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Rate of force production

Olga Eguaogie, Joseph S Vyle, Patrick F Conlon, Manuela A Gîlea, Yipei Liang
The application of mechanical force to induce the formation and cleavage of covalent bonds is a rapidly developing field within organic chemistry which has particular value in reducing or eliminating solvent usage, enhancing reaction rates and also in enabling the preparation of products which are otherwise inaccessible under solution-phase conditions. Mechanochemistry has also found recent attention in materials chemistry and API formulation during which rearrangement of non-covalent interactions give rise to functional products...
2018: Beilstein Journal of Organic Chemistry
Nicholas J Clark, Ricardo J Soares Magalhães
BACKGROUND: Q fever is a zoonotic disease caused by Coxiella burnetii. This bacterium survives harsh conditions and attaches to dust, suggesting environmental dispersal is a risk factor for outbreaks. Spatial epidemiology studies collating evidence on Q fever geographical contamination gradients are needed, as human cases without occupational exposure are increasing worldwide. METHODS: We used a systematic literature search to assess the role of distance from ruminant holdings as a risk factor for human Q fever outbreaks...
May 15, 2018: BMC Infectious Diseases
Daniel James Madigan, Miling Li, Runsheng Yin, Hannes Baumann, Owyn E Snodgrass, Heidi Dewar, David P Krabbenhoft, Zofia Baumann, Nicholas S Fisher, Prentiss H Balcom, Elsie M Sunderland
Pelagic ecosystems are changing due to environmental and anthropogenic forces, with uncertain consequences for the ocean's top predators. Epipelagic and mesopelagic prey resources differ in quality and quantity, but their relative contribution to predator diets has been difficult to track. We measured mercury (Hg) stable isotopes in young (<2 years old) Pacific bluefin tuna (PBFT) and their prey species to explore the influence of foraging depth on growth and methylmercury (MeHg) exposure. PBFT total Hg (THg) in muscle ranged from 0...
May 15, 2018: Environmental Science & Technology
Cameron S Mackey, Ryan M Thiele, Eric C Conchola, Jason M DeFreitas
PURPOSE: To compare maximal and rapid force characteristics, as well as fatigability, between traditional (TRT) and explosive (ERT) resistance-trained men. METHODS: Fourteen TRT (mean age = 25 years) and twelve ERT (mean age = 22 years) men performed rapid maximal contractions followed by an isokinetic fatigue protocol consisting of 50 maximal knee extension (KE) and flexions (KF) at a moderate speed (180° s- ¹). Baseline measures included: isokinetic peak torque (PT), isometric rate of torque development (RTD0-50 ), peak acceleration (ACCmax ), and peak velocity (Vmax )...
May 14, 2018: European Journal of Applied Physiology
Frank Seifart, Jan Strunk, Swintha Danielsen, Iren Hartmann, Brigitte Pakendorf, Søren Wichmann, Alena Witzlack-Makarevich, Nivja H de Jong, Balthasar Bickel
By force of nature, every bit of spoken language is produced at a particular speed. However, this speed is not constant-speakers regularly speed up and slow down. Variation in speech rate is influenced by a complex combination of factors, including the frequency and predictability of words, their information status, and their position within an utterance. Here, we use speech rate as an index of word-planning effort and focus on the time window during which speakers prepare the production of words from the two major lexical classes, nouns and verbs...
May 14, 2018: Proceedings of the National Academy of Sciences of the United States of America
Norbert Mücke, Lara Kämmerer, Stefan Winheim, Robert Kirmse, Jan Krieger, Maria Mildenberger, Jochen Baßler, Ed Hurt, Wolfgang H Goldmann, Ueli Aebi, Katalin Toth, Jörg Langowski, Harald Herrmann
Intermediate filaments (IFs) are principal components of the cytoskeleton, a dynamic integrated system of structural proteins that provides the functional architecture of metazoan cells. They are major contributors to the elasticity of cells and tissues due to their high mechanical stability and intrinsic flexibility. The basic building block for the assembly of IFs is a rod-like, 60-nm-long tetrameric complex made from two antiparallel, half-staggered coiled coils. In low ionic strength, tetramers form stable complexes that rapidly assemble into filaments upon raising the ionic strength...
May 10, 2018: Biophysical Journal
Navneet K Bhogal, Alveera Hasan, Julia Gorelik
3&prime;-5&prime;-cyclic adenosine monophosphate (cAMP) is a signaling messenger produced in response to the stimulation of cellular receptors, and has a myriad of functional applications depending on the cell type. In the heart, cAMP is responsible for regulating the contraction rate and force; however, cAMP is also involved in multiple other functions. Compartmentation of cAMP production may explain the specificity of signaling following a stimulus. In particular, transverse tubules (T-tubules) and caveolae have been found to be critical structural components for the spatial confinement of cAMP in cardiomyocytes, as exemplified by beta-adrenergic receptor (&beta;-ARs) signaling...
