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1.
Artigo em Inglês | MEDLINE | ID: mdl-32178876

RESUMO

C6-ceramide is an exogenous short-chain ceramide which can induce apoptosis of multiple cancer cells. Salivary adenoid cystic carcinoma (SACC) is a common salivary gland cancer, which possesses of high rate of local recurrence and distant metastasis. The mechanism of ceramide-induced SACC-83 and SACC-LM cell apoptosis has not been revealed. In our study, gene expression microarray was used to discover that the unfolded protein response (UPR) pathway, especially PRKR-like endoplasmic reticulum kinase (PERK) pathway, was the major activated pathway after treatment of c6-ceramide. D1ER, an endoplasmic-reticulum-targeted Ca2+ indicator, was used to measure Ca2+ release from endoplasmic reticulum (ER) dynamically. We found that inositol 1,4,5-trisphosphate receptor 3 (IP3R3) was activated, leading to Ca2+ release from ER, soon after c6-ceramide treatment. IP3R3 silencing could block UPR, although it could not prevent SACC-83 and SACC-LM cells from apoptosis. Moreover, we found that C/EBP-homologous protein could upregulate in a UPR-independent way. Mitochondria outer membrane permeabilization might play an important role in inducing SACC cell apoptosis.

2.
BMJ Open ; 10(3): e033731, 2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32139486

RESUMO

INTRODUCTION: Insomnia with short sleep duration has a more serious negative impact on patient health. The existing literature suggests that medication therapy is more effective for this phenotype of insomnia compared with cognitive-behavioural therapy. However, the potential side effects of hypnotic medications hinder their clinical application. Acupuncture has been widely used in the treatment of insomnia, but it remains unclear whether it has therapeutic efficacy for insomnia with short sleep duration. The purpose of this trial is to evaluate the efficacy and safety of acupuncture for insomnia with short sleep duration. METHODS AND ANALYSIS: This study is designed as a randomised, single-centre, single-blinded, placebo acupuncture controlled trial involving 152 participants. Eligible patients will be divided into two groups according to the objective total sleep time: insomnia with normal sleep duration group and insomnia with short sleep duration group. Then, patients in each group will be randomly assigned to two subgroups, the treatment group (acupuncture) and the control group (placebo acupuncture), in a 1:1 ratio with 38 subjects in each subgroup. The primary outcome is the Pittsburgh Sleep Quality Index and the Insomnia Severity Index. Secondary outcomes are actigraphy, the Beck Anxiety Inventory, the Beck Depression Inventory and the Fatigue Severity Scale. All adverse effects will be assessed by the Treatment Emergent Symptom Scale. Outcomes will be evaluated at baseline, post treatment, as well as at 1-week and 1-month follow-up. ETHICS AND DISSEMINATION: This protocol has been approved by the ethics committee of Yueyang Hospital of Integrated Traditional Chinese and Western Medicine (no. 2019-17). Written informed consent will be obtained from all participants. The results will be disseminated through peer-reviewed journals for publications. TRIAL REGISTRATION NUMBER: ChiCTR1900023473; Pre-results.

3.
IEEE Trans Cybern ; 2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-32142467

RESUMO

A granular structure of intuitionistic fuzzy (IF) information presents simultaneously the similarity and diversity of samples. However, this structural representation has rarely displayed its technical capability in data mining and information processing due to the lack of suitable constructive methods and semantic interpretation for IF information with regard to real data. To pursue better performance of the IF-based technique in real-world data mining, in this article, we examine information granularity, information entropy of IF granular structures, and their applications to data reduction of IF information systems. First, several types of partial-order relations at different hierarchical levels are defined to reveal the granularity of IF granular structures. Second, the granularity invariance between different IF granular structures is characterized by using relational mappings. Third, Shannon's entropies are generalized to IF entropies and their relationships with the partial-order relations are addressed. Based on the theoretical analysis above, the significance of intuitionistic attributes using the information measures is then introduced and the information-preserving algorithm for data reduction of IF information systems is constructed. Finally, by inducing substantial IF relations from public datasets that take both the similarity/diversity between the samples from the same/different classes into account, a collection of numerical experiments is conducted to confirm the performance of the proposed technique.

