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https://www.readbyqxmd.com/read/28523651/microstructure-and-nanomechanical-properties-of-single-stalks-from-diatom-didymosphenia-geminata-and-their-change-due-to-adsorption-of-selected-metal-ions
#1
Izabela Zgłobicka, Adrian Chlanda, Michał Woźniak, Maciej Łojkowski, Robert Szoszkiewicz, Marta Mazurkiewicz-Pawlicka, Wojciech Święszkowski, Elżbieta Wyroba, Krzysztof J Kurzydłowski
We present topographical and nanomechanical characterization of single Didymosphenia geminata stalks. We compared the samples before and after adsorption of metal ions from fresh water samples. Transmission electron microscopy studies of single stalks cross-sections have shown three distinct layers and an additional thin extra coat on the external layer (called here "EL"). Using scanning electron microscopy and atomic force microscopy (AFM) we found that topography of single stalks after ionic adsorption differs significantly from topography of pristine stalks...
May 18, 2017: Journal of Phycology
https://www.readbyqxmd.com/read/28515461/variation-of-nanostructures-molecular-interactions-and-anisotropic-elastic-moduli-of-lignocellulosic-cell-walls-with-moisture
#2
S Youssefian, J E Jakes, N Rahbar
A combination of experimental, theoretical and numerical studies is used to investigate the variation of elastic moduli of lignocellulosic (bamboo) fiber cell walls with moisture content (MC). Our Nanoindentation results show that the longitudinal elastic modulus initially increased to a maximum value at about 3% MC and then decreased linearly with increasing MC. In contrast, the transverse moduli decrease linearly with MC. We showed that amorphous materials in cell walls have key roles in the variation of elastic modulus with increasing MC...
May 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28485089/materials-nanoarchitecturing-via-cation-mediated-protein-assembly-making-limpet-teeth-without-mineral
#3
Tina Ukmar-Godec, Luca Bertinetti, John W C Dunlop, Aljaž Godec, Michal A Grabiger, Admir Masic, Huynh Nguyen, Igor Zlotnikov, Paul Zaslansky, Damien Faivre
Teeth are designed to deliver high forces while withstanding the generated stresses. Aside from isolated mineral-free exception (e.g., marine polychaetes and squids), minerals are thought to be indispensable for tooth-hardening and durability. Here, the unmineralized teeth of the giant keyhole limpet (Megathura crenulata) are shown to attain a stiffness, which is twofold higher than any known organic biogenic structures. In these teeth, protein and chitin fibers establish a stiff compact outer shell enclosing a less compact core...
May 9, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28465613/microstructure-and-nanoindentation-behavior-of-cu-composites-reinforced-with-graphene-nanoplatelets-by-electroless-co-deposition-technique
#4
Qi Zhang, Zhenbo Qin, Qin Luo, Zhong Wu, Lei Liu, Bin Shen, Wenbin Hu
A reduced graphene oxide/copper (RGO/Cu) composite was fabricated by a surfactant free, electroless co-deposition technique. The graphene oxide (GO) sheets were reduced and RGO homogeneous distributed into the copper matrix. On the basis of nanoindentation, the presence of RGO and the increase of its content in matrix significantly raised the hardness of RGO/Cu composites. Here, the relevant strengthening effect and mechanisms involved in RGO-reinforced Cu composites were systematically evaluated. Especially, the addition of RGO in Cu matrix led to the compressive micro-strain, and the resulted distortion of the lattice parameter was calculated based on Cohen's method...
May 2, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28464367/time-dependent-mechanical-response-of-apbx3-a-cs-ch3-nh3-x-i-br-single-crystals
#5
Marcos A Reyes-Martinez, Ahmed L Abdelhady, Makhsud I Saidaminov, Duck Young Chung, Osman M Bakr, Mercouri G Kanatzidis, Wole O Soboyejo, Yueh-Lin Loo
The ease of processing hybrid organic-inorganic perovskite (HOIPs) films, belonging to a material class with composition ABX3 , from solution and at mild temperatures promises their use in deformable technologies, including flexible photovoltaic devices, sensors, and displays. To successfully apply these materials in deformable devices, knowledge of their mechanical response to dynamic strain is necessary. The authors elucidate the time- and rate-dependent mechanical properties of HOIPs and an inorganic perovskite (IP) single crystal by measuring nanoindentation creep and stress relaxation...
