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1.
J Phys Condens Matter ; 36(33)2024 May 21.
Artículo en Inglés | MEDLINE | ID: mdl-38729186

RESUMEN

Spin reorientation transition is an ubiquitous phenomenon observed in magnetic rare earth orthferrites RFeO3, which has garnered significant attention in recent years due to its potential applications in spintronics or magnetoelectric devices. Although a plenty of experimental works suggest that the magnetic interaction between R3+and Fe3+spins is at the heart of the spin reorientation, but a direct and conclusive theoretical support has been lacking thus far, primarily due to the challenging nature of handling R 4felectrons. In this paper, we explored DyFeO3as an example by means of comprehensive first principles calculations, and compared two different approaches, where the Dy 4felectrons were treated separately as core or valence states, aiming to elucidate the role of Dy 4felectrons, particularly in the context of the spin reorientation transition. The comparison provides a solid piece of evidence for the experimental argument that the Dy3+-Fe3+magnetic interactions play a vital role in triggering spin reorientation of Fe3+moments at low temperatures. The findings revealed here not only extend our understanding on the underlying mechanism for spin reorientation transition in RFeO3, but also highlight the importance of explicit description of R 4felectrons in rationally reproducing their structural, electronic and magnetic properties.

2.
Phys Chem Chem Phys ; 26(11): 8824-8833, 2024 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-38425316

RESUMEN

By means of ab initio density functional theory calculations taking into account electronic correlation and van der Waals force, we conducted comprehensive studies of the electronic and magnetic properties, as well as structural and magnetic ordering evolution under pressure of the square lattice antiferromagnets AMoOPO4Cl (A = K, Rb) containing Mo5+ ions with , theoretically predicted as the potential candidates for achieving quantum phases, existing in the boundary regimes for square lattice magnets. Our results indicate that the columnar antiferromagnetic ordering, experimentally determined, is the magnetic ground state of the ambient P4/nmm phase, stabilized by the predominant antiferromagnetic next nearest neighbor interaction J2 in the diagonal directions of the square lattice, regardless of the effective Hubbard amendment values. More importantly, the P4/n phase, involving the mutual twisting of the MoO5Cl and PO4 polyhedra, satisfactorily reproduces the experimentally observed structural transition and the subsequent magnetic ordering transition from columnar antiferromagnetic ordering to Néel antiferromagnetic one, identified to be the appropriate high pressure structure. Furthermore, the mechanism underlined responsible for the magnetic ordering transition at high pressure has been disclosed in terms of density of states and spin density isosurface analysis across the transition. The loss of mirror plane symmetry in the P4/n phase activates the P 3s orbitals to participate in the magnetic interaction, giving rise to a competitive ferromagnetic superexchange interaction, in addition to antiferromagnetic direct one, and consequently initiating the magnetic ordering transition. The insights revealed here not only deepen our understanding of the electronic properties and structural and magnetic ordering transitions under high pressure of square lattice antiferromagnets AMoOPO4Cl (A = K, Rb), but also push the boundaries of knowledge by recognizing the role of nonmagnetic ions P 3s in magnetic exchange coupling.

