Chemical Components Research Articles

Chemical and Biological Prospection of Marine Sponges Belonging to the Class Demospongiae: A Review.

Marine sponges belonging to the class Demospongiae have shown to be promising sources of bioactive compounds. This review aimed to compile studies on the biological activities and chemical components of sponge species from this class, highlighting the structure/activity relationship. Data collection was conducted using the Science Direct, PubMed, Scielo, Web of Science and Google Scholar databases, employing the following descriptors: antimicrobial marine sponges, antioxidant marine sponges, and biological activity of marine sponges. The inclusion criteria were: (1) publications from the year 2022 onwards; (2) written in English or Portuguese; and (3) that evaluated biological activities. Exclusion criteria included: (1) duplicate studies; (2) studies that were not within the scope; and (3) studies that did not evaluate biological activities. As a result of this survey, it was possible to isolate and identify 262 compounds from different metabolic classes, with terpenes, lipids, and alkaloids being highlighted. The extracts, fractions, and isolates were investigated for their antioxidant, antimicrobial, anti-inflammatory, and cytotoxic properties. The sponges demonstrated broad-spectrum antimicrobial potential and cytotoxic potential against various cancer cell lines. Based on data analysis, it is concluded that the studied compounds show promise for the development of drugs for microorganism control and cancer treatment, acting through different mechanisms of action.

A Network Pharmacological Study of Qianjin Sanhuang Decoction in the Treatment of Osteoarthritic Knee Disease

Objective: To predict the action targets of Qianjin Sanhuang decoction in the treatment of knee osteoarthritis through network pharmacology, to explore its potential multi component, multi target, multi, pathway mechanism of action, and to elaborate the relationship between the pharmacological effects of the drug and the disease from the perspective of molecular mechanism. Methods: The Chinese herbal composition of Qianjin Sanhuang decoction was determined by reading ancient texts and reviewing data, and the chemical components of Qianjin Sanhuang decoction were collected through the Traditional Chinese Medicine Systematic Pharmacology Database and Analysis Platform (TCMSP), and the active ingredients of the drug were obtained after oral utilization (OB) and drug-like properties (DL) screening, and the active ingredient target prediction was performed, while the active ingredient targets were retrieved from GeneCards, OMIM, and DisGeNet database to retrieve knee osteoarthritis-related targets. After taking the intersecting targets, a software called cytoscape 3.9.0 was used for mapping, with the goal of constructing a component-target network map, followed by a string database for mapping, with the goal of making a network map of target protein-target protein interactions, and finally, a gene ontology (GO) enrichment analysis and a Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, this analysis process was performed in the metascape database. Results: A total of 1272 targets related to osteoarthritis of the knee were collected in this study, 89 active ingredients of Qianjin Sanhuang decoction, involving 267 targets, and 121 therapeutic targets involving osteoarthritis of the knee, and the results of GO enrichment analysis showed that it involved the response to inorganic substances, positive regulation of cell migration, response to oxygen content, response to lipopolysaccharide, response to peptides, regulation of cell adhesion, response to extracellular stimuli, negative regulation of cell differentiation, positive regulation of cell death, glandular development, regulation of apoptotic signaling pathways, development of reproductive structures, response to trauma, response to growth factors, regulation of inflammatory response, cellular response to organic recycling compounds, regulation of proteolysis, etc. After KEGG analysis, the results showed that signaling pathways such as AGE-RAGE pathway and HIF-1 pathway were involved. Conclusion: Qianjin Sanhuang decoction can improve the inflammatory response of knee osteoarthritis through potential multi-pathways, multi-targets and multi-pathways, and can have potential therapeutic effects on osteoarthritis.

Phytochemistry, antibacterial and antioxidant properties from Adinandra hongiaoensis and Polyspora huongiana (Theaceae)

Adinandra hongiaoensis and Polyspora huongiana are the rare and native species found in Vietnam. Firstly, the present studies demonstrated the chemical components, antioxidant and antibacterial effects of the acetone extracts from these plants. Here, a total of 54 constituents are identified in the leaf extracts of 2 studied species using the gas chromatography/mass spectrometry (GC/MS) method. The P. huongiana extract displayed activity against 3 Staphylococcus strains, including S. saprophyticus, S. aureus ATCC 29213 and S. aureus ATCC 25923 while the A. hongiaoensis extract was not active any studied bacteria. In addition, A. hongiaoensis and P. huongiana extracts was found effective against the DPPH radical scavenger with IC50 value of 213.31 and 47.60 µg/mL respectively. Hopefully, the results of this report will provide a premise further research to apply these species in pharmaceutical product development in the future.

