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Simulation involving interaction with deformable objects often causes stability problems because a slowly updated force generates additional energy to the human user. This paper proposes a stable and transparent haptic rendering for simulation involving interaction between a rigid tool and deformable objects. This method computes visual and haptic feedback in the simulation and haptic feedback loops, respectively. A local stiffness matrix consisting of points around contact points is constructed based on collision detection between a virtual tool and a deformable object in the simulation loop. The haptic feedback is then computed at a higher update rate in the haptic feedback loop using the local stiffness matrix. Equivalent springs computed by using the equivalent stiffness energy are added to the boundary of the local stiffness matrix to minimize errors in the rendered force. The proposed method is compared with the virtual coupling widely used in simulation involving interaction with deformable objects. The proposed method reduces the x -, y -, and z -axis maximum force errors by up to 52%, 80%, and 70%, respectively, compared to the virtual coupling in the simulation involving interaction with the Stanford bunny object consisting of 2087 points and 9997 tetrahedrons.

The sodium-air (Na–air) batteries are considered as a new promising energy storage devices due to their 1683 W h kg−1 of high theoretical specific energy density. However, these outstanding theoretical energy density performances cannot be achieved because undesirable sluggish oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) reaction kinetics on the air cathode side causes the high overpotential gap and low round-trip efficiencies during charge-discharge process. Therefore, the development of highly active bifunctional oxygen electrocatalysts is the key strategy to obtain the low overpotential gap with high energy density performance of Na-air batteries. In this work, a novel single crystalline thallium ruthenium oxide (Tl2Ru2O7) with pyrochlore structure was firstly revealed as an effective bifunctional electrocatalyst. Moreover, in order to enhance the surface chemical reactivity of Tl2Ru2O7, the surface of Tl2Ru2O7 is functionalized by using the dihydrogen phosphate ion (P-Tl2Ru2O7) for achieving the effective and rapid charge transfer behavior. The superior bifunctional catalytic activity of P-Tl2Ru2O7 can be explained by the degree of covalency of Ru-O bonds in Tl2Ru2O7 and enhanced covalent character by functionalized dihydrogen phosphate ion, which can afford favorable oxidation nature to Tl and Ru ions.

The sodium-air (Na-air) batteries are spotlighted as state-of-the-art electrical energy storage system, because of their high sodium-ion conductivity and specific energy density performance. However, the undesirable sluggish oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) kinetics limit the practical production of rechargeable Na-air batteries. Therefore, it is essential to develop highly effective bifunctional electrocatalysts for OER and ORR. Although the pyrochlore oxides (A2B2O7) exhibits great potential for highly-active bifunctional electrocatalyst, the lack of studies regarding to A-site cations have hindered the development of new pyrochlore catalysts with comprehensive understanding of catalytic activity. In this work, we report the use of a novel nanocrystalline bismuth ruthenate pyrochlore oxide (Bi2Ru2O7) as an effective oxygen electrocatalyst by using the favorable oxidation nature of Bi and Ru ions in Bi2Ru2O7. Further, the oxidized cations can donate the electrons to the surface and inner layers, providing the low-resistance pathway during OER and ORR. Finally, the bifunctional electrocatalytic activities of Bi2Ru2O7 are successfully translated to a practical device, an aqueous Na-air battery, for the first time.

Chalcogenide-based materials have attracted widespread interest in high-performance thermoelectric research fields. A strategy for the application of two types of chalcogenide for improved thermoelectric performance is described herein. Tin selenide (SnSe) is used as a base material, and Te nanoneedles are crystallized in the SnSe, resulting in the generation of a composite structure of SnSe with Te nanoneedles. The thermoelectric properties with various reaction times are investigated to reveal the optimum conditions for enhanced thermoelectric performance. A reaction time of 4 h at 450 K generated a composite Te nanoneedles/SnSe sample with the maximum ZT value, 3.2 times larger than that of the pristine SnSe. This result is attributed to both the reduced thermal conductivity from the effective phonon scattering of heterointerfaces and the improved electrical conductivity value due to the introduction of Te nanoparticles. This strategy suggests an approach to generating high-performance practical thermoelectric materials.

SUMMARYPrevious researches on analysis of stability of haptic simulation largely assume that the virtual environment is passive. But the virtual environment can become non-passive due to various reasons including discretization errors and interaction dynamics between virtual tools and objects. This paper provides an analysis of the stability and performance of the haptic simulation involving non-passive virtual environment. The dynamic interaction between the virtual tools and the objects is modeled using the two-port networks. The analysis is carried out using a velocity and force mapping matrix for six-DOF simulation. New stability condition resulting from the analysis is applied to an example simulation of a one-DOF virtual wall. Maximum stiffness satisfying the stability condition established in the previous literature, and the proposed condition is compared with the maximum stiffness experimentally determined with various time steps. The newly proposed stability condition manifests less standard deviation of errors than the widely applied absolute stability condition.

