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1.
Nat Commun ; 14(1): 5613, 2023 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-37699909

RESUMO

Pursuing the exotic quantum spin liquid (QSL) state in the Kitaev material α-RuCl3 has intrigued great research interest recently. A fascinating question is on the possible existence of a field-induced QSL phase in this compound. Here we perform high-field magnetization measurements of α-RuCl3 up to 102 T employing the non-destructive and destructive pulsed magnets. Under the out-of-plane field along the c* axis (i.e., perpendicular to the honeycomb plane), two quantum phase transitions are uncovered at respectively 35 T and about 83 T, between which lies an intermediate phase as the predicted QSL. This is in sharp contrast to the case with in-plane fields, where a single transition is found at around 7 T and the intermediate QSL phase is absent instead. By measuring the magnetization data with fields tilted from the c* axis up to 90° (i.e., in-plane direction), we obtain the field-angle phase diagram that contains the zigzag, paramagnetic, and QSL phases. Based on the K-J-Γ-[Formula: see text] model for α-RuCl3 with a large Kitaev term we perform density matrix renormalization group simulations and reproduce the quantum phase diagram in excellent agreement with experiments.

2.
Proc Natl Acad Sci U S A ; 120(33): e2302756120, 2023 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-37549272

RESUMO

The mutual coupling of spin and lattice degrees of freedom is ubiquitous in magnetic materials and potentially creates exotic magnetic states in response to the external magnetic field. Particularly, geometrically frustrated magnets serve as a fertile playground for realizing magnetic superstructure phases. Here, we observe an unconventional two-step magnetostructural transition prior to a half-magnetization plateau in a breathing pyrochlore chromium spinel by means of state-of-the-art magnetization and magnetostriction measurements in ultrahigh magnetic fields available up to 600 T. Considering a microscopic magnetoelastic theory, the intermediate-field phase can be assigned to a magnetic superstructure with a three-dimensional periodic array of 3-up-1-down and canted 2-up-2-down spin molecules. We attribute the emergence of the magnetic superstructure to a unique combination of the strong spin-lattice coupling and large breathing anisotropy.

3.
Mol Med Rep ; 22(5): 4376-4382, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33000198

RESUMO

The neuropeptide Y (NPY) system is considered one of the primary neural signaling pathways. NPY, produced by osteoblasts and other peripheral tissues, is known to inhibit biological functions of osteoblasts. However, until recently, little was known of the autocrine mechanism by which NPY is regulated. To investigate this mechanism, overexpression plasmids and small interfering RNA (siRNA) targeting NPY were transfected into the MC3T3­E1 cell line to observe its effects on osteogenesis. NPY overexpression was found to markedly enhance the osteogenic ability of MC3T3­E1 cells by an autocrine mechanism, coincident with the upregulation of osterix and runt­related transcription factor 2 (Runx2). Furthermore, NPY increased the activities of alkaline phosphatase (ALP) and osteocalcin (OCN) by upregulating their osteoblastic expression in vitro (as well as that of osterix and Runx2). Following transfection with NPY­siRNA, the osteoblastic ability of MC3T3­E1 cells was markedly decreased, and NPY deficiency inhibited the protein expression of osterix, Runx2, OCN and ALP in primary osteoblasts. Collectively, these results indicated that NPY played an important role in osteoblast differentiation by regulating the osterix and Runx2 pathways.


Assuntos
Subunidade alfa 1 de Fator de Ligação ao Core/metabolismo , Neuropeptídeo Y/metabolismo , Osteogênese , Fator de Transcrição Sp7/metabolismo , Regulação para Cima , Fosfatase Alcalina/metabolismo , Animais , Comunicação Autócrina , Diferenciação Celular , Linhagem Celular , Camundongos , Neuropeptídeo Y/genética , Osteoblastos/citologia , Osteoblastos/efeitos dos fármacos , Osteoblastos/metabolismo , Osteocalcina/metabolismo , Osteogênese/efeitos dos fármacos , RNA Interferente Pequeno/farmacologia
4.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-793143

