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1.
Nano Lett ; 2020 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-32004008

RESUMO

We report the control of the interplane magnetic exchange coupling in CaIrO3 perovskite thin films and superlattices with SrTiO3. By analyzing the anisotropic magneto-transport data, we demonstrate that a semimetallic paramagnetic CaIrO3 turns into a canted antiferromagnetic Mott insulator at reduced dimensions. The emergence of a biaxial magneto-crystalline anisotropy indicates the canted moment responding to the cubic symmetry. Extending to superlattices and probing oxygen octahedral rotation by half-integer X-ray Braggs diffraction, a more complete picture about the canted moment evolution with interplane coupling can be understood. Remarkably, a rotation of the canted moments' easy axes by 45° is also observed by a sign reversal of the in-plane strain. These results demonstrate the robustness of anisotropic magnetoresistance in revealing quasi two-dimensional canted antiferromagnets, as well as valuable insights about quadrupolar magnetoelastic coupling, relevant for designing future antiferromagnetic spintronic devices.

2.
Luminescence ; 2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31908148

RESUMO

Two new difluoroboron ß-carbonyl cyclic ketonate complexes C2B and DC2B were investigated using several spectroscopic methods. Relative to the absorption spectra, the fluorescence spectra were more affected by the polarity of the solvent. Also, compound C2B showed a more pronounced Stokes' shift after solvent polarity increased. Transient absorption measurements then demonstrated the relaxation behaviour of the excited state compound molecule. The kinetic results showed that the excited state C2B in tetrahydrofuran (THF) can return from the intramolecular charge-transfer (ICT) state and the initial excited state to the ground state. The kinetic relaxation pathway after THF was replaced by dimethyl sulfoxide became single. When the carbazole unit was introduced, DC2B also exhibited an ICT state but there was no significant difference in the excited state relaxation path after solvent polarity was changed. The results indicated that C2B is more susceptible to solvent polarity regulation. The global fit results revealed that an increase in the solvent polarity prolonged the lifetime of the ICT state of compound C2B and had the opposite effect on compound DC2B. These results provide guidance for understanding the relationship between solvent polarity and the designing and synthesizing advanced compound materials.

3.
Chin J Integr Med ; 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31919749

RESUMO

OBJECTIVE: To evaluate the effects of a 48-week course of adefovir dipivoxil (ADV) plus Chinese medicine (CM) therapy, namely Tiaogan Jianpi Hexue () and Tiaogan Jiedu Huashi () fomulae, in hepatitis B e antigen (HBeAg)-positive Chinese patients. METHODS: A total of 605 HBeAg-positive Chinese CHB patients were screened and 590 eligible participants were randomly assigned to 2 groups in 1:1 ratio including experimental group (EG, received ADV plus CM) and control group (CG, received ADV plus CM-placebo) for 48 weeks. The major study outcomes were the rates of HBeAg and HBV-DNA loss on week 12, 24, 36, 48, respectively. Secondary endpoints including liver functions (enzymes and bilirubin readings) were evaluated every 4 weeks at the beginning of week 24, 36, and 48. Routine blood, urine, and stool analyses in addition to electrocardiogram and abdominal B scan were monitored as safety evaluations. Adverse events (AEs) were documented. RESULTS: The combination therapy demonstrated superior HBeAg loss at 48 weeks, without additional AEs. The full analysis population was 560 and 280 in each group. In the EG, population achieved HBeAg loss on week 12, 24, 36, and 48 were 25 (8.90%), 34 (12.14%), 52 (18.57%), and 83 (29.64%), respectively; the equivalent numbers in the CG were 20 (7.14%), 41 (14.64%), 54 (19.29%), and 50 (17.86%), respectively. There was a statistically significant difference between these group values on week 48 (P<0.01). No additional AEs were found in EG. Subgroup analysis suggested different outcomes among treatment patterns. CONCLUSION: Combination of CM and ADV therapy demonstrated superior HBeAg clearance compared with ADV monotherapy. The finding indicates that this combination therapy may provide an improved therapeutic effect and safety profile (ChiCTR-TRC-11001263).

