Solution process of suspension poly(vinyl chloride) in cyclohexanone by means of a viscometer

To study the structure of grains of suspension poly(vinyl chloride) (PVC), the authors applied a capillary viscometer for cyclic measurements of viscosity of the PVC–cyclohexanone solution during dissolution of the polymer. Final concentration of the solution was 0.5–1.0 g/100 cm³ and the measurements were made at temperatures of 313, 333, 353, and 373 K. It was found that at 353 K, a temperature close to the glass transition temperature of PVC, the curve describing changes of viscosity vs. the dissolution time has a pronounced maximum. It follows from a preliminary analysis of the obtained results that this maximum corresponds to the viscosity of a PVC solution in which average apparent mass is many times larger than true average molecular mass of the studied sample. It mans that into the solution enter single chains and some formations, called microdomains in the literature, that are composed of tens of macromolecules. The microdomains disintegrate later to single macromolecules.     

Conversion of microwave pyrolysed ASR's char using high temperature agents

Pyrolysis enables to recover metals and organic feedstock from waste conglomerates such as: automotive shredder residue (ASR). ASR as well as its pyrolysis solid products, is a morphologically and chemically varied mixture, containing mineral materials, including hazardous heavy metals. The aim of the work is to generate fundamental knowledge on the conversion of the organic residues of the solid products after ASR's microwave pyrolysis, treated at various temperatures and with two different types of gasifying agent: pure steam or 3% (v/v) of oxygen. The research is conducted using a lab-scale, plug-flow gasifier, with an integrated scale for analysing mass loss changes over time of experiment, serving as macro TG at 950, 850 and 760 °C. The reaction rate of char decomposition was investigated, based on carbon conversion during gasification and pyrolysis stage. It was found in both fractions that char conversion rate decreases with the rise of external gas temperature, regardless of the gasifying agent. No significant differences between the reaction rates undergoing with steam and oxygen for char decomposition has been observed. This abnormal char behaviour might have been caused by the inhibiting effects of ash, especially alkali metals on char activity or due to deformation of char structure during microwave heating.     

Application of composites to impact energy absorption

The sleeve, conical simple composite elements and polymer foam filled composite conical element behaviour during failure are presented and discussed. The impact energy in these elements is absorbed in progressive fracture process. Possibilities of energy absorption panels – the great structures made from simple elements in a certain military and civilian field are demonstrated.     

Highly Stretchable Conducting SIBS‐P3HT Fibers

Poly(styrene‐β‐isobutylene‐β‐styrene)‐poly(3‐hexylthiophene) (SIBS‐P3HT) conducting composite fibers are successfully produced using a continuous flow approach. Composite fibers are stiffer than SIBS fibers and able to withstand strains of up 975% before breaking. These composite fibers exhibit interesting reversible mechanical and electrical characteristics, which are applied to demonstrate their strain gauging capabilities. This will facilitate their potential applications in strain sensing or elastic electrodes. Here, the fabrication and characterization of highly stretchable electrically conducting SIBS‐P3HT fibers using a solvent/non‐solvent wet‐spinning technique is reported. This fabrication method combines the processability of conducting SIBS‐P3HT blends with wet‐spinning, resulting in fibers that could be easily spun up to several meters long. The resulting composite fiber materials exhibit an increased stiffness (higher Young’s modulus) but lower ductility compared to SIBS fibers. The fibers’ reversible mechanical and electrical characteristics are applied to demonstrate their strain gauging capabilities.     

Experiences with large-scale operational trials of ALTO-enhanced P2P filesharing in an intra-ISP scenario

Application Layer Traffic Optimization (ALTO) has recently gained attention in the research and standardisation community as a way for a network operator to guide the peer selection process of distributed applications by providing network layer topology information. In particular P2P applications are expected to gain from ALTO, due to the many connections peers form among each other, often without taking network layer topology information into account. In this paper, we present results of an extensive intra-ISP trial with an ALTO-enhanced P2P filesharing software. In summary, our results show that—depending on the concrete setting and on the distribution of upload capacity in the network—ALTO enables an ISP to save operational costs significantly while not degrading application layer performance noticeably. In addition, based on our experience we are able to give advice to operators on how to save costs with ALTO while not sacrificing application layer performance at all.     

Statistical issues in biological radiation dosimetry for risk assessment using stable chromosome aberrations

Biological dosimeters are useful for epidemiologic risk assessment in populations exposed to catastrophic nuclear events and as a means of validating physical dosimetry in radiation workers. Application requires knowledge of the magnitude of uncertainty in the biological dose estimates and an understanding of potential statistical pitfalls arising from their use. This paper describes the statistical aspects of biological dosimetry in general and presents a detailed analysis in the specific case of dosimetry for risk assessment using stable chromosome aberration frequency. Biological dose estimates may be obtained from a dose-response curve, but negative estimates can result and adjustment must be made for regression bias due to imprecise estimation when the estimates are used in regression analyses. Posterior-mean estimates, derived as the mean of the distribution of true doses compatible with a given value of the biological endpoint, have several desirable properties: they are nonnegative, less sensitive to extreme skewness in the true dose distribution, and implicitly adjusted to avoid regression bias. The methods necessitate approximating the true-dose distribution in the population in which biological dosimetry is being applied, which calls for careful consideration of this distribution through other information. An important question addressed here is to what extent the methods are robust to misspecification of this distribution, because in many applications of biological dosimetry it cannot be characterized well. The findings suggest that dosimetry based solely on stable chromosome aberration frequency may be useful for population-based risk assessment.     

Hidden covariation detection: A fundamental and ubiquitous phenomenon.

H. Hendrickx, J. De Houwer, F. Baeyens, P. Eelen, and E. Van Avermaet (see record 1997-02349-012) reported a series of (mostly unsuccessful) studies on nonconscious hidden covariation detection (HCD); for example, they reported that out of 3 attempts to replicate P. Lewicki et al.'s studies (1986, see also records 73-13630, 77-29976 and 09019, and 79-38878) only 1 produced the expected results. They concluded that HCD may be not as general and robust as the previous research suggested, and they considered boundary conditions. In this article, the authors discuss a number of weaknesses of H. Hendrickx et al.'s experiments (and systematic deviations from the original methodology) that are potentially responsible for the lack of the expected results and discuss missing facts in their arguments (e.g., they failed to mention any published replications of the HCD studies from other than the present authors' laboratories). It is argued that when all evidence is considered, the proper conclusion is that nonconscious processing of covariations is not only general and robust but also a ubiquitous phenomenon mediating a variety of processes of acquisition of information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)