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Topic Review
Multivariable Formulation of Surfactant-Oil-Water Systems
Surfactant-Oil-Water (SOW) systems are found in nature and synthetic products. They usually result in two immiscible phases, e.g., for two liquids, a water phase (often a brine), and an oily phase (which could be extremely complex as petroleum). Surfactant partitions between the two phases according to some physicochemical rules due to molecular interactions. There is a very particular formulation case in which SOW systems can form three immiscible phases, that is, two excess phases (water and oil) in equilibrium with a  so-called middle phase (because of an intermediate density that places it in the middle of a test tube). This middle phase is a so-called bicontinuous microemulsion which has no droplets dispersed in an external phase as a typical emulsion, but a complex single-phase structure similar to a disordered liquid crystal. When stirred, SOW systems can form multiple dispersed systems that can be described as macroemulsions or nanoemulsions depending on the drop size (O/W or W/O) or multiple emulsions (w/O/W or o/W/O) with droplets inside larger drops. Since the beginnings of the 20th century with Bancroft’s rule, the properties of these systems have been related to many thermodynamic variables, generally with one effect at a time. Nowadays, the generalized physicochemical concept of SOW systems with many formulation variables involved allows to make predictions in various application cases, even for very complex systems, as in enhanced oil recovery (EOR), crude oil dehydration, paints, foods, cosmetics and pharmaceutical formulations, that requires the control on 6-8 variables or even more. This is mainly because of the presence of mixtures of oils from linear alkanes to triglycerides or complex molecules perfumes, or a mixture of salts with cations from sodium to calcium or aluminum, and anions like chloride to phosphate. The complexity is even worse with mixtures of very different surface-active species, resulting in non-linear interactions.
  • 3.6K
  • 17 Aug 2021
Topic Review
The Nitrogen Bond
The nitrogen bond in chemical systems occurs when there is evidence of a net attractive interaction between the electrophilic region associated with a covalently or coordinately bound nitrogen atom in a molecular entity and a nucleophile in another, or the same molecular entity. It is the first member of the family of pnictogen bonds formed by the first atom of the pnictogen family, Group 15, of the periodic table, and is an inter- or intra-molecular non-covalent interaction.
  • 3.6K
  • 25 Mar 2022
Topic Review
Water radical cations
The study of water continues to provide surprises as evidenced by recent work on the surfaces of small droplets. Systems comprising numbers of water molecules and corresponding cations represent a topic of special interest, such as nuclear safety, functional biomolecules (DNA, RNA, and proteins) damage, proton transfer process and so on. To date, water radical cations have been created through wet nitrogen ionized as a result of subjected to electron-impact ionization, photoionization of a water molecular beam or vapor, even including in helium nanodroplets. They have also been generated through intermolecular coulomb decay process by high-energy photos or above 70 eV electrons impactions.For (H2O)2+•, a theoretical simulation led to both the structure resulting from proton transfer and the dimer cation structure. For larger water radical cations, these clusters are easily constructed from the (H2O)nH+ structures by substituting one of the water molecules, which is the next neighbor of the charged site for •OH radical. Besides the ultra-fast proton transfer reaction within (H2O)n+• , and between (H2O)n+• and its neighboring water molecules to form the proton transfer product, (H2O)n+• also present ultrafast charge migration from a solute M to (H2O)n+•.
  • 3.6K
  • 27 Oct 2020
Topic Review
Singlet Fission
Singlet fission is a process that occurs in organic molecules upon the absorption of light. It produces a singlet excited state (S1) in one molecule that is shared with a neighbouring one in the ground state (S0), thus splitting into two triplet excited states (T1).
  • 3.6K
  • 01 Jun 2021
Topic Review
Pentacene and Its Derivatives Deposition Methods
Pentacene is a well-known conjugated organic molecule with high mobility and a sensitive photo response. It is widely used in electronic devices, such as in organic thin-film transistors (OTFTs), organic light-emitting diodes (OLEDs), photodetectors, and smart sensors. With the development of flexible and wearable electronics, the deposition of good-quality pentacene films in large-scale organic electronics at the industrial level has drawn more research attention. Several methods are used to deposit pentacene thin films. The thermal evaporation technique is the most frequently used method for depositing thin films, as it has low contamination rates and a well-controlled deposition rate. Solution-processable methods such as spin coating, dip coating, and inkjet printing have also been widely studied because they enable large-scale deposition and low-cost fabrication of devices. 
