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https://www.readbyqxmd.com/read/29144733/a-mechanism-for-symmetry-breaking-and-shape-control-in-single-crystal-gold-nanorods
#1
Michael J Walsh, Wenming Tong, Hadas Katz-Boon, Paul Mulvaney, Joanne Etheridge, Alison M Funston
The phenomenon of symmetry breaking-in which the order of symmetry of a system is reduced despite manifest higher-order symmetry in the underlying fundamental laws-is pervasive throughout science and nature, playing a critical role in fields ranging from particle physics and quantum theory to cosmology and general relativity. For the growth of crystals, symmetry breaking is the crucial step required to generate a macroscopic shape that has fewer symmetry elements than the unit cell and/or seed crystal from which it grew...
November 16, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/29143300/effect-of-restraining-the-base-of-support-on-the-other-biomechanical-features-in-patients-with-cerebellar-ataxia
#2
C Conte, Mariano Serrao, L Cuius, A Ranavolo, S Conforto, F Pierelli, L Padua
This study aimed to analyze the biomechanical consequences of reducing the base of support in patients with ataxia. Specifically, we evaluated the spatio-temporal parameters, upper- and lower-body kinematics, muscle co-activation, and energy recovery and expenditure. The gaits of 13 patients were recorded using a motion analysis system in unperturbed and perturbed walking conditions. In the latter condition, patients had to walk using the same step width and speed of healthy controls. The perturbed walking condition featured reduced gait speed, step length, hip and knee range of motion, and energy recovery and increased double support duration, gait variability, trunk oscillation, and ankle joint muscle co-activation...
November 15, 2017: Cerebellum
https://www.readbyqxmd.com/read/29137725/a-gait-retraining-system-using-augmented-reality-to-modify-footprint-parameters-effects-on-lower-limb-sagittal-plane-kinematics
#3
Sami Bennour, Baptiste Ulrich, Thomas Legrand, Brigitte M Jolles, Julien Favre
Improving lower-limb flexion/extension angles during walking is important for the treatment of numerous pathologies. Currently, these gait retraining procedures are mostly qualitative, often based on visual assessment and oral instructions. This study aimed to propose an alternative method combining motion capture and display of target footprints on the floor. The second objectives were to determine the error in footprint modifications and the effects of footprint modifications on lower-limb flexion/extension angles...
November 11, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/29131943/drift-tube-ion-mobility-how-to-reconstruct-collision-cross-section-distributions-from-arrival-time-distributions
#4
Adrien Marchand, Sandrine Livet, Frédéric Rosu, Valérie Gabelica
Ion mobility spectrometry allows one to determine ion collision cross sections, which are related to ion size and shape. Collision cross sections (CCS) are usually discussed based on the peak center, yet the width of each peak contains further information on the distribution of collision cross sections of each conformational ensemble. Here, we analyze how to convert arrival time distributions (ATD) to CCS distributions (CCSD). With a calibration curve taking into account the CCS dependence of the time spent outside the mobility region, one can reconstruct CCS distributions with correct peak center values...
November 13, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/29120084/excitation-dependent-photoluminescence-from-single-carbon-dots
#5
Bart van Dam, Hui Nie, Bo Ju, Emanuele Marino, Jos M J Paulusse, Peter Schall, Minjie Li, Katerina Dohnalová
Carbon dots (CDs) are carbon-based fluorescent nanoparticles that can exhibit excitation-dependent photoluminescence (PL) "tunable" throughout the entire visible range, interesting for optoelectronic and imaging applications. The mechanism underlying this tunable emission remains largely debated, most prominently being ascribed to dot-to-dot variations that ultimately lead to excitation-dependent ensemble properties. Here, single-dot spectroscopy is used to elucidate the origin of the excitation-dependent PL of CDs...
