Influence of polypropylene fiber reinforcement on tensile behavior and failure mode of tailings cemented paste backfill

Tailings were used to prepare cemented paste backfill (CPB) reinforced with polypropylene (PP) fiber, and fiber content and fiber length were 0-20 % and 3-12 mm, respectively. The Brazilian indirect tensile strength tests, macrostructural and microstructural (SEM) failure mode analyses and nuclear magnetic resonance (NMR) tests were performed. The results demonstrate that PP fiber with high tensile strength can substantially enhance the tensile strength and ductility of CPB specimens. The fiber-reinforced CPB exhibits superior performance during the pre-peak and post-peak stages and can retain its residual strength after being broken. The fiber-reinforced CPB provided a higher secant Young’s modulus and strain at peak stress than that of the unreinforced CPB. From the failure mode analysis, fiber was used to bridge the CPB microelements and combine these effectively with calcium silicate hydrate gelling. The governing failure mode of fiber is pulled out or pull off, through which fiber absorbs the tensile stress and energy. However, fiber is also believed to have confusion distribution in CPB because fiber cannot reach their full strain capacity, especially at the later curing stage. And the weak structural layers in the CPB can also be formed, and the higher tensile strength is not achieved with the additional fiber content or longer fiber length. The optimal fiber content in this study is recommended to be 0.15 %, and it’s better to choose 6 or 9 mm fiber. Moreover, fiber can reduce the original porosity by 10.72 %, but only has a slight influence on the pore size. The decrease in porosity helps increase the tensile strength of the fiber-reinforced CPB

Delayed impact of natural climate solutions

Acknowledgement: This work was supported by the National Basic Research Program of China (2016YFA0602701), the National Natural Science Foundation of China (41975113; 91937302), and the Guangdong Provincial Department of Science and Technology (2019ZT08G090). We appreciate the support from the China Association for Science and Technology Working Group for UN Environment Consultation. The authors declare no conflict of interests.Peer reviewedPostprin

Association of Short Tandem Repeat Polymorphism in the Promoter of Prostate Cancer Antigen 3 Gene with the Risk of Prostate Cancer

BACKGROUND: PCA3 (prostate cancer antigen 3) gene is one of the most prostate cancer-specific genes at present. Consequently, the prostate-specific expression and the sharp up-regulation of PCA3 mRNA in prostate cancer suggest a unique transcriptional regulation, which possibly can be attributed to promoter polymorphism. In our study, we evaluated whether there is polymorphism in PCA3 promoter region and also assess the association of the polymorphism with prostate cancer. METHODOLOGY/PRINCIPAL FINDINGS: We designed a specific primer set to screen the promoter of PCA3 gene by polymerase chain reaction (PCR)-based cloning and sequencing with the DNA extracted from peripheral blood samples of prostate cancer (PCa) cases (n = 186) and healthy control cases (n = 135). Genotype-specific risks were estimated as odds ratios (ORs) with associated 95% confidence intervals (CIs) by chi-square test. Possible deviation of the genotype frequencies from controls and PCa cases expected under Hardy-Weinberg equilibrium was assessed by the chi-square test. Short tandem repeat polymorphism of TAAA was found in the promoter region of PCA3 gene, five polymorphisms and eight genotypes were identified. The eight genotypes were divided into three groups: ≤10TAAA, 11TAAA, ≥12TAAA. The group 11TAAA and ≥12TAAA were associated with higher relative risk for prostate cancer than group ≤10TAAA (OR = 1.76, 95%CI = 1.07-2.89[for group 11TAAA]; OR = 5.28, 95%CI = 1.76-15.89[for group ≥12TAAA]). CONCLUSIONS/SIGNIFICANCE: The presence of the (TAAA)n short tandem repeat polymorphisms in the PCA3 promoter region may be a risk factor for prostate cancer in the Chinese population

A microbial functional group-based CH4 model integrated into a terrestrial ecosystem model : model structure, site-level evaluation and sensitivity analysis

