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Zhengdi He, Lingling Chen, Xuejuan Hu, Yasushi Shimada, Masayuki Otsuki, Junji Tagami, Shuangchen Ruan
The purpose of this study was to evaluate the chemical and mechanical modifications in subsurface dentin layer after Er: YAG (Erbium-Yttrium Aluminium Garnet) laser irradiation, as the guidance of new dental restorative materials specific for laser irradiated dentin. MATERIALS AND METHODS: Dentin disks obtained from extracted human molars were prepared and exposed to a single pulse Er:YAG laser irradiation at 80mJ/pulse. After laser irradiation the mechanical and chemical characteristics of intertubular dentin in subsurface layer were studied using nanoindentation tester and micro-Raman spectromy (μ-RS)...
June 3, 2017: Journal of the Mechanical Behavior of Biomedical Materials
Ippei Hamanaka, Misa Iwamoto, Lippo V J Lassila, Pekka K Vallittu, Yutaka Takahashi
Objective This study investigated the wear resistance of injection-molded thermoplastic denture base resins using nanoindentation instrument. Materials and methods Six injection-molded thermoplastic denture base resins (two polyamides, two polyesters, one polycarbonate, one polymethylmethacrylate [PMMA]) and a PMMA conventional heat-polymerized denture-based polymer control were tested. Elastic modulus, hardness, wear depth, and roughness were calculated using a nanoindentation instrument. Results Elastic modulus and hardness of the injection-molded thermoplastic denture base resins were significantly lower than those of the PMMA conventional heat-polymerized denture-based polymer...
December 2016: Acta Biomaterialia Odontologica Scandinavica
Tooba Shoaib, Prathima Chandra Nalam, Yichen He, Yuting Chen, Rosa M Espinosa-Marzal
Recognizing the limitations of solid-supported lipid bilayers to reproduce the behavior of cell membranes, including bendability, transmembrane protein inclusion and virus entry, this study describes a novel biomimetic system for cell membranes with the potential to overcome these and other limitations. The developed strategy utilizes a hydrogel with tunable mechanical behavior that resembles those of living cells as the soft support for the phospholipid bilayer, while a polyelectrolyte multilayer film serves as an intermediate layer to facilitate the self-assembly of the lipid bilayer on the soft cushion...
June 21, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Fang Wang, S S Jyothirmayee Aravind, Hao Wu, Joseph Forys, Venkat Venkataraman, Kandalam Ramanujachary, Xiao Hu
Green graphene materials prepared by photoreduction of graphite oxide were first time blended with aqueous-based silk fibroin proteins to improve the mechanical and thermal properties of silk biomaterials, and their nanocomposite interaction mechanism was illustrated. Powder X-ray diffraction (XRD) analysis confirmed the complete exfoliation of graphite oxide to graphene in presence of focused pulses of solar radiation. By varying the concentration of graphene (0.1wt% to 10wt%), a series of free standing graphene-silk films were prepared and were systematically characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and nanoindentation measurements...
October 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
J Mora-Macías, A Pajares, P Miranda, J Domínguez, E Reina-Romo
Nanoindentation has been used successfully in the determination of the mechanical properties of bone. Its application in fracture healing provides information on the evolution of material properties of the woven bone during regeneration process. However, this technique has not been applied in assessing the mechanical properties of woven bone during distraction osteogenesis. Therefore, the aim of this work is to evaluate the spatial and temporal variations of the elastic modulus of the woven bone generated during the bone transport process...
June 1, 2017: Journal of the Mechanical Behavior of Biomedical Materials
Matthew Faulkner, Jorge Rodriguez-Ramos, Gregory F Dykes, Siân V Owen, Selene Casella, Deborah M Simpson, Robert J Beynon, Lu-Ning Liu
Carboxysomes are proteinaceous organelles that play essential roles in enhancing carbon fixation in cyanobacteria and some proteobacteria. These self-assembling organelles encapsulate Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) and carbonic anhydrase using a protein shell structurally resembling an icosahedral viral capsid. The protein shell serves as a physical barrier to protect enzymes from the cytosol and a selectively permeable membrane to mediate transport of enzyme substrates and products...
June 15, 2017: Nanoscale
Biljana Janković, Tatjana Joksimović, Jernej Stare, Evgeniy Losev, Viktoriya Zemtsova, Stane Srčič, Elena Boldyreva
The nanomechanical properties of the α-, β-, and γ- conformational polymorphs of chlorpropamide were determined by the dynamic contact module continuous stiffness measurement at nanoindenter. The mechanical anisotropy of the α-polymorph was confirmed by indenting different faces, and its deformational behavior was assigned as ductile. Based on the nanoindentation results, the β and γ forms are moderately hard with plastic flow at contact points. The results revealed a correlation between Young's modulus and inter-planar interaction energy with regard to crystal orientation...
