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Topic Review
Alumina Nanocomposite
Although pure titanium and titanium alloys are highly biosafe, there are many reports of patients with metal allergies caused by titanium. In addition, it was used as a prosthesis in the oral cavity, such as the black triangle in which the gingiva turns black due to the gradual elution and deposition of metal ions in the titanium alloy, and the black margin generated when the gingiva lowers and the metal part is exposed. In some cases, there are also aesthetic issues.Zirconia is attracting attention as an alternative material to such problems. Zirconia is excellent in aesthetics and biosafety, and with the progress of CAD / CAM technology, its application in various applications has begun, and yttria-stable zirconia has already been put into practical use as a dental implant.However, yttria-stabilized zirconia, which is generally used as dental ceramics, is more brittle than metals such as titanium and has less bending properties, so there is a risk of breakage. Although yttria-stable zirconia is harder than metal, it is brittle once it is distorted, and it is a technical issue that the strength decreases when low-temperature deterioration occurs due to phase transition due to long-term use in a wet state such as in the oral cavity.On the other hand, ceria-stable zirconia-alumina composite ceramics have the same hardness as yttria-stable zirconia, and also have extremely excellent toughness, eliminating the weaknesses of ceramics such as brittleness and low-temperature deterioration in wet conditions. It is attracting attention as a ceramic.This ceramic has a nano-composite structure in which nano-sized alumina particles are incorporated into ceria-stable zirconia particles, and nano-sized ceria-stable zirconia particles are inter-dispersed in the alumina particles. , Nano zirconia). Nano zirconia has a high bending strength equivalent to that of general zirconia, and has a very high fracture toughness of 3 to 5 times that of general zirconia. Due to its high toughness as well as its strength, it is expected to be used in implan.However, nanozirconia is inferior in bone formation after implant placement compared to titanium, so surface modification is required for application as a medical device. So far, surface modification of nanozirconia has been investigated by concentrated alkali treatment, etc., but it is equivalent to titanium or titanium alloy, although it has a certain effect on the initial attachment of bone marrow cells or the induction of differentiation into hard tissue. Biocompatibility has not been achieved.
  • 747
  • 26 Oct 2020
Topic Review
Aluminium Oxide
The promising techniques of obtaining AO adsorbents are discussed, namely the technique of thermal activation in the mode of pneumatic transport with gibbsite by heated air (TCA Gb) and the technique of thermal activation of gibbsite in centrifugal flash reactors (CTA Gb).
  • 658
  • 17 Mar 2021
Topic Review
Aluminium(I)
In chemistry, aluminium(I) refers to monovalent aluminium (+1 oxidation state) in both ionic and covalent bonds. Along with aluminium(II), it is an extremely unstable form of aluminium. While late Group 3 elements such as thallium and indium prefer the +1 oxidation state, aluminium(I) is rare. Unlike late Group XIII elements, aluminium does not experience the inert pair effect, a phenomenon where valence s electrons are poorly shielded from nuclear charge due to the presence of filled d and f orbitals. As such, aluminium (III) ([math]\ce{ Al^3+ }[/math]) is the much more common oxidation state for aluminium. Aluminium(I) compounds are both prone to disproportionation and difficult to prepare. At standard conditions, they readily oxidize to the aluminium(III) form.
  • 599
  • 14 Nov 2022
Topic Review
Alzheimer's disease
Alzheimer's disease (AD) is a multifactorial disease and the most common neurodegenerative disorder affecting the elderly population world-wide.The used medications treat the symptoms of AD, but without any delay on the progression of the disease. Curcumin presented favorable effects on AD. In the last decade curcumin analogues and derivatives have been synthesized in an attempt to optimize the beneficial properties of curcumin and improve its absorbance and  distribution per os as a therapeutic agent. Reviewing the bibliographical data of the last decade, information on the structures and / or chemical groups that are associated with specific action against AD, was gathered, derived from docking studies, (Q)SAR from vitro and in vivo tests. Phenolic hydroxyl groups might contribute to the anti-amyloidogenic activity. Phenyl methoxy groups seems to contribute to the suppression of Aβ42 and to the suppression of APP. Hydrophobic interactions revealed to be important. The presence of flexible moieties at the linker are crucial for the inhibition of Aβ aggregation. The inhibitory activity of derivatives is increased with the expansion of the aromatic rings. The keto-enol tautomer form offers as a new modification for the design of amyloid-binding agents. Taking the above under consideration  innovative design  and synthesis will lead to more potent and specific curcumin analogues and derivatives against AD.
  • 1.1K
  • 30 Oct 2020
Topic Review
Amadori Rearrangement Products
Flavor is one of the most important factors in attracting consumers and maximizing food quality, and the Maillard reaction (MR) is highly-involved in flavor formation. However, Maillard reaction products have a big drawback in their relatively low stability in thermal treatment and storage. Amadori rearrangement products (ARPs), MR intermediates, can alternatively act as potential flavor additives for their better stability and fresh flavor formation ability.
  • 1.9K
  • 18 Jan 2023
Topic Review
Amalgam
An amalgam is an alloy of mercury with another metal. It may be a liquid, a soft paste or a solid, depending upon the proportion of mercury. These alloys are formed through metallic bonding, with the electrostatic attractive force of the conduction electrons working to bind all the positively charged metal ions together into a crystal lattice structure. Almost all metals can form amalgams with mercury, the notable exceptions being iron, platinum, tungsten, and tantalum. Silver-mercury amalgams are important in dentistry, and gold-mercury amalgam is used in the extraction of gold from ore. Dentistry has used alloys of mercury with metals such as silver, copper, indium, tin and zinc.
  • 926
  • 31 Oct 2022
Topic Review
Amazonian Bacuri (Platonia insignis Mart.)
Bacuri (Platonia insignis Mart) is a species from the Clusiaceae genus. Its fruit pulp is commonly used in South America in several food products, such as beverages, ice cream and candies. Only the pulp of the fruit is used, and the peels and seeds are considered waste from these industries.
  • 1.2K
  • 29 Mar 2022
Topic Review
Ambient Mass Spectrometry Imaging and Its Applications
Ambient mass spectrometry imaging (AMSI) has attracted much attention in recent years. As a kind of unlabeled molecular imaging technique, AMSI can enable in situ visualization of a large number of compounds in biological tissue sections in ambient conditions. In this review, the developments of various AMSI techniques are discussed according to one-step and two-step ionization strategies. In addition, recent applications of AMSI for lipid and metabolite analysis (from 2016 to 2021) in disease diagnosis, animal model research, plant science, drug metabolism and toxicology research, etc., are summarized. Finally, further perspectives of AMSI in spatial resolution, sensitivity, quantitative ability, convenience and software development are proposed. 
  • 708
  • 29 Mar 2022
Topic Review
Amidoalkyl Naphthols: Bioactive Substances and Building Blocks
1-amidoalkyl-2-naphthol derivatives are of increasing interest due to their biological activities and further use in the preparation of other important bioactive molecules, such as aminoalkyl naphthols and oxazines.
  • 254
  • 16 Jun 2023
Topic Review
Amine Type in CO2 Separation
Efficient CO2 capture technologies such as absorption/adsorption of CO2 sorbents, cryogenic separation, and membrane separation, have been developed experimentally and industrially. Among them, membrane technology is attracting growing attention owing to its inherent advantages that include energy-efficiency, ease of operation and scale-up, and a small footprint.
  • 632
  • 27 Sep 2022
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