Micro-to-nano-scale deformation mechanisms of a bimodal ultrafine eutectic composite.
Ontology highlight
ABSTRACT:
SUBMITTER: Lee SW
PROVIDER: S-EPMC4179130 | biostudies-other | 2014
REPOSITORIES: biostudies-other
Similar Datasets
Project description:In the present study, the microstructural evolution and the modulation of the mechanical properties have been investigated for a Co-Cr-Mo (CCM) ternary eutectic alloy by addition of a small amount of copper (0.5 and 1 at.%). The microstructural observations reveal a distinct dissimilarity in the eutectic structure such as a broken lamellar structure and a well-aligned lamellar structure and an increasing volume fraction of Co lamellae as increasing amount of copper addition. This microstructural evolution leads to improved plasticity from 1% to 10% without the typical tradeoff between the overall strength and compressive plasticity. Moreover, investigation of the fractured samples indicates that the CCMCu alloy exhibits higher plastic deformability and combinatorial mechanisms for improved plastic behavior. The improved plasticity of CCMCu alloys originates from several deformation mechanisms; i) slip, ii) deformation twinning, iii) strain-induced transformation and iv) shear banding. These results reveal that the mechanical properties of eutectic alloys in the Co-Cr-Mo system can be ameliorated by micro-alloying such as Cu addition.
| S-EPMC5220307 | biostudies-literature
Project description:This work reports on a novel controlled nanocomposite fabrication technique which is applicable for material design via a micro- and nano-assembly method. The principle is based on the use of electrostatic adsorption of the surface charge-modified particles via layer-by-layer assembly. The polarity and the zeta potential of the surface charge was controlled using polycation and polyanion, while the zeta potential strength was controlled via the number of alternating coating layers which was determined using zeta potential measurement. A systematic study was conducted to demonstrate the feasibility of composite material assembly via electrostatic adsorption using alumina (Al2O3) and silica (SiO2) composite as a study model, which was carried out as a function of surface zeta potential, surface coverage percentage, and processing time. The considerable potential of this technique for composite material design is also further demonstrated with controlled assembly involving different materials in various structural forms such as fiber, whisker, nanosheets, and even irregular-shaped foam-like structured urethane. The composite materials designed using this EA method possess good potentials to be utilized for various applications such as mechanical property control, composite ceramic films formation, selective laser sintering, and rechargeable metal-air battery.
| S-EPMC6713769 | biostudies-literature
Project description:BackgroundAlthough the use of cardiac patches is still controversial, cardiac patch has the significance in the field of the tissue engineered cardiac regeneration because it overcomes several shortcomings of intra-myocardial injection by providing a template for cells to form a cohesive sheet. So far, fibrous scaffolds fabricated using electrospinning technique have been increasingly explored for preparation of cardiac patches. One of the problems with the use of electrospinning is that nanofibrous structures hardly allow the infiltration of cells for development of 3D tissue construct. In this respect, we have prepared novel bi-modal electrospun scaffolds as a feasible strategy to address the challenges in cardiac tissue engineering .MethodsNano/micro bimodal composite fibrous patch composed of collagen and poly (D, L-lactic-co-glycolic acid) (Col/PLGA) was fabricated using an independent nozzle control multi-electrospinning apparatus, and its feasibility as the stem cell laden cardiac patch was systemically investigated.ResultsNano/micro bimodal distributions of Col/PLGA patches without beaded fibers were obtained in the range of the 4-6% collagen concentration. The poor mechanical properties of collagen and the hydrophobic property of PLGA were improved by co-electrospinning. In vitro experiments using bone marrow-derived mesenchymal stem cells (BMSCs) revealed that Col/PLGA showed improved cyto-compatibility and proliferation capacity compared to PLGA, and their extent increased with increase in collagen content. The results of tracing nanoparticle-labeled as well as GFP transfected BMSCs strongly support that Col/PLGA possesses the long-term stem cells retention capability, thereby allowing stem cells to directly function as myocardial and vascular endothelial cells or to secrete the recovery factors, which in turn leads to improved heart function proved by histological and echocardiographic findings.ConclusionCol/PLGA bimodal cardiac patch could significantly attenuate cardiac remodeling and fully recover the cardiac function, as a consequence of their potent long term stem cell engraftment capability.
