Direct mechanical effects, methods based

Class 3-Methods Based on Direct Mechanical Effects. These include the use of acoustical probes [57-71], acoustic impedance measurements [72—75], acoustic fluxmeter [76], the measurement of radiation forces [17,21,77—112], the distortion of liquid surface [ 113-115], surface cleaning, dispersive effects, emulsification [ 116-118], erosion [ 19,22,119-125], mass transfer measurements (electrochemical probe) [26,129], absorption methods [93,132], particle velocity measurements [132], and optical methods [133-141],... 

Lasers are the precision tools of photochemistry and they have been used to both pump (initiate) and probe (analyse) chemical processes on time-scales that are short enough to allow the direct observation of intramolecular motion and fragmentation (i.e. on the femtosecond time-scale). Thus, laser-based techniques provide us with one of the most direct and effective methods for investigating the mechanisms and dynamics of fundamental processes, such as photodissociation, photoionization and unimolecu-lar reactions. Avery wide variety of molecular systems have now been studied using laser techniques, and only a few selected examples can be described here. 

Methods based on direct mechanical effects, including measurements using acoustic probes, optical methods and acoustic impedance, radiation forces, liquid surface distortion or particle velocity measurements. 

To establish the molecular thermodynamic model for uniform systems based on concepts from statistical mechanics, an effective method by combining statistical mechanics and molecular simulation has been recommended (Hu and Liu, 2006). Here, the role of molecular simulation is not limited to be a standard to test the reliability of models. More directly, a few simulation results are used to determine the analytical form and the corresponding coefficients of the models. It retains the rigor of statistical mechanics, while mathematical difficulties are avoided by using simulation results. The method is characterized by two steps (1) based on a statistical-mechanical derivation, an analytical expression is obtained first. The expression may contain unknown functions or coefficients because of mathematical difficulty or sometimes because of the introduced simplifications. (2) The form of the unknown functions or unknown coefficients is then determined by simulation results. For the adsorption of polymers at interfaces, simulation was used to test the validity of the weighting function of the WDA in DFT. For the meso-structure of a diblock copolymer melt confined in curved surfaces, we found from MC simulation that some more complex structures exist. From the information provided by simulation, these complex structures were approximated as a combination of simple structures. Then, the Helmholtz energy of these complex structures can be calculated by summing those of the different simple structures. 

Fig. 3. Property of gene delivery with BLs and US exposure (a) Schema of transfection mechanism by BLs and US. The mechanical effect based on the disruption of BLs by US exposure, which results in generation of some pores on plasma membrane, is associated with direct delivery of extracellular plasmid DNA into cytosol, (b) Luciferase expression in COS-7 cells transfected by BLs and US. COS-7 cells (1x10 cells/500 pLAube) were mixed wifh pCMV-Luc (5 pg) and BLs (60 pg). The cell mixture was exposed with US (Frequency 2 MHz, Duty 50%, Burst rate 2 Hz, Intensity 2.5 W/ cm. Time 10 s). The cells were washed and cultured for 2 days. Affer fhaf, luciferase acfivify was measured, (c) Effecf of US condition on transfection efficiency with BLs. COS-7 cells were exposed with US (Frequency 2 MHz, Duty 50%, Burst rate 2 Hz, Intensity 2.5 W/cm Time 0,1, 5,10 s) in the presence of pCMV-Luc (0.25 pg) and BLs (60 pg). Luciferase activity was measured as above, (d) Effect of serum on transfection efficiency of BLs. COS-7 cells in the medium containing EBS (0,10, 30, 50% (v/v)) were treated with US (Erequency 2 MHz, Duty 50%, Burst rate 2 Hz, Intensity 2.5 W/cm, Time 10 s), pCMV-Luc (0.25 pg) and BLs (60 pg) or transfected with lipoplex of pCMV-Luc (0.25 pg) and lipofectin (1.25 pg). (e) In vitro gene delivery to various types of cell using BLs and US. The method of gene delivery was same as above. S-180 mouse sarcoma cells, Colon26 mouse colon adenocarcinoma cells, B16BL6 mouse melanoma cells, Jurkat human T cell line, HUVEC human umbilical endothelial cells. Luciferase activity was measured as above. <10 RLU/mg protein, <10 RLU/mg protein Each data represents the mean S.D. n=3). L PEG-liposomes, LF Lipotectin...

The nonlinear interaction of light with matter is useful both as an optical method for generating new radiation fields and as a spectroscopic means for probing the quantum-mechanical structure of molecules [1-5]. Light-matter interactions can be formally classified [5,6] as either active or passive processes and for electric field based interactions with ordinary molecules (electric dipole approximation), both may be described in terms of the familiar nonlinear electrical susceptibilities. The nonlinear electrical susceptibility represents the material response to incident CW radiation and its microscopic quantum-mechanical formalism can be found directly by diagrammatic techniques based on the perturbative density matrix approach including dephasing effects in their fast-modulation limit [7]. Since time-independent (DC) fields can only induce a... 

Another method based on Fl-ECL inhibition method for determination of neurotransmitters, noradrenaline, and DA has been developed for Ru(bpy)3 /TPA and for Ru(phen)3 /TPA systems. The proposed inhibition mechanism shows the quenching effect of o-benzoquinone derivative generated from the direct electrooxidation reactions of noradrenaline and DA. This method has superiority of sensitivity over several detection methods, such as spectrometry, electro-chemical, CE, and HPLC methods, and has potential for sensitive and trace analyses of... 

The conceptual framework for the - semiclassical simulation of ultrafast spectroscopic observables is provided by the Wigner representation of quantum mechanics [2, 3]. Specifically, for the ultrafast pump-probe spectroscopy using classical trajectories, methods based on the semiclassical limit of the Liouville-von Neumann equation for the time evolution of the vibronic density matrix have been developed [4-8]. Our approach [4,6-8] is related to the Liouville space theory of nonlinear spectroscopy developed by Mukamel et al. [9]. It is characterized by the ability to approximately describe quantum phenomena such as optical transitions by averaging over the ensemble of classical trajectories. Moreover, quantum corrections for the nuclear dynamics can be introduced in a systematic manner, e.g. in the framework of the entangled trajectory method [10,11]. Alternatively, these effects can be also accounted for in the framework of the multiple spawning method [12]. In general, trajectory-based methods require drastically less computational effort than full quantum mechanical calculations and provide physical insight in ultrafast processes. Additionally, they can be combined directly with quantum chemistry methods for the electronic structure calculations. 

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