Synergistic mechanism and environmental behavior of tank-mix adjuvants to topramezone and atrazine.

An effective way to reduce herbicide quantity is to use adjuvants in order to optimize the amount of herbicide and improve its control efficiency. In order to screen for efficient herbicide tank-mix adjuvants, improve the control of weeds in maize fields, reduce the amount of effective ingredients, and improve the adsorption and digestion behavior of herbicides in soil, this study evaluated the synergistic effects and soil behavior of four types of tank-mix adjuvants combined with herbicides. Different types of adjuvants can enhance herbicide production. Surface tension was significantly reduced by 13% after the pesticide solution was applied with AgroSpred™ Prime. The contact angle with the foliar surface was significantly reduced and solution wettability improved using Atp Lus 245-LQ-(TH). The permeability of topramezone and atrazine in leaves of Amaranthus retroflexus L. and Digitaria sanguinalis (L.) Scop. was increased by 22-96% after adding either tank-mix adjuvant. The solution drying time and maximum retention on leaves were not affected by the tank-mix adjuvants. Ethyl and methylated vegetable oils can reduce the adsorption of topramezone in the soil, thus reducing its half-life in soil. The tank-mix adjuvants had no significant effect on soil dissipation or adsorption of atrazine. AgroSpred™ Prime and Atp Lus 245-LQ-(TH) have the best synergistic effect on topramezone and atrazine in the control of A. retroflexus L. and D. sanguinalis (L.) Scop. in maize fields.

Effects of Tearing Conditions on the Crack Propagation in a Monolayer Graphene Sheet.

The path of crack propagation in a graphene sheet is significant for graphene patterning via the tearing approach. In this study, we evaluate the fracture properties of pre-cracked graphene during the tearing process, with consideration of the effects of the aspect ratio, loading speed, loading direction, and ambient temperatures on the crack propagation in the monolayer sheet. Some remarkable conclusions are drawn based on the molecular dynamic simulation results, i.e., a higher loading speed may result in a complicated path of crack propagation, and the propagation of an armchair crack may be accompanied by sp carbon links at high temperatures. The reason for this is that the stronger thermal vibration reduces the load stress difference near the crack tip and, therefore, the crack tip can pass through the sp link. A crack propagates more easily along the zigzag direction than along the armchair direction. The out-of-plane tearing is more suitable than the in-plane tearing for graphene patterning. The path of crack propagation can be adjusted by changing the loading direction, e.g., a rectangular graphene ribbon can be produced by oblique tearing. This new understanding will benefit the application of graphene patterning via the tearing approach.

Tunable ductility of a nano-network from few-layered graphene bonded with benzene: a molecular dynamics study.

Developing novel graphene-based materials with unique mechanical properties is of significance to meet the requirements in new applications. The pristine graphene shows a brittle fracture when the stretching strain on it exceeds the critical value. Further, it fails to bear the external load. Herein, to enhance the ductility of the pristine graphene, we proposed a corrugated sandwich carbon network based on few-layered graphene, in which the two surface layers are bonded with several corrugated core layers via benzene molecules. The effects of factors such as the geometry, temperature, and strain rate on the ductility of the carbon network were evaluated using the uniaxial tension tests by molecular dynamics simulations. Results show that the new carbon material has more than one peak fracture strain in stretching. The second peak fracture strain is proportional to the length difference between the surface layers and core layers. Hence, the carbon network has a tunable ductility, which suggests a flexible design of such novel materials in a nanostructure/nanodevice with large deformation.

Flavonoid accumulation in cell suspension cultures of Glycyrrhiza inflata Batal under optimizing conditions.

Cell growth and flavonoid production in cell suspension cultures of Glycyrrhiza inflata Batal were investigated under various initial inoculum densities, and sucrose and nitrogen concentrations to develop an optimization method for an improved flavonoid production. Both biomass accumulation and flavonoid production exhibited an "S" curve in one culture cycle, with the greatest value obtained on day 21, which showed that cell growth and flavonoid biosynthesis went along isochronously. Moreover, according to the biomass and flavonoid production, the appreciate inoculum density, and the sucrose and nitrogen concentrations were 50 g FW L(-1), 50 g L(-1) and 120 mmol L(-1), respectively. In addition, cell growth and flavonoid production showed a peak of 16.4 g DW L(-1) and 95.7 mg L(-1) on day 21 under the optimizing conditions, respectively. The flavonoid productivity of the cells which were cultured for 3 years is higher than that of the 3-year-old plant, which suggested that flavonoid production by cell cultures of G. inflata is a potentially profitable method. Therefore, this work is considered to be helpful for efficient large-scale bioprocessing of cell cultures in bioreactors.

Influence of drought on oxidative stress and flavonoid production in cell suspension culture of Glycyrrhiza inflata Batal.

The effect of water deficit on flavonoid production and physiological parameters characteristic for oxidative stress were studied in a cell suspension culture of Glycyrrhiza inflata Batal to investigate its drought tolerance. The result indicated that appropriate water deficit enhanced biomass accumulation of 27.1 g L(-1) and flavonoid production of 151.5 mg L(-1), which was about 2-fold and 1.5-fold of the control, respectively. But it decreased the water content. Drought stress led to hydrogen peroxide accumulation more than in the control. Moreover, under drought conditions, malondialdehyde content, the activities of catalase and peroxidase increased to a greater extent than the control, and each reached a maximum value of 91.3 micromol g(-1) dry weight, 85.6 U and 1951 U g(-1) dry weight per min, which was 1.5-, 1.7- and 3.7-fold of the control, respectively. All above showed that appropriate water deficit could activate the antioxidative defense enzymes system to maintain stability in plants subjected to drought stress. On the contrary, the activity of phenylalanine ammonia lyase of the control increased in company with the biosynthesis of flavonoids, which indicated that phenylalanine ammonia lyase might play an important role in the path of the biosynthesis of flavonoids.