-phonon band at about 689 - 705 cm -1 . The change in the Mg concentration dependence of these parameters at a given Li/Nb ratio determines the same threshold value as that concluded from IR and UV spectroscopic measurements. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

NMR relaxation rates and Knight shifts in MgB2 and AlB2: theory versus experiments

International Nuclear Information System (INIS)

Pavarini, E; Baek, S H; Suh, B J; Borsa, F; Bud'ko, S L; Canfield, P C

2003-01-01

We have performed 11 B NMR measurements in 11 B enriched MgB 2 powder sample in the normal phase. The Knight shift was accurately determined by using the magic angle spinning technique. Results for 11 B and 27 Al Knight shifts (K) and relaxation rates (1/T 1 ) are also reported for AlB 2 . The data show a dramatic decrease of both K and 1/T 1 for 11 B in AlB 2 with respect to MgB 2 . We compare experimental results with ab initio calculated NMR relaxation rates and Knight shifts. The experimental values for 1/T 1 and K are in most cases in good agreement with the theoretical results. We show that the decrease of K and 1/T 1 for 11 B is consistent with a drastic drop of the density of states at the boron site in AlB 2 with respect to MgB 2

Microstructure and in vitro degradation performance of Mg-Zn-Mn alloys for biomedical application.

Science.gov (United States)

Rosalbino, F; De Negri, S; Scavino, G; Saccone, A

2013-03-01

Manganese and zinc were selected as alloying elements to develop a Mg-based ternary alloy for biomedical applications, taking into account the good biocompatibility of these metals. The microstructures of Mg-Zn-Mn alloys containing 0.5 or 1.0 mass% of manganese and 1.0 or 1.5 mass% of zinc were investigated by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. Their corrosion properties were assessed by means of potentiodynamic polarization and electrochemical impedance spectroscopy measurements performed in Ringer's physiological solution that simulates bodily fluids. All tested samples are two-phase alloys formed by a Mg-based matrix, consisting of a Mg-Zn-Mn solid solution, and a Mg-Zn binary phase. The electrochemical results show an improvement of the corrosion behavior of the investigated alloys with increasing Zn and Mn content. This is attributed to the formation of a partially protective Mg(OH)(2) surface film whose protective capabilities are increased by the alloying elements. The reduced influence of the Mg-Zn intermetallic compound on the corrosion rate of Mg-Zn-Mn alloys in the presence of a partially protective surface layer can be ascribed to an increasing resistance between the Mg-Zn-Mn solid solution and the second phase, thereby decreasing the effective driving force for microgalvanic corrosion. Owing to its highest corrosion protective ability, the Mg-1.5Zn-1Mn alloy is a promising candidate for the development of degradable implants, such as screws, plates, and rods. Copyright © 2012 Wiley Periodicals, Inc.

Effect of film roughness in Fe/MgO/Fe magnetic tunnel junctions: model calculations

Energy Technology Data Exchange (ETDEWEB)

Edalati Boostan, Saeideh; Heiliger, Christian [I. Physikalisches Institut, Justus Liebig University Giessen, D-35392 (Germany); Moradi, Hosein [Department of Physics,Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)

2011-07-01

We calculate how interface roughness affects the tunneling magnetoresistance (TMR) in Fe/MgO/Fe (100) junctions. The used method is based on a single-band tight-binding (SBTB) approximation employing the Green's function formalism. We investigate the influence of disorder at the TMR ratio. Thereby, the disorder is modeled by considering different occupation probabilities of Fe and MgO at interface sites. We calculate the current densities for parallel and anti-parallel configurations for different disorders. The results show that the roughness decreases the TMR that match well with experimental observations.

Constraints on the ^22Ne(α,n)^25Mg reaction rate from ^natMg+n Total and ^25Mg(n,γ ) Cross Sections

Science.gov (United States)

Koehler, Paul

2002-10-01

The ^22Ne(α,n)^25Mg reaction is the neutron source during the s process in massive and intermediate mass stars as well as a secondary neutron source during the s process in low mass stars. Therefore, an accurate determination of this rate is important for a better understanding of the origin of nuclides heavier than iron as well as for improving s-process models. Also, because the s process produces seed nuclides for a later p process in massive stars, an accurate value for this rate is important for a better understanding of the p process. Because the lowest observed resonance in direct ^22Ne(α,n)^25Mg measurements is considerably above the most important energy range for s-process temperatures, the uncertainty in this rate is dominated by the poorly known properties of states in ^26Mg between this resonance and threshold. Neutron measurements can observe these states with much better sensitivity and determine their parameters much more accurately than direct ^22Ne(α,n)^25Mg measurements. I have analyzed previously reported Mg+n total and ^25Mg(n,γ ) cross sections to obtain a much improved set of resonance parameters for states in ^26Mg in this region, and an improved estimate of the uncertainty in the ^22Ne(α,n)^25Mg reaction rate. This work was supported by the U.S. DOE under contract No. DE-AC05-00OR22725 with UT-Battell, LLC.

Early intravenous ibuprofen decreases narcotic requirement and length of stay after traumatic rib fracture.

Science.gov (United States)

Bayouth, Lilly; Safcsak, Karen; Cheatham, Michael L; Smith, Chadwick P; Birrer, Kara L; Promes, John T

2013-11-01

Pain control after traumatic rib fracture is essential to avoid respiratory complications and prolonged hospitalization. Narcotics are commonly used, but adjunctive medications such as nonsteroidal anti-inflammatory drugs may be beneficial. Twenty-one patients with traumatic rib fractures treated with both narcotics and intravenous ibuprofen (IVIb) (Treatment) were retrospectively compared with 21 age- and rib fracture-matched patients who received narcotics alone (Control). Pain medication requirements over the first 7 hospital days were evaluated. Mean daily IVIb dose was 2070 ± 880 mg. Daily intravenous morphine-equivalent requirement was 19 ± 16 vs 32 ± 24 mg (P pain scores were lower in the Treatment group (P rib fractures significantly decreases narcotic requirement and results in clinically significant decreases in hospital length of stay. IVIb therapy should be initiated in patients with traumatic rib fractures to improve patient comfort and reduce narcotic requirement.

Preparation of Al-Mg Alloy Electrodes by Using Powder Metallurgy and Their Application for Hydrogen Production

Directory of Open Access Journals (Sweden)

Wen-Nong Hsu

2014-01-01

Full Text Available The choice of an electrode is the most critical parameter for water electrolysis. In this study, powder metallurgy is used to prepare aluminum-magnesium (Al-Mg alloy electrodes. In addition to pure Mg and Al electrodes, five Al-Mg alloy electrodes composed of Al-Mg (10 wt%, Al-Mg (25 wt%, Al-Mg (50 wt%, and Al-Mg (75 wt% were prepared. In water electrolysis experiments, the pure Al electrode exhibited optimal electrolytic efficiency. However, the Al-Mg (25 wt% alloy was the most efficient when the anticorrosion effect and materials costs were considered. In this study, an ultrasonic field was applied to the electrolysis cell to improve its efficiency. The results revealed that the current increased by approximately 23.1% when placed in a 30 wt% KOH solution under the ultrasonic field. Electrochemical polarization impedance spectroscopy (EIS was employed to evaluate the effect of the ultrasonic field on the reduction of polarization resistance. The results showed that the concentration impedance in the 30 wt% KOH electrolyte decreased markedly by 44%–51% Ω.

The effect of different dialyzer membrane on the clearance of serum β2-MG in maintenance hemodialysis patients

International Nuclear Information System (INIS)

Lu Yun; Xue Jun; Lin Xiangtong; Deng Shouzhen; Li Ding

2001-01-01

Objective: To investigate the effect of different membrane on the clearance of serum β 2 -MG in maintenance hemodialysis patients. Method: 106 maintenance hemodialysis patients randomized divided into group A and group B. Group A used cellulose triacetate membrane (N-130E), Group B used polysulfone membrane (F6). The levels of serum β 2 -MG before and after hemodialysis were compared in Group A and B, respectively. Results: Before hemodialysis, the level of serum β 2 -MG was not significant different between Group A and B (46.74 ± 19.46 mg/L vs 47.49 ± 16.71 mg/L, P>0.05). In Group A, compared with that before hemodialysis, the level of serum β 2 -MG after hemodialysis decreased significantly. (46.74±19.46 mg/L vs 39.76 ±17.66 mg/L, before HD vs after HD, P 2 -MG between before and after hemodialysis (47.49±16.71 mg/L vs 50.19±22.76 mg/L, P>0.05). Conclusion: N-130E dialyzer is better than F6 dialyzer as the effect of clearance serum β 2 -MG is concerned

Corrosion behaviour of Mg-Cu and Mg-Mo composites in 3.5% NaCl

International Nuclear Information System (INIS)

Budruk Abhijeet, S.; Balasubramaniam, R.; Gupta, M.

2008-01-01

The corrosion behaviour of pure magnesium, Mg-Cu (0.3, 0.6, and 1 vol.%) and Mg-Mo (0.1, 0.3, and 0.6 vol.%) composites has been studied in 3.5% NaCl solution by weight loss and polarisation methods. Corrosion rates determined by weight loss method were considerably higher than that determined by polarisation method. The corrosion rate increased with increasing volume fraction of reinforcement in Mg-Cu and Mg-Mo composites. At the same volume fraction of reinforcement, molybdenum reinforced composite corroded faster than copper reinforced composite. The galvanic current density between Mg-Cu and Mg-Mo couples has been experimentally measured using zero resistance ammeter technique. The experimentally observed galvanic current densities were in close agreement with those obtained using mixed potential theory analysis. SEM observation of corroded samples confirmed microgalvanic activity at the matrix/reinforcement interfaces. The poor corrosion resistance of composites has been attributed to microgalvanic effects between the matrix and reinforcements and inferior quality of surface films

Mg2+ Regulates Cytotoxic Functions of NK and CD8 T Cells in Chronic EBV Infection Through NKG2D

NARCIS (Netherlands)

Chaigne-Delalande, Benjamin; Li, Feng-Yen; O'Connor, Geraldine M.; Lukacs, Marshall J.; Jiang, Ping; Zheng, Lixin; Shatzer, Amber; Biancalana, Matthew; Pittaluga, Stefania; Matthews, Helen F.; Jancel, Timothy J.; Bleesing, Jack J.; Marsh, Rebecca A.; Kuijpers, Taco W.; Nichols, Kim E.; Lucas, Carrie L.; Nagpal, Sunil; Mehmet, Huseyin; Su, Helen C.; Cohen, Jeffrey I.; Uzel, Gulbu; Lenardo, Michael J.

2013-01-01

The magnesium transporter 1 (MAGT1) is a critical regulator of basal intracellular free magnesium (Mg2+) concentrations. Individuals with genetic deficiencies in MAGT1 have high levels of Epstein-Barr virus (EBV) and a predisposition to lymphoma. We show that decreased intracellular free Mg2+ causes

Effects of Mg Doping on the Performance of InGaN Films Made by Reactive Sputtering

Science.gov (United States)

Kuo, Dong-Hau; Li, Cheng-Che; Tuan, Thi Tran Anh; Yen, Wei-Chun

2015-01-01

Mg-doped InGaN (Mg-InGaN) films have been deposited directly on Si (100) substrates by radio-frequency reactive sputtering technique with single cermet targets in an Ar/N2 atmosphere. The cermet targets with a constant 5% indium content were made by hot pressing the mixture of metallic In, Ga, and Mg powders and ceramic GaN powder. The Mg-InGaN films had a wurtzite structure with a preferential () growth plane. The SEM images showed that Mg-InGaN films were smooth, continuous, free from cracks and holes, and composed of nanometer-sized grains. As the Mg dopant content in Mg-InGaN increased to 7.7 at.%, the film was directly transformed into p-type conduction without a post-annealing process. It had high hole concentration of 5.53 × 1018 cm-3 and electrical mobility of 15.7 ± 4.2 cm2 V-1 s-1. The over-doping of Mg in InGaN degraded the electrical properties. The bandgap of Mg-InGaN films decreased from 2.92 eV to 2.84 eV, as the Mg content increased from 7.7% to 18.2%. The constructed p-type Mg-InGaN/ n-type GaN diode was used to confirm the realization of the p-type InGaN by sputtering technique.

