Evaluation of Scissor Glide Characteristics Through Surgeons' Subjective Assessment: The Application of Nitriding in Scissor Hardening Tests.

INTRODUCTION: In robotic surgery, studies on providing tactile feedback to users are ongoing. However, the accuracy of the subjective sensations of surgeons, as users, has been largely unassessed. This study aimed to assess the validity of surgeons' subjective evaluations of scissors resistance through interindividual, inter-surgeon, and objective evaluations. Furthermore, in this study, we explored the possibility of using nitriding to increase the hardness of the scissors and assessed changes in subjective resistance values before and after nitriding using this approach. METHOD: Five surgeons conducted validation of five curved surgical scissors (145 mm; Arakawa Seisakujyo Co., Ltd., Tokyo, Japan) and assessed their subjective resistance using a scale from 0 to 10, where a rating of 10 signified significant resistance impeding the scissors' closure. The temporal changes in subjective resistance values, from maximum open to close, were graphically recorded. To demonstrate the reproducibility of subjective resistance values, the subjective resistance values of the same control scissors were measured at intervals of at least two weeks, and the correlation coefficient was calculated. To analyze the closing characteristics of subjective resistance values between different pairs of scissors, the effect of scissor type and scissor closure position was compared as two independent variables using a two-factor analysis of variance. A comparative evaluation was conducted to assess the frictional properties of scissors after nitriding, comparing the subjective assessment by surgeons with the objective assessment using a digital force gauge. RESULTS: The correlation coefficient of subjective resistance values measured by surgeons demonstrated a high reproducibility of 0.746. A two-factor analysis of variance conducted on subjective resistance values demonstrated the presence of a primary effect for the sample factor (scissors), as well as for the position factor (closing process), with the additional observation of the interaction between these two factors. The results from the two-factor analysis of variance above provide evidence supporting the validity of the subjective resistance measurements. There was a significant increase in subjective resistance after the nitriding process. The graph of subjective resistance values and objective resistance values showed similarity. CONCLUSIONS: The surgeons' subjective assessment of scissors resistance showed high reproducibility and validity, as evidenced by distinguishable differences in scissor movement interactions and pre- and post-nitriding resistance. Further studies are warranted to expand on these findings.

Atomic Imaging of Interface Defects in an Insulating Film on Diamond.

The insulator/semiconductor interface structure is the key to electric device performance, and much interest has been focused on understanding the origin of interfacial defects. However, with conventional techniques, it is difficult to analyze the interfacial atomic structure buried in the insulating film. Here, we reveal the atomic structure at the interface between an amorphous aluminum oxide and diamond using a developed electron energy analyzer for photoelectron holography. We find that the three-dimensional atomic structure of a C-O-Al-O-C bridge between two dimer rows of the hydrogen-terminated diamond surface. Our results demonstrate that photoelectron holography can be used to reveal the three-dimensional atomic structure of the interface between a crystal and an amorphous film. We also find that the photoelectron intensity originating from the C-O bonds is strongly related to the interfacial defect density. We anticipate significant progress in the study of amorphous/crystalline interfaces based on their three-dimensional atomic structures analysis.

Surface properties and biocompatibility of sandblasted and acid-etched titanium-zirconium binary alloys with various compositions.

Ti-Zr alloys have been investigated as an alternative to commercially pure Ti (c.p.Ti). According to our previous studies on the mechanical properties of Ti-Zr alloys, a Zr proportion in the range of 30-50 mol% has competitive advantages over Ti-10Zr and c.p.Ti. The aim of this study is to evaluate the biological response to Ti-Zr alloys with different compositions and their surface characteristics. Alloy surfaces are modified by sandblasting and sulfuric acid etching. As a result, similar surface structures are observed for c.p.Ti, Ti-10Zr, and Ti-30Zr, whereas Ti-50Zr does not form a micro-rough structure by the same treatment process. No significant difference is found in the viability of cells on c.p.Ti, Ti-10Zr, and Ti-30Zr, whereas lower cell attachment levels are detected on Ti-50Zr. In summary, Ti-30Zr reliably forms a micro-rough structure, which provides one evidence for its application in a new dental implant material.

Spherical micro-hole grid for high-resolution retarding field analyzer.

A wide-acceptance-angle spherical grid composed of numerous micro cylindrical holes was developed to be used for the retarding grid of a display-type retarding field analyzer (RFA) and to enhance the energy resolution (E/ΔE). Each cylindrical hole with a diameter of 50 µm and a depth of 80 µm is directed to the spherical center. The inner radius of the spherical grid is 40 mm. The holed area corresponds to an acceptance angle of ±52°. The E/ΔE of an RFA equipped with the developed holed grid was estimated to be 2000 from a measured Au 4f photoemission spectrum. A clear photoelectron hologram was observed in the Mo 4p core-level region of MoS2, indicating that the RFA with the holed grid is effective for photoelectron holography.

