检索结果-内蒙古大学图书馆

Ferromagnetic Switching of Knotted Vector Fields in Liquid Crystal Colloids

Physical Review Letters 2015年第9期115卷 097802-097802页

作者： Qiaoxuan Zhang Paul J. Ackerman Qingkun Liu Ivan I. Smalyukh Department of Physics University of Colorado Boulder Colorado 80309 USA Materials Science and Engineering Program University of Colorado Boulder Colorado 80309 USA Department of Electrical Computer and Energy Engineering University of Colorado Boulder Colorado 80309 USA Liquid Crystal Materials Research Center University of Colorado Boulder Colorado 80309 USA Renewable and Sustainable Energy Institute National Renewable Energy Laboratory and University of Colorado Boulder Colorado 80309 USA

We experimentally realize polydomain and monodomain chiral ferromagnetic liquid crystal colloids that exhibit solitonic and knotted vector field configurations. Formed by dispersions of ferromagnetic nanoplatelets in chiral nematic liquid crystals, these colloidal ferromagnets exhibit spontaneous long-range alignment of magnetic dipole moments of individual platelets, giving rise to a continuum of the magnetization field M(r). Competing effects of surface confinement and chirality prompt spontaneous formation and enable the optical generation of localized twisted solitonic structures with double-twist tubes and torus knots of M(r), which exhibit a strong sensitivity to the direction of weak magnetic fields ∼1 mT. Numerical modeling, implemented through free energy minimization to arrive at a field-dependent three-dimensional M(r), shows a good agreement with experiments and provides insights into the torus knot topology of observed field configurations and the corresponding physical underpinnings.

关键词： Chirality Ferromagnetism Colloids Liquid crystals

来源：评论

学校读者我要写书评

暂无评论

Framework Cationization by Preemptive Coordination of Open Metal Sites for Anion‐Exchange Encapsulation of Nucleotides and Coenzymes

引用

Angewandte Chemie 2016年第8期128卷

作者： Xiang Zhao Chengyu Mao Karen Tu Luong Qipu Lin Quan‐Guo Zhai Pingyun Feng Xianhui Bu Department of Chemistry and Biochemistry California State University Long Beach 1250 Bellflower Boulevard Long Beach CA 90840 USA Materials Science and Engineering Program University of California Riverside CA 92521 USA Department of Chemistry University of California Riverside CA 92521 USA

Cationic frameworks can selectively trap anions through ion exchange, and have applications in ion chromatography and drug delivery. However, cationic frameworks are much rarer than anionic or neutral ones. Herein, we propose a concept, preemptive coordination (PC), for targeting positively charged metal–organic frameworks (P‐MOFs). PC refers to proactive blocking of metal coordination sites to preclude their occupation by neutralizing ligands such as OH − . We use 20 MOFs to show that this PC concept is an effective approach for developing P‐MOFs whose high stability, porosity, and anion‐exchange capability allow immobilization of anionic nucleotides and coenzymes, in addition to charge‐ and size‐selective capture or separation of organic dyes. The CO 2 and C 2 H 2 uptake capacity of 117.9 cm 3 g −1 and 148.5 cm 3 g −1 , respectively, at 273 K and 1 atm, is exceptionally high among cationic framework materials.

关键词： Anionentrennung Ionenaustausch Kationische Gerüste Metall-organische Gerüste

来源：评论

学校读者我要写书评

暂无评论

Experimental realization of crossover in shape and director field of nematic tactoids

引用

Physical Review E 2015年第4期91卷 042507-042507页

作者： Vida Jamali Natnael Behabtu Bohdan Senyuk J. Alex Lee Ivan I. Smalyukh Paul van der Schoot Matteo Pasquali Department of Chemical and Biomolecular Engineering Rice University Houston Texas 77005 USA Department of Physics University of Colorado at Boulder Boulder Colorado 80309 USA Department of Electrical Computer and Energy Engineering and Materials Science and Engineering Program and Liquid Crystals Materials Research Center University of Colorado at Boulder Colorado 80309 USA Renewable and Sustainable Energy Institute National Renewable Energy Laboratory and University of Colorado Boulder Colorado 80309 USA Polymer Physics Group for Theory of Polymers and Soft Matter Group Department of Applied Physics Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands Institute for Theoretical Physics Utrecht University Leuvenlaan 4 3584 CE Utrecht The Netherlands Department of Chemistry Department of Materials Science and NanoEngineering The Smalley Institute for Nanoscale Science and Technology Rice University Houston Texas 77005 USA

