Beta transition

Garbarczyk, J. (1985). A study on the mechanism of polymorphic transition beta-alpha in isotactic polypropylene. Makromol Chem., Vol. 186, Issue 10, pp.2145-2151. 

Transition Beta Transus. At atmospheric pressure, tita-... 

There are some phase transitions that do not fall either into the first-order or second-order category. These include paramagnetic-to-ferromagnetic transitions in some magnetic materials and a type of transition that occurs in certain solid metal alloys that is called an order-disorder transition. Beta brass, which is a nearly equimolar mixture of copper and zinc, has a low-temperature equilibrium state in which every copper atom in the crystal lattice is located at the center of a cubic unit cell, surrounded by eight zinc atoms at the corners of the cell. At 742 K, an order-disorder transition occurs from the ordered low-temperature state to a disordered high-temperature state in which the atoms are randomly mixed in a single crystal lattice. The phase transition between normal liquid helium and liquid helium II was once said to be a second-order transition. Later experiments indicated that the heat capacity of liquid helium appears to approach infinity at the transition, so that the transition is not second... 

The heat capacity of a body is the amount of heat required to produce a temperature rise of 1°C. Specific heat is the heat capacity per unit mass, and generally decreases with lowering temperature, falling to zero at 0°K. Anomalies in the specific heat curve can be related to the molecular origins of phase transitions. Beta brass, for instance, exhibits a lambda point at 470°C due to an order-disorder transition. The specific heat anomaly is referred to as a lambda point because of the resemblance to the Greek letter A. 

Thermodynamic equation of state Boltzmann constant Affine deformation Gaussian distribution Phantom chain approximation Phantom model Constrained fluctuation model Slip-link model Nonaffine slip tube model Mooney-Rivlin equation Visoelasticity of elastomers Alpha transition Beta transition Gamma transition Storage modulus... 

Phosphorus exists in four or more allotropic forms white (or yellow), red, and black (or violet). Ordinary phosphorus is a waxy white solid when pure it is colorless and transparent. White phosphorus has two modifications alpha and beta with a transition temperature at -3.8oC. 

Similarly, emits seven helium nuclei and 4 beta particles during its transition through several other elements, until Pb is reached and Th starts the successive elimination of six helium nuclei and 4 beta particles, which leads to Pb. 

The thermal transitions of the manganese dioxides can be iUustrated by the beta phase which undergoes successive reductions and corresponding loss of oxygen as the temperature is increased (49). 

IT = isomeric transition, EC = electron capture, l3 = positron emission, and j3 = beta decay. 

Alzheimer s Disease. Figure 1 A(3 monomers can self-associate to form dimers, trimers and higher oligomers. Globular structures of synthetic A(342 are known as A(3-derived diffusible ligands (ADDLs) (3-12-mers of A(3). These structures are similar to the smallest protofibrils and represent the earliest macromolecular assembly of synthetic A(3. The characteristic amyloid fiber exhibits a high beta-sheet content and is derived in vitro by a nucleation-dependent self-association and an associated conformational transition from random to beta-sheet conformation of the A(3 molecule. Intermediate protofibrils in turn self-associate to form mature fibers. 

Tinplate and Solder. Metallurgical studies were performed to determine the effect of irradiation at low temperature on the corrosion resistance of tinplate and on the mechanical properties and microstructure of tinplate and side-seam solder of the tinplate container. The area of major interest was the effect of low-temperature irradiation on the possible conversion of the tin from the beta form to the alpha form. In the case of pure tin, the transition occurs at 18 °C. It was feared that low-temperature irradiation would create dislocations in the crystal lattice of tin and enhance the conversion of tin from the silvery form to a powdery form rendering the tin coating ineffective in protecting the base steel. Tin used for industrial consumption contains trace amounts of soluble impurities of lead and antimony to retard this conversion for several years. 

The metallurgical experiments showed that the beta-alpha transition of the tin coating did not occur at irradiation doses of 3-5 Mrad and 6-7.5 Mrad at 5, —30, and —90°C and that the tensile properties, impact ductility, peel strength of soldered lap joints, and microstructure of commercial tinplate and solder were not affected by the irradiation conditions that are used in the sterilization of meat products. 

Soto C, Castano EM, Frangione B, Inestrosa NC. The alpha-helica to beta-strand transition in the amino-terminal fragment of the amyloid beta-peptide modulates amyloid formation. J Biol Chem 1995 270 3063-3067. 

