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Contact force

Qingye Lu, Jun Huang, Omar Maan, Yang Liu, Hongbo Zeng
Surface fouling is the dominant fouling mechanism of thin-film composite (TFC) membranes used in reverse osmosis (RO) technology. Understanding the complex interactions between foulant-membrane which drive the attachment and growth of foulants on membrane surface is of both fundamental and practical importance. This work aims to understand the molecular interaction mechanisms of organic fouling on RO-TFC membranes. A surface forces apparatus (SFA) was employed to directly measure the interaction forces and time-dependent adsorption behaviors between model organic foulants: humic acid (HA), bovine serum albumin (BSA), and lipopolysaccharides (LPS) and a polyamide (PA) thin film...
December 6, 2017: Science of the Total Environment
Feike Hao, Kazuhiko Kondo, Takashi Itoh, Sumiko Ikari, Shigeyuki Nada, Masato Okada, Takeshi Noda
In response to amino acid supply, mTORC1, a master regulator of cell growth, is recruited to the lysosome and activated by a small GTPase, Rheb. However, the intracellular localization of Rheb is controversial. In this study, we showed that a significant portion of Rheb was localized on the Golgi but not on the lysosome. GFP-Rheb could activate mTORC1, even when forced to exclusively localize to the Golgi. Likewise, artificial recruitment of mTORC1 to the Golgi allowed its activation. Accordingly, the Golgi was in contact with the lysosome at the newly described Golgi lysosome contact site (GLCS)...
December 8, 2017: Journal of Cell Science
Shova Neupane, Patricia Losada-Pérez, Sebastien Vivegnis, Zineb Mekhalif, Joseph Delhalle, Asif Bashir, Frank Uwe U Renner
Controlling the molecular organization of organic self-assembled monolayers (SAM) is of utmost importance in nanotechnology, molecular electronics, and surface science. Here we propose two well-differentiated approaches, double printing based on microcontact printing (µ-cp) and molecular back-filling adsorption, to produce complex alkanethiol films. The resulting films on model Au surfaces were characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle measurements...
December 8, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
David G Glass, Niall McAlinden, Owain R Millington, Amanda J Wright
T-cells and antigen presenting cells are an essential part of the adaptive immune response system and how they interact is crucial in how the body effectively fights infection or responds to vaccines. Much of the experimental work studying interaction forces between cells has looked at the average properties of bulk samples of cells or applied microscopy to image the dynamic contact between these cells. In this paper we present a novel optical trapping technique for interrogating the force of this interaction and measuring relative interaction forces at the single-cell level...
2017: PloS One
Fuqiang Chu, Xiaomin Wu, Lingli Wang
Defrosting is essential for removing frost from engineering surfaces, but some fundamental issues are still unclear, especially for defrosting on superhydrophobic surfaces. Here, defrosting experiments on prepared superhydrophobic surfaces were conducted with the meltwater evolution characteristics investigated. According to the experiments, the typical meltwater evolution process on superhydrophobic surfaces can be divided into two stages: dewetting by edge curling and dewetting by shrinkage. The edge curling of a meltwater film is a distinct phenomenon and first reported in this work...
December 8, 2017: ACS Applied Materials & Interfaces
Christian Ganser, Caterina Czibula, Daniel Tscharnuter, Thomas Schöberl, Christian Teichert, Ulrich Hirn
Viscoelastic properties are often measured using probe based techniques such as nanoindentation (NI) and atomic force microscopy (AFM). Rarely, however, are these methods verified. In this article, we present a method that combines contact mechanics with a viscoelastic model (VEM) composed of springs and dashpots. We further show how to use this model to determine viscoelastic properties from creep curves recorded by a probe based technique. We focus on using the standard linear solid model and the generalized Maxwell model of order 2...
December 8, 2017: Soft Matter
Jae-Ik Lee, Soonjae Pyo, Min-Ook Kim, Jongbaeg Kim
We demonstrate a highly sensitive force sensor based on self-adjusting carbon nanotube (CNT) arrays. Aligned CNT arrays are directly synthesized on silicon microstructures by a space-confined growth technique which enables a facile self-adjusting contact. To afford flexibility and softness, the patterned microstructures with the integrated CNTs are embedded in polydimethylsiloxane structures. The sensing mechanism is based on variations in the contact resistance between the facing CNT arrays under the applied force...
