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intrinsic properties

Pablo Vargas, Lucie Barbier, Pablo José Sáez, Matthieu Piel
Cell migration depends on a combination of the cell's intrinsic capacity to move and the proper interpretation of external cues. This multistep process enables leukocytes to travel long distances in organs in just a few hours. This fast migration is partly due to the leukocytes' high level of plasticity, which helps them to adapt to a changing environment. Here, we review recent progress in understanding the mechanisms used by leukocytes to move rapidly and efficiently in intricate anatomical landscapes. We shall focus on specific cytoskeletal rearrangements used by neutrophils and dendritic cells to migrate within confined environments...
June 19, 2017: Current Opinion in Cell Biology
Marsida Kallupi, Qianwei Shen, Giordano de Guglielmo, Dennis Yasuda, V Blair Journigan, Nurulain T Zaveri, Roberto Ciccocioppo
Buprenorphine's clinical use is approved for the treatment of heroin addiction; however, evidence supporting its efficacy in cocaine abuse also exists. While for heroin it has been demonstrated that the effect of buprenorphine is mediated by its ability to activate μ-opioid peptide receptor (MOP) receptors, the mechanism through which it attenuates cocaine intake remains elusive. We explored this mechanism using operant models where rodents were trained to chronically self-administer cocaine for 2 hours daily...
June 21, 2017: Addiction Biology
Maria Schwarzl, Aljaž Godec, Ralf Metzler
Anomalous diffusion is being discovered in a fast growing number of systems. The exact nature of this anomalous diffusion provides important information on the physical laws governing the studied system. One of the central properties analysed for finite particle motion time series is the intrinsic variability of the apparent diffusivity, typically quantified by the ergodicity breaking parameter EB. Here we demonstrate that frequently EB is insufficient to provide a meaningful measure for the observed variability of the data...
June 20, 2017: Scientific Reports
Stefan Sawall, Joscha Maier, Carsten Leinweber, David Prox, Carsten Funck, Jan Kuntz, Marc Kachelriess
The detection of spherical markers in x-ray projections is an important task in a variety of applications, e.g. geometric calibration and detector distortion correction. Therein, the projection of the sphere center on the detector is of particular interest as the used spherical beads are no ideal point-like objects. Only few methods have been proposed to estimate this respective position on the detector with sufficient accuracy and surrogate positions, e.g. the center of gravity, are used, impairing the results of subsequent algorithms...
June 20, 2017: Physics in Medicine and Biology
Mariana Laranjeira, Rui M A Domingues, Raquel Costa-Almeida, Rui L Reis, Manuela E Gomes
Tendon and ligament (T/L) function is intrinsically related with their unique hierarchically and anisotropically organized extracellular matrix. Their natural healing capacity is, however, limited. Here, continuous and aligned electrospun nanofiber threads (CANT) based on synthetic/natural polymer blends mechanically reinforced with cellulose nanocrystals are produced to replicate the nanoscale collagen fibrils grouped into microscale collagen fibers that compose the native T/L. CANT are then incrementally assembled into 3D hierarchical scaffolds, resulting in woven constructions, which simultaneously mimic T/L nano-to-macro architecture, nanotopography, and nonlinear biomechanical behavior...
June 20, 2017: Small
Son Tran, Jiawei Yang, Nathaniel Gillgren, Timothy Espiritu, Yanmeng Shi, Kenji Watanabe, Takashi Taniguchi, Seongphill Moon, Hongwoo Baek, Dmitry Smirnov, Marc Bockrath, Ruoyu Chen, Chun Ning Lau
Quantum wells (QWs) constitute one of the most important classes of devices in the study of two-dimensional (2D) systems. In a double-layer QW, the additional "which-layer" degree of freedom gives rise to celebrated phenomena, such as Coulomb drag, Hall drag, and exciton condensation. We demonstrate facile formation of wide QWs in few-layer black phosphorus devices that host double layers of charge carriers. In contrast to traditional QWs, each 2D layer is ambipolar and can be tuned into n-doped, p-doped, or intrinsic regimes...
June 2017: Science Advances
Christian W Johnson, Derion Reid, Jillian A Parker, Shores Salter, Ryan Knihtila, Petr Kuzmic, Carla Mattos
H-, K-, and N-Ras are small GTPases that are important in the control of cell proliferation, differentiation and survival, and their mutants occur frequently in human cancers. The G-domain, which catalyzes GTP hydrolysis and mediates downstream signaling, is 95% conserved between the Ras isoforms. Due to their very high sequence identity, biochemical studies done on H-Ras have been considered representative of all three Ras proteins. We show here that this is not a valid assumption. Using enzyme kinetic assays under identical conditions, we observed clear differences between the three isoforms in intrinsic catalysis of GTP by Ras in the absence and presence of the Ras-binding domain (RBD) of the C-Raf Kinase protein (Raf-RBD)...
