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The effect of spatially modulated interaction on quantum phase transition in one-dimensional interacting spinless fermion system is theoretically investigated by exact diagonalization and density matrix renormalization group method. Our calculations show that the periodically modulated interaction can drive the spinless fermion system into topological charge density wave state. The topological state is encoded by quasiparticle end states and the fractional quantized e /2 end charges, and characterized by Berry phase and Chern number. The quasiparticle energy spectra as a function of modulated interaction period appears a stunning fractal-like structure. For the quasi-periodic case, the topological phase transition can also occur. In a word, the spatially modulated interaction can be a new elegant avenue towards realizing to interacting topological phases.

The effect of oxygen precipitates and induced dislocations on oxidation-induced stacking faults (OSFs) in nitrogen-doped Czochralski (NCZ) silicon has been investigated. Both CZ and NCZ wafers were annealed at 800 °C and 1000 °C for 225 h with or without a post-treatment at 1200 °C for 8 h, and then were totally oxidized at 1150 °C. It was found that after oxidization, few OSFs generated in the NCZ silicon subjected to the annealing at 800 and 1000 °C, while larger numbers of OSFs in the CZ silicon. However, if the post-treatment at 1200 °C was employed prior to oxidization, OSFs density in the NCZ silicon was almost similar to that in the CZ silicon. It is considered that the high density of oxygen precipitates and induced dislocations formed in NCZ silicon can absorb the self-interstitial silicon atoms so that the generation of OSFs is inhibited. After the postannealing, most dislocations shrank and dissolved with the dissolution of oxygen precipitates in the NCZ silicon so as to induce the same amount of OSFs as that in the CZ silicon. [ABSTRACT FROM AUTHOR]

The mechanical strength in germanium-doped Czochralski silicon (GCz-Si) wafers is examined by using the on-line warpage statistics analysis, indentation tests and fracture structure measurements. The generation and mobilization of the dislocations induced by indentation in Cz-Si wafers are suppressed by the germanium doping.

Resistive switching behaviors of SnO2 films are largely improved by Cu acceptor doping. At a suitable Cu2+ concentration, a high ON/OFF resistance ratio (104), good endurance (104) and long retention (104 s) are achieved in the Cu/SnO2:Cu/Pt sandwich structure with the modulation of carriers and oxygen vacancies. As a memristor, the resistive switching can be triggered by one pulse or a train of pulses, and the latter mode could simulate the long-term potentiation of biological synapses. Moreover, the multi-resistance states during the reset process demonstrate a combination of abrupt and incremental resistive switching. The peculiar conductive behavior of the devices is considered to result from the cooperation of conductive filaments and Schottky barrier, with the oxygen vacancies serving as the bridge. These studies are significant for higher density storage and cognitive computing in future. [ABSTRACT FROM AUTHOR]

A study was conducted to investigate the grown-in defects in oxygen precipitates and voids in nitrogen-doped Czochralski (NCZ) silicon. The result reveals that the formation of grown-in oxygen precipitates in NCZ silicon can be divided into two stages.

Maxwell—Wagner (M-W) theory was used to explain the dielectric relaxor behavior of BiFeO3(BFO)/Bi3.25La0.75Ti3O12(BLT) film grown on Pt/Ti/SiO2/Si substrate. The BFO film was considered to be ferroelectric film, and its temperature dependence of dielectric constant was calculated by Landau theory. BLT film was of dielectric-relaxor behavior and its temperature dependence of dielectric constant was given by Smolenski theory. The leakage currents for the BFO and BLT films were assumed to obey Poole-Frenkel emission and Schottky emission, respectively. The temperature dependent dielectric constant and loss of the BFO/BLT film were characterized, which agrees with the experiment. The enhancement of the polarization in BFO/BLT film may induced by the current leakage restraining in BFO film. [ABSTRACT FROM AUTHOR]

In the application of a set of position-thickness-dependent stress to modified Landau-Devonshire theory, the distribution of dielectric constant and the dependence of effective dielectric constant on the film thickness and the temperature have been studied in BaTiO 3 films with fine grains. The results show that both the transition temperature and dielectric constant are dependent with positions. When T T > T c , a layer with giant dielectric constant appears in the film. And when T > T cfmax , the dielectric constant near the interface is higher than that near the center. The “series capacitor model” is invalid at high temperature for c-phase. The theoretical results agree with the experiment. [ABSTRACT FROM AUTHOR]

