Ion irradiation induced nano pattern formation on TiO2 single crystal

Nanodots have been fabricated on rutile TiO₂(1 1 0) single crystals using Ar ion beam. Ion beam sputtering creates oxygen vacancies, leading to a 45 nm thick Ti rich layer, on the surface. Post-sputtering, rutile TiO₂ also exhibits a decrease in the inter planar separation along [1 1 0] direction. Additionally, blueshift in the E_g Raman mode, representing the vibrations of oxygen atoms along c-axis, is also observed. Both these results suggest the development of a compressive stress along c-axis upon sputtering. Enhancement in intensity of A_1g Raman mode also indicates modification in TiO vibrational influence.     

Aripiprazole Loaded Polymeric Biodegradable Microspheres: Formulation and In Vitro Characterization

In the present study, we attempted to prepare biodegradable microspheres of polylactic acid containing aripiprazole in order to achieve its controlled release profile suitable for parenteral administration. Biodegradable microspheres were prepared by solvent evaporation method using methylene dichloride as a solvent. The optimization of various formulation variables (e.g., stirring speed, and polymer:drug ratio, stabilizer concentration) to obtain spherical particles was also investigated. The optimized product was further characterized for various in vitro attributes, such as particle size and its distribution, encapsulation efficiency, surface properties, percentage yield, and in vitro release. Changing the ratio of polymer, stabilizers, and leaching agent (sodium chloride) affected the entrapment efficiency and release rate of aripiprazole. The release quantum was 88.41% when stirring rate was 2000 rpm and it was further increased to 94.65% when stirring speed was increased to 3000 rpm (Formulation E). Drug entrapment of microspheres was increased by increasing the concentration of PVP and maximum entrapment (62.35%) was obtained at 4% concentration of PVP (Formulation E). Spherical particles with good surface characteristics were obtained at stirring rate 3000 rpm and drug:polymer ratio 1:10.     

CAESAR: a new conformer generation algorithm based on recursive buildup and local rotational symmetry consideration

A highly efficient conformer search algorithm based on a divide-and-conquer and recursive conformer build-up approach is presented in this paper. This approach is combined with consideration of local rotational symmetry so that conformer duplicates due to topological symmetry in the systematic search can be efficiently eliminated. This new algorithm, termed CAESAR (Conformer Algorithm based on Energy Screening and Recursive Buildup), has been implemented in Discovery Studio 1.7 as part of the Catalyst Component Collection. CAESAR has been validated by comparing the conformer models generated by the new method and Catalyst/FAST. CAESAR is consistently 5-20 times faster than Catalyst/FAST for all data sets investigated. The speedup is even more dramatic for molecules with high topological symmetry or for molecules that require a large number of conformers to be sampled. The quality of the conformer models generated by CAESAR has been validated by assessing the ability to reproduce the receptor-bound X-ray conformation of ligands extracted for the Protein Data Bank (PDB) and assessing the ability to adequately cover the pharmacophore space. It is shown that CAESAR is able to reproduce the receptor-bound conformation slightly better than the Catalyst/FAST method for a data set of 918 ligands retrieved from the PDB. In addition, it is shown that CEASAR covers the pharmacophore space as well or better than Catalyst/FAST.     

Novel Chemoselective Reduction of Aldehydes in the Presence of Other Carbonyl Moieties with Thiourea Dioxide

Reduction of a variety of aldehydes in the presence of other carbonyl moieties to the corresponding alcohols occurs chemoselectively in high yields upon treatment with inexpensive reagent thiourea dioxide (TUDO) in aqueous alkali–ethanolic system for 2 h at 90 °C.     

Wavelet based schemes for linear advection-dispersion equation

In this paper, two wavelet based adaptive solvers are developed for linear advection-dispersion equation. The localization properties and multilevel structure of the wavelets in the physical space are used for adaptive computational methods for solution of equation which exhibit both smooth and shock-like behaviour. The first framework is based on wavelet-Galerkin and the second is based on multiscale decomposition of finite element method. Coiflet wavelet filter is incorporated in both the methods. The main advantage of both the adaptive methods is the elimination of spurious oscillations at very high Peclet number.     