May 3, 2018: Journal of Cardiovascular Development and Disease
David R Slochower, Michael K Gilson
Molecular motors are thought to generate force and directional motion via nonequilibrium switching between energy surfaces. Because all enzymes can undergo such switching, we hypothesized that the ability to generate rotary motion and torque is not unique to highly adapted biological motor proteins but is instead a common feature of enzymes. We used molecular dynamics simulations to compute energy surfaces for hundreds of torsions in three enzymes-adenosine kinase, protein kinase A, and HIV-1 protease-and used these energy surfaces within a kinetic model that accounts for intersurface switching and intrasurface probability flows...
May 8, 2018: Biophysical Journal
Mathijs J Hofmijster, Lotte L Lintmeijer, Peter J Beek, A J Knoek van Soest
Mechanical power output is a key performance-determining variable in many cyclic sports. In rowing, instantaneous power output is commonly determined as the dot product of handle force moment and oar angular velocity. The aim of this study was to show that this commonly used proxy is theoretically flawed and to provide an indication of the magnitude of the error. To obtain a consistent dataset, simulations were performed using a previously proposed forward dynamical model. Inputs were previously recorded rower kinematics and horizontal oar angle, at 20 and 32 strokes∙min-1 ...
May 8, 2018: Journal of Sports Sciences
Lotte L Lintmeijer, Mathijs J Hofmijster, Guido A Schulte Fischedick, Patrick J Zijlstra, A J Knoek Van Soest
In rowing, mechanical power output is a key parameter for biophysical analyses and performance monitoring and should therefore be measured accurately. It is common practice to estimate on-water power output as the time average of the dot product of the moment of the handle force relative to the oar pin and the oar angular velocity. In a theoretical analysis we have recently shown that this measure differs from the true power output by an amount that equals the mean of the rower's mass multiplied by the rower's center of mass acceleration and the velocity of the boat...
May 8, 2018: Journal of Sports Sciences
J Comaposada, B Marcos, R Bou, P Gou
Calcium alginate structures are of interest as replacers for natural casings due to their high availability, biodegradability and low price. The aim of this paper is to study the effect of oil, surfactants and proteins (pea and collagen) on the water transfer, mechanical and microstructural properties of the wet calcium alginate films. The addition of oil and surfactants tended to reduce the water permeance and the weight loss rate, reaching values between those shown by natural and collagen artificial casings...
June 2018: Food Research International
Guoliang Li, Lihong Liang, Jingchao Yang, Lihai Zeng, Zhiwei Xie, Yizhou Zhong, Xiaolin Ruan, Ming Dong, Zhanhong Yang, Guanchao Lai, Weixin Huang, Aichu Yang, Jiabing Chen, Banghua Wu, Huaming Xu, Dezhi Meng, Shijie Hu, Lihua Xia, Xingfen Yang, Laiyu Li, Sahoko Ichihara, Gaku Ichihara, Hanlin Huang, Zhenlie Huang
Calcium carbonate nanomaterials (nano-CaCO3 ) are widely used in both manufacturing and consumer products, but their potential health hazards remain unclear. The objective of this study was to survey workplace exposure levels and health effects of workers exposed to nano-CaCO3 . Personal and area sampling, as well as real-time and dust monitoring, were performed to characterize mass exposure, particle size distribution, and particle number exposure. A total of 56 workers (28 exposed workers and 28 unexposed controls) were studied in a cross-sectional study...
May 6, 2018: Nanotoxicology
Nur Liyana Mohammed Yusof, Satirah Zainalabidin, Norsyahida Mohd Fauzi, Siti Balkis Budin
Diabetes mellitus is often associated with cardiac functional and structural alteration, an initial event leading to cardiovascular complications. <i>Hibiscus sabdariffa</i> or roselle has been widely proven as an antioxidant and recently has incited research interest for its potential in treating cardiovascular disease. Therefore, this study aimed to determine the cardioprotective effects of <i>H. sabdariffa </i>(roselle) polyphenol-rich extract (HPE) in type-1 induced diabetic rats...
