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Topic Review
Reuse of Municipal Solid Waste in Construction
Society is highly dependent on natural resources such as rocks (aggregates) and minerals. Although they are an abundant resource on the planet, their recovery is slow in terms of human lifespan, and from this fact, they are considered non-renewable resources. The construction industry currently consumes around 3000 million tons of natural resources annually and is responsible for 34% of greenhouse gas emissions into the atmosphere. An alternative to reduce this over-extraction is the substitution of aggregates and cement for municipal solid waste (MSW), which represents the application of the circular economy principles. This approach and the waste management hierarchy are described, with a focus on the Latin America and the Caribbean situation. MSW is composed of several fractions, such as organic waste, paper, cardboard, metals, plastic, and glass, among other valuable materials. Areas of opportunity for their reuse in the construction industry have been demonstrated worldwide: a) plastics as substitutes for aggregates or reinforcing fibers, or replaced construction elements such as bricks; b) glass in the production of concrete, mortar, and asphalt pavement; c) paper as a hygrothermal and lighting regulator in buildings, among others.  
  • 1.0K
  • 20 Dec 2022
Topic Review
Gravity Field and Steady-State Ocean Circulation Explorer
The Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) was the first of ESA's Living Planet Programme satellites intended to map in unprecedented detail the Earth's gravity field. The spacecraft's primary instrumentation was a highly sensitive gravity gradiometer consisting of three pairs of accelerometers which measured gravitational gradients along three orthogonal axes. Launched on 17 March 2009, GOCE mapped the deep structure of the Earth's mantle and probed hazardous volcanic regions. It brought new insight into ocean behaviour; this in particular, was a major driver for the mission. By combining the gravity data with information about sea surface height gathered by other satellite altimeters, scientists were able to track the direction and speed of geostrophic ocean currents. The low orbit and high accuracy of the system greatly improved the known accuracy and spatial resolution of the geoid (the theoretical surface of equal gravitational potential on the Earth). The satellite's unique arrow shape and fins helped keep GOCE stable as it flew through the thermosphere at a comparatively low altitude of 255 kilometres (158 mi). Additionally, an ion propulsion system continuously compensated for the variable deceleration due to air drag without the vibration of a conventional chemically powered rocket engine, thus limiting the errors in gravity gradient measurements caused by non-gravitational forces and restoring the path of the craft as closely as possible to a purely inertial trajectory. After running out of propellant, the satellite began dropping out of orbit and made an uncontrolled reentry on 11 November 2013.
  • 1.0K
  • 02 Nov 2022
Topic Review
Paradigm Shift for Transition to Sustainable Urban Transport
The traffic-engineering methods of planning based on the predict-and-provide principle have self-enforcing effects of induced traffic and an unhealthy environment for humans as well as for the planet. Regardless of the huge negative effects and the recognition that a paradigm shift is emerging as the sum of methods and achievements developed by the community of academics, experts, practitioners, policymakers, and urban communities. Findings can have practical, effective implications as the determinants of a new transport policy paradigm that shows the way out of the trap of path dependency. The originality of the approach lies in having expanded and applied the concept of anomalies of the theory to the adverse effects of technologies and the mismatch between people and the modern urban environment. 
  • 1.0K
  • 14 Mar 2022
Topic Review
Unmanned NASA Missions
Following is a sampling of some of NASA's past and present programs excluding manned spacecraft. The years in brackets are for first and latest launching. A program is a number of flights or missions with the same kind of spacecraft, therefore the name of the program and the name of the spacecraft used will often be the same. In all, NASA have made more than 1,000 unmanned missions into Earth orbit or beyond.
  • 1.0K
  • 23 Oct 2022
Topic Review
Energy Efficiency in Smart Cities
Cities are constantly facing major challenges, mainly due to continuous population growth and their diversion to urban living. These challenges depend on cities’ geography and culture but, not exhaustively, are, namely: congestion management, excess pollution, resource usage, absence of satisfactory physical and social infrastructures, necessity to maintain continuous sustainable economic growth, and increasingly narrower energy and environmental obligations. The energy transition on the roadmap to a decarbonized economy can never be implemented effectively, both in terms of costs and timing, without energy efficiency being the priority, and cities will have a crucial role in such a process.
