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Ying JJ, Wang XF, Wu T, Xiang ZJ, Liu RH, Yan YJ, Wang AF, Zhang M, Ye GJ, Cheng P, Hu JP, Chen XH. Measurements of the anisotropic in-plane resistivity of underdoped FeAs-based pnictide superconductors. PHYSICAL REVIEW LETTERS 2011; 107:067001. [PMID: 21902359 DOI: 10.1103/physrevlett.107.067001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Indexed: 05/31/2023]
Abstract
We systematically investigated the in-plane resistivity anisotropy of electron-underdoped EuFe(2-x)Co(x)As(2) and BaFe(2-x)Co(x)As(2) and hole-underdoped Ba(1-x)K(x)Fe(2)As(2). Large in-plane resistivity anisotropy was found in the former samples, while tiny in-plane resistivity anisotropy was detected in the latter ones. When it is detected, the anisotropy starts above the structural transition temperature and increases smoothly through it. As the temperature is lowered further, the anisotropy takes a dramatic enhancement through the magnetic transition temperature. We found that the anisotropy is universally tied to the presence of T-linear behavior of resistivity. Our results demonstrate that the nematic state is caused by electronic degrees of freedom, and the microscopic orbital involvement in the magnetically ordered state must be fundamentally different between the hole- and electron-doped materials.
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Zhang Y, Yang LX, Xu M, Ye ZR, Chen F, He C, Xu HC, Jiang J, Xie BP, Ying JJ, Wang XF, Chen XH, Hu JP, Matsunami M, Kimura S, Feng DL. Nodeless superconducting gap in A(x)Fe2Se2 (A=K,Cs) revealed by angle-resolved photoemission spectroscopy. NATURE MATERIALS 2011; 10:273-7. [PMID: 21358648 DOI: 10.1038/nmat2981] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Accepted: 02/01/2011] [Indexed: 05/15/2023]
Abstract
Pairing symmetry is a fundamental property that characterizes a superconductor. For the iron-based high-temperature superconductors, an s(±)-wave pairing symmetry has received increasing experimental and theoretical support. More specifically, the superconducting order parameter is an isotropic s-wave type around a particular Fermi surface, but it has opposite signs between the hole Fermi surfaces at the zone centre and the electron Fermi surfaces at the zone corners. Here we report the low-energy electronic structure of the newly discovered superconductors, A(x)Fe(2)Se(2) (A=K,Cs) with a superconducting transition temperature (Tc) of about 30 K. We found A(x)Fe(2)Se(2) (A=K,Cs) is the most heavily electron-doped among all iron-based superconductors. Large electron Fermi surfaces are observed around the zone corners, with an almost isotropic superconducting gap of ~10.3 meV, whereas there is no hole Fermi surface near the zone centre, which demonstrates that interband scattering or Fermi surface nesting is not a necessary ingredient for the unconventional superconductivity in iron-based superconductors. Thus, the sign change in the s(±) pairing symmetry driven by the interband scattering as suggested in many weak coupling theories becomes conceptually irrelevant in describing the superconducting state here. A more conventional s-wave pairing is probably a better description.
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178
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Chen XH, Xiang HY, Wang Z, Zhang YJ, Han CG, Li DW, Yu JL, Cheng YQ. Studies on interaction of cucurbit aphid-borne yellow virus proteins using yeast two-hybrid system and bimolecular fluorescence complementation. Acta Virol 2011; 55:235-41. [PMID: 21978157 DOI: 10.4149/av_2011_03_235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this article, yeast two-hybrid system (YTHS) and bimolecular fluorescence complementation (BiFC) were used to analyze the interactions of cucurbit aphid-borne yellows virus (CABYV)-encoded proteins. P0, P1, P1-2, P3, P4, and P5 were tested by YTHS in all possible pairwise combinations, and only P3/P3 interaction was detected. Results obtained by BiFC further confirmed the self-interaction of P3, and the subcellular localization of reconstituted YFP fluorescence was observed mainly in nuclei of Nicotiana benthamiana leaf epidermal cells. Domains involved in P3/P3 self-interaction were analyzed by YTHS and BiFC using deletion mutants. The results showed that R domain (residues 1-61) in the N-terminus could self-interact, and it also interacted with the S domain (residues 62-199) in the C-terminus of P3. The present work would serve as a molecular basis for further characterization of CABYV proteins, and the regions involved in P3/P3 self-interaction could provide the clue for understanding the capsid assembly pathway of CABYV.
