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An iron-based beverage, HydroFerrate fluid (MRN-100), alleviates oxidative stress in murine lymphocytes in vitro
Mamdooh Ghoneum, Motohiro Matsuura, Sastry Gollapudi
Nutrition Journal , 2009, DOI: 10.1186/1475-2891-8-18
Abstract: Splenic lymphocytes from mice were cultured in the presence or absence of MRN-100 for 2 hrs and were subsequently exposed to hydrogen peroxide (H2O2) at a concentration of 25 μM for 14 hrs. Percent cell death was examined by flow cytometry and trypan blue exclusion. The effect of MRN-100 on Bcl-2 and Bax protein levels was determined by Western blot.Results show, as expected, that culture of splenic cells with H2O2 alone results in a significant increase in cell death (apoptosis) as compared to control (CM) cells. In contrast, pre-treatment of cells with MRN-100 followed by H2O2 treatment results in significantly reduced levels of apoptosis.In addition, MRN-100 partially prevents H2O2-induced down-regulation of the anti-apoptotic molecule Bcl-2 and upregulation of the pro-apoptotic molecule Bax.Our findings suggest that MRN-100 may offer a protective effect against oxidative stress-induced apoptosis in lymphocytes.Oxidative stress represents the imbalance between the cellular production of oxidants and the capacity of cellular antioxidant defenses to scavenge these oxidants. It is produced in cells by oxygen-derived species which include free radicals and peroxides; it is also produced at a low level by normal aerobic metabolism and nutritional deficiency in trace metal [1,2]. Increasing evidence indicates that oxidative stress is a major inducer of cell death [3]. In this process some of the reactive oxygen species (such as superoxide) are converted into hydrogen peroxide which can cause controlled apoptotic cell death [4,5].Oxidative stress is associated with many diseases, including chronic inflammation, arteriosclerosis, diabetes, stroke, Alzheimer's and Parkinson's diseases, and aging [6-8]. In addition, nutritional deficiencies like lack of iron have been shown to induce oxidative stress [9,10] and currently affect over 2 billion people worldwide. Thus far, the ability of iron to protect against oxidative stress has only been studied to a limited extent [11].I
Superconductivity in the Iron-Pnictide Parent Compound SrFe2As2  [PDF]
K. C. Kirshenbaum,S. R. Saha,N. P. Butch,J. D. Magill,J. Paglione
Physics , 2009, DOI: 10.1109/TIC-STH.2009.5444377
Abstract: The appearance of superconductivity at ambient pressures in the undoped iron pnictide parent compound SrFe2As2 is studied experimentally using several techniques and approaches to aid in understanding the nature of this phase. Low temperature magnetization measurements of single crystals of SrFe2As2 reveal diamagnetic screening due to the onset of superconductivity below 21 K, with volume fraction estimates varying between 0 and 15 percent. The effects of heat treatment and cold-working via severe mechanical deformation on the superconducting phase found are studied, showing that superconductivity can be suppressed via modest annealing and reinstated by cold-working.
M?ssbauer study of the '11' iron-based superconductors parent compound Fe(1+x)Te  [PDF]
A. Blachowski,K. Ruebenbauer,P. Zajdel,E. E. Rodriguez,M. A. Green
Physics , 2012, DOI: 10.1088/0953-8984/24/38/386006
Abstract: 57Fe Moessbauer spectroscopy was applied to investigate the superconductor parent compound Fe(1+x)Te for x=0.06, 0.10, 0.14, 0.18 within the temperature range 4.2 K - 300 K. A spin density wave (SDW) within the iron atoms occupying regular tetrahedral sites was observed with the square root of the mean square amplitude at 4.2 K varying between 9.7 T and 15.7 T with increasing x. Three additional magnetic spectral components appeared due to the interstitial iron distributed over available sites between the Fe-Te layers. The excess iron showed hyperfine fields at approximately 16 T, 21 T and 49 T for three respective components at 4.2 K. The component with a large field of 49 T indicated the presence of isolated iron atoms with large localized magnetic moment in interstitial positions. Magnetic ordering of the interstitial iron disappeared in accordance with the fallout of the SDW with the increasing temperature.
