Sequential determinants

The sticking coefficient of H2 on a metal has been determined through an adsorption experiment. The metal surface is assumed to have No = 1.5 x 10 sites m and each adsorption site is assumed to be occupied by one hydrogen atom when the surface is saturated. The experiment was performed by exposing the surface to a known pressure of hydrogen over a well-defined period of time (dosis) and then sequentially determining how much was adsorbed by, for example, TPD. All adsorption experiments where performed at such low temperatures that desorption could be neglected. 

Sekine K, Imai T, Kasai A. 1987. Liquid-liquid extraction separation and sequential determination of plutonium and americium in environmental samples by alpha-spectrometry. Talanta 34(6) 567-570. 

Sequential determination of platelet counts in patients receiving vincristine during early studies unexpectedly occasionally revealed thrombocytosis, which could not be accounted for by systemic response to treatment alone 10,11). Ultimately shown to most likely be the result of increased megakaryocytic endomitosis II), the observation led to the use of vincristine, and later vinblastine, both alone and bound to platelets, in a variety of thrombocytopenic disorders. These include idiopathic thrombocytopenic purpura, thrombotic thrombocytopenic purpura, and chemotherapy-induced microangiopathic hemolytic anemia. 

A more useful procedure, in that it allows sequential determination of the A-terminal amino acids in a peptide, is the Edman degradation. This process removes the A-terminal amino acid, but leaves the rest of the chain intact, so allowing further reactions to be applied. The reagent used here is phenyl isothiocyanate. 

Percival DR, Martin DB. 1974. Sequential determination of radium-226, radium-228, actinium-227, and thorium isotopes in environmental and process waste samples. Anal Chem 46 1742-1749. 

Clinical improvement, especially the disappearance of fever or defervescence, is the best parameter to judge the response to therapy. However, clinical improvement can be difficult to monitor objectively in critically ill patients with multi-system disease. Also, clinical improvement can be very slow for certain infections, e.g. tuberculosis. The peripheral blood leukocyte count including the presence of early stages in leucocyte differention and the level of serum C-Reactive Protein (CRP, an acute phase protein) are parameters that can be sequentially determined to monitor improvement. For monitoring the effect of treatment of chronic infections such as endocarditis or osteomyelitis, weekly determination of the erythrocyte sedimentation rate has been proven useful. 

Thus, a deterministic answer assumes that the laws of physics and chemistry have causally and sequentially determined the obligatory series of events leading from inanimate matter to life - that each step is causally linked to the previous one and to the next one by the laws of nature. In principle, in a strictly deterministic situation, the state of a system at any point in time determines the future behavior of the system - with no random influences. In contrast, in a non-deterministic or stochastic system it is not generally possible to predict the future behavior exactly and instead of a linear causal pathway the sequence of steps may be determined by the set of parameters operating at each step. 

Figure 21-11 Temperature profile of inductively coupled plasma. [From V A. Fassel. Simultaneous or Sequential Determination of the Elements at AH Concentration Levels And. Chem. 1979, 51, I290A.]... 

The most commonly used PCA algorithm involves sequential determination of each principal component (or each matched pair of score and loading vectors) via an iterative least squares process, followed by subtraction of that component s contribution to the data. Each sequential PC is determined such that it explains the most remaining variance in the X-data. This process continues until the number of PCs (A) equals the number of original variables (M), at which time 100% of the variance in the data is explained. However, data compression does not really occur unless the user chooses a number of PCs that is much lower than the number of original variables (A M). This necessarily involves ignoring a small fraction of the variation in the original X-data which is contained in the PCA model residual matrix E. 

This classification technique uses a space that is defined by a unique set of vectors called linear discriminants or LDs. Like the PCs obtained from PCA analysis, LDs are linear combinations of the original M-variables in the X-data that are completely independent of (or orthogonal to) one another. However, the criterion for determining LDs is quite different than the criterion for determining PCs each LD is sequentially determined such... 

Cox, A., Cook, I.G. and McLeod, C.W. (1985) Rapid sequential determination of chromium (III)-chromium (VI) by flow injection analysis-inductively coupled plasma atomic-emission spectrometry. Analyst, 110, 331-333. 

Jian, W. and McLeod, C.W. (1992) Rapid sequential determination of inorganic mercury and methylmercury in natural waters by flow-injection-cold vapour-atomic fluorescence spectrometry. Talanta, 39, 1537-1542. 

Andreae [683] described a sequential volatilisation method for the sequential determination of arsenate, arsenite, mono-, di- and trimethylarsine, monomethylarsonic and dimethylarsinic acid, and... 

Positron emission tomography (PET) using nC labeled P-gp substrates allows noninvasive and sequential determination of brain concentrations in nonhuman primates and humans (361). Using this technical advance, Sasongko et al. demonstrated that cyclosporin A (given by intravenous constant infusion... 

