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Topic Review
Pyrrolizidine Alkaloids
Pyrrolizidine alkaloids (PAs) are a group of natural compounds that are present in several plant families, among which the most predominant are Boraginaceae, Asteraceae, and Fabaceae, and are produced as a defense response against herbivores. PAs are known for their toxicity and for posing an elevated risk to human and animal health when consumed in large quantities over long periods of time.
  • 2.2K
  • 08 Feb 2024
Topic Review
Clean Ethanol from CO2 Reduction
Using renewable energy to convert CO2 to a clean fuel ethanol can not only reduce carbon emission by the utilization of CO2 as feedstock, but also store renewable energy as the widely used chemical and high-energy-density fuel, being considered as a perfect strategy to address current environment and energy issues. Developing efficient electrocatalysts, photocatalysts, and photoelectrocatalysts for CO2 reduction is the most crucial keystone for achieving this goal. Considerable progresses in CO2-based ethanol production have been made over the past decades. This review provides the general principles and summarizes the latest advancements of electrocatalytic, photocatalytic and photoelectrocatalytic CO2 conversion to ethanol. Furthermore, the main challenges and proposed future prospects are illustrated for further development of the clean fuel ethanol production.
  • 2.2K
  • 24 Nov 2020
Topic Review
Photocatalysis for Air Purification
Photocatalysis since a long time has been recognized  as a eco-technology to fight air pollution. It is focused  on the generation of reactive oxygen species (ROSs) under light on the surface of a photocatalytic material. It could be applied in different manners such as for the purification of industrial polluted air, photoconversion of toxic gas into valuable products, self-cleaning systems, photocatalytic filters, etc. However, it faces some technological issues limiting its wide application in real-world.  
  • 2.2K
  • 17 May 2021
Topic Review
MOFs for Mercury Detection
The advantages of metal organic frameworks (MOFs) are: existence of porosity to adsorb specific analyte, improved aqueous solubility, exceptional photophysical and chemical properties. MOFs are noted as exceptional candidates towards the detection and removal of specific analytes, particular for the detection/removal of environmental contaminants, such as heavy metal ions, toxic anions, hazardous gases, explosives, etc. Among heavy metal ions, mercury has been noted as a global hazard because of its high toxicity in the elemental (Hg0), divalent cationic (Hg2+), and methyl mercury (CH3Hg+) forms. To secure the environment and living organisms, many countries have imposed stringent regulations to monitor mercury at all costs. Regarding the detection/removal requirements of mercury, researchers have proposed and reported all kinds of MOFs-based luminescent/non-luminescent probes towards mercury.This review provides valuable information about the MOFs which have been engaged in detection and removal of elemental mercury and Hg2+ ions. Moreover, the involved mechanisms or adsorption isotherms related to sensors or removal studies are clarified for the readers. Finally, advantages and limitations of MOFs in mercury detection/removal are described together with future scopes.
  • 2.2K
  • 01 Jul 2021
Topic Review
Synthesis and Properties of Deep Eutectic Solvents
The use of deep eutectic solvents (DES) is on the rise worldwide because of the astounding properties they offer, such as simplicity of synthesis and utilization, low-cost, and environmental friendliness, which can, without a doubt, replace conventional solvents used in heaps.
  • 2.1K
  • 04 Jul 2023
Topic Review
Near- and Mird-Infrared Spectroscopy
Given the exquisite capability of direct, non-destructive label-free sensing of molecular transitions, IR spectroscopy has become a ubiquitous and versatile analytical tool. IR application scenarios range from industrial manufacturing processes, surveillance tasks and environmental monitoring to elaborate evaluation of (bio)medical samples. Given recent developments in associated fields, IR spectroscopic devices increasingly evolve into reliable and robust tools for quality control purposes, for rapid analysis within at-line, in-line or on-line processes, and even for bed-side monitoring of patient health indicators. 
  • 2.1K
  • 03 Aug 2022
Topic Review
Reactions of Nitrile Anions
Nitrile anions are the conjugate bases of alkyl nitriles. They undergo nucleophilic addition and substitution reactions with various electrophiles.
  • 2.1K
  • 24 Oct 2022
Topic Review
Chemistry and Occurrence of Tropane Alkaloids in Foods
Tropane alkaloids (TAs) are natural toxins produced by different plants, mainly from the Solanaceae family. 
  • 2.1K
  • 08 Feb 2022
Topic Review
Spectroscopic Techniques for Dental Materials
The presented work focuses on the application of spectroscopic methods, such as Infrared Spectroscopy (IR), Fourier Transform Infrared Spectroscopy (FT-IR), Raman spectroscopy, Ultraviolet and Visible Spectroscopy (UV-Vis), X-ray spectroscopy, and Mass Spectrometry (MS), which are widely employed in the investigation of the surface properties of dental materials.
