Mechanical terms

Dead time A very short delay introduced before the start of acquisition that allows the transmitter gate to close and the receiver gate to open. Density matrix A description of the state of nuclei in quantum mechanical terms. 

Combined with their kinetic measurements, the authors proposed CO from the gas phase could directly react with oxygen atoms in the surface oxides, accounting for relatively high reactivity of this phase for CO oxidation. This mechanism, termed as Mars-Van Krevelen mechanism, challenges the general concept that CO oxidation on Pt group metals is dominated by the Langmuir-Hinshelwood mechanism, which proceeds via (1) the adsorption of CO and the dissociative adsorption of 02 and (2) surface diffusion of COa(j and Oa(j atoms to ultimately form C02. 

The concept of discrete or quantized energy levels can be superimposed on this diagram by representing them as a series of horizontal lines, the spacing of which becomes closer with increasing energy due to the anharmonic nature of the vibration. In quantum mechanical terms, these levels are labelled V =... 

The principle of NMR can be explained in quantum mechanical terms. The angular momentum of a spinning nucleus, quantized both in magnitude and direction, is given by the equation... 

What are the mechanisms by which trichothecenes exert their transcriptional and post-transcriptional effects The 60S ribosomal subunit is a well-known molecular target of trichothecenes in leukocytes and other actively proliferating eukaryotic cells,3 whereas attempts to demonstrate alternative receptors have not been successful.37 38 Translational inhibitors that bind to ribosomes rapidly activate mitogen-activated protein kinases (MAPKs) and apoptosis via a mechanism termed the ribotoxic stress response. 39-40... 

The quantum-mechanical term forbidden indicates that the probability of the event or process is too tiny for it to occur to any significant extent. 

The scheme analyzed so far is, in a way, a simplification of the Hartree-Fock scheme. As such, it is only a model approximation. The most serious drawback is the replacement of a fundamentally quantum mechanical term, whose very nature is to be non local, by a local approximation. Of course, when the system is in an electronic degenerate state, or when the BO approximation is no longer valid, the density functional method cannot be applied. For a discussion of this and other limitations the reader is referred to the paper by Bersuker [117],... 

Structural decisions with respect to pricing mechanisms (auctions, negotiations, posted prices), segmentation mechanisms, terms of trade, bundling of products... 

With the failure of the Bohr model it was found that the properties of an electron in an atom had to be described in wave-mechanical terms (p. 54). Each Bohr model energy level corresponding to... 

Nevertheless, it takes time and experience for most people to think about and talk about atoms in completely quantum mechanical terms. It is much simpler to think about orbitals as if they have substance. Therefore, in the text that follows, you will read about electrons occupying and filling orbitals. Strictly speaking, this terminology is not scientifically correct. However, it will help you understand some challenging concepts more easily. 

Both mechanisms, termed the associative and dissociative v complex substitution mechanisms, proceed via n complex adsorbed aromatics (e.g., benzene) which occupy a position on the catalyst so that the plane of the ring is parallel to the catalyst surface [Eq. (7)] ... 

This mechanism termed (formerly S ICB) was developed by Basolo and Pearson and their groups in the 1950 s in the face of a good deal of healthy opposition from Ingold, Nyholm, Tobe and their co-workers who favored a straightforward A (82 2) attack by OH ion on the complex. For a mechanism, in general,... 

Normal males inherit an X chromosome from their mother and a Y chromosome from then-father, whereas normal females inherit an X chromosome from each parent. Because the Y chromosome carries only about 30 protein-coding genes and the X chromosome carries hundreds of protein-coding genes, a mechanism must exist to equalize the amount of protein encoded by X chromosomes in males and females. This mechanism, termed X inactivation, ocairs very early in the development of female embryos. When an X chromosome is inactivated, its DNA is not transcribed into mRNA, and it is visuahzed under the microscope as a highly condensed Barr body in the nuclei of interphase cells. X inactivation has several important characteristics It is random—in some cells of the female embryo, the X chromosome inherited from the father is inactivated, and in others the X chromosome inherited from the mother is inactivated. Like coin tossing, this is a random process. 

Earlier, we did a thonght experiment abont one way that DNA replication could take place. In this mechanism, termed semiconservative, each new strand of DNAis paired with one of the old strands that is, the two strands of the original DNA molecule are now divided between the two molecnles, each of which has one old strand and one new strand. However, there is another possibility, termed conservative. In this case, the two new strands are paired with each other and the two old strands remain paired with each other. Matthew Meselson and W. F. Stahl provided compelling evidence that DNA replication is semiconservative. Here is how the experiment was done. ... 

The SI unit (symbolized by N) for force equal to kilo-gram-meter-second. The name of this classical mechanical term stems from Isaac Newton s work showing that... 

In the ionic model, the energy of an inorganic solid is assumed to be the sum of all the potentials, C/y, between atoms i and j. These consists of two terms, a classical electrostatic potential, C/y,eiectrostatio determined by the charges on the atoms, and a quantum mechanical term, C/,y,Fermi> that includes the repulsion that prevents individual atoms from collapsing into each other as well as any residual contributions from covalent bonding (eqn (2.1)) ... 

Development of the Frank-Condon principle in quantum mechanical terms (involving a transition dipole moment14) allows a calculation of the intensities referred to in terms of a series of Frank-Condon factors by which expressions for the transition probabilities are multiplied to obtain a net transition probability from one level to another for an electron-transfer process. 

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