Nucleus fused

Inertial confinement fusion has long succeeded in the context of militai y explosions—the hydrogen bomb. In the militai y application a fission bomb produces x-rays that drive an implosion of D-T fuel to enormous temperatures and densities such that fusion reactions occur during the short time that inertia keeps the fusing nuclei densely packed and hot. 

Understanding fusion invites another question If fusing nuclei releases energy, how did the early atomic bombs work In those bombs, nuclei were not fused, they were broken apart by nuclear fission. So, where does the energy of atomic bombs come from An important piece of the answer came from a brilliant Jewish scientist who fled Nazi Germany shortly before World War II. 

Like nucleosynthesis during the Big Bang, fusing nuclei in stars and supernovas exist as plasma rather than atoms (Faure, 1998, 17). 

First, 2-pyrrol-1-yl-benzaldchyde 159 (Fig. 55), which combines in the same molecule the functions of both substrate and aldehyde, gives aminoalkylation in position 2 of the pyrrole ring by reaction with the secondary amine, thus yielding an interesting precursor (160) of polycyclic derivatives with fused nuclei. ... 

Artificial radioactivity is observed when scientists take stable nuclei and try to combine them in various ways in an attempt to produce stable isotopes of new, or at least previously undiscovered, elements. All of the elements on the periodic table with atomic numbers of 93 or greater were produced with the aid of instruments called particle accelerators, which are used to fuse nuclei of known elements together in order to produce still heavier nuclei. All of these transuranium elements have proven to be radioactive, and they decay into more stable elements after varying periods of time. 

Guthmann A, Herbert H (1999) Distribution of metabotropic glutamate receptors in the parabrachial and Kdlliker-Fuse nuclei of the rat. Neuroscience S9 873-881. 

O Figure 6.1 depicts the potential energy between two fusing nuclei as a function of the distance between them. The exact behavior of the potential is unknown near the nucleus but, at larger distances, it is Coulomb-like and decreases as the inverse of the distance. The potential barrier resulting from the two interactions is called the Coulomb barrier. 

Cell hybridization The fusion of two or more dissimilar cells leading to the formation of a synkaryon (hybrid with fused nuclei from original cells). 

The exception to this are nuclear reactions, or reactions in which tJie nuclei of atoms are either split or fused. Nuclei and atoms of other elements axe tJius formed. 

Inner shell ionization of electrons to the continuum in ion-atom collisions can occur by two different processes. For low Z (projectile) particles on high Z2 (target) atoms the only available process is Coulomb excitation which is variously treated by plane wave Born approximation (PWBA), the binary encounter approximation (BEA), and the semiclassical approximation (SCA). When Z becomes comparable to 7/1 and the ion velocity v is lower than the velocity of the bound electron in question, v, the electrons adjust adiabati-cally to the approach of the two nuclei and enter molecular orbitals (MO) which in the limit of fused nuclei approach the atomic orbitals of the united atom Z = Z + Z2. This stacking of electrons can lead to a promotion of an innershell electron to the continuum or to a vacant outer orbital by direct curve crossing, rotational coupling, or radial coupling between molecular levels when such channels are available. 

In this experiment a week of target bombardment was required to produce a single fused nucleus. The team confirmed the existence of element 109 by four independent measurements. The newly formed atom recoiled from the target at predicted velocity and was separated from smaller, faster nuclei by a newly developed velocity filter. The time of flight to the detector and the striking energy were measured and found to match predicted values. 

On first sight it seems surprising that the pyrrole heteroatom in a fused imidazole does not prevent the appearance of a large positive charge at the neighbouring ring carbon atom. The reason for this is that the pyrrole nitrogen displays its TT-donor effect almost exclusively in the direction of the fused nucleus. 

Steroid (Section 26 11) Type of lipid present in both plants and animals charactenzed by a nucleus of four fused nngs (three are six membered one is five membered) Choles terol IS the most abundant steroid in animals... 

A surprising development involving the 3-position has been presented (61,62). This position traditionally has had a carboxylic acid group and attempts to replace the carboxylate have resulted in lower antibacterial activity. However, it was demonstrated that the carboxylate could be replaced with an isothiazolo ring fused between the 2- and 3-position of the quinolone nucleus. A-62824 [111279-87-9] (22), illustrates this stmctural modification as apphed to ciprofloxacin. 

Pyrazoles can be prepared by ring opening reactions of fused systems already containing the pyrazole nucleus. Thus several [5.5], [5.6] and [5.7] fused heterocycles have been opened to substituted pyrazoles, usually in basic medium. In general, the method has little preparative interest since another pyrazole derivative has usually been used to build the ring-fused system. However, due to the unexpected structures obtained, two publications are worthy of notice. 6//-Cyclopropa[5a,6a]pyrazolo[l,5-a]pyrimidine (638) was readily obtained from the corresponding pyrazolopyrimidine by the action of diazomethane at room temperature (Scheme 59) (81H(15)265). When (638) was treated with potassium hydroxide, the pyrazole (640) was formed, probably via the diazepine (639). 

Tetrazoles (744), as bis(nitrilimine) (745) generators (Section 4.04.3.1.2(ii)), afford polypyrazoles when reacted with diynes. Benzoquinone has also been condensed with bis-sydnones to incorporate a fused pyrazole nucleus (746). 

This chapter will deal exclusively with three-membered rings containing the hetero atoms O, S and N, and fused to the steroid skeleton. Because of the conformational requirements in steroids, not all of the usual methods of synthesis of three-membered rings are applicable to the fused ring system. For the synthesis of steroids to which an aziridine, oxirane or thiirane is attached either in the side chain or at a ring position but not directly fused to the nucleus, the methods discussed in this chapter, as well as others, are applicable. 

The low order of structural specificity required for classical antihistaminic activity was noted earlier. It has been found possible to substitute an indene nucleus for one of the two aromatic rings that most of these agents possess. The basic side chain may be present as either dimethylaminoethyl or itself cyc-lized to provide an additional fused ring. 

C22-0066. Compute the speed of a tritium nucleus with enough kinetic energy to fuse with a deuteron. Calculate nuclear radii using r— frn (1 fin = 10 m). 

This equation says that a nitrogen nucleus is composed of seven protons and seven neutrons. An alpha particle, which is identical to a helium ion, has two protons and two neutrons. A highly energetic collision fuses the two nuclei. The result is a rare isotope of oxygen with eight protons and nine neutrons. The leftover proton is ejected. And that proton is what Rutherford detected. 

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