IGBT chip current imaging system by scanning local magnetic field

An IGBT / power diode current distribution imaging system was demonstrated. This system can capture current redistribution or oscillation inside or among chips on a DBC-level sub-module. It can perform failure analysis of power semiconductors by detecting problems such as nonuniform current distribution between bonding wires. The system scans the chip’s shape using a laser sensor and then records the local magnetic field near the bonding wire using a 4-axis robot coil sensor. The coil sensor has two pair of Cu patterned spiral coils symmetrically arranged on both sides of a 60-μm-thick polyimide film. The system enables the analysis of destructive current concentrations of the entire chip, among chips or a part of the chip under high current or high voltage switching conditions, without making any changes or disassembling the chip connections.24th European Symposium on Reliability of Electron Devices, Failure Physics and Analysis. Schedule, September 30-October 4, 2013, Venue, Arcachon, Franc

Giant magnetoelectric effect in an L 2₁-ordered Co₂FeSi/Pb(Mg₁/₃Nb₂/₃)O₃-PbTiO₃ multiferroic heterostructure

We experimentally show a giant magnetoelectric (ME) effect at room temperature in an interfacial multiferroic heterostructure consisting of L2₁-ordered Co₂FeSi and Pb(Mg₁/₃Nb₂/₃)O₃-PbTiO₃ (PMN-PT). Molecular beam epitaxy growth at 400 °C enables us to obtain epitaxial and L2₁-ordered Co₂FeSi films on PMN-PT(001). For the epitaxial Co₂FeSi/PMN-PT heterostructure, the remanent magnetization state can be largely modulated by varying electric fields. We note that the room-temperature ME coupling coefficient (α) is estimated to be 6.0-6.3 × 10 - ⁶ s/m, comparable to the highest α value reported previously. Nonvolatile and repeatable magnetization changes in remanent states are also demonstrated. These results will pave the way for room-temperature electric-field control of the magnetization of half-metallic Heusler alloys in high-performance spintronic devices.T. Usami, S. Fujii, S. Yamada, Y. Shiratsuchi, R. Nakatani, and K. Hamaya, Appl. Phys. Lett. 118, 142402 (2021); https://doi.org/10.1063/5.004409

Effect of Fe atomic layers at the ferromagnet-semiconductor interface on temperature-dependent spin transport in semiconductors

Using artificially controlled ferromagnet (FM)-semiconductor (SC) interfaces, we study the decay of the nonlocal spin signals with increasing temperature in SC-based lateral spin-valve devices. When more than five atomic layers of Fe are inserted at the FM/SC interfaces, the temperature-dependent spin injection/detection efficiency (P inj /det) can be interpreted in terms of the T3/2 law, meaning a model of the thermally excited spin waves in the FM electrodes. For the FM/SC interfaces with the insufficient insertion of Fe atomic layers, on the other hand, the decay of P inj /det is more rapid than the T3/2 curve. Using magneto-optical Kerr effect measurements, we find that more than five atomic layers of Fe inserted between FM and SC enable us to enhance the ferromagnetic nature of the FM/SC heterointerfaces. Thus, the ferromagnetism in the ultra-thin FM layer just on top of SC is strongly related to the temperature-dependent nonlocal spin transport in SC-based lateral spin-valve devices. We propose that the sufficient ferromagnetism near the FM/SC interface is essential for high-performance FM-SC hybrid devices above room temperature.M. Yamada, Y. Shiratsuchi, H. Kambe, K. Kudo, S. Yamada, K. Sawano, R. Nakatani, and K. Hamaya, Journal of Applied Physics 129, 183901 (2021); https://doi.org/10.1063/5.0048321

Adubação e arranjo de plantas no consórcio milho e braquiária.

A otimização do manejo de milho consorciado com braquiária depende da fertilidade do solo, da densidade de plantas de braquiária e do arranjo de plantas do milho. Avaliaram-se as interações desses fatores e sua influência na produtividade de grãos e da pastagem, em experimento conduzido por duas safras, num fatorial 2x2x3+1, combinando-se duas condições de adubação do milho (para produtividade de 6 ou > 10 t ha-1 de grãos), densidade média ou alta de braquiária ( 30 plantas m-2), três arranjos de plantas de milho (A = 90 cm entre linhas, 5 plantas m-1; B = 45 cm entre linhas, 2,5 plantas m-1; e C = 45 cm entre linhas, 3 plantas m-1) e um tratamento adicional (maior adubação, sem braquiária e arranjo A do milho). A disponibilidade hídrica influenciou as respostas aos tratamentos. Em ano chuvoso, maior adubação resultou em expressivo incremento da produtividade de grãos, independentemente do arranjo de plantas de milho e da presença de braquiária. Em ano com veranico, o ganho do milho, devido à adubação, foi menor e houve efeito prejudicial da maior densidade de braquiária. A produção de matéria seca pela braquiária não apresentou relação direta com a variação na densidade de plantas

