C-S-H Seeds Accelerate Early Age Hydration of Carbonate-Activated Slag and the Underlying Mechanism

The slow hardening process of carbonate-activated slag limits its application as a construction material. This paper aims to provide an acceleration method for the early age hydration of carbonate-activated slag by applying calcium silicate hydrate (C-S-H) seeds and unveil the underlying mechanism. The results show that the incorporation of C-S-H seeds significantly accelerates the early age reaction of carbonate-activated slag and shortens the setting time. With 4% of calcium silicate hydrate (C-S-H) seeds, the 1d-compressive strength of carbonate activates slag can achieve 25.4 MPa. The C-S-H seeds acts as the preferred nucleation sites for the strength-giving phase C-A-S-H gel and the carbonate-containing phases (e.g., calcite, gaylussite, hydrotalcite, etc.), and accelerates hydration. The dormant period of samples with C-S-H seeds becomes negligible, confirming that the seeding effect that controls the saturation limits of the pore solution is the major reason for the accelerated hydration

New Insights into the Nitrogen Isotope Compositions in Coals from the Huainan Coalfield, Anhui Province, China: Influence of the Distribution of Nitrogen Forms

A combination of nitrogen isotope analysis and X-ray photoelectron spectroscopy techniques was used to characterize nitrogen isotopic compositions and organic nitrogen forms in a total of 11 coal samples from China. A range of delta N-15 values between -2.9 parts per thousand and +3.6 parts per thousand was observed in all coals, and the N-5 peak is predominant. The results show that a correlation exists between the delta N-15 value and the proportions of the N-S peak and the sum of the N-6 and N-Q peaks. This suggests that the nitrogen isotopic composition of coal may be controlled by the distribution of nitrogen forms. The pyridinic-structure nitrogen is enriched in N-15 compared with the pyrrolic-structure nitrogen

The Research on Complex Lithology Identification Based on Well Logs: A Case Study of Lower 1st Member of the Shahejie Formation in Raoyang Sag

Lithology identification is the basis for sweet spot evaluation, prediction, and precise exploratory deployment and has important guiding significance for areas with low exploration degrees. The lithology of the shale strata, which are composed of fine-grained sediments, is complex and varies regularly in the vertical direction. Identifying complex lithology is a typical nonlinear classification problem, and intelligent algorithms can effectively solve this problem, but different algorithms have advantages and disadvantages. Compared were the three typical algorithms of Fisher discriminant analysis, BP neural network, and classification and regression decision tree (C&RT) on the identification of seven lithologies of shale strata in the lower 1st member of the Shahejie Formation (Es1L) of Raoyang sag. Fisher discriminant analysis method is linear discriminant, the recognition effect is poor, the accuracy is 52.4%; the accuracy of the BP neural network to identify lithology is 82.3%, but it belongs to the black box and can not be visualized; C&RT can accurately identify the complex lithology of Es1L, the accuracy of this method is 85.7%, and it can effectively identify the interlayer and thin interlayer in shale strata

Investigation of mechanical properties of bedded shale by nanoindentation tests: A case study on Lower Silurian Longmaxi Formation of Youyang area in southeast Chongqing, China

The mechanical properties such as Young's modulus, hardness and fracture toughness of Lower Silurian Longmaxi shale samples from Youyang area in southeast Chongqing, China were investigated using dot matrix nanoindentation measurements. With the help of field emission scanning electron microscope (FESEM) and energy dispersive X-ray fluorescence spectroscopy (EDS), the indentation morphology and mineral composition in indentation area were quantitatively analyzed. According to mechanical strength classification, a micromechanical model with three components was introduced and the Mori-Tanaka model was used to upscale mechanical parameters from nano-scale to centimeter-size scale, which were further compared with uniaxial compression results. The experimental results show that there is a positive linear correlation between Young's modulus and hardness and between the Young's modulus and the fracture toughness under nano-scale; the Young's modulus, hardness and fracture toughness perpendicular to the bedding are slightly lower than those parallel with the bedding. According to data statistics, the mechanical properties at the nano-scale follow Weibull distribution feature and the dispersion degree of hardness results is the highest, which is mainly due to shale anisotropy and nanoindentation projection uncertainty. Comparing the results from nanoindentation test, with those from upscaling model and uniaxial compression test shows that the mechanical parameters at the nano-scale are higher than those from upscaling model and uniaxial compression test, which proves mechanical parameters at different scales have differences. It's because the larger the core, the more pores and internal weakness it contains, the less accurate the interpreted results of mechanical parameters will be. Key words: nanoindentation, rock mechanics, Longmaxi Formation shale, Weibull distribution, Mori-Tanaka mode

Lower limits and grading evaluation criteria of tight oil source rocks of southern Songliao Basin, NE China

Taking the southern Songliao Basin as the target area, the hydrocarbon expulsion volume from source rocks has been quantitatively evaluated in this paper, based on the material balance method. Employing the “Overpressure” module of PetroMod software, the overpressure history of the source rocks was evaluated. According to the relationships between hydrocarbon expulsion rate, residual organic carbon content and overpressure within the source rocks, the lower limits of expulsion from tight oil source rocks were determined: a hydrocarbon expulsion amount of 2 mg/g, residual hydrocarbon content of 0.8%, and overpressure of 1 MPa. The source rocks with hydrocarbon expulsion amounts > 8 mg/g, a residual organic carbon content > 2.0%, and overpressure > 7 MPa were defined as excellent source rocks. As a result, tight oil source rocks can be divided into three types, excellent source rocks (type I), inefficient source rocks (type II) and non-productive source rocks (type III). The actual application in the southern Songliao Basin shows that the excellent source rocks have an obvious control on the planar and vertical distribution of tight oil discoveries, areas with excellent source rocks and nearby formations are favorable for the accumulation of tight oil. Key words: tight oil, source rocks, grading evaluation, hydrocarbon expulsion, overpressure, southern Songliao Basi

Centrosomal protein 120 promotes centrosome amplification and gastric cancer progression via USP54-mediated deubiquitination of PLK4

Summary: Centrosomal protein 120 (CEP120) is a 120 kDa centrosome protein that plays an important role in centrosome replication. Overexpression of CEP120 can lead to centrosome duplicate abnormality, which is closely associated with tumorigenesis and development. However, there are no reports on the relationship between CEP120 and tumors. In our study, overexpression of CEP120 promoted centrosome amplification in gastric cancer (GC), and the role of CEP120 in promoting GC progression was demonstrated in vitro and in vivo. We demonstrated that CEP120 promotes centrosome amplification and GC progression by promoting the expression and centrosome aggregation of the deubiquitinating enzyme USP54, maintaining the stability of PLK4 and reducing its ubiquitination degradation. In conclusion, the CEP120-USP54-PLK4 axis may play an important role in promoting centrosome amplification and GC progression, thus providing a potential therapeutic target for GC