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Topic Review
Polyunsaturated Fat
Polyunsaturated fats are fats in which the constituent hydrocarbon chain possesses two or more carbon–carbon double bonds. Polyunsaturated fat can be found mostly in nuts, seeds, fish, seed oils, and oysters. "Unsaturated" refers to the fact that the molecules contain less than the maximum amount of hydrogen (if there were no double bonds). These materials exist as cis or trans isomers depending on the geometry of the double bond. Saturated fats have hydrocarbon chains which can be most readily aligned. The hydrocarbon chains in trans fats align more readily than those in cis fats, but less well than those in saturated fats. In general, this means that the melting points of fats increase from cis to trans unsaturated and then to saturated. See the section about the chemical structure of fats for more information. The position of the carbon-carbon double bonds in carboxylic acid chains in fats is designated by Greek letters. The carbon atom closest to the carboxyl group is the alpha carbon, the next carbon is the beta carbon and so on. In fatty acids the carbon atom of the methyl group at the end of the hydrocarbon chain is called the omega carbon because omega is the last letter of the Greek alphabet. Omega-3 fatty acids have a double bond three carbons away from the methyl carbon, whereas omega-6 fatty acids have a double bond six carbons away from the methyl carbon. The illustration below shows the omega-6 fatty acid, linoleic acid. While it is the nutritional aspects of polyunsaturated fats that are generally of greatest interest, these materials also have non-food applications. Drying oils, which polymerize on exposure to oxygen to form solid films, are polyunsaturated fats. The most common ones are linseed (flax seed) oil, tung oil, poppy seed oil, perilla oil, and walnut oil. These oils are used to make paints and varnishes.
  • 1.4K
  • 24 Oct 2022
Topic Review
Epidemic Dropsy
Epidemic dropsy is a form of edema of extremities due to poisoning by Argemone mexicana (Mexican prickly poppy). Epidemic dropsy is a clinical state resulting from use of edible oils adulterated with Argemone mexicana seed oil. Sanguinarine and dihydrosanguinarine are two major toxic alkaloids of argemone oil, which cause widespread capillary dilatation, proliferation and increased capillary permeability. When mustard oil is adulterated deliberately (as in most cases) or accidentally with argemone oil, proteinuria (specifically loss of albumin) occurs, with a resultant edema as would occur in nephrotic syndrome. Other major symptoms are bilateral pitting edema of extremities, headache, nausea, loose bowels, erythema, glaucoma and breathlessness. Leakage of the protein-rich plasma component into the extracellular compartment leads to the formation of edema. The haemodynamic consequences of this vascular dilatation and permeability lead to a state of relative hypovolemia with a constant stimulus for fluid and salt conservation by the kidneys. Illness begins with gastroenteric symptoms followed by cutaneous erythema and pigmentation. Respiratory symptoms such as cough, shortness of breath and orthopnoea, progressing to frank right-sided congestive cardiac failure, are seen. Mild to moderate anaemia, hypoproteinaemia, mild to moderate renal azotemia, retinal haemorrhages, and glaucoma are common manifestations. There is no specific therapy. Removal of the adulterated oil and symptomatic treatment of congestive cardiac failure and respiratory symptoms, along with administration of antioxidants and multivitamins, remain the mainstay of treatment. Epidemic dropsy occurs as an epidemic in places where use of mustard oil from the seeds of Brassica juncea, commonly known as Indian mustard, as a cooking medium is common.
  • 1.4K
  • 10 Nov 2022
Topic Review
Methods of Thermal Treatment of Radioactive Waste
Nuclear power is generated by a small amount of fuel, as related to other non-renewable energy sources. The volume of waste formed in this process is comparably small. Thermal treatment of waste is a term given to any treatment technology that involves high temperatures in the processing of the waste feedstock. All the thermal treatment methods used for normal waste have been applied to radioactive waste.  
  • 1.4K
  • 24 Jan 2022
Topic Review
Comprehensive Evaluation of Fermented Foods Based on Metabolomics
Fermentation is an important process that can provide new flavors and nutritional and functional foods, to deal with changing consumer preferences. Fermented foods have complex chemical components that can modulate unique qualitative properties. Consequently, monitoring the small molecular metabolites in fermented food is critical to clarify its qualitative properties and help deliver personalized nutrition. In recent years, the application of metabolomics to nutrition research of fermented foods has expanded. In this review, we examine the application of metabolomics technologies in food, with a primary focus on the different analytical approaches suitable for food metabolomics and discuss the advantages and disadvantages of these approaches. In addition, we summarize emerging studies applying metabolomics in the comprehensive analysis of the flavor, nutrition, function, and safety of fermented foods, as well as emphasize the applicability of metabolomics in characterizing the qualitative properties of fermented foods.