  • 3.2K
  • 18 Apr 2022
Topic Review
Atmospheric Pressure Plasma Surface Treatment
Atmospheric plasma treatment is an effective and economical surface treatment technique. The main advantage of this technique is that the bulk properties of the material remain unchanged while the surface properties and biocompatibility are enhanced.
  • 3.2K
  • 09 Apr 2021
Topic Review
Structure and Bonding in Planar Hypercoordinate Carbon Compounds
The term hypercoordination refers to the extent of the coordination of an element by its normal value. In the hypercoordination sphere, the element can achieve planar and/or non-planar molecular shape. Hence, planar hypercoordinate carbon species violate two structural rules: (i) The highest coordination number of carbon is four and (ii) the tetrahedral orientation by the connected elements and/or groups. The unusual planar orientations are mostly stabilized by the electronic interactions of the central atom with the surrounding ligands. Primary knowledge of the planar hypercoordinate chemistry will lead to its forthcoming expansion. Experimental and theoretical interests in planar tetracoordinate carbon (ptC), planar pentacoordinate carbon (ppC), and planar hexacoordinate carbon (phC) are continued. The proposed electronic and mechanical strategies are helpful for the designing of the ptC compounds. Moreover, the 18-valence electron rule can guide the design of new ptC clusters computationally as well as experimentally. However, the counting of 18-valence electrons is not a requisite condition to contain a ptC in a cluster. Furthermore, this ptC idea is expanded to the probability of a greater coordination number of carbon in planar orientations. Unfortunately, until now, there are no such logical approaches to designing ppC, phC, or higher-coordinate carbon molecules/ions. There exist a few global minimum structures of phC clusters identified computationally, but none have been detected experimentally. All planar hypercoordinate carbon species in the global minima may be feasible in the gas phase.
  • 3.1K
  • 26 Dec 2022
Topic Review
Mass Concentration
In chemistry, the mass concentration ρi (or γi) is defined as the mass of a constituent mi divided by the volume of the mixture V. For a pure chemical the mass concentration equals its density (mass divided by volume); thus the mass concentration of a component in a mixture can be called the density of a component in a mixture. This explains the usage of ρ (the lower case Greek letter rho), the symbol most often used for density.
  • 3.0K
  • 12 Oct 2022
Topic Review
Hydrogen Bond Energy
Hydrogen bonds (HBs) play a crucial role in many physicochemical and biological processes. Theoretical methods can reliably estimate the intermolecular HB energies. Quantifying an intramolecular hydrogen bond (IHB) strength is not as straightforward as the intermolecular one. The main difficulty lies in isolating the X–H···Y interaction present within a molecule than in a dimer or a complex. However, the procedure discussed (viz. molecular tailoring approach) in this article, allows the generation of fragments so that the atoms/functional groups involved in the HB formation are parts of two different fragments. The energies of these fragments are added or substracted, using the inclusion exclusion principle in set theory, to obtained the energy of HB bond.
  • 3.0K
  • 19 May 2021
Topic Review
Progress of 2D Semiconductor-based photocatalysts
A complete view of basic principles and mechanisms with regard to improving the structure stability, physical and chemical properties of the low dimensional semiconductor-based photocatalysts is presented here. Various 2D semiconductor-based photocatalysts show a high electrochemical property and photocatalytic performance due to their ultrathin character, high specific surface area with more activity sites, tunable bandgap to absorb sunlight and versatile options in structural assembly with other nanosheets. At present, most photocatalysts still need rare or expensive noble metals to improve the photocatalytic activity, which inhibits their commercial-scale application extremely. Thus, developing less costly, earth-abundant semiconductor-based photocatalysts with the efficient conversion of sunlight energy remains the primary challenge. A concise overview of different types of 2D semiconductor-mediated photocatalysts is given to figure out the advantages and disadvantages for mentioned semiconductor-based photocatalysis, including the structural property and stability, synthesize method, electrochemical property, and optical properties for H2/O2 production half-reaction along with overall water splitting.
