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Topic Review
Oscillatory Spinning Drop Interfacial Rheology
The oscillatory spinning drop method has been proven recently to be an accurate technique to measure dilational interfacial rheological properties. It is the only available equipment for measuring dilational moduli in low interfacial tension systems, as is the case in applications dealing with surfactant-oil-water three-phase behavior like enhanced oil recovery, crude oil dehydration, or extreme microemulsion solubilization. Different systems can be studied with this method with the lower density phase as the spinning drop, i.e, oil-in-water, microemulsion-in-water, oil-in-microemulsion, including systems with the presence of complex natural surfactants like asphaltene aggregates or particles. The technique allows studying the characteristics and properties of water/oil interfaces, particularly when the oil contains asphaltenes and when surfactants are present. We have found that using the oscillating spinning drop method to measure interfacial rheology properties can help make precise measurements in a reasonable amount of time. This is of significance when systems with long equilibration times, e.g., asphaltene or high molecular weight surfactant-containing systems are measured, or with systems formulated with a demulsifier which is generally associated with optimum formulation and a low interfacial tension.
  • 1.6K
  • 05 Sep 2021
Topic Review
RFID Sensors for IoT
Abstract: Radio-frequency identification (RFID) sensors are one of the fundamental components of the Internet of Things.  Within this framework, chipless RFIDs are a breakthrough technology because, removing the cost associated with the chip, are at the same time printable, passive, low-power and suitable for harsh environments. For this reason, there is a clear motivation and interest to extend the chipless sensing functionality to physical, chemical, structural and environmental parameters. Temperature and humidity sensors, as well as localization, proximity, and structural health prototypes, have already been produced, and many other sensing applications are on the way. In this review, architectural approaches and requirements related to the materials employed for chipless RFID sensing are summarized. The state-of-the-art of many categories of sensors and their applications is reported and an analysis of the current limitations and possible solution strategies are given, together with an overview of expected future developments.
  • 1.6K
  • 29 Oct 2020
Topic Review
Nanobiotechnology
Nanobiotechnology, bionanotechnology, and nanobiology are terms that refer to the intersection of nanotechnology and biology. Given that the subject is one that has only emerged very recently, bionanotechnology and nanobiotechnology serve as blanket terms for various related technologies. This discipline helps to indicate the merger of biological research with various fields of nanotechnology. Concepts that are enhanced through nanobiology include: nanodevices (such as biological machines), nanoparticles, and nanoscale phenomena that occurs within the discipline of nanotechnology. This technical approach to biology allows scientists to imagine and create systems that can be used for biological research. Biologically inspired nanotechnology uses biological systems as the inspirations for technologies not yet created. However, as with nanotechnology and biotechnology, bionanotechnology does have many potential ethical issues associated with it. The most important objectives that are frequently found in nanobiology involve applying nanotools to relevant medical/biological problems and refining these applications. Developing new tools, such as peptoid nanosheets, for medical and biological purposes is another primary objective in nanotechnology. New nanotools are often made by refining the applications of the nanotools that are already being used. The imaging of native biomolecules, biological membranes, and tissues is also a major topic for nanobiology researchers. Other topics concerning nanobiology include the use of cantilever array sensors and the application of nanophotonics for manipulating molecular processes in living cells. Recently, the use of microorganisms to synthesize functional nanoparticles has been of great interest. Microorganisms can change the oxidation state of metals. These microbial processes have opened up new opportunities for us to explore novel applications, for example, the biosynthesis of metal nanomaterials. In contrast to chemical and physical methods, microbial processes for synthesizing nanomaterials can be achieved in aqueous phase under gentle and environmentally benign conditions. This approach has become an attractive focus in current green bionanotechnology research towards sustainable development.
  • 1.6K
  • 11 Oct 2022
Topic Review
Organic Waste Gasification by Steam and Carbon Dioxide
The selective studies on environmentally friendly, combustion-free, allothermal, atmospheric-pressure, noncatalytic, direct H2O/CO2 gasification of organic feedstocks like biomass, sewage sludge wastes (SSW) and municipal solid wastes (MSW) are considered to demonstrate the pros and cons of the approaches and provide future perspectives. The environmental friendliness of H2O/CO2 gasification is well known as it is accompanied by considerably less harmful emissions into the environment as compared to O2/air gasification. Comparative analysis of the various gasification technologies includes low-temperature H2O/CO2 gasification at temperatures up to 1000 °C, high-temperature plasma- and solar-assisted H2O/CO2 gasification at temperatures above 1200 °C, and an innovative gasification technology applying ultra-superheated steam (USS) with temperatures above 2000 °C obtained by pulsed or continuous gaseous detonations. Analysis shows that in terms of such characteristics as the carbon conversion efficiency (CCE), tar and char content, and the content of harmful by-products the plasma and detonation USS gasification technologies are most promising. However, as compared with plasma gasification, detonation USS gasification does not need enormous electric power with unnecessary and energy-consuming gas–plasma transition.
  • 1.6K
  • 28 Jan 2022
Topic Review
Tonti Diagram
The Tonti diagram, created by the Italian physicist and mathematician Enzo Tonti, is a diagram that classifies variables and equations of physical theories of classical and relativistic physics. The theories involved are: particle dynamics, analytical mechanics, mechanics of deformable solids, fluid mechanics, electromagnetism, gravitation, heat conduction, and irreversible thermodynamics. The classification stems from the observation that each physical variable has a well-defined association with a space and a time element, as shown in Fig. 1, which can be grasped from the corresponding global variable and from its measuring process.
