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1.
J Phys Condens Matter ; 36(22)2024 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-38373351

RESUMO

The strong geometric frustration of the kagome antiferromagnets (KAFMs) can destabilise conventional magnetic order and lead to exotic electronic states, such as the quantum spin-liquid state observed in someS=12KAFM materials. However, the ground state ofS = 1 KAFM systems are less well understood. Spin nematic phases and valence bond solid ground states have been predicted to form but a paucity of experimental realisations restricts understanding. Here, theS = 1 KAFM NH4Ni2Mo2O10H3is presented, which has the 3-fold symmetry of the kagome lattice but significant site depletion, with∼64%site occupancy. Frustration and a competition between exchange interactions are evidenced through the suppression of order below the Weiss temperature|θW|and observation of ferromagnetic and antiferromagnetic characteristics in the magnetisation data. A semi spin glass ground state is predicted based on the ac-field frequency dependence of the magnetic transition and ferromagnetic signal.

2.
Phys Rev Lett ; 121(10): 107203, 2018 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-30240241

RESUMO

The spin-1/2 kagome antiferromagnet is an archetypal frustrated system predicted to host a variety of exotic magnetic states. We show using neutron scattering measurements that deuterated vesignieite BaCu_{3}V_{2}O_{8}(OD)_{2}, a fully stoichiometric S=1/2 kagome magnet with <1% lattice distortion, orders magnetically at T_{N}=9 K into a multi-k coplanar variant of the predicted triple-k octahedral structure. We find that this structure is stabilized by a dominant antiferromagnetic third-neighbor exchange J_{3} with minor first- or second-neighbor exchanges. The spin-wave spectrum is well described by a J_{3}-only model including a tiny symmetric exchange anisotropy.

3.
J Phys Condens Matter ; 30(2): 025801, 2018 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-29226845

RESUMO

Kagome antiferromagnets (KAFMs) have long been known to host exotic electronic states due to their strong geometric frustration, including the quantum spin liquid state in [Formula: see text] systems. Away from that limit, S = 1 KAFMs are also predicted to host unconventional ground states such as spin nematic phases, but a paucity of studies on known model materials has restricted progress. Here, we present the crystal structure and preliminary magnetization measurements on the newly synthesized S = 1 KAFM, NH4Ni2.5V2O7(OH)[Formula: see text]H2O, which has the three-fold symmetry of the kagome lattice but significant site depletion, with ∼[Formula: see text] site occupancy. Bulk magnetic data show clear evidence of frustration and competition between ferromagnetic and antiferromagnetic interactions. We propose that the magnetic Hamiltonian is frustrated and that anisotropic terms cause the formation of an unconventional ground state.

4.
Allergy ; 66(1): 132-40, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20659080

RESUMO

BACKGROUND: Glucocorticoids (GCs) may affect the expression of hundreds of genes in different cells and tissues from patients with intermittent allergic rhinitis (IAR). It is a formidable challenge to understand these complex changes by studying individual genes. In this study, we aimed to identify (i) pathways affected by local GC treatment and (ii) examine if those pathways could be used to find novel markers of local GC treatment in nasal fluids from patients with IAR. METHODS: Gene expression microarray- and iTRAQ-based proteomic analyses of nasal fluids, nasal fluid cells and nasal mucosa from patients with IAR were performed to find pathways enriched for differentially expressed genes and proteins. Proteins representing those pathways were analyzed with ELISA in an independent material of nasal fluids from 23 patients with IAR before and after treatment with a local GC. RESULTS: Transcriptomal and proteomic high-throughput analyses of nasal fluids, nasal fluid cells and nasal mucosal showed that local GC treatment affected a wide variety of pathways in IAR such as the glucocorticoid receptor pathway and the acute phase response pathway. Extracellular proteins encoded by genes in those pathways were analyzed in an independent material of nasal fluids from patients. Proteins that changed significantly in expression included known biomarkers such as eosinophil cationic protein but also proteins that had not been previously described in IAR, namely CCL2, M-CSF, CXCL6 and apoH. CONCLUSION: Pathway-based analyses of genomic and proteomic high-throughput data can be used as a complementary approach to identify novel potential markers of GC treatment in IAR.


Assuntos
Biomarcadores/metabolismo , Glucocorticoides/uso terapêutico , Análise de Sequência com Séries de Oligonucleotídeos , Proteômica , Rinite Alérgica Sazonal/tratamento farmacológico , Adulto , Feminino , Perfilação da Expressão Gênica , Genômica , Ensaios de Triagem em Larga Escala , Humanos , Masculino , Líquido da Lavagem Nasal/imunologia , Mucosa Nasal/imunologia , Mucosa Nasal/metabolismo , Rinite Alérgica Sazonal/metabolismo , Adulto Jovem
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