Comment on “Effect of annealing temperature on structure, magnetic properties and optical characteristics in Zn0.97Cr0.03O nanoparticles” by Liu et al., [Appl. Surf. Sci. 256 (2010) 3559]

The authors of a recent paper (Appl. Surf. Sci. 256 (2010) 3559) studied the effect of annealing temperature on structural, magnetic and optical properties in Cr-doped zinc oxide (Zn_0.97Cr_0.03O) nanoparticles synthesized by sol-gel method. The authors have verified that Cr ions, in 3+ valence state, substitute the Zn ions in the ZnO lattice. They concluded that the ferromagnetism observed in the samples is an intrinsic property of the Cr-doped ZnO. However, we noticed an unusual point in this article. The Cr 2p XPS spectrum shown by them is against the general trend of the 2p XPS spectra of the transition metals. In this light, we re-measured the high-resolution 2p XPS spectrum of Cr for a 3% Cr-doped ZnO sample that is entirely different than theirs. The spectrum presented by them therefore demands proper interpretations or it might mislead the researchers in this developing field.     

Using path sampling to build better Markovian state models: predicting the folding rate and mechanism of a tryptophan zipper beta hairpin

We propose an efficient method for the prediction of protein folding rate constants and mechanisms. We use molecular dynamics simulation data to build Markovian state models (MSMs), discrete representations of the pathways sampled. Using these MSMs, we can quickly calculate the folding probability (P(fold)) and mean first passage time of all the sampled points. In addition, we provide techniques for evaluating these values under perturbed conditions without expensive recomputations. To demonstrate this method on a challenging system, we apply these techniques to a two-dimensional model energy landscape and the folding of a tryptophan zipper beta hairpin.     

Reaction of 2, 3, 4-pentantrione-3-arylhydrazones with N,N-dimethylhydrazine: Formation of substituted 1H-pyrazoles via demethylation

A novel one-step synthesis of 4-arylazo-1H-1, 3, 5-trimethylpyrazoles is accomplished by reaction of N, N-dimethylhydrazine with 2, 3, 4-pentantrione-3-arylhydrazones via an unusual demethylation.     

An expedient protocol for conversion of olefins to α-bromo/iodoketones using IBX and NBS/NIS

A variety of olefins have been shown to undergo conversion to the corresponding α-bromo/iodoketones when reacted with NBS/NIS and IBX in DMSO at room temperature. While the reaction is found to occur rapidly with e-rich arylolefins leading to the corresponding haloketones in 65-95% yields in 0.3-3.0 h, those containing e-withdrawing groups are found to yield diketones concomitantly, such that the latter are the exclusive products over extended duration of the reactions.     

Quantum entanglement in the NMR implementation of the Deutsch-Jozsa algorithm

A scheme to execute an n-bit Deutsch-Jozsa (DJ) algorithm using n qubits has been implemented for up to three qubits on an NMR quantum computer. For the one- and the two-bit Deutsch problem, the qubits do not get entangled, and the NMR implementation is achieved without using spin-spin interactions. It is for the three-bit case, that the manipulation of entangled states becomes essential. The interactions through scalar J-couplings in NMR spin systems have been exploited to implement entangling transformations required for the three bit DJ algorithm.     

On the noniterative multiproduct multiperiod production planning method

Bahl and Zionts [H.C. Bahl, S. Zionts, A noniterative multiproduct multiperiod production planning method, Operations Research Letters 1 (1982) 219-221] formulated a problem for planning multiproduct multiperiod production on a single facility. They developed a column-minima noniterative method and claimed that it gave an optimal solution. We show that the claim is incorrect.     

Validated ultra-performance liquid chromatography tandem mass spectrometry method for the determination of pramipexole in human plasma

A sensitive and high throughput ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS-MS) method has been developed for the determination of pramipexole, a dopamine agonist, in human plasma. Sample preparation involved liquid-liquid extraction of pramipexole and ranitidine as the internal standard (IS) in ethyl acetate from 100 μL human plasma. The chromatographic separation is achieved on a Waters Acquity UPLC BEH C18 (100 mm × 2.1 mm, 1.7 μm) analytical column using an isocratic mobile phase, consisting of 10 mM ammonium formate (pH 7.50)-acetonitrile (15:85, v/v), at a flow-rate of 0.5 mL/min. The precursor → product ion transition for pramipexole (m/z 212.1 → 153.0) and IS (m/z 315.0 → 176.1) were monitored on a triple quadrupole mass spectrometer, operating in the multiple reaction monitoring (MRM) and positive ion mode. The method was validated over a wide dynamic concentration range of 20-4020 pg/mL. Matrix effect is assessed by post-column infusion experiment and the process efficiency were 91.9% and 85.7% for pramipexole and IS, respectively. The method is rugged and rapid with a total run time of 1.5 min and is applied to a bioequivalence study of 0.25 mg PPX tablet formulation in 30 healthy Indian male subjects under fasting condition.     

Resolving overlaps in diffusion encoded spectra using band-selective pulses in a 3D BEST-DOSY experiment

A novel diffusion-edited 3D NMR experiment that incorporates a BEST-HMQC pulse sequence in its implementation is presented. Heteronuclear 3D DOSY NMR experiments are useful in elucidating the diffusion coefficients of individual constituents of a mixture, especially in cases where the proton NMR 2D DOSY spectra show considerable overlap. The present 3D BEST-DOSY pulse sequence provides a more sensitive and less time-consuming alternative to standard 3D HMQC-DOSY experiments. Cleanly separated subspectra of individual mixture components are obtained, leading to the determination of diffusion coefficients with better accuracy. The feasibility of the technique is demonstrated on a mixture of amino acids, on a mixture of small molecules with similar diffusion coefficients, and on a complex mixture with large dynamic range (commercial gasoline). The implications of using adiabatic decoupling schemes and band-selective shaped pulses for selective BEST-DOSY experiments on proteins are also discussed.     

Study of Ethyl Cellulose—Benzoic Acid Interactions in Matrices for Controlled Drug Release by DSC

The physical state of benzoic acid (BA) and its interaction with ethyl cellulose (EC) were examined in ethyl cellulose—benzoic acid matrices by Differential Scanning Calorimetry (DSC). The glass transition temperature (T_g) of EC of various matrices having BA in solid solution form (upto 27.7%) was reduced. The BA in matrices containing more than 38.9% drug exhibited distinct melting endotherms due to crystalline form. The peak temperatures of these endotherms were lowered and they broadened as the concentration was lowered. The solubility of BA increased at its melting point as compared to ambient temperature. The melting enthalpy of BA, when plotted as a function of its concentration yielded a straight line with intercept of 330 mg g^–1 of matrix. This is the solubility of BA in EC at its melting temperature. Fourier Transform Infra Red Spectroscopy (FTIR) investigations confirmed that hydrogen bonding occurred between EC and BA through hydroxyl groups.This revised version was published online in November 2005 with corrections to the Cover Date.     

Selective excitation of vibrational modes of polyatomic molecule

Mode-selective dynamics of triatomic molecule in the electronic ground state under continuous wave laser pulse is investigated for the discrete vibrational bound states. A non-perturbative approach has been used to analyse the vibrational couplings and dynamics of the molecule.