Outer-Membrane Protease (OmpT) Based E. coli Sensing with Anionic Polythiophene and Unlabeled Peptide Substrate

E. coli and Salmonella are two of the most common bacterial pathogens involved in foodborne and waterborne related deaths. Hence, it is critical to develop rapid and sensitive detection strategies for near-outbreak applications. Reported is a simple and specific assay to detect as low as 1 CFU mL⁻¹ of E. coli in water within 6 hours by targeting the bacteria's surface protease activity. The assay relies on polythiophene acetic acid (PTAA) as an optical reporter and a short unlabeled peptide (LL37_FRRV) previously optimized as a substrate for OmpT, an outer-membrane protease on E. coli. LL37_FRRV interacts with PTAA to enhance its fluorescence while also inducing the formation of a helical PTAA-LL37_FRRV construct, as confirmed by circular dichroism. However, in the presence of E. coli LL37_FRRV is cleaved and can no longer affect the conformations and optical properties of PTAA. This ability to distinguish between an intact and cleaved peptide was investigated in detail using LL37_FRRV sequence variants.     

Computational analysis of non-isothermal temperature distribution on natural convection in nanofluid filled enclosures

In this study, the problem of steady state natural convection in an enclosure filled with a nanofluid has been analyzed numerically by using heating and cooling by sinusoidal temperature profiles on one side. The governing partial differential equations, in terms of the dimensionless stream function–vorticity and temperature, are solved numerically using the finite volume method for various inclination angles 0^°≤?≤90^°$0^{°}\le ?\le 90^{°}$, different types of nanoparticles (TiO₂ and Al₂O₃) and fractions of nanoparticles 0≤φ≤0.1$0\le \phi \le 0.1$, whereas the range of the Rayleigh number Ra is 10³–10⁵. It is found that the addition of nanoparticles into water affects the fluid flow and temperature distribution especially for higher Rayleigh numbers. An enhancement in heat transfer rate was registered for the whole range of Rayleigh numbers. However, low Rayleigh numbers show more enhancement compared to high Rayleigh numbers.     

Adsorption of Remazol Brilliant Blue R on activated carbon prepared from a pine cone

In this work the activated pine cone was investigated as adsorbent to remove Remazol Brilliant Blue R from aqueous solution. The effects of various experimental parameters such as initial dye concentration, contact time, temperature, adsorbent dose and pH were examined. The adsorption of Remazol Brilliant Blue R from aqueous solution was increased with the increase in initial dye concentration, contact time, temperature, adsorbent dose but decreased with the increase in the pH. The results in this study indicated that the activated pine cone was an attractive candidate for removing Remazol Brilliant Blue R.     

Combining electron-neutral building blocks with intramolecular "conformational locks" affords stable, high-mobility p- and n-channel polymer semiconductors

Understanding the relationship between molecular/macromolecular architecture and organic thin film transistor (TFT) performance is essential for realizing next-generation high-performance organic electronics. In this regard, planar π-conjugated, electron-neutral (i.e., neither highly electron-rich nor highly electron-deficient) building blocks represent a major goal for polymeric semiconductors, however their realization presents synthetic challenges. Here we report that an easily accessible (minimal synthetic steps), electron-neutral thienyl-vinylene (TVT)-based building block having weak intramolecular S···O "conformational locks" affords a new class of stable, structurally planar, solution-processable, high-mobility, molecular, and macromolecular semiconductors. The attraction of merging the weak TVT electron richness with supramolecular planarization is evident in the DFT-computed electronic structures, favorable MO energetics, X-ray diffraction-derived molecular structures, experimental lattice coehesion metrics, and excellent TFT performance. TVT-based polymer TFTs exhibit stable carrier mobilities in air as high as 0.5 and 0.05 cm(2)/V·s (n- and p-type, respectively). All-TVT polymer-based complementary inverter circuitry exhibiting high voltage gains (~50) and ring oscillator circuitry with high f(osc)(~1.25 kHz) is readily fabricated from these materials by simple inkjet printing.     