Empirical Stability Criteria for 3D Hierarchical Triple Systems. I. Circumbinary Planets

In this work we revisit the problem of the dynamical stability of hierarchical triple systems with applications to circumbinary planetary orbits. We derive critical semimajor axes based on simulating and analyzing the dynamical behavior of 3 × 108 binary star–planet configurations. For the first time, three-dimensional and eccentric planetary orbits are considered. We explore systems with a variety of binary and planetary mass ratios, binary and planetary eccentricities from 0 to 0.9, and orbital mutual inclinations ranging from 0° to 180°. Planetary masses range between the size of Mercury and the lower fusion boundary (approximately 13 Jupiter masses). The stability of each system is monitored over 106 planetary orbital periods. We provide empirical expressions in the form of multidimensional, parameterized fits for two borders that separate dynamically stable, unstable, and mixed zones. In addition, we offer a machine learning model trained on our data set as an alternative tool for predicting the stability of circumbinary planets. Both the empirical fits and the machine learning model are tested for their predictive capabilities against randomly generated circumbinary systems with very good results. The empirical formulae are also applied to the Kepler and TESS circumbinary systems, confirming that many planets orbit their host stars close to the stability limit of those systems. Finally, we present a REST application programming interface with a web-based application for convenient access to our simulation data set.

CANNABIS: USO TERAPÊUTICO E DESAFIOS PARA SUA APLICABILIDADE MEDICINAL NO BRASIL

Introduction: The legalization of medicinal marijuana use has been a controversial and constantly debated topic in recent years worldwide. Marijuana, also known as cannabis, is a plant that contains various chemical components, including THC (tetrahydrocannabinol) and CBD (cannabidiol), which are the main compounds responsible for its medicinal effects. Although many countries have already established regulations for the therapeutic use of cannabis, there are still many barriers to overcome. Objective: To explore the methodology of therapeutic use and the challenges for the application of cannabis, focusing on its medicinal use, identifying notable challenges and the regulatory aspects involved. Methodology: This study is based on a bibliographic review with a qualitative methodology, centered on the subjective nature of the verified bibliography through literary studies. The works reviewed were published between 2020 and 2023, collected from three main sources: LILACS and PUBMED databases. Results: The review identified significant evidence pointing to the therapeutic potential of Cannabis sativa L., particularly in the treatment of neurological conditions such as epilepsy, multiple sclerosis, and anxiety disorders. However, it also highlighted the major regulatory challenges faced in countries like Brazil, where the cultivation of cannabis for medicinal purposes remains prohibited. This prohibition increases treatment costs and limits accessibility for patients. Additionally, the results revealed a growing acceptance among healthcare professionals and patients, suggesting a likely increase in the demand for medicinal cannabis in the coming years. Conclusion: Although there is robust evidence supporting the efficacy of cannabis for medicinal purposes, significant regulatory and legal barriers remain, particularly in countries with restrictive policies. A reformulation of regulatory frameworks is urgently needed to expand patient access and promote the development of local medicinal cannabis industries. Further investment in scientific research is also essential to ensure that regulatory decisions are based on comprehensive and context-specific data.

Cluster radioactivity of heavy elements within an improved Coulomb and Proximity potential model

The Coulomb and Proximity potential Model (CPPM) is improved by introducing an accurate empirical expression for the nuclear surface diffuseness parameter in the expression for the proximity potential. Within the improved CPPM, the decay half-lives of experimentally detected cluster emissions from heavy elements are calculated. The results of the calculations using the Universal Decay Law (UDL) [Qi et al., Phys. Rev. Lett. 103 (2009) 072501], the improved empirical formula of Sahu et al. (ImSahuB) [Wang et al., Chin. Phys. C 45 (2021) 044111], and the empirical formula of Horoi [J. Phys. G. Nucl. Part. Phys. 30 (2004) 945] are compared with the predictions of the improved CPPM. The lowest standard deviation is obtained for the predictions using the improved CPPM. The model’s predictive power increases significantly when the proximity potential is modified by including the diffuseness parameter. Furthermore, improved CPPM is employed to calculate the decay half-lives of undiscovered cluster emissions from heavy elements, a valuable information for upcoming experimental investigations. The calculated values are compared with the predictions of the UDL, Horoi formula and the improved empirical formula of Sahu et al. (ImSahuB). There is a high degree of agreement between the improved CPPM, UDL, and Horoi formula predictions. The ImSahuB formula predict decay half-life one or two order magnitudes lower than the predictions of the other models.