June 9, 2017: European Journal of Pharmaceutical Sciences
Christopher L Salinas, Enrique Escobar de Obaldia, Chanhue Jeong, Jessica Hernandez, Pablo Zavattieri, David Kisailus
Gastropods shells have evolved to resist the threat of increasingly stronger predators that smash, peal, and crush their shells. Their shells are most commonly constructed from a crossed lamellar microstructure, which consists of an exquisitely architected arrangement of aragonitic mineral and organic encompassing at least four orders of hierarchy. It is this careful control of mineral and organic placement within the entire crossed lamellar structure that yields a four-order of magnitude increase in fracture toughness versus abiotic aragonite...
May 31, 2017: Journal of the Mechanical Behavior of Biomedical Materials
Ping Hu, Shun Dong, Xinghong Zhang, Kaixuan Gui, Guiqing Chen, Ze Hu
Several-millimeter long SiC nanowires (NWs) with unique optical properties, excellent thermal stability and flexible nanomechanical properties were synthesized using a simple method with silicon and phenolic resin as the raw materials. The SiC NWs displayed special optical properties that were attributed to their large size and Al-doping. They displayed broad green emission at 527.8 nm (2.35 eV) and purple emission concentrated at 438.9 nm (2.83 eV), in contrast to the other results, and the synthesized SiC NWs could also remain relatively stable in air up to 1000 °C indicating excellent thermal stability...
June 7, 2017: Scientific Reports
Emily Callard Preedy, Stefano Perni, Polina Prokopovich
Bone cells are damaged by wear particles originating from total joint replacement implants. We investigated Mesenchymal stem cells (MSCs) nanomechanical properties when exposed to cobalt and titanium nanoparticles (resembling wear debris) of different sizes for up to 3days using AFM nanoindentation; along with flow-cytometry and MTT assay. The results demonstrated that cells exposed to increasing concentrations of nanoparticles had a lower value of elasticity and spring constant without significant effect on cell metabolic activity and viability but some morphological alteration (bleeping)...
May 10, 2017: Colloids and Surfaces. B, Biointerfaces
F Sciortino, M Thivolle, M L Kahn, C Gaillard, S Chevance, F Gauffre
Our group recently introduced a new process to synthesize nanoparticle shells of about 100 nm, named "hybridosomes®". Here, the structure and mechanical properties of hybridosomes® made from iron oxide nanoparticles and poly(acrylic acid) are characterized using TEM, AFM and an osmotic compression technique. For the latter, the size distribution of the hybridosomes is monitored by nanoparticle tracking analysis (NTA) in the presence of poly(ethylene glycol)s of different molecular weights. It is found that the size of the hybridosomes® can be tuned from ca...
June 21, 2017: Soft Matter
Chady Ghnatios, Christian H Mathis, Rok Simic, Nicholas D Spencer, Francisco Chinesta
Understanding sliding and load-bearing mechanisms of biphasic soft matter is crucial for designing synthetic replacements of cartilage, contact-lens materials or coatings for medical instruments. Interstitial fluid pressurization is believed to be the intrinsic load-carrying phenomenon governing the frictional properties. In this study, we have characterized permeability and identified the fluid contribution to the support of load during Atomic Force Microscopy (AFM) nanoindentation of soft polymer brushes in aqueous environments, by means of the Proper Generalized Decomposition (PGD) approach...
June 5, 2017: Soft Matter
J Kreith, T Strunz, E J Fantner, G E Fantner, M J Cordill
A versatile atomic force microscope (AFM), which can be installed in a scanning electron microscope (SEM), is introduced. The flexible design of the instrument enables correlated analysis for different experimental configurations, such as AFM imaging directly after nanoindentation in vacuum. In order to demonstrate the capabilities of the specially designed AFM installed inside a SEM, slip steps emanating around nanoindents in single crystalline brass were examined. This example showcases how the combination of AFM and SEM imaging can be utilized for quantitative dislocation analysis through the measurement of the slip step heights without the hindrance of oxide formation...
May 2017: Review of Scientific Instruments
David Labonte, Anne-Kristin Lenz, Michelle L Oyen
The remarkable mechanical performance of biological materials is based on intricate structure-function relationships. Nanoindentation has become the primary tool for characterising biological materials, as it allows to relate structural changes to variations in mechanical properties on small scales. However, the respective theoretical background and associated interpretation of the parameters measured via indentation derives largely from research on 'traditional' engineering materials such as metals or ceramics...
