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Topic Review
Hydroxyapatite Nanoparticles in Drug Delivery
A biomaterial is a synthetic material used to replace part of a living system or a material meant to be in contact with living tissue. In this sense, biomaterials can be categorized into polymers, liposomes, micelles, dendrimers, and calcium phosphate (CaP) nanoparticles, where each will show a different type of bioactivity. Hydroxyapatite (HAP) has been the gold standard in the biomedical field due to its composition and similarity to human bone. HAP nanoparticles have been used as vehicles for delivery due to their affinity to DNA, proteins, several drugs, and proper release activity.
  • 889
  • 02 Nov 2021
Topic Review
Spectrophotometric Methods for Measurement of Antioxidant Activity
The antioxidant potential can be measured by various assays with specific mechanisms of action, including hydrogen atom transfer, single electron transfer, and targeted scavenging activities. Understanding the chemistry of mechanisms, advantages, and limitations of the methods is critical for the proper selection of techniques for the valid assessment of antioxidant activity in specific samples or conditions. There are various analytical techniques available for determining the antioxidant activity of biological samples, including food and plant extracts. The different methods are categorized into three main groups, such as spectrometry, chromatography, and electrochemistry techniques. Among these assays, spectrophotometric methods are considered the most common analytical technique for the determination of the antioxidant potential due to their sensitivity, rapidness, low cost, and reproducibility.
  • 889
  • 28 Nov 2022
Topic Review
Sensing Tyrosinase Activity
Tyrosinase (TYR, E.C. 1.14.18.1), a critical enzyme participating in melanogenesis, catalyzes the first two steps in melanin biosynthesis including the ortho-hydroxylation of L-tyrosine and the oxidation of L-DOPA. Previous pharmacological investigations have revealed that an abnormal level of TYR is tightly associated with various dermatoses, including albinism, age spots, and malignant melanoma.
  • 889
  • 08 Sep 2021
Topic Review
Nanostructures Based on Cobalt Oxide
Cobalt oxide (Co3O4) is known to follow the spinel structure as (Co2+)[Co23+O4. The high spin Co2+occupies the interstitial sites of tetrahedral (8a) whereas low spin Co3+are known to occupy the interstitial sites of octahedral (16d) of the close-packed face-centered cubic lattice of CoO.Co2O3. The p-type conductivity of the material (CoO.Co2O3) is known to originate from the vacancies of Co in the crystal lattices or/and excess oxygen at interstitial sites.  Furthermore, 1D nanostructures of Co3O4  have been investigated over the past decades as an active material for chemical analytes detection owing to its superior catalytic effect together with its excellent stability.
  • 889
  • 06 Aug 2021
Topic Review
Additive Manufacturing of Ti-Based Alloys
TiAl-based intermetallic alloys have come to the fore as the preferred alloys for high-temperature applications. Conventional methods (casting, forging, sheet forming, extrusion, etc.) have been applied to produce TiAl intermetallic alloys. However, the inherent limitations of conventional methods do not permit the production of the TiAl alloys with intricate geometries. Additive manufacturing technologies such as electron beam melting (EBM) and laser powder bed fusion (LPBF), have been used to produce TiAl alloys with complex geometries. EBM technology can produce crack-free TiAl components but lacks geometrical accuracy. LPBF technology has great geometrical precision that could be used to produce TiAl alloys with tailored complex geometries, but cannot produce crack-free TiAl components. To satisfy the current industrial requirement of producingcrack-free TiAl alloys with tailored geometries, the paper proposes a new heating model for the LPBF manufacturing process. The model could maintain even temperature between the solidified and subsequent layers, reducing temperature gradients (residual stress), which could eliminate crack formation. The new conceptualized model also opens a window for in-situ heat treatment of the built samples to obtain the desired TiAl (gama-phase) and Ti3Al (α2-phase) intermetallic phases for high-temperature operations. In situ heat treatment would also improve the homogeneity of the microstructure of LPBF manufactured samples.
  • 888
  • 26 Aug 2021
Topic Review
Fluoro-Modified Surface
The original fluoro-modified polyurethane encapsulated process was designed to rapidly fabricate low flow-resistance surfaces on the zinc substrate. For the further enhancement of the drag-reduction effect, chemical etching was introduced during the fabrication process, and its surface morphology, wettability, and flow-resistance properties in a microchannel were also studied in this paper. It is indicated that the zinc substrate with micro-nano scale roughness obtained by Cu2+ assisted nitric acid etching was super hydrophilic. However, after the etched zinc substrate encapsulated with fluoro-polyurethane, the superhydrophobic wettability can be obtained. As this newly fabricated surface being applied into the microchannel, it was found that with the increase of Reynolds number, the drag reduction rate of the superhydrophobic surface remained basically unchanged at 4.0 % compared with the original zinc substrate. Furthermore, the prepared superhydrophobic surfaces exhibited outstanding reliability in most liquids, and such chemical-etching methodology were capable to be commercialized in the piping as well as the coating industry.
  • 888
  • 30 Oct 2020
Topic Review
Smart Biogenic Packaging
Smart biogenic packaging is an innovative, swiftly emerging concept, where sustainability and real-time monitoring of food are coupled together, ensuring safe and healthy food, alongside commercial and ecological prosperity. Smart biogenic packaging integrates active and intelligent packaging solutions to provide consumers with more reliable information about food product conditions. It also generates a shielding effect for the food by incorporating active substances such as antimicrobial agents in a biogenic polymer matrix.
  • 888
  • 15 Apr 2022
Topic Review
Preparation of Organosiloxane Telechelics by Anionic Ring-opening Polymerization
Polydimethylsiloxanes (PDMS) telechelics are important both in industry and in academic research. They are used both in the free state and as part of copolymers and cross-linked materials. The most important, practically used, and well-studied method for the preparation of such PDMS is diorganosiloxane ring-opening polymerization (ROP) in the presence of nucleophilic or electrophilic initiators. Anionic ring opening polymerization (AROP) under the action of various nucleophilic reagents is widely used for the synthesis of high molecular weight polydiorganosiloxane telechelics with various organic surroundings of the siloxane chain. In the process of cyclosiloxane opening and chain growth, side processes may occur: depolymerization due to the breaking of the linear chain by the active center (backbiting reaction) with the formation of low molecular weight cyclic products, and chain transfer reaction, in which the terminal active site attacks the siloxane bond of another polymer chain, leading to a redistribution of macromolecules, which is also called equilibration
  • 888
  • 24 Jun 2022
Topic Review
Solid-State Polymer Electrolytes for Lithium Batteries
In all-solid-state rechargeable lithium batteries, the solid-state electrolyte is located between the cathode and the anode, acting as an electrolyte and a separator, so the performance of the solid-state electrolyte is crucial to the performance of the entire battery.
  • 887
  • 23 Nov 2022
Topic Review
Graphene Quantum Dots (GQDs)
Graphene quantum dots (GQDs) are small fragments of graphene with lateral dimensions less than 100 nm, with properties deriving from both graphene and carbon points.
  • 887
  • 11 May 2021
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