Electroluminescence from erbium-doped nanoscale pn diodes was achieved. Decreasing the number of erbium ions in scaling light-emitting silicon devices decreases the emission intensity. This trend opens new possibility of single-photon emission-key function of quantum communication. Furthermore, doping by ion implantation takes advantage of controlling the number and position of erbium ions in the device. According to this trend, we fabricated pn-diodes with dimensions of telecom wavelength and observed the electroluminescence from the erbium doped region at the forward bias of 1.2 V. We discuss the photoemissivity and the current-voltage characteristics of the device, toward the single-photon emission.

Employment of erbium in silicon devices suffers of difficulties preventing to act as reliable photon source. We review the convergence between single ion implantation and few photon emission regime at room temperature at 1550 nm.

Quantum information processing requires quantum registers based on coherently interacting quantum bits. The dipolar couplings between nitrogen vacancy (NV) centres with nanometre separation makes them a potential platform for room-temperature quantum registers. The fabrication of quantum registers that consist of NV centre arrays has not advanced beyond NV pairs for several years. Further scaling up of coupled NV centres by using nitrogen implantation through nanoholes has been hampered because the shortening of the separation distance is limited by the nanohole size and ion straggling. Here, we demonstrate the implantation of C5N4Hn from an adenine ion source to achieve further scaling. Because the C5N4Hn ion may be regarded as an ideal point source, the separation distance is solely determined by straggling. We successfully demonstrate the fabrication of strongly coupled triple NV centres. Our method may be extended to fabricate small quantum registers that can perform quantum information processing at room temperature.

We report on the photocurrent induced by 1550 nm laser irradiation in a Er-doped micron-scale silicon transistor. The erbium defects, activated in the channel of the transistor thanks to oxygen codoping, make it possible to observe a resonant photocurrent at telecom wavelength and at room temperature by using a supercontinuum laser source working in the μW range. By exploiting a back-gate, the transistor is tuned to exploit only the electrons lying in the Er-O states. We estimate a relatively small number of photoexcited atoms (∼ 4× 104) making Er-dpoed silicon a candidate for designing resonance-based frequency selective single photon detectors at 1550 nm for quantum communications.

An erbium-doped silicon transistor prepared by ion implantation and co-doped with oxygen is investigated by photocurrent generation in the telecommunication range. The photocurrent is explored at room temperature as a function of the wavelength by using a supercontinuum laser source working in the μW range. The 1-μm2 transistor is tuned to involve in the transport only those electrons lying in the Er-O states. The spectrally resolved photocurrent is characterized by the typical absorption line of erbium and the linear dependence of the signal over the impinging power demonstrates that the Er-doped transistor is operating far from saturation. The relatively small number of estimated photoexcited atoms (≈ 4 × 10 4 ) makes Er-dpoed silicon potentially suitable for designing resonance-based frequency selective single photon detectors at 1550 nm.

The simultaneous control of the number and position of negatively charged nitrogen-vacancy (NV) centers in diamond was achieved. While single near-surface NV centers are known to exhibit outstanding capabilities in external spin sensing, trade-off relationships among the accuracy of the number and position, and the coherence of NV centers have made the use of such engineered NV centers difficult. Namely, low-energy nitrogen implantation with lithographic techniques enables the nanoscale position control but results in degradation of the creation yield and the coherence property. In this paper, we show that low-energy nitrogen ion implantation to a 12C (99.95%)-enriched homoepitaxial diamond layer using nanomask is applicable to create shallow NV centers with a sufficiently long coherence time for external spin sensing, at a high creation yield. Furthermore, the NV centers were arranged in a regular array so that 40% lattice sites contain single NV centers. The XY8-k measurements using the individual NV centers reveal that the created NV centers have depths from 2 to 12 nm, which is comparable to the stopping range of nitrogen ions implanted at 2.5 keV. We show that the position-controlled NV centers are capable of external spin sensing with a ultra-high spatial resolution.

We propose a novel process to modify the cell affinity of scaffolds in a cell-culture environment using the photocatalytic activity of visible-light (VL)-responsive TiO2. The proposed process is the improved version of our previous demonstration in which ultraviolet (UV)-responsive TiO2 was utilized. In that demonstration, we showed that cell-repellent molecules on TiO2 were decomposed and replaced with cell-permissive molecules upon UV exposure in the medium where cells are being cultured. However, UV irradiation involves taking the risk of inducing damage to the cells. In this work, a TiO2 film was sputter-deposited on a quartz coverslip at 640 °C without O2 gas injection to create a rutile structure containing oxygen defects, which is known to exhibit photocatalytic activity upon VL exposure. We show that the cell adhesion site and migration area can be controlled with the photocatalytic activity of the VL-responsive TiO2 film, while the cellular oxidative stress is reduced markedly by the substitution of VL for UV.

Ion implantation through nanometer-scale apertures (nano-apertures) is a promising method to precisely position ions in silicon matrices, which is a requirement for next generation electronic and quantum computing devices. This paper reports the application of atom probe tomography (APT) to investigate the three-dimensional distribution of germanium atoms in silicon after implantation through nano-aperture of 10 nm in diameter, for evaluation of the amount and spatial distribution of implanted dopants. The experimental results obtained by APT are consistent with a simple simulation with consideration of several effects during lithography and ion implantation, such as channeling and resist flow.

The demand for single photon emitters at lambda = 1.54 mu m, which follows from the consistent development of quantum networks based on optical fiber technologies, makes Er: O-x centers in Si a viable resource, thanks to the I-4(13/2) -> I-4(15/2) optical transition of Er3+. While its implementation in high-power applications is hindered by the extremely low emission rate, the study of such systems in the low concentration regime remains relevant for quantum technologies. In this Letter, we explore the room-temperature photoluminescence at the telecomm wavelength from very low implantation doses of Er:O-x in Si. The lower-bound number of optically active Er atoms detected is of the order of 10(2), corresponding to a higher-bound value for the emission rate per individual ion of about 10(4) s(-1). (C) 2017 Optical Society of America

A nitridation process of a diamond surface with nitrogen radical exposure far from the radio-frequency plasma for the stabilization of a negatively charged nitrogen-vacancy (NV%) centers near the surface is presented. At a nitrogen coverage of as high as 0.9 monolayers, high average Rabi contrasts of 0.40 +/- 0.06 and 0.46 +/- 0.03 have been obtained for single NV% centers formed by shallow nitrogen implantation with acceleration voltages of 1 and 2 keV, respectively. This indicates that nitrogen termination by a radical exposure process produces an electric charge state suitable for single NV- centers near the surface compared with the states obtained for alternatively terminated surfaces. (C) 2017 The Japan Society of Applied Physics

We investigated the charge state stability and coherence properties of near-surface single nitrogen vacancy (NV) centers in 12C-enriched diamond for potential use in nanoscale magnetic field sensing applications. The stability of charge states in negatively charged NV centers (NV-) was evaluated using one of the pulsed optically detected magnetic resonance measurements, Rabi oscillation measurements. During the accumulation of Rabi oscillations, an unstable shallow NV- was converted to a neutral state. As a result, the contrast of Rabi oscillations degraded, depending on charge state stability. We stabilized the NV- state of very shallow NV centers (∼2.6 ± 1.1nm from the surface) created by 1.2 keV nitrogen ion implantation by diamond surface modification, UV/ozone exposure, and oxygen annealing. This improvement indicates that we can suppress the upward surface band bending and surface potential fluctuations through Fermi level pinning originating from oxygen-terminated diamond surfaces.