The third-generation synchrotron radiation accelerator has been providing beams to users since 1995 and have been made to upgrade the performances of the accelerators and the experimental devices. For that reason, the PLS-II was started in 2009 as a three-year project. An important feature is the extension of the ID (insertion device) beamline and the efficient placement of the storage ring magnet structure. The overall structure of the beamline as well as the length and structure of the front end had to be changed to expand the ID beamline. Also, the safety of many vacuum parts that would be exposed to the large heat due to the increase in the beam energy was firstly considered in the design, and an analysis was performed in parallel. This paper describes the overall structure of the front end, including the design and analysis of the vacuum components in the Pohang Light Source(PLS)-II beamline.

Nitrogen and sulfur co-doped mesoporous carbon sphere (NSMCS) was prepared as a metal-free catalyst by an economical and facile pyrolysis process. The mesoporous carbon spheres were derived from sodium carboxymethyl cellulose as the carbon source and the nitrogen and sulfur dopants were derived from urea and p-benzenedithiol, respectively. The doping level and chemical states of nitrogen and sulfur in the prepared NSMCS can be easily adjusted by controlling the pyrolysis temperature. The NSMCS pyrolyzed at 900 °C (NSMCS-900) exhibited higher oxygen reduction reaction activity than the mesoporous carbon sphere doped solely with nitrogen or sulfur, due to the synergistic effect of co-doping. Among all the NSMCS samples, NSMCS-900 exhibited excellent ORR catalytic activity owing to the presence of a highly active site, consisting of pyridinic N, graphitic N, and thiophene S. Remarkably, the NSMCS-900 catalyst was comparable with commercial Pt/C, in terms of the onset and the half-wave potentials and showed better durability than Pt/C for ORR in an alkaline electrolyte. The approach demonstrated in this work could be used to prepare promising metal-free electrocatalysts for application in energy conversion and storage.

Graphitic carbon nitride/mesoporous carbon sphere composites were successfully synthesized using a simple, three-step treatment, and the effects of the mesoporous carbon sphere (MPCS) content on the electrochemical properties of the composites were studied. The MPCSs were homogeneously captured and dispersed on the prepared graphitic carbon nitride (GCN), forming a GCN/MPCS nanocomposite structure. These composite materials exhibited better electrochemical properties than previously reported electric double-layer capacitor (EDLC) materials, such as carbon nanotubes, graphene, activated carbon, and carbon spheres. The addition of a small amount of mesoporous carbon spheres, typically 1:2 by weight (GCN/MPCS), to form GCN/MPCS(2) resulted in an excellent specific charge capacity of 352.44 F g−1 at a scan rate of 5 mV s−1. These results indicate the potential of the composite for the development of highly capacitive energy storage devices with practical applications.

MgCo2O4 nanoneedles were introduced on the surface of micro and mesoporous silicon carbide flakes (SiCF) to synthesize a supercapacitor with high capacitive performance, made of hybrid electrode materials. Based on the synergistic effect between electric double layer capacitive contributions of SiCF and faradic reaction of MgCo2O4, the SiCF/MgCo2O4 electrode shows outstanding energy storage performance, exhibiting a 310.02 C g−1 of specific stored charge capacity at 5 mV s−1 with high capacity retention ratio over wide range of scan rates (83.2% at 500 mV s−1). Furthermore, in conjunction with a capacitive SiCF negative electrode in a quasi-solid-state PVA-KOH KI gel electrolyte, it resulted in a unique redox-active flexible solid-state asymmetric supercapacitor device. It delivers outstanding capacitive performance (specific stored charge capacity of 185.88 C g−1 at 5 mV s−1), with maximum energy density of 41.308 Wh kg−1 at 464.72 W kg−1 of power density, surpassing many recently reported flexible supercapacitors. Moreover, the ability to operate 3-V green light-emitting diodes (LED) at bending state also indicates its possibility for practical application. Therefore, these novel electrode materials with unique redox-active solid state electrolyte may find promising applications in flexible energy storage devices in future.

