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Topic Review
High Performance Polymer Composites
Summarize data on the structure, mechanical and tribological properties, and wear patterns of composites based on high-performance polymers (HPPs) intended for use in friction units. The three key sections, divided according to the tribological contact schemes regardless of the polymer matrix. In the second part, the analysis of composites is carried out in point contacts. The third section is devoted to the results of studies of HPP-based composites in linear ones. The fourth section summarizes information on flat contacts. Particular attention is paid to the formation of transfer films (TFs) in the contacts and their influence on the tribological patterns of the studied rubbing materials.
  • 1.1K
  • 16 Mar 2022
Topic Review
Chitosan and its Derivatives
Chitosan (CS) is a hemi-synthetic cationic linear polysaccharide produced by the deacetylation of chitin. CS is non-toxic, highly biocompatible, and biodegradable, and it has a low immunogenicity. Additionally, CS has inherent antibacterial properties and a mucoadhesive character and can disrupt epithelial tight junctions, thus acting as a permeability enhancer. As such, CS and its derivatives are well-suited for the challenging field of ocular drug delivery. In the present review article, we will discuss the properties of CS that contribute to its successful application in ocular delivery before reviewing the latest advances in the use of CS for the development of novel ophthalmic delivery systems. Colloidal nanocarriers (nanoparticles, micelles, liposomes) will be presented, followed by CS gels and lenses and ocular inserts. Finally, instances of CS coatings, aiming at conferring mucoadhesiveness to other matrixes, will be presented.
  • 1.1K
  • 31 Jul 2020
Topic Review
Raman and Fluorescence Enhancement Approaches
The search for novel platforms and metamaterials for the enhancement of optical and particularly Raman signals is still an objective since optical techniques offer affordable, noninvasive methods with high spatial resolution and penetration depth adequate to detect and image a large variety of systems, from 2D materials to molecules in complex media and tissues. Plasmonic platforms produce the most efficient enhancement through the surface enhanced Raman scattering (SERS) process, allowing to reach single molecule detection, and are the most studied ones. The formation of hot-spots is clue to obtain the maximum enhancements but has counterparts regarding reproducibility and homogeneity, which are required for quantification and imaging. Other light enhancement mechanisms such as resonant and interference Raman scattering, as well as their combinations with SERS are being explored. Fluorescence enhancement platforms and strategies, so important for bio-detection and imaging, are also being developed. Graphene and related materials have an important role to play in the design of the platforms.    
  • 1.1K
  • 16 Mar 2021
Topic Review
Cannabinoid Receptor Antagonist
A cannabinoid receptor antagonist, also known simply as a cannabinoid antagonist or as an anticannabinoid, is a type of cannabinoidergic drug that binds to cannabinoid receptors (CBR) and prevents their activation by endocannabinoids. They include antagonists, inverse agonists, and antibodies of CBRs. The discovery of the endocannabinoid system led to the development of CB1 receptor antagonists. The first CBR inverse agonist, rimonabant, was described in 1994. Rimonabant blocks the CB1 receptor selectively and has been shown to decrease food intake and regulate body-weight gain. The prevalence of obesity worldwide is increasing dramatically and has a great impact on public health. The lack of efficient and well-tolerated drugs to cure obesity has led to an increased interest in research and development of CBR antagonists. Cannabidiol (CBD), a naturally occurring cannabinoid, is a non-competitive CB1/CB2 receptor antagonist. And Δ9-tetrahydrocannabivarin (THCV), a naturally occurring cannabinoid, modulate the effects of THC via direct blockade of cannabinoid CB1 receptors, thus behaving like first-generation CB1 receptor inverse agonists, such as rimonabant. CBD is a very low-affinity CB1 ligand, that can nevertheless affect CB1 receptor activity in vivo in an indirect manner, while THCV is a high-affinity CB1 receptor ligand and potent antagonist in vitro and yet only occasionally produces effects in vivo resulting from CB1 receptor antagonism. THCV has also high affinity for CB2 receptors and signals as a partial agonist, differing from both CBD and rimonabant.
