Research progress in membrane water treatment technology during 1985-2013 was analyzed based on the bibliometric analysis of published papers in ISI Web of Science Core Collection (Science Citation Index-Expanded, SCI-E) database, and patents in Derwent Innovation Index database. The searched data (18,075 SCI papers and 19,182 patents) were statistically analyzed from different time, countries, research institutions, mainstream technologies and application industries. The results indicated that, the number of papers and patents on the membrane water treatment technology showed an increasing trend. The United States and China published the most SCI papers and patents in this field, respectively. China has become one of the major countries in this field, but the research level should be further improved. The research levels of the United States, Germany and France were in the international leading level in this field. Japan published a small quantity of SCI papers, but possessed many patents and ranked in second place. Moreover, the patentees of the top 10 all belonged to Japanese companies or enterprises. The mainstream technologies in the field of membrane water treatment included microfiltration, ultrafiltration, nanofiltration, reverse osmosis, electrodialysis, pervaporation and liquid membrane. Among these technologies, ultrafiltration, reverse osmosis and nanofiltration were the research hotspots in SCI papers, while reverse osmosis and liquid membrane were the research hotspots in patents. These mainstream technologies were mainly used for the treatment of drinking water and desalination of seawater or brackish water, and it is necessary to promote the application of membrane technologies in industrial wastewater treatment.
The latest Cretaceous magmatic activity in the eastern segment of the Lhasa terrane provides important insights for tracking the magma source and geodynamic setting of the eastern Gangdese batholith, eastward of eastern Himalayan Syntaxis. Detailed petrological, geochemical and geochronological studies of the intrusive rocks (monzodiorites and granodiorites) of the eastern Gangdese batholith are presented with monzodiorites and granodiorites giving zircon U–Pb crystallization dates of 70–66 Ma and 71–66 Ma with εHf(t) values of –4.8 to +6.2 and –1.9 to +5.3, respectively. These rocks are metaluminous to weakly peraluminous I‐type granites showing geochemically arc‐related features of enrichment in LREEs and some LILEs, e.g., Rb, Th, and U, and depletion in HREEs and some HFSEs, e.g., Nb, Ta, and Ti. The rocks are interpreted to be derived from partial melting of mantle material and juvenile crust, respectively, which are proposed to be triggered by Neo‐Tethyan slab rollback during northward subduction, with both experiencing ancient crustal contamination. The studied intrusive rocks formed in a transitional geodynamic setting caused by Neo‐Tethyan oceanic flat subduction to slab rollback beneath the eastern Gangdese belt during the latest Cretaceous.
In analyzing frost heave, researchers often simplify the compressive modulus of freezing soil by considering it as a constant or only as a function of temperature. However, it is a critical parameter characterizing the stress–strain behavior of soil and a variable that is influenced by many other parameters. Hence, herein several one-dimensional freezing experiments are conducted on silty clay in an open system subjected to multistage freezing by considering the compressive modulus as a variable. First, freezing soil under multistage freezing is divided into several layers according to the frozen fringe theory. Then, the correlation between the freezing rate and temperature gradient within each freezing soil layer is investigated. Takashi’s equation for frost heave analysis is modified to extend its application conditions by replacing its freezing rate term with a temperature gradient term. A mechanical model for the stress–strain behavior of freezing soil under the action of frost heave is derived within the theoretical framework of nonlinear elasticity, in which a method for determining the compressive modulus of freezing soil with temperature gradient, overburden pressure, and cooling temperature variables is proposed. This study further enhances our understanding of the typical mechanical behavior of saturated freezing silty clay under frost heave action.
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