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Topic Review
Structure-Based Drug Design
The functionality of a protein is dependent upon its structure, and structure-based drug design (SBDD) relies on the 3D structural information of the target protein, which can be acquired from experimental methods, such as X-ray crystallography, NMR spectroscopy and cryo-electron microscopy (cryo-EM). The aim of SBDD is to predict the Gibbs free energy of binding (ΔGbind), the binding affinity of ligands to the binding site, by simulating the interactions between them.
  • 2.9K
  • 09 Jan 2023
Topic Review
Compounds of Zinc
Compounds of zinc are chemical compounds containing the element zinc which is a member of the group 12 of the periodic table. The oxidation state of most compounds is the group oxidation state of +2. Zinc may be classified as a post-transition main group element with zinc(II). Zinc compounds are noteworthy for their nondescript behavior, they are generally colorless (unlike other elements with the oxidation number +2, which are usually white), do not readily engage in redox reactions, and generally adopt symmetrical structures.
  • 2.9K
  • 25 Nov 2022
Topic Review
Zeolitic Imidazolate Framework
Zeolitic imidazolate frameworks (ZIFs) are a class of metal-organic frameworks that are topologically isomorphic with zeolites. ZIFs are composed of tetrahedrally-coordinated transition metal ions (e.g. Fe, Co, Cu, Zn) connected by imidazolate linkers. Since the metal-imidazole-metal angle is similar to the 145° Si-O-Si angle in zeolites, ZIFs have zeolite-like topologies. As of 2010, 105 ZIF topologies have been reported in the literature. Due to their robust porosity, resistance to thermal changes, and chemical stability, ZIF’s are being investigated for applications such as carbon capture.
  • 2.9K
  • 25 Oct 2022
Topic Review
Radical
In chemistry, a free radical is an atom, molecule, or ion that has at least one unpaired valence electron. With some exceptions, these unpaired electrons make radicals highly chemically reactive. Many radicals spontaneously dimerize. Most organic radicals have short lifetimes. A notable example of a radical is the hydroxyl radical (HO·), a molecule that has one unpaired electron on the oxygen atom. Two other examples are triplet oxygen and triplet carbene (꞉CH2) which have two unpaired electrons. Radicals may be generated in a number of ways, but typical methods involve redox reactions. Ionizing radiation, heat, electrical discharges, and electrolysis are known to produce radicals. Radicals are intermediates in many chemical reactions, more so than is apparent from the balanced equations. Radicals are important in combustion, atmospheric chemistry, polymerization, plasma chemistry, biochemistry, and many other chemical processes. A majority of natural products are generated by radical-generating enzymes. In living organisms, the radicals superoxide and nitric oxide and their reaction products regulate many processes, such as control of vascular tone and thus blood pressure. They also play a key role in the intermediary metabolism of various biological compounds. Such radicals can even be messengers in a process dubbed redox signaling. A radical may be trapped within a solvent cage or be otherwise bound.
  • 2.9K
  • 15 Nov 2022
Topic Review
Nucleic Acid
Nucleic acids are the biopolymers, or small biomolecules, essential to all known forms of life. The term nucleic acid is the overall name for DNA and RNA. They are composed of nucleotides, which are the monomers made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. If the sugar is a compound ribose, the polymer is RNA (ribonucleic acid); if the sugar is derived from ribose as deoxyribose, the polymer is DNA (deoxyribonucleic acid). Nucleic acids are the most important of all biomolecules. They are found in abundance in all living things, where they function to create and encode and then store information in the nucleus of every living cell of every life-form organism on Earth. In turn, they function to transmit and express that information inside and outside the cell nucleus—to the interior operations of the cell and ultimately to the next generation of each living organism. The encoded information is contained and conveyed via the nucleic acid sequence, which provides the 'ladder-step' ordering of nucleotides within the molecules of RNA and DNA. Strings of nucleotides are bonded to form helical backbones—typically, one for RNA, two for DNA—and assembled into chains of base-pairs selected from the five primary, or canonical, nucleobases, which are: adenine, cytosine, guanine, thymine, and uracil; note, thymine occurs only in DNA and uracil only in RNA. Using amino acids and the process known as protein synthesis, the specific sequencing in DNA of these nucleobase-pairs enables storing and transmitting coded instructions as genes. In RNA, base-pair sequencing provides for manufacturing new proteins that determine the frames and parts and most chemical processes of all life forms.
