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排序方式: 共有56条查询结果,搜索用时 46 毫秒
1.
Utilizing Iron's Attractive Chemical and Magnetic Properties in Microrocket Design,Extended Motion,and Unique Performance
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Emil Karshalev Chuanrui Chen Gregor Marolt Aída Martín Isaac Campos Roxanne Castillo Tianlong Wu Joseph Wang 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(21)
All‐in‐one material for microrocket propulsion featuring acid‐based bubble generation and magnetic guidance is presented. Electrochemically deposited iron serves as both a propellant, toward highly efficient self‐propulsion in acidic environments, and as a magnetic component enabling complete motion control. The new microrockets display longer lifetime and higher propulsion efficiency compared to previously reported active metal zinc‐based microrockets due to the chemical properties of iron and the unique structure of the microrockets. These iron‐based microrockets also demonstrate unique and attractive cargo towing and autonomous release capabilities. The latter is realized upon loss of the magnetic properties due to acid‐driven iron dissolution. More interestingly, these bubble‐propelled microrockets assemble via magnetic interactions into a variety of complex configurations and train structures, which enrich the behavior of micromachines. Modeling of the magnetic forces during the microrocket assembly and cargo capture confirms these unique experimentally observed assembly and cargo‐towing behaviors. These findings provide a new concept of blending propellant and magnetic components into one, toward simplifying the design and fabrication of artificial micro/nanomachines, realizing new functions and capabilities for a variety of future applications. 相似文献
2.
This article reviews Computer Mediated Communications (CMC), encompassing the technology and its evaluation, with emphasis on factors crucial to the introduction of this technology in developing countries. The discussion of some promising application areas for developing countries includes education, networks of specialists, international committees and trade groups, and crisis detection and management. Also included is a summary of factors important to fostering and evolving the utilization of CMC technology. 相似文献
3.
The effect of unsaturated fatty acids on the abundance of Δ6 desaturase (D6D) mRNA and the fatty acid composition of HepG2
cell membranes was examined. Supplementation of HepG2 cells with oleic acid (18:1n-9, OA), linoleic acid (18:2n-6, LA), α-linolenic
acid (18:3n-3, ALA), arachidonic acid (20:4n-6, AA) or eicosapentaenoic acid (20:5n-3, EPA) reduced D6D mRNA abundance by
39 ± 6.6, 40 ± 2.2, 31 ± 5.2, 55 ± 4.8, and 52 ± 5.0%, respectively, compared with control cells. Despite the reduction in
D6D mRNA abundance, the level of D6D conversion products (20:3n-9, EPA and AA) in OA, ALA and LA supplemented cells, respectively,
was elevated above that in control cells. Our results suggest that although unsaturated fatty acids decrease the abundance
of D6D mRNA by as much as 50%, the conversion of polyunsaturated fatty acids and accumulation of long chain polyunsaturated
fatty acids (LCPUFA) in HepG2 cell phospholipids continues to occur. 相似文献
4.
Some courts in recent years have tarnished their credibility by willingly and blindly adopting the theory of repressed memory. Such acceptance can destroy the reputations of falsely accused individuals, and, by failing to pay due attention to scientific evidence, gives credence to pseudoscience and demeans the scientific method. This paper was written to inform judges and attorneys about the relevant evidence, which shows that: (a) the concepts of repressed and recovered memory are not generally accepted in the psychological and psychiatric community; (b) the studies cited to support these concepts reveal significant flaws; (c) much empirical evidence has been accumulated against the theory of repression; (d) the studies using the best methodology offer the least support for the repression hypothesis; and (e) there is no evidence that recovered memories accurately reveal the specifics of long-ago events. Repressed- and recovered-memory theory is not supported by science. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
Peculiar crystallization kinetics of biodegradable poly(lactic acid)/poly(propylene carbonate) blends
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Maria Laura Di Lorenzo Roxanne Ovyn Mario Malinconico Paolo Rubino Yves Grohens 《Polymer Engineering and Science》2015,55(12):2698-2705
Binary blends of poly(lactic acid) (PLA) and poly(propylene carbonate) (PPC) were found to display a peculiar crystallization kinetics. The two biodegradable polymers were blended by melt mixing, to obtain binary blends at various compositions. Temperature‐modulated calorimetry and dynamic‐mechanical analysis indicated that the blend components are partially miscible, and display two separate glass transitions, at temperatures intermediate to those of the plain polymers. Electron microscopy analysis disclosed the morphology of PLA/PPC blends, made of PPC‐rich particles finely dispersed within the PLA‐rich matrix. The possible establishment of interactions between the functional groups of the two polymers upon melt mixing has been hypothesized as the reason for partial miscibility and compatibility of the two biodegradable polymers. The PLA/PPC blends display good mechanical properties, with enhanced performance at rupture compared with plain PLA. Most importantly, the addition of PPC affects also the crystallization kinetics of PLA, since the more mobile PPC chains favor diffusion of the stiffer PLA chain segments towards the growing crystals, which fastens the spherulite growth rate of PLA. Such positive influence of an amorphous polymer on crystal growth rate has been demonstrated here for the first time in blends that display phase‐separation in the melt. POLYM. ENG. SCI., 55:2698–2705, 2015. © 2015 Society of Plastics Engineers 相似文献
6.
