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Topic Review
C,C- and C,N-Chelated Organocopper Compounds
Copper-catalyzed and organocopper-involved reactions are of great significance in organic synthesis. To have a deep understanding of the reaction mechanisms, the structural characterizations of organocopper intermediates become indispensable. Meanwhile, the structure-function relationship of organocopper compounds could advance the rational design and development of new Cu-based reactions and organocopper reagents. Compared to the mono-carbonic ligand, the C,N- and C,C-bidentate ligands better stabilize unstable organocopper compounds. Bidentate ligands can chelate to the same copper atom via η2-mode, forming a mono-cupra-cyclic compounds with at least one acute C-Cu-C angle. When the bidentate ligands bind to two copper atoms via η1-mode at each coordinating site, the bimetallic macrocyclic compounds will form nearly linear C-Cu-C angles. The anionic coordinating sites of the bidentate ligand can also bridge two metals via μ2-mode, forming organocopper aggregates with Cu-Cu interactions and organocuprates with contact ion pair structures. The reaction chemistry of some selected organocopper compounds is highlighted, showing their unique structure–reactivity relationships.
  • 743
  • 08 Oct 2021
Topic Review
Aptamer-Bound Nanomaterials in Cancer Therapy
Cancer is still a major disease that threatens human life. Although traditional cancer treatment methods are widely used, they still have many disadvantages. Aptamers, owing to their small size, low toxicity, good specificity, and excellent biocompatibility, have been widely applied in biomedical areas. Therefore, the combination of nanomaterials with aptamers offers a new method for cancer treatment.
  • 629
  • 08 Oct 2021
Topic Review
Polymer Composites Carbonaceous Materials Coated
Carbon fibre reinforced polymer composites have high mechanical properties that make them exemplary engineered materials to carry loads and stresses. Coupling fibre and matrix together require good understanding of not only fibre morphology but also matrix rheology. One way of having a strongly coupled fibre and matrix interface is to size the reinforcing fibres by means of micro- or nanocarbon materials coating on the fibre surface. Common coating materials used are carbon nanotubes and nanofibres and graphene, and more recently carbon black (colloidal particles of virtually pure elemental carbon) and graphite. There are several chemical, thermal, and electrochemical processes that are used for coating the carbonous materials onto a carbon fibre surface. Sizing of fibres provides higher interfacial adhesion between fibre and matrix and allows better fibre wetting by the surrounded matrix material.
  • 691
  • 08 Oct 2021
Topic Review
Composite Material Applications
Composite materials are composed of two or more different materials having considerably different physical and/or chemical characteristics that, when merged, produce a material with attributes that differ from the separate elements. Composite materials are extensively utilized in the automobile, construction, transportation, aerospace, and renewable energy applications due to their durability, high strength, great quality, minimal maintenance, and low weight.
  • 4.3K
  • 08 Oct 2021
Topic Review
Agave By-Products
Throughout this review, we have highlighted the current potential of agave by-products as low-cost and natural materials with several applications as biofuels, materials for nanocomposites, and functional ingredients. Among the methods used for by-products processing, US and microwaves are promising and eco-friendly methods for the efficient saccharification and increased digestibility of agave, that can eventually replace chemical processing, reducing waste generation. In this regard, future studies are required concerning accessible, low-cost, and more efficient technologies as a more attractive way for the industry to make a sustainable utilization of this by-product.
  • 707
  • 08 Oct 2021
Topic Review
Cancer-Nano-Interaction
In the targeted therapy, nanoparticles (NPs) with specific properties, nanomedicine, are designed to specifically transport therapeutic agents to tumor sites and to release under controlled conditions. This strategy could potentially overcome the limitations of conventional methods and improve the cancer treatment outcomes by distinguishing malignant cells from non-malignant cells and selectively kill malignant cells. Bio-distribution, biocompatibility, biodegradability, and systemic clearance are the general challenges of using NPs in the targeted therapy. An effective NP-based drug delivery system should predict and control the fate of NPs in the biological environment. To develop and achieve a sound and efficient NPs-based system, we need to enhance our understanding of the nano-bio-interaction (NBI) happening between nanomaterials and a complex heterogeneous biological environment. At the cellular level, the NBI occurs at the interface of NPs surface and cell membrane. The interaction behavior of NPs is highly dependent on the physical and chemical properties of NPs.