A nitridation process of a diamond surface with nitrogen radical exposure far from the radio-frequency plasma for the stabilization of a negatively charged nitrogen-vacancy (NV⁻) centers near the surface is presented. At a nitrogen coverage of as high as 0.9 monolayers, high average Rabi contrasts of 0.40 ± 0.06 and 0.46 ± 0.03 have been obtained for single NV⁻centers formed by shallow nitrogen implantation with acceleration voltages of 1 and 2 keV, respectively. This indicates that nitrogen termination by a radical exposure process produces an electric charge state suitable for single NV⁻centers near the surface compared with the states obtained for alternatively terminated surfaces.

We investigated the charge state stability and coherence properties of near-surface single nitrogen vacancy (NV) centers in ¹²C-enriched diamond for potential use in nanoscale magnetic field sensing applications. The stability of charge states in negatively charged NV centers (NV⁻) was evaluated using one of the pulsed optically detected magnetic resonance measurements, Rabi oscillation measurements. During the accumulation of Rabi oscillations, an unstable shallow NV⁻was converted to a neutral state. As a result, the contrast of Rabi oscillations degraded, depending on charge state stability. We stabilized the NV⁻state of very shallow NV centers (∼2.6 ± 1.1 nm from the surface) created by 1.2 keV nitrogen ion implantation by diamond surface modification, UV/ozone exposure, and oxygen annealing. This improvement indicates that we can suppress the upward surface band bending and surface potential fluctuations through Fermi level pinning originating from oxygen-terminated diamond surfaces.

The actual potential of materials such as silicon and diamond, which are the key materials for quantum processing as well as the basic materials in transistors, has often been realized by adding dopants to modify their electrical or optical properties. This has usually been achieved through a doping process called the ion implantation method. In the future, silicon-based scaled-down transistors will contain a few dopants in the channel. It has been well known that the random distribution of dopants causes significant variations in transistor performance. Further, complementary metal-oxide-semiconductor (CMOS) technologies will require the placement of dopants in a predetermined location, which is referred to as atomistic dopant control. This chapter 4introduces deterministic doping, i.e., a single-ion implantation method, which enables sequential implantation of dopant ions into a fine semiconductor region until the desired number of ions is reached. Self-assembled monolayer doping with loaded dopants is also discussed. This method can help achieve sub-5-nm ultrashallow junctions with spike anneals. These techniques realize atomically controlled dopant profiles in silicon, diamond, and other materials, which could provide opportunities for single-dopant transport or single-photon source beneficial to quantum processing.

Inter-story drift displacement data can provide useful information for story damage assessment. The authors' research group has developed photonic-based sensors for the direct measurement of inter-story drift displacements. This paper proposes a scheme for evaluating the degree of damage in a building structure based on drift displacement sensing. The scheme requires only measured inter-story drift displacements without any additional finite element analysis. A method for estimating yield drift deformation is proposed, and then, the degree of beam end damage is evaluated based on the plastic deformation ratios derived with the yield drift deformation values estimated by the proposed method. The validity and effectiveness of the presented scheme are demonstrated via experimental data from a large-scale shaking table test of a one-third-scale model of an 18-story steel building structure conducted at E-Defense. Copyright (C) 2016 John Wiley & Sons, Ltd.

The main constituent of green tea, (-)-Epigallocatechin-3-O-gallate (EGCG), is known to have cancer-specific chemopreventive effects. In the present work, we investigated how EGCG suppresses cell adhesion by comparing the adhesion of human pancreatic cancer cells (AsPC-1 and BxPC-3) and their counterpart, normal human embryonic pancreas-derived cells (1C3D3), in catechin-containing media using organosilane monolayer templates (OMTs). The purpose of this work is (1) to evaluate the quantitativeness in the measurement of cell adhesion with the OMT and (2) to show how green-tea catechins suppress cell adhesion in a cancer-specific manner. For the first purpose, the adhesion of cancer and normal cells was compared using the OMT. The cell adhesion in different type of catechins such as EGCG, (-)-Epicatechin-3-O-gallate (ECG) and (-)-Epicatechin (EC) was also evaluated. The measurements revealed that the anti-adhesion effect of green-tea catechins is cancer-specific, and the order is EGCG≫ECG>EC. The results agree well with the data reported to date, showing the quantitativeness of the new method. For the second purpose, the contact area of cells on the OMT was measured by reflection interference contrast microscopy. The cell-OMT contact area of cancer cells decreases with increasing EGCG concentration, whereas that of normal cells remains constant. The results reveal a twofold action of EGCG on cancer cell adhesion-suppressing cell attachment to a candidate adhesion site and decreasing the contact area of the cells-and validates the use of OMT as a tool for screening cancer cell adhesion.

The main constituent of green tea, (-)-Epigallocatechin-3-O-gallate (EGCG), is known to have cancer-specific chemopreventive effects. In the present work, we investigated how EGCG suppresses cell adhesion by comparing the adhesion of human pancreatic cancer cells (AsPC-1 and BxPC-3) and their counterpart, normal human embryonic pancreas-derived cells (1C3D3), in catechin-containing media using organosilane monolayer templates (OMTs). The purpose of this work is (1) to evaluate the quantitativeness in the measurement of cell adhesion with the OMT and (2) to show how green-tea catechins suppress cell adhesion in a cancer-specific manner. For the first purpose, the adhesion of cancer and normal cells was compared using the OMT. The cell adhesion in different type of catechins such as EGCG, (-)-Epicatechin-3-O-gallate (ECG) and (-)-Epicatechin (EC) was also evaluated. The measurements revealed that the anti-adhesion effect of green-tea catechins is cancer-specific, and the order is EGCG≫ECG>EC. The results agree well with the data reported to date, showing the quantitativeness of the new method. For the second purpose, the contact area of cells on the OMT was measured by reflection interference contrast microscopy. The cell-OMT contact area of cancer cells decreases with increasing EGCG concentration, whereas that of normal cells remains constant. The results reveal a twofold action of EGCG on cancer cell adhesion-suppressing cell attachment to a candidate adhesion site and decreasing the contact area of the cells-and validates the use of OMT as a tool for screening cancer cell adhesion.

Excitatory and inhibitory neurons have distinct roles in cortical dynamics. Here we present a novel method for identifying inhibitory GABAergic neurons from non-GABAergic neurons, which are mostly excitatory glutamatergic neurons, in primary cortical cultures. This was achieved using an asymmetrically designed micropattern that directs an axonal process to the longest pathway. In the current work, we first modified the micropattern geometry to improve cell viability and then studied the axon length from 2 to 7 days in vitro (DIV). The cell types of neurons were evaluated retrospectively based on immunoreactivity against GAD67, a marker for inhibitory GABAergic neurons. We found that axons of non-GABAergic neurons grow significantly longer than those of GABAergic neurons in the early stages of development. The optimal threshold for identifying GABAergic and non-GABAergic neurons was evaluated to be 110 mu m at 6 DIV. The method does not require any fluorescence labelling and can be carried out on live cells. The accuracy of identification was 98.2%. We confirmed that the high accuracy was due to the use of a micropattern, which standardized the development of cultured neurons. The method promises to be beneficial both for engineering neuronal networks in vitro and for basic cellular neuroscience research.