  • 1.4K
  • 29 Nov 2021
Topic Review
Chemical Safety
Chemicals as elements, compounds, mixtures, solutions and emulsions are very widely used and transported in the modern industrial society. Of necessity, they are also used in schools, universities and other training facilities to educate pupils in their safe use and handling and also are commonly used in domestic situations for cleaning, gardening and DIY. However, there are chemicals that should not mix or get in contact with others, as they can produce byproducts that may be toxic, carcinogenic, explosive etc, or can be dangerous themselves. To avoid disasters and mishaps, maintaining safety is considered paramount, especially by chemists. Chemical safety includes all those policies, procedures and practices designed to minimise the risk of exposure to potentially hazardous chemicals. This includes the risks of exposure to persons handling the chemicals, to the surrounding environment, and to the communities and ecosystems within that environment. The hazardous nature of many chemicals may be increased when mixed with other chemicals, heated or handled inappropriately. In a chemically safe environment, users are able to take appropriate actions in case of accidents although many incidents of exposure to chemical hazards occur outside of a controlled environments such as manufacturing plants or laboratories. It is estimated that 1.6 million human deaths occur each year from contact with hazardous chemicals. and that in 2016, 45 million disability-adjusted life-years were lost, a significant increase from 2012.
  • 1.4K
  • 21 Nov 2022
Topic Review
MXenes
Recent progress in the application of new 2D-materials—MXenes—in the design of biosensors, biofuel cells and bioelectronics is overviewed and some advances in this area are foreseen. Recent developments in the formation of a relatively new class of 2D metallically conducting MXenes opens a new avenue for the design of conducting composites with metallic conductivity and advanced sensing properties. Advantageous properties of MXenes suitable for biosensing applications are discussed. Frontiers and new insights in the area of application of MXenes in sensorics, biosensorics and in the design of some wearable electronic devices are outlined. Some disadvantages and challenges in the application of MXene based structures are critically discussed.
  • 1.4K
  • 08 Jan 2021
Topic Review
Catalysts Used in Pollutant Ozonation
The objective of this study was to summarize the results obtained in a wide research project carried out for more than 15 years on the catalytic activity of di erent catalysts (activated carbon, metal–carbon xerogels/aerogels, iron-doped silica xerogels, ruthenium metal complexes, reduced graphene oxide-metal oxide composites, and zeolites) in the photooxidation (by using UV or solar radiation) and ozonation of water pollutants, including herbicides, naphthalenesulfonic acids, sodium para-chlorobenzoate, nitroimidazoles, tetracyclines, parabens, sulfamethazine, sodium diatrizoate, cytarabine, and surfactants. All catalysts were synthesized and then texturally, chemically, and electronically characterized using numerous experimental techniques, including N2 and CO2 adsorption, mercury porosimetry, thermogravimetric analysis, X-ray di raction, Fourier-transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, di use reflectance UV–vis spectroscopy, photoluminescence analysis, and transmission electron microscopy. The behavior of these materials as photocatalysts and ozonation catalysts was related to their characteristics, and the catalytic mechanisms in these advanced oxidation processes were explored. Investigations were conducted into the e ects on pollutant degradation, total organic carbon reduction, and water toxicity of operational variables and the presence of di erent chemical species in ultrapure, surface, ground, and wastewaters. Finally, a review is provided of the most recent and relevant published studies on photocatalysis and catalyzed ozonation in water treatments using similar catalysts to those examined in our project.
  • 1.4K
  • 04 Jan 2021
Topic Review
High-Entropy Alloy
Cutting edge of high-entropy alloy superconductors from the perspective of materials research.
  • 1.4K
  • 26 Oct 2020
Topic Review
Cough Medicine
Cough medicines are medications used in those with coughing and related conditions. There is, however, no good evidence that over-the-counter cough medications reduce coughing. While they are used by 10% of American children in any given week, they are not recommended in Canada and the United States in children 6 years or younger because of lack of evidence showing effect and concerns of harm.
