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Condense matter

Su-Yang Xu, Nasser Alidoust, Guoqing Chang, Hong Lu, Bahadur Singh, Ilya Belopolski, Daniel S Sanchez, Xiao Zhang, Guang Bian, Hao Zheng, Marious-Adrian Husanu, Yi Bian, Shin-Ming Huang, Chuang-Han Hsu, Tay-Rong Chang, Horng-Tay Jeng, Arun Bansil, Titus Neupert, Vladimir N Strocov, Hsin Lin, Shuang Jia, M Zahid Hasan
In quantum field theory, Weyl fermions are relativistic particles that travel at the speed of light and strictly obey the celebrated Lorentz symmetry. Their low-energy condensed matter analogs are Weyl semimetals, which are conductors whose electronic excitations mimic the Weyl fermion equation of motion. Although the traditional (type I) emergent Weyl fermions observed in TaAs still approximately respect Lorentz symmetry, recently, the so-called type II Weyl semimetal has been proposed, where the emergent Weyl quasiparticles break the Lorentz symmetry so strongly that they cannot be smoothly connected to Lorentz symmetric Weyl particles...
June 2017: Science Advances
Elisabetta A Matsumoto, Randall D Kamien, Gareth P Alexander
Frustration is a powerful mechanism in condensed matter systems, driving both order and complexity. In smectics, the frustration between macroscopic chirality and equally spaced layers generates textures characterized by a proliferation of defects. In this article, we study several different ground states of the chiral Landau-de Gennes free energy for a smectic liquid crystal. The standard theory finds the twist grain boundary (TGB) phase to be the ground state for chiral type II smectics. However, for very highly chiral systems, the hierarchical helical nanofilament phase can form and is stable over the TGB...
August 6, 2017: Interface Focus
B Q Lv, Z-L Feng, Q-N Xu, X Gao, J-Z Ma, L-Y Kong, P Richard, Y-B Huang, V N Strocov, C Fang, H-M Weng, Y-G Shi, T Qian, H Ding
In quantum field theory, Lorentz invariance leads to three types of fermion-Dirac, Weyl and Majorana. Although the existence of Weyl and Majorana fermions as elementary particles in high-energy physics is debated, all three types of fermion have been proposed to exist as low-energy, long-wavelength quasiparticle excitations in condensed-matter systems. The existence of Dirac and Weyl fermions in condensed-matter systems has been confirmed experimentally, and that of Majorana fermions is supported by various experiments...
June 19, 2017: Nature
D Ramos, M Proença, M R Leite, A D Ferreira, I B Trevisan, G F S Brígida, G Y Tacao, E M C Ramos
INTRODUCTION: Pulmonary rehabilitation (PR) has many benefits for individuals with COPD. However, it is not clear whether PR could prevent the hazards of air pollution exposure. This study aimed to analyze the effects of biomass burning exposure on pulmonary inflammatory markers and pulmonary function in individuals with COPD, participants and non-participants of PR. METHODS: 35 subjects were divided into three groups: individuals with COPD who received PR (G1, n=15), those who did not (G2, n=10), and a control group composed of healthy individuals without COPD (CG, n=10)...
June 15, 2017: Revista Portuguesa de Pneumologia
L B Ju, C T Zhou, T W Huang, K Jiang, H Zhang, S Z Wu, B Qiao, S C Ruan
It was shown that in the interactions of ultra-intense circularly polarized laser pulse with the near-critical plasmas, the angular momentum can be transferred efficiently from the laser beam to electrons through the resonance acceleration process. The transferred angular momentum increases almost linearly with the acceleration time t_{a} when the electrons are resonantly accelerated by the laser field. In addition, it is shown analytically that the averaged angular momentum of electrons is proportional to the laser amplitude a_{L}, and the total angular momentum of the accelerated electron beam is proportional to the square of the laser amplitude a_{L}^{2} for a fixed parameter of n_{e}/n_{c}a_{L}...
