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2.
ACS Chem Biol ; 16(8): 1318-1324, 2021 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-34374518

RESUMO

As enzymes that mediate the attachment of long-chain fatty acids to cysteine residues, ZDHHC proteins have been reported to be promising therapeutic targets for treating cancer and autoimmune diseases. Yet, due to the lack of potent selective inhibitors, scrutiny of the biological functions of ZDHHCs has been limited. The main hindrance for developing ZDHHC inhibitors is the lack of a facile high-throughput assay. Here, we developed a ZDHHC3/7/20 high-throughput assay based on the acylation-coupled lipophilic induction of polarization (Acyl-cLIP) method and screened several potential ZDHHC inhibitors. Furthermore, we demonstrated that in vitro results from the Acyl-cLIP assay are supported by the results from cell-based assays. We envision that this new ZDHHC3/7/20 Acyl-cLIP assay will accelerate the high-throughput screening of large compound libraries for improved ZDHHC inhibitors and provide therapeutic benefits for cancer and autoimmune diseases.

3.
Artigo em Inglês | MEDLINE | ID: mdl-34396781

RESUMO

Architected metallic materials generally suffer from a serious engineering problem of mechanical instability manifested as the emergence of localized deformation bands and collapse of strength. They usually cannot exhibit satisfactory shape recoverability due to the little recoverable strain of metallic constituent material. After yielding, the metallic constituent material usually exhibits a continuous low strain-hardening capacity, giving the local yielded regions of architecture low load resistance and easily developing into excessive deformation bands, accompanied by the collapse of strength. Here, a novel constituent material deformation design strategy has been skillfully proposed, where the low load resistance of yielded regions of the architecture can be effectively compensated by the significant self-strengthening behavior of constituent material, thus avoiding the formation of localized deformation bands and collapse of strength. To substantiate this strategy, shape-memory alloys (SMAs) are considered as suitable constituent materials for possessing both self-strengthening behavior and shape-recovery function. A 3D-printing technique was adopted to prepare various NiTi SMA architected materials with different geometric structures. It is demonstrated that all of these architected metallic materials can be stably and uniformly compressed by up to 80% without the formation of localized bands, collapse of strength, and structural failure, exhibiting ultrahigh damage tolerance. Furthermore, these SMA architected materials can display more than 98% shape recovery even after 80% deformation and excellent cycle stability during 15 cycles. This work exploits the amazing impact of constituent materials on constructing supernormal properties of architected materials and will open new avenues for developing high-performance architected metallic materials.

4.
J Mech Behav Biomed Mater ; 112: 104018, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32818859

RESUMO

Nacre is a natural composite featuring exceptional mechanical properties such as high strength and high toughness. Its unique structure is now universally applied in engineering bioinspired materials. On the other hand, it is still a technical challenge to investigate its interfacial strength and fracture mechanisms at micro or nano-scale. In this work, the interfacial strength and fracture mechanism of the 'brick-mortar' structure in nacre are investigated using micro-sized cantilever beam and bend samples. As compared to previous works, a high aragonite/biopolymer interfacial strength is observed (~298 MPa). The crack propagation path is investigated via experiment and finite element modelling and compared with the fracture mechanics analysis. It is confirmed that crack deflection to the aragonite/biopolymer interface contributes to a high overall toughness. This work provides a better understanding of the toughening mechanism in nacre and other bioinspired composites.


Assuntos
Nácar , Carbonato de Cálcio , Teste de Materiais
5.
Am J Physiol Cell Physiol ; 318(3): C640-C648, 2020 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-31940246

RESUMO

Zinc (Zn) has antioxidant effect in different types of organs and is closely associated with human health. Endometrial receptivity is one of the most important factors in the embryo implantation and development. However, the regulatory mechanism of Zn in endometrium tissue is still unclear. In the study, we found that plasma Zn level is significantly associated with female infertility, which severely affects female reproductive health. Primary endometrial stromal cells were isolated from female endometrium and cultured in the laboratory. Zn chelator TPEN treatment reduced the expression of stem cell markers CD73, CD90, and CD105 and generated reactive oxygen species in endometrial stromal cells. However, pretreatment of Zn (zinc sulfate) is able to prevent TPEN-induced oxidative stress in vitro. By transcriptional profiling and gene ontology analysis, we found that Zn increased the cellular pluripotency signaling and extracellular matrix-receptor interaction, but reduced autophagy, endocytosis, and the nitrogen metabolism pathway. We further discovered the antioxidant function of Zn through the peroxisome proliferator-activated receptor gamma coactivator 1α/nuclear factor erythroid-2-related factor signaling pathway in endometrial stromal cells. Zn supplementation may open up an effective therapeutic approach for patients with oxidative stress-related endometrial diseases.