| S-EPMC9749239 | biostudies-literature
Project description:The successful treatment of malignant disease generally requires the use of multiple therapeutic agents that are coordinated in a spatiotemporal manner to enable synergy. Here, a porous silicon-based micro/nano composite (MNC) that is capable of simultaneously delivering chemotherapeutic agents and small interfering RNA (siRNA) to the lungs following intravenous injection is designed. The pores of the silicon microparticles are loaded with B-Raf proto-oncogene serine/threonine kinase (BRAF) siRNA-containing liposomes, while the surface is conjugated with docetaxel-encapsulated polymeric nanoparticles. The synergistic antitumor effect of the MNC is demonstrated in vitro in melanoma cells and in vivo using a mouse model for melanoma lung metastasis. The MNC displays superior therapeutic efficacy and increased accumulation in metastatic melanoma lesions in the lungs in comparison to combination therapy with liposomes and polymers. The results indicate that the MNC can be used as an effective delivery vehicle for simultaneous enrichment of multiple therapeutic agents in the lungs.
| S-EPMC4837059 | biostudies-literature
Project description:Insulator based dielectrophoresis (iDEP) is becoming increasingly important in emerging biomolecular applications, including particle purification, fractionation, and separation. Compared to conventional electrode-based dielectrophoresis (eDEP) techniques, iDEP has been demonstrated to have a higher degree of selectivity of biological samples while also being less biologically intrusive. Over the past two decades, substantial technological advances have been made, enabling iDEP to be applied from micro, to nano and molecular scales. Soft particles, including cell organelles, viruses, proteins, and nucleic acids, have been manipulated using iDEP, enabling the exploration of subnanometer biological interactions. Recent investigations using this technique have demonstrated a wide range of applications, including biomarker screening, protein folding analysis, and molecular sensing. Here, we review current state-of-art research on iDEP systems and highlight potential future work.
| S-EPMC7570478 | biostudies-literature
Project description:The filling behavior of polymers in narrow gaps or small pores is important for the dynamics of polymeric micro/nanostructure fabrication. Here, the filling behavior, the mechanical properties, and the stress versus strain relationship of 996 kD poly (methyl methacrylate) (PMMA) at a scale from micron to molecular confinement are measured. It has been found that the solid polymer exhibits elastic-plastic dominant deformation behavior at micron scale. As the scale reduces to submicron, the resistance to deformation of the polymeric solid has a pronounced reduction. A softening effect and the visco-dominant behavior which is always exhibited by melt flow is observed. In confinement conditions, an anomalous hardening effect is found. The modulus and the hardness of 996 kD PMMA have been found to increase dramatically. The stress-strain curve also exhibits an obvious hardening phenomenon which is contrary to the conventional shear thinning and deformation acceleration results. The results of this paper show that the PMMA can exhibit a change of "solid-fluid-solid" in mechanical character at micron to molecular confinement scale.
| S-EPMC5554152 | biostudies-other
Project description:The conventional engineering stress-strain curve could not accurately describe the true stress-strain and local deformability of the necking part of tensile specimens, as it calculates the strain by using the whole gauge length, assuming the tensile specimen was deformed uniformly. In this study, we employed 3D optical measuring digital image correlation (DIC) to systematically measure the full strain field and local strain during the whole tensile process, and calculate the real-time strain and actual flow stress in the necking region of ultrafine-grained (UFG) Ti. The post-necking elongation and strain hardening exponent of the UFG Ti necking part were then measured as 36% and 0.101, slightly smaller than those of the coarse grained Ti (52% and 0.167), suggesting the high plastic deformability in the necking part of the UFG Ti. Finite elemental modeling (FEM) indicates that when necking occurs, strain is concentrated in the necking region. The stress state of the necking part was transformed from uniaxial in the uniform elongation stage to a triaxial stress state. A scanning electron microscopic (SEM) study revealed the shear and ductile fracture, as well as numerous micro shear bands in the UFG Ti, which are controlled by cooperative grain boundary sliding. Our work revealed the large plastic deformability of UFG metals in the necking region under a complex stress state.
