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Topic Review
Ultrasonic Spray Pyrolysis
In the field of synthesis and processing of noble metal nanoparticles, the study of the bottom-up method, called Ultrasonic Spray Pyrolysis (USP), is becoming increasingly important. This review analyses briefly the features of USP, to underline the physical, chemical and technological characteristics for producing nanoparticles and nanoparticle composites with Au and Ag. The main aim is to understand USP parameters, which are responsible for nanoparticle formation. There are two nanoparticle formation mechanisms in USP: Droplet-To-Particle (DTP) and Gas-To-Particle (GTP). This review shows how the USP process is able to produce Au, Ag/TiO2, Au/TiO2, Au/Fe2O3 and Ag/(Y0.95 Eu0.05)2O3 nanoparticles, and presents the mechanisms of formation for a particular type of nanoparticle. Namely, the presented Au and Ag nanoparticles are intended for use in nanomedicine, sensing applications, electrochemical devices, and catalysis, in order to benefit from their properties, which cannot be achieved with identical bulk materials. The development of new noble metal nanoparticles with USP is a constant goal in Nanotechnology, with the objective to obtain increasingly predictable final properties of nanoparticles.
  • 2.7K
  • 14 Aug 2020
Topic Review
Ultrasonic dynamic mechanical analysis (UDMA) for polymer characterization
Ultrasonic wave propagation has been used for the high frequency dynamic mechanical analysis of polymers with the aim to monitor the changes of viscoelastic properties in polymers associated with glass transition, crystallization, physical or chemical gelation, crosslinking, and curing reactions.
  • 1.0K
  • 11 Jun 2020
Topic Review
Ultrafine-Grained Stainless Steels after Severe Plastic Deformation
Both mechanical properties and corrosion resistance of various stainless steels can be optimized owing to grain refinement decreasing the grain size down to hundreds of nanometers. The ultrafine-grained (UFG) microstructures can be obtained in ferritic and austenitic stainless steels by means of large strain deformation using severe plastic deformation (SPD) or conventional processing methods under conditions of cold to warm working. The UFG stainless steels are characterized by high strength. However, the strengthening by large strain deformation is accompanied by a substantial degradation of plasticity. Therefore, the UFG stainless steels are frequently subjected to recovery/recrystallization annealing to balance the strength and plasticity. The revealed relationships among a range of microstructural parameters open up a promising approach to clarify the mechanical behaviour of UFG stainless steels. Therefore, UFG stainless steels produced by large strain deformation have great potential for various applications as structural and functional materials.
  • 326
  • 10 Apr 2023
Topic Review
Ultrafast Phase Transitions in (001) Si
Researchers demonstrate an ultrafast (<0.1 ps) reversible phase transition in silicon (Si) under ultrafast pressure loading using molecular dynamics. Si changes its structure from cubic diamond to β-Sn on the shock-wave front. The phase transition occurs when the shock-wave pressure exceeds 11 GPa. 
  • 350
  • 04 Mar 2022
Topic Review
Ultracentrifugation Techniques for Nanoparticles Ordering
A centrifugal field can provide an external force for the ordering of nanoparticles. Especially with the knowledge from in-situ characterization by analytical (ultra)centrifugation, nanoparticle ordering can be rationally realized in preparative (ultra)centrifugation. This study summarizes the work back to the 1990s, where intuitive use of centrifugation was achieved for the fabrication of colloidal crystals to the very recent work where analytical (ultra)centrifugation is employed to tailor-make concentration gradients for advanced materials. This review is divided into three main parts. In the introduction part, the history of ordering microbeads in gravity is discussed and with the size of particles reduced to nanometers, a centrifugal field is necessary. In the next part, the research on the ordering of nanoparticles in analytical and preparative centrifugation in recent decades is described. In the last part, the applications of the functional materials, fabricated from centrifugation-induced nanoparticle superstructures are briefly discussed.
  • 692
  • 05 Feb 2021
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
Ultra-Heat Treatment on Milk Proteins
Milk contains approximately 3.5% by weight protein, which is a highly complex system. This milk protein is usually divided into two main fractions based on their solubility nature. Casein proteins are about 75% to 80% of the total protein in the milk and precipitate at pH 4.6 at 20 °C, while 20% of the protein remains in the serum.
  • 2.4K
  • 07 Oct 2021
Topic Review
Tyrocidine
Tyrocidine is a mixture of cyclic decapeptides produced by the bacteria Bacillus brevis found in soil. It can be composed of 4 different amino acid sequences, giving tyrocidine A–D. Tyrocidine is the major constituent of tyrothricin, which also contains gramicidin. Tyrocidine was the first commercially available antibiotic, but has been found to be toxic toward human blood and reproductive cells. The function of tyrocidine within its host B. brevis is thought to be regulation of sporulation. Tyrocidines A, B, and C are cyclic decapeptides. The biosynthesis of tyrocidine involves three enzymes. Parts of its sequence are identical to gramicidin S.
  • 553
  • 15 Nov 2022
Topic Review
Types of Synthetic Materials in Bone Grafts
To decide which material is most appropriate for a given procedure, it is necessary not only to have a good understanding of the biological function (osteogenesis, osteoinduction, and osteoconduction) of each material but also to consider the patient condition, as this is an essential criterion for the incorporation of any bone graft. Bone grafts are evolving and undergoing innumerable changes and there has long been talk of synthetic bone grafts and bone substitutes to the detriment of autologous, allogeneic, or even xenogeneic grafts.
  • 292
  • 19 Jun 2023
Topic Review
Types of Supercapacitors
Supercapacitors are mainly divided into three types: electrical double layer (EDL) capacitors, pseudocapacitors, and hybrid supercapacitors based on their energy storage mechanisms. 
  • 608
  • 27 Apr 2023
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