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Among biomaterials, the mechanical properties of magnesium and its alloys are closest to those of human bone tissue, making these ideal materials for bone tissue repair and replacement. In order to further improve the biocompatibility and biological activity of the magnesium alloy AZ91D, micro‐arc oxidation with a constant‐current power supply mode was employed in this study in a silicate electrolyte solution. The resultant coating surface had a porous structure, and silicon was evenly distributed in it. Further, the results of in vitro experimental studies showed that the silicon‐doped magnesium coating on the surface of the magnesium alloys has no obvious cytotoxicity, and it can induce the proliferation of osteoblasts and promote actin stretching. In addition, it has good biological activity and biocompatibility. Thus, the novel method developed in this study improves the potential for clinical applications of magnesium alloys. [ABSTRACT FROM AUTHOR]

The paper aims at investigating the shear creep property and creep model of marble with structural plane. Marble specimens were taken from diversion tunnel engineering of Jinping II hydropower station. A series of shear creep tests were conducted for two types of marbles with weak structural plane and hard structural plane. The results showed that the creep process of marble with weak structural plane included three creep phases when shear stress was higher. However, shear creep process of marble with hard structural plane only included transition creep phase and steady creep phase and roughness of hard structural plane affected on the shear creep property. Based on the experimental results, a time-dependent statistical damage constitutive model was proposed in terms of fractional calculus theory and damage evolution law to describe the time-dependent damage characteristics. The proposed model was analysed by utilising results of marble creep testing. The results of the analysis showed that the proposed model could describe not only the transient and steady creep phase of marble with weak or hard structural plane, but also the acceleration creep phase of marble with weak structural plane when shear stress is higher. [ABSTRACT FROM AUTHOR]

The triaxial compression tests on siltstone from Datansha of Guangzhou City were done by the RMT-150B multi-function automatic rigid rock servo material testing machine. The loads with five different values of 2,4,6, 8,10 MPa were adopted as confining pressures. A great deal of mesostructural images of Datansha siltstone were obtained by means of scanning electron microscopy (SEM). The mesostructural images of siltstone were processed by regional growing theory based on the image processing technique. The meso-damage information of siltstone microcracks were obtained from SEM images. The mesostructural information of microcracks was analyzed by statistical theory and the distribution regularities of microcrack parameters including angle, length, width, area and number were proposed. It is concluded that the azimuth angle, length and width of Datansha siltstone's microcracks under triaxial compression obey the regularity of generalized extreme value distribution of variable parameters. The azimuth of microcracks mainly focuses on the angle of approximate 35°. With the confining pressure increasing, there is only a substantial growth along the length of the microcracks, while no development on the width. The energy dissipation approach of siltstone samples under triaxial compression has two ways which are the growth of the number and length of microcracks. [ABSTRACT FROM AUTHOR]

An open field experiment was conducted to study the effects of applying controlled-release fertilizer blended with rapidly available chemical N fertilizer on Chinese cabbage yield and quality as well as nitrogen losses, including ammonia volatilization and NO3--N accumulation and leaching in Beijing suburb. The results showed that a combined application of 2:1 controlled-release fertilizer and urea fertilizer (total N rate 150 kg·hm-2) did not induce the reduction of Chinese cabbage yield, and decreased the leaf nitrate and organic acid contents significantly, compared with conventional urea N application (300 kg·hm-2), and had no significant difference in the cabbage yield and leaf nitrate content, compared with applying 150 kg·hm-2 of urea N. The combined application of 2:1 controlled-release fertilizer and urea fertilizer improved the N use efficiency of Chinese cabbage, and reduced the ammonia volatilization and NO3--N leaching. At harvest, the NO3--N concentrations in 20-40, 60-80 and 80-100 cm soil layers were significantly lower in the combined application treatment than in urea N treatment. [ABSTRACT FROM AUTHOR]