4.
Chem Rev ; 120(5): 2950-3048, 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32083844

RESUMO

The past decades have witnessed an increasing interest in developing advanced polymerization techniques subjected to external fields. Various physical modulations, such as temperature, light, electricity, magnetic field, ultrasound, and microwave irradiation, are noninvasive means, having superb but distinct abilities to regulate polymerizations in terms of process intensification and spatial and temporal controls. Gas as an emerging regulator plays a distinctive role in controlling polymerization and resembles a physical regulator in some cases. This review provides a systematic overview of seven types of external-field-regulated polymerizations, ranging from chain-growth to step-growth polymerization. A detailed account of the relevant mechanism and kinetics is provided to better understand the role of each external field in polymerization. In addition, given the crucial role of modeling and simulation in mechanisms and kinetics investigation, an overview of model construction and typical numerical methods used in this field as well as highlights of the interaction between experiment and simulation toward kinetics in the existing systems are given. At the end, limitations and future perspectives for this field are critically discussed. This state-of-the-art research progress not only provides the fundamental principles underlying external-field-regulated polymerizations but also stimulates new development of advanced polymerization methods.

5.
Dermatol Ther ; : e13265, 2020 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-32052534

RESUMO

Lichen aureus is a particularly rare subtype of pigmented purpuric dermatosis and is characterized by the sudden appearance of golden or rust-colored macules or needle-tip-sized flat papules (concentrated in one region to form lichenoid papules) on the lower limbs. These skin lesions are usually confined to an isolated, unilateral distribution, and linear segmental distribution is rare. In this report, we have documented one such case, where the lesions on the limb were arranged in strips (segmental distribution) that roughly followed the direction of the venous drainage. And the first attack and subsequent aggravation were both associated with the onset of allergic rhinitis, a Type I hypersensitivity.

6.
Nanoscale ; 2020 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-32080698

RESUMO

Layered heterojunctions have been widely used as two-dimensional (2D) semiconductors with unique electronic and optical properties recently. However, the force interactions in layered heterojunctions have been seldom studied. In this study, we propose a simple method to fabricate a graphene layer probe (GLP) to measure the force interactions in layered heterojunctions by atomic force microscope (AFM). The graphene layer probe was formed by attaching a multilayer graphene nanoflake onto a silica microsphere that had been glued to the AFM cantilever under an optical microscope. The frictional, normal, and adhesive forces between the graphene layer probe and four different 2D layered materials (HOPG, h-BN, MoS2, and WS2) were measured. Superlubricity was achieved at these layered heterojunctions with friction coefficients varying from 0.0005 (GLP/HOPG) to 0.003 (GLP/WS2). The variations of friction, adhesion, and van der Waals (vdW) interaction were consistent with the variations of the interlayer shear stress, the surface energy of the composed 2D layered materials, and the Hamaker constant of the heterojunctions, respectively. The good agreement between the measurements and theories confirms that this method is reliable for the fabrication of graphene or other 2D layered material probes and can be widely used for layered heterojunction measurements.

7.
ACS Appl Mater Interfaces ; 12(3): 4031-4040, 2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-31889443

RESUMO

Robust superlubricity of 2D materials could be obtained by transferring graphene on the tip surface for the formation of interlayer friction of heterojunction, owing to the availability of stable interfacial incommensurate contact. Nevertheless, the material transfer mechanisms assisting superlubricity via atomic force microscopy (AFM) probe are still hardly comprehended. In this work, we reported a superlow friction coefficient (0.003) of the WS2/graphene heterojunction governed by graphene flake-transferred AFM tips and achieved a superlubricity state of velocity independence. Both low adhesion of the heterojunction and excellent wear-resistance for tip were also observed, which were attributed to the extremely low interface interaction during the incommensurate contact. The in-depth investigation on the frictional contact zones of probes was performed through high-resolution transmission electron microscopy. The observations emphasize the prevailing mechanisms of tribo-induced interfacial material transfer when AFM probes scan on the surface of 2D materials. The evolution of the superlubricity state principally depends on the establishment of interfacial nanostructures in the self-adaptive running-in period, by different contact mechanics and tribo-reconstructing pathways. These results stimulate a technical route to develop superlubricious tribopairs of 2D materials and guide a promising perspective in the engineering system.

8.
Molecules ; 25(3)2020 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-31979295

RESUMO

The behavior of ice under extreme conditions undergoes the change of intermolecular binding patterns and leads to the structural phase transitions, which are needed for modeling the convection and internal structure of the giant planets and moons of the solar system as well as H2O-rich exoplanets. Such extreme conditions limit the structural explorations in laboratory but open a door for the theoretical study. The ice phases IX and XIII are located in the high pressure and low temperature region of the phase diagram. However, to the best of our knowledge, the phase transition boundary between these two phases is still not clear. In this work, based on the second-order Møller-Plesset perturbation (MP2) theory, we theoretically investigate the ice phases IX and XIII and predict their structures, vibrational spectra and Gibbs free energies at various extreme conditions, and for the first time confirm that the phase transition from ice IX to XIII can occur around 0.30 GPa and 154 K. The proposed work, taking into account the many-body electrostatic effect and the dispersion interactions from the first principles, opens up the possibility of completing the ice phase diagram and provides an efficient method to explore new phases of molecular crystals.

