If a three-dimensional physical electronic system emulating synapse networks could be built, that would be a significant step toward neuromorphic computing. However, the fabrication complexity of complementary metal-oxide-semiconductor architectures impedes the achievement of three-dimensional interconnectivity, high-device density, or flexibility. Here we report flexible three-dimensional artificial chemical synapse networks, in which two-terminal memristive devices, namely, electronic synapses (e-synapses), are connected by vertically stacking crossbar electrodes. The e-synapses resemble the key features of biological synapses: unilateral connection, long-term potentiation/depression, a spike-timing-dependent plasticity learning rule, paired-pulse facilitation, and ultralow-power consumption. The three-dimensional artificial synapse networks enable a direct emulation of correlated learning and trainable memory capability with strong tolerances to input faults and variations, which shows the feasibility of using them in futuristic electronic devices and can provide a physical platform for the realization of smart memories and machine learning and for operation of the complex algorithms involving hierarchical neural networks.

Sr 2 IrO 4 was predicted to be a high-temperature superconductor upon electron doping since it highly resembles the cuprates in crystal structure, electronic structure, and magnetic coupling constants. Here, we report a scanning tunneling microscopy/spectroscopy (STM/STS) study of Sr 2 IrO 4 with surface electron doping by depositing potassium (K) atoms. We find that as the electron doping increases, the system gradually evolves from an insulating state to a normal metallic state, via a pseudogaplike phase, and a phase with a sharp, V-shaped low-energy gap with about 95% loss of density of state (DOS) at E F . At certain K coverage (0.5-0.6 monolayer), the magnitude of the low-energy gap is 25-30 meV, and it closes at around 50 K. Our observations show that the electron-doped Sr 2 IrO 4 remarkably resembles hole-doped cuprate superconductors.

Humans express three distinct collagenases, MMP-1, MMP-8, and MMP-13, that initiate degradation of fibrillar type I collagen. We have previously reported that ultraviolet irradiation causes increased expression of MMP-1, but not MMP-13, in keratinocytes and fibroblasts in human skin in vivo. We report here that ultraviolet irradiation increases expression of MMP-8 in human skin in vivo. Western analysis revealed that levels of the full-length, 85 kDa proenzyme form of MMP-8 increased significantly within 8 h post ultraviolet irradiation (2 minimal erythema doses). Increased full-length MMP-8 protein was associated with infiltration into the skin of neutrophils, which are the major cell type that expresses MMP-8. Immunofluorescence revealed coexpression of MMP-8 and neutrophil elastase, a marker for neutrophils. Immunohistology demonstrated MMP-8 expression in neutrophils in the papillary dermis between 4 and 8 h post ultraviolet irradiation, and in the epidermis at 24 h post radiation. MMP-8 mRNA expression was not detected in nonirradiated or ultraviolet-irradiated human skin, indicating that increased MMP-8 following ultraviolet irradiation resulted from preexisting MMP-8 protein in infiltrating neutrophils. Pretreatment of skin with the glucocorticoid clobetasol, but not all-trans retinoic acid, significantly blocked ultraviolet-induced increases in MMP-8 protein levels, and neutrophil infiltration. In contrast, all-trans retinoic acid and clobetasol were equally effective in blocking ultraviolet induction of MMP-1 and degradation of collagen in human skin in vivo. Taken together, these data demonstrate that ultraviolet irradiation increases MMP-8 protein, which exists predominantly in a latent form within neutrophils, in human skin in vivo. Although ultraviolet irradiation induces both MMP-1 and MMP-8, ultraviolet-induced collagen degradation is initiated primarily by MMP-1, with little, if any, contribution by MMP-8.

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Recently, the interest in natural products for the treatment of cancer is increasing because they are the pre-screened candidates. In the present study, we demonstrate the therapeutic effect of celastrol, a triterpene extracted from the root bark of Chinese medicine on gastric cancer. The proliferation of AGS and YCC-2 cells were most sensitively decreased in six kinds of gastric cancer cell lines after the treatment with celastrol. Celastrol inhibited the cell migration and increased G1 arrest in cell-cycle populations in both cell lines. The treatment with celastrol significantly induced autophagy and apoptosis and increased the expression of autophagy and apoptosis-related proteins. We also found an increase in phosphorylated AMPK following a decrease in all phosphorylated forms of AKT, mTOR and S6K after the treatment with celastrol. Moreover, gastric tumor burdens were reduced in a dose-dependent manner by celastrol administration in a xenografted mice model. Taken together, celastrol distinctly inhibits the gastric cancer cell proliferation and induces autophagy and apoptosis. [BMB Reports 2014; 47(12): 697-702]