| S-EPMC7996532 | biostudies-literature
Project description:Although ZnSe has been widely studied due to its attractive electronic and optoelectronic properties, limited data on its plastic deformations are available. Through molecular dynamics simulations, we have investigated the indentations on the (001), (110), and (111) planes of ZnSe nano films. Our results indicate that the elastic modulus, incipient plasticity, elastic recovery ratio, and the structural evolutions during the indenting process of ZnSe nano films show obvious anisotropy. To analyze the correlation of structural evolution and mechanical responses, the atomic displacement vectors, atomic arrangements, and the dislocations of the indented samples are analyzed. Our simulations revealed that the plastic deformations of the indented ZnSe nano films are dominated by the nucleation and propagation of 1/2<110> type dislocations, and the symmetrically distributed prismatic loops emitted during the indenting process are closely related with the mechanical properties. By studying the evolutions of microstructures, the formation process of the dislocations, as well as the formation mechanisms of the emitted prismatic loops under the indented crystalline planes are discussed. The results presented in this work not only provide an answer for the questions about indentation responses of ZnSe nano films, but also offer insight into its plastic deformation mechanisms.
| S-EPMC8619347 | biostudies-literature
Project description:Neutrophilic, microaerobic Fe(II)-oxidizing bacteria (FeOB) from marine and freshwater environments are known to generate twisted ribbon-like organo-mineral stalks. These structures, which are extracellularly precipitated, are susceptible to chemical influences in the environment once synthesized. In this paper, we characterize the minerals associated with freshwater FeOB stalks in order to evaluate key organo-mineral mechanisms involved in biomineral formation. Micro-Raman spectroscopy and Field Emission Scanning Electron Microscopy revealed that FeOB isolated from drinking water wells in Sweden produced stalks with ferrihydrite, lepidocrocite and goethite as main mineral components. Based on our observations made by micro-Raman Spectroscopy, field emission scanning electron microscopy and scanning transmission electron microscope combined with electron energy-loss spectroscopy, we propose a model that describes the crystal-growth mechanism, the Fe-oxidation state, and the mineralogical state of the stalks, as well as the biogenic contribution to these features. Our study suggests that the main crystal-growth mechanism in stalks includes nanoparticle aggregation and dissolution/re-precipitation reactions, which are dominant near the organic exopolymeric material produced by the microorganism and in the peripheral region of the stalk, respectively.
| S-EPMC7442631 | biostudies-literature
Project description:Microneedles, fabricated by nano-moulding technology show great promise in the field of drug delivery by enabling the painless self-administration of drugs in a patient-friendly manner. In this study, double-stranded salmon DNA (SDNA) was used as both a drug-delivery vehicle and structural material with a microneedle system. SDNA is non-toxic and demonstrates good mechanical robustness, mouldability, biocompatibility, bio-absorbability, and binding affinity with drug molecules for bio-functional applications. Benign fabrication conditions to protect temperature-sensitive biomolecules are used to produce SDNA structures of various sizes with a high aspect ratio (4: 1). Unlike existing dissolving microneedle structure materials, the special binding characteristics of doxorubicin hydrochloride, anti-cancer drug molecules, and SDNA demonstrate the stability of drug-molecule encapsulation via UV-absorption and photoluminescence analyses. Based on COMSOL simulation and in vitro analysis of the stratum corneum of porcine skin, the mechanical functionality of SDNA microneedles was evaluated in vitro by penetrating the stratum corneum of porcine skin. The SDNA microneedle dissolved and drug permeation was assessed using rhodamine, a drug surrogate. Owing to its many beneficial characteristics, we anticipate that the SDNA microneedle platform will serve as an effective alternative for drug delivery.
| S-EPMC5574990 | biostudies-literature