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Chen XH, Zeng DG, Ma N. Cloning, partial sequence, and single-nucleotide polymorphism of the ryanodine receptor gene of the Pacific white shrimp Litopenaeus vannamei (Penaeidae). GENETICS AND MOLECULAR RESEARCH 2010; 9:2406-11. [PMID: 21161889 DOI: 10.4238/vol9-4gmr976] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Ryanodine receptor/calcium release channel is a large protein that plays an essential role in muscle contraction; mutations in the ryanodine receptor gene affect sensitivity to stress. As a first step towards investigating the relationship between the ryanodine receptor and shrimp cramped muscle syndrome, we cloned, partially sequenced, and examined single-nucleotide polymorphisms (SNPs) of the ryanodine receptor gene of the Pacific white shrimp (Litopenaeus vannamei). The nucleotide sequence of a 15.06-kb L. vannamei genomic DNA segment containing a partial ryanodine receptor gene sequence was determined (deposited in GenBank nucleotide database: HM367069). Direct sequencing of PCR-amplified ryanodine receptor exons with their intron-flanking regions in 10 cramped muscle syndrome shrimp and 10 healthy shrimp, revealed seven SNPs. Five of them (1713A/G, 1749T/C, 1755T/C, 3965G/A, and 8737C/T) are located in exons; however, they appear to be neutral (synonymous), since they do not alter the encoded amino acid. The other SNPs (1553C/T and 13337A/G) are in introns. The SNPs identified in the ryanodine receptor gene could be useful for association studies aimed at determining the physiological role of the ryanodine receptor in cramped muscle syndrome of shrimp.
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Cheng J, Chu WS, Wu G, Zhao HF, Xu W, Zhou J, Zhang LJ, Chen XH, Wu ZY. Potassium doping effect on the lattice softening and electronic structure of Ba(1-x)K(x)Fe(2)As(2) probed by X-ray absorption spectroscopy. JOURNAL OF SYNCHROTRON RADIATION 2010; 17:730-736. [PMID: 20975217 DOI: 10.1107/s0909049510038756] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Accepted: 09/28/2010] [Indexed: 05/30/2023]
Abstract
Ba(1-x)K(x)Fe(2)As(2) superconducting samples (x = 0, 0.2, 0.4, 0.5) were synthesized by the solid-state reaction method. In this contribution the doping effect of potassium on the lattice dynamics in this newly discovered Ba(1-x)K(x)Fe(2)As(2) superconductor has been investigated by extended X-ray absorption fine-structure spectroscopy. The analysis shows that with potassium doping an increased disorder in the iron layers is mainly related to the softening of the Fe-Fe bond. Information about the electronic structure of these materials has also been obtained by looking at the X-ray absorption near-edge structure spectra that point out the presence of holes in the Fe-3d/As-4p hybridized orbital of the BaFe(2)As(2)-based system.
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181
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He C, Zhang Y, Xie BP, Wang XF, Yang LX, Zhou B, Chen F, Arita M, Shimada K, Namatame H, Taniguchi M, Chen XH, Hu JP, Feng DL. Electronic-structure-driven magnetic and structure transitions in superconducting NaFeAs single crystals measured by angle-resolved photoemission spectroscopy. PHYSICAL REVIEW LETTERS 2010; 105:117002. [PMID: 20867599 DOI: 10.1103/physrevlett.105.117002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 06/14/2010] [Indexed: 05/29/2023]
Abstract
The electronic structure of NaFeAs is studied with angle-resolved photoemission spectroscopy on high quality single crystals. Large portions of the band structure start to shift around the structural transition temperature and smoothly evolve as the temperature lowers through the spin density wave transition. Moreover, band folding due to magnetic order emerges slightly above the structural transition. Our observation provides direct evidence that the structural and magnetic transitions share the same origin and could both be driven by the electronic structure reconstruction in Fe-based superconductors instead of Fermi surface nesting. We did not observe any sign of a gap in the superconducting state, which is likely related to weakened superconductivity in the presence of the spin density wave.
