Temporal analysis

SIGNAL RECEPTION AND ANALYSIS TEMPORAL ANALYSIS OF CHEMICAL SIGNALS TO DETERMINE SPATIAL GRADIENTS... 

This section reviews four different experimental approaches that together argue in favor of a temporal analysis function of lobster olfaction. The experiments include high-resolution measurements of turbulent odor dispersal and lobster sampling behavior, electrophysiological recording of in situ single cell responses to controlled and chaotic stimuli, and behavioral analysis of orientation and localization of odor sources. 

A. Maki, Y. Yamashita, Y. Ito, E. Watanabe, Y. Mayanagi, and H. Koizumi. Spatial and temporal analysis of human motor activity using noninvasive nir topography. Journal of Neurosicence, 11 1458-1469, 1995. 

V9. Vincent, A. M., and Maiese, K., Direct temporal analysis induction in living adherent neurons. J. Histochem. Cytochem. 47, 661-672 (1999). 

Temporal analysis of products (TAP) reactor systems enable fast transient experiments in the millisecond time regime and include mass spectrometer sampling ability. In a typical TAP experiment, sharp pulses shorter than 2 milliseconds, e.g. a Dirac Pulse, are used to study reactions of a catalyst in its working state and elucidate information on surface reactions. The TAP set-up uses quadrupole mass spectrometers without a separation capillary to provide fast quantitative analysis of the effluent. TAP experiments are considered the link between high vacuum molecular beam investigations and atmospheric pressure packed bed kinetic studies. The TAP reactor was developed by John T. Gleaves and co-workers at Monsanto in the mid 1980 s. The first version had the entire system under vacuum conditions and a schematic is shown in Fig. 3. The first review of TAP reactors systems was published in 1988. 

Additional evidence to this scheme was reported applying temporal analysis of products. This technique allows the direct determination of the reaction mechanism over each catalyst. Aromatization of n-hexane was studied on Pt, Pt—Re, and Pd catalysts on various nonacidic supports, and a monofunctional aromatization pathway was established.312 Specifically, linear hydrocarbons undergo rapid dehydrogenation to unsaturated species, that is, alkenes and dienes, which is then followed by a slow 1,6-cyclization step. Cyclohexane was excluded as possible intermediate in the dehydrocyclization network. 

Arcizet D, Meier B, Sackmann E, Radler JO, Heinrich D (2008) Temporal analysis of active and passive transport in living cells. Phys Rev Lett 101 248103... 

Myeong S. Nowak D.J. and Duggin M.J. (2006). A temporal analysis of urban forest carbon storage using remote sensing. Remote Sensing of Environment, 101(2), 277 -282. 

Micro reactors operated in the pulsed mode were introduced by Kokes et al. in 1955 [91], but have been intensively used only in the last 10 years. Such transient studies to obtain insight into reaction mechanisms were undertaken by Cleaves et al. with the temporal analysis of products (TAP) reactor 1997 [100], They observed rate coefficients of elementary reaction steps such as adsorption and desorption by applying pulses of reactants to a catalytic micro reactor combined with a quadrupole mass spectrometer. 

Temporal analysis of products Critical temperature Transmission electron microscopy Tetraethyl-ortho-silane Thermo gravimetry Tetrahydrofurane Turnover frequency Time on stream... 

Figure 24.3 Temporal analysis of responses measured simultaneously in five different antennal lobe neurons in the moth Manduca sexta. The matrices show patterns of neural synchrony evoked by either of two pheromone components or a binary mixture at two concentrations. The number of synchronous events was averaged over 20 trials and calculated for 500 ms from stimulus onset. The gray scale ranges from 0 to 3.8 coincident spikes per stimulus. The horizontal displays below the matrices show the averaged spiking rate in each single neuron (gray scale ranges from 0 to 5.5 spikes per stimulus period). Neural synchrony was influenced not only by the odor quality but also by both stimulus intensity and blend interactions (redrawn from Christensen eta ., 2000).

