In situ reduction of graphitic oxide by amorphization of magnesium diboride for the superior thermo-optical property based nanofluid applications

The reaction of magnesium diboride with water results in an intermediate borohydride product which leads to the simultaneous reduction of graphitic oxide (GO) and the formation of magnesium hydroxide. In this work, the thermo-optical properties of magnesium diboride modified reduced graphene oxide–based nanofluids have been explored. The study primarily focuses on the reaction mechanism of magnesium diboride and GO by using liquid exfoliation technique. Suspension after liquid exfoliation mainly consisted of a turbid supernatant and precipitate which was composed of boron-based nanosheets (CBNs) and a composite of magnesium hydroxide and reduced graphene oxide (CBNs-rGO), respectively. Nanofluids were subsequently formulated from the obtained products of the reaction. CBNs form a stable suspension in water and ethylene glycol because of its attached borohydrides and hydroxyl hydrophilic sites. CBNs nanofluids show good thermal conductivity with poor light absorption properties in the visible wavelength range. Whereas, CBNs-rGO nanofluids show ~95% attenuation in the radiation with a significant enhancement of ~30% and 20% in thermal conductivity as compared with Deionized water– and ethylene glycol–based fluids, respectively.     

Colloidal,Functional, Piezoelectric BaTiO3-Au Nanohybrid for Wireless Cell Therapy

Ultrasound-assisted reactive oxygen species (ROS) generation from piezoelectric nanomaterial offers unique wireless therapeutic approach in remote places. In the previous work, piezoelectric barium titanate (BaTiO₃) nanorod have been synthesized and used for wireless cell therapy. However, the piezoelectric property of BaTiO₃ nanorod needs further improvement for diverse applications. In this work, it is shown that gold nanoparticle conjugation with BaTiO₃ nanorod (BaTiO₃-Au) can significantly enhance the piezoelectric performance with the piezoelectric constant value of 110 pm V⁻¹. The colloidal BaTiO₃-Au is further functionalized with folate for selective targeting of folate-overexpressed cancer cells and used for wireless cell therapy via intracellular ROS generation under ultrasound exposure. The synthesized colloidal nanohybrid can be used for various therapeutic applications.     

Analysis of Diazofluorene DNA Binding and Damaging Activity: DNA Cleavage by a Synthetic Monomeric Diazofluorene

The lomaiviticins and kinamycins are complex DNA damaging natural products that contain a diazofluorene functional group. Herein, we elucidate the influence of skeleton structure, ring and chain isomerization, D‐ring oxidation state, and naphthoquinone substitution on DNA binding and damaging activity. We show that the electrophilicity of the diazofluorene appears to be a significant determinant of DNA damaging activity. These studies identify the monomeric diazofluorene 11 as a potent DNA cleavage agent in tissue culture. The simpler structure of 11 relative to the natural products establishes it as a useful lead for translational studies.     

Through‐Space 1,4‐Palladium Migration and 1,2‐Aryl Shift: Direct Access to Dibenzo[a,c]carbazoles through a Triple CH Functionalization Cascade

A palladium‐catalyzed expeditious synthesis of dibenzofused carbazoles from readily available 2‐arylindoles and diaryliodonium salts is reported. Interestingly, after the electrophilic C3 palladation of indole, an unexpected “through‐space” 1,4‐palladium migration to the 2‐aryl moiety, by remote C?H bond activation followed by C?H arylation with diaryliodonium salt, and an unprecedented 1,2‐aryl shift take place. Finally, an intramolecular cross‐dehydrogenative coupling (CDC) at the C2 position affords dibenzo[a,c]carbazoles in high yields. Remarkably, the present migratory annulation occurs through three C?H bond activation one C?C bond cleavage, and the simultaneous construction of three new C?C bonds in a single operation.     

On the application of the two-level large-eddy simulation method to turbulent free-shear and wake flows

We present application of the hybrid two-level large-eddy simulation (TLS-LES) method, a multi-scale simulation model, to turbulent free-shear and wake flows at moderately high Reynolds number. The TLS-LES method combines the scale-separation-based two-level simulation (TLS) model with the spatial-filtering-based conventional large-eddy simulation (LES) model in an additive manner using a normalised blending function. The additive blending can be performed in a static or a dynamic manner. We demonstrate that the method, which has been originally developed for wall-bounded flows, can be used to simulate flows in complex configurations without requiring any further adjustments to the model. In this study, three canonical flows are simulated, which are representative of free-shear and wake flows. These cases include a temporally evolving mixing layer, flow past a circular cylinder in a uniform flow and flow past a finite-span airfoil placed in a uniform flow at three different angle of attacks. We analyse the role of static and dynamic blending functions, large-scale grid resolution and the effect of small scales on the instantaneous flow features and turbulence statistics. The results obtained from these cases demonstrate robustness, accuracy and consistency of the multi-scale TLS-LES method and show that the method is suitable for investigation of turbulent flows that encompass features such as massive separation, reattachment, transition to turbulence and unsteady wake, which are challenging to model numerically.