Toughened carbon fiber fabric‐reinforced pCBT composites

Toughened carbon fiber‐fabric reinforced polymerized cyclic butylene terephthalate (pCBT) composites were obtained by chemical modification of cyclic butylene terephthalate (CBT) with small amounts of epoxy resin and isocyanates as chain extenders. Homogeneous CBT/epoxy and CBT/isocyanate blends were prepared by melt blending the components in a lab‐scale batch mixer at low temperatures and high shear rate. Melt blending was stopped before the ring‐opening polymerization of CBT could start. The modified CBT was the starting material for carbon fiber fabric‐reinforced pCBT composites (fiber content at about 65 wt%) which were prepared by ring‐opening polymerization during compression molding using a simple powder prepreg method. Interlaminar shear strength, flexural strength, and failure strain of the chemically modified composites increased up to 60% with respect to unmodified pCBT composites. Nevertheless, the flexural moduli slightly decreased due to the toughening effect of the chain extender on the pCBT matrix. Drop weight impact tests revealed that the energy absorption of the modified composites was relatively higher as compared to unmodified pCBT composites. POLYM. COMPOS., 37:1453–1460, 2016. © 2014 Society of Plastics Engineers     

Effect of modified layered silicates on the confined crystalline morphology and thermomechanical properties of poly(ethylene oxide) nanocomposites

In this work, poly(ethylene oxide) (PEO)/organoclay nanocomposites with three different types of nanoclays (Cloisite 30B, Somasif JAD400, and Somasif JAD230) were prepared by melt mixing with a laboratory kneader followed by compression molding. The nanocomposites were characterized by atomic force microscopy and scanning electron microscopy. Their crystallization behavior on a hot stage was investigated with polarized optical microscopy. The size and regularity of the spherulites of the PEO matrix were altered significantly by the incorporation of Cloisite 30B, but there was not as much variation with the other two clays. The dynamic viscoelastic behavior of the PEO/organoclay nanocomposites was assessed with a strain‐controlled parallel‐plate rheometer. The effects of clay modification on the thermomechanical and rheological properties were addressed. The reinforcing effect of the organoclay was determined with dynamic mechanical analysis and tensile testing. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of polypropylene homocomposites: Exploiting polymorphism of PP homopolymer

In this study, the properties of polypropylene (PP) homocomposites, prepared by film‐stacking followed by hot pressing, were investigated. Alpha‐ and beta‐PP served as matrices, whereas highly oriented PP tapes of the alpha form acted as reinforcement in the homocomposites. Tapes with different draw ratios (DR = 6–12) have been produced and characterized by mechanical and wide‐angle X‐ray scattering measurements. Tapes with a DR = 8 were incorporated in a cross‐ply (CP) manner in the corresponding homocomposite laminates. Specimens were subjected to static (tensile, flexural) and dynamic (instrumented falling weight impact, IFWI) tests. The thermal and thermomechanical properties of the PP tapes and homocomposites were studied by differential scanning calorimetry and dynamic mechanical thermal analysis. The homocomposite morphology was probed by polarized light microscopy, which gave evidence of transcrystalline layer at the interface between tape and matrix. The storage modulus of the CP homocomposites was improved prominently by the tape reinforcement. In static tensile tests, the homocomposites exhibited much higher stiffness and strength when compared with the neat PP specimens. However, this was accompanied with a marked reduction in the ultimate elongation. The IFWI tests showed that both alpha‐ and the beta‐PP failed in macroscopically brittle manner, whereas the corresponding homocomposites failed in semiductile way. The homocomposite laminates prepared with beta‐PP matrix exhibited higher resistance to penetration than those with alpha‐PP. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Optical gain in 1.3-μm electrically driven dilute nitride VCSOAs

We report the observation of room-temperature optical gain at 1.3 μm in electrically driven dilute nitride vertical cavity semiconductor optical amplifiers. The gain is calculated with respect to injected power for samples with and without a confinement aperture. At lower injected powers, a gain of almost 10 dB is observed in both samples. At injection powers over 5 nW, the gain is observed to decrease. For nearly all investigated power levels, the sample with confinement aperture gives slightly higher gain.     

