Laser-heated pedestal growth (LHPG) or laser floating zone (LFZ) is a crystal growth technique. A narrow region of a crystal is melted with a powerful CO2 or YAG laser. The laser and hence the floating zone, is moved along the crystal. The molten region melts impure solid at its forward edge and leaves a wake of purer material solidified behind it. This technique for growing crystals from the melt (liquid/solid phase transition) is used in materials research.[1][2]
https://en.wikipedia.org/wiki/Laser-heated_pedestal_growth
In statistical physics and mathematics, percolation theory describes the behavior of a network when nodes or links are added. This is a geometric type of phase transition, since at a critical fraction of addition the network of small, disconnected clusters merge into significantly larger connected, so-called spanning cluster. The applications of percolation theory to materials science and in many other disciplines are discussed here and in the articles network theory and percolation.
https://en.wikipedia.org/wiki/Percolation_theory
The micro-pulling-down (μ-PD) method is a crystal growth technique based on continuous transport of the melted substance through micro-channel(s) made in a crucible bottom. Continuous solidification of the melt is progressed on a liquid/solid interface positioned under the crucible. In a steady state, both the melt and the crystal are pulled-down with a constant (but generally different) velocity.
Many different types of crystal are grown by this technique, including Y3Al5O12, Si, Si-Ge, LiNbO3, α-Al2O3, Y2O3, Sc2O3, LiF, CaF2, BaF2, etc.[1][2]
https://en.wikipedia.org/wiki/Micro-pulling-down
Allotropy or allotropism (from Ancient Greek ἄλλος (allos) 'other', and τρόπος (tropos) 'manner, form') is the property of some chemical elements to exist in two or more different forms, in the same physical state, known as allotropes of the elements. Allotropes are different structural modifications of an element;[1] the atoms of the element are bonded together in a different manner. For example, the allotropes of carbon include diamond (the carbon atoms are bonded together in a tetrahedral lattice arrangement), graphite (the carbon atoms are bonded together in sheets of a hexagonal lattice), graphene(single sheets of graphite), and fullerenes (the carbon atoms are bonded together in spherical, tubular, or ellipsoidal formations).
The term allotropy is used for elements only, not for compounds. The more general term, used for any compound, is polymorphism, although its use is usually restricted to solid materials such as crystals. Allotropy refers only to different forms of an element within the same physical phase (the state of matter, such as a solid, liquid or gas). The differences between these states of matter would not alone constitute examples of allotropy. Allotropes of chemical elements are frequently referred to as polymorphs or as phases of the element.
For some elements, allotropes have different molecular formulae or different crystalline structures, as well as a difference in physical phase; for example, two allotropes of oxygen (dioxygen, O2, and ozone, O3) can both exist in the solid, liquid and gaseous states. Other elements do not maintain distinct allotropes in different physical phases; for example, phosphorus has numerous solid allotropes, which all revert to the same P4 form when melted to the liquid state.
https://en.wikipedia.org/wiki/Allotropy
Ehrenfest equations (named after Paul Ehrenfest) are equations which describe changes in specific heat capacity and derivatives of specific volume in second-order phase transitions. The Clausius–Clapeyron relation does not make sense for second-order phase transitions,[1] as both specific entropy and specific volume do not change in second-order phase transitions.
https://en.wikipedia.org/wiki/Ehrenfest_equations
Electron paramagnetic resonance (EPR) or electron spin resonance (ESR) spectroscopy is a method for studying materials with unpaired electrons. The basic concepts of EPR are analogous to those of nuclear magnetic resonance (NMR), but the spins excited are those of the electrons instead of the atomic nuclei. EPR spectroscopy is particularly useful for studying metal complexes and organic radicals. EPR was first observed in Kazan State University by Sovietphysicist Yevgeny Zavoisky in 1944,[1][2] and was developed independently at the same time by Brebis Bleaney at the University of Oxford.
https://en.wikipedia.org/wiki/Electron_paramagnetic_resonance
Electron spin resonance dating, or ESR dating, is a technique used to date newly formed materials which radiocarbon dating cannot, like carbonates, tooth enamel, or materials that have been previously heated like igneous rock. Electron spin resonance dating was first introduced to the science community in 1975, when Japanese nuclear physicist Motoji Ikeya dated a speleothem in Akiyoshi Cave, Japan.[1] ESR dating measures the amount of unpaired electrons in crystalline structures that were previously exposed to natural radiation. The age of substance can be determined by measuring the dosage of radiation since the time of its formation.[2]
https://en.wikipedia.org/wiki/Electron_spin_resonance_dating
A spin label (SL) is an organic molecule which possesses an unpaired electron, usually on a nitrogen atom, and the ability to bind to another molecule. Spin labels are normally used as tools for probing proteins or biological membrane-local dynamics using electron paramagnetic resonance spectroscopy. The site-directed spin labeling(SDSL) technique allows one to monitor a specific region within a protein. In protein structure examinations, amino acid-specific SLs can be used.
The goal of spin labeling is somewhat similar to that of isotopic substitution in NMR spectroscopy. There one replaces an atom lacking a nuclear spin (and so is NMR-silent) with an isotope having a spin I 0 (and so is NMR-active). This technique is useful for tracking the chemical environment around an atom when full substitution with an NMR-active isotope is not feasible. Recently, spin-labelling has also been used to probe chemical local environment in NMR itself, in a technique known as Paramagnetic Relaxation Enhancement (PRE).