9.
Nanoscale ; 2020 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-31974535

RESUMO

Metallic germanium (Ge) as the anode can deliver a high specific capacity and high rate capability in lithium ion batteries. However, the large volume expansion largely restrains its further application. Herein, we constructed a three-dimensional sea urchin structure consisting of double layered Ge/TiO2 nanotubes as the spines via a ZnO template-removing method, which displays a capacity as high as 1060 mA h g-1 over 130 cycles. The robust, hollow oxide backbone serves as a strong support to accommodate the morphological change of Ge while the enhanced electron-transfer kinetics is attributed to the Ge content and the intimate contact between Ge and TiO2 during charging/discharging, which were confirmed using in situ transmission electronic microscopy observations and first-principles simulations. In addition, a high capacity retention of batteries using this hybrid composite as the anode was also achieved at low temperature.

10.
J Phys Chem Lett ; 11(1): 184-190, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31826621

RESUMO

Strong hydration repulsion exists between two negatively charged surfaces in the alkali metal salt solutions, together with the fluid response to the shear of hydration layers, leading to superlubricity. However, whether the multivalent ions can obtain superlubricity has not been revealed yet. Here, we evaluate the lubrication and adsorption properties of multivalent ions at different concentrations between Si3N4 and sapphire surfaces. The divalent and trivalent ions exhibit extremely low friction coefficients of 0.005-0.006 and 0.002-0.004, respectively, under contact pressures above 0.25 GPa, and three trivalent ions can achieve superlubricity at quite low sliding speeds (3.1 mm/s), which is a significant breakthrough for superlubricity under boundary lubrication. Moreover, compared with monovalent ions, divalent ions can reduce surface potential and lower surface charge density even further, and trivalent ions can neutralize the negatively charged ceramic surfaces and even lead to charge inversion due to excess adsorption of the cations, which ensures strong adsorption of hydrated multivalent ions on friction surfaces.

12.
ACS Appl Mater Interfaces ; 11(43): 40470-40480, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31577116

RESUMO

Graphene-related materials are promising solid lubricants owing to their easy shear between lattice layers. However, the coefficient of friction (COF) of graphene is not sufficiently low at the macroscale, and the lubrication performance is largely restricted by the external environment. In this study, we fabricated a fluorinated graphene (FG) coating on a stainless-steel substrate by a simple electrophoretic deposition in ethanol. The FG coating exhibited an excellent lubrication performance, which reduced the COF by 54.0 and 66.2% compared to those of pristine graphene and graphene oxide coatings, respectively. The lubrication enhancement of FG coating is attributed to its extremely low surface energy and interlaminar shear strength. The formation of ionic metal-fluorine chemical bonds provided a robust solid tribofilm and transfer layer on the friction pairs, which further increased the lubrication performance of the FG coating. The limited influence of the humidity on the lubrication performance of the FG coating is attributed to the hydrophobicity of the FG nanoflakes, which could prevent the influence of water molecules on the sliding interface. The excellent lubrication performance and better environmental adaptability of the FG make it a promising solid lubricant for mechanical engineering applications.

13.
Langmuir ; 35(36): 11784-11790, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31432683

RESUMO

In this study, ultralow friction coefficient (COF, µ < 0.01) was obtained through polyalkylene glycol (PAG) aqueous solutions with different molecular weights (MWs) ranging from 270 to 3930 g·mol-1 under ambient conditions. With the increase in the MWs of PAG molecules, the threshold concentration to obtain this type of superlubric behavior gradually changed from 90 to 60 wt %. This phenomenon was closely related to the interaction between PAG chains and water molecules and the state of chemical binding. In the superlubricity system, superior load-bearing capacity was achieved at optimal threshold concentrations of all PAG aqueous solutions wherein multilayered adsorption layers that consisted of fully hydrated PAG molecules were formed on the sliding solid surfaces. With respect to the concentration below the threshold value, the existence of a shearing layer was indicated to play a significant role. Thus, the synergetic effect of sufficient adsorption of molecules and the unique shear rheology of the PAG aqueous solution were essential to achieve superlubricity.