Phase diagrams of aluminium alloys of Al-Cu-Mg, Al-Mg-Si-Cu, and Al-Mg-Li system

International Nuclear Information System (INIS)

Ber, L.B.; Kaputkin, E.Ya.

2001-01-01

Isothermal diagrams of phase transformations (DPT) and temperature-time charts (TTC) of variation of electric conductivity and of mechanical features at tension were plotted following thermal treatment according to the pattern of direct hardening and ageing and according to the pattern of normal aging for D16 commercial alloy, Al-Cu-Mg model alloy of the same system, AD37 commercial alloys of Al-Mg-Si-Cu and 1424 one of Al-Li-Mg system. Phase transformations were studied by means of fluorescence electron microscopy, micro-X-ray spectral analysis, X-ray phase analysis of single crystals and polycrystals and differential scanning calorimetry. For every alloy comparison of TTC and DPT enables to clarity the mechanism of phase composition effect on features and to optimize conditions of hardening cooling and ageing [ru

Morphology, magnetic and resonance properties of Fe/MgO multilayers

Energy Technology Data Exchange (ETDEWEB)

Garcia-Garcia, A; Algarabel, P A; Ibarra, M R [Instituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza-CSIC 50009 Zaragoza (Spain); Vovk, A [Centro de Fisica da Materia Condensada Unversidade de Lisboa, Campo Grande Ed. C8, 1749-016, Lisboa (Portugal); Strichovanec, P; Pardo, J A; Magen, C [Instituto de Nanociencia de Aragon, Universidad de Zaragoza 50018 Zaragoza (Spain); Golub, V; Salyuk, O, E-mail: ayvovk@fc.ul.pt [Institute of Magnetism NAS of Ukraine, 36-b Vernnadsky blvd., 03142, Kyiv (Ukraine)

2011-07-06

Magnetic, resonance and transport properties of Fe(t nm)/MgO(3.0 nm) multilayers prepared by pulsed laser deposition were investigated. Comparison of the data allows conclusions on Fe layers morphology. For t<0.61 nm typical features of granular cermet films in dielectric regime are observed, i.e. high electrical resistance, isotropic magnetoresistance and strong temperature dependence of magnetization. For higher t coalescence of Fe granules occurs and metallic percolation cluster is formed at t{approx}0.81 nm. This is manifested by rapid decrease of films resistance and formation of multipeak ferromagnetic resonance spectra. For t>1.25 nm a continuous coverage of MgO by Fe takes place. However, the morphology of Fe layers is rough. This causes the appearance of magnetostatic resonance modes analogous to those observed for continuous films deposited on embossed surfaces.

The dependence of Raman scattering on Mg concentration in Mg-doped GaN grown by MBE

International Nuclear Information System (INIS)

Flynn, Chris; Lee, William

2014-01-01

Magnesium-doped GaN (GaN:Mg) films having Mg concentrations in the range 5 × 10 18 –5 × 10 20 cm −3 were fabricated by molecular beam epitaxy. Raman spectroscopy was employed to study the effects of Mg incorporation on the positions of the E 2 and A 1 (LO) lines identifiable in the Raman spectra. For Mg concentrations in excess of 2 × 10 19 cm −3 , increases in the Mg concentration shift both lines to higher wave numbers. The shifts of the Raman lines reveal a trend towards compressive stress induced by incorporation of Mg into the GaN films. The observed correlation between the Mg concentration and the Raman line positions establish Raman spectroscopy as a useful tool for optimizing growth of Mg-doped GaN. (papers)

S-I-N tunneling spectroscopy of MgB2 superconductor: evidence of two superconducting energy gaps

International Nuclear Information System (INIS)

Sen, Shashwati; Aswal, D.K.; Singh, Ajay; Gadkari, S.C.; Shah, K.; Gupta, S.K.; Sahni, V.C.

2002-01-01

The tunneling spectra of polycrystalline MgB 2 , have been recorded, at different temperatures between 29 K and T c , using planar superconductor- insulating-normal (S-I-N) tunneling spectroscopy. The planar S-I-N tunnel junctions have been fabricated by thermally evaporating Ag electrodes on MgB 2 surface. The naive layer, which forms at the surface of MgB 2 , due to atmospheric degradation, was employed as an insulating layer between Ag electrodes and MgB 2 . We have found presence of two clear superconducting energy gaps in MgB 2 . The magnitudes of these gaps at 29.5 K are 1.8 and 5.9 MeV, respectively. In the vicinity of T c , while larger energy gap obeyed BCS temperature dependence, the smaller energy gap deviated from BCS dependence. All the spectra exhibited zero-bias conductance, which decreased linearly with temperature and vanished at T c . (author)

Effect of Mg contents on the mechanical proprieties and precipitation kinetics in Al–3.3 wt.% Cu alloy

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Messaoud Fatmi

2018-01-01

Full Text Available The effect of additional Mg on the microstructure, mechanical properties, and transformation kinetics during aging in Al–3.3 wt.% Cu alloy was studied. The compositions and microstructure were examined by X-ray diffraction, Differential scanning calorimetry (DSC and scanning electron microscope (SEM with energy dispersive X-ray spectroscopy (EDS. The results show that the Mg in the Al–Cu alloy mainly precipitated to the grain boundaries during the process of transformation and formed a ternary Al2CuMg metallic compound and the rate of discontinuous precipitation reaction decreases with increasing concentration of Mg. The activation energy of crystallization was evaluated by applying the Kissinger equation.

Inhibitory effect of high [Mg2+] on the vasopressin-stimulated hydroosmotic permeability of the isolated perfused cortical collecting duct

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Falkenstein D.

1999-01-01

Full Text Available High magnesium concentration inhibits the effect of arginine vasopressin (AVP on smooth muscle contraction and platelet aggregation and also influences hepatocyte AVP receptor binding. The aim of this study was to determine the role of magnesium concentration [Mg2+] in AVP-stimulated water transport in the kidney collecting duct. The effect of low and high peritubular [Mg2+] on the AVP-stimulated osmotic water permeability coefficient (Pf was evaluated in the isolated perfused rabbit cortical collecting duct (CCD. Control tubules bathed and perfused with standard Ringer bicarbonate solution containing 1 mM Mg2+ presented a Pf of 223.9 ± 27.2 µm/s. When Mg2+ was not added to the bathing solution, an increase in the AVP-stimulated Pf to 363.1 ± 57.2 µm/s (P<0.05 was observed. An elevation of Mg2+ to 5 mM resulted in a decrease in Pf to 202.9 ± 12.6 µm/s (P<0.05. This decrease in the AVP-stimulated Pf at 5 mM Mg2+ persisted when the CCDs were returned to 1 mM Mg2+, Pf = 130.2 ± 20.3 µm/s, and was not normalized by the addition of 8-[4-chlorophenylthio]-adenosine 3',5'-cyclic monophosphate, a cAMP analogue, to the preparation. These data indicate that magnesium may play a modulatory role in the action of AVP on CCD osmotic water permeability, as observed in other tissues.

Applications of thermodynamic calculations to Mg alloy design: Mg-Sn based alloy development

International Nuclear Information System (INIS)

Jung, In-Ho; Park, Woo-Jin; Ahn, Sang Ho; Kang, Dae Hoon; Kim, Nack J.

2007-01-01

Recently an Mg-Sn based alloy system has been investigated actively in order to develop new magnesium alloys which have a stable structure and good mechanical properties at high temperatures. Thermodynamic modeling of the Mg-Al-Mn-Sb-Si-Sn-Zn system was performed based on available thermodynamic, phase equilibria and phase diagram data. Using the optimized database, the phase relationships of the Mg-Sn-Al-Zn alloys with additions of Si and Sb were calculated and compared with their experimental microstructures. It is shown that the calculated results are in good agreement with experimental microstructures, which proves the applicability of thermodynamic calculations for new Mg alloy design. All calculations were performed using FactSage thermochemical software. (orig.)

In vitro degradation and electrochemical corrosion evaluations of microarc oxidized pure Mg, Mg-Ca and Mg-Ca-Zn alloys for biomedical applications.

Science.gov (United States)

Pan, Yaokun; He, Siyu; Wang, Diangang; Huang, Danlan; Zheng, Tingting; Wang, Siqi; Dong, Pan; Chen, Chuanzhong

2015-02-01

Calcium phosphate (CaP) ceramic coatings were fabricated on pure magnesium (Mg) and self-designed Mg-0.6Ca, Mg-0.55Ca-1.74Zn alloys by microarc oxidation (MAO). The coating formation, growth and biomineralization mechanisms were discussed. The coating degradability and bioactivity were evaluated by immersion tests in trishydroxymethyl-aminomethane hydrochloric acid (Tris-HCl) buffer and simulated body fluid (SBF) solutions, respectively. The coatings and corrosion products were characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS) and fourier transform infrared spectrometer (FT-IR). The electrochemical workstation was used to investigate the electrochemical corrosion behaviors of substrates and coatings. Results showed that Mg-0.55Ca-1.74Zn alloy exhibits the highest mechanical strength and electrochemical corrosion resistance among the three alloys. The MAO-coated Mg-0.55Ca-1.74Zn alloy has the potential to be served as a biodegradable implant. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis, crystal growth and structure of Mg containing β-rhombohedral boron: MgB17.4

International Nuclear Information System (INIS)

Adasch, Volker; Hess, Kai-Uwe; Ludwig, Thilo; Vojteer, Natascha; Hillebrecht, Harald

2006-01-01

For the first time, single crystals of Mg containing β-rhombohedral boron MgB 17.4 were synthesised from the elements in a Mg/Cu melt at 1600deg. C. The crystal structure determined by the refinement of single crystal data (space group R-3m, a=10.991(2)A, c=24.161(4)A, 890 reflections, 123 variables, R 1 (F)=0.049, wR 2 (I)=0.122) improves and modifies the former structure model derived from earlier investigations on powder samples. Mg is located on four different positions with partial occupation. While the occupation of the sites D (53.3%), E (91%) and F (7.2%) is already known from other boron-rich borides related to β-rhombohedral boron, the occupation of the fourth position (18h, 6.7%) is observed for the first time. Two boron positions show partial occupation. The summation reveals the composition MgB 17.4 and Mg 5.85 B 101.9 , respectively, confirmed by WDX measurements. The single crystals of MgB 17.4 show the highest Mg content ever found. Preliminary measurements indicate no superconductivity

Influences of arc current on composition and properties of MgO thin films prepared by cathodic vacuum arc deposition

International Nuclear Information System (INIS)

Zhu Daoyun; Zheng Changxi; Wang Mingdong; Liu Yi; Chen Dihu; He Zhenhui; Wen Lishi; Cheung, W.Y.

