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Point Group (PG) symmetries play a fundamental role in many aspects of theoretical chemistry and computational materials science. With the objective to automatize the search of PG symmetry operations of generic atomic clusters, we present a new algorithm called Symmetry Operation FInder (SOFI). SOFI addresses the problem of identifying PG symmetry by framing it as a degenerate shape-matching problem, where the multiple solutions correspond to distinct symmetry operations. The developed algorithm is compared against three other algorithms dedicated to PG identification on a large set of atomic clusters. The results, along with some illustrative use cases, showcase the effectiveness of SOFI. The SOFI algorithm is released as part of the iterative rotations and assignments library, accessible at https://github.com/mammasmias/IterativeRotationsAssignments. [ABSTRACT FROM AUTHOR]

Simulations of photochemical reaction dynamics have been a challenge to the theoretical chemistry community for some time. In an effort to determine the predictive character of current approaches, we predict the results of an upcoming ultrafast diffraction experiment on the photodynamics of cyclobutanone after excitation to the lowest lying Rydberg state (S2). A picosecond of nonadiabatic dynamics is described with ab initio multiple spawning. We use both time dependent density functional theory (TDDFT) and equation-of-motion coupled cluster singles and doubles (EOM-CCSD) theory for the underlying electronic structure theory. We find that the lifetime of the S2 state is more than a picosecond (with both TDDFT and EOM-CCSD). The predicted ultrafast electron diffraction spectrum exhibits numerous structural features, but weak time dependence over the course of the simulations. [ABSTRACT FROM AUTHOR]

Reaction rate theory has been at the center of physical chemistry for well over one hundred years. The evolution of the theory is not only of historical interest. Reliable and accurate computation of reaction rates remains a challenge to this very day, especially in view of the development of quantum chemistry methods, which predict the relevant force fields. It is still not possible to compute the numerically exact rate on the fly when the system has more than at most a few dozen anharmonic degrees of freedom, so one must consider various approximate methods, not only from the practical point of view of constructing numerical algorithms but also on conceptual and formal levels. In this Perspective, I present some of the recent analytical results concerning leading order terms in an ℏ2m series expansion of the exact rate and their implications on various approximate theories. A second aspect has to do with the crossover temperature between tunneling and thermal activation. Using a uniform semiclassical transmission probability rather than the "primitive" semiclassical theory leads to the conclusion that there is no divergence problem associated with a "crossover temperature." If one defines a semiclassical crossover temperature as the point at which the tunneling energy of the instanton equals the barrier height, then it is a factor of two higher than its previous estimate based on the "primitive" semiclassical approximation. In the low temperature tunneling regime, the uniform semiclassical theory as well as the "primitive" semiclassical theory were based on the classical Euclidean action of a periodic orbit on the inverted potential. The uniform semiclassical theory wrongly predicts that the "half-point," which is the energy at which the transmission probability equals 1/2, for any barrier potential, is always the barrier energy. We describe here how augmenting the Euclidean action with constant terms of order ℏ2 can significantly improve the accuracy of the semiclassical theory and correct this deficiency. This also leads to a deep connection with and improvement of vibrational perturbation theory. The uniform semiclassical theory also enables an extension of the quantum version of Kramers' turnover theory to temperatures below the "crossover temperature." The implications of these recent advances on various approximate methods used to date are discussed at length, leading to the conclusion that reaction rate theory will continue to challenge us both on conceptual and practical levels for years to come. [ABSTRACT FROM AUTHOR]

Purpose: To analyze the effectiveness of coating of abutments with antimicrobial agents and their influence on the physicochemical and biologic properties of the coated materials. Materials and Methods: This work was registered in Open Science Framework (osf.io/6tkcp) and followed the PRISMA protocols. A search of two independent reviewers of articles published up to October 29, 2021, was performed in the Embase, PubMed, Science Direct, and Scopus databases. Results: The databases found a total of 1,474 references. After excluding the duplicates, 1,050 remained. After reading the titles and abstracts and applying the inclusion criteria, 13 articles remained and were read in full. A total of 8 articles were included in this systematic review. Different antimicrobial agents have been used to coat abutments, including graphene oxide, polydopamine, titanium and zirconium nitride, lactoferrin, tetracycline, silver, and doxycycline with varied release times. Titanium-coated silver showed a better antimicrobial agent release time of up to 28 days. Chemical analysis confirmed the presence of antimicrobials on the surface after coating. Different pathogenic microorganisms, such as Streptococcus sanguinis, Streptococcus oralis, and Staphylococcus aureus, were inhibited when in contact with the coated surface. Conclusions: This review showed that there is still no consensus on which is the better antimicrobial agent and which coated materials have the better performance. However, the association of surface coating of abutments with antimicrobials is feasible and can benefit many patients, which can support their clinical use to favor the healing process and prevent infections that can lead to treatment failure with dental implants. [ABSTRACT FROM AUTHOR]

Despite the wide existence of vesicles in living cells as well as their important applications like drug delivery, the underlying mechanism of vesicle fusion/fission remains under debate. Classical models cannot fully explain recent observations in experiments and simulations. Here, we develop a constrained self-consistent field theory that allows tracking the shape evolution and free energy as a function of center-of-mass separation distance. Fusion and fission are described in a unified framework. Both the kinetic pathway and the mechanical response can be simultaneously captured. By taking vesicles formed by polyelectrolytes as a model system, we predict discontinuous transitions between the three morphologies: parent vesicle with a single cavity, hemifission/hemifusion, and two separated child vesicles, as a result of breaking topological isomorphism. With the increase in inter-vesicle repulsion, we observe a great reduction in the cleavage energy, indicating that vesicle fission can be achieved without hemifission, in good agreement with simulation results. The force–extension relationship elucidates typical plasticity for separating two vesicles. The super extensibility in the mechanical response of vesicle is in stark contrast to soft particles with other morphologies, such as cylinder and sphere. Our work elucidates the fundamental physical chemistry based on intrinsic topological features of vesicle fusion/fission, which provides insights into various phenomena observed in experiments and simulations. [ABSTRACT FROM AUTHOR]

