Magnetic ferroelectrics or multiferroics, which are currently extensively explored, may provide a good arena to realize a novel magnetoelectric function. Here we demonstrate the genuine electric control of the spiral magnetic structure in one of such magnetic ferroelectrics, TbMnO3. A spinpolarized neutron scattering experiment clearly shows that the spin helicity, clockwise or counterclockwise, is controlled by the direction of spontaneous polarization and hence by the polarity of the small cooling electric field.Electric control of magnetic spins or their ordering structure has long been a big challenge in condensed matter physics. Furthermore, manipulating the magnetization by electric field may provide a low energy-consuming way in spin-electronics and a higher data density in information storages [1,2]. There are a number of magnetoelectric materials whose magnetization can be changed, though minutely, with an external electric field, yet only a very few are known whose magnetic structure itself can be controlled by an electric field [1,3,4,5]. The use of ferroelectricity is perhaps indispensable to enhance the electric field action on the magnetic spins. [2] One of the robust mechanisms to produce the ferroelectricicty of magnetic origin has been recently proposed by Katsura, Nagaosa, and Balatsky (KNB) [6]. The overlap of the electronic wave function between the two atomic sites (i and i + 1) with mutually canted spins (S i and S i+1 ) can generate electric polarization,, where e i,i+1 denotes the unit vector connecting the two sites and A is a constant determined by the spin exchange interaction and the spin-orbit interaction. (Note that the similar theoretical results have been obtained independently also in refs. [7,8]). In case the transverse-spiral (cycloidal) spin order is realized ( Fig. 1(b)), the uniform spontaneous polarization is expected to emerge as the sum of the local polarization p i in the direction perpendicular to the spiral propagation vector and the vector chirality,). This spin-driven ferroelectricity has recently been found in several transversespiral magnets such as TbMnO 3 (ref.[9]), Ni 3 V 2 O 8 (ref.[10]), MnWO 4 (ref.[11]), and also in a transverse conespiral magnet CoCr 2 O 4 (ref.[12]). We report here the quantitative elucidation of such magnetically induced ferroelectricity in terms of the spin ellipticity as the order parameter and show the successful electric control between the clockwise (CW) and counter-clockwise (CCW) spin helixes.A family of perovskite manganites, RMnO 3 with R being Tb, Dy, and their solid solution, have recently been demonstrated to undergo a ferroelectric transition at the Curie temperature T C of 20 − 30 K (see the example shown in Fig. 1(c)) [13,14]. Below T N ∼ 40 K, the compounds undergo a long-range spin ordering with the modulation vector Q s = (0, ±q, 1) with q = 1/2 − 1/4 (in P bnm orthorhombic setting) [9,15]. This has been ascribed to the spin frustration effect caused by the combination of GdFeO 3 -type distortion and staggered orbital or...

Atomic and electronic structures of a polar surface of MgO formed on Ag(111) was investigated by using reflection high energy electron diffraction (RHEED), Auger electron spectroscopy, electron energy loss spectroscopy (EELS), and ultraviolet photoemission spectroscopy (UPS). A rather flat unreconstructed polar MgO(111) 1×1 surface could be grown by alternate adsorption of Mg and O2 on Ag(111). The stability of the MgO(111) surface was discussed in terms of interaction between Ag and Mg atoms at the interface, and charge state of the surface atoms. EELS of this surface did not show a band gap region, and finite density of states appeared at the Fermi level in UPS. These results suggest that a polar MgO(111) surface was not an insulating surface but a semiconducting or metallic surface.

High-resolution matrix-assisted laser desorption/ionization imaging mass spectrometry (HR-MALDI-IMS) is an emerging application for the comprehensive and detailed analysis of the spatial distribution of ionized molecules in situ on tissue slides. HR-MALDI-IMS in negative mode in a mass range of m/z 500–1000 was performed on optimal cutting temperature (OCT) compound-embedded human prostate tissue samples obtained from patients with prostate cancer at the time of radical prostatectomy. HR-MALDI-IMS analysis of the 14 samples in the discovery set identified 26 molecules as highly expressed in the prostate. Tandem mass spectrometry (MS/MS) showed that these molecules included 14 phosphatidylinositols (PIs), 3 phosphatidylethanolamines (PEs) and 3 phosphatidic acids (PAs). Among the PIs, the expression of PI(18:0/18:1), PI(18:0/20:3) and PI(18:0/20:2) were significantly higher in cancer tissue than in benign epithelium. A biomarker algorithm for prostate cancer was formulated by analyzing the expression profiles of PIs in cancer tissue and benign epithelium of the discovery set using orthogonal partial least squares discriminant analysis (OPLS-DA). The sensitivity and specificity of this algorithm for prostate cancer diagnosis in the 24 validation set samples were 87.5 and 91.7%, respectively. In conclusion, HR-MALDI-IMS identified several PIs as being more highly expressed in prostate cancer than benign prostate epithelium. These differences in PI expression profiles may serve as a novel diagnostic tool for prostate cancer.