May 2, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28462864/the-mechanical-importance-of-myelination-in-the-central-nervous-system
#6
Johannes Weickenmeier, Rijk de Rooij, Silvia Budday, Timothy C Ovaert, Ellen Kuhl
Neurons in the central nervous system are surrounded and cross-linked by myelin, a fatty white substance that wraps around axons to create an electrically insulating layer. The electrical function of myelin is widely recognized; yet, its mechanical importance remains underestimated. Here we combined nanoindentation testing and histological staining to correlate brain stiffness to the degree of myelination in immature, pre-natal brains and mature, post-natal brains. We found that both gray and white matter tissue stiffened significantly (p≪0...
April 19, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28459534/shear-induced-structural-changes-and-origin-of-ultralow-friction-of-hydrogenated-diamond-like-carbon-dlc-in-dry-environment
#7
Praveena Manimunda, Ala' Al-Azizi, Seong H Kim, Richard R Chromik
The origins of run-in and ultralow friction states of a sliding contact of hydrogenated diamond-like carbon (H-DLC) and sapphire were studied with an in situ Raman tribometer as well as ex situ analyses of transmission electron microscopy (TEM), Raman spectroscopy, and nanoindentation. Prior to ultralow friction behavior, H-DLC exhibits a run-in period. During the run-in period in dry nitrogen atmosphere, the transfer film was formed and its uniformity and thickness as well as structure were varied. The duration and friction behaviors during the run-in depended on the initial surface state of the H-DLC coatings...
May 3, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28445999/crystal-orientation-effect-on-the-subsurface-deformation-of-monocrystalline-germanium-in-nanometric-cutting
#8
Min Lai, Xiaodong Zhang, Fengzhou Fang
Molecular dynamics simulations of nanometric cutting on monocrystalline germanium are conducted to investigate the subsurface deformation during and after nanometric cutting. The continuous random network model of amorphous germanium is established by molecular dynamics simulation, and its characteristic parameters are extracted to compare with those of the machined deformed layer. The coordination number distribution and radial distribution function (RDF) show that the machined surface presents the similar amorphous state...
December 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28424904/nanoindentation-response-of-cortical-bone-dependency-of-subsurface-voids
#9
Masoud Ramezanzadehkoldeh, Bjørn Skallerud
Nanoindentation test results in the axial direction of mouse femurs were the basis for the current study. Although the majority of the nanoindentation curves showed a reasonable consistency, some curves showed a significantly softer response. Detailed investigation, using focused ion beam-scanning electron microscopy, provided that the softer response is due to subsurface cavities such as lacunae. Finite element models were developed to simulate the nanoindentation of mice femur cortical bone samples with and without the incorporation of a single lacuna underneath the bone surface...
