961 resultados para Bow and arrow.
Resumo:
In this paper, the reaction and structure of the complexes of alkaline earth metal (Ca, Sr, Ba) with 2-(4'-chloro-2'-phosphonazo)-7-(2', 6'-dibromo-4'-chlorophenylazo 1, 8-dihydroxy-3, 6-naphthalene disulfonic acid (Chlorophosphonazo-DBC) have been studied. This ligand has eight forms under different acidity. The protonation reactions take place at [H+] > 0.36 mol.dm-3. The ligand begins dissociations at pH > 0.5. Two protons are released in the complexes formation reactions(Me2+ + 2HI half-arrow-pointing-left and half-arrow-pointing-right MeL2 + 2H+). The stability constants of the complexes of Calcium, Strontium and Barium have been determined by Yoe-Jone method, Majumder-Chakrabartty method and calculation method. The order of the stability of complexes is as follows: Sr > Ba > Ca. The structure of the complexes have also been studied by infrared spectroscopy, Laser Raman spectroscopy, NMR, and EPR. The results show that these groups of N = N, PO3H2 and OH are active groups in the complex reactions. The structure of the complexes of Strontium, Barium and Calcium with chlorophosphonazo-DBC are represented and the reaction and the complex bonds are discussed in this paper.
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A novel miniaturised system for measurement of the in-flight characteristics of an arrow is introduced in this paper. The system allows the user to measure in-flight parameters such as the arrow’s speed, kinetic energy and momentum, arrow drag and vibrations of the arrow shaft. The system consists of electronics, namely a three axis accelerometer, shock switch, microcontroller and EEPROM memory embedded in the arrow tip. The system also includes a docking station for download and processing of in-flight ballistic data from the tip to provide the measured values. With this system, a user can evaluate and optimize their archery equipment setup based on measured ballistic values. Recent test results taken at NIST show the accuracy of the launch velocities to be within +/- 0.59%, when compared with NIST’s most accurate ballistic chronograph.
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In the early 19th century the requirement for clear span industrial buildings brought about the development of a variety of timber truss types. The Belfast truss was introduced circa 1860 to meet the demand for efficient wide span industrial buildings. It has essentially a bow-string configuration with a curved top chord, straight horizontal bottom chord and close-spaced lattice web. Several thousand still exist in Ireland, many in buildings of historic significance. This paper sets out to demonstrate the efficiency of the Belfast truss and to show that, by modern structural design criteria, the concept, member sizes and joint details were well chosen. Trusses in historic buildings can be replicated almost exactly as originally fabricated. Results of a theoretical study are compared with the experimental behaviour of two full-scale trusses: one a replacement truss, tested in the laboratory; the other an 80-year-old truss tested on site. In addition, experimental results from a manufacturers archive material of full-scale truss tests carried out about 100 years ago are compared with theoretical models. As well as considering their significance in building conservation the paper proposes that Belfast trusses are an attractive sustainable alternative to other roof structures. The analysis, design, fabrication and testing of trusses have resulted in a better understanding of their behaviour which is not only of historic interest and fundamental to the repair/restoration of existing trusses, but also relevant to the design of modern timber trusses and the promotion of a sustainable form of roof construction.
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175 nm-thick Ba0.5Sr0.5TiO3 (BST) thin film fabricated by pulsed laser deposition (PLD) technique is found to be a mixture of two distributions of material. We discuss whether these two components are nano-regions of paraelectric and ferroelectric phases, or a bimodal grain-size distribution, or an effect of oxygen vacancy gradient from the electrode interface. The fraction of switchable ferroelectric phase decreases under bipolar pulsed fields, but it recovers after removal of the external fields. The plot of capacitance in decreasing dc voltage (C(Vdown arrow) versus that in increasing dc 61 voltage C(Vup arrow) is a superposition of overlapping of two triangles, in contrast to one well-defined triangle for typical ferroelectric SrBi2Ta2O9 thin films.