The on-demand assembly of 2D heterostructures has brought about both novel interfacial physical chemistry and optoelectronic applications; however, existing studies rarely focus on the complementary part—the 2D cavity, which is a new-born area with unprecedented opportunities. In this study, we have investigated the electric field inside a spacer-free 2D cavity consisting of a monolayer semiconductor and a gold film substrate. We have directly captured the built-in electric field crossing a blinking 2D cavity using a Kelvin probe force microscopy–Raman system. The simultaneously recorded morphology (M), electric field (E), and optical spectroscopy (O) mapping profile unambiguously reveals dynamical fluctuations of the interfacial electric field under a constant cavity height. Moreover, we have also prepared non-blinking 2D cavities and analyzed the gap-dependent electric field evolution with a gradual heating procedure, which further enhances the maximum electric field exceeding 109 V/m. Our work has revealed substantial insights into the built-in electric field within a 2D cavity, which will benefit adventures in electric-field-dependent interfacial sciences and future applications of 2D chemical nanoreactors. [ABSTRACT FROM AUTHOR]

The solvent effects on the linear and second-order nonlinear optical properties of an aminonaphtylethenylpyridinium (ANEP) dye are investigated by combining experimental and theoretical chemistry methods. On the one hand, deep near infrared (NIR) hyper-Rayleigh scattering (HRS) measurements (1840–1950 nm) are performed on solutions of di-8-ANEPPS in deuterated chloroform, dimethylformamide, and dimethylsulfoxide to determine their first hyperpolarizablity (βHRS). For the first time, these HRS experiments are carried out in the picosecond regime in the deep NIR with very moderate (≤3 mW) average input power, providing a good signal-to-noise ratio and avoiding solvent thermal effects. Moreover, the frequency dispersion of βHRS is investigated for Disperse Red 1 (DR1), a dye commonly used as HRS external reference. On the other hand, these are compared with computational chemistry results obtained by using a sequential molecular dynamics (MD) then quantum mechanics (QM) approach. The MD method allows accounting for the dynamical nature of the molecular structures. Then, the QM part is based on TDDFT/M06-2X/6-311+G* calculations using solvation models ranging from continuum to discrete ones. Measurements report a decrease of the βHRS of di-8-ANEPPS in more polar solvents and these effects are reproduced by the different solvation models. For di-8-ANEPPS and DR1, comparisons show that the use of a hybrid solvation model, combining the description of the solvent molecules around the probe by point charges with a continuum model, already achieves quasi quantitative agreement with experiment. These results are further improved by using a polarizable embedding that includes the atomic polarizabilities in the solvent description. [ABSTRACT FROM AUTHOR]

In this study, phenyl (1,4,6-triphenyl-2-thioxo-1,2,3,4-tetrahydropyrimidin-5-yl)methanone was obtained by using the Biginelli reaction method. The structure of this compound was analyzed using elemental analysis, IR, 1H, and 13C NMR. The quantum chemical calculations (QCC) of this compound were performed density functional theory (DFT) method, 6–31 G (d, p) base set, and B3LYP functions with the Gaussian09W software package. Literature shows that pyrimidine-derived compounds have very active biological properties. For this reason, the biologically active properties of the synthesized compound were also examined. To determine embryotoxic, genotoxic, and cytotoxic effects of compound, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), lactate dehydrogenase (LDH) release, micronucleus (MN) and 8-OH-dG assays were carried out. On the other hand, pharmacokinetic and toxicity properties (ADMET) were predicted in silico via SwissADME and Protox-II web tools. In silico estimates of this compound used in the study showed that the compound has the covetable physicochemical properties for bioavailability. In conclusion, the obtained results of our study clearly showed that this compound exerted strong toxicity potential. [ABSTRACT FROM AUTHOR]

Coronavirus is a family of viruses that cause upper respiratory infections in humans. Drug properties can be obtained by studying the molecular structure of corresponding drugs. The calculation of the topological index of a drug structure enables scientists to have a better understanding of the physical chemistry and biological characteristics of drugs. In this paper, we study topological indices and find the exact formulas for general topological indices m S O γ (G) and K A (γ , η) 1 (G). By the appropriate choice of parameters γ and η, several new/old inequalities that reveal topological indices are obtained. [ABSTRACT FROM AUTHOR]

Carotenoids are especially hydrophobic and dissolve poorly in water. Encapsulation is used to increase their solubility in water-based food products. However, it is not yet known whether encapsulation with a combination of lecithin and medium-chain triglycerides improves carotenoid bioaccessibility and intestinal cell uptake. The relative bioaccessibility and Caco-2 cell uptake of two water-soluble carotenoid (i.e. lutein and astaxanthin) dispersions in a liquid form (VitaSperse®) and a powdered form (VitaDry®) were compared to the carotenoid ingredient alone. An in vitro digestion model was used to assess bioaccessibility, measuring the micellarized fraction postdigestion. The micelle fraction was incubated with Caco-2 cells to assess intestinal uptake of carotenoids. Encapsulation (by either VitaDry® or Vitasperse®) increased total astaxanthin bioaccessibility 2-2.4× and cell uptake by ∼2× relative to control. Encapsulation also increased total lutein bioaccessibility by 3–5× and cell uptake 2.3× relative to control. There was no significant difference between VitaDry® and VitaSperse® products in regards to Caco-2 cell uptake. Increased bioaccessibility largely drove increased carotenoid cell uptake from the encapsulated formulations. These results suggest further study is warranted to determine if this encapsulation approach increases carotenoid bioavailability in human studies. [ABSTRACT FROM AUTHOR]

The strategy for controlling the existence of radionuclides in drinking water depends upon an individual dose criterion (IDC) of 0.1 mSv/y, which represents a very low level of risk that is not expected to cause any identified adverse health effects. Radon gas, considered a carcinogenic radionuclide, can dissolve and accumulate in drinking water. Non-alcoholic carbonated beverages (NACBs), which mainly contain drinking water, phosphoric acid, citric acid, caffeine, and sugar, represent one of the most consumed groups worldwide and in Türkiye. In this study, the radon activity concentration and some physicochemical characteristics of 45 NACB samples from 24 most preferred commercial brands in Türkiye were determined to assess the radiological health risk associated with the ingestion of these samples. Radon activity concentrations measured in NACB samples using the AlphaGUARD radon analyzer ranged from 22.8 ± 0.7 to 54.9 ± 1.7 mBq/L. The pH, conductivity, total dissolved solids, and brix values in NACB samples ranged from 2.31 to 7.29, 401 to 3281 μSv/cm, 355 to 2453 mg/L, and 0.10 to 12.95%, respectively. Total (ingestion and inhalation) annual effective doses and the corresponding excess lifetime cancer risks estimated for adults to assess the radiological health risk are significantly below the IDC and advised safety limit (10−3), respectively. [ABSTRACT FROM AUTHOR]

