High throughput methods for polymer nanocomposites research: Extrusion, NMR characterization and flammability property screening

A large number of parameters influence polymer-nanocomposite performance and developing a detailed understanding of these materials involves investigation of a large volume of the associated multi-dimensional property space. This multi-dimensional parameter space for polymer-nanocomposites consists of the obvious list of different material types under consideration, such as polymer and nano-additive, but also includes interphase surface chemistry, and processing conditions. This article presents combinatorial library design and high-throughput screening methods for polymer nanocomposites intended as flame-resistant materials. Here, we present the results of using a twin-screwn extruder to create composition-gradient library strips of polymer nanocomposites that are screened with a solid-state NMR method to rapidly evaluate the optimal processing conditions for achieving nanocomposite dispersion. In addition, we present a comparison of a new rapid Cone calorimetry method to conventional Cone calorimetry and to the gradient heat-flux flame spread method.     

Secretions of Stingless Bees: The Dufour Gland of Nannotrigona testaceicornis

The Dufour gland of Nannotrigona testaceicornis is a large, wide, pear-shaped sac. The gland secretion consists chiefly of the diterpene ester all-trans-geranylgeranyl acetate (64% of the total), together with a complex mixture of small amounts of cyclic ketals; mono-, sesqui-, and diterpene compounds; acetates; and other oxygenated compounds. Samples of N. testaceicornis collected at two sites in Brazil and one in México shared the same composition of their glands, suggesting that the species is uniform over this wide geographical area.     

Automated Two-Axes Optical Fiber Alignment Using Grayscale Technology

In this paper, we report a new method for actuating an optical fiber in two axes. This device enables in package active alignment of an optical fiber towards reducing the time and cost of optoelectronic packaging by eliminating the need for expensive and slow macroalignment machines. Opposing comb-drive actuators with integrated three-dimensional (3-D) wedges (fabricated using grayscale technology) create a dynamic v-groove to alter the horizontal and vertical alignment of an optical fiber cantilever. All structural components are fabricated in silicon using a single lithography and dry-etching step, making the system conducive to batch fabrication, an essential element to minimize the cost of including in-package alignment capabilities. Actuation of a cleaved fiber tip greater than 30 mum in each direction is demonstrated, with automated fiber alignment times on the order of 10s, comparable to those achieved using macroalignment systems. Alignment tolerances are held below 1.25 mum over a 20-by-20-mum actuation area for the first time. The influences of alignment target location, actuation parameters, and alignment algorithm on total alignment time are also presented     

Status,causes and controls of cyanobacterial blooms in Lake Erie

The Laurentian Great Lakes are among the most prominent sources of fresh water in the world. Lake Erie's infamous cyanobacterial blooms have, however, threatened the health of this valuable freshwater resource for decades. Toxic blooms dominated by the cyanobacterium Microcystis aeruginosa have most recently been one of primary ecological concerns for the lake. These toxic blooms impact the availability of potable water, as well as public health and revenues from the tourism and fishery industries. The socioeconomic effects of these blooms have spurred research efforts to pinpoint factors that drive bloom events. Despite decades of research and mitigation efforts, these blooms have expanded both in size and duration in recent years. However, through continued joint efforts between the Canadian and United States governments, scientists, and environmental managers, identification of the factors that drive bloom events is within reach. This review provides a summary of historical and contemporary research efforts in the realm of Lake Erie's harmful cyanobacterial blooms, both in terms of experimental and management achievements and insufficiencies, as well as future directions on the horizon for the lake's research community.     

Speckle suppression using recursive wavelet transforms

An effective algorithm for digital image noise smoothing using wavelet transform techniques is presented in this paper. This algorithm is more powerful when compared to other existing filtering algorithms in terms of speckle suppression for synthetic aperture radar images where the presence of speckle makes the ratio of standard deviation to mean (STM) very high. Examples show that the original STM of about 0.30 (equivalent to three-look images) can be reduced to 0.05-0.03 (equivalent to more than 100-look images), with a possible small sacrifice of losing some details and narrow edges. The quantitative analysis is carried out and compared with the results of some existing filtering algorithms including median, K nearest neighbour averaging, Lee's multiplicative and Crimmins' geometric filters, showing that imagery filtered by the wavelet transform is the smoothest.     

