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Attraction symmetry

Kai Xing, Ruiqing Fan, Jiaqi Wang, Siqi Zhang, Kai Feng, Xi Du, Yang Song, Ping Wang, Yulin Yang
MOF-based sensors capable of effectively and stably detecting toxic species in water have attracted huge attention in terms of improving environmental monitoring levels and water quality. Combining the flexibility of structure and modifying of pore surface, a multi-walled divider installation (MWDI) strategy is proposed and used for property enhancement. We herein report three metal-organic frameworks (MOFs) 1-3 based on a C3 symmetry organic phosphonic ligand with topology increased from 3,6-connected to 3,8-connected...
May 23, 2017: ACS Applied Materials & Interfaces
Katarzyna Czarnobaj, Magdalena Prokopowicz, Wiesław Sawicki
The purpose of this study was to evaluate the surface mineralization activity and in vitro drug behavior potential of two forms of mesoporous silica: powder and granulate. Ordered mesoporous SiO2 powder was synthesized by surfactant-assisted sol-gel process using tetraethoxysilane as a silica precursor and hexadecyltrimethylammonium bromide as the structure-directing agent. The granulate was prepared using silica powder and ethyl cellulose as a binding agent. Metronidazole (MT)-an anti-inflammatory substance and doxorubicin hydrochloride (ChD)-an anti-cancer drug were chosen as drug models for delivery studies...
May 22, 2017: AAPS PharmSciTech
Ming-Wei Chen, Dmitry Ovchinnikov, Sorin Lazar, Michele Pizzochero, Michael Brian Whitwick, Alessandro Surrente, Michal Baranowski, Oriol Lopez Sanchez, Philippe Gillet, Paulina Plochocka, Oleg V Yazyev, Andras Kis
Transition metal dichalcogenides (TMDCs), together with other two-dimensional (2D) materials have attracted great interest due to the unique optical and electrical properties of atomically thin layers. In order to fulfill their potential, developing large-area growth and understanding the properties of TMDCs have become crucial. Here, we used molecular beam epitaxy (MBE) to grow atomically thin MoSe2 on GaAs(111)B. No intermediate compounds were detected at the interface of as-grown films. Careful optimization of the growth temperature can result in the growth of highly aligned films with only two possible crystalline orientations due to broken inversion symmetry...
May 22, 2017: ACS Nano
F Bianchini, H Fjellvåg, P Vajeeston
Sodium orthosilicates Na2MSiO4 (M = Mn, Fe, Co and Ni) have attracted much attention due to the possibility of exchanging two electrons per formula unit. They are also found to exhibit great structural stability due to a diamond-like arrangement of tetrahedral groups. In this work, we have systematically studied the possible polymorphism of these compounds by means of density functional theory, optimising the structure of a number of systems with different group symmetries. The ground state is found to be Pc-symmetric for all the considered M = Mn, Fe, Co, Ni, and several similar structures exhibiting different symmetries coexist within a 0...
May 22, 2017: Physical Chemistry Chemical Physics: PCCP
Kannan Badri Narayanan, Sung Soo Han
Viral nanotechnology is revolutionizing the biomimetic and bioinspired synthesis of novel nanomaterials. Bottom-up nanofabrication by self-assembly of individual molecular components of elongated viral nanoparticles (VNPs) and virus-like particles (VLPs) has resulted in the production of superior materials and structures in the nano(bio)technological fields. Viral capsids are attractive materials, because of their symmetry, monodispersity, and polyvalency. Helical VNPs/VLPs are unique prefabricated nanoscaffolds with large surface area to volume ratios and high aspect ratios, and enable the construction of exquisite supramolecular nanostructures...
May 19, 2017: Bioinspiration & Biomimetics
Rina Kumari, Mohd Imran Khan, Sourav Bhowmick, Kislay K Sinha, Neeladri Das, Prolay Das
DNA derived well-controlled arrangement of porphyrins has emerged as promising hybrid nanostructures. Exceptional biocompatibility and DNA-directed surface addressability coupled with rich symmetry features of the porphyrin have made these hybrid nanostructures attractive candidates for potential biomedical and biotechnological applications. However, the noteworthy photophysical properties of porphyrin and related molecules when present in DNA based nanostructures are yet to be explored fully and should be a matter of intense research that may unearth a plethora of interesting applications of these nanostructures...
May 11, 2017: Journal of Photochemistry and Photobiology. B, Biology
Xiaoliang Ma, Mingbo Pu, Xiong Li, Yinghui Guo, Ping Gao, Xiangang Luo
Chiral metamaterials represent a special type of artificial structures that cannot be superposed to their mirror images. Due to the lack of mirror symmetry, cross-coupling between electric and magnetic fields exist in chiral mediums and present unique electromagnetic characters of circular dichroism and optical activity, which provide a new opportunity to tune polarization and realize negative refractive index. Chiral metamaterials have attracted great attentions in recent years and have given rise to a series of applications in polarization manipulation, imaging, chemical and biological detection, and nonlinear optics...