April 19, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/28415479/natural-polymeric-microspheres-for-modulated-drug-delivery
#10
Costantino Del Gaudio, Valentina Crognale, Gianpaolo Serino, Pierluca Galloni, Alberto Audenino, Domenico Ribatti, Umberto Morbiducci
Microspheres can be regarded as a suitable platform for the development of ad hoc drug delivery systems, since the targeted release of a therapeutic agent can effectively contribute to support and improve a pharmacological protocol. However, several crucial factors related to the selection of materials, drugs and fabrication techniques should be critically analyzed in order to enhance the expected performance. Dealing with highly compatible materials, e.g. naturally-derived polymers and "green" reagents, can be a valid approach...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28415400/antibacterial-and-cytocompatible-nanotextured-ti-surface-incorporating-silver-via-single-step-hydrothermal-processing
#11
Anu Mohandas, Amit G Krishnan, Raja Biswas, Deepthy Menon, Manitha B Nair
Nanosurface modification of Titanium (Ti) implants and prosthesis is proved to enhance osseointegration at the tissue-implant interface. However, many of these products lack adequate antibacterial capability, which leads to implant loosening. As a curative strategy, in this study, nanotextured Ti substrates embedded with silver nanoparticles were developed through a single step hydrothermal processing in an alkaline medium containing silver nitrate at different concentrations (15, 30 and 75μM). Scanning electron micrographs revealed a non-periodically oriented nanoleafy structure on Ti (TNL) decorated with Ag nanoparticles (nanoAg), which was verified by XPS, XRD and EDS analysis...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28410916/chronic-alcohol-abuse-in-men-alters-bone-mechanical-properties-by-affecting-both-tissue-mechanical-properties-and-microarchitectural-parameters
#12
M Cruel, M Granke, C Bosser, M Audran, T Hoc
OBJECTIVE OF THE STUDY: Alcohol-induced secondary osteoporosis in men has been characterized by higher fracture prevalence and a modification of bone microarchitecture. Chronic alcohol consumption impairs bone cell activity and results in an increased fragility. A few studies highlighted effects of heavy alcohol consumption on some microarchitectural parameters of trabecular bone. But to date and to our knowledge, micro- and macro-mechanical properties of bone of alcoholic subjects have not been investigated...
April 11, 2017: Morphologie: Bulletin de L'Association des Anatomistes
https://www.readbyqxmd.com/read/28386450/nanoindentation-analysis-of-the-micromechanical-anisotropy-in-mouse-cortical-bone
#13
Michele Casanova, Anna Balmelli, Davide Carnelli, Diana Courty, Philipp Schneider, Ralph Müller
Studies investigating micromechanical properties in mouse cortical bone often solely focus on the mechanical behaviour along the long axis of the bone. Therefore, data on the anisotropy of mouse cortical bone is scarce. The aim of this study is the first-time evaluation of the anisotropy ratio between the longitudinal and transverse directions of reduced modulus and hardness in mouse femurs by using the nanoindentation technique. For this purpose, nine 22-week-old mice (C57BL/6) were sacrificed and all femurs extracted...
February 2017: Royal Society Open Science
https://www.readbyqxmd.com/read/28384503/manufacturing-and-characterization-of-molybdenum-pellets-used-as-targets-for-99m-tc-production-in-cyclotron
#14
Izabela Cieszykowska, Tomasz Janiak, Tadeusz Barcikowski, Mieczysław Mielcarski, Renata Mikołajczak, Jarosław Choiński, Marek Barlak, Łukasz Kurpaska
The method of (100)Mo metallic target preparation for production of (99m)Tc by proton irradiation in (100)Mo(p,2n)(99m)Tc reaction was demonstrated. For this purpose, pressing of molybdenum powder into pellets and their subsequent sintering in reductive atmosphere were applied. The influence of parameters such as molybdenum mass and time of both pressing and sintering on the (100)Mo target durability was investigated. Under the optimized conditions, (100)Mo metallic pellet targets with density of 9.95±0.06g/cm(3) were obtained...
March 10, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28381566/the-vertex-specific-proteins-pul17-and-pul25-mechanically-reinforce-herpes-simplex-virus-capsids
#15
Joost Snijder, Kerstin Radtke, Fenja Anderson, Luella Scholtes, Eleonora Corradini, Joel Baines, Albert J R Heck, Gijs J L Wuite, Beate Sodeik, Wouter H Roos
Using atomic force microscopy imaging and nanoindentation measurements, we investigated the effect of the minor capsid proteins pUL17 and pUL25 on the structural stability of the icosahedral Herpes Simplex Virus capsids. pUL17 and pUL25 that form the capsid vertex-specific component (CVSC) particularly contributed to the capsid resilience along the 5-fold and 2-fold, but not along the 3-fold icosahedral axes. Our detailed analyses, including quantitative mass spectrometry on the protein composition of the capsids, revealed that pUL17 and pUL25 are both required to stabilize the capsid shells at the vertices...