Na–air batteries have received significant attention as possible candidates for alternative battery systems due to their high specific energy density (1683 W h kg−1). However, the undesirable sluggish kinetics of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) limit the practicality of the production of rechargeable Na–air batteries. Recently, pyrochlore oxides (A2B2O7) have received great attention as effective bifunctional electrocatalysts. However, the comprehensive understanding of catalytic activity with the development of new pyrochlore catalysts is unsatisfactory due to the limited use of B-site cations. Here, we report the use of a novel nanocrystalline bismuth rhodium oxide (Bi2Rh2O6.8) crystal with a pyrochlore structure as a bifunctional electrocatalyst. Moreover, the surface of Bi2Rh2O6.8 was modified via phosphate-ion functionalization (P-Bi2Rh2O6.8) to enhance its surface chemical reactivity, resulting in fast and efficient charge transfer with high ORR and OER activities. During electrocatalysis, the functionalized H2PO4− ion can not only significantly enhance the surface reactivity for a fast and efficient electron/charge-transfer reaction but also facilitate the oxidation of Bi and Rh ions and boost the electron donation by improving the electron transport. Finally, the first successful translation of the bifunctional electrocatalytic activities of P-Bi2Rh2O6.8 to a practical device, an aqueous Na–air battery, was demonstrated.

The 3d transition metal-based catalysts have emerged as prospective electrocatalysts for the oxygen evolution reaction (OER) owing to the wide availability of transition metals in the Earth’s crust, as well as the low cost and long lifetime of the catalysts. However, their moderate activity for the OER is a challenge for commercial applications. In this study, a heterostructure (W@Ni(OH)2/CC) composed of Ni(OH)2 nanosheets and tungsten nanoparticles was successfully synthesized on a conductive carbon cloth to overcome the problem of deficient catalytic activity. The constructed heterointerface and the two-dimensional (2D) nanosheet morphology of the catalyst can accelerate the charge transfer, OER kinetics, and the ion/gas transport. In addition, interfacial electronic structure optimization was investigated to facilitate the formation of oxyhydroxide intermediates on the catalyst surface, which enhances the overall OER performance. This paper provides a thorough explanation on the role of modified electronic configuration in the heterostructures and proposes a new path to synthesize these heterostructures.

Micro- and mesoporous silicon carbide (SiC)/ferroferric oxide (Fe 3 O 4 ) composites (SiC/Fe 3 O 4 ) were prepared (to develop novel supercapacitor electrode materials) via chemical deposition of Fe 3 O 4 on SiC surfaces by chemical reduction of an Fe precursor. Based on the synergistic contributions between the electric double layer capacitive contribution of SiC and the pseudocapacitive contribution of Fe 3 O 4 , the SiC/Fe 3 O 4 electrode exhibits outstanding charge storage capacity, exhibiting a specific capacitance of 423.2 F g −1 at 5 mV s −1 with high capacitance retention ratio over a wide range of scan rates (81.8% at 500 mV s −1 ). In conjunction with a capacitive SiC positive electrode in a quasi-solid-state PVA-KOH- p -nitroaniline (PVA-KOH-PNA) gel electrolyte, it resulted in a unique redox-active flexible solid-state asymmetric supercapacitor device. Due to the vigorous redox reactions of Fe 3 O 4 nanoparticles and the p -nitroaniline redox active electrolyte, the device delivers outstanding capacitive performance (specific capacitance of 97.6 F g −1 at 5 mV s −1 ) with maximum energy density of 48.94 Wh kg −1 at power density of 463.64 W kg −1 , surpassing many recently reported flexible supercapacitors. Therefore, these novel electrode materials with unique redox-active solid-state electrolytes may find promising applications in flexible energy storage devices.

Ni(OH)2 nanoparticles were decorated on mesoporous carbon spheres (MPCS) using a simple hard template method. The MPCS were derived from sodium carboxymethyl cellulose. As-prepared MPCS/Ni(OH)2 nanocomposites were used as electrode materials for supercapacitors. These composites exhibited better electrochemical properties than a pristine mesoporous carbon sphere owing to the synergistic effect. However, the increase in Ni(OH)2 is not proportional to the electrochemical performance improvement. The addition of an optimal amount of Ni(OH)2, typically 1:20 by weight (MPCS:NiCl2·6H2O), showed an excellent specific capacitance of 1338.296 F g−1 at a scan rate of 5 mV s−1. These encouraging results indicate excellent potential for the development of highly capacitive energy storage devices for practical applications.