Angiogenesis takes place during embryogenesis, characterized by the formation of new blood vessels from pre-existing ones. This biological process is also found in the female reproductive system, wound healing, and cancer development. Apoptosis, programmed cell death, is a physiological process in development, tissue homeostasis, and disease. Apoptosis is a normal event in several reproductive tissues including human placenta. In these studies, we investigated whether aberrant angiogenesis and apoptosis are associated with recurrent pregnancy loss (RPL). We compared the gene expression level for angiogenesis- and apoptosis-related genes in chorionic villi from RPL patients and those from normal controls. Semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis revealed that 7 angiogenesis- and 12 apoptosis-related genes were abnormally expressed in chorionic villi from RPL patients. Angiogenesis-related genes that showed aberrant expression level are matrix metalloproteinase-2 (MMP-2), plasminogen activator inhibitor (PAI), integrin, transforming growth factor-beta (TGF-beta), vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and leptin receptor. Expression levels for these genes, except for leptin receptor, showed less in chorionic villi from RPL patients than those from normal controls. In contrast, higher expression levels of 12 apoptosis-related genes (caspase 3, 6, 7, 8, 9, 10, 12, BAD, BAX, BID, Fas, and FasL) were shown in chorionic villi from RPL patients than those from normal controls. Taken all together, it is likely that the lower expression of angiogenesis-related genes and the excessive expression of apoptosis-related genes are associated with RPL.

We have first grown single crystals of multiferroic double-perovskite Lu 2 CoMnO 6 and studied the directional dependence of their magnetic and dielectric properties. The ferromagnetic order emerges below T C ≈48 K along the crystallographic c axis. Dielectric anomaly arises along the b axis with no electric polarization at T C , contrary to the polycrystalline work suggesting ferroelectricity along the c axis. It is proposed that the incommensurate centric spin modulation leads to the antiferroelectric order with the large dielectric anomaly. Through the strongly coupled ferromagnetic and dielectric states, the highly non-linear variation of both dielectric constant and magnetization was achieved in application of magnetic fields. This concurrent tunability provides a new route to manipulation of multiple order parameters in multiferroics. a) phylove@yonsei.ac.kr Realization of strong magnetoelectric coupling in multiferroics where ferroelectricity and magnetism coexist, opens new opportunities for novel device applications such as magnetoelectric data storage and sensors utilizing cross-coupling effects between electric and magnetic order parameters. [1][2][3][4] The current research on multiferroics is mainly focused on magnetism-driven ferroelectrics in which the ferroelectricity originates from the lattice relaxation via exchange strictions in the ordered magnetic state. Both symmetric and antisymmetric parts of the magnetic exchange coupling can contribute to the ferroelectric distortions. Symmetric exchange interaction is active for multiferroics such as Ca 3 CoMnO 6 and GdFeO 3 5,6 while multiferroicity in spiral magnets of TbMnO 3 and CuBr 2 7,8 results primarily from antisymmetric exchange interaction. In principle, the substantial coupling between structural distortions and magnetic order can lead to a large variation of the dielectric properties under the application of magnetic fields. However, only few of single phase multiferroics possess the net magnetization, which is advantageous for achieving the mutual control of multiple order parameters. 9,10 In spite of enormous efforts made on multiferroics research, it is still anticipated to design and discover new systems accompanying enhanced cross-coupled functionalities for practical applications. Various systems have been suggested as a candidate belonging to a new class of multiferroics, however, many of them studied so far have been synthesized only in the polycrystalline form, preventing characterization of their intrinsic properties. [11][12][13][14] Lu 2 CoMnO 6 (LCMO) crystallizes in a monoclinic P2 1 /n double-perovskite structure with a unit cell of a=0.516 nm, b=0.554 nm, and c=0.742 nm. Co 2+ and Mn 4+ ions are alternatingly located in corner-shared octahedral environments as shown in Figs. 1(a) and (b). It has drawn an interest due to its newly-found multiferroicity in the previous polycrystalline work. 15 The polycrystalline specimen exhibits a broad temperature dependence of dielectric anomaly below ~50 K. It has been predicted that ...