We study the effect of network size on synchronized activity in living neuronal networks. Dissociated cortical neurons form synaptic connections in culture and generate synchronized spontaneous activity within 10 days in vitro. Using micropatterned surfaces to extrinsically control the size of neuronal networks, we show that synchronized activity can emerge in a network as small as 12 cells. Furthermore, a detailed comparison of small (similar to 20 cells), medium (similar to 100 cells), and large (similar to 400 cells) networks reveal that synchronized activity becomes destabilized in the small networks. A computational modeling of neural activity is then employed to explore the underlying mechanism responsible for the size effect. We find that the generation and maintenance of the synchronized activity can be minimally described by: (1) the stochastic firing of each neuron in the network, (2) enhancement in the network activity in a positive feedback loop of excitatory synapses, and (3) Ca-dependent suppression of bursting activity. The model further shows that the decrease in total synaptic input to a neuron that drives the positive feedback amplification of correlated activity is a key factor underlying the destabilization of synchrony in smaller networks. Spontaneous neural activity plays a critical role in cortical information processing, and our work constructively clarifies an aspect of the structural basis behind this.

© 2016 American Physical Society.We study the effect of network size on synchronized activity in living neuronal networks. Dissociated cortical neurons form synaptic connections in culture and generate synchronized spontaneous activity within 10 days in vitro. Using micropatterned surfaces to extrinsically control the size of neuronal networks, we show that synchronized activity can emerge in a network as small as 12 cells. Furthermore, a detailed comparison of small (∼20 cells), medium (∼100 cells), and large (∼400 cells) networks reveal that synchronized activity becomes destabilized in the small networks. A computational modeling of neural activity is then employed to explore the underlying mechanism responsible for the size effect. We find that the generation and maintenance of the synchronized activity can be minimally described by: (1) the stochastic firing of each neuron in the network, (2) enhancement in the network activity in a positive feedback loop of excitatory synapses, and (3) Ca-dependent suppression of bursting activity. The model further shows that the decrease in total synaptic input to a neuron that drives the positive feedback amplification of correlated activity is a key factor underlying the destabilization of synchrony in smaller networks. Spontaneous neural activity plays a critical role in cortical information processing, and our work constructively clarifies an aspect of the structural basis behind this.

Adhesion of cancer cells with different metastatic potential and anticancer drug resistance has been quantitatively evaluated by using self-assembled monolayer (SAM)-patterned substrates and reflection interference contrast microscopy (RICM). Cell-adhesive SAM spots with optimized diameter could prevent cell cell adhesion and thus allowed the systematic evaluation of statistically reliable numbers of contact area between single cancer cells and substrates by RICM. The statistical image analysis revealed that highly metastatic mouse melanoma cells showed larger contact area than lowly metastatic cells. We also found that both cancer cell types exhibited distinct transition from the "strong" to "weak" adhesion states with increase in the concentration of (-)-epigallo-catechin gallate (EGCG), which is known to exhibit cancer preventive activity. Mathematical analysis of the adhesion transition revealed that adhesion of the highly metastatic mouse melanoma cells showed more EGCG tolerance than that of lowly metastatic cells. Moreover, time-lapse RICM observation revealed that EGCG weakened cancer cell adhesion in a stepwise manner, probably via focal adhesion complex. These results clearly indicate that contact area can be used as a quantitative measure for the determination of cancer phenotypes and their drug resistance, which will provide physical insights into the mechanism of cancer metastasis and cancer prevention.

Dissociated neurons form a uniform network in culture that covers the whole coverslip. The number of neurons in the network and extent of their axon/dendrite elaboration can be controlled by using micropatterned surfaces as growth scaffolds. "Defined" neuronal networks thus fabricated make it possible to study how structure of a network correlates with its functional properties. We first describe surface micropatterning techniques can be used to make an array of neurons and to direct axon-dendrite polarity of each cell. To create functional networks, the isolated neurons must subsequently be interconnected. To accomplish this, the cell-repellent domain between individual neurons needs to be altered from cell-repellent to cell-permissive in the culture medium, so that the neurons would be hard-wired. We developed for this purpose a novel surface modification method using titanium dioxide photocatalysis.

Hippocampal granule cells (GCs) are generated throughout the lifetime and are properly incorporated into the innermost region of the granule cell layer (GCL). Hypotheses for the well-regulated lamination of newly generated GCs suggest that polysialic acid (PSA) is present on the GC surface to modulate GC-to-GC interactions, regulating the process of GC migration; however, direct evidence of this involvement is lacking. We show that PSA facilitates the migration of newly generated GCs and that the activity of N-acetyl-a-neuraminidase 1 (NEU1, sialidase 1) cleaves PSA from immature GCs, terminating their migration in the innermost GCL. Developing a migration assay of immature GCs in vitro, we found that the pharmacological depletion of PSA prevents the migration of GCs, whereas the inhibition of PSA degradation with a neuraminidase inhibitor accelerates this migration. We found that NEU1 is highly expressed in immature GCs. The knockdown of NEU1 in newly generated GCs in vivo increased PSA presence on these cells, and attenuated the proper termination of GC migration in the innermost GCL. In conclusion, this study identifies a novel mechanism that underlies the proper lamination of newly generated GCs through the modulation of PSA presence by neuronal NEU1.

Nanoscale electronic devices will require the placement of dopants in a predetermined location, namely, a single atom control to explore novel functions for future nanoelectronics. Deterministic doping method, i.e. single-ion implantation, realizes ordered arrays of single-atoms in silicon, diamond and other materials, which might provide opportunities to single-dopant transport or single-photon source beneficial to quantum processing.

Single photon sources (SPS) are crucial for quantum key distribution. Here we demonstrate a stable triggered SPS at 738 nm with linewidth less than 5 nm at room temperature based on a negatively charged single silicon vacancy color center. Thanks to the short photon duration of about 1.3-1.7 ns, by using high repetition pulsed excitation at 30 MHz, the triggered single photon source generates 16.6 kcounts/s. And we discuss the feasibility of this triggered SPS in the application of quantum key distribution. (C) 2015 Optical Society of America

Organic contaminants adsorbed on the surface of titanium dioxide (TiO2) can be decomposed by photocatalysis under ultraviolet (UV) light. Here we describe a novel protocol employing the TiO2 photocatalysis to locally alter cell affinity of the substrate surface. For this experiment, a thin TiO2 film was sputter-coated on a glass coverslip, and the TiO2 surface was subsequently modified with an organosilane monolayer derived from octadecyltrichlorosilane (OTS), which inhibits cell adhesion. The sample was immersed in a cell culture medium, and focused UV light was irradiated to an octagonal region. When a neuronal cell line PC12 cells were plated on the sample, cells adhered only on the UV-irradiated area. We further show that this surface modification can also be performed in situ, i.e., even when cells are growing on the substrate. Proper modification of the surface required an extracellular matrix protein collagen to be present in the medium at the time of UV irradiation. The technique presented here can potentially be employed in patterning multiple cell types for constructing coculture systems or to arbitrarily manipulate cells under culture.

Single-photon emitters with stable and uniform photoluminescence properties are important for quantum technology. However, in many cases, colour centres in diamond exhibit spectral diffusion and photoluminescence intensity fluctuation. It is therefore essential to investigate the dynamics of colour centres at the single defect level in order to enable the on-demand manipulation and improved applications in quantum technology. Here we report the polarization switching, intensity jumps and spectral shifting observed on a negatively charged single silicon-vacancy colour centre in diamond. The observed phenomena elucidate the single emitter dynamics induced by photoionization of nearby electron donors in the diamond.

Single-photon emitters with stable and uniform photoluminescence properties are important for quantum technology. However, in many cases, colour centres in diamond exhibit spectral diffusion and photoluminescence intensity fluctuation. It is therefore essential to investigate the dynamics of colour centres at the single defect level in order to enable the on-demand manipulation and improved applications in quantum technology. Here we report the polarization switching, intensity jumps and spectral shifting observed on a negatively charged single silicon-vacancy colour centre in diamond. The observed phenomena elucidate the single emitter dynamics induced by photoionization of nearby electron donors in the diamond.

