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https://www.readbyqxmd.com/read/30115898/effects-of-loading-frequency-and-loading-type-on-high-cycle-and-very-high-cycle-fatigue-of-a-high-strength-steel
#1
Yuanpei Hu, Chengqi Sun, Jijia Xie, Youshi Hong
High-cycle and very-high-cycle fatigue tests via rotary bending (52.5 Hz), electromagnetic resonance (120 Hz) axial cycling, and ultrasonic (20 kHz) axial cycling were performed for a high-strength steel with three heat treatment conditions, and the effects of loading frequency and loading type on fatigue strength and fatigue life were investigated. The results revealed that the loading frequency effect is caused by the combined response of strain rate increase and induced temperature rise. A parameter η was proposed to judge the occurrence of loading frequency effect, and the calculated results were in agreement with the experimental data...
August 16, 2018: Materials
https://www.readbyqxmd.com/read/30113117/computed-microtomography-study-of-untreated-shaped-and-filled-mesiobuccal-canals-of-maxillary-first-molars
#2
Daniele Angerame, Matteo De Biasi, Francesco Brun, Gianluca Turco, Vittorio Franco
This study assessed the effectiveness of modern endodontic shaping and filling procedures on mesiobuccal roots of maxillary molars with two canals. The canals of 20 mesiobuccal roots were treated with Mtwo rotary files, passive ultrasonic irrigation and Guttafusion obturators. X-ray computed microtomography analysis was carried out prior to treatment, after canal shaping and after canal filling to determine the alterations of the canal volume before and after the instrumentation, the volume of the hard tissue debris, and percentage of the volume occupied by filling materials...
August 16, 2018: Australian Endodontic Journal: the Journal of the Australian Society of Endodontology Inc
https://www.readbyqxmd.com/read/30112755/modern-neonatal-transport-sound-and-vibration-levels-and-their-impact-on-physiological-stability
#3
Vickie Bailey, Edgardo Szyld, Kristi Cagle, Deborah Kurtz, Hala Chaaban, Dee Wu, Patricia Williams
OBJECTIVE:  To measure sound and vibration in rotary wing air transport (RWAT) and ground ambulance transport (GAT), comparing them to current recommendations, and correlating them with physiological stability measures in transported neonates. STUDY DESIGN:  This is a prospective cohort observational study including infants ≤ 7 days of age transported over an 8-month period. Infants with neurologic conditions were excluded. Sound and vibration was continuously measured during transport...
August 15, 2018: American Journal of Perinatology
https://www.readbyqxmd.com/read/30111558/wing-inertia-as-a-cause-of-aerodynamically-uneconomical-flight-with-high-angles-of-attack-in-hovering-insects
#4
Hoang Vu Phan, Hoon Cheol Park
Flying insects can maintain maneuverability in the air by flapping their wings, and to save energy, the wings should operate following the optimal kinematics. However, unlike conventional rotary wings, insects operate their wings at aerodynamically uneconomical and high angles-of-attack (AoAs). Although insects have continuously received attention from biologists and aerodynamicists, the high AoA operation in insect flight has not been clearly explained. Here, we use a theoretical blade-element model to examine the impact of wing inertia on the power requirement and flapping AoA, based on three-dimensional free-hovering flight wing kinematics of a horned beetle, Alloymyrina dichotoma The relative simplicity of the model allows us to search for the best AoAs distributed along the wingspan, which generate the highest vertical force per unit power...
August 15, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30111107/fulgides-as-light-driven-molecular-rotary-motors-computational-design-of-a-prototype-compound
#5
Michael Filatov, Marco Paolino, Seung Kyu Min, Kwang S Kim
A new family of light driven molecular rotary motors utilizing the fulgide motif is proposed and its prototype molecule is studied by quantum chemical calculations and non-adiabatic molecular dynamics simulations. The new motor performs pure unidirectional axial rotation of the rotor blade with high quantum efficiency (φ ∼ 0.55-0.68) and ultrafast dynamics (⟨t⟩S1 ∼ 200-300 fs) of its successive photoisomerization steps. The photocyclization reaction typical of fulgide compounds is blocked by the design of the new motor and never occurred in the molecular dynamics simulations...
