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Topic Review
Optical Fiber Biochemical Sensors Based on Graphene
Graphene, a novel form of the hexagonal honeycomb two-dimensional carbon-based structural material with a zero-band gap and ultra-high specific surface area, has unique optoelectronic capabilities, promising a suitable basis for its application in the field of optical fiber sensing. Graphene optical fiber sensing has also been a hotspot in cross-research in biology, materials, medicine, and micro-nano devices in recent years, owing to prospective benefits, such as high sensitivity, small size, and strong anti-electromagnetic interference capability and so on. 
  • 859
  • 20 Jun 2022
Topic Review
Mechanistic Organic Photochemistry
Some chemical reactions take place by the action of light. These are called, "photochemical reactions", or "photolysis". Mechanistic organic photochemistry is the aspect of organic photochemistry which seeks to explain the mechanisms of organic photochemical reactions. The absorption of ultraviolet light by organic molecules often leads to reactions. In the earliest days, sunlight was employed, while in more modern times ultraviolet lamps are employed. Organic photochemistry has proven to be a very useful synthetic tool. Complex organic products can be obtained simply. Over the last century and earlier an immense number of photochemical reactions have been uncovered. In modern times the field is quite well understood and is used in organic synthesis and industrially. The utility of organic photochemistry has arisen only by virtue of the available mechanistic treatment; reactions which appear unlikely in ground-state understanding become understandable and accessible in terms of electronic excited-state consideration.
  • 858
  • 17 Nov 2022
Topic Review
The PRESAGE Radiochromic Polymer Dosimeter
Advances in radiotherapy technology and techniques have allowed a highly conformal radiation to be delivered to the tumor target inside the body for cancer treatment. A three-dimensional (3D) dosimetry system is required to verify the accuracy of the complex treatment delivery. A 3D dosimeter based on the radiochromic response of a polymer towards ionising radiation has been introduced as the PRESAGE dosimeter. The polyurethane dosimeter matrix is combined with a leuco-dye and a free radical initiator, whose colour changes in proportion to the radiation dose. PRESAGE overcomes the limitations of its predecessors, the Fricke gel and the polymer gel dosimeters, which are challenging to fabricate and read out, sensitive to oxygen, and sensitive to diffusion. The formulation of PRESAGE shows a delicate balance between the number of radical initiators, metal compounds, and catalysts to achieve stability, optimal sensitivity, and water equivalency. 
  • 857
  • 22 Jul 2022
Topic Review
Entrance Length
In fluid dynamics, the entrance length is the distance a flow travels after entering a pipe before the flow becomes fully developed. Entrance length refers to the length of the entry region, the area following the pipe entrance where effects originating from the interior wall of the pipe propagate into the flow as an expanding boundary layer. When the boundary layer expands to fill the entire pipe, the developing flow becomes a fully developed flow, where flow characteristics no longer change with increased distance along the pipe. Many different entrance lengths exist to describe a variety of flow conditions. Hydrodynamic entrance length describes the formation of a velocity profile caused by viscous forces propagating from the pipe wall. Thermal entrance length describes the formation of a temperature profile. Awareness of entrance length may be necessary for the effective placement of instrumentation, such as fluid flow meters.
  • 857
  • 17 Oct 2022
Topic Review
Strangeness Production
Strangeness production is a signature and a diagnostic tool of quark–gluon plasma (or QGP) formation and properties. Unlike up and down quarks, from which everyday matter is made, strange quarks are formed in pair-production processes in collisions between constituents of the plasma. The dominant mechanism of production involves gluons only present when matter has become a quark–gluon plasma. When quark–gluon plasma disassembles into hadrons in a breakup process, the high availability of strange antiquarks helps to produce antimatter containing multiple strange quarks, which is otherwise rarely made. Similar considerations are at present made for the heavier charm flavor, which is made at the beginning of the collision process in the first interactions and is only abundant in the high-energy environments of CERN's Large Hadron Collider.
  • 856
  • 02 Dec 2022
Topic Review
Wavefront shaping concepts in OCT
Optical coherence tomography (OCT) enables three-dimensional imaging with resolution on the micrometer scale. The technique relies on the time-of-flight gated detection of light scattered from a sample and has received enormous interest in applications as versatile as non-destructive testing, metrology and non-invasive medical diagnostics. However, in strongly scattering media such as biological tissue, the penetration depth and imaging resolution are limited. Combining OCT imaging with wavefront shaping approaches significantly leverages the capabilities of the technique by controlling the scattered light field through manipulation of the field incident on the sample.
  • 854
  • 24 Dec 2020
Topic Review
Low Power Cusped Field Thruster
The cusped field thruster is a novel concept of electric propulsion devicewith the advantages of an extremely large thrust throttle ability (more than three orders of magnitude), low complexity, strong robustness and a long lifetime (more than 18,750 h). A cusped field magnetic field is formed in the channel by arranging quasi-periodic permanent magnets around the discharge channel.
  • 854
  • 28 Jul 2021
Topic Review
Solar Energy Conversion
Solar energy conversion describes technologies devoted to the transformation of solar energy to other (useful) forms of energy, including electricity, fuel, and heat. It covers light-harvesting technologies including traditional semiconductor photovoltaic devices (PVs), emerging photovoltaics, solar fuel generation via electrolysis, artificial photosynthesis, and related forms of photocatalysis directed at the generation of energy rich molecules. Fundamental electro-optical aspects in several emerging solar energy conversion technologies for generation of both electricity (photovoltaics) and solar fuels constitute an active area of current research.
  • 853
  • 19 Oct 2022
Biography
Günter Nimtz
Günter Nimtz (born 22 September 1936) is a German physicist, working at the 2nd Physics Institute at the University of Cologne in Germany. He has investigated narrow-gap semiconductors and liquid crystals and was engaged in several interdisciplinary studies on the effect of non-ionizing electromagnetic radiation in biological systems. His international reputation mainly results from experiments
  • 851
  • 29 Dec 2022
Topic Review
Liquid Crystal Waveguide Structures
Liquid crystal materials can be used to make either a core, in which light beams can be confined, or a cladding of optical waveguides.
  • 851
  • 02 Nov 2021
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