3.
J Ethnopharmacol ; 324: 117789, 2024 Apr 24.
Artículo en Inglés | MEDLINE | ID: mdl-38266950

RESUMEN

ETHNOPHARMACOLOGICAL RELEVANCE: "Snow-white waterlily" (Nymphaea candida) dried flower possesses various efficacy in Uighur medicine such as reducing fever and nourishing the liver, anti-inflammatory and cough relieving, moistening the throat and quenching thirst. AIM OF THE STUDY: Polyphenols are characteristic component of N. candida as well as its quality markers, and the purpose of this study was to conduct investigations into anti-inflammatory, antitussive, antipyretic, and analgesic activities of the polyphenol-enriched fraction from N. candida (NCTP) in order to validate the traditional efficacy of this plant. MATERIALS AND METHODS: The polyphenols in NCTP were analyzed by HPLC, and an acute oral toxicity study was conducted for NCTP. The anti-inflammatory activities of NCTP were evaluated using xylene induced ear edema, capillary permeability, cotton pellet granuloma, and carrageenan-induced rat paw edema, of which multiple biochemical indices were measured in carrageenan-induced rat paw edema such as prostaglandin E2 (PGE2), cyclooxygenase-2 (COX-2),5-lipoxygenase (5-LOX), interleukin-6 (IL-6), interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH) activities; the analgesic activities were investigated using acetic acid writhing, hot plate test, and formalin test; the anti-tussive and antipyretic effects were tested by ammonia induced cough in mice and yeast-induced fever respectively. RESULTS: NCTP with LD50 of 5222 mg/kg was low toxicity and safety. NCTP (200 mg/kg) could significantly reduce ear swelling and capillary permeability by 30.63% and 31.37%, respectively. NCTP revealed 15.76% inhibiting activities in cotton pellet granuloma in mice at a dosage of 200 mg/kg. Furthermore, NCTP (50, 100, and 200 mg/kg) substantially decreased carrageenin-induced paw edema in rats between 1 and 5 h, and NCTP could decrease PGE2, 5-LOX, COX-2 levels as well as IL-6, IL-1ß, TNF-α activities compared with the control group; NCTP could decrease MDA contents in carrageenin-induced rise, and increase SOD and GSH activities. Furthermore, the dose-dependent inhibition effect of NCTP on pain was revealed in the hot plate experiment. In addition to reducing the amount of writhes brought on by acetic acid, NCTP (50, 100, and 200 mg/kg) significantly inhibited pain latency against both stages of the formalin test. Moreover, NCTP (50, 100, 200 mg/kg) showed the better antitussive activities in mice in a dose-dependent manner. In the yeast-induced pyrexia test, dosages of 50, 100, and 200 mg/kg resulted in a statistically significant drop in rectal temperature. CONCLUSION: The experimental results proved the analgesic, anti-inflammatory, anti-tussive and antipyretic activities of the polyphenol-enriched fraction from N. candida, and supported the traditional use of this plant as well.


Asunto(s)
Antipiréticos , Antitusígenos , Nymphaea , Ratas , Ratones , Animales , Antipiréticos/farmacología , Antipiréticos/uso terapéutico , Antipiréticos/química , Carragenina , Antitusígenos/uso terapéutico , Polifenoles/farmacología , Polifenoles/uso terapéutico , Factor de Necrosis Tumoral alfa , Saccharomyces cerevisiae , Interleucina-6 , Ciclooxigenasa 2 , Dinoprostona , Extractos Vegetales/uso terapéutico , Extractos Vegetales/toxicidad , Antiinflamatorios/efectos adversos , Analgésicos/farmacología , Analgésicos/uso terapéutico , Analgésicos/química , Dolor/tratamiento farmacológico , Antiinflamatorios no Esteroideos/uso terapéutico , Edema/inducido químicamente , Edema/tratamiento farmacológico , Edema/patología , Acetatos , Tos/tratamiento farmacológico , Granuloma/tratamiento farmacológico , Superóxido Dismutasa
4.
Heart Lung ; 63: 108-113, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-37844535

RESUMEN

BACKGROUND: Based on the findings of current observational studies, asthma and inflammatory bowel disease (including Crohn's disease and ulcerative colitis) are associated; however, their causal association cannot be established due to methodological limitations. OBJECTIVES: we use two-sample bidirectional mendelian randomization (MR) to overcome the confounding factors and explore the causal link between asthma and inflammatory bowel disease. METHODS: After selecting asthma and IBD-related genome-wide association studies (GWAS) data and screening single nucleotide polymorphisms (SNPs), MR analysis was performed by four methods: inverse variance weighted (IVW), MR-Egger, maximum likelihood, and weighted median (WM), while Cochran's Q test was used to detect heterogeneity and MR-Egger intercept to detect horizontal pleiotropy. Finally, we used the leave-one-out method and funnel plot to perform sensitivity analysis. RESULTS: We screened 57, 59, and 60 SNPs in the association analysis of asthma and IBD, CD, and UC, respectively. The results of MR analysis showed that asthma only increased the risk of CD (IVW: OR = 1.1712, 95% CI = 1.0418-1.3167, P value = 0.0082; maximum likelihood: OR = 1.1739, 95% CI = 1.0428-1.3215, P value = 0.0080). Neither forward nor reverse MR analysis revealed heterogeneity or horizontal pleiotropy. Similarly, we did not find potential directional pleiotropy by funnel plot, and the leave-one-out method did not suggest a significant effect of a single SNP on the overall results. CONCLUSIONS: we found a negative correlation between asthma and Crohn's disease, but more research is needed to confirm this.