As a result of enormous ring strain, cyclopropene compounds display a range of diverse reactivities in both noncatalytic and transition-metal-catalyzed transformations, thus presenting unique opportunities for organic synthesis. [1,2] To further enhance the synthetic potential of cyclopropenes, the development of expeditious methods for the synthesis of enantioenriched cyclopropenes is highly desirable.[3] In this context, a cyclopropenation reaction of alkynes with diazo compounds that is catalyzed by chiral dirhodium(II) complexes represents one of the most powerful means for the construction of this class of optically active building blocks. Doyle, Müller, and co-workers were the first to demonstrate asymmetric induction (up to ! 98 % ee) in cyclopropenation reactions of terminal alkynes including propargyl alcohol or propargylamine derivatives with diazoacetates using [Rh 2 (5S-mepy) 4 ] (2 a; Scheme 1) as a chiral catalyst.[4] Doyle et al. also reported an enantioselective intramolecular cyclopropenation of diazoacetates, in which [Rh 2 (4S-ibaz) 4 ] (2 b) provided macrocyclic cyclopropenes in up to ! 99 % ee.[5] Corey and coworkers demonstrated that a new mixed carboxylate/carboxamidate catalyst [Rh 2 (OAc)(dpti) 3 ] (3) is highly exceptional for cyclopropenation of a broad range of terminal alkynes with ethyl diazoacetate.[6] The extension of this methodology to include a-substituted a-diazoacetates is particularly attractive because it has the capability to form cyclopropenes with a quaternary stereogenic carbon center. [7][8][9] Although high levels of enantioselectivity (up to 99 % ee) in cyclopropenations of terminal alkynes with aryldiazoacetates [7a] or arylvinyldiazoacetates [7b] under catalysis by [Rh 2 (S-dosp) 4 ] (4) have been reported by Davies and co-workers, the goal for the reaction with a-alkyl-a-diazoesters remains elusive because of the propensity to form a,b-unsaturated esters through a 1,2-hydride shift.[10] Panne and Fox recently disclosed that dirhodium(II) tetrapivalate exhibits high selectivity for cyclopropenation over alkene formation in the reaction of terminal alkynes with a-alkyl-a-diazoesters. [11,12] However, to the best of our knowledge, an enantioselective version of this reaction has not been reported.Our research group has previously demonstrated the first examples of highly enantio-, diastereo-, and chemoselective intramolecular C À H insertion reactions of a-alkyl-a-diazoesters by using dirhodium(II) tetrakis[N-phthaloyl-(S)-tertleucinate] ([Rh 2 (S-pttl) 4 ], 1 a) in which high levels of asymmetric induction (up to 95 % ee) were achieved. [13][14][15] Herein, we report that [Rh 2 (S-tbpttl) 4 ] (1 f), a new dirhodium(II) carboxylate complex that incorporates N-tetrabromophthaloyl-(S)-tert-leucinate as chiral bridging ligands, catalyzes the cyclopropenation reaction of terminal alkynes with 2,4-dimethyl-3-pentyl a-alkyl-a-diazoacetates to give 1,2-disubstituted 2-cyclopropenecarboxylates in good to high yields and with up to 99 % ee. Scheme 1. Chiral dirhodium(II) com...

Stress-activated protein kinase/c-Jun NH 2 -terminal kinase (SAPK/JNK), belonging to the mitogen-activated protein kinase family, plays an important role in stress signaling. SAPK/JNK activation requires the phosphorylation of both Thr and Tyr residues in its Thr-Pro-Tyr motif, and SEK1 and MKK7 have been identified as the dual specificity kinases. In this study, we generated The SAPK/JNK 1 is a member of the family of mitogen-activated protein kinase (MAPK). This MAPK is activated not only by many types of cellular stresses, including changes in osmolarity, heat shock, and UV irradiation, but also by serum, lysophosphatidic acid, and inflammatory cytokines (interleukin-1␤ and tumor necrosis factor-␣). The activated SAPK/JNK phosphorylates transcription factors c-Jun, Jun D, and activating transcription factor-2 to regulate gene expression for the stress response. Activation of SAPK/JNK requires the phosphorylation of Tyr and Thr residues located in a Thr-Pro-Tyr motif in the activation loop between VII and VIII of the kinase domain. The phosphorylation is catalyzed by the dual specificity kinases SEK1 (also known as MKK4) and MKK7 (SEK2), which are capable of catalyzing the phosphorylation of both Thr and Tyr residues in vitro (1, 2).Targeted gene-disruption experiments in mice demonstrate that both SEK1 and MKK7 are required for embryonic development. Sek1 Ϫ/Ϫ embryos die between embryonic day 10.5 (E10.5) and E12.5 with impaired liver formation (3-5). Furthermore, we have recently reported that SEK1 is crucial for hepatocyte growth factor-induced activation of SAPK/JNK in developing hepatoblasts of mouse embryos. On the other hand, mkk7 Ϫ/Ϫ embryos die between E11.5 and E12.5 with similar impairment of liver formation and SAPK/JNK activation (6). These results clearly show that both SEK1 and MKK7 play indispensable roles in hepatoblast proliferation during mouse embryogenesis. Distinct biochemical properties between SEK1 and MKK7 may be critical for the indispensable roles of the two activators of SAPK/JNK in vivo.In this regard, several in vitro experiments have shown that SAPK/JNK is activated synergistically by SEK1 and MKK7 (7-9). The synergistic activation may be related to the enzymatic properties of the two MAPKKs: SEK1 prefers the Tyr residue and MKK7 prefers the Thr residue of the MAPK. We have also reported that the synergistic activation of SAPK/JNK in response to stress signals is attenuated with a decreased level of its Tyr phosphorylation in sek1 Ϫ/Ϫ mouse ES cells that retain MKK7 at the same level as the wild-type cells (10).