  • 1.6K
  • 29 Sep 2022
Topic Review
Spin
Spin is an intrinsic form of angular momentum carried by elementary particles, and thus by composite particles (hadrons) and atomic nuclei. Spin is one of two types of angular momentum in quantum mechanics, the other being orbital angular momentum. The orbital angular momentum operator is the quantum-mechanical counterpart to the classical angular momentum of orbital revolution and appears when there is periodic structure to its wavefunction as the angle varies. For photons, spin is the quantum-mechanical counterpart of the polarization of light; for electrons, the spin has no classical counterpart. The existence of electron spin angular momentum is inferred from experiments, such as the Stern–Gerlach experiment, in which silver atoms were observed to possess two possible discrete angular momenta despite having no orbital angular momentum. The existence of the electron spin can also be inferred theoretically from the spin–statistics theorem and from the Pauli exclusion principle—and vice versa, given the particular spin of the electron, one may derive the Pauli exclusion principle. Spin is described mathematically as a vector for some particles such as photons, and as spinors and bispinors for other particles such as electrons. Spinors and bispinors behave similarly to vectors: they have definite magnitudes and change under rotations; however, they use an unconventional "direction". All elementary particles of a given kind have the same magnitude of spin angular momentum, though its direction may change. These are indicated by assigning the particle a spin quantum number. The SI unit of spin is the same as classical angular momentum (i.e., N·m·s, J·s, or kg·m2·s−1). In practice, spin is given as a dimensionless spin quantum number by dividing the spin angular momentum by the reduced Planck constant ħ, which has the same dimensions as angular momentum, although this is not the full computation of this value. Very often, the "spin quantum number" is simply called "spin". The fact that it is a quantum number is implicit.
  • 1.6K
  • 27 Oct 2022
Topic Review
Extinction
In astronomy, extinction is the absorption and scattering of electromagnetic radiation by dust and gas between an emitting astronomical object and the observer. Interstellar extinction was first documented as such in 1930 by Robert Julius Trumpler. However, its effects had been noted in 1847 by Friedrich Georg Wilhelm von Struve, and its effect on the colors of stars had been observed by a number of individuals who did not connect it with the general presence of galactic dust. For stars that lie near the plane of the Milky Way and are within a few thousand parsecs of the Earth, extinction in the visual band of frequencies (photometric system) is roughly 1.8 magnitudes per kiloparsec. For Earth-bound observers, extinction arises both from the interstellar medium (ISM) and the Earth's atmosphere; it may also arise from circumstellar dust around an observed object. Strong extinction in earth's atmosphere of some wavelength regions (such as X-ray, ultraviolet, and infrared) is overcome by the use of space-based observatories. Since blue light is much more strongly attenuated than red light, extinction causes objects to appear redder than expected, a phenomenon referred to as interstellar reddening.
  • 1.6K
  • 18 Oct 2022
Topic Review
List of Largest Stars
Below is a list of the largest stars currently known, ordered by radius. The unit of measurement used is the radius of the Sun (approximately 695,700 km; 432,300 mi). The angular diameters of stars can be measured directly using stellar interferometry. Other methods can use lunar occultations or from eclipsing binaries, which can be used to test indirect methods of finding stellar radii. Only a few useful supergiant stars can be occulted by the Moon, including Antares A (Alpha Scorpii A). Examples of eclipsing binaries are Epsilon Aurigae (Almaaz), VV Cephei, and V766 Centauri (HR 5171). Angular diameter measurements can be inconsistent because the boundary of the very tenuous atmosphere (opacity) differs depending on the wavelength of light in which the star is observed. Uncertainties remain with the membership and order of the list, especially when deriving various parameters used in calculations, such as stellar luminosity and effective temperature. Often stellar radii can only be expressed as an average or be within a large range of values. Values for stellar radii vary significantly in different sources and for different observation methods. All the sizes stated in this list have various inaccuracies and may be disputed. This list is still a work in progress and various parameters are extremely disputed.
  • 1.6K
  • 21 Nov 2022
Topic Review
Perovskite Semiconductor Field–Effect Transistors
Perovskite materials are considered as the most alluring successor to the conventional semiconductor materials to fabricate solar cells, light emitting diodes and electronic displays. However, the use of the perovskite semiconductors as a channel material in field effect transistors (FET) are much lower than expected due to the poor performance of the devices. Despite low attention, the perovskite FETs are used in widespread applications on account of their unique opto-electrical properties. 
  • 1.6K
  • 27 Jul 2022
Topic Review
A Message from Earth (2008)
A Message from Earth (AMFE) is a high-powered digital radio signal that was sent on 9 October 2008 towards Gliese 581c, a large terrestrial extrasolar planet orbiting within the Gliese 581 system. The signal is a digital time capsule containing 501 messages that were selected through a competition on the social networking site Bebo. The message was sent using the RT-70 radar telescope. The signal will reach the planet Gliese 581c in early 2029. More than half a million people including celebrities and politicians participated in the AMFE project, which was the world's first digital time capsule where the content was selected by the public. As of 1 February 2018, the message has traveled 62.43 trillion kilometers of the total 192 trillion kilometers, which is 33.5% of the distance to the Gliese 581 system. On 13 February 2015, scientists (including David Grinspoon, Seth Shostak, and David Brin) at an annual meeting of the American Association for the Advancement of Science, discussed Active SETI and whether transmitting a message to possible intelligent extraterrestrials in the Cosmos was a good idea; That same week, a statement was released, signed by many in the SETI community, that a "worldwide scientific, political and humanitarian discussion must occur before any message is sent". However neither Frank Drake, nor Seth Shostak signed this appeal. On 28 March 2015, a related essay with some different point of view was written by Seth Shostak and published in The New York Times .
  • 1.5K
  • 21 Oct 2022
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