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Maria Aznar, Sergi Roca-Bonet, David Reguera
One of the most important components of a virus is the protein shell or capsid 
 that encloses its genetic material. The main role of the capsid is to protect 
 the viral genome against external aggressions, facilitating its safe and 
 efficient encapsulation and delivery. As a consequence, viral capsids have 
 developed astonishing mechanical properties that are crucial for viral function. 
 These remarkable properties have started to be unveiled in single-virus 
 nanoindentation experiments, and are opening the door to the use of 
 viral-derived artificial nanocages for promising bio- and nano-technological 
May 17, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Dongce Ma, Ran Wang, Shuxun Chen, Tao Luo, Yu-Ting Chow, Dong Sun
Cancer cell migration and invasion, which are involved in tumour metastasis, are hard to predict and control. Numerous studies have demonstrated that physical cues influence cancer cell migration and affect tumour metastasis. In this study, we proposed the use of a microchannel chip equipped with a number of vertical constrictions to produce periodic compression forces on cells passing through narrow channels. The chip with repeated vertical confinement was applied on adherent MHCC-97L liver cancer cells and suspended OCI-AML leukaemia cells to determine the migration ability of these cancer cells...
March 2018: Biomicrofluidics
Dewy C van der Valk, Casper F T van der Ven, Mark C Blaser, Joshua M Grolman, Pin-Jou Wu, Owen S Fenton, Lang H Lee, Mark W Tibbitt, Jason L Andresen, Jennifer R Wen, Anna H Ha, Fabrizio Buffolo, Alain van Mil, Carlijn V C Bouten, Simon C Body, David J Mooney, Joost P G Sluijter, Masanori Aikawa, Jesper Hjortnaes, Robert Langer, Elena Aikawa
In calcific aortic valve disease (CAVD), microcalcifications originating from nanoscale calcifying vesicles disrupt the aortic valve (AV) leaflets, which consist of three (biomechanically) distinct layers: the fibrosa, spongiosa, and ventricularis. CAVD has no pharmacotherapy and lacks in vitro models as a result of complex valvular biomechanical features surrounding resident mechanosensitive valvular interstitial cells (VICs). We measured layer-specific mechanical properties of the human AV and engineered a three-dimensional (3D)-bioprinted CAVD model that recapitulates leaflet layer biomechanics for the first time...
May 3, 2018: Nanomaterials
Xuefeng Hu, Jyh-Wei Lee, Xi Zheng, Junhua Zhang, Xin Lin, Yingnan Song, Bingmei Wang, Xiaoxiao Hu, Hao-Hueng Chang, Yiping Chen, Chun-Pin Lin, Yanding Zhang
BACKGROUND: Although adult human tissue-derived epidermal stem cells are capable of differentiating into enamel-secreting ameloblasts and forming teeth with regenerated enamel when recombined with mouse dental mesenchyme that possesses odontogenic potential, the induction rate is relatively low. In addition, whether the regenerated enamel retains a running pattern of prism identical to and acquires mechanical properties comparable with human enamel indeed warrants further study. METHODS: Cultured human keratinocyte stem cells (hKSCs) were treated with fibroblast growth factor 8 (FGF8) and Sonic hedgehog (SHH) for 18 h or 36 h prior to being recombined with E13...
May 2, 2018: Stem Cell Research & Therapy
Youfeng Zhang, Yunje Oh, Douglas Stauffer, Andreas A Polycarpou
We present a highly sensitive force-displacement transducer capable of performing ultra-shallow nanoindentation and adhesion measurements. The transducer utilizes electrostatic actuation and capacitive sensing combined with microelectromechanical fabrication technologies. Air indentation experiments report a root-mean-square (RMS) force resolution of 1.8 nN and an RMS displacement resolution of 0.019 nm. Nanoindentation experiments on a standard fused quartz sample report a practical RMS force resolution of 5 nN and an RMS displacement resolution of 0...
April 2018: Review of Scientific Instruments
Radovan Žižka, Radim Čtvrtlík, Jan Tomaštík, Kamila Fačevicová, Ladislav Gregor, Jiří Šedý
Introduction: The purpose of this study was to examine the microhardness and modulus of elasticity (MOE) of White ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK) after setting in moist or dry intracanal conditions. Methods and Materials: To simulate root canal system, 14 polyethylen molds with internal diameter of 1 mm and height of 12 mm were used. These molds were filled with 9-mm thick layers of White ProRoot Mineral Trioxide Aggregate (MTA; Dentsply Tulsa Dental, Tulsa, OK)...
2018: Iranian Endodontic Journal
Marcel Enke, Lukas Köps, Stefan Zechel, Johannes C Brendel, Jürgen Vitz, Martin D Hager, Ulrich S Schubert
Aspartate incorporated into the protein structure of mussel byssal threads is believed to play an important role, besides the reversible histidine-zinc interactions, in the self-healing behavior of mussel byssal threads. Therefore, copolymers containing both aspartate and histidine moieties are synthesized in order to investigate the influence of aspartate on the complexation of zinc(II) as well as on the self-healing behavior and the mechanical properties of the resulting supramolecular networks. For this purpose, isothermal titration calorimetry measurements of a model aspartate compound as well as of these copolymers are performed and the thermodynamic parameters are utilized for the design of self-healing copolymers...
