Ammonia Cracking Catalyzed by Ni Nanoparticles Confined in the Framework of CeO2 Support

For the extraction of hydrogen from ammonia at low temperatures, we investigated Ni-based catalysts fabricated by the thermal decomposition of RNi5 intermetallics (R = Ce or Y). The interconnected microstructure formed via phase separation between the Ni catalyst and the resulting oxide support was observed to evolve via low-temperature thermal decomposition of RNi5. The resulting Ni/CeO2 nanocomposite exhibited superior catalytic activity of ∼25% at 400 °C for NH3 cracking. The high catalytic activity was attributed to the interlocking of Ni nanoparticles with the CeO2 framework. The growth of Ni nanoparticles was prevented by this interconnected microstructure, in which the Ni nanoparticles incorporated nitrogen owing to the size effect, whereas Ni does not commonly form nitrides. To the best of our knowledge, this is a unique example of a microstructure that enhances catalytic NH3 cracking.

Unique Conduction Band Minimum of Semiconductors Possessing a Zincblende-Type Framework

Tetrahedral semiconductors such as Si adopt a diamond-type crystal structure with low packing density arising from open cavities in the crystallographic space. By taking LiAlGe as an example, we propose a zincblende-type framework as a platform for semiconductors possessing electroactive cavities. LiAlGe adopts a half-Heusler-type crystal structure including an ordered diamond-type sublattice (zincblende-type) (AlGe) and is an indirect semiconductor with a band gap of ∼0.1 eV. The conduction band minimum (CBM) is uniquely located at the cavity space surrounded by four cations (Al₄) in real space. The bond ionicity and cation (Al) p orbitals located around the Fermi energy are requisite for the CBM to float in the cavity space. DFT calculations indicate the conversion of the semiconductor to a semimetallic electride under a pressure of ∼8 GPa, which is accompanied by band gap collapse due to electron transfer from valence band maximum to the cavity space. The high-pressure electride of LiAlGe formed under a very small critical pressure is derived from the presence of inherent crystallographic cavities having deep orbital levels energetically. This finding suggests the possible utilization of electroactive cavity spaces in tetrahedral semiconductors, which are widely used in modern electronic devices.

Superior catalytic performance of intermetallic CaPt2 nanoparticles supported on titanium group oxides in hydrogenation of ketones to alcohols

Intermetallic CaPt₂ nanoparticles, supported on titanium group oxides, were prepared using a molten salt method with CaH₂ as both the reducing agent and the calcium source. The nanoparticles exhibited superior catalytic activity compared to a commercial Pt/C catalyst in the hydrogenation of ketones to alcohols, which could be promoted by electron-rich Pt sites in CaPt₂.

Intermetallic YIr2 nanoparticles with negatively charged Ir active sites for catalytic hydrogenation of cyclohexanone to cyclohexanol

Negatively charged iridium species in Laves phase YIr2 as highly active sites for hydrogenation of cyclohexanone to cyclohexanol.

Chemical route to prepare nickel supported on intermetallic Ti6Si7Ni16 nanoparticles catalyzing CO methanation

In this study, ternary intermetallic nickel silicide, Ti₆Si₇Ni₁₆, nanoparticles with a high surface area of 37.5 m² g^-1 were chemically prepared from SiO₂-impregnated oxide precursors, which were reduced at as low as 600 °C by a CaH₂ reducing agent in molten LiCl, resulting in the formation of single-phase Ti₆Si₇Ni₁₆ with a nanosized morphology. The intermetallic Ti₆Si₇Ni₁₆ phase in the nanoparticles was stabilized in air by surface passive oxide layers of TiO_x-SiO_y, which facilitated the handling of the nanoparticles. Considering our previous successful work of preparing single-phase LaNi₂Si₂ (39.3 m² g^-1) and YNi₂Si₂ (27.0 m² g^-1) nanoparticles in a similar manner, the proposed chemical method showed to be a versatile approach in preparing ternary silicide nanoparticles. In this study, we applied the obtained Ti₆Si₇Ni₁₆ nanoparticles as catalyst supports in CO methanation. The supported nickel catalyst showed an activation energy of 56 kJ mol^-1, which is half as low as that of common TiO₂-supported nickel catalysts. Also, Ni/Ti₆Si₇Ni₁₆ provided the lower activation energy more than any previous Ni-based catalyst. Since the measured work function of Ti₆Si₇Ni₁₆ (4.5 eV) was lower than that of nickel (5.15 eV), it was suggested that the Ti₆Si₇Ni₁₆ support can accelerate the rate-determining step of C-O bond dissociation in CO methanation due to its good electron donation capacity.