Light Absorption Properties of Brown Carbon Aerosol During Winter at a Polluted Rural Site in the North China Plain

Brown carbon aerosols (BrC), a subfraction of organic aerosols, significantly influence the atmospheric environment, climate and human health. The North China Plain (NCP) is a hotspot for BrC research in China, yet our understanding of the optical properties of BrC in rural regions is still very limited. In this study, we characterize the chemical components and light absorption of BrC at a rural site during winter in the NCP. The average mass concentration of PM1 is 135.1 ± 82.3 μg/m3; organics and nitrate are the main components of PM1. The absorption coefficient of BrC (babs,BrC) is 53.6 ± 45.7 Mm−1, accounting for 39.5 ± 10.2% of the total light absorption at 370 nm. Diurnal variations reveal that the babs,BrC and organics are lower in the afternoon, attributed to the evolution of planetary boundary layers. BrC is mainly emitted locally, and both the aqueous phase and the photooxidation reactions can increase babs,BrC. Notably, the babs,BrC is reduced when RH > 65%. During foggy conditions, reactions in the aqueous phase facilitate the formation of secondary components and contribute to the bleaching of BrC. This process ultimately causes a decrease in both the absorption Ångström exponent (AAE) and the mass absorption efficiency (MAE). In contrast, the babs,BrC, along with AAE and MAE, rise significantly due to substantial primary emissions. This study enhances our understanding of the light absorption of BrC in rural polluted regions of the NCP.

Role of Lignin in Moisture Interactions of Cellulose Microfibril Structures in Wood

Wood is a complex, multi‐component material with a variety of applications. The properties of wood are especially sensitive to its moisture content and comprehending wood–water interactions is thus paramount. Understanding of the moisture interactions of the wood polysaccharide components, cellulose microfibrils and hemicelluloses, is improving. However, the role of lignin remains less clear. In this work, X‐ray scattering measurements were carried out on delignified spruce undergoing a desorption‐adsorption cycle, and the results were compared to previous data from untreated wood. In addition, a molecular model of the cell wall nanostructure, including the main chemical components, was used to support the experimental results. Based on the small‐angle scattering, delignification affects the arrangement of cellulose microfibrils in the cell wall by increasing their packing distance. Wide‐angle scattering shows that delignification has no substantial effect on the cellulose crystal structure and how it changes with moisture. Both the scattering results and simulations suggest that lignin is a passive, rather than an active participant in the moisture response of microfibril bundles in wood cell walls. Small‐angle scattering from fully wet delignified wood reveals a contribution that can be assigned to aligned nanometer scale pores which close during drying.

E-Waste and Hazardous Elements: A Comprehensive Study of Chemical Components and Environmental Threats

Electronic waste, or "e-waste," has grown significantly as a result of the exponential rise of electronic gadgets and is currently one of the waste streams with the fastest rate of growth in the world. Many dangerous substances, such as organic pollutants like brominated flame retardants and heavy metals like lead, mercury, and cadmium, can be found in e-waste. The chemical components of e-waste are thoroughly analyzed in this work, with an emphasis on the identification, measurement, and health and environmental effects of these hazardous materials. According to study, e-waste improper disposal and unofficial recycling can release dangerous substances into the environment, posing a major risk to human health including endocrine disruption and neurological damage. This can result in soil, water, and air contamination. The results highlight the necessity of more advanced recycling technology, stringent laws, and environmentally friendly design principles in order to reduce these hazards. This study adds to the expanding body of information on e-waste and urges immediate action to mitigate the risks that electronic trash poses to the environment and public health.