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Voltammetric studies of PCl3 and POCl3 have not been reported in the literature to date, probably due to the instability of these molecules in conventional aprotic solvents giving unstable and irreproducible results. From a previous study [Amigues et al. Chem. Commun. 2005, 1-4], it was found that ionic liquids have the ability to offer a uniquely stable solution phase environment for the study of these phosphorus compounds. Consequently, the electrochemistry of PCl3 and POCl3 has been studied by cyclic voltammetry on a gold microelectrode in the ionic liquid [C(4)mpyrr][N(Tf)(2)] (1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide). For both compounds, reduction and oxidation waves were observed and a tentative assignment of the waves is given. For PCl3, the reduction was thought to proceed via the following mechanism: PCl3 + e(-) h reversible arrow PCl3-, PCl3- reversible arrow Cl- + (PCl2)-Cl-center dot, (and) Cl- + PCl3 h PCl4-. For POCl3, the suggested reduction mechanism was analogous to that of PCl3: POCl3 + e(-) reversible arrow POCl3-, POCl3- reversible arrow Cl- + (POCl2)-O-center dot, and Cl- + POCl3 h POCl4-. In both cases (PCl2)-Cl-center dot and (POCl2)-O-center dot are likely to engage in further reactions. Potential step microdisk chronoamperometry was carried out on the reductive waves of PCl3 and POCl3 to measure diffusion coefficients and number of electrons transferred. It was found that the diffusion of PCl3 was unusually slow (3.1 x 10(-12) m(2) s(-1)): approximately 1 order of magnitude less than that for POCl3 (2.2 x 10(-11) m(2) s(-1)). For both PCl3 and POCl3, a
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We extend the contingent valuation (CV) method to test three differing conceptions of individuals' preferences as either (i) a-priori well-formed or readily divined and revealed through a single dichotomous choice question (as per the NOAA CV guidelines [K. Arrow, R. Solow, P.R. Portney, E.E. Learner, R. Radner, H. Schuman, Report of the NOAA panel on contingent valuation, Fed. Reg. 58 (1993) 4601-4614]); (ii) learned or 'discovered' through a process of repetition and experience [J.A. List, Does market experience eliminate market anomalies? Q. J. Econ. (2003) 41-72; C.R. Plott, Rational individual behaviour in markets and social choice processes: the discovered preference hypothesis, in: K. Arrow, E. Colombatto, M. Perleman, C. Schmidt (Eds.), Rational Foundations of Economic Behaviour, Macmillan, London, St. Martin's, New York, 1996, pp. 225-250]; (iii) internally coherent but strongly influenced by some initial arbitrary anchor [D. Ariely, G. Loewenstein, D. Prelec, 'Coherent arbitrariness': stable demand curves without stable preferences, Q. J. Econ. 118(l) (2003) 73-105]. Findings reject both the first and last of these conceptions in favour of a model in which preferences converge towards standard expectations through a process of repetition and learning. In doing so, we show that such a 'learning design CV method overturns the 'stylised facts' of bias and anchoring within the double bound dichotomous choice elicitation format. (C) 2007 Elsevier Inc. All rights reserved.
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The aim of this study was to determine bow nutrient intake is affected by a short-term phytoestrogen-rich diet. Ten healthy volunteers consumed 100 g soya chunks, 150 g lentils, and 250 g kidney beans daily for 3 days. Urine was collected during the 2 days before, 3 intervention days, and 2 days after the intervention and analyzed for phytoestrogen status. Subjects filled in food diaries throughout the study period. Urinary daidzein, but not equol and enterolactone, levels increased during the 7-day period. There was no change in energy, protein, sugar, or total fat intake, but an increase in carbohydrate, fiber, and starch intake. There was a change in the distribution of fat intake with a fall in saturated fat and cholesterol intake. Iron intake significantly increased, although vitamin B-12 fell significantly. The long-term effects of this diet and the associated health benefits of these changes require further study. (C) 2006 Elsevier Inc. All rights reserved.
Structural and kinetic studies of spin crossover in an Iron(II) complex with a novel tripodal ligand
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Configurational and ligand conformational influences on the kinetics of (1)A(1) reversible arrow T-5(2) spin crossover in the Fe(II) complex with the novel tripodal ligand, 1,1,1-tris((N-(2-pyridylmethyl)-N-methylamino)methyl)ethane (tptMetame), have been explored. Despite having six chelate rings and three chiral nitrogen atoms, only one enantiomeric pair of isomers, Delta, SSS, and Lambda, RRR, of the complex ion is observed. The conformation of the three rings forming the upper ''cap'' of the complex structure can be assigned delta or lambda with respect to the 3-fold molecular axis. X-ray data at 300 and 153 K, above and below the critical temperature for the spin transition, show that the conformation of the ligand ''cap'' is the same as the absolute configuration of the complex, with the same Lambda lambda(CAP)(or Delta delta(CAP)) combination prevailing for both the LS ((1)A(1)) and HS (T-5(2)) isomers. Molecular mechanics calculations further show that the ligand energy remains lowest for this Lambda lambda(CAP) (or Delta delta(CAP)) combination at all Fe-N distances over the range spanning the LS and HS isomers. Measurements of the spin crossover relaxation time have been carried out in solution over the temperature range 293-170 K. The observed monophasic relaxation traces are also consistent with the absolute configuration of the complex remaining unaltered during the spin crossover.
