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Gloria Basile, Giorgio Baudana, Giulio Marchese, Massimo Lorusso, Mariangela Lombardi, Daniele Ugues, Paolo Fino, Sara Biamino
In this work, the characterization of the assembly of a steel shaft into a γ-TiAl part for turbocharger application, obtained using Electron Beam Welding (EBW) technology with a Ni-based filler, was carried out. The Ti-48Al-2Nb-0.7Cr-0.3Si (at %) alloy part was produced by Electron Beam Melting (EBM). This additive manufacturing technology allows the production of a lightweight part with complex shapes. The replacement of Nickel-based superalloys with TiAl alloys in turbocharger automotive applications will lead to an improvement of the engine performance and a substantial reduction in fuel consumption and emission...
January 17, 2018: Materials
Kamila J Bladek, Margaret E Reid, Hirotomo Nishihara, Farid Akhtar, Benjamin S Gelfand, George K H Shimizu
By complexing a bent phosphonate monoester ligand with cobalt(II), coupled with in situ ester hydrolysis, coordination microspheres (CALS=CALgary Sphere) are formed whereas the use of the phosphonic acid directly resulted in a sheet-like structure. Manipulation of the synthetic conditions gave spheres with different sizes, mechanical stabilities, and porosities. Time-dependent studies determined that the sphere formation likely occurred through the formation of a Co2+ and ligand chain that propagates in three dimensions through different sets of interactions...
January 16, 2018: Chemistry: a European Journal
Priyadarshi Ranjan, Sreejith Shankar, Ronit Popovitz-Biro, Sidney R Cohen, Iddo Pinkas, Reshef Tenne, Michal Lahav, Milko E van der Boom
We report here a new methodology for the formation of free-standing nanotubes composed of individual gold nanoparticles crosslinked by coordination complexes or porphyrin molecules using WS2 nanotubes (INT-WS2) as a template. Our method consists of three steps: (i) the coverage of these robust inorganic materials with monodispersed and dense monolayers of gold nanoparticles, (ii) formation of a molecular-AuNP network by exposing these decorated tubes to solutions containing a ruthenium polypyridyl complex or meso-tetra(4-pyridyl)porphyrin, (iii) removal of the INT-WS2 template with a hydrogen peroxide (H2O2) solution...
January 16, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
G E Gomez, R F D'vries, D F Lionello, L M Aguirre-Díaz, M Spinosa, C S Costa, M C Fuertes, R A Pizarro, A M Kaczmarek, J Ellena, L Rozes, M Iglesias, R Van Deun, C Sanchez, M A Monge, G J A A Soler-Illia
Main group element coordination polymers (MGE-CPs) are important compounds for the development of multifunctional materials. However, there has been a shortage of studies regarding their structural, optical, catalytic, mechanical, and antibacterial properties. This work presents an exhaustive study of a set of crystalline MGE-CPs obtained from bismuth and indium metals and iminodiacetate, 1,2,4,5-benzenetetracarboxylate, and 2,2'-bipyridine as building blocks. An in-depth topological analysis of the networks was carried out...
January 11, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Bruno Vidal, Rita Cascão, Mikko A J Finnilä, Inês P Lopes, Simo Saarakkala, Peter Zioupos, Helena Canhão, João E Fonseca
INTRODUCTION: Arthritis induces joint erosions and skeletal bone fragility. OBJECTIVES: The main goal of this work was to analyze the early arthritis induced events at bone architecture and mechanical properties at tissue level. METHODS: Eighty-eight Wistar rats were randomly housed in experimental groups, as follows: adjuvant induced arthritis (AIA) (N = 47) and a control healthy group (N = 41). Rats were monitored during 22 days for the inflammatory score, ankle perimeter and body weight and sacrificed at different time points (11 and 22 days post disease induction)...
2018: PloS One
Nirup Nagabandi, Cengiz Yegin, Xuhui Feng, Charles King, Jun Kyun Oh, Ethan Adam Scholar, Sreekant Narumanchi, Mustafa Akbulut
Herein, novel hybrid nanocomposite thermal interface materials (TIMs) relying on the chemical linkage of silver, boron nitride nanosheets (BNNSs), and organic ligands are reported. These TIMs were prepared using a co-electrodeposition/chemisorption approach where the electrolytic reduction of silver ions into silver nano-/micro-crystals was coupled with the conjugation of ligand-coated nanosheets onto silver crystals. Furthermore, the influence of bond strength of silver/nanosheet links on the thermal, mechanical, and structural properties is investigated using a combination of techniques; including laser flash analysis, phase-sensitive transient thermoreflectance, nanoindentation, and electron microscopy...