November 9, 2017: Small
https://www.readbyqxmd.com/read/29113724/imaging-with-ultra-small-angle-x-ray-scattering-using-a-laue-case-analyzer-and-its-application-to-human-breast-tumors
#6
Daisuke Shimao, Naoki Sunaguchi, Tenta Sasaya, Tetsuya Yuasa, Shu Ichihara, Tomonori Kawasaki, Masami Ando
PURPOSE: In this study, we demonstrate a novel imaging technique, based on ultra-small-angle X-ray scattering (USAXS) that uses a Laue-case Si wafer as the angle analyzer. METHODS: We utilized the (1 1 1) diffraction plane of a 356 μm thick, symmetrically cut Si wafer as the angle analyzer, denoted by A[L]. With this device, we performed USAXS imaging experiments using 19.8 keV synchrotron X-rays. The objects we imaged were formalin-fixed, paraffin-embedded breast tumors (an invasive carcinoma and an intraductal papilloma)...
November 4, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/29109306/hierarchy-and-scaling-behaviour-of-multi-rank-domain-patterns-in-ferroelectric-k-sub-0-9-sub-na-sub-0-1-sub-nbo-sub-3-sub-strained-films
#7
Dorothee Braun, Martin Schmidbauer, Michael Hanke, Jutta Schwarzkopf
The formation process of a ferroelectric multi-rank domain pattern in the thickness range of 7 to 52 nm is investigated for monoclinic K<sub>0.9</sub>Na<sub>0.1</sub>NbO<sub>3</sub> strained epitaxial films on (110) NdScO<sub>3</sub> substrates. Although the elastic strain energy density is degenerated for two pseudocubic orientations, a distinctive hierarchy of domain evolution is observed with exclusive in-plane a<sub>1</sub>a<sub>2</sub> domains for very thin films and the retarded onset of a ferroelectric M<sub>C</sub> phase at larger film thickness...
November 7, 2017: Nanotechnology
https://www.readbyqxmd.com/read/29108568/comprehensive-two-dimensional-gas-chromatography-using-partial-modulation-via-a-pulsed-flow-valve-with-a-short-modulation-period
#8
Chris E Freye, H Daniel Bahaghighat, Robert E Synovec
Partial modulation via a pulsed flow valve for comprehensive two-dimensional (2D) gas chromatography (GC × GC) is demonstrated, producing narrow peak widths, (2)Wb, on the secondary separation dimension, (2)D, coupled with short modulation periods, PM, thus producing a high peak capacity on the (2)D dimension, (2)nc. The GC × GC modulator is a pulse flow valve that injects a pulse of carrier gas at the specified PM, at the connection between the primary, (1)D, column and the (2)D column. Using a commercially available pulse flow valve, this injection technique performs a combination of vacancy chromatography and frontal analysis, whereby each pulse disturbance in the analyte concentration profile as it exits the (1)D column results in data that is readily converted into a (2)D separation...
January 15, 2018: Talanta
https://www.readbyqxmd.com/read/29106739/evaluation-of-tomotherapy-dose-calculations-with-intra-fractional-motion-and-motion-compensation
#9
Edward H Chao, Daniel Lucas, Eric Schnarr
PURPOSE: Anatomical motion, both cyclical and aperiodic, can impact the dose delivered during external beam radiation. In this work, we evaluate the use of a research version of the clinical TomoTherapy(®) dose calculator to calculate dose with intra-fraction rigid motion. We also evaluate the feasibility of a method of motion compensation for helical tomotherapy using the jaws and MLC. METHODS: Treatment plans were created using the TomoTherapy treatment planning system...
November 6, 2017: Medical Physics
https://www.readbyqxmd.com/read/29096123/in-vitro-validation-of-a-novel-mechanical-model-for-testing-the-anchorage-capacity-of-pedicle-screws-using-physiological-load-application
#10
Christian Liebsch, Julia Zimmermann, Nicolas Graf, Christoph Schilling, Hans-Joachim Wilke, Annette Kienle
Biomechanical in vitro tests analysing screw loosening often include high standard deviations caused by high variabilities in bone mineral density and pedicle geometry, whereas standardized mechanical models made of PU foam often do not integrate anatomical or physiological boundary conditions. The purpose of this study was to develop a most realistic mechanical model for the standardized and reproducible testing of pedicle screws regarding the resistance against screw loosening and the holding force as well as to validate this model by in vitro experiments...