4.
ACS Appl Mater Interfaces ; 12(3): 4114-4122, 2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-31927903

RESUMO

A controllable electronic manipulation in a frustrated magnetic system such as solution-based two-dimensional (2D) all-inorganic perovskites offers a possible route for their integrations with electronic and magnetic devices for their advanced applications. Here, we perform element-specific investigations of an emergent class of quasi-2D all-inorganic perovskites Cs2CuCl4-xBrx with (0 ≤ x ≤ 4) using a combination of synchrotron-radiation photoelectron techniques. Surface- and element-sensitive X-ray absorption spectroscopy spectra of Cu L2,3 edges indicate strong electronic transition that is largely influenced by their halogen content at room temperature. This implies that site-selective occupation largely dominates the electronic transition across the unoccupied states of these series since chlorine atoms possess a stronger electronegative character than bromine atoms. Moreover, the implication of halogen site is reflected in the valence band of Cl-rich copper perovskite in which the valence band edge is closer to Fermi energy (EF) than that of the Br-rich compound. Furthermore, X-ray magnetic circular dichroism spectra of mixed ratio and Br-rich compounds exhibit antiferromagnetism at room temperature. These site-specific magnetic-spectroscopic results are corroborated by density functional theory calculations. The strong electronic modulation and the local magnetic spectroscopy results in these solution-based and low-temperature-growth materials will pave the way toward energy- and cost-efficient perovskite devices.

5.
ACS Appl Mater Interfaces ; 12(4): 4558-4564, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31960670

RESUMO

Superoxide (O2-) species play a crucial role in determining the charge kinetics for aprotic lithium-oxygen (Li-O2) batteries. However, the growth of O2--rich lithium peroxide (Li2O2) is challenging since O2- is thermodynamically unfavorable and unstable in an O2 atmosphere. Herein, we reported the synthesis of defective Li2O2 with tunable O2- via K+ doping. The K+ dopants can successfully stabilize O2- species and induce the coordination of Li+ with O2-, leading to increased Li vacancies. Compared to the pristine Li2O2, the as-prepared defective Li2O2 can be charged at a lower overpotential in Li-O2 batteries, which is ascribed to further increased Li vacancies contributed by the depotassiation process at the onset of the charge process. Our findings suggest a new strategy to better control O2- species in Li2O2 by K+ dopants and provide insights into the K+ effects on charge mechanism in Li-O2 batteries.

6.
Nano Lett ; 20(2): 1101-1109, 2020 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-31944125

RESUMO

Oxide heterostructures have attracted a lot of interest because of their rich exotic phenomena and potential applications. Recently, a greatly enhanced tunneling electroresistance (TER) of ferroelectric tunnel junctions (FTJs) has been realized in such heterostructures. However, our understanding on the electronic structure of resistance response with polarization reversal and the origin of huge TER is still lacking. Here, we report on electronic structures, particularly at the interface and surface, and the control of the spontaneous polarization of BaTiO3 films by changing the termination of a SrTiO3 substrate. Interestingly, unusual electron and hole midgap states are concurrently formed and accompanied by orbital reconstructions, which determine the ferroelectric polarization orientation in the BaTiO3/SrTiO3. Such unusual midgap states, which yield a strong electronic screening effect, reduce the ferroelectric barrier width and height, and pin the ferroelectric polarization, lead to a dramatic enhancement of the TER effect. The midgap states are also observed in BaTiO3 films on electron-doped Nb/SrTiO3 revealing its universality. Our result provides new insight into the origin of the huge TER effect and opens a new route for designing ferroelectric tunnel junction-based devices with huge TER through interface engineering.

