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Volume and time

An important observation in the figure is that the volume, and so the density, of the glass is not constant at a given temperature, but is a function of the cooling rate Thus a polymer glass is not a solid in thermodynamic equilibrium, but is, in a sense, supercooled to various states of non-equilibrium molecular packing. If the polymer is quenched from a high temperature, more entropy is frozen into [Pg.56]

This dependence on cooling rate is not unique to volume and density. It will be shown, to a greater or lesser extent, by all the thermodynamic properties of the glass, and so it will become apparent in a variety of different thermal analyses. A lack of recognition of these rate effects leads to different measurements that may appear to be inconsistent. Thus often the thermal mass of a sample used in mechanical measurements is much larger than that used in calorimetric investigations, so the rates of heat flow and temperature rise are different. [Pg.57]

This concept of free volume is not a very convenient way of quantifying the restriction of the motion, although it does reflect that nature of the changes which occur at a molecular level. Nevertheless, there are techniques to probe the volume between molecules and it is found that, as assumed by the free volume theories, the available space between molecules does dramatically increase at the transition temperature. [Pg.57]


Furthermore VGInsight [16], a high-end tool for multi-volume and time-dependent volume raytracing is used for Virtual Reality inspection of the measured dataset. The package is running on a Quad-Pentium Pro System under the Linux Operating System. [Pg.495]

Figure 6. Relationship between Plate Volumes and Time... Figure 6. Relationship between Plate Volumes and Time...
Equation 18 defmes a parabolic relationship between filtrate volume and time. The expression is valid for any type of cake (i.e., compressible and incompressible). From a plot of V + C versus (t+Tq), the filtration process may be represented by a parabola with its apex at the origin as illustrated in Figure 5. Moving the axes to distances C and Tq provides the characteristic filtration curve for the system in terms of volume versus time. Because the parabola s apex is not located at the origin of this new system, it is clear why the filtration rate at the beginning of the process will have a finite value, which corresponds to actual practice. [Pg.166]

As more fuel is converted into combustion products per unit of volume and time, expansion flow becomes stronger. Higher flow velocities go hand in hand with more intense turbulence. This process feeds on itself that is, a positive feedback coupling comes into action. In the turbulent stage of flame propagation, a gas explosion may be described as a process of combustion-driven expansion flow with the turbulent expansion-flow structure acting as an uncontrolled positive feedback (Figure 3.2). [Pg.51]

I is the number of ions created per unit volume and time. The value used was / = 1.4 X 1010 ions cc.-1 sec.-1 which corresponds to irradiation with a 50-mc. source (see section on intensity of irradiation above) n is the number of ions per cc. Ion recombination coefficient... [Pg.222]

A dynamic ordinary differential equation was written for the number concentration of particles in the reactor. In the development of EPM, we have assumed that the size dependence of the coagulation rate coefficients can be ignored above a certain maximum size, which should be chosen sufficiently large so as not to affect the final result. If the particle size distribution is desired, the particle number balance would have to be a partial differential equation in volume and time as shown by other investigators ( ). [Pg.365]

Integrating each equation over all volumes and times ... [Pg.165]

The progress of recovery efforts cannot be based confidently on LNAPL product thickness maps. Although these maps provide quantification of overall trends, the numerous factors that impact hydrocarbon thicknesses make accurate quantification difficult. An estimate of effectiveness thus is based on volume recovered to date divided by the total volume that is considered recoverable. Furthermore, as the recovery project progresses and new data are introduced, the volume and time frame for recovery should be continually reevaluated and revised. [Pg.201]

Overall volumetric productivity Qp (mol.m s ) (it is also common to use a yearly basis) is the average production capacity per unit volume and time of the bioreactor. The overall volumetric productivity is confined, on the one hand, by physical constraints, such as mass and heat transfer, and, on the other hand, by biocatalyst concentration... [Pg.393]

Concentrations of gaseous pollutants are often expressed in terms of parts per million (ppm) by volume, and time is expressed in minutes. Use of these concentration units must be reflected in the units used for the rate constants as well for example, second-order rate constants are in units of ppnt-1 min-1. Occasionally, gas concentrations are given in units of mol L-1 or in units of pressure such as Torr, atmospheres, or Pascals these can be converted to the more conventional units... [Pg.132]

Expressed in words, this equation says that the temporal change of the concentration in the reactor is equal to the input per unit volume and time minus the output and total reaction per unit volume and time. [Pg.483]

J orption describes the amount of chemical being sorbed (or desorbed, if. /SOrpti0n < 0) per unit bulk volume and time. From Eq. 2 (iff = constant) ... [Pg.820]

The system is shown in Fig. 21.7. It is described by two concentrations (state variables), CA and CB, by two zero-order input functions, JA and JB (input per volume and time), by two first-order output functions, kACA and kBCB (output per volume and time), and by the first-order transformations from A to B and vice versa. The inputs and outputs can be the sum of two or more processes, for instance, the sum of the input through different inlets and from the atmosphere (as in Eq. 21-7a), or the sum of the output at the outlet and by exchange to the atmosphere (as in Eq. 21-7b.). [Pg.976]

