Focusing, molecular

Haab B B and Mathies R A 1999 Single-molecule detection of DNA separations in microfabricated capillary electrophoresis chips employing focused molecular streams Ana/. Chem. 71 5137-45... 

The ability to focus molecular expression analysis on only a limited number of cell types depends on cell separation methods that minimize the opportunity for other cell types to contribute to gene expression in situ. Even the most carefully gathered biological samples contain many cell types, especially if the sample is from inflamed or necrotic tissue. More homogeneous samples are provided by laser capture microdissection (LCM), a method that isolates individual cells or sections of tissue from a fixed sample [144-148]. The use of LCM minimizes contributions by nontarget cell populations in comparisons of diseased and normal tissues, but also introduces handling and preparation steps that can affect detection accuracy. 

Haab, B.B. and Mathies, R.A., Single-molecule detection of DNA separations in microfabricated capillary electrophoresis chips employing focused molecular streams. Anal. Chem., 71,5137, 1999. Jacobson, S.C., Hergenrdder, R., Koutny, L.B., Warmack, R.J., and Ramsey, J.M., Effects of injection schemes and column geometry on the performance of microchip electrophoresis devices. Anal. Chem.,... 

Scientists use very focused "molecular beams" of gas-phase atoms and molecules in high-vacuum systems to study one-step chemical processes. For the gas-phase molecular beam reaction between sodium atoms and methyl chloride to make sodium chloride and the methyl radical,... 

An excellent treatment of molecular quantum mechanics, on a level comparable to that of Szabo and Ostiund. The scope of this book is quite different, however, as it focuses mainly on the basic principles of quantum mechanics and the theoretical treatment of spectroscopy. 

Because of limitations of space, this section concentrates very little on rotational motion and its interaction with the vibrations of a molecule. However, this is an extremely important aspect of molecular dynamics of long-standing interest, and with development of new methods it is the focus of mtense investigation [18, 19, 20. 21. 22 and 23]. One very interesting aspect of rotation-vibration dynamics involving geometric phases is addressed in section A1.2.20. 

Of course, condensed phases also exliibit interesting physical properties such as electronic, magnetic, and mechanical phenomena that are not observed in the gas or liquid phase. Conductivity issues are generally not studied in isolated molecular species, but are actively examined in solids. Recent work in solids has focused on dramatic conductivity changes in superconducting solids. Superconducting solids have resistivities that are identically zero below some transition temperature [1, 9, 10]. These systems caimot be characterized by interactions over a few atomic species. Rather, the phenomenon involves a collective mode characterized by a phase representative of the entire solid. 

As in classical mechanics, the outcome of time-dependent quantum dynamics and, in particular, the occurrence of IVR in polyatomic molecules, depends both on the Flamiltonian and the initial conditions, i.e. the initial quantum mechanical state I /(tQ)). We focus here on the time-dependent aspects of IVR, and in this case such initial conditions always correspond to the preparation, at a time of superposition states of molecular (spectroscopic) eigenstates involving at least two distinct vibrational energy levels. Strictly, IVR occurs if these levels involve at least two distinct... 

A MBER spectrometer is shown schematically in figure C1.3.1. The teclmique relies on using two inhomogeneous electric fields, the A and B fields, to focus the beam. Since the Stark effect is different for different rotational states, the A and B fields can be set up so that a particular rotational state (with a positive Stark effect) is focused onto the detector. In MBER spectroscopy, the molecular beam is irradiated with microwave or radiofrequency radiation in the... 

A few Van der Waals complexes have been observed using the analogous teclmique of molecular beam magnetic resonance, in which the molecules are focused using a magnetic rather than an electric field. 

We are all familiar with tire tliree states of matter gases, liquids and solids. In tire 19tli century the liquid crystal state was discovered [1 and 2] tliis can be considered as tire fourtli state of matter [3].The essential features and properties of liquid crystal phases and tlieir relation to molecular stmcture are discussed here. Liquid crystals are encountered in liquid crystal displays (LCDs) in digital watches and otlier electronic equipment. Such applications are also considered later in tliis section. Surfactants and lipids fonn various types of liquid crystal phase but this is discussed in section C2.3. This section focuses on low-molecular-weight liquid crystals, polymer liquid crystals being discussed in tire previous section. 

Extending time scales of Molecular Dynamics simulations is therefore one of the prime challenges of computational biophysics and attracted considerable attention [2-5]. Most efforts focus on improving algorithms for solving the initial value differential equations, which are in many cases, the Newton s equations of motion. 

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