Geochemical record of rapid climate change and chemical weathering in a semi-arid area, northeastern Tibetan Plateau

Wenxiang Zhang,Hucai Zhang,Jie Niu,Guoliang Lei,Fengqin Chang 한국지질과학협의회 2020 Geosciences Journal Vol.24 No.6

Lacustrine deposits can provide insight into chemical weathering and climate change. Based on the analysis of the element concentrations and parameters of the acid-leaching residual fractions (AR) in the lacustrine deposits of the Qaidam Basin (QB), chemical weathering and paleoclimate changes in the northeastern Tibetan Plateau (NETP) have been studied. The results show that the characteristics of trace element concentrations exhibit two kinds of patterns by normalized element arbitrary units (a.u.). The rare earth element (REE) distribution patterns are moderately rich in light rare earth elements (LREEs) with slightly right-tilting and negative Eu anomalies. Triangular plots of the REEs and (La/Yb)n-ΣREE suggest that the sediments have a similar source. The geochemical records of climate proxies indicated warm-wet climate stages during 45.1–31.6 cal. ka BP., further proving that a megalake stage existed in the semi-arid area in marine isotope stage (MIS) 3. Strong evaporation resulted in a high paleolake level history in the northeastern Tibetan Plateau after the late period of MIS 3. Meanwhile, the geochemical records of the Qaidam Basin are synchronous with the global records.

Detection of LSB Matching Revisited Using Pixel Difference Feature

( Wenxiang Li ),( Tao Zhang ),( Zhenhao Zhu ),( Yan Zhang ),( Xin Ping ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.10

This paper presents a detection method for least significant bit matching revisited (LSBMR) steganography. Previous research shows that the adjacent pixels of natural images are highly correlated and the value 0 appears most frequently in pixel difference. Considering that the message embedding process of LSBMR steganography has a weighted-smoothing effect on the distribution of pixel difference, the frequency of the occurrence of value 0 in pixel difference changes most significantly whereas other values approximately remain unchanged during message embedding. By analyzing the effect of LSBMR steganography on pixel difference distribution, an equation is deduced to estimate the frequency of difference value 0 using the frequencies of difference values 1 and 2. The sum of the ratio of the estimated value to the actual value as well as the ratio of the frequency of difference value 1 to difference value 0 is used as the steganalytic detector. Experimental results show that the proposed method can effectively detect LSBMR steganography and can outperform previous proposed methods.

Vapor phase condensation of methyl acetate with formaldehyde to preparing methyl acrylate over cesium supported SBA-15 catalyst

Jianbiao Yan,Chunlei Zhang,Chunli Ning,Yong Tang,Yi Zhang,Lili Chen,Shuang Gao,Zhenlu Wang,Wenxiang Zhang 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.25 No.-

A cesium ion-containing catalyst, on an SBA-15 mesoporous molecular support, was prepared by the impregnation method and applied to the aldol condensation of methyl acetate with formaldehyde. The catalyst showed high catalytic activity in the condensation reaction. XRD characterization indicated that the cesium nitrate below 5 wt% loading was highly dispersed on the SBA-15 support. FT-IR and XPS results confirmed that a Si–O–Cs species was formed on the surface of the catalyst. Pyridine-IR verified that an L-acid site existed on the surface. The NH3-TPD and CO2-TPD results indicated that weak Lewis acid–base pairs were loaded on the surface, and these weak acid–base active sites might favor the aldol condensation reaction. The 5Cs/SBA-15 catalyst demonstrated the highest (48.4%) conversion of methyl acetate reported and 95.0% selectivity for methyl acrylate. The deactivated catalyst was completely regenerated by calcination. The catalyst was regenerated nine times with a total operation time of more than 60 h, and the initial conversion of methyl acetate and the selectivity for methyl acrylate did not change. The high catalytic activity was mainly due to the suitable strength of weak acid–base properties, which were rooted in the Si–O–Cs species on the surface of the support.