7.
Artigo em Inglês | MEDLINE | ID: mdl-31931575

RESUMO

Stabilized Cu+ species have been widely considered as catalytic active sites in composite copper catalysts for catalytic reactions with industrial importance. However, few examples comprehensively explicated the origin of stabilized Cu+ in a low-cost and widely investigated CuO/TiO2 system. In this study, mass producible CuO/TiO2 catalysts with interface-stabilized Cu+ were prepared, which showed excellent low-temperature CO oxidation activity. A thorough characterization and theoretical calculations proved that the strong charge-transfer effect and Ti-O-Cu hybridization in Ti-doped CuO(111) at the CuO/TiO2 interface contributed to the formation and stabilization of Cu+ species. The CO molecule adsorbed on Cu+ and reacted directly with Ti doping-promoted active lattice oxygen via a Mars-van Krevelen mechanism, leading to the enhanced low-temperature activity.

8.
HLA ; 95(2): 133-134, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31628781

RESUMO

The novel allele HLA-A*33:131 was identified in a Chinese individual using the sequencing-based typing method.

9.
J Anim Physiol Anim Nutr (Berl) ; 104(1): 371-378, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31724249

RESUMO

In order to investigate the mechanism of genistein (Gen) in the treatment of climacteric syndrome, an in vivo study was performed to investigate the beneficial effects of genistein on the expression of P450 aromatase (P450 arom) and follicle-stimulating hormone receptor (FSHR) in the mouse ovary and uterus. Fifty female ICR mice (45 ± 5g, n = 50), aged 12 months, were divided into the following five groups with 10 animals in each: blank control group (CG), low-dose genistein group (L-Gen), middle-dose genistein group (M-Gen) and high-dose genistein group (H-Gen) (received 15, 30 and 60 mg/kg of genistein, respectively), and oestrogen group (EG; received 0.5 mg/kg diethylstilbestrol). The expression levels of the FSHR protein were determined by an immunohistochemical staining method. The expression of P450 arom, Cytochrome P450 19 (CYP19) and FSHR was quantified by real-time PCR. Immunohistochemical results showed that the expression levels of the FSHR protein in the M-Gen (average stained area: 20.79) and the H-Gen (average stained area: 21.21) groups were significantly stronger than in the CG (average area was 17.24) group (p < .05). The expression levels of CYP19 mRNA and P450 arom were positively correlated with the dose of genistein. Specifically, the relative expression levels in the H-Gen and EG groups were more than 1.5 times higher than in the CG group (p < .05). Genistein played a significant role in regulating aromatase and FSHR gene expression to improve perimenopausal ovarian and uterine function.

10.
Adv Mater ; 32(4): e1906437, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31777990

RESUMO

The identification of chemoselective oxidation process en route to fine chemicals and specialty chemicals is a long-standing pursuit in chemical synthesis. A vertically structured, cobalt single atom-intercalated molybdenum disulfide catalyst (Co1 -in-MoS2 ) is developed for the chemoselective transformation of sulfides to sulfone derivatives. The single-atom encapsulation alters the electron structure of catalyst owing to confinement effect and strong metal-substrate interaction, thus enhancing adsorption of sulfides and chemoselective oxidation at the edge sites of MoS2 to achieve excellent yields of up to 99% for 34 examples. The synthetic scopes can be extended to sulfide-bearing alkenes, alkynes, aldehydes, ketones, boronic esters, and amines derivatives as a toolbox for the synthesis of high-value, multifunctional sulfones and late-stage functionalization of pharmaceuticals, e.g., Tamiflu. The synthetic utility of cobalt single atom-intercalated MoS2 , together with its reusability, scalability, and simplified purification process, renders it promising for industrial productions.