RESUMO

@# Objective: To investigate the short-term efficacy and toxicity of bevacizumab combined with DP or rh-endostatin(recombinant human vascular endostatin injection)combined with DP in locally advanced EGFR wild-type non-small cell lung cancer (NSCLC). Methods: Seventy-two patients with treatment of locally advanced EGFR wild-type NSCLC admitted to the Department of Respiratory Medicine of Zhongshan Hospital Affiliated to Guangdong Medical University from January 2014 to January 2017 were divided into bevacizumab group (34 cases) and rh-endostatin group (38 cases) according to the random number method. The former group was treated with bevacizumab combined with docetaxel and cisplatin, while the latter was treated with rh-endostatin combined with docetaxel and cisplatin. According to RECISIT 1.1 standard, the changes of lesion size before and after treatment in two groups were evaluated. Serum levels of vascular endothelial growth factor (VEGF), carcinoembryonic antigen (CEA), cytokeratin 21-1 fragment (CYFRA21-1), squamous cell carcinoma antigen (SCC) were measured. The adverse reactions during treatment were also evaluated. Results: In bevacizumab group, patients with CR, PR, SD, PD, DCR and ORR were 2 cases, 12 cases, 15 cases, 5 cases, 41.18% and 85.29%, respectively. In rh-endostatin group, patients with CR, PR, SD, PD, DCR, ORR were 2 cases, 16 cases, 14 cases, 6 cases, 47.37% and 84.21%, respectively. The DCR in rh-endostatin group was significantly higher than that in bevacizumab group (P<0.05).The serum levels of VEGF and CEAin rh-endostatin group decreased more obvious than those in bevacizumab group (all P<0.05). The incidence of gastrointestinal reaction, skin reaction and cardiac toxicity in rh-endostatin group was higher than that in bevacizumab group, while the incidence of bleeding in bevacizumab group was higher than that in rh-endostatin group (all P<0.05). Conclusion: In patients with locally advanced EGFR wild-type NSCLC, rh-endostatin combined with DP regimen is better than bevacizumab combined with DPregimen. In clinical practice, corresponding treatment regimen can be selected according to different characteristics of patients, so as to minimize the toxic reaction during treatment and avoid clinical risk.

5.
Mikrochim Acta ; 185(9): 424, 2018 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-30128831

RESUMO

Surface functional groups strongly affect the properties of carbon dots (CDs). Amino, carboxy, and hydroxy groups are most commonly encountered in CDs, and they can be introduced via covalent and noncovalent modification. This article (with 116 refs.) reviews the progress made in the past few years. Following an introduction into the field, a large section covers methods for covalent modification (via amide coupling reactions, silylation, and other reactions including esterification, sulfonylation and copolymerization). Next section reviews methods for noncovalent modifications (π interactions, complexation/chelation, and electrostatic interactions). The resulting modified CDs are powerful nanomaterials for targeting and extracting analytes, and in drug release. The modification of the surface also affects fluorescence quantum yields, complexation capacity, the color of fluorescence, and their quenching capability. Current challenges are critically assessed in the concluding section. Graphical abstract The modification methods of carbon dots (CDs) includes covalent and noncovalent. Covalent modifications include amidation, silylation, esterification, sulfonylation and copolymerization reaction. Noncovalent modifications include electrostatic interactions, complexation and π interactions.

6.
Spectrochim Acta A Mol Biomol Spectrosc ; 173: 854-862, 2017 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-27816885

RESUMO

Biomass is regarded as an excellent candidate for the preparation of heteroatom-doped carbon nanomaterials. We have developed a simple and facile one-pot synthesis of nitrogen and sulfur codoped fluorescent carbon dots from pigeon feathers, egg and manure via the pyrolysis carbonization method. The as-prepared four PCDs have high fluorescence quantum yield about 24.87% (PCDs-f), 17.48% (PCDs-w), 16.34% (PCDs-y), 33.50% (PCDs-m), respectively, which is higher than the other carbon dots preparing from biomass. We found that the preparation of PCDs-m with pigeon manure has no favourable selectively with heavy metal ions. However, other PCDs exhibit highly sensitive and selective detection behavior of Hg2+/Fe3+ ions with a low detection limit of 10.3 and 60.9nM. They were applied to imaging of human umbilical vein endothelial cells, showing low cytotoxicity and good biocompatibility.


Assuntos
Carbono/química , Ferro/análise , Mercúrio/análise , Pontos Quânticos/química , Animais , Columbidae , Esterco
7.
J Photochem Photobiol B ; 162: 1-13, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27323236

RESUMO

Nitrogen and boron co-doped carbon dots (BCNDs1-3) were prepared from three kinds of borate via a facile hydrothermal method. The as-prepared BCNDs did not shift with the change of excitation wavelength and possess good water dispersibility, strong fluorescence emission with high fluorescent quantum yield of 29.01%, 51.42%, 68.28%, respectively. Subsequently, these BCNDs were exploited as excellent Hg(2+) ion and 2,4,6-trinitrophenol (TNP) probe. The efficient selective detection of Hg(2+) can be attributed to non-radiative electron/hole recombination annihilation through an effective electron transfer process and the detection of TNP can be attributed to the fluorescence resonance energy transfer process (FRET). The results show that the BCNDs2 is the most sensitive fluorescence probe for Hg(2+) ions and TNP detection as low as Hg(2+) 7.3nM and TNP 0.35µM compared with BCNDs1 and BCNDs3. The as-prepared BCNDs possess the advantages of good selectivity, fast response and a broad linear detection. They were applied to sensing and imaging of human umbilical vein endothelial cells, showing low cytotoxicity and good biocompatibility.