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182
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Zhang Y, Yang LX, Chen F, Zhou B, Wang XF, Chen XH, Arita M, Shimada K, Namatame H, Taniguchi M, Hu JP, Xie BP, Feng DL. Out-of-plane momentum and symmetry-dependent energy gap of the pnictide Ba0.6K0.4Fe2As2 superconductor revealed by angle-resolved photoemission spectroscopy. PHYSICAL REVIEW LETTERS 2010; 105:117003. [PMID: 20867600 DOI: 10.1103/physrevlett.105.117003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2010] [Indexed: 05/29/2023]
Abstract
The three-dimensional band structure and superconducting gap of Ba0.6K0.4Fe2As2 are studied with angle-resolved photoemission spectroscopy. In contrast with previous results, we have identified three holelike Fermi surface sheets near the zone center with sizable out-of-plane or kz dispersion. The superconducting gap on certain Fermi surface sheets shows significant kz dependence. Moreover, the superconducting gap sizes are different at the same Fermi momentum for two bands with different spatial symmetries (one odd, one even). Our results further reveal the three-dimensional and orbital-dependent structure of the superconducting gap in iron pnictides, which facilitates the understanding of momentum-integrated measurements and provides a distinct test for theories.
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183
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Lumata LL, Choi KY, Brooks JS, Reyes AP, Kuhns PL, Wu G, Chen XH. 77Se and 63Cu NMR studies of the electronic correlations in CuxTiSe2 (x = 0.05, 0.07). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:295601. [PMID: 21399313 DOI: 10.1088/0953-8984/22/29/295601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report a (77)Se and (63)Cu nuclear magnetic resonance (NMR) investigation on the charge-density-wave (CDW) superconductor Cu(x)TiSe(2) (x = 0.05 and 0.07). At high magnetic fields where superconductivity is suppressed, the temperature dependence of (77)Se and (63)Cu spin-lattice relaxation rates 1/T(1) follow a linear relation. The slope of (77)Se 1/T(1) versus T increases with the Cu doping. This can be described by a modified Korringa relation which suggests the significance of electronic correlations and the Se 4p- and Ti 3d-band contribution to the density of states at the Fermi level in the studied compounds.
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184
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He Y, Wu T, Wu G, Zheng QJ, Liu YZ, Chen H, Ying JJ, Liu RH, Wang XF, Xie YL, Yan YJ, Dong JK, Li SY, Chen XH. Evidence for competing magnetic and superconducting phases in superconducting Eu 1-x Sr x Fe 2-y Co y As 2 single crystals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:235701. [PMID: 21393768 DOI: 10.1088/0953-8984/22/23/235701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In single crystals of Eu(1-x)Sr(x)Fe(2-y)Co(y)As(2), Co doping suppresses spin-density wave (SDW) ordering and induces a superconducting transition. A resistivity reentrance due to the antiferromagnetic ordering of Eu(2+) spins is observed, indicating the competition between antiferromagnetism (AFM) and superconductivity (SC). It is striking that the resistivity reentrance can be completely suppressed by a small magnetic field due to a field-induced metamagnetic transition from AFM to ferromagnetism (FM). The resistivity reentrance can also be suppressed by the substitution of Eu(2+) ions with nonmagnetic Ba(2+)/Sr(2+) to completely destroy the AFM ordering. These results indicate that the AFM order appears destructive to SC, while FM can coexist with the superconductivity. Further we find that magnon excitation exists in AFM ordering and can be suppressed by an applied field. Coexistence of SC from the FeAs layer and the inner field produced by the ferromagnetic Eu(2+) layer suggest a possible p-wave component in the superconducting order parameter.
