Quantitative elemental localisation in leaves and stems of nickel hyperaccumulating shrub Hybanthusfloribundus subsp. floribundus using micro-PIXE spectroscopy

Hybanthusfloribundus (Lindl.) F.Muell. subsp. floribundus is a native Australian nickel (Ni) hyperaccumulating shrub and a promising species for rehabilitation and phytoremediation of Ni tailings. Spatial localisation and quantification of Ni in leaf and stem tissues of H.floribundus subsp. floribundus was studied using micro-proton-induced X-ray emission (micro-PIXE) spectroscopy. Young plants, grown in a potting mix under controlled glasshouse conditions were exposed to Ni concentrations of 0 and 26 mM kg⁻¹ for 20 weeks. Leaf and stem samples were hand-sectioned and freeze-dried prior to micro-PIXE analysis. Elemental distribution maps of leaves revealed Ni concentration of 7800 mg kg⁻¹ dry weight (DW) in whole leaf sections, which was identical to the bulk tissue analysis. Elemental maps showed that Ni was preferentially localised in the adaxial epidermis (10,000 mg kg⁻¹ DW) and reached a maximum of up to 10,000 mg kg⁻¹ DW in the leaf margin. Freeze-dried stem sections from the same plants contained lower Ni than leaf tissues (1800 mg kg⁻¹ versus 7800 mg kg⁻¹ DW, respectively), however did not resolve a clear pattern of compartmentalisation across different anatomical regions. Our results suggest localisation in epidermal cells is an important physiological mechanism involved in Ni accumulation and tolerance in leaves of H.floribundus subsp. floribundus.     

Effect of object onset on the distribution of visual attention.

There now exists considerable evidence to suggest that the appearance of a new object in the visual field captures visual attention. One of the consequences of this attentional capture is that the object initiates a redistribution of attentional resources across visual space. This is classically observed in the precuing paradigm in which the onset of an abrupt cue influences the processing of a subsequently presented target. The present research describes a new phenomenon that occurs as a result of a new object appearing in the visual field. A stimulus presented in a region of space adjacent to a comer of an onsetting object receives an enhancement of processing relative to a stimulus presented adjacent to one of the object's straight edges. With the use of 2 converging methods, evidence is presented that suggests that the effect is a higher order attentional phenomenon whereby greater resources become directed to the comers of objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Situational Reengineering: Case Study Analysis

Owners and contractors faced with the drastic consequences of a “crisis” often accomplish projects whose short schedules, tight budgets, or technical complexity require adoption of extraordinary approaches to design and construction. Crisis or “exceptional” projects occur for many reasons; industrial accidents or acts of God cause damage to crucial manufacturing capacity or changes in the economy or international markets require a rapid product to market cycle. Often, these crisis projects are completed in record time, with superior quality or within a very low budget. It is also common on exceptional projects for strategies that are designed to (say) reduce schedule, to exhibit collateral beneficial impacts on the project's cost or quality. The research reported herein, investigates 30 exceptional projects to identify and document work process changes and their impact on cost and schedule as compared to traditional projects of similar scope and complexity. Results illustrate that changing work processes and providing appropriate cultural environments can result in significant schedule reduction (35%) with no increase in project costs. Additionally, over half of the exceptional projects studied demonstrate a reduction in cost as well as a reduced schedule. Fundamentally, this paper demonstrates the efficacy of ingenious and innovative changes to existing work paradigms in response to a variety of situational requirements. Additionally, this paper includes a discussion of barriers to implementation and organizational issues surrounding situational reengineering.     

Multicultural competence: Criteria and case examples.

How do you as a professional psychologist know if you are competent to treat clients whose cultural origins and values differ from your own? What awareness, knowledge, and skills do you need? With whom should you consult? When should you refer? Adopting an idiographic, inclusive approach, the authors identify 12 minimal multicultural competencies for practice and illustrate their usefulness through 3 case examples. Suggestions for how professional psychologists can augment and evaluate their own multicultural competencies are offered as well as implications for professional psychology educators. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Design equations for optimized PEM fuel cell electrodes

This paper presents simple mathematical expressions that can be used for optimizing fuel cell electrode structures, specifically polymer electrolyte membrane fuel cells (PEMFCs). Based on the effectiveness factor, equations relate current density to catalyst utilization and a mass transfer coefficient. These can be used to screen new materials or identify which specific processes need to be improved in an existing electrode design. The optimum thickness, or catalyst loading, and maximum current that can be achieved with a given set of materials can be calculated from a simple set of equations based on the mass transfer characteristics of the electrode materials. These methods can save considerable experimental time and cost during electrode development.     