Assuntos
Boro/análise , Carbono/química , Corantes Fluorescentes/química , Mercúrio/análise , Nitrogênio/análise , Picratos/análise , Transferência Ressonante de Energia de Fluorescência , Limite de Detecção , Microscopia Eletrônica de Transmissão , Espectrofotometria Ultravioleta
8.
ACS Appl Mater Interfaces ; 7(42): 23431-8, 2015 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-26457724

RESUMO

Blue oxygen-deficient nanoparticles of anatase TiO2 (H-TiO2) are synthesized using a modified hydrogenation process. Scanning electron microscope and transmission electron microscope images clearly demonstrate the evident change of the TiO2 morphology, from 60 nm rectangular nanosheets to much smaller round or oval nanoparticles of ∼17 nm, after this hydrogenation treatment. Importantly, electron paramagnetic resonance and positronium annihilation lifetime spectroscopy confirm that plentiful oxygen vacancies accompanied by Ti(3+) are created in the hydrogenated samples with a controllable concentration by altering hydrogenation temperature. Experiments and theory calculations demonstrate that the well-balanced Li(+)/e(-) transportation from a synergetic effect between Ti(3+)/oxygen vacancy and reduced size promises the optimal H-TiO2 sample a high specific capacity, as well as greatly enhanced cycling stability and rate performance in comparison with the other TiO2.

9.
Phys Chem Chem Phys ; 17(12): 8078-86, 2015 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-25728386

RESUMO

Hollow hierarchical microspheres of Bi/BiOBr (SBB) with oxygen vacancies were prepared using a one step solvothermal method. It was found that the stannous chloride dihydrate played key roles in the formation of Bi, defects and the stacking mode of hierarchical construction units. Positron annihilation lifetime spectroscopy (PALS) was used to demonstrate the oxygen vacancies in Bi/BiOBr samples. The density of states (DOS) of the valence band of BiOBr can be modulated by the introduction of oxygen vacancies according to the valence band XPS and Density Functional Theory (DFT) calculations. Analyses of photoluminescence and BET demonstrated that SBB hollow hierarchical microspheres with higher specific surface area have a lower recombination rate of photo-generated electrons and holes. The photocatalytic and adsorptive performances showed that the samples exhibited stronger adsorption capacity toward rhodamine B (RhB) and highly efficient photocatalytic activity in the degradation of RhB, which were attributed to the higher adsorption ability and synergistic effect of oxygen vacancies and construction of the heterojunction structure (Bi/BiOBr).

10.
Zhongguo Gu Shang ; 21(1): 42-5, 2008 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-19102273

RESUMO

OBJECTIVE: To prove the therapeutic effects of Sihuang powder (composed by four traditional Chinese herbs: root of baikal skullcap, bark of amur corktree, root of sorrel rhubarb, fruit of cape jasmine, which were mixed with wild Chrysanthemum flower solution)in treating acute synovitis in experimental rabbit knee osteoarthritic models induced by papain injection and to explore its mechanism. METHODS: Thirty-two New-Zealand white rabbits were divided into 6 groups: blank group, model group, Sihuang powder with high dosage group (2 g/kg), Sihuang powder with low dosage group (1 g/kg), Yingtaiqing group and wild Chrysanthemum flower group. The latter four groups were treated respectively with low and high dose Sihuang powder synovium and cartilage were tested concentrations of nitrogen monoxide (NO) and IL-1 level and then were prepared for pathologic and histologic observation 10 days later. Cartilage pathologic changes were record and synovium pathologic changes were valued by means of Mankin's value system. RESULTS: The NO concentration of synovium in Sihuang powder with high dosage group was lower than that of model group, and there was significantly differences between the two groups (P < 0.01). The IL-1 level of synovium was failed after treated with Sihuang powder with high dosage (P < 0.05). Sihuang powder with low dosage and Yingtaiqing also could restrain IL-1's release (P < 0.05). In Mankin's value system, Sihuang powder with high dosage almost eliminated inflammatory cells infiltrating in synovium, which was seldom found in other groups. The value of Sihuang powder with high dosage group was the lowest in treatment groups (P < 0.005). Sihuang powder with low dosage group and wild Chrysanthemum flower group also decreased the degree of inflammatory in synovium (P < 0.05). CONCLUSION: Sihuang powder can reduce the concentration of NO and IL-1 and improve inflammatory cell infiltrate in lining cells of synovium. Moreover, it can alleviate swelling and pain of joint, improve joint movement and postpone degeneration of the cartilage.


Assuntos
Medicamentos de Ervas Chinesas/uso terapêutico , Osteoartrite/tratamento farmacológico , Papaína/toxicidade , Sinovite/tratamento farmacológico , Doença Aguda , Animais , Feminino , Interleucina-1/análise , Óxido Nítrico/análise , Osteoartrite/patologia , Pós , Coelhos , Sinovite/induzido quimicamente , Sinovite/patologia
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