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Topic Review
Biorefinery of agroindustrial banana waste
Life cycle system of second-generation ethanol production from rachis of banana.
  • 1.6K
  • 27 Aug 2020
Topic Review
XPS Analysis of Carbon Materials
The surface chemistry of carbon materials is predominantly explored using x-ray photoelectron spectroscopy (XPS). However, many journal articles have critical failures in the published analysis which typically stems from an ill-informed approach to analyzing the spectroscopic data. The presented work presents a discussion on lineshapes and associated changes in the spectral envelope of predominantly graphitic materials, which together with the use of the D-parameter to verify levels of the graphitic content, using this information to highlight a simple and logical approach to strengthen confidence in the functionalization derived from the carbon core-level spectra.
  • 1.6K
  • 16 Jul 2021
Topic Review
A Review of Geometry, Construction and Modelling for Carbon Nanotori
After the discovery of circular formations of single walled carbon nanotubes called fullerene crop circles, their structure has become one of the most researched amongst carbon nanostructures due to their particular interesting physical properties. Several experiments and simulations have been conducted to understand these intriguing objects, including their formation and their hidden characteristics. It is scientifically conceivable that these crop circles, nowadays referred to as carbon nanotori, can be formed by experimentally bending carbon nanotubes into ring shaped structures or by connecting several sections of carbon nanotubes. Toroidal carbon nanotubes are likely to have many applications, especially in electricity and magnetism. In this review, geometry, construction, modelling and possible applications are discussed and the existing known analytical expressions, as obtained from the Lennard-Jones potential and the continuum approximation, for their interaction energies with other nanostructures are summarised.
  • 1.5K
  • 29 Oct 2020
Topic Review
Thallium
Thallium, as a pharmaceutical cosmetic product, is applied for facial hair removal and fungal infections of the scalp. Thallium acetate is currently used as a catalyst in organic synthesis in the oxidation of olefins and hydrocarbons, and in epoxidation and polymerization reactions. Detection of Tl is a challenging task because its concentration in environmental samples may be at a nanogram per gram level or lower.
  • 1.5K
  • 23 Nov 2021
Topic Review
Base
In chemistry, there are three definitions in common use of the word base, known as Arrhenius bases, Brønsted bases, and Lewis bases. All definitions agree that bases are substances which react with acids as originally proposed by G.-F. Rouelle in the mid-18th century. In 1884, Svante Arrhenius proposed that a base is a substance which dissociates in aqueous solution to form Hydroxide ions OH−. These ions can react with hydrogen ions (H+ according to Arrhenius) from the dissociation of acids to form water in an acid–base reaction. A base was therefore a metal hydroxide such as NaOH or Ca(OH)2. Such aqueous hydroxide solutions were also described by certain characteristic properties. They are slippery to the touch, can taste bitter and change the color of pH indicators (e.g., turn red litmus paper blue). In water, by altering the autoionization equilibrium, bases yield solutions in which the hydrogen ion activity is lower than it is in pure water, i.e., the water has a pH higher than 7.0 at standard conditions. A soluble base is called an alkali if it contains and releases OH− ions quantitatively. Metal oxides, hydroxides, and especially alkoxides are basic, and conjugate bases of weak acids are weak bases. Bases and acids are seen as chemical opposites because the effect of an acid is to increase the hydronium (H3O+) concentration in water, whereas bases reduce this concentration. A reaction between aqueous solutions of an acid and a base is called neutralization, producing a solution of water and a salt in which the salt separates into its component ions. If the aqueous solution is saturated with a given salt solute, any additional such salt precipitates out of the solution. In the more general Brønsted–Lowry acid–base theory (1923), a base is a substance that can accept hydrogen cations (H+)—otherwise known as protons. This does include aqueous hydroxides since OH− does react with H+ to form water, so that Arrhenius bases are a subset of Brønsted bases. However, there are also other Brønsted bases which accept protons, such as aqueous solutions of ammonia (NH3) or its organic derivatives (amines). These bases do not contain a hydroxide ion but nevertheless react with water, resulting in an increase in the concentration of hydroxide ion. Also, some non-aqueous solvents contain Brønsted bases which react with solvated protons. For example in liquid ammonia, NH2− is the basic ion species which accepts protons from NH4+, the acidic species in this solvent. G. N. Lewis realized that water, ammonia, and other bases can form a bond with a proton due to the unshared pair of electrons that the bases possess. In the Lewis theory, a base is an electron pair donor which can share a pair of electrons with an electron acceptor which is described as a Lewis acid. The Lewis theory is more general than the Brønsted model because the Lewis acid is not necessarily a proton, but can be another molecule (or ion) with a vacant low-lying orbital which can accept a pair of electrons. One notable example is boron trifluoride (BF3). Some other definitions of both bases and acids have been proposed in the past, but are not commonly used today.
  • 1.5K
  • 29 Sep 2022
Topic Review
Heterocyclic Anticancer Compounds
Heterocyclic organic compounds are designated as integral components on a wide array of structures with both pharmacological and biological importance. They constitute a large cohort of structures with immense importance in the life sciences. 
  • 1.5K
  • 29 Mar 2022
Topic Review
Medical Applications of Hybrid Hydrogels Containing Natural Polymers
Hybrid hydrogels definition is still debatable. They are defined either as a complex composed  chemically or physically cross-linking structures, or it refers to systems combining different polymers and/or with nanoparticles, such as plasmonic, magnetic, and carbonaceous nanoparticles, among others, or they are constituted by chemically, functionally, and morphologically distinct features from at least two different classes of molecules, which can include biologically active polymers as polysaccharides and/or proteins, peptides, or nano/microstructures, interconnected via physical or chemical means.
  • 1.5K
  • 29 Mar 2022
Topic Review Peer Reviewed
Tautomerism of β-Diketones and β-Thioxoketones
The present overview concentrates on recent developments of tautomerism of β-diketones and β-thioxoketones, both in solution and in the solid state. In particular, the latter has been a matter of debate and unresolved problems. Measurements of 13C, 17O, and 2H chemical shifts have been used. Deuterium isotope effects on chemical shifts are proposed as a tool in the study of this problem. Photoconversion of β-diketones and β-thioxoketones are discussed in detail, and the incorporation of β-diketones into molecules with fluorescent properties is assessed. Finally, docking studies of β-diketones are scrutinized with an emphasis on correct tautomeric structures and knowledge about barriers to interconversion of tautomers.
  • 1.5K
  • 10 Mar 2023
Topic Review
Ceramic-Polymer Composite Membranes
Ceramics and polymers are two main candidate materials for membranes, where the majority has been made of polymeric materials, due to the low cost, easy processing, and tunability in pore configurations. In contrast, ceramic membranes have much better performance, extra-long service life, mechanical robustness, and high thermal and chemical stabilities, and they have also been applied in gas, petrochemical, food-beverage, and pharmaceutical industries, where most of polymeric membranes cannot perform properly. 
  • 1.5K
  • 22 Jun 2021
Topic Review
Cyclodextrins Modified/Coated Metal–Organic Frameworks
The introduction of cyclodextrins (CDs) via noncovalent bonds could improve various physiochemical properties of metal-organic frameworks (MOFs) and expand their practical applications in aqueous solutions, for example, biocompatible CDs could improve the solubility of CDs-coated MOFs as a hybrid delivery system. And external-stimuli responsiveness of CDs-coated MOFs is key for widening applications in controlled drug releasing system, catalysis, detection, extraction and separation.
  • 1.5K
  • 27 Oct 2020
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