April 20, 2018: Macromolecular Rapid Communications
Yuan-Yuan Cui, Yun-Fei Jia, Fu-Zhen Xuan
Cyclic elastoplastic deformation behaviors of austenite phase and ferrite phase in a duplex stainless steel were investigate by load-controlled cyclic nanoindentation with a Berkovich indenter. During the tests, the maximum penetration depth per cycle increased rapidly with cycle number at transient state, and reached stable at quasi-steady state. Plastic dissipated energy was quantitatively proved to be the driving force for the propagation of deformation zones during cyclic nanoindentation tests. Transmission electron microscopy combined with FIB was used to reveal the deformation mechanisms of both phases underneath indents with cycles...
April 18, 2018: Scientific Reports
Laura W Gamer, Steven Pregizer, Jackson Gamer, Marina Feigenson, Andreia Ionescu, Qing Li, Lin Han, Vicki Rosen
Bone morphogenetic proteins (BMPs) are key regulators of skeletal development, growth and repair. While BMP signaling is required for synovial joint formation and is also involved in preserving joint function after birth, the role of specific BMP ligands in adult joint homeostasis remains unclear. The purpose of this study was to define the role of Bmp2 in the morphogenesis and maintenance of the knee joint. To do this, we first created Bmp2-LacZ and Gdf5-LacZ knock-in mice and compared their expression patterns in the developing and postnatal murine knee joint...
April 17, 2018: Journal of Bone and Mineral Research: the Official Journal of the American Society for Bone and Mineral Research
Imke A K Fiedler, Felix N Schmidt, Eva M Wölfel, Christine Plumeyer, Petar Milovanovic, Roberta Gioia, Francesca Tonelli, Hrishikesh A Bale, Katharina Jähn, Roberta Besio, Antonella Forlino, Björn Busse
Excessive skeletal deformations and brittle fractures in the vast majority of patients suffering from osteogenesis imperfecta (OI) are a result of substantially reduced bone quality. Since the mechanical competence of bone is dependent on the tissue characteristics at small length scales, it is of crucial importance to assess how osteogenesis imperfecta manifests at the micro- and nanoscale of bone. In this context, the Chihuahua (Chi/ +) zebrafish, carrying a heterozygous glycine substitution in the α1 chain of collagen type I, has recently been proposed as suitable animal model of classical dominant OI, showing skeletal deformities, altered mineralization patterns and a smaller body size...
April 17, 2018: Journal of Bone and Mineral Research: the Official Journal of the American Society for Bone and Mineral Research
S Azinas, F Bano, I Torca, D H Bamford, G A Schwartz, J Esnaola, H M Oksanen, R P Richter, N G Abrescia
The protection of the viral genome during extracellular transport is an absolute requirement for virus survival and replication. In addition to the almost universal proteinaceous capsids, certain viruses add a membrane layer that encloses their double-stranded (ds) DNA genome within the protein shell. Using the membrane-containing enterobacterial virus PRD1 as a prototype, and a combination of nanoindentation assays by atomic force microscopy and finite element modelling, we show that PRD1 provides a greater stability against mechanical stress than that achieved by the majority of dsDNA icosahedral viruses that lack a membrane...
April 16, 2018: Nanoscale
Patricia A Lopes, Adriana F P Carreiro, Rubens M Nascimento, Brendan R Vahey, Bruno Henriques, Júlio C M Souza
Objective: The purpose of this study was to investigate Morse taper implant-abutment joints by chemical, mechanical, and microscopic analysis. Materials and Methods: Surfaces of 10 Morse taper implants and the correlated abutments were inspected by field emission gun-scanning electron microscopy (FEG-SEM) before connection. The implant-abutment connections were tightened at 32 Ncm. For microgap evaluation by FEG-SEM, the systems were embedded in epoxy resin and cross-sectioned at a perpendicular plane of the implant-abutment joint...
January 2018: European Journal of Dentistry
Bowen Wang, Ruisong Chen, Fengrong Chen, Jingjing Dong, Zixiang Wu, Hu Wang, Zhao Yang, Faqi Wang, Jian Wang, Xiaofan Yang, Yafei Feng, Zheyuan Huang, Wei Lei, Haoyuan Liu
BACKGROUND Our study explored the influences of hydration conditions and loading methods on the mechanical properties of cortical bones and cancellous bones. MATERIAL AND METHODS Elastic modulus and hardness of human cortical bones and cancellous bones that contained different moisture levels (20%, 30%, 40%, 50%, and 60%) were measured with nanoindentation with different peak loads and loading rates. Cortical bones with 20% and 60% moisture were tested with 30 nm, 40 nm, and 50 nm peak loads at 6 nm/s, 8 nm/s, and 10 nm/s loading rates, respectively...
