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Despitethe fact that polarizability of water is different in thebulk and in protein, simulations of protein–ligand complexesare mostly carried out in nonpolarizable water media. We present oxime(HI-6) unbinding from the active site gorge of AChE, known to be stronglyinfluenced by intermolecular cation-π, hydrogen bridge (HB)and water bridge (WB) interactions and by molecular simulations witheffective polarization in polarizable mean-field model of TIP3P water.Enabled by the recent availability of a method of obtaining microkineticsof rare events, we set out to investigate the rate constants of unbindingtransitions from one basin to the other through a combination of metadynamicsand hyperdynamics simulations. The results underpin the importanceof electronic polarization effects on the pathways, potential of meanforce, rate constants, and HB and WB dynamics of unbinding transitionsof a drug molecule ligated to protein interior. The method is alsoapplicable to unravel the binding mechanisms. [ABSTRACT FROM AUTHOR]

A detailedstudy has been done on the phase behavior and rheologicalproperties of viscoelastic surfactant (VES)-based fracturing fluidsbearing lamellar liquid crystal structures that are developed fromtwo surfactants (SDS and NaOA) and three co-surfactants (propan-2-ol, iso-amyl alcohol, and 2-ethyl hexanol) in the presence ofclove oil as the organic phase and water as the aqueous phase. Lamellarliquid crystals prepared from NaOA/2-ethyl hexanol/clove oil/watersystem demonstrated the best viscoelastic properties among all thedeveloped fluids, because it exhibited resistance to high temperatureand shear conditions. The addition of alkali and nanoparticles enhancedthe viscoelastic properties, which were observed from static and dynamicrheological tests. [ABSTRACT FROM AUTHOR]

The efficacy of some bio-rational insecticides against, tea looper complex, Hyposidra spp. was evaluated at two different locations of Dooars tea plantations, West Bengal. The results indicated that all the insecticides were effective in reducing the looper population to a significant level. However, in comparison to other insecticides, neem based insecticides could not give the desired level of control. Among the different treatments, diflubenzuron 25 WP @ 700g/ha caused maximum reduction of loopers over control in both the sprayings at both the locations [Location 1: 66.91% and 65.54% reduction of loopers at 7 days after 1st and 2nd spraying respectively) and Location 11: 68% and 50.85% reduction of loopers at 7 days after 1st and 2nd spraying respectively)] and appeared to be the best treatment against loopers. Br-k @ 1000 mL/ha was the next best treatment for suppressing looper population at 7 days after 2nd spraying (64.44% and 67.81% reduction of loopers at Location I and II respectively) which was at par with recommended insecticide deltamethrin 2.8 EC @ 200 mL/ha (65.14% and 62.16% reduction of loopers at Location I and II respectively). However, in 2nd spraying, its efficacy was declined. Both the doses of Neem based insecticides recorded 31-49% reduction of loopers after 151 spraying but this was reduced only to 9-17% after 2nd spraying, Thus, in consideration of the performance of the insecticides, diflubenzuron @700 g/ha and Bt-k @ 1000 mL/ha could be included in the IPM package of looper. [ABSTRACT FROM AUTHOR]

Weighted average IR spectra of CO3•−·nH2O (n= 1−6) clusters are reported and compared with those of CO32−·nH2O (n= 1−6) clusters based on quantum chemical calculations. Simulated annealing combined with the Monte Carlo sampling method is also applied to locate the global minimum energy structure. It is observed that hydrated clusters of CO3•−ion having cyclic water networks are the most stable structure in each size of hydrated cluster. IR bands at the lower side of the O−H stretching region of water correspond to single/double hydrogen bonding interaction, and those in the higher side correspond to inter water hydrogen bonding for the lower clusters (n= 2−3). For the tetrahydrated cluster of CO3•−ion, a complete crossover of the IR spectra in the O−H stretching region occurred. Cyclic water networks having three or four solvent water molecules are characterized by strong peaks at 3550 and 3450 cm−1. In the case of CO3•−·nH2O clusters, O−H stretching bands of all of the solvent water molecules are above 3100 cm−1in contrast to that of CO32−·nH2O clusters showing distinctive IR signature. This suggests that size selected hydrated clusters of CO3•−and CO32−ions can easily be distinguished on the basis of their IR spectra. [ABSTRACT FROM AUTHOR]

