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Topic Review
Impact of Nanostructured Silicon on Thermoelectric Performance
Nanostructured materials remarkably improve the overall properties of thermoelectric devices, mainly due to the increase in the surface-to-volume ratio. This behavior is attributed to an increased number of scattered phonons at the interfaces and boundaries of the nanostructures. Among many other materials, nanostructured Si was used to expand the power generation compared to bulk crystalline Si, which leads to a reduction in thermal conductivity. However, the use of nanostructured Si leads to a reduction in the electrical conductivity due to the formation of low dimensional features in the heavily doped Si regions. Accordingly, the fabrication of hybrid nanostructures based on nanostructured Si and other different nanostructured materials constitutes another strategy to combine a reduction in the thermal conductivity while keeping the good electrical conduction properties. 
  • 494
  • 08 Aug 2022
Topic Review
Near- and Mird-Infrared Spectroscopy
Given the exquisite capability of direct, non-destructive label-free sensing of molecular transitions, IR spectroscopy has become a ubiquitous and versatile analytical tool. IR application scenarios range from industrial manufacturing processes, surveillance tasks and environmental monitoring to elaborate evaluation of (bio)medical samples. Given recent developments in associated fields, IR spectroscopic devices increasingly evolve into reliable and robust tools for quality control purposes, for rapid analysis within at-line, in-line or on-line processes, and even for bed-side monitoring of patient health indicators. 
  • 1.1K
  • 03 Aug 2022
Topic Review
Solid and Liquid Oxygen under Ultrahigh Magnetic Fields
Oxygen is a unique molecule that possesses a spin quantum number S=1. In the condensed phases of oxygen, the delicate balance between the antiferromagnetic interaction and van der Waals force results in the various phases with different crystal structures. By applying ultrahigh magnetic fields, the antiferromagnetic coupling between O2 molecules breaks, and novel high-field phase (θ phase) appears. Since oxygen is an important element for various (bio-)chemical reactions, the reorientation of O2 molecules could be an attractive mechanism for contrlling the reactivity.
  • 563
  • 01 Aug 2022
Topic Review
Development of Thin Film Blackbody Radiation Source
In developing and calibrating cryogenic receivers in the terahertz and sub-terahertz frequency range, illumination from an ideal source (blackbody, BB) with exactly known power spectral density is required. An electrically heated blackbody radiation source comprising thin metal film on a dielectric substrate and an integrating cavity was designed, fabricated, and experimentally studied at frequencies from 75 to 500 GHz.
  • 630
  • 28 Jul 2022
Topic Review
Current Status of The Celestial Reference Frame
The International Celestial Reference Frame (ICRF) is based on the currently accepted International Celestial Reference System (ICRS) and forms the basis for all positional astronomy in the radio domain. The first three generations of this frame have been built from high precision Very Long Baseline Interferometry (VLBI) astrometric measurements of positions of extragalactic radio sources (quasars and other radio-loud Active Galactic Nuclei, AGN), with each successive realization of the ICRF becoming more precise. VLBI angular position accuracy has now improved to near the 100 micro-arcsecond (μas) level. Catalogues of positions of extragalactic radio sources with the highest precision, such as the ICRF, are crucial to many applications, such as determining the Earth’s orientation in space, providing calibrator sources for astronomy, studying the motion of tectonic plates, and in spacecraft navigation. The ICRF also contributes towards the realization of a Global Geodetic Reference Frame (GGRF) for sustainable development, a resolution adopted by the United Nations in 2015.
  • 548
  • 28 Jul 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
Applications of Thermal Plasma Waste Treatment
Non-thermal as well as thermal plasmas are used for the processing of materials and waste. Thermal (hot) plasmas are characterized by their high energy density and by the equal temperatures of the electrons and the heavy particles, i.e., thermal plasmas are in local thermodynamic equilibrium. Non-thermal plasmas (also called cold plasmas), on the other hand, are non-equilibrium ionized gases, which are characterized by lower energy densities and by the large difference between the electron temperature and the temperature of the heavy particles.
  • 910
  • 25 Jul 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. 
  • 919
  • 22 Jul 2022
Topic Review
Magnetic Ag-Integrated Photocatalysts in Water Treatment
One of the great dangers facing humanity is the depletion of natural resources. For water specifically, the problem of shortage is all but gone. In 1960, only 9% of the world’s population was facing chronic water shortage issues, while nearly 50% of the global population has to manage moderate shortage, with around 10% of that population facing almost complete lack of water. Many measures have been employed to balance this ever-increasing threat, such as irrigated areas, groundwater utilization and reservoir storage, as this increase in water shortage does not only affect agriculture but human health itself as well and can even increase risks of diseases. The need for low-cost water treatment is especially evident in countries such as Pakistan, where the increased dependency on severely threatening contaminated water (by ~80% of the population) necessitates methods such as low-cost water filters for increased availability of affordable drinking water throughout the country. A magnetic/silver composite combines the advantages of magnetic properties with those of plasmonic nanoparticles, and these composites are able to perform well under UV and visible light, are effective against pollutants and pathogenic bacteria and can be easily separated from a solution with a simple magnet.
  • 579
  • 19 Jul 2022
Topic Review
Peroxisomal β-Oxidation
It is not paradoxical that what has been overlooked tends to be of great importance. Peroxisomes, the widely distributed organelles in the body, play irreplaceable roles in cellular metabolism, especially in fatty acid oxidation (FAO) and the generation and elimination of reactive oxygen species (ROS).
  • 4.7K
  • 15 Jul 2022
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