| 1. |
- Kuiper, Pieter, 1960-, et al.
(författare)
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Resonant X-Ray raman spectra of Cu dd excitations in Sr2CuO2Cl2
- 1998
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Ingår i: Physical Review Letters. - College Park, MD : American Physical Society. - 0031-9007 .- 1079-7114. ; 80:23, s. 5204-5207
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Tidskriftsartikel (refereegranskat)abstract
- We present resonant x-ray Raman scattering results on Sr2CuO2Cl2, a model compound for high- Tc superconductors. We demonstrate that the dd excitations can be observed and show that the polarization dependence can be used to identify the dd excitations. We find the transition from the dx2−y2 ground state to the dxy excited state at 1.35 eV and to the degenerate dxz and dyz excited states at 1.7 eV. From analysis of the polarization dependence we conclude that the d3z2−r2 orbital energy is at 1.5 eV and not in the midinfrared (0.5 eV) as recently suggested. We use recent theoretical arguments to show that the d3z2−r2 excitation is accompanied by a local spin flip resulting in a shift upwards of 0.2 eV due to the exchange interaction with the neighboring spins. ©1998 American Physical Society.
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| 2. |
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| 3. |
- Butorin, S. M., et al.
(författare)
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Low-Energy d-d Excitations in MnO Studied by Resonant X-ray Fluorescence Spectroscopy
- 1997
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Ingår i: Advanced Light Source. - Berkely : Ernest Orlando Lawrence Berkeley National Laboratory University of California Berkeley, California. ; , s. 135-136
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Resonant soft X-ray emission spectroscopy has been demonstrated to possess interesting abilities for studies of electronic structure in various systems, such as symmetry probing, alignment and polarization dependence, sensitivity to channel interference, etc. (see other abstracts in this Annual Report). In the present abstract we focus on the feasibility of resonant soft X-ray emission to probe low energy excitations by means ofresonant electronic X-ray Raman scattenng....
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| 4. |
- Butorin, S. M., et al.
(författare)
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Low-energy d-d excitations in MnO studied by resonant x-ray fluorescence spectroscopy
- 1996
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 54, s. 4405-4408
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Tidskriftsartikel (refereegranskat)abstract
- We measured the Mn Lα,β x-ray fluorescence spectra of MnO excited by selected photon energies near the L2,3 absorption edges. The resulting resonant inelastic x-ray scattering spectra probe low-lying electronic excited states, due to dd and charge-transfer excitations. Using a two-step model and a purely atomic approximation, we reproduce both energies and varying intensities of dd excitations relative to the electronic recombination peak. Our results show that strongly varying line shapes in resonant x-ray emission need not be due to channel interference effects.
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| 5. |
- Byers, M, et al.
(författare)
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Estrogen receptor-beta mRNA expression in rat ovary: down-regulation by gonadotropins
- 1997
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Ingår i: Molecular endocrinology (Baltimore, Md.). - : The Endocrine Society. - 0888-8809 .- 1944-9917. ; 11:2, s. 172-182
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Tidskriftsartikel (refereegranskat)abstract
- We have examined the expression and regulation of the two estrogen receptor (ERα and ERβ) genes in the rat ovary, using Northern blotting, RT-PCR, and in situ hybridization histochemistry. Northern blotting results show that the ovary expresses both ERα and ERβ genes as single (∼6.5-kb) and multiple (ranging from ∼1.0-kb to ∼10.0-kb) transcripts, respectively. ERα mRNA is expressed at a level lower than ERβ mRNA in immature rat ovaries. This relationship appears unchanged between sexually mature adult rats and immature rats. In sexually mature adult rats undergoing endogenous hormonal changes, whole ovarian content of ERβ mRNA, as determined by RT-PCR, remained more or less constant with the exception of the evening of proestrus when ERβ mRNA levels were decreased. Examination of ERβ mRNA expression at the cellular level, by in situ hybridization, showed that ERβ mRNA is expressed preferentially in granulosa cells of small, growing, and preovulatory follicles, although weak expression of ERβ mRNA was observed in a subset of corpora lutea, and that the decrease in ERβ mRNA during proestrous evening is attributable, at least in part, to down-regulation of ERβ mRNA in the preovulatory follicles. This type of expression and regulation was not typical for ERα mRNA in the ovary. Although whole ovarian content of ERα mRNA was clearly detected by RT-PCR, no apparent modulation of ERα mRNA levels was observed during the estrous cycle. Examination of ERα mRNA expression at the cellular level, by in situ hybridization, showed that ERα mRNA is expressed at a low level throughout the ovary with no particular cellular localization.To further examine the potential role of the preovulatory pituitary gonadotropins in regulating ERβ mRNA expression in the ovary, we used immature rats treated with gonadotropins. In rats undergoing exogenous hormonal challenges, whole ovarian content of ERβ mRNA, as determined by RT-PCR, remained more or less unchanged after an injection of PMSG. In contrast, a subsequent injection of human CG (hCG) resulted in a substantial decrease in whole ovarian content of ERβ mRNA. In situ hybridization for ERβ mRNA shows that small, growing, and preovulatory follicles express ERβ mRNA in the granulosa cells. The preovulatory follicles contain ERβ mRNA at a level lower than that observed for small and growing follicles. In addition, there is an abrupt decrease in ERβ mRNA expression in the preovulatory follicles after hCG injection. The inhibitory effect of hCG on ERβ mRNA expression was also observed in cultured granulosa cells. Moreover, agents stimulating LH/CG receptor-associated intracellular signaling pathways (forskolin and a phorbol ester) readily mimicked the effect of hCG in down-regulating ERβ mRNA in cultured granulosa cells.Taken together, our results demonstrate that 1) the ovary expresses both ERα and ERβ genes, although ERβ is the predominant form of estrogen receptor in the ovary, 2) ERβ mRNA is localized predominantly to the granulosa cells of small, growing, and preovulatory follicles, and 3) the preovulatory LH surge down-regulates ERβ mRNA. These results clearly implicate the physiological importance of ERβ in female reproductive functions.
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| 6. |
- Kuiper, GGJM, et al.
(författare)
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Cloning of a novel receptor expressed in rat prostate and ovary
- 1996
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 93:12, s. 5925-5930
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Tidskriftsartikel (refereegranskat)abstract
- We have cloned a novel member of the nuclear receptor superfamily. The cDNA of clone 29 was isolated from a rat prostate cDNA library and it encodes a protein of 485 amino acid residues with a calculated molecular weight of 54.2 kDa. Clone 29 protein is unique in that it is highly homologous to the rat estrogen receptor (ER) protein, particularly in the DNA-binding domain (95%) and in the C-terminal ligand-binding domain (55%). Expression of clone 29 in rat tissues was investigated by in situ hybridization and prominent expression was found in prostate and ovary. In the prostate clone 29 is expressed in the epithelial cells of the secretory alveoli, whereas in the ovary the granuloma cells in primary, secondary, and mature follicles showed expression of clone 29. Saturation ligand-binding analysis of in vitro synthesized clone 29 protein revealed a single binding component for 17beta-estradiol (E2) with high affinity (Kd= 0.6 nM). In ligand-competition experiments the binding affinity decreased in the order E2 > diethylstilbestrol > estriol > estrone > 5alpha-androstane-3beta,17beta-diol >> testosterone = progesterone = corticosterone = 5alpha-androstane-3alpha,17beta-diol. In cotransfection experiments of Chinese hamster ovary cells with a clone 29 expression vector and an estrogen-regulated reporter gene, maximal stimulation (about 3-fold) of reporter gene activity was found during incubation with 10 nM of E2. Neither progesterone, testosterone, dexamethasone, thyroid hormone, all-trans-retinoic acid, nor 5alpha-androstane-3alpha,I7beta-diol could stimulate reporter gene activity, whereas estrone and 5alpha-androstane-3beta,17beta-diol did. We conclude that clone 29 cDNA encodes a novel rat ER, which we suggest be named rat ERbeta to distinguish it from the previously cloned ER (ERalpha) from rat uterus.
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