Assuntos
Endométrio/metabolismo , Fator 2 Relacionado a NF-E2/fisiologia , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/fisiologia , Células Estromais/metabolismo , Transcrição Genética/fisiologia , Zinco/metabolismo , Adulto , Sobrevivência Celular/fisiologia , Células Cultivadas , Endométrio/diagnóstico por imagem , Feminino , Humanos , Transdução de Sinais/fisiologia , Células Estromais/patologia , Adulto Jovem
6.
Adv Mater ; 32(18): e1904387, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31538374

RESUMO

Nanosized materials are known to have the ability to withstand ultralarge elastic strains (4-10%) and to have ultrahigh strengths approaching their theoretical limits. However, it is a long-standing challenge to harnessing their exceptional intrinsic mechanical properties in bulk forms. This is commonly known as "the valley of death" in nanocomposite design. In 2013, a breakthrough was made to overcome this challenge by using a martensitic phase transforming matrix to create a composite in which ultralarge elastic lattice strains up to 6.7% are achieved in Nb nanoribbons embedded in it. This breakthrough was enabled by a novel concept of phase transformation assisted lattice strain matching between the uniform ultralarge elastic strains (4-10%) of nanomaterials and the uniform crystallographic lattice distortion strains (4-10%) of the martensitic phase transformation of the matrix. This novel concept has opened new opportunities for developing materials of exceptional mechanical properties or enhanced functional properties that are not possible before. The work in progress in this research over the past six years is reported.

7.
Data Brief ; 27: 104566, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31799342

RESUMO

This article provides experimental and numerical data for the propagation of stress-induced martensitic transformation within NiTi structures with uniform and nonuniform geometries. This article is related to the research paper entitled "Computational and experimental analyses of martensitic transformation propagation in shape memory alloys" [1]. The heterogeneous transformation evolutions within geometrically graded NiTi structures are presented by thermal images recorded by a high-resolution infrared camera during tensile loading. The modelling of transformation and deformation behaviours of those structures is presented by finite element computational method.

8.
Nat Biomed Eng ; 3(5): 402-413, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31036888

RESUMO

Cells and tissues often display pronounced spatial and dynamical metabolic heterogeneity. Common glucose-imaging techniques report glucose uptake or catabolism activity, yet do not trace the functional utilization of glucose-derived anabolic products. Here we report a microscopy technique for the optical imaging, via the spectral tracing of deuterium (STRIDE), of diverse macromolecules derived from glucose. Based on stimulated Raman-scattering imaging, STRIDE visualizes the metabolic dynamics of newly synthesized macromolecules, such as DNA, protein, lipids and glycogen, via the enrichment and distinct spectra of carbon-deuterium bonds transferred from the deuterated glucose precursor. STRIDE can also use spectral differences derived from different glucose isotopologues to visualize temporally separated glucose populations using a pulse-chase protocol. We also show that STRIDE can be used to image glucose metabolism in many mouse tissues, including tumours, brain, intestine and liver, at a detection limit of 10 mM of carbon-deuterium bonds. STRIDE provides a high-resolution and chemically informative assessment of glucose anabolic utilization.


Assuntos
Deutério/química , Glucose/metabolismo , Imagem Óptica/métodos , Animais , Animais Recém-Nascidos , Linhagem Celular Tumoral , Humanos , Intestinos , Lipídeos/biossíntese , Substâncias Macromoleculares/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Nus , Biossíntese de Proteínas , Análise Espectral Raman
9.
Acta Biomater ; 98: 50-66, 2019 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-30853611