October 25, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/29092144/mode-locked-tm-fiber-laser-using-smf-simf-gimf-smf-fiber-structure-as-a-saturable-absorber
#11
Huanhuan Li, Zhaokun Wang, Can Li, Junjie Zhang, Shiqing Xu
We demonstrate a mode-locked all-fiber Tm laser using a single mode-step index multimode-graded-index multimode-single mode fiber structure as a saturable absorber based on the nonlinear multimodal interference. Stable fundamentally mode-locking operation was obtained at a pump threshold of 180mW. The output soliton pulses had a center wavelength, spectral width, pulse duration, and repetition rate of 1888 nm, 3.6 nm, 1.4 ps, and19.82 MHz, respectively. This is a simple, low-cost, stable, and convenient laser oscillator with many potential applications in eye-safe ultrafast photonics...
October 30, 2017: Optics Express
https://www.readbyqxmd.com/read/29082783/impairments-in-spatiotemporal-gait-adaptation-during-obstacle-navigation-in-huntington-s-disease
#12
Naznine Anwar, Izelle Labuschagne, Katrina Simpson, Luke Smith, Nellie Georgiou-Karistianis
BACKGROUND: Navigating obstacles whilst walking might be associated with poorer balance and a higher risk of falling in individuals with symptomatic Huntington's disease (symp-HD). However, this issue has not been investigated within the literature. OBJECTIVE: A unique obstacle navigation experiment was designed to examine adaptive gait patterns in order to identify spatiotemporal gait characteristics that might be associated with poorer balance and a higher risk of falling in symp-HD...
October 1, 2017: Neurorehabilitation and Neural Repair
https://www.readbyqxmd.com/read/29072539/coordination-impairments-are-associated-with-falling-among-older-adults
#13
Eric G James, Suzanne G Leveille, Jeffrey M Hausdorff, Bruce Barton, Sarah Cote, Murat Karabulut, Phillip Conatser, David N Kennedy, Katherine L Tucker, Soham Al Snih, Kyriakos S Markides, Jonathan F Bean
Background/Study Context: Approximately one third of older adults over the age of 65, and over 40% of those over 80 years, fall each year, leading to fractures, morbidity, and mortality. Annual direct medical costs due to falls in the United States are approximately $19.2 billion. The identification of new treatable risk factors for falls has the potential to advance their prevention and rehabilitation. METHODS: A cross-sectional study of 127 community-dwelling adults aged 67-99 years was conducted...
October 26, 2017: Experimental Aging Research
https://www.readbyqxmd.com/read/29066982/foot-placement-characteristics-and-plantar-pressure-distribution-patterns-during-stepping-on-ground-in-neonates
#14
F Sylos-Labini, S Magnani, G Cappellini, V La Scaleia, A Fabiano, S Picone, P Paolillo, A Di Paolo, F Lacquaniti, Y Ivanenko
Stepping on ground can be evoked in human neonates, though it is rather irregular and stereotyped heel-to-toe roll-over pattern is lacking. Such investigations can provide insights into the role of contact- or load-related proprioceptive feedback during early development of locomotion. However, the detailed characteristics of foot placements and their association with motor patterns are still incompletely documented. We elicited stepping in 33 neonates supported on a table. Unilateral limb kinematics, bilateral plantar pressure distribution and EMG activity from up to 11 ipsilateral leg muscles were recorded...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/29063942/pure-zero-dimensional-cs4pbbr6-single-crystal-rhombohedral-microdisks-with-high-luminescence-and-stability
#15
Haihua Zhang, Qing Liao, Yishi Wu, Jianwei Chen, Qinggang Gao, Hongbing Fu
Zero-dimensional (0D) perovskite Cs4PbBr6 has been speculated to be an efficient solid-state emitter, exhibiting strong luminescense on achieving quantum confinement. Although several groups have reported strong green luminescence from Cs4PbBr6 powders and nanocrystals, doubts that the origin of luminescence comes from Cs4PbBr6 itself or CsPbBr3 impurities have been a point of controversy in recent investigations. Herein, we developed a facile one-step solution self-assembly method to synthesize pure zero-dimensional rhombohedral Cs4PbBr6 micro-disks (MDs) with a high PLQY of 52% ± 5% and photoluminescence full-width at half maximum (FWHM) of 16...
