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Topic Review
Country Code Top-Level Domain
A country code top-level domain (ccTLD) is an Internet top-level domain generally used or reserved for a country, sovereign state, or dependent territory identified with a country code. All ASCII ccTLD identifiers are two letters long, and all two-letter top-level domains are ccTLDs. In 2018, the Internet Assigned Numbers Authority (IANA) began implementing internationalized country code top-level domains, consisting of language-native characters when displayed in an end-user application. Creation and delegation of ccTLDs is described in RFC 1591, corresponding to ISO 3166-1 alpha-2 country codes. While gTLD have to obey international regulations, ccTLD are subjected to requirements that are determined by each country’s domain name regulation corporation. With over 150 million domain name registrations today, ccTLDs make up 40% of the total domain name industry. Country code extension applications began in 1985. The registered first extensions that year were .us (United States), .uk (United Kingdom), and .il (Israel). There are 312 ccTLDs in active use totally. .cn, .tk, .de and .uk contain the highest number of domains.
  • 7.2K
  • 08 Nov 2022
Topic Review
Can CFD Analysis Help PEM Fuel Cell Design and Operation?
Polymer electrolyte membrane (PEM) fuel cell system is an advanced power system for the future that is sustainable, clean and environmental friendly. PEM fuel cells are growing in importance as sources of sustainable energy and will doubtless form part of the changing program of energy resources in the future. PEM fuel cells are still undergoing intense development, and the combination of new and optimized materials, improved product development, novel architectures, more efficient transport processes, and design optimization and integration are expected to lead to major gains in performance, efficiency, reliability, manufacturability and cost-effectiveness. The difficult experimental environment of PEM fuel cell systems has stimulated efforts to develop models that could simulate and predict multi-dimensional coupled transport of reactants, heat and charged species using computational fluid dynamic (CFD) technology. The strength of the CFD numerical approach is in providing detailed insight into the various transport mechanisms and their interaction, and in the possibility of performing parameters sensitivity analyses. The results of CFD analyses are relevant in: conceptual studies of new designs, detailed product development, troubleshooting, and redesign. CFD analysis complements testing and experimentation, by reduces the total effort required in the experiment design and data acquisition. Relevant case studies and recent progress in CFD techniques used in PEM fuel cell development have been presented and analyzed. The CFD models are shown to be able to provide a computer-aided tool for design and optimize future PEM fuel cell with much higher power density, long cell life, and lower cost.
  • 7.2K
  • 26 Apr 2020
Topic Review
BMW X5 (E70)
The BMW E70 is the second-generation BMW X5 mid-size luxury crossover SUV. It replaced the BMW X5 (E53) in July 2006. It was manufactured alongside the BMW X6 at BMW's Greer, South Carolina plant in the U.S. and BMW's facility in Toluca, Mexico.
  • 7.2K
  • 29 Nov 2022
Topic Review
Nielsen Ratings
Nielsen TV ratings (commonly referred to as "Nielsen ratings") are the audience measurement systems operated by Nielsen Media Research that seek to determine the audience size and composition of television programming in the United States using a rating system. Nielsen Media Research was founded by Arthur C. Nielsen, a market analyst who started his career in the 1920s with marketing research and performance analysis. The company expanded into radio market analysis in the late 1930s, culminating in the Nielsen Radio Index in 1942, which was meant to provide statistics as to the markets of radio shows. The first Nielsen ratings for radio programs were released the first week of December 1947. They measured the top 20 programs in four areas: total audience, average audience, cumulative audience, and homes per dollar spent for time and talent. In 1950, Nielsen moved to television, developing a ratings system using the methods he and his company had developed for radio. That method became the primary source of audience measurement information in the US television industry.