  • 2.9K
  • 28 Nov 2022
Topic Review
Bacterial Nanocellulose
Bacterial nanocellulose (BNC) is a biomaterial with a growing interest in the field of nanocomposites and sustainable materials. It is produced through fermentative processes by several species of bacteria as extracellular secretion. BNC looks like a highly pure and flexible 3D porous network suitable for various applications including biodegradable materials, reinforcing agents, packaging films, transpiring membranes, and medical devices. Among the many applications, the use of BNC functionalized with organic and inorganic groups has found wide use as a catalyst in chemical transformations.
  • 2.9K
  • 25 Jan 2021
Topic Review
Dispersion
A dispersion is a system in which distributed particles of one material are dispersed in a continuous phase of another material. The two phases may be in the same or different states of matter. Dispersions are classified in a number of different ways, including how large the particles are in relation to the particles of the continuous phase, whether or not precipitation occurs, and the presence of Brownian motion. In general, dispersions of particles sufficiently large for sedimentation are called suspensions, while those of smaller particles are called colloids and solutions.
  • 2.8K
  • 11 Oct 2022
Topic Review Peer Reviewed
Deep Eutectic Solvents and Pharmaceuticals
Deep eutectic solvents (DES) are eutectic mixtures that present a deviation from the ideal thermodynamic solid–liquid phase behavior, where a significant depression in the melting temperature occurs. If properly designed and chosen, DES may be liquid at room and the human body’s temperatures and display a biocompatible character, thus representing relevant options in the pharmaceutical field. Accordingly, DES have been studied as alternative solvents or in formulations of pharmaceuticals to improve their solubility and stability. Depending on the DES components, these mixtures might exhibit interesting biological activities compatible with several applications. The use of DES as functional agents or as novel liquid forms of active pharmaceutical ingredients (API-DES) with the goal of improving bioavailability, permeability and therapeutic efficacy of a given API stands as alternative strategies in the pharmaceutical field for drug delivery purposes.
  • 2.8K
  • 13 Apr 2022
Topic Review
Hot dip galvanizing
Hot-dip galvanizing is one of the most effective methods of protecting steel against corrosion. It allows one to obtain good quality coatings, ensuring long-term protection with relatively low operating costs of the coatings.
  • 2.8K
  • 29 Oct 2020
Topic Review
Benzodiazepine Dependence
Benzodiazepine dependence defines a situation in which one has developed one or more of either tolerance, withdrawal symptoms, drug seeking behaviors, such as continued use despite harmful effects, and maladaptive pattern of substance use, according to the DSM-IV. In the case of benzodiazepine dependence, however, the continued use seems to be associated with the avoidance of unpleasant withdrawal reaction rather than from the pleasurable effects of the drug. Benzodiazepine dependence develops with long-term use, even at low therapeutic doses, without the described dependence behavior. Addiction consists of people misusing or craving the drug not to relieve withdrawal symptoms, but to experience its euphoric or intoxicating effects. It is necessary to distinguish between addiction to and abuse of benzodiazepines and physical dependence on them. The increased GABA inhibition on the neural systems caused by benzodiazepines is counteracted by the body's development of tolerance to the drug's effects; the development of tolerance occurs as a result of neuroadaptations, which result in decreased GABA activity and increased excitability of the glutamate system; these adaptations occur as a result of the body trying to overcome the central nervous system depressant effects of the drug to restore homeostasis. When benzodiazepines are stopped, these neuroadaptations are "unmasked" leading to hyper-excitability of the nervous system and the appearance of withdrawal symptoms. Therapeutic dose dependence is the largest category of people dependent on benzodiazepines. These individuals typically do not escalate their doses to high levels and generally use their medication as intended by their prescriber. Smaller groups include patients escalating their dosage to higher levels and drug misusers as well. Tolerance develops within days or weeks to the anticonvulsant, hypnotic, muscle relaxant and after 4 months there is little evidence that benzodiazepines retain their anxiolytic properties. Some authors, however, disagree and feel that benzodiazepines retain their anxiolytic properties. Long-term benzodiazepine treatment may remain necessary in certain clinical conditions. Numbers of benzodiazepine prescriptions have been declining, due primarily to concerns of dependence. In the short term, benzodiazepines can be effective drugs for acute anxiety or insomnia. With longer-term use, other therapies, both pharmacological and psychotherapeutic, become more effective. This is in part due to the greater effectiveness over time of other forms of therapy, and also due to the eventual development of pharmacological benzodiazepine tolerance.