August 15, 2018: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/30110975/effect-of-electromagnetic-stirring-on-the-microstructure-and-properties-of-fe-cr-co-steel
#6
Lin Zhang, Yuhang Hou, Xiao Guo, Zhaolong Xiang, Engang Wang
High chromium steel has been synthesized by an induction furnace adopting electromagnetic stirring (EMS). Varying amounts of cobalt was added to obtain 3, 6, and 12% Co in the steel. The melt was allowed to solidify with or without EMS in a rotary magnetic field. The effects of the varying cobalt content and the stirring have been characterized by the microstructural evolution and the consequent improvement in mechanical properties. The application of a rotary EMS during solidification has shown a significant effect on the grain refining, the reduction of element segregation, the promotion of eutectic volume fraction, and the consequent improvement of mechanical properties, including hardness and high-temperature strength...
August 14, 2018: Materials
https://www.readbyqxmd.com/read/30110747/combined-influence-of-hydrodynamics-and-chemotaxis-in-the-distribution-of-microorganisms-around-spherical-nutrient-sources
#7
Nikhil Desai, Arezoo M Ardekani
We study how the interaction between hydrodynamics and chemotaxis affects the colonization of nutrient sources by microorganisms. We use an individual-based model and perform probabilistic simulations to ascertain the impact of important environmental and motility characteristics on the spatial distribution of microorganisms around a spherical nutrient source. In general, we unveil four distinct regimes based on the distribution of the microorganisms: (i) strong surface colonization, (ii) rotary-diffusion-induced "off-surface" accumulation, (iii) a depletion zone in the spatial distribution, and (iv) no appreciable aggregation, with their occurrence being contingent on the relative strengths of hydrodynamic and chemotactic effects...
July 2018: Physical Review. E
https://www.readbyqxmd.com/read/30107220/impact-of-blend-properties-on-die-filling-during-tableting
#8
B Van Snick, W Grymonpré, J Dhondt, K Pandelaere, G Di Pretoro, J P Remon, T De Beer, C Vervaet, V Vanhoorne
Based on characterization of a wide range of fillers and APIs, thirty divergent blends were composed and subsequently compressed on a rotary tablet press, varying paddle speed and turret speed. The tablet weight variability was determined of 20 grab samples consisting of each 20 tablets. Additionally, the bulk residence time, ejection force, pre-compression displacement, main compression force, die fill fraction and feed frame fill fraction were determined during each run. Multivariate data analysis was applied to investigate the relation between the process parameters, blend characteristics, product and process responses...
August 11, 2018: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/30106673/a-high-definition-non-invasive-neuromuscular-electrical-stimulation-system-for-cortical-control-of-combinatorial-rotary-hand-movements-in-a-human-with-tetraplegia
#9
Nicholas Annetta, Jeffrey Friend, Andrew Schimmoeller, Vimal S Buck, David Friedenberg, Chad E Bouton, Marcia A Bockbrader, Patrick Ganzer, Sam Colachis, Mingming Zhang, W Jerry Mysiw, Ali R Rezai, Gaurav Sharma
OBJECTIVE: Paralysis resulting from spinal cord injury (SCI) can have a devastating effect on multiple arm and hand motor functions. Rotary hand movements, such as supination and pronation, are commonly impaired by upper extremity paralysis, and are essential for many activities of daily living. In this proof-of-concept study, we utilize a neural bypass system (NBS) to decode motor intention from motor cortex to control combinatorial rotary hand movements elicited through stimulation of the arm muscles, effectively bypassing the SCI of the study participant...
August 7, 2018: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/30105836/lubrication-during-root-canal-treatment
#10
REVIEW
Nicholas Chandler, Deepak Chellappa
Lubrication is involved in all root canal treatment phases, from dental dam placement to canal obturation. Most often associated with instrumentation, lubrication is required to facilitate the mechanical action of hand/rotary files and to help emulsify and suspend the debris produced. Aqueous irrigation solutions such as sodium hypochlorite and ethylenediaminetetraacetic acid (EDTA) should be regarded as lubricants, but paste-type substances are marketed specifically for this purpose. As more patients demand the retention of challenging teeth with narrow and curved root canals, the importance of lubrication in all aspects of root canal treatment must be acknowledged...
