Osaka UniversityOsaka

Ōsaka, Japan

Osaka UniversityOsaka

Ōsaka, Japan
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Sharma A.,Indian Institute of Technology Hyderabad | Sharma A.,Osaka UniversityOsaka | Bandari V.,Indian Institute of Technology Hyderabad | Bandari V.,Osaka UniversityOsaka | And 4 more authors.
Journal of Manufacturing Processes | Year: 2017

Motivated by the recent use of friction stirring in the manufacture of in-situ composites, a new additive manufacturing method for the design and manufacture of tailor-made functionally graded composites is presented. The existing literature on the subject matter is limited to creating functional grades in the vicinity of the weld nugget without direct control on composition and property gradients. A mathematical model is developed for achieving a compositional gradient over a predefined length in a metal matrix composite and subsequently demonstrated through the manufacture of aluminum + TiC functionally graded composite. Progressive gradients are observed in hardness and local mechanical properties, namely, Young's modulus, stain hardening exponent, and yield stress obtained using the digital image correlation technique. The process mechanism is elucidated by correlating results of mechanical tests and electron backscatter diffraction analysis. A specific process condition vis-à-vis the number of passes, volume faction, and particle size combination may promote one or more phenomena such as continuous dynamic recrystallization, particle fragmentation, and breaking of initial matrix grains, which eventually affect particle mixing and matrix grain size and thus cause property gradients. The findings are expected to enable the manufacture of functionally graded composites products of larger size. © 2017 The Society of Manufacturing Engineers

Yoshii T.,Kyoto University | Hosokawa H.,Kyoto University | Matsuo N.,Osaka UniversityOsaka | Matsuo N.,Kyoto University
Neuropharmacology | Year: 2017

Fear memory extinction has several characteristic behavioral features, such as spontaneous recovery, renewal, and reinstatement, suggesting that extinction training does not erase the original association between the conditioned stimulus (CS) and the unconditioned stimulus (US). However, it is unclear whether reactivation of the original physical record of memory (i.e., memory trace) is sufficient to produce conditioned fear response after extinction. Here, we performed pharmacogenetic neuronal activation using transgenic mice expressing hM3Dq DREADD (designer receptor exclusively activated by designer drug) under the control of the activity-dependent c-fos gene promoter. Neuronal ensembles activated during fear-conditioned learning were tagged with hM3Dq and subsequently reactivated after extinction training. The mice exhibited significant freezing, even when the fear memory was no longer triggered by external CS, indicating that the artificial reactivation of a specific neuronal ensemble was sufficient to evoke the extinguished fear response. This freezing was not observed in non-fear-conditioned mice expressing hM3dq in the same brain areas. These results directly demonstrated that at least part of the original fear memory trace remains after extinction, and such residual plasticity might reflect the persistent memory. © 2016 Elsevier Ltd

Koizumi K.,Osaka UniversityOsaka | Tanimoto C.,The International Institute for Advanced StudiesKyoto | Iwasaki Y.,Cyber UniversityFukuoka | Li L.H.,CAS Institute of Geology and Geophysics | And 2 more authors.
Ancient Underground Opening and Preservation - Proceedings of the International Symposium on Scientific Problems and Long-Term Preservation of Large-Scale Ancient Underground Engineering, 2015 | Year: 2016

Fundamental environmental information is necessary to preserve stone caves. An advanced environmental monitoring system, wireless sensor network, was installed in the Longyou Grottoes, China, in August 2010. This study develops a system by which a filed manager and his/her cooperating researchers are able to continuously monitor environmental conditions in and around caves. It confirms that wireless monitoring is effective, even if observed objects, such as Cave 2 and Cave 3, are far from the base station. The outside air did not affect Cave 2 and affected only the upper part of Cave 3 during the surveillance period. These findings are based on the date of first 50 days of monitoring. The next step is to observe the seasonal variations and differences of the caves. © 2016 Taylor & Francis Group, London.

Chen J.,Japan Advanced Institute of Science and Technology | Mazumder R.,Japan Advanced Institute of Science and Technology | Miyaji A.,Japan Advanced Institute of Science and Technology | Miyaji A.,Japan Science and Technology Agency | Miyaji A.,Osaka UniversityOsaka
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2016