The authors' research group has developed a noncontact type of sensors which directly measure the inter-story drift displacements of a building during a seismic event. Soon after that event, such seismically-induced drift displacement data would provide structural engineers with useful information to judge how the stories have been damaged. This paper presents a scheme of estimating the story cumulative plastic deformation ratios based on such measured drift displacement information toward the building safety monitoring. The presented scheme requires the data of story drift displacements and the ground motion acceleration. The involved calculations are rather simple without any detailed information on structural elements required: the story hysteresis loops are first estimated and then the cumulative plastic deformation ratio of each story is evaluated from the estimated hysteresis. The effectiveness of the scheme is demonstrated by utilizing the data of full-scale building model experiment performed at E-defense and conducting numerical simulations.

The authors' research group has recently invented a non-contact type of sensing device of directly measuring the inter-story drift displacements for building structures. That sensor obtains the time histories of two dimensional drift displacements during a seismic event. This kind of sensor had been a long-wanted device but was not available until the recent development of these sensors. Utilizing an opportunity of participating in the shake table test experiments of a scale building model at E-defense, the authors' group installed these developed sensors into that model building. Reporting those drift displacement results which the sensors measured from non-severe to severe seismic excitations, this paper demonstrates that the sensors could provide the structural engineers with useful and significant data for damage assessment at the primary stage in particular.

Ge impurities in silicon generate deep donor states in the silicon bandgap. We demonstrate the single ion implantation of Ge ions in the channel of silicon transisteas and their electrical activation. Because of the deep donor ground state of Ge, we realize room temperature impurity bands. Our method enables us to create atomic scale conductive paths in silicon with no need of external gate voltages.

Titanium dioxide (TiO&lt
inf&gt
2&lt
/inf&gt
) photocatalysis can be applied to pattern proteins and cells under aqueous solution. In this work, we extended the application of this technique to patterning primary neurons, a type of cell with relatively weak adhesibility. For this purpose, we employed ribosomal protein L2 (RPL2) that has high affinity toward silica and metal oxides, including TiO&lt
inf&gt
2&lt
/inf&gt
, to stably bind a neuronal adhesion protein laminin to the TiO&lt
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2&lt
/inf&gt
surface. We utilized two types of molecular recognition to achieve this - binding of anti-laminin antibody to its antigen (laminin) and binding of protein A to the antibody. We show that a protein complex consisting of laminin/anti-laminin antibody/protein A-RPL2 is spontaneously formed by simply mixing the precursor proteins in solution phase. We then show that the surface coated with the protein complex supports stable growth of rat hippocampal neurons. Finally, we show that the cells can be selectively grown on the protein complex patterned with the TiO&lt
inf&gt
2&lt
/inf&gt
-assisted method. The protocol established in this work is a unique combination of a top-down micropatterning of the surface using TiO&lt
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2&lt
/inf&gt
photocatalysis and a bottom-up self-assembly of biomolecules, which can be further applied to pattern a wide range of proteins and cells.

Among promising color centers for single-photon sources in diamond, the negatively charged silicon-vacancy (SiV-) has 70% of its emission to the zero-phonon line (ZPL), in contrast to the negatively charged nitrogen vacancy (NV-), which has a broad spectrum. Fabricating single centers of useful defect complexes with high yield and excellent grown-in defect properties by ion implantation has proven to be challenging. We have fabricated bright single SiV- centers by 60-keV focused ion beam implantation and subsequent annealing at 1000 degrees C with high positioning accuracy and a high yield of 15%. (C) 2014 The Japan Society of Applied Physics

We demonstrate a novel application of TiO2 photocatalysis for modifying the cell affinity of a scaffold surface in a cell-culture environment. An as-deposited octadecyltrichlorosilane self-assembled monolayer (OTS SAM) on TiO2 was found to be hydrophobic and stably adsorbed serum albumins that blocked subsequent adsorption of other proteins and cells. Upon irradiation of ultraviolet (UV) light, OTS molecules were decomposed and became permissive to the adhesion of PC12 cells via adsorption of an extracellular matrix protein, collagen. Optimal UV dose was 200 J cm(-2) for OTS SAM on TiO2. The amount of collagen adsorption decreased when excessive UV light was irradiated, most likely due to the surface being too hydrophilic to support its adsorption. This UV-induced modification required TiO2 to be present under the SAM and hence is a result of TiO2 photocatalysis. The UV irradiation for surface modification can be performed before cell plating or during cell culture. We also demonstrate that poly(ethylene glycol) SAM can also be patterned with this method, indicating that it is applicable to both hydrophobic and hydrophilic SAMs. This method provides a unique tool for fabricating cell microarrays and studying dynamical properties of living cells.

We demonstrate a novel application of TiO2 photocatalysis for modifying the cell affinity of a scaffold surface in a cell-culture environment. An as-deposited octadecyltrichlorosilane self-assembled monolayer (OTS SAM) on TiO2 was found to be hydrophobic and stably adsorbed serum albumins that blocked subsequent adsorption of other proteins and cells. Upon irradiation of ultraviolet (UV) light, OTS molecules were decomposed and became permissive to the adhesion of PC12 cells via adsorption of an extracellular matrix protein, collagen. Optimal UV dose was 200 J cm-2 for OTS SAM on TiO2. The amount of collagen adsorption decreased when excessive UV light was irradiated, most likely due to the surface being too hydrophilic to support its adsorption. This UV-induced modification required TiO2 to be present under the SAM and hence is a result of TiO2 photocatalysis. The UV irradiation for surface modification can be performed before cell plating or during cell culture. We also demonstrate that poly(ethylene glycol) SAM can also be patterned with this method, indicating that it is applicable to both hydrophobic and hydrophilic SAMs. This method provides a unique tool for fabricating cell microarrays and studying dynamical properties of living cells.

Future CMOS will require the placement of dopants in a predetermined location, namely, a single atom control. Deterministic doping method, i.e. single-ion implantation, realizes ordered arrays of single-atoms in silicon, diamond and other materials, which might provide opportunities to single-dopant transport or single-photon source beneficial to quantum processing.

We have developed a noncontact-type relative displacement sensor for structural health monitoring which is capable of measuring relative displacement and rotation angle of the object independently. The sensor is composed of a laser as a measurement target and two position sensitive detectors (PSDs). The accuracy of the sensor system was experimentally evaluated to be 0.10 mm in the relative displacement measurement and 0.22 mrad in the rotation angle measurement respectively. These results indicate that the developed sensor system has a sufficient accuracy for structural health monitoring.

We investigated the signal-to-noise ratio (S/N) of real-time single-molecule fluorescence imaging (SMFI) using zero-mode waveguides (ZMWs). The excitation light and the fluorescence propagating from a molecule in the ZMW were analyzed by computational optics simulation. The dependence of the S/N on the ZMW structure was investigated with the diameter and etching depth as the simulation parameters. We found that the SMFI using a conventional ZMW was near the critical level for detecting binding and dissociation events. We show that etching the glass surface of the ZMW by 60 nm enhances the S/N six times the conventional nonetched ZMWs. The enhanced S/N improves the temporal resolution of the SMFI at physiological concentrations. © 2013 American Physical Society.

