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排序方式: 共有452条查询结果,搜索用时 187 毫秒
61.
Spencer B. Backus Rina Onishi Andrew Bocklund Andrew Berg Eric D. Contreras Aaron Parness 《野外机器人技术杂志》2020,37(6):972-986
We present the design and experimental results for the JPL‐Nautilus Gripper, a 16‐finger highly underactuated microspine gripper for use in the deep ocean. The gripper can grasp objects from 10 to 30 cm in size and anchor to flat and curved rocky surfaces (i.e., cliff faces and seamounts). Laboratory results demonstrated an anchoring capability of greater than 450 N on rough rocks in both shear and normal loading directions. Deployment on the Hercules ROV (remotely operated vehicle) aboard the E/V Nautilus on three deep‐ocean dives verified performance at depths up to to 2,100 m with approximately 100 N loads applied through the ROV's thrusters, including moment loads. The gripper also serves as a development unit for future robotic tools that will include a coring drill in the center of the gripper, as previously demonstrated in non‐ocean environments with microspine grippers. Such a tool will facilitate the collection of geologic samples from the deep ocean using more agile and cost‐effective systems. 相似文献
62.
The structure of the L-tartaric acid adsorbed on the surface of a nickel metal catalyst with or without NaBr was studied by FT-IRAS. The carboxylic acid and carboxylate type adsorbed species were observed on nickel surface which was treated with only tartaric acid, while only one type of carboxylate ion was observed on the nickel surface which was treated with tartaric acid and NaBr. 相似文献
63.
Highly acidic catalysts stronger than the SO4/ZrO2 superacid with an acid strength of Ho –16.04 were obtained by kneading Zr(OH)4 with ammonium sulfate together with chlorides of Ir, Pt, Rh, Ru, Os, and Pd followed by calcining in air at 600°C, the metal concentration being equivalent to Pt of 7.5 wt% based on the hydroxide. The catalysts with Ir and Pt materials were highest in activity for the skeletal isomerization of butane to isobutane. The present catalysts were not obtained by treating the crystallized oxide, ZrO2 calcined at 700°C, but the amorphous form followed by calcination to the crystallization.Superacids by metal oxides, VI. For previous publication in this series see ref. [1]. 相似文献
64.
1,2‐Propanediol–cellulose–acrylamide graft copolymers (PCACs) were developed for enhanced oil recovery. They were prepared with acrylamide and 1,2‐propanediol (PDO)–cellulose, which was formed through the addition of glycols to cellulose by the Shotten–Baumann reaction between 3‐chloro‐1,2‐propanediol and cellulose. The graft copolymerization was initiated with a redox system between Ce4+ and glycols in cellulose. The infrared spectrum of PDO–cellulose had some characteristic absorption bands around 2960 (νC? H) and 1050 cm?1 (νC? O) that also appeared for the PDO group and pyranose ring of cellulose, respectively. The rate of Ce4+ consumption by PDO–cellulose was investigated through the calculation of the overall kinetic constant from the slopes of ln(D ? DR) versus time (where D is the absorbance and DR is the absorbance of the original polysaccharide solution) The results showed that PDO–cellulose had high reactivity and that there were two mechanisms of oxidation by Ce4+ with PDO–cellulose. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3022–3029, 2004 相似文献
65.
Yutaka Hasegawa Ryohei Harada Kazuki Tokuda Kimihiro Kimura Hideo Ogawa Toshikazu Onishi Atsushi Nishimura Johnson Han Makoto Inoue 《Journal of Infrared, Millimeter and Terahertz Waves》2017,38(5):638-652
A new stepped septum-type waveguide circular polarizer (SST-CP) was developed to operate in the 230 GHz band for radio astronomy, especially submillimeter-band VLBI observations. For previously reported SST-CP models, the 230 GHz band is too high to achieve the design characteristics in manufactured devices because of unexpected machining errors. To realize a functional SST-CP that can operate in the submillimeter band, a new method was developed, in which the division surface is shifted from the top step of the septum to the second step from the top, and we simulated the expected machining error. The SST-CP using this method can compensate for specified machining errors and suppress serious deterioration. To verify the proposed method, several test pieces were manufactured, and their characteristics were measured using a VNA. These results indicated that the insertion losses were approximately 0.75 dB, and the input return losses and the crosstalk of the left- and right-hand circular polarization were greater than 20 dB at 220–245 GHz on 300 K. Moreover, a 230 GHz SST-CP was developed by the proposed method and installed in a 1.85-m radio telescope receiver systems, and then had used for scientific observations during one observation season without any problems. These achievements demonstrate the successful development of a 230 GHz SST-CP for radio astronomical observations. Furthermore, the proposed method can be applicable for observations in higher frequency bands, such as 345 GHz. 相似文献
66.
