A Chemodosimetric Probe Based on a Conjugated Oxidized Bis-Indolyl System for Selective Naked-Eye Sensing of Cyanide Ions in Water

A new bis-indolyl-based colorimetric probe has been synthesized. This allows a Michael-type adduct formation for the detection of cyanide ions. The probe shows a remarkable color change from red to colorless upon addition of the cyanide ions in pure water. The cyanide ion reacts with the probe and removes the conjugation of the bis-indolyl moiety of the probe with that of the 4-substituted aromatic ring. This renders the probe colorless. The mechanism of the reaction of the probe with the cyanide ion was established by using 1H and 13C NMR spectroscopy, mass spectrometry, and kinetic studies.

Generalized top-spin analysis and new physics in e(+)e(-) collisions with beam polarization

A generalized top-spin analysis proposed some time ago in the context of the standard model and subsequently studied in varying contexts is now applied primarily to the case of e(+)e(-) -> t (tww) over bar with transversely polarized beams. This extends our recent work with new physics couplings of scalar (S) and tensor (T) types. We carry out a comprehensive analysis assuming only the electron beam to be transversely polarized, which is sufficient to probe these interactions, and also eliminates any azimuthal angular dependence due to the standard model or new physics of the vector (V) and axial-vector (A) type interactions. We then consider new physics of the general four-Fermi type of V and A type with both beams transversely polarized and discuss implications with longitudinal polarization as well. The generalized spin bases are all investigated in the presence of either longitudinal or transverse beam polarization to look for appreciable deviation from the SM prediction in case of the new physics. 90% confidence level limits are obtained on the interactions for the generalized spin bases with realistic integrated luminosity. In order to achieve this we present a general discussion based on helicity amplitudes and derive a general transformation matrix that enables us to treat the spin basis. We find that beamline basis combined with transverse polarization provides an excellent window of opportunity both for S, T and V, A new physics, followed by the off-diagonal basis. The helicity basis is shown to be the best in case of longitudinal polarization to look for new physics effects due to V and A. DOI: 10.1103/PhysRevD.86.114019

Top-spin analysis of new scalar and tensor interactions in e(+) e (-) collisions with transverse beam polarization

The top polarization at the International Linear Collider (ILC) with transverse beam polarization is utilized in the process to probe interactions of the scalar and tensor type beyond the Standard Model and to disentangle their individual contributions. Confidence level limits of 90% are presented on the interactions with realistic integrated luminosity and are found to improve by an order of magnitude compared to the case when the spin of the top quark is not measured. Sensitivities of the order of a few times 10 (-aEuro parts per thousand 3) TeV (-aEuro parts per thousand 2) for real and imaginary parts of both scalar and tensor couplings at and 800 GeV with an integrated luminosity of 500 fb (-aEuro parts per thousand 1) and completely polarized beams are shown to be possible.

Fish inspired biomimetic ionic polymer metal composite pectoral fins using labriform propulsion

Ionic polymer metal composites (IPMC) are a new class of smart materials that have attractive characteristics such as muscle like softness, low voltage and power consumption, and good performance in aqueous environments. Thus, IPMC’s provide promising application for biomimetic fish like propulsion systems. In this paper, we design and analyze IPMC underwater propulsor inspired from swimming of Labriform fishes. Different fish species in nature are source of inspiration for different biomimetic flapping IPMC fin design. Here, three fish species with high performance flapping pectoral fin locomotion is chosen and performance analysis of each fin design is done to discover the better configurations for engineering applications. In order to describe the behavior of an active IPMC fin actuator in water, a complex hydrodynamic function is used and structural model of the IPMC fin is obtained by modifying the classical dynamic equation for a slender beam. A quasi-steady blade element model that accounts for unsteady phenomena such as added mass effects, dynamic stall, and the cumulative Wagner effect is used to estimate the hydrodynamic performance of the flapping rectangular shape fin. Dynamic characteristics of IPMC actuated flapping fins having the same size as the actual fins of three different fish species, Gomphosus varius, Scarus frenatus and Sthethojulis trilineata, are analyzed with numerical simulations. Finally, a comparative study is performed to analyze the performance of three different biomimetic IPMC flapping pectoral fins.

