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E S Lourenço, C F A B Mourão, P E C Leite, J M Granjeiro, M D Calasans-Maia, G G Alves
Platelet-rich fibrin (PRF) membranes are biomaterials widely used for therapeutic purposes, and canonically produced through the processing of peripheral blood with fixed-angle rotor centrifuges. In this work, we evaluate the in vitro stability and release of cytokines and growth factors when these biomaterials are produced with a horizontal swing-out clinical centrifuge. Membranes produced from the blood of 14 donors were morphologically evaluated by scanning electron microscopy and fluorescence microscopy, and their stability was assessed by photographic recording after incubation in culture medium for up to 28 days...
January 18, 2018: Journal of Biomedical Materials Research. Part A
Samuel I Miller, Nina R Salama
Gram-negative bacteria are surrounded by two membrane bilayers separated by a space termed the periplasm. The periplasm is a multipurpose compartment separate from the cytoplasm whose distinct reducing environment allows more efficient and diverse mechanisms of protein oxidation, folding, and quality control. The periplasm also contains structural elements and important environmental sensing modules, and it allows complex nanomachines to span the cell envelope. Recent work indicates that the size or intermembrane distance of the periplasm is controlled by periplasmic lipoproteins that anchor the outer membrane to the periplasmic peptidoglycan polymer...
January 2018: PLoS Biology
Ramanathan Parameswaran, Aleksandr Voskoboinik, Alexandra Gorelik, Geoffrey Lee, Peter M Kistler, Prashanthan Sanders, Jonathan M Kalman
Aims: Rotor mapping and ablation have gained favour over the recent years as an emerging ablation strategy targeting drivers of atrial fibrillation (AF). Their efficacy, however, has been a topic of great debate with variable outcomes across centres. The aim of this study was to systematically review the recent medical literature to determine the medium-term outcomes of rotor ablation in patients with paroxysmal atrial fibrillation (PAF) and persistent atrial fibrillation (PeAF). Methods and results: A systematic search of the contemporary scientific literature (PubMed and EMBASE) was performed in August 2017...
January 11, 2018: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
Yan Li, Kirsten Pace, Pavel N Nesterenko, Brett Paull, Roger Stanley, Mirek Macka
A miniaturised high pressure 6-port injection valve has been designed and evaluated for its performance in order to facilitate the development of portable capillary high performance liquid chromatography (HPLC). The electrically actuated valve features a very small size (65 × 19 × 19mm) and light weight (33g), and therefore can be easily integrated in a miniaturised modular capillary LC system suited for portable field analysis. The internal volume of the injection valve was determined as 98 nL. The novel conical shape of the stator and rotor and the spring-loaded rotor performed well up to 32MPa (4641psi), the maximum operating pressure investigated...
April 1, 2018: Talanta
Marcel Schuck, Daniel Steinert, Thomas Nussbaumer, Johann W Kolar
Our world is increasingly powered by electricity, which is largely converted to or from mechanical energy using electric motors. Several applications have driven the miniaturization of these machines, resulting in high rotational speeds. Although speeds of several hundred thousand revolutions per minute have been used industrially, we report the realization of an electrical motor reaching 40 million rpm to explore the underlying physical boundaries. Millimeter-scale steel spheres, which are levitated and accelerated by magnetic fields inside a vacuum, are used as a rotor...
January 2018: Science Advances
Rikiya Watanabe, Makoto Genda, Yasuyuki Kato-Yamada, Hiroyuki Noji
F1-ATPase is a rotary motor protein driven by ATP hydrolysis. Among molecular motors, F1 exhibits unique high reversibility in chemo-mechanical coupling, synthesizing ATP from ADP and inorganic phosphate upon forcible rotor reversal. The ε subunit enhances ATP synthesis coupling efficiency to > 70% upon rotation reversal. However, the detailed mechanism has remained elusive. In this study, we performed stall-and-release experiments to elucidate how the ε subunit modulates ATP association/dissociation and hydrolysis/synthesis process kinetics and thermodynamics, key reaction steps for efficient ATP synthesis...