Manufacturing micropatterned collagen scaffolds with chemical-crosslinking for development of biomimetic tissue-engineered oral mucosa.

The junction between the epithelium and the underlying connective tissue undulates, constituting of rete ridges, which lack currently available soft tissue constructs. In this study, using a micro electro mechanical systems process and soft lithography, fifteen negative molds, with different dimensions and aspect ratios in grid- and pillar-type configurations, were designed and fabricated to create three-dimensional micropatterns and replicated onto fish-scale type I collagen scaffolds treated with chemical crosslinking. Image analyses showed the micropatterns were well-transferred onto the scaffold surfaces, showing the versatility of our manufacturing system. With the help of rheological test, the collagen scaffold manufactured in this study was confirmed to be an ideal gel and have visco-elastic features. As compared with our previous study, its mechanical and handling properties were improved by chemical cross-linking, which is beneficial for grafting and suturing into the complex structures of oral cavity. Histologic evaluation of a tissue-engineered oral mucosa showed the topographical microstructures of grid-type were well-preserved, rather than pillar-type, a well-stratified epithelial layer was regenerated on all scaffolds and the epithelial rete ridge-like structure was developed. As this three-dimensional microstructure is valuable for maintaining epithelial integrity, our micropatterned collagen scaffolds can be used not only intraorally but extraorally as a graft material for human use.

Liquid/solution-based microfluidic quantum dots light-emitting diodes for high-colour-purity light emission.

Organic light-emitting diodes (OLEDs) using a liquid organic semiconductor (LOS) are expected to provide extremely flexible displays. Recently, microfluidic OLEDs were developed to integrate and control a LOS in a device combined with microfluidic technology. However, LOS-based OLEDs show poor-colour-purity light emissions owing to their wide full width at half maximum (FWHM). Here we report liquid/solution-based microfluidic quantum dots light-emitting diodes (QLEDs) for high-colour-purity light emission. Microfluidic QLEDs contain liquid materials of LOS for a backlight and QDs solutions as luminophores. The microfluidic QLED exhibits red, green, and blue light emissions and achieves the highest light colour purity ever reported among LOS-based devices for green and red lights with narrow FWHMs of 26.2 nm and 25.0 nm, respectively. Additionally, the effect of the channel depth for the luminophore on the peak wavelength and FWHM is revealed. The developed device extends the capabilities of flexible microfluidic OLEDs-based and QDs-based displays.

Biological reaction control using topography regulation of nanostructured titanium.

The micro- and nanosize surface topography of dental implants has been shown to affect the growth of surrounding cells. In this study, standardized and controlled periodic nanopatterns were fabricated with nanosized surface roughness on titanium substrates, and their influence on bone marrow stromal cells investigated. Cell proliferation assays revealed that the bare substrate with a 1.7 nm surface roughness has lower hydrophilicity but higher proliferation ability than that with a 0.6 nm surface roughness. Further, with the latter substrate, directional cell growth was observed for line and groove patterns with a width of 100 nm and a height of 50 or 100 nm, but not for those with a height of 10 or 25 nm. With the smooth substrate, time-lapse microscopic analyses showed that more than 80% of the bone marrow cells on the line and groove pattern with a height of 100 nm grew and divided along the lines. As the nanosized grain structure controls the cell proliferation rate and the nanosized line and groove structure (50-100 nm) controls cell migration, division, and growth orientation, these standardized nanosized titanium structures can be used to elucidate the mechanisms by which surface topography regulates tissue responses to biomaterials.

Development of microstructured fish scale collagen scaffolds to manufacture a tissue-engineered oral mucosa equivalent.