A View on Formation Gap in Transition Metal Hydrides and Its Collapse

Late transition metals (LTMs) do not form hydrides under conventional experimental conditions except for palladium (Pd). The incorporation of a small amount of metal with low electronegativity converts LTMs into hydrogen (H) storage intermetallics (IMs) such as LaNi₅. We examined the critical property of the H absorbing ability of LTMs and found that the lattice softness of Pd is a unique parameter for H insertion. This idea is applicable to H storage IMs. Indeed, negatively charged LTM ions, such as Ni^δ- in LaNi₅, play a crucial role in hydrogenation. These ions cause lattice softening, which renders H solution possible. As a result, we propose that lattice softness can be an effective criterion for the development of new H storage IMs.

Twinning by Merohedry and Thermal Expansion of Zeolitic Clathrasil Deca-dodecasil 3R

Rhombohedral crystal particles of zeolitic clathrasil deca-dodecasil 3R (DDR), hydrothermally synthesized from a mixture consisting of fumed silica, water, and 1-adamantanamine, were characterized by single-crystal and powder X-ray diffractometry as a function of temperature and pole figure analysis. The crystallite was bounded by six equivalent {101̅1} faces and exhibited twin-free appearance, whereas the structure was resolved with the binary twin by merohedry, defined by the twin point group 3̅2'/m'1, consisting of two twin domains with nearly equal volume fractions. This twinning modifies the positions of O atoms in the Si-O-Si framework while preserving the positions of Si atoms that define the topology of polyhedral cages. This type of twinning therefore does not disrupt the microporous channels via the 8-membered rings of the 19-hedral cages and little disturbs the adsorption and permeation of gas molecules in DDR. The cell volume of DDR increased monotonically with an increase in temperature up to ∼673 K accompanied by an elongation perpendicular to the [0001] axis and a shrinkage along the [0001] axis. Above ∼673 K, the cell volume decreased with temperature. These positive and negative volume expansion coefficients observed in this study were roughly one-half and one-third of the values currently available.

On the Origin of the Negative Thermal Expansion Behavior of YCu

Among the intermetallics and alloys, YCu is an unusual material because it displays negative thermal expansion without spin ordering. The mechanism behind this behavior that is caused by the structural phase transition of YCu has yet to be fully understood. To gain insight into this mechanism, we experimentally examined the crystal structure of the low-temperature phase of YCu and discuss the origin of the phase transition with the aid of thermodynamics calculations. The result shows that the high-temperature (cubic CsCl-type) to low-temperature (orthorhombic FeB-type) structural phase transition is driven by the rearrangement of three covalent bonds, namely, Y-Cu, Y-Y, and Cu-Cu, which compete for the bonding energy and phonon entropy. At low temperatures, the mixing of Y and Cu does not take place easily because of the weak attractive force between these atoms expected from the small negative mixing enthalpy. This causes all three interactions to take part in the bonding, and Y and Cu are segregated to form an FeB-type structure, which is stabilized by internal energy. At higher temperatures, Cu ions are bound loosely with Y ions due to the large Y-Cu distance (3.01 Å), which results in large vibration entropy and stabilizes a CsCl-type crystal structure. In addition, the CsCl-type structure is reinforced by the Y-Y interaction between next-nearest neighbors, resulting in a smaller unit cell volume. The crystal structure has the simple cubic framework of Y containing Cu ions bound loosely at the cavity sites. The calculated frequency of the Y-like phonon modes is much higher than that of the Cu-like modes, indicating the presence of Y-Y covalent interactions in the CsCl-type phase.

