Principles Of Physical Chemistry Research Articles

Development of a Method for Determining the Residual Life of Structural Elements with Cracks Under the Action of Load and Corrosive Environment, as well as the Application of Corrosion Inhibitors to Enhance It

A developed method for determining the lifespan of structural elements with large-scale cracks of complex geometry under the influence of long-term static loads and corrosive environments. The method is based on an appropriate computational model, which relies on the first law of thermodynamics for the elementary act of local failure (crack propagation), some fundamental principles of physical chemistry, as well as the basic principles of fracture mechanics. The advantages of this method over existing ones are substantiated. The application of the method is demonstrated through examples involving the determination of the residual life of such structural elements as torsion and a pipe with small cracks made of 45KhN2MFA steel (tempered at 470 K and 725 K) under the influence of long-term static loading and distilled water. As the cracks are considered small, we have constructed a computational model in terms of deformation parameters, including a well-known counterpart in fracture mechanics, crack opening at the crack tip δt. At the same time, based on available experimental data from the literature, it is substantiated that the application of existing linear fracture mechanics methods in stress intensity factors KI for implementing the mentioned problems, the application of existing linear fracture mechanics methods is inappropriate. To determine the residual life of structural elements using this method, it is necessary to have kinetic diagrams in coordinates of the growth rate of small cracks and the crack opening at the crack tip, which means V ∼ δt. These diagrams are constructed here using the provided formulas for determining δt and diagrams are constructed here using the provided formulas and known experimental data for 45KhN2MFA steel under the influence of distilled water and static tension. Using the mentioned method, the residual lifespans of the torsion and the pipe were calculated under the influence of long-term static loading and distilled water. Additionally, the effectiveness of water solutions of well-known inorganic corrosion inhibitors on the residual lifespan of the mentioned structural elements was verified through calculations. It was found that the residual lifespan effectively characterizes the performance of corrosion inhibitors, which can be applied in engineering practice.

ВПЛИВ РУДНОВУГІЛЬНИХ КОМПОЗИЦІЙ У СКЛАДІ ШИХТИ НА ФОРМУВАННЯ ТЕРМІЧНО РЕЗЕРВНОЇ ЗОНИ ДОМЕННОЇ ПЕЧІ

The object of research is the technology of iron smelting when using ore-coal compositions. The purpose of the work is the effect of changing the composition of the blast furnace charge on the thermal state of the formation of the thermal reserve zone. Research methods - theoretical studies are based on the basic principles of physical chemistry and the theory of metallurgical processes. Experimental studies were carried out in laboratory and industrial conditions. Scientific novelty - there is a "coupling phenomenon" between recovery and gasification - this is a close contact between small particles of iron oxides and carbon, which is formed in the ore-coal composite, which ensures an increase in the efficiency of blast furnace smelting. Reduction of fuel consumption and, accordingly, the amount of gases per unit charge of modern blast furnace smelting, the height of the reserve zone is reduced; this zone is not observed in the vertical elements of the furnace with the maximum ore load. Practical significance - the use of ore-coal composites provides a high speed of iron recovery and carbon gasification reactions and a low initial temperature of carbon gasification of 250-420ºС, which is ensured by gas recirculation in the under burden, due to the short distance between the parts of iron-containing and carbon composites and their sizes, where the distance between them is short and the limit of the reaction is "visible" to both.

Physical chemical properties of surfactants in solution and their applications: A comprehensive account

AbstractIn this brief review, we have discussed various physical chemical principles that guide the functions of surfactants in solution. The surfactants have special functions at the air/liquid and air/solid interfaces forming Gibbs and Langmuir monomolecular films by way of spreading at the interfaces. Their self‐aggregation or micelle formation, a remarkable and useful phenomenon has been presented and elaborated. The application of fundamental physical chemistry principles for the understanding of the energetics of the micelle formation has been discussed. The involvement of surfactants in the formation of soft assembled (condensed) matters namely, vesicles, emulsions, foams, reverse micelles (or, microemulsions), gels, and so forth has been presented. The uniqueness of the “critical micelle concentration” (CMC), and its determination have been briefly presented. Applications of surfactants are numerous. We have briefly cited several applications namely, nano‐material synthesis, detergency, agrochemical formulations, drug delivery, retardation of water evaporation, and so forth. A short account of bio‐related surfactants namely, lung surfactants, bile salts, plant‐and microbe‐generated bio‐surfactants, and their utilities have been also presented.