Spindle-shaped nematic droplets (tactoids) form in solutions of rod-like molecules at the onset of the liquid crystalline phase. Their unique shape and internal structure result from the interplay of the elastic deformation of the nematic and anisotropic surface forces. The balance of these forces dictates that tactoids must display a continuous variation in aspect ratio and director-field configuration. Yet, such continuous transition has eluded observation for decades: tactoids have displayed either a bipolar configuration with particles aligned parallel to the droplet interface or a homogeneous configuration with particles aligned parallel to the long axis of the tactoid. Here, we report the first observation of the continuous transition in shape and director-field configuration of tactoids in true solutions of carbon nanotubes in chlorosulfonic acid. This observation is possible because the exceptional length of carbon nanotubes shifts the transition to a size range that can be visualized by optical microscopy. Polarization micrographs yield the interfacial and elastic properties of the system. Absorbance anisotropy measurements provide the highest nematic order parameter (S=0.79) measured to date for a nematic phase of carbon nanotubes at coexistence with its isotropic phase.

关键词： Carbon nanotubes

来源：评论

学校读者我要写书评

暂无评论

Effect of student-centered programs on retention of engineering students 122

Effect of student-centered programs on retention of engineer...

引用

2015 122nd ASEE Annual Conference and Exposition

作者： Ernzen, John Judson, Eugene Krause, Stephen J. Collofello, James Chen, Ying-Chih Beeley, Kendra Rae Culbertson, Robert J. Mary Lou Fulton Teachers College Arizona State University United States Materials Science Program Fulton School of Engineering Arizona State University United States Arizona State University United States Division of Teacher Preparation Mary Lou Fulton Teachers College Arizona State University TempeAZ United States Physics Department Arizona State University United States

来源：评论

学校读者我要写书评

暂无评论

Effects of nanoscale embedded Schottky barriers on carrier dynamics in ErAs:GaAs composite systems

引用

Physical Review B 2015年第13期92卷 134303-134303页

作者： S. N. Gilbert Corder J. K. Kawasaki C. J. Palmstrøm H. T. Krzyżanowska N. H. Tolk Interdisciplinary Materials Science Program Vanderbilt University Nashville Tennessee 37235 USA Materials Department University of California Santa Barbara Santa Barbara California 93106 USA Department of Electrical Engineering University of California Santa Barbara Santa Barbara California 93106 USA Department of Physics and Astronomy Vanderbilt University Nashville Tennessee 37235 USA

Semiconducting GaAs is widely used in microwave and millimeter integrated circuits, infrared LEDs, lasers, and solar cells. Introducing semimetallic ErAs nanoparticles provides a way to controllably tune the optical and electronic properties of GaAs. We show that for high volume fractions (0.5%–10%) of ErAs nanoparticles embedded in GaAs, the relaxation dynamics indicates that ErAs forms discrete states in the GaAs band gap. For specific carrier momentum conditions, the localized Schottky states may be occupied, exhibit carrier trapping, or inject carriers into the GaAs conduction band. Carrier occupation and scattering from the Schottky states has not previously been reported in optical studies of this system. The scattering mechanism is observed to be active above an occupation threshold where the excited carrier density exceeds the trap density. The array of nanoparticle densities and the characterization of the relaxation pathways at multiple carrier excitation energies represents the most complete fundamental investigation of these systems to date.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Needle-implantable, wireless biosensor for continuous glucose monitoring 12

Needle-implantable, wireless biosensor for continuous glucos...

