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排序方式: 共有408条查询结果,搜索用时 15 毫秒
1.
Yeong‐Tarng Shieh Pei‐Yu Tai Chih‐Chia Cheng 《Journal of polymer science. Part A, Polymer chemistry》2019,57(21):2149-2156
Poly(methyl methacrylate) (PMMA) nanoparticles with a sensitive CO2‐responsive hydrophilic/hydrophobic surface that confers controlled dispersion and aggregation in water were prepared by emulsion polymerization at 50 °C under CO2 bubbling using amphiphilic diblock copolymers of 2‐dimethylaminoethyl methacrylate (DMAEMA) and N‐isopropyl acrylamide (NIPAAm) as an emulsifier. The amphiphilicity of the hydrophobic–hydrophilic diblock copolymer at 50 °C was triggered by CO2 bubbling in water and enabled the copolymer to serve as an emulsifier. The resulting PMMA nanoparticles were spherical, approximately 100 nm in diameter and exhibited sensitive CO2/N2‐responsive dispersion/aggregation in water. Using copolymers with a longer PNIPAAm block length as an emulsifier resulted in smaller particles. A higher concentration of copolymer emulsifier led to particles with a stickier surface. Given its simple preparation and reversible CO2‐triggered amphiphilic behavior, this newly developed block copolymer emulsifier offers a highly efficient route toward the fabrication of sensitive CO2‐stimuli responsive polymeric nanoparticle dispersions. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2149–2156 相似文献
2.
I. J. Lozada J. C. Osorio D. V. Griffiths M. Cerrolaza 《Numerical Methods for Partial Differential Equations》2006,22(2):296-316
The semi‐analytical integration of an 8‐node plane strain finite element stiffness matrix is presented in this work. The element is assumed to be super‐parametric, having straight sides. Before carrying out the integration, the integral expressions are classified into several groups, thus avoiding duplication of calculations. Symbolic manipulation and integration is used to obtain the basic formulae to evaluate the stiffness matrix. Then, the resulting expressions are postprocessed, optimized, and simplified in order to reduce the computation time. Maple symbolic‐manipulation software was used to generate the closed expressions and to develop the corresponding Fortran code. Comparisons between semi‐analytical integration and numerical integration were made. It was demonstrated that semi‐analytical integration required less CPU time than conventional numerical integration (using Gaussian‐Legendre quadrature) to obtain the stiffness matrix. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2006 相似文献
3.
Dongliang Gao Andrey Novitsky Tianhang Zhang Fook Chiong Cheong Lei Gao Chwee Teck Lim Boris Luk'yanchuk Cheng‐Wei Qiu 《Laser \u0026amp; Photonics Reviews》2015,9(1):75-82
This paper investigates the singular optics of nonparaxial light beams in the near field when the light behaves as a tractor beam. New insights into the optical pulling force, which is usually represented by integrating the stress tensor at a black box enclosing the object, are interpreted by the optical singularity of the Poynting vector. The negative nonconservative pulling force originates from the transfer of the azimuthal Poynting vector to the longitudinal component partly owing to the presence of a scatterer. The separatrice pattern and singularity shifts of the Poynting vector unanimously exhibit a differentiable near‐field distribution in the presence of optical pulling force. A new method is established to calculate the near‐field optical force using the differential Poynting vector in the far field. The results obtained provide a clear physical interpretation of the light–matter interaction and manifest the significance of singular optics in manipulating objects.
4.
J.-H. Huang S.-Y. Zhu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(3):557-575
The normalized second-order
correlation of the emission fields from a driven four-level atomic
ensemble is investigated theoretically by using the state vector
method. The violation of Cauchy-Schwarz inequality, which indicates
the establishment of non-classical correlation between two emission
fields, has been found. The effects of various decays and time delay
on the correlation are discussed in detail, which are helpful in
finding the ways to obtain high non-classical correlation. This
technique for the generation of non-classical light is operable
based on the current experimental technology and will lead to some
potential applications in quantum information science. 相似文献
5.
L. Ye 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):413-416
We propose two schemes for generating a four-atom cluster state in a thermal
cavity. With the assistant of a strong classical field the
photon-number-dependent parts in the effective Hamiltonian are canceled.
Thus the schemes are insensitive to the thermal field. The schemes can also
be used to generate the cluster state for the trapped ions in thermal
motion. 相似文献
6.
We review the recent progress on the magnetic skyrmions in chiral magnetic materials.The magnetic skyrmion is a topological spin configuration with localized spatial extent,which could be thought of as an emergent rigid particle,owing to its particular topological and chiral properties.Static skyrmionic configurations have been found in various materials with different transport and thermodynamic properties.The magnetic skyrmions respond to externally applied fields in a very unique way,and their coupling to other quasiparticles in solid-state systems gives rise to the emergent electrodynamics.Being not only theoretically important,the magnetic skyrmion is also very promising to be the information carrier in next generation spintronic devices. 相似文献
7.