January 9, 2018: Nanotechnology
Hyung-In Yoon, Min-Jeong Jeon, Hye-Lee Kim, Do-Gyoon Kim, Jung-Suk Han
The aim of the study was to evaluate the spatial variations in the biomechanical properties of the bone around the implants retrieved from human subjects due to fixture head fracture after almost 20 years of loading. The implant-in-bone specimens were prepared for the histomorphometry and nanoindentation test to measure the bone-to-implant contact ratio (BIC ratio) and elastic modulus (E) of peri-implant bone. The indentations were performed in the up, center, down, and away regions of the bone tissues within all the thread spaces...
December 28, 2017: Journal of the Mechanical Behavior of Biomedical Materials
L Longley, N Li, F Wei, T D Bennett
A nanoporous three-dimensional metal-organic framework (MOF), ZnPurBr undergoes a transition to a previously unreported high-temperature phase, ZnPurBr-ht. The transition, which proceeds without mass loss, is uncovered through the use of differential scanning calorimetry (DSC). The new crystal structure was solved using single-crystal X-ray diffraction, and the mechanical properties of both phases investigated by nanoindentation and density functional theory. The anisotropy of the calculated Young's moduli showed good agreement with the crystallographic alignment of the stiff purinate organic linker...
November 2017: Royal Society Open Science
Vinicius P Fardin, Estevam A Bonfante, Paulo G Coelho, Malvin N Janal, Nick Tovar, Lukasz Witek, Dimorvan Bordin, Gerson Bonfante
OBJECTIVE: To evaluate the residual stress (nanoindentation based on hardness) of fatigued porcelain-fused to zirconia 3-unit fixed dental prostheses (FDP) with different framework designs. METHODS: Twenty maxillary 3-unit FDP replacing second-premolar (pontic) were fabricated with conventional framework-design (even-thickness of 0.5mm and 9mm2 connector area) and modified framework-design (thickness of 0.5mm presenting lingual collar connected to proximal struts and 12mm2 connector area)...
December 16, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
Tian Tian, Zhixin Zeng, Diana Vulpe, Mirian E Casco, Giorgio Divitini, Paul A Midgley, Joaquin Silvestre-Albero, Jin-Chong Tan, Peyman Z Moghadam, David Fairen-Jimenez
A critical bottleneck for the use of natural gas as a transportation fuel has been the development of materials capable of storing it in a sufficiently compact form at ambient temperature. Here we report the synthesis of a porous monolithic metal-organic framework (MOF), which after successful packing and densification reaches 259 cm3 (STP) cm-3 capacity. This is the highest value reported to date for conformed shape porous solids, and represents a greater than 50% improvement over any previously reported experimental value...
December 11, 2017: Nature Materials
Lanjiao Liu, Wenxiao Zhang, Li Li, Xinyao Zhu, Jinyun Liu, Xinyue Wang, Zhengxun Song, Hongmei Xu, Zuobin Wang
Colchicine is a drug commonly used for the treatment of gout, however, patients may sometimes encounter side-effects induced by taking colchicine, such as nausea, vomiting, diarrhea and kidney failure. In this regard, it is imperative to investigate the mechanism effects of colchicine on biological cells. In this paper, we present a method for the detection of mechanical properties of nephrocytes (VERO cells), hepatocytes (HL-7702 cells) and hepatoma cells (SMCC-7721 cells) in culture by atomic force microscope (AFM) to analyze the 0...
December 7, 2017: Journal of Biomechanics
T Vermeij, E Plancher, C C Tasan
Focused ion beam (FIB) milling has enabled the development of key microstructure characterization techniques (e.g. 3D electron backscatter diffraction (EBSD), 3D scanning electron microscopy imaging, site-specific sample preparation for transmission electron microscopy, site-specific atom probe tomography), and micro-mechanical testing techniques (e.g. micro-pillar compression, micro-beam bending, in-situ TEM nanoindentation). Yet, in most milling conditions, some degree of FIB damage is introduced via material redeposition, Ga+ ion implantation or another mechanism...
December 7, 2017: Ultramicroscopy
Y F Zhang, J Zheng, J X Yu, H T He
Human tooth enamel is a natural biocomposite consisting of mineral units surrounded by a soft protein shell. The mechanical behaviors of enamel are closely associated with its structure. In this paper, the strain-rate dependent mechanical properties of enamel were investigated with nanoindentation techniques. Five constant strain rates (0.01s-1, 0.03s-1, 0.05s-1, 0.1s-1, 0.3s-1) were used in this study. Results showed that the hardness and elastic modulus of enamel increased with increasing strain rate. These results indicate that the variation of hardness under different stain rates is associated with creep behavior of organic matrix in enamel...