  • 1.4K
  • 21 Nov 2022
Topic Review
HMM and SBA Porous Materials
Mesoporous silicas have enjoyed great interest among scientists practically from the moment of their discovery thanks to their unique attractive properties. Many types of mesoporous silicas have been described in literature, the most thoroughly MCM-41 and SBA-15 ones. The methods of syntheses, characterization and use of mesoporous silicas from SBA (Santa Barbara Amorphous) and HMM (Hybrid Mesoporous Materials) groups are presented. The first group is represented by (i) SBA-1 of three-dimensional cubic structure and (ii) SBA-2 of three-dimensional combined hexagonal and cubic structures. The HMM group is represented by (i) HMM-1 of two-dimensional hexagonal structure and (ii) HMM-2 of three-dimensional structure. The paper provides comprehensive information on the above-mentioned silica materials available so far, also including the data for the silicas modified with metal ions or/and organic functional groups and examples of the materials applications.
  • 1.4K
  • 18 Mar 2021
Topic Review
MSMPs and MSMs
Magnetic shape memory polymers (MSMPs) belong to the group of shape memory materials, a group that can change their shape back to their “remembered” shape when they are exposed to a stimulus. MSMPs are essentially shape memory polymers whose shape memory effect is stimulated by heat. In the case of the MSMPs, magnetic particles are incorporated in the shape memory polymer. When the material is placed in an external alternating magnetic field, the magnetic particles heat up due to induction heating. The heated particles heat the shape memory polymer from the inside and when the activation temperature is reached, the shape memory effect is activated. Magnetic soft materials (MSMs) exist out of an elastomer with incorporated magnetic particles. The magnetic fields of these magnetic particles are set in specific magnetization patterns inside the elastomer during the fabrication process. When the magnetic soft material is placed inside an external static magnetic field, the magnetic fields of the magnetic particles align with the external magnetic field. This creates micro torques in the elastomer and pulls the elastomer matrix in a programmed shape.
  • 1.4K
  • 09 Oct 2021
Topic Review
Cation–pi Interaction
Cation–π interaction is a noncovalent molecular interaction between the face of an electron-rich π system (e.g. benzene, ethylene, acetylene) and an adjacent cation (e.g. Li+, Na+). This interaction is an example of noncovalent bonding between a monopole (cation) and a quadrupole (π system). Bonding energies are significant, with solution-phase values falling within the same order of magnitude as hydrogen bonds and salt bridges. Similar to these other non-covalent bonds, cation–π interactions play an important role in nature, particularly in protein structure, molecular recognition and enzyme catalysis. The effect has also been observed and put to use in synthetic systems.
  • 1.4K
  • 15 Nov 2022
Topic Review
Antimony/Bismuth Chalcohalides
Despite their comparable performance to commercial solar systems, lead-based perovskite (Pb-perovskite) solar cells exhibit limitations including Pb toxicity and instability for industrial applications. To address these issues, two types of Pb-free materials have been proposed as alternatives to Pb-perovskite: perovskite-based and non-perovskite-based materials. In this entry, we briefly introduce the crystal, energy band structures and theoretical insights of Sb/Bi chalcohalides as solar abosrbers.
  • 1.4K
  • 26 Nov 2020
Topic Review
Three-finger Toxin
Three-finger toxins (abbreviated 3FTx) are a protein superfamily of small toxin proteins found in the venom of snakes. Three-finger toxins are in turn members of a larger superfamily of three-finger protein domains which includes non-toxic proteins that share a similar protein fold. The group is named for its common structure consisting of three beta strand loops connected to a central core containing four conserved disulfide bonds. The 3FP protein domain has no enzymatic activity and is typically between 60-74 amino acid residues long. Despite their conserved structure, three-finger toxin proteins have a wide range of pharmacological effects. Most members of the family are neurotoxins that act on cholinergic intercellular signaling; the alpha-neurotoxin family interacts with muscle nicotinic acetylcholine receptors (nAChRs), the kappa-bungarotoxin family with neuronal nAChRs, and muscarinic toxins with muscarinic acetylcholine receptors (mAChRs).
  • 1.4K
  • 18 Oct 2022
Topic Review
Permafrost Carbon Cycle
The permafrost carbon cycle is a sub-cycle of the larger global carbon cycle. Permafrost is defined as subsurface material that remains below 0o C (32o F) for at least two consecutive years. Because permafrost soils remain frozen for long periods of time, they store large amounts of carbon and other nutrients within their frozen framework during that time. Permafrost represents a large carbon reservoir that is seldom considered when determining global terrestrial carbon reservoirs. Recent and ongoing scientific research however, is changing this view. The permafrost carbon cycle (Arctic Carbon Cycle) deals with the transfer of carbon from permafrost soils to terrestrial vegetation and microbes, to the atmosphere, back to vegetation, and finally back to permafrost soils through burial and sedimentation due to cryogenic processes. Some of this carbon is transferred to the ocean and other portions of the globe through the global carbon cycle. The cycle includes the exchange of carbon dioxide and methane between terrestrial components and the atmosphere, as well as the transfer of carbon between land and water as methane, dissolved organic carbon, dissolved inorganic carbon, particulate inorganic carbon and particulate organic carbon.