  • 515
  • 08 Oct 2021
Topic Review
Biomass-Derived Furfurals, Furanic Biofuels
The concomitant hydrolysis and dehydration of biomass-derived cellulose and hemicellulose to furfural (FUR) and 5-(hydroxymethyl)furfural (HMF) under acid catalysis allows a dramatic reduction in the oxygen content of the parent sugar molecules with a 100% carbon economy. However, most applications of FUR or HMF necessitate synthetic modifications. Catalytic hydrogenation and hydrogenolysis have been recognized as efficient strategies for the selective deoxygenation and energy densification of biomass-derived furfurals generating water as the sole byproduct.
  • 622
  • 08 Oct 2021
Topic Review
Dapsone Imine Derivatives
Dapsone (DDS) is an antibacterial drug with well-known antioxidant properties. However, the antioxidant behavior of its derivatives has not been well explored. In the present work, the antioxidant activity of 10 dapsone derivatives 4-substituted was determined by an evaluation in two in vitro models (DPPH radical scavenging assay and ferric reducing antioxidant power). These imine derivatives 1–10 were obtained through condensation between DDS and the corresponding aromatic aldehydes 4-substuited. Three derivatives presented better results than DDS in the determination of DPPH (2, 9, and 10). Likewise, we have three compounds with better reducing activity than dapsone (4, 9, and 10). In order to be more insight, the redox process, a conceptual DFT analysis was carried out. Molecular descriptors such as electronic distribution, the total charge accepting/donating capacity (I/A), and the partial charge accepting/donating capacity (ω+/ω−) were calculated to analyze the relative donor-acceptor capacity through employing a donor acceptor map (DAM). The DFT calculation allowed us to establish a relationship between GAPHOMO-LUMO and DAM with the observed antioxidant effects. According to the results, we concluded that compounds 2 and 3 have the lowest Ra values, representing a good antioxidant behavior observed experimentally in DPPH radical capturing. On the other hand, derivatives 4, 9, and 10 display the best reducing capacity activity with the highest ω− and Rd values. Consequently, we propose these compounds as the best antireductants in our DDS imine derivative series.
  • 1.2K
  • 08 Oct 2021
Topic Review
Entropy-Enthalpy Compensations Fold Proteins
 we reveal a protein-folding mechanism based on the entropy-enthalpy compensations that initially driven by laterally hydrophobic collapse among the side-chains of adjacent residues in the sequences of unfolded protein chains. This hydrophobic collapse promotes the formation of the H-bonds within the polypeptide backbone structures through the entropy-enthalpy compensation mechanism, enabling secondary structures and tertiary structures to fold reproducibly following explicit physical folding codes and forces. The temperature dependence of protein folding is thus attributed to the environment dependence of the conformational Gibbs free energy equation. The folding codes and forces in the amino acid sequence that dictate the formation of β-strands and α-helices can be deciphered with great accuracy through evaluation of the hydrophobic interactions among neighboring side-chains of an unfolded polypeptide from a β-strand-like thermodynamic metastable state. The folding of protein quaternary structures is found to be guided by the entropy-enthalpy compensations in between the docking sites of protein subunits according to the Gibbs free energy equation that is verified by bioinformatics analyses of a dozen structures of dimers. Protein folding is therefore guided by multistage entropy-enthalpy compensations of the system of polypeptide chains and water molecules under the solution conditions. 
  • 959
  • 08 Oct 2021
Topic Review
Yucca Saponins. Bioactivity and analytical methods
Yucca is one of the main sources of steroidal saponins, hence different extracts are commercialized for use as surfactant additives by beverage, animal feed, cosmetics or agricultural products. For a deeper understanding of the potential of the saponins that can be found in this genus, an exhaustive review of the structural characteristics, bioactivities and analytical methods that can be used with these compounds has been carried out, since there are no recent reviews on the matter. Thus, a total of 108 saponins from eight species of the genus Yucca have been described.
  • 870
  • 08 Oct 2021
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