  • 3.0K
  • 21 Oct 2020
Topic Review
Preparation of Protein Oleogels
In recent years, the search for alternative routes to structure oil has gained increasing interest. Structured oils are referred to as oleogels, in which the continuous lipid phase is an edible oil, and the structuring agent forms a three-dimensional network. Such oleogels are used as a substitute for solid fats, which contain high amounts of saturated and trans fatty acids. Among available structuring agents that have been used to provide solid properties to liquid oils, protein is a more recent candidate. Due to their nutritional value and high consumer acceptance, proteins are of special interest for the preparation of edible oleogels as an alternative for solid fats. Whereas the field of protein oleogelation is still rather new and just starts unfolding, several preparation methods have been demonstrated to be suitable for protein oleogel preparation. 
  • 2.8K
  • 12 Jan 2021
Topic Review
Gas Hydrate Technology
Innovating methods for treating industrial wastewater containing heavy metals frequently incorporate toxicity-reduction technologies to keep up with regulatory requirements. This research reviews the latest advances, benefits, opportunities and drawbacks of several heavy metal removal treatment systems for industrial wastewater in detail. The conventional physicochemical techniques used in heavy metal removal processes with their advantages and limitations are evaluated. A particular focus is given to innovative gas hydrate-based separation of heavy metals from industrial effluent with their comparison, advantages and limitations in the direction of commercialization as well as prospective remedies. Clathrate hydrate-based removal is a potential technology for the treatment of metal-contaminated wastewater. In this research, a complete assessment of the literature is addressed based on removal efficiency, enrichment factor and water recovery, utilizing the gas hydrate approach. It is shown that gas hydrate-based treatment technology may be the way of the future for water management purposes, as the industrial treated water may be utilized for process industries, watering, irrigation and be safe to drink. 
  • 2.8K
  • 15 Apr 2022
Topic Review
Recrystallization
In chemistry, recrystallization is a technique used to purify chemicals. By dissolving both impurities and a compound in an appropriate solvent, either the desired compound or impurities can be removed from the solution, leaving the other behind. It is named for the crystals often formed when the compound precipitates out. Alternatively, recrystallization can refer to the natural growth of larger ice crystals at the expense of smaller ones.
  • 2.6K
  • 14 Oct 2022
Topic Review
Eugenol-based O/W Emulsion by Low-energy Emulsification
Emulsions are systems formed by two immiscible liquids, one of which is dispersed in the other as droplets with a relative stability. These have multiple applications, among them, in the formulation of pharmaceutical and cosmetic products. Its preparation requires generating a large interfacial area, which is usually attained by using the physicochemical formulation know-how on surfactant-oil-water (SOW) systems. Among the applications in the pharmaceutical industry, topical creams, and emulsions for intravenous and for oral administration can be found.  Eugenol can be extracted from cloves (Syzygium aromaticum) by various methods, including steam distillation, hydrodistillation and Soxhlet extraction. Furthermore, emulsions based on eugenol can be obtained for a variety of applications, including as topical and oral anesthetic. Nanoemulsions can be formulated with a mixture of non-ionic surfactants Span 20/Tween 80 at an HLB of 11 to 13 and a total surfactant concentration of 4%, using the dilution phase transition method (so-called spontaneous emulsification) to attain stable O/W eugenol-based emulsions. Paraffin oil/eugenol ratio of 4/1 can be used to reach a final emulsion internal oil phase content of 10% with 4% surfactant and 86% aqueous phase. Different polymers are used as viscosifiers, including carboxymethylcellulose. Under these conditions, eugenol-based emulsions with an average droplet size of less than 2 μm can be attained, with topical and oral anesthetic characteristics.
