Search Results (3)

The sustainability of agriculture is seriously threatened by climate change. In Europe, chestnut ecosystems, which are growing mainly in Mediterranean climate, are facing during summertime increasing of heat and drought stresses. These induce fragilities on trees, leading to a reduction in productivity and predisposing them to pest and disease attacks. The plasticity of chestnut species under contrasting climate is known. Understanding the specific adaptation of cultivars to different climate features is now important to anticipating climate changes. Caucasian Region is considered the origin center of chestnut (Castanea sativa), which is characterized by climatic transition from the Mediterranean to the Euro-Siberian area. Mostly, areas of chestnut are concentrated in the countries around the Mediterranean Basin, thriving in regions with humid and Pré-Atlantic bioclimates. In Portugal, more than 95% of the chestnut area is located in the Center and North side of Portugal. This is an anisohydry species, characterized by good hydroplasticity: 90% reduction in A occurs when Ψ_wstem drops to −1.25 MPa, and a 50% reduction in A occurs at values of −1.7 MPa. The highest fatty acid contents in chestnut chloroplasts are a-linolenic acid (18:3), ranging between 40 and 50% of the total amount and being the unsaturated/saturated 2.27 for Longal. New strategies are being investigated in order to increase tolerance against those abiotic factors in chestnut species. They include the use of innovative irrigation techniques, which can increase production 22–37%. Fertilization with silicone (Si) has been investigated to promote the tolerance of plants against heat and drought stresses. Breeding programs, mostly (in Europe) against ink disease, have been performed since the middle of the XX century to create new genotypes (such the Portuguese ColUTAD^®). ClimCast, a network of orchards, was created in Portugal with the aim of responding to the new challenges facing orchards in the context of climate change. Full article

Filtrate reducer is a drilling fluid additive that can effectively control the filtration loss of drilling fluid to ensure the safe and efficient exploitation of oilfields. It is the most widely used treatment agent in oilfields. Due to its moderate conditions and controllable procedure, alkaline hydrolysis of high-purity waste polyacrylonitrile has been utilized for decades to produce filtrate reducer on a large scale in oilfields. However, the issues of long hydrolysis time, high viscosity of semi-finished products, high drying cost, and tail gas pollution have constrained the development of the industry. In this study, low-purity waste acrylic fiber was first separated and purified using high-temperature hydroplastization, and the hydrolyzed product was obtained using alkaline hydrolysis with the micro-water method, which was called MW−HPAN. The hydrolysis reaction was characterized using X-ray diffraction, scanning electron microscopy, infrared spectroscopy, and thermogravimetric analysis, and the elemental analysis showed a hydrolysis degree of 73.21%. The experimental results showed that after aging at 180 °C for 16 h, the filtration volume of the freshwater base slurry with 0.30% dosage and 4% brine base slurry with 1.20% dosage was 12.7 mL and 18.5 mL, respectively. The microstructure and particle size analysis of the drilling fluid gel system showed that MW−HPAN could prevent the agglomeration of clay and maintain a reasonable particle size distribution even under the combined deteriorating effect of high temperature and inorganic cations, thus forming a dense filter cake and achieving a low filtrate volume of the drilling fluid gel system. Compared with similar commercially available products, MW−HPAN has better resistance to temperature and salt in drilling fluid gel systems, and the novel preparation method is promising to be extended to practical production. Full article

Tectonic events caused by paleoearthquakes are reflected in sediments. Outcrops and cores from the Chang-7 Member of the Late Triassic Yanchang Formation, Ordos Basin in Northern China, yield a wide variety of soft-sediment deformation structures (SSDSs), many of which are laterally extensive for more than 150 km. They include various types of folds, soft-sediment liquefaction flow deformation (liquefied sand dyke, liquefied breccia), gravity-driven deformation (load structures, ball-and-pillow structures), hydroplastic deformation (loop bedding, convolute deformation), and brittle deformation (intrastratal and stair-step faults, cracks). In most cases, deformation resulted in hybrid brittle-ductile structures exhibiting lateral variation in deformation style. These occur in delta front to semideep-to-deep lake sands and mudstones (shales). The seismites recognized in outcrops and cores indicate earthquakes with magnitudes (Ms) between 6 and 8, which are interpreted as a response to orogenic events related to the collision of the South China Block (SCB) and North China Block (NCB) during the Late Triassic period. Systematic study of the spatial and temporal distribution of these seismites improves the understanding of the tectonic context and evolutionary history of sedimentary basements. This study can provide a new perspective on the evolution of tectonic activities in the basin. Full article