Implementation and Evaluation of a Wide-Range Human-Sensing System Based on Cooperating Multiple Range Image Sensors

A museum is an important place for science education for children. The learning method in the museum is reading exhibits and explanations. Museums are investing efforts to quantify interests using questionnaires and sensors to improve their exhibitions and explanations. Therefore, even in places where many people gather, such as in museums, it is necessary to quantify people's interest by sensing behavior of multiple people. However, this has not yet been realized. We aim to quantify the interest by sensing a wide range of human behavior for multiple people by coordinating multiple noncontact sensors. When coordinating multiple sensors, the coordinates and the time of each sensor differ. To solve these problems, coordinates were transformed using a simultaneous transformation matrix and time synchronization was performed using unified time. The effectiveness of this proposal was verified through experimental evaluation. Furthermore, we evaluated the actual museum content. In this paper, we describe the proposed method and the results of the evaluation experiment.

Transformation of the Chromium Coordination Environment in LaCrAsO Induced by Hydride Doping: Formation of La2Cr2As2OyHx

We report the synthesis of La₂Cr₂As₂O_yH_x (0.1 < y < 1.6) oxyhydride solid solutions using a solid-state reaction under high pressure with a solid-state hydrogen source and exhibit an example of how H^- doping can also promote structural changes: H^- doping in LaCrAsO results in the formation of La₂Cr₂As₂O_yH_x with the La₂Fe₂Se₂O₃-type layered structure. Remarkably, this transformation includes a change of the coordination number of Cr from 4 to 6, with the some of the H^- being accommodated in new sites within the CrAs layers. In this way, H^- not only serves as a conventional electron dopant by the substitution of O^2- but also makes new bonds to the transition metals.

Cubic Fluorite-Type CaH2 with a Small Bandgap

A cubic variant of CaH₂ adopting a fluorite-type crystal structure was synthesized by cationic substitution with La or Y, yielding the first alkaline earth hydride-based with fluorite-type framework. The material has a bandgap of ∼2.5 eV (greenish yellow in color), which is much smaller than that of orthorhombic PbCl₂-type CaH₂ (4.4 eV) and is, in fact, the smallest among alkaline or alkaline earth metal hydrides reported to date. Analysis of the density functional theory band structure of cubic-CaH₂ indicates that its conduction band minimum is formed mainly by the interaction between the Ca 3d e_g orbitals around the crystallographic cavity defined by cubes of H^- ions. The use of such cavities in the creation of low-lying conduction band minima by semiconductors is extremely rare, and has similarities to inorganic electrides.

The Unique Electronic Structure of Mg2 Si: Shaping the Conduction Bands of Semiconductors with Multicenter Bonding

The electronic structures of the antifluorite-type compound Mg₂ Si is described in which a sublattice of short cation-cation contacts creates a very low conduction band minimum. Since Mg₂ Si shows n-type conductivity without intentional carrier doping, the present result indicates that the cage defined by the cations plays critical roles in carrier transport similar to those of inorganic electrides, such as 12 CaO⋅7 Al₂ O₃ :e^- and Ca₂ N. A distinct difference in the location of conduction band minimum between Mg₂ Si and the isostructural phase Na₂ S is explained in terms of factors such as the differing interaction strengths of the Si/S 3s orbitals with the cation levels, with the more core-like character of the S 3s leading to a relatively low conduction band energy at the Γ point. Based on these results and previous research on electrides, approaches can be devised to control the energy levels of cation sublattices in semiconductors.

Design and Control of a Wearable Stewart Platform-Type Ankle-Foot Assistive Device

The design and control of an active ankle-foot rehabilitation orthotic system that was designed as a wearable and portable rehabilitation and walking assistive tool is presented. This device can measure and assist the six degree of freedoms (DOFs) movement of the human ankle joint by using a Stewart platform mechanism, which can adapt to the displacement of the rotation axis during the movement of a human foot. The estimation method of an instantaneous rotation axis of ankle-foot motion is also proposed. In this paper, the motion measurement and motion control performance of the developed assistive device is evaluated. Static and dynamic motion measurement and motion reproduction performance verification experiments are conducted. The experimental results showed that the developed assistive device is enough for measuring and controlling the human ankle-foot motion.

