A self-powered "sense-act-treat" system that is based on a biofuel cell and controlled by boolean logic

Bio-logic-al: an autonomous, integrated "sense-act-treat" system that is based on an enzymatic biofuel cell has been developed. The system couples a biocomputing logic-detection method with a drug-release system to provide a logic-activated therapeutic intervention in response to a simulated abnormal physiological state, without the need for an external power source, control electronics, or microelectromechanical actuators.     

A sum-over-state scheme of analysis of hyperpolarizabilities and its application to spiroconjugated molecular system

The static first and second hyperpolarizabilities of a number of spiromolecules with varying degree of polarity have been calculated at the HF and MP2 level using the 6-31+G* basis set and the B3LYP/6-31+G* optimized geometry. The variation of mean second hyperpolarizability in these molecular systems has been explained in terms of the ground state dipole moment, mean linear polarizability and second-order polarizability. A number of relationships among these quantities have been derived in the framework of the sum-over-state scheme and the generalized Thomas–Kuhn sum rule. The spiroconjugation results in the significant increase of the mean polarizability. The appreciable enhancement of first hyperpolarizability due to the spiroconjugation between two dipolar monomer units has been accounted for the rather significant increase of the mean polarizability tensor and the ground state dipole moment. The relatively larger value of the average second hyperpolarizability of the spiroconjugated molecules compared to that of the corresponding monomers arises from the rather significant increase of the nonaxial component γ _xxyy . The replacement of spirocarbon by spirosilicon results in the enhancement of the cubic polarizability manifold. The donor–acceptor substituted spirocompounds are predicted to be the superior third-order nonlinear optical (NLO) phores. The nature of π-conjugation in the monomer units around the spirocenter shows a strong modulation of the NLO properties of spirocompounds. The influence of electron correlation on the NLO properties at the MP2 level has been found to be rather significant.     

Semiempirical quantum mechanical calculations of dipolar interaction between dipyridamole and dipalmitoyl phosphatidyl choline in Langmuir monolayers

Recent studies have shown that dipalmitoyl phosphatidyl choline (DPPC) monolayers respond cooperatively to the presence of dipyridamole (DIP) guest molecules even at small concentrations, which is a signature of molecular recognition. Using semiempirical quantum mechanical calculations for the DIP-DPPC system, we show that the incorporation of DIP causes large changes in the vertical dipole moment of the DIP-DPPC system, which can explain why measurable changes in surface potential are observed experimentally even at very low DIP concentrations. The calculations are also consistent with the anomalous concentration dependence of the surface pressure and surface potential isotherms for DIP-DPPC monolayers. Rather than saturation or a continuous increase in the effects caused by the incorporation of increasing amounts of DIP, the experimentally observed inversion in the behavior of the surface potential as the DIP concentration reaches 0.5 mol % would be caused by a change in DIP conformation, from a vertical arrangement for the DIP rings to a horizontal or intermediate arrangement. The strong dipolar interactions indicated in the calculations may also be the origin of the drastic changes in monolayer morphology seen in fluorescence microscopy images, with triskellion-shaped domains being formed for condensed DIP-DPPC monolayers.     

Simple method for the preparation of DNA-poly(o-methoxyaniline) hybrid: structure, morphology, and uncoiling of poly(o-methoxyaniline) on the DNA surface