Copyright of Nachrichten aus der Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Nachrichten aus der Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Nachrichten aus der Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The evaluation of oxidation and reduction potentials is a pivotal task in various chemical fields. However, their accurate prediction by theoretical computations, which is a complementary task and sometimes the only alternative to experimental measurement, may be often resource‐intensive and time‐consuming. This paper addresses this challenge through the application of machine learning techniques, with a particular focus on graph‐based methods (such as graph edit distances, graph kernels, and graph neural networks) that are reviewed to enlighten their deep links with theoretical chemistry. To this aim, we establish the ORedOx159 database, a comprehensive, homogeneous (with reference values stemming from density functional theory calculations), and reliable resource containing 318 one‐electron reduction and oxidation reactions and featuring 159 large organic compounds. Subsequently, we provide an instructive overview of the good practice in machine learning and of commonly utilized machine learning models. We then assess their predictive performances on the ORedOx159 dataset through extensive analyses. Our simulations using descriptors that are computed in an almost instantaneous way result in a notable improvement in prediction accuracy, with mean absolute error (MAE) values equal to 5.6 kcal mol−1 for reduction and 7.2 kcal mol−1 for oxidation potentials, which paves a way toward efficient in silico design of new electrochemical systems. [ABSTRACT FROM AUTHOR]

The dissociation of methane is not only an important reaction step in catalytic processes, but also of fundamental interest. Dynamical effects during the dissociative chemisorption of methane on metal surfaces cause significant differences in computed reaction rates, compared to what is predicted by typical transition state theory (TST) models. It is clear that for a good understanding of the catalytic activation of methane dynamical simulations are required. In this paper, a general blueprint is provided for performing dynamical simulations of the dissociative chemisorption of methane on metal surfaces, by employing either the quasi-classical trajectory or ring polymer molecular dynamics approach. If the computational setup is constructed with great care-since results can be affected considerably by the setup - chemically accurate predictions are achievable. Although this paper concerns methane dissociation, the provided blueprint is, so far, applicable to the dissociative chemisorption of most molecules. [ABSTRACT FROM AUTHOR]

The document discusses the significance of carbon nanotubes (CNTs) and nanosheets for sustainable solutions, highlighting their unique properties such as ultrahigh strength, thermal conductivity, and biocompatibility. The Special Issue features articles from various countries, showcasing global collaboration in nanotechnology research. Specific applications of CNTs are explored, including biomedical sensors, seed priming for agriculture, superconductivity, supercapacitors, road de-icing, vibration analysis, and defect engineering. The research presented in the document contributes to the advancement of nanotechnology and its potential applications in diverse fields. [Extracted from the article]

In the development of polymer electrolytes, the understanding of the complex interplay of factors that affect ion transport is of importance. In this study, the strongly coordinating and flexible poly (ethylene oxide) (PEO) is compared to the weakly coordinating and stiff poly (trimethylene carbonate) (PTMC) as opposing model systems. The effect of molecular weight (Mn) and end group chemistry on the physical properties: glass transition temperature (Tg) and viscosity (η) and ion transport properties: transference number (T+), ion coordination strength and ionic conductivities were investigated. The cation transference number (T+) showed the opposite dependence on Mn for PEO and PTMC, decreasing at low Mn for PTMC and increasing for PEO. This was shown to be highly dependent on the ion coordination strength of the system regardless of whether the end group was OH or if the chains were end‐capped. Although the coordination is mainly of the cations in the systems, the differences in T+ were due to differences in anion rather than cation conductivity, with a similar Li+ conductivity across the polymer series when accounting for the differences in segmental mobility. [ABSTRACT FROM AUTHOR]

Energy can exist in nature in a wide range of forms. Energy conversion refers to the process in which energy is converted from one form to another, and this process will be greatly enhanced by energy conversion sensitizers. Recently, an emerging class of new materials, namely liquid metals (LMs), shows excellent prospects as highly versatile materials. Notably, in terms of energy delivery and conversion, LMs functional materials are chemical responsive, heat‐responsive, photo‐responsive, magnetic‐responsive, microwave‐responsive, and medical imaging responsive. All these intrinsic virtues enabled promising applications in energy conversion, which means LMs can act as energy sensitizers for enhancing energy conversion and transport. Herein, first the unique properties of the light, heat, magnetic and microwave converting capacity of gallium‐based LMs materials are summarized. Then platforms and applications of LM‐based energy conversion sensitizers are highlighted. Finally, some of the potential applications and opportunities of LMs are prospected as energy conversion sensitizers in the future, as well as unresolved challenges. Collectively, it is believed that this review provides a clear perspective for LMs mediated energy conversion, and this topic will help deepen knowledge of the physical chemistry properties of LMs functional materials. [ABSTRACT FROM AUTHOR]

Developing mechanically robust and chemically tolerant coatings that maintain a high water content remains an extremely challenging task to pursue to date. Here, an optimum reinforcement of a hollow nano‐clay i.e., halloysite in a dual crosslinked and interpenetrating polymeric network is introduced to yield a high (≈95 wt%) water content coating with an ability to improve toughness (9.9 ± 0.6 MJm−3 Vs. 0.5 ± 0.03 MJ m−3) of a deformable fibrous substrate. The association of covalent and physical crosslinking chemistries provides essential tolerance against exposures to diverse severe chemically complex conditions, including extremes of pH, seawater, river water, and organic solvents. High water content in the prepared hydrogel network endows a robust bio‐inspired underwater nonadhesive superoleophobicity with oil contact angle of 160.7 ± 0.2° and force of oil‐droplet adhesion of 8.7 ± 0.3 µN. This approach provides a liquid selective filtrating membrane with ultrahigh crude oil/water separation efficiency (99.7%), superior intrusion pressure (3.5 ± 0.4 kPa), relatively high separation flux (11,162 Lm−2 h−1), and the ability to perform even when the surface tension of aqueous phase is brought down to similar of oily phase. Moreover, a mixture of immiscible, non‐aqueous liquids having differences in surface tension below 2.5 mN m−1 is successfully separated. [ABSTRACT FROM AUTHOR]

