Search results for "CERAMICS"
showing 10 items of 1599 documents
Strength and Damage of Elementary Flax Fibers Extracted from Tow and Long Line Flax
2009
Flax fibers possess high specific strength and stiffness, and thus are competitive in terms of mechanical properties with traditional reinforcing fibers used in polymer-matrix composite materials. For environmental and economical benefit, it would be preferable to apply nontextile grade fibers in composites provided their mechanical characteristics are acceptable. Elementary fibers have been extracted from long line flax, used as high-quality raw material for textile industry, and flax tow, and their strength distribution and damage level determined. It is shown that the elementary flax fibers coming from short flax fiber are not inferior to those of textile-quality flax in terms of streng…
Structural reorganisation in polytopic receptors revealed by kinetic studies.
2010
One of the first kinetic studies of metal ion reorganisation between the different sites of a tritopic polyaza ligand reveals well defined pathways for the movement of the metal ion.
Thermal and light induced polymorphism in iron(II) spin crossover compounds.
2004
The spin crossover complexes {Fe[H2B(pz)2]2L} ([H2B(pz)2]2 = dihydrobis(pyrazolyl)borate, L = 2,2'-bipyridine (1), bipy and 1,10-phenanthroline, phen (2)) undergo both thermal and light induced spin crossover, but the structure of the low spin and light induced high spin states for 2 are different from that of the thermally induced high spin state and from those of 1. Real Cabezos, Jose Antonio, Jose.A.Real@uv.es
Monte Carlo studies of polymer interdiffusion and spinodal decomposition: A review
1991
Abstract Putting a layer of polymer A on top of a layer of polymer B, the broadening of the interfacial profile is observed in the framework of a lattice model (‘bond fluctuation method’). The interdiffusion constant is studied as a function of chain length, vacancy concentration, and interaction energy between unlike monomers, and a comparison with pertinent theoretical predictions is made. A lattice model where polymers are represented as self-avoiding walks on a simple cubic lattice is used to model ‘spinodal decomposition’, i.e. phase separation by ‘uphill diffusion’ in the unstable part of the phase diagram of a polymer mixture. For chain lengths N ≤ 32, the linearized Cahn-like theory…
Crystal structure determination of a new LaPO4 phase in a multicomponent glass ceramic via 3D electron diffraction
2022
Abstract A glass ceramic from the MgO–Al2O3–SiO2 system containing additives of ZrO2, TiO2, La2O3 and P2O5 was investigated. Via x-ray powder diffraction (XRPD) and Transmission electron microscopy(TEM) the crystalline phases present could be identified as MgAl2O4 (Spinel), orthorhombic ZrTiO4 and a polymorph of LaPO4 with a previously unknown crystal structure. The crystal structure of this LaPO4 phase was solved ab initio via 3D ED Data. The polymorph occurs in a distorted barite structure type in the same space group (P21/n) as the stable monazite type polymorph, however the density is higher and the La has a higher coordination number. Furthermore the LaPO4 is present in a spinodal reli…
Competitive Profiling of Ligandable Cysteines in Staphylococcus aureus with an Organogold Compound
2022
With the idea of exploiting metal-templated reactions to achieve selective modification of cysteines in proteins for antibacterial applications, an organometallic cyclometalated Au(III) compound was explored in a competitive chemoproteomic approach based on the isoDTB-ABPP (isotopically labelled desthiobiotin azide-activity-based protein profiling) technology in S. aureus cell extracts. In this way, more than 100 ligandable cysteines where identified, of which 10 were close to functional sites of proteins encoded by essential genes indicating potential for antibiotic development. Interestingly, more than 50% of the identified ligandable sites were not engaged by organic α-chloroacetamides i…
Application of the theory of naturally curved and twisted bars to designing Gorlov's helical turbine 1. System of governing equations
1998
The method of designing a new type of turbine used in flows of various kinds is discussed. Static, kinematic, and constitutive equations for transversely isotropic naturally curved and twisted bars are given, and the hypotheses used are discussed. The statement of the problem is linear and corresponds to small displacements. A method for solving the statically indeterminate problem is proposed. The objectives of numerical calculations, which will comprise the content of the second part of the investigation, are formulated.
Nonlinear response functions in an exponential trap model
2014
The nonlinear response to an oscillating field is calculated for a kinetic trap model with an exponential density of states and the results are compared to those for the model with a Gaussian density of states. The calculations are limited to the high temperature phase of the model. It is found that the results are qualitatively different only in a temperature range near the glass transition temperature $T_0$ of the exponential model. While for the Gaussian model the choice of the dynamical variable that couples to the field has no impact on the shape of the linear response, this is different for the exponential model. Here, it is found that also the relaxation time strongly depends on the …
Topologically Novel Multiple Rotaxanes and Catenanes Based on Tetraurea Calix[4]arenes
2006
Calix[4]arenes bearing at their wide rim four urea residues easily form hydrogen bonded dimeric capsules. This has been used to preorganise alkenyl functions attached to these urea groups for their controlled connection via metathesis reaction. Multimacrocyclic tetraurea derivatives are thus obtained in excellent yields via heterodimers which are formed exclusively with tetratosylurea derivatives. Heterodimerisation of such bis- and tetraloop tetraureas leads analogously to multicatenanes, or to rotaxanes by stoppering. Huge macrocycles are detached from tetraloop derivatives by cleavage of the urea function.
A heteropentanuclear oxalato-bridged [ReIV 4GdIII] complex: synthesis, crystal structure and magnetic properties
2012
The compound (NBu 4) 5[Gd III{Re IVBr 4(μ-ox)} 4(H 2O)]·H 2O (1), with intramolecular antiferromagnetic coupling, is the first Re(iv) system incorporating a 4f ion. © 2012 The Royal Society of Chemistry.