Threonine Phosphorylation of an Electrochemical Peptide-Based Sensor to Achieve Improved Uranyl Ion Binding Affinity

We have successfully designed a uranyl ion (U(VI)-specific peptide and used it in the fabrication of an electrochemical sensor. The 12-amino acid peptide sequence, (n) DKDGDGYIpTAAE (c), originates from calmodulin, a Ca(II)-binding protein, and contains a phosphothreonine that enhances the sequence’s affinity for U(VI) over Ca(II). The sensing mechanism of this U(VI) sensor is similar to other electrochemical peptide-based sensors, which relies on the change in the flexibility of the peptide probe upon interacting with the target. The sensor was systematically characterized using alternating current voltammetry (ACV) and cyclic voltammetry. Its limit of detection was 50 nM, which is lower than the United States Environmental Protection Agency maximum contaminant level for uranium. The signal saturation time was ~40 min. In addition, it showed minimal cross-reactivity when tested against nine different metal ions, including Ca(II), Mg(II), Pb(II), Hg(II), Cu(II), Fe(II), Zn(II), Cd(II), and Cr(VI). Its reusability and ability to function in diluted aquifer and drinking water samples were further confirmed and validated. The response of the sensor fabricated with the same peptide sequence but with a nonphosphorylated threonine was also analyzed, substantiating the positive effects of threonine phosphorylation on U(VI) binding. This study places emphasis on strategic utilization of non-standard amino acids in the design of metal ion-chelating peptides, which will further diversify the types of peptide recognition elements available for metal ion sensing applications

Estimating the Spins of Stellar-Mass Black Holes by Fitting Their Continuum Spectra

We have used the Novikov-Thorne thin disk model to fit the continuum X-ray spectra of three transient black hole X-ray binaries in the thermal state. From the fits we estimate the dimensionless spin parameters of the black holes to be: 4U 1543-47, a* = a/M = 0.7-0.85; GRO J1655-40, a* = 0.65-0.8; GRS 1915+105, a* = 0.98-1. We plan to expand the sample of spin estimates to about a dozen over the next several years. Some unresolved theoretical issues are briefly discussed.Comment: 8 pages, 4 figures, 1 table; to appear in "Astrophysics of Compact Objects" eds. Y. F. Yuan, X. D. Li, D. Lai, AI

Linear, redox modified DNA probes as electrochemical DNA sensors

We show here that hybridization-linked changes in the dynamics of a redox-modified, electrode-bound linear (as opposed to stem-loop) probe DNA produce large changes in Faradaic current, allowing for the ready detection of target oligonucleotides

The Economic Impact on Leisure Activities

This study explores the influence of the economic recession on leisure activities because economic impact is a significant factor that can change people’s travel decisions. A methodology, Ridit analysis, is applied in this study, and it adopts cumulative probability scores instead of ordinal scores. Results show that current economic crisis has had an impact on people’s ability to take time away from work

Examining the relationships between perceived value, service quality, satisfaction, and willingness to revisit a theme park

The purpose of the study is to examine the relationships between satisfaction, perceived value, and quality in their prediction of revisiting intention. Furthermore, this study applies Cronin’s (2000) research model to test the relationships, and a structural model (SEM) is used to examine the hypothesized relationships. The results show that service quality has a direct effect on perceived value and satisfaction, perceived value has direct effect on satisfaction, and satisfaction has strong relation to visitors’ willingness to revisit theme parks

SELF-ASSEMBLED MONOLAYERS AND METHODS FOR USING THE SAME IN BIOSENSING APPLICATIONS

Cross - linked amphiphile constructs that form self - as sembled monolayers ( SAMs ) on metal surfaces such as gold surfaces are disclosed . These new SAMs generate well packed and highly oriented monolayer films on gold sur faces . A method for using the SAMs in the fabrication of biomolecule sensors is also disclosed

Perceived strength of forensic scientists’ reporting statements about source conclusions

