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Mechanical force

Ryo Suzuki, Kohta Ito, Taeyong Lee, Naomichi Ogihara
Accurate identification of the material properties of the plantar soft tissue is important for computer-aided analysis of foot pathologies and design of therapeutic footwear interventions based on subject-specific models of the foot. However, parameter identification of the hyperelastic material properties of plantar soft tissues usually requires an inverse finite element analysis due to the lack of a practical contact model of the indentation test. In the present study, we derive an analytical contact model of a spherical indentation test in order to directly estimate the material properties of the plantar soft tissue...
September 22, 2016: Journal of the Mechanical Behavior of Biomedical Materials
Mario Encinar, Santiago Casado, Alicia Calzado-Martín, P Natale, Álvaro San Paulo, Montserrat Calleja, Marisela Vélez, Francisco Monroy, Iván López-Montero
Erythrocyte membranes have been particularly useful as a model for studies of membrane structure and mechanics. Native erythroid membranes can be electroformed as giant unilamellar vesicles (eGUVs). In the presence of ATP, the erythroid membrane proteins of eGUVs rearrange into protein networks at the microscale. Here, we present a detailed nanomechanical study of individual protein microfilaments forming the protein networks of eGUVs when spread on supporting surfaces. Using Peak Force tapping Atomic Force Microscopy (PF-AFM) in liquid environment we have obtained the mechanical maps of the composite lipid-protein networks supported on solid surface...
October 13, 2016: Colloids and Surfaces. B, Biointerfaces
Zhizhao Che, Panagiotis E Theodorakis
Surface nanobubbles are stable gaseous phases in liquids that form on solid substrates. While their existence has been confirmed, there are many open questions related to their formation and dissolution processes along with their structures and properties, which are difficult to investigate experimentally. To address these issues, we carried out molecular dynamics simulations based on atomistic force fields for systems comprised of water, air (N2 and O2), and a Highly Oriented Pyrolytic Graphite (HOPG) substrate...
October 14, 2016: Journal of Colloid and Interface Science
Qiao-Li Lv, Yuan-Tao Huang, Gui-Hua Wang, Yan-Ling Liu, Jin Huang, Qiang Qu, Bao Sun, Lei Hu, Lin Cheng, Shu-Hui Chen, Hong-Hao Zhou
Emerging studies show that dysregulation of the receptor of activated protein kinase C1 (RACK1) plays a crucial role in tumorigenesis and progression of various cancers. However, the biological function and underlying mechanism of RACK1 in glioma remains poorly defined. Here, we found that RACK1 was significantly up-regulated in glioma tissues compared with normal brain tissues, being closely related to clinical stage of glioma both in mRNA and protein levels. Moreover, Kaplan-Meier analysis demonstrated that patients with high RACK1 expression had a poor prognosis (p = 0...
October 18, 2016: International Journal of Environmental Research and Public Health
Yingwang Gao, Jinfeng Geng, Xiuqin Rao, Yibin Ying
Skinning injury on potato tubers is a kind of superficial wound that is generally inflicted by mechanical forces during harvest and postharvest handling operations. Though skinning injury is pervasive and obstructive, its detection is very limited. This study attempted to identify injured skin using two CCD (Charge Coupled Device) sensor-based machine vision technologies, i.e., visible imaging and biospeckle imaging. The identification of skinning injury was realized via exploiting features extracted from varied ROIs (Region of Interests)...
October 18, 2016: Sensors
Yonggang Jiang, Jian Li, Zhiwen Zhou, Xinggang Jiang, Deyuan Zhang
Single-crystal silicon carbide (SiC)-based pressure sensors can be used in harsh environments, as they exhibit stable mechanical and electrical properties at elevated temperatures. A fiber-optic pressure sensor with an all-SiC sensor head was fabricated and is herein proposed. SiC sensor diaphragms were fabricated via an ultrasonic vibration mill-grinding (UVMG) method, which resulted in a small grinding force and low surface roughness. The sensor head was formed by hermetically bonding two layers of SiC using a nickel diffusion bonding method...
October 17, 2016: Sensors
Sylwia Szotek, Joanna Dawidowicz, Brian Eyden, Natalia Matysiak, Aleksander Czogalla, Grzegorz Dudzik, Anna Leśniewicz, Krzysztof Maksymowicz
Fascia lata is an important element of the fascial system, which forms the continuum of connective tissue throughout the body. This deep fascia envelops the entire thigh and hip area and its main function is to transmit mechanical forces generated by the musculoskeletal system of the lower extremities. Fascia lata is also known as a useful and easily harvested graft material. Despite its crucial role in lower extremity biomechanics and wide-ranging applications in plastic and reconstructive surgery, both the structure of fascia lata and particularly the cells populating this tissue are relatively unexplored and therefore poorly understood...