Insight into structural biophysics from solution X-ray scattering

The current challenges of structural biophysics include determining the structure of large self-assembled complexes, resolving the structure of ensembles of complex structures and their mass fraction, and unraveling the dynamic pathways and mechanisms leading to the formation of complex structures from their subunits. Modern synchrotron solution X-ray scattering data enable simultaneous high-spatial and high-temporal structural data required to address the current challenges of structural biophysics. These data are complementary to crystallography, NMR, and cryo-TEM data. However, the analysis of solution scattering data is challenging; hence many different analysis tools, listed in the SAS Portal (http://smallangle.org/), were developed. In this review, we start by briefly summarizing classical X-ray scattering analyses providing insight into fundamental structural and interaction parameters. We then describe recent developments, integrating simulations, theory, and advanced X-ray scattering modeling, providing unique insights into the structure, energetics, and dynamics of self-assembled complexes. The structural information is essential for understanding the underlying physical chemistry principles leading to self-assembled supramolecular architectures and computational structural refinement.

Advances in the Applications of Bioinformatics and Chemoinformatics.

Chemoinformatics involves integrating the principles of physical chemistry with computer-based and information science methodologies, commonly referred to as "in silico techniques", in order to address a wide range of descriptive and prescriptive chemistry issues, including applications to biology, drug discovery, and related molecular areas. On the other hand, the incorporation of machine learning has been considered of high importance in the field of drug design, enabling the extraction of chemical data from enormous compound databases to develop drugs endowed with significant biological features. The present review discusses the field of cheminformatics and proposes the use of virtual chemical libraries in virtual screening methods to increase the probability of discovering novel hit chemicals. The virtual libraries address the need to increase the quality of the compounds as well as discover promising ones. On the other hand, various applications of bioinformatics in disease classification, diagnosis, and identification of multidrug-resistant organisms were discussed. The use of ensemble models and brute-force feature selection methodology has resulted in high accuracy rates for heart disease and COVID-19 diagnosis, along with the role of special formulations for targeting meningitis and Alzheimer's disease. Additionally, the correlation between genomic variations and disease states such as obesity and chronic progressive external ophthalmoplegia, the investigation of the antibacterial activity of pyrazole and benzimidazole-based compounds against resistant microorganisms, and its applications in chemoinformatics for the prediction of drug properties and toxicity-all the previously mentioned-were presented in the current review.

Thermochromism: Theory Directed Design of a Thermochromic Thermometer

The dissolution of cobalt(II) chloride in an appropriate binary alcohol solvent yields an equilibrium mixture, consisting of the differently colored octahedral (pink in color) and tetrahedral (blue in color) cobalt(II) coordination complexes, which can exhibit a brilliant and reversible pink-to-blue color transition over a ∼10 °C window─i.e., function as a thermochromic thermometer─where the dynamic equilibrium is described by CoCl2(R1OH)4+2R2OH⇄CoCl2(R2OH)2+4R1OH. In this experiment, students are challenged to exploit the principles of equilibrium in order to exhibit control over the chemical system and design, model, and implement a thermochromic thermometer which, when correctly prepared, exhibits a specifically targeted composition and color at a unique temperature assigned to each student. By employing fundamental principles of physical chemistry in conjunction with spectrophotometric analysis, students quantify pertinent thermodynamic parameters for the chemical system, and then use them to predictively model/calculate (via Excel) the exact initial composition required to enable the specifically desired equilibrium composition and color to emerge at precisely the target temperature. Completely directed by their modeled prescriptions, students then validate their theoretical predictions by implementing the functional thermochromic thermometer in the laboratory.

Electromechanical Properties of Lipid Bilayers in Peptide-Lipid Interactions: Clinical Applications

Despite the amazing diversity and complexity of living systems, all life shares the presence of a semi-permeable lipid membrane. Throughout evolution, this permeability has been finely regulated by the function of proteins that form ion channels. Similarly, some peptides can stabilize by forming aqueous pores in a dose-dependent manner. At high concentrations, however, these peptides can compromise the integrity of the membrane, destroying it. Given this behavior, a huge diversity of antimicrobial peptides and lipo-peptides has been identified. Understanding the physical-chemical principles of their interactions with lipids can contribute to the design of synthetic peptides with antimicrobial activity as an alternative to the use of conventional antibiotics.

