摘要 :
This paper describes aspects of the synthesis of cage complexes in relation to their prospects for use in biology. The means of attaching peptides, cholestane, paraffin tails and aromatic residues are outlined. Also, the propertie...
展开
This paper describes aspects of the synthesis of cage complexes in relation to their prospects for use in biology. The means of attaching peptides, cholestane, paraffin tails and aromatic residues are outlined. Also, the properties of some of these molecules, especially a new class 6f detergents, a new polymer able to capture metal ions, the selectivity of the cages for metal ions and the DNA intercalating properties of aromatic residues attached to the cages are discussed.
收起
摘要 :
Three possible routes to polynuclear transition metal complexes are discussed. The first route, oligomerization induced by desolvation of small cages, is exemplified by synthesis of a dodecanuclear cobalt cage, and by reactions wh...
展开
Three possible routes to polynuclear transition metal complexes are discussed. The first route, oligomerization induced by desolvation of small cages, is exemplified by synthesis of a dodecanuclear cobalt cage, and by reactions which give octa- and dode-canuclear chromium cages. The second route involves linking cages through organic spacers, and is illustrated by use of phthalate of link together cobalt and nickel cages. For the nickel case a complex consisting of four cubanes and a sodium octahedron is found. The third route involves the use of water to introduce hydroxide bridges into cages. One method of introducing water is to use hydrated metal salts; the trans-formation of a Cu_6Na cage into a Cu_(12)La_8 illustrates this approach. Alternatively, adventitious water within solvents can be used as a source, and this approach has led to a Co_(24) cage. The structures and magnetic properties of these various cages are discussed.
收起
摘要 :
In cryogenic environments, it is not possible to apply oil or grease to ball bearings, owing to the extreme temperature conditions. Thus, polytetrafluoroethylene (PTFE) cages are used as solid lubricants in such environments, beca...
展开
In cryogenic environments, it is not possible to apply oil or grease to ball bearings, owing to the extreme temperature conditions. Thus, polytetrafluoroethylene (PTFE) cages are used as solid lubricants in such environments, because PTFE has a low coefficient of friction. PTFE cages increase the rotational stability of the ball bearings by reducing the frictional force of the rolling elements. In addition, design parameters such as the cage guidance and ball-pocket clearances significantly affect the stability of the ball bearings. In this study, the dynamic behavior of a ball bearing cage submerged in a cryogenic fluid was investigated for different cage clearances and rotation speeds. For experimental verification, a test rig was designed to realize a cryogenic environment. The test rig could be driven to 11,000 rpm using a DC motor and provided loads of up to 20 kN using a pneumatic cylinder. A metal ring was employed to measure the cage whirling amplitude using a fiber optic displacement sensor. The parameters considered included the cage whirling amplitude, ball bearing torque, and cage wear. The effects of the clearances and rotation speed on the cage stability and performance were analyzed using the probability density function of the cage whirling frequency, and the standard deviation of this function decreased as the outer guidance clearance decreased. In addition, the cage wear loss increased with decreasing cage ball-pocket clearance, owing to the collisions between the balls and cage pocket. The experimental results agreed partially with the existing theory and demonstrated that the cage instability increased as the cage guidance clearance increased. (C) 2018 Elsevier Ltd. All rights reserved.
收起
摘要 :
Cage rotating and whirling inside rolling bearings involve conical motion and easily lead to excessive wear if the cage exists unexpected unbalances. In this study, the cage motions affected by its unbalance in a ball bearing are ...
展开
Cage rotating and whirling inside rolling bearings involve conical motion and easily lead to excessive wear if the cage exists unexpected unbalances. In this study, the cage motions affected by its unbalance in a ball bearing are investigated analytically and experimentally, which helps to understand the bearing dynamics and cage wear. Firstly, a dynamic model of angular contact ball bearing with the unbalanced cage is established to simulate the cage motions as a function of typical cage unbalances over a range of operating speeds. Then, an experimental approach is proposed to measure the spatial motions of the cage with various prescriptive unbalances on a test rig. Finally, the trajectories, waveforms, and spectra of cage motions are constructed and compared to elucidate its diversified patterns under various cage unbalances. The experimental observations of the cage motions agree well with the theoretical predictions and reveal that the whirl motions of cage are evidently affected by its unbalances. The increment of cage unbalance mass makes the trajectories of cage center more regular and enlarges the whirl radii. It is also observed that the amplitudes of the axial and radial motions of the cage, particularly corresponding cage rotating frequency and the wear extent of the cage guiding surface increase with the increment of cage unbalance.
