Safety assessment of high voltage substation earthing systems with synthetic geotextile membrane

High voltage substations built within areas prone to vegetation or with unfavourable subgrade conditions are paved with the addition of punched geotextiles and non-conductive synthetic fabrics underneath switchyard surfacing. The aim of this research is to identify the impact of synthetic textiles on earthing system performance through numerical analysis with the state-of-the-art software package. The new layer interferes with the earthing grids performance with a different behaviour depending on the installation above or underneath the layer with considerable impact taking place when the earthing grid is installed above the geotextile layer. Rods penetrating the geotextile can alleviate the potential voltage distribution issues and improve the earthing system performance regardless of the native soil stratification.

A New Type of Cemented Sand-Gravel (CSG) Mixtures for Water-Tightening of Hardfill Dams

This paper aims to achieve a specific type of cemented sand-gravel mixtures with low permeability to implement in the impervious zone of hardfill dams. To this end, various mixtures are prepared by blending two native soils of sand and gravel with different amounts of kaolinite or bentonite additives in presence of various cement content. The compaction properties, uniaxial compressive strength, permeability and scanning electron microscope (SEM) images of mixtures are measured. According to the results, the cemented mixture containing 10% of kaolinite additive regardless of native soil type exhibits the maximum strength. However, the bentonite disturbs the cement hydration in the mixture, and the strength of mixtures especially with high cement content decreases with increasing the bentonite content. The permeability of mixtures is related to the amount of cement and fine additive in the mixture. The permeability of both cemented sand and gravel mixtures decreases with increasing the bentonite additive. However, the kaolinite additive has a limited influence on the permeability of cemented gravel mixtures. The lowest permeability is achieved in the mixture involving the higher amount of bentonite (with a weight ratio of 30%) in presence of adequate cement.

Decomposition of carbon adsorbed on iron (III)-treated clays and their effect on the stability of soil organic carbon and external carbon inputs

The interaction of organic carbon (OC) with clay and metals stabilizes soil carbon (C), but the influence of specific clay-metal-OC assemblages (flocs) needs further evaluation. This study aimed to investigate the stability of flocs in soil as affected by external C inputs. Flocs representing OC-mineral soil fractions were synthesized using dissolved organic C (DOC) combined with kaolinite (1:1 layer structure) or montmorillonite (2:1 layer structure) clays in the absence or presence of two levels of Fe (III) (named low or high Fe). Flocs were mixed with soil (classified as Luvisol) and incubated with or without 13C labelled plant residue (i.e., ryegrass) for 30 days. The CO2 emissions and DOC concentrations as well as their 13C signatures from all treatments were examined. Total C mineralization from flocs was approximately 70% lower than non-flocced DOC. The flocs made with montmorillonite had 16–43% lower C mineralization rate than those made with kaolinite with no Fe or low Fe. However, when flocs were made with high Fe, clay mineralogy did not significantly affect total C mineralization. A positive priming effect (PE) of flocs on native soil OC was observed in all treatments, with a stronger PE found in lower Fe treatments. The high-Fe clay flocs inhibited ryegrass decomposition, while the flocs made without clay had no impact on it. Interestingly, flocs significantly decreased the PE of ryegrass on native soil OC decomposition. These results indicate that the adsorption of DOC onto clay minerals in the presence of Fe (III) stabilizes it against decomposition processes and its stability increases as Fe in flocs increases. Flocs also protect soil OC from the PE of external degradable plant C input. This study showed that Fe level and clay mineralogy play an important role in controlling soil C stability.

A Holistic Approach for Enhancing the Efficacy of Soil Microbial Inoculants in Agriculture:

Microbial inoculants can be an efficient tool to manage the soil and plant microbiomes providing direct beneficial effects, and for modulating native soil and plant-associated microbiota. However, the application of soil microbial inoculants as biofertilizers and biopesticides in agriculture is still limited by factors related to their formulation, application method, and the knowledge about the impact and interactions between microbial inoculants and native soil and plant host microbiomes. The review is thus describing and discussing three major aspects related to microbial-based product exploitation, namely: i) the discovery and screening of beneficial microbial strains; ii) the opportunities and challenges associated with strain multifunctional features; iii) the fermentation and formulation strategies also based on the use of wastes as growth substrates and the technical and regulatory challenges faced in their path to field application. All these issues are addressed in activities performed by the EXCALIBUR project (www.excaliburproject.eu), which aims to expand the current concept about microbiomes interactions, acknowledging their interactive network that can impact agricultural practices as well as on all living organisms within an ecosystem.

