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Palena A Pinto, Guillaume Colas, Tobin Filleter, Grace M De Souza
Yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) is a ceramic material used in indirect dental restorations. However, phase transformation at body temperature may compromise the material's mechanical properties, affecting the clinical performance of the restoration. The effect of mastication on 3Y-TZP aging has not been investigated. 3Y-TZP specimens (IPS E-max ZirCAD and Z5) were aged in three different modes (n=13): no aging (control), hydrothermal aging (HA), or chewing simulation (CS). Mechanical properties and surface topography were analyzed...
October 26, 2016: Microscopy and Microanalysis
Pavel Zelenovskiy, Igor Kornev, Semen Vasilev, Andrei Kholkin
The elastic properties of the nanotubes of self-assembled aromatic dipeptide diphenylalanine are investigated by means of Raman spectroscopy and a mass-in-mass 1D model. Analysis of nanotubes' lattice vibrations reveals the essential contribution of the water in the nanochannel core of the tubes to the Young's modulus and high water mobility along the channel. Direct measurements of the Young's modulus performed by nanoindentation confirm the obtained results.
October 24, 2016: Physical Chemistry Chemical Physics: PCCP
Y F Zhang, D Y Li, J X Yu, H T He
OBJECTIVE: To determine the thickness and nanomechanical properties of salivary pellicle formed on tooth enamel. METHODS: In vitro adsorption experiments were conducted by immersing enamel samples in centrifuged saliva for 1min, and then the nanomechanical properties of the salivary pellicle/tooth enamel system were measured firstly using nanoindentation based on a continuous stiffness measurement technique. Finally, a model was proposed to obtain the thickness and the intrinsic nanohardness of this biofilm...
October 19, 2016: Journal of Dentistry
Sarsvat Patel, Xiang Kou, Hao Helen Hou, Ye Bill Huang, John C Strong, Geoff G Z Zhang, Changquan Calvin Sun
Amorphous solid dispersions (ASDs) consisting of acetaminophen (APAP) and copovidone were systematically studied to identify effects of drug loading and moisture content on mechanical properties, thermal properties, and tableting behavior. ASDs containing APAP at different levels were prepared by film casting and characterized by differential scanning calorimetry and nanoindentation. The glass transition temperature (Tg) continuously decreased with increasing amount of APAP, but the hardness of ASDs was increased at a low APAP content and reduced at high APAP content...
October 18, 2016: Journal of Pharmaceutical Sciences
Mon-Shu Ho, Chih-Pong Huang, Jyun-Hwei Tsai, Che-Fu Chou, Wen-Jay Lee
This paper reports an array-designed C84-embedded Si substrate fabricated using a controlled self-assembly method in an ultra-high vacuum chamber. The characteristics of the C84-embedded Si surface, such as atomic resolution topography, local electronic density of states, band gap energy, field emission properties, nanomechanical stiffness, and surface magnetism, were examined using a variety of surface analysis techniques under ultra, high vacuum (UHV) conditions as well as in an atmospheric system. Experimental results demonstrate the high uniformity of the C84-embedded Si surface fabricated using a controlled self-assembly nanotechnology mechanism, represents an important development in the application of field emission display (FED), optoelectronic device fabrication, MEMS cutting tools, and in efforts to find a suitable replacement for carbide semiconductors...
September 28, 2016: Journal of Visualized Experiments: JoVE
Tao Fu, Xianghe Peng, Xiang Chen, Shayuan Weng, Ning Hu, Qibin Li, Zhongchang Wang
We performed molecular dynamics simulation of nanoindentation on Cu/Ni nanotwinned multilayer films using a spherical indenter, aimed to investigate the effects of hetero-twin interface and twin thickness on hardness. We found that both twinning partial slip (TPS) and partial slip parallel with twin boundary (PSPTB) can reduce hardness and therefore should not be ignored when evaluating mechanical properties at nanoscale. There is a critical range of twin thickness λ (~25 Å < λ < ~31 Å), in which hardness of the multilayer films is maximized...
October 21, 2016: Scientific Reports
Fang Mao, Mamoun Taher, Oleksandr Kryshtal, Adam Kruk, Aleksandra Czyrska-Filemonowicz, Mikael Ottosson, Anna Mikaela Andersson, Urban Wiklund, Ulf Jansson
A combinatorial approach is applied to rapidly deposit and screen Ag-Al thin films to evaluate the mechanical, tribological and electrical properties as a function of chemical composition. Ag-Al thin films with large continuous composition gradients (6-60 at.% Al) were deposited by a custom-designed combinatorial magnetron sputtering system. X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning and transmission electron microscopy (SEM & TEM), X-ray photoelectron spectroscopy (XPS), nanoindentation, and four-point electrical resistance screening were employed to characterize the chemical composition, structure and physical properties of the films in a rapid and time-efficient way...
