Hydration effect on the ion-pair extraction of lithium picrate by hydrophobic benzo-15-crown-5 ether into various less-polar diluents.

The ion-pair formation constant (K(MLA)(0) in mol(-1) dm(3)) for Li(B15C5)(+) with a picrate ion (Pic(-)) in water was determined by potentiometry with a K(+)-selective electrode at 25 degrees C and an ionic strength of 0, where B15C5 denotes benzo-15-crown-5 ether. Using the concentration equilibrium constants, K(MLA), estimated from this value, the extraction constants (mol(-2) dm(6) unit) of about ten diluents were re-calculated from previously reported extraction data. Also, the distribution constants of an ion-pair complex, Li(B15C5)Pic, between water and the diluents were re-estimated. A disagreement in the determined K(MLA) value between a solvent-extraction method and potentiometry was explained in terms of the Scatchard-Hildebrand equation; it came from the fact that the hydration of Li(I) in Li(B15C5)Pic was larger than that of free B15C5 in water. Then, the previously determined value by the former method was re-estimated using the potentiometric K(MLA) value.     

LMC complexity for the ground states of different quantum systems

Lower bound for the shape complexity measure of López-Ruiz-Mancini-Calbet (LMC), CLMC is studied. Analytical relations for simple examples of the harmonic oscillator, the hydrogen atom and two-electron ‘entangled artificial’ atom proposed by Moshinsky are derived. Several numerical examples of the spherically confined model systems are presented as the test cases. For the homogeneous potential, CLMC is found to be independent of the parameters in the potential which is not the case for the non-homogeneous potentials.     

Perfluorocyclobutyl-based methacrylate monomers: Synthesis and radical polymerization

A new class of methacrylate monomers containing perfluorocyclobutyl unit was synthesized in multi-steps including crossing-dimerization, demethylation and esterification using commercially available p-substituted phenol, tetrafluoroethylene and methacryloyl chloride as starting materials. These monomers can be polymerized in solution to provide perfluorocyclobutyl-based polymethacrylate, a kind of potential transparent material.     

A starlike amphiphilic graft copolymer with hydrophilic poly(acrylic acid) backbones and hydrophobic polystyrene side chains

A well‐defined starlike amphiphilic graft copolymer bearing hydrophilic poly(acrylic acid) backbones and hydrophobic polystyrene side chains was synthesized by successive atom transfer radical polymerization followed by the hydrolysis of poly‐(methoxymethyl acrylate) backbone. A grafting‐from strategy was employed for the synthesis of a graft copolymer with narrow molecular weight distribution. Hydrophobic polystyrene side chains were connected to the backbones through stable C? C bonds. The poly(methoxymethyl acrylate) backbones can be easily hydrolyzed with HCl without affecting the hydrophobic polystyrene side chains. This kind of amphiphilic graft copolymer can form stable sphere micelles in water. The sizes of the micelles were dependent on the ionic strength and pH value. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3687–3697, 2007     

Active compensation of rf-pulse transients

A new approach to compensate rf-pulse transients is proposed. Based on the idea of the response theory of a linear system, a formula is derived to obtain the required excitation voltage profile back from the intended target rf-pulse shape. The validity of the formula is experimentally confirmed by monitoring the rf-field created inside the sample coil with a pickup coil. Since this approach realizes accurate rf-pulse shapes without reducing the Q-factor of the tank circuit of the probe, it can be used not only to suppress the transient tail of the rf-pulse, but also as a general concept for accurate rf-pulsing.     

A simple and linear time randomized algorithm for computing sparse spanners in weighted graphs

Let G = (V,E) be an undirected weighted graph on |V | = n vertices and |E| = m edges. A t‐spanner of the graph G, for any t ≥ 1, is a subgraph (V,E_S), E_S ⊆ E, such that the distance between any pair of vertices in the subgraph is at most t times the distance between them in the graph G. Computing a t‐spanner of minimum size (number of edges) has been a widely studied and well‐motivated problem in computer science. In this paper we present the first linear time randomized algorithm that computes a t‐spanner of a given weighted graph. Moreover, the size of the t‐spanner computed essentially matches the worst case lower bound implied by a 43‐year old girth lower bound conjecture made independently by Erdős, Bollobás, and Bondy & Simonovits. Our algorithm uses a novel clustering approach that avoids any distance computation altogether. This feature is somewhat surprising since all the previously existing algorithms employ computation of some sort of local or global distance information, which involves growing either breadth first search trees up to θ(t)‐levels or full shortest path trees on a large fraction of vertices. The truly local approach of our algorithm also leads to equally simple and efficient algorithms for computing spanners in other important computational environments like distributed, parallel, and external memory. © 2006 Wiley Periodicals, Inc. Random Struct. Alg., 2007     

Branching Brownian Motions on Riemannian Manifolds: Expectation of the Number of Branches Hitting Closed Sets

For a branching Brownian motion on Riemannian manifold, we give an analytic criterion for the expectation of the number of branches hitting a closed set being finite. The author was supported in part by Grant-in-Aid for Scientific Research (No.18340033 (B)), Japan Society for the Promotion of Science.     

LR-normal orthogroups

A new kind of regular orthogroups, namely, the LR-normal orthogroups is introduced and investigated. In particular, we will introduce the gearing techniques for fitting semigroup components on a semilattice in the construction of LR-normal orthogroups.     

Conical support for double-stage diamond anvil apparatus

ABSTRACT

Both micro-paired and conical support type double-stage diamond anvil cells (ds-DAC) were tested using a newly synthesized ultra-fine nano-polycrystalline diamond (NPD). Well-focused X-ray sub-micron beam and the conically supported 2nd stage anvils (micro-anvils) with 10?μm culet enable us to obtain good quality X-ray diffraction peaks from the sample at around 400?GPa. The relationship between confining pressure and sample pressure depends heavily on the initial height (thickness) of micro-anvils, the difference of a few micrometers leads to a quite different compression path. The conical support type is a solution to retain both enough thickness and strength of micro-anvils at higher confining pressure conditions. All conical support ds-DAC experiments terminated by the failure of the 1st stage anvil instead of 2nd one. The combination of ultra-fine NPD 2nd stage anvil and NPD 1st stage anvil opens a new frontier for measurement of the X-ray absorption spectrum above 300?GPa.