A cryptographic hash is defined as a transformation of variable length-message into a fixed length value. The application of cryptographic hash is increasing day by day. In modern cryptography, it is now defined as “Swiss Army Knife of Cryptography” because of usage in the verify process of integrity for files or messages, verification of the password, file/data identifier, pseudo-random generation and key derivation. The cryptographic hash consists of a compression function, where compression function can be built by scratch or blockcipher. The blockcipher based hash is suitable for constrained device (WSN device) encryption because of direct hardware implementation of the blockcipher. The blockcipher hash can be categorized into (n, n) and (n, 2n) [(block-length, key-length)]. A class of (n, n) is more suitable than the (n, 2n) because of less power and memory utilization. There are some familiar schemes of (n, n) blockcipher hash such as MDC-2, MDC-4, MJH, Bart-12, MSR, where some schemes provide higher security bound and some are good for efficiency. The schemes of MDC-2, MDC-4, Bart, MSR need multiple key scheduling but the MJH needs single key scheduling. The proof technique of early mentioned schemes are based on the ideal cipher model (ICM), except the Bart and MJH. These two follows a model of the finite field multiplicative operation. In this paper, we proposed a scheme of (n, n) blockcipher hash that satisfies a single key scheduling (KS = 1). The collision and preimage resistance of our scheme is bounded by O (2n) and O (22n). Our scheme follows three calls of blockcipher under the Davies Meyer (DM) mode. At first, we use the ICM proof technique. Later, we provide the weak cipher model (WCM) proof technique, which is more rigorous than the ICM. © Springer International Publishing Switzerland 2016.

Al-Naamani E.,Osaka UniversityOsaka | Ide M.,Osaka UniversityOsaka | Gopal A.,Osaka UniversityOsaka | Saeki A.,Osaka UniversityOsaka | And 2 more authors.
Journal of Photopolymer Science and Technology | Year: 2015

Benzotrithiophene (BTT), where three thiophenes are fused to a central benzene, was polymerized with three kinds of electron accepting units, thiadiazolopyridine (TP), difluorobenzothiadiazole (FT), or naphthobisthiadiazole (NTz). These low bandgap polymers exhibited deep HOMO level (-5.4 ~-5.6 eV) which can lead to increasing open circuit voltage (VOC) of bulk heterojunction organic photovoltaics (OPV). One of the BTT polymers and methano[60]fullerene (PCBM) blend showed a high VOC of 0.99 V, owing to the deep HOMO level and low energy loss. The best power conversion efficiency (PCE) of 2.7% was obtained for the BTT-NTz polymer blended with methano[70]fullerene. We have intensively characterized optoelectronic and morphological features of the new polymers by atomic force microscopy, 2-dimensional X-ray diffraction, and time-resolved microwave conductivity. This work highlights the potential of BTT-based polymers for an increase of PCE, because there are extra rooms for further improvement. © 2015 SPST.

Minamoto T.,Osaka UniversityOsaka | Azuma M.,Osaka UniversityOsaka | Yaoi K.,Kyoto University | Ashizuka A.,Kyoto University | And 4 more authors.
Frontiers in Human Neuroscience | Year: 2014

The posterior parietal cortex (PPC) has two attentional functions: top-down attentional control and stimulus-driven attentional processing. Using the focused version of the reading span test (RST), in which the target word to be remembered is the critical word for comprehending a sentence (focused word) or a non-focused word, we examined the effect of tDCS on resolution of distractor interference by the focused word in the non-focus condition (top-down attentional control) and on augmented/shrunk attentional capture by the focused word in both the focus and non-focus conditions (stimulus-driven attentional processing). Participants were divided into two groups: anodal tDCS (atDCS) and cathodal tDCS (ctDCS). Online stimulation was given while participants performed the RST. A post-hoc recognition task was also administered in which three kinds of words were presented: target words in the RST, distractor words in the RST, and novel words. atDCS augmented the effect of the focused word by increasing differences in performance between the focus and non-focus conditions. Such an effect was not observed in the ctDCS group. As for the recognition task, atDCS again produced the augmented effect of the focused words in the distractor recognition. On the other hand, ctDCS brought less recognition of non-focused target words in comparison to sham. The results indicate that atDCS promotes stimulus-driven attentional processing, possibly by affecting neural firing in the inferior parietal regions. In contrast, ctDCS appears to prevent retrieval of less important information from episodic memory, which may require top-down attentional processing. © 2014 Minamoto, Azuma, Yaoi, Ashizuka, Mima, Osaka, Fukuyama and Osaka.

Assadi M.H.N.,Osaka UniversityOsaka | Hanaor D.A.H.,University of Sydney
Applied Surface Science | Year: 2016

Copper dopants are varyingly reported to enhance photocatalytic activity at titanium dioxide surfaces through uncertain mechanisms. In order to interpret how copper doping might alter the performance of titanium dioxide photocatalysts in aqueous media we applied density functional theory methods to simulate surface units of doped anatase (101) planes. By including van der Waals interactions, we consider the energetics of adsorbed water at anatase surfaces in pristine and copper doped systems. Simulation results indicate that copper dopant at anatase (101) surfaces is most stable in a 2+ oxidation state and a disperse configuration, suggesting the formation of secondary CuO phases is energetically unfavourable. In agreement with previous reports, water at the studied surface is predicted to exhibit molecular adsorption with this tendency slightly enhanced by copper. Results imply that the enhancement of photoactivity at anatase surfaces through Cu doping is more likely to arise from electronic interactions mediated by charge transfer and inter-bandgap states increasing photoexcitation and extending surface-hole lifetimes rather than through the increased density of adsorbed hydroxyl groups. © 2016 Elsevier B.V.