RESUMO

Proper alloying magnesium with element scandium (Sc) could transform its microstructure from α phase with hexagonal closed-packed (hcp) structure into ß phase with body-cubic centered (bcc) structure. In the present work, the Mg-30 wt% Sc alloy with single α phase, dual phases (α + ß) or ß phase microstructure were developed by altering the heat-treatment routines and their suitability for usage within bone was comprehensively investigated. The ß phased Mg-30 wt% Sc alloy showed the best mechanical performance with ultimate compressive strength of 603 ±â€¯39 MPa and compressive strain of 31 ±â€¯3%. In vitro degradation test showed that element scandium could effectively incorporate into the surface corrosion product layer, form a double-layered structure, and further protect the alloy matrix. No cytotoxic effect was observed for both single α phased and ß phased Mg-30 wt% Sc alloys on MC3T3 cell line. Moreover, the ß phased Mg-30 wt%Sc alloy displayed acceptable corrosion resistance in vivo (0.06 mm y-1) and maintained mechanical integrity up to 24 weeks. The degradation process did not significantly influence the hematology indexes of inflammation, hepatic or renal functions. The bone-implant contact ratio of 75 ±â€¯10% after 24 weeks implied satisfactory integration between ß phased Mg-30 wt%Sc alloy and the surrounding bone. These findings indicate a potential usage of the bcc-structured Mg-Sc alloy within bone and might provide a new strategy for future biomedical magnesium alloy design. STATEMENT OF SIGNIFICANCE: Scandium is the only rare earth element that can transform the matrix of magnesium alloy into bcc structure, and Mg-30 wt%Sc alloy had been recently reported to exhibit shape memory effect. The aim of the present work is to study the feasibility of Mg-30 wt%Sc alloy with different constitutional phases (single α phase, single ß phase or dual phases (α + ß)) as biodegradable orthopedic implant by in vitro and in vivo testings. Our findings showed that ß phased Mg-30 wt%Sc alloy which is of bcc structure exhibited improved strength and superior in vivo degradation performance (0.06 mm y-1). No cytotoxicity and systematic toxicity were shown for ß phased Mg-30 wt%Sc alloy on MC3T3 cell model and rat organisms. Moreover, good osseointegration, limited hydrogen gas release and maintained mechanical integrity were observed after 24 weeks' implantation into the rat femur bone.


Assuntos
Ligas/química , Osso e Ossos/fisiologia , Magnésio/química , Escândio/química , Implantes Absorvíveis , Animais , Densidade Óssea , Varredura Diferencial de Calorimetria , Morte Celular , Corrosão , Eletroquímica , Hemólise , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Hidrogênio/análise , Concentração de Íons de Hidrogênio , Magnésio/sangue , Fenômenos Mecânicos , Camundongos , Adesividade Plaquetária , Ratos Sprague-Dawley , Propriedades de Superfície , Termogravimetria , Distribuição Tecidual , Difração de Raios X , Microtomografia por Raio-X
10.
Biomed Mater ; 13(6): 065014, 2018 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-30213920

RESUMO

Alveolar bone loss is a common problem that affects dental implant placement. A barrier between the bone substitute and gingiva that can prevent fibro-tissue ingrowth, bacterial infection and induce bone formation is a key factor in improving the success of alveolar ridge reconstruction. This study aims to develop a bioactive collagen barrier material for guided bone regeneration, that is coupled with anti-bacterial and anti-inflammatory properties. We have evaluated two silver coating methods and found controllable and precise coating achieved by sonication compared with sputtering. The optimized AgNP-coated collagen membrane exhibited excellent anti-bacterial effects against Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) with limited cellular toxicity. It also displayed effective anti-inflammatory effects by reducing the expression and release of inflammatory cytokines including IL-6 and TNF-alpha. Additionally, AgNP-coated collagen membranes were able to induce osteogenic differentiation of mesenchymal stem cells that guide bone regeneration. These findings demonstrate the potential application of AgNP-coated collagen membranes to prevent infection after bone graft introduction in alveolar ridge reconstruction.


Assuntos
Antibacterianos/química , Anti-Inflamatórios/química , Regeneração Óssea , Regeneração Tecidual Guiada Periodontal/métodos , Nanopartículas Metálicas/química , Prata/química , Processo Alveolar/fisiologia , Animais , Substitutos Ósseos , Sobrevivência Celular , Materiais Revestidos Biocompatíveis , Colágeno/química , Implantes Dentários , Gengiva , Regeneração Tecidual Guiada , Interleucina-6/metabolismo , L-Lactato Desidrogenase/metabolismo , Células-Tronco Mesenquimais/metabolismo , Camundongos , Camundongos Endogâmicos C3H , Testes de Sensibilidade Microbiana , Osseointegração , Osteogênese , Pseudomonas aeruginosa/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Propriedades de Superfície , Fator de Necrose Tumoral alfa/metabolismo
11.
Nano Lett ; 18(5): 2976-2983, 2018 05 09.
Artigo em Inglês | MEDLINE | ID: mdl-29714487