Asunto(s)
Asma , Enfermedad de Crohn , Enfermedades Inflamatorias del Intestino , Humanos , Enfermedad de Crohn/genética , Análisis de la Aleatorización Mendeliana , Estudio de Asociación del Genoma Completo , Enfermedades Inflamatorias del Intestino/complicaciones , Enfermedades Inflamatorias del Intestino/genética , Asma/epidemiología , Asma/genética
5.
J Biochem Mol Toxicol ; 38(1): e23594, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38050438

RESUMEN

The role of LINC01703 in cancers, especially in colorectal cancer (CRC), is still largely unclear. Bioinformatics prediction, real-time quantitative polymerase chain reaction (RT-qPCR), 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay, colony formation assay, Transwell assays, in vivo animal experiments, IF, luciferase reporter assay, and Western blot were carried out for the exploration of the potential involvement and underlying molecular mechanisms of LINC01703 in CRC cells. The results showed that LINC01703 appeared upregulated in CRC and was linked to poor prognosis. LINC01703 acted as an oncogene in both in vitro and in vivo CRC cell environments. LINC01703 activated the PI3K/AKT signaling pathway by mediating the miR-205-5p/E2F1 axis in CRC. In summary, LINC01703 possesses an oncogenic function and can be a possible biomarker or target to treat CRC.


Asunto(s)
Neoplasias Colorrectales , MicroARNs , ARN Largo no Codificante , Animales , Proteínas Proto-Oncogénicas c-akt/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , ARN Largo no Codificante/genética , ARN Largo no Codificante/metabolismo , Línea Celular Tumoral , Proliferación Celular/genética , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/metabolismo , Invasividad Neoplásica , MicroARNs/genética , MicroARNs/metabolismo , Movimiento Celular/genética
6.
J Immunol Res ; 2023: 5577850, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37781475

RESUMEN

There remains a lack of standard models that have all the characteristics of human diseases. Especially in immunological hepatic fibrosis, the bovine serum albumin (BSA)-induced liver fibrosis models have the same developmental mechanisms as human liver fibrosis models, but have received little attention. We standardized a BSA-induced liver fibrosis model in rats and thoroughly assessed its pathological characteristics. We also used 16S sequencing to assess homeostasis of the intestinal microflora of rats with BSA-induced liver fibrosis and detected various differential metabolites in the serum of these rats using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). We observed stable and unambiguous histological changes in liver tissue morphology and remarkably high concentrations of inflammatory markers in the serum of BSA-induced liver fibrosis rats. In keeping with the fact that BSA induction can cause gut microbiota disorders in rats. UHPLC-MS/MS analysis of rat serum samples in positive-ion mode and negative-ion mode revealed 17 and 25 differential metabolites, respectively. Network analysis revealed that phenylalanine or tyrosine metabolites (e.g., PAGln) were the predominant metabolites in the sera of BSA-induced liver fibrosis rats. Taken together, our results suggest that disorders of amino acid metabolism caused by the gut microbiota may play an important role in the progression of immunological hepatic fibrosis.


Asunto(s)
Cirrosis Hepática , Espectrometría de Masas en Tándem , Ratas , Humanos , Animales , Espectrometría de Masas en Tándem/métodos , Cirrosis Hepática/patología , Metaboloma , Cromatografía Líquida de Alta Presión/métodos
7.
J Phys Condens Matter ; 35(49)2023 Sep 13.
Artículo en Inglés | MEDLINE | ID: mdl-37669647

