192 research outputs found
Exploiting Cation Structure and Water Content in Modulating the Acidity of Ammonium Hydrogen Sulfate Protic Ionic Liquids
In this paper, we investigated the effect of cation structure and water content on proton dissociation in alkylammonium [HSOâ]â» protic ionic liquids (ILs) doped with 20 wt % water and correlated this with experimental Hammett acidities. For pure systems, increased cation substitution resulted in a reduction in the number of direct anionâanion neighbors leading to larger numbers of small aggregates, which is further enhanced with addition of water. We also observed spontaneous proton dissociation from [HSOâ]â» to water only for primary amine-based protic ILs, preceded by the formation of an anion trimer motif. Investigation using DFT calculations revealed spontaneous proton dissociation from [HSOâ]â» to water can occur for each of the protic ILs investigated; however, this is dependent on the size of the anion aggregates. These findings are important in the fields of catalysis and lignocellulosic biomass, where solvent acidity is a crucial parameter in biomass fractionation and lignin chemistry
RNAi: uma estratĂ©gia a ser explorada para a indução de resistĂȘncia a viroses em tomateiro.
bitstream/item/152688/1/edicao20-inoueNagata.pd
Field-Induced gap due to four-spin exchange in a spin ladder
The effect of the four-spin cyclic exchange interaction at each plaquette in
the two-leg spin ladder is investigated at T=0, especially focusing on
the field-induced gap. The strong rung coupling approximation suggests that it
yields a plateau at half of the saturation moment () in the
magnetization curve, which corresponds to a field-induced spin gap with a
spontaneous breaking of the translational symmetry. A precise phase diagram at
is also presented based on the level spectroscopy analysis of the
numerical data obtained by Lanczos method. The boundary between the gapless and
plateau phases is confirmed to be of the Kosterlitz-Thouless (KT) universality
class.Comment: 10 pages, 3 eps figures (embedded), to be published in J. Phys.:
Cond. Matte
Accuracy of a remote quantitative image analysis in the whole slide images
The rationale for choosing a remote quantitative method supporting a diagnostic decision requires some empirical studies and knowledge on scenarios including valid telepathology standards. The tumours of the central nervous system [CNS] are graded on the base of the morphological features and the Ki-67 labelling Index [Ki-67 LI]. Various methods have been applied for Ki-67 LI estimation. Recently we have introduced the Computerized Analysis of Medical Images [CAMI] software for an automated Ki-67 LI counting in the digital images
Clinical and radiological features related to the growth potential of meningioma
Clinical and radiological features that help predict the growth potential of meningioma would be beneficial. The purpose of this study is to clarify the characteristics related to proliferating potential using the MIB-1 staining index. We analyzed the relationship of MIB-1 staining indices to characteristics of 342 consecutive patients with meningioma surgically removed between 1995 and 2004 by logistic regression analysis. One hundred and forty-nine of the patients with meningioma were â„60 in age; 89 male; 48 recurrent; 203 symptomatic; 157 at the skull base; 124 over 20 cm(3); 24 multiple; 136 with edema; 117 with calcification. The MIB-1 staining index in 56 of 296 grade I meningiomas in WHO classification was â„ 3.0; in 27 of 28 grade II; and in 17 of 18 grade III, respectively. Logistic regression analysis demonstrated that male (odds ratio [OR], 2.374, p=0.003), recurrence (OR, 7.574, p=0.0001), skull base (OR, 0.540, p=0.035), calcification (OR, 0.498, p=0.019) were independent risk factors for a high MIB-1 staining index (â„3.0); age, symptomatic, volume, multiple, edema were not. Male, recurrence, non-skull base, absence of calcification are independent risk factors for a high proliferative potential. These should be taken into consideration when managing meningiomas
Magnetic Phase Diagram of Spin-1/2 Two-Leg Ladder with Four-Spin Ring Exchange
We study the spin-1/2 two-leg Heisenberg ladder with four-spin ring exchanges
under a magnetic field. We introduce an exact duality transformation which is
an extension of the spin-chirality duality developed previously and yields a
new self-dual surface in the parameter space. We then determine the magnetic
phase diagram using the numerical approaches of the density-matrix
renormalization-group and exact diagonalization methods. We demonstrate the
appearance of a magnetization plateau and the Tomonaga-Luttinger liquid with
dominant vector-chirality quasi-long-range order for a wide parameter regime of
strong ring exchange. A "nematic" phase, in which magnons form bound pairs and
the magnon-pairing correlation functions dominate, is also identified.Comment: 18pages, 7 figure
Magnetic properties of the distorted diamond chain at T=0
We explore, at T=0, the magnetic properties of the antiferromagnetic
distorted diamond chain described by the Hamiltonian {\cal H}
= \sum_{j=1}^{N/3}{J_1 ({\bi S}_{3j-1} \cdot {\bi S}_{3j}
+ {\bi S}_{3j} \cdot {\bi S}_{3j+1})
+ J_2 {\bi S}_{3j+1} \cdot {\bi S}_{3j+2}
+ J_3 ({\bi S}_{3j-2} \cdot {\bi S}_{3j}
+ {\bi S}_{3j} \cdot {\bi S}_{3j+2})}
\allowbreak - H \sum_{l=1}^{N} S_l^z with , which well
models with , and azurite . We employ the physical
consideration, the degenerate perturbation theory, the level spectroscopy
analysis of the numerical diagonalization data obtained by the Lanczos method
and also the density matrix renormalization group (DMRG) method. We investigate
the mechanisms of the magnetization plateaux at and , and
also show the precise phase diagrams on the plane
concerning with these magnetization plateaux, where
and is the saturation magnetization. We also calculate the magnetization
curves and the magnetization phase diagrams by means of the DMRG method.Comment: 21 pages, 29 figure
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