Photons or Electrons? A Critical Comparison of Electrochemistry and Photoredox Catalysis for Organic Synthesis.

Redox processes are at the heart of synthetic methods that rely on either electrochemistry or photoredox catalysis, but how do electrochemistry and photoredox catalysis compare? Both approaches provide access to high energy intermediates (e.g., radicals) that enable bond formations not constrained by the rules of ionic or 2 electron (e) mechanisms. Instead, they enable 1e mechanisms capable of bypassing electronic or steric limitations and protecting group requirements, thus enabling synthetic chemists to disconnect molecules in new and different ways. However, while providing access to similar intermediates, electrochemistry and photoredox catalysis differ in several physical chemistry principles. Understanding those differences can be key to designing new transformations and forging new bond disconnections. This review aims to highlight these differences and similarities between electrochemistry and photoredox catalysis by comparing their underlying physical chemistry principles and describing their impact on electrochemical and photochemical methods.

Improving the efficiency of CRISPR-Cas12a-based genome editing with site-specific covalent Cas12a-crRNA conjugates

The CRISPR-Cas12a system shows unique features compared with widely used Cas9, making it an attractive and potentially more precise alternative. However, the adoption of this system has been hindered by its relatively low editing efficiency. Guided by physical chemical principles, we covalently conjugated 5' terminal modified CRISPR RNA (crRNA) to a site-specifically modified Cas12a through biorthogonal chemical reaction. The genome editing efficiency of the resulting conjugated Cas12a complex (cCas12a) was substantially higher than that of the wild-type complex. We also demonstrated that cCas12a could be used for precise gene knockin and multiplex gene editing in a chimeric antigen receptor Tcell preparation with efficiency much higher than that of the wild-type system. Overall, our findings indicate that covalently linking Cas nuclease and crRNA is an effective approach to improve the Cas12a-based genome editing system and could potentially provide an insight into engineering other Cas family members with low efficiency as well.

Physical-chemical principles of clay modifying into filler, pozzolanization through rehydro-liming, for cement concrete resistance to the natural disasters

The aim of this paper is to increase the stability of buildings and structures to natural disasters by modifying the Georgian clays into cement concrete filler by creation-using of rehydro-liming pozzolanization technology. The risk of damage-destruction of buildings and structures caused by earthquakes, sea storms, floods, mudflows, has increased in the world. Risks can be prevented by increasing of building and structure stability by reducing the anisotropy of cement concrete strength. To do this: Aqueous aluminosilicate minerals of clays, while dehydrating preserving habitus, are modified into a void containing (...mAl2O3∙nSiO2..) base minerals in which, after mixing in cement concrete while rehydro-liming, Ca(OH)2 is sorbed. The tobermorite, stratlingite, generated in filler, together with cement ettringite form fiber-needle-flaky habit clusters by modifying the structure of cement concrete with 3D self-nano-reinforcement, by reducing the anisotropy of strength – by increasing of stability to loads with variable direction-magnitude. It has been proven that in order to prevent risks of catastrophe, it is possible to use modification of Georgian clays by thermal dehydration in cement concrete technologies, which will create the preconditions for cement concrete pozzolanization by rehydro-liming, so the study of the basics of this process is actual.