Ca2CuO3ceramics were synthesized by the traditional solid-state sintering method. Its dielectric properties were studied in the frequency range from 102Hz to 106Hz and in the temperature range from 100 K to room temperature. The activation energy was calculated by the Arrhenius Equation. The analysis for XPS spectrum and the fitting value of the activation energy (Q= 0.17 eV) indicated that the dielectric response in Ca2CuO3might be governed by the electron hopping between the Cu ions. The experimental result revealed a relaxation process for the polarization mechanism. Given the relationship between relaxation time and temperature, the dielectric properties of Ca2CuO3can be perfectly described by the Cole-Cole model. [ABSTRACT FROM AUTHOR]

The process of the thermal denaturation of albumin was studied using dynamic speckle methods, which included the time history of speckle patterns (THSP), the THSP based on wavelet entropy (WE), speckle size measurement and the speckle pattern mean contrast techniques. In experiments, the dynamic speckle pattern sequences produced from the albumin colloid during heat denaturation were obtained using CCD camera. And then, using these dynamic speckle methods, the change of the movement properties of protein particles was analyzed during the heating process. All results show that the protein particles become bigger, their mean free path becomes shorter and the velocity of the Brownian movement becomes slower during the heating process. The experiments prove that dynamic speckle methods are useful tools to investigate the particles motion in solution. [ABSTRACT FROM AUTHOR]

Examines the growth of nitrogen-doped crystals in a nitrogen atmosphere under reduced pressure. Resistivity of n-type nitrogen-doped silicon; Formation of thermal acceptors in N-doped silicon; Concentration of thermal acceptor.

Due to many remarkable physical and chemical properties, two-dimensional (2D) nanomaterials have become a hot spot in the field of condensed matter physics. In this paper, we have studied the structural, mechanical, and electronic properties of the 2D GaInO3 system by first-principles method. We find that 2D GaInO3 can exist stably at ambient condition. Molecular dynamic simulations show that GaInO3-sheet has excellent thermal stability and is stable up to 1100 K. Electronic structural calculations show that GaInO3-sheet has a band gap of 1.56 eV, which is close to the ideal band gap of solar cell materials, demonstrating great potential in future photovoltaic application. In addition, strain effect studies show that the GaInO3-sheet structure always exhibits a direct band gap under biaxial compressive strain, and as the biaxial compressive strain increases, the band gap gradually decreases until it is converted into metal. While biaxial tensile strain can cause the 2D material to transform from a direct band gap semiconductor into an indirect band gap semiconductor, and even to metal. Our research expands the application of the GaInO3 system, which may have potential application value in electronic devices and solar energy. [ABSTRACT FROM AUTHOR]

Chinese medical Q&A is easily affected by the noise of medical-specific terminology, making it more challenging than open-domain Q&A. Previous studies on Chinese medical Q&A mainly relied on character-level fine-grained information, neglecting word-level coarse-grained information that carries more semantic information. In addition, introducing external medical knowledge graph can further enrich the fine-grained information in Q&A sentences, but most existing studies usually adopt a simple way of joint representation of sentences and external knowledge. Therefore, this paper proposes a Chinese medical Q&A matching model based on multi-granularity semantic information and knowledge graph (CMQA-MGSI). The model employs a Lattice network to select the most relevant character-level and word-level sequences from the Q&A sentences, and leverages Word2Vec and BERT to enhance the semantic information; to better exploit the external domain knowledge, a dual-channel attention mechanism is devised to capture the multi-angle knowledge representations between the Q&A sentences and the entity embeddings and relation embeddings in the knowledge graph. Experiments on the cMedQA1.0 and cMedQA2.0 datasets demonstrate that the proposed model outperforms existing Chinese medical Q&A matching models. [ABSTRACT FROM AUTHOR]