December 8, 2017: Nanotechnology
Steffen Rolf-Pissarczyk, Shichao Yan, Luigi Malavolti, Jacob A J Burgess, Gregory McMurtrie, Sebastian Loth
We present the appearance of negative differential resistance (NDR) in spin-dependent electron transport through a few-atom spin chain. A chain of three antiferromagnetically coupled Fe atoms (Fe trimer) was positioned on a Cu_{2}N/Cu(100) surface and contacted with the spin-polarized tip of a scanning tunneling microscope, thus coupling the Fe trimer to one nonmagnetic and one magnetic lead. Pronounced NDR appears at the low bias of 7 mV, where inelastic electron tunneling dynamically locks the atomic spin in a long-lived excited state...
November 24, 2017: Physical Review Letters
Roohollah Hafizi, Jerry Tersoff, Vasili Perebeinos
Capillary and van der Waals forces cause nanotubes to deform or even collapse under metal contacts. Using ab initio band structure calculations, we find that these deformations reduce the band gap by as much as 30%, while fully collapsed nanotubes become metallic. Moreover, degeneracy lifting due to the broken axial symmetry, and wave functions mismatch between the fully collapsed and the round portions of a CNT, lead to a 3 times higher contact resistance. The latter we demonstrate by contact resistance calculations within the tight-binding approach...
November 17, 2017: Physical Review Letters
Randal C Paniello, Sarah Brookes, Neel K Bhatt, Khadijeh Bijangi-Vishehsaraei, Hongji Zhang, Stacey Halum
OBJECTIVE: Muscle progenitor cells (MPCs) can be isolated from muscle samples and grown to a critical mass in culture. They have been shown to survive and integrate when implanted into rat laryngeal muscles. In this study, the ability of MPC implants to enhance adductor function of reinnervated thyroarytenoid muscles was tested in a canine model. STUDY DESIGN: Animal study. METHODS: Sternocleidomastoid muscle samples were harvested from three canines...
December 8, 2017: Laryngoscope
Xing'an Cao, Xuehui Gan, Yitian Peng, Yongxia Wang, Xingzhong Zeng, Haojie Lang, Jinan Deng, Kun Zou
Interfacial friction is of crucial importance to ensure the friction-reducing and anti-wear properties of mechanical microstructures in micro/nanoelectromechanical systems (MEMS/NEMS). An ultra-low frictional interface combining hydrophobic 1H,1H,2H,2H-perfluorodecyltrichlorosilane (FDTS) self-assembled monolayers (SAMs) coated on an AFM tip with mechanically exfoliated molybdenum disulfide (MoS2) nanosheets deposited on a planar Si/SiO2 substrate was achieved. The FDTS SAMs/MoS2 interface between the FDTS SAMs and the MoS2 nanosheets exhibits an ultra-low friction force that is independent of the relative humidity...
December 8, 2017: Nanoscale
Vahid Abbasian, Ehsan A Akhlaghi, Mohammad A Charsooghi, Maasoomeh Bazzar, Ali-Reza Moradi
The aim of this paper is to introduce digital holographic microscopy (DHM) as a non-contact, inexpensive, and non-abrasive method for 3D surface characterization of polymeric nanocomposites. A common-path and vibration-immune Mirau system with a microsphere-assisted arrangement is utilized to increase the lateral resolution of the images. The characterization is performed through the measurement of roughness parameters of the surfaces, which are derived from the recorded holograms. Pure poly(triazole-amide-imide) (PTAI) and PTAI nanocomposite reinforeced with surface modified TiO2 nanoparticles (MN-TiO2) are used and compared...
November 28, 2017: Ultramicroscopy
Veeren M Chauhan, David J Scurr, Thomas Christie, Gary Telford, Jonathan W Aylott, David I Pritchard
Necator americanus, a haematophagous hookworm parasite, infects ~10% of the world's population and is considered to be a significant public health risk. Its lifecycle has distinct stages, permitting its successful transit from the skin via the lungs (L3) to the intestinal tract (L4 maturing to adult). It has been hypothesised that the L3 larval sheath, which is shed during percutaneous infection (exsheathment), diverts the immune system to allow successful infection and reinfection in endemic areas. However, the physicochemical properties of the L3 larval cuticle and sheath, which are in direct contact with the skin and its immune defences, are unknown...
December 2017: PLoS Neglected Tropical Diseases
Tulaya Prachgosin, Wipawan Leelasamran, Pruittikorn Smithmaitrie, Surapong Chatpun
BACKGROUND: Total-contact orthosis (TCO) is one kind of foot orthosis (FO) that is used to adjust biomechanics in flexible flatfoot. OBJECTIVE: To determine the effects of a TCO on the MLA moment, MLA deformation angle and lower limb biomechanics. STUDY DESIGN: Cross-sectional study. METHODS: Seven-flatfoot and thirteen-normal foot subjects were recruited by footprint and radiographs. The biomechanics of subjects with normal foot (NF), flatfoot with shoe only (FWOT) and flatfoot with TCO (FWT) were collected in a 3D motion analysis laboratory and force plates...
