Chemical-physical methods

Synthesis of metallic nanoparticles proceeds in many ways they can be divided into physical and chemical. Physical methods include inert gas condensation, arc discharge, ion sputtering, and laser ablation. The main idea behind these methods is condensation of solid particles from the gas phase, the substrate for nanoparticle generation being pure metals (or their mixtures/alloys in the case of complex particle composition). Chemical methods, in turn, include various methods utilizing... 

All remediation methods which remove, convert, or destroy contaminants in a matrix, i.e., soil or groundwater, except thermal and biological methods, are defined as chemical-physical methods. It is possible to pursue a variety of strategies with chemical-physical methods (Offutt etal. 1988) ... 

In addition to organoleptic assessment, several chemical/physical methods have been developed to measure lipid oxidation. These include peroxide value, thiobarbituric acid (TBA) value, ultraviolet absorption (at 233 nm), ferric thiocyanate, Kreis test, chemiluminescence, oxygen uptake and analysis of carbonyls by HPLC (see Rossell, 1986). 

The most contemporary chemical physics methods and principles are applied to the characterization of these ten properties. The coverage is broad, ranging from the study of biopolymers to the analysis of antioxidant and medicinal chemical activity, on the one hand, to the determination of the chemical kinetics of not chemical systems and the characterization of elastic properties of novel nanometer scale material systems, on the other. 

Advances in Kinetics and Mechanism of Chemical Reactions describes the chemical physics and/or chemistiy of 10 novel material or chemical systems. These 10 novel material or chemical systems are examined in the context of issues of stmeture amd bonding, and/or reactivity, and/or transport properties, and/or polymer properties, and/ or biological characteristics. This eclectic survey thus encompasses a special focus on the associated kinetics, reaction mechanisms and/or other chemical physics properties, of these 10 broadly chosen material or chemical systems. Thus, the most contemporary chemical physics methods and principles are applied to the characterization of the properties of these 10 novel material or chemical systems. The coverage of these novel systems is thus broad, ranging fiom the study of biopolymers to the analysis of antioxidant and medicinal chemical activity, on the one hand, to the determination of the chemical kinetics of novel chemical systems, and the characterization of elastic properties of novel nanometer scale material systems, on the other hand. 

The potency, or vitamin content, of foods may be determined by biological, microbiological, chemical, physical methods, and/or human assay. 

Compared to chemical-physical methods as the phase inversion temperature (PIT) method as used, for example, in the cosmetic industry, the high-pressure homogenization can be applied for a wide range of ingredients. It is extremely flexible in terms of phase viscosities and interfadal tension. 

The deposition of films from a liquid phase whose precursor solution has been synthesized via sol-gel chemistry has widely been applied to produce coatings of different compositions and structures, such as oxides, hybrids, nanocomposites, and mesoporous coatings. Chemical-physical methods, such as plasma-enhanced chemical vapor deposition (PECVD) or chemical vapor deposition (CVD), are still fevored for most of the industrial applications. The sol-gel route to films, however, even if has not been able to challenge these techniques in terms of mass production, has occupied an important niche in the field. 

In this manner, the KuQp of a petroieum cut can be calcuiated quickly from readily avkilable data, i. e., the specific gravity and the distillation curve. The A //np value is between 10 and 13 and defines the chemical nature of the cut as it will for the pure components. The characterization factor is extremely Va luable and widely used in refining although the discriminatory character of the Kuqp is less than that obtained by more modern physical methods described in 3.2 and 3.3. 

Voth G 1996 Path integral centroid methods Advances in Chemical Physics, New methods in Computational Quantum Mechanics vol XCIII, ed I Prigogine and S A Rice... 

In this section we present several numerical teclmiques that are conmronly used to solve the Sclirodinger equation for scattering processes. Because the potential energy fiinctions used in many chemical physics problems are complicated (but known to reasonable precision), new numerical methods have played an important role in extending the domain of application of scattering theory. Indeed, although much of the fomial development of the previous sections was known 30 years ago, the numerical methods (and computers) needed to put this fomialism to work have only been developed since then. 

A connnon feature of all mass spectrometers is the need to generate ions. Over the years a variety of ion sources have been developed. The physical chemistry and chemical physics communities have generally worked on gaseous and/or relatively volatile samples and thus have relied extensively on the two traditional ionization methods, electron ionization (El) and photoionization (PI). Other ionization sources, developed principally for analytical work, have recently started to be used in physical chemistry research. These include fast-atom bombardment (FAB), matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ES). 

Pulay P 1987 Analytioal derivative methods in quantum ohemistry Advances in Chemical Physics vol LXIX, ed K P Lawley (New York Wiley-Intersoienoe) pp 241-86... 

Figure 6.25 reprinted from Chemical Physics Letters, 196, Ding H-Q, N Karasawa and W A Goddard III, T he Reduced Cell Multipole Method for Coulomb Interactions in Periodic Systems with Million-Atom Unit Cells, 6-10, 1992, with permission of Elsevier Science. 

Figure 7.2 from Alder B J and TE Wainwright 1959. Studies in Molecular Dynamics. 1. General Method. The Journal of Chemical Physics 31 459-466. 

Johnson B G, P M W Gill and J A Pople 1993. The performance of a family of density functional methods. Journal of Chemical Physics 98 5612-5626. 

Fig. 5.29 Method for correcting the path followed by a steepest descents algorithm to generate the intrinsic reaction coordinate. The solid line shows the real path and the dotted line shows the algorithmic approximation to it. (Figure redrawn from Gonzalez C and H B Schlegel 1988. An Improved Algorithm for Reaction Path Following. Journal of Chemical Physics 90 2154-2161.)...

Aj ala P Y and H B Schlegel 1997. A Combined Method for Determining Reaction Paths, Minima and Transition State Geometries. Journal of Chemical Physics 107 375-384. 

Elber R and M Karplus 1987. A Method for Determining Reaction Paths in Large Molecules Application to Myoglobin. Chemical Physics Letters 139 375-380. 

Darden T A, D York and L Pedersen 1993. Particle-mesh Ewald An N.log(N) method for Ewald sums in large systems. Journal of Chemical Physics 98 10089-10092. 

I A, I G Tironi and W F van Gunsteren 1995, Lattice-sum methods for calculating electrostatic teractions in molecular simulations. Journal of Chemical Physics 103 3014-3021. 

Zhou R and B J Berne 1995. A New Molecular Dynamics Method Combining the Reference Sys Propagator Algorithm with a Fast Multipole Method for Simulating Proteins and Ol Complex Systems. Journal of Chemical Physics 103 9444-9459. 

H and B J Berne 1999. Multicanonical Jump Walking A Method for Efficiently Sampling Rough Energy Landscapes. Journal of Chemical Physics 110 10299-10306. 

Pearlman D A and P A Kollman 1989. A New Method for Carrying Out Free-Energy Perturbation Calculations - Dynamically Modified Wmdows. Journal Of Chemical Physics 90 2460-2470. 

Zwanzig R W 1954. High-temperature Equation of State by a Perturbation Method. 1. Nonpolar Gases. Journal of Chemical Physics 22 1420-1426. 

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