Pb(Zr,Ti)O3 films of various grain size were prepared by the sol–gel technique. X-ray diffraction results show that these films are of single tetragonal phase with no evidence of preferential orientation. Anomalous polarization switching (APS) was induced in the films with average grain size ~150 nm by using the tip of a scanning force microscope. After scanning an area by the tip with constant poling parameter, the polarization of some grains orient opposite to the applied electric field irrespective of applied field polarity, exhibiting APS; while the rest switch in a normal way. The ratio of the APS grains to the total number decreases with the decrease of average grain size. Pulse poling experiments reveal that APS is likely to be related to the intrinsic characteristic of grains. Control experiments of poling (during and after) exclude backswitching after the removal of the external field due to the charge injection effect or the built-in field; both of which are possible reasons for APS. It is suggested that coupling between the temporary stress created in grains during field-induced normal switching and the applied field probably plays a key role in APS. [ABSTRACT FROM AUTHOR]

The point contact tunnel junctions between a one-dimensional topological superconductor and single-channel quantum Hall (QH) liquids are investigated theoretically with bosonization technology and renormalization group methods. For the integer QH liquid, the universal low-energy tunneling transport is governed by the perfect Andreev reflection fixed point with quantized zero-bias conductance , which can serve as a definitive fingerprint of the existence of a Majorana fermion. For the Laughlin fractional QH liquids, its transport is governed by the perfect normal reflection fixed point with vanishing zero-bias conductance and bias-dependent conductance . Our setup is within reach of the present experimental techniques. [ABSTRACT FROM AUTHOR]

SnO2:Cu memristor devices were fabricated to investigate the influence of Frenkel defects on endurance behavior. We controlled the oxygen pressure during pulsed laser deposition to obtain different Frenkel defect conditions. For SnO2:Cu devices with homogeneous Frenkel defects, high-resistance state (HRS) fatigue was observed with increasing switching cycles due to the reduction of interfacial barriers caused by unrecoverable fragments of conductive filaments. In bilayer SnO2:Cu devices with Frenkel defect concentration gradients, the vertical Fick force resulting from the concentration gradient can drive mobile oxygen ions to restrain the formation of unrecoverable fragments. Thus, HRS fatigue was improved by restraining the reduction of interfacial barriers. When the gradient becomes large, the bilayer devices demonstrate HRS rise and stuck switching in several switching cycles. In this case, the Fick force may dominate the diffusion of mobile oxygen ions, leading to the overfilling of oxygen vacancies at the interface and an increase in interfacial barriers. [ABSTRACT FROM AUTHOR]

ST-xZS ceramics were prepared by solid-state sintering and have high temperature dielectric relaxation behavior at the temperature ranges of 300 °C–500 °C. We explore the origin of high temperature dielectric relaxation behavior of samples by activation energy calculation, XPS energy spectrum analysis and oxygen treatment experiment. We get a conclusion that the dielectric relaxation of pure ST ceramics comes from the migration of Vo. However, with the increase of ZS content, the dielectric relaxation related to Vo migration is gradually transformed into the influence of Ti4+ ion polarization, and the possible causes of relaxation behavior dependence are analyzed in detail. [ABSTRACT FROM AUTHOR]

In this work, we studied the evolution of vacancy-like defects and the formation of brittle precipitates in a reduced-activation V−Cr−Mn medium-entropy alloy. The evolution of local electronic circumstances around Cr and Mn enrichments, the vacancy defects, and the CrMn3 precipitates were characterized by using scanning electron microscopy with energy-dispersive spectroscopy, X-ray diffraction, and positron annihilation spectroscopy. The microstructure measurements showed that the Mn and Cr enrichments in the as-cast sample significantly evolved with temperature, i.e., from 400 °C, the Cr/Mn-segregated regions gradually dissolved into the matrix and then disappeared, and from 900 °C to 1000 °C, they existed as CrMn3 precipitates. The crystallite size of the phase corresponding to CrMn3 precipitates was about 29.4 nm at 900 °C and 43.7 nm at 1000 °C. The positron annihilation lifetime results demonstrated that the vacancies mediated the migration of Cr and Mn, and Cr and Mn segregation finally led to the formation of CrMn3 precipitates. The coincidence Doppler broadening results showed that the characteristic peak moved to the low-momentum direction, due to an increase in the size of the vacancy defects at the interface and the formation of CrMn3 precipitates. [ABSTRACT FROM AUTHOR]