14.
Langmuir ; 35(34): 11108-11113, 2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31364855

RESUMO

It is easy to achieve extremely low friction of graphene or graphite in dry conditions via the formation of an incommensurate interface but is difficult to achieve with water lubrication. Herein, we propose a new strategy to achieve extremely low friction on a graphitic surface in water by self-assembling cationic surfactant micelles in the contact zone. When uniform surfactant micelles are formed on silica and freshly cleaved graphene layers via self-assembly under low contact pressure, the friction coefficient between them can reduce to 0.0004. When the self-assembled micelles are ruptured in the contact zone by high pressure, the friction coefficient between them would increase to 0.005 (still in the superlubricity regime). The mechanism of the different friction behaviors was studied at the nanoscale, which was attributed to the formation of different shear planes that shifts from the interface of the micelle/micelle to surfactant molecules/graphene layers after micellar rupture. The results provide direct evidence that the cationic surfactant micelles can efficiently lubricate graphitic surface regardless of micellar rupture.

15.
Langmuir ; 35(35): 11452-11462, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31404491

RESUMO

Graphene oxide (GO) has been evaluated as a multifunctional cross-linker or reinforcement agent in composite hydrogels. In this study, a nanocomposite hydrogel consisting of GO nanosheets and zwitterionic poly(sulfobetaine methacrylate) (PSBMA) was synthesized in an aqueous system via chemical and physical cross-linking effects. GO nanosheets were well dispersed in the hydrogels and effectively cross-linked into the sulfobetaine methacrylate (SBMA) polymer chains through the electrostatic interactions. The PSBMA hydrogel exhibited a significant enhancement in the compressive stress (close to a 5-fold increase) and a remarkable reduction in the coefficient of friction (COF) (corresponding to a decline of 52-76%) after the embedding of GO nanosheets. These improvements indicate the existence of synergetic interaction and good compatibility between GO nanosheets and the PSBMA hydrogel matrix, which results in an intertwined network structure with higher load-bearing capacity and better lubrication properties. This study provides potential in the development of new graphene-polymer composites, which is beneficial for cartilage replacement with high mechanical properties and excellent lubrication characteristics.

16.
ACS Appl Mater Interfaces ; 11(28): 25535-25546, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31264826

RESUMO

Onion-like carbon (OLC), spherical nanoparticles consisting of carbon shells, is capable of providing exceptional lubrication effects. Nevertheless, the underlying mechanism, especially the tribo-induced evolution of interfacial nanostructures and their correlation with the friction states, is not clear. In this work, OLC films with a thickness of ∼1 µm were synthesized by electrophoretic deposition on the mirror-polished stainless steel. The lubricity was evaluated by tailoring the sliding aspects including applied normal load, contact time, and counterface materials. It is found that the friction reduction level is highly dependent on the material transfer and transformation of the OLC surface and the physicochemical nature of the as-formed tribolayer in the contact areas. The subsurface of the OLC film always undergoes a deep amorphization transformation upon sliding. It is interesting to note that the tribolayer formed on the bare steel ball is mainly composed of highly ordered graphene-like nanoflakes derived from the sliding-induced degradation of OLC nanospheres. In comparison, the nanospherical carbon structure can be retained in the topmost subsurface of the tribolayer formed on the ceramic Si3N4 ball. Such a nanosphere-/amorphization-coupled interface is capable of providing a robust lubrication state under high contact stresses. The findings identify a new lubrication mechanism for the spherical carbon nanostructure, rendering them effective solid lubricants.

17.
New Phytol ; 223(3): 1607-1620, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31087371

RESUMO

(E)-ß-Farnesene (EßF) is the predominant constituent of the alarm pheromone of most aphid pest species. Moreover, natural enemies of aphids use EßF to locate their aphid prey. Some plant species emit EßF, potentially as a defense against aphids, but field demonstrations are lacking. Here, we present field and laboratory studies of flower defense showing that ladybird beetles are predominantly attracted to young stage-2 pyrethrum flowers that emitted the highest and purest levels of EßF. By contrast, aphids were repelled by EßF emitted by S2 pyrethrum flowers. Although peach aphids can adapt to pyrethrum plants in the laboratory, aphids were not recorded in the field. Pyrethrum's (E)-ß-farnesene synthase (EbFS) gene is strongly expressed in inner cortex tissue surrounding the vascular system of the aphid-preferred flower receptacle and peduncle, leading to elongated cells filled with EßF. Aphids that probe these tissues during settlement encounter and ingest plant EßF, as evidenced by the release in honeydew. These EßF concentrations in honeydew induce aphid alarm responses, suggesting an extra layer of this defense. Collectively, our data elucidate a defensive mimicry in pyrethrum flowers: the developmentally regulated and tissue-specific EßF accumulation and emission both prevents attack by aphids and recruits aphid predators as bodyguards.