Significant effect of interfacial spin moments in ferromagnet-semiconductor heterojunctions on spin transport in a semiconductor

Using controlled ferromagnet (FM) -semiconductor (SC) interfaces in SC-based lateral spin-valve (LSV) devices, we experimentally study the effect of interfacial spin moments in FM-SC heterojunctions on spin transport in SC. First-principles calculations predict that the spin moment of FM-SC junctions can be artificially reduced by inserting 3d transition metal V, Cr, or Cu atomic layers between FM and SC. When all-epitaxial FM-SC Schottky-tunnel contacts with a 0.4-0.5-nm-thick V, Cr, or Cu interfacial layer are formed, we find that the spin signals in FM-SC LSV devices are significantly decreased at 8 K. When we increase the interfacial spin moment by inserting an ∼0.3-nm-thick Co layer between FM and SC, the spin signals at 8 K are significantly enhanced again. From these experiments, we conclude that the interfacial spin moments at FM-SC interfaces are one of the important factors to achieve large spin signals even in SC-based spintronic devices.T. Naito, R. Nishimura, M. Yamada, A. Masago, Y. Shiratsuchi, Y. Wagatsuma, K. Sawano, R. Nakatani, T. Oguchi, and K. Hamaya, Significant effect of interfacial spin moments in ferromagnet-semiconductor heterojunctions on spin transport in a semiconductor, Phys. Rev. B 105, 195308

Overexpression of the p53-inducible brain-specific angiogenesis inhibitor 1 suppresses efficiently tumour angiogenesis

The brain-specific angiogenesis inhibitor 1 gene has been isolated in an attempt to find fragments with p53 “functional” binding sites. As reported herein and by others, brain-specific angiogenesis inhibitor 1 expression is present in some normal tissues, but is reduced or lost in tumour tissues. Such data and its particular structure prompted the hypothesis that brain-specific angiogenesis inhibitor 1 may act as a mediator in the local angiogenesis balance. We herein demonstrate that brain-specific angiogenesis inhibitor 1 over-expression suppresses tumour angiogenesis, delaying significantly the human tumour growth in immunodeficient mice. The inhibitory effect of brain-specific angiogenesis inhibitor 1 was documented using our intravital microscopy system, strongly implicating brain-specific angiogenesis inhibitor 1 as a mediator in the control of tumour angiogenesis. In contrast, in vitro tumour cell proliferation was not inhibited by brain-specific angiogenesis inhibitor 1 transfection, whereas some level of cytotoxicity was assessed for endothelial cells. Immunohistochemical analysis of tumour samples confirmed a reduction in the microvessel density index in brain-specific angiogenesis inhibitor 1-overexpressing tumours. At messenger level, moderate changes could be detected, involving the down-regulation of vascular endothelial growth factor and collagenase-1 expression. Furthermore, brain-specific angiogenesis inhibitor 1 expression that was lost in a selection of human cancer cell lines could be restored by wild-type p53 adenoviral transfection. Brain-specific angiogenesis inhibitor 1 should be considered for gene therapy and development of efficient drugs based on endogenous antiangiogenic molecules

Discriminação da castanheira (Bertholletia excelsa) com análise de mistura espectral com múltiplos membros-finais aplicada a dados multiespectrais WorldView - 2.

O objetivo da pesquisa é testar a aplicação da Análise de Mistura Espectral com Múltiplos Membros-finais (MESMA; Roberts et al., 1998) para indicação da distribuição espacial de castanhais nativos de Bertholletia excelsa na região de Tefé (AM), norte do Brasil, a fim de subsidiar o manejo sustentável da espécie

Auxiliary role for D-alanylated wall teichoic acid in Toll-like receptor 2-mediated survival of Staphylococcus aureus in macrophages

金沢大学医薬保健研究域薬学系We previously reported that Staphylococcus aureus avoids killing within macrophages by exploiting the action of Toll-like receptor 2 (TLR2), which leads to the c-Jun N-terminal kinase (JNK)-mediated inhibition of superoxide production. To search for bacterial components responsible for this event, a series of S. aureus mutants, in which the synthesis of the cell wall was interrupted, were screened for the level of JNK activation in macrophages. In addition to a mutant lacking the lipoproteins that have been suggested to act as a TLR2 ligand, two mutant strains were found to activate the phosphorylation of JNK to a lesser extent than the parental strain, and this defect was recovered by acquisition of the corresponding wild-type genes. Macrophages that had phagocytosed the mutant strains produced more superoxide than those engulfing the parental strain, and the mutant bacteria were more efficiently killed in macrophages than the parent. The genes mutated, dltA and tagO, encoded proteins involved in the synthesis of D-alanylated wall teichoic acid. Unlike a cell wall fraction rich in lipoproteins, d-alanine-bound wall teichoic acid purified from the parent strain by itself did not activate JNK phosphorylation in macrophages. These results suggest that the D-alanylated wall teichoic acid of S. aureus modulates the cell wall milieu for lipoproteins so that they effectively serve as a ligand for TLR2. © 2009 Blackwell Publishing Ltd