RESUMEN

Structural, electronic and magnetic properties of ilmenite-type CoVO3have been explored via the generalized gradient approximation + effective HubbardUeffcorrection, in the framework of density functional theory. Our results indicate that high temperature rhombohedralR3-phase is metallic with oxidation states and electronic configurations Co2+(t2g↑3eg↑2t2g↓2eg↓0), V4+(t2g↑1eg↑0t2g↓0eg↓0), respectively, while low temperature triclinicP1-phase, induced from spin-Peierls transition in the V-V dimerization manner, is insulating, maintaining charge and electronic states unchanged. Furthermore, the A-type antiferromagnetic ordering, where the ferromagnetic honeycomb layers are anti-aligned along the stacking axis, is identified to be the magnetic ground state for the low temperature phase, in nice agreement with experimental findings, analogous to CoTiO3. The unexpected intralayer ferromagnetic couplings can be attributed to the intraorbitalt2g-t2gexchange coupling, which was assumed to be small earlier and ignored, but actually large in honeycomb cobaltates with 3d7electronic configuration. In addition, the computed magnetic moment on Co2+ion ranges from 2.5 to 2.7µB, HubbardUeffdependent, close to idealS= 3/2 state, rather than the anticipatedJeff= 1/2 state. Furthermore, the supplemental calculations, taking spin-orbit coupling (SOC) into account, uncover faint orbital moments of 0.21-0.27µBat the Co site, illustrating the insignificance of SOC. Except for the inevitable trigonal distortions, the excessive structural distortion triggered by the formation V-V dimerization, i.e. the breaking of trigonal symmetry around Co2+, further lifts the degeneracy oft2gorbitals and increases crystal field splitting, driving it away from potential candidates for realizing Kitaev model physics.

8.
Inorg Chem ; 61(51): 21011-21015, 2022 Dec 26.
Artículo en Inglés | MEDLINE | ID: mdl-36517465

RESUMEN

CdMnO3 had not been previously reported and was a missing piece in the A2+Mn4+O3 series. We succeeded in synthesizing this compound by a high-pressure method and confirmed that it is crystallized in a distorted perovskite structure with a Cd2+Mn4+O3 charge configuration. The obtained insulating CdMnO3 exhibits an antiferromagnetic transition at about 86 K. First-principles calculations revealed that the Mn4+ (t2g3) spins form a C-type antiferromagnetic structure, which is in sharp contrast to the G-type antiferromagnetism in the isostructural and isoelectronic CaMnO3. Significant overlap of the Mn-3d and O(2)-2p orbitals produces distorted octahedra with a large Mn-O(1)-Mn tilt and induces antiferromagnetic couplings in the ac plane and the ferromagnetic couplings along the b axis.

9.
Front Plant Sci ; 13: 908035, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36275577

RESUMEN

Soil water repellency (SWR) is a physical phenomenon whereby water cannot penetrate or has difficulty penetrating the soil surface. There are many factors involved in its occurrence, but the main factors controlling its emergence in loess remain unclear. In this work, we have studied numerous physicochemical and biological factors functioning in different dominant vegetations (Pinus tabulaeformis Carr., Robinia pseudoacacia L., and Hippophae rhamnoides L.) in a loess hilly region by gas chromatography-mass spectrometry (GC-MS) and high-throughput sequencing techniques. We observed that more than 75% of the soils under Robinia and Hippophae are categorized as slightly or strongly water repellent, while nearly 50% of the soils under Pinus are categorized as severely to extremely water repellent. The relative concentrations of total free lipids in the soil in the same water-repellency class were Pinus > Robinia > Hippophae, where fatty acids, alkanols, and sterols were positively correlated with SWR, whereas alkanes were not. For the abundance and diversity index of bacterial and fungal communities, the three species ranked in the following order: Robinia ≈ Hippophae > Pinus. Thus, solvent-extractable polar waxes were indicated to be better preserved in water-repellent soils under Pinus due to lower microbial diversity than Robinia and Hippophae. Here, we demonstrate polar waxes to be the principal factor controlling SWR. Moreover, the dominant phyla of fungi varied greatly than those of bacteria under three vegetation types. Correlation analysis showed that the abundance of Actinobacteria in dominant bacteria increased with SWR. Nonmetric multidimensional scaling suggested the fungal community in different water-repellent soils under Pinus to vary more than those under Robinia and Hippophae. The indicator species mainly belonged to Actinobacteria in bacteria and Basidiomycota in fungi at the phylum level; this finding was further supported by the linear discriminant analysis (LDA) effect size (LEfSe). Additionally, GC-MS identified a small amount of ergosterol, a specific biomarker of fungi under Pinus. These pieces of evidence collectively reveal that severe to extreme SWR occurs under Pinus and appears to be the most influenced by fungi and actinomycetes when the topsoil is close to air drying. However, there is a need for further testing on different plant species or land use.