Six-axis orthodontic force and moment sensing system for dentist technique training

The purpose of this study is to develop a sensing system device that measures three-axis orthodontic forces and three-axis orthodontic moments for dentist training. The developed sensing system is composed of six-axis force sensors, action sticks, sliders, and tooth models. The developed system also simulates various types of tooth row shape patterns in orthodontic operations, and measures a 14 × 6 axis orthodontic force and moment from tooth models simultaneously. The average force and moment error per loaded axis were 2.06 % and 2.00 %, respectively.

Measurement of the passive stiffness of ankle joint in 3 DOF using stewart platform type ankle foot device

This paper presents a method to measure the passive stiffness of an ankle joint in three degrees of freedom (DOF) under two motion speeds (1 Hz and 5 degree/s) using a developed Stewart platform-type device. The developed device can reproduce input motions of the foot in 6 DOF by controlling six pneumatic linear motion actuators. We used the device to measure the passive stiffness of an ankle joint undergoing three kinds of motion, namely dorsi-plantar flexion, inversion-eversion, and adduction-abduction. The measured values of the passive stiffness of the ankle joint in dorsiflexion that we obtained agreed well with that obtained in a previous study, indicating that the developed device is useful for measuring the passive stiffness of ankle joint. In addition, the developed device can be used to measure the stiffness in inversion-eversion and adduction-abduction motions as well, parameters that have never been measured. The results we obtained demonstrated certain interesting features as we varied both the direction and pace of motion (e.g., there were significant differences in the stiffness not only between adduction and abduction during the faster pace, but also between these and the other motions).

Development of Six-DOF Human Ankle Motion Control Device Using Stewart Platform Structure for Fall Prevention

[abstFig src='/00280005/06.jpg' width='300' text='Developed device' ] According to a worldwide WHO survey, about one-third of people at the age of 65 or older experience at least one fall a year, which may result in a severe injury. Meanwhile, the population of the developed world is increasingly aging, and fall incidents can be therefore considered as a global problem. The causes of falls include the weakening of the tibialis anterior and gastrocnemius muscles that respectively play important roles in the dorsal and plantar flexion of the foot, and deterioration of the functions necessary to recover balance from perturbations during gait. Such dysfunctions are treated with rehabilitation provided by physical therapists and with special gait training in which the patient is subjected to perturbations. Although devices for rehabilitation and gait training have been developed, they are problematic since they only allow the ankle joint to move at a low number of degrees of freedom (DOF). In this study, we developed an ankle foot orthosis to provide six-DOF control of the ankle joint using a parallel link mechanism known as a Stewart platform. The Stewart platform construction makes it possible to provide six-DOF control. Since the ankle foot orthosis can be applied to walking, it can assist walking or gait training. In one of our prior studies, we proposed a force control method for the device, and verified its accuracy. In the present study, we improved the attachment method and introduced a pressure sensor to the previous version of the device to allow implementation of a new method that enables control adapted to the human gait. In addition, we conducted four experiments to verify whether it is possible to reproduce the physical therapist’s rehabilitation manipulations without limiting the ankle joint’s DOF, provide arbitrary walking assist action, and impart perturbations to the subject during gait. The first experiment verified the device’s accuracy in reproducing motion, the second confirmed the dispersion of the reproduced motion, the third assessed the walking-assist performance to prevent trips, and the fourth ascertained whether it is possible to make the subject lose balance by the imparted perturbation. The results demonstrated that the motions can be reproduced with high accuracy and with low dispersion and that the ankle joint motions can be controlled adaptively to fit the subject’s gait, suggesting the usefulness of the proposed device.

