Effect of temperature,shear and blending conditions on the relaxation properties of milled and compression molded plasticized PVC compounds

Blended, milled, and compression molded plasticized PVC compounds containing 30 wt percent of DIOP plasticizer were studied by combination of low effective frequency relaxation methods. The compounds were found to be heterogeneous and the ratio of plasticized and unplasticized phases dependent on the processing parameters. There is a correlation between the mechanical strength and the phase structure of the system.     

Learning the Statistics of People in Images and Video

This paper address the problems of modeling the appearance of humans and distinguishing human appearance from the appearance of general scenes. We seek a model of appearance and motion that is generic in that it accounts for the ways in which people's appearance varies and, at the same time, is specific enough to be useful for tracking people in natural scenes. Given a 3D model of the person projected into an image we model the likelihood of observing various image cues conditioned on the predicted locations and orientations of the limbs. These cues are taken to be steered filter responses corresponding to edges, ridges, and motion-compensated temporal differences. Motivated by work on the statistics of natural scenes, the statistics of these filter responses for human limbs are learned from training images containing hand-labeled limb regions. Similarly, the statistics of the filter responses in general scenes are learned to define a background distribution. The likelihood of observing a scene given a predicted pose of a person is computed, for each limb, using the likelihood ratio between the learned foreground (person) and background distributions. Adopting a Bayesian formulation allows cues to be combined in a principled way. Furthermore, the use of learned distributions obviates the need for hand-tuned image noise models and thresholds. The paper provides a detailed analysis of the statistics of how people appear in scenes and provides a connection between work on natural image statistics and the Bayesian tracking of people.     

In situ liquid-liquid extraction as a sample preparation method for matrix-assisted laser desorption/ionization MS analysis of polypeptide mixtures

A novel liquid-liquid extraction (LLE) procedure was investigated for preparation of peptide and protein samples for matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). LLE using ethyl acetate as the water-immiscible organic solvent enabled segregation of hydrophobic and hydrophilic polypeptides in mixtures, thereby reducing the complexity of mass spectra obtained by MALDI MS. The LLE technique was optimized for rapid and sensitive in situ (on-target) sample preparation for MALDI MS analysis of proteins and peptides at low-picomole and subpicomole levels. Addition of MALDI matrix to the organic solvent enhanced the efficiency of the LLE-MALDI MS method for analysis of hydrophobic peptides and proteins. LLE-MALDI MS enabled the detection of the hydrophobic membrane protein bacteriorhodopsin as a component in a simple protein mixture. Peptide mixtures containing phosphorylated, glycosylated, or acylated peptides were successfully separated and analyzed by the in situ LLE-MALDI MS technique and demonstrate the potential of this method for enhanced separation and structural analysis of posttranslationally modified peptides in proteomics research.     

Applied Dielectric Spectroscopy of Polymeric Composites

In this article a theoretical background for understanding dielectric phenomena in heterogeneous polymeric composites is presented, and the application of these principles to practical problems is illustrated by experimental examples. First a short overview of the existing theoretical mixing formulae is given, the differences in these approaches are discussed, and the areas of application are indicated. Conditions for the appearance of an interfacial relaxation process are delineated; limitations of the theories are given. Experimental examples include immiscible polymer blends, mineral-filled polyolefins, thermoset composites, and conductive composites. In the first example, AC dielectric spectroscopy is used to monitor the phase separation process and to evaluate interactions between the separated phases. In the second example, the effect of filler permittivity, volume fraction, and surface treatment is discussed with respect to the AC and DC dielectric properties. It is shown that in mineral-filled polyolefins, water adsorbed at the matrix-filler interface plays an important role. In the third example, the effect of filler purity (and conductivity) on the dielectric properties is demonstrated. Nonelectrical-grade glass powder causes a strong interfacial polarization and electrode polarization in an unsaturated polyester resin, whereas electrical-grade glass fiber reinforcement leads to minor property changes. In the final example, the effects of processing conditions on the AC conductivity and permittivity of conductive composites is discussed. Extensive shear and orientation cause a shift of the percolation threshold, thus reducing the conductivity. Thus it is shown that dielectric methods can be used to investigate problems in processing technology.     