The present study aimed to develop a more biomimetic tissue-engineered oral mucosa equivalent comprising 1% type I tilapia scale collagen scaffold having microstructures mimicking the dermal-epidermal junction of oral mucosa and oral keratinocytes as graft materials for human use. We designed four micropattern prototypes mimicking the dermal-epidermal junction. Using a semiconductor process and soft lithography, negative molds were fabricated to develop microstructures using both polydimethylsiloxane and silicon substrates. Micropattern configurations of dermal-epidermal junctions manufactured from fish collagen consisting of a fibril network using our micropatterning system were well preserved, although the internal fibril network of the pillar pattern was sparse. Mixing 1% chondroitin sulfate with the collagen matrix minimized tissue-engineered oral mucosa equivalent contraction. Histologic examinations showed a flattening of the vertical dimensions of all microstructures and expansion of their pitches, indicating changes in the originally designed configurations. Nonetheless, histologic examinations revealed that a fully differentiated and stratified epithelial layer was developed on all scaffolds, suggesting that the microstructured fish scale collagen scaffolds have potential in the manufacturing of tissue-engineered oral mucosa equivalents for clinical use; however, enhancement of the mechanical properties of micropatterns is required. Our micropatterning technology can also apply to the development of oral mucosa in vitro models.

Kinetics of Excimer Electrogenerated Chemiluminescence of Pyrene and 1-Pyrenebutyricacid 2-Ethylhexylester in Acetonitrile and an Ionic Liquid, Triethylpentylphosphonium Bis(trifluoromethanesulfonyl)imide.

We describe the kinetics of excimer electrogenerated chemiluminescence (ECL) of a liquid pyrene derivative, 1-pyrenebutyricacid 2-ethylhexylester (PLQ) dissolved in a molecular solvent, acetonitrile (MeCN), and an ionic liquid, triethylpentylphosphonium bis(trifluoromethanesulfonyl)imide ([P2225][TFSI]). Pyrene was also used for comparison. To discuss the kinetics of the excimer ECLs, the photophysical and electrochemical properties and electronic states of PLQ and pyrene were revealed. The photoluminescence (PL) spectra, rate constants for the radiative transitions, and redox potentials of PLQ and pyrene dissolved in MeCN and [P2225][TFSI] suggest that as a solvent, [P2225][TFSI] behaves more polar than MeCN. By analyzing the PL decay curves, the rate constants to form the excimer were determined to be on the order of 109 and 107 M-1 s-1 in MeCN and [P2225][TFSI], respectively, which were limited by the diffusion. For neat PLQ (1.6 M), a delay of 0.3-0.4 ns for the excimer emission compared to the monomer emission was observed. It is likely that the delay corresponds to the timescale for arranging the conformation to form the excimer. The ECL of PLQ was generated by applying a square wave voltage to produce the radical anion and cation, and on the ECL spectra, the excimer emission was more prevailed compared to the PL spectra. Kinetic analysis for the electron transfer reaction between the radical ions based on Marcus theory indicates that the electron transfer is limited by the diffusion of the radical ions. Moreover, the electron transfer distance (det) between the radical cation and anion to generate excited states was calculated with a framework of the theory. Kinetically, the electron transfer can take place at det < ∼11 Å in MeCN and det < ∼12 Å in [P2225][TFSI]. The density functional theory (DFT) and time-dependent DFT calculations show that the potential energy curve of the excimer against the distance between the pyrene rings reaches a minimum at 3.50 Å. This suggests that through the electron transfer, the process of the direct formation of the monomer S1 state followed by the excimer formation is more prevailed than that of the direct excimer formation.

Highly flexible transparent electrodes based on mesh-patterned rigid indium tin oxide.

We developed highly bendable transparent indium tin oxide (ITO) electrodes with a mesh pattern for use in flexible electronic devices. The mesh patterns lowered tensile stress and hindered propagation of cracks. Simulations using the finite element method confirmed that the mesh patterns decreased tensile stress by over 10% because of the escaped strain to the flexible film when the electrodes were bent. The proposed patterned ITO electrodes were simply fabricated by photolithography and wet etching. The resistance increase ratio of a mesh-patterned ITO electrode after bending 1000 times was at least two orders of magnitude lower than that of a planar ITO electrode. In addition, crack propagation was stopped by the mesh pattern of the patterned ITO electrode. A mesh-patterned ITO electrode was used in a liquid-based organic light-emitting diode (OLED). The OLED displayed the same current density-voltage-luminance (J-V-L) curves before and after bending 100 times. These results indicate that the developed mesh-patterned ITO electrodes are attractive for use in flexible electronic devices.

In-Plane Anisotropic Molecular Orientation of Pentafluorene and Its Application to Linearly Polarized Electroluminescence.

