Hybrid Photopatterned Enzymatic Reaction (HyPER) for in Situ Cell Manipulation

The ability to design artificial extracellular matrices as cell‐instructive scaffolds has opened the door to technologies capable of studying the fate of cells in vitro and to guiding tissue repair in vivo. One main component of the design of artificial extracellular matrices is the incorporation of biochemical cues to guide cell phenotype and multicellular organization. The extracellular matrix (ECM) is composed of a heterogeneous mixture of proteins that present a variety of spatially discrete signals to residing cell populations. In contrast, most engineered ECMs do not mimic this heterogeneity. In recent years, photo‐deprotection has been used to spatially immobilize signals. However, this approach has been limited mostly to small peptides. Here we combine photo‐deprotection with enzymatic reaction to achieve spatially controlled immobilization of active bioactive signals that range from small molecules to large proteins. A peptide substrate for transglutaminase factor XIII (FXIIIa) was caged with a photo‐deprotectable group, which was then immobilized to the bulk of a cell‐compatible hydrogel. With focused light, the substrate can be deprotected and used to immobilize patterned bioactive signals. This approach offers an innovative strategy to immobilize delicate bioactive signals, such as growth factors, without loss of activity and enables in situ cell manipulation of encapsulated cells.     

Fluorescent Nanodiamonds Embedded in Biocompatible Translucent Shells

High pressure high temperature (HPHT) nanodiamonds (NDs) represent extremely promising materials for construction of fluorescent nanoprobes and nanosensors. However, some properties of bare NDs limit their direct use in these applications: they precipitate in biological solutions, only a limited set of bio‐orthogonal conjugation techniques is available and the accessible material is greatly polydisperse in shape. In this work, we encapsulate bright 30‐nm fluorescent nanodiamonds (FNDs) in 10–20‐nm thick translucent (i.e., not altering FND fluorescence) silica shells, yielding monodisperse near‐spherical particles of mean diameter 66 nm. High yield modification of the shells with PEG chains stabilizes the particles in ionic solutions, making them applicable in biological environments. We further modify the opposite ends of PEG chains with fluorescent dyes or vectoring peptide using click chemistry. High conversion of this bio‐orthogonal coupling yielded circa 2000 dye or peptide molecules on a single FND. We demonstrate the superior properties of these particles by in vitro interaction with human prostate cancer cells: while bare nanodiamonds strongly aggregate in the buffer and adsorb onto the cell membrane, the shell encapsulated NDs do not adsorb nonspecifically and they penetrate inside the cells.     

Evaluation of fibre optic sensors for structural condition monitoring

This paper presents fibre optic sensing technology for strain monitoring of engineering materials and structures. The research program consisted of laboratory tests including thermal tests, tensile tests and flexural tests, and a field application on a concrete bridge deck (Joffre Bridge) reinforced partly with fiber reinforced polymers (FRP). Four types of Fabry-Perot fibre optic sensors were investigated and compared to other types of strain gauges including Bragg fibre optic sensors and resistance strain gauges. Typical field monitoring results from the static and dynamic tests using calibrated-truck loads on the Joffre Bridge are also presented in this paper. Experimental and field monitoring results show that Fabry-Perot fibre optic sensors perform linearly and show good response to thermal variations and mechanical loading conditions. The fibre optic sensing technology shows an enhanced accuracy and has potential for significant improvement in the long-term monitoring of strain levels in field applications over conventional strain gauges. It is a promising technique for long-term ‘health’ monitoring of new and rehabilitated structures.     

The confirmability and disconfirmability of trait concepts revisited: Does content matter?

M. Rothbart and B. Park (1986) demonstrated that, consistent with the common negativity bias, positive traits are difficult to confirm and easy to disconfirm, whereas the opposite is true for negative traits. This article extends their analysis by showing that trait (dis-)confirmability is moderated by trait content (warmth vs. competence). Study 1 identifies a trait sample representative of warmth and competence. Study 2 shows a strong negativity effect for warmth and a reduced (or absent) negativity effect for competence. Study 3 examines trait properties related to the behavioral range of the trait possessor and to the motivational goals of the perceiver as predictors of trait (dis-)confirmability. The theoretical and practical implications of the authors' findings are discussed, and avenues for future research are suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social acceptance of carbon dioxide storage

This article discusses public acceptance of carbon capture and storage (CCS). Responses by citizens are described in relation to responses by professionally involved actors. Interviews with members of the government, industry and environmental NGOs showed that these professional actors are interested in starting up storage projects, based on thorough evaluation processes, including discussions on multi-actor working groups. As appeared from a survey among citizens living near a potential storage site (N=103), public attitudes in general were slightly positive, but attitudes towards storage nearby were slightly negative. The general public appeared to have little knowledge about CO₂-storage, and have little desire for more information. Under these circumstances, trust in the professional actors is particularly important. NGOs were found to be trusted most, and industry least by the general public. Trust in each of the three actors appeared to depend on perceived competence and intentions, which in turn were found to be related to perceived similarity of goals and thinking between trustee and trustor. Implications for communication about CCS are discussed.     

Doped silicon under uniaxial tensile strain investigated by PAC

The recent application of strained silicon into transistor design has led to significant progress in increasing the performance of devices. However, up to now little is known about the mechanical behaviour of the strained Si layers and the elastic properties of the deformed semiconductor lattice. The perturbed angular correlation method is ideally suited to study strain related local phenomena in silicon using the acceptor ¹¹¹In as probe. In the past, the influence of external uniaxial strain on In acceptors in pure Si and on donor-acceptor pairs in silicon has been investigated intensively (G. Marx, R. Vianden, Phys. Lett. A210, 364 1996; G. Tessema, PhD thesis, University of Bonn, 2003). In the course of these studies it was found that the unpaired indium probes on regular lattice sites showed an unexpected reaction to uniaxial strain, which depended on the dopant species. Our current experiments reveal that the tension induced local deformation around the In probe atoms also depends on the concentration of the co-implanted donors suggesting a local change of the elastic properties of silicon. In addition, the reaction of the silicon lattice to tensile strain applied along different crystal axes showed strong differences.     

In-situ observations of phase transformations in titanium

An in-situ laser-scanning confocal microscopy study has been undertaken on the phase transformations in highpurity titanium. Observations of the β-Ti to α-Ti were observed to proceed with a pronounced Widmanstätten plate morphology due to the large β-Ti grain size. An anomalous transformation was also observed, with the α-Ti growing with a defined ledge-like surface relief. The observed transformation morphologies are discussed with reference to the crystallography of the regions, analyzed using electron-backscatter diffraction.     

Simplified correlation models for CO/H2 chemical reaction times

This paper provides simplified correlation models for CO/H₂ chemical reaction times. The procedure used for the CO/H₂ simplified modeling utilized the full chemical kinetics mechanism run over a range of temperatures from 700 to 1800 K, pressures from 0.5 to 50 atm, mixtures from 0% to 95% CO, and equivalence ratios from 0.2 to 2.0 to determine ignition (or reaction) time. The correlations for ignition times are given in formulas as functions of equivalence ratio, temperature, and pressure. Two different forms of correlations were obtained, one being a single, overall correlation and the other a two-stage correlation representing regions of high and low temperatures. These correlations are shown to work well over a range of chemical time scales spanning ten orders of magnitude. The correlations are also compared with measured data from the literature.