The influence of stress on the spontaneous polarization in two-dimensional Bi4Ti3O12 (BiT) films is investigated by modified Landau—Devonshire thermodynamic theory. Three orientation cases of BiT unit, nine ferroelectric phases are discussed under the mechanism of strain-polarization coupling. Results show that the effect of stress on out-of-plane spontaneous polarization for all cases is small and can not clarify the origin of the effect of external stress on the net-switched charge in Nd- and La-doped Bi4Ti3O12 films. So there is a need to consider stress-induced reorientation of domains. [ABSTRACT FROM AUTHOR]

With the continuous development of nanomaterials technology, the research on electromagnetic absorption of nanomaterials dispersed in large-scale sea has important application value. Therefore, the wave absorption mechanism of nano-silica-coated ferroferric oxide (Fe3O4@SiO2) powder in large scale space is studied. By calculating the area of absorption cross-section and scattering cross-section of a single core-shell Fe3O4@SiO2 composite particle with seawater as the background medium, and the wave absorption property of core-shell Fe3O4@SiO2composite particles is analyzed from the microscopic aspect. Then, the wave-absorbing properties of core-shell Fe3O4@SiO2 composite particles dispersed in the large-scale sea with the size of 3 m are studied, and the absorbing loss is calculated, and the absorbing mechanism is further analyzed. [ABSTRACT FROM AUTHOR]

Sr 1 − 3 x / 2 La x TiO 3 (SLTO) ceramics (x = 0.05, 0.10, 0.15) were prepared with giant dielectric constant by the traditional solid-state method at 1350 ∘ C. The temperature dependence of the dielectric constant was obtained at the temperature ranging from 29 ∘ C to 500 ∘ C and the frequency ranging from 2 kHz to 2 MHz. Two sets of relaxation peaks appear in the low temperature (region I) and the high temperature (region II), respectively. For region I, we conclude that the relaxation behavior is related to the oxygen vacancy migration. For region II, the two relaxation processes are caused by grain boundary for high frequency and Sr or Ti defects at grain interior for low frequency. With the doping amount reaching 0.15, the relaxation peaks disappear and become a common phase transition because of the aggravation of lattice distortion. These possible physical mechanisms of two sets of relaxation peaks are briefly discussed. [ABSTRACT FROM AUTHOR]

Grown-in defects including oxygen precipitates and voids in nitrogen-doped Czochralski (NCZ) silicon have been investigated. It was found that the formation of grown-in oxygen precipitates in NCZ silicon can be divided into two stages. The large precipitates supposed to be enhanced by N[sub 2]-V[sub 2]-O[sub χ] complexes are generated around 1150 °C, while the small precipitates supposed to be enhanced by N[sub m]O[sub n] complexes are formed at 750 °C and below. Moreover, it was revealed that the oxygen precipitation behavior in the mixed-type NCZ silicon, which contains vacancy-type and interstitial-type defects distinguished by an OSF-ring in the oxidized wafer, is in sharp contrast to that in the mixed-type Czochralski (CZ) silicon, when subjected to one-step high temperature annealing (1050 °C/32 h) and two-step annealing (800 °C/4 h+ 1050 °C/16 h). On the other hand, it was found that, compared with CZ silicon, NCZ silicon has much denser crystal originated particles in smaller sizes, which were verified to have been annihilated at relatively lower temperatures. Based on the experimentally found phenomena, a tentative model that takes into account the formation of nitrogen-related complexes involving oxygen atoms and vacancies, void formation, and oxygen precipitation is presented. [ABSTRACT FROM AUTHOR]

Deals with a study which reported experimental evidence for the effect of carbon on oxygen precipitation in a high carbon content Czochralski silicon crystal. Experimental details; Results and discussion; Conclusion.

Investigates the formation behavior of donors associated with oxygen in nitrogen-doped and undoped Czochralski (CZ) silicon by means of electrical and infrared measurements at low temperatures. Use of CZ single crystal silicon in the microelectronic industry; Experimental details; Findings of the study.