Characterization of Poly(Aminosiloxane) Surface Chemistry on Aluminum Oxide

N-2-aminoethyl-3-aminopropyltrimethoxysilane (AAPS) was shown to react with aluminum oxide powder to form an amine/carbonate salt, as observed by diffuse reflectance infrared spectroscopy (DRIFT) and thermogravimetric analysis with mass spectroscopy (TGA-MS). TGA-MS, together with electron spectroscopy for chemical analysis (ESCA), reveal that the stoichiometric ratio of amine salt to free amine is higher on the surface of aluminum oxide powder than in a comparable neat film. In addition, TGA-MS shows that a nonstoichiometric ratio of CO₂H₂O is evolved upon heating the surface-treated powder (4.5/1), whereas the neat film evolves CO₂/H₂O at a ratio near unity. The high fraction of protonated amines, together with the higher ratio of CO₂/H₂O in the presence of alumina, is consistent with a proposed bonding mechanism which involves carbonate bridging between protonated amines and hydroxyl sites on the aluminum oxide surface.     

Passive alignment optical subassemblies for military/aerospacefiber-optic transmitter/receiver modules

Under the DARPA sponsored Avionics Optoelectronic Module Technology program, new passive alignment carrier (PAC) optical subassemblies (LED-PAC and PIN-PAC) ruggedized for military/aerospace avionics fiber-optic transmitter and receiver applications have been developed, LED-PAC and PIN-PAC silicon micro-optical bench substrates were fabricated together on a 5 in diameter silicon wafer via multistage photolithography, thin-film, and substrate processing. Alignment v-grooves designed for passive optical alignment of 100/140 μm multimode optical fiber to the optoelectronic devices were terminated by solder locking the fiber to the silicon PAC substrates. The LED-PAC comprising a surface emitting LED die-bonded onto a novel precision molded AM submount passively mounted onto the silicon microbench achieves the required high coupling efficiency to 100/140 μm multimode optical fiber to meet stringent avionics transmitter output power requirements. The 100/130 μm multimode optical fiber-pigtailed PIN-PAC with a refractive lens etched into the p-i-n photodiode backside surface exhibited responsivities greater than 0.8 A/W at 1.3 μm wavelength. The LED-PAC and PIN-PAC optical subassemblies integrated with Boeing ARINC 636 (FDDI) transmitter and receiver thick film multichip (MCM-C) circuitry are capable of meeting both ARINC 636 and FDDI physical layer requirements     

Enzyme Directed Templating of Artificial Bone Mineral

Bone is one of Nature's most remarkable materials, not only for its mechanical properties but also for its ability to repair fractures and remodel its microstructure in response to stress. At the nanoscale bone is a supramolecular matrix of collagen fibers reinforced by hydroxyapatite crystals with a high degree of order. Emulating elements of the biological synthesis of this composite could help develop strategies for advanced materials. Previous work has demonstrated the use of functionalized peptide amphiphile nanofibers in a two-dimensional system to emulate hydroxyapatite mineralization in natural bone. We describe here an artificial, in vitro biomineralization process that allows a similar process to occur in three dimensions. The system employs the natural enzyme alkaline phosphatase and a phosphorylated, anionic nanofiber gel matrix to template hydroxyapatite nanocrystals with size, shape, and crystallographic orientation resembling natural bone mineral. The formation of this biomimetic mineral in three dimensions results from the synergy of fiber-induced nucleation and the temporal control of phosphate ion harvesting by the enzyme. Gradual enzymatic harvesting of ions for crystal growth and the strong nucleating ability of the phosphorylated fibers suppresses uncontrolled precipitation of mineral. The strategy could lead to biomimetic materials to promote bone regeneration or the synthesis of hybrid materials with crystallographically defined structures.