Ratiometric, reversible, and parts per billion level detection of multiple toxic transition metal ions using a single probe in micellar media

We present the selective sensing of multiple transition metal ions in water using a synthetic single probe. The probe is made up of pyrene and pyridine as signaling and interacting moiety, respectively. The sensor showed different responses toward metal ions just by varying the medium of detection. In organic solvent (acetonitrile), the probe showed selective detection of Hg2+ ion. In water, the fluorescence quenching was observed with three metal ions, Cu2+, Hg2+, and Ni2+. Further, just by varying the surface charge on the micellar aggregates, the probe could detect and discriminate the above-mentioned three different toxic metal ions appropriately. In neutral micelles (Brij 58), the probe showed a selective interaction with Hg2+ ion as observed in acetonitrile medium. However, in anionic micellar medium (sodium dodecyl sulfate, SDS), the probe showed changes with both Cu2+ and Ni2+. under UV-vis absorption spectroscopy. The discrimination between these two ions was achieved by recording their emission spectra, where it showed selective quenching with Cu2+.

Two-axis force sensing and control of a Reorientable scanning probe

This paper presents the design and implementation of a reorientable scanning probe that is capable of two-axis force sensing and control in the 2-D scanning (X-Z) plane. The probe is comprised of three major components, namely a compliant manipulator, laser measurement system, and magnetic actuation system. Control of the position and orientation of the probe tip is realized by means of magnetic actuation combined with a novel structural design. The design of the manipulator's compliance and that of the optical path of the laser measurement system together enable achieving sensitivity to lateral (X) forces that is nearly identical to that of normal (Z) forces. The achieved sensitivity ratio, of about 0.6, is significantly higher than that of conventional scanning probe systems. The theoretical bases for the structural design and the sensitivity of the two-axis force sensing system are presented. Subsequently, fabrication of the manipulator is described and the result of experimental evaluation of the scanning probe's features is discussed. The scanning probe is used to access the vertical and re-entrant features on the two sides of a cylindrical micropipette, which are subsequently scanned by regulating the lateral force of tip-sample interaction.

Analysis of grating inscribed micro-cantilever for high resolution AFM probe

We present a mathematical modelling and analysis of reflection grating etched Si AFM cantilever deflections under different loading conditions. A simple analysis of the effect of grating structures on cantilever deflection is carried out with emphasis on optimizing the beam and gratings such that maximum amount of diffracted light remains within the detector area.

Modulation of redox regulatory molecules and electron transport chain activity in muscle of air breathing fish Heteropneustes fossilis under air exposure stress

Responses of redox regulatory system to long-term survival (> 18 h) of the catfish Heteropneustes fossilis in air are not yet understood. Lipid and protein oxidation level, oxidant (H2O2) generation, antioxidative status (levels of superoxide dismutase, catalase, glutathione peroxidase and reductase, ascorbic acid and non-protein sulfhydryl) and activities of respiratory complexes (I, II, III and IV) in mitochondria were investigated in muscle of H. fossilis under air exposure condition (0, 3, 6, 12 and 18 h at 25 A degrees C). The increased levels of both H2O2 and tissue oxidation were observed due to the decreased activities of antioxidant enzymes in muscle under water deprivation condition. However, ascorbic acid and non-protein thiol groups were the highest at 18 h air exposure time. A linear increase in complex II activity with air exposure time and an increase up to 12 h followed by a decrease in activity of complex I at 18 h were observed. Negative correlation was observed for complex III and V activity with exposure time. Critical time to modulate the above parameters was found to be 3 h air exposure. Dehydration induced oxidative stress due to modulation of electron transport chain and redox metabolizing enzymes in muscle of H. fossilis was clearly observed. Possible contribution of redox regulatory system in muscle tissue of the fish for long-term survival in air is elucidated. Results of the present study may be useful to understand the redox metabolism in muscle of fishes those are exposed to air in general and air breathing fishes in particular.