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185
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Chen XH, Xia LX, Zhou HB, Qiu GZ. Chemical composition and antioxidant activities of Russula griseocarnosa sp. nov. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:6966-6971. [PMID: 20429560 DOI: 10.1021/jf1011775] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Pileus and stipe of mushroom Russula griseocarnosa from South China were analyzed separately for chemical composition and antioxidant activities. The wild mushroom species proved to have antioxidant potential, using assays of reducing power, chelating effect on ferrous ions, scavenging effect on hydroxyl free radicals, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. The mushroom contained very useful phytochemicals such as phenolics, flavonoids, ergosterol, and beta-carotene. The phenolic composition of R. griseocarnosa was analyzed by high-performance liquid chromatography (HPLC). The major component in R. griseocarnosa was quercetin (95.82 microg/g). The combination of bioactive substances and rich nutritional composition (high contents in protein and carbohydrates, low content in fat) in the mushroom should be useful to consumers in encouraging them to utilize the nutritive potential of this edible wild mushroom.
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186
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Zhao Z, Liu XF, Wu HC, Zou SB, Wang JY, Ni PH, Chen XH, Fan QS. Rab5a overexpression promoting ovarian cancer cell proliferation may be associated with APPL1-related epidermal growth factor signaling pathway. Cancer Sci 2010; 101:1454-62. [PMID: 20412119 PMCID: PMC11159928 DOI: 10.1111/j.1349-7006.2010.01558.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Revised: 02/26/2010] [Accepted: 03/02/2010] [Indexed: 02/01/2023] Open
Abstract
Rab5a is a regulatory guanosine triphosphatase that is associated with the transport and fusion of endocytic vesicles, and participates in regulation of intracellular signaling pathways embraced by cells to adapt to the specific environment. Rab5a is also correlated with lung, stomach, and hepatocellular carcinomas. Here, we detected Rab5a in paraffin-embedded samples of 20 ovarian cysts, 20 benign cystadenomas, and 39 ovarian cancers by immunohistochemistry, and observed that Rab5a expression was significantly higher in ovarian cancer (P = 0.0001). By setting up stable HO-8910 cell lines expressing Rab5a or dominant negative Rab5a (Rab5a:S34N), we found that Rab5a overexpression enhanced the cell growth by promoting G1 into S phase. In contrast, Rab5a:S34N inhibited this process. Additionally, APPL1 (adaptor protein containing PH domain, PTB domain, and Leucine zipper motif), a downstream effector of Rab5a, was also involved in promoting HO-8910 cell cycle progress. But this function was blocked by Rab5a:S34N. Laser scanning confocal microscopy represented the colocalization of APPL1 and Rab5a in the plasmolemma, which changed with the time of epidermal growth factor (EGF) stimulation. We also found APPL1 could transfer from the membranes into the nucleus where it interacted with NuRD/MeCP1 (the nucleosome remodeling and histone deacetylase multiprotein complex). NuRD is reported to be involved in the deacetylation of histone H3 and H4 to regulate nuclear transcription. So Rab5a promoted proliferation of ovarian cancer cells, which may be associated with the APPL1-related epidermal growth factor signaling pathway.
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Peng HF, Chen XH, Lu YP, Peng YF, Wan BH, Chen ND, Wu B, Xin SP, Zhang GQ. Fine mapping of a gene for non-pollen type thermosensitive genic male sterility in rice (Oryza sativa L.). TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2010; 120:1013-1020. [PMID: 20012261 DOI: 10.1007/s00122-009-1229-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2009] [Accepted: 11/21/2009] [Indexed: 05/28/2023]
Abstract
The thermo-sensitive genic male sterility (TGMS) lines play a crucial role in two-line hybrid rice production. For a practical TGMS line, the stability of male sterility is one of the most important technical indicators. In this study, XianS, a spontaneous mutant with stable male sterility from an indica rice cultivar Xianhuangzhan, was classified as a non-pollen type TGMS line. The critical non-pollen sterility point temperature of XianS was determined as 27 degrees C. Genetic analysis demonstrated that the non-pollen sterility in XianS was controlled by a single recessive gene. Using SSR markers and bulked segregant analysis, the TGMS gene in XianS was fine mapped to a 183 kb interval between RMAN81 and RMX21 on chromosome 2. Two markers, 4039-1 and RMX14 completely cosegregated with this gene. Allelism test indicated that the non-pollen phenotype in seven non-pollen type TGMS lines from different sources, XianS, AnnongS-1, Q523S, Q524S, N28S, G421S, and Q527S is caused by the same TGMS gene. Although the location of TGMS gene in XianS is close to the gene OsNAC6, a previously identified candidate gene of tms5 in AnnongS-1, the sequence of OsNAC6 and its promoter region was identical in TGMS line XianS, AnnongS-1, and wild-type Xianhuangzhan. These results suggest that the non-pollen type TGMS trait probably be controlled by the same TGMS gene in different TGMS rice lines, but its real candidate gene still need to be further studied and identified.
