Basic Experimental Approach

These considerations encouraged water-soluble polymers such as PEO to be popularly studied in early research on electrospinning. Only limited work on electrospinning of polymers such as polyamides was reported in the early literature because of the requirement for expensive and/or hazardous solvents (e.g., formic acid for nylon-6,6). 

The minimum equipment requirements for demonstration of simple electrospinning in the laboratory are as follows  

An electrode (hollow tubular or solid) that is maintained in contact with the polymer solution. 

A grounded or oppositely charged surface to collect the nanofibers. 

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The basic experimental approach is suitable using Purkinje fibers from a variety of species including in addition to the dog, the rabbit and pig. The use of primate tissue for such studies carries with it some ethical and financial considerations, as does, in fact the use of dog purkinje fibers in certain countries. 

The basic experimental approach when using electro-osmosis to characterize surfaces is to measure fluid mobility at a surface when electro-osmosis is in-... 

Basically, experimental approaches to ion transfer kinetics rely on classical galvanostatic [152] or potentiostatic [146] techniques, such as chronopotentiometry [118, 138], chronocoulometry [124], cyclic voltammetry [146], convolution potential sweep voltammetry [147], phase selective ac voltammetry [142], or equilibrium impedance measurements [148]. These techniques were applied mostly to liquid-liquid interfaces with a macroscopic area (typically around 0.1 cm ). However, microelectrode methodology has been successfully introduced into liquid-liquid electrochemistry as a novel electroanalytical tool by Senda and coworkers [153] and... 

Variations of this basic experimental approach include the addition of various solid phases and dissolved species common in natural waters. The effect of these additional components on the calculated and observed ORP s is then noted. Sodium or potassium nitrate or chloride was also added in some experiments to adjust the ionic strength. 

Thermal desorption studies have the attraction of comparatively simple experimentation, but face severe problems in the evaluation of unambiguous, unique rate parameters from the measurements. The subject has been reviewed several times recently (see, for example, refs. 57—61), particularly in relation to gas—metal systems, so here we will concentrate on its specific applications to semiconductors, where it has been used almost exclusively to study metal absorbate-isemiconductor surface interactions. Since this topic provides the subject matter for Sect. 5, we will limit the discussion in this section to the basic experimental approach and available methods of data analysis. We will leave to Sect. 5 the critical appraisal of the validity of these methods as applied to solid adsorbates, and the interaction models which have been postulated. 

Courtier-Murias, D., Farooq, H., Masoom, H. et al. 2012. Comprehensive multiphase NMR spectroscopy Basic experimental approaches to differentiate phases in heterogeneous samples. J. Magn. Reson. doi 10.1016/j.jmr.2012.02.009. 

One of the basic experimental approaches to understanding thermodynamics of a process is to investigate die effect of temperature. It allows the estimations of the enthalpy and, sometimes, entropy of the process, thus provides insights on the microscopic molecular... 

One can distinguish among several basic experimental approaches to the problem of membrane biogenesis in Chlamydomonas (1) Use of mutants which have lost the ability to form photosynthetic membranes when grown in the dark, but can do so when exposed to the light. (2) Use of synchronized cultures in which the replication of the chloroplast and increase in membrane can be isolated in time from the remainder of the other cellular and developmental activities during the life cycle of the organism. (3) Isolation and characterization of membrane mutants. (4) Use of specific protein, RNA, and DNA synthesis inhibitors in combination with any of the above three systems. 

To enable comparison to this experimental approach, archaeological human bones of various ages and soil properties (Table 9.1) from the Anthropological Collection in Munich were analyzed. All German skeletal series come from humic soil with, neutral to slightly basic pH. The samples from Tinkey, Syria, coastal Pern and Egypt have been buried in dry, sandy soils. Soil samples from most of the excavation sites were available and bone sample... 

The basic experimental arrangements for photocurrent measurements under periodic square and sinusoidal light perturbation are schematically depicted in Fig. 19. In the previous section, we have already discussed experimental results based on chopped light and lock-in detection. This approach is particularly useful for measurement at a single frequency, generally above 5 Hz. At lower frequencies the performance of lock-in amplifier and mechanical choppers diminishes considerably. For rather slow dynamics, DC photocurrent transients employing optical shutters are more advisable. On the other hand, for kinetic studies of the various reaction steps under illumination, intensity modulated photocurrent spectroscopy (IMPS) has proved to be a very powerful approach [132,133,148-156]. For IMPS, the applied potential is kept constant and the light intensity is sinusoid-... 

For oxidation by atmospheric oxygen a sample in an EPR tube may simply be opened to air and stirred. However, reaction with any other gas than air requires special handling of the sample on the manifold of a Schlenk line. Examples are oxidation by pure oxygen, reduction by hydrogen, and also the reaction by any gaseous substrate or inhibitor such as CO, C02, NO, N20, etc. Basically, there are two different experimental approaches mixing with a solution in which the gas is dissolved or mixing with a pressurized atmosphere of the gas. 

The measurement of vibrational optical activity requires the optimization of signal quality, since the experimental intensities are between three and six orders of magnitude smaller than the parent IR absorption or Raman scattering intensities. To date all successful measurements have employed the principles of modulation spectroscopy so as to overcome short-term instabilities and noise and thereby to measure VOA intensities accurately. In this approach, the polarization of the incident radiation is modulated between left and tight circular states and the difference intensity, averaged over many modulation cycles, is retained. In spite of this common basis, there are major differences in measurement technique and instrumentation between VCD and ROA consequently, the basic experimental methodology of these two techniques will be described separately. 

An alternative method to get rid of the biexponentiality of the transverse I spin relaxation is to use the basic experimental scheme known as the measurement of Ti in the rotating frame or instead of the CPMG approach. This was proposed, for the purpose of carbon-13 studies, by Ohuchi et al. [46] already in the late seventies. The general relation between T2, and other related quantities was discussed in that work and in the important paper by Vega [47]. The basic idea of the Tip measurements is illustrated in fig. 4(b). After the initial (7t/2) I-spin pulse, the phase of the radiofrequency field is switched by 90°. The transverse mag-... 

A mixed-flow reactor requires uniform composition of the fluid phase throughout the volume while the fluid is constantly flowing through it. This requires a special design in order to be achieved in the case of gas-solid systems. These reactors are basically experimental devices, which closely approach the ideal flow conditions and have been devised by Carbeny (Levenspiel, 1972). This device is called a basket-type mixed reactor (Figure 3.6). The catalyst is contained in four rapidly spinning wire baskets. 

The methods of analysis involving numerical solutions appear sufficiently well advanced to permit a rapid expansion of the microscopic analysis of turbulent transport as soon as some of the basic experimental facts are obtained. The next advance of particular interest to the chemical engineer appears to be an understanding of the kinetics of chemical reactions in turbulent flow. The fluctuating temperatures and concentrations introduce perturbation in the normal approach to kinetics that may well yield interesting results in the field of combustion and perhaps in chemical processing. 

In this chapter experimental approach to the study of a photochemical reaction is gradually developed starting from simple observations. It is expected that such an approach will promote basic understanding of the methodology and an appreciation for the use of sophisticated instruments necessary in photochemical studies. The case history of the reaction be tween anthracene and carbon tetrachloride has been taken up as this apparently simple reaction has many complexities and has been investigated bv a number of workers at various levels of sophistication. 

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