October 20, 2016: Ultrastructural Pathology
Yunus Dogramaci, Ibrahim Gökhan Duman
BACKGROUND: Human amniotic membrane is used to prevent peritendinous adhesions after tendon injuries. This study compares the mechanical properties of modified Kessler repairs and modified Kessler repairs strengthened using multiple layers of human amniotic membrane. METHODS: Twenty flexor digitorum profundus tendons of sheep forelimbs were sutured by the two-strand modified Kessler technique (group A) and by the two-strand modified Kessler repair reinforced with multiple layers of human amniotic membrane (group B)...
September 2, 2016: Journal of the American Podiatric Medical Association
Colin Crist
Skeletal muscle is the most abundant tissue in our body, is responsible for generating the force required for movement and is also an important thermogenic organ. Skeletal muscle is an enigmatic tissue because, while on one hand, skeletal muscle regeneration after injury is arguably one of the best studied stem cell dependent regenerative processes, on the other hand, skeletal muscle is still subject to many degenerative disorders with few therapeutic options in the clinic. It is important to develop new regenerative medicine based therapies for skeletal muscle...
October 20, 2016: Journal of Pathology
Nirod Kumar Sarangi, K G Ayappa, Sandhya S Visweswariah, Jaydeep Kumar Basu
Cell membranes are believed to be highly complex dynamical systems having compositional heterogeneity involving several types of lipids and proteins as the major constituents. This dynamical and compositional heterogeneity is suggested to be critical to the maintenance of active functionality and response to chemical, mechanical, electrical and thermal stresses. However, delineating the various factors responsible for the spatio-temporal response of actual cell membranes to stresses can be quite challenging...
October 20, 2016: Physical Chemistry Chemical Physics: PCCP
P H Kim, B D Hauer, C Doolin, F Souris, J P Davis
Reducing the moment of inertia improves the sensitivity of a mechanically based torque sensor, the parallel of reducing the mass of a force sensor, yet the correspondingly small displacements can be difficult to measure. To resolve this, we incorporate cavity optomechanics, which involves co-localizing an optical and mechanical resonance. With the resulting enhanced readout, cavity-optomechanical torque sensors are now limited only by thermal noise. Further progress requires thermalizing such sensors to low temperatures, where sensitivity limitations are instead imposed by quantum noise...
October 20, 2016: Nature Communications
Meizhen Yin, Baozhong Lü, Shusen You, Pengyu Li, Chen Li, Klaus Müllen
Supramolecular self-assembly has attracted increasing attention as a breakthrough methodology in the fields of nanoscience and nanotechnology. In this study, a perylene dianhydride derivative (TP-PDA) self-assembles into well-defined nanospheres through a nucleation-growth process. The mechanisms of this process are explored by spectral ananlysis, dynamic light scattering (DLS) and scanning electron microscopy (SEM). Both in-situ DLS and in-situ SEM reveal that the sizes of aggregated nanospheres increase with time until the formation of equilibrium H-aggregates...
October 20, 2016: Chemistry: a European Journal
Mariya Ptashnyk, Brian Seguin
The microscopic structure and anisotropy of plant cell walls greatly influence the mechanical properties, morphogenesis, and growth of plant cells and tissues. The microscopic structure and properties of cell walls are determined by the orientation and mechanical properties of the cellulose microfibrils and the mechanical properties of the cell wall matrix. Viewing the shape of a plant cell as a square prism with the axis aligning with the primary direction of expansion and growth, the orientation of the microfibrils within the side walls, i...
October 19, 2016: Bulletin of Mathematical Biology
Qingqi Yan, Yumei Wang, Wawat Rodiahwati, Antje Spiess, Michael Modigell
Screw press processing of biomass can be considered as a suitable mechanically based pretreatment for biofuel production since it disrupts the structure of lignocellulosic biomass with high shear and pressure forces. The combination with chemical treatment has been suggested to increase the conversion of lignocellulosic biomass to fermentable sugars. Within the study, the synergetic effect of alkaline (sodium hydroxide, NaOH) soaking and screw press pretreatment on wheat straw was evaluated based on, e.g., sugar recovery and energy efficiency...