Increase in strength of manganese agglomerate during processing humate solution

The object of the research is the metallurgical technology of involving finely dispersed manganese concentrates, which are formed during the extraction and enrichment of raw materials, in the production of manganese agglomerate. The purpose of the work is to develop innovative technological solutions and recommendations for the sintering tec hnology of agglomerate with an increased up to 60% share in the charge of grade 2 finely dispersed concentrate based on the results of the analysis of physicochemical processes during the sintering of manganese agglomerate and experimental studies. Research methods – theoretical studies of concentrate agglomeration processes are based on the basic principles of physical chemistry and the theory of metallurgical processes. Calculations of the thermodynamic equilibrium of oxide systems, adequate for agglomeration, are based on the Gibbs theory and implemented using the computer program "FASTSage 6.0"; the method of mathematical statistics was used to process the results. Research results. A rational scheme for preliminary preparation of finely dispersed manganese ore enrichment waste for use in metallurgical processes has been determined; a rational amount of manganese ore beneficiation waste in the initial charge has been established; the proven possibility of returning 50...70% (against the usual 10...15%) of finely di spersed (0-1 mm fractions) grade 2 manganese concentrate to the batch for the production of manganese agglomerate due to the use of the peat hydroxide reagent (PTH) in the amount of 5...7% with a simultaneous increase the strength of the agglomerate granules is doubled. The original carbonate manganese ore was treated at the stage of dosing it into the batch and the obtained agglomerate with humic peat extract to strengthen the agglomerate and reduce dust formation

New understanding of electrical activity brought by surface potential of cardiomyocytes

Aiming at the problem encountered in the previous research: during the electrical activity of cardiomyocytes, the influent ions do not seem to be directly derived from the extracellular fluid. We chose to cut in from the colloidal properties of the cells, follow the basic principles of physical chemistry, and establish hypotheses along the derivation of the structural characteristics of cardiomyocytes. Through the surface ion adsorption experiment and patch clamp experiment of living cells, under the condition of sequentially reducing the concentration of Na+ in the extracellular fluid, we observed the exchange and diffusion of adsorbed ions on the cell surface; the changes of inflow INa, ICa-L and action potential; and correlation between results. The results showed that the hypothesis is true. The observed parameter changes were consistent with the fact that during depolarization of cardiomyocytes, the ions of influx were derived from the inference of adsorbed ions on the cell surface; at the same time, it also provided an objective and realistic explanation for the generation of electrocardiogram.

Effects of plant hydraulic traits on the flammability of live fine canopy fuels

Abstract Plant species vary in how they regulate moisture and this has implications for their flammability during wildfires. We explored how fuel moisture is shaped by variation within five hydraulic traits: saturated moisture content, cell wall rigidity, cell solute potential, symplastic water fraction and tissue capacitance. Using pressure–volume curves, we measured these hydraulic traits in twigs and distal shoots (i.e. twigs + leaves) in 62 plant species across four wooded communities in south‐eastern Australia. Moisture content of fine fuels was then estimated for circumstances typical of fire weather. These projections were made assuming that under the hot, dry, windy conditions typical of large wildfires, leaves and fine twigs would function at internal water pressures close to wilting point (i.e. turgor loss point, TLP). The effect of different moisture contents at TLP on ignition time was then modelled using a fully mechanistic, finite element model of biomass ignition based on standard principles of physical chemistry. We also measured predawn water potential, an indication of plant access to soil water that is influenced by root architecture. These data were used to model how root traits influence fuel moisture and ignition time. Most variation among species in fuel moisture under fire weather conditions arose from differences in saturated moisture content (3.4‐ to 3.6‐fold variation). Twig capacitance was also an important driver of fuel moisture under these weather conditions (1.9‐ to 2.2‐fold variation in moisture content). A suite of other leaf and root traits influencing how much shoots dry out as they approach wilting point each contributed 1.0‐ to 1.6‐fold variation in projected fuel moisture during fire weather. Fuel moisture variation in turn drove variation in flammability by modifying predicted ignition time. Two main life‐history types in fire‐prone habitats are obligate seeders and resprouters. There were no significant differences between these species groups in estimated fuel moisture during fire weather, nor in any measured hydraulic traits. Live fuel moisture is an important determinant of wildfire activity. Our data show that variation in tissue saturated moisture content among co‐occurring species represents an important ecological store of variation in flammability in the study communities. A free Plain Language Summary can be found within the Supporting Information of this article.

A Triple Role for a Bilayer: Using Nanoliposomes to Cross and Protect Cellular Membranes.