RESUMO

Freestanding nanomaterials (such as nanowires, nanoribbons, and nanotubes) are known to exhibit ultralarge elastic strains and ultrahigh strengths. However, harnessing their superior intrinsic mechanical properties in bulk composites has proven to be difficult. A recent breakthrough has overcome this difficulty by using a martensitic phase transforming matrix in which ultralarge elastic strains approaching the theoretical limit is achieved in Nb nanowires embedded in the matrix. This discovery, breaking a long-standing challenge, still limits our ability of harnessing the exceptional properties of nanomaterials and developing ultrahigh strength bulk materials to a narrow selection of phase transforming alloy matrices. In this study, we investigated the possibility to harness the intrinsic mechanical properties of nanoinclusions in conventional dislocation slip matrix based on a principle of synergy between the inclusion and the matrix. The small spacing between the densely populated hard and dislocation-impenetrable nanoinclusions departmentalize the plastic matrix into small domains to effectively impede dislocation motion within the matrix, inducing significant strengthening and large local elastic strains of the matrix, which in turn induced large elastic strains in the nanoinclusions. This dual phase synergy is verified in a Ti3Sn inclusions/B2-NiTi(Fe) plastic matrix model materials system. The maximum elastic strain of Ti3Sn inclusion obtained in the dislocation slip matrix is comparable to that achieved in a phase transforming matrix. This finding opens new opportunities for the development of high-strength nanocomposites.

12.
Sci Rep ; 7(1): 17240, 2017 12 08.
Artigo em Inglês | MEDLINE | ID: mdl-29222467

RESUMO

Using state-of-the-art atomic scale super energy dispersive X-ray spectroscopy and high angle annular dark field imaging this study reveals the elemental partitioning preference between the γ' and γ phases in a Co-Al-W-Ti-Ta superalloy and the site preference of its alloying elements in the ordered L12 γ' phase. A semi-quantitative analysis of atomic column compositions in the ordered L12 γ' structure is provided. Co atoms were found to occupy the {1/2, 1/2, 0} face-center positions whereas Al, W, Ti and Ta atoms prefer to occupy the {0, 0, 0} cube corner positions in the L12 γ phase. These findings agree well with predictions from first principles simulations in the literature.

13.
J Am Chem Soc ; 139(46): 16903-16912, 2017 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-29091409

RESUMO

5-Formylcytosine (5fC) is identified as one of the key players in active DNA demethylation and also as an epigenetic mark in mammals, thus representing a novel attractive target to chemical intervention. The current study represents an attempt to develop a reversible 5fC-targeted intervention tool. A supramolecular aldehyde reactive probe was therefore introduced for selective conversion of the 5fC to 5fC-AD nucleotide. Using various methods, we demonstrate that cucurbit[7]uril (CB7) selectively targets the 5fC-AD nucleotide in DNA, however, the binding of CB7 to 5fC-AD does not affect the hydrogen bonding properties of natural nucleobases in duplex DNA. Importantly, CB7-driven host-guest chemistry has been applied for reversible intervention of a variety of 5fC-targeted biochemical reactions, including restriction endonuclease digestion, DNA polymerase elongation, and polymerase chain reaction. On the basis of the current study, the macrocyclic CB7 creates obstructions that, through steric hindrance, prevent the enzyme from binding to the substrate, whereas the CB7/5fC-AD host-guest interactions can be reversed by treatment with adamantanamine. Moreover, fragment- and site-specific identification of 5fC modification in DNA has been accomplished without sequence restrictions. These findings thus show promising potential of host-guest chemistry for DNA/RNA epigenetics.


Assuntos
Adamantano/metabolismo , Aldeídos/metabolismo , Hidrocarbonetos Aromáticos com Pontes/metabolismo , Citosina/análogos & derivados , Imidazóis/metabolismo , Sondas Moleculares/metabolismo , Nucleosídeos/metabolismo , Adamantano/química , Aldeídos/química , Hidrocarbonetos Aromáticos com Pontes/química , Citosina/química , Citosina/metabolismo , DNA/química , DNA/metabolismo , Imidazóis/química , Sondas Moleculares/química , Estrutura Molecular , Nucleosídeos/química
14.
Sci Rep ; 7(1): 13264, 2017 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-29038576

