Sample-independent ordering

NIR models are validated in order to ensure quality in the analytical results obtained in applying the method developed to samples independent of those used in the calibration process. Although constructing the model involves the use of validation techniques that allow some basic characteristics of the model to be established, a set of samples not employed in the calibration process is required for prediction in order to conhrm the goodness of the model. Such samples can be selected from the initial set, and should possess the same properties as those in the calibration set. The quality of the results is assessed in terms of parameters such as the relative standard error of prediction (RSEP) or the root mean square error of prediction (RMSEP). 

In 4-5 45° ACWJ s, Jc(45°) was nearly sample independent and nonvanishing. [12] For these ACWJ s, they obtained Fraunhofer-like patterns and performed Shapiro step analyses, indicating that their junctions were weak and first order. They also found to be independent of... 

In this test, cultured cells are seeded onto slides and the cells, which had been treated with and without metabolic activation for a short time period (e.g. 3 hours). Where negative or equivocal results are obtained, an independent experiment is conducted in which cells are treated for a long time period (e.g. 20 hours) in the absence of metabolic activation alone, and then sampled and examined for chromosome analysis. In both experiments the cells were sampled 20 hours after the start of treatment, as were the concurrent solvent and positive control cultures. Colcemide was added to each culture 2 hours before sampling in order to arrest cell division. Chromosome preparations were made, fixed, stained and examined. However, if clearly positive results were obtained in the first experiment, those from the second assay were not examined. If equivocal or negative results were... 

Differential scanning calorimetry measures the thermodynamic parameters associated with thermally induced phase transitions. Here, the sample of interest and an inert reference are heated or cooled independently at a programmed rate, and in tandem, such that their temperatures change in unison and the differential temperature is maintained at zero. If the sample undergoes a thermally induced transition, heat must be applied to or withdrawn from the sample in order to maintain the same temperature in both sample and reference compartments. The instrument measures the heat flow into the sample relative to the reference and this dijferential heat flow (or excess specific heat) is recorded as a function of temperature, resulting in a trace, as shown in Fig. 1... 

In order to verify the influence of physisorption on these experiments, H2 adsorption uptakes were measured at different temperatures at increasing S/Pt molar ratio. A maximum in adsorption uptake was observed at 100°C for both S/Pt=0 and S/Pt=2 samples, while hydrogen adsorbed on the S/Pt=383 sample was lower than for the other samples independent of temperature (Figure 6). 

All trace elements. All results obtained for trace elements are represented in Figure 4.5.9. Ideally the statistical analysis should take into account the effects of spatial location and time of sampling in order to analyze the total observed variation. However, spatial and temporal effects are not independent since it was not possible to collect all of the samples at the various locations simultaneously. It is clear that no significant variation was observed between sampling sites for some elements (e.g. Al, Cr, Cu) whereas trends can be observed for others (e.g. Fe, Mn, B). Concentrations of most trace elements were very low and this precluded any interpretation of results or any assessment of trends, and the statistical analysis focused on the same three trace elements (B, Sc and Zn) as those studied in the analysis of sampling uncertainty (see Uncertainty from sampling, above, pp. 311-316). 

The absolute quantification assay is used to quantify unknown samples by interpolating their quantity from a standard curve. Absolute quantification might be used to correlate a viral copy number with a disease status. It is of interest to the scientist to know the exact copy number of the target DNA in a given biological sample in order to monitor the progress of the disease. Absolute quantification can be performed with data from aU real-time PCR instruments however, knowledge of the absolute quantities of the standards is an absolute prerequisite in order to run the analysis, and most appropriate by some independent means. 

The statistical-mechanical applications of Monte Carlo nearly all involve special sampling methods known as importance sampling and ordinarily require a Markov chain of sample configurations rather than independent samples. In order to understand this it is helpful to begin by imagining a simpler Monte Carlo estimation of a quantity like U) of (2), and then to see why such an estimation would not be successful. 