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Dong JK, Zhou SY, Guan TY, Zhang H, Dai YF, Qiu X, Wang XF, He Y, Chen XH, Li SY. Quantum criticality and nodal superconductivity in the FeAs-based superconductor KFe2As2. PHYSICAL REVIEW LETTERS 2010; 104:087005. [PMID: 20366962 DOI: 10.1103/physrevlett.104.087005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Indexed: 05/29/2023]
Abstract
The in-plane resistivity rho and thermal conductivity kappa of the FeAs-based superconductor KFe2As2 single crystal were measured down to 50 mK. We observe non-Fermi-liquid behavior rho(T) approximately T{1.5} at H{c{2}}=5 T, and the development of a Fermi liquid state with rho(T) approximately T{2} when further increasing the field. This suggests a field-induced quantum critical point, occurring at the superconducting upper critical field H{c{2}}. In zero field, there is a large residual linear term kappa{0}/T, and the field dependence of kappa_{0}/T mimics that in d-wave cuprate superconductors. This indicates that the superconducting gaps in KFe2As2 have nodes, likely d-wave symmetry. Such a nodal superconductivity is attributed to the antiferromagnetic spin fluctuations near the quantum critical point.
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Wang XF, Yan YJ, Ying JJ, Li QJ, Zhang M, Xu N, Chen XH. Structure and physical properties for a new layered pnictide-oxide: BaTi₂As₂O. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:075702. [PMID: 21386395 DOI: 10.1088/0953-8984/22/7/075702] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We have successfully synthesized a new layered pnictide-oxide: BaTi(2)As(2)O. It shares similar characteristics with Na(2)Ti(2)Sb(2)O. The crystal has a layered structure with a tetragonal P4/nmm group (a = 4.047(3) Å, c = 7.275(4) Å). The resistivity shows an anomaly at 200 K, which should be ascribed to an SDW or structural transition. The SDW or structural transition is confirmed by magnetic susceptibility and heat capacity measurements. These behaviors are very similar to those observed in parent compounds of high-T(c) iron-based pnictide superconductors, in which the superconductivity shows up when the anomaly due to the SDW or structural transition is suppressed. Therefore, the new layered pnictide-oxide, BaTi(2)As(2)O, could be a potential parent compound for superconductivity. It is found that Li( + ) doping significantly suppresses the anomaly, but no superconductivity emerges so far.
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Duncan WJ, Welzel OP, Harrison C, Wang XF, Chen XH, Grosche FM, Niklowitz PG. High pressure study of BaFe2As2--the role of hydrostaticity and uniaxial stress. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:052201. [PMID: 21386332 DOI: 10.1088/0953-8984/22/5/052201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We investigate the evolution of the electrical resistivity of BaFe(2)As(2) single crystals with pressure. The samples used were from the same batch, grown using a self-flux method, and showed properties that were highly reproducible. Samples were pressurized using three different pressure media: pentane-isopentane (in a piston-cylinder cell), Daphne oil (in an alumina anvil cell) and steatite (in a Bridgman cell). Each pressure medium has its own intrinsic level of hydrostaticity, which dramatically affects the phase diagram. An increasing uniaxial pressure component in this system quickly reduces the spin density wave order and favours the appearance of superconductivity, which is similar to what is seen in SrFe(2)As(2).