The DNA-poly(o-methoxyaniline) (POMA) hybrid is prepared by mixing aqueous solutions of POMA [emeraldine salt (ES), doping level [Cl]/[N] = 0.52] and sodium salt of DNA (Na-DNA) and is then freeze-dried after 4 days. Three different compositions (WDNA = 0.25, 0.5, and 0.75, WDNA is the weight fraction of DNA) of the hybrids are prepared. The SEM pictures show a gradation in morphology; for example, for WDNA = 0.75, fibrils are present but, at lower DNA concentration, a fibrillar network structure of the hybrid is observed. The circular dichroism (CD) spectra of the hybrid solutions indicate unchanged DNA conformation and WAXS patterns indicate intact crystal structure of DNA in the hybrid. The UV-vis spectra suggest no denaturation of DNA during the blending process. The UV-vis spectra of the hybrids in aqueous medium show a gradual red shift of the pi band to polaron band transition with time. The plots of these wavelengths with time are sigmoidal, indicating the autocatalytic nature of the process. With an increase in the temperature, the rate of the red shift of the above peak is faster. Arrhenius analysis of the rate (1/tau700 where tau700 is the time required to reach the absorption maximum at the wavelength 700 nm) yields straight lines for the three hybrid compositions with activation energy values of 13-15 kcal/mol. These values are almost equal to the activation energy values of conformational transition of other polymers, supporting the red shift in UV-vis spectra occurs from conformational transition. DNA offers a surface where POMA gets adsorbed and the stable conformational transition resulting in the uncoiling of the POMA chain occurs through repulsive interaction among bound radical cations of POMA (ES) on the DNA surface. The conductivity of the hybrids is on the order of 10(-6) S/cm, and the I-V characteristic curves indicate the semiconducting nature of the hybrids.     

Transport properties of CdS nanowire embedded poly(3-hexyl thiophene) nanocomposite

Electrical transport properties of CdS nanowire embedded regioregular poly(3-hexyl thiophene) (P3HT) nanocomposite are investigated and the results are compared with those of the pure P3HT polymer. Both dc and ac conductivities of P3HT and CdS-P3HT nanocomposites show semiconducting nature and conductivity of CdS-P3HT is much less than that of the pure P3HT conducting polymer. The difference in the electrical behavior is attributed to the formation of nanowires in the CdS-P3HT nanocomposite. The dc conductivity data at high and low temperatures are qualitatively consistent with the optical-photon-assisted hopping and variable-range hopping models, respectively. However, the multiphonon-assisted hopping models of small polarons in nonadiabatic regime, which consider strong interactions with electrons with the optical as well as acoustical phonons, are the best to interpret quantitatively the experimental data in the entire temperature range for both P3HT and CdS-P3HT nanocomposites. We observe that the quantum tunneling model of small polarons is consistent with almost every respect of the loss data of P3HT conducting polymer, while for CdS-P3HT nanocomposite the ac conductivity varies with temperature in a different manner, which is explained in terms of simple quantum tunneling model of electrons in contrast to that of pure P3HT conducting polymer.     

A new colorimetric chemodosimeter for mercury ion via specific thioacetal deprotection in aqueous solution and living cells

A sensitive and selective new chemodosimeteric chemosensor (DIBT) for mercury ions was successfully devised and characterized. Upon addition of Hg²⁺ to DIBT, a red-edge absorption band at 972 nm was observed. An important feature for the new chemodosimeter is its high selectivity toward mercury ions over the other competitive species due to Hg²⁺-triggered specific C–S cleavage, making the ‘naked-eye’ detection of mercury ions possible in aqueous solution and living cells such as Candida albicans.     

Unity of elementary particles and forces for the third family

We propose a non-supersymmetric SU(5)$\mathit{SU}(5)$ model in which only the third family of fermions are unified. The model remedies the non-unification of the three Standard Model couplings in non-supersymmetric SU(5)$\mathit{SU}(5)$. It also provides a mechanism for baryon number violation which is needed for the baryon asymmetry of the Universe and is not present in the Standard Model. Current experimental constraints on the leptoquark gauge bosons, mediating such baryon and lepton violating interactions in our model, allow their masses to be at the TeV scale. These can be searched for as a (bτ) or (tt) resonance at the Large Hadron Collider as predicted in our model.     

Phase-function method for elasticα-α scattering

The phase-function method is adapted to deal with scattering on Coulomb plus nonlocal separable potentials. The Coulomb effect is included rigorously and a closed form expression is obtained for the scattering phase shiftδ _l (k). Based on the expression forδ _l (k) we present results forα-α elastic scattering phases which compare very well with more detailed calculations.