  • 7.2K
  • 29 Sep 2022
Topic Review
Modular Construction
A modular construction is an assembly of standardized-dimension building elements such as wall panel, slab, beam or also an assembly of container-type units called “modules” or else “prefabricated prefinished volumetric construction (PPVC)” which are prefabricated in factory and afterwards transported and assembled on-site. The naming of “container house” is given to transportable modules that are completely finished in the factory and ready to be inhabited; for smaller units, eventually with different shapes, the nomenclature of “living pod” or “capsule” is also found in literature. Modular buildings are always prefabricated buildings, but the reverse is not necessarily true. The degree of prefabrication and assembly technique mainly varies depending on the life span of the building (temporary or permanent), the desired space layout and the technical equipment to install (heating, electricity, sewer, plumbing, etc.).
  • 7.2K
  • 26 Oct 2020
Topic Review
Zwitterionic Dental Biomaterials
Biofilms are formed on surfaces inside the oral cavity covered by the acquired pellicle and develop into a complex, dynamic, microbial environment. Oral biofilm is a causative factor of dental and periodontal diseases. Accordingly, novel materials that can resist biofilm formation have attracted significant attention. Zwitterionic polymers (ZPs) have unique features that resist protein adhesion and prevent biofilm formation while maintaining biocompatibility. Recent literature has reflected a rapid increase in the application of ZPs as coatings and additives with promising outcomes. 
  • 7.2K
  • 29 Dec 2020
Topic Review
Ti Nitrides and Ti Silicides
The diffusion of nitrogen into TiSi2 films of low electrical resistivity, deposited on complementary metal oxyde semiconductor (CMOS) and Schottky diodes components increases their performances. TiN acts as a good diffusion barrier, gate material, Schottky barrier contact...Both TiSi2 and TiN are synthesized in Ti films coated on Si wafers and processed in an expanding microwave plasma producing nitrogen species such as NHx...This process promotes the chemical reactions at the surface of the metal. The growth of both compounds give rise to two competing processes which are thermodynamically and kinetically controlled. Ti films, 250 nm thick, processed at 600°C for  30 min, only consist of TiSi2 crystallites and TiN of amorphous structure. TiN crystallizes at 800°C and grows at the expense of TiSi2 according to thermodynamic data. 
  • 7.2K
  • 30 Oct 2020
Topic Review
The Braking Torque
A disc brake is a braking system in which a disc that rotates in solidarity with the vehicle wheel is subjected to friction by brake pads with a high coefficient of friction. The brake pads are arranged in a part called the caliper, which is in turn fixed solidly to the structure of the car. A hydraulic circuit pushes the brake pads against the disc with sufficient force to transform all or part of the kinetic energy of the vehicle in movement, into heat, until it is stopped or its speed is reduced, as the case may be.
  • 7.2K
  • 27 Oct 2020
Topic Review
Livelihood Vulnerability
Livelihood vulnerability can be a function of both physiological and social factors [9]. Physiological vulnerability is the extent to which communities are exposed to physical effects such as sea-level rise and an increase in sea temperature, and/or atmospheric temperature. Such exposure to climate change increases rural livelihood vulnerability and reduces households’ ability to cope with climate risks, shocks, and stress. Rural households often have limited assets and thus adaptive capacity. The social vulnerability can include factors such as relative inequality, culture, the degree of urbanisation, and the rate of economic growth.
  • 7.2K
  • 15 Jul 2021
Topic Review
Activity of Kalanchoe pinnata in Cancer
Kalanchoe pinnata (Lam) Pers. (syn. Bryophyllum pinnatum Lam.), belonging to the genus Kalanchoe, is a succulent plant cultivated in gardens, which can be found as a herb or shrub. The bioactive ingredients in Kalanchoe pinnata, a succulent herb with ethnomedical applications for several diseases, including cancer, and reveal its anticancer mechanisms through a molecular approach.
  • 7.2K
  • 17 Oct 2022
Topic Review
MOFs and COFs
Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) are two innovative classes of porous coordination polymers. MOFs are three-dimensional materials made up of secondary building blocks comprised of metal ions/clusters and organic ligands whereas COFs are 2D or 3D highly porous organic solids made up by light elements (i.e., H, B, C, N, O). Both MOFs and COFs, being highly conjugated scaffolds, are very promising as photoactive materials for applications in photocatalysis and artificial photosynthesis because of their tunable electronic properties, high surface area, remarkable light and thermal stability, easy and relative low-cost synthesis, and structural versatility. 
