Effect of micronisation and electromagnetic radiation on physical and mechanical properties of Canadian barley

The effect of micronisation (high‐intensity infrared heating) and microwave radiation of normal barley (NB), high‐amylose barley (HAB) and waxy barley (WB) on the physical and mechanical properties was studied. Samples were tempered to 42–45% moisture content and then subjected to infrared or microwave radiation to reduce the moisture content to approximately 10%. The grain surface temperature during radiation was maintained at 100 °C. The changes in physical and mechanical properties were compared with unprocessed samples. Thermal radiation increased slightly the volume of the kernels because of the diffusion of water vapour from inside to the outer surface. These changes resulted in a decrease in particle and bulk densities. Thermal radiation affected the Hunter colour values, as well. The mechanical properties including bio‐yield point, modulus of elasticity and breakage susceptibility were affected by micronisation and microwave heating.     

Exploring the loss of semantic memory in semantic dementia: Evidence from a primed monitoring study.

An on-line primed monitoring study was used in an exploration of the nature of semantic memory loss in a patient (P.P.) with semantic dementia who showed a profound semantic impairment on a range of off-line tasks. Priming for pairs of words taken from a common category (e.g., cat-dog, spade-rake, ruby-emerald) was contrasted with that for word pairs from different categories that were related functionally (e.g., shampoo-hair, broom-floor, theater-play). Control participants showed robust priming for both types of semantic relation. P.P., in contrast, showed a normal priming effect for the functionally related conditions but no priming for category coordinates. This result suggests that P.P.'s semantic memory loss cannot be explained solely as a loss of stored representations or as a problem with deliberate controlled access to that information. Rather, elements of both explanations apply for different kinds of semantic information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Improved clean-up for the determination of lasalocid in 'difficult' food matrices

Methodology has been developed for the determination of lasalocid in analytically 'difficult' matrices such as processed and spiced foods. The procedure was based on an existing silica-based solid-phase extraction (SPE) clean-up to which was added a novel NH 2 SPE step before HPLC with fluorescence detection. Use of the additional step enabled the determination of lasalocid in matrices such as baby food, meat pies ('pasties'), etc. Analysis of these matrices was not possible using the standard clean-up on its own. Chromatography showed a massive reduction in the amount of co-extractives and interferences. Validation data were obtained down to the 10-40 μg kg -1 level for a range of products. Recoveries ranged from 74% at 10 μg kg -1 for pork sausages to 96% at 40 μg kg -1 for meat pies.     

Exceptional Flame Resistance and Gas Barrier with Thick Multilayer Nanobrick Wall Thin Films

Layer‐by‐layer (LbL) assembly is a powerful and versatile technique to deposit functional thin films, but often requires a large number of deposition steps to achieve a film thick enough to provide a desired property. By incorporating amine salts into the cationic polyelectrolyte and its associated rinse, LbL clay‐containing nanocomposite films can achieve much greater thickness (>1 μm) with relatively few deposition cycles (≤6 bilayers). Amine salts interact with nanoclays, causing nanoplatelets to deposit in stacks rather than as individual platelets. This technique appears to be universal, exhibiting thick growth with multiple types of nanoclay, including montmorillonite and vermiculite (VMT), and a variety of amine salts (e.g., hexylamine and diethanolamine). The characteristic order found in LbL‐assembled films is maintained despite the incredible thickness. Films assembled in this manner achieve oxygen transmission rates below 0.009 cc m⁻² d⁻¹ atm⁻¹ with just 6 bilayers (BLs) of chitosan/VMT deposited. These thick clay‐based thin films also impart exceptional flame resistance. A 2‐BL film renders a 3.2 mm polystyrene plate self‐extinguishing, while an 8‐BL film (3.9 μm thick) prevents ignition entirely. This ability to generate much thicker clay‐based multilayers with amine salts opens up tremendous potential for these nanocoatings in real world applications.     

Identification and Characterization of a Welwitindolinone Alkaloid Biosynthetic Gene Cluster in the Stigonematalean Cyanobacterium Hapalosiphon welwitschii

The identification of a 36 kb welwitindolinone (wel) biosynthetic gene cluster in Hapalosiphon welwitschii UTEX B1830 is reported. Characterization of the enzymes responsible for assembling the early biosynthetic intermediates geranyl pyrophosphate and 3‐((Z)‐2′‐isocyanoethenyl)indole as well as a dedicated N‐methyltransferase in the maturation of N‐methylwelwitindolinone C isothiocyanate solidified the link between the wel pathway and welwitindolinone biosynthesis. Comparative analysis of the ambiguine and welwitindolinone biosynthetic pathways in two different organisms provided insights into the origins of diverse structures within hapalindole‐type molecules.     

Media-based effects on the hydrolytic degradation and crystallization of electrospun synthetic-biologic blends