18.
ACS Appl Mater Interfaces ; 11(22): 20249-20256, 2019 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-31083968

RESUMO

It was previously proved that the existence of a large amount of hydrogen ions in water-based lubricants can easily lead to a superlubric state; however, it was also shown that these hydrogen ions could cause severe corrosion. As part of a large family of attractive clays, layered double hydroxides (LDHs) possess excellent tribological properties in water-based lubrication systems. In the present work, two different kinds of LDHs are dispersed in polyalkylene glycol (PAG) aqueous solutions, in two distinct forms: ultrathin nanosheets (ULDH-NS) of ca. 60 nm wide and ca. 1 nm thick (single or double layer) and nanoparticles (LDH-NP) of ca. 19.73 nm wide and ca. 8.68 nm thick. We find that the addition of ULDH-NS greatly shortens (as much as 85%) the running-in period prior to reaching the superlubricity regime and increases the ultimate load-bearing capacity by about four times. As compared to the fluid film thickness of the lubricating PAG solution, their ultrathin longitudinal dimension will not impair or influence the fluid film coverage in the contact zone. The analysis of sliding solid surfaces and the atomic force microscope microscale friction test demonstrate that the adsorption of ULDH-NS enables the sliding solid surfaces to be polished and protected because of their relatively weak interlayer interaction and increased adhesion effect. Owing to their superior tribological properties as lubricant additives, ultrathin LDH nanosheets hold great potential for enabling liquid superlubricity in industrial applications in the future.

19.
J Phys Chem Lett ; 10(11): 2978-2984, 2019 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-31094522

RESUMO

Graphene is efficient to provide ultralow friction after the formation of an incommensurate interface but is limited to dry contact conditions and specific lattice structures. In this Letter, a new strategy is proposed to achieve the superlubricity of graphene through the creation of a sliding interface between graphene and a highly hydrophobic surface of self-assembled fluoroalkyl monolayers (SAFMs) in water. A superlow friction coefficient of µ = 0.0003 was obtained, demonstrating the extremely low shear stress between graphene and hydrophobic SAFMs in water. Molecular dynamics (MD) simulation shows that a nanometer-thick water layer is intercalated between graphene and hydrophobic SAFMs, and the weak interactions between water molecules and graphene provide a small energy barrier for water molecules sliding on graphene, which contributes to superlubricity. This finding reveals how to form a superlubricity interface by water intercalation, which has implications for minimizing the friction of layered materials and hydrophobic surfaces in water.

20.
Hepatol Res ; 49(7): 743-757, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30861258

RESUMO

AIM: Glucagon-like peptide-1 receptor agonists (GLP-1Ras) have been reported to prevent non-alcoholic fatty liver disease (NAFLD), but the potential mechanisms are still debated. MicroRNAs (miRNAs) play a prominent role in the field of metabolic disorders, including NAFLD. Our study was designed to further evaluate the effect of GLP-1Ra liraglutide on NAFLD in terms of miRNAs. METHODS: MicroRNA expression was evaluated by clustering analysis of microRNA arrays in high fat diet-fed mice. The luciferase reporter assay was carried out to validate the cross-talk between adipose triglyceride lipase (ATGL) and miR-124a. MicroRNA-124a mimics and inhibitor plasmids were transfected to study the role of miR-124a in palmitate-treated normal human liver cell line (HL-7702). Liraglutide treatment was used to observe the effect of GLP-1Ra on the miR-124a/ATGL pathway. RESULTS: Expression of ATGL decreased and miR-124a expression increased in hepatosteatosis in vivo and in vitro. Mechanistically, miR-124a interacted with the 3'-untranslated region of ATGL mRNA and induced its degradation. MicroRNA-124a overexpression antagonized the effect of liraglutide on NAFLD by inhibiting ATGL expression, whereas miR-124a knockdown led to elevated ATGL and sirtuin 1 (Sirt1) expression, and subsequently decreased lipid accumulation and inflammation in cells. CONCLUSIONS: MicroRNA-124a overexpression contributes to the progression of NAFLD through reduction of ATGL expression, whereas miR-124a knockdown can reverse this trend, suggesting that miR-124a and its downstream target ATGL can be novel therapeutic targets of NAFLD. We reveal a novel mechanism by which liraglutide attenuates NAFLD by the miR-124a/ATGL/Sirt1 pathway.

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