Acoustic receptivity of Mach 4.5 boundary layer with leading-edge bluntness

Boundary layer receptivity to two-dimensional slow and fast acoustic waves is investigated by solving Navier–Stokes equations for Mach 4.5 flow over a flat plate with a finite-thickness leading edge. Higher order spatial and temporal schemes are employed to obtain the solution whereby the flat-plate leading edge region is resolved by providing a sufficiently refined grid. The results show that the instability waves are generated in the leading edge region and that the boundary-layer is much more receptive to slow acoustic waves (by almost a factor of 20) as compared to the fast waves. Hence, this leading-edge receptivity mechanism is expected to be more relevant in the transition process for high Mach number flows where second mode instability is dominant. Computations are performed to investigate the effect of leading-edge thickness and it is found that bluntness tends to stabilize the boundary layer. Furthermore, the relative significance of fast acoustic waves is enhanced in the presence of bluntness. The effect of acoustic wave incidence angle is also studied and it is found that the receptivity of the boundary layer on the ‘windward’ side (with respect to the acoustic forcing) decreases by more than a factor of four when the incidence angle is increased from 0° to 45°. However, the receptivity coefficient for the ‘leeward’ side is found to vary relatively weakly with the incidence angle.      

Ultrasound-assisted synthesis of benzothiazepines and assessment of their in vitro acetylcholinesterase inhibition activity

A series of steroidal 1,5-benzothiazepine and its derivatives have been synthesized by the reaction of α,β-unsaturated ketones with 2-aminothiophenol using small amount of dimethylformamide (DMF) as a solvent and catalytic amount of acetic acid at 45–50°C under ultrasonic irradiation. This method provides several advantages such as the shortest reaction time, high yields, simple work-up procedure, and purification of products by nonchromatographic methods. All the synthesized compounds were screened for their acetylcholinesterase (AChE) inhibition activity. These compounds exhibited moderate AChE inhibition activity as compared to the standard drug, tacrine. Compound 5 showed the highest inhibition among all benzothiazepines. The AChE inhibition activity of the compound 5 was further investigated with the help of in silico docking study to predict the active sites.     

Comparison of tin‐doped indium oxide films fabricated by spray pyrolysis and magnetron sputtering

A comparison of the properties between Tin‐doped Indium Oxide (ITO) films fabricated by sputtering and spray pyrolysis is presented. This analysis shows that the ITO films fabricated by DC magnetron sputtering in pure argon gas requires of a subsequent annealing for the improvement of their structural, electrical and optical properties, when they are compared to films fabricated by single‐stage spray pyrolysis process that includes a new approach. The optimum annealing temperature for ITO films sputtered at room temperature lies in the 300‐350 °C range. Under such conditions, the ITO sputtered films are slightly more resistive than the resistivity (2 × 10^‐4 Ω‐cm) shown by films sprayed at 480 °C using a solution with a 5 % of tin to indium ratio, and almost four times the worst value of the combination of transparency and conductivity determined by the value of the figure of merit (FOM). The sprayed films have a high value of the FOM, 2.9×10^‐2 Ω^‐1, which is comparable with the best published results.     

Self-Aggregation of Cationic Dimeric and Anionic Monomeric Surfactants with Nonionic Surfactant in Aqueous Medium

Spectrofluorometric measurements have been used to elaborate the self-aggregation of mixture of anioinic, sodium dodecylbenzenesulfonate (SDBS), and cationic gemini, alkanediyl-α, ω-bis (tetradecyldimethylammonium bromide) (14-4-14) with nonionic surfactant, polyoxyethylene 10 cetyl ether (Brij-56). The critical micelle concentration (cmc) of the binary mixtures has been investigated. Application of the regular solution theory (RST) to the experimental data yield the interaction parameter at mixed micelles (β), indicate an attractive interaction and reflect the synergistic behavior in both Brij-56/SDBS and Brij-56/14-4-14 systems. The micelle aggregation number (N _agg) was measured using a steady state fluorescence quenching method. The N _agg values of the mixed surfactant system were larger than those of pure components. The micropolarity of various combinations and the binding constants (K _sv) were determined from the ratio of intensity of peaks (I ₁/I ₃) of pyrene fluorescence emission spectrum and its quenching, respectively.     

Lagrangian PTV in 3D flows

Particle Tracking Velocimetry (PTV) is one of the evolving techniques which can cover the increasing need for measurements in a Lagrangian frame. Here some recent developments and the validation of the tracking scheme on the Kinematic Simulation Inertial Model (KSIM) test flow field is presented.     