Goto Y.,Osaka University | Goto Y.,Osaka UniversityOsaka | Oshino S.,Osaka UniversityOsaka | Shimizu T.,Osaka UniversityOsaka | And 2 more authors.
Journal of Clinical Neuroscience | Year: 2016

We aimed to evaluate combined use of atelocollagen sheet and fibrin glue for sellar reconstruction. Experiment 1: A plastic chamber was prepared with a hydroxyapatite lid with a hole of 10 mm in diameter at its center, covered with a Gore-Tex sheet (W.L. Gore & Associates, Tokyo, Japan) 15 mm in diameter and sealed with a combination of fibrin glue sealant and either atelocollagen sheet or polyglycolic acid (PGA) sheet. Air was injected into the chamber and the pressure at which air leakage occurred was measured under each situation. Mean (± standard deviation) leakage pressure was 816 ± 162 mmH2O for atelocollagen sheet (n = 5), significantly higher than the 557 ± 130 mmH2O for PGA sheet (n = 5, p < 0.05, Wilcoxon test). Experiment 2: Bilateral 5 mm bone windows were made in the temporal bone in eight rats. The surgical cavities were filled with one of four materials (fibrin glue only; fibrin glue and atelocollagen sheet; PGA sheet; or autologous fat tissue). Histological changes including the status of implanted materials and inflammatory responses were investigated 2 and 5 weeks after the procedures. Both atelocollagen and PGA sheets remained at 5 weeks after implantation, whereas fibrin glue and fat tissue were absorbed and undetectable at 2 weeks. Inflammatory cell accumulation was less around the atelocollagen sheet compared to the PGA sheet. The combination of atelocollagen sheet and fibrin glue sealant showed sufficient adhesion force and favorable tissue affinity, suggesting this combination as a feasible material in sellar reconstruction. © 2015 Elsevier Ltd.

Yanagisawa K.,Osaka UniversityOsaka | Shirafuji S.,Osaka UniversityOsaka | Ikemoto S.,Osaka UniversityOsaka | Hosoda K.,Osaka UniversityOsaka
Advances in Intelligent Systems and Computing | Year: 2016

To realize both grasp stability and manipulation dexterity is a central problem in the development of robot hands. In recent years, many underactuated robot hands have been developed that flexibly conform to an object’s surface with simple control. In contrast, it is difficult to realize dexterous manipulation by such underactuated hands in which all degrees of freedom (DoFs) should be controlled. In this research, to realize the dexterous manipulation by simple mechanism and control, we develop a robot gripper comprising of two tendon-driven robotic fingers with nonelastic branching tendons. The branching tendon is a tendon that branches out and connects an actuator to different links. The two joints of this robotic finger are coupled by the nonelastic branching tendon when no external force is exerted. If sufficient external force is applied to the fingertip, one of the tendons slackens and the coupling between the two joints is lost. This means that the two-DoF robotic finger is easily controlled as a single DoF mechanism when reaching toward an object, but when the fingertip is placed on the object, the coupling provided by the branching tendon is released and the finger shifts. Based on this idea, we develop and control a two-DoF robotic finger equipoed with two tendons including a nonelastic branching tendon. We also analyze the conditions, where the branching tendon slacken, and confirmed in an experiment. As the result, the availability of controlling the slack of branched tendon was successfully confirmed. © Springer International Publishing Switzerland 2016.

Zeng Z.,Osaka UniversityOsaka | Mizukami S.,Osaka UniversityOsaka | Fujita K.,Osaka UniversityOsaka | Kikuchi K.,Osaka UniversityOsaka
Chemical Science | Year: 2015

Near-infrared (NIR) fluorescence imaging is promising due to the high penetration depths and minimal levels of autofluorescence in living systems. However, it suffers from low fluorescent quantum yield, and metal-enhanced fluorescence (MEF) is considered to be a promising technique to overcome this. Stimuli-responsive NIR fluorescence enhancement shows remarkable potential for applications in medical imaging and diagnosis. Herein, we successfully fabricated an enzyme-responsive near-infrared sensor based on MEF by functionalizing gold nanoparticles with NIR fluorophores and enzyme-responsive self-aggregation moieties. The NIR fluorescence of fluorophores on the gold nanoparticles was significantly enhanced due to increases both in the light scattering intensity and in the radiative decay rate (kr) of the NIR fluorophores, along with relatively small variation in the nonradiative decay rate. This novel strategy for NIR fluorescent sensors should be particularly promising for NIR fluorescence imaging of enzyme activities and early diagnosis based on rationally designed nanomaterials. This journal is © The Royal Society of Chemistry.

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