Prediction of Field Sand Liquefaction Caused by Earthquake by Optimum Seeking Method

There are many uncertain factors influencing the field sand liquefaction induced by earthquake, therefore, the predictions of available methods are usually unsatisfactory. In this paper, a new way is developed, i.e., according to the available field sand liquefaction data, the influencing factors are optimized by optimum seeking method, then the prediction is made on the optimized results. By this method, 20 field cases are predicted and the correct rate is 95%. It proves that the suggested method is effective and feasible

The Role of Mineral Composition on the Frictional and Stability Properties of Powdered Reservoir Rocks

The growing hazard of induced seismicity driven by the boom in unconventional resources exploitation is strongly linked to fault activation. We perform laboratory measurements on simulated fault gouges comprising powdered reservoir rocks from major oil and gas production sites in China, to probe the control of mineral composition on fault friction and stability responses during reservoir stimulation. Double direct shear experiments were conducted on gouges with phyllosilicate content ranging from 0 to 30wt.% and grain sizes <150m, at constant normal stresses of 10-40MPa and conditions of room temperature and water saturation. The velocity step and slide-hold-slide sequences were employed to evaluate frictional stability and static healing, respectively. Results indicate that the mineralogy of the gouges exhibit a strong control on the frictional strength, stability, and healing. Phyllosilicate-rich samples show lower frictional strength and higher values of (a-b), promoting stable sliding. For the gouges studied, the frictional strength decreases monotonically with increasing phyllosilicate content, and a transition from velocity weakening to velocity strengthening behavior is evident at 15wt.% phyllosilicates. Intermediate healing rates are common in gouges with higher content of phyllosilicates, with high healing rates predominantly in phyllosilicate-poor gouges. As an indispensable component in reservoir rocks, the carbonates are shown to affect both the frictional stability and healing response. These findings can have important implications for understanding the effects of mineralogy on fault behavior and induced seismic potential in geoengineering activities, particularly in reservoirs in China.National Natural Science Foundation of China [41672268, 41772286]; U.S. Department of Energy (DOE) [DE-FE0023354]6 month embargo; published online: 5 February 2019This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Metabolomic and transcriptomic analyses of rice plant interaction with invasive weed Leptochloa chinensis

IntroductionLeptochloa chinensis is an annual weed in paddy fields, which can engage in competition with rice, leading to a severe yield reduction. However, theunderlying mechanism governing this interaction remain unknown.MethodsIn this study, we investigated the mutual inhibition between rice and the weed undermono-culture and co-culture conditions. We found that the root exudates of both species played essential roles in mediating the mutual inhibition. Further metabolomic analysis identified a significant number of differential metabolites. These metabolites were predominantly enriched in the phenylpropanoid and flavonoid biosynthesis pathways in weed and rice. Transcriptomic analysis revealed that the differentially expressed genes responding to the interaction were also enriched in these pathways.ResultsPhenylpropanoid and flavonoid biosynthesis pathways are associated with allelopathy, indicating their pivotal role in the response of rice-weed mutual inhibition.DiscussionOur findings shed light on the conserved molecular responses of rice and L. chinensis during theirinteraction, provide evidence to dissect the mechanisms underlying the allelopathic interaction and offer potential strategies for weed management in rice paddies

Photocatalytic Degradation of Profenofos and Triazophos Residues in the Chinese Cabbage, \u3cem\u3eBrassica chinensis\u3c/em\u3e, Using Ce-Doped TiO\u3csub\u3e2\u3c/sub\u3e

Pesticides have revolutionized the modern day of agriculture and substantially reduced crop losses. Synthetic pesticides pose a potential risk to the ecosystem and to the non-target organisms due to their persistency and bioaccumulation in the environment. In recent years, a light-mediated advanced oxidation processes (AOPs) has been adopted to resolve pesticide residue issues in the field. Among the current available semiconductors, titanium dioxide (TiO2) is one of the most promising photocatalysts. In this study, we investigated the photocatalytic degradation of profenofos and triazophos residues in Chinese cabbage, Brassica chinensis, using a Cerium-doped nano semiconductor TiO2 (TiO2/Ce) under the field conditions. The results showed that the degradation efficiency of these organophosphate pesticides in B. chinensis was significantly enhanced in the presence of TiO2/Ce. Specifically, the reactive oxygen species (ROS) contents were significantly increased in B. chinensis with TiO2/Ce treatment, accelerating the degradation of profenofos and triazophos. Ultra-performance liquid chromatography–mass spectroscopy (UPLC-MS) analysis detected 4-bromo-2-chlorophenol and 1-phenyl-3-hydroxy-1,2,4-triazole, the major photodegradation byproducts of profenofos and triazophos, respectively. To better understand the relationship between photodegradation and the molecular structure of these organophosphate pesticides, we investigated the spatial configuration, the bond length and Mulliken atomic charge using quantum chemistry. Ab initio analysis suggests that the bonds connected by P atom of profenofos/triazophos are the initiation cleavage site for photocatalytic degradation in B. chinensis