An Efficient Probe for Rapid Detection of Cyanide in Water at Parts per Billion Levels and Naked-Eye Detection of Endogenous Cyanide

A new molecular probe based on an oxidized bis-indolyl skeleton has been developed for rapid and sensitive visual detection of cyanide ions in water and also for the detection of endogenously bound cyanide. The probe allows the naked-eye detection of cyanide ions in water with a visual color change from red to yellow ((max)=80nm) with the immediate addition of the probe. It shows high selectivity towards the cyanide ion without any interference from other anions. The detection of cyanide by the probe is ratiometric, thus making the detection quantitative. A Michael-type addition reaction of the probe with the cyanide ion takes place during this chemodosimetric process. In water, the detection limit was found to be at the parts per million level, which improved drastically when a neutral micellar medium was employed, and it showed a parts-per-billion-level detection, which is even 25-fold lower than the permitted limits of cyanide in water. The probe could also efficiently detect the endogenously bound cyanide in cassava (a staple food) with a clear visual color change without requiring any sample pretreatment and/or any special reaction conditions such as pH or temperature. Thus the probe could serve as a practical naked-eye probe for in-field experiments without requiring any sophisticated instruments.

Differentially Selective Chemosensor with Fluorescence Off-On Responses on Cu2+ and Zn2+ Ions in Aqueous Media and Applications in Pyrophosphate Sensing, Live Cell Imaging, and Cytotoxicity

A new benzoyl hydrazone based chemosensor R is synthesized by Schiff base condensation of 2,6-diformyl-4-methylphenol and phenyl carbohydrazide and acts as a highly selective fluorescence sensor for Cu2+ and Zn2+ ions in aqueous media. The reaction of R with CuCl2 or ZnCl2 forms the corresponding dimeric dicopper(II) Cu-2(R)(CH3O)-(NO3)](2)(CH3O)(2) (R-Cu2+) and dizinc(1) Zn-2(R)(2)](NO3)(2) (R-Zn2+) complexes, which are characterized, as R, by conventional techniques including single-crystal X-ray analysis. Electronic absorption and fluorescence titration studies of R with different metal cations in a CH3CN/0.02 M HEPES buffer medium (pH = 7.3) show a highly selective binding affinity only toward Cu(2+)and Zn2+ ions even in the presence of other commonly coexisting ions such as Ne+, K+, Mg2+, Ca2+, Mn2+, Fe2+, Fe3+, Co2+, Ni2+, Cd2+, and Hg2+. Quantification of the fluorescence titration analysis shows that the chemosensor R can indicate the presence of Cu2+ and Zn2+ even at very low concentrations of 17.3 and 16.5 ppb, respectively. R-Zn2+ acts as a selective metal-based fluorescent sensor for inorganic pyrophosphate ion (PPi) even in the presence of other common anions such as F-, Cl-, Br-, I-, CH3COO-, CO32-, HCO3-, N-3(-), SO42-, PPi, AMP, ADP, and ATP in an aqueous medium. The propensity of R as a bioimaging fluorescent probe to detect Cu2+ and Zn2+ ions in human cervical HeLa cancer cell lines and their cytotoxicity against human cervical (HeLa), breast cancer (MCF7), and noncancer breast epithelial (MCF10a) cells have also been investigated. R-Cu2+ shows better cytotoxicity and sensitivity toward cancer cells over noncancer cells than R and R-Zn2+ under identical conditions, with the appearance of apoptotic bodies.

A Probe for the Selective and Parts-per-Billion-Level Detection of Copper(II) and Mercury(II) using a Micellar Medium and Its Utility in Cell Imaging

A novel colorimetric probe 1 based on the picolyl moiety has been designed and synthesized. Probe 1 is composed of a pyrene and a bispicolyl amine (BPA) unit, in which the BPA moiety acts as a binding unit and the binding phenomenon is sensed from the changes in the signaling subunit. The probe detects Cu2+ specifically in water and both Cu2+ and Hg2+ efficiently in neutral Brij-58 micellar media. The probe shows a color change visible to the naked eye upon addition of metal ions. Notably, in a micellar medium, probe 1 can detect both the Cu2+ and Hg2+ ions even at parts-per-billion levels. Furthermore, the probe shows ratiometric detection of both the metal ions making the sensing quantitative. The two metal ions could be discriminated both visibly under a UV lamp and with the use of fluorescence spectroscopy. The probe could be also used in biological cell lines for the detection of both Hg2+ and Cu2+ ions.