Vapor-phase selective hydrogenation of maleic anhydride to succinic anhydride over Ni/TiO2 catalysts

Weitao Huo,Chunlei Zhang,Hongjing Yuan,Mingjun Jia,Chunli Ning,Yong Tang,Yi Zhang,Jiahuan Luo,Zhenlu Wang,Wenxiang Zhang 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.6

A series of supported Ni/TiO2 catalysts were prepared by incipient wetness impregnation method underdifferent calcination temperatures, and the as-prepared catalysts were characterized by X-ray diffraction(XRD), hydrogen temperature-programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy(XPS). The catalytic properties of these Ni/TiO2 catalysts were investigated in the vapor phasehydrogenation of maleic anhydride (MA) to succinic anhydride (SA). The results showed that thecatalytic activity and the selectivity of the Ni/TiO2 catalysts were strongly affected by the calcinationtemperature. The catalyst calcined at 1023 K showed a relatively higher SA selectivity of 96% at high MAconversion (96%) under the tested conditions (493 K and 0.2 MPa). The improvement of SA selectivitycould be mainly assigned to the presence of suitable metal–support interaction, which can play a role incatalytic property of active nickel species as electron promoter. Besides, the change of surface propertiesof TiO2 support with the increasing calcination temperatures, e.g., the decrease of Lewis acid sites, mightalso have some positive role in reducing the side-products like g-butyrolacetone (GBL).

Optimal pulse pattern with negative pulses and third harmonic mixed injection

Qinqing Zhang,Wenxiang Song,Tianqing Shui,Hongzhang Lyu 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.3

Adding negative pulses into a neutral-point clamped three-level inverter is an optimal pulse pattern (OPP) that can help restrain the neutral-point (NP) voltage fluctuation. However, this method can also cause the current harmonic distortion to be increased so that it becomes difficult to quantify the negative pulse width. Third harmonic injection can suppress neutralpoint potential fluctuation without increasing the switching frequency and it can also be automatically eliminated. Based on current harmonic minimization pulse width modulation (CHMPWM), a new optimal pulse pattern containing negative pulses and third harmonics is presented, which can inhibit NP voltage. Regarding the re-expression of the fundamental voltage expression, the optimal third harmonic content can be determined by constructing the analytical relationship between the fundamental voltage and the neutral-point current under the harmonic voltage. Combining this with a fitness function, sequence quadratic programming (SQP) is utilized to solve the new switching angles, which means that the CHMPWM is injected by negative pulses and third harmonics. Through simulations and experiments on a three-level inverter with a resistance-inductance load, it is verified that the proposed method can effectively suppress the voltage fluctuation at the neutral-point of the DC bus while taking the current harmonic distortion rate into account.

A Study of Job Failure Prediction on Supercomputers with Application Semantic Enhancement

Haotong Zhang,Gang Xian,Wenxiang Yang,Jie Yu 한국정보과학회 2022 Journal of Computing Science and Engineering Vol.16 No.4

The powerful computing capabilities of supercomputers play an important role in today’s scientific computing. A large number of high-performance computing jobs are submitted and executed concurrently in the system. Job failure can cause a waste of system resources and impact the efficiency of the system and user jobs. Job failure prediction can support fault-tolerant technology to alleviate this phenomenon in supercomputers. At present, the related work mainly predicts job failure by collecting the real-time performance attributes of jobs, but it is difficult to apply in the real environment because of the high cost of collecting job attributes. In addition to analyzing the time and resource attributes in the job logs, this study also explores the semantic information of jobs. We mine job application semantic information from job names and job paths, where job path is collected by additional monitoring of the job submitting process. A prediction method based on job application semantic enhancement is proposed, and the prediction results of the non-ensemble learning algorithm and the ensemble learning algorithm are compared under each evaluation indicator. This prediction method requires more miniature feature collection and computation overhead and is easy to apply. The experimental results showed that the prediction effect was promisingly improved with job application semantic enhancement, and the final evaluation indicator S_score was improved by 5%–6%, of which was 88.16% accuracy with 95.23% specificity and 88.24% sensitivity.