By preparing parallelly aligned 1.9-µm-high SiO2 microfluidic channels on an indium tin oxide substrate surface, the solution flow direction during spin-coating was controlled to be parallel to the grating. Using this technique, a pentafluorene-4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP) binary solution in chloroform was spin-coated to embed a 40-50 nm-thick 10 wt %-pentafluorene:CBP thin film in the channels. In-plane polarized photoluminescence measurements revealed that the pentafluorene molecules tended to orient along the grating, demonstrating that one-dimensional fluid flow can control the in-plane molecular orientation. Furthermore, the dependences of the photoluminescence anisotropy on the spin speed and substrate material suggest that the velocity of the solution flow and/or its gradient in the vertical direction greatly affects the resulting orientation. This indicates that the mechanism behind the molecular orientation is related to stress such as the shear force. The effect of the solution flow on the molecular orientation was demonstrated even in organic light-emitting diodes (OLEDs). Linearly polarized electroluminescence was obtained by applying the in-plane orientation to OLEDs, and it was found that the dichroic ratio of the electroluminescence orthogonal (x) and parallel (y) to the grating is x/y = 0.75.

Low-temperature direct heterogeneous bonding of polyether ether ketone and platinum.

Direct heterogeneous bonding between polyether ether ketone (PEEK) and Pt was realized at the temperatures lower than 150°C. In order to create sufficient bondability to diverse materials, the surface was modified by vacuum ultraviolet (VUV) irradiation, which formed hydrate bridges. For comparison, direct bonding between surfaces atomically cleaned via Ar fast atom bombardment (FAB) was conducted in a vacuum. The VUV irradiation was found to be effective for creating an ultrathin hydrate bridge layer from the residual water molecules in the chamber. Tight bonds were formed through dehydration of the hydrate bridges by heating at 150°C, which also contributed to enhancing interdiffusion across the interface. The VUV-modified surfaces showed bondability as good as that of the FAB-treated surfaces, and the VUV-modified samples had shear strengths at the same level as those of FAB-treated surfaces. This technology will be of practical use in the packaging of lightweight, flexible biomedical devices.

Microfluidic White Organic Light-Emitting Diode Based on Integrated Patterns of Greenish-Blue and Yellow Solvent-Free Liquid Emitters.

We demonstrated a novel microfluidic white organic light-emitting diode (microfluidic WOLED) based on integrated sub-100-µm-wide microchannels. Single-µm-thick SU-8-based microchannels, which were sandwiched between indium tin oxide (ITO) anode and cathode pairs, were fabricated by photolithography and heterogeneous bonding technologies. 1-Pyrenebutyric acid 2-ethylhexyl ester (PLQ) was used as a solvent-free greenish-blue liquid emitter, while 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyltetracene (TBRb)-doped PLQ was applied as a yellow liquid emitter. In order to form the liquid white light-emitting layer, the greenish-blue and yellow liquid emitters were alternately injected into the integrated microchannels. The fabricated electro-microfluidic device successfully exhibited white electroluminescence (EL) emission via simultaneous greenish-blue and yellow emissions under an applied voltage of 100 V. A white emission with Commission Internationale de l'Declairage (CIE) color coordinates of (0.40, 0.42) was also obtained; the emission corresponds to warm-white light. The proposed device has potential applications in subpixels of liquid-based microdisplays and for lighting.

Electrogenerated chemiluminescence of donor-acceptor molecules with thermally activated delayed fluorescence.

The electrochemistry and electrogenerated chemiluminescence (ECL) of four kinds of electron donor-acceptor molecules exhibiting thermally activated delayed fluorescence (TADF) is presented. TADF molecules can harvest light energy from the lowest triplet state by spin up-conversion to the lowest singlet state because of small energy gap between these states. Intense green to red ECL is emitted from the TADF molecules by applying a square-wave voltage. Remarkably, it is shown that the efficiency of ECL from one of the TADF molecule could reach about 50%, which is comparable to its photoluminescence quantum yield.

Real-time single-cell imaging of protein secretion.

Protein secretion, a key intercellular event for transducing cellular signals, is thought to be strictly regulated. However, secretion dynamics at the single-cell level have not yet been clarified because intercellular heterogeneity results in an averaging response from the bulk cell population. To address this issue, we developed a novel assay platform for real-time imaging of protein secretion at single-cell resolution by a sandwich immunoassay monitored by total internal reflection microscopy in sub-nanolitre-sized microwell arrays. Real-time secretion imaging on the platform at 1-min time intervals allowed successful detection of the heterogeneous onset time of nonclassical IL-1ß secretion from monocytes after external stimulation. The platform also helped in elucidating the chronological relationship between loss of membrane integrity and IL-1ß secretion. The study results indicate that this unique monitoring platform will serve as a new and powerful tool for analysing protein secretion dynamics with simultaneous monitoring of intracellular events by live-cell imaging.

Fast and quantitative analysis of branched-chain amino acids in biological samples using a pillar array column.