Tissue engineering scaffold degradation in aqueous environments is a widely recognized factor determining the fate of the associated anchorage-dependent cells. Electrospun blends of synthetic polycaprolactone (PCL) and a biological polymer, gelatin, of 25, 50, and 75 wt% were investigated for alterations in crystallinity, microstructure and morphology following widely used in vitro biological exposures. To our knowledge, the effects of these different aqueous-based biological media compositions on the degradation of these blends have never been directly compared. X-ray diffraction (XRD) analysis exposed that differences in PCL crystallinity were observed following exposures to phosphate buffered solution (PBS), Dulbecco’s modified eagle medium (DMEM) cell culture media, and DI water following 7 days of exposure at 37 °C. XRD data suggested that in vitro medium exposures aid in providing chain mobility and rearrangement due to hydrolytic degradation of the gelatin phase, allowing previously constrained, poorly crystalline PCL regions to achieve more intense reflections resulting in the presence of crystalline peaks. The dry, as-spun modulus of relatively soft 100 % PCL fibers was approximately 10 % of any gelatin-containing composition. Tensile testing results indicate that hydrated gelatin containing scaffolds on average had a fivefold increase in elongation compared to as-spun scaffolds. After 24-h of aqueous exposure, the elastic modulus decreased in proportion to increasing gelatin content. After 1 day of exposure, the 75 and 100 % gelatin compositions largely ceased to display measurable values of modulus, elongation or tensile strength due to considerable hydrolytic degradation. On a relative basis, common aqueous in vitro medium exposures (deionized water, PBS, and DMEM) resulted in significantly divergent amounts of crystalline PCL, overall microstructure and fiber morphology in the blended compositions, subsequently ‘shielding’ scaffolds from significant changes in mechanical properties after 24-h of exposure. Understanding electrospun PCL-gelatin scaffold dynamics in different aqueous-based cell culture medias enables the ability to tailor scaffold composition to ‘tune’ degradation rate, microstructure, and long-term mechanical stability for optimal cellular growth, proliferation, and maturation.     

The applicability of ultrasound dynamic receive beamformers to photoacoustic imaging

Ultrasound array transducers offer several advantages over mechanically-scanned transducers for photoacoustic imaging, including high imaging frame rates and dynamic focusing. Development of a photoacoustic array system can be accelerated by adapting existing commercial ultrasound systems and harnessing their performance-enhancing aspects such as parallel beamforming. One challenge faced when adapting commercial ultrasound systems for photoacoustic imaging is that the dynamic delay sequences required for focusing must account for one-way rather than two-way ultrasound wave propagation. Modifying the hardware may be difficult for developers and impossible for users, but some ultrasound systems provide a parameter, c: the speed of sound used to calculate these delays. A linear-array based ultrasound platform with parallel channel acquisition is used to compare experimental point-spread functions produced using an ultrasound beamformer with a scaled value of c to those produced by a photoacoustic beamformer. Scaling c by a factor of √2 provides the best image quality compared with adjustments by 1 and 2, but requires image rescaling, which can be done post-acquisition or by modification of the rendering software. Although optimal focusing is achieved for linear scanning, this is not the case for sector scanning, which requires angular and depth rescaling.     

Compositional changes in whole grain flours as a result of solvent washing and their effect on starch amylolysis

Whole grain flour is used most often as raw material for fuel alcohol production. However, the dry-milling process and the non-starch components of flours may impact the enzymatic hydrolysis of starch to glucose. The particle size distributions of flours prepared from whole grain triticale, barley, wheat and corn were determined and the effects of pre-washing with water, hexane, 100% ethanol or 50% ethanol on flour composition and the amylolysis of starch were studied. Scanning electron microscopy of the flours revealed that grinding grain to pass a sieve with an aperture size of 0.5 mm effectively released starch granules from endosperm cells. Pre-washing with water or 50% ethanol decreased the protein, phytic acid and total free phenolic contents of flours and, except for corn flour, increased starch content. Pre-washing with water reduced the ash contents of all flours, and reduced the ??-glucan content of barley flour by 98%. Pre-washing with hexane or 100% ethanol removed much of the lipid from the flours. Pentosan content was affected only slightly by any of the pre-washing treatments. Each of the pre-washings was associated with a significant change, positive or negative, in the extent of ??-amylolysis for one or more of the flours. The degree of ??-amylolysis in unwashed flours ranged from 22.4 to 26.1%, and from 21.6 to 28.1% in pre-washed flours, varying with flour source and solvent treatment. Pre-washing of flours increased the degree of hydrolysis achieved with sequential ??-amylase/amyloglucosidase treatment, with values ranging from 61.4 to 72.8% in pre-washed flours compared to 56.2-57.8% in unwashed flours. The highest degrees of hydrolysis were achieved with 50% ethanol pre-washing (72.4 and 72.8% for triticale and barley flours, respectively). The degree of ??-amylase/amyloglucosidase hydrolysis obtained for isolated starches ranged from 83.7 to 93.0%. This study demonstrated clearly that the partial removal of non-starch components from whole grain flours by solvent pre-washing enhanced the degree of amylolysis of starch.     

Preparation and properties of bisphenol A polyetherketoneketone based phthalonitrile resins

A promising high temperature phthalonitrile (PN) resin composed of a polyetherketoneketone (PEKK) core bridged by two bisphenol A linkers and end capped with PN groups is presented. This PEKK-PN resin was characterized via differential scanning calorimetry, thermogravimetric analysis, proton nuclear magnetic resonance spectroscopy, scanning electron microscopy, dynamic mechanical analysis, attenuated total reflection Fourier transform infrared, and rheometry. The PEKK-PN resin was evaluated with two different compositions containing 1) 70:30 PEKK-PN to bisphenol A PN (n = 0) and 2) pure PEKK-PN. The 70:30 PEKK-PN resin was mixed with bis[4-(3-aminophenoxy)phenyl]sulfone and exhibited a melt viscosity of 271 cP, much lower than the 657 cP viscosity of the pure PEKK-PN mixture. Void-free PEKK-PN polymers were easily prepared by degassing and curing up to 380°C, resulting in fully crosslinked networks exhibiting thermal stability above 500°C and a 75% char yield. Additionally, the cured PEKK-PN polymer samples displayed good mechanical integrity retaining 50% stiffness at 300°C. This combination of properties suggests these new PEKK-PN resins are excellent materials for high temperature thermosets in composite applications.