  • 1.4K
  • 04 Nov 2022
Topic Review
Mechanochemistry in Portugal
In Portugal, publications with mechanochemical methods date back to 2009, with the report on mechanochemical strategies for the synthesis of metallopharmaceuticals. Since then, mechanochemical applications have grown in Portugal, spanning several fields, mainly crystal engineering and supramolecular chemistry, catalysis, and organic and inorganic chemistry.
  • 1.4K
  • 24 Jan 2022
Topic Review
Organogold Chemistry
Organogold chemistry is the study of compounds containing gold–carbon bonds. They are studied in academic research, but have not received widespread use otherwise. The dominant oxidation states for organogold compounds are I with coordination number 2 and a linear molecular geometry and III with CN = 4 and a square planar molecular geometry. The first organogold compound discovered was gold(I) carbide Au2C2, which was first prepared in 1900.
  • 1.4K
  • 04 Nov 2022
Topic Review
Central Pontine Myelinolysis
Central pontine myelinolysis is a neurological condition involving severe damage to the myelin sheath of nerve cells in the pons (an area of the brainstem). It is predominately iatrogenic (treatment-induced), and is characterized by acute paralysis, dysphagia (difficulty swallowing), dysarthria (difficulty speaking), and other neurological symptoms. Central pontine myelinolysis was first described as a disorder in 1959. The original paper described four cases with fatal outcomes, and the findings on autopsy. The disease was described as a disease of alcoholics and malnutrition. ‘Central pontine’ indicated the site of the lesion and ‘myelinolysis’ was used to emphasise that myelin was affected. The authors intentionally avoided the term ‘demyelination’ to describe the condition, in order to differentiate this condition from multiple sclerosis and other neuroinflammatory disorders. Since this original description, demyelination in other areas of the central nervous system associated with osmotic stress has been described outside the pons (extrapontine). Osmotic demyelination syndrome is the term used for both central pontine myelinolysis and extrapontine myelinolysis. Central pontine myelinolysis, and osmotic demyelination syndrome, present most commonly as a complication of treatment of patients with profound hyponatremia (low sodium), which can result from a varied spectrum of conditions, based on different mechanisms. It occurs as a consequence of a rapid rise in serum tonicity following treatment in individuals with chronic, severe hyponatremia who have made intracellular adaptations to the prevailing hypotonicity.
  • 1.3K
  • 28 Oct 2022
Topic Review
Deep Eutectic Solvents and Rare Earth Elements
The boosted interest in the use of rare earth elements (REEs) in modern technologies had also increase the necessity of their recovery from various sources, including raw materials and wastes. Though Hydrometallurgy plays a key role in these recovery processes, some drawbacks (apparent or not) of these processes (including the use of aggressive mineral acids, harmful extractants and diluents, etc.), had led to the development of a more environmental friendship subclass named Solvometallurgy, in which non-aqueous solvents substituted to the aqueous media of the hydrometallurgical processing. Together to ionic liquids (ILs), the non-aqueous solvents chosen for these usages are the chemicals known as Deep Eutectic Solvents (DEEs). The utilization of DEEs included the leaching of REEs from the different sources containing them, and also in the separation-purification steps necessary for the yielding of these elements, normally as oxides or salts, in the most purified form. 
  • 1.3K
  • 15 Apr 2024
Topic Review
Microfluidics to Study Membrane Filtration
Membrane filtration processes are best known for their application in the water, oil, and gas sectors, but also in food production they play an eminent role. Filtration processes are known to suffer from a decrease in efficiency in time due to e.g., particle deposition, also known as fouling and pore blocking. Although these processes are not very well understood at a small scale, smart engineering approaches have been used to keep membrane processes running. Microfluidic devices have been increasingly applied to study membrane filtration processes and accommodate observation and understanding of the filtration process at different scales, from nanometer to millimeter and more. In combination with microscopes and high-speed imaging, microfluidic devices allow real time observation of filtration processes.
  • 1.3K
  • 24 Nov 2020
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