December 2017: Prosthetics and Orthotics International
Emin Istif, Antonia Kagkoura, Javier Hernández-Ferrer, Anastasios Stergiou, Theodosis Skaltsas, Raul Arenal, Ana M Benito, Wolfgang K Maser, Nikos Tagmatarchis
The self-assembly of novel core-shell nanoensembles consisting of regioregular poly(3-hexylthiophene) nanoparticles (P3HTNPs) of 100 nm as core and semiconducting CdTe quantum dots (CdTeQDs) as shell with a thickness of a few tens of nanometers was accomplished by employing a re-precipitation approach. The structure, morphology and composition of P3HTNPs/CdTeQDs nanoensembles were confirmed by high-resolution scanning transmission microscopy and dynamic light scattering studies. Intimate interface contact between the CdTeQDs shell and the P3HTNPs core leads to the stabilization of the P3HTNPs/CdTeQDs nanoensemble as probed by steady-state absorption spectroscopy...
December 7, 2017: ACS Applied Materials & Interfaces
C Reichhardt, C J O Reichhardt
Using simulations we examine a two-dimensional disk system in which two disk species are driven in opposite directions. We measure the average velocity of one of the species versus the applied driving force and identify four phases as function of drive and disk density: a jammed state, a completely phase separated state, a continuously mixing phase, and a laning phase. The transitions between these phases are correlated with jumps in the velocity-force curves that are similar to the behavior observed at dynamical phase transitions in driven particle systems with quenched disorder such as vortices in type-II superconductors...
December 7, 2017: Soft Matter
Arati G Kolhatkar, Yi-Ting Chen, Pawilai Chinwangso, Ivan Nekrashevich, Gamage C Dannangoda, Ankit Singh, Andrew C Jamison, Oussama Zenasni, Irene A Rusakova, Karen S Martirosyan, Dmitri Litvinov, Shoujun Xu, Richard C Willson, T Randall Lee
This paper highlights the relation between the shape of iron oxide (Fe3O4) particles and their magnetic sensing ability. We synthesized Fe3O4 nanocubes and nanospheres having tunable sizes via solvothermal and thermal decomposition synthesis reactions, respectively, to obtain samples in which the volumes and body diagonals/diameters were equivalent. Vibrating sample magnetometry (VSM) data showed that the saturation magnetization (Ms) and coercivity of 100-225 nm cubic magnetic nanoparticles (MNPs) were, respectively, 1...
November 30, 2017: ACS Omega
Wouter Johannes van Drunen, Mathias Mueller, Anatoly Glukhovskoy, Rolf Salcher, Marc Christopher Wurz, Thomas Lenarz, Hannes Maier
Introduction: Most implantable hearing aids currently available were developed to compensate the sensorineural hearing loss by driving middle ear structures (e.g., the ossicles). These devices are successfully used in round window (RW) stimulation clinically, although this was initially not the intended use. Here, a novel microactuator, specifically designed for RW stimulation, was tested in human temporal bones to determine actuator performance and applicability. Methods: Stapes footplate response to RW stimulation was determined experimentally in human temporal bones and the obtained sound pressure output level was estimated...
2017: BioMed Research International
Steven J Newman, Bruce C Jayne
A central issue for understanding locomotion of vertebrates is how muscle activity and movements of their segmented axial structures are coordinated, and snakes have a longitudinal uniformity of body segments and diverse locomotor behaviors that are well suited for studying the neural control of rhythmic axial movements. Unlike all other major modes of snake locomotion, rectilinear locomotion does not involve axial bending, and the mechanisms of propulsion and modulating speed are not well understood. We integrated electromyograms and kinematics of boa constrictors to test Lissmann's decades-old hypotheses of activity of the costocutaneous superior (CCS) and inferior (CCI) muscles and the intrinsic cutaneous interscutalis (IS) muscle during rectilinear locomotion...
December 6, 2017: Journal of Experimental Biology
Arnaud Diffo Kaze, Stefan Maas, Pierre-Jean Arnoux, Claude Wolf, Dietrich Pape
BACKGROUND: Results of finite element (FE) analyses can give insight into musculoskeletal diseases if physiological boundary conditions, which include the muscle forces during specific activities of daily life, are considered in the FE modelling. So far, many simplifications of the boundary conditions are currently made. This study presents an approach for FE modelling of the lower limb for which muscle forces were included. METHODS: The stance phase of normal gait was simulated...
December 7, 2017: Biomedical Engineering Online
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