MgCo 2 O 4 nanoneedles were deposited onto micro and mesoporous silicon carbide flakes (SiCF) to synthesize hybrid electrode materials with high capacitive performance for use as supercapacitors. These SiCF/MgCo 2 O 4 electrodes were fabricated at different MgCo 2 O 4 feeding ratios to determine the optimal MgCo 2 O 4 amount for both total surface area coverage and a suitable redox reaction rate by maximizing the synergy between the electric double layer capacitive effects of SiCF and the Faradic reaction of MgCo 2 O 4 nanoneedles. The SiCF/MgCo 2 O 4 electrode formed at a MgCo 2 O 4 /SiCF feeding ratio of 1.8:1 (SiCF/MgCo 2 O 4 (1.8)) had a specific surface area of 1069 m 2 g −1 . This surface featured the highest specific stored charge capacity of 310.02 C g -1 at a scan rate of 5 mV s -1 with 83.2% rate performance when the scan rate was increased from 5 to 500 mV s -1 in a 1 M KOH electrolyte. The outstanding electrochemical performance of the SiCF/MgCo 2 O 4 (1.8) electrode can be attributed to the ideal electrode material design, considering both the electric double-layer capacitive contribution of SiCF and the battery-type electrochemical behavior of the MgCo 2 O 4 nanoneedles on the SiCF surface. For high capacity electrode materials, this hybrid material strategy introduces possibilities for combinations of porous silicon carbide with other battery-type binary metal oxide materials.

This paper proposes a new control architecture for stable and transparent haptic rendering of interactive simulation involving a rigid tool and deformable objects. The traditional direct and proxy-based haptic rendering schemes are analyzed for the absolute stability, and transmit impedance employing the well-known bilateral control architecture frequently used in the field of teleoperation systems. An equivalent impedance is conveyed in the proposed control scheme to the haptic device instead of the contact force between the virtual tool and the object. The trade-off problem between the absolute stability and the transmitted impedance is resolved by computing the haptic feedback using the equivalent impedance. The proposed rendering scheme shows higher transparency than the conventional haptic rendering methods while maintaining the absolute stability.

A higher figure of merit (ZT) can be achieved for tin selenide (SnSe)-based thermoelectric materials by significantly reducing the thermal conductivity (κ) via three promising strategies: substitution with isoelectric atoms, exfoliation of nanosheets (NSs) from a bulk ingot, and chemical transformation of the material into a porous structure. Specifically, SnSe1–xSx NSs are prepared from bulk ingots by hydrothermal Li intercalation and subsequent exfoliation. The substitution of S atoms into SnSe and the fabrication of SnSe1–xSx NSs contribute to the scattering of phonons at a number of atomic disorders and nanosized boundaries, leading to effective reduction of the κ value and an improved ZT. The introduction of porosity into the material through the chemical transformation process results in further reduction of κ, which leads to a higher ZT. The fabricated porous SnSe0.8S0.2 NS has a maximal ZT value of 0.12 at 310 K, which is significantly higher than that of pristine SnSe.

Graphene/Co3O4 nanowire composite films were successfully synthesized using a simple, three-step treatment, and the effect of the Co3O4 nanowire content on the electrochemical properties of the composite films was studied. The one-dimensional Co3O4 nanowires were homogeneously embedded and dispersed between prepared graphene papers, forming a layered graphene/Co3O4 nanowire hybrid structure. These composite films exhibited better electrochemical properties than previously reported ones, such as graphene/CNT, where carbon spheres existed in the graphene composites, which were fabricated using the same method but without the Co3O4 nanowires. The addition of a small amount of Co3O4—typically 8 : 1 by weight (reduced graphene oxide (RGO) : Co3O4)—to form thick RGO/Co3O4 sandwiches in the form of papers resulted in an excellent specific charge capacity of 278.936 C g−1 at a scan rate of 5 mV s−1. These results indicate the potential of the composite for the development of highly capacitive energy storage devices for practical applications.

Recently, diverse research has actively been conducted to control the posture of jumping robots using an inertial tail mechanism. However, the inertial tail mechanism has a high probability of collision with obstacles. In this study, a momentum wheel mechanism is proposed to achieve the same attitude control performance while reducing the volume occupied by the inertial tail mechanism. To verify the performance of the momentum wheel mechanism, we proposed a jumping robot with a momentum wheel mechanism and performed a dynamic analysis, simulation, and experiments on a jumping robot with a momentum wheel mechanism. In addition, it has been demonstrated that the momentum wheel mechanism can contribute to control of the body angle of the jumping robot. As a result, the momentum wheel mechanism can enhance the stability of the jumping robot more than the tail mechanism, and the momentum wheel mechanism contributes to the attitude control of the body angle, which allows the jumping robot to perform continuous jumping.

