Scanning gate microscopy (SGM) is a novel technique that has been used to image characteristic features related to the coherent electron flow in mesoscopic structures. For instance, SGM has ...successfully been applied to study peculiar electron transport properties that arise due to small levels of disorder in a system. The particular case of an InGaAs quantum well layer in a heterostructure, which is dominated by a quasi-ballistic regime, was analyzed. A quantum point contact fabricated onto this material exhibits conduction fluctuations that are not expected in typical high-mobility heterostructures such as AlGaAs/GaAs. SGM revealed not only interference patterns corresponding to specific conductance fluctuations but also mode-dependent resistance peaks corresponding to the first and second quantum levels of conductance (2e(2)/h) at zero magnetic field. On the other hand, clear conductance plateaus originating from the integer quantum Hall effect were observed at high magnetic fields. The physical size of incompressible edge channels was estimated from cross-sectional analysis of these images.
In the present study we examined involvement of nuclear protein tyrosine phosphatase TC-PTP in PRL-mediated signaling. TC-PTP could dephosphorylate signal transducer and activator of transcription 5a ...(STAT5a) and STAT5b, but the apparent dephosphorylation activity of TC-PTP was weaker than that of cytosolic PTP1B 30 min after PRL stimulation in transfected COS-7 cells, whereas both STAT5a and STAT5b were dephosphorylated to the same extent by recombinant TC-PTP and PTP1B in vitro. Tyrosine-phosphorylated STAT5 was coimmunoprecipitated with substrate trapping mutants of TC-PTP, suggesting that STAT5 is a specific substrate of TC-PTP. These observations were further extended in mammary epithelial COMMA-1D cells stably expressing TC-PTP. A time-course study revealed that dephosphorylation of STAT5 by TC-PTP was delayed compared with that by cytosolic PTP1B due to nuclear localization of TC-PTP throughout PRL stimulation in mammary epithelial cells. Endogenous beta-casein gene expression and beta-casein gene promoter activation in COS-7 cells were largely suppressed by TC-PTP wild type as well as catalytically inactive mutants, suggesting that stable complexes formed between STAT5 and TC-PTP in the nucleus. Taken together, we conclude that TC-PTP is catalytically competent with respect to dephosphorylation and deactivation of PRL-activated STAT5 in the nucleus.
The gonad quality of sea urchin (Mesocentrotus nudus) adults from a barren can be improved by feeding the animals fronds of the kelp Saccharina japonica from May–July. The improvement in taste is ...expected to depend on the amino acid composition of the kelp fronds, which varies among the frond portions. We investigated the effects of feeding apical, middle and basal frond portions of S. japonica on gonad size, hardness, color (L*a*b*) and taste (free amino acids) of M. nudus from a barren from May–July in a rearing experiment in which we analyzed the protein and total and free amino acid content of each frond portion. Feeding of each frond portion improved gonad size, hardness, color and taste. Feeding of the basal portion, which contained high levels of glutamic acid, alanine, and proline, markedly increased the alanine and glutamic acid content and decreased the content of bitter-tasting amino acids in gonads, implying greatly enhanced sweet and umami taste. Based on a comparison of alanine content with that reported in past studies of M. nudus, the gonad taste would be evaluated at a higher level. The basal portion of S. japonica fronds has the high potential to improve gonad taste.
•Apical, middle and basal frond portions of Saccharina kelp were fed to Mesocentrotus nudus.•Feeding of each frond portion improved gonad size, hardness, color and taste.•Basal portion markedly increased alanine and glutamic acid contents in gonads.•Basal portion showed high potential to improve gonad taste.
We have fabricated a high mobility device, composed of a monolayer graphene flake sandwiched between two sheets of hexagonal boron nitride. Conductance fluctuations as functions of a back gate ...voltage and magnetic field were obtained to check for ergodicity. Non-linear dynamics concepts were used to study the nature of these fluctuations. The distribution of eigenvalues was estimated from the conductance fluctuations with Gaussian kernels and it indicates that the carrier motion is chaotic at low temperatures. We argue that a two-phase dynamical fluid model best describes the transport in this system and can be used to explain the violation of the so-called ergodic hypothesis found in graphene.
A new type of micromixer for rapid mixing was developed based on mixing by both kinetic energy and molecular diffusion of fluids. The rapid mixing was realized by the collision of micro segments, ...which were divided into several streams in the radial, at the center of the mixer. The excellent performance of the developed micromixer was confirmed by examining the Villermaux/Dushman reaction and the precipitation of polymer particles by phase separation. From these results, it was clarified that the rapid mixing was driven by both the breaking of micro segments under a high shear rate and instant molecular diffusion between micro segments. In addition, the mixer had a high throughput and corresponded to a wide range of flow rate ratios of fluids. Thus, it is expected that the proposed design concept for micro mixing will give us an efficient micro processing route in the future.
A new type of micromixer for rapid mixing was developed based on mixing by utilization of both the kinetic energy and molecular diffusion of fluids. Rapid mixing was realized by the collision of micro segments. From the excellent performance and high throughput of the developed micromixer, it is expected that the proposed design concept for micromixing will yield an efficient micro processing route in the future.