Formation of an axon is the first morphological evidence of neuronal polarization, visible as a profound outgrowth of the axon compared with sibling neurites. One unsolved question on the mechanism of axon formation is the role of axon outgrowth in axon specification. This question was difficult to assess, because neurons freely extend their neurites in a conventional culture. Here, we leveraged surface nano/micro-modification techniques to fabricate a template substrate for constraining neurite lengths of cultured neurons. Using the template, we asked (i) Do neurons polarize even if all neurites cannot grow sufficiently long? (ii) Would the neurite be fated to become an axon if only one was allowed to grow long? A pattern with symmetrical short paths (20 mu m) was used to address the former question, and an asymmetrical pattern with one path extended to 100 mu m for the latter. Axon formation was evaluated by tau-1/MAP2 immunostaining and live-cell imaging of constitutively-active kinesin-1. We found that (1) neurons cannot polarize when extension of all neurites is restricted and that (2) when only a single neurite is permitted to grow long, neurons polarize and the longest neurite becomes the axon. These results provide clear evidence that axon outgrowth is required for its specification.

To investigate the impact of only the dopant position on threshold voltage (V-th) in nanoscale field-effect transistors, we fabricated transistors with ordered dopant arrays and conventional random channel doping. Electrical measurements revealed that device performance could be enhanced by controlling the dopant position alone, despite varying dopant number according to a Poisson distribution. Furthermore, device-to-device fluctuations in V-th could be suppressed by implanting a heavier ion such as arsenic owing to the reduction of the projected ion struggling. The results of our study highlight potential improvements in device performance by controlling individual dopant positions. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4733289]

We have developed a novel relative-story displacement sensor for structural health monitoring which is capable of measuring the 5-DOF movement of building layers. Three pairs of infrared-light emitting diode arrays and position sensitive detector units were used for simultaneously measuring the relative displacement, the local inclination angle, and the torsion angle between two adjacent layers. For verification, laboratory tests were carried out using a shaking table, a motorized micrometer, and a rotation stage. In the static experiment, it is verified that the local inclination angle and the torsion angle can be measured as well as the relative-story displacement using the sensor system. The resolution of the sensor system in the displacement measurement, that in the inclination angle measurement, and that in the torsion angle measurement were evaluated to be 0.10 mm, 34.4 μrad, and 14.6 μrad, respectively. In the dynamic response experiment, the accuracy of the sensor system was experimentally evaluated to be 0.20 mm in the relative-displacement measurement, 110 μrad in the inclination angle measurement, and 90 μrad in the torsion angle measurement, respectively. These results indicate that the developed sensor system has a sufficient accuracy for structural health monitoring. © 2012 The Japan Society of Mechanical Engineers.

Si transistors with deterministically implanted donors were fabricated by single-ion implantation method and their quantum transport was investigated. By placing donors in one dimensional array, we observed the transport characteristics categorized into two regimes: single-electron tunneling through isolated D^0 and D^- states; Hubbard band formation due to the inter-donor coupling. Our deterministic doping method is more effective and reliable for single-dopant transistor development and paves the way towards single atom electronics for extended CMOS applications.

Si transistors with deterministically implanted donors were fabricated by single-ion implantation method and their quantum transport was investigated. By placing donors in one dimensional array, we observed the transport characteristics categorized into two regimes: single-electron tunneling through isolated D^0 and D^- states; Hubbard band formation due to the inter-donor coupling. Our deterministic doping method is more effective and reliable for single-dopant transistor development and paves the way towards single atom electronics for extended CMOS applications.

Si transistors with deterministically implanted donors were fabricated by single-ion implantation method and their quantum transport was investigated. By placing donors in one dimensional array, we observed the transport characteristics categorized into two regimes: single-electron tunneling through isolated D^0 and D^- states; Hubbard band formation due to the inter-donor coupling. Our deterministic doping method is more effective and reliable for single-dopant transistor development and paves the way towards single atom electronics for extended CMOS applications.

Si transistors with deterministically implanted donors were fabricated by single-ion implantation method and their quantum transport was investigated. By placing donors in one dimensional array, we observed the transport characteristics categorized into two regimes: single-electron tunneling through isolated D^0 and D^- states; Hubbard band formation due to the inter-donor coupling. Our deterministic doping method is more effective and reliable for single-dopant transistor development and paves the way towards single atom electronics for extended CMOS applications.

In-situ guidance of neuronal processes (neurites) is demonstrated by applying wet femtosecond-laser processing to an organosilane self-assembled monolayer (SAM) template. By scanning focused laser beam between cell adhesion sites, on which primary neurons adhered and extended their neurites, we succeeded in guiding the neurites along the laser-scanning line. This guidance was accomplished by multiphoton laser ablation of cytophobic SAM layer and subsequent adsorption of cell adhesion molecule, laminin, onto the ablated region. This technique allows us to arbitrarily design neuronal networks in vitro. (C) 2011 American Institute of Physics. [doi:10.1063/1.3651291]

As semiconductor device dimensions decrease, the individual impurity atom position becomes a critical factor in determining device performance. We fabricated transistors with ordered and random dopant distributions on one side of the channel and evaluated the transconductance to investigate the impact of discrete dopant positions on the electron transport properties. The largest transconductance was observed when dopants were placed on the drain side in an ordered distribution; this was attributed to the suppression of injection velocity degradation on the source side and the uniformity of the electrostatic potential. Thus, the control of discrete dopant positions could enhance the device performance. (C) 2011 American Institute of Physics. [doi:10.1063/1.3622141]

The adhesive ability of two human pancreatic cancer cell lines was evaluated using organosilane monolayer templates (OMTs). Using the OMT, the spreading area of adhered cells can be limited, and this enables us to focus on the initial attachment process of adhesion. Moreover, it becomes possible to arrange the cells in an array and to quantitatively evaluate the number of attached cells. The adhesive ability of the cancer cells cultured on the OMT was controlled by adding (-)-epigallocatechin-3-gallate (EGCG), which blocks a receptor that mediates cell adhesion and is overexpressed in cancer cells. Measurement of the relative ability of the cancer cells to attach to the OMT revealed that the ability for attachment decreased with increasing EGCG concentration. The results agreed well with the western blot analysis, indicating that the OMT can potentially be employed to evaluate the adhesive ability of various cancer cells. (c) 2011 The Japan Society of Applied Physics

Zero-mode waveguides for single-molecule fluorescence imaging were fabricated using a simple desktop UV nanoimprint lithography system. An array of 30- to 150-nm-diameter nanoholes was successfully fabricated in an aluminum layer on a thin quartz plate by the single-step lift-off process using the UV-curable resist NIAC 707. Using the nanoholes, we performed real-time single-molecule fluorescence imaging to visualize the cochaperonin GroES binding with and dissociating from the chaperonin GroEL immobilized within the nanoholes. The demonstration revealed that the fluorescence from the GroES binding with the GroEL was three times stronger than the fluorescence from the GroES undergoing Brownian motion, and the real-time single-molecule fluorescence imaging was feasible using the zero-mode waveguide fabricated by the UV nanoimprint lithography lift-off process. (C) 2011 The Japan Society of Applied Physics

We have developed a novel sensor that enables us to measure the relative story displacement of a building structure in real time. This lateral displacement sensor (LDS) is composed of a light-emitting diode (LED) array, which is fixed on the ceiling, and a position-sensitive detector (PSD) unit, which is placed on the floor. We optimized the LDS to achieve high accuracy in lateral displacement measurement. The accuracy was evaluated to be 60 mu m by conducting shaking table tests. Two LDSs were implemented in an actual building equipped with an active variable stiffness (AVS) system, and the building was vibrated with seismic waveforms by an exciter placed on the rooftop. The seismic displacement of the second floor relative to the first floor was measured using the LDS. Furthermore, the inclination angle of the second floor could be measured using the LDS during the seismic vibration. Using the AVS system, we realized the residual displacement of the second floor without inducing damage to the building, and succeeded in real-time residual displacement measurement for the first time. These results indicate that the LDS is useful for the health diagnosis of a building structure. (C) 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