Supercapacitors have been attracting considerable interest because of their wide range of applications in electric vehicles, digital devices due to their high power density, short charging time, and long cycling life. For ideal charge/discharge mechanism, the micro and mesoporous silicon carbide flakes (PSF) with a high surface area of 1376 m 2 g −1 were obtained by one-step carbonization of Si flakes. The micropores originated from the partial evaporation of Si atoms during the carbonization process, while the mesopores were formed by the integration of neighboring micropores. Subsequently, oxygen-containing functional groups were introduced on the PSF surface to stimulate the faradic redox reaction during the charge/discharge process. The PSF electrode oxidized for 24 h (OPSF–24 h) exhibits a high charge storage capacity, showing a specific capacitance of 243.3 F g −1 at a scan rate of 5 mV s −1 with 85.6% rate performance from 5 to 500 mV s −1 in 1 M KCl aqueous electrolyte. This outstanding capacitive performance of OPSF–24 h electrode can be attributed to the harmonious synergistic effect between the electric double-layer capacitive contribution of the PSF and the pseudocapacitive contribution of the oxygen-containing functional groups.

Supercapacitors have been attracting significant research interest because of their wide range of applications in electric vehicles, digital devices, pulsing techniques due to their high power density, short charging time, and long cycling life. For ideal charge/discharge mechanism, the micro/mesoporous silicon carbide flakes (SiCFs) with a high surface area of about 1376 m2 g−1 were obtained by one-step carbonization of waste Si wafer without any chemical or physical activation. The micropores are derived from the partial evaporation of Si atoms during the carbonization process and mesopores are formed by the integration of neighboring micropores. Two-electrode supercapacitor cells constructed with this silicon carbide yielded high values of gravimetric capacitance and energy density with aqueous and organic electrolytes. SiCF electrode carbonized at 1250 °C shows a high-charge storage capacity, with a specific capacitance of 49.2 F g−1 in 1 M KCl aqueous electrolyte at a scan rate of 5 mV s−1 (specific capacitance for the single electrode : 196.8 F g−1). In addition, a specific capacitance of 38.7 F g−1 is measured in 1 M 1-butyl-3-methyl-imidazolium tetrafluoroborate in acetonitrile (BMIM BF4/AN) organic electrolyte at a scan rate of 5 mV s−1 (specific capacitance for the single electrode: 154.8 F g−1), with an energy density of 65.84 W h kg−1; and ∼98.65% specific capacitance being retained over 20,000 cycles.

Hierarchical micro/mesoporous silicon carbide flakes (SiCF) with a high surface area of about 1376 m 2 g −1 are obtained by one-step carbonization of waste Si wafer without any chemical or physical activation. The micropores are derived from the partial evaporation of Si atoms during the carbonization process and mesopores are formed by the integration of neighboring micropores. During carbonization process, the proportion of micro and mesopores in SiCF can be controlled by carbonization time by controlling the amount of partial evaporation of Si atoms. The SiCF electrode carbonized for 8 h at 1250 °C exhibits high charge storage capacity with a specific capacitance of 203.7 F g −1 at a scan rate of 5 mV s −1 with 87.3% rate performance from 5 to 500 mV s −1 in 1 M KCl aqueous electrolyte. The outstanding electrochemical performance can be the synergistic effect of both enhanced electric double layer properties caused by micropores and reduced resistant pathways for ions diffusion in the pores as well as a large accessible surface area for ion transport/charge storage caused by mesopores. These encouraging results demonstrate that the SiCF carbonized for 8 h at 1250 °C can be promising candidate for high performance electrode materials for supercapacitors.

Three-dimensional silicon carbide-based frameworks with hierarchical micro- and mesoporous structures (2MSiC) are prepared by employing the template method and carbonization reaction using aerosol-spray drying. The mesopores are generated by the self-assembly of a structure-directing agent, whereas the micropores originate from the partial evaporation of Si atoms during the carbonization process. During the carbonization process, the proportion of micro- and mesopores in 2MSiC can be controlled by the carbonization temperature by controlling the amount of partial evaporation of Si atoms. The 2MSiC electrode prepared using a Brij56 structure-directing agent as the mesopore template and carbonized at 1250 °C exhibits a high charge storage capacity with a specific capacitance of 259.9 F g −1 at a scan rate of 5 mV s −1 with 88.1% rate performance from 5 to 500 mV s −1 in 1 M KCl aqueous electrolyte. This outstanding electrochemical performance can be attributed to the synergistic effect of both the enhanced electric double layer properties caused by micropores and reduced resistant pathways for ion diffusion in the pores as well as a large accessible surface area for ion transport/charge storage caused by mesopores. These encouraging results demonstrate that the 2MSiC electrode prepared with Brij56 and carbonized at 1250 °C is a promising candidate for high-performance electrode materials for supercapacitors.