Thanks in large part to the seminal work of Steve White and his colleagues, we appreciate the "ordered complexity" of the lipid bilayer and how it impacts the incorporation of integral membrane proteins as well as more peripherally associated proteins. Steve's work also provides a vital foundation to tackle another challenge: cytotoxic oligomeric complexes which accumulate in various neurodegenerative diseases. These oligomers have a relatively fluid structure and interact with many different proteins in the cell, but their main target is thought to be the phospholipid membrane, either the plasma membrane or internal organelles such as the mitochondria. This fascinating encounter between two essentially fluid phases generates a more disordered membrane, and presumably promotes uncontrolled transport of small metal ions across the membrane barrier. Happily, this unwanted interaction may be suppressed by mobilizing the phospholipid bilayer into its own defense. Extruded nanolipoparticles (NLPs) consisting of DPPC lipids, cholesterol and PEG2000 are excellent vehicles to take up small "oligomer-bashing" hydrophobic molecules such as baicalein and transport them with increased half-life in the plasma and with markedly more efficient crossing of the blood-brain barrier. Thus the bilayer has a triple role in this account: a safe space for a reactive hydrophobic small molecule, a barrier to cross to deliver a drug payload and a target to protect against oligomer attacks. NLPs containing small hydrophobic molecules show great promise in combating neurodegenerative diseases in animal models and may serve as an example of the White approach: applying robust physical-chemical principles to deal with biological problems involving phospholipid membranes.

Mechanistic Investigations of Growth of Anisotropic Nanostructures in Reverse Micelles.

Tailoring the characteristics of anisotropic nanostructures like size, morphology, aspect ratio, and size dispersity is of extreme importance due to the unique and tunable properties including catalytic, optical, photocatalytic, magnetic, photochemical, electrochemical, photoelectrochemical, and several other physical properties. The reverse microemulsion (RM) method offers a useful soft-template and low-temperature procedure that, by variation of experimental conditions and nature of reagents, has proved to be extremely versatile in synthesis of nanostructures with tailored properties. Although many reports of synthesis of nanostructures by the RM method exist in the literature, most of the research studies carried out still follow the “hit and trial” method where the synthesis conditions, reagents, and other factors are varied and the resulting characteristics of the obtained nanostructures are justified on the basis of existing physical chemistry principles. Mechanistic investigations are scarce to generate a set of empirical rules that would aid in preplanning the RM-based synthesis of nanostructures with desired characteristics as well as make the process viable on an industrial scale. A consolidation of such research data available in the literature is essential for providing future directions in the field. In this perspective, we analyze the literature reports that have investigated the mechanistic aspects of growth of anisotropic nanostructures using the RM method and distil the essence of the present understanding at the nanoscale timescale using techniques like FCS and ultrafast spectroscopy in addition to routine techniques like DLS, fluorescence, TEM, etc.

Novel technology for hydrogen sulfide purification via the slurry prepared from roasted vanadium steel slag

Roasted vanadium-bearing steel (V-S) slag was used to prepare absorption slurry to purify H2S offgas, and the technical parameters and mechanism for the H2S purification were investigated in this study. The roasted V-S slag had a relatively high alkalinity and abundant higher-valence metal oxides, and it exhibited a relatively high desulfurisation efficiency and sulfur capacity. When the pH of the absorption slurry maintained a natural variation, the desulfurisation rate in the absorption system was almost 100% within 100 min, then gradually decreased from 96.9% at 120 min to 77.2% at 260 min. O2 could moderately restore the oxidation performance of the absorption slurry, and the O2 content in the inlet gas was not less than 0.5%. The molecular H2S diffused from a gas to liquid phase. HS− was the main form of soluble sulfide under alkaline condition, and it might be oxidised to sulfur-containing products by the dissolved metal ions or oxygen in the aqueous solution. Based on the principles of physical chemistry and the results obtained in this study, a pathway of the H2S catalytic purification via the absorption slurry of roasted V-S slag was proposed, and potential chemical reactions during the desulfurisation process were also suggested to expound on the process of H2S catalytic oxidation.

A Survival Guide for the "Electro-curious".