Structure, stability, and vibrational IR and Raman spectra of I2•−.nCO2clusters (n= 1−10) are reported based on first-principle electronic structure calculations. Several close-lying minimum energy structures are predicted for these solvated clusters following the quasi Newton−Raphson procedure of geometry optimization. Search strategy based on Monte−Carlo simulated annealing is also applied to find out the global minimum energy structures of these clusters. Successive addition of solvent CO2molecules to the negatively charged diatomic solute, I2•−, is fairly symmetrical. Energy parameters of these solvated clusters are calculated following second-order Moller−Plesset perturbation (MP2) as well as coupled cluster theory with 6−311+G(d) set of basis function (I atom is treated with 6−311G(d) set of basis function). The excess electron in these solvated clusters is observed to be localized mainly over the two I atoms. Average interaction energy between the anionic solute, I2•−, and a solvent CO2molecule is ∼129 meV in I2•−.nCO2clusters, and the average interaction energy between two solvent CO2molecules is ∼85 meV in the case of neutral (CO2)nclusters at MP2 level of theory. IR spectra show similar features in all these solvated clusters, depicting a strong band at ∼2330 cm−1for C−O stretching and a weak band at ∼650 cm−1for CO2bending modes. Degeneracy of the bending mode of a free solvent CO2unit gets lifted when it interacts with the charged solute I2•−to form a molecular cluster because of the change in structure of solvent CO2units. The vibrational band at the bending region of CO2in the Raman spectra of these anionic clusters shows a characteristic feature for the formation of I2•−.nCO2clusters showing a Raman band at ∼650 cm−1. [ABSTRACT FROM AUTHOR]

A systematic study on the structure and stability of nitrate anion hydrated clusters, NO3-·nH2O (n1−8) are carried out by applying first principle electronic structure methods. Several possible initial structures are considered for each size cluster to locate equilibrium geometry by applying a correlated hybrid density functional with 6-311G(d,p) basis function. Three different types of arrangements, namely, symmetrical double hydrogen bonding, single hydrogen bonding and inter-water hydrogen bonding are obtained in these hydrated clusters. A structure having inter-water hydrogen bonding is more stable compared to other arrangements. Surface structures are predicted to be more stable over interior structures. Up to five solvent H2O molecules can stay around solute NO3-anion in structures having an inter-water hydrogen-bonded cyclic network. A linear correlation is obtained for weighted average solvent stabilization energy with the size (n) of the hydrated cluster. Distinctly different shifts of IR bands are observed in these hydrated clusters for different kinds of bonding environments of O−H and NO stretching modes compared to isolated H2O and NO3-anion. Weighted average IR spectra are calculated on the basis of statistical population of individual configurations of each size cluster at 150 K. [ABSTRACT FROM AUTHOR]

Structure and properties of hydrated clusters of halogen gas, X2·nH2O (X Cl, Br, and I; n1−8) are presented following first principle based electronic structure theory, namely, BHHLYP density functional and second-order Moller−Plesset perturbation (MP2) methods. Several geometrical arrangements are considered as initial guess structures to look for the minimum energy equilibrium structures by applying the 6-311G(d,p) set of the basis function. Results on X2−water clusters (X Br and I) suggest that X2exists as a charge separated ion pair, X−X-in the hydrated clusters, X2·nH2O (n≥ 2). Though the optimized structures of Cl2·nH2O clusters look like X2·nH2O (X Br and I) clusters, Cl2does not exist as a charge separated ion pair in the presence of solvent water molecules. The calculated interaction energy between X2and solvent water cluster increases from Cl2·nH2O to I2·nH2O clusters, suggesting solubility of gas-phase I2in water to be a maximum among these three systems. Static and dynamic polarizabilities of hydrated X2clusters, X2·nH2O, are calculated and observed to vary linearly with the size (n) of these water clusters with correlation coefficient >0.999. This suggests that the polarizability of the larger size hydrated clusters can be reliably predicted. Static and dynamic polarizabilities of these hydrated clusters grow exponentially with the frequency of an external applied field for a particular size (n) of hydrated cluster. [ABSTRACT FROM AUTHOR]

The synthesis of complex oligosaccharides has been a challenge for researchers. Herein, we describe a strategy for the synthesis of an activated oligomannan 1that employs ionic liquid (IL) support glycosylation methodology on an IL-tagged mannosyl fluoride donor. This method is capable of rapidly producing linear (1→6) oligomannan thioglycosides in a convenient and cost-effective manner without the need of column purification after each glycosylation step. [ABSTRACT FROM AUTHOR]