May 22, 2017: Acta Biomaterialia
Wen-Hsien Kao, Yean-Liang Su, Jeng-Haur Horng, Yun-Ting Hsieh
AISI 316L specimens were nitrided using a low temperature (390℃) plasma nitriding process and then coated with a thin layer of titanium nitride by closed field unbalanced magnetron sputtering. The microstructure, adhesion properties and hardness of the duplex-treated samples were examined using X-ray diffraction, scratch testing and nanoindentation, respectively. In addition, the tribological properties were investigated by means of reciprocating wear tests performed against 316L, Si3N4 and Ti6Al4V balls under a load of 10 N for 24 min in 0...
January 1, 2017: Journal of Biomaterials Applications
Izabela Zgłobicka, Adrian Chlanda, Michał Woźniak, Maciej Łojkowski, Robert Szoszkiewicz, Marta Mazurkiewicz-Pawlicka, Wojciech Święszkowski, Elżbieta Wyroba, Krzysztof J Kurzydłowski
We present topographical and nanomechanical characterization of single Didymosphenia geminata stalk. We compared the samples before and after adsorption of metal ions from freshwater samples. Transmission electron microscopy studies of single stalk cross-sections have shown three distinct layers and an additional thin extra coat on the external layer (called "EL"). Using scanning electron microscopy and atomic force microscopy (AFM), we found that topography of single stalks after ionic adsorption differed significantly from topography of pristine stalks...
May 18, 2017: Journal of Phycology
S Youssefian, J E Jakes, N Rahbar
A combination of experimental, theoretical and numerical studies is used to investigate the variation of elastic moduli of lignocellulosic (bamboo) fiber cell walls with moisture content (MC). Our Nanoindentation results show that the longitudinal elastic modulus initially increased to a maximum value at about 3% MC and then decreased linearly with increasing MC. In contrast, the transverse moduli decrease linearly with MC. We showed that amorphous materials in cell walls have key roles in the variation of elastic modulus with increasing MC...
May 17, 2017: Scientific Reports
Tina Ukmar-Godec, Luca Bertinetti, John W C Dunlop, Aljaž Godec, Michal A Grabiger, Admir Masic, Huynh Nguyen, Igor Zlotnikov, Paul Zaslansky, Damien Faivre
Teeth are designed to deliver high forces while withstanding the generated stresses. Aside from isolated mineral-free exception (e.g., marine polychaetes and squids), minerals are thought to be indispensable for tooth-hardening and durability. Here, the unmineralized teeth of the giant keyhole limpet (Megathura crenulata) are shown to attain a stiffness, which is twofold higher than any known organic biogenic structures. In these teeth, protein and chitin fibers establish a stiff compact outer shell enclosing a less compact core...
May 9, 2017: Advanced Materials
Qi Zhang, Zhenbo Qin, Qin Luo, Zhong Wu, Lei Liu, Bin Shen, Wenbin Hu
A reduced graphene oxide/copper (RGO/Cu) composite was fabricated by a surfactant free, electroless co-deposition technique. The graphene oxide (GO) sheets were reduced and RGO homogeneous distributed into the copper matrix. On the basis of nanoindentation, the presence of RGO and the increase of its content in matrix significantly raised the hardness of RGO/Cu composites. Here, the relevant strengthening effect and mechanisms involved in RGO-reinforced Cu composites were systematically evaluated. Especially, the addition of RGO in Cu matrix led to the compressive micro-strain, and the resulted distortion of the lattice parameter was calculated based on Cohen's method...
May 2, 2017: Scientific Reports
Marcos A Reyes-Martinez, Ahmed L Abdelhady, Makhsud I Saidaminov, Duck Young Chung, Osman M Bakr, Mercouri G Kanatzidis, Wole O Soboyejo, Yueh-Lin Loo
The ease of processing hybrid organic-inorganic perovskite (HOIPs) films, belonging to a material class with composition ABX3 , from solution and at mild temperatures promises their use in deformable technologies, including flexible photovoltaic devices, sensors, and displays. To successfully apply these materials in deformable devices, knowledge of their mechanical response to dynamic strain is necessary. The authors elucidate the time- and rate-dependent mechanical properties of HOIPs and an inorganic perovskite (IP) single crystal by measuring nanoindentation creep and stress relaxation...
June 2017: Advanced Materials
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