The appeal and promise of synthetic organic electrochemistry have been appreciated over the past century. In terms of redox chemistry, which is frequently encountered when forging new bonds, it is difficult to conceive of a more economical way to add or remove electrons than electrochemistry. Indeed, many of the largest industrial synthetic chemical processes are achieved in a practical way using electrons as a reagent. Why then, after so many years of the documented benefits of electrochemistry, is it not more widely embraced by mainstream practitioners? Erroneous perceptions that electrochemistry is a "black box" combined with a lack of intuitive and inexpensive standardized equipment likely contributed to this stagnation in interest within the synthetic organic community. This barrier to entry is magnified by the fact that many redox processes can already be accomplished using simple chemical reagents even if they are less atom-economic. Time has proven that sustainability and economics are not strong enough driving forces for the adoption of electrochemical techniques within the broader community. Indeed, like many synthetic organic chemists that have dabbled in this age-old technique, our first foray into this area was not by choice but rather through sheer necessity. The unique reactivity benefits of this old redox-modulating technique must therefore be highlighted and leveraged in order to draw organic chemists into the field. Enabling new bonds to be forged with higher levels of chemo- and regioselectivity will likely accomplish this goal. In doing so, it is envisioned that widespread adoption of electrochemistry will go beyond supplanting unsustainable reagents in mundane redox reactions to the development of exciting reactivity paradigms that enable heretofore unimagined retrosynthetic pathways. Whereas the rigorous physical organic chemical principles of electroorganic synthesis have been reviewed elsewhere, it is often the case that such summaries leave out the pragmatic aspects of designing, optimizing, and scaling up preparative electrochemical reactions. Taken together, the task of setting up an electrochemical reaction, much less inventing a new one, can be vexing for even seasoned organic chemists. This Account therefore features a unique format that focuses on addressing this exact issue within the context of our own studies. The graphically rich presentation style pinpoints basic concepts, typical challenges, and key insights for those "electro-curious" chemists who seek to rapidly explore the power of electrochemistry in their research.

Developing physical-chemical principles to manufacture effective heating systems when using mica

The organization of effective heating systems in non-industrial, industrial and livestock buildings is an urgent problem. The developing of heating is especially relevant for utilizing in agricultural industry. Energy prices are steadily rising, and as a result, the efficient utilization of energy resources is of great significance for this industry. One of the most prospective lines of development in this area can be the trend to utilize resistive heaters where mica is used as a basic material. The research aim. Developing physical-chemical principles to manufacture effective heating systems when using mica for the construction industry. The possibility of employing composite materials to produce an economically sound, reliable, electro-permissible and stable heater is considered. Finding physical and chemical laws of interaction of mica with the binder element in the technology of micaceous composites. Research methods. The methods of thermodynamic quantum chemical calculations, as well as kinetic studies that involve a number of advanced techniques of physical and chemical studies (x-ray phase analysis, thermal analysis, and IR spectroscopy). Electro physical and mechanical characteristics of composites and starting materials were determined by the standardized methods to comply with the All Union State Standard. Research results. The foundations of effective heating systems when utilizing micalex have been worked out by means of scientific generalizations and experimental studies. The developed technology of electric heating elements (mica ceramic electric heating) is employed in various fields of construction industry.

The transition model of RTK activation: A quantitative framework for understanding RTK signaling and RTK modulator activity

Here, we discuss the transition model of receptor tyrosine kinase (RTK) activation, which is derived from biophysical investigations of RTK interactions and signaling. The model postulates that (1) RTKs can interact laterally to form dimers even in the absence of ligand, (2) different unliganded RTK dimers have different stabilities, (3) ligand binding stabilizes the RTK dimers, and (4) ligand binding causes structural changes in the RTK dimer. The model is grounded in the principles of physical chemistry and provides a framework to understand RTK activity and to make predictions in quantitative terms. It can guide basic research aimed at uncovering the mechanism of RTK activation and, in the long run, can empower the search for modulators of RTK function.

Seeking to uncover biology's chemical roots

Despite the considerable advances in molecular biology over the past several decades, the nature of the physical-chemical process by which inanimate matter become transformed into simplest life remains elusive. In this review, we describe recent advances in a relatively new area of chemistry, systems chemistry, which attempts to uncover the physical-chemical principles underlying that remarkable transformation. A significant development has been the discovery that within the space of chemical potentiality there exists a largely unexplored kinetic domain which could be termed dynamic kinetic chemistry. Our analysis suggests that all biological systems and associated sub-systems belong to this distinct domain, thereby facilitating the placement of biological systems within a coherent physical/chemical framework. That discovery offers new insights into the origin of life process, as well as opening the door toward the preparation of active materials able to self-heal, adapt to environmental changes, even communicate, mimicking what transpires routinely in the biological world. The road to simplest proto-life appears to be opening up.