10.
Inorg Chem ; 61(38): 15007-15015, 2022 Sep 26.
Artículo en Inglés | MEDLINE | ID: mdl-36095280

RESUMEN

By means of density functional theory calculations with the inclusion of spin-orbit coupling, we present a comprehensive investigation of the structural, electronic, and magnetic properties of the novel series of ilmenite-type honeycomb lattice iridates MIrO3 (M = Cd, Zn, and Mg), the potential candidates for realizing the quantum spin liquid. Our findings are as follows: (i) the structural relaxations could not properly capture the abnormal thin two-dimensional honeycomb IrO6 layers in CdIrO3, making the experimentally proposed crystal structure questionable. Furthermore, the calculations within the experimental structure could not correctly determine the magnetic ground state; however, the results within the optimized one rectify this scenario and provide a precise and reasonable description of its electronic and magnetic properties, which is in good agreement with the experimental observations and that of Zn and Mg analogues. In this regard, we hope that our report will inspire additional studies on this issue and eventually resolve the crystal structure of CdIrO3. (ii) We identified that the magnetic ground state of this series of iridates MIrO3 is the zigzag antiferromagnetic ordering, where ferromagnetic zigzag chains are coupling antiferromagnetically across the bridging bonds within a hexagon. (iii) Though it is widely assumed that all the iridates can be well described based on the spin-orbit-assisted Jeff = 1/2 Mott insulating state model, detailed analysis of electronic band structures indicates that the formation of quasimolecular orbitals (QMOs) within a hexagon plays a non-negligible role in appropriately depicting the electronic and magnetic properties. Finally, (iv) we found that all the antiferromagnetic patterns are insulating with finite band gaps. Clarifying the effect of magnetic ordering on the electronic structures is important because it reminds us of potential erroneous identification/prediction of the ground state. The results suggest that precisely determining the magnetic ground state and adopting it in the simulations are imperative for faithfully rendering the electronic properties of a compound. Our results underline the importance of structural factor, spin-orbit coupling, correlation correction, the formation of the QMOs within the hexagon, as well as magnetic ordering in elucidating the electronic structure of a series of ilmenite-type honeycomb lattice iridates MIrO3.

11.
Angew Chem Int Ed Engl ; 61(25): e202203669, 2022 Jun 20.
Artículo en Inglés | MEDLINE | ID: mdl-35384197

RESUMEN

The ambient pressure cation disordered InVO3 bixbyite has been predicted to form a GdFeO3 -type perovskite phase under high pressure and high temperature. Contrary to the expectation, InVO3 was found to crystallize in the polar LiNbO3 -type structure with a calculated spontaneous polarization as large as 74 µC cm-2 . Antiferromagnetic coupling of V3+ magnetic moments and a cooperative magnetic ground state below about 10 K coupled with a polar structure suggest an intriguing ground state of the novel LiNbO3 -type high-pressure InVO3 structure.

12.
Dalton Trans ; 50(13): 4673-4679, 2021 Apr 07.
Artículo en Inglés | MEDLINE | ID: mdl-33725051

RESUMEN

From our material exploration study in wide pressure and temperature conditions, we found a new 6H polymorph of BaRhO3 was stabilised under high pressure conditions from 14 to 22 GPa. The material crystallised in the monoclinic 6H hexagonal perovskite structure in space group C2/c. The 4H BaRhO3 polymorph was stabilised at lower pressures, but the 3C cubic BaRhO3 likely requires pressures greater than 22 GPa. Both 6H and 4H polymorphs contain Rh2O9 dimers and the large 4d Rh orbital spatial diffusivity in these dimers leads to Pauli paramagnetic and metallic ground states, which are also supported by first-principles electronic structure calculations. High Wilson ratios of approximately 2 for either compound indicate strong electron correlation.