August 13, 2018: Australian Endodontic Journal: the Journal of the Australian Society of Endodontology Inc
https://www.readbyqxmd.com/read/30105499/non-surgical-endodontic-management-of-immature-permanent-mandibular-first-molar-a-3-year-follow-up
#11
P K Musale, S Kothare
BACKGROUND: Deep carious lesions in immature permanent molars with pulp necrosis pose a serious challenge to contemporary paedodontic practice. A further complex clinical scenario is an immature permanent molar with varying root formation in both roots. This case report demonstrates the successful management of an immature permanent mandibular first molar. CASE REPORT: An 8-year-old boy was referred for endodontic management of 36 by a general practitioner. After clinical and radiographic evaluation, a diagnosis of recurrent chronic periapical abscess with abrupt root closure in the mesial root and cessation of root closure in the distal root was made...
August 13, 2018: European Archives of Paediatric Dentistry: Official Journal of the European Academy of Paediatric Dentistry
https://www.readbyqxmd.com/read/30096551/dynamics-of-magnetization-under-stimulus-induced-rotary-saturation-sequence
#12
Hiroyuki Ueda, Hiroaki Seki, Yosuke Ito, Takenori Oida, Yo Taniguchi, Testsuo Kobayashi
We studied stimulus-induced rotary-saturation preparation (which enables measurement of oscillating magnetic fields using MRI) and derived an analytical solution of the Bloch equation to understand magnetization dynamics mathematically and comprehensively and to conduct simulations without sequential-calculation techniques such as the Runge-Kutta method. We formulated the dynamics using the Bloch equation, introducing an additional rotating frame and some approximations to make it into a homogeneous differential equation...
July 20, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/30094842/the-importance-of-venous-return-in-starling-like-control-of-rotary-ventricular-assist-devices
#13
Andrew Stephens, Shaun Gregory, Robert Salamonsen
Rotary ventricular assist devices (VADs) are less sensitive to preload than the healthy heart, resulting in inadequate flow regulation in response to changes in patient cardiac demand. Starling-like physiological controllers (SLCs) have been developed to automatically regulate VAD flow based on ventricular preload. An SLC consists of a cardiac response curve (CRC) which imposes a non-linear relationship between VAD flow and ventricular preload, and a venous return line (VRL) which determines the return path of the controller...
August 9, 2018: Artificial Organs
https://www.readbyqxmd.com/read/30093105/discrete-time-setpoint-triggered-reset-integrator-design-with-guaranteed-performance-and-stability
#14
Raaja Ganapathy Subramanian, Vinodh Kumar Elumalai
According to Bode's gain-phase relationship, in linear time-invariant controllers, introducing an integral action to eliminate the steady-state error has an adverse effect of increased phase delay and overshoot, leading to performance deterioration. Moreover, increasing the bandwidth of the closed-loop system to enhance the low-frequency disturbance rejection invariably amplifies the sensitivity to high-frequency disturbances. Hence, the performance of the linear controllers is always limited due to these fundamental frequency- and time-domain limitations...
August 6, 2018: ISA Transactions
https://www.readbyqxmd.com/read/30088100/mechanism-of-fracture-of-niti-superelastic-endodontic-rotary-instruments
#15
Javier Gil, Elisa Rupérez, Eugenio Velasco, Conrado Aparicio, José María Manero
The aim is to investigate the premature catastrophic fracture produced for different periods during clinical endodontic treatment of two brands of NiTi endodontic rotary instruments. 3 samples as-received, 6 samples used with patients for 2 and 7 h and 5 samples fractured were studied for each brand of endodontic NiTi rotary instruments. Transformation temperatures (Ms , Mf , As and Af ) and enthalpies of transformation were determined by calorimetry. Critical stresses until fracture (σβ→SIM , σSIM→β ) were obtained using an electromechanical testing machine...