May 2017: Physical Review. E
Bo Yang, Xiaoming Zhang, Mingwen Zhao
As a new type of quantum matter, Dirac node line (DNL) semimetals are currently attracting widespread interest in condensed matter physics and materials science. The DNL, featured by a closed line consisting of linear band crossings in the momentum space, was mostly predicted in three-dimensional materials. Here, we propose a tight-binding (TB) model of pz + px,y or pz + s orbitals defined on the two-dimensional (2D) Lieb lattice for the 2D version of DNL semimetals. The DNL states in these models are caused by the inversion of the bands with different symmetries and thus robust against spin-orbit interaction...
June 15, 2017: Nanoscale
Justin N Cross, Jing Su, Enrique R Batista, Samantha K Cary, William J Evans, Stosh A Kozimor, Veronika Mocko, Brian L Scott, Benjamin W Stein, Cory J Windorff, Ping Yang
Developing a better understanding of covalency (or orbital mixing) is of fundamental importance. Covalency occupies a central role in directing chemical and physical properties for almost any given compound or material. Hence, the concept of covalency has potential to generate broad and substantial scientific advances, ranging from biological applications to condensed matter physics. Given the importance of orbital mixing combined with the difficultly in measuring covalency, estimating or inferring covalency often leads to fiery debate...
June 14, 2017: Journal of the American Chemical Society
Jing Zhang, Wei Xu, Peng Sheng, Guangyao Zhao, Daoben Zhu
Organic donor-acceptor (DA) complexes have attracted wide attention in recent decades, resulting in the rapid development of organic binary system electronics. The design and synthesis of organic DA complexes with a variety of component structures have mainly focused on metallicity (or even superconductivity), emission, or ferroelectricity studies. Further efforts have been made in high-performance electronic investigations. The chemical versatility of organic semiconductors provides DA complexes with a great number of possibilities for semiconducting applications...
June 13, 2017: Accounts of Chemical Research
Yi Zhang, Eun-Ah Kim
Despite rapidly growing interest in harnessing machine learning in the study of quantum many-body systems, training neural networks to identify quantum phases is a nontrivial challenge. The key challenge is in efficiently extracting essential information from the many-body Hamiltonian or wave function and turning the information into an image that can be fed into a neural network. When targeting topological phases, this task becomes particularly challenging as topological phases are defined in terms of nonlocal properties...
May 26, 2017: Physical Review Letters
Nitin Samarth
No abstract text is available yet for this article.
June 7, 2017: Nature
Christopher Benndorf, Hellmut Eckert, Oliver Janka
Intermetallic compounds are of broad interest for solid state chemists, condensed matter physicists, and material scientists due to their intriguing crystal chemistry, their physical properties, and their potential applications, ranging from lab curiosities to everyday objects. To characterize and understand the properties of new compounds and novel materials, the availability of structural information, particularly single-crystal X-ray diffraction data, is a mandatory prerequisite. Especially when it comes to the formation of compounds with deficient or mixed site occupancies, superstructures, or representatives crystallizing in other, thus far unknown structure types, a complementary method for structural analysis is of great value...
June 7, 2017: Accounts of Chemical Research
Zhi-Gang Zheng, Rafael S Zola, Hari Krishna Bisoyi, Ling Wang, Yannian Li, Timothy J Bunning, Quan Li
Zigzag pattern formation is a common and important phenomenon in nature serving a multitude of purposes. For example, the zigzag-shaped edge of green leaves boosts the transportation and absorption of nutrients. However, the elucidation of this complicated shape formation is challenging in fluid mechanics and soft condensed matter systems. Herein, a dynamically reconfigurable zigzag pattern deformation of a soft helical superstructure is demonstrated in a photoresponsive self-organized cholesteric liquid crystal superstructure under the simultaneous influence of an applied electric field and light irradiation...
June 7, 2017: Advanced Materials
Stein Nilsen, Kirsti Malterud
OBJECTIVE: To explore general practitioners (GPs') experiences from consultations when a patient's request is denied, and outcomes of such incidents. DESIGN AND PARTICIPANTS: We conducted a qualitative study with semi-structured individual interviews with six GPs in Norway. We asked them to tell about experiences from specific encounters where they had refused a patient's request. The texts were analysed with Systematic Text Condensation, a method for thematic cross-case analysis...