The role of oxidative damage in poor scalp health: ramifications to causality and associated hair growth

The oxidative stress element of unhealthy scalp leads to compromised pre-emergent hair formation and poorly formed hair as it grows. Only cosmetic solutions can minimize the impact of unhealthy hair and to achieve healthy looking and feeling hair, the scalp health must be normalized first. The objectives of this research were to both investigate whether oxidative stress was a relevant aetiological element in scalp dandruff and seborrhoeic dermatitis and whether scalp condition affects the quality of hair that grows from it. Further, this research was designed to determine whether an effective anti-dandruff shampoo would repair and protect the scalp and pre-emergent hair from oxidative stress. This study demonstrated that oxidative stress is an aetiological element relevant to the dandruff condition and that a potentiated ZPT shampoo effectively improves scalp condition, including a reduction in oxidative stress. The compromised hair condition associated with dandruff is concomitantly improved when the scalp condition is improved. It appears that there is a direct link between hair quality and scalp health.

Dental plaque assessment lifelogging system using commercial camera for oral healthcare

We present a system for estimating the dental plaque adhesion area using a commercial camera image for oral healthcare via management of the intraoral environment. In recent years, several studies have reported on the relationship between a general disease and a periodontal disease. Such studies mention that normalization of the intraoral environment by tooth brushing is the most important treatment in preventive dentistry. However, evaluation of individual tooth brushing skill is difficult. Some devices for automatically measuring the quantity of dental plaque have already been proposed for the teaching tool of tooth brushing. However, these devices have certain limitations, such as large size, requirement to fix the head position, and limited applicability in daily life. In this study, we propose a method for calculating the dental plaque adhesion area using a commercial camera and an intraoral camera. We also propose an evaluation method for the quantity of adhered dental plaque for replacing the Plaque Control Record (PCR). The relationship between PCR of the front teeth and that of all teeth was investigated by using the proposed method. The experimental results show that the proposed method can estimate the PCR of all teeth from the information of the front tooth. This method is not dependent on a particular camera system, and is applicable with many types of cameras, including smartphones. Therefore, it will be a useful tool in daily use for routine and sustainable management of the intraoral environment.

Development of Stewart platform type ankle-foot device for trip prevention support

This paper presents an ankle-foot device using a Stewart platform, which is a type of parallel-link mechanism, for trip prevention support. The developed device can reproduce the input motions of the ankle joint in six degrees of freedom by controlling six pneumatic cylinders at the same time. The root mean square errors of the 3-D position and rotation angle of the reproduced motions with the input motions (dorsiflexion and plantar flexion) were 6.3 mm and 3.0°, respectively. Verification experiments for trip prevention support performance were conducted by comparing motions in each walking condition measured using a motion capture system. The experimental results showed that the minimum foot clearance during mid-swing and initial swing increased significantly by the trip prevention support offered by the developed device. The developed device can perform passive exercises for ankle rehabilitation and support walking for trip prevention.

Evaluation of venous return in lower limb by passive ankle exercise performed by PHARAD

This paper presents evaluation of venous return, i.e., blood flow volume of vein (BF), in the lower limb after passive exercise performed by our developed "parallel link type human ankle rehabilitation assistive device (PHARAD)". The PHARAD can perform complex passive exercises (plantar flexion/dorsiflexion, inversion/eversion, adduction/abduction, and combination of these motions) by reproducing input motions of a foot plate that is attached to a sole of foot. The passive exercise can be performed for not only rehabilitation but also prevention of deep vein thrombosis (DVT). In this study, we measured the concentration of Total hemoglobin (Total-Hb) using multi-channel near infra-red spectroscopy (NIRS)-based tissue oximeters and calculated a gradient of Total-Hb during a venous occlusion. We defined the gradient as BF and evaluated BF after 3 min passive exercise performed by the PHARAD comparing to BF of resting. Seven healthy young adult people were recruited for the experiment and we assessed passive exercise, active exercise, and walking. Experimental results show that BF after the passive exercises significantly increases compare to BF of resting and this indicates that passive exercises performed by the PHARAD increases BF and has a potential to prevent DVT.