Parameter Sweep Workflows for Modelling Carbohydrate Recognition

Carbohydrate recognition is a phenomenon critical to a number of biological functions in humans. Understanding the dynamic behaviour of oligosaccharides should help in the discovery of the mechanisms which lead to specific and selective recognition of carbohydrates by proteins. Computer programs which can provide insight into such biological recognition processes have significant potential to contribute to biomedical research if the results of the simulation can prove consistent with the outcome of conventional wet laboratory experiments. In order to validate these simulation tools and support their wider uptake by the bio-scientist research community, high-level easy to use integrated environments are required to run massively parallel simulation workflows. This paper describes how the ProSim Science Gateway, based on the WS-PGRADE Grid portal, has been created to execute and visualise the results of complex parameter sweep workflows for modelling carbohydrate recognition.     

Living carbocationic polymerization

Mono- and bifunctionaltert-alcohols, i.e., cumyl alcohol (CumOH), 2,4,4-trimethyl-2-pentanol (TMPOH), 2,6-dihydroxy-2,4, 4, 6-tetramethylheptane (TMHDiOH), in conjunction with BCl₃ have been shown to be efficient initiating systems for the living polymerization of isobutylene (IB) in CH₃Cl or CH₂Cl₂ solvents in the –10° to –80°C range. The living nature of the polymerizations was demonstrated by linear M_n versus amount of polyisobutylene (PIB) formed (W_PIB) plots starting at the origin and corresponding horizontal number of PIB moles formed (N) versus W_PIB plots. Quenching with methanol producestert-chlorine terminated PIBs. Quantitative dehydrochlorination of the latter products yields exo-olefin (isopropylidene) end groups. These experiments demonstrate that living carbocationic polymerizations have in fact been conducted in these laboratories long ago (1) without having been recognized as such.     

A psychometric study of the McMaster Family Assessment Device in psychiatric, medical, and nonclinical samples.

Investigated the psychometric properties of the McMaster Family Assessment Device (FAD [N. Epstein et al; see PA, Vol 71:2891]), a multidimensional measure of family functioning, using data from psychiatric (n?=?1,138), nonclinical (n?=?627), and medical (n?=?298) samples. Internal scale reliabilities and factorial validity were assessed for each group, and results were compared across groups. In general, scale reliabilities were favorable and the hypothesized factor structure of the FAD was supported. Results also support the use of the 60-item version over the original 53-item version. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assessment of edema using STIR+ via 3D cardiovascular magnetic resonance imaging in patients with suspected myocarditis

Objective

To evaluate three-dimensional T2-weighted fast spin echo triple inversion recovery sequences (STIR+) for the diagnosis of myocardial edema in patients with suspected early myocarditis after respiratory or gastrointestinal tract viral infection and at follow-up.

Materials and methods

We prospectively examined 28 patients with suspected myocarditis and 37 controls matched for gender and age. An ECG-triggered STIR+ was used to cover the entire left ventricle in short-axis images with 10-mm slice thickness and no interslice gap. The global signal intensity ratio (heart muscle in relation to skeletal muscle) was calculated (global STIR+ ratio) to evaluate edema. All patients had repeat examinations at follow-up (mean interval 4.9 months, 1–12 months).

Results

The mean global STIR+ ratio was 2.15 ± 0.4 in the initial examination of patients as compared to 1.78 ± 0.3 in controls (p < 0.0001) and 1.89 ± 0.3 in patients at follow-up (p = 0.0001 vs. first visit). Left ventricular ejection fraction did not differ between patients and controls at baseline and at follow-up.

Conclusion

We could identify a significantly higher global STIR+ ratio in patients with suspected myocarditis compared to controls, and a dynamic change during follow-up. The global STIR+ ratio may, therefore, be useful for the diagnosis of myocarditis and should be further explored.