The therapeutic potential of two important flavonoids, i.e. hesperidin and naringenin, remains unutilized due to pharmacokinetics issues, especially poor aqueous solubility. Hydrotropic solid dispersions with different agents like sodium salicylate, niacinamide, benzoic acid, and urea etc. can change the solubility profile of poorly soluble drugs. The current study investigated the potential of different hydrotropic agents in improving the solubility of both natural bioactives. The hydrotropic solid dispersion in 1:3 w/w drug: sodium salicylate ratio showed maximum solubility and dissolution amongst all the tested hydrotropes. This novel and economical approach could be explored for other poorly soluble pharmaceuticals. [ABSTRACT FROM AUTHOR]

Excessive intake of iodine will do harm to human health. In recent years, high iodine groundwater has become a global concern after high arsenic and high fluorine groundwater. A deep understanding of the environmental factors affecting iodine accumulation in groundwater and the mechanism of migration and transformation is the scientific prerequisite for effective prevention and control of iodine pollution in groundwater. The paper comprehensively investigated the relevant literature on iodine pollution of groundwater and summarized the present spatial distribution and hydrochemical characteristics of iodine-enriched groundwater. Environmental factors and hydrogeological conditions affecting iodine enrichment in aquifers are systematically summarized. An in-depth analysis of the hydrologic geochemistry, physical chemistry, biogeochemistry and human impacts of iodine transport and transformation in the surface environment was conducted, the results and conclusions in the field of high iodine groundwater research are summarized comprehensively and systematically. Stable isotope can be used as a powerful tool to track the sources of hydrochemical components, biogeochemistry processes, recharge sources and flow paths of groundwater in hydrogeological systems, to provide effective research methods and means for the study of high iodine groundwater system, and deepen the understanding of the formation mechanism of high iodine groundwater, the application of isotopic technique in high iodine groundwater is also systematically summarized, which enriches the method and theory of high iodine groundwater research. This paper provides more scientific basis for the prevention and control of groundwater iodine pollution and the management of groundwater resources in water-scarce areas. [ABSTRACT FROM AUTHOR]

At this time in Indonesia, much illegal sand mining is negatively impacting the environment. One area where many Illicit mining activities are found is the Gantar area and its surroundings, West Java Province. Sand mining activities using an open pit mining system. The open pit mining system degrades soil quality by mining sand. This study uses laboratory analysis by measuring the physical, chemical, and mineralogy of soils. The purposive sampling method is used to sample post-mining ex-sand mining soil samples in Gantar District, West Indramayu Regency, West Java Province. Physical soil quality measurement is characterized by increased bulk density, particle density, fine fractions (clay and silt), and decreased porosity and permeability. Chemical examination showed a decrease in C-organic, N-organic, P, and K concentrations (available) and base saturation; however, the CEC level increased. The results showed that sand mining activities have degraded soil quality in the former sand mining area in Gantar District, West Java, Indonesia. This research makes a major contribution to policymakers to pay attention to post-mining activities so that the decline in soil quality can be avoided. [ABSTRACT FROM AUTHOR]

Mn doping has been used to improve the physical chemistry of lead halide perovskite nanocrystals such as CsPbX3, where X is a halogen ion. In this paper, a two‐phase method for Mn‐doped CsPbX3 nanosheets (where X=Br, Cl), namely water‐hexane system, is reported. Compared to conventional catalyst arrays, the band gap of CsPbBr3 nanocrystalline is easily tuned, the carrier diffusion distance is remote, the band edge position of the band structure is favorable for a wide range of electrocatalytic redox reactions, and the catalytic active site is maximally exposed, providing a larger electrolyte contact area. The porous hierarchical structure also accelerates the release of hydrogen bubbles. The results showed that the optimized Mn : CsPbBr3 catalyst exhibited excellent electrolytic performance of aquatic hydrogen in alkaline electrolyte (1 mol/L KOH). The overpotentials of the oxygen evolution reaction (OER) at the current densities of 10 and 100 mA cm−2 are only 114.4 and 505.4 mV, respectively, with a Tafel slope of 43 mV dec−1. At a current density of 10 mA cm−2, the excess potential required for the hydrogen evolution reaction (HER) is 158.6 mV and it exhibits excellent electrochemical stability. The Mn : CsPbBr3 nanocrystalline consists of two electrodes for hydrolysis of water, requiring only a voltage of 1.45 V. This provides implications for the optimization of electrocatalysts in alkaline electrolytes with the aim of developing next generation 2D electrocatalysts for overall water splitting. [ABSTRACT FROM AUTHOR]

Resveratrol (RSV), as a natural polyphenol exhibiting antioxidative properties, is studied in the treatment of neurodegenerative diseases. However, RSV has low oral bioavailability. In this study and in order to overcome the issue, RSV was encapsulated into the solid lipid nanoparticles (SLNs). In this study, RSV‐loaded solid lipid nanoparticles (RSV‐SLNs) were prepared by the solvent emulsification‐evaporation technique, and their physicochemical properties were optimized using Box–Behnken response surface methodology. The morphology of the particles was evaluated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The neuroprotective effects of the nanoparticles were investigated in animal models using the Morris water maze (MWM). Then after, the rats were sacrificed, their brains were collected, and the extent of lipid peroxidase (LPO) as well as the level of reduced glutathione (GSH) were determined in the hippocampus section samples. Finally, the collected brain tissues were histologically studied. The particle size, polydispersity index (PDI), zeta potential, entrapment efficiency (EE%), and drug loading (DL%) of the optimized nanoparticles were 104.5 ± 12.3 nm, 0.322 ± 0.11, −3.1 ± 0.15 mV, 72.9 ± 5.31% and 14.6 ± 0.53%, respectively. The microscopic images revealed spherically shaped and nonaggregated nanoparticles. The in vivo studies demonstrated higher efficiency of RSV‐SLN in the reduction of escape latency time and improvement in the time spent in the target quadrant compared to free RSV. Moreover, it was demonstrated that RSV‐SLN posed a higher potency in the reduction of LPO as well as elevation of the GSH levels in the brain samples. The histological studies revealed a decline in neural degeneration and an improvement in the CA1 pyramidal cell morphology. The obtained data revealed that RSV‐SLNs caused more reduction in Alzheimer‐related symptoms rather than free RSV. [ABSTRACT FROM AUTHOR]

This article explores the relationship between the spontaneity of chemical reactions and time travel. It explains the concept of spontaneity in chemical reactions and its connection to the Second Law of Thermodynamics. The article also discusses the Gibbs free energy and how it determines the spontaneity of chemical reactions. Additionally, it delves into the concept of chemical potential and its relationship to Gibbs free energy and the Second Law of Thermodynamics. The author concludes by discussing the limitations of time travel and the potential for future scientific discoveries. [Extracted from the article]