In contrast, the natural bandwidth is an intrinsic property of the sample, independent of the instrument bandwidth, and is defined as the width (in nm) at half the height of the sample absorption peak, as shown in Figure 11. For example, the value for the natural bandwidth of the 340 nm peak of NADH is 58 nm, whereas for most cytochromes at room temperature the natural bandwidths in the a-region are of the order of 10 nm. It is easy to conceive that having too broad a spectral bandwidth would result in an apparent decrease of sample absorption. This is because the incident light would contain a large fraction of radiation with wavelengths poorly absorbed by the sample. 

FIG. 9 The effect of different thermal rates on the DSC spectra recorded upon the melting of a previously frozen sample. First-order phase transitions are rate-independent. However, the smaller the final step from the dynamic to the isothermal part of the measurement (iso.T in time units), the lower wiU be the difference between the sample and reference temperatures. Water-hexadecane sample with C = 0.25. (a)-(d), dTIdt = 1, 2, 4, and 8 K/min. Composition is given in Table 2. Symbols A//, w i,x are used to identify the thermal peaks due to the melting of hexadecane (h), water (w), K-oleate-hexanol-water mixture (b), and hexanol (x). (From Ref. 13.)... 

For physical techniques, transmission electron microscopy (TEM) seems to be the optimal technique for measuring the size of nanoparticles, as it allows us to look at them directly. However, its use is problematic. For example, the analysis is carried out on a microscopic amount of catalyst, and is hardly representative of the whole sample. Many observations must be made on each of several independently loaded samples in order to get reliable data, with the considerable expen-ditme of time that entails. Moreover, small or flat nanoparticles may be lost due to the insufficient contrast. However, a careful use of TEM is very valuable in some cases. 

It should be emphasized that the STM technique is only applicable for a conductive surface or electrode. Accordingly, problems may arise if an insirlating oxide layer is formed on a semiconductor surface. This problem is avoided by applying atomic force microscopy (AFM). In this case, the mass attraction and repulsion between a tip and a sample is measured, which is independent of the conductivity of insirlating layers at the surface of a given sample. In order to have sufficient sensitivity, the tip vibrates at a given resonance frequency and the change of this frequency is taken as a measure of the distance between the tip and the sample [27]. 

There is no standard dissolution test so the pilot test described in this report was adapted from published procedures. It needs to be compared against a standard sample in order to establish and compare accuracy and precision within the industry. Alternatively an intercomparison could be co-ordinated by an independent organisation by sending similar samples with imknown (to the analyst) activities for testing at participating establishments. 

A critical issue in statistical conformational sampling is the reliability and accuracy of the samples. In order to ensure the reliability of the statistical sampling of a particular conformational state, the relevant conformational region must be sampled sufficiently. A measure of the accuracy of statistical results is the variances of the samples. In order for the statistical results to be accurate, several independent samples have to be taken and the variances of the results calculated from these samples must be within given tolerances. Conformational sampling using the standard MC or MD procedures does not always meet the requirements of reliability and accuracy in all problems. Therefore, efforts have to be made to improve upon the basic sampling procedures in order to obtain satisfactory results. 

The typical reference electrode serves two main functions in electrochemical cells it produces a constant potential independent of ions in the sample, and, along with the working electrode, completes the flow of current in the electrochemical circuit. Conventional reference electrodes based on liquid junctions are able to accomplish these functions by separating the sample solution from a reference solution. They rely on slow leakage of ions from the inner solution into the sample in order to complete the circuit. This type of arrangement has several drawbacks, which make their use for long-term remote monitoring impossible the slow diffusion of ions from the inner solution would cause sample contamination and... 

Calorimetric data also demonstrated that the low temperature first-order transition occurs in quenched samples independent of the particular chemical nature and length of the flexible spacers. Since the structure of the rigid core of the mesogenic groups is the same for all the polyesters examined, it can be reasonably assumed that such a transition involves exclusively the aromatic moiety of the repeating unit. This conclusion is also supported by the calorimetric data obtained for copolyesters HTH-C3/C5 and HTH-C5/C10, which still exhibit the double-peaked transition in their DSC curves at the same temperature as that of the corresponding homopolymers (Fig. 1). It must be noted, however, that copolymer samples quenched from the LC state had very poor crystallinity and attempts to clarify the nature and state of order of the supercooled mesophase by x-ray analysis have been unsuccessful to date. 

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