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Jorge Bustamante, Jason F Panzarino, Timothy J Rupert, Catherine Loudon
The mechanical properties of bed bug (Cimex lectularius L.) tarsi and pretarsi were investigated in order to evaluate their vulnerability to piercing by plant trichomes (sharp microscopic hairs). Nanoindentation was used to measure the force required to insert a sharp probe into the cuticle of these different regions, as well as to determine creep and reduced elastic moduli for the cuticle. Scanning electron microscopy was used to visualize the indents that had been generated by nanoindentation. The force required to insert a cube corner nanoindenter probe into the cuticle was determined for a range of displacements (1 to 9 µm) and strain rates (0...
September 21, 2017: Biology Open
Borislav Vasic, Aleksandar Matkovic, Rados Gajic
We investigate phase imaging of supported graphene using amplitude modulation atomic force microscopy (AFM), so called, tapping mode. The phase contrast between graphene and neighbouring substrate grows at hard tapping conditions and the contrast is enhanced compared to the topographic one. Therefore, the phase measurements could enable a high contrast imaging of graphene and related two dimensional materials and heterostructures, not achievable with conventional AFM based topographic measurements. Obtained phase maps are then transformed into energy dissipation maps which are important for graphene applications in various mechanical systems...
September 21, 2017: Nanotechnology
Siddhartha Pathak, Surya R Kalidindi, Jordan S Weaver, Yongqiang Wang, Russell P Doerner, Nathan A Mara
We discuss and demonstrate the application of recently developed spherical nanoindentation stress-strain protocols in characterizing the mechanical behavior of tungsten polycrystalline samples with ion-irradiated surfaces. It is demonstrated that a simple variation of the indenter size (radius) can provide valuable insights into heterogeneous characteristics of the radiation-induced-damage zone. We have also studied the effect of irradiation for the different grain orientations in the same sample.
September 20, 2017: Scientific Reports
Maria Koifman Khristosov, Shiri Dishon, Imrit Noi, Alex Katsman, Boaz Pokroy
Nanoporous gold is widely used in research and nanotechnology because of its diverse properties, including high surface area and catalytic activity. The ligament size is usually considered as one of the main parameters controlling thermal stability and mechanical properties of nanoporous gold. Recently we developed a method for creating nanoporous single crystal gold particles using eutectic decomposition of Au-Ge, followed by selective etching of Ge. Here, we used this novel method to create nanoporous gold particles with controlled ligament sizes by changing the initial sample's relative concentrations of gold and germanium...
September 19, 2017: Nanoscale
Kathryn M Kumamoto, Christopher A Thom, David Wallis, Lars N Hansen, David E J Armstrong, Jessica M Warren, David L Goldsby, Angus J Wilkinson
The strength of olivine at low temperatures and high stresses in Earth's lithospheric mantle exerts a critical control on many geodynamic processes, including lithospheric flexure and the formation of plate boundaries. Unfortunately, laboratory-derived values of the strength of olivine at lithospheric conditions are highly variable and significantly disagree with those inferred from geophysical observations. We demonstrate via nanoindentation that the strength of olivine depends on the length scale of deformation, with experiments on smaller volumes of material exhibiting larger yield stresses...
September 2017: Science Advances
M Arnold, S Zhao, S Ma, F Giuliani, U Hansen, J P Cobb, R L Abel, O Boughton
OBJECTIVES: Microindentation has the potential to measure the stiffness of an individual patient's bone. Bone stiffness plays a crucial role in the press-fit stability of orthopaedic implants. Arming surgeons with accurate bone stiffness information may reduce surgical complications including periprosthetic fractures. The question addressed with this systematic review is whether microindentation can accurately measure cortical bone stiffness. METHODS: A systematic review of all English language articles using a keyword search was undertaken using Medline, Embase, PubMed, Scopus and Cochrane databases...
September 2017: Bone & Joint Research
Cem Simsek, Sibel Oto, Gursel Yilmaz, Dilek Dursun Altinors, Ahmet Akman, Sirel Gur Gungor
PURPOSE: To evaluate the elastic modulus, hardness, and mechanical properties of the anterior lens capsule in different types of cataract and to assess the correlation with age. SETTING: Baskent University Hospital, Department of Ophthalmology, Ankara, Turkey. DESIGN: Prospective comparative study. METHODS: Patients were divided into 3 groups. Group 1 comprised patients with senile cataract, Group 2 patients had pseudoexfoliation (PXF) syndrome, and Group 3 patients had dye-enhanced cataract surgery...