Potentiometric homogeneous enzyme-linked competitive binding assays using adenosine deaminase as the label

Homogeneous enzyme-linked competitive binding assays for biotin are described that are based on the competition between an enzyme-biotin conjugate and free biotin for a fixed number of binding sites of avidin. Unlike conventional homogeneous enzyme immunoassays, in this system the analyte (biotin) is labeled with adenosine deaminase (ADA), an ammonia-producing enzyme. Consequently, potentiometric rather than photometric methods can be used as means of detection. Several ADA-biotin conjugates were prepared and showed as high as 97% inhibition of the enzymatic activity in the presence of avidin. Addition of free biotin reverses this inhibition in an amount proportional to the concentration of analyte. Relatively steep dose-response curves were observed, leading to a precise and accurate assay for biotin. The detection limits of these curves were as low as 1 x 10(-8) M. Varying the concentration of the reagents in the assay allowed the detection limit and working range to be altered to a desired value. The proposed method was applied in the determination of biotin in a horse-feed supplement.     

Analysis of temperature-dependent AC dielectric loss data

The analysis of dielectric loss data is frequently complicated by the presence of ohmic conductivity, especially at lower frequencies. Two simple methods are discussed for locating transition temperatures and for determining activation energies in such cases. In the first method the permittivity derivative [dε′(T)/dT] is used; in the second, permittivity difference spectra ε′(T, v₁) – ε′(T, v₂) (v₁ ? v₂ are used. The latter technique, however, cannot be used for activation energy determination. The theoretical basis of these methodologies and an analysis of representative experimental data are presented. The data set include measurements of pure and filled polyurethanes and of radiation-cured unsaturated polyester resins. Finally, the advantages of data presentation in the form of ε′ and ε″ instead of tan δ are discussed.     

An optimisation strategy in a digital environment applied to neonatal chest imaging

The aim of this study was to find the optimum tube voltage for neonatal chest imaging in computed radiography. The study was designed to take full advantage of the benefits of digital imaging, for example, by comparing the tube voltages at constant effective dose. A phantom study using a living rabbit was first conducted. Images were collected at tube voltages ranging from 40 to 90 kV(p). The reproduction of four structures (central vessels, peripheral vessels, carina and thoracic vertebrae) was rated by 10 radiologists. The reproduction of both central and peripheral vessels was relatively independent of tube voltage. The carina was better reproduced at higher tube voltages whereas the opposite was true for the thoracic vertebrae. Based on the higher importance of the reproduction of the carina it was decided that 90 kV(p) was the optimal tube voltage. To validate the result from the phantom study, a follow-up study was conducted in which images of neonates collected at the tube voltage regularly used at Sahlgrenska University Hospital (70 kV(p)) were compared with images collected at the tube voltage proposed by the phantom study. The follow-up study confirmed the results from the phantom study that the reproduction of the carina was better at 90 than at 70 kV(p). In conclusion, for neonatal chest imaging-given the same effective dose-90 kVp gives better reproduction of important structures than the regularly used 70 kV(p).     

Influence of prenatal mercury exposure upon scholastic and psychological test performance: benchmark analysis of a New Zealand cohort

A general biological concept of the unity of structure and function in biological systems at all levels of their organization-cell, tissue, organ and organism-is well known. However, the constructive contents of such unity remain unclear. It appears that until we learn to separate and allocate structural and functional problems of biological systems construction, we cannot understand how this unity is reached. Or else, there is a methodological problem: how to separate and to allocate the basic categories of biological self-organization? Here, we consider different biological tissues in order to separate, in the first place, the basic concepts-structure, function, control-as independent systems which have their own referents. Then to solve the problem of association, a concept of "equipment" is introduced: the structure is equipped with function, the function is equipped with control. As a result, any elementary cycle of bioorganization is represented as a sequence of phases: (1) formation of structural basis, (2) functional equipment of structure, (3) libernetical equipment of function-differentiation of variability freedoms, (4) establishment of control to overcome the superfluous freedom of structural and functional organization.     

Dielectric spectroscopic study of wood plastic combinations

Curing of wood-polyester combitions was studied by recording dielectric spectra as a function of temperature at fixed frequency at different stages of cure and as function of cure-time at fixed temperature. The measurements were preformed by a specially constructed continuously recording spectrometer equipped with linear temperature program. By measuring the shifts of the dielectric transition temperatures it was possible to follow changes of the molecular mobilities in the resin as crosslinking proceeded. By measuring the relative intensities of the dielectric absorption the change of the concentration of the polar groups as a function of cure time could be followed. The existence of a stepwise aftercuring waw revealed.