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Beckett MA Horton PN Hursthouse MB Timmis JL Varma KS 《Dalton transactions (Cambridge, England : 2003)》2012,41(15):4396-4403
The synthesis and characterization of a series of cyclo-alkylammonium pentaborate salts {[cyclo-C(n)H(2n-1)NR(3)][B(5)O(6)(OH)(4)] (R = H, n = 3, 5-7 (1-4); R = Me, n = 6 (5))} are reported. Compounds 1, 2 and 5 have been further characterized by single-crystal XRD studies. Attempted recrystallization of 3 and 4 yielded small crops of the unexpected heptaborate salts, [cyclo-C(6)H(11)NH(3)](2)[B(7)O(9)(OH)(5)]·3H(2)O·B(OH)(3) (6) and [cyclo-C(7)H(13)NH(3)](2)[B(7)O(9)(OH)(5)]·2H(2)O·2B(OH)(3) (7) which were also characterized crystallographically. All compounds show extensive supramolecular H-bonded anionic lattices templated by the cations. H-bond interactions are described in detail. TGA-DSC analysis of the pentaborates 1-5 showed that they thermally decomposed in air at 800 °C to 2.5B(2)O(3), in a 2 step process involving dehydration (<250 °C) and oxidative decomposition (250-600 °C). BET analysis of materials derived from the pentaborates had internal porosities of <1 m(2) g(-1). 相似文献
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An Artificial Immune System for Clustering Amino Acids in the Context of Protein Function Classification 总被引:1,自引:0,他引:1
A. Secker M. N. Davies A. A. Freitas J. Timmis E. Clark D. R. Flower 《Journal of Mathematical Modelling and Algorithms》2009,8(2):103-123
This paper addresses the classification task of data mining (a form of supervised learning) in the context of an important
bioinformatics problem, namely the prediction of protein functions. This problem is cast as a hierarchical classification
problem. The protein functions to be predicted correspond to classes that are arranged in a hierarchical structure (this takes
the form of a class tree). The main contribution of this paper is to propose a new Artificial Immune System that creates a
new representation for proteins, in order to maximize the predictive accuracy of a hierarchical classification algorithm applied
to the corresponding protein function prediction problem.
相似文献
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Given a regular –-hermitian form on an n-dimensional vector space V over a commutative field K of characteristic 2 (
). Call an element of the unitary group a quasi-involution if is a product of commuting quasi-symmetries (a quasi-symmetry is a unitary transformation with a regular (n–1)-dimensional fixed space). In the special case of an orthogonal group every quasi-involution is an involution. Result: every unitary element is a product of five quasi-involutions. If K is algebraically closed then three quasi-involutions suffice. 相似文献
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Joanne H Gibson Barry Slobedman Harikrishnan KN Sarah L Williamson Dimitri Minchenko Assam El-Osta Joshua L Stern John Christodoulou 《BMC neuroscience》2010,11(1):53
Background
The Rett Syndrome (RTT) brain displays regional histopathology and volumetric reduction, with frontal cortex showing such abnormalities, whereas the occipital cortex is relatively less affected. 相似文献5.
Ferrer M Golyshina OV Chernikova TN Khachane AN Martins Dos Santos VA Yakimov MM Timmis KN Golyshin PN 《Chemistry & biology》2005,12(8):895-904
We created a metagenome expression library from the brine:seawater interface of the Urania hypersaline basin, screened it for esterases, and characterized five of these. Two had no significant sequence homology to known esterases, hydrolyzed both carboxylesters and thioesters, and exhibited unusual, habitat-specific characteristics (preference for high hydrostatic pressure and salinity). One has an unusual structural signature incorporating three catalytic active centers mediating distinct hydrolytic activities and an adaptive tertiary-quaternary structure that alters between three molecular states, according to the prevailing physicochemical conditions. Some of the esterases have high activities, specificities, enantioselectivities, and exceptional stability in polar solvents, and they are therefore potentially useful for industrial biotransformations. One possesses the highest enantioselectivity toward an ester of the important chiral synthon solketal (E: 126[S]; 98%ee). 相似文献
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Beckett MA Rugen-Hankey MP Timmis JL Varma KS 《Dalton transactions (Cambridge, England : 2003)》2008,(11):1503-1506
The reaction of metal alkoxides M(OR)4 (M = Ti, Zr; R = organyl) with (MeO)3B3O3 (1 : 0.67) in dry propan-2-one at room temperature led to gels which when dried and calcined in air for 24 h at 500-1000 degrees C afforded bi-phased mixed-oxide materials formulated as 4TiO2 x 3B2O3 and ZrO2 x B2O3 in high ceramic yields and purity; the B2O3 phases of these materials were amorphous. The materials remained amorphous upon calcination at lower temperatures. The TiO2 phase of the 4TiO2 x 3B2O3 was crystalline when calcined at higher temperatures with either anatase (600 degrees C) or rutile (>800 degrees C) being obtained. The ZrO2 phase of the ZrO2 x B2O3 was crystalline when calcined at higher temperatures and was obtained as a metastable tetragonal phase (<700 degrees C) or baddeleylite (>800 degrees C). In a similar reaction, Al(O(i)Pr)3 (2 : 1) gave a bi-phased aluminium borate-boron oxide (Al18B4O(33).7B2O3) after calcination at >700 degrees C. The dried gels and oxide materials were all characterized by elemental analysis, TGA-DSC, and powder XRD. 相似文献
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