August 2017: Journal of Cataract and Refractive Surgery
Gordon A MacDonald, Chelsea M Heveran, Mengjin Yang, David Moore, Kai Zhu, Virginia L Ferguson, Jason P Killgore, Frank William DelRio
In this letter, methylammonium lead iodide (MAPbI3) thin films were examined via piezoresponse force microscopy (PFM) and nanoindentation (NI) to determine if long-range atomic order existed across the full width and depth of the apparent grains. From the PFM, the piezoelectric response of the films was strongly correlated with low-index planes of the crystal structure and ferroelastic domains in macro-scale solution-grown MAPbI3 crystals, which implied long-range order near the top surface. From the NI, it was found that the induced cracks were straight and extended across the full width of the apparent grains, which indicated that the long-range order was not limited to the near-surface region, but extended through the film thickness...
September 15, 2017: ACS Applied Materials & Interfaces
Germán Prieto, Konstantinos D Bakoglidis, Walter R Tuckart, Esteban Broitman
Cryogenic treatments are increasingly used to improve the wear resistance of various steel alloys by means of transformation of retained austenite, deformation of virgin martensite and carbide refinement. In this work the nanotribological behavior and mechanical properties at the nano-scale of cryogenically and conventionally treated AISI 420 martensitic stainless steel were evaluated. Conventionally treated specimens were subjected to quenching and annealing, while the deep cryogenically treated samples were quenched, soaked in liquid nitrogen for 2 h and annealed...
2017: Beilstein Journal of Nanotechnology
Xingling Tang, Abdelkhalak El-Hami, Khalil El-Hami, Mohamed Eid, Chaorun Si
This paper carries out a preliminary study for the elastic properties of single walled carbon nanotube (SWCNT) thin film. The SWCNT thin films (~250 nm) are prepared by a simple and cost effective method of spin-coating technology. Nanoindentation test with a Berkovich indenter is used to determine the hardness and elastic modulus of the SWCNT thin film. It is important to note that the elastic properties of SWCNT film are indirectly derived from the information of load and displacement of the indenter under certain assumptions, deviation of the 'test value' is inevitable...
September 12, 2017: Scientific Reports
Xiao Wang, Tao Huang, Yapeng Luo, Huixia Liu
The purpose of this paper is to present an advanced method for welding fine wire to metal sheet, namely laser indirect shock welding (LISW). This process uses silica gel as driver sheet to accelerate the metal sheet toward the wire to obtain metallurgical bonding. A series of experiments were implemented to validate the welding ability of Al sheet/Cu wire and Al sheet/Ag wire. It was found that the use of a driver sheet can maintain high surface quality of the metal sheet. With the increase of laser pulse energy, the bonding area of the sheet/wire increased and the welding interfaces were nearly flat...
September 12, 2017: Materials
Rodolfo B Anchieta, Márcia V M Guimarães, Marcelo Suzuki, Nick Tovar, Estevam A Bonfante, Pablo Atria, Paulo G Coelho
PURPOSE: This work evaluated the nanomechanical properties of bone surrounding submerged and immediately loaded implants after 3 years in vivo. It was hypothesized that the nanomechanical properties of bone would markedly increase in immediately and functionally loaded implants compared with submerged implants. MATERIALS AND METHODS: The second, third, and fourth right premolars and the first molar of 10 adult Doberman dogs were extracted. After 6 months, 4 implants were placed in 1 side of the mandible...
August 17, 2017: Journal of Oral and Maxillofacial Surgery
Bret E Dunlap, Timothy J Ruggles, David T Fullwood, Brian Jackson, Martin A Crimp
In this work, the relative capabilities and limitations of electron channeling contrast imaging (ECCI) and cross-correlation electron backscattered diffraction (CC-EBSD) have been assessed by studying the dislocation distributions resulting from nanoindentation in body centered cubic Ta. Qualitative comparison reveals very similar dislocation distributions between the CC-EBSD mapped GNDs and the ECC imaged dislocations. Approximate dislocation densities determined from ECC images compare well to those determined by CC-EBSD...
September 1, 2017: Ultramicroscopy
Peng Huang, Dan Guo, Guoxin Xie, Jian Li
The understanding on the mechanical properties of graphene under the applications of physical fields is highly relevant to the reliability and lifetime of graphene-based nanodevices. In this work, we demonstrate that the application of electric field could soften the mechanical properties of graphene dramatically on the basis of the conductive AFM nanoindentation method. It has been found that the Young's modulus and fracture strength of graphene nanosheets suspended on the holes almost stay the same initially and then exhibit a sharp drop when the normalized electric field strength increases to be 0...