Background: The variational method, a quantum mechanical approach, estimates effective charge distributions and ground-state energy by minimizing the Hamiltonian's expectation value using trial wave functions with adjustable parameters. This method provides valuable insights into system behavior and is widely used in theoretical chemistry and physics. This paper aims to investigate ground-state energies and isoelectronic sequences using the variational method, introducing a novel approach for analyzing multi-electron systems. This technique allows for determining effective charge values and ground-state energies for 2–5 electrons sequence up to Z ≤ 20. Hydrogenic wave functions are used as a trial wave function to calculate effective charge in 1 s, 2 s, and 2p states. Two varying parameters were used to calculate an approximate wave function for the system. These values are then used in non-relativistic Hamiltonian with electron–electron interaction terms to calculate the ground-state energy of an atom. Result: The results align with the reported experimental values, showing a marginal 1% error. Conclusion: A Python algorithm is established based on the variational principle. It was found that, based on a few selected parameters in scripting the program, a very promising result was obtained. Furthermore, adding more variational parameters can minimize the difference between experimental and theoretical values, and this technique can be extended to elements with higher atomic numbers. [ABSTRACT FROM AUTHOR]

Herein, we study the London dispersion forces between organic structure directing agents (OSDAs)—here tetraalkyl-ammonium or -phosphonium molecules—and silica zeolite frameworks (FWs). We demonstrate that the interaction energy for these dispersion forces is correlated to the number of H atoms in OSDAs, irrespective of the structures of OSDAs or FWs, and of variations in charges and thermal motions. All calculations considered—DFT-D3 and BOMD undertaken by us, and molecular mechanics from an accessible database—led to the same trend. The mean energy of these dispersion forces is ca. −2 kcal.mol−1 per H for efficient H-O contacts. [ABSTRACT FROM AUTHOR]

Simple Summary: Non-small cell lung cancer (NSCLC) is marked by low survival and resistance to platinum-based chemotherapy. Recent studies have emphasized the critical role of DNA repair mechanisms in NSCLC tumorigenesis and response to treatment. XPG endonuclease, a crucial component of the Nucleotide Excision Repair (NER) pathway, has emerged as a promising biomarker of clinical outcome in advanced NSCLC and its downregulation improved cisplatin efficacy by increasing DNA damage. However, so far, no study has been carried out with the purpose of identifying XPG inhibitors. This work thus aims to discover potential small-molecule inhibitors of XPG to be used in combination with cisplatin therapy to enhance its efficacy in NSCLC patients. NSCLC is marked by low survival and resistance to platinum-based chemotherapy. The XPG endonuclease has emerged as a promising biomarker for predicting the prognosis of cisplatin-treated patients and its downregulation having been reported to increase cisplatin efficacy. This study presents an integrated strategy for identifying small molecule inhibitors of XPG to improve cisplatin therapy in NSCLC. A structure-based virtual screening approach was adopted, including a structural and physicochemical analysis of the protein, and a library of small molecules with reported inhibitory activities was retrieved. This analysis identified Lys84 as a crucial residue for XPG activity by targeting its interaction with DNA. After molecular docking and virtual screening calculations, 61 small molecules were selected as potential XPG inhibitors, acquired from the ChemBridge database and then validated in H1299 cells, a NSCLC cell line exhibiting the highest ERCC5 expression. The MTS assay was performed as a first screening approach to determine whether these potential inhibitors could enhance cisplatin-induced cytotoxicity. Overall, among the eight compounds identified as the most promising, three of them revealed to significantly increase the impact of cisplatin. The inherent cytotoxicity of these compounds was further investigated in a non-tumoral lung cell line (BEAS-2B cells), which resulted in the identification of two non-cytotoxic candidates to be used in combination with cisplatin in order to improve its efficacy in NSCLC therapy. [ABSTRACT FROM AUTHOR]

Benzodiazepines are frequently encountered in crime scenes, often mixed with adulterants and diluents, complicating their analysis. This study investigates the interactions between two benzodiazepines, lorazepam (LOR) and alprazolam (ALP), with common adulterants/diluents (paracetamol, caffeine, glucose, and lactose) using infrared (IR) spectroscopy and quantum chemical methods. The crystallographic structures of LOR and ALP were optimized using several functionals (B3LYP, B3LYP-D3BJ, B3PW91, CAM-B3LYP, M05-2X, and M06-2X) combined with the 6-311++G(d,p) basis set. M05-2X was the most accurate when comparing experimental and theoretical bond lengths and angles. Vibrational and 13C NMR spectra were calculated to validate the functional's applicability. The differences between LOR's experimental and theoretical IR spectra were attributed to intramolecular interactions between LOR monomers, examined through density functional theory (DFT) optimization and quantum theory of atoms in molecules (QTAIM) analysis. Molecular dynamics simulations modeled benzodiazepine–adulterant/diluent systems, predicting the most stable structures, which were further analyzed using QTAIM. The strongest interactions and their effects on IR spectra were identified. Comparisons between experimental and theoretical spectra confirmed spectral changes due to interactions. This study demonstrates the potential of quantum chemical methods in analyzing complex mixtures, elucidating spectral changes, and assessing the structural stability of benzodiazepines in forensic samples. [ABSTRACT FROM AUTHOR]

Nonadiabatic molecular dynamics (NA-MD) is a powerful tool to model far-from-equilibrium processes, such as photochemical reactions and charge transport. NA-MD application to condensed phase has drawn tremendous attention recently for development of next-generation energy and optoelectronic materials. Studies of condensed matter allow one to employ efficient computational tools, such as density functional theory (DFT) and classical path approximation (CPA). Still, system size and simulation timescale are strongly limited by costly ab initio calculations of electronic energies, forces, and NA couplings. We resolve the limitations by developing a fully machine learning (ML) approach in which all the above properties are obtained using neural networks based on local descriptors. The ML models correlate the target properties for NA-MD, implemented with DFT and CPA, directly to the system structure. Trained on small systems, the neural networks are applied to large systems and long timescales, extending NA-MD capabilities by orders of magnitude. We demonstrate the approach with dependence of charge trapping and recombination on defect concentration in MoS2. Defects provide the main mechanism of charge losses, resulting in performance degradation. Charge trapping slows with decreasing defect concentration; however, recombination exhibits complex dependence, conditional on whether it occurs between free or trapped charges, and relative concentrations of carriers and defects. Delocalized shallow traps can become localized with increasing temperature, changing trapping and recombination behavior. Completely based on ML, the approach bridges the gap between theoretical models and realistic experimental conditions and enables NA-MD on thousand-atom systems and many nanoseconds. [ABSTRACT FROM AUTHOR]