  • 7.1K
  • 08 Dec 2020
Topic Review
Salt-Tolerant Rice
Soil salinization and a degraded ecological environment are challenging agricultural productivity and food security.  Salt stress-inhibited growth and development of plants is the key limiting factor resulting in the reduction of rice yield, the contradiction of yield promotion and salt tolerance greatly affects salt-tolerant rice breeding.  Here, we  highlight current advances and challenges to breeding salt-tolerant rice, providing a basis for further studies and efforts aimed at breeding salt-tolerant rice varieties.
  • 7.1K
  • 17 Jan 2022
Topic Review Peer Reviewed
Metaverse
The Metaverse is the post-reality universe, a perpetual and persistent multiuser environment merging physical reality with digital virtuality. It is based on the convergence of technologies that enable multisensory interactions with virtual environments, digital objects and people such as virtual reality (VR) and augmented reality (AR). Hence, the Metaverse is an interconnected web of social, networked immersive environments in persistent multiuser platforms. It enables seamless embodied user communication in real-time and dynamic interactions with digital artifacts. Its first iteration was a web of virtual worlds where avatars were able to teleport among them. The contemporary iteration of the Metaverse features social, immersive VR platforms compatible with massive multiplayer online video games, open game worlds and AR collaborative spaces.
  • 7.1K
  • 13 Apr 2022
Topic Review
Six-Gear Roadmap towards Smart Factory
The fourth industrial revolution is the transformation of manufacturing into smart manufacturing. Advanced industrial digital technologies that make the trend Industry 4.0 are considered as the transforming force that will enable this transformation. However, these technologies need to be connected, integrated and used effectively to create value and to provide insights for data driven manufacturing. Smart manufacturing is a journey and requires a roadmap to guide manufacturing organizations for its adoption. The proposed roadmap is a simple holistic management strategy for an Industry 4.0 implementation journey. It serves as a strategic practical tool for rapid adoption of Industry 4.0 technologies. It bridges the gap between the advanced technologies and their application in manufacturing industry, especially for SMEs.
  • 7.1K
  • 06 Aug 2021
Topic Review
Sound Vibration on Human Health
This entry presents a narrative review of research literature to “map the landscape” of the mechanisms of the effect of sound vibration on humans including the physiological, neurological, and biochemical. It begins by narrowing music to sound and sound to vibration. The focus is on low frequency sound (up to 250 Hz) including infrasound (1–16 Hz). Types of application are described and include whole body vibration, vibroacoustics, and focal applications of vibration. Literature on mechanisms of response to vibration is categorized into hemodynamic, neurological, and musculoskeletal. Basic mechanisms of hemodynamic effects including stimulation of endothelial cells and vibropercussion; of neurological effects including protein kinases activation, nerve stimulation with a specific look at vibratory analgesia, and oscillatory coherence; of musculoskeletal effects including muscle stretch reflex, bone cell progenitor fate, vibration effects on bone ossification and resorption, and anabolic effects on spine and intervertebral discs. In every category research on clinical applications are described. The conclusion points to the complexity of the field of vibrational medicine and calls for specific comparative research on type of vibration delivery, amount of body or surface being stimulated, effect of specific frequencies and intensities to specific mechanisms, and to greater interdisciplinary cooperation and focus. 