RAFT polymerization of linear ABC triblock copolymer P<Emphasis Type="Italic">t</Emphasis>BA-<Emphasis Type="Italic">b</Emphasis>-PS-<Emphasis Type="Italic">b</Emphasis>-P2VP and regulation of its hierarchical self-assembly structure in solution

Linear ABC triblock copolymer PtBA₁₅₄-b-PS₃₀₀-b-P2VP₂₄₀ was successfully synthesized by RAFT polymerization. Block copolymer micelles were prepared by the two-step hierarchical self-assembly process. Size exclusion chromatography and ¹H NMR were used to characterize the structure of samples. Morphologies and size of micelles were determined by transmission electron microscope. The results showed that the densely dispersed spherical micelles of PtBA₁₅₄-b-PS₃₀₀-b-P2VP₂₄₀ were obtained in the first step of the hierarchical self-assembly process. In the second step, core-compartmentalized micelle strings with different lengths and distribution densities were obtained when the primary self-assembled solution was dialyzed in distilled water with pH ≈ 3. When distilled water with pH ≈ 3 was added drop-wise to this solution, uniformly dispersed spherical core-compartmentalized micelles of PtBA₁₅₄-b-PS₃₀₀-b-P2VP₂₄₀ were prepared. Thus, hierarchical self-assembly structure of linear ABC triblock copolymer was obtained successfully and the preparation of uniformly dispersed spherical micelles of triblock copolymers was realized simply by changing the secondary self-assembly methods.     

Combustion modeling using Principal Component Analysis: A posteriori validation on Sandia flames D,E and F

The present work shows the first application of the PC-transport approach in the context of Large Eddy Simulation (LES) of turbulent combustion. Detailed kinetic mechanisms, together with advanced computational tools, are needed to advance our knowledge of turbulent reacting systems. However, the cost related to high-fidelity simulations of turbulent reacting flows is still prohibitive for realistic configurations. Therefore, there is a need to reduce the complexity of the problem by identifying low-dimensional manifolds. To this end, the potential offered by Principal Component Analysis (PCA) in parameterizing the thermo-chemical state-space is very appealing. The present paper extends the PC-transport framework to three-dimensional Large Eddy Simulation (LES), coupling PCA with Gaussian Process Regression (GPR). To demonstrate the potential of the method, LES simulations of Sandia flames D, E and F are shown. Results show the great potential of the PC-GPR model, as indicated by the accuracy of the simulation results when compared with experimental data, using only 2 principal components. The sensitivity to the kinetic mechanism and subgrid closure model is also investigated.     

A single-layer peptide nanofiber for enhancing the cytotoxicity of trastuzumab (anti-HER)

A multivalent system is often employed to enhance the effectiveness of a targeted therapy. In the present study, we report a single-layer peptide nanofiber (NFP) as a multivalent targeting platform to improve the cytotoxicity of trastuzumab (anti-HER), a monoclonal antibody targeting the human epidermal growth factor receptor 2 (HER-2) in approximately 20 % of breast cancer patients. The trastuzumab-conjugated nanofiber (anti-HER/NFP) was 100 × 4 nm in size and was assembled from multiple peptide units (mPEG-BK(FITC)SGASNRA-kldlkldlkldl-CONH₂). The optimized preparation was attached with approximately 10 antibodies at the surface. Because of an increase in the multivalency, anti-HER/NFP was able to truncate more cell surface HER-2 and, thus, showed an enhanced cytotoxicity toward HER-2 positive SKBr-3 human breast cancer as compared to the free anti-HER. Western blot analysis and fluorescence microscopic studies confirmed that there was a significant downregulation of the HER-2 level and also inhibition of the cell survival cell signaling pathways including the phosphatidylinositol 3-kinase (PI3K) and the mitogen activated protein kinase (MAPK) pathway. Our data suggested that NFP can be useful as a multivalent platform for immunotherapy, especially in combination with other chemotherapeutic agents in the future.     

Field-induced transition from homeotropic to planar geometry in the SmC* phase of an electroclinic liquid crystal

The optical and electrical behavior was investigated of a symmetric liquid crystal (LC) cell: ITO–silane–LC–silane–ITO. The silane layer induces a perfect homeotropic alignment of the molecules of the studied electroclinic liquid crystal (ELC) material, BDH 764E. A field-induced transition from the perfect homeotropic to planar orientation in the chiral smectic C (SmC*) and smectic A (SmA) phases of the ELC was observed. Optical and dielectric studies were performed for both alignment (geometry) modes. The field-induced transition from the homeotropic to planar orientation was studied vis-à-vis the high negative dielectric anisotropy obtained in the studied material. Such an ELC with large negative dielectric anisotropy and perfect homeotropic alignment may have important implications for modern LC display technology.