Construction of a low-temperature thermodynamic measurement system for single crystal of molecular compounds under pressures

An apparatus to obtain low-temperature thermodynamic information under high pressures for a tiny single crystal of molecular compounds was developed based on the ac technique. To detect small temperature oscillation of a sample inside the cramp-type pressure cell, we have used a small ruthenium oxide chip sensor as a thermometer. The adoption of the four-terminal method by the ac resistance bridge has made high-resolution detection of thermal anomaly possible in the low-temperature region. The constructed high-pressure thermodynamic system was mounted on a 3He refrigerator and we have succeeded to detect the thermal anomaly in relevant to magnetic order of single crystal sample of Mn4-cluster complex up to 1.05 GPa. A distinct peak of the heat capacity and its upward shift with increasing pressures was observed using a tiny crystal of about 100 microg. The high-pressure behavior of the discontinuity of heat capacity at the superconductive transition of 6 mg of metal indium has also been detected by this apparatus. The details and performance of the technique are reported.     

Kinetically Stable Bicelles with Dilution Tolerance,Size Tunability,and Thermoresponsiveness for Drug Delivery Applications

Mixtures of a phospholipid (1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphatidylcholine, DPPC) and a sodium‐cholate‐derived surfactant (SC‐C₅) at room temperature formed phospholipid bilayer fragments that were edge‐stabilized by SC‐C₅: so‐called “bicelles”. Because the bilayer melting point of DPPC (41 °C) is above room temperature and because SC‐C₅ has an exceptionally low critical micelle concentration (<0.5 mm ), the bicelles are kinetically frozen at room temperature. Consequently, they exist even when the mixture is diluted to a concentration of 0.04 wt %. In addition, the lateral size of the bicelles can be fine‐tuned by altering the molar ratio of DPPC to SC‐C₅. On heating to ≈37 °C, the bicelles transformed into micelles composed of DPPC and SC‐C₅. By taking advantage of the dilution tolerance, size tunability, and thermoresponsiveness, we demonstrated in vitro drug delivery based on use of the bicelles as carriers, which suggests their potential utility in transdermal drug delivery.     

Human-sized anthropomorphic robot hand with detachable mechanism at the wrist

In this paper, we proposed a human-sized multi-fingered robot hand with detachable mechanism at the wrist. The fingers are tendon-driven by wires and the actuators are embedded in the arm part. The driving forces from the arm part are transmitted to the hand part by a gear mechanism at the wrist. The gear mechanism makes the hand part and the arm part splittable. The detachable mechanism enables separate maintenance of the hand and arm parts. To avoid undesired joint mutual interferences due to the tendon-driven mechanism, a joint motion correction control is implemented in that counteracting motions are ordered to actuators. The correction coefficient can be calculated based on the mechanical configuration. The developed robot hand has the size of 200[mm](length) × 78[mm](width) × 24.6[mm](thickness) and can exert 10[N] at the fingertip. The performance of the developed robot hand was shown by a motion control experiment.     

High harmonic exploring on different materials in dynamic atomic force microscopy

In atomic force microscopy(AFM), high-frequency components consisted in dynamic tip-sample interaction have been recently demonstrated as a promising technique for exploring more extensive material properties. Here we present an exploratory study of high harmonic atomic force microscopy by force-spectroscopy and high harmonic imaging. Since these components are very weak compared to the fundamental response, we firstly designed a high harmonic cantilever by tuning the second order flexural resonance frequency to an integer 6 times of its fundamental mode(i.e. ω_2=6ω_1). Moreover, it is verified that high harmonic can discern extra features than topographies on different samples with amplitude/frequency modulation(AM/FM) dynamic AFM mode. In AM mode, the first resonance amplitude and 6 th harmonic amplitude were discussed. The 6 th harmonic is more sensitive than the first order response. In FM mode, it is noted that the decaying rate of the 6 th harmonic frequency is approximately 6 multiples to the slope of the fundamental frequency shift when the tip approaches to the surface of sample. This non-destructive method was also adopted to investigate the local interlayer coupling and intercalation in the two-dimensional graphene films tentatively.     