2010-01-01

MgO thin films with high optical transmittances (more than 90%) were prepared by cathodic vacuum arc deposition technique. With the increase of arc current from 40 to 80 A, the deposition pressure decreases and the film thickness increases; the atomic ratio of Mg/O in MgO thin films (obtained by RBS) increases from 0.97 to 1.17, giving that deposited at 50 A most close to the stoichiometric composition of the bulk MgO; the grains of MgO thin films grow gradually as shown in SEM images. XRD patterns show that MgO (1 1 0) orientation is predominant for films prepared at the arc currents ranged from 50 to 70 A. The MgO (1 0 0) orientation is much enhanced and comparable to that of MgO (1 1 0) for films prepared at the arc current of 80 A. The secondary electron emission coefficient of MgO thin film increases with arc current ranged from 50 to 70 A.

Accuracy of genetic code translation and its orthogonal corruption by aminoglycosides and Mg2+ ions.

Science.gov (United States)

Zhang, Jingji; Pavlov, Michael Y; Ehrenberg, Måns

2018-02-16

We studied the effects of aminoglycosides and changing Mg2+ ion concentration on the accuracy of initial codon selection by aminoacyl-tRNA in ternary complex with elongation factor Tu and GTP (T3) on mRNA programmed ribosomes. Aminoglycosides decrease the accuracy by changing the equilibrium constants of 'monitoring bases' A1492, A1493 and G530 in 16S rRNA in favor of their 'activated' state by large, aminoglycoside-specific factors, which are the same for cognate and near-cognate codons. Increasing Mg2+ concentration decreases the accuracy by slowing dissociation of T3 from its initial codon- and aminoglycoside-independent binding state on the ribosome. The distinct accuracy-corrupting mechanisms for aminoglycosides and Mg2+ ions prompted us to re-interpret previous biochemical experiments and functional implications of existing high resolution ribosome structures. We estimate the upper thermodynamic limit to the accuracy, the 'intrinsic selectivity' of the ribosome. We conclude that aminoglycosides do not alter the intrinsic selectivity but reduce the fraction of it that is expressed as the accuracy of initial selection. We suggest that induced fit increases the accuracy and speed of codon reading at unaltered intrinsic selectivity of the ribosome.

Microstructure and Mechanical Properties of Ultrasonic Spot Welded Mg/Al Alloy Dissimilar Joints

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He Peng

2018-04-01

Full Text Available Lightweight structural applications of magnesium and aluminum alloys inevitably necessitate welding and joining, especially dissimilar welding between these alloys. The objective of this study was to examine the feasibility of joining ZEK100 Mg alloy to Al6022 alloy via ultrasonic spot welding, focusing on effects of welding energy. An interface diffusion layer consisting of α-Mg and Al12Mg17 eutectic structure was observed to form, with its thickness increased from ~0.5 µm to ~30 µm with increasing welding energy from 500 J to 2000 J. The tensile lap shear peak load or strength and critical stress intensity of the welded joints first increased and then decreased with increasing welding energy, with their peak values achieved at 750 J. Fatigue life of the joints made at 750 J and 2000 J was equivalent at the lower cyclic loading levels, while it was longer for the joints made at 750 J at the higher cyclic loading levels. Fatigue fracture mode changed from interfacial failure to mainly transverse-through-thickness crack growth with decreasing cyclic loading level, which corresponded well to the bi-linear characteristic of S-N curves. Crack initiation basically occurred at the weld nugget border and at the interface between the two sheets, which can be understood via a theoretical stress analysis.

Effect of sterilization process on surface characteristics and biocompatibility of pure Mg and MgCa alloys

International Nuclear Information System (INIS)

Liu, X.L.; Zhou, W.R.; Wu, Y.H.; Cheng, Y.; Zheng, Y.F.

2013-01-01

The aim of this work was to investigate the effect of various sterilization methods on surface characteristics and biocompatibility of MgCa alloy, with pure Mg as a comparison, including steam autoclave sterilization (SA), ethylene oxide steam sterilization (EO), glutaraldehyde sterilization (GD), dry heat sterilization (DH) and Co60 γ ray radiation sterilization (R) technologies. The surface characterizations were performed by environmental scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, grazing incidence X-ray diffraction, water contact angle and surface free energy measurement, whereas the cytotoxicity and hemocompatibility were evaluated by cellular adhesive experiment, platelet adhesion and hemolysis test. The results showed that the five sterilization processes caused more changes on the surface of MgCa alloy than that on the surface of pure Mg. The GD sterilization caused the most obvious changes on the surface of the pure Mg, and the SA sterilization made the largest alteration on the MgCa alloy surface. The GD and DH sterilization processes could cause increases on surface free energy for both pure Mg and MgCa alloys, while the other three sterilization processes reduced the surface free energy. The DH and GD sterilization processes caused the least alteration on the cell adhesion on pure Mg surface, whereas the EO sterilization performed the greatest impact on the cell adhesion on the Mg–Ca alloy surface. The hemolysis percentage of pure Mg and MgCa alloys were reduced by SA sterilization, meanwhile the other four sterilization processes increased their hemolysis percentages significantly, especially for the EO sterilization. - Highlights: • The effect of sterilization on surface chemistry and biocompatibility was studied. • Sterilization caused more surface changes on MgCa alloy than pure Mg. • Co60 γ ray radiation is the most appropriate sterilization process

Pressure-induced structural change in MgSiO3 glass at pressures near the Earth's core-mantle boundary.

Science.gov (United States)

Kono, Yoshio; Shibazaki, Yuki; Kenney-Benson, Curtis; Wang, Yanbin; Shen, Guoyin

2018-02-20

Knowledge of the structure and properties of silicate magma under extreme pressure plays an important role in understanding the nature and evolution of Earth's deep interior. Here we report the structure of MgSiO 3 glass, considered an analog of silicate melts, up to 111 GPa. The first (r1) and second (r2) neighbor distances in the pair distribution function change rapidly, with r1 increasing and r2 decreasing with pressure. At 53-62 GPa, the observed r1 and r2 distances are similar to the Si-O and Si-Si distances, respectively, of crystalline MgSiO 3 akimotoite with edge-sharing SiO 6 structural motifs. Above 62 GPa, r1 decreases, and r2 remains constant, with increasing pressure until 88 GPa. Above this pressure, r1 remains more or less constant, and r2 begins decreasing again. These observations suggest an ultrahigh-pressure structural change around 88 GPa. The structure above 88 GPa is interpreted as having the closest edge-shared SiO 6 structural motifs similar to those of the crystalline postperovskite, with densely packed oxygen atoms. The pressure of the structural change is broadly consistent with or slightly lower than that of the bridgmanite-to-postperovskite transition in crystalline MgSiO 3 These results suggest that a structural change may occur in MgSiO 3 melt under pressure conditions corresponding to the deep lower mantle.

Formation of Multiple-Phase Catalysts for the Hydrogen Storage of Mg Nanoparticles by Adding Flowerlike NiS.

Science.gov (United States)

Xie, Xiubo; Ma, Xiujuan; Liu, Peng; Shang, Jiaxiang; Li, Xingguo; Liu, Tong

2017-02-22

In order to enhance the hydrogen storage properties of Mg, flowerlike NiS particles have been successfully prepared by solvothermal reaction method, and are subsequently ball milled with Mg nanoparticles (NPs) to fabricate Mg-5 wt % NiS nanocomposite. The nanocomposite displays Mg/NiS core/shell structure. The NiS shell decomposes into Ni, MgS and Mg 2 Ni multiple-phases, decorating on the surface of the Mg NPs after the first hydrogen absorption and desorption cycle at 673 K. The Mg-MgS-Mg 2 Ni-Ni nanocomposite shows enhanced hydrogenation and dehydrogenation rates: it can quickly uptake 3.5 wt % H 2 within 10 min at 423 K and release 3.1 wt % H 2 within 10 min at 573 K. The apparent hydrogen absorption and desorption activation energies are decreased to 45.45 and 64.71 kJ mol -1 . The enhanced sorption kinetics of the nanocomposite is attributed to the synergistic catalytic effects of the in situ formed MgS, Ni and Mg 2 Ni multiple-phase catalysts during the hydrogenation/dehydrogenation process, the porthole effects for the volume expansion and microstrain of the phase transformation of Mg 2 Ni and Mg 2 NiH 4 and the reduced hydrogen diffusion distance caused by nanosized Mg. This novel method of in situ producing multiple-phase catalysts gives a new horizon for designing high performance hydrogen storage material.

Mixed conductivity in La(Ga,Mg,NbO3-δ Perovskites

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Marques, F. M. B.

1999-12-01

Full Text Available Solid-solution formation has been found in the perovskite-type system LaGa0.85-xMg0.15(Nb0.33Mg0.66xO3-δ (x = 0 - 0.20. Increasing dopant concentration leads to lower oxygen ionic conductivity and, at temperatures above 1000 K, higher p-type electronic conductivity. Oxygen-ion transference numbers in air were determined to vary in the range 0.78 to 0.96, decreasing with increasing x and temperature. Thermal expansion coefficients of ceramic samples of LaGa0.85-xMg0.15(Nb0.33Mg0.66xO3-δ were calculated in a temperature range of 300 to 1100 K to be essentially independent of composition, varying in the range (10.0 ± 0.2 x 10-6 K-1. Values of the activation energy for the total electrical conductivity in air are 104-106 kJ/mol in the temperature range 670 - 1000 K and 67 - 76 kJ/mol in the temperature range 1000 - 1200 K. The method of synthesis was found to affect both the symmetry of the perovskite unit cell and phase composition. The presence of second phases led to a dramatic decrease in conductivity.Se ha encontrado la formación de una solución sólida en el sistema LaGa0.85-xMg0.15(Nb0.33Mg0.66xO3-δ (x = 0 - 0.20. Un aumento de la concentración de dopante lleva a una menor conductividad iónica de oxígeno y a temperaturas superiores a 1000 K, una mayor conductividad electrónica de tipo p. El número de transferencia del ión oxígeno en aire fue determinado y varía en el rango 0.78 a 0.96 disminuyendo con el aumento de x y de la temperatura. El coeficiente de expansión térmico de las muestras cerámicas de LaGa0.85-xMg0.15(Nb0.33Mg0.66xO3-δ fue calculado en el rango de temperatura de 300 a 1100 k siendo independiente de la composición, y variando en el rango (10.0 ± 0.2 x 10-6 K-1. Los valores de la energía de activación para la conductividad eléctrica total en aire son 104-106 KJ/mol en el rango de temperatura 670-1000 K y 67-76 kJ/mol en el rango de temperaturas 1000-1200 K. Se encontró que el método de síntesis afecta

Nanocontainer-Enhanced Self-Healing for Corrosion-Resistant Ni Coating on Mg Alloy.

Science.gov (United States)

Xie, Zhi-Hui; Li, Dan; Skeete, Zakiya; Sharma, Anju; Zhong, Chuan-Jian

2017-10-18

The ability to manipulate the functionalization of Ni coating is of great importance in improving the corrosion resistance of magnesium (Mg) alloy for many industrial applications. In the present work, MCM-41 type mesoporous silica nanocontainers (MSNs) loaded with corrosion inhibitor (NaF) were synthesized and employed as smart reinforcements to enhance the integrity and corrosion inhibition of the Ni coating. The incorporation of the F-loaded MSNs (F@MSNs) to enhance the corrosion resistant capacity of a metallic coating is reported for the first time. The mesoporous structures of the as-prepared MSNs and F@MSNs were confirmed by transmission electron microscopy (TEM), small angle X-rays scattering (SAXS), and N 2 adsorption-desorption isotherms. The X-ray photoelectron spectroscopy (XPS) data demonstrated the successful immobilization of fluoride ion on the MSNs and formation of a magnesium fluoride (MgF 2 ) protective film at the corrosion sites of the Mg alloy upon soaking in a F@MSNs-containing NaCl solution. The results from potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) for both bare Mg alloy and Ni coatings with and without F@MSNs have revealed a clear decrease in corrosion rate in a corrosive solution for a long-time immersion due to the introduction of F@MSNs. These findings open new opportunities in the exploration of self-healing metallic coatings for highly enhanced anticorrosion protection of Mg alloy.