May 17, 2017: Nanomaterials
K Sathiyadevi, S Karthiga, V K Chandrasekar, D V Senthilkumar, M Lakshmanan
Spontaneous symmetry breaking is an important phenomenon observed in various fields including physics and biology. In this connection, we here show that the trade-off between attractive and repulsive couplings can induce spontaneous symmetry breaking in a homogeneous system of coupled oscillators. With a simple model of a system of two coupled Stuart-Landau oscillators, we demonstrate how the tendency of attractive coupling in inducing in-phase synchronized (IPS) oscillations and the tendency of repulsive coupling in inducing out-of-phase synchronized oscillations compete with each other and give rise to symmetry breaking oscillatory states and interesting multistabilities...
April 2017: Physical Review. E
Chang-Yu Hou, Denise E Freed, Pabitra N Sen
We study the low-frequency polarization response of a surface-charged oblate spheroidal particle immersed in an electrolyte solution. Because the charged spheroid attracts counterions which form the electric double layer around the particle, using usual boundary conditions at the interface between the particle and electrolyte can be quite complicated and challenging. Hence, we generalize Fixman's boundary conditions, originally derived for spherical particles, to the case of the charged oblate spheroid. Given two different counterion distributions in the thin electric double-layer limit, we obtain analytic expressions for the polarization coefficients to the first nontrivial order in frequency...
April 2017: Physical Review. E
Guy Bunin
Ecological communities in heterogeneous environments assemble through the combined effect of species interaction and migration. Understanding the effect of these processes on the community properties is central to ecology. Here we study these processes for a single community subject to migration from a pool of species, with population dynamics described by the generalized Lotka-Volterra equations. We derive exact results for the phase diagram describing the dynamical behaviors, and for the diversity and species abundance distributions...
April 2017: Physical Review. E
Bolin Liao, Huan Zhao, Ebrahim Najafi, Xiaodong Yan, He Tian, Jesse Tice, Austin J Minnich, Han Wang, Ahmed H Zewail
As an emerging single elemental layered material with a low symmetry in-plane crystal lattice, black phosphorus (BP) has attracted significant research interest owing to its unique electronic and optoelectronic properties, including its widely tunable bandgap, polarization-dependent photoresponse and highly anisotropic in-plane charge transport. Despite extensive study of the steady-state charge transport in BP, there has not been direct characterization and visualization of the hot carriers dynamics in BP immediately after photoexcitation, which is crucial to understanding the performance of BP-based optoelectronic devices...
May 17, 2017: Nano Letters
G Q Wang, X H Gong, Y J Chen, J H Huang, Y F Lin, Z D Luo, Y D Huang
Two novel red phosphors KBaEu(XO4)3 (X = Mo, W) have been synthesized by high-temperature solid-state reactions and the crystal structures were determined for the first time. Single-crystal X-ray diffraction data reveal that their space groups are C2/c. The crystalline structure is constituted of K/BaO8 distorted square antiprisms and distorted EuO8 polyhedra which form chains lying along the c-axis and two kinds of distorted XO4 tetrahedra. This high disorder of K/Ba which might lower the crystal field symmetry around Eu(3+) results in the high purity of red emission around 615 nm originating from (5)D0 → (7)F2 transition under near-ultraviolet (NUV) excitation...
May 11, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Piotr Golec, Kamila Żelechowska, Joanna Karczewska-Golec, Jakub Karczewski, Adam Lesniewski, Marcin Łoś, Grzegorz Wegrzyn, Andrzej M Klonkowski
The use of phage display to identify peptides with an ability to bind Eu2O3 is demonstrated in this report. This is the first report of modified phages specifically binding a lanthanide. The peptides exposed on virions revealed very strong binding to Eu2O3 nanoparticles and the ability to catalyze Eu2O3 nanoparticles' formation from Eu(OH)3 and Eu(NO3)3 solutions. The luminescence emission spectrum of Eu3+ ions indicated that these ions existed mostly in sites deviated from the inversion symmetry in crystalline Eu2O3 aggregates and gelatinous Eu(OH)3 precipitate...
May 8, 2017: Bioconjugate Chemistry
Zhendong Li, Garnet Kin-Lic Chan
We present a new wave function ansatz that combines the strengths of spin projection with the language of matrix product states (MPS) and matrix product operators (MPO) as used in the density matrix renormalization group (DMRG). Specifically, spin-projected matrix product states (SP-MPS) are constructed as [Formula: see text], where [Formula: see text] is the spin projector for total spin S and |ΨMPS((N,M))⟩ is an MPS wave function with a given particle number N and spin projection M. This new ansatz possesses several attractive features: (1) It provides a much simpler route to achieve spin adaptation (i...
