Nano-particle motion in a monolithic silica column using the single-particle tracking method.

Porous materials are used in a variety of industrial applications owing to their large surface areas, large pore volumes, hierarchical porosities, and low densities. The motion of particles inside the pores of porous materials has attracted considerable attention. We investigated nano-particle motion in a porous material using the single-particle tracking method. Particle motion such as absorption and desorption at the wall was observed. The displacement probability distribution deviated from the Gaussian distribution at the tail, indicating non-Gaussian motion of the particles. Moreover, an analysis of the relative angle between three consecutive particle positions revealed that the probability of the particle moving backward was approximately twice that of the particle moving forward. These results indicate that particle motion inside porous materials is highly complex and that a single-particle study is essential for fabricating a structure that is suitable for applications.

Structured light illumination for pressure-sensitive paint measurement under ambient light.

We propose a pressure-sensitive paint (PSP) method under ambient light based on structured light illumination. In the PSP method, pressure is obtained by measuring the variation of the emission light intensity from a PSP coating when it is illuminated by a light source. Since the extraction of the emission light from ambient light is difficult in the conventional PSP method, the existence of ambient light induces a noticeable measurement error. While spatially uniform light is used as illumination light in the conventional PSP method, structured light, the spatial intensity of which is actively controlled, is used in the proposed method. By measuring the PSP emission by varying the spatial pattern of the structured light illumination, one can eliminate ambient light, which is not synchronized with the structured light and can measure pressure without the effect of ambient light. In this study, we demonstrate the pressure measurement under ambient light using structured light with a sinusoidal wave generated by a digital mirror device. The measured pressure agrees well with the pressure measured by a pressure transducer connected to a pressure tap. The proposed method is promising under ambient light conditions.

Synthesis of Visible-Light-Activated Hypervalent Iodine and Photo-oxidation under Visible Light Irradiation via a Direct S0→Tn Transition.

Heavy atom-containing molecules cause a photoreaction by a direct S0 → Tn transition. Therefore, even in a hypervalent iodine compound with a benzene ring as the main skeleton, the photoreaction proceeds under 365-400 nm wavelength light, where UV-visible spectra are not observed by usual measurement method. Some studies, however, report hypervalent iodine compounds that strongly absorb visible light. Herein, we report the synthesis of two visible light-absorbing hypervalent iodines and their photooxidation properties under visible light irradiation. We also demonstrated that the S0 → Tn transition causes the photoreaction to proceed under wavelengths in the blue and green light region.

Markerless Image Alignment Method for Pressure-Sensitive Paint Image.

We propose a markerless image alignment method for pressure-sensitive paint measurement data replacing the time-consuming conventional alignment method in which the black markers are placed on the model and are detected manually. In the proposed method, feature points are detected by a boundary detection method, in which the PSP boundary is detected using the Moore-Neighbor tracing algorithm. The performance of the proposed method is compared with the conventional method based on black markers, the difference of Gaussian (DoG) detector, and the Hessian corner detector. The results by the proposed method and the DoG detector are equivalent to each other. On the other hand, the performances of the image alignment using the black marker and the Hessian corner detector are slightly worse compared with the DoG and the proposed method. The computational cost of the proposed method is half of that of the DoG method. The proposed method is a promising for the image alignment in the PSP application in the viewpoint of the alignment precision and computational cost.

FRET Measurement of Polymer Response under Shear.

Polymer solutions under shear flow are often observed in manufacturing processes. Classically, polymer behavior is represented by Kuhn's bead-spring model, in which only the elongation of polymer chains is assumed. In recent years, the compression of polymer chains under shear flow has been reported. In this study, we investigated the behavior of polymer chains dissolved in various concentrations under shear flow. We measured the time variation of the fluorescence intensity emitted from a FRET (fluorescence resonance energy transfer) polymer, which enabled us to study the change in the distance between both ends of a polymer chain. The polymer chains appeared to stretch and compress depending on the concentration of the polymer solution. The results showed that the deformation of polymer chains was different from the classical theory. The FRET measurement is a promising diagnostic method for understanding the dynamics of polymer chains.

Pressure-Sensitive Nano-Sheet for Optical Pressure Measurement.