Band‐Gap Manipulations of Monolayer Graphene by Phenyl Radical Adsorptions: A Density Functional Theory Study 下载免费PDF全文
Phenyl radical (Ph.) adsorption on monolayer graphene sheets is used to investigate the band‐gap manipulation of graphene through density functional theory. Adsorption of a single Ph. on graphene breaks the aromatic π‐bond and generates an unpaired electron, which is delocalized to the ortho or para position. Adsorption of a second radical at the ortho or para position saturates the radical by electron pairing and results in semiconducting graphene. Adsorption of a second radical at the ortho position (ortho–ortho pairing) is found to be more favorable than adsorption at the para position (ortho–para pairing), and the ortho–ortho pairing has stronger effects on band‐gap opening compared with ortho–para pairing. Adsorption of even numbers of Ph. on graphene by ortho–ortho and ortho–para pairings, in general, increases the band gap. Our study shows promise of band‐gap manipulation in monolayer graphene by Ph. adsorption, leading to potential wider applications of graphene. 相似文献
8.
Dr. Hua Su Ben Niu Haoran Li Dr. Fei Liu Tinglian Yuan Prof. Hong-Yuan Chen Prof. Wei Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(43):19371-19376
The ordered assembly of molecules within a specific space of nanoscale, such as a surface, holds great promise in advanced micro-/nanostructure fabrication for various applications. Herein, we demonstrate the evanescent wave (EW)-guided organization of small molecules into a long-range ordered nanowire (NW) array. Experiment and simulation revealed that the orientation and periodicity of the NW array were feasibly regulated by altering the propagation direction and the wavelength of EW. The generality of this approach was demonstrated by using different molecule precursors. While existing studies on EW often took advantages of its near-field property for optical sensing, this work demonstrated the photochemical power of EW in the guided-assembly of small molecules for the first time. It also provides an enlightening avenue to periodic structure with fluorescence, promising for super-resolution microscopy and important devices applicable to optical and bio-related fields. 相似文献
9.
Meng Su Feifei Qin Zeying Zhang Bingda Chen Qi Pan Zhandong Huang Zheren Cai Zhipeng Zhao Xiaotian Hu Dominique Derome Jan Carmeliet Yanlin Song 《Angewandte Chemie (International ed. in English)》2020,59(34):14234-14240
A key issue of micro/nano devices is how to integrate micro/nanostructures with specified chemical components onto various curved surfaces. Hydrodynamic printing of micro/nanostructures on three‐dimensional curved surfaces is achieved with a strategy that combines template‐induced hydrodynamic printing and self‐assembly of nanoparticles (NPs). Non‐lithography flexible wall‐shaped templates are replicated with microscale features by dicing a trench‐shaped silicon wafer. Arising from the capillary pumped function between the template and curved substrates, NPs in the colloidal suspension self‐assemble into close‐packed micro/nanostructures without a gravity effect. Theoretical analysis with the lattice Boltzmann model reveals the fundamental principles of the hydrodynamic assembly process. Spiral linear structures achieved by two kinds of fluorescent NPs show non‐interfering photoluminescence properties, while the waveguide and photoluminescence are confirmed in 3D curved space. The printed multiconstituent micro/nanostructures with single‐NP resolution may serve as a general platform for optoelectronics beyond flat surfaces. 相似文献
10.
《Surface Science Reports》2020,75(4):100509
It was a long-cherished dream for chemists to take a direct look at chemical bonding, a fundamental component of chemistry. This dream was finally accomplished by the state-of-the-art noncontact atomic force microscopy (NC-AFM) equipped with qPlus force sensors and carbon monoxide (CO) functionalized tips. The resolved interconnectivity between atoms and molecules in NC-AFM frequency shift images is interpreted as chemical bonding, providing essential knowledge of the bond length, bond angle and even bond order. The featured contrast of different chemical bonds can serve as fingerprints for further interpretation of chemical structures toward unknown species synthesized on surfaces. This breakthrough enriches characterization tools for surface science and brings our understanding of on-surface reactions to a new level. Beyond bond imaging, the application of NC-AFM has been extended to quantifying interatomic interactions, identifying three-dimensional nanostructures, manipulating molecules and reactions, as well as determining molecular electronic characteristics. Moreover, some recent efforts address the improvement of the usability and versatility of the bond-resolved NC-AFM technique, including high-resolution molecular investigation on bulk insulators, application-specific tip modification, stable bond imaging above liquid helium temperature and autonomous experimentation implemented by artificial intelligence. 相似文献