December 7, 2017: Journal of the Mechanical Behavior of Biomedical Materials
D Arola, S Murcia, M Stossel, R Pahuja, T Linley, Arun Devaraj, M Ramulu, E A Ossa, J Wang
Fish scales serve as a flexible natural armor that have received increasing attention across the materials community. Most efforts in this area have focused on the composite structure of the predominately organic elasmodine, and limited work addresses the highly mineralized external portion known as the Limiting Layer (LL). This coating serves as the first barrier to external threats and plays an important role in resisting puncture. In this investigation the structure, composition and mechanical behavior of the LL were explored for three different fish, including the arapaima (Arapaima gigas), the tarpon (Megalops atlanticus) and the carp (Cyprinus carpio)...
December 14, 2017: Acta Biomaterialia
Christoffer Zehnder, Jan-Niklas Peltzer, James S K-L Gibson, Doris Möncke, Sandra Korte-Kerzel
In many daily applications glasses are indispensable and novel applications demanding improved strength and crack resistance are appearing continuously. Up to now, the fundamental mechanical processes in glasses subjected to high strain rates at room temperature are largely unknown and thus guidelines for one of the major failure conditions of glass components are non-existent. Here, we elucidate this important regime for the first time using glasses ranging from a dense metallic glass to open fused silica by impact as well as quasi-static nanoindentation...
December 15, 2017: Scientific Reports
Mariska G M van Rosmalen, Glen R Nemerow, Gijs J L Wuite, Wouter H Roos
Viruses are extensively studied as vectors for vaccine applications and gene therapies. For these applications, understanding the material properties of viruses is crucial for creating optimal functionality. Using atomic force microscopy (AFM) nanoindentation, we studied the mechanical properties of human adenovirus type 5 with the fiber of type 35 (Ad5F35) and compared it to viral capsids with a single point mutation in the protein VI precursor protein (pVI-S28C). Surprisingly, the pVI-S28C mutant turned out to be twice as stiff as the Ad5F35 capsids...
December 15, 2017: Journal of Biological Physics
Sung Hoon Hwang, Rouzbeh Shahsavari
Scaffolded porous submicron particles with well-defined diameter, shape and pore size have profound impacts in drug delivery, bone-tissue replacement, catalysis, sensors, photonic crystals and self-healing materials. However, understanding the interplay between pore size, particle size, and mechanical properties of such ultrafine particles, specially at the level of individual particles and their ensemble states, is a challenge. Herein, we focus on porous calcium-silicate submicron particles with various diameters - as a model system - and perform an extensive 900+ nanoindentations to completely map out their mechanical properties at three distinct structural forms from individual submicron particles to self-assembled ensembles to pressure-induced assembled arrays...
December 14, 2017: ACS Applied Materials & Interfaces
Zhiping Xiong, Gilberto Casillas, Ahmed A Saleh, Shaogang Cui, Elena V Pereloma
For the first time, deformation twinning and martensitic transformation were observed in retained austenite in a low-alloyed transformation-induced plasticity steel using nanoindentation in conjunction with electron backscattering diffraction and transmission electron microscopy. Dislocation glide, martensite formation and deformation twinning were correlated to pop-ins and deviation from linearity in the load-displacement curve. Deformation twinning was found to enhance the stability of retained austenite...
December 12, 2017: Scientific Reports
Aftab A Khan, Abdulaziz A Al-Kheraif, Abdullah M Al-Shehri, Eija Säilynoja, Pekka K Vallittu
This laboratory study was aimed to characterize semi-interpenetrating polymer network (semi-IPN) of fiber-reinforced composite (FRC) prepregs that had been stored for up to two years before curing. Resin impregnated prepregs of everStick C&B (StickTech-GC, Turku, Finland) glass FRC were stored at 4°C for various lengths of time, i.e., two-weeks, 6-months and 2-years. Five samples from each time group were prepared with a light initiated free radical polymerization method, which were embedded to its long axis in self-curing acrylic...
November 26, 2017: Journal of the Mechanical Behavior of Biomedical Materials
Christian Ganser, Caterina Czibula, Daniel Tscharnuter, Thomas Schöberl, Christian Teichert, Ulrich Hirn
Viscoelastic properties are often measured using probe based techniques such as nanoindentation (NI) and atomic force microscopy (AFM). Rarely, however, are these methods verified. In this article, we present a method that combines contact mechanics with a viscoelastic model (VEM) composed of springs and dashpots. We further show how to use this model to determine viscoelastic properties from creep curves recorded by a probe based technique. We focus on using the standard linear solid model and the generalized Maxwell model of order 2...
December 8, 2017: Soft Matter
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