Pressure-Sensitive Paint (PSP) is a powerful measurement technique to obtain pressure distribution on a model of interest by measuring the emission intensity of the PSP coating with a camera. Since a PSP coating is prepared by applying a solution containing an organic solvent, generally, by sprayer, the properties such as the pressure- and the temperature-sensitivity depends on the skill of the person applying it. This fabrication process is one of the barriers to use of the PSP technique because of the legal restrictions on the use of organic solvents. Thus, a sticker-like PSP coating is useful because it does not require the use of organic solvent and the applying skill. In this study, we have fabricated freestanding Pressure-Sensitive Nano-Sheet (PSNS) by a sacrificial layer process using a spin-coating method. We employed Pt(II) meso-tetra(pentafluorophenyl)porphine (PtTFPP) as a pressure-sensitive dye and poly(1-trimethylsilyl-propyne) (PTMSP) and poly(L-lactic acid) (PLLA) as a polymer binder; thus, the PSNS samples based on PTMSP and PLLA were prepared. The pressure- and the temperature-sensitivity, the lifetime of the luminescence, and the quantum yield of the fabricated PSNS have been investigated. The pressure-sensitivity of PTMSP-based PSNS is higher than that of PLLA-based PSNS. Conversely, the quantum yield of PLLA-based PSNS is higher than that of PTMSP-based PSNS.

Numerical study for tableting process in consideration of compression speed.

A numerical study of the tableting process using a finite element method (FEM) is important to quantitatively understand the structural change inside the tablet and the mechanism of tableting failures such as capping, picking, lamination, and sticking. In the pharmaceutical field, the Drucker-Prager Cap (DPC) model is used most widely to demonstrate the mechanical behavior of the powder during tableting. The DPC model, however, cannot consider compaction speed, although the compaction speed has a large impact on the tablet strength and tableting failures. In the present study, a combined novel model using both the DPC and Perzyna models, which incorporates a visco-plastic behavior considering the compression speed, was proposed and numerical simulation was conducted. Cellulose, lactose, and acetaminophen were selected as model powders. The DPC-Perzyna model parameters were determined from experimental compaction tests, unconfined compression tests, and tension tests. The calculated loading curves agreed with the experimental data under different compaction speeds, in addition the high compression speed resulted in less plastic deformation and much residual stress. It was demonstrated that the DPC-Perzyna model proposed in the present study was useful to analyze the tableting process when considering compression speed.

Electrophoretic Separation on an Origami Paper-Based Analytical Device Using a Portable Power Bank.

The electrophoresis of ampholytes such as amino acids on a paper device is difficult because of the variation of pH distribution in time. On the basis of this observation, we propose a paper-based analytical device (PAD) with origami structure. By folding a filter paper, a low operation voltage of 5 V was achieved, where the power was supplied by a 5 V 1.5 A portable power bank through the USB type A receptacle. As a demonstration, we carried out the electrophoretic separation of pI markers (pI 5.5 and 8.7). The separation was achieved within 4 min before the pH distribution on the paper varied. Though the separation distance was small, it could be increased by expanding the origami structure. This result indicates that our proposed PAD is useful for electrophoretic separation on a paper device.

Impact cratering on a granular bed by hydrogel spheres having intermediate property between solid and liquid.

We investigated the low speed impact on a granular bed by a hydrogel sphere and especially focused on the resultant crater diameter. Though the crater diameter depends only on the impact kinetic energy for the solid sphere impact cratering, it also depends on the elastic energy for the hydrogel sphere. The hydrogel sphere impact cratering is classified into two dynamics: small and large indentation of the sphere. For the small indentation, the crater diameter is proportional to the 1/4 power of the energy for ejecting granular materials, which is calculated by substituting the elastic energy stored in the sphere from the impact kinetic energy. Considering the force balance between the inertial force and the indentation, we derived the relation between the impact kinetic energy, Young's modulus, and the crater diameter. In the large limit of Young's modulus, the relation leads to the 1/4 power law observed in solid sphere impact. The dependency of Young's modulus on the crater diameter for the large indentation of the sphere is larger than the impact with small indentation.

Estimation of diffusive states from single-particle trajectory in heterogeneous medium using machine-learning methods.

We propose a novel approach to analyze random walks in heterogeneous medium using a hybrid machine-learning method based on a gamma mixture and a hidden Markov model. A gamma mixture and a hidden Markov model respectively provide the number and the most probable sequence of diffusive states from the time series position data of particles/molecules obtained by single-particle/molecule tracking (SPT/SMT) method. We evaluate the performance of our proposed method for numerically generated trajectories. It is shown that our proposed method can correctly extract the number of diffusive states when each trajectory is long enough to be frame averaged. We also indicate that our method can provide an indicator whether the assumption of a medium consisting of discrete diffusive states is appropriate or not based on the available amount of trajectory data. Then, we demonstrate an application of our method to the analysis of experimentally obtained SPT data.

