Effect of crystallization behavior of polyethylene glycol 6000 on the properties of granules prepared by fluidized hot-melt granulation (FHMG)

The objective of this study was to investigate the effect of the crystallization behavior of Macrogol 6000 (polyethylene glycol 6000; PEG 6000), used as a binder, during the solidification process on the properties of mononucleic granules prepared by the fluidized hot-melt granulation (FHMG) technique. Crystallization of PEG 6000 from molten liquid was investigated using differential scanning calorimetry (DSC) and hot stage microscopy. The results obtained from the measurement of isothermal crystallization demonstrated that crystallization of PEG 6000 was either slow or rapid. Analysis based on solid-state decomposition showed that slow crystallization was due to the two-dimensional growth of nuclei mechanism, while rapid crystallization was due to the three-dimensional growth of nuclei mechanism. Observation of the crystallization of PEG 6000 by hot stage microscopy supported the existence of two different crystallization mechanisms. Granules containing PEG 6000 that underwent rapid crystallization during FHMG showed a significantly higher fraction powder under 150 microm in diameter. This was caused by the loss of powder particles from the surface of mononucleic granules during the solidification process, because many cracks were observed after crystallization of PEG 6000 with a short isothermal crystallization time (ICT) due to the reduced of sticking of particles. The results of this study suggested that the crystallization behavior of the binder during the solidification process of FHMG can influence the properties of the resultant granules, such as particle size distribution, content uniformity or taste masking. It was also indicated that measuring the ICT using DSC was a useful method to classify PEG 6000.     

MassBank: a public repository for sharing mass spectral data for life sciences

MassBank is the first public repository of mass spectra of small chemical compounds for life sciences (<3000 Da). The database contains 605 electron‐ionization mass spectrometry(EI‐MS), 137 fast atom bombardment MS and 9276 electrospray ionization (ESI)‐MSⁿ data of 2337 authentic compounds of metabolites, 11 545 EI‐MS and 834 other‐MS data of 10 286 volatile natural and synthetic compounds, and 3045 ESI‐MS² data of 679 synthetic drugs contributed by 16 research groups (January 2010). ESI‐MS² data were analyzed under nonstandardized, independent experimental conditions. MassBank is a distributed database. Each research group provides data from its own MassBank data servers distributed on the Internet. MassBank users can access either all of the MassBank data or a subset of the data by specifying one or more experimental conditions. In a spectral search to retrieve mass spectra similar to a query mass spectrum, the similarity score is calculated by a weighted cosine correlation in which weighting exponents on peak intensity and the mass‐to‐charge ratio are optimized to the ESI‐MS² data. MassBank also provides a merged spectrum for each compound prepared by merging the analyzed ESI‐MS² data on an identical compound under different collision‐induced dissociation conditions. Data merging has significantly improved the precision of the identification of a chemical compound by 21–23% at a similarity score of 0.6. Thus, MassBank is useful for the identification of chemical compounds and the publication of experimental data. Copyright © 2010 John Wiley & Sons, Ltd.     

Structural and functional properties of designed globins

De novo design of artificial proteins is an essential approach to elucidate the principles of protein architecture and to understand specific functions of natural proteins and also to yield novel molecules for medical and industrial aims. We have designed artificial sequences of 153 amino acids to fit the main-chain framework of the sperm whale myoglobin structure based on the knowledge-based energy functions to evaluate the compatibility between protein tertiary structures and amino acid sequences. The synthesized artificial globins bind a single heme per protein molecule as designed, which show well-defined electrochemical and spectroscopic features characteristic of proteins with a low-spin heme. Redox and ligand binding reactions of the artificial heme proteins were investigated and these heme-related functions were found to vary with their structural uniqueness. Relationships between the structural and functional properties are discussed.     

Vanadium-catalyzed sulfenylation of indoles and 2-naphthols with thiols under molecular oxygen

Vanadium oxyacetylacetonate [VO(acac)(2)] works as a catalyst for the direct synthesis of 3-sulfanylindoles from indoles and thiols under an atmospheric pressure of molecular oxygen as a reoxidant. For example, the reaction of 2-phenylindole with benzenethiol in the presence of a catalytic amount of VO(acac)(2), potassium iodide, and 2,6-di-tert-butyl-p-cresol in chlorobenzene under molecular oxygen proceeds to afford 2-phenyl-3-(phenylsulfanyl)indole in 86% yield. This catalytic system can also be applied to 2-naphthols instead of indoles to give the corresponding 1-sulfanyl-2-naphthols in up to 57% yield.     