  • 7.1K
  • 21 Jun 2021
Topic Review
Vacuum State
In quantum field theory, the quantum vacuum state (also called the quantum vacuum or vacuum state) is the quantum state with the lowest possible energy. Generally, it contains no physical particles. Zero-point field is sometimes used as a synonym for the vacuum state of an individual quantized field. According to present-day understanding of what is called the vacuum state or the quantum vacuum, it is "by no means a simple empty space". According to quantum mechanics, the vacuum state is not truly empty but instead contains fleeting electromagnetic waves and particles that pop into and out of existence. The QED vacuum of quantum electrodynamics (or QED) was the first vacuum of quantum field theory to be developed. QED originated in the 1930s, and in the late 1940s and early 1950s it was reformulated by Feynman, Tomonaga and Schwinger, who jointly received the Nobel prize for this work in 1965. Today the electromagnetic interactions and the weak interactions are unified (at very high energies only) in the theory of the electroweak interaction. The Standard Model is a generalization of the QED work to include all the known elementary particles and their interactions (except gravity). Quantum chromodynamics (or QCD) is the portion of the Standard Model that deals with strong interactions, and QCD vacuum is the vacuum of quantum chromodynamics. It is the object of study in the Large Hadron Collider and the Relativistic Heavy Ion Collider, and is related to the so-called vacuum structure of strong interactions.
  • 7.1K
  • 17 Oct 2022
Topic Review
Human Body Segments
The knowledge of human body proportions and segmental properties of limbs, head and trunk is of fundamental importance in biomechanical research. Given that many methods are employed, it is important to know which ones are currently available, which data on human body masses, lengths, center of mass (COM) location, weights and moment of inertia (MOI) are available and which methods are most suitable for specific research purposes. Graphical, optical, x-ray and derived techniques, MRI, laser, thermography, has been employed for in-vivo measurement, while direct measurements involve cadaveric studies with dissection and various methods of acquiring shape and size of body segments.
  • 7.1K
  • 20 Nov 2020
Topic Review
History of Nanotechnology
The history of nanotechnology traces the development of the concepts and experimental work falling under the broad category of nanotechnology. Although nanotechnology is a relatively recent development in scientific research, the development of its central concepts happened over a longer period of time. The emergence of nanotechnology in the 1980s was caused by the convergence of experimental advances such as the invention of the scanning tunneling microscope in 1981 and the discovery of fullerenes in 1985, with the elucidation and popularization of a conceptual framework for the goals of nanotechnology beginning with the 1986 publication of the book Engines of Creation. The field was subject to growing public awareness and controversy in the early 2000s, with prominent debates about both its potential implications as well as the feasibility of the applications envisioned by advocates of molecular nanotechnology, and with governments moving to promote and fund research into nanotechnology. The early 2000s also saw the beginnings of commercial applications of nanotechnology, although these were limited to bulk applications of nanomaterials rather than the transformative applications envisioned by the field.
  • 7.1K
  • 17 Oct 2022
Topic Review
Wolf Distribution
Wolf distribution is the species distribution of the wolf (Canis lupus). Originally, wolves occurred in Eurasia above the 12th parallel north and in North America above the 15th parallel north. However, deliberate human persecution has reduced the species' range to about one-third, because of livestock predation and fear of wolf attacks on humans. The species is now extirpated (made locally extinct) in much of Western Europe, Mexico, and the contiguous United States , and completely from the British Isles and the Japanese archipelago. In modern history, the gray wolf occurs mostly in wilderness and remote areas, particularly in Canada , Alaska, the Northern United States, Europe and Asia from about the 75th parallel north to the 12th parallel north. Wolf population declines have been arrested since the 1970s, and have fostered recolonization and reintroduction in parts of its former range, due to legal protection, changes in land-use and rural human population shifts to cities. Competition with humans for livestock and game species, concerns over the danger posed by wolves to people, and habitat fragmentation pose a continued threat to the species. Despite these threats, because of the gray wolf's relatively widespread range and stable population, it is classified as Least Concern on the IUCN Red List. In Africa the population of wolves is limited to the northern regions with the African golden wolf (Canis lupaster) north of the Sahara and the Ethiopian wolf (Canis simensis) in Ethiopia.
  • 7.1K
  • 25 Oct 2022
Topic Review
Types of Insulation Materials
Insulation materials are classified into three main categories depending on material composition, material technology, and material sustainability index.
  • 7.1K
  • 11 Jan 2023
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