Spherically aggregated boron nitride (BN) is advantageous for improving thermal conductivity. However, it is difficult to process due to its fragility and poor wettability. Herein we report coating boron nitride aggregates with polysilazane (PSZ) and three different silanes, glycidoxypropyltrimethoxysilane (GPTMS), aminopropyltriethoxysilane (APTES), and mercaptopropyltrimethoxysilane (MPTMS), via hydrolysis and condensation. The PSZ coating protected BN from external force, and the silane coatings enhanced interfacial adhesion between the filler and the matrix. An epoxy composite contained the BN surface modified with PSZ and APTES had the highest thermal conductivity of 11.8 W m−1 K−1 at a filler fraction of 75 wt%. Its thermal conductivity was 62 times higher than that of the neat epoxy.

Snake robots are composed of multiple links and joints and have a high degree of freedom. They can perform various motions and can overcome various terrains. Snake robots need additional driving algorithms and sensors that acquire terrain data in order to overcome rough terrains such as grasslands and slopes. In this study, we propose a driving assistant mechanism (DAM), which assists locomotion without additional driving algorithms and sensors. In this paper, we confirmed that the DAM prevents a roll down on a slope and increases the locomotion speed through dynamic simulation and experiments. It was possible to overcome grasslands and a 27 degrees slope without using additional driving controllers. In conclusion, we expect that a snake robot can conduct a wide range of missions well, such as exploring disaster sites and rough terrain, by using the proposed mechanism.

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) have been explored extensively for various energy conversion and storage system. Development of metal single atom doped well designed carbon substrates are considered as a new effective strategy to enhance catalytic activity and stability, and focused on as promising air cathode materials for metal-air battery. In this work, we report a novel method to fabricate cobalt (Co) single-atom species supported on porous carbon substrate using poly-(1,4-diethynylbenzene) (PDEB) chain as a new carbon substrate. Nitrogen doped PDEB chain combined with cobalt single-atom (Co-N-PDEB) shows excellent ORR and OER bifunctional catalytic performance with 1.08 V of oxygen electrode activity due to the synergistic effect between unique meso and macroporous carbon matrix with doped Co-N4 moiety. Finally, Co-N-PDEB air cathode adopted hybrid sodium (Na) air battery exhibits outstanding charge-discharge characteristics with low overpotential gap (0.296 V) and high round trip efficiency (91.02 %).

Hot embossing is in the spotlight due to the development of electronic devices, wearable devices, microfluidic channels, and optical devices. The conventional hot-embossing process creates a pattern on polymer film by using a previously patterned stamp that applied heat and pressure. This method has a disadvantage because it depends on the shape of the patterned stamp. For this reason, this method requires a high cost and a lot of time when replacing the stamp for making a new pattern shape or for modifying the error of the pattern. To solve this problem, the impact print-type hot-embossing method was proposed to create arbitrary patterns, and equipment for this method was assembled. In addition, patterning experiments were conducted to imprint several tens of micrometer-sized patterns in real time. For this method, we proposed an electromagnetic actuator for making the hot-embossing print type and for reducing the size of the actuator compared to previous studies. Through the patterning experiment, we determined that the proposed device could engrave fine dot patterns ranging from 60 &mu, m to 120 &mu, m in diameter. We verified the size of the generated pattern by using a confocal microscope, and we found the proposed hot-embossing technology can realize the desired shape in any position by using the proposed technique.

Graphene/Co(OH)₂ nanowire composite films were successfully synthesized using a simple three-step treatment, and the effect of the Co(OH)₂ nanowire content on the electrochemical properties of the composite films was studied in this study. One-dimensional Co(OH)₂ nanowires were homogeneously embedded and dispersed between the prepared graphene papers, forming a layered graphene/Co(OH)₂ nanowire hybrid structure. These composite films exhibited better electrochemical properties than the previously reported graphene composites with carbon spheres such as graphene/CNT composites. These graphene composites were fabricated using the same method we used in this study but without the addition of Co(OH)₂ nanowires. The addition of a small amount of Co(OH)₂ to reduced graphene oxide (rGO) (RGO:Co(OH)₂=5:1) yielded thick paper-like rGO/Co(OH)₂ sandwiches, which showed an excellent specific capacitance of 1032.57 Fg-1 at a scan rate of 5 mVs-1. These results indicate the potential of these composites for the development of highly capacitive energy storage devices for practical applications.