Support system for pathologists and researchers

Aims:

In Japan, cancer is the most prevalent cause of death; the number of patients suffering from cancer is increasing. Hence, there is an increased burden on pathologists to make diagnoses. To reduce pathologists’ burden, researchers have developed methods of auto-pathological diagnosis. However, virtual slides, which are created when glass slides are digitally scanned, saved in a unique format, and it is difficult for researchers to work on the virtual slides for developing their own image processing method. This paper presents the support system for pathologists and researchers who use auto-pathological diagnosis (P-SSD). Main purpose of P-SSD was to support both of pathologists and researchers. P-SSD consists of several sub-functions that make it easy not only for pathologists to screen pathological images, double-check their diagnoses, and reduce unimportant image data but also for researchers to develop and apply their original image-processing techniques to pathological images.

Methods:

We originally developed P-SSD to support both pathologists and researchers developing auto-pathological diagnoses systems. Current version of P-SSD consists of five main functions as follows: (i) Loading virtual slides, (ii) making a supervised database, (iii) learning image features, (iv) detecting cancerous areas, (v) displaying results of detection.

Results:

P-SSD reduces computer memory size random access memory utilization and the processing time required to divide the virtual slides into the smaller-size images compared with other similar software. The maximum observed reduction in computer memory size and reduction in processing time is 97% and 99.94%, respectively.

Conclusions:

Unlike other vendor-developed software, P-SSD has interoperability and is capable of handling virtual slides in several formats. Therefore, P-SSD can support both of pathologists and researchers, and has many potential applications in both pathological diagnosis and research area.

An anti CuO2-type metal hydride square net structure in Ln2M2As2H(x) (Ln=La or Sm, M=Ti, V, Cr, or Mn)

Using a high pressure technique and the strong donating nature of H(-), a new series of tetragonal La2Fe2Se2O3-type layered mixed-anion arsenides, Ln2M2As2H(x), was synthesized (Ln=La or Sm, M=Ti, V, Cr, or Mn; x≈3). In these compounds, an unusual M2H square net, which has anti CuO2 square net structures accompanying two As(3-) ions, is sandwiched by (LaH)2 fluorite layers. Notably, strong metal-metal bonding with a distance of 2.80 Å was confirmed in La2Ti2As2H2.3, which has metallic properties. In fact, these compounds are situated near the boundary between salt-like ionic hydrides and transition-metal hydrides with metallic characters.

Development of three-dimensional motion measuring device for the human ankle joint by using parallel link mechanism

This paper presents a novel ankle motion measuring device that can measure three-dimensional motions without a motion capture system (MCS). We adapted a parallel link mechanism for the device using six wire-type displacement sensors to measure the ankle joint motions in six degrees of freedom (six-DOF). We define the motions of a foot plate which is attached to a foot sole as ankle joint motions. A posture of the foot plate, i.e., the three-dimensional position (x, y, z) and rotation angle (θ, Φ, ψ), is numerically calculated by solving the forward kinematics of the developed device. We conducted performance verification experiments of the developed device by comparing these results with those of the MCS. The experimental results show that the maximum root mean square error of the three-dimensional position and rotation angle measured by the developed device are 2.6 mm and 1.5°, respectively. This measuring performance of the developed device indicates that the ankle motion measuring device is accurate and valid. Moreover, this device enables physical therapists to easily measure ankle motions with an accuracy as high as that of an MCS.

New LaMAsH(x) (M = Co, Ni, or Cu) arsenides with covalent M-H chains

A new series of tetragonal LaPtSi-type mixed-anion arsenides, LaMAsH(x) (M = Co, Ni, or Cu), has been synthesized using high-temperature and high-pressure techniques. The crystal structure of these intermetallic compounds determined via powder neutron diffraction is composed of a 3D framework of three connected planes with the La ions filling the cavities in the structure. Each late transition-metal ion M, all of which have relatively large electronegativities, behaves like a main group element and forms a planar coordination configuration with three As ions. The trigonal-bipyramidal coordination adopted by the H in the cavity, HM2La3, is compressed along the C3 axis, and unusual M-H chains run along the x and y directions, reinforcing the covalent framework. These chains, which are unique in solids, are stabilized by covalent interactions between the M 4s and H 1s orbitals.

