Palladium(II)-catalyzed intramolecular aminoacetoxylation of sugar derived alkenyl tosylsulfonamide: Total synthesis of l-deoxyallonojirimycin

Palladium catalyzed intramolecular aminoacetoxylation of d-ribose derived alkenyl tosylsulfonamide to deliver l-deoxyallonojirimycin in an overall yield of 19%. The preliminary screening of l-deoxyallonojirimycin against carbohydrate processing enzymes showed moderate inhibitory activity against α-glucosidase (yeast) and α-mannosidases.     

Higher hydrogen uptake capacity of C2H4Ti+ than C2H4Ti: a quantum chemical study

Using density functionals theory, we show that gravimetric hydrogen uptake of C₂H₄Ti complex and its cation, C₂H₄Ti⁺, differ by about 2 wt%. Six and five hydrogen molecules are found to be adsorbed on C₂H₄Ti⁺ and C₂H₄Ti complexes thereby showing a hydrogen-uptake capacity of 13.74 and 11.72 wt%, respectively. All hydrogen molecules are adsorbed in molecular form on C₂H₄Ti⁺ ion with an increase in metal bond strength, whereas in some cases, the hydrogen molecules are found to be dissociated on C₂H₄Ti neutral complex. The uptake capacity of neutral C₂H₄Ti complex shown in this work is in excellent agreement with that reported experimentally, Phillips and Shivaram (Phys Rev Lett 100:105505, 2008). The H₂ adsorption energy and its dependence on exchange and correlation functions in density functionals method were illustrated. Even after the adsorption of maximum number of hydrogen molecules on C₂H₄Ti and C₂H₄Ti⁺ complexes, Ti and Ti⁺ remain strongly bound to C₂H₄ substrate.     

Simulative investigation the impact of optical amplification techniques on single- and dual-electrode MZM and direct modulator's in single-tone RoF system

Since the introduction of erbium-doped fiber amplifier (EDFA) in optical fiber communication systems at 1550 nm, the fiber loss is no longer considered as the limiting factor but the fiber dispersion and chirp parameters play an important role in degrading the performance of optical communication systems. Further, the invention of external modulators of Mach-Zehnder (MS) type minimizes the transmission power penalty due to fiber chromatic dispersion as these modulators are consider almost chirp-free modulators. Also, better suppression of nonlinear distortions consists of harmonic distortions (HDs) and intermodulation distortions (IMDs) were achieved by using Mach-Zehnder external modulator [8]. In this work, a simulation comparison of external- and direct-modulation schemes using different optical amplifiers; SOA and EDFA in single-tone RoF system is reported. A single-tone channel of 20 GHz is transmitted over single-mode fiber (SMF) either externally modulated by using single-electrode (SEMZM) - and dual-electrode (DEMZM) - Mach-Zehnder modulator or by direct-modulation scheme. Better improvements in the measurement of received RF power of a 20 km linked single-tone RoF system are achieved by using SEMZM with EDFA, which means maximum optical link is achieved between Central Office (CO) and Base Station (BS). Further, this scheme provides better BER as compare to other schemes discussed in this paper.     

Synthesis and photo physical properties of Au @ Ag (core @ shell) nanoparticles disperse in poly vinyl alcohol matrix

Synthesis of core @ shell (Au @ Ag) nanoparticle with varying silver composition has been carried out in aqueous poly vinyl alcohol (PVA) matrix. Core gold nanoparticle (~15 nm) has been synthesized through seed-mediated growth process. Synthesis of silver shell with increasing thickness (~1–5 nm) has been done by reducing Ag⁺ over the gold sol in the presence of mild reducing ascorbic acid. Characterization of Au @ Ag nanoparticles has been done by UV–Vis, High resolution transmission electron microscope (HRTEM) and energy dispersive X-ray (EDX) spectroscopic study. The blue shift of surface plasmon resonance (SPR) band with increasing mole fraction of silver has been interpreted due to dampening of core, i.e. Au SPR by Ag. The dependence of nonlinear optical response of spherical core @ shell nanoparticles has been investigated as a function of relative composition of each metal. Simulation of SPR extinction spectra based on quasi-static theory is done. A comparison of our experimental and the simulated extinction spectra using quasi-static theory of nanoshell suggests that our synthesized bimetallic particles have core @ shell structure rather than bimetallic alloy particles.     

Synthesis of Novel Functionalized 4-Aza-2,3-Didehydropodophyllotoxin Derivatives with Potential Antitumor Activity

Novel arylamino alcohols were synthesized and these alcohols were used to prepare 12 novel N-(2-hydroxy-ethyl)-2,3-didehydroazapodophyllotoxins, in one step, by simple reflux in ethanol. Isolated yields in the range of 50-70% were obtained.     

Viscoelastic characterization of selected foods over an extended frequency range

Three disparate food systems (gummy candy, Mozzarella cheese, and cooked ham) were characterized for their viscoelastic behavior under isothermal conditions over an extended frequency range of 10⁻³ to 10⁴ Hz using broadband viscoelastic spectroscopy (BVS). The materials were tested for any stress-induced fluid flow. However, no evidence of fluid flow was found under the tested frequency range. Validity of time–temperature superposition for the selected materials was also tested and compared with data from BVS.     

Biased Online Parameter Inference for State-Space Models

We consider Bayesian online static parameter estimation for state-space models. This is a very important problem, but is very computationally challenging as the state-of-the art methods that are exact, often have a computational cost that grows with the time parameter; perhaps the most successful algorithm is that of SM C² (Chopin et al., J R Stat Soc B 75: 397–426 2013). We present a version of the SM C² algorithm which has computational cost that does not grow with the time parameter. In addition, under assumptions, the algorithm is shown to provide consistent estimates of expectations w.r.t. the posterior. However, the cost to achieve this consistency can be exponential in the dimension of the parameter space; if this exponential cost is avoided, typically the algorithm is biased. The bias is investigated from a theoretical perspective and, under assumptions, we find that the bias does not accumulate as the time parameter grows. The algorithm is implemented on several Bayesian statistical models.     

Traction data analysis in reference to a unique zero condition

The lack of a unique definition for the zero condition leads to innumerable zero conditions resulting in different amounts of net traction at the same value of slip. In this paper, an attempt has been made to discuss various aspects of different zero conditions and finally result in a unique definition of the zero condition. Based on this definition, a traction prediction model using mobility number approach has been developed to evaluate the performance of tractor tyres in sandy clay loam soils.