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Topic Review
Contaminations in Ion-Adsorption Type Rare Earths Tailings
Rare earth elements, particularly middle and heavy rare earth, are among the most valuable resources in the pursuit of a greener economy. The production of middle and heavy rare earth elements heavily relies on ion adsorption, which constitutes over 80% of global output and is centered in southern China. Unfortunately, the extensive mining activities have led to severe environmental pollution, resource depletion, and risks to human health.
  • 470
  • 16 May 2023
Topic Review
Contemporary Methods of Measuring Methane Emission from Ruminants
Methane is the second most important anthropogenic greenhouse gases (GHG) in terms of global warming potential (GWP) and quantity and is responsible for 20% of the global warming caused by anthropogenic GHG emissions. The global annual CH4 emission from ruminant livestock is estimated to be between 80 and 95 million tons. Methane (CH4) production is also a loss of energy availability to the host ruminant animal, normally representing between 2% and 12% of the total gross energy intake, depending on the level of intake and diet composition. There is immense interest to develop an accurate ruminant CH4 emission of accounting to reduce the negative effects of GHGs on the environment and to evaluate mitigation strategies. Several methods have been developed to measure CH4 emissions from ruminants.
  • 452
  • 07 Nov 2022
Topic Review
Contrastive Learning for Hyperspectral Image Classification
Despite the rapid development of deep learning in hyperspectral image classification (HSIC), most models require a large amount of labeled data, which are both time-consuming and laborious to obtain. However, contrastive learning can extract spatial–spectral features from samples without labels, which helps to solve the above problem. 
  • 279
  • 02 Aug 2023
Topic Review
Contribution of Opuntia Species to Ecosystem
Opuntia is an invasive flowering succulent plant species that grows up to 5 m tall and is a crassulacean acid metabolism (CAM) plant which belongs to the Cactaceae family.
  • 1.2K
  • 13 Apr 2022
Topic Review
Contributions of Nano-Nitrogen Fertilizers to Sustainable Development Goals
Nano-nitrogen fertilizers (NNFs) have emerged as a promising technology in the field of agriculture, offering potential solutions to improve nutrient uptake efficiency, enhance crop productivity, and reduce environmental impacts. NNFs showed superior characteristics and performance on crops and, therefore, became a potential alternative to conventional nitrogen (N) fertilizers. These fertilizers enhance plant uptake while simultaneously reducing environmental losses. For example, a hydroxy appetite-based urea NNF extended the N release for 112 days, which could cover the N demand of many perennial crops, thus reducing losses. 
  • 171
  • 19 Dec 2023
Topic Review
Controlled Environment Agriculture and Sustainability
Controlled Environment Agriculture (CEA) is one of the emerging agri-food technologies that has increasingly gained attention from researchers, practitioners, and consumers for its potential to make growing practices more sustainable. The term controlled environment agriculture was first introduced in the 1960s, referring to an intensive approach for controlling plant growth through the broad implementation of advanced techniques and innovations in technology. In this sense, CEA is not a completely new concept, as agriculture has witnessed a technological and functional evolution over the last century, from simple row covers in open fields to highly sophisticated indoor facilities where all growing elements are under accurate control. By controlling the growth environments and manipulating plant responses to their environments, CEA claims to offer advantages to increase production efficiency, optimise plant yield, and improve product quality.
  • 430
  • 17 Jan 2023
Topic Review
Controlling Factors of California Precipitation
Using observational data covering 1948–2020, the environmental factors controlling the winter precipitation in California were investigated. Empirical orthogonal function (EOF) analysis was applied to identify the dominant climate regimes contributing to the precipitation. The first EOF mode described a consistent change, with 70.1% variance contribution, and the second modeexhibited a south–east dipole change, with 11.7% contribution. For EOF1, the relationship was positive between PC1(principal component) and SST (sea surface temperature) in the central Pacific Ocean, while it was negative with SST in the southeast Indian Ocean. The Pacific–North America mode, induced by the positive SST and precipitation in the central Pacific Ocean, leads to Californiabeing occupied by southwesterlies, which would transport warm and wet flow from the ocean, beneficial for precipitation. As for the negative relationship, California is controlled by biotrophically high pressure, representing part of the Rossby wave train induced by the positive SST in the Indian ocean, which is unfavorable for the precipitation. For EOF2, California is controlled by positivevorticity at the upper level, whereas at the lower level, there is positive vorticity to the south and negative vorticity to the north, the combination of which leads to the dipole mode change in the precipitation.
  • 519
  • 20 Aug 2021
Topic Review
Convective Boundary Layer
The Convective Boundary layer (CBL), also known as the daytime Planetary boundary layer, is the part of the atmosphere most directly affected by solar heating of the earth's surface. This layer extends from the earth surface to a capping inversion that typically locates at a height of 1–2 km by midafternoon over land. Below the capping inversion (10-60% of CBL depth, also called entrainment zone in the daytime), CBL is divided into two sub-layers: mixed layer (35-80% of CBL depth) and surface layer (5-10% of CBL depth). The mixed layer, the major part of CBL, has a nearly constant distribution of quantities such as potential temperature, wind speed, moisture and pollutant concentration because of strong buoyancy generated convective turbulent mixing. Parameterization of turbulent transport is used to simulate the vertical profiles and temporal variation of quantities of interest, because of the randomness and the unknown physics of turbulence. However, turbulence in the mixed layer is not completely random, but is often organized into identifiable structures such as thermals and plumes in the CBL. Simulation of these large eddies is quite different from simulation of smaller eddies generated by local shears in the surface layer. Non-local property of the large eddies should be accounted for in the parameterization.
  • 980
  • 24 Nov 2022
Topic Review
Conventional Event Tree Analysis on Liquefied Natural Gas
Liquefied natural gas (LNG) is stored in facilities located in urban areas and transported over public roads. A shift towards the broader use of LNG is economically and environmentally justified. Conventional event trees for LNG emergency release in three different units is a concept that is based on the physical and chemical properties of LNG. It has been designed with deep consideration and analysis of past experiences and real cases of LNG incidents. The idea of having training checkpoints, such as ‘decision points’ and ‘learning curve points’ in the continuum of a training or exercise enable the achievement of optimal learning objectives in a flexible way which take into account the trainee individual mental and physical disposition on a day, scalability of difficulty level as well as realistic scenario paths determined by the performance of the trainees facing concrete operational problems.
  • 804
  • 07 Mar 2022
Topic Review
Conversion of Spent SCR Catalysts into Photocatalysts
Research has explored new recycling methods to convert spent SCR catalysts into products rather than raw materials, such as a pigment and ceramic opacifier. The idea of recycling spent SCR catalysts as photocatalysts for pollution treatment is in-line with the concept of “treating waste with waste”.
  • 461
  • 16 Nov 2022
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