Reference Gene Selection for qRT-PCR Analysis in the Sweetpotato Whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae)

BACKGROUND: Accurate evaluation of gene expression requires normalization relative to the expression of reliable reference genes. Expression levels of classical reference genes can differ, however, across experimental conditions. Although quantitative real-time PCR (qRT-PCR) has been used extensively to decipher gene function in the sweetpotato whitefly Bemisia tabaci, a world-wide pest in many agricultural systems, the stability of its reference genes has rarely been validated. RESULTS: In this study, 15 candidate reference genes from B. tabaci were evaluated using two Excel-based algorithms geNorm and Normfinder under a diverse set of biotic and abiotic conditions. At least two reference genes were selected to normalize gene expressions in B. tabaci under experimental conditions. Specifically, for biotic conditions including host plant, acquisition of a plant virus, developmental stage, tissue (body region of the adult), and whitefly biotype, ribosomal protein L29 was the most stable reference gene. In contrast, the expression of elongation factor 1 alpha, peptidylprolyl isomerase A, NADH dehydrogenase, succinate dehydrogenase complex subunit A and heat shock protein 40 were consistently stable across various abiotic conditions including photoperiod, temperature, and insecticide susceptibility. CONCLUSION: Our finding is the first step toward establishing a standardized quantitative real-time PCR procedure following the MIQE (Minimum Information for publication of Quantitative real time PCR Experiments) guideline in an agriculturally important insect pest, and provides a solid foundation for future RNA interference based functional study in B. tabaci

Determination and applications of rock quality designation (RQD)

Characterization of rock masses and evaluation of their mechanical properties are important and challenging tasks in rock mechanics and rock engineering. Since in many cases rock quality designation (RQD) is the only rock mass classification index available, this paper outlines the key aspects on determination of RQD and evaluates the empirical methods based on RQD for determining the deformation modulus and unconfined compressive strength of rock masses. First, various methods for determining RQD are presented and the effects of different factors on determination of RQD are highlighted. Then, the empirical methods based on RQD for determining the deformation modulus and unconfined compressive strength of rock masses are briefly reviewed. Finally, the empirical methods based on RQD are used to determine the deformation modulus and unconfined compressive strength of rock masses at five different sites including 13 cases, and the results are compared with those obtained by other empirical methods based on rock mass classification indices such as rock mass rating (RMR), Q-system (Q) and geological strength index (GSI). It is shown that the empirical methods based on RQD tend to give deformation modulus values close to the lower bound (conservative) and unconfined compressive strength values in the middle of the corresponding values from different empirical methods based on RMR, Q and GSI. The empirical methods based on RQD provide a convenient way for estimating the mechanical properties of rock masses but, whenever possible, they should be used together with other empirical methods based on RMR, Q and GSI. (C) 2016 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V.Open Access JournalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Evaluation of rock mass deformability using empirical methods – A review

Evaluation of rock mass deformability is an important but very challenging task in the analysis and design of underground structures in rock. Although various empirical (correlation) methods have been developed for determining the deformation modulus of rock masses, they come in many forms and are scattered in different sources. It is often difficult, time-consuming, or even impossible for a practitioner to find appropriate information to determine the deformation modulus of rock masses for a particular project. Therefore, this paper first provides a comprehensive review of the different empirical methods for determining the deformation modulus of rock masses. Then a comparative analysis and discussion is carried out on the accuracy and main issues of these methods. Since many of the empirical methods for determining the deformation modulus of rock masses need to use the deformation modulus of intact rock, the various empirical methods for estimating the deformation modulus of intact rock are also reviewed. In addition, this paper highlights the scale effect on rock mass deformability, the effect of confining stress on rock mass deformability, and the anisotropy of rock mass deformability. Overall this paper outlines the key aspects of rock mass deformability and provides the fundamental and essential information required for effective evaluation of rock mass deformability using the empirical methods. Keywords: Rock mass, Deformability, Empirical method, Scale effect, Stress effect, Anisotrop

Analysis and design of axially loaded drilled shafts socketed into rock

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1997.Includes bibliographical references (leaves 162-167).by Lianyang Zhang.M.S