Apple residues derived porous carbon nanosheets synthesized with FeCl3 assisted hydrothermal carbonization for supercapacitors with high rate performance

Li Qiqi,Zhang Yingnan,Song Ya,Yang Huawei,Yang Lixia,Bai Liangjiu,Wei Donglei,Wang Wenxiang,Liang Ying,Chen Hou 한국탄소학회 2023 Carbon Letters Vol.33 No.2

Biomass carbon materials with high rate capacity have great potential to boost supercapacitors with cost effective, fast charging–discharging performance and high safety requirements, yet currently suffers from a lack of targeted preparation methods. Here we propose a facile FeCl3 assisted hydrothermal carbonization strategy to prepare ultra-high rate biomass carbon from apple residues (ARs). In the preparation process, ARs were first hydrothermally carbonized into a porous precursor which embedded by Fe species, and then synchronously graphitized and activated to form biocarbon with a large special surface area (2159.3 m2 g−1) and high degree of graphitization. The material exhibited a considerable specific capacitance of 297.5 F g−1 at 0.5 A g−1 and outstanding capacitance retention of 85.7% at 10 A g−1 in 6 M KOH, and moreover, achieved an energy density of 16.2 Wh kg−1 with the power density of 350.3 W kg−1. After 8000 cycles, an initial capacitance of 95.2% was maintained. Our findings provide a new idea for boosting the rate capacity of carbon-based electrode materials.

Commutability Assessment of Candidate External Quality Assessment Materials for Aminotransferase Activity Measurements Based on Different Approaches in China

Long Qichen,Qi Tianqi,Zhang Tianjiao,Wang Jing,Zeng Jie,Ying Yan,Meng Wang,Wei Huang,Haijian Zhao,Wenxiang Chen,Chuanbao Zhang 대한진단검사의학회 2021 Annals of Laboratory Medicine Vol.41 No.1

Background: Using commutable external quality assessment (EQA) materials is important for monitoring successful harmonization efforts. We assessed the commutability of four human serum pool (HSP) preparations to identify candidate EQA materials for alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity measurement. Methods: One set each of 85 clinical samples (CSs) was collected for ALT and AST activity measurement. The 15 candidate EQA materials included four types of HSP preparations (A to D): materials A, C, and D contained human original recombinant (HOR) aminotransferases; materials B was mixed leftover samples. The CSs and 15 candidate EQA materials were analyzed using seven routine assays, and the ln-transformed results were analyzed in 21 assay pairs. Commutability was assessed using Deming regression, with a 95% prediction interval (CLSI approach) and the difference in bias with an error component model (International Federation of Clinical Chemistry and Laboratory Medicine [IFCC] approach). Results: For ALT, all materials were commutable for 14–21 assay pairs according to the CLSI and IFCC approaches. For AST, B01-03 showed commutability for 14-21 assay pairs, and C01-03 and D01-03 showed commutability for no less than 10 assay pairs according to the two approaches. A01-06 were commutable for 9-16 assay pairs according to the CLSI approach, but for 6-9 assay pairs according to the IFCC approach. Conclusions: Mixed leftover samples showed desirable commutability characteristics as candidate EQA materials for routine aminotransferase activity measurements. Human serum bases supplemented with HOR were commutable for most routine ALT activity measurements.

Variations in bacterial and fungal communities through soil depth profiles in a Betula albosinensis forest

Can Du,Zengchao Geng,Qiang Wang,Tongtong Zhang,Wenxiang He,Lin Hou,Yueling Wang 한국미생물학회 2017 The journal of microbiology Vol.55 No.9

Microbial communities in subsurface soil are specialized for their environment, which is distinct from that of the surface communities. However, little is known about the microbial communities (bacteria and fungi) that exist in the deeper soil horizons. Vertical changes in microbial alpha-diversity (Chao1 and Shannon indices) and community composition were investigated at four soil depths (0–10, 10–20, 20–40, and 40–60 cm) in a natural secondary forest of Betula albosinensis by high-throughput sequencing of the 16S and internal transcribed spacer rDNA regions. The numbers of operational taxonomic units (OTUs), and the Chao1 and Shannon indices decreased in the deeper soil layers. Each soil layer contained both mutual and specific OTUs. In the 40–60 cm soil layer, 175 and 235 specific bacterial and fungal OTUs were identified, respectively. Acidobacteria was the most dominant bacterial group in all four soil layers, but reached its maximum at 40–60 cm (62.88%). In particular, the 40–60 cm soil layer typically showed the highest abundance of the fungal genus Inocybe (47.46%). The Chao1 and Shannon indices were significantly correlated with the soil organic carbon content. Redundancy analysis indicated that the bacterial communities were closely correlated with soil organic carbon content (P = 0.001). Collectively, these results indicate that soil nutrients alter the microbial diversity and relative abundance and affect the microbial composition.