A single-ion implantation technique that enables us to implant dopant ions one-by-one into semiconductors until the desired number is reached has been developed. The key to controlling the ion number is to detect secondary electrons (SEs) emitted from a target upon ion incidence. The SE detection efficiency currently achieved is 90% due to the low probability of SE emission, but has been enhanced to almost 100% by increasing the number of SEs by controlling the substrate bias voltage. This improvement has accelerated the prospects for realizing single-dopant devices, which are necessary for the ultimate control of the ion number. (C) 2011 The Japan Society of Applied Physics

With the gate length of MOSFETs approaching 10 nm, the channel region contains only one or a few dopant atoms. Thus, the number and position of dopant atoms become critical factors in determining device performance. In previous work, we have revealed that the control of not only the dopant atom number but also its position is essential by experimentally for the first time [1]. A several theoretical analyses of random dopant fluctuation (RDF) effects have been presented since 1990s [2,3,4]. However, the effect of individual dopant positions on device electrical properties is not well understood experimentally. Here, we report the fabrication of transistors whose channel dopants are implanted one by one using single-ion implantation (SII) method [5,6,7]. Electrical measurements reveal that controlling of discrete dopant position serves to highlight the improvements in device transconductance. © 2011 IEEE.

We have developed a novel relative-story displacement sensor capable of measuring the 5-degree-of-freedom movement of building layers for structural health monitoring. Three pairs of infrared-light emitting diode arrays and position-sensitive detector units were used for simultaneously measuring the relative-story displacement, the inclination angle of the lower layer, and the torsion angle between two adjacent layers. For verification, laboratory tests were carried out using a shaking table, a motorized micrometer and a rotation stage. In the static experiment, it is verified that the local inclination angle and the torsion angle can be measured as well as the relative-story displacement using the sensor system. The resolution of the sensor system in the displacement measurement, that in the inclination angle measurement, and that in the torsion angle measurement were evaluated to be 0.10 mm, 34.4 mu rad, and 14.6 mu rad, respectively. In the dynamic response experiment, the accuracy of the sensor system was experimentally evaluated to be 0.20 mm in the relative-displacement measurement, 110 mu rad in the inclination angle measurement, and 90 mu rad in the torsion angle measurement, respectively. These results indicate that the developed sensor system has a sufficient accuracy for the structural health diagnostics of buildings.

We have developed a novel sensor that enables us to measure the relative story displacement of a building structure in real time. This lateral displacement sensor (LDS) is composed of a light-emitting diode (LED) array, which is fixed on the ceiling, and a position-sensitive detector (PSD) unit, which is placed on the floor. We optimized the LDS to achieve high accuracy in lateral displacement measurement. The accuracy was evaluated to be 60 μm by conducting shaking table tests. Two LDSs were implemented in an actual building equipped with an active variable stiffness (AVS) system, and the building was vibrated with seismic waveforms by an exciter placed on the rooftop. The seismic displacement of the second floor relative to the first floor was measured using the LDS. Furthermore, the inclination angle of the second floor could be measured using the LDS during the seismic vibration. Using the AVS system, we realized the residual displacement of the second floor without inducing damage to the building, and succeeded in real-time residual displacement measurement for the first time. These results indicate that the LDS is useful for the health diagnosis of a building structure. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley &amp
Sons, Inc.

We propose a novel relative-story displacement sensor for structural health monitoring. The sensor is composed of three pairs of position sensitive detector (PSD) units and light emitting diode (LED) arrays, and is capable of measuring both the local inclination angle of the PSD unit and the relative displacement between the PSD unit and the LED array. By immobilizing the LED arrays on the ceiling and the PSD units on the floor, we can accurately measure the relative-story displacement in real time. We have verified the measurement accuracy of the developed sensor using a shaking table and a θ stage, and the accuracy was evaluated to be approximately 0.15 mm in the displacement and 0.1 mrad in the local rotation angle. The results indicate that the developed sensor is applicable to the relative-story displacement measurement for the diagnostics of an actual building.

We propose a novel relative-story displacement sensor for structural health monitoring. The sensor is composed of three pairs of position sensitive detector (PSD) units and light emitting diode (LED) arrays, and is capable of measuring both the local inclination angle of the PSD unit and the relative displacement between the PSD unit and the LED array. By immobilizing the LED arrays on the ceiling and the PSD units on the floor, we can accurately measure the relative-story displacement in real time. We have verified the measurement accuracy of the developed sensor using a shaking table and a θ stage, and the accuracy was evaluated to be approximately 0.15 mm in the displacement and 0.1 mrad in the local rotation angle. The results indicate that the developed sensor is applicable to the relative-story displacement measurement for the diagnostics of an actual building.

We propose a novel sensor system for monitoring the structural health of a building. The system optically measures the relative-story displacement during earthquakes for detecting any deformations of building elements. The sensor unit is composed of three position sensitive detectors (PSDs) and lenses capable of measuring the relative-story displacement precisely, even if the PSD unit was inclined in response to the seismic vibration. For verification, laboratory tests were carried out using an X theta-stage and a shaking table. The static experiment verified that the sensor could measure the local inclination angle as well as the lateral displacement. The dynamic experiment revealed that the accuracy of the sensor was 150 mu m in the relative-displacement measurement and 100 mu rad in the inclination angle measurement. These results indicate that the proposed sensor system has sufficient accuracy for the measurement of relative-story displacement in response to the seismic vibration.

We propose a novel relative-story displacement sensor for structural health monitoring. The sensor is composed of three pairs of position sensitive detector (PSD) units and light emitting diode (LED) arrays, and is capable of measuring both the local inclination angle of the PSD unit and the relative displacement between the PSD unit and the LED array. By immobilizing the LED arrays on the ceiling and the PSD units on the floor, we can accurately measure the relative-story displacement in real time. We have verified the measurement accuracy of the developed sensor using a shaking table and a θ stage, and the accuracy was evaluated to be approximately 0.15 mm in the displacement and 0.1 mrad in the local rotation angle. The results indicate that the developed sensor is applicable to the relative-story displacement measurement for the diagnostics of an actual building.

It has been widely believed that an asymmetric GroEL-GroES complex (termed the bullet-shaped complex) is formed solely throughout the chaperonin reaction cycle, whereas we have recently revealed that a symmetric GroEL-(GroES)(2) complex (the football-shaped complex) can form in the presence of denatured proteins. However, the dynamics of the GroEL-GroES interaction, including the football-shaped complex, is unclear. We investigated the decay process of the football-shaped complex at a single-molecule level. Because submicromolar concentrations of fluorescent GroES are required in solution to form saturated amounts of the football-shaped complex, single-molecule fluorescence imaging was carried out using zero-mode waveguides. The single-molecule study revealed two insights into the GroEL-GroES reaction. First, the first GroES to interact with GroEL does not always dissociate from the football-shaped complex prior to the dissociation of a second GroES. Second, there are two cycles, the "football cycle " and the "bullet cycle," in the chaperonin reaction, and the lifetimes of the football-shaped and the bullet-shaped complexes were determined to be 3-5 s and about 6 s, respectively. These findings shed new light on the molecular mechanism of protein folding mediated by the GroEL-GroES chaperonin system.

Recently, relative displacement measurement attracts much attention because of its capability for directly monitoring damages of a building structure. We have developed a noncontact-type relative displacement monitoring system by arranging a two-dimensional PSD paired with a LED array on each story, and investigated the feasibility of this system from the viewpoint of measurement accuracy.