引用

12th IEEE International Conference on Wearable and Implantable Body Sensor Networks, BSN 2015

作者： Vaddiraju, Santhisagar Kastellorizios, Michail Legassey, Allen Burgess, Diane Jain, Faquir Papadimitrakopoulos, Fotios Biorasis Inc. Technology Incubation Program University of Connecticut StorrsCT06268 United States Nanomaterials Optoelectronics Laboratory Institute of Materials Science University of Connecticut StorrsCT06269 United States Electrical and Computer Engineering University of Connecticut StorrsCT06269 United States Department of Pharmaceutical Sciences University of Connecticut StorrsCT06269 United States Department of Chemistry University of Connecticut StorrsCT06269 United States

ISBN: (纸本)9781467372015

Unlike non-invasive and minimally invasive continuous monitoring of glucose (CGM) devices, invasive devices require less rigorous calibration and exhibit smaller subject-to-subject variability. Biorasis, Inc. and the University of Connecticut are developing a totally implantable CGM device. Glucowizzard™ is engineered at the smallest possible footprint (0.5 × 0.5 × 5 mm). This miniaturization is made possible by utilizing light both for powering and wireless communication. In addition, Glucowizzard™ utilizes 'smart' hydrogel coatings intended for localized release of various tissue response modifiers for effective control of negative tissue responses. The use of light-based powering and communication together with advanced microelectronic design rules has allowed the fabrication of truly miniaturized CGM device. The drug delivery coating has enabled substantial reduction of negative tissue responses for up to 1 month in small as well as large animals (rats and minipigs). The functionality of Glucowizzard™ has been demonstrated in vivo in both rats and minipigs. © 2015 IEEE.

关键词： Rats

来源：评论

学校读者我要写书评

暂无评论

Functionalized nafen™ alumina nanofiber (ANF) reinforced polyamide 6 nanocomposites: Mechanical, thermal and flame retardant properties

Functionalized nafen™ alumina nanofiber (ANF) reinforced po...

引用

SAMPE Baltimore 2015 Conference and Exhibition

作者： Wu, Hao Krifa, Mourad Koo, Joseph H. University of Texas at Austin AustinTX78712 United States Materials Science and Engineering Program Texas Materials Institute University of Texas at Austin 204 E. Dean Keeton St. C2200 AustinTX78712 United States School of Human Ecology-Textile and Apparel Technology University of Texas at Austin 1 University Station A2700 AustinTX78712 United States Department of Mechanical Engineering University of Texas at Austin 204 E. Dean Keeton St. C2200 AustinTX78712 United States

ISBN: (纸本)9781934551196

Nafen™ alumina nanofibers (ANF) have the potential to improve material's mechanical and flame retardant properties when uniformly dispersed in the polymer matrix. In this study, various concentrations of Nafen™ ANF were incorporated in polyamide 6 (PA6) nanocomposites by co-rotating twin screw extrusion. Before the extrusion process, the ANFs were prepared using both ultra-sonication and planetary centrifugal mixing in order to pulverize agglomerates and obtain separated alumina nanofibers. The separated ANFs were then functionalized in order to obtain good interfacial properties with the PA6 matrix. TEM images indicate a homogeneous dispersion of ANF within PA6. There is no significant difference in both FTIR spectra and thermal stabilities tested by TGA and DSC. Low concentrations of ANF have minimal effect on flammability, further increasing the ANF concentration may lead to lower flammability but the results in this report are not significant. Mechanical tensile test results are also reported. Copyright 2015. Used by the Society of the Advancement of Material and Process engineering with permission.