April 5, 2017: Journal of Virology
https://www.readbyqxmd.com/read/28378770/unraveling-the-role-of-calcium-ions-in-the-mechanical-properties-of-individual-collagen-fibrils
#16
Xiangchao Pang, Lijun Lin, Bin Tang
Collagen, the dominating material in the extracellular matrix, provides the strength, elasticity and mechanical stability to the organisms. The mechanical property of collagen is mainly dominated by its surrounding environments. However, the variation and origin of the mechanics of collagen fibril under different concentrations of calcium ions (χCa) remains unknown. By using the atomic force microscopy based nanoindentation, the mechanics and structure of individual type II collagen fibril were first investigated under different χCa in this study...
April 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28378291/vibrational-spectroscopic-techniques-to-assess-bone-quality
#17
REVIEW
E P Paschalis, S Gamsjaeger, K Klaushofer
Although musculoskeletal diseases such as osteoporosis are diagnosed and treatment outcome is evaluated based mainly on routine clinical outcomes of bone mineral density (BMD) by DXA and biochemical markers, it is recognized that these two indicators, as valuable as they have proven to be in the everyday clinical practice, do not fully account for manifested bone strength. Thus, the term bone quality was introduced, to complement considerations based on bone turnover rates and BMD. Bone quality is an "umbrella" term that incorporates the structural and material/compositional characteristics of bone tissue...
April 5, 2017: Osteoporosis International
https://www.readbyqxmd.com/read/28376622/mechanical-loading-influences-the-viscoelastic-performance-of-the-resin-carious-dentin-complex
#18
Manuel Toledano, Raquel Osorio, Modesto T López-López, Fátima S Aguilera, Franklin García-Godoy, Manuel Toledano-Osorio, Estrella Osorio
The aim of this study was to evaluate the changes in the mechanical behavior and bonding capability of Zn-doped resin-infiltrated caries-affected dentin interfaces. Dentin surfaces were treated with 37% phosphoric acid (PA) followed by application of a dentin adhesive, single bond (SB) (PA+SB) or by 0.5 M ethylenediaminetetraacetic acid (EDTA) followed by SB (EDTA+SB). ZnO microparticles of 10 wt. % or 2 wt. % ZnCl2 was added into SB, resulting in the following groups: PA+SB, PA+SB-ZnO, PA+SB-ZnCl2, EDTA+SB, EDTA+SB-ZnO, EDTA+SB-ZnCl2...
April 4, 2017: Biointerphases
https://www.readbyqxmd.com/read/28374551/the-impact-of-hyperglycemia-on-adhesion-between-endothelial-and-cancer-cells-revealed-by-single-cell-force-spectroscopy
#19
Katarzyna E Malek-Zietek, Marta Targosz-Korecka, Marek Szymonski
The impact of hyperglycemia on adhesion between lung carcinoma cells (A549) and pulmonary human aorta endothelial cells (PHAEC) was studied using the single-cell force spectroscopy. Cancer cells were immobilized on a tipless Atomic Force Microscopy (AFM) cantilever and a single layer of endothelial cells was prepared on a glass slide. The measured force-distance curves provided information about the detachment force and about the frequency of specific ligand-receptor rupture events. Measurements were performed for different times of short term (up to 2 h) and prolonged hyperglycemia (3 h - 24 h)...
April 4, 2017: Journal of Molecular Recognition: JMR
https://www.readbyqxmd.com/read/28372387/note-nanomechanical-characterization-of-soft-materials-using-a-micro-machined-nanoforce-transducer-with-an-fib-made-pyramidal-tip
#20
Z Li, S Gao, U Brand, K Hiller, N Wollschläger, F Pohlenz
The quantitative nanomechanical characterization of soft materials using the nanoindentation tech-nique requires further improvements in the performances of instruments, including their force resolution in particular. A micro-machined silicon nanoforce transducer based upon electrostatic comb drives featuring the force and depth resolutions down to ∼1 nN and 0.2 nm, respectively, is described. At the end of the MEMS transducer's main shaft, a pyramidal tip is fabricated using a focused ion beam facility. A proof-of-principle setup with this MEMS nanoindenter has been established to measure the mechanical properties of soft polydimethylsiloxane...
March 2017: Review of Scientific Instruments
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