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Search Results: 1 - 10 of 23439 matches for " Jianmin Yuan "
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Relaxation and screening in Auger emission: an explanation for the changes from bandlike to quasi-atomiclike CVV Auger spectra across the transition metal series
Jianmin Yuan
Physics , 2001,
Abstract: Supercell method is used to study the relaxation and screening effects during the Auger transition in metals. In order to make the interaction between the core-holes sited at different atoms negligible, the real metal is simulated by supercells repeated periodically. The electronic states concerned by the Auger transition are calculated by using FLAPW method. The occurrence of both bandlike and quasi-atomiclike Auger spectra across transition metal series is related clearly to the different responses of these metals to the existence of a core-hole depending on whether their d-bands are partially or completely filled. As examples, L_3VV and M_1VV Auger spectral profiles of Cu have been calculated in a reasonably well agreement with experiment. The hole-hole interaction is considered explicitly in the calculation to give the multi-splitting in the quasi-atomiclike Auger spectra.
Adsorption of molecular oxygen on doped graphene: atomic, electronic and magnetic properties
Jiayu Dai,Jianmin Yuan
Physics , 2010, DOI: 10.1103/PhysRevB.81.165414
Abstract: Adsorption of molecular oxygen on B-, N-, Al-, Si-, P-, Cr- and Mn-doped graphene is theoretically studied using density functional theory in order to clarify if O2 can change the possibility of using doped graphene for gas sensors, electronic and spintronic devices. O2 is physisorbed on B-, and Ndoped graphene with small adsorption energy and long distance from the graphene plane, indicating the oxidation will not happen; chemisorption is observed on Al-, Si-, P-, Cr- and Mn-doped graphene. The local curvature caused by the large bond length of X-C (X represents the dopants) relative to CC bond plays a very important role in this chemisorption. The chemisorption of O2 induces dramatic changes of electronic structures and localized spin polarization of doped graphene, and in particular, chemisorption of O2 on Cr-doped graphene is antiferromagnetic. The analysis of electronic density of states shows the contribution of the hybridization between O and dopants is mainly from the p or d orbitals. Furthermore, spin density shows that the magnetization locates mainly around the doped atoms, which may be responsible for the Kondo effect. These special properties supply a good choice to control the electronic properties and spin polarization in the field of graphene engineering.
Non-perturbative QED Model with Dressed States to Tackle HHG in Ultrashort Intense Laser Pulses
Huayu Hu,Jianmin Yuan
Physics , 2008, DOI: 10.1103/PhysRevA.78.063826
Abstract: A generalization of non-perturbative QED model for high harmonic generation is developed for the multi-mode optical field case. By introducing classical-field-dressed quantized Volkov states analytically, a formula to calculate HHG for hydrogen-like atom in ultrashort intense laser pulse is obtained, which has a simple intuitive interpretation. The dressed state QED model indicates a new perspective to understand HHG, for example, the presence of the weak even-order harmonic photons, which has been verified by both theoretical analysis and numerical computation. Long wavelength approximation and strong field approximation are involved in the development of the formalism.
Dynamical core polarization of two-active-electron systems in strong laser fields
Zengxiu Zhao,Jianmin Yuan
Physics , 2013, DOI: 10.1103/PhysRevA.89.023404
Abstract: The ionization of two-active-electron systems by intense laser fields is investigated theoretically. In comparison with time-dependent Hartree-Fock and exact two electron simulation, we show that the ionization rate is overestimated in SAE approximation. A modified single-active-electron model is formulated by taking into account of the dynamical core polarization. Applying the new approach to Ca atoms, it is found that the polarization of the core can be considered instantaneous and the large polarizability of the cation suppresses the ionization by 50% while the photoelectron cut-off energy increases slightly. The existed tunneling ionization formulation can be corrected analytically by considering core polarization.
Origin of Band-like and Atom-like Features of the Valence Band Auger Emission from Transition Metals