Compositional and temperature dependent thermoelectric power measurements have been performed on the polycrystalline manganite perovskite system: La1?xCaxMnO3+?(x= 0.00, 0.25, 0.33, 0.50 and 1.00), in the paramagnetic state (T> Tc) (300-673?K). The Seebeck coefficient (?) has been used to calculate the Fermi energy, the activation energy (E?), the Mn4+-ion concentration and the oxygen content (?), for different compositions. The observed decrease in E?with increase in Ca-concentration and a large value of E?as compared with a relatively high temperature sintered material of the same compositions have been explained in the light of the decrease in the interatomic distances and grain growth with Ca-substitution. It is shown that [Mn4+][Mn3+] ion concentration is not the only factor that governs conduction in the manganite perovskites. The significantly small values of ? (?22?µV?K?1) at high temperature can be explained on the basis of (Mn3+-Mn3+) charge disproportionation into stable Mn2+-Mn4+pairs in the system rather than on the basis of nominal Mn3+/4+valence arguments. Finally, nearly temperature independent variation of ?, charge-carrier concentration at high temperature and low value of mobility are hallmarks of small polaron hopping. [ABSTRACT FROM AUTHOR]

A method for defect-free large crystallite graphene growth remains unknown despite much research effort. In this work, we discuss the role of flow duration of H2 gas for the production of graphene as per requirement and production at a minimum flow rate considering the safety issue of hydrogen utilization. The copper substrate used for growth was treated for different time intervals (0 to 35 min) in H2 flow prior to growth. Structural and chemical changes occurring in the copper substrate surface were probed by grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy. The results were correlated with the Raman spectroscopy data, which can quantify the quality of graphene. With increasing H2 flow interval, secondary nucleation sites were observed and growth favored few-layer graphene structures. The surface-adsorbed oxygen molecules and its conversion to an OH terminated surface with increasing hydrogen flow interval was found to be a key factor in enhancing nucleation density. The Stranski–Krastanov type of nucleation was observed for samples grown with different time intervals of H2 treatment, except 5 min of H2 flow prior to growth for which the Volmer–Weber type of growth favored monolayer graphene crystallite growth. [ABSTRACT FROM AUTHOR]

Lung cancer is one of the leading causes of cancer death worldwide. Survival has not improved significantly in spite of newer therapies. In view of the high-symptom burden and severe morbidity, evaluation of quality of life (QOL) becomes important in these patients. Several instruments are now available for this purpose, and have demonstrated good correlation with performance status, symptoms, and survival. Quality of life assessments also help in comparing different therapeutic regimes, thus allowing selection of the appropriate modality. Problems of inconsistent interpretability and high-patient dropout rate poses a challenging problem that needs to be tackled. In spite of these drawbacks, QOL is now considered to be an essential component of lung cancer management and should be performed routinely. Such a practice will help the physician plan appropriate treatment strategies and set practical therapeutic goals. [ABSTRACT FROM AUTHOR]

The influence of a uniform static external electric field on some aliphatic and aromatic molecular species is studied within the density functional theory (DFT) employing the 6-311G(2d,2p) basis set with B3LYP exchange-correlation prescription. The electric field perturbs the molecular geometry but drastically alters the dipole moments and engenders, to a varying degree, the molecular vibrational Stark effect, i.e., shifts in the infrared (IR) vibrational frequencies accompanied by spectral intensity redistribution. For polar molecules, significant negative (“red”) and positive (“blue”) frequency shifts are observed for field orientations both parallel and antiparallel to their permanent dipole moments. Further, a selective reordering of frontier orbitals is observed to be brought about by moderately intense fields. In particular, molecules having a lowest unoccupied molecular orbital (LUMO) with predominant character possess a threshold field beyond which energy gap between the highest occupied molecular orbital (HOMO) and LUMO diminishes rapidly. A time-dependent (TD) DFT analysis reveals that an increase in the applied field strength by and large increases the excitation energies corresponding to significant electronic transitions among frontier MOs with a concomitant decrease in their oscillator strengths. [ABSTRACT FROM AUTHOR]

The present article comprises a theoretical study of structures and energetics of the lowest energy conformers of peroxyformic acid (PFA) and its hydrated variants, viz. PFA···(H2O)n(n 1−4), at the molecular level. We have employed two different ab initio quantum chemical methods, viz. restricted Hartree−Fock (RHF) and the second-order Møller−Plesset (MP2) perturbation theory with the basis sets 6-31G(d,p) and 6-311G(2d,2p). Modifications in the structure as well as vibrational frequencies of PFA brought about by successive addition of H2O molecules are also discussed. Cooperativity of hydrogen bonding in these clusters can be gauged through a detailed many body interaction energy analysis. [ABSTRACT FROM AUTHOR]