Access to information on sustainable intensification practices for new agricultural business entities in China.

The adoption of sustainable intensification practices (SIPs) is generally lagging in China, as disseminating new technology to millions of farmers on heterogeneous smallholdings is challenging. Agricultural development strategies emphasise the role of new agricultural business entities (NABEs) in driving smallholder farmers' development. This study used a sustainable intensive apple culture system as an example of an SIP. To understand the effects of different information dissemination channels, extension service attributes, social networking structures, and socioeconomic factors on the efficiency of acquiring information on SIPs by NABEs, we used the censored least absolute deviation to analyse the data obtained from face-to-face interview surveys of 218 NABEs in the Loess Plateau. This study found that direct connections between NABEs and research institutions had the strongest facilitating effect on information acquisition, farm shops had the second strongest effect, agricultural extension agencies had the weakest effect, and field agricultural material promotion workers showed a significant adverse effect. Improving the quality of extension services has a far greater effect on facilitating the acquisition of information on SIPs than does increasing extension intensity. Relying primarily on weak ties to manage plantations significantly facilitated information acquisition, whereas relying on strong ties to manage plantations significantly inhibited acquisition. The study results show that implementing the "research institute + NABEs + smallholder farmers" technology extension model can significantly improve the adoption efficiency of SIPs.

Study of Township Construction Land Carrying Capacity and Spatial Pattern Matching in Loess Plateau Hilly and Gully Region: A Case of Xifeng in China.

With the acceleration of urbanization, the construction land scale of urban and rural areas is constantly expanding, which leads to contradiction and conflict between territorial development and ecological protection becoming more and more serious. Therefore, as an important unit of county (district), and even urban and rural, development, the study on land resource carrying capacity and the rationality of the development can provide some basis for developing the optimal strategies of differential territorial space. Taking Xifeng, Gansu Province, China as the research area, this study constructs the evaluation index system of township construction land carrying capacity from the three dimensions of ecological protection, natural environment, and social economy. It evaluates the suitability of township construction land by the means of a comprehensive scoring method and discusses the carrying capacity and spatial pattern matching of township construction land based on the suitability evaluation results. The results showed that: (1) the spatial difference of suitability of construction land is obvious, which is higher in the city center than in the surrounding areas; (2) the comprehensive carrying capacity of township construction land is 52.62%, and different townships range from 3.78% to 13.15%. It is different between towns; (3) on the whole, the condition of township construction land is well-developed, and the main distribution forms are flaky, banded, and dotted. (4) There is a positive correlation between spatial matching and carrying capacity. The carrying capacity should be considered in regional development to avoid overdevelopment. It can provide a basis for optimizing the territorial spatial layout, strengthening the coordinated development among townships, and improving the comprehensive township carrying capacity in the Loess Plateau hilly and gully region.

Modified graphene/polyimide nanocomposites: reinforcing and tribological effects.

By taking advantage of design and construction of strong graphene-matrix interfaces, we have prepared modified graphene/polyimide (MG/PI) nanocomposites via a two-stage process consisting of (a) surface modification of graphene and (b) in situ polymerization. The 2 wt % MG/PI nanocomposites exhibited a 20-fold increase in wear resistance and a 12% reduction in friction coefficient, constituting a potential breakthrough for future tribological application. Simultaneously, MG also enhanced thermal stability, electrical conductivity, and mechanical properties, including tensile strength, Young's modulus, storage modulus, and microhardness. Excellent thermal stability and compatibility of interface, strong covalent adhesion interaction and mechanical interlocking at the interface, as well as homogeneous and oriented dispersion of MG were achieved here, contributing to the enhanced properties observed here. The superior wear resistance is ascribed to (a) tribological effect of MG, including suppression effect of MG in the generation of wear debris and protective effect of MG against the friction force, and (b) the increase in mechanical properties. In light of the relatively low cost and the unique properties of graphene, the results of this study highlight a pathway to expand the engineering applications of graphene and solve wear-related mechanical failures of polymer parts.

Chemically modified graphene/polyimide composite films based on utilization of covalent bonding and oriented distribution.

Herein, we have developed a rather simple composite fabrication approach to achieving molecular-level dispersion and planar orientation of chemically modified graphene (CMG) in the thermosetting polyimide (PI) matrix as well as realizing strong adhesion at the interfacial regions between reinforcing filler and matrix. The covalent adhesion of CMG to PI matrix and oriented distribution of CMG were carefully confirmed and analyzed by detailed investigations. Combination of covalent bonding and oriented distribution could enlarge the effectiveness of CMG in the matrix. Efficient stress transfer was found at the CMG/PI interfaces. Significant improvements in the mechanical performances, thermal stability, electrical conductivity, and hydrophobic behavior were achieved by addition of only a small amount of CMG. Furthermore, it is noteworthy that the hydrophilic-to-hydrophobic transition and the electrical percolation were observed at only 0.2 wt % CMG in this composite system. This facile methodology is believed to afford broad application potential in graphene-based polymer nanocomposites, especially other types of high-performance thermosetting systems.

[Comparative study of friction and wear behavior of different human enamel in vitro].

OBJECTIVE: To investigate the friction and wear behavior of different human enamels. METHODS: 24 enamel samples selected from aged, young permanent and faded deciduous teeth were classified into 3 groups and slid against artificial porcelain teeth in the presence of artificial saliva on an oscillating friction and wear test rig. The wear volume loss, microhardness and toughness of each group of the enamel specimens were measured, the wear scars were observed with a scanning electron microscope, and the elemental compositions of Ca, P, and Si of the wear scar and wear debris were determined with an energy dispersion spectrometer. RESULTS: The wear volume losses of aged, young permanent and deciduous tooth enamels are (2.40 +/- 1.10) x 10(-12) m(3), (3.50 +/- 1.83) x 10(-12) m(3) and (4.86 +/- 2.49) x 10(-12) m(3). The data of aged tooth enamels are statistically greater than that of deciduous tooth enamels (P < 0.05). There is no significant difference between the wear volume loss of aged and young permanent tooth enamels or between the young permanent and deciduous tooth enamels (P > 0.05). However, the friction and wear behavior of each group of enamel specimens is different from each other. CONCLUSIONS: In the present testing condition, the wear scars of each kind of enamel specimens is characterized by ploughing and cracking. The different wear resistance of the three kinds of enamels is attributed to the different microstructure of the enamel, while the hardness and toughness of the enamels are not correlated with the wear resistance.