Most stable conformation of the cyclopropane ring attached at a carbon atom in a 1,2-dicarba-closo-dodecaborane(12) system

We obtained two crystal structures of electronically interesting dicarba-closo-dodecaborane(12)s (hereafter, "carboranes") substituted with a cyclopropyl group at a caged carbon atom, i.e., C-cyclopropyl-o-carborane (4) and C-cyclopropyl-o-carboranylphenylmethanol (9), at 123 K. In these C-cyclopropyl-o-carboranes, the cyclopropyl group adopted a slightly twisted perpendicular conformation with respect to the electron-deficient carbon-carbon (C-C) bond axis in the o-carborane cage. In contrast, it has previously been shown that a phenyl group substituted at the caged carbon atom, i.e., C-phenyl-o-carborane (3), is almost parallel to this axis at both 150 and 199 K. In other words, the pi system of the phenyl ring adopted an almost bisected conformation in 3. The preferred conformation of the cyclopropane ring in these C-cyclopropyl-o-carboranes was compared among the solid, the solution, and the gaseous states and was retained under the present conditions. Moreover, we found that the C-C bond length in the o-carborane cage not only varied along the rotation of the cyclopropyl group in 4 but also was longer than that in 3, which bears a phenyl group at the dominant conformation. These phenomena may be related to homoconjugations between the caged o-carborane system that serves as an electron acceptor and the homoconjugative substituent that serves as an electron donor. In these C-cyclopropyl-o-carboranes, two types of homoconjugations would result in a slightly twisted perpendicular conformation and 4 would be more strongly stabilized than would the phenyl derivative 3. On the basis of these studies, we propose the existence of a third type of strongly stabilizing interactive geometry for a cyclopropane ring in an o-carborane system.     

B(0)-B(0) mixing in unquenched lattice QCD

We present an unquenched lattice calculation for the B(0)-B(0) transition amplitude. The calculation, carried out at an inverse lattice spacing 1/a=2.22(4) GeV, incorporates two flavors of dynamical quarks described by the O(a)-improved Wilson fermion action and heavy quarks described by nonrelativistic QCD. Particular attention is paid to the uncertainty that arises from the chiral extrapolation, especially the effect of pion loops, for light quarks, which we find could be sizable for the leptonic decay constant, whereas it is small for the B parameters. We obtain f(B(d))=191(10)(+12-22) MeV, f(B(s))/f(B(d))=1.13(3)(+13-2), B(B(d))(m(b))=0.836(27)(+56-62), B(B(s))/B(B(d))=1.017(16)(+56-17), and xi=1.14(3)(+13-2), where the first error is statistical, and the second is systematic, including uncertainties due to chiral extrapolation, finite lattice spacing, heavy quark expansion, and perturbative operator matching.     

Dynamical quark effects on light quark masses

Light quark masses are calculated in lattice QCD with two degenerate flavors of dynamical quarks. The calculations are made with improved actions with lattice spacing a = 0.22-0.11 fm. In the continuum limit we find m(M&Smacr;)(ud)(2 GeV) = 3.44(+0.14)(-0.22) MeV using the pi and rho meson masses as physical input, and m(M&Smacr;)(s)(2 GeV) = 88(+4)(-6) MeV or 90(+5)(-11) MeV with the K or straight phi meson mass as additional input. The quoted errors represent statistical and systematic combined, the latter including those from continuum and chiral extrapolations, and from renormalization factors. Compared to quenched results, two flavors of dynamical quarks reduce quark masses by about 25%.     

Screening of the confinement potential in theSU(2) lattice gauge theory with scalar matter

Using theSU (2) Higgs system with dynamical scalar matter fields as a model for analyzing screening properties of the confining potential in gauge theories, we examine the Wilson loopW (T, R) and the gauge invariant 2-point functionG(T, R) by Monte Carlo simulations on a 16⁴ lattice. For small values of the hopping parameterk these quantities show non-asymptotic area law behavior which changes to asymptotic perimeter law behavior ask increases. Close to the Higgs phase transition we find an indication that both these asymptotic and nonasymptotic terms are present simultaneously within the lattice at different distancesR andT and that the breaking of the confining flux tube by matter pair production occurs within the lattice. Introducing an appropriate ansatz forW(T, R) andG(T, R), respectively, we determine in this complex situation the string tension, the screening energy of the external sources, and the order parameter introduced by Fredenhagen and Marcu.