Iron Displacements and Magnetoelastic Coupling in the Spin-Ladder Compound BaFe2Se3  [PDF]
J. M. Caron,J. R. Neilson,D. C. Miller,A. Llobet,T. M. McQueen
Physics , 2011, DOI: 10.1103/PhysRevB.84.180409
Abstract: We report long-range ordered antiferromagnetism concomitant with local iron displacements in the spin-ladder compound BaFe$_2$Se$_3$. Short-range magnetic correlations, present at room temperature, develop into long-range antiferromagnetic order below T$_N$ = 256 K, with no superconductivity down to 1.8 K. Built of ferromagnetic Fe$_4$ plaquettes, the magnetic ground state correlates with local displacements of the Fe atoms. These iron displacements imply significant magnetoelastic coupling in FeX$_4$-based materials, an ingredient hypothesized to be important in the emergence of superconductivity. This result also suggests that knowledge of these local displacements is essential for properly understanding the electronic structure of these systems. As with the copper oxide superconductors two decades ago, our results highlight the importance of reduced dimensionality spin ladder compounds in the study of the coupling of spin, charge, and atom positions in superconducting materials.
Mechanical behaviour of spheriodal graphite cast iron in the temperature range Between -100°c and +100°c
Fierro,V.E.; Sikora,J.A.; Ansaldi,A.F.; Ratto,P.J.J.; Agüera,F.R.; Alvarez Villa,H.N.;
Latin American applied research , 2003,
Abstract: impact tests were done on spheroidal graphite cast iron samples, with five different microstructures. these were obtained by means of the following heat treatments: subcritical annealing, normalizing and two different austempering processes. other samples were tested in their as-cast condition. the tests were carried out in a temperature range from -100°c to +100°c. also, tensile tests and hardness measurements were performed to qualify the samples. every specimen came from a single melt, cast in "y" blocks of two different thicknesses. the impact test results showed an alteration in the fracture behaviour as a function of temperature. the transition temperature, in particular, showed a meaningful shift with the enlargement of the "y" block. this feature can lead to lower performances than expected. the harder and tougher the matrix, the more important this shift was.
Mechanical behaviour of spheriodal graphite cast iron in the temperature range Between -100°c and +100°c
V.E. Fierro,J.A. Sikora,A.F. Ansaldi,P.J.J. Ratto
Latin American applied research , 2003,
Abstract: Impact tests were done on spheroidal graphite cast iron samples, with five different microstructures. These were obtained by means of the following heat treatments: subcritical annealing, normalizing and two different austempering processes. Other samples were tested in their as-cast condition. The tests were carried out in a temperature range from -100°C to +100°C. Also, tensile tests and hardness measurements were performed to qualify the samples. Every specimen came from a single melt, cast in "Y" blocks of two different thicknesses. The impact test results showed an alteration in the fracture behaviour as a function of temperature. The transition temperature, in particular, showed a meaningful shift with the enlargement of the "Y" block. This feature can lead to lower performances than expected. The harder and tougher the matrix, the more important this shift was.
KFe_2Se_2 is the parent compound of K-doped iron selenide superconductors  [PDF]
Wei Li,Hao Ding,Zhi Li,Peng Deng,Kai Chang,Ke He,Shuaihua Ji,Lili Wang,Xucun Ma,Jiang-Ping Hu,Xi Chen,Qi-Kun Xue
Physics , 2012, DOI: 10.1103/PhysRevLett.109.057003
Abstract: We elucidate the existing controversies in the newly discovered K-doped iron selenide (KxFe2-ySe2-z) superconductors. The stoichiometric KFe2Se2 with \surd2\times\surd2 charge ordering was identified as the parent compound of KxFe2-ySe2-z superconductor using scanning tunneling microscopy and spectroscopy. The superconductivity is induced in KFe2Se2 by either Se vacancies or interacting with the anti-ferromagnetic K2Fe4Se5 compound. Totally four phases were found to exist in KxFe2-ySe2-z: parent compound KFe2Se2, superconducting KFe2Se2 with \surd2\times\surd5 charge ordering, superconducting KFe2Se2-z with Se vacancies and insulating K2Fe4Se5 with \surd5\times\surd5 Fe vacancy order. The phase separation takes place at the mesoscopic scale under standard molecular beam epitaxy condition.
