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Chee Meng Benjamin Ho, Abhinay Mishra, Pearlyn Teo Pei Lin, Sum Huan Ng, Wai Yee Yeong, Young-Jin Kim, Yong-Jin Yoon
Fabrication of tissue engineering scaffolds with the use of novel 3D printing has gained lot of attention, however systematic investigation of biomaterials for 3D printing have not been widely explored. In this report, well-defined structures of polycaprolactone (PCL) and PCL- carbon nanotube (PCL-CNT) composite scaffolds have been designed and fabricated using a 3D printer. Conditions for 3D printing has been optimized while the effects of varying CNT percentages with PCL matrix on the thermal, mechanical and biological properties of the printed scaffolds are studied...
November 28, 2016: Macromolecular Bioscience
Masoud Sarraf, Bushroa Abdul Razak, Bahman Nasiri-Tabrizi, Ali Dabbagh, Noor Hayaty Abu Kasim, Wan Jefrey Basirun, Eshamsul Bin Sulaiman
Tantalum pentoxide nanotubes (Ta2O5 NTs) can dramatically raise the biological functions of different kinds of cells, thus have promising applications in biomedical fields. In this study, Ta2O5 NTs were prepared on biomedical grade Ti-6Al-4V alloy (Ti64) via physical vapor deposition (PVD) and a successive two-step anodization in H2SO4: HF (99:1)+5% EG electrolyte at a constant potential of 15V. To improve the adhesion of nanotubular array coating on Ti64, heat treatment was carried out at 450°C for 1h under atmospheric pressure with a heating/cooling rate of 1°Cmin(-)(1)...
November 16, 2016: Journal of the Mechanical Behavior of Biomedical Materials
Hao Tang, Ying Li, Jianwei Ma, Xianlin Zhang, Baoe Li, Shimin Liu, Fangfei Dai, Xiangqian Zhang
A homogeneous and uniform array of nanotubes with a diameter of about 70 nm was produced on titanium (Ti) surface by anodic oxidation. The wall thickness of the nanotubes was around 20 nm, and the depth was about 200 nm. The biological properties of the anodized Ti surface were investigated by simulated body fluid (SBF) soaking test and in vitro cell culture test. The mechanical properties were evaluated by instrumented nanoindentation test and friction-wear test. The results showed that the anodized Ti surface can induce the formation of bone-like apatite after immersion in SBF for four weeks, enhance cell adhesion, proliferation and gene expression, it also showed decreased friction coefficient, similar stiffness and Young's modulus to those of the cortical bone...
November 25, 2016: Bio-medical Materials and Engineering
M D Peng, J Q Wei, Y N Wang, Q Li
The aim of the present study was to investigate the effects of low-temperature aging on the micro-mechanical and micro-structural properties of zirconia-porcelain interface. In total, thirty-three Y-TZP zirconia blocks were fabricated by using CAD/CAM technology, veneered with porcelains. Specimens were submitted to low-temperature aging in an autoclave at 134°C, additional 0.2MPa pressure for 0h, 5h, or 10h. Flexural strength was obtained by using three-point bending test. Micro-mechanical properties (nano-hardness (H) and reduced modulus (Er)) were investigated by nanoindentation tests...
November 11, 2016: Journal of the Mechanical Behavior of Biomedical Materials
Qiang Liu, Xiaoqing Hu, Xin Zhang, Xiaoning Duan, Peng Yang, Fengyuan Zhao, Yingfang Ao
Mechanical factors play a key role in regulating the development of cartilage degradation in osteoarthritis. This study aimed to identify the influence of mechanical stress in cartilage and chondrocytes. To explore the effects of mechanical stress on cartilage morphology, we observed cartilages in different regions by histological and microscopic examination. Nanoindentation was performed to assess cartilage biomechanics. To investigate the effects of mechanical stress on chondrocytes, cyclic tensile strain (CTS, 0...
November 17, 2016: Scientific Reports
Arjun Dey, Manish Kumar Nayak, A Carmel Mary Esther, Maurya Sandeep Pradeepkumar, Deeksha Porwal, A K Gupta, Parthasarathi Bera, Harish C Barshilia, Anoop Kumar Mukhopadhyay, Ajoy Kumar Pandey, Kallol Khan, Manjima Bhattacharya, D Raghavendra Kumar, N Sridhara, Anand Kumar Sharma
Vanadium oxide-molybdenum oxide (VO-MO) thin (21-475 nm) films were grown on quartz and silicon substrates by pulsed RF magnetron sputtering technique by altering the RF power from 100 to 600 W. Crystalline VO-MO thin films showed the mixed phases of vanadium oxides e.g., V2O5, V2O3 and VO2 along with MoO3. Reversible or smart transition was found to occur just above the room temperature i.e., at ~45-50 °C. The VO-MO films deposited on quartz showed a gradual decrease in transmittance with increase in film thickness...
