Bondi Accretion in the Spherically Symmetric Johannsen-Psaltis Spacetime

The Johannsen-Psaltis spacetime explicitly violates the no hair theorem. It describes rotating black holes with scalar hair in the form of parametric deviations from the Kerr metric. In principle, black hole solutions in any modified theory of gravity could be written in terms of the Johannsen-Psaltis metric. We study the accretion of gas onto a static limit of this spacetime. We utilise a recently proposed pseudo-Newtonian formulation of the dynamics around arbitrary static, spherically symmetric spacetimes. We obtain a potential that generalises the Paczy\'nski-Wiita potential to the static Johannsen-Psaltis metric. We also perform a fully relativistic analysis of the geodesic equations in the static Johannsen-Psaltis spacetime. We find that positive values of the scalar hair parameter, $\epsilon_{3}$, lower the accretion rate and vice versa. Similarly, positive (negative) values of $\epsilon_{3}$ reduce (increase) the gravitational acceleration of radially infalling massive particles.Comment: 13 Pages, 1 figure, submitted to CQ

A Selective and Sensitive Chromogenic and Fluorogenic Detection of a Sulfur Mustard Simulant

A simple and highly selective chromogenic and fluorogenic detection of sulfur mustard (SM) simulants is reported. Dithiol 1, in the presence and absence of a mustard simulant behaves differently toward a squaraine dye (SQ), and thus provides a visual and spectroscopic signal for mustard gas. The sensor responds to the SM simulant, but not to the O-analog of mustard stimulant or nerve agent mimics and other electrophilic agents. The visual and fluorescent detection with less than 50 mu M of SM simulant shows good sensitivity. The utility of the sensor was demonstrated by analysis of SM simulant on surfaces, in soil, and in the gas phase.Office of Naval Research N00014-09-1-1087Welch Foundation F-1151Department of Science and Technology, IndiaDefense Research and Development Organization, IndiaChemistr

Consistent treatment of hydrophobicity in protein lattice models accounts for cold denaturation

The hydrophobic effect stabilizes the native structure of proteins by minimizing the unfavourable interactions between hydrophobic residues and water through the formation of a hydrophobic core. Here we include the entropic and enthalpic contributions of the hydrophobic effect explicitly in an implicit solvent model. This allows us to capture two important effects: a length-scale dependence and a temperature dependence for the solvation of a hydrophobic particle. This consistent treatment of the hydrophobic effect explains cold denaturation and heat capacity measurements of solvated proteins.Comment: Added and corrected references for design procedure in main text (p. 2) and in Supplemental Information (p. 8

Predicting the composition of red wine blends using an array of Multicomponent peptide-based sensors

Differential sensing using synthetic receptors as mimics of the mammalian senses of taste and smell is a powerful approach for the analysis of complex mixtures. Herein, we report on the effectiveness of a cross-reactive, supramolecular, peptide-based sensing array in differentiating and predicting the composition of red wine blends. Fifteen blends of Cabernet Sauvignon, Merlot and Cabernet Franc, in addition to the mono varietals, were used in this investigation. Linear Discriminant Analysis (LDA) showed a clear differentiation of blends based on tannin concentration and composition where certain mono varietals like Cabernet Sauvignon seemed to contribute less to the overall characteristics of the blend. Partial Least Squares (PLS) Regression and cross validation were used to build a predictive model for the responses of the receptors to eleven binary blends and the three mono varietals. The optimized model was later used to predict the percentage of each mono varietal in an independent test set composted of four tri-blends with a 15% average error. A partial least square regression model using the mouth-feel and taste descriptive sensory attributes of the wine blends revealed a strong correlation of the receptors to perceived astringency, which is indicative of selective binding to polyphenols in wine

Rotamer-Restricted Fluorogenicity Of The Bis-Arsenical ReAsH

Fluorogenic dyes such as FlAsH and ReAsH are used widely to localize, monitor, and characterize proteins and their assemblies in live cells. These bis-arsenical dyes can become fluorescent when bound to a protein containing four proximal Cys thiols—a tetracysteine (Cys4) motif. Yet the mechanism by which bis-arsenicals become fluorescent upon binding a Cys4 motif is unknown, and this nescience limits more widespread application of this tool. Here we probe the origins of ReAsH fluorogenicity using both computation and experiment. Our results support a model in which ReAsH fluorescence depends on the relative orientation of the aryl chromophore and the appended arsenic chelate: the fluorescence is rotamer-restricted. Our results do not support a model in which fluorogenicity arises from the relief of ring strain. The calculations identify those As–aryl rotamers that support fluorescence and those that do not and correlate well with prior experiments. The rotamer-restricted model we propose is supported further by biophysical studies: the excited-state fluorescence lifetime of a complex between ReAsH and a protein bearing a high-affinity Cys4 motif is longer than that of ReAsH-EDT2, and the fluorescence intensity of ReAsH-EDT2 increases in solvents of increasing viscosity. By providing a higher resolution view of the structural basis for fluorogenicity, these results provide a clear strategy for the design of more selective bis-arsenicals and better-optimized protein targets, with a concomitant improvement in the ability to characterize previously invisible protein conformational changes and assemblies in live cells

Temporal Control over Transient Chemical Systems using Structurally Diverse Chemical Fuels

The next generation of adaptive, intelligent chemical systems will rely on a continuous supply of energy to maintain the functional state. Such systems will require chemical methodology that provides precise control over the energy dissipation process, and thus, the lifetime of the transiently activated function. This manuscript reports on the use of structurally diverse chemical fuels to control the lifetime of two different systems under dissipative conditions: transient signal generation and the transient formation of self-assembled aggregates. The energy stored in the fuels is dissipated at different rates by an enzyme, which in-stalls a dependence of the lifetime of the active system on the chemical structure of the fuel. In the case of transient signal generation, it is shown that different chemical fuels can be used to generate a vast range of signal profiles, allowing temporal control over two orders of magnitude. Regarding self-assembly under dissipative conditions, the ability to control the lifetime using different fuels turns out to be particularly important as stable aggregates are formed only at well-defined surfactant/fuel ratios, meaning that temporal control cannot be achieved by simply changing the fuel concentration

Compositions and methods for the detection of chemical warfare agents

Compositions for detection of chemical warfare agents that comprise oximate anion reactive sites and fluorophore cores. Methods for detecting a chemical warfare agents that comprise providing a detector molecule comprising an oximate anion reactive site and a fluorophore core and detecting fluorescence from the detector molecule. Methods for enhancing the reactivity of an oximate nucleophile that comprise introducing an oxime into an aprotic solvent and deprotonating the oxime to form the oximate nucleophile with a base that creates noncoordinating anions.Board of Regents, University of Texas Syste