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191
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Butler LD, Koopman C, Neri E, Giese-Davis J, Palesh O, Thorne-Yocam KA, Dimiceli S, Chen XH, Fobair P, Kraemer HC, Spiegel D. Effects of supportive-expressive group therapy on pain in women with metastatic breast cancer. Health Psychol 2009; 28:579-87. [PMID: 19751084 DOI: 10.1037/a0016124] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE To examine whether a group intervention including hypnosis can reduce cancer pain and trait hypnotizability would moderate these effects. DESIGN This randomized clinical trial examined the effects of group therapy with hypnosis (supportive-expressive group therapy) plus education compared to an education-only control condition on pain over 12 months among 124 women with metastatic breast cancer. MAIN OUTCOME MEASURES Pain and suffering, frequency of pain, and degree of constant pain were assessed at baseline and 4-month intervals. Those in the treatment group also reported on their experiences using the hypnosis exercises. RESULTS Intention-to-treat analyses indicated that the intervention resulted in significantly less increase in the intensity of pain and suffering over time, compared to the education-only group, but had no significant effects on the frequency of pain episodes or amount of constant pain, and there was no interaction of the intervention with hypnotizability. Within the intervention group, highly hypnotizable participants, compared to those less hypnotizable, reported greater benefits from hypnosis, employed self-hypnosis more often outside of group, and used it to manage other symptoms in addition to pain. CONCLUSION These results augment the growing literature supporting the use of hypnosis as an adjunctive treatment for medical patients experiencing pain.
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192
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Kurmaev EZ, McLeod JA, Skorikov NA, Finkelstein LD, Moewes A, Korotin MA, Izyumov YA, Xie YL, Wu G, Chen XH. Structural models of FeSe(x). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:435702. [PMID: 21832444 DOI: 10.1088/0953-8984/21/43/435702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Two different structural models for non-stoichiometric FeSe(x) are examined and compared with soft x-ray spectroscopy findings for FeSe(x) (x = 0.85, 0.50). A structural model of tetragonal FeSe with excess interstitial Fe gives better agreement with experiment than a structural model of tetragonal FeSe with Se vacancies. This interstitial Fe increases the number of 3d states at the Fermi level. We find evidence that large non-stoichiometric ratios of Fe:Se, such as that of FeSe(0.50), yield clusters of pure Fe in the crystal structure.
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Riggs SC, McDonald RD, Kemper JB, Stegen Z, Boebinger GS, Balakirev FF, Kohama Y, Migliori A, Chen H, Liu RH, Chen XH. Doping dependent nonlinear Hall effect in SmFeAsO(1-x)F(x). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:412201. [PMID: 21693981 DOI: 10.1088/0953-8984/21/41/412201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report the Hall resistivity, ρ(xy), of polycrystalline SmFeAsO(1-x)F(x) for four different fluorine concentrations from the onset of superconductivity through the collapse of the structural phase transition. For the two more highly doped samples, ρ(xy) is linear in magnetic field up to 50 T with only weak temperature dependence, reminiscent of a simple Fermi liquid. For the lightly doped samples with x<0.15, we find a low temperature regime characterized as ρ(xy)(H) being both nonlinear in magnetic field and strongly temperature-dependent even though the Hall angle is small. The onset temperature for this nonlinear regime is in the vicinity of the structural phase (SPT)/magnetic ordering (MO) transitions. The temperature dependence of the Hall resistivity is consistent with a thermal activation of carriers across an energy gap. The evolution of the energy gap with doping is reported.
