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Topic Review
Catalytic Applications of Single-Atom Catalysts
Heterogeneous catalysis is an important research hotspot in the global field. Due to its economic and energy-saving features, it is widely used in the transformation of various energy resources (e.g., petroleum, coal, natural gas, and solar energy) in nature, the synthesis of numerous industrial chemicals, the purification of vehicle exhaust, and so on. It is estimated that catalysts are used in the production processes of about 80% of artificial chemicals at some stages, and about 35% of the world’s gross domestic product (GDP) is accounted for by catalytic processes. In the field of catalysis, exploring the efficient, stable, and economical catalyst formulations has promoted the rapid development of nanomaterials synthesis methods. Traditional heterogeneous catalysts are metal nanoparticles (NPs) dispersed on supports. Among them, noble metals are the most efficient catalysts. 
  • 683
  • 04 Nov 2022
Topic Review
Catalytic Ozonation and Membrane Contactors
Membrane filtration has been widely used in water and wastewater treatment. However, this process is not very effective for the removal of refractory organic compounds (e.g., of pharmaceutical origin). Alongside, ozonation is an efficient oxidative process, although ozone is considered to be a rather selective oxidant agent and sometimes it presents quite low mineralization rates. An improvement of this oxidation process is catalytic ozonation, which can degrade organic compounds via the acceleration of hydroxyl radicals’ production. The hydroxyl radicals are unselective oxidative species, presenting high reaction constants with organic compounds. An efficient way to couple membrane filtration with catalytic ozonation is the deposition of an appropriate solid catalyst onto the membrane surface. Catalytic membrane ozonation can enhance the degradation of these compounds and, subsequently, the incidence of membrane fouling (i.e., the major problem of membrane uses).
  • 960
  • 18 Nov 2020
Topic Review
Catch and Cover Crop Biomass Bioconversion into Energy
Catch and cover crops are defined as crops sown in pure or mixed sowings between two main crops. A short vegetation period is a key feature of these plants.
  • 213
  • 07 Feb 2024
Topic Review
Cathode Materials of Sodium-Metal Chloride Batteries
The widespread electrification of various sectors is triggering a strong demand for new energy storage systems with low environmental impact and using abundant raw materials. Batteries employing elemental sodium could offer significant advantages, as the use of a naturally abundant element such as sodium is strategic to satisfy the increasing demand.
  • 277
  • 08 Nov 2023
Topic Review
Cationic Polystyrene-Based Hydrogels
Nitrites are metastable anions that are derived from the oxidation of ammonia by agricultural pollution, sewage, decaying protein, and other nitrogen sources. They are a recognized environmental issue due to their role in eutrophication, as well as in surface and groundwater contamination, being toxic to almost all living creatures. Two cationic resins (R1 and R2) forming hydrogels (R1HG and R2HG) by dispersion in water in removing anionic dyes from water by electrostatic binding. 
  • 232
  • 01 Feb 2024
Topic Review
Celestial Coordinate System
In astronomy, a celestial coordinate system (or celestial reference system) is a system for specifying positions of satellites, planets, stars, galaxies, and other celestial objects relative to physical reference points available to a situated observer (e.g. the true horizon and north cardinal direction to an observer situated on the Earth's surface). Coordinate systems can specify an object's position in three-dimensional space or plot merely its direction on a celestial sphere, if the object's distance is unknown or trivial. The coordinate systems are implemented in either spherical or rectangular coordinates. Spherical coordinates, projected on the celestial sphere, are analogous to the geographic coordinate system used on the surface of Earth. These differ in their choice of fundamental plane, which divides the celestial sphere into two equal hemispheres along a great circle. Rectangular coordinates, in appropriate units, are simply the Cartesian equivalent of the spherical coordinates, with the same fundamental (x, y) plane and primary (x-axis) direction. Each coordinate system is named after its choice of fundamental plane.