January 9, 2018: Biophysical Journal
Maria Besora, Pietro Vidossich, Agusti Lledos, Gregori Ujaque, Feliu Maseras
The result of the application of different approaches based on the ideal gas/rigid rotor/harmonic oscillator (IGRRHO) model, commonly used in popular software packages, for the calculation of free energies in solution is compared with that of ab initio molecular dynamics for a process involving ligand exchange in palladium complexes. The IGRRHO-based approaches considered differ in most cases in the extent to which the rotational and translational contributions are included in the correction. Our study supports the use the free energy values directly obtained from dispersion-corrected DFT functionals without any correction or with minor corrections at most...
January 10, 2018: Journal of Physical Chemistry. A
Wei Zhi, Jinkui Chu, Jinshan Li, Yinlong Wang
This paper aims to develop a novel attitude determination system aided by polarization sensor. An improved heading angle function is derived using the perpendicular relationship between directions of E-vector of linearly polarized light and solar vector in the atmospheric polarization distribution model. The Extended Kalman filter (EKF) with quaternion differential equation as a dynamic model is applied to fuse the data from sensors. The covariance functions of filter process and measurement noises are deduced in detail...
January 9, 2018: Sensors
Atsuko Nakanishi, Jun-Ichi Kishikawa, Masatada Tamakoshi, Kaoru Mitsuoka, Ken Yokoyama
Proton translocating rotary ATPases couple ATP hydrolysis/synthesis, which occurs in the soluble domain, with proton flow through the membrane domain via a rotation of the common central rotor complex against the surrounding peripheral stator apparatus. Here, we present a large data set of single particle cryo-electron micrograph images of the V/A type H+-rotary ATPase from the bacterium Thermus thermophilus, enabling the identification of three rotational states based on the orientation of the rotor subunit...
January 8, 2018: Nature Communications
Hans Dierckx, I V Biktasheva, H Verschelde, A V Panfilov, V N Biktashev
Meandering spiral waves are often observed in excitable media such as the Belousov-Zhabotinsky reaction and cardiac tissue. We derive a theory for drift dynamics of meandering rotors in general reaction-diffusion systems and apply it to two types of external disturbances: an external field and curvature-induced drift in three dimensions. We find two distinct regimes: with small filament curvature, meandering scroll waves exhibit filament tension, whose sign determines the stability and drift direction. In the regimes of strong external fields or meandering motion close to resonance, however, phase locking of the meander pattern is predicted and observed...
December 22, 2017: Physical Review Letters
Tina Gupta, Derek J Dean, Nicholas J Kelley, Jessica A Bernard, Ivanka Ristanovic, Vijay A Mittal
The present double-blind crossover study examines the effects of cerebellar transcranial direct current stimulation (tDCS) in controls and in an analogue population to psychosis: individuals reporting elevated symptoms of nonclinical psychosis (NCP). A total of 18 controls and 24 NCP individuals were randomized into conditions consisting of 25 minutes of anodal (active) or sham cerebellar tDCS. Following this, both groups completed a pursuit rotor task designed to measure procedural learning performance. Participants then returned 1-week later and received the corresponding condition (either active or sham) and repeated the pursuit rotor task...
December 30, 2017: Schizophrenia Bulletin
Ananad Bellam Balaji, Chantara Thevy Ratnam, Mohammad Khalid, Rashmi Walvekar
The effect of electron beam radiation on ethylene-propylene diene terpolymer/polypropylene blends is studied as an attempt to develop radiation sterilizable polypropylene/ethylene-propylene diene terpolymer blends suitable for medical devices. The polypropylene/ethylene-propylene diene terpolymer blends with mixing ratios of 80/20, 50/50, 20/80 were prepared in an internal mixer at 165°C and a rotor speed of 50 rpm/min followed by compression molding. The blends and the individual components were radiated using 3...
January 1, 2018: Journal of Biomaterials Applications
Zhisong Wang
Many motor proteins achieve high efficiency for chemomechanical conversion, and single-molecule force-resisting experiments are a major tool to detect the chemomechanical coupling of efficient motors. Here, we introduce several quantitative relations that involve only parameters extracted from force-resisting experiments and offer new benchmarks beyond mere efficiency to judge the chemomechanical optimality or deficit of evolutionary remote motors on the same footing. The relations are verified by the experimental data from F1-ATPase, kinesin-1, myosin V and cytoplasmic dynein, which are representative members of four motor protein families...
