Search results for "GLASS"
showing 10 items of 1153 documents
Quantification of low levels of amorphous content in maltitol
2004
A method for the quantification of low levels of amorphous content of maltitol with hyper-DSC (high speed DSC) was developed. The method is based on the fact that the change of specific heat ( � Cp) at the glass transition is linearly proportional to the amorphous content. Twelve synthetic mixtures with various degrees of crystalline and amorphous maltitol were prepared. � Cp was determined at both fictive and
Confinement-induced polymorphism in acetylsalicylic acid–nanoporous glass composites
2018
We report on the experimental observation of confinement-induced new phase appearance in acetylsalicylic acid (ASA)–porous glass (PG) composites. In this study, ASA was embedded in PG host matrices of various pore widths (15–200 nm). The Raman spectra and positron annihilation lifetime measurements exhibit the existence of ASA nanocrystals in the PG matrix. The DSC data revealed that the melting temperature TM and excess specific heat decrease with decreasing the size of embedded ASA nanocrystals. The close inspection of the TM dependence versus diameter of filled pores has shown that the ASA crystallizes in polymorph II in confined matrix. Moreover, it was demonstrated that the ASA spatial…
Dielectric properties of (KBr)1-x (KCN)x
1982
The temperature dependence of the dielectric constant of (KBr)1−x (KCN) x was measured at frequencies of 87.5 Hz, 1, 10 and 100 kHz for concentrations ofx=0, 0.01, 0.04, 0.14, 0.25, and 0.50. Both the real and the imaginary part showed maxima at characteristic temperatures which depend on the measuring frequency and the concentration. The results are analogous to the behaviour of the magnetic susceptibility in spin glasses and support the existence of an orientational glass state.
The Azimuthal Dependence of Exchange Bias Effect and its Analysis by Spin Glass Model in Ni0.8Fe0.2/CoxNi1−xO Bilayers
2021
Exchange bias (EB) effect has been vigorously researched for many years due to its possible applications in information storage and spintronics, especially in spin valves for magnetic recording devices. Even though many models have been expounded to this day, they do not prove convincingly the origins of EB effect. We attempt to establish the azimuthal dependence of EB effect with respect to varying the composition of the antiferromagnet CoxNi $_{\mathrm {1-x}}\text{O}$ and temperature. In this report, we deposited the bilayer thin films of Ni0.8Fe0.2/Co x Ni1− x O with $x$ varying from 0.4 to 0.8 by magnetron sputtering and studied the variation of exchange bias field and coercivity. The E…
Aging as dynamics in configuration space
1999
The relaxation dynamics of many disordered systems, such as structural glasses, proteins, granular materials or spin glasses, is not completely frozen even at very low temperatures. This residual motion leads to a change of the properties of the material, a process commonly called aging. Despite recent advances in the theoretical description of such aging processes, the microscopic mechanisms leading to the aging dynamics are still a matter of dispute. In this Letter we investigate the aging dynamics of a simple glass former by means of molecular dynamics computer simulation. Using the concept of the inherent structure we give evidence that aging dynamics can be understood as a decrease of …
Magnetic properties of Cd–Mg–Tb quasicrystal
2004
Abstract The magnetic properties of an icosahedral Cd–Mg–Tb quasicrystal were studied by dc magnetization and thermoremanent magnetization time decay measurements. An unusual temperature dependence of the susceptibility below freezing temperature can be attributed to the inhomogeneous sample structure. In addition to the quasicrystalline portion which exhibits a spin-glass transition at 12.5 K a part of the sample behaves like a paramagnet. During aging of the sample in air the spin-glass part transforms into the paramagnetic one. The linear M ∝ H dependence of the thermoremanent magnetization time decay on magnetic field is quite different as compared to canonical spin glasses.
Biochips for cell biology by combined dip-pen nanolithography and DNA-directed protein immobilization.
2013
A general methodology for patterning of multiple protein ligands with lateral dimensions below those of single cells is described. It employs dip pen nanolithography (DPN) patterning of DNA oligonucleotides which are then used as capture strands for DNA-directed immobilization (DDI) of oligonucleotide-tagged proteins. This study reports the development and optimization of PEG-based liquid ink, used as carrier for the immobilization of alkylamino-labeled DNA oligomers on chemically activated glass surfaces. The resulting DNA arrays have typical spot sizes of 4-5 μm with a pitch of 12 μm micrometer. It is demonstrated that the arrays can be further functionalized with covalent DNA-streptavidi…
Glass fibre strength distribution determined by common experimental methods
2002
The tensile strength of brittle fibres is routinely described by the Weibull distribution. The parameters of the distribution can be obtained from tests on single fibres and fibre bundles or from model composite tests. However, there is growing evidence that the distribution parameters obtained by different experimental techniques differ systematically. In order to investigate the possible causes of such discrepancies, single-fibre tension, fibre bundle, and single-fibre fragmentation tests are employed in this study to obtain strength distribution of commercial E-glass fibres. The results reveal parameter dependence on the approach used to extract the distribution parameters from experimen…
Stable two -dimensional spatial solitons in heavy metal oxide glasses
2007
In this Communication, a stable self-confined propagation with ps near-infrared (NIR) pulses and over several Rayleigh lengths is demonstrated for the first time . Multiphoton absorption is shown to saturate the self-focusing response in a novel glass of the ternary system Nb2O5-O2-PbO (NPG) exhibiting a high refractive index (2-2.1) in the NIR and an energy gap of 3.52 eV. NPG belongs to the family of heavy metal oxides, widely studied for its fast and high nonlinearity in the infrared.
Mechanical properties of pultruded glass fiber-reinforced plastic after moistening
2012
Abstract The kinetics of moisture sorption under immersion in water at room and elevated temperatures and flexural characteristics of dry (conditionally initial) and wet (moistened up to saturation level) composite material were investigated on flat specimens of polyester based glass fiber-reinforced plastic, cut from I-beam pultruded profile. It was found that the coefficients of diffusion and swelling are different in three principal axis of the composite. The former have the largest value in fiber axis direction, but the latter – in transverse to fiber axis direction out of plane of the layers. The observed difference in kinetics of mass gain and change of volume strain for the specimens…