  • 2.7K
  • 18 Nov 2022
Topic Review
LSPR Optical Fiber Sensors
In recent years, the interaction between light and metallic films have been proven to be a highly powerful tool for optical sensing applications. There has been continuous effort to integrate this plasmonic sensing technology using micro and nanofabrication techniques with the optical fiber sensor world, trying to get better, smaller and cost-effective high performance sensing solutions. In this work, we present a review of the latest and more relevant scientific contributions to the optical fiber sensors field using plasmonic materials over the last decade. The combination of optical fiber technology with metallic micro and nanostructures that allow plasmonic interactions have opened a complete new and promising field of study. We review the main advances in the integration of such metallic micro/nanostructures onto the optical fibers, discuss the most promising fabrication techniques and show the new trends in physical, chemical and biological sensing applications.
  • 2.7K
  • 31 May 2021
Topic Review
Metal Bis(trimethylsilyl)amides
Metal bis(trimethylsilyl)amides (often abbreviated as metal silylamides) are coordination complexes composed of a cationic metal with anionic bis(trimethylsilyl)amide ligands and are part of a broader category of metal amides. Due to the bulky hydrocarbon backbone metal bis(trimethylsilyl)amide complexes have low lattice energies and are lipophilic . For this reason, they are soluble in a range of nonpolar organic solvents, in contrast to simple metal halides, which only dissolve in reactive solvents. These steric bulky complexes are molecular, consisting of mono-, di-, and tetramers. Having a built-in base, these compounds conveniently react with even weakly protic reagents. The class of ligands and pioneering studies on their coordination compounds were described by Bürger and Wannagat. The ligands are often denoted hmds (e.g. M(N(SiMe3)2)3 = M(hmds)3) in reference to the hexamethyldisilazane from which they are prepared.
  • 2.7K
  • 02 Dec 2022
Topic Review
Mineralogy of Antimony Ores and Antimony Production
Antimony is a metalloid element having common oxidation states of 5+ and 3+. It is a lustrous silvery-white solid, which is quite brittle and exhibits a flaky texture.  Antimony is classified as a critical/strategic metal. Stibnite, jamesonite, and antimony-gold ores are the most common sources of antimony.
  • 2.7K
  • 02 Sep 2022
Topic Review
SLMed Magnesium Alloys
The selective laser melting（SLM） technology has the characteristics of rapid solidification.Therefore, refined microstructures and high-performance products can be obtained.The microstructure of magnesium alloy varies with the cooling rate(processing).And the higher the cooling rate, the finer the microstructure of the magnesium alloy.Different cooling rates also affect the phase composition of magnesium alloys. The SLM process inhibits the formation of the second phase in the magnesium alloy due to the characteristics of rapid solidification.Post-treatment processes, such as heat treatment and hot isostatic pressing（HIP）, can be applied to SLMed magnesium alloys. These processes help to close the pores , dissolve the second phase and reduce the source of cracks caused by the mismatch between the second phase and the α-Mg matrix, thereby improving the  mechanical properties of the magnesium alloy, especially the elongation.However, SLMed magnesium alloys need further research in the application of post-processing, alloy design, base material purification, and thermodynamic and kinetic theoretical calculations of intermetallic compounds.