13.
Inorg Chem ; 59(22): 16205-16214, 2020 Nov 16.
Artículo en Inglés | MEDLINE | ID: mdl-33121244

RESUMEN

The ilmenite-type MgMnO3 and ZnMnO3 with honeycomb Mn layers exhibit distinctive magnetic ground states. In experiments, MgMnO3 exhibits a Néel antiferromagnetic alignment, in which both nearest-neighbor (NN) J1 and next-nearest-neighbor (NNN) J2 exchange interactions are antiferromagnetic, while ZnMnO3 has zigzag antiferromagnetic ordering with NN ferromagnetic and NNN antiferromagnetic coupling. On the basis of ab initio band structure calculations, we explain the deviation of NN J1 exchange coupling from antiferromagnetic (MgMnO3) to ferromagnetic (ZnMnO3) as originating from the intensive hybridization between the occupied Zn 3d10 orbitals with those of the bridging O 2p states, strongly depending on the position of the orbitals. In addition, our results indicate that, in combination with the NN J1 coupling, the considerably large third-nearest-neighbor (TNN) J3 exchange interaction plays an important role in erecting the magnetic ground states, rather than the experimentally proposed NNN J2. Furthermore, our findings highlight the important role of not only the electronic configurations but also the positions of the nonmagnetic cations in determining the essence of the magnetic exchange interactions. Therefore, the hybridization effect of nonmagnetic cations should not be dismissed in an analysis of the magnetic properties of transition-metal oxides.

14.
Artículo en Inglés | MEDLINE | ID: mdl-29916823

RESUMEN

Typographical errors are present in the Table 2 of the paper stated above. The correct table is give below. All numerical results and conclusions of the paper remains unchanged.

15.
J Phys Condens Matter ; 29(31): 315501, 2017 Aug 09.
Artículo en Inglés | MEDLINE | ID: mdl-28653658

RESUMEN

The structural, electronic and magnetic properties of a charge-ordered iron fluoride material CsFe2+Fe3+F6 have been explored by density functional theory calculations based on the generalized gradient approximation + U approach, which was implemented in the VASP code. The material exhibits a 3D pyrochlore-related structure which consists of corner-shared Fe2+F6 and Fe3+F6 octahedra. Our results confirm that CsFe2F6 is a Mott-Hubbard insulator, and bears a magnetically frustrated ground state in which the localized 3d electrons are antiferromagnetically coupled between the homogeneous Fe ions (Fe3+-Fe3+ along the b axis, and Fe2+-Fe2+ along the a axis), while interactions between the heterogeneous Fe ions (Fe3+-Fe2+ along the c axis) are frustrated, consistent with Goodenough-Kanamori superexchange interactions. Although the disproportionation of the total 3d charge is extremely low, explicit evidence is provided on the charge ordering by an order parameter, which is defined as the difference in minority d yz orbital (in the local coordinates) occupations between the Fe3+ and Fe2+ cations. In addition, spin ordering and the spin-orbit coupling effect play an insignificant role in the charge ordering and the preferential occupation of the d yz orbital scenario in CsFe2F6.

16.
J Phys Condens Matter ; 29(10): 105801, 2017 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-28145278

RESUMEN

In this work, we comparatively explored the electronic structure and the low-dimensional magnetic interactions of double-perovskite compounds Sr2CuTeO6 and Sr2CuWO6 through first-principles calculations. The electronic structure calculations indicate that the Cu2+ (3d 9) site is the only magnetic active one, whereas Te6+ and W6+ remain in nonmagnetic states with d 10 and d 0 electronic configurations, respectively. The magnetic exchange interactions have been evaluated on the basis of the classical Heisenberg model. Both Sr2CuTeO6 and Sr2CuWO6 should be strong frustrated 2D magnetism, in excellent agreement with the experimental observations. Nevertheless, the nearest-neighbor antiferromagnetic interaction J 1 plays a determined role in constructing the Néel antiferromagnetic ordering within the square Cu2+ framework of Sr2CuTeO6. While, the next-nearest-neighbor antiferromagnetic interaction J 2 transcends the nearest-neighbor interaction J 1, establishes the collinear antiferromagnetic ordering in Sr2CuWO6. The discrimination has been explored and analyzed in detail using density of states, charge density as well as spin density analysis.