June 19, 2017: Journal of Biological Chemistry
Meddy El Alaoui, Laurent Soulère, Alexandre Noiriel, Yves Queneau, Abdelkarim Abousalham
Lipases are essentially described as sn-1 and sn-3 regio-selective. Actually few methods are available to measure this lipase regio-selectivity, moreover they require chiral chromatography analysis or specific derivations which are discontinuous and time consuming. In this study we describe a new, convenient, sensitive and continuous spectrophotometric method to screen lipases regio-selectivity using synthetic triglycerides (TG) containing α-eleostearic acid (9Z, 11E, 13E-octadecatrienoic acid) either at the sn-1 position [1-α-eleostearoyl-2,3-octadecyl-sn-glycerol (sn-EOO)] or at the sn-3 position [1,2-octadecyl-3-α-eleostearoyl-sn-glycerol (sn-OOE)] and coated onto the wells of microtiter plates...
June 16, 2017: Chemistry and Physics of Lipids
Motoharu Takao, Yumi Fukuda, Takeshi Morita
Since the discovery of intrinsic photosensitive retinal ganglion cell (ipRGC) was reported in 2002, many features specific to this cell type have been described. However, scare information is available on the retinographic components directly reflecting ipRGC activity. In this study, we identified the electroretinogram (microERG) that reflects the photoresponses by ipRGCs in ex vivo preparations of the mouse retina, in which classical photoreceptors (cones and rods) were ablated mechanically and photochemically...
June 16, 2017: Neuroscience
Assad Ullah Khan, Clayton Scruggs, David Hicks, Guoliang Liu
Conventional analysis and characterization of polymer brush formation relies on laborious methods that use quartz crystal microbalance, atomic force microscope, microcantilever, or other tools that measure concentration change of solutions. Herein we develop a simple and easy method that utilizes intrinsically-flat two-dimensional (2D) plasmonic nanoparticles as sensors for unveiling the mechanism of polymer brush formation on surfaces. Via ultraviolet-visible spectroscopy, the plasmonic nanoparticles can be used to determine the amount of polymers near the surface in situ...
June 20, 2017: Analytical Chemistry
Emmanuel Oppong, Gunter Stier, Miriam Gaal, Rebecca Seeger, Melanie Stoeck, Marc-André Delsuc, Andrew C B Cato, Bruno Kieffer
The human androgen receptor (AR) is a ligand inducible transcription factor that harbors an amino terminal domain (AR-NTD) with a ligand-independent activation function. AR-NTD is intrinsically disordered and displays aggregation properties conferred by the presence of a poly-glutamine (polyQ) sequence. The length of the polyQ sequence as well as its adjacent sequence motifs modulate this aggregation property. AR-NTD also contains a conserved KELCKAVSVSM sequence motif that displays an intrinsic property to form amyloid fibrils under mild oxidative conditions...
June 19, 2017: Biomolecules
Ke Wang, Yang Zhao, Deyong Chen, Chengjun Huang, Beiyuan Fan, Rong Long, Chia-Hsun Hsieh, Junbo Wang, Min-Hsien Wu, Jian Chen
This paper presents the instrumentation of a microfluidic analyzer enabling the characterization of single-cell biophysical properties, which includes seven key components: a microfluidic module, a pressure module, an imaging module, an impedance module, two LabVIEW platforms for instrument operation and raw data processing, respectively, and a Python code for data translation. Under the control of the LabVIEW platform for instrument operation, the pressure module flushes single cells into the microfluidic module with raw biophysical parameters sampled by the imaging and impedance modules and processed by the LabVIEW platform for raw data processing, which were further translated into intrinsic cellular biophysical parameters using the code developed in Python...
June 19, 2017: International Journal of Molecular Sciences
Janice Lim, Mingliang You, Jian Li, Zibiao Li
Polyhydroxyalkanoates (PHAs) are a class of biodegradable polymers derived from microorganisms. On top of their biodegradability and biocompatibility, different PHA types can contribute to varying mechanical and chemical properties. This has led to increasing attention to the use of PHAs in numerous biomedical applications over the past few decades. Bone tissue engineering refers to the regeneration of new bone through providing mechanical support while inducing cell growth on the PHA scaffolds having a porous structure for tissue regeneration...
October 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Eun-Ho Song, Seol-Ha Jeong, Ji-Ung Park, Sukwha Kim, Hyoun-Ee Kim, Juha Song
Polyurethane (PU)-based dressing foams have been widely used due to their excellent water absorption capability, optimal mechanical properties, and unequaled economic advantage. However, the low bioactivity and poor healing capability of PU limit the applications of PU dressings in complex wound healing cases. To resolve this problem, this study was carried out the hybridization of bioactive silica nanoparticles with PU through a one-step foaming reaction that is coupled with the sol-gel process. The hybridization with silica did not affect the intrinsically porous microstructure of PU foams with silica contents of up to 10wt% and where 5-60nm silica nanoparticles were well dispersed in the PU matrix, despite slight agglomerations...
