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BACKGROUND The quantification of trace elements in geological samples depends largely on the analytical methods that require complex chemical pretreatment. High-energy polarized energy-dispersive X-ray fluorescence spectrometry (HE-P-EDXRF) has a considerable advantage for the determination of trace elements with large atomic numbers, due to its high-energy properties, which can effectively excite the Kα line of heavy elements. OBJECTIVES To establish a HE-P-EDXRF method for quantitative analysis of major and trace elements in geological samples. METHODS HE-P-EDXRF was used to establish an analysis method for major and trace elements in soil, rock and water system sediments. The selection of analysis lines, line overlap interference correction and matrix correction modes were discussed. Uncertainty was used to evaluate the method. RESULTS The Kα line was selected as the analysis line for trace elements with a larger atomic number due to less interference from the spectral line overlap, which is beneficial to obtaining the net peak intensity. Rare earth elements such as La, Ce and Nd can be accurately measured. Detection limits of the trace element Ba and rare earth elements such as La, Ce determined by EDXRF were greater than those determined by WDXRF, but lesser for light elements. For all the major and trace elements, the average of relative error of test training data was less than 15% except for Na2O, MgO, P and Sm. The average relative error of trace elements was between 2.40% and 16.3%. The accuracy of trace elements (except Cu and Yb) was significantly better than that of WDXRF. According to the evaluation method of the Europe Union, no significant difference existed between the trace elements results (except V and Th) and the recommended value of certified reference materials. CONCLUSIONS HE-P-EDXRF is a simple, fast and environmentally-friendly method that can simultaneously analyze multiple elements in geological samples. This method is suitable for quantification of the trace and rare earth elements in rock, soil and sediment, which overcomes the dependence of quantitative analysis of rare earth and trace elements in geological samples on the need for methods requiring complex chemical pretreatment.

BACKGROUND The contents of silver, tin, boron, molybdenum, and lead in geological samples are extremely important for studying the metallogenic regularity and for geochemical prospecting. Current analytical methods rarely determine silver, tin, boron, molybdenum, and lead simultaneously. OBJECTIVES To establish a method to simultaneously determine silver, tin, boron, molybdenum and lead in geological samples. METHODS To eliminate the matrix interference, first-class standard materials (rock, soil and water sediments) were used for linear fitting of the synthetic silicate standard materials curve. By setting analytical line conversion values, different analytical line can be used for samples with different contents. RESULTS The detection limits of silver, tin, boron, molybdenum, and lead were 0.0077μg/g, 0.19μg/g, 0.68μg/g, 0.058μg/g, 0.49μg/g, respectively. The precisions of the method were 3.23%-9.39%. The measured value of national first class standard materials including soil, water sediments and rock by this method was in accordance with standard values, with an absolute value of △logC < 0.10. The qualified rates of actual sample were 92%-98%, and the qualified rate of the inspection sample was 100%. CONCLUSIONS This method is easy to apply and can be used to analyze samples rapidly. It can also be used to avoid contamination during sample dilution. Compared with traditional atomic emission spectrometry that uses a single analytical spectrum line, this method can be used to obtain a value which is closer to the standard value of national standard materials. The detection limit of this method is much lower than the standard value of the specification of testing quality management for geological laboratories.

Commutation failure is an important factor on safe and stable operation of the receiving-end power grid for high voltage direct current (HVDC) project. A commutation failure event in Jinsu DC transmission project caused by a complex AC failure was taken as background, process of fault and action sequences of protection was introduced, and the reason of the commutation failure and protection action was analysed from principle. Real-time digital simulation (RTDS) was connected to the true-type device of ultra-high voltage direct current (UHVDC) control and protection to form a closed-loop simulation platform. The commutation failure event was inversed, and the simulation result was compared with the actual recorded wave. The results show that abnormal AC voltage leads to the commutation failure.

Embedding its own branches in private enterprises is the governance strategy that the Communist Party of China (CPC) controls the grassroots society. This study proposes a framework by incorporating the socioemotional wealth theory into neo-institutionalism to explain how are family businesses involved in the organizational network of the CPC. Findings reveal that there is an organizational isomorphism that the coverage of party organizations expanded from non-family businesses to family businesses. Furthermore, family businesses are not likely to establish party organizations when coercive pressures are low. However, this resistance strategy sharply disappears when coercive pressures are high, and joining state-backed industry associations and mimicking others' practice both are also positive factors motivating family businesses to establish party organizations, which means that the coercive, normative and mimetic mechanisms jointly shape the organizational isomorphism. This study contributes to the literature of neo-institutionalism and sheds new light on the state-society relationship in China. [ABSTRACT FROM AUTHOR]

In order to reduce the impact of bipolar blocking on grid stability of restoration and restart process, a unipolar blocking caused by fires in Jin Su ultra-high voltage direct current (UHVDC) as background was taken, using real time digital simulator (RTDS) built a model of DC and AC power grid on both sides, forming closed-loop simulation platform together with UHVDC control and protection true-type device. Based on the simulation platform, unipolar blocking fault caused by wildfire was inversed, and line protection action principle and restarting logic are studied. Protection action and restart during unipolar blocking were studied. Based on simulation platform on RTDS of UHVDC control and protection, the unipolar blocking event was inversed and the simulation result was compared with the actual recorded wave. The results show: operation of the protection device does reflect the line fault. [ABSTRACT FROM AUTHOR]

We studied plugging of crossflow behind oil-well casing with nitrogen foam under reservoir conditions. We have experimentally demonstrated the feasibility of the gas-liquid injection mode and suggest injecting the foam into the water-producing layer. If the nitrogen is injected first, the pressure in the oil-producing layer exceeds the pressure in the water-producing layer. The nitrogen can displace some of the water from the pores, reducing dilution of the foaming agent. As the experimental results show, the plugging strength of the foam injected into the water-producing layer is reduced as the plugging time increases. When the plugging time is longer than 200 hours, the pressure gradient can exceed 1.22 MPa/m and as a result, the nitrogen foam continues to plug the water. However, the lifetime of the nitrogen foam in the oil-producing layer is limited. The experimental study of plugging crossflow behind the casing with nitrogen foam and the field tests conducted confirmed the feasibility of plugging crossflow behind the casing with nitrogen foam. [ABSTRACT FROM AUTHOR]

This study explored the effects of mammalian target of rapamycin (mTOR) on the increased risk of developing Alzheimer's disease (AD) in rats with type 2 diabetes mellitus (T2DM). Male Sprague-Dawley rats were randomly divided into four groups: control, T2DM, AD and T2DM+AD. Changes in the learning and memory abilities of the rats were observed using the Morris water maze. mTOR activity and tau protein hyperphosphorylation in the hippocampus were analyzed by immunohistochemical staining and RT-PCR. The learning and memory abilities of the experimental rats were weakened compared with those of the control group. The T2DM+AD group revealed significant changes over the T2DM and AD groups. Compared with the control, T2DM and AD groups, the mTOR protein and mRNA levels, hyperphosphorylation of tau protein and total tau protein mRNA levels were significantly increased in the T2DM+AD group. T2DM may excessively activate mTOR in the hippocampal tissue by impairing insulin signaling, thereby increasing the extent of tau hyperphosphorylation and promoting the occurrence of AD.