Evaluation of linear spectral unmixing and ΔNBR for predicting post‐fire recovery in a North American ponderosa pine forest

The Differenced Normalized Burn Ratio (ΔNBR) is widely used to map post‐fire effects in North America from multispectral satellite imagery, but has not been rigorously validated across the great diversity in vegetation types. The importance of these maps to fire rehabilitation crews highlights the need for continued assessment of alternative remote sensing approaches. To meet this need, this study presents a first preliminary comparison of immediate post‐fire char (black ash) fraction, as measured by linear spectral unmixing, and ΔNBR, with two quantitative one‐year post‐fire field measures indicative of canopy and sub‐canopy conditions: % live tree and dry organic litter weight (gm^?2). Image analysis was applied to Landsat 7 Enhanced Thematic Mapper (ETM+) imagery acquired both before and immediately following the 2000 Jasper Fire, South Dakota. Post‐fire field analysis was conducted one‐year post‐fire. Although the immediate post‐fire char fraction (r ² = 0.56, SE = 28.03) and ΔNBR (r ² = 0.55, SE = 29.69) measures produced similarly good predictions of the % live tree, the standard error in the prediction of litter weight with the char fraction method (r ² = 0.55, SE = 4.78) was considerably lower than with ΔNBR (r ² = 0.52, SE = 8.01). Although further research is clearly warranted to evaluate more field measures, in more fires, and across more fire regimes, the char fraction may be a viable approach to predict longer‐term indicators of ecosystem recovery and may potentially act as a surrogate retrospective measure of the fire intensity.     

Collaborative Technology in the Classroom: A Review of the GSS Research and a Research Framework

Over the past several years, a number of research studies have investigated the application of group support system (GSS) technology to the classroom. The purpose of this paper is twofold: (1) to summarize and assess what has been learned from this emerging body of research, and (2) to draw on the GSS and cooperative learning literatures to construct a framework to guide future studies. The review of research studies reported in this paper focuses on comparative studies investigating the synchronous GSS classroom environment. While research findings regarding the impacts of GSS on learning performance are somewhat mixed, early indications are encouraging and suggest that GSS may have a positive impact under certain situations. A framework based on the GSS and cooperative learning research is introduced that identifies the contextual, group process, and outcome factors that researchers may wish to consider when designing and interpreting future research studies in this area.     

Development of a lacticin 3147-enriched whey powder with inhibitory activity against foodborne pathogens.

The broad-spectrum bacteriocin lacticin 3147, produced by Lactococcus lactis DPC3147, is inhibitory to a wide range of gram-positive food spoilage and pathogenic organisms. A 10% solution of demineralized whey powder was fermented with DPC3147 at a constant pH of 6.5. The fermentate was spray dried, and the resulting powder exhibited inhibitory activity. The ability of the lacticin 3147-enriched powder to inhibit Listeria monocytogenes Scott A and Staphylococcus aureus 10 was assessed in buffer at both acidic (pH 5) and neutral (pH 7) pH. In addition, the ability of the powder to inhibit L. monocytogenes Scott A in an infant milk formulation was assessed. Resuspension of approximately 10(8) midexponential phase L. monocytogenes Scott A cells in a 10% solution of the lacticin 3147-enriched powder resulted in a 1,000-fold reduction in viable cells at pH 5 and pH 7 after 3 h at 30 degrees C. In the case of S. aureus 10, resuspension of 2.5 x 10(7) midexponential phase cells in a 15% solution of the lacticin 3147-enriched powder at pH 5 resulted in only a 10-fold reduction in viable cell counts, compared with a 1,000-fold reduction at pH 7, following incubation for 3 h at 30 degrees C. The use of the lacticin 3147 powder in an infant milk formulation resulted in greater than a 99% kill of L. monocytogenes within 3 h at 30 degrees C. These results suggest that this bioactive lacticin 3147 food ingredient may find applications in many different foods, including those with pH close to neutrality.     

Evaluation of prescription opioids using operant-based pain measures in rats.

Opioids are the most effective compounds available for the relief of pain, yet there are a number of side effects that are of great concern to clinicians. For example, opioids are powerful reinforcers, and the treatment of pain using opioids could lead to the development of addiction. In addition, there is an increasing body of literature demonstrating that the repeated administration of opioids could lead to a phenomenon called opioid-induced hyperalgesia (i.e., increased sensitivity to painful stimulation). Studies examining these potential adverse effects are necessary in the development of novel analgesics. Furthermore, most studies of pain sensitivity and pain relief use reflex-based procedures to identify analgesics; however, it is argued here that operant-based procedures provide measures that are more analogous to the human condition (i.e., the mechanisms of pain are similar to those in humans) and should be useful in the assessment of novel analgesics. A series of studies examining the effects of opioids and the influence of variables such as age are discussed to demonstrate the utility of this approach. (PsycINFO Database Record (c) 2010 APA, all rights reserved)