The given text is a list of names and initials, likely of authors or researchers, along with various page numbers and abbreviations. It does not provide any information or content that can be summarized. The purpose or context of this list is unclear, as there is no accompanying information or explanation provided. [Extracted from the article]

Metal‐based nanoparticles (NPs) have entered clinical use for enhancing radiotherapy, but the underlying mechanisms remain ambiguous. Herein, single‐cell analysis of two cell lines in response to megavolt irradiation and a radiomimetic drug, neocarzinostatin (NCS) after coculture with gold NPs with different surface coatings, polyethylene glycol (AuPEG), PEG, and transferrin (AuT) or silica (AuSiO2), is reported. Different surface chemistry presents a major challenge for objective comparison between the biological impacts where major differences in cell‐uptake exist. AuSiO2 NPs are the most efficient for promoting radiosensitization despite being associated with cells 10 times less than the actively targeted AuT NPs. Conversely, for cells exposed to NCS, AuSiO2 NPs impede the radiomimetic action and promote cell survival. AuT NPs enhance death of cells in combination with NCS showing that NPs can sensitize against cytotoxic agents in addition to radiation. While NPs contribute to radiosensitization (or enhancing/impeding chemotherapeutic drug activity), due to cell and cell line heterogeneity, the ultimate radiosensitivity of a cell appears to be dominated by its inherent radiosensitivity and how this cell‐regulated response is manipulated by NPs. This is evidenced through comparison of radiobiological response of cells with equivalent NP association rather than equivalent coculture conditions. [ABSTRACT FROM AUTHOR]

Nickel transition metal complexes have shown various biological activities that depend on the ligands and geometry. In this contribution, six Ni(II) nitrate complexes with pyridoxal-semi, thiosemi, and isothiosemicarbazone ligands were examined using theoretical chemistry methods. The structures of three previously reported complexes ([Ni(PLSC)(H2O)3]∙2NO3−, [Ni(PLTSC)2] ∙2NO3−∙H2O, and [Ni(PLITSC)(H2O)3]∙2NO3−) were investigated based on Hirshfeld surface analysis, and the most important stabilization interactions in the crystal structures were outlined. These structures were optimized at the B3LYP/6-311++G(d,p)(H,C,N,O,(S))/LanL2DZ(Ni) level of theory, and the applicability was checked by comparing theoretical and experimental bond lengths and angles. The same level of theory was applied for the optimization of three additional structures, ([Ni(PLSC)2]2+, [Ni(PLTSC)(H2O)3]2+, and [Ni(PLITSC)2]2+). The interactions between selected ligands and Ni(II) were examined using the Natural Bond Orbital (NBO) and Quantum Theory of Atoms in Molecules (QTAIM) approaches. Particular emphasis was placed on interactions between oxygen, sulfur, and nitrogen donor atoms and Ni(II). Human Serum Albumin (HSA) and the DNA-binding properties of these complex cations were assessed using molecular docking simulations. The presence of water molecules and various substituents in the thermodynamics of the processes was demonstrated. The results showed significant effects of structural parameters on the stability and reactivity towards important biomolecules. [ABSTRACT FROM AUTHOR]

We have developed a homemade sugar-based light experimental platform by specially designing an optical analyzer, allowing us to observe paper-cut art and dynamic rainbow boards. Moreover, by substituting the central sugar solution with sugar building blocks, we can create neon-colored building blocks. This apparatus is easy to set up and operate, with a clear and concise principle, meeting the requirements of popular science activities for safety, flexibility, and engaging demonstrations. Through observing the shifting colors, students can personally delve into the mysteries of the interaction between light and optically active molecules, thereby enhancing their appreciation of the beauty of physical chemistry. [ABSTRACT FROM AUTHOR]

Against the backdrop of the Snowflake Castle collapse and through the dialogue between Little Snowflake and the Doctor, this paper introduces the main components, principles of action, and applications of snow melting agents. Using snow melting agents as an example, it further explores the concept of colligative properties of dilute solutions, their related applications, and the methods of using snow melting agents. The aim is to familiarize readers with the concept of colligative properties in physical chemistry and to promote the concept of environmental protection. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) have garnered extensive interest in basic physical chemistry as well as in biomedical applications due to their low cost, good biocompatibility, and great aqueous solubility. However, the synthesis of multi-functional carbon dots has always been a challenge for researchers. Here, we synthesized novel CDs with a high quantum yield of 28.2% through the straightforward hydrothermal method using Diaminomaleonitrile and Boc-D-2, 3-diaminopropionic acid. The size, chemical functional group, and photophysical properties of the CDs were characterized by TEM, FTIR, XPS, UV, and fluorescence. It was demonstrated in this study that the prepared CDs have a high quantum yield, excellent photostability, and low cytotoxicity. Regarding the highly water-soluble property of CDs, they were proven to possess selective and sensitive behavior against Cu2+ ions (linear range = 0–9 μM and limit of detection = 1.34 μM). Moreover, the CDs were utilized in fluorescent ink in anti-counterfeiting measures. Because of their low cytotoxicity and good biocompatibility, the CDs were also successfully utilized in cell imaging. Therefore, the as-prepared CDs have great potential in fluorescence sensing, anti-counterfeiting, and bioimaging. [ABSTRACT FROM AUTHOR]

Fruit juices (FJs) are among the most popular beverages frequently preferred by consumers, believing FJs contain the nutritional values, minerals, phytochemicals, vitamins, and antioxidants necessary for a healthy life. However, FJs may contain natural radionuclides such as radon (222Rn), which originates from the fruit and water utilized in their production, at levels that may pose a health risk to people. Inhalation and ingestion of 222Rn gas increases the risk of lung and stomach cancer. In this study, commercially packaged FJs from the seventeen most popular brands consumed in Turkey were analyzed for physicochemical properties and 222Rn activity concentrations to evaluate the radiological health risk. The values of pH, brix and 222Rn activity concentrations in FJ samples varied from 2.68 to 4.28, 2.50 to 14.30%, 9.6 ± 1.1 to 25.2 ± 2.5 mBq/L, respectively. The radiological health risk caused by internal exposure was evaluated for children and adults by estimating the ingestion and inhalation annual effective dose. The average values of the total annual effective dose for children and adults were found as 0.039 µSv and 0.056 µSv, respectively, which are much lower than the recommended dose of 100 µSv for drinking water. [ABSTRACT FROM AUTHOR]