Study Of The Effectiveness Of The Use Of Gypsum And Volcanic Ash On Stability Of The Clay Soil Based On The CBR Value And The Unconfined Compression Test

Stabilization is one of the efforts to improve the condition of the soil which has a poor index of properties. One of the soil stabilization that is usually done is by adding chemicals to the soil. Chemicals commonly used in the form of cement, lime, bitumen. In this study, the stabilization of clay was carried out by adding gypsum and volcanic ash. The purpose of this study was to determine the value of the index properties due to the addition of 2% gypsum and volcanic ash on the clay soil, then to determine the maximum compressive strength value due to the addition of variations in stabilizing materials by testing the Unconfined Compression Test (UCT) and testing the California Bearing Ratio (CBR). ) laboratory. From the research, it was found that the original soil sample had a moisture content of 12.42%; specific weight 2.65; liquid limit 46.82% and plasticity index 29.40%. The original soil classification according to USCS is classified as Clay – Low Plasticity (CL) and according to AASHTO it is classified as A-7-6 (10). Unconfined Compression Test (UCT) values ​​for native soil and native soil plus 2% gypsum were 1.40 kg/cm2 and 1.66 kg/cm2. The laboratory CBR values ​​for soaked and unsoaked for the original soil were 4.44% and 6.28%, respectively. While the laboratory CBR values ​​soaked and unsoaked for the original soil plus 2% gypsum were 6.74% and 8.02%, respectively.The most effective results were obtained from a mixture of 2% gypsum and 10% volcanic ash with a UCT value of 2.79 kg/cm2 (an increase of 99.28%). For laboratory CBR testing, the most effective mixture was on a mixed variation of 2% gypsum and 9% volcanic ash with laboratory CBR values ​​soaked and unsoaked of 9.07% (an increase of 104.27% from the original soil) and 10 ,29% (an increase of 63.85% from the original land). The soil that has been mixed with the most effective stabilizer material, namely 2% gypsum and 9% volcanic ash is classified as Clay - Low Plasticity (CL) based on the USCS classification and is classified as A-6 (4) based on the AASHTO classification.

Effects of Corn Stalks and Urea on N2O Production from Corn Field Soil

Returning corn stalks to the field is an important and widely used soil management practice which is conducive to the sustainable development of agriculture. In this study, the effects of corn stalks and urea on N2O production in corn field soil were investigated through a 21-day incubation experiment. This study showed that increasing amounts of urea added to soil with a history of corn cultivation leads to increasing overall N2O emissions, by increasing both the intensity and the duration of emissions. Although N2O production was affected primarily by urea-derived NH4+-N and NO3−-N, its main source was native soil nitrogen, which accounted for 78.5 to 94.5% of N2O. Returning corn stalk residue to the field reduced the production of N2O, and the more urea was applied, the stronger the effect of corn residue on reducing N2O emissions. Combining the application of corn stalks and urea could reduce the concentration of NH4+-N and NO3−-N derived from urea, and then reduce the substrate required for N2O production in nitrification and denitrification processes. In addition, the combined application of corn stalks and urea could effectively inhibit the abundance of key N2O-producing genes AOA amoA, nirS and nirK.

Shen Congwen's Idealized Ethnic

This article investigates the underexamined ethnic motifs of the modern literary master Shen Congwen's 沈從文 fictional creations. In the field of Chinese literary scholarship, Shen is widely recognized as a leading figure of the May Fourth “native soil” literary tradition and is usually labeled as a “regionalist” writer. Yet as an ethnically hybrid author, Shen's ethnographically inspired, mythologizing accounts of indigenous non-Han tribes place him in a long tradition of searching for moral truths in borderland societies in Chinese literary and cultural history. The article argues that ethnicity is an important motif that runs throughout the early Shen Congwen's literary oeuvre, particularly in the Miao-themed stories that he crafted in the 1920s and 1930s. Shen idealizes non-Han peoples, particularly the Miao in southern China's borderland, as the ultimate source of moral courage and aesthetic perfection in his vision of a wholesome China. Through his ethnically themed novellas and short stories, Shen is both heir to and questions the Confucian tradition of locating a civilizational “other” in the non-Sinitic/non-Han border regions. The article further reveals how Shen embodies contradictory motifs with regard to ethnicity in China: on the one hand, he romanticizes the Miao as moral agents living freely in a timeless society, governed only by divine powers and unruly passions. On the other hand, Shen laments the historical discrimination experienced by the Miao and assumes a sober voice as he calls for ethnic equality. Simultaneously lyrical and political, Shen's ethnically themed works are significant for forming new scholarly understandings of both May Fourth literature and the broader discourse of ethnicity, which underpins the very notion of Chineseness in modern China.