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Self-propelled directional liquid transport (SDLT) has been observed on many natural substrates, serving as an efficient strategy to utilize surrounding liquids for a better habitat to the local environment. Drawing inspiration, various artificial materials capable of SDLT have been developed. However, the liquid transport velocity is normally very low (ca. 3-30 μm/s), which limits its practical applications. Herein, we developed novel pyramid-structured fibers with concave curved surfaces (P-concave curved-fiber, PCCF), which enable the ultrafast SDLT. Specifically, the liquid transport velocity can be up to ∼28.79 mm/s on a dry tri-PCCF, over 50 times faster than that on the surface of Sarracenia trichome (∼520 μm/s). The velocity is even faster on a wet fiber by two times (∼47.34 mm/s). Here, the Laplace pressure difference (FL) induced by the tapered structure determines the liquid transport direction. It is proposed that both the capillary rises imparted by the concave curved surfaces and the oriented microridges/valleys and the enhanced FL aroused by the reduced cross-sectional area accelerate the SDLT on surfaces of the PCCFs. Consequently, the PCCF takes a different liquid transport strategy with a convex-shaped advancing meniscus, differing from that on traditional conical fibers. Moreover, the as-developed PCCF is also applicable for underwater ultrafast SDLT of oil. We envision that the result will open a new perspective for fabricating a fibrous system for microfluidic and liquid manipulation.

Kaifeng is rich in geothermal resources. It is important to clarify its genetic model for its further sustainable utilization. In this paper, the geothermal geological conditions of Kaifeng Depression are analyzed, the circulation of geothermal water in Kaifeng area are discussed by using hydrochemical and isotopic data, and the conceptual model of geothermal system is preliminarily established.

Deep saline aquifers are considered as the most promising option for geologic disposal of CO2. One of the main concerns, however, is the integrity of the caprocks between and above the storage formations. Here, a hydrogeochemical and isotopic investigation is presented, using ionic chemistry, stable isotopes (δ18O, δ2H and 87Sr/86Sr) and radiocarbon dating, on five saline aquifers on a regional scale, namely: Neogene Minghuazhen, Guantao, Ordivician, Cambrian and Precambrian, all found in the Bohai Bay Basin (BBB) in North China. Groundwater recharge, flow pattern, age and mixing processes in the saline aquifers show that the Neogene Guantao Formation (Ng) in the Jizhong and Huanghua Depressions on both of the west and east sides of the Cangxian Uplift is a prospective reservoir for CO2 sequestration, with a well confined regional seal above, which is the clayey layers in the Neogene Minghuazhen Formation (Nm). However, this is not the case in the Cangxian Uplift, where the Ng is missing where structural high and fault zones are developed, creating strong hydraulic connections and trans-formational flow to the Nm aquifer. Comparing storage capacity and long-term security between the various hydrogeologic units, the depressions are better candidate sites for CO2 sequestration in the BBB.

Coal collapse columns are special geologic structures developed in the coal fields in North China. Water bursting related to the columns is characterized by large flow rates and is difficult to be predicted. In some cases, it is difficult to distinguish coal collapse columns and faults. Here, we propose a method based on sediment dating combined with borehole drilling and geophysical surveys. By application of the method to the Guqiao coal mine in the Huainan coal field, we recognized a significant offset of the Quaternary units around a geologic structure, and inferred that it cannot result from coal collapse columns but by faulting, and determined the ages of the faults.

The Neogene Guantao formation in the Beitang sag in the Bohai Bay Basin (BBB) of North China, a Mesozoic–Cenozoic sedimentary basin of continental origin, has been chosen as a candidate for a pilot field test of CO2 sequestration. Hydrogeological and geochemical investigations have been carried out to assess its suitability, taking advantage of many existing geothermal wells drilled to 2000 m or greater depths. Water samples from 25 wells and drill cores of three sections of the Guantao formation were collected for measurements of mineralogy, water chemistry and isotopes (d

Sustainable development of geothermal resources is the key to prolong the commercial life of geothermal fields. This paper uses two well-known geothermal fields in China, with long histories of production, to demonstrate how sustainability can be quantitatively evaluated, and to highlight the essential differences between sustainable and non-sustainable development schemes. After examining the complex nature of sustainability evaluation, fuzzy synthetic evaluation is applied as a tool for the quantitative sustainability rating of geothermal reservoirs. The evaluation procedures include systemic criteria selection, weighing, individual criterion evaluation and finally final multi-criterion decision analysis evaluation. The sustainability of a limestone reservoir in the urban sector of Tianjin is rated rather low because of insufficient levels of water injection. On the contrary, the carbonate rock reservoirs of the Xiaotangshan geothermal field in suburban Beijing have a strong sustainability rating, mainly due to high injection rates.