Jianmin YUAN,LFritsche,JNoffke,

材料科学技术学报 , 1999,
Abstract: The occurrence of both band-like and atom-like Auger spectra involving valence band electron of d-transition metals is discussed based on the two-step model of the Auger electron emission, i.e. an initial core-hole is first generated and the Auger transition occurs between the core-hole and the valence states. The occupied valence states relax to screen the core-hole which results in a redistribution of the valence electrons. The electronic states concerned by the Auger transition are calculated by the FLAPW method. There is a clear relation between band-like and atom-like features of the spectra and the different responses of these metals to the existence of a core-hole.
Poultry fat decreased fatty acid transporter protein mRNA expression and affected fatty acid composition in chickens
Jianmin Yuan, Bingkun Zhang, Yuming Guo
Journal of Animal Science and Biotechnology , 2012, DOI: 10.1186/2049-1891-3-17
Abstract: PF had no influence on intestinal morphology, weight, or DNA, RNA, or protein concentrations at 2, 4, and 6?wk of age. However, compared with SBO, PF significantly decreased FATP mRNA abundance at 4?wk (P?=?0.009) and 6?wk of age (P?<?0.001); decreased liver fatty acid-binding protein (L-FABP) mRNA abundance at 6?wk of age (P?=?0.039); and decreased C18:2 (P?=?0.015), C18:3 (P?<?0.001), C20:2 (P?=?0.018), Σ-polyunsaturated fatty acids (Σ-PUFA) (P?=?0.020), and the proportion of PUFA (P?<?0.001) in the intestinal mucosa and decreased C18:2 (P?=?0.010), C18:3 (P?<?0.001), C20:2 (P?<?0.001), Σ-PUFA (P?=?0.005), and the proportion of PUFA (P?<?0.001) in breast muscle at 6?wk of age.PF decreases FATP and L-FABP mRNA expression and decreased the proportion of PUFA in the intestinal mucosa and breast muscle.As an organ of nutrient absorption, the small intestine is very important for animals. The capacity to absorb nutrients depends mainly on the development of the intestinal mucosa. A previous study showed that morphological characteristics of the small intestinal mucosa are affected by diet [1]. Dietary lipids could affect intestinal morphology [2-4], influencing the fatty acid (FA) composition of the apical enterocyte membrane [5] and the fluidity of brush border membranes [6]. This in turn could alter the transportation and diffusion of certain nutrients across the intestine [7].Poultry fat (PF), an available ingredient source, has been widely used as an energy source in swine feeds. A previous study showed that PF appeared to be more efficiently utilized than swine fat for both body weight (BW) gain and the production of carcass energy [8] and did not influence swine performance compared with soybean oil (SBO) [9]. However, few data exist on the effect of PF on the development of intestinal structure and on the absorption and utilization of FA compared with other animal fats or plant oil.Recently, there has been an increasing interest in improving the quality of meat.
Human Susceptibility to Framing Effect in Decisions Can Be Reflected in Scalp Potentials  [PDF]
Jianmin Zeng, Fenghua Zhang, Ying Wang, Qinglin Zhang, Hong Yuan, Lei Jia, Jiang Qiu
Psychology (PSYCH) , 2013, DOI: 10.4236/psych.2013.46077

Humans are susceptible to a famous decision bias named framing effect, which refers that people make different decisions in two decision questions that are intrinsically the same but described in different ways. This intriguing phenomenon has been widely studied with behavioral methods, animal models, and fMRI technique. To date, it’s still unknown whether human susceptibility to this intriguing decision bias can be reflected in scalp potentials. We recorded subjects’ scalp potentials when they decided between risky options and sure options, which were described in positive or negative way. We found that subjects’ brain potential significantly differed between when their choices were consistent with framing effect and when not. More significantly, we found that their susceptibility to framing effect could be reflected in their scalp potentials. Further research in this line can possibly help minimize framing effect bias.

Quantum Langevin molecular dynamics determination of the solar-interior equation of state
Jiayu Dai,Yong Hou,Jianmin Yuan
Physics , 2010, DOI: 10.1088/0004-637X/721/2/1158
Abstract: The equation of state (EOS) of the solar interior is accurately and smoothly determined from \textit{ab initio} simulations named quantum Langevin molecular dynamics (QLMD) in the pressure range of $58 \leq P \leq 4.6\times10^5$ Mbar at the temperature range of $1 \leq T \leq 1500$ eV. The central pressure is calculated, and compared with other models. The effect of heavy elements such as carbon and oxygen on the EOS is also discussed.
Double core-hole spectroscopy of transient plasmas produced in the interaction of ultraintense x-ray pulses with neon
Cheng Gao,Jiaolong Zeng,Jianmin Yuan
Physics , 2015,
Abstract: Double core-hole (DCH) spectroscopy is investigated systematically for neon atomic system in the interaction with ultraintense x-ray pulses with photon energy from 937 eV to 2000 eV. A time-dependent rate equation, implemented in the detailed level accounting approximation, is utilized to study the dynamical evolution of the level population and emission properties of the highly transient plasmas. For x-ray pulses with photon energy in the range of 937-1030 eV, where $1s\rightarrow 2p$ resonance absorption from single core-hole (SCH) states of neon charge states exist, inner-shell resonant absorption (IRA) effects play important roles in the time evolution of population and DCH spectroscopy. Such IRA physical effects are illustrated in detail by investigating the interaction of x-ray pulses at a photon energy of 944 eV, which corresponds to the $1s\rightarrow 2p$ resonant absorption from the SCH states ($1s2s^22p^4$, $1s2s2p^5$ and $1s2p^6$) of Ne$^{3+}$. After averaging over the space and time distribution of the x-ray pulses, DCH spectroscopy at photon energies of 937, 944, 955, 968, 980, and 990 eV (corresponding to the $1s\rightarrow 2p$ resonance energies of Ne$^{2+}$-Ne$^{7+}$, respectively) are studied in detail. The complex mechanisms of producing the DCH states are discussed, taking the DCH spectroscopy at 937 and 980 eV as examples. For photon energy larger than 1362 eV, there are no resonance absorption in the interaction, resulting in a similar physical picture of DCH spectroscopy. The dominant DCH states are due to higher ionization stages of Ne$^{7+}$-Ne$^{9+}$, while the DCH spectroscopy from lower charge states Ne$^{2+}$-Ne$^{6+}$ are much weaker. With the increase of x-ray photon energy, the contributions from the lower charge states become larger.
Dynamic orbitals in high-harmonic generation from CO molecules
Bin Zhang,Jianmin Yuan,Zengxiu Zhao
Physics , 2014, DOI: 10.1103/PhysRevA.90.035402
Abstract: We identify that both the dynamic core polarization and dynamic orbital deformation are important in the orientation-dependent high-harmonic generation of CO molecules subjected to intense few cycle laser fields. These polarization dynamics allow for the observation of strong orientation effects and dynamic minimum in the harmonic spectra. The generated attosecond pulses can be greatly affected by these multielectron effects. This work sheds light on future development of dynamic orbital imaging on attosecond time scale.
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