October 17, 2016: ACS Applied Materials & Interfaces
Zhenyu Zhang, Liangchao Guo, Junfeng Cui, Bo Wang, Renke Kang, Dongming Guo
Nanoscale solely amorphous layer is achieved in silicon (Si) wafers, using a developed diamond wheel with ceria, which is confirmed by high resolution transmission electron microscopy (HRTEM). This is different from previous reports of ultraprecision grinding, nanoindentation and nanoscratch, in which an amorphous layer at the top, followed by a crystalline damaged layer beneath. The thicknesses of amorphous layer are 43 and 48 nm at infeed rates of 8 and 15 μm/min, respectively, which is verified using HRTEM...
October 13, 2016: Scientific Reports
Lauryn L Baranowski, Chelsea M Heveran, Virginia L Ferguson, Conrad R Stoldt
The need for smaller, lighter, and longer lasting rechargeable batteries is projected to increase rapidly in the coming years due to high demand for portable electronics and electric vehicles. While traditional Li-ion batteries use liquid-phase electrolytes, these suffer from safety risks and low energy density. Solid-phase electrolytes can avoid these issues by enabling a Li metal anode, but tend to fail during cycling due to Li metal dendrite growth between the electrodes. Because Li dendrite nucleation and growth can be viewed in terms of the mechanical behavior of the battery components, it is critical to understand the mechanical response of candidate electrolyte materials...
October 10, 2016: ACS Applied Materials & Interfaces
Aniruddha Samanta, Himel Chakraborty, Manjima Bhattacharya, Jiten Ghosh, Monjoy Sreemany, Sandip Bysakh, Ramkrishna Rane, Alphonsa Joseph, Ghanshyam Jhala, Subroto Mukherjee, Mitun Das, Anoop K Mukhopadhyay
AISI 316L is a well known biocompatible, austenitic stainless steel (SS). It is thus a bio-steel. Considering its importance as a bio-prosthesis material here we report the plasma nitriding of AISI 316L (SS) followed by its microstructural and nanotribological characterization. Plasma nitriding of the SS samples was carried out in a plasma reactor with a hot wall vacuum chamber. For ease of comparison these plasma nitrided samples were termed as SSPN. The experimental results confirmed the formations of an embedded nitrided metal layer zone (ENMLZ) and an interface zone (IZ) between the ENMLZ and the unnitrided bulk metallic layer zone (BMLZ) in the SSPN sample...
September 15, 2016: Journal of the Mechanical Behavior of Biomedical Materials
Alberto Garcia, Jose F Rodriguez Matas, Manuela T Raimondi
Recent evidence suggests that mechanical deformation of the cell nucleus regulates the nuclear import of the transcriptional activators of genes involved in primary physiological cell responses such as stem cell differentiation. In addition, this nuclear mechanosensing response is de-regulated in pathological states, such as cancer and neurodegeneration. One hypothesis that could greatly advance the field is that the deformation of the nuclear envelope activates nuclear pore complexes through a direct mechanical link...
October 10, 2016: Integrative Biology: Quantitative Biosciences From Nano to Macro
Zhijun Zhang, Honglei Jia, Jiyu Sun, Jin Tong
ABSTACT With the rapid development of bionic science, especially the progress that has been made in the fields of biomaterials and biomimetics, there is now great interest in the surface and internal mechanical properties of biological materials at the micro- and nanoscale. The study of micro- and nanoscale biomaterial mechanical properties could enable interdisciplinary applications in materials science, biological science and bionic science. Dung beetle (Copris ochus Motschulsky) cuticle is a viscoelastic material that is both viscous and flexible via elastic deformation under external forces; where stress σ, strain ϵ and elastic modulus E are related in the following way: σ = Eϵ...
September 2, 2016: Bioengineered
M Mostafavi, R Bradley, D E J Armstrong, T J Marrow
Nanoindentation of engineering materials is commonly used to study, at small length scales, the continuum mechanical properties of elastic modulus and yield strength. However, it is difficult to measure strain hardening via nanoindentation. Strain hardening, which describes the increase in strength with plastic deformation, affects fracture toughness and ductility, and is an important engineering material property. The problem is that the load-displacement data of a single nanoindentation do not provide a unique solution for the material's plastic properties, which can be described by its stress-strain behaviour...
October 4, 2016: Scientific Reports
Syamantak Roy, Arpan Hazra, Arkamita Bandyopadhyay, Devraj Raut, P Lakshmi Madhuri, D S Shankar Rao, Upadrasta Ramamurty, Swapan Kumar Pati, S Krishna Prasad, Tapas Kumar Maji
We report the design, synthesis, detailed characterization, and analysis of a new multifunctional π-conjugated bola-amphiphilic chromophore: oligo-(p-phenyleneethynylene)dicarboxylic acid with dialkoxyoctadecyl side chains (OPE-C18-1). OPE-C18-1 shows two polymorphs at 123 K (OPE-C18-1') and 373 K (OPE-C18-1″), whose crystal structures were characterized via single crystal X-ray diffraction. OPE-C18-1 also exhibits thermotropic liquid crystalline property revealing a columnar phase. The inherent π-conjugation of OPE-C18-1 imparts luminescence to the system...