November 8, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29063599/observation-and-determination-of-periodontal-tissue-profile-using-optical-coherence-tomography
#16
S Kakizaki, A Aoki, M Tsubokawa, T Lin, K Mizutani, G Koshy, A Sadr, S Oda, Y Sumi, Y Izumi
BACKGROUND AND OBJECTIVE: Diagnosis is a crucial step in periodontal treatment. The aim of this study was to evaluate the effectiveness of optical coherence tomography (OCT) for observation and determination of periodontal tissue profiles in vivo. MATERIAL AND METHODS: In experiment 1, refractive indices of purified water, porcine gingiva and human gingiva at 1330 nm were determined for the analysis of OCT images of periodontal tissues. In experiment 2, OCT examination was performed in the midlabial apico-coronal plane of mandibular anteriors in 30 Asian volunteers with healthy gingiva...
October 24, 2017: Journal of Periodontal Research
https://www.readbyqxmd.com/read/29060031/effects-of-wide-step-walking-on-swing-phase-hip-muscle-forces-and-spatio-temporal-gait-parameters
#17
Soheil Bajelan, Hanatsu Nagano, Tony Sparrow, Rezaul K Begg
Human walking can be viewed essentially as a continuum of anterior balance loss followed by a step that re-stabilizes balance. To secure balance an extended base of support can be assistive but healthy young adults tend to walk with relatively narrower steps compared to vulnerable populations (e.g. older adults and patients). It was, therefore, hypothesized that wide step walking may enhance dynamic balance at the cost of disturbed optimum coupling of muscle functions, leading to additional muscle work and associated reduction of gait economy...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/29057513/optical-coherence-tomography-for-margin-definition-of-basal-cell-carcinoma-before-micrographic-surgery-recommendations-regarding-the-marking-and-scanning-technique
#18
N De Carvalho, S Schuh, N Kindermann, R Kästle, J Holmes, J Welzel
BACKGROUND/PURPOSE: Mohs Micrographic Surgery (MMS) is the preferred therapeutic treatment for high-risk basal cell carcinoma (BCC). Optical Coherence Tomography (OCT) is a non-invasive imaging technique that enables the diagnosis of BCC. We thought to determine the margins of BCCs with OCT, prior to MMS, to reduce the number of surgical steps. METHODS: Different permanent markers were tested on the skin regarding line width, resistance against disinfection and brightness in the OCT image...
October 23, 2017: Skin Research and Technology
https://www.readbyqxmd.com/read/29054002/low-temperature-preparation-of-oxygen-deficient-tin-dioxide-nanocrystals-and-a-role-of-oxygen-vacancy-in-photocatalytic-activity-improvement
#19
Supanan Anuchai, Sukon Phanichphant, Doldet Tantraviwat, Prayoonsak Pluengphon, Thiti Bovornratanaraks, Burapat Inceesungvorn
The introduction of oxygen vacancies (Vos) into tin dioxide crystal structure has been found as an effective method to improve its photocatalytic performance. Herein, oxygen-deficient tin dioxide (SnO2-x) nanocrystals were successfully prepared via a facile, one-step hydrothermal method at the temperature lower than those reported previously. The effect of hydrothermal temperature on phase composition and Vos content was also firstly investigated. Due to its high oxygen vacancy concentration, the SnO2-x prepared at 80 °C provides the best photocatalytic degradation of methyl orange under UV-visible light...
October 13, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/29049848/multi-step-crystallization-of-barium-carbonate-rapid-interconversion-of-amorphous-and-crystalline-precursors
#20
Michael L Whittaker, Paul J M Smeets, Hasti Asayesh-Ardakani, Reza Shahbazian-Yassar, Derk Joester
The direct observation of amorphous barium carbonate (ABC), which transforms into a previously unknown barium carbonate hydrate (herewith named gortatowskite) within a few hundred milliseconds of formation, is described. In situ X-ray scattering, cryo-, and low-dose electron microscopy were used to capture the transformation of nanoparticulate ABC into gortatowskite crystals, highly anisotropic sheets that are up to 1 μm in width, yet only about 10 nm in thickness. Recrystallization of gortatowskite to witherite starts within 30 seconds...
October 19, 2017: Angewandte Chemie
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