Parity checking and generating circuit with semiconductor optical amplifier in all-optical domain

In this paper, an all-optical parity checker and parity generator circuit is proposed in which SOA-MZI configuration is used to implement the XOR logic gate. This performance monitoring logic device is simulated at ultra high speed i.e. 120 GHz. Two logic circuits are proposed for parity generator, in one design inverter used to generate parity bit is implemented by the same additional XOR gate as inverter while in 2nd design inverter is implemented using XGM in SOA and thus number of SOA in 2nd design is reduced. ER ratio achieved in 1st case is 9.28 with maximum Q factor 73.39 and minimum BER 0 while in 2nd design it is 9.35 with maximum Q factor 8.41 and minimum BER 1.93e−17. ER ratio achieved in parity checker circuit is 32.54 with maximum Q factor 77.76 and minimum BER 0.     

Coherent switching with decay of mixing: an improved treatment of electronic coherence for non-Born-Oppenheimer trajectories

The self-consistent decay-of-mixing (SCDM) semiclassical trajectory method for electronically nonadiabatic dynamics is improved by modifying the switching probability that determines the instantaneous electronic state toward which the system decoheres. This method is called coherent switching with decay of mixing (CSDM), and it differs from the previously presented SCDM method in that the electronic amplitudes controlling the switching of the decoherent state are treated fully coherently in the electronic equations of motion for each complete passage through a strong interaction region. It is tested against accurate quantum mechanical calculations for 12 atom-diatom scattering test cases. Also tested are the SCDM method and the trajectory surface hopping method of Parlant and Gislason that requires coherent passages through each strong interaction region, and which we call the "exact complete passage" trajectory surface hopping (ECP-TSH) method. The results are compared with previously presented results for the fewest switches with time uncertainty and Tully's fewest switches (TFS) surface hopping methods and the semiclassical Ehrenfest method. We find that the CSDM method is the most accurate of the semiclassical trajectory methods tested. Including coherent passages improves the accuracy of the SCDM method (i.e., the CSDM method is more accurate than the SCDM method) but not of the trajectory surface hopping method (i.e., the ECP-TSH method is not more accurate on average than the TFS method).     

An efficient one step dihydroxylation of 1,2-glycals with oxone in acetone

A number of glycals have been converted into the corresponding 1,2-diols in fair to good yields. The reaction appears to proceed via the corresponding epoxide which opens in situ.     

6‐(Diazomethyl)‐1,3‐bis(methoxymethyl)uracil,Synthesis and Transformation into Annulated Pyrimidinediones

6‐(Diazomethyl)‐1,3‐bis(methoxymethyl)uracil ( 5 ) was prepared from the known aldehyde 3 by hydrazone formation and oxidation. Thermolysis of 5 and deprotection gave the pyrazolo[4,3‐d]pyrimidine‐5,7‐diones 7a and 7b . Rh₂(OAc)₄ catalyzed the transformation of 5 into to a 2 : 1 (Z)/(E) mixture of 1,2‐diuracilylethenes 9 (67%). Heating (Z)‐ 9 in 12n HCl at 95° led to electrocyclisation, oxidation, and deprotection to afford 73% of the pyrimido[5,4‐f]quinazolinetetraone 12 . The Rh₂(OAc)₄‐catalyzed reaction of 5 with 3,4‐dihydro‐2H‐pyran and 2,3‐dihydrofuran gave endo/exo‐mixtures of the 2‐oxabicyclo[4.1.0]heptane 13 (78%) and the 2‐oxabicyclo[3.1.0]hexane 15 (86%), Their treatment with AlCl₃ or Me₂AlCl promoted a vinylcyclopropane–cyclopentene rearrangement, leading to the pyrano‐ and furanocyclopenta[1,2‐d]pyrimidinediones 14 (88%) and 16 (51%), respectively. Similarly, the addition product of 5 to 2‐methoxypropene was transformed into the 5‐methylcyclopenta‐pyrimidinedione 18 (55%). The Rh₂(OAc)₄‐catalyzed reaction of 5 with thiophene gave the exo‐configured 2‐thiabicyclo[3.1.0]hexane 19 (69%). The analoguous reaction with furan led to 8‐oxabicyclo[3.2.1]oct‐2‐ene 20 (73%), and the reaction with (E)‐2‐styrylfuran yielded a diastereoisomeric mixture of hepta‐1,4,6‐trien‐3‐ones 21 (75%) that was transformed into the (1E,4E,6E)‐configured hepta‐1,4,6‐trien‐3‐one 21 (60%) at ambient temperature.