We propose a novel sensor for directly measuring the relative displacement of a building structure. The sensor is composed of a laser light source and a phototransistor (PT) at-ray. The PT array is immobilized on the floor together with a photo scattering plate made of glass, whereas the laser light source is separately immobilized on the ceiling. The photo scattering plate is placed in front of the PT array and distributes the laser beam oil the multiple PTs. The relative displacement between the ceiling and the floor is estimated by the distribution of the PT output voltages, and the displacement is estimated with a resolution finer than the interval between the PTs. The accuracy of the relative displacement sensor (RDS) is experimentally assessed by conducting a shaking table test exhibiting several waves from harmonic sinusoidal waves to real seismic waves. We discuss the feasibility of real-time monitoring system utilizing this sensor. (C) 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Objectives: Green tea epigalocatechin galate (EGCG) has been shown to exhibit a growth-suppressive effect on human pancreatic cancer cells; however, the exact molecular mechanism by which EGCG suppresses cell proliferation is unclear. We hypothesize that interference with cell adhesion might be one mechanism. Methods: The effect of EGCG on cell adhesion and proliferation was examined using pancreatic cancer cells. Results: EGCG-treated pancreatic cancer cells AsPC-1 and BxPC-3 decrease cell adhesion ability on micro-pattern dots, accompanied by dephosphorylations of both focal adhesion kinase (FAK) and insulin-like growth factor 1 receptor (IGF-1R), whereas retained the activations of mitogen-activated protein kinase and mammalian target of rapamycin. The growth of AsPC-1 and BxPC-3 cells, when cultured at low density, can be significantly suppressed by EGCG treatment alone in a dose-dependent manner. At a dose of 100 mu M that completely abolishes activations of FAK and IGF-1R, EGCG suppresses more than 50% of cell proliferation without evidence of apoptosis analyzed by PARP cleavage. Finally, the MEK1/2 inhibitor U0126 enhances growth-suppressive effect of EGCG. Conclusions: Blocking FAK and IGF-1R by EGCG could prove valuable for targeted therapy, which can use in combination with other therapies, for pancreatic cancer.

The exact molecular mechanism by which epigallocatechin gallate (EGCG) suppresses human pancreatic cancer cell proliferation is unclear. We show here that EGCG-treated pancreatic cancer cells AsPC-1 and BxPC-3 decrease cell adhesion ability on micropattern dots, accompanied by dephosphorylations of both focal adhesion kinase (FAK) and insulin-like growth factor-1 receptor (IGF-1R) whereas retained the activations of mitogen-activated protein kinase and mammalian target of rapamycin. The growth of AsPC-1 and BxPC-3 cells can be significantly suppressed by EGCG treatment alone in a dose-dependent manner. At a dose of 100 mu M which completely abolishes activations of FAK and IGF-1R, EGCG suppresses more than 50% of cell proliferation without evidence of apoptosis analyzed by PARP cleavage. Finally, the MEK1/2 inhibitor U0126 enhances growth-suppressive effect of EGCG. Our data suggests that blocking FAK and IGF-1R by EGCG could prove valuable for targeted therapy, which can be used in combination with other therapies, for pancreatic cancer.

For reliable deterministic single-atom doping, i.e. single-ion implantation (SII), improvement of single-ion detection efficiency is successfully achieved by controlling channel potential using back-gate of transistor. We also fabricate transistors whose channel dopnats are introduced one-by-one using SII and find that subthreshold current becomes larger when dopants are located at drain-side than source-side. The single-atom doping method could contribute to the novel device development beneficial for extensibility of doped-channel device technologies towards atomic-scale devices and single-dopant device.

A relative-story displacement sensor for measuring the ceiling-floor displacement and the floor inclination angle was developed. Three pairs of position-sensitive detector (PSD) units and light emitting diode (LED) arrays were utilized for the measurement. The measurement accuracy of the sensor was evaluated using a shaking table and a theta-stage. The outputs from the developed sensor agreed well with the reference, and the accuracy was evaluated to be approximately 0.15 mm in the displacement and 0.1 mrad in the local inclination angle. These results indicate that the developed sensor resolves the angular error problem on the relative-story displacement measurement and is applicable for assessing the safety of actual buildings.

We propose a novel sensor for directly measuring the relative displacement of a building structure. The sensor is composed of a laser light source and a phototransistor (PT) array. The PT array is immobilized on the floor together with a photo scattering plate made of glass, whereas the laser light source is separately immobilized on the ceiling. The photo scattering plate is placed in front of the PT array and distributes the laser beam on the multiple PTs. The relative displacement between the ceiling and the floor is estimated by the distribution of the PT output voltages, and the displacement is estimated with a resolution finer than the interval between the PTs. The accuracy of the relative displacement sensor (RDS) is experimentally assessed by conducting a shaking table test exhibiting several waves from harmonic sinusoidal waves to real seismic waves. We discuss the feasibility of real-time monitoring system utilizing this sensor. © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley &amp
Sons, Inc.

The exact molecular mechanism by which epigallocatechin gallate (EGCG) suppresses human pancreatic cancer cell proliferation is unclear. We show here that EGCG-treated pancreatic cancer cells AsPC-1 and BxPC-3 decrease cell adhesion ability on micro-pattern dots, accompanied by dephosphorylations of both focal adhesion kinase (FAK) and insulin-like growth factor-1 receptor (IGF-1R) whereas retained the activations of mitogen-activated protein kinase and mammalian target of rapamycin. The growth of AsPC-1 and BxPC-3 cells can be significantly suppressed by EGCG treatment alone in a dose-dependent manner. At a dose of 100M which completely abolishes activations of FAK and IGF-1R, EGCG suppresses more than 50 of cell proliferation without evidence of apoptosis analyzed by PARP cleavage. Finally, the MEK1/2 inhibitor U0126 enhances growth-suppressive effect of EGCG. Our data suggests that blocking FAK and IGF-1R by EGCG could prove valuable for targeted therapy, which can be used in combination with other therapies, for pancreatic cancer. Copyright © 2010 Hoang Anh Vu et al.

The exact molecular mechanism by which epigallocatechin gallate (EGCG) suppresses human pancreatic cancer cell proliferation is unclear. We show here that EGCG-treated pancreatic cancer cells AsPC-1 and BxPC-3 decrease cell adhesion ability on micropattern dots, accompanied by dephosphorylations of both focal adhesion kinase (FAK) and insulin-like growth factor-1 receptor (IGF-1R) whereas retained the activations of mitogen-activated protein kinase and mammalian target of rapamycin. The growth of AsPC-1 and BxPC-3 cells can be significantly suppressed by EGCG treatment alone in a dose-dependent manner. At a dose of 100 mu M which completely abolishes activations of FAK and IGF-1R, EGCG suppresses more than 50% of cell proliferation without evidence of apoptosis analyzed by PARP cleavage. Finally, the MEK1/2 inhibitor U0126 enhances growth-suppressive effect of EGCG. Our data suggests that blocking FAK and IGF-1R by EGCG could prove valuable for targeted therapy, which can be used in combination with other therapies, for pancreatic cancer.

We present a simple method for improving the field emission performance of tungsten-tip electron sources based on single-walled carbon nanotube (SWCNT) modification. By coating a sandwich-like thin film of Al-Fe-Al (with Fe as a catalyst) on a tungsten tip, SWCNTs were synthesized at 600°C in a chemical vapor deposition (CVD) reactor. The influence of CNT modification on the electron emission characteristics of the emitters was investigated by means of a triode structure. We have found that CNT-modified tungsten tips exhibit low threshold-voltage for electron emission, and improved emission-current stability, compared with nonmodified and Al-Fe-Al-coated needles. © 2006 American Institute of Physics.