17.
Inorg Chem ; 52(2): 1032-9, 2013 Jan 18.
Artículo en Inglés | MEDLINE | ID: mdl-23301906

RESUMEN

By means of first-principles calculations based on density functional theory (DFT) and hybrid functional, we studied the structural, electronic, and ferroelectric properties of the two recently synthesized high-pressure perovskite-type (orthorhombic, space group Pnma) and LiNbO(3)-type (rhombohedral, space group R3c) polymorphs of CdPbO(3). Besides providing structural and electronic results in good agreement with available experiments, our results are able to correctly describe the pressure-induced Pnma → R3c structural phase transition and most importantly predict the realization of proper ferroelectric behavior in LiNbO(3)-type CdPbO(3) with an electric polarization of 52.3 µC/cm(2). The proper covalent interaction mechanism driving the ferroelectric transition is discussed and explained in terms of the analysis of Born effective charges, potential-energy surfaces, charge density isosurfaces, and electric localization function.

18.
J Phys Condens Matter ; 24(23): 236003, 2012 Jun 13.
Artículo en Inglés | MEDLINE | ID: mdl-22569174

RESUMEN

The electronic structure and magnetism of layered oxyselenide La(2)Mn(2)Se(2)O(3) have been studied by using first-principles calculations within the generalized gradient approximation (GGA) and GGA + U methods. The G-type antiferromagnetic (AF) state is calculated to be the most stable phase among the various magnetic configurations of interest, irrespective of the choice of the functional used, which is in good agreement with the experiments. In contrast to La(2)Fe(2)Se(2)O(3) and La(2)Co(2)Se(2)O(3), in which the AF states show metallic behavior under the GGA method, we predict the ground state of La(2)Mn(2)Se(2)O(3) is a semiconductor with an indirect band gap of ∼0.52 eV via the GGA calculations. This is closely related to a closed shell configuration and large exchange splitting (∼3.5 eV) in the Mn 3d states. Moreover, the magnetic properties are also discussed in terms of the calculated Heisenberg spin exchange constants, suggesting that La(2)Mn(2)Se(2)O(3) is a strong two-dimensional magnetically frustrated system.

19.
J Phys Condens Matter ; 23(12): 125501, 2011 Mar 30.
Artículo en Inglés | MEDLINE | ID: mdl-21386373

RESUMEN

Using first-principles total energy calculations we investigate the structural, elastic and electronic properties of new hypothetical oP(12)-type phase RuB(2) and OsB(2). The calculations indicate that the oP(12)-type phase RuB(2) and OsB(2) are thermodynamically and mechanically stable. Remarkably, the new phases RuB(2) and OsB(2) are predicted to be semiconductors, and the appearance of band gaps is ascribed to the enhanced B-B covalent hybridization. Compared to metallic oP(6)-type RuB(2) and OsB(2) phases, the new phases possess similar mechanical properties and hardness. The combination of the probability of tunable electronic properties, strong stiffness and high hardness make RuB(2) and OsB(2) attractive and interesting for advanced applications.

20.
Artículo en Chino | MEDLINE | ID: mdl-22295534

RESUMEN

OBJECTIVE: To explore the role of c-src on the initiation of primordial follicles. METHODS: 2-days-old female SD rats' ovaries were cultured in Waymouth culture system and were used HE staining and immunohistochemy to observe the number of follicles after 0, 4, 8 days cultured. Use chemically synthesized small interference RNA (siRNA) transfected into ovarian tissue in cultured for RNA interference, and use HE staining and RT-PCR to detect the best siRNA and packaging it by lentiviruses to test the interference effect. RESULTS: With the increase of culturing days, the nummber of the primordial follicles in ovarian gradually reduced. We packed the best siRNA by lentiviruses to doing RNA interference and found comparing with the blank control group and blank vector group, c-src mRNA of the best interference group were significantly decreased. The total number of primordial follicles was relatively greater and the development of primordial folliculars was inhibited. CONCLUSION: c-src plays an important role in primordial follicle development and folliculogenesis initiation.


Asunto(s)
Folículo Ovárico/crecimiento & desarrollo , Ovario/crecimiento & desarrollo , Proteínas Proto-Oncogénicas pp60(c-src)/fisiología , ARN Interferente Pequeño/genética , Animales , Animales Recién Nacidos , Secuencia de Bases , Técnicas de Cultivo , Femenino , Datos de Secuencia Molecular , Folículo Ovárico/metabolismo , Ovario/metabolismo , Proteínas Proto-Oncogénicas pp60(c-src)/genética , Interferencia de ARN , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Transfección
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