11.
Nano Lett ; 19(11): 8040-8048, 2019 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-31560545

RESUMO

Although Si acts as an electrical semiconductor, it has properties of an optical dielectric. Here, we revisit the behavior of Si as a plasmonic metal. This behavior was previously shown to arise from strong interband transitions that lead to negative permittivity of Si across the ultraviolet spectral range. However, few have studied the plasmonic characteristics of Si, particularly in its nanostructures. In this paper, we report localized plasmon resonances of Si nanostructures and the observation of plasmon hybridization in the UV (∼250 nm wavelength). In addition, simulation results show that Si nanodisk dimers can achieve a local intensity enhancement greater than ∼500-fold in a 1 nm gap. Lastly, we investigate hybrid Si-Al nanostructures to achieve sharp resonances in the UV, due to the coupling between plasmon resonances supported by Si and Al nanostructures. These results will have potential applications in the UV range, such as nanostructured devices for spectral filtering, plasmon-enhanced Si photodetectors, interrogation of molecular chirality, and catalysis. It could have significant impact on UV photolithography on patterned Si structures.

12.
Ying Yong Sheng Tai Xue Bao ; 30(7): 2338-2344, 2019 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-31418237

RESUMO

To obtain salt-alkali tolerant strains which could be potenially used to improve the quality of saline-alkali soil, soil samples collected from Dongying, Shandong Province were diluted and spread to modified Gibbson medium with pH 9 and salt concentration of 100 g·L-1. A total of 18 bacteria strains were obtained. By increasing salt concentration and pH, an extremely salt-alkali tole-rant strain N14 was screened which could grow at pH 12 and salt concentration of 20%. We analyzed the morphological, physiological and biochemical characters and 16S rDNA sequence of N14. The strain N14 was identified as Bacillus marmarensis. N14 bacterial fertilizer significantly increased the biomass of wheat, improved shoot height, fresh weight and dry weight by 21.8%, 57.9% and 41.7%, respectively. The addition of N14 bacterial fertilizer significantly increased the chlorophyll a, chlorophyll b and total chlorophyll in wheat by 36.4%, 20.0% and 31.7%, respectively. It significantly increased the activities of invertase, urease and alkaline phosphatase in saline-alkali soil by 23.2%, 68.8% and 106.5%, respectively. It also significantly increased the activities of superoxide dismutase, peroxidase and catalase in roots by 109.6%, 17.8% and 50%, respectively. The concentration of malondialdehyde in wheat roots was significantly reduced by 39.8%. This study provided an idea for the application of extreme salt-alkali tolerant bacteria and a way for improvement of saline-alkali soil.


Assuntos
Fertilizantes , Plantas Tolerantes a Sal/fisiologia , Triticum/fisiologia , Agricultura , Álcalis , Clorofila A , Solo , Microbiologia do Solo
13.
Biosci Rep ; 39(9)2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31439759

RESUMO

The aim of the present study is to investigate the role of RNA interference in the inhibition of MUC1 gene expression in occurrence and metastasis of oral squamous cell carcinoma (OSCC) and its in-depth mechanisms. The OSCC and normal oral mucosa tissues, as well as normal oral epithelial cell line HOK and OSCC cell line SCC-4, Cal-27, TSCCA, Tca8113 were obtained to detect the expression of MUC1. Slug expression in OSCC and normal oral mucosa tissues was also determined. The OSCC cells were grouped to investigate the role of MUC1 gene silencing on proliferation, DNA replication, cell cycle distribution, apoptosis, colony formation ability, epithelial-mesenchymal transition (EMT), invasion, and migration of OSCC cells. We first found higher positive rate of MUC1 and Slug expression in OSCC tissues. Next, it was determined that higher expression of MUC1 was found in OSCC tissues and cells. Furthermore, silencing of MUC1 declined Slug expression, inhibited the proliferation, DNA replication, cell cycle progression, and EMT while inducing apoptosis of OSCC cells. Our study suggests that overexpression of MUC1 is found in OSCC, and MUC1 gene silencing could inhibit the proliferation, invasion, and migration while inducing apoptosis of OSCC cells.