J [ML 3r ] total external input of chemical per unit volume and time... [Pg.1056]

The production of species i (number of moles per unit volume and time) is the velocity of reaction,. In the same sense, one understands the molar flux, jh of particles / per unit cross section and unit time. In a linear theory, the rate and the deviation from equilibrium are proportional to each other. The factors of proportionality are called reaction rate constants and transport coefficients respectively. They are state properties and thus depend only on the (local) thermodynamic state variables and not on their derivatives. They can be rationalized by crystal dynamics and atomic kinetics with the help of statistical theories. Irreversible thermodynamics is the theory of the rates of chemical processes in both spatially homogeneous systems (homogeneous reactions) and inhomogeneous systems (transport processes). If transport processes occur in multiphase systems, one is dealing with heterogeneous reactions. Heterogeneous systems stop reacting once one or more of the reactants are consumed and the systems became nonvariant. [Pg.3]

The use of ELISA is broad and it finds applications in many biological laboratories over the last 30 years many tests have been developed and vahdated in different domains such as clinical diagnostics, pharmaceutical research, industrial control or food and feed analytics for instance. Our work has been to redesign the standard ELISA test to fit in a microfluidic system with disposable electrochemical chips. Many applications are foreseen since the biochemical reagents are directly amenable from a conventional microtitre plate to our microfluidic system. For instance, in the last 5 years, we have reported previous works with this concept of microchannel ELISA for the detection of thromboembolic event marker (D-Dimer) [4], hormones (TSH) [18], or vitamin (folic acid) [24], It is expected that similar technical developments in the future may broaden the use of electroanalytical chemistry in the field of clinical tests as has been the case for glucose monitoring. This work also contributes to the novel analytical trend to reduce the volume and time consumption in analytical labs using lab-on-a-chip devices. Not only can an electrophoretic-driven system benefit from the miniaturisation but also affinity assays and in particularly immunoassays with electrochemical detection. [Pg.904]

The rates at which epoxy and primary amine groups are consumed, in units of moles (equivalents) per unit volume and time, are described by the following constitutive equations ... [Pg.162]

If the local low-frequency component of a phase quantity is assumed to be constant throughout the volume and time averaging, we can further obtain... [Pg.194]

Chemical activities in the field of mass screening are often related to combinatorial chemistry [51,52]. One major goal, especially in the field of solid phase chemistry involving polymers like DNA or peptides, aims at the increase in the number of compounds per reactor volume and time. Commercially available microtiter plates are established as reactors in this case whereby robotic feed systems fit perfectly to their dimensions. A drastic reduction of reaction volume and increase in number of reaction vessels ( wells ) leads to the so-called nanotiter plates (e.g. with 3456 wells). Microfabrication methods such as the LIGA process are ideal means for the cost effective fabrication of nano-titer plates in polymeric materials by embossing or injection molding techniques so that inexpensive one-way tools are realized. [Pg.247]

The total number of transitions per unit volume and time from Eq. (17) is obtained by dividing by t and summing over j (occupied bands) and / (unoccupied bands). Integrating over the Brillouin zone gives ... [Pg.331]

Scenario uncertainty includes descriptive errors (e.g. wrong or incomplete information), aggregation errors (e.g. approximations for volume and time), errors of assessment (e.g. choice of the wrong model) and errors of incomplete analysis (e.g. overlooking an important exposure pathway). [Pg.17]

Off-line dicarbamate solvent extraction and ICP-MS analysis [317] provided part-per-trillion detection limits Cd (0.2 ppt), Co (0.3 ppt), Cu (3 ppt), Fe (21 ppt), Ni (2 ppt), Pb (0.5 ppt), and Zn (2 ppt). Off-line matrix removal and preconcentration using cellulose-immobilized ethylenediaminetetraacetic acid (EDTA) have also been reported [318]. Transition metals and rare earth elements were preconcentrated and separated from the matrix using on-line ion chromatography with a NTA chelating resin [319]. Isotope-dilution-based concentration measurement has also been used after matrix separation with a Chelex ion-exchange resin [320]. The pH, flow rate, resin volume, elution volume, and time required for isotope equilibration were optimized. A controlled-pore glass immobilized iminodiacetate based automated on-line matrix separation system has also been described [321]. Recoveries for most metals were between 62% and 113%. [Pg.134]

Gas released from adsorbent bulb into dosing volume and time allowed for equilibration. [Pg.68]


See other pages where Volume and time is mentioned: [Pg.172]    [Pg.173]    [Pg.442]    [Pg.24]    [Pg.111]    [Pg.111]    [Pg.173]    [Pg.100]    [Pg.971]    [Pg.1056]    [Pg.35]    [Pg.494]    [Pg.500]    [Pg.179]    [Pg.1221]    [Pg.469]    [Pg.165]    [Pg.338]    [Pg.35]    [Pg.329]    [Pg.363]    [Pg.221]    [Pg.179]    [Pg.110]    [Pg.196]    [Pg.411]    [Pg.300]    [Pg.5]   


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Retention Volume and Time

Volume and residence time

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