RESUMO

This paper reports a study of time-resolved deformation process at the atomic scale of a nanocrystalline Pt thin film captured in situ under a transmission electron microscope. The main mechanism of plastic deformation was found to evolve from full dislocation activity-enabled plasticity in large grains (with grain size d > 10 nm), to partial dislocation plasticity in smaller grains (with grain size 10 nm < d < 6 nm), and grain boundary-mediated plasticity in the matrix with grain sizes d < 6 nm. The critical grain size for the transition from full dislocation activity to partial dislocation activity was estimated based on consideration of stacking fault energy. For grain boundary-mediated plasticity, the possible contributions to strain rate of grain creep, grain sliding and grain rotation to plastic deformation were estimated using established models. The contribution of grain creep is found to be negligible, the contribution of grain rotation is effective but limited in magnitude, and grain sliding is suggested to be the dominant deformation mechanism in nanocrystalline Pt thin films. This study provided the direct evidence of these deformation processes at the atomic scale.

15.
Data Brief ; 13: 562-568, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28706965

RESUMO

Functionally graded NiTi structures benefit from the combination of the smart properties of NiTi and those of functionally graded structures. This article provides experimental data for thermomechanical deformation behaviour of microstructurally graded, compositionally graded and geometrically graded NiTi alloy components, related to the research article entitled "Functionally graded shape memory alloys: design, fabrication and experimental evaluation" (Shariat et al., 2017) [1]. Stress-strain variation of microstructurally graded NiTi wires is presented at different heat treatment conditions and testing temperatures. The complex 4-way shape memory behaviour of a compositionally graded NiTi strip during one complete thermal cycle is demonstrated. The effects of geometrical design on pseudoelastic behaviour of geometrically graded NiTi plates over tensile loading cycles are presented on the stress-strain diagrams.

16.
Mol Phylogenet Evol ; 113: 1-8, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28487259

RESUMO

One of the most contentious theories in current ecology is the ecological niche conservatism, which is defined as conservatism among closely related species; however, the ecological niche can also be shifted, as documented in several cases. Genetic drift and ecological divergent selection may cause ecological niche divergence. The current study aims to test whether the ecological niche is conserved or divergent and to determine the main factor that drives ecological niche divergence or conservation. We analyzed the phylogenetic relationship, ecological niche model (ENM) and demographic history of Eared Pheasants in the genus Crossoptilon (Galliformes: Phasianidae) to test niche conservatism with respect to different geographically distributed patterns. The phylogenetic relationship was reconstructed using ∗BEAST with mitochondrial cytochrome b (cyt b) and 44 unlinked autosomal exonic loci, and ENMs were reconstructed in MAXENT using an average of 41 occurrence sites in each species and 22 bioclimatic variables. A background similarity test was used to detect whether the ecological niche is conserved. Demographic history was estimated using the isolation with migration (IM) model. We found that there was asymmetric gene flow between the allopatric sister species Crossoptilon mantchuricum and C. auritum and the parapatric sister species C. harmani and C. crossoptilon. We found that ecological niches were divergent, not conserved, between C. mantchuricum and C. auritum, which began to diverge at approximately 0.3 million years ago. However, the ecological niches were conserved between C. crossoptilon and C. harmani, which gradually diverged approximately half a million years ago. Ecological niches can be either conserved or divergent, and ecological divergent selection for local adaptation is probably an important factor that promotes and maintains niche divergence in the face of gene flow. This study provides a better understanding of the role that divergent selection has in the initial speciation process. The platform combined demographic processes and ecological niches to offer new insights into the mechanism of biogeography patterns.


Assuntos
Ecossistema , Galliformes/fisiologia , Geografia , Animais , Galliformes/genética , Fluxo Gênico , Especiação Genética , Modelos Teóricos , Filogenia , Especificidade da Espécie
17.
Chem Sci ; 8(9): 6380-6388, 2017 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-29308175