收起
摘要 :
The survey summarizes modern methods of synthesis and reactivity of tetracoordinated phosphorus cage compounds containing one or more endocyclic P-C bonds (phosphine oxides, phosphinates and phosphonates, phosphatripticenes and ot...
展开
The survey summarizes modern methods of synthesis and reactivity of tetracoordinated phosphorus cage compounds containing one or more endocyclic P-C bonds (phosphine oxides, phosphinates and phosphonates, phosphatripticenes and others). Intramolecular cyclization reactions including electrophilic aromatic substitution with unsaturated organophosphorus compounds, reactions of P-H-derivatives with carbonyl compounds as well as cycloaddition reactions involving I-IV-coordinated phosphorus derivatives are considered.
收起
摘要 :
The girth pair of a graph gives the length of a shortest odd and a shortest even cycle. The existence of regular graphs with given degree and girth pair was proved by Harary and Kovacs [Regular graphs with given girth pair, J Grap...
展开
The girth pair of a graph gives the length of a shortest odd and a shortest even cycle. The existence of regular graphs with given degree and girth pair was proved by Harary and Kovacs [Regular graphs with given girth pair, J Graph Theory 7 (1983), 209-218]. A (delta, g)-cage is a smallest delta-regular graph with girth g. For all delta >= 3 and odd girth g >= 5, Harary and Kovbcs conjectured the existence of a (delta, g)-cage that contains a cycle of length g + 1. In the main theorem of this article we present a lower bound on the order of a delta-regular graph with odd girth g >= 5 and even girth h >= g + 3. We use this bound to show that every (delta, g)-cage with delta >= 3 and g is an element of {5, 7} contains a cycle of length g + 1, a result that can be seen as an extension of the aforementioned conjecture by Harary and Kovacs for these values of delta, g. Moreover, for every odd g >= 5, we prove that the even girth of all (delta, g)-cages with delta large enough is at most (3g - 3)/2. (c) 2007 Wiley Periodicals, Inc.
收起
摘要 :
To compare the clinical outcomes, radiographic results and fusion rate of ACDF between empty PEEK cages and PEEK cages packed with beta-tricalcium phosphate.
摘要 :
A numerical model is developed to calculate the mooring forces and cage volumes for a gravity cage system. The collar, nets, bottom ring and mooring system are all modelled by line elements due to the slender structure. The effect...
展开
A numerical model is developed to calculate the mooring forces and cage volumes for a gravity cage system. The collar, nets, bottom ring and mooring system are all modelled by line elements due to the slender structure. The effect of structural parameters on the cage capacity and mooring forces is evaluated in a sensitivity analysis, to provide knowledge in the design phase of a fish cage. Heaver sinkers and nets with smaller solidity are preferred to prevent the volume reduction of fish cages but they lead to a larger mooring force or an increase in the probability of fish escaping. Linear wave theory is applied. Short waves increase the mean value of the mooring force and higher waves result in a larger amplitude of the mooring force. It is also found that short waves can change the shape of the nets while the shape of the cage subjected to long waves almost keeps constant as the one under uniform flow, which obtains a good agreement as previous experiments.
收起
摘要 :
Following the experimental discovery of several nearly symmetric protein cages, we define the concept of homogeneous symmetric congruent equivalent near-miss polyhedral cages made out of P-gons. We use group theory to parameterize...
展开
Following the experimental discovery of several nearly symmetric protein cages, we define the concept of homogeneous symmetric congruent equivalent near-miss polyhedral cages made out of P-gons. We use group theory to parameterize the possible configurations and we minimize the irregularity of the P-gons numerically to construct all such polyhedral cages for P = 6 to P = 20 with deformation of up to 10%.
收起
摘要 :
In 21st century water resource will be at premium with water shortage expected after 2015, with such a pressure on this vital resource for aquaculture business as usual scenarios will no longer be possible. In this aspect there is...
展开
In 21st century water resource will be at premium with water shortage expected after 2015, with such a pressure on this vital resource for aquaculture business as usual scenarios will no longer be possible. In this aspect there is need of water basedaquaculture system like cages, pens (inshore, offshore). The cage aquaculture sector has grown very rapidly during the past 20 years and is presently undergoing rapid changes in response to pressures from globalization and growing demand for aquatic products in both developing and developed countries. It has been predicted that fish consumption in developing countries will increase by 57 percent, from 62.7 million metric tons in 1997 to 98.6 million in 2020. Presently there are only wooden, steel, galvanised iron, and HDPE made cages in India, From past years there was an increase in novel technologies for cages in other countries but not in India, for more development there is an need of futuristic cages like closed cage from Aquafarm equipment's(As),ocean drifter IMTA, Aquapod pens, single point mooring cages etc., should be developed for future aquaculture development.
收起
原文获取