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Topic Review
Radiolabeled Gold Nanoseeds and Glioblastoma Multiforme
Glioblastoma multiforme (GBM), classified as a grade IV brain tumor, represents the most frequent brain tumor, accounting for approximately 12–15% of all intracranial neoplasms. Current therapeutic strategies for GBM rely on open surgery, chemotherapy and radiotherapy. Despite some progress in the past 30 years, the overall survival of patients with glioblastoma remains extremely poor. The average lifespan is approximately 15 months after diagnosis, with most patients experiencing tumor relapse and outgrowth within 7–10 months of initial radiation therapy.
  • 632
  • 14 Jan 2022
Topic Review
PSR J0737-3039
PSR J0737−3039 is the only known double pulsar. It consists of two neutron stars emitting electromagnetic waves in the radio wavelength in a relativistic binary system. The two pulsars are known as PSR J0737−3039A and PSR J0737−3039B. It was discovered in 2003 at Australia's Parkes Observatory by an international team led by the radio astronomer Marta Burgay during a high-latitude pulsar survey.
  • 632
  • 12 Oct 2022
Topic Review
Permanent Magnets and How They Dictated History
The most efficient electric motor is a permanent-magnet synchronous motor. Their efficiency makes them popular for drive motors, power steering, stop-start motors, and regenerative braking generators. These motors use permanent magnets based on rare-earth elements (REEs), in particular neodymium-iron-boron (Nd-Fe-B) and samarium-cobalt (Sm-Co), because of their high maximum energy product (BH)max (a measure of the magnet’s performance), which is needed for the high efficiency and the high resistance to demagnetization. But there are still some challenges and gaps in their performance and application.
  • 631
  • 27 Feb 2024
Topic Review
Cross Section
In physics, the cross section is a measure of the probability that a specific process will take place when some kind of radiant excitation (e.g. a particle beam, sound wave, light, or an X-ray) intersects a localized phenomenon (e.g. a particle or density fluctuation). For example, the Rutherford cross-section is a measure of probability that an alpha particle will be deflected by a given angle during an interaction with an atomic nucleus. Cross section is typically denoted σ (sigma) and is expressed in units of area, more specifically in barns. In a way, it can be thought of as the size of the object that the excitation must hit in order for the process to occur, but more exactly, it is a parameter of a stochastic process. In classical physics, this probability often converges to a deterministic proportion of excitation energy involved in the process, so that, for example, with light scattering off of a particle, the cross section specifies the amount of optical power scattered from light of a given irradiance (power per area). It is important to note that although the cross section has the same units as area, the cross section may not necessarily correspond to the actual physical size of the target given by other forms of measurement. It is not uncommon for the actual cross-sectional area of a scattering object to be much larger or smaller than the cross section relative to some physical process. For example, plasmonic nanoparticles can have light scattering cross sections for particular frequencies that are much larger than their actual cross-sectional areas. When two discrete particles interact in classical physics, their mutual cross section is the area transverse to their relative motion within which they must meet in order to scatter from each other. If the particles are hard inelastic spheres that interact only upon contact, their scattering cross section is related to their geometric size. If the particles interact through some action-at-a-distance force, such as electromagnetism or gravity, their scattering cross section is generally larger than their geometric size. When a cross section is specified as the differential limit of a function of some final-state variable, such as particle angle or energy, it is called a differential cross section (see detailed discussion below). When a cross section is integrated over all scattering angles (and possibly other variables), it is called a total cross section or integrated total cross section. For example, in Rayleigh scattering, the intensity scattered at the forward and backward angles is greater than the intensity scattered sideways, so the forward differential scattering cross section is greater than the perpendicular differential cross section, and by adding all of the infinitesimal cross sections over the whole range of angles with integral calculus, we can find the total cross section. Scattering cross sections may be defined in nuclear, atomic, and particle physics for collisions of accelerated beams of one type of particle with targets (either stationary or moving) of a second type of particle. The probability for any given reaction to occur is in proportion to its cross section. Thus, specifying the cross section for a given reaction is a proxy for stating the probability that a given scattering process will occur. The measured reaction rate of a given process depends strongly on experimental variables such as the density of the target material, the intensity of the beam, the detection efficiency of the apparatus, or the angle setting of the detection apparatus. However, these quantities can be factored away, allowing measurement of the underlying two-particle collisional cross section. Differential and total scattering cross sections are among the most important measurable quantities in nuclear, atomic, and particle physics.
  • 630
  • 18 Nov 2022
Topic Review
Colloidal Quantum Dots-Based Upconversion Devices
Colloidal quantum dots (CQD) have narrow emission linewidth and adjustable bandgap, so that CQD based infrared detectors can realize a widely tunable infrared spectral range. In addition, the luminescence spectrum of CQDs is extremely narrow, the color saturation and purity are high, and the optical stability is excellent, which can be obtained by solution procession. Therefore, CQDs-based LEDs (QLEDs) have excellent performances of a wide color gamut, long life, and low cost. For CQD baesd upconverters, except for the top electrode, the entire device can be prepared by solution method, which greatly simplifies the preparation of the device and make the upconverters are available for use in the fields of flexible devices.
  • 631
  • 31 Mar 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
Fluorescence-Based Sensors for High-Temperature Monitoring
Fiber-optic high-temperature sensors are gradually replacing traditional electronic sensors due to their small size, resistance to electromagnetic interference, remote detection, multiplexing, and distributed measurement advantages. 
  • 630
  • 17 Aug 2022
Topic Review
Rubens' Tube
A Rubens' tube, also known as a standing wave flame tube, or simply flame tube, is an antique physics apparatus for demonstrating acoustic standing waves in a tube. Invented by German physicist Heinrich Rubens in 1905, it graphically shows the relationship between sound waves and sound pressure, as a primitive oscilloscope. Today, it is used only occasionally, typically as a demonstration in physics education.
  • 630
  • 29 Nov 2022
Biography
Robert Bruce Lindsay
Robert Bruce Lindsay (1 January 1900 – 2 March 1985) was an United States physicist and physics professor, known for his prolific authorship of physics books in acoustics, and historical and philosophical analyses of physics.[1][2] R(obert) Bruce Lindsay's January 1, 1900 birth date hailed a new century. At the age of 20, he received both a BA and an MS in physics from Brown University. Bef
  • 630
  • 26 Dec 2022
Topic Review
Radiographic Imaging with Muons
Radiographic imaging with muons, also called Muography, is based on the measurement of the absorption of muons, generated by the interaction of cosmic rays with the earth’s atmosphere, in matter. Muons are elementary particles with high penetrating power, a characteristic that makes them capable of crossing bodies of dimensions of the order of hundreds of meters. 
  • 629
  • 08 Dec 2021
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