| 1. |
- Baron, V, et al.
(författare)
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Neutron powder diffraction study of Mn-bearing hematite, α-Fe2−xMnxO3, in the range 0 x 0.176
- 2005
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Ingår i: Solid State Sciences. - : Elsevier BV. - 1293-2558. ; 7:6, s. 753-759
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Tidskriftsartikel (refereegranskat)abstract
- A detailed neutron powder diffraction and calorimetric study was conducted to determine the influence of increasing Mn-substitution on the crystal and the magnetic structures of hematite, α-Fe2O3. The study was initiated to determine, if Mn substitution may be responsible for unusual ferromagnetic properties of natural hematite samples from the Kalahari Mn field, South Africa. Natural as well as synthetic Mn-bearing hematite samples with the compositional range Fe2−xMnxO3 (x=0 to 0.176) were examined. Calorimetric measurements were performed to determine the Néel TN and the Morin TM temperature transitions. All studied hematite samples, irrespective of chemical composition, display weak ferromagnetism at 295 K and coexistence of weak ferromagnetic and antiferromagnetic phases at 10 K. A slight decrease of the total magnetic moment and TM but a drastic decrease of TN can be attributed to increasing Mn-substitution. The results illustrate that Mn substitution may contribute but cannot be the sole reason for the unusual magnetic properties of natural hematite samples.
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| 2. |
- Windahl, Sara H, 1971, et al.
(författare)
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Bone protection by estrens occurs through non-tissue-selective activation of the androgen receptor.
- 2006
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Ingår i: The Journal of clinical investigation. - 0021-9738. ; 116:9, s. 2500-9
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Tidskriftsartikel (refereegranskat)abstract
- The use of estrogens and androgens to prevent bone loss is limited by their unwanted side effects, especially in reproductive organs and breast. Selective estrogen receptor modulators (SERMs) partially avoid such unwanted effects, but their efficacy on bone is only moderate compared with that of estradiol or androgens. Estrens have been suggested to not only prevent bone loss but also exert anabolic effects on bone while avoiding unwanted effects on reproductive organs. In this study, we compared the effects of a SERM (PSK3471) and 2 estrens (estren-alpha and estren-beta) on bone and reproductive organs to determine whether estrens are safe and act via the estrogen receptors and/or the androgen receptor (AR). Estrens and PSK3471 prevented gonadectomy-induced bone loss in male and female mice, but none showed true anabolic effects. Unlike SERMs, the estrens induced reproductive organ hypertrophy in both male and female mice and enhanced MCF-7 cell proliferation in vitro. Estrens directly activated transcription in several cell lines, albeit at much higher concentrations than estradiol or the SERM, and acted for the most part through the AR. We conclude that the estrens act mostly through the AR and, in mice, do not fulfill the preclinical efficacy or safety criteria required for the treatment or prevention of osteoporosis.
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