Suppressing the coffee-ring effect of colloidal droplets by dispersed cellulose nanofibers.

We report that the addition of a small amount of cellulose nanofibers (CNFs) into an aqueous dispersion of colloidal particles suppresses the coffee-ring effect when the dispersion dries on a solid substrate, as revealed by the computational analysis of experimental time-series images and by particle image velocimetry. The addition of CNFs is much more effective than the increase of colloidal particle concentration at the same weight percentage; it is also more environment friendly than the use of typical molecular surfactants. This finding is promising for the fabrication of metamaterials from colloidal dispersions and for ink printing in electronics, where CNFs can also serve as a substrate for flexible devices.

Molecular-dynamics study on characteristics of energy and tangential momentum accommodation coefficients.

Gas-surface interaction is studied by the molecular dynamics method to investigate qualitatively characteristics of accommodation coefficients. A large number of trajectories of gas molecules colliding to and scattering from a surface are statistically analyzed to calculate the energy (thermal) accommodation coefficient (EAC) and the tangential momentum accommodation coefficient (TMAC). Considering experimental measurements of the accommodation coefficients, the incident velocities are stochastically sampled to represent a bulk condition. The accommodation coefficients for noble gases show qualitative coincidence with experimental values. To investigate characteristics of these accommodation coefficients in detail, the gas-surface interaction is parametrically studied by varying the molecular mass of gas, the gas-surface interaction strength, and the molecular size of gas, one by one. EAC increases with increasing every parameter, while TMAC increases with increasing the interaction strength, but decreases with increasing the molecular mass and the molecular size. Thus, contradictory results in experimentally measured TMAC for noble gases could result from the difference between the surface conditions employed in the measurements in the balance among the effective parameters of molecular mass, interaction strength, and molecular size, due to surface roughness and/or adsorbed molecules. The accommodation coefficients for a thermo-fluid dynamics field with a temperature difference between gas and surface and a bulk flow at the same time are also investigated.

High-Mobility 6,13-Bis(triisopropylsilylethynyl) Pentacene Transistors Using Solution-Processed Polysilsesquioxane Gate Dielectric Layers.

Polysilsesquioxane (PSQ) is a low-temperature curable polymer that is compatible with low-cost plastic substrates. We cured PSQ gate dielectric layers by irradiation with ultraviolet light at ~60 °C, and used them for 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) thin film transistors (TFTs). The fabricated TFTs have shown the maximum and average hole mobility of 1.3 and 0.78 ± 0.3 cm2V-1s-1, which are comparable to those of the previously reported transistors using single-crystalline TIPS-pentacene micro-ribbons for their active layers and thermally oxidized SiO2 for their gate dielectric layers. Itis therefore demonstrated that PSQ is a promising polymer gate dielectric material for low-cost organic TFTs.

Polymer-Particle Pressure-Sensitive Paint with High Photostability.

We propose a novel fast-responding and paintable pressure-sensitive paint (PSP) based on polymer particles, i.e. polymer-particle (pp-)PSP. As a fast-responding PSP, polymer-ceramic (PC-)PSP is widely studied. Since PC-PSP generally consists of titanium (IV) oxide (TiO2) particles, a large reduction in the luminescent intensity will occur due to the photocatalytic action of TiO2. We propose the usage of polymer particles instead of TiO2 particles to prevent the reduction in the luminescent intensity. Here, we fabricate pp-PSP based on the polystyrene particle with a diameter of 1 µm, and investigate the pressure- and temperature-sensitives, the response time, and the photostability. The performances of pp-PSP are compared with those of PC-PSP, indicating the high photostability with the other characteristics comparable to PC-PSP.

Faster Convergence of Diffusion Anisotropy Detection by Three-Step Relation of Single-Particle Trajectory.

We focus on the issue of limited number of samples in the single particle tracking (SPT) when trying to extract the diffusion anisotropy that originates from the particle asymmetry. We propose a novel evaluation technique of SPT making use of the relation of the consecutive three steps. More specifically, the trend of the angle comprised of the three positions and the displacements are plotted on a scatter diagram. The particle anisotropy dependence of the shape of the scatter diagram is examined through the data from the standard numerical model of anisotropic two-dimensional Brownian motion. Comparison with the existing method reveals the faster convergence in the evaluation. In particular, our proposed method realizes the detection of diffusion anisotropy under the conditions of not only less number of data but also larger time steps. This is of practical importance not only when the abundant data is hard to achieve but also when the rotational diffusion is fast compared to the frame rate of the camera equipment, which tends to be more common for smaller particles or molecules of interest.

