We have performed high-field magnetization and ESR measurements on Ba3CoSb2O9 single crystals, which approximates the two-dimensional (2D) S = 1/2 triangular-lattice Heisenberg antiferromagnet. For an applied magnetic field H parallel to the ab-plane, the entire magnetization curve including the plateau at one-third of the saturation magnetization (Ms) is in excellent agreement with the results of theoretical calculations except a small step anomaly near (3/5)Ms, indicative of a theoretically undiscovered quantum phase transition. However, for H c, the magnetization curve exhibits a cusp near Ms/3 owing to the weak easy-plane anisotropy and the 2D quantum fluctuation. From a detailed analysis of the collective ESR modes observed in the ordered state, combined with the magnetization process, we have determined all the magnetic parameters including the interlayer and anisotropic exchange interactions.PACS numbers: 75.10. Jm, 75.45.+j, 75.60.Ej, Over the past decades, there has been considerable interest in frustrated quantum magnets, owing to a rich variety of exotic quantum phenomena [1][2][3]. For classical spins with an antiferromagnetic coupling, a geometric frustration suppresses the long-range ordering, leading to a degenerate ground state. The degeneracy can be destroyed by quantum fluctuations, which emerge not only through an interplay of strong geometric frustration, low dimensionality, and small spin, but also through the application of a magnetic field. Despite intensive research efforts, the detailed mechanism of the quantum effects, e.g., the ground state property [4,5], has still been highly controversial.One macroscopic manifestation of the quantum phenomena is the stabilization of the "up-up-down" spin structure under a magnetic field, predicted for a twodimensional (2D) triangular-lattice Heisenberg antiferromagnet (TLHAF) with a small spin [6,7]. In a magnetization process, the nonclassical anomaly appears as a plateau in a finite field range at one-third of the saturation magnetization M s , hereafter referred to as the M s /3 plateau. In a classical picture, a monotonic increase in the magnetization is expected up to M s . A number of theoretical approaches for explaining the quantum mechanism of the M s /3 plateau have been proposed [8][9][10][11][12][13][14]. Thus far, however, few numbers of definite experimental results reserved judgment on the issue. This is mainly due to the experimental difficulty in growing the model material, let alone in observing the M s /3 plateau purely driven by quantum fluctuations. In fact, most of the TLHAFs ever studied, such as Cs 2 CuBr 4 , [15,16] have a distorted triangular lattice, which induces an antisymmetric Dzyaloshinsky-Moriya (DM) interaction.It is believed that the spin state in the lower-field range above the higher edge field of the M s /3 plateau is the 2 : 1 canted coplanar state that is a continuous variant of the up-up-down state [7][8][9][10][11]. However, whether the 2 : 1 canted coplanar state is stable up to the saturation or a new quan...

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A versatile approach for the preparation of micrometer-sized, monodisperse, "mushroom-like" Janus polymer particles in aqueous dispersed systems is proposed. The synthetic methodology of the Janus particles consists of the following two steps. The first step is the preparation of spherical poly(methyl methacrylate) (PMMA)/poly(styrene-2-(2-bromoisobutyryloxy)ethyl methacrylate) (P(S-BIEM)) Janus particles based on the internal phase separation induced by solvent evaporation from the solvent droplets dissolving the polymers. The second step is surface-initiated atom transfer radical polymerization (ATRP) of 2-(dimethylamino)ethyl methacrylate (DM) using the Janus particles with ATRP initiator groups at one side of the surface as macroinitiator. As a consequence, mushroom-like PMMA/P(S-BIEM)-graft-poly(DM) Janus particles were prepared, which had pH-responsive property.

"Mushroom-like" Janus poly(methyl methacrylate) (PMMA)/poly(styrene-2-(2-bromoisobutyryloxy)ethyl methacrylate)-graft-poly(2-(dimethylamino)ethyl methacrylate) (PDM) particles synthesized in our previous report were applied as particulate surfactants. The PDM moiety at the one side of the Janus particles reversibly exhibited the volume phase transition in response to pH and temperature in an aqueous medium; that is, the surface property of the Janus particles comprising both PDM and PMMA reversibly changed between amphiphilic and hydrophobic based on the nature of PDM. Consequently, 1-octanol-in-water emulsion droplets stabilized by the amphiphilic Janus particles coalesced in the alkaline region and at 60 degrees C around neutral pH because of desorption of the hydrophobized Janus particles from the interface to the oil phase.

Purpose: The peptides derived from ideal cancer-testis antigens, including LY6K, CDCA1, and IMP3 (identified using genome-wide cDNA microarray analyses), were used in immunotherapy for head and neck squamous cell cancer (HNSCC). In this trial, we analyzed the immune response to and safety and efficacy of vaccine therapy.Experimental Design: A total of 37 patients with advanced HNSCC were enrolled in this trial of peptide vaccine therapy, and the OS, PFS, and immunologic response were evaluated using enzyme-linked ImmunoSpot (ELISPOT) and pentamer assays. The peptides were subcutaneously administered weekly with IFA. The primary endpoints were evaluated on the basis of differences between HLA-A Ã 2402-positive [A24(þ)] patients treated with peptide vaccine therapy and -negative [A24(À)] patients treated without peptide vaccine therapy among those with advanced HNSCC.Results: Our cancer vaccine therapy was well tolerated. The OS of the A24(þ) vaccinated group (n ¼ 37) was statistically significantly longer than that of the A24(À) group (n ¼ 18) and median survival time (MST) was 4.9 versus 3.5 months, respectively; P < 0.05. One of the patients exhibited a complete response. In the A24(þ) vaccinated group, the ELISPOT assay identified LY6K-, CDCA1-, and IMP3-specific CTL responses in 85.7%, 64.3%, and 42.9% of the patients, respectively. The patients showing LY6K-and CDCA1-specific CTL responses demonstrated a longer OS than those without CTL induction. Moreover, the patients exhibiting CTL induction for multiple peptides demonstrated better clinical responses.Conclusions: The immune response induced by this vaccine may improve the prognosis of patients with advanced HNSCC.