HYDROXYUREA TREATMENT DECREASES GLOMERULAR HYPERFILTRATION IN CHILDREN WITH SICKLE CELL ANEMIA

Science.gov (United States)

Aygun, Banu; Mortier, Nicole A.; Smeltzer, Matthew P.; Shulkin, Barry L.; Hankins, Jane S.; Ware, Russell E.

2015-01-01

Background Glomerular hyperfiltration and microalbuminuria/proteinuria are early manifestations of sickle nephropathy. The effects of hydroxyurea therapy on these renal manifestations of sickle cell anemia (SCA) are not well defined. Objective To investigate the effects of hydroxyurea on glomerular filtration rate (GFR) measured by 99mTc-DTPA clearance, and on microalbuminuria/proteinuria in children with SCA. Study Design Hydroxyurea Study of Long-Term Effects (HUSTLE) is a prospective study (NCT00305175) with the goal of describing the long-term cellular, molecular, and clinical effects of hydroxyurea therapy in SCA. Glomerular filtration rate, urine microalbumin, and serum cystatin C were measured before initiating hydroxyurea therapy and then repeated after 3 years. Baseline and Year 3 values for HUSTLE subjects were compared using the Wilcoxon Signed Rank test. Associations between continuous variables were evaluated using Spearman correlation coefficient. Results Twenty-three children with SCA (median age 7.5 years, range 2.5–14.0 years) received hydroxyurea at maximum tolerated dose (MTD, 24.4 ± 4.5 mg/kg/day, range 15.3–30.6 mg/kg/day). After three years of treatment, GFR measured by 99mTc-DTPA decreased significantly from 167 ± 46 mL/min/1.73m2 to 145 ± 27 mL/min/1.73m2 (p=0.016). This decrease in GFR was significantly associated with increase in fetal hemoglobin (p= 0.042) and decrease in lactate dehydrogenase levels (p=0.035). Urine microalbumin and cystatin C levels did not change significantly. Conclusions Hydroxyurea at MTD is associated with a decrease in hyperfiltration in young children with SCA. PMID:23255310

Enhanced superconducting properties of MgB2 by carbon substitution using carbon containing nano additives

International Nuclear Information System (INIS)

Devadas, K.M.; Varghese, Neson; Vinod, K.; Rahul, S.; Thomas, Syju; Anooja, J.B.; Syamaprasad, U.; Sundaresan, A.; Roy, S.B.

2010-01-01

A comparative study on the effect of doping of nano carbon, nano diamond and nano SiC in MgB 2 is carried out. The J c (H) is significantly enhanced for all doped samples compared to the pure sample among which MgB 1.9 C 0.1 (nano C) exhibits the best J c (H) performance. The enhanced performance is due to the effective substitution of C at B site which is confirmed by the systematic decrease in both α axis and T c . (author)

A study on preparation and hydriding of β-Mg2Al3 and γ-Mg17Al12

International Nuclear Information System (INIS)

Hadi Suwarno

2009-01-01

The mechanism of the synthetic formation of β-Mg 2 Al 3 and γ-Mg 17 Al 12 has been studied. Mechanical alloying of Mg and Al powders with the atomic ratio of Mg:Al = 2:3 in toluene solution yields β-Mg 2 Al 3 compound after milling for 30 h. The γ-Mg 17 Al 12 can be formed by heating the β-Mg 2 Al 3 at 430°C under high vacuum. The measured hydrogen capacities of β-Mg 2 Al 3 and γ-Mg 17 Al 12 as hydride at 300°C are 3.2 and 4.9 wt%, respectively. Microstructure of the Mg-Al specimen shows that on hydriding at 300°C the polygonal shape of the γ-Mg 17 Al 12 changes into irregular shapes which are composed of γ-MgH 2 and Al. (author)

Solid-liquid stable phase equilibria of the ternary systems MgCl2 + MgB6O10+ H2O AND MgSO4 + MgB6O10 + H2O at 308.15 K

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Lingzong Meng

2014-03-01

Full Text Available The solubilities and the relevant physicochemical properties of the ternary systems MgCl2 + MgB6O10 + H2O and MgSO4 + MgB6O10 + H2O at 308.15 K were investigated using an isothermal dissolution method. It was found that there is one invariant point, two univariant curves, and two crystallization regions of the systems. The systems belong to a simple co-saturated type, and neither double salts nor solid solutions were found. Based on the extended HW model and its temperature-dependent equations, the single-salt Pitzer parameters β(0, β(1, β(2 and CØ for MgCl2, MgSO4, and Mg(B6O7(OH6, the mixed ion-interaction parameters θCl,B6O10, θSO4,B6O10, ΨMg,Cl,B6O10, ΨMg,SO4,B6O10 of the systems at 308.15 K were fitted, In addition, the average equilibrium constants of the stable equilibrium solids at 308.15 K were obtained by a method using the activity product constant. Then the solubilities of the ternary systems are calculated. The calculated solubilities agree well with the experimental values.

Single dose (400 mg) versus 7 day (200 mg) daily dose itraconazole in the treatment of tinea versicolor: a randomized clinical trial.

Science.gov (United States)

Wahab, M A; Ali, M E; Rahman, M H; Chowdhury, S A; Monamie, N S; Sultana, N; Khondoker, L

2010-01-01

Tinea (pityriasis) versicolor is a superficial fungal infection and one of the most commonly found pigmentary disorders of skin caused by the yeast Malassezia. Multiple topical as well as systemic therapies are available for treatment. Systemic therapies are used for extensive disease, frequent relapse or where topical agents have failed. The aim that translates the rationale of the study was to compare the efficacy, safety, tolerability and cost effectiveness of single dose 400mg versus 7 day 200 mg daily dose of itraconazole in the treatment of tinea versicolor. A clinical study was done to compare the efficacy of single dose (400 mg) of itraconazole and 7 day 200 mg daily dose of itraconazole in the treatment of extensive tinea versicolor. Total 60 patients (aged 18-50 years) were selected for the study during the period of June 2007 to May 2008 in the department of Dermatology of three different hospitals in Bangladesh. Cases having with extensive involvement, diagnosed clinically and confirmed by wood's lamp and KOH microscopy were taken. Patients were randomly allocated into equal groups. Group A was given single dose 400 mg itraconazole and Group B was given 7 day 200 mg daily itraconazole. Fifty three (88%) male and 7(12%) female were included in the study. The mean age of group A was 32.37+/-9 years and in group B 33.23+/-8 years. The mean duration of the disease in group A was 2.63+/-2 months and 2.76+/-2 months in group B. In group A clinical responders was found cure 22(73.33%) and improvement 5(16.33%) and in group B it was found cure 24(79.99%) and improvement 4(13.33%). The measure at the End point (EP1) equals to 90% response and in-group B it was found cure 24 (79.99%) and improvement 4(13.33%). (Here the End point EP2) equals to 93.33%. The EP clinical analysis however shows 91.66% response. Both single dose and 7 day daily dose of itraconazole can be effective in the treatment of tinea versicolor with extensive involvement but single dose appears

Cuprizone decreases intermediate and late-stage progenitor cells in hippocampal neurogenesis of rats in a framework of 28-day oral dose toxicity study

International Nuclear Information System (INIS)

Abe, Hajime; Tanaka, Takeshi; Kimura, Masayuki; Mizukami, Sayaka; Saito, Fumiyo; Imatanaka, Nobuya; Akahori, Yumi; Yoshida, Toshinori; Shibutani, Makoto

2015-01-01

Developmental exposure to cuprizone (CPZ), a demyelinating agent, impairs intermediate-stage neurogenesis in the hippocampal dentate gyrus of rat offspring. To investigate the possibility of alterations in adult neurogenesis following postpubertal exposure to CPZ in a framework of general toxicity studies, CPZ was orally administered to 5-week-old male rats at 0, 120, or 600 mg/kg body weight/day for 28 days. In the subgranular zone (SGZ), 600 mg/kg CPZ increased the number of cleaved caspase-3 + apoptotic cells. At ≥ 120 mg/kg, the number of SGZ cells immunoreactive for TBR2, doublecortin, or PCNA was decreased, while that for SOX2 was increased. In the granule cell layer, CPZ at ≥ 120 mg/kg decreased the number of postmitotic granule cells immunoreactive for NEUN, CHRNA7, ARC or FOS. In the dentate hilus, CPZ at ≥ 120 mg/kg decreased phosphorylated TRKB + interneurons, although the number of reelin + interneurons was unchanged. At 600 mg/kg, mRNA levels of Bdnf and Chrna7 were decreased, while those of Casp4, Casp12 and Trib3 were increased in the dentate gyrus. These data suggest that CPZ in a scheme of 28-day toxicity study causes endoplasmic reticulum stress-mediated apoptosis of granule cell lineages, resulting in aberrations of intermediate neurogenesis and late-stage neurogenesis and following suppression of immediate early gene-mediated neuronal plasticity. Suppression of BDNF signals to interneurons caused by decreased cholinergic signaling may play a role in these effects of CPZ. The effects of postpubertal CPZ on neurogenesis were similar to those observed with developmental exposure, except for the lack of reelin response, which may contribute to a greater decrease in SGZ cells. - Highlights: • Effect of 28-day CPZ exposure on hippocampal neurogenesis was examined in rats. • CPZ suppressed intermediate neurogenesis and late-stage neurogenesis in the dentate gyrus. • CPZ suppressed BDNF signals to interneurons by decrease of cholinergic

Cuprizone decreases intermediate and late-stage progenitor cells in hippocampal neurogenesis of rats in a framework of 28-day oral dose toxicity study

Energy Technology Data Exchange (ETDEWEB)

Abe, Hajime; Tanaka, Takeshi; Kimura, Masayuki; Mizukami, Sayaka [Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509 (Japan); Pathogenetic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu-shi, Gifu 501-1193 (Japan); Saito, Fumiyo; Imatanaka, Nobuya; Akahori, Yumi [Chemicals Evaluation and Research Institute, Japan, 1-4-25 Koraku, Bunkyo-ku, Tokyo 112-0004 (Japan); Yoshida, Toshinori [Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509 (Japan); Shibutani, Makoto, E-mail: mshibuta@cc.tuat.ac.jp [Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509 (Japan)