We investigate the linear and non-linear conductance of quantum point contacts (QPCs), in the region near pinch-off where Kondo physics has previously been connected to the appearance of the 0.7 ...feature. In studies of seven different QPCs, fabricated in the same high-mobility GaAs/AlGaAs heterojunction, the linear conductance is widely found to show the presence of the 0.7 feature. The differential conductance, on the other hand, does not generally exhibit the zero-bias anomaly (ZBA) that has been proposed to indicate the Kondo effect. Indeed, even in the small subset of QPCs found to exhibit such an anomaly, the linear conductance does not always follow the universal temperature-dependent scaling behavior expected for the Kondo effect. Taken collectively, our observations demonstrate that, unlike the 0.7 feature, the ZBA is not a generic feature of low-temperature QPC conduction. We furthermore conclude that the mere observation of the ZBA alone is insufficient evidence for concluding that Kondo physics is active. While we do not rule out the possibility that the Kondo effect may occur in QPCs, our results appear to indicate that its observation requires a very strict set of conditions to be satisfied. This should be contrasted with the case of the 0.7 feature, which has been apparent since the earliest experimental investigations of QPC transport.
Using expression analysis, the role of the sucrose transporter OsSUT1 during germination and early growth of rice seedlings has been examined in detail, over a time-course ranging from 1 d to 7 d ...post-imbibition. Unlike the wheat orthologue, TaSUT1, which is thought to be directly involved in sugar transfer across the scutellar epithelium, OsSUT1 is not expressed in the scutellar epithelial cell layer of germinating rice and is, therefore, not involved in transport of sugars across the symplastic discontinuity between the endosperm and the embryo. OsSUT1 expression was also absent from the aleurone cells, indicating it is not involved in the transport of sucrose in this cell layer during germination. However, by 3 d post-imbibition, OsSUT1 was present in the companion cells and sieve elements of the scutellar vascular bundle, where it may play a role in phloem loading of sucrose for transport to the developing shoot and roots. This sucrose is most likely sourced from hexoses imported from the endosperm. In addition, sucrose may be remobilized from starch granules which are present at a high density in the scutellar ground tissues surrounding the vasculature and at the base of the shoot. OsSUT1 was also present in the coleoptile and the first and second leaf blades, where it was localized to the phloem along the entire length of these tissues, and was also present within the phloem of the primary roots. OsSUT1 may be involved in retrieval of sugars from the apoplasm in these tissues.
Signal transducer and activator of transcription 3 (STAT3), which mediates biological actions in many physiological processes, is activated by cytokines and growth factors, and has been reported to ...be constitutively activated in numerous cancer cells. In this study, we examined whether low molecular weight-dual specificity phosphatase two (LMW-DSP2) is involved in the regulation of the interleukin 6 (IL-6)/leukemia inhibitory factor (LIF)/STAT3-mediated signaling pathway. IL-6/LIF-induced LMW-DSP2 expression in murine testicular or hepatoma cell lines, while LMW-DSP2 overexpression in 293T cells suppressed IL-6-induced phosphorylation and activation of STAT3. Furthermore, LMW-DSP2 suppressed the expression of IL-6-induced endogenous genes. In contrast, small-interfering RNA-mediated reduction of LMW-DSP2 expression enhanced IL-6-induced STAT3-dependent transcription. In fact, LMW-DSP2 interacted with STAT3 in vivo and endogenous LMW-DSP2 bound to STAT3 in murine testicular GC-1 cells. These results strongly suggest that LMW-DSP2 acts as a negative regulator of the IL-6/LIF/STAT3-mediated signaling pathway.
Using an approach that allows us to probe the electronic structure of strongly pinched-off quantum point contacts (QPCs), we provide evidence for the formation of self-consistently realized bound ...states (BSs) in these structures. Our approach exploits the resonant interaction between closely coupled QPCs, and demonstrates that the BSs may give rise to a robust confinement of single spins, which show clear Zeeman splitting in a magnetic field.
With an aim of decreasing the temperature at which metallic Y reacts with H2 to form the semiconductor phase YH3 (γ phase), we employed Pd and Ni co-capping layers as catalysts. For this purpose, ...various types of Pd/Ni co-capping layers having different Ni thicknesses varied from 5 to 80nm while having a Pd thickness of 80nm were prepared as a catalytic capping layer on metal Y. We achieved an onset temperature (50°C) of the γ phase formation, which is approximately independent of Ni thickness except for 40nm. A directing principle for decreasing the onset temperature of the γ phase formation was discussed in terms of crystal texture and crystallite size of dihydride phase (β phase).
•Low-temperature and low-H2 pressure synthesis of YH3 using a new capping layer.•Developing the Pd/Ni co-capping catalysis layer.•Varying Ni thickness from 5 to 80nm, while maintaining Pd thickness at 80nm.•Ni thicknesses except 40nm show low-temperature (∼50°C) YH3 formation.•The 40nm-Ni material with poor crystal quality shows poor YH3 formation.
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