14.
Adv Mater ; 31(40): e1903779, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31423650

RESUMO

Among van der Waals layered ferromagnets, monolayer vanadium diselenide (VSe2 ) stands out due to its robust ferromagnetism. However, the exfoliation of monolayer VSe2 is challenging, not least because the monolayer flake is extremely unstable in air. Using an electrochemical exfoliation approach with organic cations as the intercalants, monolayer 1T-VSe2 flakes are successfully obtained from the bulk crystal at high yield. Thiol molecules are further introduced onto the VSe2 surface to passivate the exfoliated flakes, which improves the air stability of the flakes for subsequent characterizations. Room-temperature ferromagnetism is confirmed on the exfoliated 2D VSe2 flakes using a superconducting quantum interference device (SQUID), X-ray magnetic circular dichroism (XMCD), and magnetic force microscopy (MFM), where the monolayer flake displays the strongest ferromagnetic properties. Se vacancies, which can be ubiquitous in such materials, also contribute to the ferromagnetism of VSe2 , although density functional theory (DFT) calculations show that such effect can be minimized by physisorbed oxygen molecules or covalently bound thiol molecules.

15.
J Phys Chem Lett ; 10(14): 4142-4147, 2019 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-31260324

RESUMO

Predictions about the electrical conductance across molecular junctions based on self-assembled monolayers (SAMs) are often made from the SAM precursor properties. Collective electrostatic effects, however, in a densely packed SAM can override these predictions. We studied, experimentally and theoretically, molecular tunneling junctions based on thiolate SAMs with an aromatic biphenyl backbone and variable, highly polarizable halogen termini X (S-(C6H5)2X; X = H, F, Cl, Br, or I). We found that the halogen-terminated systems show tunneling rates and dielectric behavior that are independent of X despite the large change in the electronegativity of the terminal atom. Using density functional theory, we show that collective electrostatic effects result in modulations of the electrostatic potential that are strongly confined spatially along the direction of charge transport, thereby rendering the role of the halogen atoms insignificant for SAMs with conjugated backbones.

16.
Adv Mater ; 31(29): e1902685, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31157473

RESUMO

Materials with large optical nonlinearity, especially in the visible spectral region, are in great demand for applications in all-optical information processing and quantum optics. 2D hybrid Ruddlesden-Popper-type halide perovskites (RPPs) with tunable ultraviolet-to-visible direct bandgaps exhibit large nonlinear optical responses due to the strong excitonic effects present in their multiple quantum wells. Using a microscopic Z-scan setup with femtosecond laser pulses tunable across the visible spectrum, it is demonstrated that single-crystalline lead halide RPP nanosheets possess unprecedentedly large nonlinear refraction and absorption coefficients near excitonic resonances. A room-temperature insulator (exciton)-metal (plasma) Mott transition is found to occur near the exciton resonance of the thinnest qunatum-well RPPs, boosting the nonlinear response. Owing to the rapidly changing refractive index near resonance, a single RPP crystal can exhibit different nonlinear functionalities across the excitation spectrum. The results suggest that RPPs are efficient nonlinear materials in the visible waveband, indicating their potential use in integrated nonlinear photonic applications such as optical modulation and switching.

17.
Nano Lett ; 19(8): 5109-5117, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31248259

RESUMO

Ultrathin ferroelectrics hold great promise for modern miniaturized sensors, memories, and optoelectronic devices. However, in most ferroelectric materials, polarization is destabilized in ultrathin films by the intrinsic depolarization field. Here we report robust in-plane ferroelectricity in few-layer tin sulfide (SnS) 2D crystals that is coupled anisotropically to lattice strain. Specifically, the intrinsic polarization of SnS manifests as nanoripples along the armchair direction due to a converse piezoelectric effect. Most interestingly, such nanoripples show an odd-and-even effect in terms of its layer dependence, indicating that it is highly sensitive to changes in inversion symmetry. Ferroelectric switching is demonstrated in field-effect transistor devices fabricated on ultrathin SnS films, in which a stronger ferroelectric response is achieved at negative gate voltages. Our work shows the promise of 2D SnS in ultrathin ferroelectric field-effect transistors as well as nanoscale electromechanical systems.