Duarte IF Stanley EG Holmes E Lindon JC Gil AM Tang H Ferdinand R McKee CG Nicholson JK Vilca-Melendez H Heaton N Murphy GM 《Analytical chemistry》2005,77(17):5570-5578
This work presents the first application of high-resolution magic angle spinning (HR-MAS) 1H NMR spectroscopy to human liver biopsy samples, allowing a determination of their metabolic profiles before removal from donors, during cold perfusion, and after implantation into recipients. The assignment of peaks observed in the 1H HR-MAS NMR spectra was aided by the use of two-dimensional J-resolved, TOCSY and 1H-13C HMQC spectra. The spectra were dominated by resonances from triglycerides, phospholipids, and glycogen and from a variety of small molecules including glycerophosphocholine (GPC), glucose, lactate, creatine, acetate, amino acids, and nucleoside-related compounds such as uridine and adenosine. In agreement with histological data obtained on the same biopsies, two of the six livers were found to contain high amounts of triglycerides by NMR spectroscopy, which also indicated that these tissues contained a higher degree of unsaturated lipids and a lower proportion of phospholipids and low molecular weight compounds. Additionally, proton T2 relaxation times indicated two populations of lipids, a higher mobility triglyceride fraction and a lower mobility phospholipid fraction, the proportions of which changed according to the degree of fat content. GPC was found to decrease from the pretransplant to the posttransplant biopsy of all livers except for one with a histologically confirmed high lipid content, and this might represent a biomarker of liver function posttransplantation. NMR signals produced by the liver preservation solution were clearly detected in the cold perfusion stage biopsies of all livers but remained in the posttransplant spectra of only the two livers with a high lipid content and were prominent mainly in the graft that later developed primary graft dysfunction. This study has shown biochemical differences between livers used for transplants that can be related to the degree and type of lipid composition. This technology might therefore provide a novel screening approach for donor organ quality and a means to assess function in the recipient after transplantation. 相似文献
7.
Di Wu Yilong Yang Pengcheng Xu Duo Xu Yang Liu Roxanne Castillo Ran Yan Jie Ren George Zhou Chaoyong Liu Meng Qin Juanjuan Du Lihua Hou Irvin Chen Chunsheng Kang Lihua Jin Jing Wen Wei Chen Yunfeng Lu 《Advanced materials (Deerfield Beach, Fla.)》2019,31(39)
Cells transport mass dynamically, crossing cell membranes to maintain metabolism and systemic homeostasis, through which biomolecules are also delivered to cells for gene editing, cell reprograming, therapy, and other purposes. Quantifying the translocation kinetics is fundamentally and clinically essential, but remains limited by fluorescence‐based technologies, which are semi‐quantitative and only provide kinetics information at cellular level or in discrete time. Herein, a real‐time method of quantifying cell internalization kinetics is reported using functionalized firefly‐luciferase nanocapsules as the probe. This quantitative assay will facilitate the rational design of delivery vectors and enable high‐throughput screening of peptides and other functional molecules, constituting an effective tool for broad applications, including drug development and cancer therapy. 相似文献
8.
Roxanne M. Broadway 《Journal of chemical ecology》1989,15(7):2101-2113
In their larval luminal midgut fluid,Trichoplusia ni (Lepidoptera: Noctuidae) andPieris rapae (Lepidoptera: Pieridae) contain endopeptidases as their primary proteases. Neither species has detectable exopeptidase activity. Studies using enzyme-specific substrates and inhibitors demonstrate that the endopeptidases are serine proteinases (both trypsinlike and chymotrypsinlike) with histidine at the active site. Optimal pH for the tryptic and chymotryptic activity is 8.5 and 8.0, respectively, forT. ni. and 8.0 and 9.0, respectively, forP. rapae. The efficiency of proteolytic digestion (as measured by the rate of in vitro digestion of a standard protein by the midgut luminal fluid) is positively correlated with the larval dietary protein requirement and is significantly influenced by the ratios of tryptic to chymotryptic activity present in the gut lumen of these two species of Lepidoptera. 相似文献
9.
This research examined the impact of goal-setting conditions on memory beliefs and performance among older and younger adults. After baseline recall and assessment of beliefs, participants were assigned to goal-setting, goals plus feedback, or control. Then, additional recall trials were followed by repeated memory beliefs assessments. For both younger and older adults, performance, motivation, and self-efficacy were affected positively by goal-setting. The impact of goals plus feedback was mixed and varied as a function of age and dependent measure. Success rates for reaching memory goals, which were low for the older adults, may have been a factor in these results. Adults' self-set recall goals were predicted initially by baseline performance and self-efficacy. On the final trial, goals were predicted by last trial performance, self-efficacy, and control beliefs. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
Paul H. Falcone Aaron C. Tribby Roxanne M. Vogel Jordan M. Joy Jordan R. Moon Chantelle A. Slayton Micah M. Henigman Joanne A. Lasrado Brandon J. Lewis Brenda A. Fonseca Kristin M. Nieman Kelli A. Herrlinger 《Journal of the International Society of Sports Nutrition》2018,15(1):58