  • 2.1K
  • 03 Jun 2021
Topic Review
Ammonium Nitrate Disasters
When heated, ammonium nitrate decomposes non-explosively into gases including oxygen; however, it can be induced to decompose explosively by detonation. Large stockpiles of the material can be a major fire risk due to their supporting oxidation, and may also detonate, as happened in the Texas City disaster of 1947, which led to major changes in the regulations for storage and handling. There are two major classes of incidents resulting in explosions: In the first case, the explosion happens by the mechanism of shock to detonation transition. The initiation happens by an explosive charge going off in the mass, by the detonation of a shell thrown into the mass, or by detonation of an explosive mixture in contact with the mass. The examples are Kriewald, Morgan, Oppau, Tessenderlo, and Traskwood. In the second case, the explosion results from a fire that spreads into the ammonium nitrate (AN) itself (Texas City, Brest, Tianjin), or to a mixture of an ammonium nitrate with a combustible material during the fire. The fire must be confined at least to a degree for successful transition from a fire to an explosion (a phenomenon known as "deflagration to detonation transition", or DDT). Pure, compact AN is stable and very difficult to initiate. However, there are numerous cases when even impure AN did not explode in a fire. Ammonium nitrate decomposes in temperatures above 210 °C (410 °F). Pure AN is stable and will stop decomposing once the heat source is removed, but when catalysts are present, the reaction can become self-sustaining (known as self-sustaining decomposition, or SSD). This is a well-known hazard with some types of NPK fertilizers and is responsible for the loss of several cargo ships.
  • 2.1K
  • 28 Oct 2022
Topic Review
Nucleophilic Substitution
A nucleophilic substitution is a class of chemical reactions in which an electron-rich chemical species (known as a nucleophile) replaces a functional group within another electron-deficient molecule (known as the electrophile). The molecule that contains the electrophile and the leaving functional group is called the substrate. The most general form of the reaction may be given as the following: The electron pair (:) from the nucleophile (Nuc) attacks the substrate (R-LG) and bonds with it. Simultaneously, the leaving group (LG) departs with an electron pair. The principal product in this case is R-Nuc. The nucleophile may be electrically neutral or negatively charged, whereas the substrate is typically neutral or positively charged. An example of nucleophilic substitution is the hydrolysis of an alkyl bromide, R-Br under basic conditions, where the attacking nucleophile is OH− and the leaving group is Br−. Nucleophilic substitution reactions are common in organic chemistry (especially introductory organic chemistry). Nucleophiles often attack a saturated aliphatic carbon. Less often, they may attack an aromatic or unsaturated carbon.
  • 2.0K
  • 26 Oct 2022
Topic Review
Extraction of Metal Ions with Metal–Organic Frameworks
Metal–organic frameworks (MOFs) are crystalline porous materials composed of metal ions or clusters coordinated with organic linkers. Due to their extraordinary properties such as high porosity with homogeneous and tunable in size pores/cages, as well as high thermal and chemical stability, MOFs have gained attention in diverse analytical applications. 
  • 2.0K
  • 23 Dec 2021
Topic Review
Cracking
In petrochemistry, petroleum geology and organic chemistry, cracking is the process whereby complex organic molecules such as kerogens or long-chain hydrocarbons are broken down into simpler molecules such as light hydrocarbons, by the breaking of carbon-carbon bonds in the precursors. The rate of cracking and the end products are strongly dependent on the temperature and presence of catalysts. Cracking is the breakdown of a large alkane into smaller, more useful alkenes. Simply put, hydrocarbon cracking is the process of breaking a long chain of hydrocarbons into short ones. This process requires high temperatures. More loosely, outside the field of petroleum chemistry, the term "cracking" is used to describe any type of splitting of molecules under the influence of heat, catalysts and solvents, such as in processes of destructive distillation or pyrolysis. Fluid catalytic cracking produces a high yield of petrol and LPG, while hydrocracking is a major source of jet fuel, diesel fuel, naphtha, and again yields LPG.
  • 2.0K
  • 27 Oct 2022
Topic Review
Coconut Palm
The price of traditional sources of nutrients used in animal feed rations is increasing steeply in developed countries due to their scarcity, high demand from humans for the same food items, and expensive costs of raw materials. Thus, one of the alternative sources is coconut parts or coconut as a whole fruit. Coconut is known as the ‘tree of abundance’, ‘tree of heaven’, and ‘tree of life’ owing to its numerous uses, becoming a very important tree in tropical areas for its provision of food, employment, and business opportunities to millions of people. Coconut contains a rich profile of macro and micronutrients that vary depending on the parts and how they are used. It is frequently chosen as an alternative source of protein and fiber. Its uses as an antibacterial agent, immunomodulant, and antioxidant further increase its importance. Using coconut oil in ruminant feed helps to minimize methane gas emissions by 18–30%, and to reduce dry matter intake up to 4.2 kg/d. The aquaculture sectors also use coconut palm as an alternative source because it significantly improves the digestion, growth, lipid metabolism, health, and antioxidative responses. However, coconut is not widely used in poultry diets although it has adequate amount of protein and carbohydrate due to anti-nutritional factors such cellulose (13%), galactomannan (61%), and mannan (26%). 