April 15, 2018: Medical Science Monitor: International Medical Journal of Experimental and Clinical Research
Louis G Malito, Sofia Arevalo, Adam Kozak, Stephen Spiegelberg, Anuj Bellare, Lisa Pruitt
This is the first study to simultaneously measure material properties in tension, compression, nanoindentation as well as microstructure (crystallinity and lamellar level properties) across a wide variety of clinically relevant ultra-high molecular weight polyethylene (UHMWPE) formulations. Methodologies for the measurement of UHMWPE mechanical properties-namely elastic modulus, yield stress, yield strain, ultimate strength, energetic toughness, Poisson's ratio, hardness and constitutive variables-are evaluated...
April 3, 2018: Journal of the Mechanical Behavior of Biomedical Materials
Sarah Pragnère, Caroline Boulocher, Ophélie Pollet, Catherine Bosser, Aurélie Levillain, Magali Cruel, Thierry Hoc
OBJECTIVE: The purpose of this study was to assess mechanical properties along with microstructural modifications of the hyaline cartilage (HC), calcified cartilage (CC) and cortical plate (Ct.Pt), in an anterior cruciate ligament transection (ACLT) model. Medial femoral condyles of six healthy rabbits (control group) and of six ACLT rabbits 6 weeks after OA induction were explanted. The zone of interest (ZOI) for all experiments was defined as the weight bearing areas of the samples...
April 3, 2018: Journal of the Mechanical Behavior of Biomedical Materials
Abby E Peters, Riaz Akhtar, Eithne J Comerford, Karl T Bates
Osteoarthritis is traditionally associated with cartilage degeneration although is now widely accepted as a whole-joint disease affecting the entire osteochondral unit; however site-specific cartilage and bone material properties during healthy ageing and disease are absent limiting our understanding. Cadaveric specimens (n = 12; 31-88 years) with grades 0-4 osteoarthritis, were dissected and spatially correlated cartilage, subchondral and trabecular bone samples (n = 8 per cadaver) were harvested from femoral and tibial localities...
April 12, 2018: Scientific Reports
Miguel Gonzalez-Andrades, Roholah Sharifi, Mohammad-Mirazul Islam, Thibaut Divoux, Michael Haist, Eleftherios Paschalis, Larisa Gelfand, Shamina Mamodaly, Luca Di Cecilia, Andrea Cruzat, Franz-Josef Ulm, James Chodosh, Francois Delori, Claes H Dohlman
PURPOSE: To make the Boston keratoprosthesis (B-KPro), together with its carrier corneal graft, more easily procured, transported and stored, as well as less expensive, easier for the surgeon to implant and safer for the patient, it is proposed that the B-KPro-graft combination be pre-assembled by an expert technician, followed by sterilization with gamma ray irradiation (GI) allowing long-term storage at room temperature. For this to be possible, it must be shown that the B-KPro itself (not only the graft) remains unharmed by the irradiation...
April 5, 2018: Ocular Surface
Baran Sarac, Yurii P Ivanov, Andrey Chuvilin, Thomas Schöberl, Mihai Stoica, Zaoli Zhang, Jürgen Eckert
The large plasticity observed in newly developed monolithic bulk metallic glasses under quasi-static compression raises a question about the contribution of atomic scale effects. Here, nanocrystals on the order of 1-1.5 nm in size are observed within an Fe-based bulk metallic glass using aberration-corrected high-resolution transmission electron microscopy (HRTEM). The accumulation of nanocrystals is linked to the presence of hard and soft zones, which is connected to the micro-scale hardness and elastic modulus confirmed by nanoindentation...
April 6, 2018: Nature Communications
Siqi Ying, Lifeng Ma, Tan Sui, Chrysanthi Papadaki, Enrico Salvati, Leon Romano Brandt, Hongjia Zhang, Alexander M Korsunsky
Nickel superalloys play a pivotal role in enabling power-generation devices on land, sea, and in the air. They derive their strength from coherent cuboidal precipitates of the ordered γ' phase that is different from the γ matrix in composition, structure and properties. In order to reveal the correlation between elemental distribution, dislocation glide and the plastic deformation of micro- and nano-sized volumes of a nickel superalloy, a combined in situ nanoindentation compression study was carried out with a scanning electron microscope (SEM) on micro- and nano-pillars fabricated by focused ion beam (FIB) milling of Ni-base superalloy CMSX4...
April 5, 2018: Materials
Kamran Ali, Sivaprasad Narayana, R A Shakoor, Paul C Okonkwo, Moinuddin M Yusuf, Abdullah Alashraf, Ramazan Kahraman
This research work presents the microscopic analysis of pulse electrodeposited Ni-AlN nanocomposite coatings using SEM and AFM techniques and their performance evaluation (mechanical and electrochemical) by employing nanoindentation and electrochemical methods. The Ni-AlN nanocomposite coatings were developed by pulse electrodeposition. The nickel matrix was reinforced with various amounts of AlN nanoparticles (3, 6, and 9 g/L) to develop Ni-AlN nanocomposite coatings. The effect of reinforcement concentration on structure, surface morphology, and mechanical and anticorrosion properties was studied...
2018: Scanning
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