Broad Temperature Plateau for High Piezoelectric Coefficient by Embedding PNRs in Singe‐Phase KNN‐Based Ceramics

AbstractTo date, the enormous potential of lead‐free piezoceramics in ultrasonic transducers and micro‐actuators has driven extensive research and development. Although the piezoelectric coefficient (d33) of lead‐free ceramics is improved unprecedentedly, the breakthrough in comprehensive performance is still a key issue, one of which is the inverse relationship between d33 and Curie temperature (TC), and the other is the temperature stability of piezoelectricity. Here, based on the synergistic optimization of the chemical component modulation and texture technology, the high Curie temperature (≈365 °C), high piezoelectric properties (d33 ≈331 pC/N, d33* ≈561 pm V−1) and advanced piezoelectric temperature stability are realized by embedded PNRs in the conceived and prepared lead‐free single phase 0.96((K0.5Na0.5)(Nb0.98Ta0.02)O3)‐0.01(Bi(Ni0.67Nb0.33)O3)‐0.03(Bi0.5K0.5)HfO3 texture ceramics. The d33 changes by only 2.0% when the temperature is increased from 25 to 100 °C (≈10.0% to 200 °C), while the electrical strain (d33*) changes by only 4.2% when the temperature is increased from 25 to 175 °C (≈9.8% to 200 °C), which is comparable to the commercial lead‐based materials (i.e., PZT‐4). This work demonstrates significant progress in the comprehensive piezoelectric performance (especially the piezoelectric temperature stability) of lead‐free ceramics and inspires further attempts to achieve high‐temperature piezoelectric properties.

Field test and numerical research on explosion crater in calcareous sand

The explosion in foundation poses a significant threat to people and buildings. Currently, a unified empirical prediction formula for crater in calcareous foundation has not been established. In this paper, analyzed the types and sizes of explosion crater with different scaled burial depths through field tests and numerical simulation. In field tests, revealed the influence of scaled burial depth on the type and size of explosion crater and obtained the critical scaled burial depth for three different types of explosion craters, namely ejecta-type crater, collapse-type crater and covert explosion. Through the Smooth Particle Hydrodynamic-Finite Element Method (SPH-FEM) coupling algorithm, studied the movement trajectory of sand particles around the explosive at the moment of explosion in detail. Based on the field tests and numerical simulation results, it was found that calcareous sand has a smaller specific gravity due to its own characteristics, and the size of the explosion crater is larger than that of quartz sand at the same scaled burial depth. Obtained an empirical formula for crater in calcareous sand. Which can quickly predict the size of explosion crater and provide calculation basis for explosion resistant design in calcareous sand foundations.

Egg-shaped sections of fluid structures around black holes

Astrophysical fluids subjected to the strong gravity of black holes can form rotating toroidal-like structures known as thick accretion discs. In order to facilitate the study of such structures, we introduce approximate empirical formulae for a relatively simple analytical description of their poloidal cross-sections that are usually described only numerically. Our comparisons of the approximate and exact descriptions of the cross-sections of the structures rotating around Schwarzschild and Kerr central black holes, together with the determination of the associated total masses of these structure, indicate a high degree of accuracy for these introduced formulae.

A Simplified Non‐Hertzian Wheel‐Rail Adhesion Model Under Interfacial Contaminations Considering Surface Roughness

ABSTRACTThe accuracy and efficiency of the wheel‐rail adhesion model are important to the wheel‐rail rolling contact issues. The purpose of this study is to develop a simplified non‐Hertzian wheel‐rail adhesion model under interfacial contaminations to predict the wheel‐rail adhesion coefficient. Firstly, a non‐Hertzian full elasto‐hydrodynamic lubrication (EHL) model was developed and applied to determine the wheel‐rail contact pressure and film thickness under interfacial contaminations. Then, the empirical formula of central film thickness available to non‐Hertzian wheel‐rail normal contact relating to train speeds, axle loads and material parameters were proposed based on a large number of non‐Hertzian full EHL simulation for smooth surface under interfacial contaminations using linear regression. The empirical non‐Hertzian central film thickness formula and minimum film thickness formula for wheel‐rail contact obtained in this paper show certain differences from the formulas based on Hertzian contact. Using the proposed non‐Hertzian central film thickness formula, a simplified non‐Hertzian wheel‐rail contact adhesion model was developed, and the adhesion coefficient was obtained at different speeds and compared with the field test data. The numerical results showed good agreement with field test data.

