Efficient and Industrially Viable Synthesis of Donepezil

An efficient, economically viable process has been developed for large‐scale preparation of donepezil HCl (1), an anti‐Alzheimer's agent. The process involves the condensation of 5,6‐dimethoxy‐1‐indanone (3) and 1‐benzyl‐4‐piperidinecarboxaldehyde (4) in the presence of alkalimetal carbonates at elevated temperature to yield 1‐benzyl‐4‐[(5,6‐dimethoxy‐1‐indanone)‐2‐yidenyl] methyl piperidine (2), the key intermediate in the synthesis of donepezil. Hydrogenation of 2 yields donepezil.     

Studies of Nucleophilic Substitution Reactions of p‐Nitrophenyl Acetate with Some Dihydroxamate Ions in Cationic Micellar Media

Pseudo‐first‐order rate constants have been determined for the nucleophilic substitution reactions of p‐nitrophenyl acetate with oxalo, malono, and succinodihydroxamate ions (^?ONHC(O)(CH₂)_nC(O)NHO^?) in phosphate buffer (pH=7.9) at 27°C. The rate data of the reaction revealed that the nucleophilic reactivity sequence of these hydroxamate ions is generally ODHA>MDHA>SDHA. The k_obs value increases upon addition of cationic surfactants to the reaction medium which is typical behavior of micelle‐assisted bimolecular reactions. The pseudo‐phase ion exchange model has been successfully applied to determine binding constant.     

Effects of oxidation pretreatment temperature on Kovar used as CO_2 reforming catalyst

The effect of oxidation pretreatment temperature(500 ~ 1 000 ℃) on the catalytic activity of Kovar applied on hydrocarbon CO2reforming was examined. Catalytic performance evaluation using tetradecane at 800 ℃ with 70 μmol/s CO2revealed 700 and 1 000 ℃ as the best pre-oxidation temperature in producing CO and H2,respectively. XRD and SEM-EDX analyses showed that a separate metal oxide layer composed of iron oxide(Fe2O3and F3O4),nickel,cobalt,and possibly their respective oxides started to form when oxidation was conducted at 700 ℃ or higher.The presence of iron enhanced the stability of nickel in the structure while the compact structure of Fe3O4resulted into the formation of a thick and rigid metal oxide layer on the surface of the Kovar tube. The strong physical bond between the metal oxide layer and Kovar tube provided the catalyst good mechanical strength and consequently good catalytic activity.     

Structural and magnetic studies on spark plasma sintered SmCo5/Fe bulk nanocomposite magnets

SmCo₅+x wt% Fe (x=0$x=0$, 5 and 10) nanocomposite powders were synthesized by mechanical milling and were consolidated into bulk shape by spark plasma sintering (SPS) technique. The evolution of structure and magnetic properties were systematically investigated in milled powders as well as in SPS samples. A maximum coercivity of 8.9 kOe was achieved in spark plasma sintered SmCo₅+5 wt% Fe sample. The exchange spring interaction between the hard and soft magnetic phases was evaluated using δM–H measurements and the analysis revealed that the SPS sample containing 5 wt% Fe had a stronger exchange coupling between the magnetic phases than that of the sample with10 wt% Fe.     

A Factorial Design Approach for Hydrothermal Synthesis of Phase‐Pure AgInO2: A Parametric Optimization Study

Owing to a wide range of industrial applications and fundamental importance, delafossite compounds have gathered tremendous interest in research community. In this study, the formation of hexagonal nanoplates of AgInO₂ mainly dominated by (00l) facets with no metallic Ag impurity, reported using a facile hydrothermal route at 180 °C using KOH as mineralizer by adopting a factorial design approach. Rietveld analysis of the powder XRD pattern and SAED confirms the rhombohedral system of AgInO₂. FE‐SEM image shows a uniform hexagonal plate‐like morphology with an average width of about 300 nm and thickness of 70 nm. XPS and EDX analysis confirm potassium ion free AgInO₂. A specific surface area of about 48.5 m² g^?1 is arrived from N₂ adsorption studies. Temperature‐dependent AC impedance measurements revealed an activation energy of 0.24 eV/f.u. Further, TG‐DTA studies found that the compound is stable in air up to 595 °C.     

Poisson structures due to Lie algebra representations

Using a unitary solution of the classical Yang-Baxter equation on a Lie algebraG we describe a particular way of constructing homogeneous quadratic Poisson structures on the dual of aG-moduleV and study some local features of the symplectic foliation due to the involutive distribution of the Hamiltonian vector fields. We also give some examples where the symplectic leaves are explicitly calculated.     

Effective thermal conductivity of granulated two-phase systems at interstitial air pressures

Considering the htermal conduction through molecular collisions an expression for the effective thermal conductivityλ _e of loose and granular two-phase materials at different interstitial air pressure has been derived. The dependence ofλ _e on pore and particle sizes, characteristic pressure and radiative heat transfer is also discussed. Calculated values ofλ _e of glass beads and loose building materials are compared with reported results.     

Testing Hypotheses About the Power Law Process Under Failure Truncation Using Intrinsic Bayes Factors

Conventional Bayes factors for hypotheses testing cannot typically accommodate the use of standard noninformative priors, as such priors are defined only up to arbitrary constants which affect the values of the Bayes factors. To circumvent this problem, Berger and Pericchi (1996, J. Amer. Statist. Assoc., 19, 109-122) introduced a new criterion called the Intrinsic Bayes Factor (IBF). In this paper, we use their methodology to test several hypotheses regarding the shape parameter of the power law process. Assuming that we have data from the process according to the failure-truncation sampling scheme, we derive the arithmetic and geometric IBF's using the reference priors. We deduce a set of intrinsic priors that correspond to these IBF's, as the observed number of failures tends to infinity. We then use these results to analyze an actual data set on the failures of an aircraft generator.     

Photoelasticity in quasicrystals

The maximum number of non-vanishing and independent second order photoelastic coefficients required by the seven pentagonal and the two icosahedral point groups 5(C₅), (S₁₀), (C_5h ), m2(D_5h ), 52(D₅), 5m(C_5v ), 2m(D_5d ); 235(I), 2/m (I _h )—that describe the quasicrystals symmetry groups in two and three dimensions—is obtained. The schemes of non-vanishing and independent coefficients have been calculated and listed. Finally the results of this group-theoretical study are briefly discussed.     

Multiple scattering of gamma rays in water,concrete and sand

The transmitted photon spectra of¹³³Ba,²²Na,¹³⁷Cs,⁵⁴Mn and⁶⁰Co point sources are measured through different thicknesses of water, concrete and sand. The multiple-scatter peaks observed in these materials at 60, 90 and 100 keV energies respectively are found to be independent of incident photon energy and thickness of the medium.