Wetlands are one of the most important terrestrial ecosystems for land-atmosphere CH4 exchange. A new process-based, biophysical model to quantify CH4 emissions from natural wetlands was developed and integrated into a terrestrial ecosystem model (Integrated Biosphere Simulator). The new model represents a multisubstance system (CH4, O-2, CO2, and H-2) and describes CH4 production, oxidation, and three transport processes (diffusion, plant-mediated transport, and ebullition). The new model uses several critical microbial mechanisms to represent the interaction of anaerobic fermenters and homoacetogens, hydrogenotrophic, and acetoclastic methanogens, and methanotrophs in CH4 production and oxidation. We applied the model to 24 different wetlands globally to compare the simulated CH4 emissions to observations and conducted a sensitivity analysis. The results indicated that (1) for most sites, the model was able to capture the magnitude and variation of observed CH4 emissions under varying environmental conditions; (2) the parameters that regulate dissolved organic carbon and acetate production, and acetoclastic methanogenesis had the significant impact on simulated CH4 emissions; (3) the representation of the process components of CH4 cycling showed that CH4 oxidation was about half or more of CH4 production, and plant-mediated transport was the dominant pathway at most sites; and (4) the seasonality of simulated CH4 emissions can be controlled by soil temperature, water table position, or combinations thereof.Peer reviewe

A Semi-Empirical Inversion Model for Assessing Surface Soil Moisture using AMSR-E Brightness Temperatures

In 2004-2005, 2007 and 2009, three major drought disasters occurred in Guangdong Province of southern China, which caused serious economic losses. Hence, it has recently become an important research subject in China to monitor surface soil moisture (SSM) and the drought disaster quickly and accurately. SSM is an effective indicator for characterizing the degree of drought. First, using the brightness temperatures (T[subscript b]) of the Advanced Microwave Scanning Radiometer on the EOS Aqua Satellite (AMSR-E), a modified surface roughness index was developed to map the land surface roughness. Then by combining microwave polarization difference indices (MPDI)-based vegetation cover classification and the modified surface roughness index, a simple semi-empirical model of SSM was derived from the passive microwave radiative transfer equation using AMSR-E C-band T[subscript b] and observed surface soil temperature (T[subscript s]). The model was inverted to calculate SSM. The results show the ability to discriminate over a broad range of SSM (7%~73%) with an accuracy of 2.11% in bare ground and flat areas (R² =0.87), 2.89% in sparse vegetation and flat surface areas (R²=0.85), about 6%~9% in dense vegetation areas and rough surface areas (0.80≤R²≤0.83). The simulation results were also validated using in-situ SSM data (R²=0.87, RMSE=6.36%). Time series mapping of SSM from AMSR-E imageries further demonstrated that the presented method was effective to detect the initiation, duration and recovery of the drought events.This is the author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/journal-of-hydrology/.Keywords: Drought disaster, Brightness temperature (T[subscript b]), South China, Semi-Empirical model, Surface soil moisture (SSM), AMSR-E, Passive microwave remote sensin

Climatic and biotic factors influencing regional declines and recovery of tropical forest biomass from the 2015/16 El Niño

International audienceThe 2015/16 El Niño brought severe drought and record-breaking temperatures in the tropics. Here, using satellite-based L-band microwave vegetation optical depth, we mapped changes of above-ground biomass (AGB) during the drought and in subsequent years up to 2019. Over more than 60% of drought-affected intact forests, AGB reduced during the drought, except in the wettest part of the central Amazon, where it declined 1 y later. By the end of 2019, only 40% of AGB reduced intact forests had fully recovered to the predrought level. Using random-forest models, we found that the magnitude of AGB losses during the drought was mainly associated with regionally distinct patterns of soil water deficits and soil clay content. For the AGB recovery, we found strong influences of AGB losses during the drought and of γ . γ is a parameter related to canopy structure and is defined as the ratio of two relative height (RH) metrics of Geoscience Laser Altimeter System (GLAS) waveform data—RH25 (25% energy return height) and RH100 (100% energy return height; i.e., top canopy height). A high γ may reflect forests with a tall understory, thick and closed canopy, and/or without degradation. Such forests with a high γ ( γ ≥ 0.3) appear to have a stronger capacity to recover than low- γ ones. Our results highlight the importance of forest structure when predicting the consequences of future drought stress in the tropics

Research and Application of Scheduling Algorithm for Digital Television Multiplexer

The DTV program multiplexer in system level needs to combine many programs and some message into multi-program TS for transporting in the channel. Because DTV program contains audio and video signal, and the fluctuation of code rate is very large, data packet is easy to lose in the process of combining them into a data stream at a steady rate. Therefore, the research on dispatch algorithm about DTV multiplexer is of vital importance. This paper puts forward a two-level joint dispatching method with monopolizing and sharing buffers, which gets packets from monopolizing buffers respectively, and forms a buffer array supporting priority in sharing buffer, and then outputs at steady rate. Through verify this method has less data loss rate at equivalent serve intension