2015-09-15

Developmental exposure to cuprizone (CPZ), a demyelinating agent, impairs intermediate-stage neurogenesis in the hippocampal dentate gyrus of rat offspring. To investigate the possibility of alterations in adult neurogenesis following postpubertal exposure to CPZ in a framework of general toxicity studies, CPZ was orally administered to 5-week-old male rats at 0, 120, or 600 mg/kg body weight/day for 28 days. In the subgranular zone (SGZ), 600 mg/kg CPZ increased the number of cleaved caspase-3{sup +} apoptotic cells. At ≥ 120 mg/kg, the number of SGZ cells immunoreactive for TBR2, doublecortin, or PCNA was decreased, while that for SOX2 was increased. In the granule cell layer, CPZ at ≥ 120 mg/kg decreased the number of postmitotic granule cells immunoreactive for NEUN, CHRNA7, ARC or FOS. In the dentate hilus, CPZ at ≥ 120 mg/kg decreased phosphorylated TRKB{sup +} interneurons, although the number of reelin{sup +} interneurons was unchanged. At 600 mg/kg, mRNA levels of Bdnf and Chrna7 were decreased, while those of Casp4, Casp12 and Trib3 were increased in the dentate gyrus. These data suggest that CPZ in a scheme of 28-day toxicity study causes endoplasmic reticulum stress-mediated apoptosis of granule cell lineages, resulting in aberrations of intermediate neurogenesis and late-stage neurogenesis and following suppression of immediate early gene-mediated neuronal plasticity. Suppression of BDNF signals to interneurons caused by decreased cholinergic signaling may play a role in these effects of CPZ. The effects of postpubertal CPZ on neurogenesis were similar to those observed with developmental exposure, except for the lack of reelin response, which may contribute to a greater decrease in SGZ cells. - Highlights: • Effect of 28-day CPZ exposure on hippocampal neurogenesis was examined in rats. • CPZ suppressed intermediate neurogenesis and late-stage neurogenesis in the dentate gyrus. • CPZ suppressed BDNF signals to interneurons by decrease of

Effect of the third element on the structure of liquid Mg{sub 65}Cu{sub 25}Y{sub 10} alloy

Energy Technology Data Exchange (ETDEWEB)

Liu, Dan [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan 250061 (China); Weihai Wanfeng Magnesium Industry Science and Technology Development Co. Ltd., Weihai 264209 (China); Zhu, Xun Ming [Weihai Wanfeng Magnesium Industry Science and Technology Development Co. Ltd., Weihai 264209 (China); Qin, Jing Yu, E-mail: qinjy@sdu.edu.cn [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan 250061 (China); Duan, Jun Peng; Wang, Ai Min [Weihai Wanfeng Magnesium Industry Science and Technology Development Co. Ltd., Weihai 264209 (China); Gu, Ting Kun [School of Electrical Engineering, Shandong University, Jinan 250061 (China)

2016-08-12

The liquid structures of Mg{sub 65}Cu{sub 25}Y{sub 10} and its three homologous binary liquid alloys are investigated via ab initio molecular dynamics in the present work. The chemical and topological environments in all four liquid alloys are analyzed using pair distribution function, coordination number, and the Voronoi polyhedron. It shows that the Cu atoms play significant role in deciding the chemical and topological short-range orders of the Mg{sub 65}Cu{sub 25}Y{sub 10} liquid alloy. The Voronoi polyhedra in the ternary liquid alloy illustrate less varieties and longer lifetime. Moreover, the diffusion coefficients are decreased significantly in the ternary liquid alloys according to the mean square displacements. All above offer a deeper insight into how the three species work in the Mg{sub 65}Cu{sub 25}Y{sub 10} liquid alloy. - Highlights: • Cu plays crucial role in Mg{sub 65}Cu{sub 25}Y{sub 10}'s chemical and topological SROs. • Additive elements decrease varieties and prolong lifetimes of Voronoi polyhedra. • Additive elements hinder the diffusion of Mg and Y efficiently.

Impact of diagenesis and low grade metamorphosis on Triassic sabkha dolomite δ26Mg

Science.gov (United States)

Immenhauser, A.; Geske, A.; Richter, D.; Buhl, D.; Niedermayr, A.

2012-12-01

Dolomite is a common rock forming mineral in the geological record but its value as archive of ancient seawater δ26Mg signatures and their variations in time are at present underexplored. Unknown factors include the sensitivity of δ26Mg ratio to processes in the diagenetic and low grade metamorphic domain. Here, we document and discusses the first detailed δ26Mg data set from early diagenetic and burial dolomites. Samples come from the Upper Triassic Hauptdolomit (Dolomia Principale; The Dolomites, Italy) and include coeval dolmicrites that underwent differential burial diagenesis in a temperature range between about 100 and more than 350°C. As indicated by dolmicrite 87/86Sr ratios, sabkha calcian D1 dolomites precipitated from evaporated seawater and stabilized at an early diagenetic stage to D2 dolomites analysed here. With increasing burial temperature, dolomite δ26Mg ratio scatter in the data set decreases with increasing Mg/Ca ratio and degree of order. Specifically, δ26Mg ratio variability is reduced from ~0.7‰ at burial temperatures beneath 100°C to about ~0.2‰ at temperatures in excess of 350°C, respectively, with mean δ26Mg values ranging constantly near -1.9‰. This suggests that, at least for the rock buffered system investigated here, dolmicrite δ26Mg proxy data are conservative and preserve near pristine values even at elevated burial temperatures. At present, the main element of uncertainty is the Mg-isotope fractionation factor between (evaporated) seawater and dolomite. A possible solution to this problem includes the compilation of a data from modern sabkha environments including pore water and calcian dolomite δ26Mg isotope signatures.

Mg-enriched erythrite from Bou Azzer, Anti-Atlas Mountains, Morocco: geochemical and spectroscopic characteristics

Science.gov (United States)

Dumańska-Słowik, Magdalena; Pieczka, Adam; Natkaniec-Nowak, Lucyna; Kunecki, Piotr; Gaweł, Adam; Heflik, Wiesław; Smoliński, Wojciech; Kozub-Budzyń, Gabriela

2018-06-01

Supergene Mg-enriched erythrite, with an average composition (Co2.25Mg0.58Ni0.14Fe0.04Mn0.02 Zn0.02) (As1.97PMorocco. The unit cell parameters of monoclinic Mg-enriched erythrite [space group C2/ m, a = 10.252(2) Å, b = 13.427(3) Å, c = 4.757(3) Å, ß = 105.12(1)°] make the mineral comparable with erythrite from other localities. The composition of the sample represents the solid solution between erythrite, hörnesite and annabergite, that is, the nearest to the endmember erythrite. However, Mg-enriched erythrite forming the crystal exhibits variable compositions, especially in Mg and Co contents, with Mg increasing from 0.32 up to 1.39 apfu, and Co decreasing from 2.53 to 1.50 apfu, which manifests in the fine compositional oscillatory zoning. It is the highest content of Mg in erythrite structure reported so far. The most intensive Raman active ν3 and ν1 bands, recorded for the crystal's zones with maximum Mg contents, occur at 865 and 800 cm- 1 and are shifted towards higher wavenumbers, where normally hörnesite Raman bands appear. The characteristic oscillatory zoning texture results from varying contents of main and trace elements mobilized from the host ores (Co arsenides, mainly skutterudite) and rock-forming minerals (among others, dolomite) by the solutions in the oxidation zone of the ore deposits. The heating of the Mg-enriched erythrite up to 1000 °C leads to the crystallization of the water-free (Co,Mg)3(AsO4)2 phase.

Structural and optical properties of ZnMgO nanostructures formed by Mg in-diffused ZnO nanowires

International Nuclear Information System (INIS)

Pan, C.-J.; Hsu, H.-C.; Cheng, H.-M.; Wu, C.-Y.; Hsieh, W.-F.

2007-01-01

ZnMgO nanostructures with wurtzite phase were prepared by thermal diffusion of Mg into the ZnO nanowires. As ZnO light-emitting devices have been operated by using ZnMgO layers as energy barrier layers to confine the carriers, it is essential to realize the characterization of ZnMgO particularly. In this work, the Mg content in Zn 1 -x Mg x O alloy determined by X-ray diffraction (XRD) and photoluminescence (PL) shows a good coincidence. The variation of lattice constant and the blueshift of near-band-edge emission indicate that Zn 2+ ions are successfully substituted by Mg 2+ ions in the ZnO lattice. In Raman-scattering studies, the change of E 2 (high) phonon line shape in ZnO:Mg nanostructures reveals the microscopic substitutional disorder. In addition to the host phonons of ZnO, two additional bands around 383 and 510 cm -1 are presumably attributed to the Mg-related vibrational modes. - Graphical abstract: We reported the synthesis of the ZnMgO nanostructures prepared by a simple vapor transport method. Magnesium-related anomalous modes are observed by Raman spectra for the first time in ZnMgO system

A comparative study of Mg and Pt contacts on semi-insulating GaAs: Electrical and XPS characterization

Energy Technology Data Exchange (ETDEWEB)

Dubecký, F., E-mail: elekfdub@savba.sk [Institute of Electrical Engineering, SAS, Dúbravská cesta 9, Bratislava, SK-84104 (Slovakia); Kindl, D.; Hubík, P. [Institute of Physics CAS, v.v.i., Cukrovarnická 10, CZ-16200 Prague (Czech Republic); Mičušík, M. [Polymer Institute, SAS, Dúbravská cesta 9, Bratislava, SK-84541 (Slovakia); Dubecký, M. [Department of Physics, Faculty of Science, University of Ostrava, 30. dubna 22, CZ-70103 Ostrava 1 (Czech Republic); Boháček, P.; Vanko, G. [Institute of Electrical Engineering, SAS, Dúbravská cesta 9, Bratislava, SK-84104 (Slovakia); Gombia, E. [IMEM-CNR, Parco area delle Scienze 37/A, Parma, I-43010 (Italy); Nečas, V. [Faculty of Electrical Engineering and Information Technology, SUT, Ilkovičova 3, Bratislava, SK-81219 (Slovakia); Mudroň, J. [Department of Electronics, Academy of Armed Forces, Demänová 393, Liptovský Mikuláš, SK-03106 (Slovakia)

2017-02-15

Highlights: • Explored were diodes with full-area low/high work function metal contacts on semi-insulating GaAs (S). • The Mg-S-Mg diode is promising for radiation detectors for its low high-field current. • The XPS analysis of Mg-S interface shows presence of MgO instead of Mg metal. - Abstract: We present a comparative study of the symmetric metal-SI GaAs-metal (M-S-M) diodes with full-area contacts on both device sides, in order to demonstrate the effect of contact metal work function in a straightforward way. We compare the conventional high work function Pt contact versus the less explored low work function Mg contact. The Pt-S-Pt, Mg-S-Mg and mixed Mg-S-Pt structures are characterized by the current-voltage measurements, and individual Pt-S and Mg-S contacts are investigated by the X-ray photoelectron spectroscopy (XPS). The transport measurements of Mg-S-Pt structure show a significant current decrease at low bias while the Mg-S-Mg structure shows saturation current at high voltages more than an order of magnitude lower with respect to the Pt-S-Pt reference. The phenomena observed in Mg-containing samples are explained by the presence of insulating MgO layer at the M-S interface, instead of the elementary Mg, as confirmed by the XPS analysis. Alternative explanations of the influence of MgO layer on the effective resistance of the structures are presented. The reported findings have potential applications in M-S-M sensors and radiation detectors based on SI GaAs.