ICP-OES is an analytical system that can do simultaneous or sequential determination of up to 50 elements at all concentration levels with a high degree of accuracy and precision. Excellent vaporization-atomization-excitation-ionization is obtained with an argon-supported ICP operated at atmospheric pressure. The emitted spectra is observed with a polychromator or a scanning spectrometer may be used depending on whether simultaneous or sequential determinations are desired. This atomization-excitation process does not exhibit interelenent effects often seen in AAS, and ppb range detection is routine. Effective nebulization of samples needs to be improved on however, ICP and direct-current (DC) plasmas are extremely effective atomization sources that provide the most effective instrumental technique for simultaneous elemental analysis. 

M. Gallignani, M. Valero, M. R. Brunette, J. L. Burguera, M. Burguera, Y. Petit de Pena, Sequential determination of Se(IV) and Se(VI) by flow injection-hydride generation-atomic absorption spectrometry with HCl/HBr microwave aided pre-reduction of Se(VI) to Se(IV), Talanta, 52 (2000), 1015-1024. 

The acid mixture is chosen such that the majority of steels can be dissolved in it. When a residue remains this must be fused using the well-known sodium tetraborate method. This sequential determination of 15 elements in one weighing obviously requires the previous setting up of 15 calibration curves in the appropriate concentration range (Fig. 2). This can be done, in principle, in two ways either the calibration curves are entered using known data with the aid of a microprocessor or appropriate standard samples are used with every analysis. 

Direct structure determination methods, where positives are characterized directly via off-bead or on-bead identification of their chemical structure, will be described in detail in this section. Indirect methods that determine the structure of positives from the library architecture will be covered later they use either deconvolutive methods (Section 7.3), where the iterative synthesis of library pools with decreasing complexity via sequential determination of the best monomers leads to the identification of a positive structure, or encoding methods (Section 7.4), where, during the library synthesis, the structure of each component is coupled to a tag that can be read from a single bead after the library screening. 

Ultrasonic nebulizers have also been employed in continuous flow systems as interfaces between sample preparation steps in the analytical process and detection by virtue of their suitability for operating in a continuous mode. Thus, preconcentration devices have commonly been coupled to atomic spectrometers in order to increase the sensitivity of some analytical methods. An enhancement factor of 100 (10 due to USNn and 10 due to preconcentration) was obtained in the determination of platinum in water using a column packed with polyurethane foam loaded with thiocyanate to form a platinum-thiocyanate complex [51]. An enhancement factor of 216 (12 with USNn and 18 with preconcentration) was obtained in the determination of low cadmium concentrations in wine by sorption of metallic complexes with pyridylazo reagents on the inner walls of a PTFE knotted reactor [52]. One special example is the sequential determination of As(lll) and As(V) in water by coupling a preconcentration system to an ICP-AES instrument equipped with a USN. For this purpose, two columns packed with two different resins selective for each arsenic species were connected via a 16-port valve in order to concentrate them for their subsequent sequential elution to the spectrometer [53]. 

A coulometric titration method was introduced for sequential determination of sulfite, thiosulfate and ascorbic acid (1) in solutions containing sulfite-thiosulfate or sulfite-ascorbic acid couples. Formaldehyde or acetaldehyde can be used to mask the sulfite component. Two sequential measurements of coulometric time, one for both components in the mixture and one for the sample solution in which sulfite is masked, can be used to determine the concentrations of sutfite-thiosulfate and sulfite-ascorbic acid couples. The method is linear for 0.5-60 p,M 1 in the presence of 0.44-13 (xM sulfite, with RSD 0.1-4% and current efficiency of ca 98.0%. The method can be used for determination of the presence of sulfite and 1 in real sample matrices such as mineral waters and vitamin C tablets . 

Strategic Reductions of Computa-tionai Compiexity. Logically, the Active Ana-Ic Approach can be conceived as sequentially determining all the sterically allowed conformations for each molecule under consider-... 

The studies described above, as well as numerous others, have led to the conclusion that protein antigens may contain two general classes of determinant structures, namely, sequential and conformational. Sequential determinants would be those occurring in a linear conformation, as in the unfolded form of a protein, and conformational determinants would be those that are recognized by their homologous antibodies only when they occur in a particular conformation. The latter class would include determinants formed from amino acids that are located at distant points in the... 

Andreae described a method for the sequential determination of arsenate, arsenite, mono-, di- and trimethyl arsine, MMAA, DMAA and trimethylarsine oxide in natural waters with detection limits of several ng/1. The arsines are volatilized from the sample by gas stripping the other species are then selectively reduced to the corresponding arsines and volatilized. The arsines are collected in a cold trap cooled with liquid nitrogen. They are then separated by slow warming of the trap or by gas chromatography, and measured with atomic absorption, electron capture and/or flame ionization detectors. He found that these four arsenic species all occurred in natural water samples. 

Radiochemical methods which allow sequential determination of radionuclides are often desirable for reasons of speed and cost-effectiveness, for example in mixed waste streams or in waste characterization for nuclear decommissioning. Although a variety of methods are in use for the analysis of in concretes, they tend to use large reagent volumes and involve... 

Sequential Determination of Ca-41/45 and Sr-90 in an Activated Concrete Core 3 CONCLUSIONS... 

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