INDEX concentration dependence

Creatine kinase, creatine kinase myocardial band Creatine kinase (CK) enzymes are found in many isoforms, with varying concentrations depending on the type of tissue. Creatine kinase is a general term used to describe the nonspecific total release of all types of CK, including that found in skeletal muscle (MM), brain (BB) and heart (MB). CK MB is released into the blood from necrotic myocytes in response to infarction and is a useful laboratory test for diagnosing myocardial infarction. If the total CK is elevated, then the relative index (RI), or fraction of the total that is composed of CK MB, is calculated as follows RI = (CK MB/CK total) x 100. An RI greater than 2 is typically diagnostic of infarction. 

The measurement of the width of the metastable zone is discussed in Section 15.2.4, and typical data are shown in Table 15.2. Provided the actual solution concentration and the corresponding equilibrium saturation concentration at a given temperature are known, the supersaturation may be calculated from equations 15.1-15.3. Data on the solubility for two- and three-component systems have been presented by Seidell and Linkiv22 , Stephen et alS23, > and Broul et a/. 24. Supersaturation concentrations may be determined by measuring a concentration-dependent property of the system such as density or refractive index, preferably in situ on the plant. On industrial plant, both temperature and feedstock concentration can fluctuate, making the assessment of supersaturation difficult. Under these conditions, the use of a mass balance based on feedstock and exit-liquor concentrations and crystal production rates, averaged over a period of time, is usually an adequate approach. 

P has a very suggestive form in relation to Figure 8.26. For a large concentration of acceptors, the second term in the denominator can be made considerably smaller than 1 (i.e., Xt is proportional to acceptor concentration [A]), and P will be independent of concentration. On the other hand, for a small concentration of acceptors, the second term in the denominator can be made considerably larger than 1, and P will fall off linearly as the concentration is reduced. The scale factor in all of this is Q. With Q large, the transition from concentration independence to linear concentration dependence will be at low acceptor concentrations. P falls to 5 when the second term in the denominator of Eq. (8.27) is equal to 1, and so a critical concentration of acceptors [A], /2 can be defined to characterize the falloff. Expressing Xt in terms of molecular parameters (x, = em[A] ln(10)/, where n is the particle refractive index, em is the molar decadic extinction coefficient, [A] is the concentration of acceptors, and k is 2n/X) yields... 

As phenytoin has a narrow therapeutic index therapeutic drug monitoring to establish therapeutic levels is mandatory. Dose and concentration dependent adverse effects are nausea, vomiting, tremor, confusion, headache and dizziness, nystagmus and ataxia. 

Pharmacokinetic parameters are also important in relation to toxicity. The toxicity of antimicrobial drugs varies considerably and is usually concentration dependent. The therapeutic index is the ratio between the concentration of drug that is toxic for the... 

The preceding discussion assumed a pure liquid was used for the measurement. Most molecules of interest, however, are not in the liquid state at room temperature. In this case it is common to dissolve the compound in an appropriate solvent and conduct the measurement. Contributions to the second harmonic signal are therefore obtained from both the solvent and solute. Since r and the local field factors that are related to e and n, (the dielectric constant and refractive index respectively) are concentration dependent, the determination of p for mixtures is not straightforward. Singer and Garito (15) have developed methods for obtaining r0, eQ, and nQ, the values of the above quantities at infinite dilution, from which accurate values for p can be obtained in most cases. 

The dipole moments were determined from the concentration dependence of the dielectric constant and the refractive index of the solutions in the low concentration limit (mol fraction ca. 0.001). 

Fig. 10. Concentration dependence of the refractive index difference (An) between the polymer solution and solvent for a 13% PET-PCL copolymer. The lines represent the least-square fits to the measured data...

At the comparison of concentration dependencies of the characteristic quantities (6.61) with experimental determinations, one has to remember that effect of excluded volume was not taken into account in equations (6.61), which allow us to say only about qualitative correspondence. The behaviour of the initial viscosity is the most widely studied (Poh and Ong 1984, Takahashi et al. 1985). The concentration dependence of the viscosity coefficient in the melt-like region can be represented by a power law (Phillies 1995). The index can be found to be approximately 25 + 1, in accordance with (6.61). There are some differences in the behaviour of polymer solutions, which are connected with different behaviour of macromolecular coils at dilution. 

For isotropic scatterers at 45° and 135°, 1 + cos2 i i has an identical absolute value that cancels to unity. For anisotropic particles, the concentration dependence of Z complicates the measurements, but this defect is mitigated by plotting a series of Z 1 vs c points and extrapolating to 0. The intercept, referred to as the reduced specific dissymmetry, is a better index of nonsphericity. Z can be adapted to the determination of Mw (Stacey, 1956). 

The major constituents in seawater are conventionally taken to be those elements present in typical oceanic water of salinity 35 that have a concentration greater than 1 mg kg excluding Si, which is an important nutrient in the marine environment. The concentrations and main species of these elements are presented in Table 1. One of the most significant observations from the Challenger expedition of 1872-1876 was that these major components existed in constant relative amounts. As already explained, this feature was exploited for salinity determinations. Inter-element ratios are generally constant, and often expressed as a ratio to Cl%o as shown in Table 1. This implies conservative behaviour, with concentrations depending solely upon mixing processes, and indeed, salinity itself is a conservative index. 

Carboxyethylgermsesquioxane can inhibit bone resorption by osteoclasts in a concentration-dependent manner . The therapeutic effect of 2-carboxyethylgermanium sesquioxane (Ge-132) for experimental osteoporosis has been studied using ovariectomized rats maintained on a low calcium containing diet. The Ge-132 decreased the bone strength, and affected the femur cortical bone index and bone mineral mass caused by osteoporosis . ... 

The effective polarizability a was defined in (93). The relation between and the refractive index n was given in (13). Concentration-dependent measurements of the refractive index yield experimental information about the optical polarizability of the molecules. 

Concentration-dependent measurements of this quantity yield the permanent dipole moment in the electronic ground state. The static first-order polarizability a(0 0) in (105) can be estimated from refractive index measurements of a(-w w), (103). 

The above relationships (Figure 1.10) show that the optical pigment properties depend on the particle size D and the complex refractive index n = n (1 - i/c), which incorporates the real refractive index n and the absorption index k. As a result, the reflectance spectrum, and hence the color properties, of a pigment can be calculated if its complex refractive index, concentration, and particle size distribution are known [1.40]. Unfortunately, reliable values for the necessary optical constants (refractive index n and absorption index k) are often lacking. These two parameters generally... 

Since the square of the specific refractive index increment (dn/dc) appears in the light scattering equations, this value must be accurately known in order to measure Mv,- (An error of x% in dn/dc will result in a corresponding error of about 2x% in M. ) The value of dn/dc is needed at infinite dilution, but there is very little concentration dependence for polymer concentrations in the normal range used for light scattering. The required value can therefore be obtained from... 

For most of the drugs, a better delivery system would significantly minimize the fluctuations in blood levels and consequently improve the therapeutic benefit of the drug as well as reduce its concentration-dependent adverse effect. This feature is of special importance for drugs with relatively narrow therapeutic index and narrow absorption window (e.g. L-Dopa). While the... 

The value of the refractive index increment dh/dc is needed at infinite dilution, but there is little concentration dependence in the normal concentration range used for light scattering of polymer solutions. The required value can therefore be obtained from... 

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