May 4, 2018: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
C Purna Chander, B Raju, M Ramesh, G Shankar, R Srinivas
RATIONALE: Stress stability studies of drugs have been recognized as an essential part of the drug development process. These studies are used to investigate the intrinsic stability of the drugs and for the development of a selective stability indicating assay method (SIAM). Stress testing is also useful for the formulation and packaging development, shelf-life determination and designing of manufacturing processes. As per regulatory guidelines, stress degradation studies and structural characterization should be carried out to establish degradation pathways of the drug, which is essential from both efficacy and safety point of view...
May 3, 2018: Rapid Communications in Mass Spectrometry: RCM
Jian Nan Liu, Ming Yi Wang, Kenneth Wan, Jing Han, Shi Jian Zhang, Xing Zhou Qu, Hui Shan Ong
PURPOSE: Previous studies have shown that biodegradable implants can be used in mandibular fixation with optimal results. The effect of postoperative radiotherapy (PORT) on the implants' degradation rate, strength, and by-product secretion is not yet known. PATIENTS AND METHODS: This prospective randomized controlled trial included 40 consecutive mandibulotomy patients randomly divided into either the titanium or biodegradable osteofixation cohort. All patients received PORT...
April 7, 2018: Journal of Oral and Maxillofacial Surgery
Amanda Y Kong, Shelley D Golden, Allison E Myers, Melissa A Little, Robert Klesges, Wayne Talcott, Sara M Vandegrift, Daniel G Cassidy, Kurt M Ribisl
INTRODUCTION: Active duty military personnel have higher cigarette and smokeless tobacco use rates than civilian populations. Although US Airmen (called Airmen regardless of gender or rank) are required to be tobacco-free during initial training, many resume use once this period ends, perhaps as a result of easy access to cheap tobacco products. METHODS: Between July and September 2016, we collected tobacco product, price and promotion information by visiting on-base (n=28) and off-base (n=80) tobacco retailers near the eight technical training bases where approximately 99% of Airmen attend training...
April 28, 2018: Tobacco Control
Evangelos Karagiannis, Michail Michailidis, Katerina Karamanoli, Athina Lazaridou, Ioannis S Minas, Athanassios Molassiotis
Sweet cherry, a non-climacteric and highly perishable fruit, is usually cold-stored during post-harvest period to prevent senescence; therefore, metabolic profiling in response to cold storage in sweet cherry is of economic and scientific interest. In the present work, metabolic analysis was performed in fruit and stem tissues to determine the metabolic dynamics associated with cold storage in response to 1-methylcyclopropene (1-MCP), an ethylene-action inhibitor, and modified atmosphere packaging (MAP). Fruit (cv...
April 24, 2018: Plant Physiology and Biochemistry: PPB
Vassilios Raikos, Shannon B Grant, Helen Hayes, Viren Ranawana
Powdered β-glucan extracted from brewer's yeast (Yestimun, Leiber GmbH, Bramsche, Germany) was incorporated into skimmed-milk yogurt at varying concentrations (0.2-0.8% wt/wt) to investigate its potential application as a thickener. The effect of β-glucan fortification on the nutritional profile, microstructure, physicochemical properties, and texture of freshly prepared yogurts was investigated. Sensory evaluation was also conducted and was correlated with instrumental analysis. The addition of Yestimun significantly reduced the fermentation time of the yogurt mix from 4 h to 3 h...
April 25, 2018: Journal of Dairy Science
María Sebastián, Adrián Velázquez-Campoy, Milagros Medina
Emergence of multidrug-resistant bacteria forces us to explore new therapeutic strategies, and proteins involved in key metabolic pathways are promising anti-bacterial targets. Bifunctional flavin-adenine dinucleotide (FAD) synthetases (FADS) are prokaryotic enzymes that synthesise the flavin mononucleotide (FMN) and FAD cofactors. The FADS from the human pathogen Streptococcus pneumoniae (SpnFADS)-causative agent of pneumonia in humans - shows relevant catalytic dissimilarities compared to other FADSs...
December 2018: Journal of Enzyme Inhibition and Medicinal Chemistry
Sidney Grosprêtre, Philippe Gimenez, Alain Martin
PURPOSE: Practising a power-type activity over years can shape the neuromuscular profile of athletes. This study aimed at comparing the neuromuscular profile of a non-trained group (NT, n = 10) to power athletes practising Parkour (= traceurs, group PK, n = 11), an activity consisting of jumping obstacles mostly in an urban landscape. METHODS: Maximal isometric plantar flexion force (MVC) and rate of torque development (RTD) were evaluated, and neuromuscular function of triceps surae muscles was assessed and compared between groups through the analysis of evoked potentials from posterior tibial nerve stimulation...
April 20, 2018: European Journal of Applied Physiology
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