775 research outputs found
Binding interaction between (−)-epigallocatechin-3-gallate (EGCG) of green tea and pepsin
Analysis of the binding interaction of (−)-epigallocatechin-3-gallate (EGCG) and pepsin is important for understanding the inhibition of digestive enzymes by tea polyphenols. We studied the binding of EGCG to pepsin using fluorescence spectroscopy, Fourier transform infrared spectroscopy, isothermal titration calorimetry, and protein-ligand docking. We found that EGCG could inhibit pepsin activity. According to thermodynamic parameters, a negative ΔG indicated that the interaction between EGCG and pepsin was spontaneous, and the electrostatic force accompanied by hydrophobic binding forces may play major role in the binding. Data from multi-spectroscopy and docking studies suggest that EGCG could bind pepsin with a change in the native conformation of pepsin. Our results provide further understanding of the nature of the binding interactions between catechins and digestive enzymes
Structure and magnetic properties of sputtered (Nd,Dy)(Fe,Co,Nb,B) \u3csub\u3e5.5\u3c/sub\u3e/M (M = FeCo,Co) multilayer magnets
The magnetic properties of nanocomposite multilayer magnets of the (Nd,Dy)(Fe,Co,Nb,B) 5.5/M (M = Co,FeCo) on Ti-buffered Si substrates have been investigated. X-ray diffraction results reveal that the Nd2Fe14B-type phase in almost all the films is randomly oriented. Different thickness x (nm) for Co layers and y (nm) for FeCo layers were adopted in the multilayers. It is found that high remanence is achieved in the nanocomposite multilayer films consisting of the Nd2Fe14B-type phase and soft magnetic phase for Co with 6≥x≥4 and for FeCo with 10≥y≥6. The enhancement of the remanence in the nanocomposite multilayer films is attributed to the exchange coupling between the magnetically soft and hard phases. Increasing the soft magnetic components results in a continuously decreasing coercivity
Structure and magnetic properties of sputtered (Nd,Dy)(Fe,Co,Nb,B) \u3csub\u3e5.5\u3c/sub\u3e/M (M = FeCo,Co) multilayer magnets
The magnetic properties of nanocomposite multilayer magnets of the (Nd,Dy)(Fe,Co,Nb,B) 5.5/M (M = Co,FeCo) on Ti-buffered Si substrates have been investigated. X-ray diffraction results reveal that the Nd2Fe14B-type phase in almost all the films is randomly oriented. Different thickness x (nm) for Co layers and y (nm) for FeCo layers were adopted in the multilayers. It is found that high remanence is achieved in the nanocomposite multilayer films consisting of the Nd2Fe14B-type phase and soft magnetic phase for Co with 6≥x≥4 and for FeCo with 10≥y≥6. The enhancement of the remanence in the nanocomposite multilayer films is attributed to the exchange coupling between the magnetically soft and hard phases. Increasing the soft magnetic components results in a continuously decreasing coercivity
Scaling Behavior of Anomalous Hall Effect and Longitudinal Nonlinear Response in High-Tc Superconductors
Based on existing theoretical model and by considering our longitudinal
nonlinear response function, we derive a nonliear equation in which the mixed
state Hall resistivity can be expressed as an analytical function of magnetic
field, temperature and applied current. This equation enables one to compare
quantitatively the experimental data with theoretical model. We also find some
new scaling relations of the temperature and field dependency of Hall
resistivity. The comparison between our theoretical curves and experimental
data shows a fair agreement.Comment: 4 pages, 3 figure
Field Driven Pairing State Phase Transition in d_x^2-y^2+id_xy-Wave Superconductors
Within the framework of the Ginzburg-Landau theory for
-wave superconductors, we discuss the pairing state phase
transition in the absence of the Zeeman coupling between the Cooper pair
orbital angular momentum and the magnetic field. We find that above a
temperature , the pairing state in a magnetic field is pure
-wave. However, below , the pairing state is
-wave at low fields, and it becomes pure
-wave at higher fields. Between these pairing states there
exists a field driven phase transition . The transition field increases with
decreasing temperature. In the field-temperature phase diagram, the phase
transition line is obtained theoretically by a combined use of a variational
method and the Virial theorem. The analytical result is found to be in good
agreement with numerical simulation results of the Gingzburg-Landau equations.