Preferential immobilization of a protein by using a nano-patterned organosilane monolayer as the template was investigated. A passivation film of an organosilane self-assembled monolayer was formed on a silicon dioxide layer by chemical vapor deposition. Then, the inside of the pattern was modified with active chemical groups. At each step, a fluorescent image of the fluophore-labeled biotin, the avidin, and the green fluorescent protein (GFP) was obtained by fluoroscent microscope.

We have succeeded in detecting the adenosine triphosphate (ATP) concentration in a solution quantitatively using an ATP-molecule recognition chip. The ATP-molecule recognition chip is composed of a silicon photodiode on which bioluminous enzyme luciferase is immobilized. When the chip was immersed in an ATP-containing solution, the luciferase emitted light and the photoinduced current detected by the photodiode was in proportion to the ATP concentration. We found that the photoinduced current fits the Michaelis-Menten plot. These results indicate that the luciferase is successfully immobilized on the silicon chip without losing the bioluminous activity and that the proposed device enables us to detect the ATP concentration in a solution by measuring the photoinduced current.

Using an electrochemical scanning tunneling microscope (ECSTM), we have observed nucleation and growth of Cu clusters on highly oriented pyrolytic graphite (HOPG). In situ observations were made at different sample potentials. Firstly, preliminary images were obtained at the sample potential where Cu did not precipitate. Then, we obtained images at the sample potential where Cu deposition was observed. We found superperiodic structures on the top graphite layer and Cu clusters of about 2 nm in diameter formed along the step-edge with a constant interval. The interval between clusters had a same periodicity as that of the superperiodic structure. Namely, the superperiodic structure on the top graphite layer induced nucleation of Cu along the step-edge. (C) 2000 Elsevier Science B.V. All rights reserved.

We have developed a technique for detecting single-ions that uses CR-39 plastic. Chemical etching of the plastic enables us to visualize both the incident sites and the existence of the single-ion incidences as etch pits. Using this technique, we obtained a singularity rate of 88.3%. (C) 1999 American Institute of Physics. [S0034-6748(99)00711-X].

We report, for the first time, the behavior of Cu nucleation and growth on hydrogen- (H-) terminated Si(111) surface in solution. The samples were prepared by immersing H-terminated Si(111) surfaces in Cu-containing sulfuric acid solution with various immersion times. The Cu-adsorbed silicon surfaces were observed with an atomic force microscope (AFM). Statistical analysis of the AFM images indicates that Cu nucleation occurred immediately after immersing into the solution, and the coverage of the surfaces with Cu adsorbates increased linearly with immersion time although the average height increased negligibly. These results suggest that the growth behavior of Cu adsorbate on H-terminated Si(111) surfaces is fundamentally two-dimensional due to the long-range migration of Cu ions which were reduced at the silicon/solution interface.

The amount of charges induced by high energy single ion irradiation at a p-n junction diode has been measured and its dependence on the ion incident position has been evaluated by using single-ion microprobe technique. By irradiating single He ions with various incident energy (1.4-4.05 MeV), dependence of the profiles of collected charges on the ion incident energy has been investigated. Origins of the different profiles among the different incident energy are discussed in terms of different contribution of two mechanisms of charge collection, namely, field funneling and diffusion of carriers. In the case of the ion incidence within the junction area, dependence of the charge collection profile on the ion incident energy comes from different contribution of the funneling in the charge collection process, while difference in the collection efficiency of the diffused charges affects the profile in the case of the ion incidence at outside of the junction. (C) 1998 American Institute of Physics.

Soft-error immunity of a 256kbit DRAM against quasi-heavy ion irradiation has been evaluated using He single ion microprobe at Waseda University. The technique for hitting micron size area with arbitrary number of He ions enables us to simulate the space environment under irradiation of heavy ions with higher LET than that of alpha-particles. From the maps of error-sensitive sites obtained by irradiating various number of He ions, the threshold LET of soft-errors, effect of diffused charges on the soft-error cross section, and susceptibility to multi-bit errors have been estimated. The results of measuring single-ion induced noise charges at the PN junction which is considered as equivalent to the storage node of the DRAM have been presented and the origins which determine the soft-error immunity under irradiation with various LET have been discussed.

Radiation effects induced by MeV He single ions in pMOSFETs and nMOSFETs in commercially available CMOS4007 have been studied extensively. The key results from this study are: (1) pMOSFETs are more fragile than nMOSFETs in terms of threshold voltage shift, (2) nMOSFETs are more susceptible than pMOSFETs to the degradation of subthreshold swing. The different features in the radiation effects have been discussed comprehensively.

The scalability of alpha-particle-induced soft errors has been evaluated. We have irradiated individual sites in and near a PN-junction area with single alpha particles and measured the charge collected at the junction. As the PN-junction size is reduced, the charge collected by diffusion upon the incidence of alpha particles at the outer area around the junction increases relative to the charge collected upon direct incidence at the junction area. This suggests that the soft-error-sensitive area is not scaled down even if memory cell size is reduced.

Localized ion irradiation effects in n-channel metal-oxide-semiconductor field-effect transistor (n-ch MOSFET) have been investigated quantitatively by means of both the single ion microprobe (SIMP) and single ion beam induced charge (SIBIC) imaging. An extremely large leakage current in the subthreshold gate voltage V-g-drain current I-d characteristics (V-g < threshold voltage V-th) have been induced by exposing a small fraction of the MOSFET gate area to MeV He single ions, while the turn-on V-g-I-d characteristics (V-g > V-th) have scarcely been affected. The causes of the large leakage current in the subthreshold region induced by the localized ion irradiation have been discussed. (C) 1996 American Institute of Physics.

Generation rates of Si/SiO2 interface defects, namely, the oxide trapped holes and the interface states, by MeV He single ion irradiation have been investigated quantitatively. From the analysis of threshold voltage shifts induced by single ions of 2 MeV He, the number of the oxide trapped holes and the interface states induced in an n-ch MOSFET in CMOS4007 by a single ion have been estimated to be about 28 and 9, respectively. The hole trapping efficiency is almost 100% at the ion dose below 1 ions/mu m(2). (C) 1996 American Institute of Physics.

Total dose effect on the soft-error susceptibility of 64kbit CMOS SRAM has been investigated by using the single ion microprobe technique which enables us to get a map of soft-error sensitivity in a memory cell by hitting a micron-size area with single ions. The effects of the ion dose on the susceptibility of each error-sensitive site have been evaluated. The errors due to the upset of p-MOSFETs have become more susceptible at higher dose while that of the n-MOSFETs less susceptible. One of the origins of the errors are the negative threshold voltage(V-th) shifts of the MOSFETs which are caused by oxide trapped charges. Displacement damage induced by ion irradiation also affects the susceptibility to the soft-error.

To achieve quantitative analysis of site-dependent total dose effects in metal-oxide-semiconductor field-effect transistors (MOSFETs), a new imaging technique designated as the reverse-mode single ion beam induced charge (R-mode SIBIC) imaging for sample positioning combined with accurate ion counting has been developed using the single-ion microprobe. With only five He single ions per pixel, we have succeeded in obtaining images of n-ch MOSFET and n-type Si regions fabricated on a p-well without any degradation of device characteristics. The R-mode SIBIC imaging has made it possible to count exactly the number of ions incident upon the MOSFET during radiation hardness tests.

In order to minimize image degradation of IBIC (ion beam induced charge) during observation, the single ion beam induced charge (SIBIC) imaging technique has been developed by using a single ion microprobe, which enables us to hit a particular site of a device with single ions one by one. With only five He single ions per pixel, we have succeeded in obtaining reasonable quality images of an active area of a device. Since the number of defects induced by five single ions is quite low, the irradiated device was still alive for subsequent process and device diagnoses.