  • 1.0K
  • 10 Dec 2021
Topic Review
Tanks in France
French development into tanks began during World War I as an effort to overcome the stalemate of trench warfare, and largely at the initiative of the manufacturers. The Schneider CA1 was the first tank produced by France, and 400 units were built. The French also experimented with various tank designs, such as the Frot-Laffly landship, Boirault machine and Souain experiment. Another 400 Saint-Chamond tanks were manufactured from April 1917 to July 1918, however these tanks were largely underpowered and of limited utility due to the design of the caterpillar tracks, which were too short in comparison with the tank's length and weight. The most significant French tank development during the war was the Renault FT light tank, which set the general layout for future tank designs and was used or redesigned by various military forces, including those of the United States.
  • 1.0K
  • 03 Nov 2022
Topic Review
Fruit and Vegetable Wastes
Food waste (FW) is already acknowledged as a major global issue that threatens the long-term viability of the food supply chain.
  • 1.0K
  • 26 Oct 2021
Topic Review
Organophosphorus Compounds Degradation by EC3.1.8.2
The organophosphorus substances, including pesticides and nerve agents (NAs), represent highly toxic compounds. Standard decontamination procedures place a heavy burden on the environment. Given their continued utilization or existence, considerable efforts are being made to develop environmentally friendly methods of decontamination and medical countermeasures against their intoxication. Enzymes can offer both environmental and medical applications. One of the most promising enzymes cleaving organophosphorus compounds is the enzyme with enzyme commission number (EC): 3.1.8.2, called diisopropyl fluorophosphatase (DFPase) or organophosphorus acid anhydrolase from Loligo Vulgaris or Alteromonas sp. JD6.5, respectively. Structure, mechanisms of action and substrate profiles are described for both enzymes. Wild-type (WT) enzymes have a catalytic activity against organophosphorus compounds, including G-type nerve agents. Their stereochemical preference aims their activity towards less toxic enantiomers of the chiral phosphorus center found in most chemical warfare agents. Site-direct mutagenesis has systematically improved the active site of the enzyme. These efforts have resulted in the improvement of catalytic activity and have led to the identification of variants that are more effective at detoxifying both G-type and V-type nerve agents. Some of these variants have become part of commercially available decontamination mixtures.
  • 1.0K
  • 24 Dec 2020
Topic Review
Porous Concrete
Alternative materials to replace cement in pavements have recently been widely studied with the purpose of decreasing the environmental impacts that the construction industry generates. In this context, the implementation of sustainable urban drainage systems has grown, especially with porous pavements, with the intention to reduce water and environmental impacts. In the present investigation, the addition of alternative materials to minimize the use of cement in porous concrete pavements is evaluated. Starting from a partial substitution of Portland cement with metakaolin, experimental geopolymer concretes were produced with metakaolin and waste basalt powder according to several dosages. Two sets of mixtures were analyzed to evaluate the Porous Concrete Design (PCD) methodology for porous concrete mixtures with alternative materials. A deep analysis was proposed for the evaluation of the mechanical and volumetric properties of the mixtures. Results demonstrated that replacing 5% of cement with metakaolin can increase both permeability and indirect tensile strength. Geopolymer mixtures can achieve permeability significantly higher than the traditional porous concrete, but this decreases their indirect tensile strength. However, considering the promising results, an adjustment in the mix design of the geopolymer mixtures could increase their mechanical properties without negatively affecting the porosity, making these materials a suitable alternative to traditional porous cement concrete, and a solution to be used in urban pavements.
  • 1.0K
  • 27 Oct 2020
Topic Review
Capacitive Field-Effect Bio-Chemical Sensors
       Electrolyte-insulator-semiconductor (EIS) field-effect sensors belong to a new generation of electronic chips for biochemical sensing, enabling a direct electronic readout. The review gives an overview on recent advances and current trends in the research and development of chemical sensors and biosensors based on the capacitive field-effect EIS structure—the simplest field-effect device, which represents a biochemically sensitive capacitor. Fundamental concepts, physicochemical phenomena underlying the transduction mechanism and application of capacitive EIS sensors for the detection of pH, ion concentrations, and enzymatic reactions, as well as the label-free detection of charged molecules (nucleic acids, proteins, and polyelectrolytes) and nanoparticles, are presented and discussed.
  • 1.0K
  • 19 Apr 2022
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