Wyniki wyszukiwania - Biblioteka Nauki

Nowa wersja platformy, zawierająca wyłącznie zasoby pełnotekstowe, jest już dostępna.
Przejdź na https://bibliotekanauki.pl

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Failure characteristics of jointed rock-like material containing multi-joints under a compressive-shear test: Experimental and numerical analyses

100%

Cao R. H. , Cao P. , Lin H. , Ma G. W. , Zhang C. Y. , Jiang C.

Archives of Civil and Mechanical Engineering

2018

tom Vol. 18, no. 3

784--798

Extensive efforts have been made to gain a better understanding of the failure behaviour of rocks and rock-like materials, but crack propagation and failure processes under compressive-shear loading have not yet been comprehensively investigated. To address this area of research, the peak shear strengths (τ) and failure processes of specimens with multiple joints are studied by lab testing and particle flow code (PFC2D). Four types of failure modes are observed: (a) shear failure through a plane (Mode-I), (b) intact shear failure (Mode-II), (c) oblique shear crack connection failure (Mode-III), and (d) stepped path failure (Mode-IV). The failure mode gradually transformed to Mode-III as α (joint inclination angle) increases from 0° to 90° in the specimens. In addition, with increasing joint distance (d) in the specimens, the failure mode changes to Mode-II. As the non-overlapping length between joints (c) in the specimens increases, the failure mode changes to Mode-IV. The joint geometry has a major influence on the shear strength of the jointed specimens. The peak shear strength of specimens with different joint inclination angles is obtained when α = 45°. Additionally, the peak shear strength increases as the joint distance (d) and non-overlapping length (c) increase.

Downregulation of the lycopene ε-cyclase gene confers tolerance to salt and drought stress in Nicotiana tabacum

59%

Shi J. , Liu P. , Xia Y. , Wei P. , Li W. , Zhang W. , Chen X. , Cao P. , Xu Y. , Jin L. , Li F. , Luo Z. , Wei C. , Zhang J. , Xie X. , Qu L. , Yang J. , Lin F. , Wang R.

tom 37

nr 10

Lycopene ε-cyclase (ε-LCY) functions at a branch point of the carotenoid biosynthesis pathway and modulates the ratio of lutein to the β-carotenoids. RNA interference (RNAi) and overexpression (OE) of Ntε-LCY were used to evaluate the physiological roles of ε-LCY in Nicotiana tobacum. In leaves, strong accumulation of β branch carotenoids and high expression of carotenoid biosynthesis genes resulted from suppression of Ntε-LCY expression. RNAi plants showed enhanced salt and drought tolerance, while overexpression of the Ntε-LCY gene weakened tolerance to salt and drought stress, as compared to control. Further analysis revealed that RNAi plants exhibited less water loss and had lower reactive oxygen species levels than did WT plants after both the salt and drought treatments. Further, higher levels of ABA accumulated in the RNAi lines than in the WT lines under stress conditions. These results suggest that reduced Ntε-LCY expression can improve drought and salinity tolerance in Nicotiana tabacum by enhancing their ROS scavenging ability.