Transesterification of palm oil on K{sub y}Mg{sub 1} {sub -} {sub x}Zn{sub 1} {sub +} {sub x}O{sub 3} catalyst: Effect of Mg-Zn interaction

Energy Technology Data Exchange (ETDEWEB)

Olutoye, M.A.; Hameed, B.H. [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

2010-06-15

The Mg-Zn interaction effect of K{sub y}Mg{sub 1} {sub -} {sub x}Zn{sub 1} {sub +} {sub x}O{sub 3} heterogeneous type catalyst and its performance on transesterification of palm oil have been studied using the response surface methodology and the factorial design of experiments. The catalyst was synthesized using the co-precipitation method and the activity was assessed by transesterification of palm oil into fatty acid methyl esters. The ratio of the Mg/Zn metal interaction, temperature and time of calcination were found to have positive influence on the conversion of palm oil to fatty acid methyl ester (FAME) with the effect of metal to metal ratio and temperature of calcination being more significant. The catalytic activity was found to decrease at higher calcination temperature and the catalyst type K{sub 2}Mg{sub 0.34}Zn{sub 1.66}O{sub 3} with Mg/Zn ratio of 4.81 gave FAME content of 73% at a catalyst loading of 1.404 wt.% of oil with molar ratio of methanol to oil being 6:1 at temperature of 150 C in 6 h. A regression model was obtained to predict conversions to methyl esters as a function of metal interaction ratio, temperature of calcination and time. The observed activity of the synthesized catalyst was due to its synergetic structure and composition. (author)

Grain refining mechanism of Al-containing Mg alloys with the addition of Mn-Al alloys

Energy Technology Data Exchange (ETDEWEB)

Qin, Gaowu W., E-mail: qingw@smm.neu.edu.c [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Wenhu Road 3-11, Heping District, Shenyang 110004, Liaoning Province (China); Ren Yuping; Huang Wei; Li Song; Pei Wenli [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Wenhu Road 3-11, Heping District, Shenyang 110004, Liaoning Province (China)

2010-10-08

Graphical abstract: Display Omitted Research highlights: The {epsilon}-AlMn phase acts as the heterogeneous nucleus of {alpha}-Mg phase during the solidification of the AZ31 Mg alloy, not the {gamma}-Al{sub 8}Mn{sub 5} phase. The grain refinement effect is very clear with the addition of only 0.5 wt% Mn-28Al alloy (pure {epsilon}-AlMn). The grain refinement does not deteriorate up to the holding time of 60 min at 740 {sup o}C. - Abstract: The effect of manganese on grain refinement of Al-containing AZ31 Mg alloy has been investigated by designing a series of Mn-Al alloys composed of either pure {epsilon}-AlMn, {gamma}{sub 2}-Al{sub 8}Mn{sub 5} or both of them using optical microscopy and X-ray diffraction. It is experimentally clarified that the grain refinement of the AZ31 Mg alloy is due to the existence of the {epsilon}-AlMn phase in the Mn-Al alloys, not the {gamma}{sub 2}-Al{sub 8}Mn{sub 5} phase. The grain size of AZ31 Mg alloy is about 91 {mu}m without any addition of Mn-Al alloys, but remarkably decreases to {approx}55 {mu}m with the addition of either Mn-34 wt% Al or Mn-28 wt% Al. With a minor addition of 0.5 wt% Mn-28Al alloy, the grain size of AZ31 alloy decreases to {approx}53 {mu}m, and the Mn-28Al alloy can be active as grain refiner for holding time up to 60 min for the melt AZ31 alloy at 750 {sup o}C.

Hydrogen absorption kinetics and structural properties of Mg85Ni10Ca5 and Mg90Ni10

International Nuclear Information System (INIS)

Aoki, Masakazu; Saito, Katsushi; Towata, Shin-ichi

2005-01-01

Mg 85 Ni 10 Ca 5 and Mg 90 Ni 10 were prepared by melting mixtures of the elements in mild steel crucibles and pouring them into copper molds. Hydrogen absorption kinetics and structural properties of the alloys were characterized by the volumetric method using a Sievert's apparatus, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The crystallite size of Mg in Mg 85 Ni 10 Ca 5 , which is evaluated by XRD peak broadening, is about 50% smaller than that in Mg 90 Ni 10 . In addition, the nanometer-scale structure composed of Mg, Mg 2 Ni, Mg 2 Ca was observed in Mg 85 Ni 10 Ca 5 . Mg 85 Ni 10 Ca 5 shows better hydrogen absorption kinetics than Mg 90 Ni 10 in the temperature range of room temperature to 573 K. The better absorption kinetics of Mg 85 Ni 10 Ca 5 is mainly attributed to the nanometer-scale structure

Enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers by inhibiting Ta diffusion

Energy Technology Data Exchange (ETDEWEB)

Li, Xu-Jing; Jiang, Shao-Long; Zhang, Jing-Yan; Liu, Qian-Qian; Liu, Yi-Wei; Zhao, Jian-Cheng [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Wu, Zheng-Long [Analytical and Testing Center, Beijing Normal University, Beijing 100875 (China); Feng, Chun, E-mail: fengchun@ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Li, Ming-Hua [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Yu, Guang-Hua, E-mail: ghyu@mater.ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)

2016-03-01

Graphical abstract: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis have been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation to some extent due to the oxygen deficit MgO{sub x} (x < 1), and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent during the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (K{sub CoFeB/MgO}). As a result, the perpendicular magnetic anisotropy at high annealing temperatures was maintained. - Highlights: • High annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers was realized. • X-ray photoelectron spectroscopy analysis has been performed to explore the reasons. • The prevention of Ta diffusion was realized by introducing Mg at the CoFeB/MgO interface. - Abstracts: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis has been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation, and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent in the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (KCoFeB/MgO). As a result, the perpendicular magnetic anisotropy at high annealing temperatures is maintained.

Interplay of Rashba effect and spin Hall effect in perpendicular Pt/Co/MgO magnetic multilayers

Institute of Scientific and Technical Information of China (English)

赵云驰; 杨光; 董博闻; 王守国; 王超; 孙阳; 张静言; 于广华

2016-01-01

The interplay of the Rashba effect and the spin Hall effect originating from current induced spin–orbit coupling was investigated in the as-deposited and annealed Pt/Co/MgO stacks with perpendicular magnetic anisotropy. The above two effects were analyzed based on Hall measurements under external magnetic fields longitudinal and vertical to dc current, respectively. The coercive field as a function of dc current in vertical mode with only the Rashba effect involved decreases due to thermal annealing. Meanwhile, spin orbit torques calculated from Hall resistance with only the spin Hall effect involved in the longitudinal mode decrease in the annealed sample. The experimental results prove that the bottom Pt/Co interface rather than the Co/MgO top one plays a more critical role in both Rashba effect and spin Hall effect.

The Evaluation of Damage Effects on MgO Added Concrete with Slag Cement Exposed to Calcium Chloride Deicing Salt

Science.gov (United States)

Jang, Jae-Kyeong; Kim, Hong-Gi; Kim, Jun-Hyeong

2018-01-01

Concrete systems exposed to deicers are damaged in physical and chemical ways. In mitigating the damage from CaCl2 deicers, the usage of ground slag cement and MgO are investigated. Ordinary Portland cement (OPC) and slag cement are used in different proportions as the binding material, and MgO in doses of 0%, 5%, 7%, and 10% are added to the systems. After 28 days of water-curing, the specimens are immersed in 30% CaCl2 solution by mass for 180 days. Compressive strength test, carbonation test, chloride penetration test, chloride content test, XRD analysis, and SEM-EDAX analysis are conducted to evaluate the damage effects of the deicing solution. Up to 28 days, plain specimens with increasing MgO show a decrease in compressive strength, an increase in carbonation resistance, and a decrease in chloride penetration resistance, whereas the S30- and S50- specimens show a slight increase in compressive strength, an increase in carbonation resistance, and a slight increase in chloride penetration resistance. After 180 days of immersion in deicing solution, specimens with MgO retain their compressive strength longer and show improved durability. Furthermore, the addition of MgO to concrete systems with slag cement induces the formation of magnesium silicate hydrate (M-S-H) phases. PMID:29758008

The Evaluation of Damage Effects on MgO Added Concrete with Slag Cement Exposed to Calcium Chloride Deicing Salt.

Science.gov (United States)

Jang, Jae-Kyeong; Kim, Hong-Gi; Kim, Jun-Hyeong; Ryou, Jae-Suk

2018-05-14

Concrete systems exposed to deicers are damaged in physical and chemical ways. In mitigating the damage from CaCl₂ deicers, the usage of ground slag cement and MgO are investigated. Ordinary Portland cement (OPC) and slag cement are used in different proportions as the binding material, and MgO in doses of 0%, 5%, 7%, and 10% are added to the systems. After 28 days of water-curing, the specimens are immersed in 30% CaCl₂ solution by mass for 180 days. Compressive strength test, carbonation test, chloride penetration test, chloride content test, XRD analysis, and SEM-EDAX analysis are conducted to evaluate the damage effects of the deicing solution. Up to 28 days, plain specimens with increasing MgO show a decrease in compressive strength, an increase in carbonation resistance, and a decrease in chloride penetration resistance, whereas the S30- and S50- specimens show a slight increase in compressive strength, an increase in carbonation resistance, and a slight increase in chloride penetration resistance. After 180 days of immersion in deicing solution, specimens with MgO retain their compressive strength longer and show improved durability. Furthermore, the addition of MgO to concrete systems with slag cement induces the formation of magnesium silicate hydrate (M-S-H) phases.

Effect of strontium on the grain refining efficiency of Mg-3Al alloy refined by carbon inoculation

International Nuclear Information System (INIS)

Du Jun; Yang Jian; Kuwabara, Mamoru; Li Wenfang; Peng Jihua

2009-01-01

The effect of Sr on the grain refining efficiency of the Mg-3Al alloy refined by carbon inoculation has been investigated in the present study. A significant grain refinement was obtained for the Mg-3Al alloy treated with either 0.2% C or 0.2% Sr. The Al-C-O particles were found in the sample refined by 0.2% C, and the element O should come from reaction between Al 4 C 3 nuclei of Mg grains and water during the process of sample preparation. The grain size of the sample refined by carbon inoculation was further decreased after the combined addition of Sr. The grain size decreased with increasing Sr content. Much higher refining efficiency was obtained when the Sr addition was increased to 0.5%. Sr is an effective element to improve the grain refining efficiency for the Mg-Al alloys refined by carbon inoculation. The number of Al 4 C 3 particles in the sample refined by the combination of carbon and Sr was more than that in the sample refined by only carbon. No Al-C-O-Sr-rich particles were obviously found in the sample refined by the combination of carbon and a little (<0.5%) Sr addition

Cryogenic milling for the fabrication of high J{sub c} MgB{sub 2} bulk superconductors

Energy Technology Data Exchange (ETDEWEB)

Kim, D. N.; Kang, M. O.; Park, H. W. [Korea University of Technology and Education, Cheonan (Korea, Republic of); Jun, B. H.; Kim, C. J. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2017-06-15

Cryogenic milling which is a combined process of low-temperature treatment and mechanical milling was applied to fabricate high critical current density (J{sub c}) MgB{sub 2} bulk superconductors. Liquid nitrogen was used as a coolant, and no solvent or lubricant was used. Spherical Mg (6-12 μm, 99.9 % purity) and plate-like B powder (⁓ 1 μm, 97 % purity) were milled simultaneously for various time periods (0, 2, 4, 6 h) at a rotating speed of 500 rpm using ZrO{sub 2} balls. The (Mg{sup +2B}) powders milled were pressed into pellets and heat-treated at 700°C for 1 h in flowing argon. The use of cryomilled powders as raw materials promoted the formation reaction of superconducting MgB{sub 2}, reduced the grain size of MgB{sub 2}, and suppressed the formation of impurity MgO. The superconducting critical temperature (T{sub c}) of MgB{sub 2} was not influenced as the milling time (t) increased up to 6 h. Meanwhile, the critical current density (J{sub c}) of MgB{sub 2} increased significantly when t increased to 4 h. When t increased further to 6 h, however, Jc decreased. The J{sub c} enhancement of MgB{sub 2} by cryogenic milling is attributed to the formation of the fine grain MgB{sub 2} and a suppression of the MgO formation.