Three studies investigated lay people’s perceptions of the relative strength of various conclusions that a forensic scientist might present about whether two items (fingerprints, biological samples) have a common source. Lay participants made a series of judgments about which of two conclusions seemed stronger for proving the items had a common source. The data were fitted to Thurstone–Mosteller paired comparison models to obtain rank-ordered lists of the various statements and an indication of the perceived differences among them. The results reveal the perceived strength of several types of statements, relative to one another, including verbal statements regarding strength of support (e.g. ‘extremely strong support for same source’), source probability statements (e.g. ‘highly probable same source’), random match probabilities (e.g. RMP = 1 in 100 000), likelihood ratios, and categorical statements (e.g. ‘identification’). These comparisons in turn provide insight into whether particular statements about the strength of forensic evidence convey the intended meaning and will be interpreted in a manner that is justifiable and appropriate

COMBINED USE OF OSCILLATING MEANS AND ELLIPSOMETRY TO DETERMINE UNCORRELATED EFFECTIVE THICKNESS AND OPTICAL CONSTANTS OF MATERIAL DEPOSITED AT OR ETCHED FROM A WORKING ELECTRODE THAT PREFERRABLY COMPRISES NON - NORMAL ORIENTED NANOFIBERS

Disclosed are systems and methods that enable determination of uncorrelated thickness of a working electrode and surface region optical constants in settings involving electrochemical processing at a working electrodes in a Piezo electric Balance system , by simultaneous application of an Ellipsometer system , the working electrode optionally having a multiplicity of nanofibers that are oriented non normally to a surface of said working electrode . Further disclosed is , simultaneous with said determinations , the monitoring of electrochemical processes at a piezoelectric balance working electrode driven by electrical energy applied between said working electrode and counter electrode

α,ω-Dithiol Oligo(phenylene vinylene)s for the Preparation of High-Quality π-Conjugated Self-Assembled Monolayers and Nanoparticle-Functionalized Electrodes

While thioacetate-terminated oligo(phenylene vinylene)s (OPVs) have been synthesized and employed in applications involving the formation of metal–molecule–metal junctions, the synthesis and application of potentially more versatile α,ω-dithiol OPVs have not previously been described. Here, a thiomethyl-precursor route to the synthesis of α,ω-dithiol OPVs is reported and their ability to form well-ordered self-assembled monolayers (SAMs) without the addition of exogenous deprotection reagents is described. α,ω-Dithiol OPV monolayers exhibit thicknesses consistent with molecular length and are nearly defect-free, as assayed by electrochemical measurements. To demonstrate the ease with which SAMs containing these bifunctional OPVs can, in contrast to thioacetate functionalized OPVs, be further functionalized with materials other than gold, we have modified them in a single step with a sub-monolayer of cadmium selenide nanocrystals (NCs). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) confirm that these NC-modified films are both smooth and uniform over the largest areas investigated (\u3e 10 μm2) and no evidence of NC aggregation is observed. To evaluate the electrochemical response of these metal–molecule– semiconductor assemblies we have fabricated NC-modified OPV SAMs with ferrocene-coated NCs. Variable-frequency alternating current voltammetry indicates that electron transfer in these assemblies is much more rapid than in analogous structures formed using simple alkane dithiols. It thus appears that α,ω-dithiol OPVs are well suited for the formation of high-quality conducting SAMs for the functionalization of gold and other surfaces

Design and Synthesis of a New Class of Twin-Chain Amphiphiles for Self-Assembled Monolayer-based Electrochemical Biosensor Applications

A new class of twin-chain hydroxyalkylthiols (mercaptoalkanols) featuring a nearly constant cross-section and the potential for modification of one or both termini are available with complete regioselectivity through Pd-mediated couplings of benzene diiododitriflate, including an example of a previously unreported coupling to generate an ortho-substituted arene bis acetic acid. Selfassembled monolayers (SAMs) prepared from the new amphiphiles demonstrate improved stability in an electrochemical sensor system compared with monolayers prepared from analogous single chain thiols