Clone-specific expression, transcriptional regulation, and action of interleukin-6 in human colon carcinoma cells

<p>Abstract</p> <p>Background</p> <p>Many cancer cells produce interleukin-6 (IL-6), a cytokine that plays a role in growth stimulation, metastasis, and angiogenesis of secondary tumours in a variety of malignancies, including colorectal cancer. Effectiveness of IL-6 in this respect may depend on the quantity of basal and inducible IL-6 expressed as the tumour progresses through stages of malignancy. We therefore have evaluated the effect of <it>IL-6 </it>modulators, i.e. IL-1β, prostaglandin E₂, 17β-estradiol, and 1,25-dihydroxyvitamin D₃, on expression and synthesis of the cytokine at different stages of tumour progression.</p> <p>Methods</p> <p>We utilized cultures of the human colon carcinoma cell clones Caco-2/AQ, COGA-1A and COGA-13, all of which expressed differentiation and proliferation markers typical of distinct stages of tumour progression. IL-6 mRNA and protein levels were assayed by RT-PCR and ELISA, respectively. DNA sequencing was utilized to detect polymorphisms in the <it>IL-6 </it>gene promoter.</p> <p>Results</p> <p><it>IL-6 </it>mRNA and protein concentrations were low in well and moderately differentiated Caco-2/AQ and COGA-1A cells, but were high in poorly differentiated COGA-13 cells. Addition of IL-1β (5 ng/ml) to a COGA-13 culture raised IL-6 production approximately thousandfold via a prostaglandin-independent mechanism. Addition of 17β-estradiol (10^-7M) reduced basal IL-6 production by one-third, but IL-1β-inducible IL-6 was unaffected. Search for polymorphisms in the <it>IL-6 </it>promoter revealed the presence of a single haplotype, i.e., -597A/-572G/-174C, in COGA-13 cells, which is associated with a high degree of transcriptional activity of the <it>IL-6 </it>gene. IL-6 blocked differentiation only in Caco-2/AQ cells and stimulated mitosis through up-regulation of c-<it>myc </it>proto-oncogene expression. These effects were inhibited by 10^-8M 1,25-dihydroxyvitamin D₃.</p> <p>Conclusion</p> <p>In human colon carcinoma cells derived from well and moderately differentiated tumours, IL-6 expression is low and only marginally affected, if at all, by PGE₂, 1,25-dihydroxyvitamin D₃, and 17β-estradiol. However, IL-6 is highly abundant in undifferentiated tumour cells and is effectively stimulated by IL-1β. In case of overexpression of an <it>IL-6 </it>gene variant with extreme sensitivity to IL-1β, massive release of the cytokine from undifferentiated tumour cells may accelerate progression towards malignancy by paracrine action on more differentiated tumour cells with a still functioning proliferative IL-6 signalling pathway.</p

Helicobacter pylori Impairs Murine Dendritic Cell Responses to Infection

International audienceBACKGROUND: Helicobacter pylori, a human pathogen associated with chronic gastritis, peptic ulcer and gastric malignancies, is generally viewed as an extracellular microorganism. Here, we show that H. pylori replicates in murine bone marrow derived-dendritic cells (BMDCs) within autophagosomes. METHODOLOGY/PRINCIPAL FINDINGS: A 10-fold increase of CFU is found between 2 h and 6 h p.i. in H. pylori-infected BMDCs. Autophagy is induced around the bacterium and participates at late time points of infection for the clearance of intracellular H. pylori. As a consequence of infection, LC3, LAMP1 and MHC class II molecules are retained within the H. pylori-containing vacuoles and export of MHC class II molecules to cell surface is blocked. However, formalin-fixed H. pylori still maintain this inhibitory activity in BMDC derived from wild type mice, but not in from either TLR4 or TLR2-deficient mice, suggesting the involvement of H. pylori-LPS in this process. TNF-alpha, IL-6 and IL-10 expression was also modulated upon infection showing a TLR2-specific dependent IL-10 secretion. No IL-12 was detected favoring the hypothesis of a down modulation of DC functions during H. pylori infection. Furthermore, antigen-specific T cells proliferation was also impaired upon infection. CONCLUSIONS/SIGNIFICANCE: H. pylori can infect and replicate in BMDCs and thereby affects DC-mediated immune responses. The implication of this new finding is discussed for the biological life cycle of H. pylori in the host