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We propose a new mechanism of high-order harmonic generation during an interaction of a high-intensity laser pulse with underdense plasma. A tightly focused laser pulse creates a cavity in plasma pushing electrons aside and exciting the wake wave and the bow wave. At the joint of the cavity wall and the bow wave boundary, an annular spike of electron density is formed. This spike surrounds the cavity and moves together with the laser pulse. Collective motion of electrons in the spike driven by the laser field generates high-order harmonics. A strong localization of the electron spike, its robustness to oscillations imposed by the laser field and, consequently, its ability to produce high-order harmonics is explained by catastrophe theory. The proposed mechanism explains the experimental observations of high-order harmonics with the 9 TW J-KAREN laser (JAEA, Japan) and the 120 TW Astra Gemini laser (CLF RAL, UK) [A. S. Pirozhkov, et al., arXiv:1004.4514 (2010); A. S. Pirozhkov et al, AIP Proceedings, this volume]. The theory is corroborated by high-resolution two- and three-dimensional particle-in-cell simulations.
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Cathepsin L proteases secreted by the helminth pathogen Fasciola hepatica have functions in parasite virulence including tissue invasion and suppression of host immune responses. Using proteomics methods alongside phylogenetic studies we characterized the profile of cathepsin L proteases secreted by adult F. hepatica and hence identified those involved in host-pathogen interaction. Phylogenetic analyses showed that the Fasciola cathepsin L gene family expanded by a series of gene duplications followed by divergence that gave rise to three clades associated with mature adult worms (Clades 1, 2, and 5) and two clades specific to infective juvenile stages (Clades 3 and 4). Consistent with these observations our proteomics studies identified representatives from Clades 1, 2, and 5 but not from Clades 3 and 4 in adult F. hepatica secretory products. Clades 1 and 2 account for 67.39 and 27.63% of total secreted cathepsin Ls, respectively, suggesting that their expansion was positively driven and that these proteases are most critical for parasite survival and adaptation. Sequence comparison studies revealed that the expansion of cathepsin Ls by gene duplication was followed by residue changes in the S2 pocket of the active site. Our biochemical studies showed that these changes result in alterations in substrate binding and suggested that the divergence of the cathepsin L family produced a repertoire of enzymes with overlapping and complementary substrate specificities that could cleave host macromolecules more efficiently. Although the cathepsin Ls are produced as zymogens containing a prosegment and mature domain, all secreted enzymes identified by MS were processed to mature active enzymes. The prosegment region was highly conserved between the clades except at the boundary of prosegment and mature enzyme. Despite the lack of conservation at this section, sites for exogenous cleavage by asparaginyl endopeptidases and a Leu-Ser[downward arrow]His motif for autocatalytic cleavage by cathepsin Ls were preserved.
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In today’s rapidly developing digital age and increasingly socially-aware society, the notion of media accessibility is evolving in response to shifting audience expectations. Performing arts and media, such as opera, are called upon to include all audiences, and related audiovisual translation methods are progressing in this direction. These comprise audio description and touch tours for the blind and partially-sighted, two relatively new translation modalities which are consumer-oriented and require an original research design for the analysis of the translation processes involved. This research design follows two fundamental principles: (1) audience reception studies should be an integral part of the investigation into the translation process; and (2) the translation process is regarded as a network. Therefore, this chapter explores the unique translation processes of audio description and touch tours within the context of live opera from the perspective of actor-network theory and by providing an overview of a reception project. Through discussion of the methodology and findings, this chapter addresses the question of the impact of audience reception on the translation process.
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We study the magnetospheric structure and the ionospheric Joule Heating of planets orbiting M-dwarf stars in the habitable zone using a set of magnetohydrodynamic models. The stellar wind solution is used to drive a model for the planetary magnetosphere, which is coupled with a model for the planetary ionosphere. Our simulations reveal that the space environment around close-in habitable planets is extreme, and the stellar wind plasma conditions change from sub- to super-Alfvénic along the planetary orbit. As a result, the magnetospheric structure changes dramatically with a bow shock forming in the super-Alfvénic sectors, while no bow shock forms in the sub-Alfvénic sectors. The planets reside most of the time in the sub-Alfvénic sectors with poor atmospheric protection. A significant amount of Joule Heating is provided at the top of the atmosphere as a result of the intense stellar wind. For the steady-state solution, the heating is about 0.1%-3% of the total incoming stellar irradiation, and it is enhanced by 50% for the time-dependent case. The significant Joule Heating obtained here should be considered in models for the atmospheres of habitable planets in terms of the thickness of the atmosphere, the top-side temperature and density, the boundary conditions for the atmospheric pressure, and particle radiation and transport. Here we assume constant ionospheric Pedersen conductance similar to that of the Earth. The conductance could be greater due to the intense EUV radiation leading to smaller heating rates. We plan to quantify the ionospheric conductance in future study.