Enhancement of Plantar Tactile Sensitivity by Wearable Stabilization Device Based on Stochastic Resonance for Fall Prevention

This article reports on the results of experiments that involved the use of a wearable sensorimotor enhancement device for preventing falls. The brief exposure of the tactile receptors to sub-sensory vibration is known to enhance tactile sensitivity, a phenomenon called “stochastic resonance” (SR) in the somatosensory system. Applying white-noise vibration to a tarsal tunnel is thus expected to improve plantar tactile sensitivity and improve the stability of the standing posture and gait. A prototype of a wearable device is proposed as part of this research. Eleven healthy young subjects (22.6±0.6 years old) were recruited for the plantar tactile enhanced test. Twenty-one healthy elderly subjects (73.3±4.6 years old) were recruited for the standing posture stabilization and gait tests. The elderly subjects were separated into two groups, one being a high-sensitivity group, and the other being a low-sensitivity group. The plantar tactile sensitivity of the healthy young subjects was found to be significantly increased in the plantar tactile enhanced test (p < 0.05). The total sway length (p < 0.05), lateral range (p < 0.05), velocity variability (p < 0.05), lateral velocity variability (p < 0.05), and lateral acceleration variability (p < 0.05) of COP in the standing posture stabilizing test were found to be significantly lower in the elderly subjects when using the prototype device. The step length in the gait test with the device was significantly increased in the high-sensitivity elderly group (p < 0.05). The results of the plantar tactile enhanced test showed that the mechanical vibration noise applied to the tarsal tunnel by the developed prototype device can enhance the plantar tactile sensitivity. The results of the standing posture stabilizing test and the gait test showed that the device can improve the static and dynamic balance control ability of the elderly subjects. These results suggest that the proposed device offers the potential of reducing the risk of fall accidents among the elderly.

Force, Stiffness and Viscous Damping Control of a Stewart-Platform-Type Ankle-Foot Rehabilitation Assist Device with Pneumatic Actuator

The number of physically disabled people in need of rehabilitation is increasing. Unfortunately, there is a shortage of physical therapists specializing in such rehabilitation. This has increased the demand for rehabilitation assist devices that can lessen the burden of physical therapists. In this study, the authors develop a device that can assist in the rehabilitation of the ankle joint by employing a Stewart-platform (SP)-type parallel-link mechanism. With the SP-type parallel-link mechanism, it is possible to measure and control six degrees-of-freedom (DOFs) of ankle-foot movement during rehabilitation. Because the device enables the measurements of the ankle and foot, it is possible to calculate the instantaneous center of the ankle joint. In previous studies, the authors proposed methods to calculate and control the posture of the ankle and foot by an SP-type parallel-link mechanism and verified their accuracy. In this paper, the authors propose a method for force control using the device and also verify its accuracy. Using this device, the force acting on the ankle-foot can be controlled by six air cylinders. The force produced by a single air cylinder is determined by controlling the pressures in the extension and retraction directions. The accuracy of the force control method is verified for a single air cylinder and for the assist device when all six air cylinders are engaged. Results show that the accuracy of the single air cylinder has a mean square error of 0.24 N or less, while those for force control of the entire device are 4.2 N or less for parallel translation and 3.2 Nm or less for rotation. This demonstrates a satisfactory accuracy. To incorporate rehabilitation assistance by means of stiffness or viscous damping in the future, the authors also propose methods to control the coefficients of stiffness and viscous damping of the air cylinder and verify their accuracy. The mean square errors for the accuracies in controlling the coefficients of stiffness and viscous damping are 3.4 N/m and 1.4 Ns/m, respectively, thus verifying the validity of the proposed methods.

