Direct use of unassigned resonances in NMR structure calculations with proxy residues

We present a method that significantly enhances the robustness of (automated) NMR structure determination by allowing the NOE data corresponding to unassigned NMR resonances to be used directly in the calculations. The unassigned resonances are represented by additional atoms or groups of atoms that have no interaction with the regular protein atoms except through distance restraints. These so-called "proxy" residues can be used to generate NOE-based distance restraints in a similar fashion as for the assigned part of the protein. If sufficient NOE information is available, the restraints are expected to place the proxies at positions close to the correct atoms for the unassigned resonance, which can facilitate subsequent assignment. Convergence can be further improved by supplying additional information about the possible identities of the unassigned resonances. We have implemented this approach in the widely used automated assignment and structure calculation protocols ARIA and CANDID. We find that it significantly increases the robustness of structure calculations with regard to missing assignments and yields structures of higher quality. Our approach is still able to find correctly folded structures with up to 30% randomly missing resonance assignments, and even when only backbone and beta resonances are present! This should be of significant value to NMR-based structural proteomics initiatives.     

Rheological and Coating Properties of Modified Silica Sols

The rheological behavior of modified silica sols has been investigated by gel formation kinetics and dynamic flowing within the pH range 3–7 and the temperature range 20–50°C. The sols show pseudo-plastic behavior at low shear-rates, with Newtonian behavior below 100 s–1. Oscillation measurements reveal that gelation starts with a significant decrease of phase difference <10°, because of a strong increase in elastic behavior. After solidification the values of phase difference increase, indicating a partial destruction of the gel structure due to stress. The relationship between the viscosity of the modified silica sols and their coating parameters was compared for both dip coating and continuous coating with a slide coating unit.     

Gravitational,electromagnetic, and nuclear theory

Through an examination of neutron lifetimes we shall propose a new theory of gravitational, electromagnetic, and nuclear fields. The fundamental assumption of our theory is that the motion of a particle in a combination of gravitational, electromagnetic, and nuclear fields is determined from a variational principle of the form _A ^B d=0. The form of the physical time is determined from an examination of classical equations of motion. The field equations are determined from an examination of Maxwell-Einstein theory and Yukawa theory. Utilizing the standard elementary model of the deuteron, the theory predicts that at a proton-neutron separationr 10^–13 cm the neutron lifetime is infinite and that nucleons have a repulsive core. These predictions have been experimentally verified.     

发光玻璃在X射线实时成像系统中的应用

介绍了以铽（Ｔｂ）激活的高密度发光玻璃和光导纤维发光玻璃的特性。它应用在Ｘ射线实时成像系统中,可大大改善空间分辨能力。用它做的转换屏比一般晶粒状荧光物质做的厚得多,特别适合用于高能Ｘ射线实时成像系统