Select
Conditions for ponderomotive resonances in the Kapitza–Dirac effect
Chao Yu,Jingtao Zhang,Zhenrong Sun,Ju Gao,Dong-Sheng Guo
Front. Phys. . 2015, 10 (5 ): 104208-.
https://doi.org/10.1007/s11467-015-0499-4
By applying a nonperturbative quantum electrodynamic theory, we study ponderomotive resonances when an electron beam is scattered by a standing photon wave. Our study shows that the ponderomotive parameter u p , the ponderomotive energy per laser-photon energy, for each of the two traveling laser modes possesses a minimum value ℏ ω / ( m e c 2 ) . Ponderomotive resonances occur only when the ratio of the laser photon energy to the electron rest-mass energy is a fraction, where the denominator is twice the square of a positive integer and the numerator is the total ponderomotive number, which is also a positive integer.
References |
Related Articles |
Metrics
Select
The Boson peak in confined water: An experimental investigation of the liquid-liquid phase transition hypothesis
Francesco Mallamace,Carmelo Corsaro,Domenico Mallamace,Zhe Wang,Sow-Hsin Chen
Front. Phys. . 2015, 10 (5 ): 106103-.
https://doi.org/10.1007/s11467-015-0487-8
The Boson peak (BP) of deeply cooled confined water is studied by using inelastic neutron scattering (INS) in a large interval of the (P , T ) phase plane. By taking into account the different behavior of such a collective vibrational mode in both strong and fragile glasses as well as in glass-forming materials, we were able to determine the Widom line that characterizes supercooled bulk water within the frame of the liquid-liquid phase transition (LLPT) hypothesis. The peak frequency and width of the BP correlated with the water polymorphism of the LLPT scenario, allowing us to distinguish the “low-density liquid” (LDL) and “high-density liquid” (HDL) phases in deeply cooled bulk water.Moreover, the BP properties afford a further confirmation of theWidom line temperature T W as the (P , T ) locus in which the local structure of water transforms from a predominately LDL form to a predominately HDL form.
References |
Related Articles |
Metrics
Select
Dynamical changes in hydration water accompanying lysozyme thermal denaturation
Francesco Mallamace,Carmelo Corsaro,Domenico Mallamace,Nicola Cicero,Sebastiano Vasi,Giacomo Dugo,H. Eugene Stanley
Front. Phys. . 2015, 10 (5 ): 106104-.
https://doi.org/10.1007/s11467-015-0486-9
We study the dynamics of the first hydration shell of lysozyme to determine the role of hydration water that accompanies lysozyme thermal denaturation. We use nuclear magnetic resonance spectroscopy to investigate both the translational and rotational contributions. Data on proton self-diffusion and reorentational correlation time indicate that the kinetics of the lysozyme folding/unfolding process is controlled by the dynamics of the water molecules in the first hydration shell. When the hydration water dynamics change, because of the weakening of the hydrogen bond network, the three-dimensional structure of the lysozyme is lost and denaturation is triggered. Our data indicates that at temperatures above approximately 315 K, water behaves as a simple liquid and is no longer a good solvent.
References |
Related Articles |
Metrics
Select
Water and lysozyme: Some results from the bending and stretching vibrational modes
Francesco Mallamace,Carmelo Corsaro,Domenico Mallamace,Cirino Vasi,Nicola Cicero,H. Eugene Stanley
Front. Phys. . 2015, 10 (5 ): 106105-.
https://doi.org/10.1007/s11467-015-0488-7
The dynamic or glass transition in biomolecules is important to their functioning. Also essential is the transition between the protein native state and the unfolding process. To better understand these transitions, we use Fourier transform infrared spectroscopy to study the vibrational bending and stretching modes of hydrated lysozymes across a wide temperature range. We find that these transitions are triggered by the strong hydrogen bond coupling between the protein and hydration water. More precisely, we demonstrate that in both cases the water properties dominate the evolution of the system. We find that two characteristic temperatures are relevant: in the supercooled regime of confined water, the fragile-to-strong dynamic transition occurs at T L , and in the stable liquid phase, T * ≃ 315 ± 5 K characterizes the behavior of both isothermal compressibility K T (T,P ) and the coefficient of thermal expansion a P (T,P ).
References |
Related Articles |
Metrics
Select
Quantum phase transitions in two-dimensional strongly correlated fermion systems
Bao An(保安),Chen Yao-Hua(陈耀华),Lin Heng-Fu(林恒福),Liu Hai-Di(刘海迪),Zhang Xiao-Zhong(章晓中)
Front. Phys. . 2015, 10 (5 ): 106401-.
https://doi.org/10.1007/s11467-015-0498-5
In this article, we review our recent work on quantum phase transition in two-dimensional strongly correlated fermion systems. We discuss the metal−insulator transition properties of these systems by calculating the density of states, double occupancy, and Fermi surface evolution using a combination of the cellular dynamical mean-field theory (CDMFT) and the continuous-time quantum Monte Carlo algorithm. Furthermore, we explore the magnetic properties of each state by defining magnetic order parameters. Rich phase diagrams with many intriguing quantum states, including antiferromagnetic metal, paramagnetic metal, Kondo metal, and ferromagnetic insulator, were found for the two-dimensional lattices with strongly correlated fermions. We believe that our results would lead to a better understanding of the properties of real materials.
References |
Related Articles |
Metrics
14 articles