RESUMO

Natural nucleic acid bases can form Watson-Crick (WC) or Hoogsteen (HG) base pairs. Importantly, 8-oxo-2'-deoxyguanosine (8-oxo-dG) in DNA or 8-oxo-dG 5'-triphosphate (8-oxo-dGTP) favors a syn conformation because of the steric repulsion between O8 and O4' of the deoxyribose ring. 8-oxo-dGTP can be incorporated into DNA opposite the templating adenine (A) using HG pairing as the dominant mechanism. Both RNA and DNA can be methylated at the N6 position of A to form N6-methyladenine (m6A). It has been found that certain viral infections may trigger an increase in the production of both 8-oxo-dGTP and m6A. The current study aims to systematically explore the effects of m6A methylation on HG base pairs and the consequent nucleotide incorporation. Our thermodynamic melting study shows that the m6A·8-oxo-dG is significantly less stable than the A·8-oxo-dG base pair in the paired region of a DNA duplex. Moreover, we have used pre-steady-state kinetics to examine the incorporation of 8-oxo-dGTP opposite m6A relative to A by a variety of reverse transcriptase (RT) enzymes and DNA polymerase (DNA pol) enzymes such as the human immunodeficiency virus type 1 (HIV-1) RT and human DNA pol ß. The results demonstrate that all of these enzymes incorporate 8-oxo-dGTP less efficiently opposite m6A relative to A. Considering the steric bulk of the purine-purine pair between 8-oxo-dG and A, m6A methylation may affect the HG pairing to a great extent. Hence, it will be unfavorable to incorporate 8-oxo-dGTP into the growing strand opposite m6A. Moreover, the impeded incorporation of 8-oxo-dGTP opposite m6A has been extended to determine m6A at pre-defined positions in human rRNA. Our study may provide new insights into the roles of m6A in reducing the mutagenic potential of cellular 8-oxo-dGTP.

18.
ACS Appl Mater Interfaces ; 8(25): 16310-6, 2016 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-27276656

RESUMO

Inspired by the driving principle of traditional bias-type two-way actuators, we developed a novel two-way actuation nanocomposite wire in which a massive number of Nb nanoribbons with ultralarge elastic strains are loaded inside a shape memory alloy (SMA) matrix to form a continuous array of nanobias actuation pairs for two-way actuation. The composite exhibits a two-way actuation strain of 3.2% during a thermal cycle and an actuation stress of 934 MPa upon heating, which is about twice as high as that (∼500 MPa) found in reported two-way SMAs. Upon cooling, the composite shows an actuation stress of 134 MPa and a mechanical work output of 1.08 × 10(6) J/m(3), which are about three and five times higher than those of reported two-way SMAs, respectively. It was revealed that the massive number of Nb nanoribbons in the compressive state provides the high actuation stress and high work output upon cooling, and the SMA matrix with high yield strength offers the high actuation stress upon heating. Compared to traditional bias-type two-way actuators, the two-way actuation composite with a small volume and simple construct works well with the miniaturization and simplification of actuators.

19.
ACS Appl Mater Interfaces ; 8(5): 2917-22, 2016 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-26745016

RESUMO

Individual metallic nanowires can sustain ultralarge elastic strains of 4-7%. However, achieving and retaining elastic strains of such magnitude in kilogram-scale nanowires are challenging. Here, we find that under active load, ∼ 5.6% elastic strain can be achieved in Nb nanowires embedded in a metallic matrix deforming by detwinning. Moreover, large tensile (2.8%) and compressive (-2.4%) elastic strains can be retained in kilogram-scale Nb nanowires when the external load was fully removed, and adjustable in magnitude by processing control. It is then demonstrated that the retained tensile elastic strains of Nb nanowires can increase their superconducting transition temperature and critical magnetic field, in comparison with the unstrained original material. This study opens new avenues for retaining large and tunable elastic strains in great quantities of nanowires and elastic-strain-engineering at industrial scale.

20.
Sci Rep ; 5: 17530, 2015 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-26625854

RESUMO

Freestanding nanowires have been found to exhibit ultra-large elastic strains (4 to 7%) and ultra-high strengths, but exploiting their intrinsic superior mechanical properties in bulk forms has proven to be difficult. A recent study has demonstrated that ultra-large elastic strains of ~6% can be achieved in Nb nanowires embedded in a NiTi matrix, on the principle of lattice strain matching. To verify this hypothesis, this study investigated the elastic deformation behavior of a Nb nanowire embedded in NiTi matrix by means of in situ transmission electron microscopic measurement during tensile deformation. The experimental work revealed that ultra-large local elastic lattice strains of up to 8% are induced in the Nb nanowire in regions adjacent to stress-induced martensite domains in the NiTi matrix, whilst other parts of the nanowires exhibit much reduced lattice strains when adjacent to the untransformed austenite in the NiTi matrix. These observations provide a direct evidence of the proposed mechanism of lattice strain matching, thus a novel approach to designing nanocomposites of superior mechanical properties.

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