Fracture and Delamination Assessment of Prestressed Composite Concrete for Use with Pipe Jacking Method

Prestressed composite concrete pipe (PCCP) has been widely used in water-transmission line and has been proven with many advantages over pure concrete or steel pipes, such as high performance with relatively low cost for materials as well as simplified installation and construction process. Recent efforts have been made to enable the PCCP structure suitable for pipe jacking method so as to replace the conventional cut and cover method. In this way, the construction time, disturbance to nearby structures, and the cost can be greatly reduced. In this paper, we present the full-scale experimental and numerical studies of PCCP and the evaluation of fracture and delamination behaviour of the structure when it is used with pipe jacking construction method subjected to various jacking forces and ground conditions

The relationship between permeability and pore structure of coal slime filter cake based on fractal characteristics

Establishing the correlation between the complex microscopic pore structure characteristics of the filter cake and the macroscopic seepage behavior is an important basis for solving the difficulty of coal slime dewatering. In order to characterize the pore structure of the filter cake accurately, four main minerals in the coal slime such as clean coal, quartz, kaolinite and montmorillonite were used as the research objects. The samples were scanned and imaged by CT, a 3D digital filter cake was constructed and a pore network model was extracted. Finally, the 3D display and quantitative characterization of the pore structure of the filter cake was realized. The classical K-C equation and the double fractal permeability model were deeply compared and analyzed in the filter cake permeability calculation. Based on fractal theory, Hagen-Poiseulle law and Darcy's law, combined with low-field nuclear magnetic resonance technology, bound water saturation and pore shape fractal dimension were introduced, and the existing fractal permeability model was revised to establish a filter cake microstructure. The permeability prediction model, the results show that the mineral composition in the slime filter cake is very complex, the filter cake formed by each mineral has obvious characteristic differences, the dewatering effect of clean coal and quartz is the best, and the pore size distribution of the clean coal filter cake is in the order of large pores. Mainly, but there are a certain amount of isolated pores inside, the connectivity is average, the pore tortuosity is the lowest, the porosity of the quartz filter cake is the largest, the connectivity is the highest, but the tortuosity is large. The filter cake formed by montmorillonite and kaolinite, the number of their pores is very small, and most of them are composed of pores below 10 μm, with large tortuosity, poor connectivity, which cause the poor dewatering performance. The filter cake of coal slime is mainly distributed in narrow strips, and the pore size is small. The overall porosity is low, the connectivity is poor, the tortuosity is high, and dehydration is difficult. The filter cake micro-permeability prediction model has high prediction accuracy for the permeability of quartz and clean coal filter cake, with relative errors of 1.34% and 1.15%, respectively. For the complex composition of slime filter cake and kaolinite filter cake, its permeability prediction error can be controlled within 5%, and the calculation error of the permeability of the montmorillonite filter cake can also be reduced to 13.42%

Interdecadal variation of precipitation over Yunnan, China in summer and its possible causes

In recent decades, severe drought conditions have become increasingly frequent in Yunnan, Southwest China. The extreme drought events cause huge losses to agricultural economy, ecological security and human health. To uncover the reasons behind the worsening drought conditions, this study investigates the interdecadal variability (IDV) of summer precipitation in Yunnan during 1961–2019 and its association with the Indo-Pacific Sea surface temperature (SST) configuration based on gauge observation and reanalysis data. The dominant mode of summer precipitation IDV in Yunnan shows a uniform pattern characterizing the alternations of flood and drought. Specifically, a relatively wet period persists from the early 1990s to the early 2000s, followed by a relatively dry period from the early 2000s to the late 2010s. The IDV of precipitation is consistent with the IDV of the column-integrated water vapor flux divergence, where the wind anomalies play a major role in modulating the moisture supply. The main SST forcings of the IDV of precipitation include the sea surface temperature anomalies (SSTAs) over the Bay of Bengal (BOB), the Western Pacific Warm Pool (WPWP), and the western North Pacific (WNP). The negative SSTAs over the BOB and the WPWP trigger a Gill-Matsuno-type response that enhances the cyclonic curvature over Yunnan. The SSTAs over the WNP show a tripole pattern that weakens the WNP subtropical high and further enhances the cyclonic anomaly over Yunnan. The above SST configuration also favors moisture transport to Yunnan. Numerical experiments verify the key physical processes