This article provides a personal account of the author's career in mass spectrometry, both in the United States and Spain. The author discusses their training in the US and their work with Dr. John Oró at the University of Houston, as well as their experiences with mass spectrometry and gas chromatography. They also mention their involvement in NASA research programs and the social and historic events they witnessed during their time in the US. The article then focuses on the challenges faced by the author in establishing a biomedical mass spectrometry laboratory in Spain, including the lack of support and funding for research. Despite these difficulties, the author and their team managed to publish papers and graduate students. The text also discusses the author's efforts to promote the use of biomedical mass spectrometry in Spain, including organizing international symposiums and meetings. The author reflects on the advancements in mass spectrometry technology during this time period. They also discuss their involvement in the organization of international conferences and the development of biomedical mass spectrometry in Spain. The author served on scientific committees and played a key role in organizing the 15th International Mass Spectrometry Conference in Barcelona in 2000. They also discuss the challenges and successes of their research group, including the creation of a proteomics MS lab. The author reflects on their career in the field of mass spectrometry, particularly in the medical community in Spain. They discuss the challenges they faced in conducting research and the lack of available resources and facilities. [Extracted from the article]

The development of density functional theory (DFT) has significantly enhanced the use of computational chemistry as a tool in the design and development of ligands for the separation of actinides (An) and lanthanides (Ln) in the nuclear waste management. In the past, identifying new ligands involved either making incremental structural changes to existing ligands or conducting extensive laboratory testing of numerous compounds. However, these experimental methods are often costly and time-consuming. With the advancements in hardware and software, theoretical and computational chemistry has become a powerful and cost-effective approach in nuclear waste management research. The density functional theory (DFT), in particular, has played a pivotal role by enabling scientists to accurately predict the effectiveness of ligands based on electronic and molecular properties, as well as reactivity indices. This computational approach provides valuable insights into the separation efficiencies of ligands without the need for extensive experimental efforts. This review highlights the role of computational chemistry in the design of ligands for the separation of lanthanides and actinides in spent nuclear fuel processing. It discusses various design strategies and computational analyses used in ligand optimization, highlighting the potential applications of computational tools in guiding ligand design and improving separation processes. The work emphasizes the synergy between computational insights and experimental observations in lanthanide/actinide chemistry, which enhances understanding of complex phenomena and aids in the interpretation of experimental results. It also explores different design approaches that allow for fine-tuning of ligand properties and selectivity toward specific metal ions, ultimately improving separation efficiency. In this review, we will discuss some widely used computational tools in chemistry without delving into complex mathematical formulas. This will be particularly helpful for researchers who come from an experimental background and may not be as familiar with advanced mathematical concepts. The tools covered are bond order analysis, population analysis, quantum theory of atoms in molecules (QTAIM) analysis, Energy Decomposition Analysis (EDA), and thermodynamic analysis. These methods are explored in a more accessible manner for non-theoretical researchers. They provide valuable insights into bonding, binding, stability, non-bonding interactions, coordinating abilities and selectivity of organic ligands in extraction of actinides and lanthanides, thus providing useful information in the designing of ligands to enhance separation strategies. This review serves as an excellent resource for future ligand design, offering valuable insights into computational techniques used to understand the coordination and complexation behaviors of ligands. Also an attempt has been made to understand the role of DFT functionals in the calculations. It provides a foundation for researchers to comprehend and apply computational tools effectively in their investigations. [ABSTRACT FROM AUTHOR]

A pair of atropisomers secofumitremorgins C (1a) and D (1b), together with fifteen known alkaloids (2-16), were isolated from a saltern-derived fungus Aspergillus fumigatus GXIMD00544. The structures of atropisomers 1a and 1b were elucidated by the detailed spectroscopic data, chemical reaction and quantum chemical calculations. Compounds 1 and 8 displayed antifungal spore germination effects against plant pathogenic fungus associated with sugarcane Fusarium sp. with inhibitory rates of 53% and 77% at the concentration of 100 µM, repectively. Atropisomers 1 also exhibited antifouling potential against Balanus amphitrite larval settlement with an inhibitory rate of 96% at the concentration of 100 µM. [ABSTRACT FROM AUTHOR]

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Molecular‐level understanding of photoinduced processes is critically important for breakthroughs in transformative technologies utilizing light, ranging from photomedicine to photoresponsive materials. Theory and simulation play a crucial role in this task. Despite great advances in hardware and computational methods, the theoretical description of photoinduced phenomena in the presence of complex environments and external photoexcitation conditions still poses formidable challenges for theoreticians and there are numerous formal and computational difficulties that must be overcome. The development of predictive, accurate, and at the same time, computationally efficient theoretical approaches to describe complex problems in photochemistry and photophysics is an active field of research in contemporary theoretical and computational chemistry. In this advanced review, we discuss modern computational advances and novel approaches that have been recently developed in excited‐electronic structure methods, and multiscale modeling, with a special emphasis on coupled electron‐nuclear dynamics and spectroscopy, from fully quantum to semi‐classical methodologies—including dissipative effects, the explicit light field interaction, femtosecond time‐resolved spectroscopy, and software infrastructure. This article is categorized under:Software > Quantum ChemistryElectronic Structure Theory > Combined QM/MM MethodsTheoretical and Physical Chemistry > SpectroscopySoftware > Molecular Modeling [ABSTRACT FROM AUTHOR]

For the evolution of chemical engineering is useful the definition proposed by Kuhn, which defines a scientific paradigm as: "universally recognized scientific achievements that, for a time, provide model problems and solutions for a community of practitioners" (Kuhn, 1996).11 From the ancient times applied chemistry meant an art, a trade for obtaining salt, caustic soda, soap, sulfuric acid, sugar, glass-things in rudimentary workshops. Traditional recipes have been transferred with minor, empirical improvements gained from observation. This period can be considered as the empirical stage of chemical engineering. The development of the variety and the amounts of the chemical products, mainly in the last quarter of the 19th century, imposed a new stage, respectively the rational stage of chemical engineering. The empirical rules and practices were abandoned for rational scientific methods. The transition to this stage is especially owing to the great progresses of physical chemistry. In 1885 prof. H.E. Amstrong has taught at Central College of London the first chemical engineering course. In this course fundamental scientific training was combined with technical practice for design of chemical industry equipment. It may be considered that at this moment the rational stage of chemical engineering begins. In 1887 prof. Geoge Davies from Manchester Technical College has taught a lot of chemical engineering lessons. These lessons were the roots of his further Handbook of Chemical Engineering published in 1901. The practical value of Davies lessons from this book consists in the variety and abundance of the technical end economical data. Due to the lack of scientific explanations, in fact this book belongs to empirical stage and is a document of what meant chemical engineering at that stage Bratu. [ABSTRACT FROM AUTHOR]