Carbon dioxide (CO2) normally exists in a gaseous molecular state under ambient conditions, while two-dimensional (2D) crystals of CO2 have not been reported yet. In this work, based on density functional theory and the particle swarm optimization method, we unveil two CO2 2D crystals with space groups of P4̅M2 and Amm2. Our results show that these structures have excellent thermal, dynamic, and mechanical stability. The new structures are insulators with an indirect or direct band gap, while the indirect band gap can be tuned to be direct with small uniaxial strains. More importantly, the P4̅M2 structure has an in-plane negative Poisson's ratio, which is due to the interaction of the lattice symmetry and the local CO4 tetrahedron symmetry. In addition, the Amm2 sheet has a very large electronic band gap (＞9 eV), which is the largest in all known 2D materials. Enthalpy curves indicate that these 2D structures may be obtained from the ambient phase of CO2 under high pressure. This work presents new structures of CO2, and because of their excellent performance in terms of stability, mechanical and electronic properties, they potentially have broad applications. [ABSTRACT FROM AUTHOR]

Density functional theory calculations were carried out to investigate the Diels-Alder cycloaddition between cyclopentadiene and C60 after the encapsulation of Li+ ion with transition states identified and confirmed by intrinsic reaction coordinate calculations. Our results showed that the Li+-encapsulation results in a lower energy barrier and the presence of counter anion [ABSTRACT FROM AUTHOR]

Effects of protein polari sation on docking accuracy were investigated using molecular docking programme AutoDock 4 in which topology-specific empirical Gasteiger charges were replaced with Polarised protein-specific charges (PPC) to represent quantum mechanics- polarised protein. Docking was successfully conducted for 50 diverse protein–ligand complexes. The docking with PPC charges shows a decrease in the root-mean-square deviation (RMSD) values of ligands compared to those from the docking with Gasteiger charges. Ligand binding orientations and their key interactions such as hydrogen bonding interactions in X-ray structures were substantially reproduced in complexes docked using PPC scheme with 98% of the RMSDs of the best docking poses less than 2 Å compared to 74% in the docking with Gasteiger charges. Considerable improvements in docking accuracy were observed by simply altering the atomic partial charges in the scoring function, which reflects the importance of protein polarisation in molecular docking. Further research can be carried out to (1) include polarisation of both ligands and proteins to account for polarisation effects within protein and between protein and ligand, and (2) develop a PPC-based scoring function to increase the docking accuracies for protein–ligand complexes from a larger variety of protein families. [ABSTRACT FROM AUTHOR]

Van der Waals (vdW) interactions play an important role on semiconductors in nanoscale. Here, we utilized first-principles calculations based on density functional theory to demonstrate the growth mode transition from prolate to multiunit configurations for Ge n ( n = 10-50) clusters. In agreement with the injected ion drift tube techniques that 'clusters with n < 70 can be thought of as loosely bound assemblies of small strongly bound fragments (such as Ge7 and Ge10),' we found these stable fragments are connected by Ge6, Ge9, or Ge10 unit (from bulk diamond), via strong covalent bonds. Our calculated cations usually fragment to Ge7 and Ge10 clusters, in accordance with the experiment results that the spectra Ge7 and Ge10 correspond to the mass abundance spectra. By controlling a germanium cluster with vdW interactions parameters in the program or not, we found that the vdW effects strengthen the covalent bond from different units more strikingly than that in a single unit. With more bonds between units than the threadlike structures, the multiunit structures have larger vdW energies, explaining why the isolated nanowires are harder to produce. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

We propose an innovative approach based on optical vortex metrology (OVM) to characterize a dynamic random process. The dynamic process under consideration involves scatterers within a sample moving stochastically with time evolution. Specifically, the dynamic random process such as white paint drying has been investigated experimentally. In simulations, two unique descriptors, namely the successive survival rate of optical vortices and the average velocity of survival vortices, are introduced to determine the dynamic process based on the uniqueness of the optical vortex. Numerical simulation and experimental results show that these unique descriptors can be used to quantitatively analyze the dynamic process. Furthermore, we have found that further information on the dynamic process can be obtained by the proposed method, thereby facilitating innovative applications using OVM. [ABSTRACT FROM AUTHOR]