Competition and cooperation of sulfate reducing bacteria and five other bacteria during oil production

Embargo until March 18, 2023Effective control of sulfate-reducing bacteria (SRB) will help reduce economic losses and prevent threats to human health during the oil production. In this study, the responses of SRB to environmental variables and some functional microorganisms (including denitrifying bacteria (DNB), methanogenic bacteria (MGB), saprophytic bacteria (SPB), zymophyte bacteria (ZPB), and iron bacteria (IB)), during oil production processes were investigated to improve our understanding of how to control SRB abundance. Correlation analyses demonstrated that nitrate and redox potential exihibited significant inhibitory effects on the growth and reproduction of SRB and redox potential (0.175, P < 0.01) had a stronger effect than NO3− (0.0817, P < 0.05). PCA analysis demonstrated a clear division of the bacteria into two clusters, cluster 1 consisted of SRB, SPB and IB, while cluster 2 consisted of DNB, MGB and ZPB. Cooperation was apparent for SRB with SPB and IB, while competition was apparent for SRB with DNB, MGB and ZPB. These results provide new insights to possible solutions to control SRB growth in the oilfield environment, including addition of nitrate and nitrite, to promote the growth of denitrifying bacteria, thereby suppressing the growth of SRB.acceptedVersio

In Situ OH Generation From O2- and H2O2 Plays a Critical Role in Plasma Induced Cell Death

Reactive oxygen and nitrogen species produced by cold atmospheric plasma (CAP) are considered to be the most important species for biomedical applications, including cancer treatment. However, it is not known which species exert the greatest biological effects, and the nature of their interactions with tumor cells remains ill-defined. These questions were addressed in the present study by exposing human mesenchymal stromal and LP-1 cells to reactive oxygen and nitrogen species produced by CAP and evaluating cell viability. Superoxide anion (O2-) and hydrogen peroxide (H2O2) were the two major species present in plasma, but their respective concentrations were not sufficient to cause cell death when used in isolation; however, in the presence of iron, both species enhanced the cell death-inducing effects of plasma. We propose that iron containing proteins in cells catalyze O2- and H2O2 into the highly reactive OH radical that can induce cell death. The results demonstrate how reactive species are transferred to liquid and converted into the OH radical to mediate cytotoxicity and provide mechanistic insight into the molecular mechanisms underlying tumor cell death by plasma treatment

Research of the Channel Estimation in Wireless Communication Systems

Wireless communication technology has been developed rapidly after entering the 21st century. Data transfer rate increased significantly as well as the bandwidth became wider and wider from 2G to 4G in wireless communication systems. Channel estimation is an import part of any communication systems; its accuracy determines the quality of the whole communication. Channel estimation methods of typical wireless communication systems such as UWB, 2G and 3G have been researched

Genome-wide analysis and identification of stress-responsive genes of the CCCH zinc finger family in Capsicum annuum L.

The CCCH zinc finger gene family encodes a class of proteins that can bind to both DNA and RNA, and an increasing number of studies have demonstrated that the CCCH gene family plays a key role in growth and development and responses to environmental stress. Here, we identified 57 CCCH genes in the pepper (Capsicum annuum L.) genome and explored the evolution and function of the CCCH gene family in C. annuum. Substantial variation was observed in the structure of these CCCH genes, and the number of exons ranged from one to fourteen. Analysis of gene duplication events revealed that segmental duplication was the main driver of gene expansion in the CCCH gene family in pepper. We found that the expression of CCCH genes was significantly up-regulated during the response to biotic and abiotic stress, especially cold and heat stress, indicating that CCCH genes play key roles in stress responses. Our results provide new information on CCCH genes in pepper and will aid future studies of the evolution, inheritance, and function of CCCH zinc finger genes in pepper