18.
ACS Appl Mater Interfaces ; 11(28): 25147-25154, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31199107

RESUMO

Lithium-sulfur (Li-S) batteries are strong contenders among lithium batteries due to superior capacity and energy density, but the polysulfide shuttling effect limits the cycle life and reduces energy efficiency due to a voltage gap between charge and discharge. Here, we demonstrate that graphene foam impregnated with single-atom catalysts (SACs) can be coated on a commercial polypropylene separator to catalyze polysulfide conversion, leading to a reduced voltage gap and a much improved cycle life. Also, among Fe/Co/Ni SACs, Fe SACs may be a better option to be used in Li-S systems. By deploying SACs in the battery separator, cycling stability improves hugely, especially considering relatively high sulfur loading and ultralow SAC contents. Even at a metal loading of ∼2 µg in the whole cell, an Fe SAC-modified separator delivers superior Li-S battery performance even at high sulfur loading (891.6 mAh g-1, 83.7% retention after 750 cycles at 0.5C). Our work further enriches and expands the application of SACs catalyzing polysulfide blocking and conversion and improving round trip efficiencies in batteries, without side effects such as electrolyte and electrode decomposition.

19.
J Anim Physiol Anim Nutr (Berl) ; 103(5): 1594-1601, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31144391

RESUMO

The objective of this study was to assess the effects of genistein (GEN) on expression of insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 1 (IGFBP-1) in young and aged rat ovary. Forty young female Sprague Dawley (SD) rats (200 ± 20 g) and forty aged female SD rats (490 ± 20 g) were selected and according to weight, they were divided into the following five groups with eight animals in each: negative control group (NC), low-dose group (L), middle-dose group (M), high-dose group (H) and positive control group (PC). GEN group received GEN of 15, 30, 60 mg/kg respectively. It lasted 30 days. Concentrations of serum hormones, IGF-1 and IGFBP-1 were determined by enzyme-linked immunosorbent assay (ELISA). Gene and protein expressions of IGF-1 and IGFBP-1 were determined by real-time PCR and Western blot respectively. Compared with NC, GEN significantly increased oestradiol-17ß(E2 ) level in aged rat, reduced luteinizing hormone (LH) level in young and aged rat. Serum levels of IGFBP-1 in young rats were significantly higher in GEN groups (p < 0.05). mRNA and protein expression levels of IGF-1 and IGFBP-1 were positively correlated with GEN dose. GEN could significantly reduce the ratio of IGF-1/IGFBP-1 of aged rats. Multivariate Cox regression analysis result showed IGF-1 and IGFBP-1 levels significantly correlated with GEN dose. We speculate that there is an association between the addition of GEN and expression of IGF-1 and IGFBP-1, and the relationship between them is different in young and aged rat.

20.
Nano Lett ; 19(5): 3057-3065, 2019 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-30964306

RESUMO

Complex oxide thin-film heterostructures often exhibit magnetic properties different from those known for bulk constituents. This is due to the altered local structural and electronic environment at the interfaces, which affects the exchange coupling and magnetic ordering. The emergent magnetism at oxide interfaces can be controlled by ferroelectric polarization and has a strong effect on spin-dependent transport properties of oxide heterostructures, including magnetic and ferroelectric tunnel junctions. Here, using prototype La2/3Sr1/3MnO3/BaTiO3 heterostructures, we demonstrate that ferroelectric polarization of BaTiO3 controls the orbital hybridization and magnetism at heterointerfaces. We observe changes in the enhanced orbital occupancy and significant charge redistribution across the heterointerfaces, affecting the spin and orbital magnetic moments of the interfacial Mn and Ti atoms. Importantly, we find that the exchange coupling between Mn and Ti atoms across the interface is tuned by ferroelectric polarization from ferromagnetic to antiferromagnetic. Our findings provide a viable route to electrically control complex magnetic configurations at artificial multiferroic interfaces, taking a step toward low-power spintronics.

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