In this study, a fast and quantitative determination method for branched-chain amino acids (BCAAs), namely leucine, isoleucine, and valine, was developed using a pillar array column. A pillar array column with low-dispersion turns was fabricated on a 20 × 20-mm(2) microchip using multistep ultraviolet photolithography and deep reactive ion etching. The BCAAs were fluorescently labeled with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F), followed by reversed-phase separation on the pillar array column. The NBD derivatives of the three BCAAs and an internal standard (6-aminocaproic acid) were separated in 100 s. The calibration curves for the NBD-BCAAs had good linearity in the range of 0.4-20 µM, using an internal standard. The intra- and interday precisions were found to be in the ranges of 1.42-3.80 and 2.74-6.97%, respectively. The accuracies for the NBD-BCAA were from 90.2 to 99.1%. The method was used for the analysis of sports drink and human plasma samples. The concentrations of BCAAs determined by the developed method showed good agreements with those determined using a conventional high-performance liquid chromatography system. As BCAAs are important biomarkers of some diseases, these results showed that the developed method could be a potential diagnostic tool in clinical research.

Integration of pillar array columns into a gradient elution system for pressure-driven liquid chromatography.

A gradient elution system for pressure-driven liquid chromatography (LC) on a chip was developed for carrying out faster and more efficient chemical analyses. Through computational fluid dynamics simulations and an experimental study, we found that the use of a cross-Tesla structure with a 3 mm mixing length was effective for mixing two liquids. A gradient elution system using a cross-Tesla mixer was fabricated on a 20 mm × 20 mm silicon chip with a separation channel of pillar array columns and a sample injection channel. A mixed solution of water and fluorescein in methanol was delivered to the separation channel 7 s after the gradient program had been started. Then, the fluorescence intensity increased gradually with the increasing ratio of fluorescein, which showed that the gradient elution worked well. Under the gradient elution condition, the retention times of two coumarin dyes decreased with the gradient time. When the gradient time was 30 s, the analysis could be completed in 30 s, which was only half the time required compared to that required for an isocratic elution. Fluorescent derivatives of aliphatic amines were successfully separated within 110 s. The results show that the proposed system is promising for the analyses of complex biological samples.

Use of folded micromachined pillar array column with low-dispersion turns for pressure-driven liquid chromatography.

In this study, we show for the first time that the separation efficiency of a pillar array column under pressure-driven liquid chromatography (LC) conditions can be improved using a separation channel with low-dispersion turns. The pillar array column was fabricated by reactive ion etching of a silicon substrate. With the low-dispersion-turn geometry, a column with a length and width of 110 mm and 400 microm, respectively, could be fabricated on a 20 x 20 mm microchip. Under nonretained conditions, the solute bands obtained for fluorescent compounds remained almost unchanged even after passing through the low-dispersion turns; however, significant skewing of the solute bands was observed in the case of constant-radius turns. Two coumarin dyes were well resolved under reversed-phase conditions, and a maximum theoretical plate number of 8000 was obtained. Successful separation of the fluorescent derivatives of six amino acids was achieved in 140 s. These results indicated that the separation efficiency of microchip chromatography could be significantly improved using a long separation channel with low-dispersion turns.

High efficiency electrochemical immuno sensors using 3D comb electrodes.

To realize highly sensitive electrochemical immunoassays, a micro-fabricated three-dimensional (3D) electrode was fabricated and applied to enzyme immuno assay based on production of a redox species. The dimensions of the electrodes are 10 microm in width and 30 microm in height, with 20 microm spacing in between, and the 30 pairs of anode and cathode electrodes made up a single sensor. This structure lead to enhancement of the electrochemical reaction, nearly 100% of trap ratio of redox species. It can be applied to highly sensitive enzyme immuno sensing based on p-aminophenylphosphate (PAPP). Applicability of this technique to the immuno assay for one of the clinical diagnostic marker proteins (alpha-fetoprotein; AFP) from 6 to 500 ng/mL was demonstrated.

Exceeding the classical capacity limit in a quantum optical channel.

The amount of information transmissible through a communications channel is determined by the noise characteristics of the channel and by the quantities of available transmission resources. In classical information theory, the amount of transmissible information can be increased twice at most when the transmission resource is doubled for fixed noise characteristics. In quantum information theory, however, the amount of information transmitted can increase even more than twice. We present a proof-of-principle demonstration of this superadditivity of classical capacity of a quantum channel by using the ternary symmetric states of a single photon, and by event selection from a weak coherent light source. We also show how the superadditive coding gain, even in a small code length, can boost the communication performance of the conventional coding technique.