Real-time determination of the activity of ATPase by use of a water-soluble polythiophene

This contribution introduces a fluorescence assay for real-time determination of the activity of p97/VCP, a 540-kDa homo-hexameric enzyme, belonging to the AAA-ATPase family. A fluorescent reporter “poly 1-(3-((4-methylthiophen-3-yl)oxy)propyl)quinuclidin-1-ium” (poly PTQ) is used to monitor the hydrolysis of ATP to ADP by p97/VCP. The proposed assay relies on the different strength of coordination of ATP and ADP to the polymer backbone. We used recovery of fluorescence intensity on addition of p97/VCP to a poly PTQ/ATP solution to determine the enzymatic activity. The kinetic data K _m and V _max were 0.30?mmol?L^?1 ATP and 0.134?nmol ATP min^?1?μg^?1 enzyme, respectively. The specificity of the assay was investigated by using an unhydrolyzable ATP analogue and sensitivity against p97 mutagenesis was further examined by detection of the activity of wild type and truncated p97/VCP. Our study demonstrates that determination of the real-time activity of p97/VCP is possible, because of the superior sensitivity and very fast optical response of poly PTQ.

Buoyancy induced flow in a nanofluid filled enclosure partially exposed to forced convection

A numerical study was performed on natural convection for water–CuO nanofluid filled enclosure where the top surface was partially exposed to convection. The cavity has a square cross-section and differentially heated. Except exposed convection part on the top, all sides are adiabatic on horizontal walls. Effects of Rayleigh number (10³ ? Ra ? 10⁵), Biot number (0 ? Bi ? ∞), length of partial convection (0.0 ? L ? 1.0) and volume fraction of nanoparticles (0.0 ? φ ? 0.1) on heat and fluid flow were investigated. The results showed that for the case of high Biot number that heat transfer along the heated was enhanced by increasing the Rayleigh number mainly at the upper portion of the heated wall. When the top wall was totally exposed to convection, the results prevail that the heat transfer was more effective at high Biot number especially at the upper portion of the heated wall. For the case of high Biot number, the results prevailed that the heat transfer at the upper portion of the heated wall increases considerably at high exposed length to convection (L); however, for L ? 0.75 the effect of L was less pronounced. Contour maps for percentage of heat transfer enhancement were presented and it was shown that the location of maximum enhancement in heat transfer was sensitive to Ra, φ and L.     

First principles calculations of Cd and Zn chalcogenides with modified Becke–Johnson density potential

In this work, we present first principles calculations based on a full potential linear augmented plane-wave method (FP-LAPW) to calculate structural and electronic properties of CdX and ZnX (X = S, Se, Te) based II–VI chalcogenides. First principles calculations using the local density approximation (LDA) and the related generalized gradient approximation (GGA) lead to a severe underestimate of the band gap. The proposed model uses various exchange–correlation potentials (LSDA, GGA and MBJLDA) to determine band gaps and structural properties of semiconductors. We show that using modified Becke–Johnson (MBJLDA) density potential leads to a better agreement with experimental data for band gaps of Cd and Zn based semiconductors.     

Analyzing of the effect of the dusty fluid,anisotropy and layered of the wall on the wave propagation

This study considers the propagation of time harmonic waves in, prestressed, anisotropic elastic tubes filled with viscous fluid containing dusty particles. The fluid is assumed to be incompressible and Newtonian. The tube material is considered to be incompressible, anisotropic, and elastic. The tube is subjected to a static inner pressure P_i and an axial stretch λ. Utilizing the theory of “Superposing small deformations on large initial static deformations”, differential equations governing wave propagation inside the tube are obtained in terms of cylindrical coordinates. Analytical solutions for the equations of motion for the dust and the fluid are obtained, and expressed numerically. The dispersion relation is obtained as a function of the stretch, the thickness ratio and the parameters for dusty particles.     

A numerical study of the effects of the vertical baffle on liquid sloshing in two-dimensional rectangular tank

The liquid sloshing in a moving partially filled rectangular tank with a vertical baffle is investigated. A numerical algorithm based on the volume of fluid (VOF) technique is used to study the nonlinear behavior of liquid sloshing. The numerical model solves the complete Navier–Stokes equations in primitive variables by using of finite difference approximations with the moving coordinate system. The ratio of baffle height to the initial liquid depth has been changed in the range of 0≤h_B/h≤1.2. The critical baffle height to reach the roof of the tank and the baffle height beyond the liquid does not get over the baffle anymore have been investigated. The vortex originated by the flow separation from the baffle tip became weaker with increasing the baffle height. In order to assess the accuracy of the method used, some results with baffle height are compared with the experimental results. Comparisons show good agreement for slosh loads in the cases investigated. The free surface elevation and the time variations of pressures have been also presented.