Automated solid phase synthesis of oligoarabinofuranosides

Automated solid phase synthesis enables rapid access to the linear and branched arabinofuranoside oligosaccharides. A simple purification step is sufficient to provide the conjugation ready oligosaccharides in good yield

Modular automated solid phase synthesis of dermatan sulfate oligosaccharides

Dermatan sulfates are glycosaminoglycan polysaccharides that serve a multitude of biological roles as part of the extracellular matrix. Orthogonally protected D-galactosamine and L-iduronic acid building blocks and a photo- cleavable linker are instrumental for the automated synthesis of dermatan sulfate oligosaccharides. Conjugation-ready oligosaccharides were obtained in good yield

Effect of hydrogen jets in supersonic mixing using strut injection schemes

The prevalence of complex phenomena associated with the fuel mixing of a supersonic stream in scramjet combustor is inherently occurred due to the short residence time. An efficient injection mechanism is required to enhance the mixing and improve combustion efficiency. This numerical simulation study aims to reveal the performance of modified strut injection strategies within a Mach 2.0 flow field. Two-dimensional steady and transient Navier-Stokes computations of the DLR scramjet experiment is performed for various strut injection locations. The Reynolds Averaged Navier Stokes equation with the SST k-ε turbulence model is utilized to solve the flow field under steady conditions. The critical parameters examined to investigate steady solutions are wall static pressure, flow Mach number, and total pressure loss across the combustor. The dual injection configuration in the flow considerably reduces the shock waves impact at the downstream of the strut and preserves the magnitude of internal forces acting on combustor walls and total pressure loss. Unsteady Detached Eddy Simulation (DES) results for hydrogen concentration and velocity field are analyzed by applying Dynamic Mode Decomposition (DMD). Multiple injections are observed to alter the frequency and the number of dominant modes

Numerical investigations on the hydrogen jet pressure variations in a strut based scramjet combustor

Purpos

Combustion Characteristics of Nanoaluminium-Based Composite Solid Propellants: An Overview

The nanosized powders have gained attention to produce materials exhibiting novel properties and for developing advanced technologies as well. Nanosized materials exhibit substantially favourable qualities such as improved catalytic activity, augmentation in reactivity, and reduction in melting temperature. Several researchers have pointed out the influence of ultrafine aluminium (∼100 nm) and nanoaluminium (<100 nm) on burning rates of the composite solid propellants comprising AP as the oxidizer. The inclusion of ultrafine aluminium augments the burning rate of the composite propellants by means of aluminium particle’s ignition through the leading edge flames (LEFs) anchoring above the interfaces of coarse AP/binder and the binder/fine AP matrix flames as well. The sandwiches containing 15% of nanoaluminium solid loading in the binder lamina exhibit the burning rate increment of about 20–30%. It was noticed that the burning rate increment with nanoaluminium is around 1.6–2 times with respect to the propellant compositions without aluminium for various pressure ranges and also for different micron-sized aluminium particles in the composition. The addition of nano-Al in the composite propellants washes out the plateaus in burning rate trends that are perceived from non-Al and microaluminized propellants; however, the burning rates of nanoaluminized propellants demonstrate low-pressure exponents at the higher pressure level. The contribution of catalysts towards the burning rate in the nanoaluminized propellants is reduced and is apparent only with nanosized catalysts. The near-surface nanoaluminium ignition and diffusion-limited nano-Al particle combustion contribute heat to the propellant-regressing surface that dominates the burning rate. Quench-collected nanoaluminized propellant residues display notable agglomeration, although a minor percentage of the agglomerates are in the 1–3 µm range; however, these are within 5 µm in size. Percentage of elongation and initial modulus of the propellant are decreased when the coarse AP particles are replaced by aluminium in the propellant composition

Tris(pentafluorophenyl)borane-Promoted Stereoselective Glycosylation with Glycosyl Trichloroacetimidates under Mild Conditions

Tris­(pentafluorophenyl)­borane-promoted stereoselective glycosylation with trichloroacetimidate glycosyl donors is described. The reactions proceed efficiently with a wide range of acceptors, from sugar to nonsugar, under mild conditions in the presence of a catalytic amount of B­(C₆F₅)₃. The perbenzylated glucosyl α-imidate provides β-selective glycosides in 70–92% yields

Urea–hydrogen peroxide prompted the selective and controlled oxidation of thioglycosides into sulfoxides and sulfones

A practical method for the selective and controlled oxidation of thioglycosides to corresponding glycosyl sulfoxides and sulfones is reported using urea–hydrogen peroxide (UHP). A wide range of glycosyl sulfoxides are selectively achieved using 1.5 equiv of UHP at 60 °C while corresponding sulfones are achieved using 2.5 equiv of UHP at 80 °C in acetic acid. Remarkably, oxidation susceptible olefin functional groups were found to be stable during the oxidation of sulfide

High-efficiency c-Si based interdigitated point contact back heterojunction solar cells

We report on the modeling and performance optimization studies of point contact back heterojunction (BHJ) solar cells. BHJ solar cell technology is a combination of front heterojunction (a-Si:H/c-Si) solar cell technology and interdigitated back junction c-Si solar cell technology. In this work, both emitter (p(+)-a-Si:H) and back surface field (BSF, n(+)-a-Si:H) were formed at the rear side as an array of interdigitated points, where their respective contacts formed an interdigitated pattern. The gap between p-type and n-type contact fingers was fixed at 10 A mu m. The n(+)-a-Si:H (i.e. BSF) circular diameter was fixed while emitter size was varied, and vice versa. Simulation was also performed with and without passivation layer underneath emitter and BSF. We also investigated the impact of surface texture size on cell efficiency. By varying surface texture size, viz. pyramid height and base width, an efficiency as high as 26.61% was obtained with 761 mV V-oc, 41 mA/cm(2) J(sc), and 84.5% FF for a small pyramid structure with 2 mu m height and 4 mu m base width