October 3, 2016: Journal of Physical Chemistry Letters
Jiyu Sun, Wei Wu, Weiliang Xue, Jin Tong, Xianping Liu
Bovine horns are durable that they can withstand an extreme loading force which with special structures and mechanical properties. In this study, the authors apply quasi-static nanoindentation and modulus mapping techniques to research the nanomechanical properties of bovine horn in the transverse direction (TD) and longitudinal direction (LD). In quasi-static nanoindentation, the horn's modulus and hardness in the inner layer and the outer layer demonstrated a gradual increase in both TD and LD. Laser scanning confocal microscopy revealed microstructure in the horn with wavy morphology in the TD cross-section and laminate in the LD cross-section...
October 2016: IET Nanobiotechnology
Jing Li, Ben-Cang Cui, Yuan-Hua Lin, Xu-Liang Deng, Ming Li, Ce-Wen Nan
OBJECTIVE: To evaluate the microstructure and mechanical behavior of polymer-infiltrated zirconia ceramics as a function of Fe2O3 concentration (0-0.3mol%). METHODS: Polymer-infiltrated zirconia ceramics with different concentrations of Fe2O3 were prepared by infiltration and polymerization. XRD was employed to determine phase structure. The microstructure and fracture mechanism was observed by SEM. Flexural strength and fracture toughness were measured by three-point bending method and single-edge-notched beam method, respectively...
September 23, 2016: Dental Materials: Official Publication of the Academy of Dental Materials
Aaron H Aziz, Joseph Wahlquist, Aaron Sollner, Virginia Ferguson, Frank W DelRio, Stephanie J Bryant
Multi-layer hydrogels are promising for tissue engineering due to the ability to control the local properties within each layer. However, the interface that forms between each layer has the potential to affect the performance of the hydrogel. The goals of this study were to characterize how the interface forms via its thickness and mechanical properties, identify its impact on the overall hydrogel properties, and provide new insights into how to control the interface. A photo-clickable poly(ethylene glycol) hydrogel was used to form bilayer hydrogels that were sequentially polymerized in a step-and-repeat process...
September 8, 2016: Journal of the Mechanical Behavior of Biomedical Materials
Yu Sun, Qiaoqin Yang, Haidong Wang
Multifunctional tissue scaffold material nanodiamond (ND)/chitosan (CS) composites with different diamond concentrations from 1 wt % to 5 wt % were synthesized through a solution casting method. The microstructure and mechanical properties of the composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and nanoindentation. Compared with pristine CS, the addition of ND resulted in a significant improvement of mechanical properties, including a 239%, 276%, 321%, 333%, and 343% increase in Young's modulus and a 68%, 96%, 114%, 118%, and 127% increase in hardness when the ND amount was 1 wt %, 2 wt %, 3 wt %, 4 wt %, and 5 wt %, respectively...
September 15, 2016: Journal of Functional Biomaterials
Zhentao Man, Xiaoqing Hu, Zhenlong Liu, Hongjie Huang, Qingyang Meng, Xin Zhang, Linghui Dai, Jiying Zhang, Xin Fu, Xiaoning Duan, Chunyan Zhou, Yingfang Ao
Cartilage tissue engineering is the hotspot of cartilage repair. The allogenic chondrocytes appear to be a promising source of seed cells in cartilage tissue engineering. In this study, we aimed to transplant allogenic chondrocytes with chitosan hydrogel (CS)-demineralized bone matrix (DBM) hybrid scaffold (CS/DBM) to repair rabbit cartilage injury with one-step operation. After the CS/DBM scaffold was successfully fabricated, it showed that the porous CS filled the large pores of DBM, which improved the distribution of seed cells in the CS/DBM scaffold...
November 2016: Biomaterials
Mohsen Asadnia, Ajay Giri Prakash Kottapalli, K Domenica Karavitaki, Majid Ebrahimi Warkiani, Jianmin Miao, David P Corey, Michael Triantafyllou
We report the development of a new class of miniature all-polymer flow sensors that closely mimic the intricate morphology of the mechanosensory ciliary bundles in biological hair cells. An artificial ciliary bundle is achieved by fabricating bundled polydimethylsiloxane (PDMS) micro-pillars with graded heights and electrospinning polyvinylidenefluoride (PVDF) piezoelectric nanofiber tip links. The piezoelectric nature of a single nanofiber tip link is confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR)...
2016: Scientific Reports
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