A yeast surface display platform for plant hormone receptors: Toward directed evolution of new biosensors

Small-molecule biosensors have major applications in biotechnology and medicine but remain difficult to engineer. Plant hormone receptors represent an attractive platform for engineering such biosensors because their chemically induced dimerization architectures naturally decouple small-molecule sensing and sensor actuation. Rapid biosensor engineering will require quantitative high-throughput screening methods. Here we develop a yeast surface display (YSD) platform for the PYR1/HAB1 abscisic acid sensor of Arabidopsis thaliana. We extensively optimized PYR1 surface display, HAB1 purification, and binding reaction conditions. Our system reproduces previous results with wild-type and engineered receptors, and a mathematical analysis of the PYR1/HAB1 system allows us to infer all binding constants. Critically, we find that a previously engineered PYR1 receptor with altered ligand specificity binds HAB1 with identical affinity, suggesting that substantial reengineering of the PYR1 binding pocket does not compromise sensor actuation. This YSD platform for A. thaliana PYR1/HAB1 will facilitate future biosensor engineering efforts.     

Monitoring the degradation of a solid oxide fuel cell stack during 10,000 h via electrochemical impedance spectroscopy

A 5-cell solid oxide fuel cell stack was tested during 10,000 h of continuous operation with simulated reformate gas as fuel (71 vol.% H₂, 20.7 vol.% CO₂ and 8.3 vol.% steam) under high fuel utilization (73%) and constant current load (0.5 A cm^?2 or 25 A) at 750 °C. In situ electrochemical impedance spectroscopy was used to monitor the evolution of ohmic and polarisation resistances of individual cells in the stack without interrupting the current load. Impedance spectra were recorded on each cell periodically (every 1000 h) or after uncontrolled incidents happened with the test setup. It has been found that the stack degradation is mainly attributed to the increased ohmic resistance, pointing to possible causes such as interconnect corrosion and reduced effective contact areas between cells and interconnects. The degradation rate during the first 5000 h was about 1% kh^?1, but increased afterwards up to 1.5% kh^?1 due to the impact of incidents. Both types of incidents (fuel supply fluctuations and overloading failure of the electronic load) were complicated by inhomogeneous fuel distribution among cells, leading to most probably partial re-oxidation of the anode, accelerating the stack degradation.     

Design, implementation, and deployment of the iKP secure electronicpayment system

This paper discusses the design, implementation, and deployment of a secure and practical payment system for electronic commerce on the Internet. The system is based on the iKP family of protocols-(i=1,2,3)-developed at IBM Research. The protocols implement credit card-based transactions between buyers and merchants while the existing financial network is used for payment clearing and authorization. The protocols are extensible and can be readily applied to other account-based payment models, such as debit cards. They are based on careful and minimal use of public-key cryptography, and can be implemented in either software or hardware. Individual protocols differ in both complexity and degree of security. In addition to being both a precursor and a direct ancestor of the well-known SET standard, iKP-based payment systems have been in continuous operation on the Internet since mid-1996. This longevity-as well as the security and relative simplicity of the underlying mechanisms-makes the iKP experience unique. For this reason, this paper also reports on, and addresses, a number of practical issues arising in the course of implementation and real-world deployment of a secure payment system     

Alloying element nitride stability in iron-based alloys; denitriding of nitrided Fe–V alloys

Recognising the various types of absorbed nitrogen in nitrided iron-based alloys and the lack of accuracy in local composition analysis of the individual nano-sized nitride precipitates (e.g. by atom probe tomography), precise determination of the nitride composition requires so-called denitriding treatments. This study proposes two routes to determine the nanonitride stoichiometry, which are demonstrated by experimental analysis of the denitriding behaviour in hydrogen gas of nitrided, model Fe–V alloys. The minimal nitrogen activity to stabilise the alloying element nitrides MeN in Fe–Me–N alloys is calculated. A strategy is offered to stabilise the alloying element nitrides and to determine the nitrogen content strongly bonded in the nitrides.     

Teaching evidence-based interventions: Perceptions of influences on use in professional practice in school psychology.

This study examined perceptions of school psychologists regarding their use of evidence-based interventions in school settings after completing a graduate course in school-based psychosocial interventions. Ninety-four individuals who completed the course during the 10 years prior to the study were asked to complete a survey that focused on personal and organizational factors affecting the implementation of evidence-based interventions through assessment of (a) the extent of their use of interventions in professional school psychology practice, (b) perceptions of facilitators to implementation, and (c) perceptions of barriers to implementation. Fifty-four responded (a 57% response rate); analyses were conducted on the responses of 34 individuals who indicated that they were currently school psychologists working in schools. Results indicated that school psychologists’ personal beliefs about the interventions influenced their decisions to implement them. Several evidence-based interventions were less likely to be used in urban practice settings. Training in evidence-based interventions should address the personal and contextual issues that are related to implementation, as well as the procedures of the interventions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Atomic Friction Investigations on Ordered Superstructures

We review recent friction measurements on ordered superstructures performed by atomic force microscopy. In particular, we consider ultrathin KBr films on NaCl(001) and Cu(001) surfaces, single and bilayer graphene on SiC(0001), and the herringbone reconstruction of Au(111). Atomically resolved friction images of these systems show periodic features spanning across several unit cells. Although the physical mechanisms responsible for the formation of these superstructures are quite different, the experimental results can be interpreted within the same phenomenological framework. A comparison between experiments and modeling shows that, in the cases of KBr films on NaCl(001) and of graphene films, the tip-surface interaction is well described by a potential with the periodicity of the substrate which is modulated or, respectively, superimposed with a potential with the symmetry of the superstructure.     

Fluorous Iminoalditols: A New Family of Glycosidase Inhibitors and Pharmacological Chaperones

A collection of new reversible glycosidase inhibitors of the iminoalditol type featuring N‐substituents containing perfluorinated regions has been prepared for evaluation of physicochemical, biochemical and diagnostic properties. The vast variety of feasible oligofluoro moieties allows for modular approaches to customised structures according to the intended applications, which are influenced by the fluorine content as well as the distance of the fluorous moiety from the ring nitrogen. The first examples, in particular in the D ‐galacto series, exhibited excellent inhibitory activities. A preliminary screen with two human cell lines showed that, at subinhibitory concentrations, they are powerful pharmacological chaperones enhancing the activities of the catalytically handicapped lysosomal D ‐galactosidase mutants associated with GM1 gangliosidosis and Morquio B disease.     

Mechanical properties and morphology of papers prepared from single-walled carbon nanotubes functionalized with aromatic amides

Carbon nanotube papers (CNT papers, also referred to as “buckypapers”) prepared from chemically functionalized single-walled CNTs are being investigated for their mechanical tensile properties. While the Young’s moduli are unaffected by the functionalization with diazonium salts of aniline or aromatic mono- and bis-amides tensile strengths of CNT papers are found to increase with a growing degree of functionalization, and more pronounced with a growing number of amide groups capable of hydrogen bonding. The importance of hydrogen bonding becomes evident after its inhibition through N-methylation of the amide groups, resulting in a distinct reduction of strength values. Scanning electron micrography indicates that a high degree of functionalization or a high number of amide group results in the formation of domains with aligned CNTs.