Influence of short dispersed and short integral glass fibres on the mechanical behaviour of textile-reinforced concrete

This article addresses the influence of the addition of short dispersed and short integral fibres made of alkali-resistant (AR) glass on the fracture behaviour of textile-reinforced concrete (TRC) subject to tensile loading. A series of uniaxial, deformation-controlled tension tests was performed to study the strength, deformation, and fracture behaviour of thin, narrow plates made of TRC, both with and without the addition of short fibres. Additionally, uniaxial tension tests on specimens reinforced with only short fibres were performed to figure out the difference in behaviour in the absence of textile reinforcement. Furthermore, multifilament-yarn and single-fibre pullout tests were carried out to gain a better understanding of bonding properties and crack-bridging behaviour. While pronounced enhancement of first-crack stress was achieved due to the addition of short dispersed fibres (the value increased by a factor of 2), a significant improvement in tensile strength was recorded for TRC specimens with the addition of integral glass fibres; the value increased by approximately 30 %. Moreover, TRC specimens reinforced with short dispersed glass fibres showed formation of more and finer cracks in comparison to the specimens with integral fibres. It was also found that short integral fibres can improve the bond between multifilament-yarns and the surrounding matrix by means of “special” cross-links. In TRC with short dispersed fibres this phenomenon was less pronounced. The investigations were accompanied by microscopical investigations which provided additional basis for an in-depth discussion of the decisive working mechanisms of hybrid reinforcement.     

What else could I have done? Patients' responses to failed treatment decisions.

13 successful and 16 failed renal transplant patients (mean age 41.3 yrs) were compared concerning their perceptions of the initial decision to undergo transplantation. Results suggest that, relative to successful transplant Ss, failed transplant Ss recalled the circumstances of the initial decision in a manner that lessened personal responsibility for that decision. They indicated that they had had little choice but to make the decision they had made. There was slight evidence that failed transplant Ss diffused responsibility for the decision or its outcome onto others. It is concluded that cognitive factors may play a role in undermining possible self-recrimination following failed treatment decisions in which a patient has been involved. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis,photodegradation, and energy transfer in a series of poly(ethylene terephthalate–co–2,6-naphthalenedicarboxylate) copolymers

Triplet–triplet energy transfer has been shown to occur from poly(ethylene terephthalate) (PET) units to the 2,6-naphthalenedicarboxylate (2,6-ND) monomer units in a series of poly(ethylene terephthalate–co–2,6-naphthalenedicarboxylate) (PET–2,6-ND) copolymers, as filament yarns, by an exchange mechanism at 77°K. The radius of the “quenching sphere” has been calculated to be 19.7 Å, indicating the presence of triplet energy migration. Photostabilization was observed in the copolymer yarns with the concentration of the monomer dimethyl 2,6-naphthalenedicarboxylate (2,6-DMN) at or above 2 mol %; the rate of phototendering in an air atmosphere was shown to decrease from 2.0 × 10^?19% breaking strength loss/quantum absorbed/cm² in the homopolymer PET to 0.7 × 10^?19% breaking strength loss/quantum absorbed/cm² in the copolymer yarns. The photophysical processes in the monomers, dimethyl terephthalate and 2,6-DMN, were examined by absorption and luminescence studies. The lowest excited singlet and triplet in both monomers were identified to be the ¹(π, π^*) and ³(π, π^*) states, respectively. The phosphorescence of PET was shown to originate from a ³(π, π^*) state, while the complex fluorescence spectrum may arise from some oriented aggregates in the polymer matrix. In copolymer yarns, only the fluorescence emission from the 2,6-ND monomer units at 380 nm was observed. The phosphorescence spectra of the copolymer yarns showed phosphorescence emissions from the PET and 2,6-ND monomer units; in addition, delayed fluorescence from the 2,6-ND monomer was also observed.     

An experimental analysis of a flaring process for tube ends using a novel spinning tool

The flaring of tube ends are typically performed using electromagnetic forming, or punch-and-die method, both of which cost time and effort. In this work, a new method of tube flaring using a metal spinning process is proposed. An experimental study was carried out to flare the end of aluminium tubes. A multifunction tool was designed based on the flaring ratio to widen the tube end. Several flared specimens were conducted at different working conditions. The effects of working conditions such as flaring ratio, axial feed rate (mm/rev), and rotating speed (rpm) on the flaring loads were investigated. An experimental analysis was carried out to illustrate the effect of the working conditions on the characteristics of the formed part. The analysis showed that these working conditions have a clear influence on wall thickness, surface hardness, and flaring loads.     

Functionality dependent olefin activity in acyclic diene metathesis polymerization: mass spectrometry characterization of amino acid functionalized olefins

Mass spectrometry has become an essential tool in delineating the structural properties of a new series of amino acid functionalized acyclic diene metathesis (ADMET) polymers known as bioolefins. These measurements, coupled with the measurement of the polymers chemical and physical properties, assist in the determination of their utility as biomaterials. In the present study, a set of five polymers with different bulk size and electronic properties were chosen for structural analyses by MALDI-TOF, MALDI-FTICR, and DIOS-TOF. The obtained data show that due to the competing metathesis and isomerization during ADMET, depending on their structural properties, the olefins display different selectivity toward main metathesis or isomerized products.     

A top-down framework for watershed model evaluation and selection under uncertainty

This study introduces a top-down strategy for model evaluation and selection under uncertainty in which watershed model structures with increasing complexity are applied to twelve watersheds across a hydro-climatic gradient within the United States (US). The models' complexities and their related assumptions provide an indication of the dominant controls on the watershed response at the inter-annual, intra-annual, monthly, and daily time scales as captured in the water balance signatures (or metrics) used in this study. The ability of the models to capture the water balance signatures is evaluated in an ensemble framework with respect to their reliability (Is the model ensemble capturing the observed signature?) and with their shape (Is the model structure capable of representing an observed signature's variability?). Model selection is automated by combining the reliability and shape performance measures in a fuzzy rule system. Our results suggest that the framework can be tuned to function as a screening tool that formalizes our model selection process. This fuzzy model selection framework enhances our ability to automatically select parsimonious model structures for large databases of watersheds and therefore provides an important step towards understanding how controls on the watershed response vary with landscape and climatic characteristics. This understanding further advances our ability for model-based watershed classification.