Relationship between structure and physical strength of silk fibroin nanofiber sheet depending on insolubilization treatment

Materials such as expanded polytetrafluoroethylene and glutaraldehyde‐fixed bovine pericardium are currently used for cardiac tissue regeneration. However, patches made from these materials remain permanently without being absorbed by the body and must be replaced overtime because of degeneration or lack of growth. To improve the long‐term outcomes for cardiac tissue regeneration, biocompatible and biodegradable materials must be used. In this study, we used two biocompatible polymers, silk fibroin (SF), which is biodegradable and segmented polyurethane, to prepare nonwoven sheets that were then insolubilized by water vapor or methanol treatment. The tensile stress increased significantly on adding segmented polyurethane to pure SF and the water vapor processed sheets showed higher extension on strain than the methanol‐processed sheets. The different insolubilization treatments also resulted in different SF structures. Our results show that it is possible to obtain the physical properties required for cardiac tissue repair patch by varying the insolubilization treatment. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45560.     

Compact Tunable Narrowband Terahertz-Wave Source Based on Difference Frequency Generation Pumped by Dual Fiber Lasers in MgO:LiNbO<Subscript>3</Subscript>

We demonstrate a high-average-power, single longitudinal-mode, and tunable terahertz (THz)-wave source based on difference frequency generation (DFG) in a MgO:LiNbO₃ (MgO:LN) crystal. The waves for DFG are generated using a pair of Yb-doped pulsed fiber lasers with a master oscillator power fiber amplifier configuration. The average power of the THz-wave output reaches 450 μW at 1.07 THz (280 μm) at a linewidth of 7.2 GHz, and the tunability ranges from 0.35 to 1.07 THz under the pulse repetition frequency of 500 kHz. A short burn-in test of the THz wave is also carried out, and the output power stability is within ± 5% of the averaged power without any active stabilizing technique. The combination of MgO:LN-DFG and stable and robust fiber laser sources is highly promising for the development of high-average-power THz-wave sources, particularly in the high transmission sub-THz region. This approach may enable new applications of THz-wave spectroscopy in imaging and remote sensing.     

Characteristics of humic substances in the Kuji River waters as determined by high-performance size exclusion chromatography with fluorescence detection

Direct measurement by high-performance size exclusion chromatography with fluorescence detection was applied to the characterization of humic substances in river waters from the Kuji River system, which runs through forest hills and an agricultural plain in Japan. The monitoring wavelength of excitation 320 nm and emission 430 nm corresponds to the fluorescence maxima for aquatic fulvic acid. Chromatograms of the river waters showed four peaks; each peak position was in good agreement among these samples. Peak height ratios for the samples from the upstream Kuji River and its tributaries were different from those of the midstream and downstream sections of the Kuji River, which may reflect differences in the characteristics of humic substances and other organic materials supplied from soil to river.     

利用弯曲元测量土体表层剪切波速的初步试验

土体剪切波速是土力学研究与岩土工程设计的关键参数之一。根据压电弯曲元波速测量的方向性,提出了侧向激发与接收的测量模式,使得弯曲元技术可用于室内和现场土体表层剪切波速的测量。在砂土模型内的初步试验表明,以激发元和接收元内侧间距为剪切波传播距离,并采用时域初达波法判别剪切波到达时间,则侧向激发与接收方式弯曲元的剪切波速测量结果准确可靠,精度与常规"对向激发与接收"方式相同。该弯曲元测试方法为当前大量涉及的取样扰动评价及地基处理质量控制等重要问题提供了便捷可靠的无损检测手段。     

基于GIS空间数据库的三维边坡稳定性分析

结合GIS的空间数据分析功能和改进的Hovland三维边坡稳定分析模型，提出一个全新的基于GIS空间数据库的三维边坡稳定分析模型，假定初始三维滑动面为椭球形，研究采用Monte-Carlo模拟方法搜寻最危险滑动面，全部分析研究程序采用VB和GIS控制软件编制，利用GIS的空间数据处理分析功能，各种可能滑动面所需输入数据可以方便地得到，而且结果也能方便地在数字地图上表示和分类。     

Mixed valency in rare-earth fullerides

Mixed-valence phenomena associated with the highly correlated narrow-band behaviour of the 4f electrons in rare earths are well documented for a variety of rare-earth chalcogenides, borides and intermetallics (Kondo insulators and heavy fermions). The family of rare-earth fullerides with stoichiometry RE2.75C60 (RE=Sm, Yb, Eu) also displays an analogous phenomenology and a remarkable sensitivity of the rare-earth valency to external stimuli (temperature and pressure) making them the first known molecular-based members of this fascinating class of materials. Using powerful crystallographic and spectroscopic techniques which provide direct indications of what is happening in these materials at the microscopic level, we find a rich variety of temperature- and pressure-driven abrupt or continuous valence transitions-the electronically active fulleride sublattice acts as an electron reservoir that can accept electrons from or donate electrons to the rare-earth 4f/5d bands, thereby sensitively modulating the valence of the rare-earth sublattice.