To investigate the effects of metal fuels on the reactions of ammonium perchlorate (AP) oxidizer in propulsion sys¬tems, the energy release processes and reaction characteristics of two aluminum-based metal fuels, namely Al-Li alloy and Al-Mg alloy, were analyzed by TG-DSC, SEM, XRD, and a custom-designed combustion apparatus. The apparent activation en¬ergy was calculated by Kissinger method. The results reveals that the Al-Li alloy exhibits inhibitory effects on both the low-tem¬perature and high-temperature decomposition stages of AP, which elevates decomposition peak temperatures for both stages. In contrast, the Al-Mg alloy has a strong promoting effect on the low-temperature decomposition stage of AP, lowering the de¬composition peak temperature to 287. 3 °C . The addition of Al-Li alloy results in an apparent activation energy of 129. 7 kj/mol for the first decomposition stage of AP and approximately 247.0kJ/mol for the second stage. Conversely, the addition of Al-Mg alloy leads to a negative apparent activation energy ( - 207. 2 kj/mol) for the first decomposition stage of AP. Additional¬ly, in the Al-Mg alloy/AP system, a vigorous decomposition of AP is observed, accompanied by the generation of a prominent gaseous flame during sample combustion. In this process, aluminum and magnesium are nearly fully consumed. However, in the Al-Li alloy/AP system, aluminum is still detected among the combustion products. [ABSTRACT FROM AUTHOR]

Aiming at the pyrolysis and combustion process of the near burning surface of the pasty propellant, the laser ignition combustion experiment of the pasty propellant were carried out. At the same time, the pyrolysis and combustion characteristics of the near burning surface region of the pasty propellant were studied based on the multiphase chemical reaction numerical sol¬ver developed by the research group and the 14-component and 14-primitive chemical reaction equation. The macroscopic structure of propellant combustion flame was obtained through experiments and the burning rate of the pasty propellant was measured under constant pressure conditions. The combustion flame structure and chemical reaction sequence of the pasty pro¬pellant under constant pressure conditions were analyzed by numerical calculations. The effects of different ambient pressure on the combustion process of the pasty propellant were calculated. The results show that the fitted burning rate curve was in good agreement with the experimental results. In the range of experimental pressure, the burning rate of propellant in the combustion chamber of pasty rocket engine could be predicted well. The decomposition of AP is the first reaction in the combustion of pasty propellant, and the higher ambient pressure limited the diffusion of primary combustion gases, but enhanced the thermal feedback effect on the pasty domain, which increased the burning rate of the pasty propellant. [ABSTRACT FROM AUTHOR]

Carbon nanofibers (CNFs) are introduced into the nitroguanidine gun propellant system to investigate its effects on structure and properties of the gun propellant. The structure and composition of the sample are characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy (Raman). Differential scanning calorimetry (DSC) is used to analyze the thermal decomposition behavior and kinetics of the propellant by the Kissinger and the Ozawa methods. The effect of CNFs on the combustion performance of nitroguanidine gun propellant is studied by closed bomb test, and the impact strength tests are carried out. The results show that the structure of nitroguanidine gun propellant modified by CNFs is stable. Compared with the blank sample, the activation energy (fa) of thermal decomposition of the gun propellant sample containing 1 % (mass fraction) CNFs increases from 200. 62kJ/mol to 208. 65kJ/mol, reflecting the improvement of thermal stability. The gun propellant containing CNFs can burn steadily and appropriate amount of CNFs have a good regulatory effect on its combustion process. In addition, adding appropriate amount of CNFs can effectively improve the impact strength of the propellant. The impact strength of the sample with 0.5% CNFs is improved by 26. 03% compared with the blank sample at low temperature. [ABSTRACT FROM AUTHOR]

The random packing structures of five types of explosive molding granular samples were investigated using X-ray mi¬crotomography to obtain the parameters, including granule spatial arrangement, packing characteristics, and granule contact features. The results show that the random packing system of molding granules exhibits a certain degree of size segregation, with larger granules tending to distribute at the bottom of the container. The filling process affects the horizontal orientation of granule distribution. The average packing efficiency of each sample varies continuously as granular radial distance increases, in¬dicating a long-range disorder in the random packing structure of the molding granules. The average contact number of the sam¬ples is 5--6, suggesting a random loose packing of spherical granules. However, due to the impact of the radius and morphol¬ogies, the volume fraction of granular random packing systems can exceed the limit of random close packing for spherical gran¬ules (0. 64) . The particles formed by the packing system of molding granules in local contact are unevenly distributed in terms of quantity, size, and morphology, but the contact angle around 60° is the most frequent among various contact structures, forming a contact angle distribution with a single characteristic peak around 60°. [ABSTRACT FROM AUTHOR]

In order to study the heat-induced damage evolution of GAP/AP/RDX/AI composite solid propellants under heating conditions, two GAP-based propellants with different RDX/AP contents were prepared, and the thermal decomposition proper¬ties of the samples were characterized by TG-DSC-IR technology. The samples were heated with a heating device, and the CT profile image, 3D pore distribution map, porosity and pore size distribution of the two propellant samples were obtained under different heating temperatures (50--130°C ), heating times (5--35min) and heating areas (25%, 50% and 87. 5% surface area) through micro-CT imaging and three-dimensional reconstruction of scanning images. The results show that the pores in the initial sample of GAP propellant are mainly the initial pores inside solid particles such as AP and RDX, and the thermal damage pores are mainly the interface dewedding pores between solid particles and the adhesive matrix, the pores generated after the matrix decomposition, and the initial structural defects. The pore damage size of GAP propellant after heating at 130°C increases significantly compared with the initial sample, and the higher the RDX content, the greater the damage degree of the sample after thermal stimulation. [ABSTRACT FROM AUTHOR]