The validity of the variational method is discussed. The difference to the case
with the Zeeman coupling is discussed, which may be utilized to the detection
of the Zeeman coupling.Comment: 5 pages, 2 figures, submitted to PRB Brief Repor
New rosette tools for developing rotational vibration-assisted incremental sheet forming
A major limitation of the incremental sheet forming (ISF) is its difficulties to manufacture hard-to-form materials. The existing ISF process variants require additional systems or devices, which compromises the process flexibility and simplicity, the unique advantages of the ISF. In this study, a novel type of rosette tools is proposed for developing a new ISF process to improve material formability, named as Rotational Vibration-assisted ISF (RV-ISF). A hard-to-form material, magnesium alloy AZ31B, has been successfully formed in the RV-ISF experiment by creating low-frequency and low-amplitude vibrations, and elevated temperatures at the local forming zone in the range of 250–450 °C. By developing the new RV-ISF, it has achieved a 60% increase in fracture depth than that by friction-stir ISF and more than 46% reduction in forming force than that by the conventional ISF. Experimental evaluation and analytical prediction of temperature increase, forming force and flow-stress reduction have concluded that the combined thermal effect and vibration softening is the key mechanism leading to the significant formability enhancement. The results show that both the rosette tool design and tool rotational speed are critical factors determining heat generation and transfer as well as vibration frequency and amplitude. Investigation on microstructural evolution has revealed that the low-frequency and low-amplitude vibrations created by the rosette tool have activated dislocations and dynamic recrystallization, and produced refined grains and increased micro hardness. The new RV-ISF developed has potentials to manufacture other hard-to-form materials and complex geometries of sheet products, overcoming the formability limitation of the current ISF technology
The Superconductivity, Intragrain Penetration Depth and Meissner Effect of RuSr2(Gd,Ce)2Cu2O10+delta
The hole concentration (p)(delta), the transition temperature Tc, the
intragrain penetration depth lambda, and the Meissner effect were measured for
annealed RuSr2(Gd,Ce)2Cu2O10+delta samples. The intragrain superconducting
transition temperature Tc} varied from 17 to 40 K while the p changed by only
0.03 holes/CuO2. The intragrain superfluid-density 1/lambda^2 and the
diamagnetic drop of the field-cooled magnetization across Tc (the Meissner
effect), however, increased more than 10 times. All of these findings are in
disagreement with both the Tc vs. p and the Tc vs. 1/lambda^2 correlations
proposed for homogeneous cuprates, but are in line with a possible
phase-separation and the granularity associated with it.Comment: 7 pages, 6 figures, accepted for publication in Phys. Rev. B (May 2,
2002
Direct Measurements of the Branching Fractions for and and Determinations of the Form Factors and
The absolute branching fractions for the decays and
are determined using singly
tagged sample from the data collected around 3.773 GeV with the
BES-II detector at the BEPC. In the system recoiling against the singly tagged
meson, events for and events for decays are observed. Those yield
the absolute branching fractions to be and . The
vector form factors are determined to be
and . The ratio of the two form
factors is measured to be .Comment: 6 pages, 5 figure
BESII Detector Simulation
A Monte Carlo program based on Geant3 has been developed for BESII detector
simulation. The organization of the program is outlined, and the digitization
procedure for simulating the response of various sub-detectors is described.
Comparisons with data show that the performance of the program is generally
satisfactory.Comment: 17 pages, 14 figures, uses elsart.cls, to be submitted to NIM
Measurements of J/psi Decays into 2(pi+pi-)eta and 3(pi+pi-)eta
Based on a sample of 5.8X 10^7 J/psi events taken with the BESII detector,
the branching fractions of J/psi--> 2(pi+pi-)eta and J/psi-->3(pi+pi-)eta are
measured for the first time to be (2.26+-0.08+-0.27)X10^{-3} and
(7.24+-0.96+-1.11)X10^{-4}, respectively.Comment: 11 pages, 6 figure
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