关键词： Nanocomposites

来源：评论

学校读者我要写书评

暂无评论

Fabrication of periodically aligned vertical singlecrystalline anatase TiO2 nanotubes with perfect hexagonal open-ends using chemical capping materials

引用

Nano Research 2014年第1期7卷 104-109页

作者： Hui Song Kyubong Jo Bock Young Jung Gun Young Jung School of Materials Science and Engineering Gwangju Institute of Science and Technology (GIST) Gwangju Republic of Korea Department of Chemistry and Interdisciplinary Program of Integrated Biotechnology Sogang University Seoul Republic of Korea Department of General Dentistry College of Dentistry Yonsei University Seoul Republic of Korea

A vertically aligned anatase TiO2 （A-TiO2） nanotube array has been fabricated by coating a ZnO nanorod （NR） template with a TiO2 precursor solution. After coating, the ZnO NR cores were selectively etched in an acidic environment to form TiO2 nanotubes （NTs）. More specifically, after growing the ZnO NRs via a hydrothermal method, one drop of the TiO2 precursor solution was cast to coat the ZnO NRs, the tops of which were previously covered with chemical capping materials by electrostatic interaction, and then the sample was sintered. Finally, the sample was immersed in an acidic solution resulting in selective etching of the ZnO NR cores. Thus, only TiO2 NTs remained on the substrate. The capping material is effectively used to create a perfect, hexagonal open-ended TiO2 NT array, which interestingly extends onset absorption towards the visible region.

关键词： TiO2 nanotubes chemical capping material ZnO nanorod template laser interferencelithography

来源：评论

学校读者我要写书评

暂无评论

Direct observation of symmetry-specific precession in a ferrimagnet

引用

Physical Review B 2015年第10期92卷 104402-104402页

作者： P. Warnicke E. Stavitski J.-S. Lee A. Yang Z. Chen X. Zuo S. Zohar W. E. Bailey V. G. Harris D. A. Arena Photon Sciences Directorate Brookhaven National Laboratory Upton New York 11973 USA Department of Electrical and Computer Engineering Northeastern University Boston Massachusetts 02115 USA Materials Science Program Department of Applied Physics Columbia University New York New York 10027 USA

Here we demonstrate an experimental observation of GHz-scale spin dynamics resolved to sublattice octahedral (Oh) tetrahedral (Td) sites in a spinel ferrimagnet, in this case a Mn-ferrite thin film. X-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) are used, in combination with multiplet calculations, to uniquely identify the spectral signature from Mn2+ and Fe2+,3+ on Oh and Td lattice sites. With the sample under rf excitation, the spin alignment of the sublattices is tracked with time-resolved XMCD (TR-XMCD). The spin alignment of the sublattices is mostly antiferromagnetic. The phase difference between the Oh Fe2+ [Oh Fe3+] and Td Mn2+ sites is 181.2±3.8∘ [183.3∘±3.7∘] at 150 K and 186.6±2.2∘ [182.0∘±2.2∘] at 300 K. Such direct measurement of the dynamic coupling, exchange stiffness, and damping enabled by TR-XMCD across sublattices will be essential for optimizing the development of future-generation microwave devices.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Multi-layered covert QR codes for increased capacity and security

引用

International Journal of Computers and Applications 2015年第1期37卷 17-27页

作者： Meruga, Jeevan M. Fountain, Carly Kellar, Jon Crawford, Grant Baride, Aravind May, P. Stanley Cross, William Hoover, Randy Materials Engineering and Science Program South Dakota School of Mines and Technology 515 E. St. Joseph St Rapid CitySD57701 United States Department of Mathematics and Computer Science South Dakota School of Mines and Technology University of South Dakota United States Department of Electrical and Computer Engineering South Dakota School of Mines and Technology University of South Dakota United States Department of Chemistry University of South Dakota United States

Quick Response (QR) codes, used in marketing, warehouse management, product tracking, and other applications, are usually only comprised of visible black and white modules. The goal of this research is the creation of covert, color QR codes for increased data capacity, and security. This goal was met by layering QR codes, each of a unique color, printing the covert versions of the color QR codes, upconverting the covert codes into visible codes and unlayering them to take advantage of the various color channels present. It was shown that color layering of the QR codes effectively increased the data capacity by three times that of a traditional QR code, while the covert nature of the code provides added security. Finally, it was also demonstrated that a layered QR code with six base colors (using color intensity variations) could further increase QR code data capacity. © 2015 Taylor and Francis.

关键词： Color

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：