  • 2.7K
  • 19 Aug 2020
Topic Review
Magnesium Forging
Interest in magnesium alloys and their applications has risen in recent years. This trend is mainly evident in casting applications, but wrought alloys are also increasingly coming into focus. Among the most common forming processes, forging is a promising candidate for the industrial production of magnesium wrought products. This overview is intended to give a general introduction into the forging of magnesium alloys and to help in the practical realization of forged products. The basics of magnesium forging practice are described and possible problems as well as material properties are discussed.
  • 2.6K
  • 10 Nov 2020
Topic Review
Rhamnus (Genus)
Rhamnus is a genus of about 110 accepted species of shrubs or small trees, commonly known as buckthorns in the family Rhamnaceae. Its species range from 1 to 10 meters tall (rarely to 15 m) and are native mainly in east Asia and North America, but found throughout the temperate and subtropical Northern Hemisphere, and also more locally in the subtropical Southern Hemisphere in parts of Africa and South America. Both deciduous and evergreen species occur. The leaves are simple, 3 to 15 centimeters long, and arranged alternately or in opposite pairs, or almost paired (subopposite). One distinctive character of many buckthorns is the way the veination curves upward towards the tip of the leaf. The plant bears fruits which are black or red berry-like drupe. The name is due to the woody spine on the end of each twig in many species. In the United States , Buckthorn is considered an invasive species by many local jurisdictions and state governments, such as Minnesota or Wisconsin.
  • 2.6K
  • 31 Oct 2022
Topic Review
Phthalocyanine Blue BN
Phthalocyanine Blue BN, also called by many names (EINECS 205-685-1), is a bright, crystalline, synthetic blue pigment from the group of phthalocyanine dyes. Its brilliant blue is frequently used in paints and dyes. It is highly valued for its superior properties such as light fastness, tinting strength, covering power and resistance to the effects of alkalis and acids. It has the appearance of a blue powder, insoluble in most solvents including water.
  • 2.6K
  • 01 Dec 2022
Topic Review
Nickel(II) Precatalysts
Nickel(II) precatalysts are a type of catalyst used in organic reactions. Many transformations are catalyzed by nickel in organometallic chemistry and in organic synthesis. Many of these transformations invoke a low valent (generally Ni(0)) species as the active catalyst. Unfortunately, unlike its counterpart, Pd(0), Ni(0) catalysts are predominantly confined to the glovebox due to their high instability to air and water, with the most common Ni(0) catalyst being Ni(cod)2. Additionally, Ni(cod)2 is more expensive than many Ni(II) salts and the quality varies significantly amongst suppliers. To make nickel catalysis more accessible and amenable to synthesis and industrial purposes, the use of air-stable Ni(II) precursors has emerged as an important development in this area of research. This page describes the more commonly employed nickel(II) precatalysts, their synthesis for those not commercially available, and the methods for their reduction to Ni(0) complexes.
  • 2.6K
  • 08 Nov 2022
Topic Review
Fundamentals of Water-Splitting Reaction
A viable energy source, hydrogen has the advantages of clean energy, high conversion efficiency, and environmental friendliness. One of the possible routes for the generation of hydrogen in this context is the solar water splitting reaction under direct sunlight. To succeed on a commercial basis, though, there remains a very long way to go. 
  • 2.6K
  • 07 Nov 2022
Topic Review
Mars Oxygen ISRU Experiment
The Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE) is a technology demonstration on the NASA Mars 2020 rover Perseverance investigating the production of oxygen on Mars. On April 20, 2021, MOXIE produced oxygen from carbon dioxide in the Martian atmosphere by using solid oxide electrolysis. This was the first experimental extraction of a natural resource from another planet for human use. The technology may be scaled up for use in a human mission to the planet to provide breathable oxygen, oxidizer, and propellant; water may also be produced by combining the produced oxygen with hydrogen. The experiment was a collaboration between the Massachusetts Institute of Technology, the Haystack Observatory, the NASA/Caltech Jet Propulsion Laboratory, and other institutions.
  • 2.6K
  • 28 Nov 2022
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