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Chen XH, Zhou HB, Qiu GZ. Analysis of several heavy metals in wild edible mushrooms from regions of China. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2009; 83:280-285. [PMID: 19452115 DOI: 10.1007/s00128-009-9767-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2009] [Accepted: 05/01/2009] [Indexed: 05/27/2023]
Abstract
The metal (Cu, Ni, Cd, Hg, As, Pb) contents in wild edible mushrooms collected from three different sites in China were determined by atomic absorption spectrometry and atomic fluorescence spectrometry. All element concentrations were determined on a dry weight basis. A total of 11 species was studied, five being from the urban area and six from rural areas in China. The As content ranged from 0.44 to 1.48 mg/kg. The highest As content was seen in Macrolepiota crustosa from the urban area, and the lowest in Russula virescens from rural areas. A high Ni concentration (1.35 mg/kg) was found in Calvatia craniiformis from the urban area. The lowest Ni level was 0.11 mg/kg, for the species R. virescens and Cantharellus cibarius. The Cu content ranged from 39.0 to 181.5 mg/kg. The highest Cu content was seen in Agaricus silvaticus and the lowest in C. cibarius. The Pb content ranged from 1.9 to 10.8 mg/kg. The highest Pb value was found in C. craniiformis. The Cd content ranged from 0.4 to 91.8 mg/kg. The highest Cd value was found in M. crustosa. The Hg content ranged from 0.28 to 3.92 mg/kg. The highest Hg level was found in Agaricus species. The levels of the heavy metals Cd, Pb, and Hg in the studied mushroom species from urban area can be considered high. The metal-to-metal correlation analysis supported they were the same source of contamination. High automobile traffic was identified as the most likely source of the contamination. Based upon the present safety standards, consumption of those mushrooms that grow in the polluted urban area should be avoided.
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Wu G, Wu T, Li Z, Zhao L, Liu RH, Chen H, Fang DF, Luo JL, Chen XH. Transport properties and the large anisotropic magnetoresistance of Cu(x)NbS(2) single crystals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:275601. [PMID: 21828495 DOI: 10.1088/0953-8984/21/27/275601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The transport properties of Cu(x)NbS(2) (x = 0.09, 0.44 and 0.55) single crystals were systematically studied. The in-plane and out-of-plane resistivities decrease with increasing Cu content, and a transition with hysteresis shows up for the crystals with x = 0.44 and 0.55. The thermopower and Hall coefficient of Cu(x)NbS(2) show opposite signs, indicating that there are two kinds of carriers in this system. The angular dependences of the in-plane magnetoresistance (MR(ab) = (ρ(ab)(H)-ρ(ab)(0))/ρ(ab)(0) × 100%) at different temperatures were also studied. The single crystals with x = 0.44 and 0.55 show a strong anisotropic MR(ab). For the x = 0.55 sample, MR(ab) reaches 80% with a magnetic field of 14 T applied along the c-axis, while MR(ab) is less than 5% for the magnetic field applied within the ab-plane. These results can be well understood in the light of the anisotropic Fermi surface in the multiband system.
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196
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Wu G, Xie YL, Chen H, Zhong M, Liu RH, Shi BC, Li QJ, Wang XF, Wu T, Yan YJ, Ying JJ, Chen XH. Superconductivity at 56 K in samarium-doped SrFeAsF. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:142203. [PMID: 21825317 DOI: 10.1088/0953-8984/21/14/142203] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We synthesized the samples Sr(1-x)Sm(x)FFeAs with a ZrCuSiAs-type structure. These samples were characterized by resistivity and susceptibility. It is found that substitution of rare earth metal for alkaline earth metal in this system suppresses the anomaly in resistivity and induces superconductivity. Superconductivity at 56 K in nominal composition Sr(0.5)Sm(0.5)FFeAs is realized, indicating that the superconducting transition temperatures in the iron arsenide fluorides can reach as high as that in oxypnictides with the same structure.
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197
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Drew AJ, Niedermayer C, Baker PJ, Pratt FL, Blundell SJ, Lancaster T, Liu RH, Wu G, Chen XH, Watanabe I, Malik VK, Dubroka A, Rössle M, Kim KW, Baines C, Bernhard C. Coexistence of static magnetism and superconductivity in SmFeAsO(1-x)F(x) as revealed by muon spin rotation. NATURE MATERIALS 2009; 8:310-314. [PMID: 19234446 DOI: 10.1038/nmat2396] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Accepted: 01/20/2009] [Indexed: 05/27/2023]
Abstract
The recent observation of superconductivity with critical temperatures (Tc) up to 55 K in the pnictide RFeAsO(1-x)F(x), where R is a lanthanide, marks the first discovery of a non-copper-oxide-based layered high-Tc superconductor. It has raised the suspicion that these new materials share a similar pairing mechanism to the cuprate superconductors, as both families exhibit superconductivity following charge doping of a magnetic parent material. In this context, it is important to follow the evolution of the microscopic magnetic properties of the pnictides with doping and hence to determine whether magnetic correlations coexist with superconductivity. Here, we present a muon spin rotation study on SmFeAsO(1-x)F(x), with x=0-0.30 that shows that, as in the cuprates, static magnetism persists well into the superconducting regime. This analogy is quite surprising as the parent compounds of the two families have rather different magnetic ground states: itinerant spin density wave for the pnictides contrasted with the Mott-Hubbard insulator in the cuprates. Our findings therefore suggest that the proximity to magnetic order and associated soft magnetic fluctuations, rather than strong electronic correlations in the vicinity of a Mott-Hubbard transition, may be the key ingredients of high-Tc superconductors.
