The Kernel polynomial method ͑KPM͒ has been successfully applied to tight-binding electronic-structure calculations as an O(N) method. Here we extend this method to nonorthogonal basis sets with a sparse overlap matrix S and a sparse Hamiltonian H. Since the KPM method utilizes matrix vector multiplications it is necessary to apply S Ϫ1 H onto a vector. The multiplication of S Ϫ1 is performed using a preconditioned conjugate-gradient method and does not involve the explicit inversion of S. Hence the method scales the same way as the original KPM method, i.e., O(N), although there is an overhead due to the additional conjugategradient part. We apply this method to a large scale electronic-structure calculation of amorphous diamond.
The chromosome is an important genetic material carrier in living individuals and the spatial conformation (mainly referring to the chromosomal structure, quantity, centromere position and other morphological information) may be abnormal or mutated. Thus, it may generate a high possibility to cause diseases. Generally, the karyotype of chromosome G-bands is detected and analyzed using an optical microscope. However, it is difficult to detect the G-band structures for traditional optical microscopes on the nanometer scale. Herein, we have studied the detection method of chromosome G-band samples by atomic force microscopy (AFM) imaging.The structures of chromosome G-banding are studied with different trypsin treatment durations. The experiment result shows that the treatment duration of 20 s is the best time to form G-band structures. The AFM images show the structures of chromosome G-bands which cannot be observed under an optical microscope. This work provides a new way for the detection and diagnosis of chromosome diseases on the nanometer scale.
This study aimed to reveal the impact of the severe drying-wetting process on the safety and stability of high-altitude dumps. Numerical calculations were conducted for the open mining dump of limestone mines for cement in high-altitude mining areas. The distribution law equation of the matric suction and the shear strength equation were imported for unsaturated soil based on the unsaturated-saturated seepage theory. Therefore, the evolution characteristics of the unsaturated-saturated seepage field and the stability of the dump were studied under severe drying-wetting. The results indicated the following rules: As the intensity of the wetting-drying alternation increased, the surface soil on the dump changed from an unsaturated to a saturated state, the matric suction continued to decrease until it reached zero, the shear strength decreased, and the unsaturated area shrank. The dump slipped under the influence of the drying-wetting alternation, the sliding area was the dump itself, and developed to the deep layer as the intensity of the drying-wetting alternation strengthened. The cumulative settlement value of the dump increased with time and eventually stabilized, and the maximum accumulative settlement value calculated by simulation was in good agreement with the actual monitoring value. The safety factor decreased as the intensity of the drying-wetting alternation increased.
Epoxide nitrile butadiene rubber (ENBR) was prepared via in situ epoxidation from nitrile butadiene rubber (NBR) with acetic acid and hydrogen peroxide.
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