Electric conductive pattern element fabricated using commercial inkjet printer for paper-based analytical devices.

Herein, we proposed the addition of an inkjet-printed conductive pattern to paper-based analytical devices (PADs) in order to expand their applications. An electric conductive pattern was easily, quickly, and inexpensively fabricated using a commercial inkjet printer. The addition of a printed electric element will enhance the applications of PADs without the loss of properties such as cost efficiency, disposability, and portability. In this study, we applied an inkjet-printed heater to a piece of paper and investigated its characteristics. The use of the heater as a valve, concentrator, and heat source for chemical reactions on PADs was investigated. Previously, these functions were difficult to realize with PADs. The inkjet-printed heater was used as a valve and concentrator through evaporation of the working fluid and solvent, and was also found to be useful for providing heat for chemical reactions. Thus, the combination of printed electric circuits and PADs has many potential applications.

Unsteady pressure-sensitive paint measurement based on the heterodyne method using low frame rate camera.

The pressure-sensitive paint technique based on the heterodyne method was proposed for the precise pressure measurement of unsteady flow fields. This measurement is realized by detecting the beat signal that results from interference between a modulating illumination light source and a pressure fluctuation. The beat signal is captured by a camera with a considerably lower frame rate than the frequency of the pressure fluctuation. By carefully adjusting the frequency of the light and the camera frame rate, the signal at the frequency of interest is detected, while the noise signals at other frequencies are eliminated. To demonstrate the proposed method, we measured the pressure fluctuations in a resonance tube at the fundamental, second, and third harmonics. The pressure fluctuation distributions were successfully obtained and were consistent with measurements from a pressure transducer. The proposed method is a useful technique for measuring unsteady phenomena.

Characteristics of Japanese Duchenne and Becker muscular dystrophy patients in a novel Japanese national registry of muscular dystrophy (Remudy).

BACKGROUND: Currently, clinical trials for new therapeutic strategies are being planned for Duchenne and Becker muscular dystrophies (DMD/BMD). However, it is difficult to obtain adequate numbers of patients in clinical trials. As solutions to these problems, patient registries are an important resource worldwide, especially in rare diseases such as DMD/BMD. METHODS: We developed a national registry of Japanese DMD/BMD patients in collaboration with TREAT-NMD. The registry includes male Japanese DMD/BMD patients whose genetic status has been confirmed by genetic analysis. The registry includes patients throughout Japan. RESULTS: As of February 2012, 583 DMD and 105 BMD patients were registered. Most individuals aged less than 20 years. In terms of genetic mutations of registrants of DMD and BMD, deletion of exons was the most frequent (61.4% and 79.0%) followed by point mutations (24.5% and 14.3%) and duplications (13.6% and 4.8%), respectively. 43.6% of DMD are capable of walking, and 76.2% of BMD registrants are able to walk. 41.1% of DMD registrants in the database were treated using steroids. 29.5% of DMD and 23.8% of BMD registrants were prescribed one cardiac medicine at least. 22% of DMD used ventilator support, and non-invasive support was common. Small numbers of DMD and BMD registrants, only 3.9% and 1.0% of them, have received scoliosis surgery. 57 (9.8%) patients were eligible to clinical trial focused on 'skipping' exon 51. CONCLUSIONS: The Remudy has already demonstrated utility in clinical researches and standardization of patients care for DMD/BMD. This new DMD/BMD patient registry facilitates the synchronization of clinical drug development in Japan with that in other countries.

Organic electroluminescent sensor for pressure measurement.

We have proposed a novel concept of a pressure sensor called electroluminescent pressure sensor (ELPS) based on oxygen quenching of electroluminescence. The sensor was fabricated as an organic light-emitting device (OLED) with phosphorescent dyes whose phosphorescence can be quenched by oxygenmolecules, and with a polymer electrode which permeates oxygen molecules. The sensor was a single-layer OLED with Platinum (II) octaethylporphine (PtOEP) doped into poly(vinylcarbazole) (PVK) as an oxygen sensitive emissive layer and poly(3,4-ethylenedioxythiophene) mixed with poly(styrenesulfonate) (PEDOT:PSS) as an oxygen permeating polymer anode. The pressure sensitivity of the fabricated ELPS sample was equivalent to that of the sensor excited by an illumination light source. Moreover, the pressure sensitivity of the sensor is equivalent to that of conventional pressure-sensitive paint (PSP), which is an optical pressure sensor based on photoluminescence.