The magnetic and dielectric properties of a YMnCoO ceramic have been investigated. The x-ray diffraction pattern shows that the sample has the monoclinic structure (space group P2/ n). Magnetic measurements show that YMnCoO becomes ferromagnetic (FM) below T ~75 K. More importantly, the temperature dependence of magnetization (zero field cooled and field cooled behavior) and the M(H) behavior are indicative of spin-glass-like behavior of YMnCoO, which may be caused by competition between the FM and antiferromagnetic interaction. Dielectric relaxor behavior at low temperature is also observed; this arises from dipolar effects associated with the charge ordering of Co and Mn. [ABSTRACT FROM AUTHOR]

Within the framework of Pertsev's thermodynamic theory, the equilibrium polarization states and the physical properties of single-domain Pb(Zr0.35Ti0.65)O3 (PZT) thin films epitaxially grown on dissimilar cubic substrates are investigated. The "misfit strain-temperature" phase diagrams are obtained for the films. The presence of stability range of the rhombohedral phase is the characteristic feature of these phase diagrams, which separates the stability ranges of the tetragonal phase and the orthorhombic phase. The coexistence of the rhombohedral phase and the tetragonal phase in PZT film can be explained by Pertsev's theory with the gradient strain case with a suitable stress form. [ABSTRACT FROM AUTHOR]

The field-dependent ferroelectric properties of Bi3.25La0.75Ti3O12 thin films under different stress were studied. It was found that, when the voltage increased from 3 V to 16 V, the remnant polarization and the coercive field increased for the films either under stress or not. Under both compressive and tensile stress, the above tendency of the remnant polarization and the coercive field got enhanced. It was also found that, the fatigue properties of films deteriorated with the measured voltage decreasing. The pinning of the domain walls and the coarsening of the domains induced by stress were used to discuss the above results. [ABSTRACT FROM AUTHOR]

The effect of uniaxial stress on Bi 3.25 La 0.75 Ti 3 O 12 (BLT) thin films annealed at two different temperatures of 700°C and 800°C were studied. It was observed that the films annealed at 800°C had lager remnant polarization ( P r ) compared with that annealed at 700°C under either applied stress or not. However, the tendency of change about the remnant polarization and the coercive field with stress in both films was very similar. That is to say, the remnant polarization increased with tensile stress, but decreased with compressive stress; On the contrary, the coercive field decreased with the stress changing from maximum compression to maximum tension in films. The above results are thought to originate from the grain integrity and the reorientation of domains in films under stress. [ABSTRACT FROM AUTHOR]

ABSTRACT. A sample of 486 children in Beijing, China, were tested on the water-level task (WLT; J. Piaget & B. Inhelder, 1948/1956). The participants were 256 boys and 230 girls from 4th, 5th, 6th, 8th, and 11th grades. Three levels of mastery of the WLT were found. Level 1 consisted of 4th and 5th graders, who averaged about 71% correct. Level 2 consisted of 6th and 8th graders, who averaged about 83% correct. Level 3 consisted of 11th graders, who averaged 97% correct. The results provide partial support for the Piagetian theory of age-related developmental differences in performance on the WLT. The findings depict an interactive relationship of maturation with culture and education in the development of the ability to solve the WLT. [ABSTRACT FROM AUTHOR]

We present here the structural and dielectric properties of Tb0.5Y0.5MnO3 ceramics synthesized by solid state reaction. The X-ray diffraction pattern shows that the sample has an orthorhombic structure with space group Pbnm. Dielectric characteristics of Tb0.5Y0.5MnO3 ceramics are investigated over a broad temperature and a frequency range. Two dielectric relaxations are observed at 40-90 and 100-220 K. The results indicate that the low temperature dielectric relaxation (LTDR) may be exhibited variable ranger hopping behavior due to the oxygen vacancies (=start_CONVERSION_=VO+=start_CONVERSION_=), while the high temperature dielectric relaxation (HTDR) may come from the dipolar effects associated with the charge carrier hopping between Mn2+ and Mn3+. [ABSTRACT FROM AUTHOR]

Investigates the effect of nitrogen-oxygen complex on electrical properties of Czochralski silicon. Results of Fourier transmission infrared spectrometer measurements; Role of the complex as shallow thermal donors; Stabilization of the carrier concentration of the nitrogen-rich silicon.