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Topic Review
Biological Functions of Nitric Oxide
Nitric oxide (nitrogen monoxide) is a molecule and chemical compound with chemical formula of NO. In mammals including humans, nitric oxide is a signaling molecule involved in several physiological and pathological processes. It is a powerful vasodilator with a half-life of a few seconds in the blood. Standard pharmaceuticals such as nitroglycerine and amyl nitrite are precursors to nitric oxide. Low levels of nitric oxide production are typically due to ischemic damage in the liver. As a consequence of its importance in neuroscience, physiology, and immunology, nitric oxide was proclaimed "Molecule of the Year" in 1992. Research into its function led to the 1998 Nobel Prize for elucidating the role of nitric oxide as a cardiovascular signalling molecule.
  • 2.5K
  • 04 Nov 2022
Topic Review
Polycrystalline Materials
Polycrystalline materials can be defined as the counterpart of single crystals. These latter  arise from solution crystallization by transfer of a solute from the liquid phase to the crystalline phase. Crystallization from melt originates instead crystallites or grains, that is regular crystalline regions  randomly oriented and separated one anoher by borders with geometric shapes, Polycrystalline materials are the result of a multiple nucleation process, whereas monocrystals are ideally obtainable by dipping a seed crystal into a supercooled melt.  Polycrystalline materials often consist of spherulites, i.e. crystalline aggregates growing with a rounded shape up to impingment with adjacent spherulites. The borders amongst spherulites and the size and the final shape of spherulites affect considerably the properties of polycrystalline materials.
  • 2.5K
  • 12 May 2021
Topic Review
Tissues to Implant Abutments
This entry is based on the fact that physical or biomechanical phenomena can cause biologic results. Implant-abutment connection structures determine the stability of soft tissue attachment to abutments. The bone responses to the strain that the stress is converted to, not the stress itself. Some implant-abutment materials and connection designs prevent the marginal bone loss by converting the stress to the strain stimulating bone apposition properly. These biomechanical interpretation of soft tissue seal and bone stimulation should be understood for the clinical long-term success of dental implants.
  • 2.5K
  • 27 Oct 2020
Topic Review
Five-Membered Heterocyclic Compounds
Heterocyclic compounds are a class of compounds of natural origin with favorable properties and hence have major pharmaceutical significance. They have an exceptional adroitness favoring their use as diverse smart biomimetics, in addition to possessing an active pharmacophore in a complex structure. This has made them an indispensable motif in the drug discovery field. Heterocyclic compounds are usually classified according to the ring size, type, and the number of heteroatoms present in the ring.
  • 2.5K
  • 16 Aug 2022
Topic Review
Ultra-High-Purity Aluminum
Properties of high-purity aluminum are the low magnetic permeability, the absence of low-temperature brittleness, as well as the increased strength and plasticity at low temperatures. These explain the classical application of high- to ultra-high-purity aluminum for the stabilization of superconductors running at cryogenic temperatures as low as −269 °C.
  • 2.5K
  • 01 Nov 2021
Topic Review
GaN(0001) Surfaces
Herein, the surface properties of gallium nitride (GaN) of the wurtzite form, (0001) oriented are presented. X-ray and UV photoelectron spectroscopies (XPS, UPS) were employed to show chemical and physical characters of the surface . Basic information about electronic structure of various doped GaN(0001) surfaces as well as surface Fermi level pinning are discussed.
  • 2.5K
  • 10 Feb 2021
Topic Review
Zone Refining
Zone refining is a technology of deeply purifying metals. Its essence is to use the difference in solubility of impurity elements in the solid and molten state of the main metal to precipitate the impurities or change the distribution of the impurity elements. It provides an effective and easy method for preparing high-purity metals. 
  • 2.5K
  • 18 May 2021
Topic Review
Semiconductor Gas Sensors
Semiconductor materials include metal oxides, conducting polymers, carbon nanotubes, and 2D materials. Metal oxides are most often the first choice due to their ease of fabrication, low cost, high sensitivity, and stability. Some of their disadvantages are low selectivity and high operating temperature. Conducting polymers have the advantage of a low operating temperature and can detect many organic vapors. They are flexible but affected by humidity. Carbon nanotubes are chemically and mechanically stable and are sensitive towards NO and NH3, but need dopants or modifications to sense other gases. Graphene, transition metal chalcogenides, boron nitride, transition metal carbides/nitrides, metal organic frameworks, and metal oxide nanosheets as 2D materials represent gas-sensing materials of the future, especially in medical devices, such as breath sensing.
  • 2.5K
  • 10 Dec 2020
Topic Review
Synthetic Applications of Lawesson’s Reagent in Organic Synthesis
Lawesson’s reagent (LR) is a well-known classic example of a compound with unique construction and unusual chemical behavior, with a wide range of applications in synthetic organic chemistry. Its main functions were rounded for the thionation of various carbonyl groups in the early days. Now its use can help the chemistry community to understand innovative ideas. These include constructing biologically valuable heterocycles, coupling reactions, and the thionation of natural compounds.
  • 2.5K
  • 27 Nov 2021
Topic Review
Seed Priming
Seed nano-priming is an efficient process that can change seed metabolism and signaling pathways, affecting not only germination and seedling establishment but also the entire plant lifecycle.
  • 2.5K
  • 13 Jan 2022
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