  • 1.9K
  • 31 Aug 2022
Topic Review
Gas Chromatography Olfactometry
Gas Chromatography-olfactometry (GC-O) is, by nature, the technique of choice for the screening of the molecules with odour (odorants) responsible for the aromatic sensory properties of any product. Ideally, the GC-O technique should provide an unbiased ranking of the odorants attending to the relevance of their contribution to those sensory properties. Such ranking is essential for further steps directed to the elucidation of the chemical nature of the odorants, for their quantification or for a basic understanding of the chemical bases of the aromatic perception in such product. The review discusses the different approaches for GC-O specifically applied to deciphering wine aroma. The critical difference between approaches is whether the ranking of odorants is carried out on an extract containing all the odorants present in the product or on an extract representative of the odorants contained in the vapour phases that cause the odour and flavor. Historically, most researchers have preferred techniques based on total extracts, because of sensitivity and operational issues. It is argued that the second alternative is more direct and can be more efficient, but it requires a good understanding of the factors affecting orthonasal olfaction, handling volatiles (purging, trapping, eluting, and separating) and about the sensory assessment of GC effluents.
  • 1.9K
  • 12 Jan 2021
Topic Review
Phase Change Materials
The energy sector is one of the fields of interest for different nations around the world. Due to the current fossil fuel crisis, the scientific community develops new energy-saving experiences to address this concern. Buildings are one of the elements of higher energy consumption, so the generation of knowledge and technological development may offer solutions to this energy demand, which are more than welcome. Phase change materials (PCMs) included in building elements such as wall panels, blocks, panels or coatings, for heating and cooling applications have been shown, when heating, to increase the heat storage capacity by absorbing heat as latent heat.
  • 1.9K
  • 29 Mar 2021
Topic Review
MS/MS-Based Molecular Networking
Natural products (NPs) have historically played a primary role in the discovery of small-molecule drugs. However, due to the advent of other methodologies and the drawbacks of NPs, the pharmaceutical industry has largely declined in interest regarding the screening of new drugs from NPs since 2000. There are many technical bottlenecks to quickly obtaining new bioactive NPs on a large scale, which has made NP-based drug discovery very time-consuming, and the first thorny problem faced by researchers is how to dereplicate NPs from crude extracts. Remarkably, with the rapid development of omics, analytical instrumentation, and artificial intelligence technology, in 2012, an efficient approach, known as tandem mass spectrometry (MS/MS)-based molecular networking (MN) analysis, was developed to avoid the rediscovery of known compounds from the complex natural mixtures. 
  • 1.9K
  • 03 Jan 2023
Topic Review
Indium-Mediated Allylation
Indium-Mediated Allylations (IMAs) are important chemical reactions for the formation of carbon–carbon bonds. This reaction has two steps: first, indium inserts itself between the carbon–halogen bond of an allyl halide, becoming the organoindium intermediate; second, this allyl indide intermediate reacts with an electrophile to synthesize one of a wide range of compounds, such as carbohydrates and antihelminthic drugs. This reaction is depicted in the scheme below: Although this reaction occurs in two steps, it is commonly done as a Barbier reaction where the indium, allyl halide, and electrophile are all mixed together in a one-pot process. Indium reacts more readily than other metals, such as Mg, Pb, Bi, or Zn and does not require a promoter or flammable organic solvent to drive the reaction. IMAs have advantages over other carbon bond forming reactions because of their ability to be carried out in water, which is cheap and environmentally friendly. Therefore, these reactions represent Green chemistry, providing a safer alternative to the very common Grignard reaction, performed with Mg. Reactions yield high stereo- and regio-selectivity with few by-products making it easy to purify the desired product.
  • 1.9K
  • 02 Dec 2022
Topic Review
Significance of Anthocyanins
Anthocyanins are widespread and biologically active water-soluble phenolic pigments responsible for a wide range of vivid colours, from red (acidic conditions) to purplish blue (basic conditions), present in fruits, vegetables, and coloured grains. 
  • 1.9K
  • 12 Dec 2022
Topic Review
Nanostructured Materials for VOC Sensing
Environmental pollution related to volatile organic compounds (VOCs) has become a global issue which attracts intensive work towards their controlling and monitoring. To this direction various regulations and research towards VOCs detection have been laid down and conducted by many countries. Distinct devices are proposed to monitor the VOCs pollution. Among them, chemiresistor devices comprised of inorganic-semiconducting materials with diverse nanostructures are most attractive because they are cost-effective and eco-friendly. These diverse nanostructured materials-based devices are usually made up of nanoparticles, nanowires/rods, nanocrystals, nanotubes, nanocages, nanocubes, nanocomposites, etc. They can be employed in monitoring the VOCs present in the reliable sources.
  • 1.9K
  • 04 Feb 2021
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