August 7, 2018: Journal of Materials Science. Materials in Medicine
https://www.readbyqxmd.com/read/30083493/toward-fast-and-efficient-visible-light-driven-molecular-motors-a-minimal-design
#16
Jun Wang, Bo Durbeej
A key goal in the development of light-driven rotary molecular motors is to facilitate their usage in biology and medicine by shifting the required irradiation wavelengths from the UV regime to the nondestructive visible regime. Although some progress has been made toward this goal, most available visible-light-driven motors either have relatively low quantum yields or require that thermal steps follow the photoisomerizations that underlie the rotary motion. Here, a minimal design for visible-light-driven motors without these drawbacks is presented and evaluated on the basis of state-of-the-art quantum chemical calculations and molecular dynamics simulations...
August 2018: ChemistryOpen
https://www.readbyqxmd.com/read/30083211/influence-of-two-preparation-techniques-on-transportation-of-simulated-type-ii-root-canals
#17
Saeed Moradi, Maryam Gharechahi, Fatemeh Bonyadimanesh
Introduction: The purpose of this study was to evaluate the changes of canal configuration in simulated type II root canals that were instrumented by two different techniques using ProTaper Universal rotary files. Methods and Materials: Sixty simulated type II root canal in resin blocks were made and randomly divided into two groups. Pre and post-instrumentation images of resin blocks were prepared using stereomicroscope from three surfaces of blocks included two longitudinal section (mesiodistally and buccolingually), and one cross sectional surface...
2018: Iranian Endodontic Journal
https://www.readbyqxmd.com/read/30083208/effects-of-different-irrigation-solutions-on-root-fracture-resistance-an-in-vitro-study
#18
Melissa Cristina Lantigua Domínguez, Victor Feliz Pedrinha, Lorena Cássia Oliveira Athaide da Silva, Mara Eliane Soares Ribeiro, Sandro Cordeiro Loretto, Patrícia de Almeida Rodrigues
Introduction: The aim of this in vitro study was to evaluate the effects of sodium hypochlorite (NaOCl), ethylenediaminetetraacetic acid (EDTA), chlorhexidine (CHX) and hydroxyethylidene bisphosphonate (HEBP), also known as etidronate, on susceptibility to root fracture resistance (RFR) in human teeth subjected to endodontic preparation. Methods and Materials: Seventy extracted single-rooted human teeth were selected, endodontically prepared using the ProTaper Next rotary system (PTN, Dentsply, Maillefer, Ballaigues, Switzerland) and then randomly divided according to the following irrigation regimes ( n =10): G1, saline solution (0...
2018: Iranian Endodontic Journal
https://www.readbyqxmd.com/read/30082903/a-coevolution-guided-model-for-the-rotor-of-the-bacterial-flagellar-motor
#19
Shahid Khan, Tai Wei Guo, Saurav Misra
The Salmonella typhimurium trans-membrane FliF MS ring templates assembly of the rotary bacterial flagellar motor, which also contains a cytoplasmic C-ring. A full-frame fusion of FliF with the rotor protein FliG assembles rings in non-motile expression hosts. 3D electron microscopy reconstructions of these FliFFliG rings show three high electron-density sub-volumes. 3D-classification revealed heterogeneity of the assigned cytoplasmic volume consistent with FliG lability. We used residue coevolution to construct homodimer building blocks for ring assembly, with X-ray crystal structures from other species and injectisome analogs...
August 6, 2018: Scientific Reports
https://www.readbyqxmd.com/read/30081754/the-mechanics-of-bolt-drilling-and-theoretical-analysis-of-drilling-parameter-effects-on-respirable-dust-generation
#20
Hua Jiang, Yi Luo, Jian Yang
The respirable dust generated during bolt-hole drilling can present serious health problems to the miners involved in roof drilling operations. A proactive dust control approach, different from the conventional passive approaches, is proposed. Laboratory experiments have been conducted to validate the dust reduction effects of the approach. A mechanical model has been developed to simulate the rotary drag bits drilling process under different cutter conditions. The functions of the area of the total friction, drilling power and specific energy are all presented in the model...
August 6, 2018: Journal of Occupational and Environmental Hygiene
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