  • 2.6K
  • 03 Apr 2022
Topic Review
Ignition of Fires from Electrical Causes
In a number of countries, somewhere around 20% of reported building fires are due to electrical faults or failures. There can be a number of mechanisms responsible, but arcing in air and hot-surface ignitions of combustible materials are important causes. Details of these two mechanisms are reviewed. It is shown that even though arcing in air produces temperatures greatly higher than the ignition temperature of any ignitable solid, this does not always result in ignition. With regards to ignitions from hot surfaces or objects, it is shown that the area of the hot object presented to the ignitable material is a crucial variable.
  • 2.6K
  • 10 Aug 2023
Topic Review
Hydrogen Bond
The hydrogen bond may be treated as a local stabilizing interaction that acts between the proton or the electron charge deficient region of hydrogen centre and the electron rich region that is related to one or more centres. This may be named as the two-sites hydrogen bond definition. However in numerous studies the A-H proton donating bond with the positively charged H-atom and the proton acceptor, say B, being the electron rich centre are taken into account. Thus so-called A-H∙∙∙B hydrogen bridges are often considered. In such a way the three-sites hydrogen bond definition may be proposed that the hydrogen bond is the A-H∙∙∙B local stabilizing system with the proton situated between two A and B electron rich sites, most often closer to one of them, forming the A-H covalent bond; both A and B may correspond to one or more atomic centres.
  • 2.5K
  • 07 Sep 2021
Topic Review
Bioactive Lipids in Food Applications
Bioactive lipids, such as fat-soluble vitamins, omega-3 fatty acids, conjugated linoleic acids, carotenoids and phytosterols play an important role in boosting human health and wellbeing. These lipophilic substances cannot be synthesized within the human body, and so people must include them in their diet. There is increasing interest in incorporating these bioactive lipids into functional foods designed to produce certain health benefits, such as anti-inflammatory, antioxidant, anticancer and cholesterol-lowering properties. However, many of these lipids have poor compatibility with food matrices and low bioavailability because of their extremely low water solubility. Nanotechnology is a promising technology that can be used to overcome many of these limitations. Different kinds of nanoscale delivery systems have been designed to encapsulate and protect bioactive lipids, thereby facilitating their handling, stability, food matrix compatibility, and bioavailability.
  • 2.5K
  • 27 Mar 2021
Topic Review
Protection of Iron by Corrosion Inhibitors
Iron is a widely used metal due to its low cost and availability, but it is susceptible to corrosion in many circumstances. This corrosion can result in economic and environmental losses, and negatively affect the physical and chemical properties of the metal.
  • 2.4K
  • 24 Mar 2023
Topic Review
Ionic and Excited Species
Experimental and theoretical studies of either characterization and reactivity of ionic and excited species with atoms, molecules, and radicals of interest in the chemistry of plasmas and energy production. Single and ionized species with single or multiple charge (H+, He+, H3+, HCO+, H3O+, He22+, CO22+, etc.), excited atoms and molecules (e.g. O(1D), N(2D), H*(2s2S1/2), He*(21,3S0,1), N2*(A3Σu+), etc.) play a crucial role in various important chemical systems such as flames (i.e. chemi-ionizations), natural plasmas (i.e. planetary ionospheres, comet tails and interstellar clouds), and biological environments (e.g. damaged biological tissues via the interaction between ionizing radiation and living cells). Such processes are very interesting from a fundamental point of view in Physical Chemistry and attracted the attention of a wide scientific community, since many applications to important fields: radiation chemistry, plasma physics and chemistry, combustion processes, development of laser sources. In particular, the conversion of waste carbon dioxide via assisted plasma technology gained recently increasing interest due to the possibility of obtaining value-added products, like gaseous or liquid fuels. Such characteristics make this an encouraging strategy for the storage of electrical energy from renewable sources into chemical energy in a circular economy scheme.
  • 2.3K
  • 01 Nov 2020
Topic Review
Citric Acid Derived Carbon Dots
Carbon Dots (CDs) are a kind of 0-D emissive spheroidal carbon-based nanostructures with a size smaller than 20 nm. The CDs, in fact, stand in between organic (polymers) and inorganic materials (black carbon), macromolecules, and nanoparticle, between bottom-up (polycyclic aromatic compounds) and top-down synthesis (laser ablation of graphene, etc.).
  • 2.3K
  • 01 Feb 2021
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