The development of bifunctional electrocatalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is essential for electrical energy storage systems (EES). Sodium–air (Na–air) batteries are emerging as a new type of EES, due to their high specific energy density and high sodium ion conductivity. However, the undesirable sluggish kinetics of the ORR and OER limit the practical production of rechargeable Na–air batteries. Although pyrochlore oxides (A2B2O7) exhibit great potential for highly-active bifunctional electrocatalysts, the lack of studies regarding A and B-site cations has hindered the development of new pyrochlore catalysts with a comprehensive understanding of the catalytic activity. Here, we demonstrate the use of a single crystalline thallium rhodium pyrochlore oxide (Tl2Rh2O7) as a highly efficient bifunctional electrocatalyst. The high catalytic activity of Tl2Rh2O7 can be attributed to the oxidation of Tl and Rh ions in Tl2Rh2O7 during the ORR and OER. The oxidized Tl and Rh ions can donate their electrons, which easily migrate to the surface and inner layers, following the low-resistance electron pathway during the electrocatalytic reaction. The hybrid Na–air batteries using the prepared Tl2Rh2O7 achieve greatly improved round-trip efficiency with a high power density for 50 cycles.

Currently, research on a jumping robot has been actively conducted in the Robotics field. In this paper, we propose a linkage structure of the jumping robot leg. The trajectory and take-off angle are simulated by using a free software, LINKAGE program. Also, we introduced the two types of the propulsion structure.

This paper proposes a model of the skin stiffness including the effect of the pressure of the radial artery, which is transmitted to the palpating doctor's hand. The transmitted stiffness is modeled with serially linked skin and radial artery stiffness. The stiffness of the radial artery comes from the inner pressure and stiffness of the artery wall. The relation between the stiffness and the inner pressure of the radial artery is experimentally determined. The proposed model is used to control the haptic interface of a training simulation of the radial artery palpation.

To achieve excellent photoelectrochemical water-splitting activity, photoanode materials with high light absorption and good charge-separation efficiency are essential. One effective strategy for the production of materials satisfying these requirements is to adjust their band structure and corresponding bandgap energy by introducing oxygen vacancies. A simple chemical reduction method that can systematically generate oxygen vacancies in barium stannate (BaSnO3 (BSO)) crystal is introduced, which thus allows for precise control of the bandgap energy. A BSO photoanode with optimum oxygen-vacancy concentration (8.7%) exhibits high light-absorption and good charge-separation capabilities. After deposition of FeOOH/NiOOH oxygen evolution cocatalysts on its surface, this photoanode shows a remarkable photocurrent density of 7.32 mA cm-2 at a potential of 1.23 V versus a reversible hydrogen electrode under AM1.5G simulated sunlight. Moreover, a tandem device constructed with a perovskite solar cell exhibits an operating photocurrent density of 6.84 mA cm-2 and stable gas production with an average solar-to-hydrogen conversion efficiency of 7.92% for 100 h, thus functioning as an outstanding unbiased water-splitting system.

It is crucial for leaping forward renewable energy technology to develop highly active oxygen evolution reaction (OER) catalysts with fast OER kinetics, and the novel design of high-performance catalysts may come down to unveiling the origin of high catalytic behavior. Herein, a new class of heterogeneous OER electrocatalyst (metallic Co nanoparticles anchored on yttrium ruthenate pyrochlore oxide) is provided for securing fast OER kinetics. In situ X-ray absorption spectroscopy (in situ XAS) reveals that fast OER kinetics can be achieved by the harmonious catalytic synergy of a pyrochlore oxide support to Co nanoparticles. By the facile oxidation of yttrium (A-site) and ruthenium (B-site) cations, the pyrochlore oxide support helps to expel the electrons generated from the catalytic behavior of Co to the inner layers of the support, facilitating the electrostatic adsorption of OH- ions and reducing the barrier energy for the formation of CoOOH intermediates. This work affords the rational design of transition metal nanoparticles anchored on pyrochlore oxide heterogeneous catalysts and the fundamental insight of catalytic origin associated with self-reconstruction of OER electrocatalysts.