Recent developments in the theory and experimental measurement of PREs have enabled the detection, characterization and visualization of sparsely populated states of proteins and their complexes.[1] Such states, which are invisible to conventional biophysical and structural techniques, play a key role in many biological processes including molecular recognition, allostery, macromolecular assembly and aggregation.
https://en.wikipedia.org/wiki/Spin_label
In polymer physics, the coil–globule transition is the collapse of a macromolecule from an expanded coil state through an ideal coil state to a collapsed globule state, or vice versa. The coil–globule transition is of importance in biology due to the presence of coil-globule transitions in biological macromolecules such as proteins[1] and DNA.[2] It is also analogous with the swelling behavior of a crosslinked polymer gel and is thus of interest in biomedical engineering for controlled drug delivery. A particularly prominent example of a polymer possessing a coil-globule transition of interest in this area is that of Poly(N-isopropylacrylamide)(PNIPAAm).[3]
Description[edit]
In its coil state, the radius of gyration of the macromolecule scales as its chain length to the three-fifths power. As it passes through the coil–globule transition, it shifts to scaling as chain length to the half power (at the transition) and finally to the one third power in the collapsed state.[4] The direction of the transition is often specified by the constructions 'coil-to-globule' or 'globule-to-coil' transition.
https://en.wikipedia.org/wiki/Coil–globule_transition
In chemistry and biology a cross-link is a bond or a short sequence of bonds that links one polymer chain to another. These links may take the form of covalent bonds or ionic bonds and the polymers can be either synthetic polymers or natural polymers (such as proteins).
In polymer chemistry "cross-linking" usually refers to the use of cross-links to promote a change in the polymers' physical properties.
When "crosslinking" is used in the biological field, it refers to the use of a probe to link proteins together to check for protein–protein interactions, as well as other creative cross-linking methodologies.[not verified in body]
Although the term is used to refer to the "linking of polymer chains" for both sciences, the extent of crosslinking and specificities of the crosslinking agents vary greatly. As with all science, there are overlaps, and the following delineations are a starting point to understanding the subtleties.
https://en.wikipedia.org/wiki/Cross-link
States of matter are distinguished by changes in the properties of matter associated with external factors like pressure and temperature. States are usually distinguished by a discontinuity in one of those properties—for example, raising the temperature of ice produces a discontinuity at 0°C (32°F) as energy goes into a phase transition, rather than an increase in temperature. The four classical states of matter are usually summarized as solid, liquid, gas, and plasma. In the 20th century however, increased understanding of the more exotic properties of matter resulted in the identification of many additional states of matter, none of which are observed in normal conditions.
https://en.wikipedia.org/wiki/List_of_states_of_matter
A hydrogen turboexpander-generator or generator loaded expander for hydrogen gas is an axial flow turbine or radial expander for energy recoverythrough which a high pressure hydrogen gas is expanded to produce work that is used to drive an electrical generator. It replaces the control valve or regulator where the pressure drops to the appropriate pressure for the low pressure network. A turboexpander-generator can help recover energy losses and offset electrical requirements and CO2 emissions.[1]
https://en.wikipedia.org/wiki/Hydrogen_turboexpander-generator
The perturbed γ-γ angular correlation, PAC for short or PAC-Spectroscopy, is a method of nuclear solid-state physics with which magnetic and electric fields in crystal structures can be measured. In doing so, electrical field gradients and the Larmor frequency in magnetic fields as well as dynamic effects are determined. With this very sensitive method, which requires only about 10-1000 billion atoms of a radioactive isotope per measurement, material properties in the local structure, phase transitions, magnetism and diffusion can be investigated. The PAC method is related to nuclear magnetic resonance and the Mössbauer effect, but shows no signal attenuation at very high temperatures. Today only the time-differential perturbed angular correlation (TDPAC) is used.
https://en.wikipedia.org/wiki/Perturbed_angular_correlation
https://en.wikipedia.org/wiki/Ferromagnetic_resonance
https://en.wikipedia.org/wiki/Irreducible_representation
https://en.wikipedia.org/wiki/Symmetric_matrix
https://en.wikipedia.org/wiki/Quadrupole
https://en.wikipedia.org/wiki/Perturbed_angular_correlation
https://en.wikipedia.org/wiki/Kronecker_delta
https://en.wikipedia.org/wiki/Gunn_diode
https://en.wikipedia.org/wiki/Circulator
Angle Correction
https://en.wikipedia.org/wiki/Power_factor
https://en.wikipedia.org/wiki/Gamma_correction
https://en.wikipedia.org/wiki/Prism_correction
https://en.wikipedia.org/wiki/Slip_angle
https://en.wikipedia.org/wiki/Volume_correction_factor
https://en.wikipedia.org/wiki/1_in_60_rule
https://en.wikipedia.org/wiki/Stripline
https://en.wikipedia.org/wiki/Varicap
https://en.wikipedia.org/wiki/Negative_resistance#Reflection_amplifier
https://en.wikipedia.org/wiki/Isolator_(microwave)
https://en.wikipedia.org/wiki/Negative_resistance
https://en.wikipedia.org/wiki/Tunnel_diode
https://en.wikipedia.org/wiki/Negative_mass
https://en.wikipedia.org/wiki/Scattering_parameters
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