In vivo and in vitro degradation comparison of pure Mg, Mg-10Gd and Mg-2Ag: a short term study

Directory of Open Access Journals (Sweden)

I Marco

2017-02-01

Full Text Available The purpose of this study was to compare short term in vitro and in vivo biodegradation studies with low purity Mg (> 99.94 %, Mg-10Gd and Mg-2Ag designed for biodegradable implant applications. Three in vitro testing conditions were applied, using (i phosphate buffered saline (PBS, (ii Hank’s balanced salt solution (HBSS and (iii Dulbecco’s modified eagle medium (DMEM in 5 % CO2 under sterile conditions. Gas evolution and mass loss (ML were assessed, as well as the degradation layer, by elemental mapping and scanning electron microscopy (SEM. In vivo, implantations were performed on male Sprague-Dawley rats evaluating both, gas cavity volume and implant volume reduction by micro-computed tomography (µCT, 7 d after implantation. Samples were produced by casting, solution heat treatment and extrusion in disc and pin shape for the in vitro and in vivo experiments, respectively. Results showed that when the processing of the Mg sample varied, differences were found not only in the alloy impurity content and the grain size, but also in the corrosion behaviour. An increase of Fe and Ni or a large grain size seemed to play a major role in the degradation process, while the influence of alloying elements, such as Gd and Ag, played a secondary role. Results also indicated that cell culture conditions induced degradation rates and degradation layer elemental composition comparable to in vivo conditions. These in vitro and in vivo degradation layers consisted of Mg hydroxide, Mg-Ca carbonate and Ca phosphate.

The response of soil and stream chemistry to decreases in acid deposition in the Catskill Mountains, New York, USA

Science.gov (United States)

McHale, Michael; Burns, Douglas A.; Siemion, Jason; Antidormi, Michael

2017-01-01

The Catskill Mountains have been adversely impacted by decades of acid deposition, however, since the early 1990s, levels have decreased sharply as a result of decreases in emissions of sulfur dioxide and nitrogen oxides. This study examines trends in acid deposition, stream-water chemistry, and soil chemistry in the southeastern Catskill Mountains. We measured significant reductions in acid deposition and improvement in stream-water quality in 5 streams included in this study from 1992 to 2014. The largest, most significant trends were for sulfate (SO42−) concentrations (mean trend of −2.5 μeq L−1 yr−1); hydrogen ion (H+) and inorganic monomeric aluminum (Alim) also decreased significantly (mean trends of −0.3 μeq L−1 yr−1 for H+ and −0.1 μeq L−1 yr−1 for Alim for the 3 most acidic sites). Acid neutralizing capacity (ANC) increased by a mean of 0.65 μeq L−1 yr−1 for all 5 sites, which was 4 fold less than the decrease in SO42−concentrations. These upward trends in ANC were limited by coincident decreases in base cations (−1.3 μeq L−1 yr−1 for calcium + magnesium). No significant trends were detected in stream-water nitrate (NO3−) concentrations despite significant decreasing trends in NO3− wet deposition. We measured no recovery in soil chemistry which we attributed to an initially low soil buffering capacity that has been further depleted by decades of acid deposition. Tightly coupled decreasing trends in stream-water silicon (Si) (−0.2 μeq L−1 yr−1) and base cations suggest a decrease in the soil mineral weathering rate. We hypothesize that a decrease in the ionic strength of soil water and shallow groundwater may be the principal driver of this apparent decrease in the weathering rate. A decreasing weathering rate would help to explain the slow recovery of stream pH and ANC as well as that of soil base cations.

Supplementation of xanthophylls increased antioxidant capacity and decreased lipid peroxidation in hens and chicks.

Science.gov (United States)

Gao, Yu-Yun; Xie, Qing-Mei; Ma, Jing-Yun; Zhang, Xiang-Bin; Zhu, Ji-Mei; Shu, Ding-Ming; Sun, Bao-Li; Jin, Ling; Bi, Ying-Zuo

2013-03-28

The present study investigated the effects of xanthophyll supplementation on production performance, antioxidant capacity (measured by glutathione peroxidase, superoxide dismutase (SOD), catalase, total antioxidant capacity (T-AOC), and reduced glutathione:oxidised glutathione ratio (GSH:GSSG)) and lipid peroxidation (measured by malondialdehyde (MDA)) in breeding hens and chicks. In Expt 1, 432 hens were fed diets supplemented with 0 (control group), 20 or 40 mg xanthophyll/kg diet. Blood samples were taken at 7, 14, 21, 28 and 35 d of the trial. Liver and jejunal mucosa were sampled at 35 d. Both xanthophyll groups improved serum SOD at 21 and 28 d, serum T-AOC at 21 d and liver T-AOC, and serum GSH:GSSG at 21, 28 and 35 d and liver GSH:GSSG. Xanthophylls also decreased serum MDA at 21 d in hens. Expt 2 was a 2 × 2 factorial design. Male chicks hatched from 0 or 40 mg in ovo xanthophyll/kg diet of hens were fed a diet containing either 0 or 40 mg xanthophyll/kg diet. Liver samples were collected at 0, 7, 14 and 21 d after hatching. Blood samples were also collected at 21 d. In ovo-deposited xanthophylls increased antioxidant capacity and decreased MDA in the liver mainly within 1 week after hatching. Maternal effects gradually vanished during 1-2 weeks after hatching. Dietary xanthophylls increased antioxidant capacity and decreased MDA in the liver and serum mainly from 2 weeks onwards. Data suggested that xanthophyll supplementation enhanced antioxidant capacity and reduced lipid peroxidation in different tissues of hens and chicks.

Respiratory outcomes following 100 mg/kg v. 200 mg/kg of poractant ...

African Journals Online (AJOL)

In keeping with current evidence, the initial dose of poractant alpha was increased from 100 mg/kg to 200 mg/kg. e outcomes of newborns requiring treatment with surfactant before and aer this change were reviewed. Methods. Electronic clinical records were reviewed of infants admitted to ACH who received surfactant ...

Mg/Ca ratio in fertilization and agricultural soils, Mg percent of liming ...

African Journals Online (AJOL)

Strong increase of NPK (nitrogen, phosphorus and potassium) in mineral fertilization (fm) included relative delay in Mg supplementation and dilution in plant available silicon (Si) via recycled nutrients (rcl). (Silicon is not included in essential fertilizers in Finland.) Methods: We have assessed old data on Ca and Mg in ...

Enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers by inhibiting Ta diffusion

International Nuclear Information System (INIS)

Li, Xu-Jing; Jiang, Shao-Long; Zhang, Jing-Yan; Liu, Qian-Qian; Liu, Yi-Wei; Zhao, Jian-Cheng; Wu, Zheng-Long; Feng, Chun; Li, Ming-Hua; Yu, Guang-Hua

2016-01-01

Graphical abstract: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis have been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation to some extent due to the oxygen deficit MgO_x (x < 1), and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent during the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (K_C_o_F_e_B_/_M_g_O). As a result, the perpendicular magnetic anisotropy at high annealing temperatures was maintained. - Highlights: • High annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers was realized. • X-ray photoelectron spectroscopy analysis has been performed to explore the reasons. • The prevention of Ta diffusion was realized by introducing Mg at the CoFeB/MgO interface. - Abstracts: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis has been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation, and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent in the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (KCoFeB/MgO). As a result, the perpendicular magnetic anisotropy at high annealing temperatures is maintained

Investigations on structural, vibrational and dielectric properties of nanosized Cu doped Mg-Zn ferrites

Energy Technology Data Exchange (ETDEWEB)

Yadav, Anand [School of Physics, Vigyan Bhavan, Devi Ahilya University, Khandwa Road Campus, Indore 452001 (India); Department of Physics, MEDICAPS Institute of Science and Technology, Pithampur 453331 (India); Rajpoot, Rambabu; Dar, M. A.; Varshney, Dinesh, E-mail: vdinesh33@rediffmail.com, E-mail: anand.212@gmail.com [School of Physics, Vigyan Bhavan, Devi Ahilya University, Khandwa Road Campus, Indore 452001 (India)

2016-05-23

Transition metal Cu{sup 2+} doped Mg-Zn ferrite [Mg{sub 0.5}Zn{sub 0.5-x}Cu{sub x}Fe{sub 2}O{sub 4} (0.0 ≤ x ≤ 0.5)] were prepared by sol gel auto combustion (SGAC) method to probe the structural, vibrational and electrical properties. X-ray diffraction (XRD) pattern reveals a single-phase cubic spinel structure without the presence of any secondary phase corresponding to other structure. The average particle size of the parent Mg{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} is found to be ~29.8 nm and is found to increase with Cu{sup 2+} doping. Progressive reduction in lattice parameter of Mg{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} has been observed due to difference in ionic radii of cations with improved Cu doping. Spinel cubic structure is further confirmed by Raman spectroscopy. Small shift in Raman modes towards higher wave number has been observed in doped Mg-Zn ferrites. The permittivity and dielectric loss decreases at lower doping and increases at higher order doping of Cu{sup 2+}.

Effects of Ce concentrations on ignition temperature and surface tension of Mg-9wt.%Al alloy

Directory of Open Access Journals (Sweden)

Deng Zhenghua

2013-03-01

Full Text Available Magnesium alloys are well known for their excellent properties, but the potential issues with oxidation and burning during melting and casting largely limit its industrial applications. The addition of Ce in magnesium alloys can significantly raise ignition-proof performance and change the structure of the oxide film on the surface of the molten metal as well as the surface tension values. Surface tension is an important physical parameter of the metal melts, and it plays an important role in the formation of surface oxide film. In this present work, the ignition temperature and the surface tension of Mg-9wt.%Al alloy with different Ce concentrations were studied. Surface tensions was measured using the maximum bubble pressure method (MBPM. Ignition temperature was measured using NiCr-NiSi type thermocouples and was monitored and recorded via a WXT-604 desk recording device. The results show that the ignition point of Mg-9wt.%Al alloy can be effectively elevated by adding Ce. The ignition temperature reaches its highest point of 720 ℃ when the addition of Ce is 1wt.%. The surface tension of the molten Mg-9wt.%Al alloy decreases exponentially with the increase of Ce addition at the same temperature. Similarly, the experiment also shows that the surface tension of Mg-9wt.%Al alloy decreases exponentially with the increase of temperature.

Site preference of Mg acceptors and improvement of p-type doping efficiency in nitride alloys.

Science.gov (United States)

Park, Ji-Sang; Chang, K J

2013-06-19

We perform first-principles density functional calculations to investigate the effect of Al and In on the formation energy and acceptor level of Mg in group-III nitride alloys. Our calculations reveal a tendency for the Mg dopants to prefer to occupy the lattice sites surrounded with Al atoms, whereas hole carriers are generated in In- or Ga-rich sites. The separation of the Mg dopants and hole carriers is energetically more favourable than a random distribution of dopants, being attributed to the local bonding effect of weak In and strong Al potentials in alloys. As a consequence, the Mg acceptor level, which represents the activation energy of Mg, tends to decrease with increasing numbers of Al next-nearest neighbours, whereas it increases as the number of In next-nearest neighbours increases. Based on the results, we suggest that the incorporation of higher Al and lower In compositions will improve the p-type doping efficiency in quaternary alloys, in comparison with GaN or AlGaN ternary alloys with similar band gaps.