The effect of crystal size of these zeolites on the resulted toluene conversion can be ruled out as the crystal sizes are rather comparable, which is particularly valid for ZSM-5 vs. SSZ-35 and Beta vs. SSZ-33. The concentrations of aluminum in the framework of ZSM-5 and SSZ-35 are comparable, Si/Al = 37.5 and 39, respectively. However, the differences in toluene conversion after 15 min of time-on-stream (T-O-S) are considerable being 25 and 48.5 %, respectively. On the other hand, SSZ-35 exhibits a substantially higher concentration of strong Lewis acid sites, which can promote a higher rate of the disproportionation reaction. Two mechanisms of xylene isomerization were proposed on the literature [8] and especially the bimolecular one involving the formation of biphenyl methane intermediate was considered to operate in ZSM-5 zeolites. Molecular modeling provided the evidence that the bimolecular transition state of toluene disproportionation reaction fits in the channel intersections of ZSM-5. With respect to that formation of this transition state should be severely limited in one-dimensional (1-D) channel system of medium pore zeolites. This is in contrast to the results obtained as SSZ-35 with 1-D channels system exhibits a substantially higher... 

In this work the methanol and methyl iodide conversion and their co-reaction are investigated on Fe-Beta zeolite without any oxygen. Partly Fe-ion-exchanged Beta-300 i.e. Fe-H-Beta-300 (shortly Fe-Beta-300) zeolite keeps the light acidity to a certain extent, however the presence of Fe ions (as transition metal, Fe is an excellent Lewis acid) can modify the reaction pathway. This Fe-Beta-300 has been tested already by low temperature peat pyrolysis [6], At present, the adsorption as well as desorption of methanol are followed-up by radiodetectors using ( -radioisotopic labeling [4, 7]. The... 

Although the loss of beta hydrogens should decrease the stability of a carbonium ion or its related transition states, if enough of the beta... 

Dicko, C., Kenney, J. M., Knight, D., and Vollrath, F. (2004a). Transition to a beta-sheet-rich structure in spidroin in vitro The effects of pH and cations. Biochemistry 43, 14080-14087. 

Knight, D. P., Knight, M. M., and Vollrath, F. (2000). Beta transition and stress-induced phase separation in the spinning of spider dragline silk. Int. J. Biol. Macromol. 27, 205-210. 

Uversky, V. N., Narizhneva, N. V., Kirschstein, S. O., Winter, S., and Lober, G. (1997). Conformational transitions provoked by organic solvents in beta-lactoglobulin Can a molten globule like intermediate be induced by the decrease in dielectric constant FoldingDes. 2, 163-172. 

However, a more realistic model for the phase transition between baryonic and quark phase inside the star is the Glendenning construction [16], which determines the range of baryon density where both phases coexist. The essential point of this procedure is that both the hadron and the quark phase are allowed to be separately charged, still preserving the total charge neutrality. This implies that neutron star matter can be treated as a two-component system, and therefore can be parametrized by two chemical potentials like electron and baryon chemical potentials [if. and iin. The pressure is the same in the two phases to ensure mechanical stability, while the chemical potentials of the different species are related to each other satisfying chemical and beta stability. The Gibbs condition for mechanical and chemical equilibrium at zero temperature between both phases reads... 

Catalytic conversions in the monoterpene field have been reviewed recently [13-15]. There is an ongoing transition from conventional homogeneous catalysts (mineral acids, zinc halides) to solid Bronsted and Lewis acid catalysts. Thus, limonene can be alkoxylated with lower alcohols using zeolite H-Beta as the catalyst [16] at room temperature already, with high selectivity and conversion (Scheme 5.3). The alkoxy compounds are applied as fragrances with, dependent on the length of R, characteristic odors. 

A nucleus that has an excess of neutrons will undergo neutron to proton transition, a process that may restore the N P ratio but that requires the loss of an electron to convert the neutron to a positively charged proton, and as a result the atomic number increases by one. The particle emitted is a high speed electron known as a negation (P ) and the atom is said to emit beta radiation, e.g. 

Conversely, nuclei that contain an excess of protons undergo proton to neutron transition with the emission of a positively charged beta particle known as a positron Q8+) and with the reduction of the atomic number by one. A positron has only a very short existence, combining immediately with an electron of a nearby atom. The two particles disintegrate in the process with the emission of two gamma rays, e.g. 

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