An Experimental Investigation of Moisture-Induced Softening Mechanism of Marble Based on Quantitative Analysis of Acoustic Emission Waveforms

The decrease of strength after saturation of rocks is known as moisture-induced softening. To date, there are numerous studies on the mechanism of moisture-induced softening of different rocks. However, due to a lack of effective observational methods, the microcosmic mechanism of moisture-induced softening still needs to be understood. We collected and processed acoustic emission (AE) signals during the uniaxial compression test of marble specimens. The results of spectral and statistical analysis show that two dominant frequency bands of AE waveforms exist regardless of the specimen’s water content. Additionally, for the AE signals from the saturated specimens, the ranges of the low and high frequency bands are wider than dried rock samples. Besides, since the tensile and shear failures in the rock release low and high dominant frequency AE signals, respectively, the test results of this paper show that micro-shear and micro-tensile failures dominate the final failure of dried and saturated rocks, respectively.

Study on Strength Characteristics of Solidified Contaminated Soil under Freeze-Thaw Cycle Conditions

Cement solidification/stabilization is a commonly used method for the remediation of contaminated soils. The stability characteristics of solidified/stabilized contaminated soils under freeze-thaw cycle are very important. A series of tests, which include unconfined compressive strength tests, freeze-thaw cycle tests, and scanning electron microscopy (SEM) tests, are performed to study the variation law of strength characteristics and microstructure. It aims at revealing the microcosmic mechanism of solidified/stabilized Pb2+ contaminated soils with cement under freeze-thaw cycle. The results show that the unconfined compressive strength of the contaminated soils significantly improved with the increase of the cement content. The unconfined compressive strength of stabilized contaminated soils first increases with the increase of times of freeze-thaw cycle, and after reaching the peak, it decreases with the increase of times of freeze-thaw cycle. The results of the scanning electron microscopy tests are consistent with those of the unconfined compressive strength tests. This paper also reveals the microcosmic mechanism of the changes in engineering of the stabilized contaminated soils under freeze-thaw cycle.

DNA and DNA computation based on toehold-mediated strand displacement reactions

Other than being a carrier of the code of life deoxyribonucleic acid (DNA) can also be used as a kind of ideal biomaterial with good biocompatibility. The basis of DNA dynamic nanotechnology is the toehold-mediated strand displacement reactions. Utilizing the specificity and predictability of Watson–Crick base pairing, and the programmability of the base sequence of DNA, researchers can construct the molecular machine and precisely control its operation to realize various complex molecular calculations. In this paper, we reviewed the progress of DNA structure and mechanical properties in recent years, discussed the microcosmic mechanism of DNA strand replacement reaction, and introduced the latest achievements in DNA molecular computing and its application in DNA constant temperature self-assembly.

A Report on the Effect of Electromagnetic Radiation on the Growth of Silkworm in Mobile Phone

This study was conducted to study the growth process of silkworm eggs in a silkworm research center under the condition of no electromagnetic radiation and strong electromagnetic radiation. In the course of the study, the silkworm seeds were randomly divided into two groups. All the mulberry leaves were used to observe and record the time of molting dormancy growth and the related physiological parameters were recorded and recorded. The effect of mobile phone radiation on the growth process of silkworm larvae was analyzed. Based on the experimental results, the microcosmic mechanism of the effects of mobile radiation on organisms and adolescents was analyzed and the preventive measures were put forward. First, for young people as much as possible to reduce the frequency of mobile phone use, thereby reducing the adverse effects of electromagnetic radiation on the growth and development of young people, to develop good habits. Second, the social and electromagnetic wave management departments attach importance to strengthen the rational use of electromagnetic waves.