The increasing use of nitrogen fertilizers exerts extreme pressure on the environment (e.g., greenhouse gas emissions, GHGs) for winter wheat-summer maize rotation systems in the North China Plain. The application of controlled-release fertilizers is considered as an effective measure to improve crop yield and nitrogen fertilizer utilization efficiency. To explore the impact of one-time fertilization of controlled-release blended fertilizer on crop yield and GHGs of a wheat-maize rotation system, field experiments were carried out in Dezhou Modern Agricultural Science and Technology Park from 2020 to 2022. Five treatments were established for both winter wheat and summer maize, including no nitrogen control (CK), farmers' conventional nitrogen application (FFP), optimized nitrogen application (OPT), CRU1 (the blending ratio of coated urea and traditional urea on winter wheat and summer maize was 5:5 and 3:7, respectively), and CRU2 (the blending ratio of coated urea and traditional urea on winter wheat and summer maize was 7:3 and 5:5, respectively). The differences in yield, nitrogen fertilizer utilization efficiency, fertilization economic benefits, and GHGs among different treatments were compared and analyzed. The results showed that nitrogen application significantly increased the single season and annual crop yields of the wheat-maize rotation system ( P < 0.05). Compared with those of FFP, the CRU1 and CRU2 treatments increased the yields of summer maize by 0.4% to 5.6%, winter wheat by -5.4% to 4.1%, and annual yields by -1.1% to 3.9% ( P > 0.05). N recovery efficiency (NRE), N agronomic efficiency (NAE), and N partial factor productivity (NPFP) were increased by -8.6%-43.4%, 2.05-6.24 kg·kg -1 , and 4.24-10.13 kg·kg -1 , respectively. Annual net income increased by 0.2% to 6.3%. Nitrogen application significantly increased the annual emissions of soil N 2 O and CO 2 in the rotation system ( P < 0.05) but had no effect on the annual emissions of CH 4 (except for in the FFP treatment in the first year). The annual total N 2 O emissions under the CRU1 and CRU2 treatments were significantly reduced by 23.4% to 30.2% compared to those under the FFP treatment ( P < 0.05). Additionally, nitrogen application significantly increased the annual global warming potential (GWP) of the rotation system ( P < 0.05), but the intensity of greenhouse gas emissions was reduced due to the increase in crop yields. Compared with that under FFP, the annual GWP under the CRU1 and CRU2 treatments decreased by 9.6% to 11.5% ( P < 0.05), and the annual GHGs decreased by 11.2% to 13.8% ( P > 0.05). In summary, the one-time application of controlled-release blended fertilizer had a positive role in improving crop yield and economic benefits, reducing nitrogen fertilizer input and labor costs, and GHGs, which is an effective nitrogen fertilizer management measure to promote cleaner production of food crops in the North China Plain.

Degradable resin- coated controlled release fertilizer is one of the hottest current research focuses in the field of fertilizer. In terms of practical application, the photodegradability characteristics of three kinds of coatings including polyethylene/hydrophilic nano-TiO2 composite, polyethylene/hydrophilic nano-TiO2 composite and pure polyethylene were analyzed under irradiation of sunlight and ultraviolet by ATR-FTIR, which was aimed to know their degradation behaviors under two conditions. The result showed that under irradiation of sunlight and ultraviolet, the type of functional group was not changed with the addition of the photo-catalyst, but the photo-catalyst just had an effect on intensity of functional groups. The trend was polyethylene/hydrophobic nano-TiO2 composite>polyethylene/hydrophilic nano-TiO2 composite>pure polyethylene. Furthermore, sunlight and ultraviolet had different effects on molecular structures of coatings. Under irradiation of sunlight, crosslinking reaction took place and ether bond was generated among the carbon chain of polyethylene except for the form of hydroperoxides. Then, carbon chain continued being oxidized to form carbonyl group. The existence of carbonyl group promoted the further degradation of coatings; under irradiation of ultraviolet, high local concentrations of reactive oxygen species were produced and the ability to attack the carbon chain of polymer was strong. Thus, the long alkyl chain of polyethylene was quickly oxidized to form intermediate products containing carbonyl groups. However, the irradiation experiment of ultraviolet didn’t fully reveal the degradation behavior of coatings.

An open field experiment was conducted to study the effects of applying controlled-release fertilizer blended with rapidly available chemical N fertilizer on Chinese cabbage yield and quality as well as nitrogen losses, including ammonia volatilization and NO3- -N accumulation and leaching in Beijing suburb. The results showed that a combined application of 2:1 controlled-release fertilizer and urea fertilizer (total N rate 150 kg x hm(-2)) did not induce the reduction of Chinese cabbage yield, and decreased the leaf nitrate and organic acid contents significantly, compared with conventional urea N application (300 kg x hm(-2)), and had no significant difference in the cabbage yield and leaf nitrate content, compared with applying 150 kg x hm(-2) of urea N. The combined application of 2:1 controlled-release fertilizer and urea fertilizer improved the N use efficiency of Chinese cabbage, and reduced the ammonia volatilization and NO3- -N leaching. At harvest, the NO3- -N concentrations in 20-40, 60-80 and 80-100 cm soil layers were significantly lower in the combined application treatment than in urea N treatment.