Magnetic structure and electromagnetic properties of LnCrAsO with a ZrCuSiAs-type structure (Ln = La, Ce, Pr, and Nd)

We report the synthesis, structure, and electromagnetic properties of Cr-based layered oxyarsenides LnCrAsO (Ln = La, Ce, Pr, and Nd) with a ZrCuSiAs-type structure. All LnCrAsO samples showed metallic electronic conduction. Electron doping in LaCrAsO by Mn-substitution for the Cr sites gave rise to a metal-insulator transition. Analysis of powder neutron diffraction data revealed that LaCrAsO had G-type antiferromagnetic (AFM) ordering, i.e., a checkerboard-type AFM ordering in the CrAs plane and antiparallel spin coupling between the adjacent CrAs planes, at 300 K with a large spin moment of 1.57 μB along the c axis. The magnetic susceptibility of LaCrAsO was very small (on the order of 10(-3) emu/mol) and showed a broad hump at ∼550 K. First-principles density functional theory calculations of LaCrAsO explained its crystal structure and metallic nature well, but could not replicate the antiparallel spin coupling between the CrAs layers. The electronic structure of LaCrAsO is discussed with regard to those of related compounds LaFeAsO and LaMnAsO.

Development of childhood fall motion database and browser based on behavior measurements

This paper describes the development of a fall motion database and a browser designed to facilitate investigations into fall-related injury risk. First, child-related daily activities were collected at a "sensor home", which is a model of a normal living environment equipped with an embedded video-surveillance system and within which child test subjects were equipped with wearable acceleration-gyro sensors. As of this report, measurements have been conducted for 19 children (months age: mean=23.8, standard deviation=10.5), and data has been obtained on 105 fall incidents. During our research, falls were detected from the accumulated sensor data using a detection algorithm developed by the authors, and then video clips of detected falls were extracted from the recorded video streams automatically. The extracted video clips were then used for fall motion analysis. A computer vision (CV) algorithm, which was developed to automate fall motion analysis, facilitates accumulation of fall motion data into the abovementioned database, and the associated database browser allows users to perform conditional searches of fall data by inputting search conditions, such as child attributes and specific fall situations. Before this study, there was no database which contains child's actual fall motion data, and it has the potential to facilitate injury risk reduction related to falls in daily living environments.

Integration of Ultrasonic Sensors and Kinect Sensors for People Distinction and 3D Localization

The method proposed here for 3D position measurement and identification of individuals by integrating ultrasonic and Kinect sensors uses ultrasonic transmitter tags with unique identifiers. Ultrasonic sensors measure the 3D positions of and identify tagged individuals, but cannot make measurements if there are no receivers in the direction of ultrasonic waves from transmitters. Kinect sensors measure 3D positions of individuals and track them with OpenNI, but Kinect sensors cannot make measurements if occlusion occurs due to the overlapping of individuals. Evaluation results show that the method proposed here is more robust than methods only using either ultrasonic or Kinect sensors.

Superconductivity in defective pyrite-type iridium chalcogenides Ir(x)Ch2 Ch = Se and Te

We report superconductivity in defective pyrite-type iridium chalcogenides Ir(x)Ch2 (Ch = Se and Te). Maximum values of T(c) of 6.4 K for Ir(0.91)Se(2) and 4.7 K for Ir(0.93)Te(2) were observed. It was found that Ir(0.75)Ch(2) (Ir(3)Ch(8)) is close to the boundary between metallic and insulating states and Ir(x)Ch(2) systems undergo nonmetal to metal transitions as x increases. On the basis of density functional theory calculations and the observed large variation in the Ch-Ch distance with x, we suggest that Ir(0.75)Ch(2) (Ir(3)Ch(8)) is the parent compound for the present superconductors.

Development of Database of Children’s Fall Dynamics Using Daily Behavior Observing System

This paper describes the development of a fall database for biomechanical simulation. First, data on children’s daily activities were collected at a “sensor home,” which is a imitation daily living space. The sensor-based home comprises a video-surveillance system embedded into a daily-living environment and a wearable acceleration-gyro sensor. Falls were then detected from sensor data using a fall detection algorithm that we developed, and videos of detected falls were extracted from long-time recorded video. Extracted videos were used for fall motion analysis. A new Computer Vision (CV) algorithm was developed to automate fall motion analysis. Using the CV algorithm, fall motion data were accumulated into a database. The database allows a user to perform conditional searches for fall data by inputting search conditions, such as a child’s attributes, and fall situations.