Qingshan Zhu Kazuhisa Shobu Eiji Tani Kazushi Kishi Seiki Umebayashi 《Journal of the American Ceramic Society》1999,82(8):2276-2278
Molybdenum carbosilicide composites (SiC-Mo≤5 Si3 C≤1 ) were fabricated via the melt-infiltration process. The fracture behavior of the composites was studied from room temperature up to 1800°C in 1 atm (∼105 Pa) of argon. The bend strength of the composites slightly increased at ∼1200°C, because of the brittle-ductile transition of the intermetallic phase. The composites retained ∼90% of their room-temperature strength, even at 1700°C. Compressive creep tests were performed over a temperature range of 1760°-1850°C and a stress range of 200–250 MPa. The creep rate of the SiC-Mo≤5 Si3 C≤1 composites was approximately an order of magnitude higher than that of reaction-bonded SiC. 相似文献
67.
Yuko Kinowaki Towako Taguchi Iichiroh Onishi Susumu Kirimura Masanobu Kitagawa Kouhei Yamamoto 《International journal of molecular sciences》2021,22(17)
Ferroptosis, a term first proposed in 2012, is iron-dependent, non-apoptotic regulatory cell death induced by erastin. Ferroptosis was originally discovered during synthetic lethal screening for drugs sensitive to RAS mutant cells, and is closely related to synthetic lethality. Ferroptosis sensitizes cancer stem cells and tumors that undergo epithelial−mesenchymal transition and are resistant to anticancer drugs or targeted therapy. Therefore, ferroptosis-inducing molecules are attractive new research targets. In contrast, synthetic lethal strategies approach mechanisms and genetic abnormalities that cannot be directly targeted by conventional therapeutic strategies, such as RAS mutations, hypoxia, and abnormalities in the metabolic environment. They also target the environment and conditions specific to malignant cells, have a low toxicity to normal cells, and can be used in combination with known drugs to produce new ones. However, the concept of synthetic lethality has not been widely adopted with ferroptosis. In this review, we surveyed the literature on ferroptosis-related factors and synthetic lethality to examine the potential therapeutic targets in ferroptosis-related molecules, focusing on factors related to synthetic lethality, discovery methods, clinical application stages, and issues in drug discovery. 相似文献
68.
Ultramultiple roundtrips of surface acoustic wave on sphere realizing innovation of gas sensors 总被引:1,自引:0,他引:1
Yamanaka K Ishikawa S Nakaso N Takeda N Sim DY Mihara T Mizukami A Satoh I Akao S Tsukahara Y 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2006,53(4):793-801
A thin beam of wave usually diverges due to diffraction, which is a limitation of any device using such waves. However, a surface acoustic wave (SAW) on a sphere with an appropriate aperture does not diverge but is naturally collimated, realizing ultramultiple roundtrips along an equator of the sphere. This effect is caused by the balance between diffraction and focusing on a spherical surface, and it enables realization of high-performance ball SAW sensors. The advantage of ball SAW is most fully appreciated when applied to a very thin sensitive film for which the multiple-roundtrip enhances the sensitivity, but the attenuation loss is not very large. It is exemplified in a hydrogen gas sensor that realizes a wide sensing range of 10 ppm to 100% for the first time, and realizes relatively fast response time of 20 s without heating the sensitive film. 相似文献
69.
70.