June 5, 2017: Scandinavian Journal of Primary Health Care
Cheung Chan, Xiong-Jun Liu
The search for topological superconductors and non-Abelian Majorana modes ranks among the most fascinating topics in condensed matter physics. There now exist several fundamental superconducting phases which host symmetry protected or chiral Majorana modes, of which the chiral modes are protected by Chern numbers in even dimensions. Here we propose to observe novel chiral Majorana modes by realizing a Fulde-Ferrell-Larkin-Ovchinnikov state, i.e., the pair density wave (PDW) phase in a Weyl semimetal which breaks time-reversal symmetry...
May 19, 2017: Physical Review Letters
Shriram Ramanathan
No abstract text is available yet for this article.
May 31, 2017: Nature
Fei Zhang, Yuan Wu, Hongbo Lou, Zhidan Zeng, Vitali B Prakapenka, Eran Greenberg, Yang Ren, Jinyuan Yan, John S Okasinski, Xiongjun Liu, Yong Liu, Qiaoshi Zeng, Zhaoping Lu
Polymorphism, which describes the occurrence of different lattice structures in a crystalline material, is a critical phenomenon in materials science and condensed matter physics. Recently, configuration disorder was compositionally engineered into single lattices, leading to the discovery of high-entropy alloys and high-entropy oxides. For these novel entropy-stabilized forms of crystalline matter with extremely high structural stability, is polymorphism still possible? Here by employing in situ high-pressure synchrotron radiation X-ray diffraction, we reveal a polymorphic transition from face-centred-cubic (fcc) structure to hexagonal-close-packing (hcp) structure in the prototype CoCrFeMnNi high-entropy alloy...
June 1, 2017: Nature Communications
Yan Meng, Weiwei Wang, Jinsong Kang, Xinxue Wang, Liankun Sun
Diabetes mellitus is associated with cognitive dysfunction. Numerous previous studies have shown that type 1 diabetes-induced hyperglycaemia causes structural brain damage, such as a decrease in whole-brain grey matter. The impact of diabetes mellitus on the cerebral cortex is poorly understood and requires further clarification. In the present study, diabetes was induced via an intraperitoneal injection of streptozotocin (50 mg/kg). Hematoxylin and eosin (H&E) staining was performed to detect the morphological changes in the cerebral cortex, terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) staining was used to detect neuronal apoptosis and western blotting was performed to determine protein expression levels...
May 2017: Experimental and Therapeutic Medicine
M Johansen, P Lund, M R Weisbjerg
The aim of this meta-analysis was to compare feed intake, milk production, milk composition and organic matter (OM) digestibility in dairy cows fed different grass and legume species. Data from the literature was collected and different data sets were made to compare families (grasses v. legumes, Data set 1), different legume species and grass family (Data set 2), and different grass and legume species (Data set 3+4). The first three data sets included diets where single species or family were fed as the sole forage, whereas the approach in the last data set differed by taking the proportion of single species in the forage part into account allowing diets consisting of both grasses and legumes to be included...
May 31, 2017: Animal: An International Journal of Animal Bioscience
G Grellet-Tinner, S Lindsay, M B Thompson
Megapodes are galliform birds endemic to Australasia and unusual among modern birds in that they bury their eggs for incubation in diverse substrates and using various strategies. Alectura lathami and Leipoa ocellata are Australian megapodes that build and nest in mounds of soil and organic matter. Such unusual nesting behaviours have resulted in particular evolutionary adaptations of their eggs and eggshells. We used a combination of scanning electron microscopy, including electron backscatter diffraction and energy-dispersive X-ray spectroscopy, to determine the fine structure of the eggshells and micro-CT scanning to map the structure of pores...
May 30, 2017: Journal of Microscopy
E Compagno, G De Chiara, D G Angelakis, G M Palma
A toolbox for the quantum simulation of polarons in ultracold atoms is presented. Motivated by the impressive experimental advances in the area of ultracold atomic mixtures, we theoretically study the problem of ultracold atomic impurities immersed in a Bose-Einstein condensate mixture (BEC). The coupling between impurity and BEC gives rise to the formation of polarons whose mutual interaction can be effectively tuned using an external laser driving a quasi-resonant Raman transition between the BEC components...
May 24, 2017: Scientific Reports
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