Structural and optical properties of magnetron sputtered Mg{sub x}Zn{sub 1-x}O thin films

Energy Technology Data Exchange (ETDEWEB)

Kumar, Sanjeev; Gupte, Vinay; Sreenivas, K [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India)

2006-04-05

Mg{sub x}Zn{sub 1-x}O (MZO) thin films prepared by an rf magnetron sputtering technique are reported. The films were grown at room temperature and at relatively low rf power of 50 W. MZO thin films were found to possess preferred c-axis orientation and exhibited hexagonal wurtzite structure of ZnO up to a Mg concentration of 42 mol%. A small variation in the c-axis lattice parameter of around 0.3% was observed with increasing Mg composition, showing the complete solubility of Mg in ZnO. The band gap of the MZO films in the wurtzite phase varied linearly with the Mg concentration and a maximum band gap {approx}4.19 eV was achieved at x = 0.42. The refractive indices of the MgO films were found to decrease with increasing Mg content. The observed optical dispersion data are in agreement with the single oscillator model. A photoluminescence study revealed a blue shift in the near band edge emission peak with increasing Mg content in the MZO films. The results show the potential of MZO films in various opto-electronic applications.

Microstructure and magnetic properties of FeCo epitaxial thin films grown on MgO single-crystal substrates

International Nuclear Information System (INIS)

Shikada, Kouhei; Ohtake, Mitsuru; Futamoto, Masaaki; Kirino, Fumiyoshi

2009-01-01

FeCo epitaxial films were prepared on MgO(100), MgO(110), and MgO(111) substrates by ultrahigh vacuum molecular beam epitaxy. FeCo thin films with (100), (211), and (110) planes parallel to the substrate surface grow on respective MgO substrates. FeCo/MgO interface structures are studied by high-resolution cross-sectional transmission electron microscopy and the epitaxial growth mechanism is discussed. Atomically sharp boundaries are recognized between the FeCo thin films and the MgO substrates where misfit dislocations are introduced in the FeCo thin films presumably to decrease the lattice misfits. Misfit dislocations are observed approximately every 9 and 1.4 nm in FeCo thin film at the FeCo/MgO(100) and the FeCo/MgO(110) interfaces, respectively. X-ray diffraction analysis indicates that the lattice spacing measured parallel to the single-crystal substrate surfaces are in agreement within 0.1% with those of the respective bulk values of Fe 50 Co 50 alloy crystal, showing that the FeCo film strain is very small. The magnetic anisotropies of these epitaxial films basically reflect the magnetocrystalline anisotropy of bulk FeCo alloy crystal

Segregation of solute elements at grain boundaries in an ultrafine grained Al-Zn-Mg-Cu alloy

International Nuclear Information System (INIS)

Sha, Gang; Yao, Lan; Liao, Xiaozhou; Ringer, Simon P.; Chao Duan, Zhi; Langdon, Terence G.

2011-01-01

The solute segregation at grain boundaries (GBs) of an ultrafine grained (UFG) Al-Zn-Mg-Cu alloy processed by equal-channel angular pressing (ECAP) at 200 o C was characterised using three-dimensional atom probe. Mg and Cu segregate strongly to the grain boundaries. In contrast, Zn does not always show clear segregation and may even show depletion near the grain boundaries. Trace element Si selectively segregates at some GBs. An increase in the number of ECAP passes leads to a decrease in the grain size but an increase in solute segregation at the boundaries. The significant segregation of alloying elements at the boundaries of ultrafine-grained alloys implies that less solutes will be available in the matrix for precipitation with a decrease in the average grain size. -- Research Highlights: → Atom probe tomography has been employed successfully to reveal unique segregation of solutes at ultrafine grained material. → Mg and Cu elements segregated strongly at the grain boundary of an ultrafine grained Al-Zn-Mg-Cu alloy processed by 4-pass and 8-pass ECAP at 200 o C. Zn frequently depleted at GBs with a Zn depletion region of 7-15 nm in width on one or both sides of the GBs. Only a small fraction (3/13) of GBs were observed with a low level of Zn segregation where the combined Mg and Cu excess is over 3.1 atom/nm 2 . Si appeared selectively segregated at some of the GBs. → The increase in number of ECAP passes from 4 to 8 correlated with the increase in mean level segregation of Mg and Cu for both solute excess and peak concentration. → The change of plane normal of a grain boundary within 30 o only leads to a slight change in the solute segregation level.

NFKB activity decreased in BALB/c mice with high fat diet and fructose

Science.gov (United States)

Nur'aini, Farida Dewi; Rahayu, Sri; Rifa'i, Muhaimin

2017-05-01

Excessive consumption of fat and fructose leads to obesity due to lipid accumulation. The excessive lipid causes hypertrophy in the adipocytes which lead to cell death. Consequently, dead adipocytes will produce adipokines, which cause macrophages and lymphocytes to infiltrate into the adipose tissue, elevating pro-inflammatory cytokines, thus triggering the production of pro-inflammatory cytokines through NFκB activity. Elicited soybeans extract (ESE) with bacteria and light contain Glyceollin and Isoflavones, which inhibit the activation of NFKB and reduce plasma cholesterol levels by upregulating cholesterol metabolism. This study aimed to analyze the effect of ESE against the relative number of CD4+ NFκB+ cells in BALB/c mice spleen after administrated by high-fat diet food and fructose (HFD) for 20 weeks. Mice were given orally with ESE after administrated by HFD at dose 78 mg/kgBW (D1), 104 mg/kgBW (D2), and 130 mg/kgBW (D3) for 4 weeks. This study also used positive control (HFD mice model without ESE treatment) and normal mice. Identification of NFKB activation was conducted using Flowcytometry analytical methods. Our result indicated that ESE could decrease significantly activation of NFκB in CD4 cell compare than positive control. The optimum dose that can decrease the relative number of CD4+ NFκB+ cells is dose 3.

Corrosion behaviors of Mg and its alloys with different Al contents in a modified simulated body fluid

Energy Technology Data Exchange (ETDEWEB)

Wen Zhaohui [Department of Ultrasound, First Affiliated Hospital of Harbin Medical University, Harbin 150001 (China); Wu Changjun, E-mail: wucj163@126.co [Department of Ultrasound, First Affiliated Hospital of Harbin Medical University, Harbin 150001 (China); Dai Changsong, E-mail: changsd@hit.edu.c [School of Chemistry Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Yang Feixia [School of Chemistry Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China)

2009-11-20

The corrosion behaviors of pure magnesium (Mg) and three Mg alloys with different Al contents were investigated in a modified simulated body fluid (m-SBF) through immersion tests, Tafel experiments, and electrochemical impedance spectroscopic (EIS) experiments. The immersion results show that the corrosion rates (CRs) of the four samples were in an order of AZ91D < AZ61 < AZ31 < pure Mg after immersion for 1 day. With an increase in immersion time, their corrosion rates decreased and then a stable stage was reached after 16 days. The order of CRs of the four samples changed to AZ91D < pure Mg < AZ61 < AZ31 after immersion for 24 days. The results of EIS experiments indicate that the charge transfer resistance (R{sub ct}) of the three magnesium alloys initially increased and then decreased while the R{sub ct} of pure Mg was kept lower within 24 h. The results of a scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) show that pure Mg and three alloys were heterogeneously corroded in the m-SBF. The corrosion of pure Mg, which showed a more uniform corrosion appearance, resulted from localized corrosion over the entire surface. Alloy AZ91D (of 8.5-9.5 wt.% Al) showed relatively uniform corrosion morphology and the {beta}-Mg{sub 12}Al{sub 17} precipitates in alloy AZ91D were more homogeneously and continuously distributed along the grain boundaries. Obvious corrosion pits were found on the surface of alloy AZ61 and AZ31. The corrosion pits of alloy AZ61 were shallower than those of alloy AZ31. Alloy AZ61 (of 5.8-7.2 wt.% Al) possessed more Al{sub 8}Mn{sub 5} and a little {beta}-Mg{sub 12}Al{sub 17} presented along the grain boundary heterogeneously and discontinuously. Al{sub 8}Mn{sub 5} was the main phase of the AZ31 alloy (of 2.5-3.5 wt.% Al) dispersed into the matrix. In conclusion, the microstructure and the Al content in the {alpha}-Mg (Al) matrix significantly affected the corrosion properties of the alloys in the m-SBF. With the increase

Influence of Dy in solid solution on the degradation behavior of binary Mg-Dy alloys in cell culture medium.

Science.gov (United States)

Yang, Lei; Ma, Liangong; Huang, Yuanding; Feyerabend, Frank; Blawert, Carsten; Höche, Daniel; Willumeit-Römer, Regine; Zhang, Erlin; Kainer, Karl Ulrich; Hort, Norbert

2017-06-01

Rare earth element Dy is one of the promising alloying elements for magnesium alloy as biodegradable implants. To understand the effect of Dy in solid solution on the degradation of Mg-Dy alloys in simulated physiological conditions, the present work studied the microstructure and degradation behavior of Mg-Dy alloys in cell culture medium. It is found the corrosion resistance enhances with the increase of Dy content in solid solution in Mg. This can be attributed to the formation of a relatively more corrosion resistant Dy-enriched film which decreases the anodic dissolution of Mg. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of amorphous Mg50Ni50 on hydriding and dehydriding behavior of Mg2Ni alloy

International Nuclear Information System (INIS)

Guzman, D.; Ordonez, S.; Fernandez, J.F.; Sanchez, C.; Serafini, D.; Rojas, P.A.; Aguilar, C.; Tapia, P.

2011-01-01

Composite Mg 2 Ni (25 wt.%) amorphous Mg 50 Ni 50 was prepared by mechanical milling starting with nanocrystalline Mg 2 Ni and amorphous Mg 50 Ni 50 powders, by using a SPEX 8000 D mill. The morphological and microstructural characterization of the powders was performed via scanning electron microscopy and X-ray diffraction. The hydriding characterization of the composite was performed via a solid gas reaction method in a Sievert's-type apparatus at 363 K under an initial hydrogen pressure of 2 MPa. The dehydriding behavior was studied by differential thermogravimetry. On the basis of the results, it is possible to conclude that amorphous Mg 50 Ni 50 improved the hydriding and dehydriding kinetics of Mg 2 Ni alloy upon cycling. A tentative rationalization of experimental observations is proposed. - Research Highlights: → First study of the hydriding behavior of composite Mg 2 Ni (25 wt.%) amorphous Mg 50 Ni 50 . → Microstructural characterization of composite material using XRD and SEM was obtained. → An improved effect of Mg 50 Ni 50 on the Mg 2 Ni hydriding behavior was verified. → The apparent activation energy for the hydrogen desorption of composite was obtained.

Superconducting properties of Zn and Al double-doped Mg1-x(Zn0.5Al0.5)xB2

DEFF Research Database (Denmark)

Xu, G.J.; Grivel, Jean-Claude; Abrahamsen, A.B.

2004-01-01

(XRD), ac susceptibility, magnetization and resistivity. The double doping leads to decreases in both the lattice parameters a and c, and the T-c decreases with increasing dopant content. A systematical comparison with Al doped- and Li, Al double doped MgB2 of structure, superconducting transition......A series of polycrystalline samples of Mg1-x(Zn0.5Al0.5)(x)B-2 (0less than or equal toxless than or equal to0.8) were prepared by solid state reaction method and their structure, superconducting transition temperature (T-c) and transport properties were investigated by means of X-ray diffraction...

Synthesis of Mg(OH)₂, MgO, and Mg nanoparticles using laser ablation of magnesium in water and solvents