October 19, 2016: Bioprocess and Biosystems Engineering
Angelyn V Nguyen, Kendra D Nyberg, Michael B Scott, Alia M Welsh, Andrew H Nguyen, Nanping Wu, Sophia V Hohlbauch, Nicholas A Geisse, Ewan A Gibb, A Gordon Robertson, Timothy R Donahue, Amy C Rowat
Metastasis is a fundamentally physical process in which cells are required to deform through narrow gaps as they invade surrounding tissues and transit to distant sites. In many cancers, more invasive cells are more deformable than less invasive cells, but the extent to which mechanical phenotype, or mechanotype, can predict disease aggressiveness in pancreatic ductal adenocarcinoma (PDAC) remains unclear. Here we investigate the invasive potential and mechanical properties of immortalized PDAC cell lines derived from primary tumors and a secondary metastatic site, as well as noncancerous pancreatic ductal cells...
October 20, 2016: Integrative Biology: Quantitative Biosciences From Nano to Macro
Sayantan Maji, Pankaj Chaudhary, Irina Akopova, Phung M Nguyen, Richard J Hare, Ignacy Gryczynski, Jamboor K Vishwanatha
: Tumor-derived exosomes are emerging mediators of tumorigenesis and tissue-specific metastasis. Proteomic profiling has identified Annexin A2 as one of the most highly expressed proteins in exosomes; however, studies focused on the biological role of exosomal-AnnexinA2 (exo-AnxA2) are still lacking. In this study, mechanistic insight was sought regarding exo-AnxA2 and its function in angiogenesis and breast cancer metastasis. Multiple in vitro and in vivo techniques were used to study the role of exo-AnxA2 in angiogenesis...
October 19, 2016: Molecular Cancer Research: MCR
Nir Kampf, Chunxian Wu, Yilin Wang, Jacob Klein
The surface structure of the trimeric surfactant tri(dodecyldimethylammonioacetoxy)-diethyltriamine trichloride (DTAD) on mica, and the interactions between two such DTAD-coated surfaces were determined using atomic force microscopy and a surface force balance. In an aqueous solution of 3 mM, five times the critical aggregation concentration (CAC), the surfaces are coated with worm-like micelles or hemi-micelles and larger (ca. 80 nm) bilayer vesicles. Repulsive normal interactions between the surfaces indicate a net surface charge and a solution concentration of ions close to that expected from the CAC...
October 19, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Chunfeng Chen, Jie Chen, Tianyu Wang, Minghua Liu
Four kinds of commercially available diacetylene (DA) monomers with different chain length, diacetylene positions were fabricated into the organogels via mixing with a chaperone gelator, an amphiphilic L-histidine ester derivative LHC18 that can help the non-gelator to form gels. Upon photo irradiation with a 254 UV light, the white gels underwent topochemical reaction and turned into red or blue gels, depending on the DA monomer structures. Through the gel formation, the molecular chirality of LHC18 can be transferred to the polydiacetylene (PDA) and helical nanoribbon structures were obtained...
October 19, 2016: ACS Applied Materials & Interfaces
Yunzhu Meng, Wansoo Pak, Berkan Guleyupoglu, Bharath Koya, F Scott Gayzik, Costin D Untaroiu
Child pedestrian protection deserves more attention in vehicle safety design since they are the most vulnerable road users who face the highest mortality rate. Pediatric Finite Element (FE) models could be used to simulate and understand the pedestrian injury mechanisms during crashes in order to mitigate them. Thus, the objective of the study was to develop a computationally efficient (simplified) six-year-old (6YO-PS) pedestrian FE model and validate it based on the latest published pediatric data. The 6YO-PS FE model was developed by morphing the existing GHBMC adult pedestrian model...
October 16, 2016: Accident; Analysis and Prevention
Lorenzo Teodonio, Mauro Missori, Dominika Pawcenis, Joanna Łojewska, Francesco Valle
Mapping the morphological and nano-mechanical properties of cellulose fibers within paper sheets or textile products at the nano-scale level by using atomic force microscopy is a challenging task due to the huge surface level variation of these materials. However this task is fundamental for applications in forensic or cultural heritage sciences and for the industrial characterization of materials. In order to correlate between nano-mechanical properties and local nanometer scale morphology of different layers of cellulose fibers, a new strategy to prepare samples of isolated cellulose fibers was designed...
October 5, 2016: Micron: the International Research and Review Journal for Microscopy
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