Size Modulation of Colloidal Au Nanoparticles via Digestive Ripening in Conjunction with a Solvated Metal Atom Dispersion Method: An Insight Into Mechanism

Digestive ripening, a postsynthetic treatment of colloidal nanoparticles, is a versatile method to produce monodisperse nanoparticles and to prepare various bimetallic nanostructures. The mechanism of this process is largely unknown. Herein, we present a systematic study conducted using Au nanoparticles prepared by a solvated metal atom dispersion method to probe the mechanistic aspects of digestive ripening. In our study, experimental conditions such as concentration of capping agent, reaction time, and temperature, were found to influence the course of the digestive ripening process. Here it is shown that, during digestive ripening under reflux, nanoparticles within an optimum size window are conserved, and surface etching facilitated mass transfer resulted in monodisperse nanoparticles. Overall, digestive ripening can be considered as a kinetically controlled thermodynamic process.

Optical properties of an inhomogeneously broadened Lambda V-system with multiple excited states

We present a theoretical model using a density matrix approach to show the influence of multiple excited states on the optical properties of an inhomogeneously broadened Lambda V-system of the Rb-87 D2 line. These closely spaced multiple excited states cause asymmetry in absorption and dispersion profiles. We observe the reduced absorption profiles, due to dressed state interactions of the applied electromagnetic fields, which results the Mollow sideband-like transparency windows. In a room temperature vapor, we obtain a narrow enhanced absorption and steep positive dispersion at the line center when the strengths of control and pump fields are equal. Here, we show how the probe transmittance varies when it passes through the atomic medium. We also discuss the transient behavior of our system which agrees well with the corresponding absorption and dispersion profiles. This study has potential applications in controllability of group velocity, and for optical and quantum information processing.

Mycobacterium tuberculosis Rho Is an NTPase with Distinct Kinetic Properties and a Novel RNA-Binding Subdomain

Two mechanisms - factor independent and dependent termination - ensure the completion of RNA synthesis in eubacteria. Factor-dependent mechanism relies on the Rho protein to terminate transcription by interacting with RNA polymerase. Although well studied in Escherichia coli, the properties of the Rho homologs from most bacteria are not known. The rho gene is unusually large in genus Mycobacterium and other members of actinobacteria, having,150 additional residues towards the amino terminal end. We describe the distinct properties of Rho from Mycobacterium tuberculosis. It is an NTPase with a preference for purine nucleoside triphosphates with kinetic properties different from E. coli homolog and an ability to use various RNA substrates. The N-terminal subdomain of MtbRho can bind to RNA by itself, and appears to contribute to the interaction of the termination factor with RNAs. Furthermore, the interaction with RNA induces changes in conformation and oligomerization of MtbRho.

Tuning photoinduced terahertz conductivity in monolayer graphene: Optical-pump terahertz-probe spectroscopy

Optical-pump terahertz-probe differential transmission measurements of as-prepared single layer graphene (AG) (unintentionally hole dopedwith Fermi energy E-F at similar to -180 meV), nitrogen doping compensated graphene (NDG) with E-F similar to -10 meV, and thermally annealed doped graphene (TAG) are examined quantitatively to understand the opposite signs of photoinduced dynamic terahertz conductivity Delta sigma. It is negative for AG and TAG but positive for NDG. We show that the recently proposed mechanism of multiple generations of secondary hot carriers due to Coulomb interaction of photoexcited carriers with the existing carriers together with the intraband scattering can explain the change of photoinduced conductivity sign and its magnitude. We give a quantitative estimate of Delta sigma in terms of controlling parameters-the Fermi energy E-F and momentum relaxation time tau. Furthermore, the cooling of photoexcited carriers is analyzed using a supercollision model which involves a defect mediated collision of the hot carriers with the acoustic phonons, thus giving an estimate of the deformation potential.