  • 1.2K
  • 02 Dec 2022
Topic Review
Cellular Automata in Modeling and Predicting Urban Densification
The creation of an accurate simulation of future urban growth is considered to be one of the most important challenges of the last five decades that involves spatial modeling within a GIS environment. Even though built-up densification processes, or transitions from low to high density, are critical for policymakers concerned with limiting sprawl, the literature on models for urban study reveals that most of them focus solely on the expansion process. Although the majority of these models have similar goals, they differ in terms of implementation and theoretical assumptions. Cellular automata (CA) models have been proven to be successful at simulating urban growth dynamics and projecting future scenarios at multiple scales.
  • 433
  • 05 Aug 2022
Topic Review
Cement Production in Nigeria
Cement is the most common and extensively used adhesive in the construction industry. It is employed on highways, houses, embankments, bridges, commercial establishments, and flyovers. In recent years, the Nigerian cement industry has grown from import dependency to an export-thriving epicentre within Africa. The country possesses the largest cement industry within West Africa, with at least 12 registered companies amounting to a merged cement capacity of 58.9 Mt/yr. Dangote Cement is the largest cement producer in Nigeria and West Africa, manufacturing a combined share of more than 28.5 Mt/yr of cement capacity. Also, LafargeHolcim (through its subsidiary AshakaCem & Lafarge WAPCO) and BUA Group boost 18.9 Mt/yr and 11.5 Mt/yr of integrated cement capacity, respectively.
  • 12.3K
  • 16 Sep 2021
Topic Review
Cenozoic Basins-evolution Eastern-External Betic Zone
Four main unconformities (1-4) were recognized in the sedimentary record of the Cenozoic basins of the eastern External Betic Zone. More in detail, they are located at different stratigraphic levels as follows: (1) Cretaceous-Paleogene boundary even if this unconformity was also recorded at the early Paleocene (Murcia sector) and early Eocene (Alicante sector); (2) Eocene-Oligocene boundary and quite synchronous in the whole considered area; (3) early Burdigalian, and quite synchronous (recognized in the Murcia sector); (4) middle Tortonian (recognized in Murcia and Alicante sectors). These unconformities correspond to stratigraphic gaps of different temporal extensions with different meanings, which allowed recognizing minor sedimentary cycles in the Paleocene-Miocene time span. The Cenozoic marine sedimentation started over the oldest unconformity (i.e. the principal one), above the Mesozoic marine deposits. Paleocene-Eocene sedimentation shows numerous tectofacies (such as: turbidites, slumps, olistostromes, mega-olistostromes and pillow-beds) interpreted as related to an early, blind and deep-seated tectonic activity, acting in the more internal subdomains of the External Betic Zone as a result of the geodynamic processes related to the evolution of the westernmost branch of the Tethys. The second unconformity resulted from a Oligocene to Aquitanian sedimentary evolution in the Murcia Sector from marine realms to continental environments. This last time interval is characterized as the previous one by a gentle tectonic activity. On the other hand, the Miocene sedimentation was totally controlled by the development of superficial thrusts and/or bend zones of strike-slip faults both related to the regional geodynamic evolutionary framework linked to the Mediterranean opening. These bends of strike-slip faults created subsidence areas (pull-apart basin-type) and affected the sedimentation lying above the third unconformity. By contrast, the subsidence areas were bounded by structural highs affected by thrusts and folds. After the third unconformity, the Burdigalian-Serravallian sedimentation occurred mainly in shallow- to deep-water marine environments (Tap Fm). During the late Miocene, after the fourth unconformity, the activation of the bend zones of strike-slip faults caused a shallow marine environment sedimentation in the Murcia sector and a continental (lacustrine and fluvial) deposition in the Alicante sector represented, the latter resulting in alluvial fan deposits. Furthermore, the location of these fans changed over time according to the activation of faults responsible for the tectonic rising of Triassic salt deposits, which fed the fan themselves.
  • 1.2K
  • 10 Oct 2020
Topic Review
Central Highlands, Vietnam
Tây Nguyên, translated as Western Highlands and sometimes also called Central Highlands, is one of the regions of Vietnam. It contains the provinces of Đắk Lắk, Đắk Nông, Gia Lai, Kon Tum, Lâm Đồng. This region is sometimes referred to as Cao nguyên Trung bộ (literally "Midland Highlands"), and was referred to during the Republic of Vietnam as Cao nguyên Trung phần (literally "Central Highlands").
  • 735
  • 22 Nov 2022
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