September 11, 2017: Nano Letters
Zhong Li, Gary Hin-Fai Yam, Brianna C Thompson, Melina Setiawan, Gwendoline Tze Wei Goh, Donald Tan, Jodhbir S Mehta, Khiam Aik Khor
The manufacture of mechanically strong and biocompatible titania (TiO2 ) materials is of vital importance for their application as corneal implant skirts. This study was aimed at optimizing the selection of raw powder and sintering conditions for TiO2 ceramics. TiO2 compacts were synthesized from five raw powders, denoted as Altair, Inframat, Alfa, Materion and Amperit, respectively, by spark plasma sintering using different sintering parameters. The XRD and Raman results confirmed that the anatase TiO2 phase in the Inframat powder had converted completely to rutile TiO2 phase after sintering at 900°C and above...
September 4, 2017: Journal of Biomedical Materials Research. Part A
Zdeněk Tolde, Vladimír Starý, Ladislav Cvrček, Marta Vandrovcová, Jan Remsa, Stanislav Daniš, Jan Krčil, Lucie Bačáková, Petr Špatenka
Surface bioactivity has been under intensive study with reference to its use in medical implants. Our study is focused on coatings prepared from an electroactive material which can support bone cell adhesion. Until now, hydroxyapatite films have usually been utilized as a chemically-active surface agent. However, electrically-active films could set a new direction in hard tissue replacement. As a base for these films, it is necessary to prepare an intermediate film, which can serve as a suitable barrier against the possible diffusion of some allergens and toxic elements from the substrate...
November 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Xiaojun Wang, Xiaoan Xia, Xiaogang Zhang, Weijia Meng, Chen Yuan, Meiqing Guo
This study was dedicated to develop a nonenzymatic glucose sensor based on Ag&Pt hollow nanoparticles supported on TiO2 nanotubes. The Ag&Pt-TiO2/(500°C) was synthesized by a simple reduction and galvanic replacement method in an aqueous solution. The surface morphology and structure of Ag&Pt-TiO2/(500°C) could be examined by transmission electron microscopy, scanning electron microscopy and energy dispersive spectrometer. The mechanical behavior was measured by nanoindentation test and the hydropathy property was measured by contact angle test...
November 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Sun Jiapeng, Li Cheng, Jing Han, Aibin Ma, Liang Fang
Silicon has such versatile characteristics that the mechanical behavior and deformation mechanism under contact load are still unclear and hence are interesting and challenging issues. Based on combined study using molecular dynamics simulations and experiments of nanoindentation on Si(100), the versatile deformation modes, including high pressure phase transformation (HPPT), dislocation, median crack and surface crack, were found, and occurrence of multiple pop-in events in the load-indentation strain curves was reported...
August 31, 2017: Scientific Reports
B M Assis, L A F Silva, C R O Lima, F J F Sant'Ana, G P Santos, V A S Vulcani, R E Rabelo
The aim of this study was to describe the microstructure of the pigmented and depigmented hoof capsule of Girolando cattle by bi- and tridimensional microtomography and nanoindentation, analysing the possible relation between these findings and the susceptibility of such animals to podal diseases. To carry out the microtomography and the nanoindentation, duplicated samples were collected from the dorsal wall, abaxial wall and pre-bulbar sole of the hoof capsule. Material collection was performed in 40 medial digits of thoracic limbs and 40 lateral digits of pelvic limbs...
August 31, 2017: Anatomia, Histologia, Embryologia
Zengrong Hu, Feng Chen, Dong Ling, Qiong Nian, Pedram Parandoush, Xing Zhu, Zhuqiang Shao, Gary J Cheng
The exceptional mechanical properties of graphene enable itself as ideal nanofiller to reinforce the metal matrix composites (MMCs). In this work, graphene copper (Gr-Cu) nanocomposites have been fabricated by laser additive manufacturing process. The transmission electron microscope (TEM), X-ray diffraction (XRD), and Raman spectroscopy were utilized to characterize the fabricated nanocomposites. The XRD, Raman spectrum, energy disperse spectroscopy (EDS) and TEM results demonstrate the feasibility of laser additive manufacturing of Gr-Cu nanocomposites...
August 30, 2017: Nanotechnology
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