A study of the rheological behavior of high‐temperature polymer electrolyte membrane solutions

The viscosity behavior of various compositions of polymer electrolyte membrane solutions, which are later hydrolyzed into proton conducting membrane film for fuel cells, is characterized. Using the Carreau‐Yasuda model and time–temperature superposition, an empirical model relating the viscosity as a function of temperature and shear strain rate has been developed for several membrane solution compositions. It is observed that the viscosity of the non‐Newtonian membrane has a strong correlation to the membrane's inherent viscosity (a property determined during membrane synthesis). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Is the failure to monitor comprehension an instance of cognitive impulsivity?

Third and fifth graders' ability to monitor comprehension was measured with the error detection paradigm. Subjects read three passages, each containing incongruent information. Subjects' performance at detecting these contradictions was recorded. Subjects were also given a multiple-choice recall/comprehension test after each passage. Cognitively reflective and impulsive children were identified with the Matching Familiar Figures Test (MFF). Reflective children detected significantly more inconsistencies than impulsive children across grade levels. Although there were no significant reflective-impulsive differences on the overall recall/comprehension test, reflectives recalled significantly more information necessary for identifying the inconsistencies. These results are interpreted in an analytic-global processing framework. It is argued that comprehension monitoring failure of impulsives is in part due to their failure to adopt a suitable analytic reading strategy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Standard atomic weights of the elements (1988)

Standard atomic weights of the elements (1988)     

Relation among error detection, sentence verification, and low-level reading skills of fourth graders.

The author explored the relation among low-level reading skills, sentence verification, and error detection in 4th graders. Literal text comprehension was measured with the Sentence Verification Technique (J. M. Royer, in press) procedure. A higher (strategic) level of text comprehension was assessed with the error detection paradigm. Thus low- and high-level text comprehension were correlated with low-level reading skill: decoding, lexical access, verbal working memory span, and each other. Although literal text comprehension and low-level reading measures were correlated, both were uncorrelated with error detection. A second study deomonstrated that 4th graders' error detection was best predicted by their tendency to generate inferences while reading. These data suggest that although literal text comprehension is dependent on low-level reading processes, strategic reading competence reflects the 4th grader's tendency to go beyond literal information in a text. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A low-cost Mr compatible ergometer to assess post-exercise phosphocreatine recovery kinetics

Objective

To develop a low-cost pedal ergometer compatible with ultrahigh (7 T) field MR systems to reliably quantify metabolic parameters in human lower leg muscle using phosphorus magnetic resonance spectroscopy.

Materials and methods

We constructed an MR compatible ergometer using commercially available materials and elastic bands that provide resistance to movement. We recruited ten healthy subjects (eight men and two women, mean age ± standard deviation: 32.8 ± 6.0 years, BMI: 24.1 ± 3.9 kg/m²). All subjects were scanned on a 7 T whole-body magnet. Each subject was scanned on two visits and performed a 90 s plantar flexion exercise at 40% maximum voluntary contraction during each scan. During the first visit, each subject performed the exercise twice in order for us to estimate the intra-exam repeatability, and once during the second visit in order to estimate the inter-exam repeatability of the time constant of phosphocreatine recovery kinetics. We assessed the intra and inter-exam reliability in terms of the within-subject coefficient of variation (CV).

Results

We acquired reliable measurements of PCr recovery kinetics with an intra- and inter-exam CV of 7.9% and 5.7%, respectively.

Conclusion

We constructed a low-cost pedal ergometer compatible with ultrahigh (7 T) field MR systems, which allowed us to quantify reliably PCr recovery kinetics in lower leg muscle using ³¹P-MRS.

     

Relationship between acid value of extracted fatty matter and age of green coffee beans

The work described in this paper was aimed at attempts to determine the changes in the acidity of the fatty matter of green coffee beans during storage under tropical conditions, and to relate them to the age of coffee beans, and to the panel assessment of colour and cup-test of the roasted coffee. On the basis of systematic studies a relationship between acid value and coffee age has been found. The coffee beans stored under tropical conditions for up to 4 years showed relatively large increases in acid value, which correlated with average responses of the tasters. In comparison, samples stored under European conditions showed lesser increases in acid value over 5 years, and little change in taste assessment. The determination of acid value is considered to be a useful objective quality control test.     

How do the efficiencies of reading subcomponents relate to looking back in text?

The compensatory-encoding model of reading suggests that experienced readers compensate metacognitively for inefficient reading subcomponents or cognitive resource limitations. For instance, readers with less efficient access to information in working memory are predicted to look back in text more than those with more efficient access to information in working memory. Both groups of readers still have good comprehension. One hundred nine adult readers were measured on the efficiencies of selected reading subcomponents. Texts were read from a computer screen 1 sentence at a time. The extent to which readers looked back in text (reread sentences) was noted. Those with more efficient access to information in verbal working memory looked back less, consistent with the model. Theoretical and educational implications are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Flammability and thermal properties of rigid polyurethane foams with additionally introduced cyclic structures

Flammability, smoke evolution, thermal, and thermomechanical properties of low-density rigid polyurethane foams obtained from different aromatic polyols were investigated. The foams were prepared according to a standard formulation ensuring the same foam phosphorus content. Cellular polyurethanes with the best fire resistance were obtained from polyols containing disubstituted naphthalene and biphenyl rings. A linear equation was proposed to describe the influence of various structural units of the polyurethane (the content of cyclic structures C_c, nitrogen content C_N, and crosslinking equivalent M_c) upon its flammability, expressed in terms of its oxygen index (OI) Thermal stability of crosslinked polyurethanes was not found to influence significantly their thermomechanical properties, while crosslink density and the type and quantity of cyclic structures additionally introduced did have a pronounced effect upon these properties.     

Standard atomic weights of the elements (1988)

Standard atomic weights of the elements (1988)     

Resistive switching of HfO2-based Metal-Insulator-Metal diodes: Impact of the top electrode material

This paper deals with the impact of the top metal electrode on the resistive switching properties of HfO₂-based Metal-Insulator-Metal diodes. By screening five different metals as top electrode, Al-Cu-Hf-Pt-Ti, we have demonstrated the feasibility of the resistive switching effect on HfO₂. Metals with a low enthalpy of formation of oxides ΔH_f⁰ (Pt and Cu) lead to uni-polar switching whereas easily oxidizable metals with a higher ΔH_f⁰ (Al, Hf and Ti) lead to bipolar switching. Cu-, Hf- and Pt-based devices show a degradation of the top electrode after the forming step by the formation of bubbles whereas such phenomenon was not observed in Al- and Ti-based devices. 200 switching cycles were performed on each device in order to extract the main parameters of the resistive switching effect: I_ON and I_OFF currents in the mA range, R_OFF/R_ON resistance ratio up to 5, V_set and V_reset, voltage levels around 1 V, and powers dissipated during read and write operations in the μW and mW range, respectively. For all systems, the reset process dissipates higher power than the set process. From these results, the Ti top adlayer shows the best performance in terms of stability and resistive switching characteristics.