Growth of monodisperse nanocrystals of cerium oxide during synthesis and annealing

Monodisperse cerium oxide nanocrystals have been successfully synthesised using simple ammonia precipitation technique from cerium(III) nitrate solution at different temperatures in the range 35–80 °C. The activation energy for growth of CeO₂ nanocrystals during the precipitation is calculated as 11.54 kJ/mol using Arrhenius plot. Average crystal diameter was obtained from XRD analysis, HR-TEM and light scattering (PCS). The analysis of size data from HR-TEM images and PCS clearly indicated the formation of highly crystalline CeO₂ particles in narrow size range. CeO₂ nanocrystals precipitated at 35 °C were further annealed at temperatures in the range 300–700 °C. The activation energy for crystal growth during annealing is also calculated and is close to the reported values. An effort is made to predict the mechanism of crystal growth during the precipitation and annealing.     

Synthesis and characterization of Bi-doped zirconia for solid electrolyte

(100-x)ZrO₂(x)Bi₂O₃ (x = 5, 10, 15) system has been synthesized by solid-state reaction technique. Tetragonal Bi_7.38Zr_0.62O_12.31 phase has formed in all the samples after sintering at 850 °C for 24 h. Apart from this, ZrO₂ and Bi₂O₃ are also identified as minority phases. The volume fraction of Bi_7.38Zr_0.62O_12.31 phase increases with increasing concentration of Bi₂O₃. The AC conductivity plots exhibit phase transition at 570 °C and 460 °C for x = 10 and x = 15 samples, respectively. The maximum conductivity is observed (1.60 mS/cm) in x = 15 sample. These results are correlated and supported with microstructural and thermal analysis.     

Interacting branching process as a simple model of innovation

We describe innovation in terms of a generalized branching process. Each new invention pairs with any existing one to produce a number of offspring, which is Poisson distributed with mean p. Existing inventions die with probability p/τ at each generation. In contrast with mean field results, no phase transition occurs; the chance for survival is finite for all p > 0. For τ = ∞, surviving processes exhibit a bottleneck before exploding superexponentially-a growth consistent with a law of accelerating returns. This behavior persists for finite τ. We analyze, in detail, the asymptotic behavior as p→0.     

Generalized Univex Functions in Nonsmooth Multiobjective Optimization

In this paper, we have considered a nonsmooth multiobjective optimization problem where the objective and constraint functions involved are directionally differentiable. A new class of generalized functions (d???ρ???η???θ)-type I univex is introduced which generalizes many earlier classes cited in literature. Based upon these generalized functions, we have derived weak, strong, converse and strict converse duality theorems for mixed type multiobjective dual program in order to relate the efficient and weak efficient solutions of primal and dual problem.     

Pyrazole‐4‐carboxylic Acids from Vanadium‐catalyzed Chemical Transformation of Pyrazole‐4‐carbaldehydes

The conversion of aldehydes into carboxylic acids using oxidizing agents is a common protocol in transformation chemistry. An efficient oxidation strategy of transformation of pyrazole‐4‐aldehydes to the corresponding acids using vanadium catalysts in the presence of 30% H₂O₂ as an oxidant is described. The catalytic technology was successfully applied to a range of various 4‐formylpyrazoles, and plausible mechanism is also discussed.     

Design and Synthesis of Imidazole and Triazole Pyrazoles as Mycobacterium Tuberculosis CYP121A1 Inhibitors

The emergence of untreatable drug-resistant strains of Mycobacterium tuberculosis is a major public health problem worldwide, and the identification of new efficient treatments is urgently needed. Mycobacterium tuberculosis cytochrome P450 CYP121A1 is a promising drug target for the treatment of tuberculosis owing to its essential role in mycobacterial growth. Using a rational approach, which includes molecular modelling studies, three series of azole pyrazole derivatives were designed through two synthetic pathways. The synthesized compounds were biologically evaluated for their inhibitory activity towards M. tuberculosis and their protein binding affinity (K_D). Series 3 biarylpyrazole imidazole derivatives were the most effective with the isobutyl ( 10 f ) and tert-butyl ( 10 g ) compounds displaying optimal activity (MIC 1.562 μg/mL, K_D 0.22 μM ( 10 f ) and 4.81 μM ( 10 g )). The spectroscopic data showed that all the synthesised compounds produced a type II red shift of the heme Soret band indicating either direct binding to heme iron or (where less extensive Soret shifts are observed) putative indirect binding via an interstitial water molecule. Evaluation of biological and physicochemical properties identified the following as requirements for activity: LogP >4, H-bond acceptors/H-bond donors 4/0, number of rotatable bonds 5–6, molecular volume >340 ų, topological polar surface area <40 Ų.     

Bound anionic states of DNA and RNA nucleobases: An EOM-CCSD investigation

In this article, we have studied the bound anionic states of DNA and RNA nucleobases using the newly developed bt-PNO-EOM-CCSD method and extended basis sets. All of the five nucleobases have a single bound anionic state, which is dipole bound in nature. The electron affinity corresponding to the dipole-bound state is found to be extremely sensitive to the used basis set, and a proper agreement with the available experimental data requires a large basis set with a sufficient number of diffuse functions. Electron correlation plays a major role in stabilizing the bound anionic states of nucleobases. No valence-bound anionic states are observed for any of the nucleobases.