Charge-Stripe Order in a Parent Compound of Iron-based Superconductors  [PDF]
Wei Li,Wei-Guo Yin,Lili Wang,Ke He,Xucun Ma,Qi-Kun Xue,Xi Chen
Physics , 2014,
Abstract: Charge ordering is one of the most intriguing and extensively studied phenomena in correlated electronic materials because of its strong impact on electron transport properties including superconductivity. Despite its ubiquitousness in correlated systems, the occurrence of charge ordering in iron-based superconductors is still unresolved. Here we use scanning tunneling microscopy to reveal a long-range charge-stripe order and a highly anisotropic dispersion of electronic states in the ground state of stoichiometric FeTe, the parent compound of the Fe(Te, Se, S) superconductor family. The formation of charge order in a strongly correlated electron system with integer nominal valence (here Fe$^{2+}$) is unexpected and suggests that the iron-based superconductors may exhibit more complex charge dynamics than originally expected. We show that the present observations can be attributed to the surpassing of the role of local Coulomb interaction by the poorly screened longer-range Coulomb interactions, facilitated by large Hund's rule coupling.
Low-temperature thermal conductivity of BaFe2As2: Parent compound of iron-arsenide superconductors  [PDF]
N. Kurita,F. Ronning,C. F. Miclea,E. D. Bauer,J. D. Thompson,A. S. Sefat,M. A. McGuire,B. C. Sales,D. Mandrus,R. Movshovich
Physics , 2009, DOI: 10.1103/PhysRevB.79.214439
Abstract: We report low-temperature thermal conductivity down to 40 mK of the antiferromagnet BaFe$_2$As$_{2}$, which is the parent compound of recently discovered iron-based superconductors. In the investigated temperature range below 4 K, the thermal conductivity $\kappa$ is well described by the expression $\kappa$ = $aT$ + $bT^{2.22}$. We attribute the ``$aT$''-term to an electronic contribution which is found to satisfy the Wiedemann-Franz law in the $T$ $\to$ 0 K limit, and the remaining thermal conductivity, $\sim$ $T^{2.22}$, is attributed to phonon conductivity. A small influence on thermal conductivity by magnetic fields up to 8 T is well accounted by the observed magnetoresistance. The result is consistent with a fully gapped magnon spectrum, inferred previously from inelastic neutron scattering measurements.
Pressure decoupled magnetic and structural transitions of the parent compound of iron based 122 superconductors BaFe2As2  [PDF]
Junjie Wu,Jungfu Lin,Xiancheng Wang,Qingqing Liu,Jinglong Zhu,Yuming Xiao,Paul Chow,Changqing Jin
Physics , 2014, DOI: 10.1073/pnas.1310286110
Abstract: The recent discovery of iron ferropnictide superconductors has received intensive concerns on magnetic involved superconductors. Prominent features of ferropnictide superconductors are becoming apparent: the parent compounds exhibit antiferromagnetic (AFM) ordered spin density wave (SDW) state; the magnetic phase transition is always accompanied to a crystal structural transition; superconductivity can be induced by suppressing the SDW phase via either chemical doping or applied external pressure to the parent state. These features generated considerable interests on the interplay between magnetism and structure in chemical doped samples, showing crystal structure transitions always precedes to or coincide with magnetic transition. Pressure tuned transition on the other hand would be more straightforward to superconducting mechanism studies since there are no disorder effects caused by chemical doping; however, remarkably little is known about the interplay in the parent compounds under controlled pressure due to the experimental challenge of in situ measuring both of magnetic & crystal structure evolution at high pressure & low temperatures. Here we show from combined synchrotron Mossbauer and x-ray diffraction at high pressures that the magnetic ordering surprisingly precedes the structural transition at high pressures in the parent compound BaFe2As2, in sharp contrast to the chemical doping case. The results can be well understood in terms of the spin fluctuations in the emerging nematic phase before the long range magnetic order that sheds new light on understanding how parent compound evolves from a SDW state to a superconducting phase, a key scientific inquiry of iron based superconductors.
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