October 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Roman Major, Hanna Plutecka, Anna Gruszczynska, Juergen M Lackner, Boguslaw Major
The aim of this study was to determine the mutagenic and thrombogenic potential of a material composed of a thin coating deposited on a polymeric substrate. In this work, a surface was modified in a manner that would mimic the function of cellular niches. Finally, the surfaces should actively capture and differentiate progenitor cells from the blood stream. Thin films with 10 to 500nm thicknesses were deposited by unbalanced, pulsed DC magnetron sputtering on smooth polyurethane. Such high energy conditions led to a stiffening of the polymer surface layers by pseudodiffusion during the initial stages of film growth...
October 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Alvaro Rafael Muñoz-Castro, Franck Gam, Dayan Paez-Hernandez, Ramiro Arratia-Perez, C W Liu, Samia Kahlal, Jean-Yves Saillard
Coinage-metal atomically precise nanoclusters are made of a well-defined metallic core embedded in a ligand-protecting outer shell. Whereas gold derivatives are particularly well documented, examples of silver nanoclusters are somewhat limited and copper species remain particularly scare. Our DFT relativistic calculations on superatomic metallic cores indicate that copper species are almost as stable as gold clusters and more stable than their silver counterparts. Thus, for silver superatomic cores, the role of the stabilizing ligands is more crucial in the stabilization of the overall structure, in comparison to copper and gold...
June 19, 2017: Chemistry: a European Journal
Jialiang Lang, Bin Ding, Shuai Zhang, Hanxiao Su, Binghui Ge, Longhao Qi, Huajian Gao, Xiaoyan Li, Qunyang Li, Hui Wu
2D Si nanomaterials have attracted tremendous attention due to their novel properties and a wide range of potential applications from electronic devices to energy storage and conversion. However, high-quality and large-scale fabrication of 2D Si remains challenging. This study reports a room-temperature and one-step synthesis technique that leads to large-scale and low-cost production of Si nanosheets (SiNSs) with thickness ≈4 nm and lateral size of several micrometers, based on the intrinsic delithiation process of chemically leaching lithium from the Li13 Si4 alloy...
June 19, 2017: Advanced Materials
Xian Kong, Diannan Lu, Jianzhong Wu, Zheng Liu
Supported lipid bilayers (SLBs) have been widely used in drug delivery, biosensors and biomimetic membranes. The microscopic mechanism of SLB formation and stability depends on a number of factors underlying solvent-mediated lipid-lipid and lipid-substrate interactions. Whereas recent years have witnessed remarkable progress in understanding the kinetics of SLB formation, relatively little is known about the lipid phase behavior controlling the SLB stability under diverse solution conditions. In this work, we examine the structure of SLBs using classical density functional theory (CDFT) in the context of a coarse-grained model that accounts for ion-explicit electrostatic interactions, surface hydrophobicity, as well as the molecular characteristics of the lipid tails...
June 19, 2017: Physical Chemistry Chemical Physics: PCCP
Aaron Mascaro, Zi Wang, Pierre Hovington, Yoichi Miyahara, Andrea Paolella, Vincent Gariepy, Zimin Feng, Tyler Enright, Connor Aiken, Karim Zaghib, Kirk H Bevan, Peter Grutter
One of the main challenges in improving fast charging lithium-ion batteries is the development of suitable active materials for cathodes and anodes. Many materials suffer from unacceptable structural changes under high currents and/or low intrinsic conductivities. Experimental measurements are required to optimize these properties, but few techniques are able to spatially resolve ionic transport properties at small length scales. Here we demonstrate an atomic force microscope (AFM)-based technique to measure local ionic transport on LiFePO4 to correlate with the structural and compositional analysis of the same region...
June 21, 2017: Nano Letters
Zhifang Li, Tianye Yang, Qi Zhao, Mingzhe Zhang
Trivalent lanthanide-doped luminescent nanomaterials have unique spectral and magnetic properties, which have been extensively investigated due to their potential application prospects in a number of new technologies. The rare earth Dy(3+) and Tb(3+) ions co-doped β-In2S3 dilute nanoparticles with different doping concentrations were successfully synthesized by a gas-liquid phase chemical deposition method. The band gap energy could be tuned by varying the doping concentration from 3.17 to 3.51 eV. The In2S3:Dy(3+),Tb(3+) nanoparticles exhibited strong photoluminescence emission peaks and room temperature ferromagnetism...
June 19, 2017: Physical Chemistry Chemical Physics: PCCP
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