November 17, 2016: Scientific Reports
Shun Kondo, Tasuku Mitsuma, Naoya Shibata, Yuichi Ikuhara
In deformation processes, the presence of grain boundaries has a crucial influence on dislocation behavior; these boundaries drastically change the mechanical properties of polycrystalline materials. It has been considered that grain boundaries act as effective barriers for dislocation glide, but the origin of this barrier-like behavior has been a matter of conjecture for many years. We directly observe how the motion of individual dislocations is impeded at well-defined high-angle and low-angle grain boundaries in SrTiO3, via in situ nanoindentation experiments inside a transmission electron microscope...
November 2016: Science Advances
Zechuan Yu, Ao Zhou, Denvid Lau
At 100-nanometer length scale, the mesoscopic structure of calcium silicate hydrate (C-S-H) plays a critical role in determining the macroscopic material properties, such as porosity. In order to explore the mesoscopic structure of C-S-H, we employ two effective techniques, nanoindentation test and molecular dynamics simulation. Grid nanoindentation tests find different porosity of C-S-H in cement paste specimens prepared at varied water-to-cement (w/c) ratios. The w/c-ratio-induced porosity difference can be ascribed to the aspect ratio (diameter-to-thickness ratio) of disk-like C-S-H building blocks...
November 15, 2016: Scientific Reports
Daan Vorselen, Ernst S Kooreman, Gijs J L Wuite, Wouter H Roos
Tip size in atomic force microscopy (AFM) has a major impact on the resolution of images and on the results of nanoindentation experiments. Tip wear is therefore a key limitation in the application of AFM. Here we show, however, how wear can be turned into an advantage as it allows for directed tip shaping. We studied tip wear on high roughness polycrystalline titanium and diamond surfaces and show that tip wear on these surfaces leads to an increased tip size with a rounded shape of the apex. Next, we fitted single peaks from AFM images in order to track the changes in tip radius over time...
November 11, 2016: Scientific Reports
Kang-Han Kim, Yong-Cheol Jeong
We present the light-controlled hierarchical mechanical properties of optically patterned azobenzene thin films through a nanoindentation study. In this study, we inscribed holographic surface relief grating (SRG) of azopolymers by two-beam coupling-based light interference lithography. The resultant morphological profile of azopolymers was monitored by atomic force microscope (AFM), followed by the nanoindentation study. From the load-displacement curve of the indentation procedure, photomechanical changes of the azopolymers along grating patterns were evaluated in terms of hardness and modulus at the crest and trough of the SRG, respectively...
October 31, 2016: Optics Express
Balila Nagamani Jaya, Jeffrey Martin Wheeler, Juri Wehrs, James P Best, Rafael Soler, Johann Michler, Christoph Kirchlechner, Gerhard Dehm
The micro-mechanical fracture behavior of single crystalline silicon was investigated as a function of temperature in situ in the scanning electron microscope equipped with a nanoindenter. A gradual but continuous increase in KC was observed with increasing temperature above 300 °C, in contrast to the sharp transitions observed in earlier works. No sharp brittle to ductile transition temperature (BDTT) could be identified, but a clear change in cracking mechanism occurs at ~300 °C with multiple load drops accompanying the deformation...
November 2, 2016: Nano Letters
Marcel Stenvang, Morten S Dueholm, Brian S Vad, Thomas W Seviour, Guanghong Zeng, Susana Geifman-Shochat, Mads T Søndergaard, Gunna Christiansen, Rikke Louise Meyer, Staffan Kjelleberg, Per Halkjær Nielsen, Daniel E Otzen
Epigallocatechin-3-gallate (EGCG) is the major polyphenol in green tea. It has anti-microbial properties and disrupts the ordered structure of amyloid fibrils involved in human disease. The anti-microbial effect of EGCG against the opportunistic pathogen Pseudomonas aeruginosa has been shown to involve disruption of quorum sensing (QS). Functional amyloid fibrils in P. aeruginosa (Fap) are able to bind and retain quorum sensing molecules, suggesting that EGCG interferes with QS through structural remodeling of amyloid fibrils...
October 26, 2016: Journal of Biological Chemistry
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
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