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198
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Zhang Y, Wei J, Ou HW, Zhao JF, Zhou B, Chen F, Xu M, He C, Wu G, Chen H, Arita M, Shimada K, Namatame H, Taniguchi M, Chen XH, Feng DL. Unusual doping dependence of the electronic structure and coexistence of spin-density-wave and superconductor phases in single crystalline Sr1-xKxFe2As2. PHYSICAL REVIEW LETTERS 2009; 102:127003. [PMID: 19392313 DOI: 10.1103/physrevlett.102.127003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2008] [Indexed: 05/27/2023]
Abstract
The nature of the spin-density wave (SDW) and its relation with superconductivity are crucial issues in the newly discovered iron-pnictide superconductors. Particularly, it is unclear whether the superconducting phase and SDW are truly exclusive from each other. We here report splittings of the band structures in Sr1-xKxFe2As2 (x=0, 0.1, 0.18), and their unusual doping dependence. Our data on single crystalline samples prove that the SDW and superconductivity could coexist in iron pnictides.
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199
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Wang XF, Wu T, Wu G, Chen H, Xie YL, Ying JJ, Yan YJ, Liu RH, Chen XH. Anisotropy in the electrical resistivity and susceptibility of superconducting BaFe2As2 single crystals. PHYSICAL REVIEW LETTERS 2009; 102:117005. [PMID: 19392232 DOI: 10.1103/physrevlett.102.117005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2008] [Indexed: 05/27/2023]
Abstract
We report that sizable single crystals of BaFe2As2 have been grown with the self-flux method. Measurements and anisotropy of intrinsic transport and magnetic properties from high-quality single crystal are first presented. The resistivity anisotropy (rho{c}/rho{ab}) is as large as 150 and independent of temperature. In contrast to the susceptibility behavior observed in polycrystalline samples, no Curie-Weiss behavior is observed, and a linear-T dependent susceptibility occurs from the spin-density-wave transition temperature, (T{s}), to 700 K. This result suggests that strong antiferromagnetic correlations are present well above T{s}. A twofold symmetry of susceptibility in the ab plane indicates a stripelike spin structure as observed by neutron scattering. The resistivity minimum is strongly dependent on the magnetic field, suggesting that the upturn of the resistivity at low temperatures should be related to spin fluctuation.
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200
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Yang LX, Zhang Y, Ou HW, Zhao JF, Shen DW, Zhou B, Wei J, Chen F, Xu M, He C, Chen Y, Wang ZD, Wang XF, Wu T, Wu G, Chen XH, Arita M, Shimada K, Taniguchi M, Lu ZY, Xiang T, Feng DL. Electronic structure and unusual exchange splitting in the spin-density-wave state of the BaFe2As2 parent compound of iron-based superconductors. PHYSICAL REVIEW LETTERS 2009; 102:107002. [PMID: 19392146 DOI: 10.1103/physrevlett.102.107002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2008] [Indexed: 05/27/2023]
Abstract
The magnetic properties in the parent compounds are often intimately related to the microscopic mechanism of superconductivity. Here we report the first direct measurements on the electronic structure of a parent compound of the newly discovered iron-based superconductor, BaFe2As2, which provides a foundation for further studies. We show that the energy of the spin density wave in BaFe2As2 is mainly lowered through exotic exchange splitting of the band structure.
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