Recently, attention has been focused on the synthesis and application of nanocomposites for supercapacitors, which can have superior electrochemical performance than single structured materials. Here, we report a carbon-coated TiO2/Co3O4 ternary hybrid nanocomposite (TiO2@C/Co) electrode for supercapacitors. A carbon layer was directly introduced onto the TiO2 surface via thermal vapor deposition. The carbon layer provides anchoring sites for the deposition of Co3O4, which was introduced onto the carbon-coated TiO2 surface by hydrazine and the thermal oxidation method. The TiO2@C/Co electrode exhibits much higher charge storage capacity relative to pristine TiO2, carbon-coated TiO2, and pristine Co3O4, showing a specific capacitance of 392.4 F g(-1) at a scan rate of 5 mV s(-1) with 76.2% rate performance from 5 to 500 mV s(-1) in 1 M KOH aqueous solution electrolyte. This outstanding electrochemical performance can be attributed to the high conductivity and high pseudo-capacitive contributions of the nanoscale particles. To evaluate the capacitive performance of a supercapacitor device employing the TiO2@C/Co electrode, we have successfully assembled TiO2@C/Co//activated carbon (AC) asymmetric supercapacitors. The optimized TiO2@C/Co//AC supercapacitor could be cycled reversibly in the voltage range from 0 to 1.5 V, and it exhibits a specific capacitance of 59.35 F g(-1) at a scan rate of 5 mV s(-1) with a specific capacitance loss of 15.4% after 5000 charge-discharge cycles. These encouraging results show great potential in terms of developing high-capacitive energy storage devices for practical applications.

In this work, a three-dimensional hierarchical carbon framework/Co3O4 hybrid composite was fabricated. The three-dimensional hierarchical carbon framework was constructed by thermal vapor deposition on the silica nanosphere templates and etching these templates. The resulting carbon framework was activated using phosphoric acid to control its surface area and porosity. The degree of activation of the carbon framework was optimized by measuring the specific capacitance. The carbon framework electrode activated with 3 M phosphoric acid (HCCA(3)) exhibited the highest specific capacitance (134 F g(-1) at 10 mV s(-1)). Subsequently, Co3O4 was formed on the carbon framework via the hydrothermal method. The resulting product HCCA(3)/Co3O4 showed a dramatic enhancement in the specific capacitance (456 F g(-1) at 1 A g(-1)) compared with the pristine Co3O4 and HCCA(3) electrodes. The proposed HCCA(3)/Co3O4 composite can be used for the fabrication of high-performance electrodes.

Oxygen-containing functional groups were introduced onto the surface of the micro- and meso-porous silicon carbide sphere (MMPSiC) in order to investigate the relationship between the electric double layer properties and pseudo-capacitive properties; the degree of oxidation of MMPSiC was also optimized. Although the oxygenated surface functionalities can lead to a decrease in the surface area of MMPSiC, the oxygen functional groups attached to the external surface can participate in the redox reaction, resulting in the enhancement of the total super-capacitive performance. The MMPSiC electrode oxidized for 24 h exhibits a high charge storage capacity with a specific capacitance of 301.1 F g(-1) at a scan rate of 5 mV s(-1), with 86.8% rate performance from 5 to 500 mV s(-1) in 1 M KCl aqueous electrolyte. This outstanding capacitive performance of the MMPSiC electrode oxidized for 24 h can be attributed to the harmonious synergistic effect between the electric double layer capacitive contribution of MMPSiC and the pseudo-capacitive contribution of the oxygen-containing functional groups. These encouraging results demonstrate that the MMPSiC electrode oxidized for 24 h is a promising candidate for high performance electrode materials for supercapacitors.

Composites of micro- and mesoporous SiC flakes (SiCF) and ferroferric oxide (Fe3O4), SiCF/Fe3O4, were prepared via the chemical deposition of Fe3O4 on SiCF by the chemical reduction of an Fe precursor. The SiCF/Fe3O4 electrodes were fabricated at different Fe3O4 feeding ratios to determine the optimal Fe3O4 content that can maintain a high total surface area of SiCF/Fe3O4 composites as well as cause a vigorous redox reaction, thereby maximizing the synergistic effect between the electric double-layer capacitive effects of SiCF and the pseudo-capacitive effects of Fe3O4. The SiCF/Fe3O4 electrode fabricated with a Fe3O4/SiCF feeding ratio of 1.5:1 (SiCF/Fe3O4(1.5)) exhibited the highest charge storage capacity, showing a specific capacitance of 423.2 F g-1 at a scan rate of 5 mV s-1 with a rate performance of 81.8% from 5 to 500 mV s-1 in an aqueous 1 M KOH electrolyte. The outstanding capacitive performance of the SiCF/Fe3O4(1.5) electrode could be attributed to the harmonious synergistic effect between the electric double-layer capacitive contribution of the SiCF and the pseudocapacitive contribution of the Fe3O4 nanoparticles introduced on the SiCF surface. These encouraging results demonstrate that the SiCF/Fe3O4(1.5) electrode is a promising high-performance electrode material for use in supercapacitors.