  • 1.1K
  • 08 Nov 2022
Topic Review
Ethiopian Anticancer Plants
This entry provides an overview on the active phytochemical constituents of twenty-seven medicinal plants that are traditionally used to manage cancer in Ethiopia. It is compiled and discusses the potential anticancer, antiproliferative, and cytotoxic agents based on the types of secondary metabolites, such as terpenoids, phenolic compounds, alkaloids, steroids, and lignans. Among the anticancer secondary metabolites reported in this review, only few have been isolated from plants that are originated and collected in Ethiopia, and the majority of compounds are reported from plants belonging to different areas of the world. Thus, based on the available bioactivity reports, extensive and more elaborate ethnopharmacology-based bioassay-guided studies have to be conducted on selected traditionally claimed Ethiopian anticancer plants, which inherited from a unique and diverse landscape, with the aim of opening a way forward to conduct anticancer drug discovery program.
  • 1.1K
  • 21 Oct 2020
Topic Review
Cobalt–Chromium Dental Alloys
Co–Cr dental alloys consist of Co, Cr and also other metals (e.g., gallium, iron, molybdenum, nickel, ruthenium, tungsten). Since the 1990s, regulations have emerged to protect European patients and also monitor recent scientific knowledge. The use of metals and, therefore, dental alloys has been highly regulated by directives and regulations. Europe has, therefore, developed a regulatory package to protect all players involved in alloys, whether they are metal producers, manufacturers of alloys and medical devices, healthcare professionals and patients. Objective information is provided about Co–Cr dental alloys, with regard to both the latest toxicological data and regulatory developments from 2020–2025. The release of metal ions and the problem of wear particles are also discussed. With the recent change of regulatory status of Co, it is necessary to know the many repercussions (economic, technical etc.) of their use precisely in order to then allow actors to modify their daily work. The legislative changes also bring the need to propose new alternatives to Co-Cr dental alloys.  
  • 1.1K
  • 21 Jan 2021
Topic Review
MDCs for Next-generation Optical Coatings
In Dielectric/Metal/Dielectric (DMD) type multilayer coating applications, it is very important to achieve simultaneously highly stable and durable optical properties together with accurate control over the apparent color properties of coated glass, in both reflection and transmission. In this encyclopedia entry, we report on the properties of RF magnetron co-sputtered metal-dielectric composite (MDC) material systems of interest for forward-looking applications in the areas of thin-film nanomaterials and optical coatings.
  • 1.1K
  • 02 Nov 2020
Topic Review
Fatigue Crack Growth
The development of crack patterns is a serious problem affecting the durability of orthopedic implants and the prognosis of patients. This issue has gained considerable attention in the medical community in recent years. This literature focuses on the five primary aspects relevant to the evaluation of the surface cracking patterns, i.e., inappropriate use, design flaws, inconsistent elastic modulus, allergic reaction, poor compatibility, and anti-corrosiveness. The hope is that increased understanding will open doors to optimize fabrication for biomedical applications. The latest technological issues and potential capabilities of implants that combine absorbable materials and shape memory alloys are also discussed. 
  • 1.1K
  • 18 Jan 2021
Topic Review
Cement Asphalt Emulsion Mortar Composites
CA mortar (sometimes abbreviated to CAM) is one of the major construction materials for slab ballastless track in high-speed railways; it is an intermediate layer flung within the space between the track slab and the trackbed (as depicted in) of CRTS I and CRTS II. Cement and asphalt mortar is an organic–inorganic composite material primarily composed of asphalt emulsion, cement, sand, water, and other chemical admixtures. This composite material possesses fascinating properties that are different from both concrete and asphalt material alone because it couples the strength of cement as well as the flexibility of asphalt material.
  • 1.1K
  • 03 Nov 2021
Topic Review
Mechanism of Self-Healing Hydrogels
Polymeric hydrogels have drawn considerable attention as a biomedical material for their unique mechanical and chemical properties, which are very similar to natural tissues. Among the conventional hydrogel materials, self-healing hydrogels (SHH) are showing their promise in biomedical applications in tissue engineering, wound healing, and drug delivery. Additionally, their responses can be controlled via external stimuli (e.g., pH, temperature, pressure, or radiation). Identifying a suitable combination of viscous and elastic materials, lipophilicity and biocompatibility are crucial challenges in the development of SHH. Furthermore, the trade-off relation between the healing performance and the mechanical toughness also limits their real-time applications. Additionally, short-term and long-term effects of many SHH in the in vivo model are yet to be reported.
  • 1.1K
  • 09 Nov 2022
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