The plug flow reactor is increasingly being used under transient conditions to obtain kinetic data by analysing the combined reactor and catalyst response upon a stimulus. Mostly used are a small reactant pulse (e.g. in temporal analysis of products (TAP) [16] and positron emission profiling (PEP) [17, 18]) or a concentration step change (in step-response measurements (SRE) [19]). Isotopically labeled compounds are used which allow operation under overall steady state conditions, but under transient conditions with respect to the labeled compound [18, 20-23]. In this type of experiments both time- and position-dependent concentration profiles will develop which are described by sets of coupled partial differential equations (PDEs). These include the concentrations of proposed intermediates at the catalyst. The mathematical treatment is more complex and more parameters are to be estimated [17]. Basically, kinetic studies consist of ... 

Other types of discontinuous flow reactors may be used for transient kinetic studies in which, for example, isotopically labelled reactants are widely used in kinetic studies. This kind of investigation has been particularly developed in the case of discontinuous flow reactors. A different instrument called TAP (for Temporal Analysis of Products) permits extremely sensitive detection of intermediates or products. The results obtained with these various instruments can provide information about reaction mechanisms. 

Recent research has shown that the pheromone mediated behavior of lepidopterous insects is very complex. The chemical components of the pheromones are usually simple molecules, but complex mixtures involving permutations of geometry, functionality, and chain length are often required to elicit the complicated behavioral repertoire that eventually culminates in mating. To elucidate the chemical and behavioral aspects of this communications system, we have used a combination of methods including collection of the volatiles emitted by the female, analysis by high resolution capillary gas chromatography (GC), and the sequential and temporal analysis of the male s behavioral response to the pheromone blend and components thereof. New liquid phases and state of the art techniques have been developed for capillary GC to separate all the components of a pheromone blend. With these methods the chemical communication systems of Heliothis virescens (F.) and H. subflexa (Gn.) have been analyzed and certain aspects have been elucidated. 

There have been two recent kinetic studies of the dismutation behaviour of CHC12F, CHC1F2 and other members of the CHC13 F series, in one case over activated y-alumina under conventional flow conditions [105] in the other, over activated chromia using plug-flow and temporal analysis of products (TAP) reactors... 

Biagoev, B., Ong, S. E., Kratchmarova, I., Mann, M. (2004). Temporal analysis of phosphotyrosine-dependent signaling networks by quantitative proteomics. Nat. Biotechnol. 22, 1139-1145. 

A consecutive reaction mechanism was also proposed by Cleaves and Centi (11). This mechanism was based on experimental work to back up the theoretical calculations of Schitt and Jorgensen. Although the proposed intermediates were not detected under reaction conditions, they have been observed with fuel-rich gas feeds and under conditions of transient reactor operation. Using a TAP (temporal analysis of products) reactor, the researchers detected products in the following order of formation butane —> butene butadiene furan. However, the... 

We have developed several new measurement techniques ideally suited to such conditions. The first of these techniques is a High Pressure Sampling Mass Spectrometric method for the spatial and temporal analysis of flames containing inorganic additives (6, 7). The second method, known as Transpiration Mass Spectrometry (TMS) (8), allows for the analysis of bulk heterogeneous systems over a wide range of temperature, pressure and controlled gas composition. In addition, the now classical technique of Knudsen Effusion Mass Spectrometry (KMS) has been modified to allow external control of ambient gases in the reaction cell (9). Supplementary to these methods are the application, in our laboratory, of classical and novel optical spectroscopic methods for in situ measurement of temperature, flow and certain simple species concentration profiles (7). In combination, these measurement tools allow for a detailed fundamental examination of the vaporization and transport mechanisms of coal mineral components in a coal conversion or combustion environment. 

Easterby, J.S. (1990) Integration of temporal analysis and control analysis of metabolic systems. Biochem. J. 269, 255-259. 

TAP-2 (Temporal Analysis of Products) reactor was used to obtain adsorption parameters and diffusion coeflScients of the system NO-carbon catalyst. The dififiisivity of NO as well as the enthalpy of adsorption does not change after increasing the number of fimctional groups by an oxidative pretreatment of the carbon. 

This work shows the ability of the temporal analysis of products technique to obtain the transport and sorption parameters for the NO-carbon system. These parameters are directly related to the nature and number of functional groups on the carbon. 

Butene, cis/trans-2-butenes, butadiene and furan have been detected in the oxidation of n-butane on the VPO catalysts under very unusual conditions, such as under oxygen deficiency at high n-butane concentration and very short contact times [9], or in high vacuum in a temporal analysis of products (TAP) reactor [70]. 

---