May 16, 2017: Journal of Chemical Theory and Computation
Diego Guedes-Sobrinho, Anderson S Chaves, Maurício J Piotrowski, Juarez L F Da Silva
Although several studies have been reported for Pt55 and Au55 nanoclusters, our atomistic understanding of the interplay between the adsorbate-surface interactions and the mechanisms that lead to the formation of the distorted reduced core (DRC) structures, instead of the icosahedron (ICO) structure in gas phase, is still far from satisfactory. Here, we report a density functional theory (DFT) investigation of the role of the adsorption effects of PH3 (one lone pair of electrons) and SH2 (two lone pairs) on the relative stability of the Pt55 and Au55 nanoclusters...
April 28, 2017: Journal of Chemical Physics
Juyeong Kim, Xiaohui Song, Fei Ji, Binbin Luo, Nicole F Ice, Qipeng Liu, Qiao Zhang, Qian Chen
The shape anisotropy of nanoparticle building blocks is of critical importance in determining their packing symmetry and assembly directionality. While there has been extensive research on the effect of their overall geometric shapes, the importance of nanometer morphology details is not well-recognized or understood. Here we draw on shape-anisotropic gold triangular nanoprism building blocks synthesized based on a method we recently developed; besides the "large-scale" triangular prism shape (79.8 nm in side length and 22...
May 1, 2017: Nano Letters
Felix Tabbert, Christian Schelte, Mustapha Tlidi, Svetlana V Gurevich
We report on the dynamics of localized structures in an inhomogeneous Swift-Hohenberg model describing pattern formation in the transverse plane of an optical cavity. This real order parameter equation is valid close to the second-order critical point associated with bistability. The optical cavity is illuminated by an inhomogeneous spatial Gaussian pumping beam and subjected to time-delayed feedback. The Gaussian injection beam breaks the translational symmetry of the system by exerting an attracting force on the localized structure...
March 2017: Physical Review. E
Ke Lan, Zhichao Li, Xufei Xie, Yao-Hua Chen, Chunyang Zheng, Chuanlei Zhai, Liang Hao, Dong Yang, Wen Yi Huo, Guoli Ren, Xiaoshi Peng, Tao Xu, Yulong Li, Sanwei Li, Zhiwen Yang, Liang Guo, Lifei Hou, Yonggang Liu, Huiyue Wei, Xiangming Liu, Weiyi Cha, Xiaohua Jiang, Yu Mei, Yukun Li, Keli Deng, Zheng Yuan, Xiayu Zhan, Haijun Zhang, Baibin Jiang, Wei Zhang, Xuewei Deng, Jie Liu, Kai Du, Yongkun Ding, Xiaofeng Wei, Wanguo Zheng, Xiaodong Chen, E M Campbell, Xian-Tu He
Octahedral spherical hohlraums with a single laser ring at an injection angle of 55^{∘} are attractive concepts for laser indirect drive due to the potential for achieving the x-ray drive symmetry required for high convergence implosions. Laser-plasma instabilities, however, are a concern given the long laser propagation path in such hohlraums. Significant stimulated Raman scattering has been observed in cylindrical hohlraums with similar laser propagation paths during the ignition campaign on the National Ignition Facility (NIF)...
March 2017: Physical Review. E
Thomas Gibaud, C Nadir Kaplan, Prerna Sharma, Mark J Zakhary, Andrew Ward, Rudolf Oldenbourg, Robert B Meyer, Randall D Kamien, Thomas R Powers, Zvonimir Dogic
In the presence of a nonadsorbing polymer, monodisperse rod-like particles assemble into colloidal membranes, which are one-rod-length-thick liquid-like monolayers of aligned rods. Unlike 3D edgeless bilayer vesicles, colloidal monolayer membranes form open structures with an exposed edge, thus presenting an opportunity to study elasticity of fluid sheets. Membranes assembled from single-component chiral rods form flat disks with uniform edge twist. In comparison, membranes composed of a mixture of rods with opposite chiralities can have the edge twist of either handedness...
April 25, 2017: Proceedings of the National Academy of Sciences of the United States of America
Katherine S H Beckham, Luciano Ciccarelli, Catalin M Bunduc, Haydyn D T Mertens, Roy Ummels, Wolfgang Lugmayr, Julia Mayr, Mandy Rettel, Mikhail M Savitski, Dmitri I Svergun, Wilbert Bitter, Matthias Wilmanns, Thomas C Marlovits, Annabel H A Parret, Edith N G Houben
Mycobacteria are characterized by their impermeable outer membrane, which is rich in mycolic acids(1). To transport substrates across this complex cell envelope, mycobacteria rely on type VII (also known as ESX) secretion systems(2). In Mycobacterium tuberculosis, these ESX systems are essential for growth and full virulence and therefore represent an attractive target for anti-tuberculosis drugs(3). However, the molecular details underlying type VII secretion are largely unknown, due to a lack of structural information...
April 10, 2017: Nature Microbiology
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