January 3, 2018: Integrative Biology: Quantitative Biosciences From Nano to Macro
A L Gregory, A Agarwal, J Lasenby
We present a novel application of rotors in geometric algebra to represent the change of curvature tensor that is used in shell theory as part of the constitutive law. We introduce a new decomposition of the change of curvature tensor, which has explicit terms for changes of curvature due to initial curvature combined with strain, and changes in rotation over the surface. We use this decomposition to perform a scaling analysis of the relative importance of bending and stretching in flexible tubes undergoing self-excited oscillations...
November 2017: Royal Society Open Science
Johannes Hellwagner, Nino Wili, Luis Fábregas Ibáñez, Johannes J Wittmann, Beat H Meier, Matthias Ernst
Dipolar recoupling techniques that use isolated rotor-synchronized π pulses are commonly used in solid-state NMR spectroscopy to gain insight into the structure of biological molecules. These sequences excel through their simplicity, stability towards radio-frequency (rf) inhomogeneity, and low rf requirements. For a theoretical understanding of such sequences, we present a Floquet treatment based on an interaction-frame transformation including the chemical-shift offset dependence. This approach is applied to the homonuclear dipolar-recoupling sequence Radio-Frequency Driven Recoupling (RFDR) and the heteronuclear recoupling sequence Rotational Echo Double Resonance (REDOR)...
December 20, 2017: Journal of Magnetic Resonance
Byounghyun Lim, Minki Hwang, Jun-Seop Song, Ah-Jin Ryu, Boyoung Joung, Eun Bo Shim, Hyungon Ryu, Hui-Nam Pak
BACKGROUND: We previously reported that stable rotors are observed in in-silico human atrial fibrillation (AF) models, and are well represented by a dominant frequency (DF). In the current study, we hypothesized that the outcome of DF ablation is affected by conduction velocity (CV) conditions and examined this hypothesis using in-silico 3D-AF modeling. METHODS: We integrated 3D CT images of left atrium obtained from 10 patients with persistent AF (80% male, 61...
2017: PloS One
Ivan E Ivanov, Paul Lebel, Florian C Oberstrass, Charles H Starr, Angelica C Parente, Athena Ierokomos, Zev Bryant
Single-molecule methods provide direct measurements of macromolecular dynamics, but are limited by the number of degrees of freedom that can be followed at one time. High-resolution rotor bead tracking (RBT) measures DNA torque, twist, and extension, and can be used to characterize the structural dynamics of DNA and diverse nucleoprotein complexes. Here, we extend RBT to enable simultaneous monitoring of additional degrees of freedom. Fluorescence-RBT (FluoRBT) combines magnetic tweezers, infrared evanescent scattering, and single-molecule FRET imaging, providing real-time multiparameter measurements of complex molecular processes...
December 13, 2017: Biophysical Journal
Kedar K Aras, Matthew W Kay, Igor R Efimov
No abstract text is available yet for this article.
December 2017: Circulation. Arrhythmia and Electrophysiology
Paul William Bisso, Michelle Tai, Hari Katepalli, Nicolas Bertrand, Daniel Blankschtein, Robert Langer
Hydrophobic self-assembly pairs diverse chemical precursors and simple formulation processes to access a vast array of functional colloids. Exploration of this design space, however, is stymied by lack of broadly general, high-throughput colloid characterization tools. Here, we show that a narrow structural subset of fluorescent, zwitterionic molecular rotors - dialkylaminostilbazolium sulfonates [DASS] with intermediate-length alkyl tails - fills this major analytical void by quantitatively sensing hydrophobic interfaces in microplate format...
December 15, 2017: Nano Letters
P Feneyrou, L Leviandier, J Minet, G Pillet, A Martin, D Dolfi, J-P Schlotterbeck, P Rondeau, X Lacondemine, A Rieu, T Midavaine
Frequency-modulated continuous-wave lidar is evaluated for range finding, velocimetry, and laser anemometry. An original signal processing and waveform calibration for range finding leads to a reduction of computational effort while preserving capability for long-range measurement. Multiple target distance measurement is also demonstrated. For laser anemometry, the aim is to avoid parasitic echoes in the vicinity of a helicopter and to measure the air speed at the shortest distance farther than the rotor-induced turbulent volume around the helicopter...
December 10, 2017: Applied Optics
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