Design of gas control lane of 9# coal seam in Wuhushan Mine based on layer layout optimization

In order to address the issue of gas over limit in the upper corner of the working face of the 9# coal seam in Wuhushan Mine, a series of theoretical and numerical simulation analyses were conducted to evaluate the optimal configuration for the gas control lane of the 9# coal seam. In accordance with the "O" circle theory and the lithology of the overlying rock strata of the 9# coal seam, the height range of the fallout zone and fissure zone in the working face mining area was determined by employing empirical formulas. The change rule and distribution characteristics of the porosity of the fissure zone and the fall zone in the mining area were analyzed based on the characteristics of rock movement and fall. The determination method was also provided. The numerical simulation software was employed to simulate and analyze the gas concentration field in the air-mining zone under conditions of no extraction and six distinct layer positions of the gas control lane. The optimal layer position of the gas control lane in the 9# coal seam was determined and subsequently implemented in the field. The results demonstrate that the overlying rock layer in the 9# coal seam exhibits a height range of 6.86 ~ 11.26 m, while the fissure zone displays a height range of 30.11 ~ 41.31 m. When the gas control road is situated in close proximity to the working face, the gas concentration field exhibits a markedly low concentration. When the distance between the gas control lane and the return airway of the working face is 20 m and the distance from the top of the coal seam is 20 m, the gas concentration in the upper corner and the return airway is 0.35% and 0.26%, respectively. These values are close to the lowest concentration observed in the layout scheme. Additionally, the gas extraction concentration and the pure volume of the gas control lane are 23.7% and 38.3 m3 min−1, respectively. These values represent the highest concentrations observed in the various layout schemes. The application of the gas management lane in the field, based on the numerical simulation results, demonstrated a successful extraction effect, which was consistent with the numerical simulation results. This effectively managed the issue of an over-limit of gas in the upper corner of the working face of the 9# coal seam.

Study on the chemical constituents and anti-free radical activity of mint essential oils in Binh Thuan Province, Vietnam

Mints (Mentha spp.) are famous aromatic and medicinal herbs that are used in traditional and folk medicines around the world for their antimicrobial and antioxidant properties. Mints contain volatile components such as flavonoids, organic acids, and quinones for the digestive system, central nervous system and respiratory system. Therefore, this study aimed to primarily find out the constituents and antioxidant activity of mint essential oil, which are very essential. The mint was harvested from the Ham Thuan Nam district of Binh Thuan province, Vietnam, in 2023. The essential oil of the mint was collected using steam distillation and dried with Na2SO4 for the final product. Chemical analysis of the components of the mint essential oil by GC-MS led to the identification of 17 chemical components, representing 98.72% of the hydro-distilled essential oil. Of these, five were hydrocarbons, such as monoterpenes (32.82%), and the rest were oxygenated hydrocarbons, such as alcohols (53.42%), aldehydes (4.67%), and ketones (7.81%). The 1,1-diphenyl-2-picrylhydrazol free radical scavenging activity of the mint essential oil was 39.36±1.23%, and this value was lower than that of 0.5 mM ascorbic acid (42.84 ±1.18%). Thus, the results of this study have high scientific and practical significance, when adding peppermint essential oil to food, it not only creates a fragrant smell for food, but also has antioxidant and antibacterial effects for food.

Assessment of some chemical constituents in selected energy drinks in Ilorin, Nigeria

The study compared and evaluated the physicochemical characteristics and some chemical components of some energy drinks. Samples of five (5) different energy drink brands were bought at random. The physicochemical characteristics of all the samples (pH, turbidity, conductivity, and total dissolved solids), as well as the levels of aspartame, sugar, and caffeine, were examined. The physicochemical properties (pH, turbidity, conductivity, and total dissolved solids) were 4.47 ± 0.012 – 5.96 ± 0.012, 8 ± 0.577 – 592 ± 1.155 NTU, 2.21 ± 0.006 – 1975 ± 1.732 μs/cm, and 243 ± 0.577 – 1064 ± 0.577 mg/L, respectively. The values were found to be moderate and it was found to be within the FDA's suggested range. All energy drinks contained iron, calcium, zinc, and potassium, with concentrations ranging from 2.0 to 2500 mg/L, 2.763 ± 0.0009 - 19.310 ± 0.0015 mg/L, 0.045 ± 0.0001 - 13.887 ± 0.0037 mg/L, and 1.961 ± 0.0003 - 0.294 ± 0.0005 mg/L, respectively. Energy drinks had concentrations of copper, lead, and manganese ranging from 0.002 ± 0.0002 - 0.102 ± 0.0003 mg/L, 0.028 ± 0.0006 - 0.209 ± 0.0009 mg/L, and 0.003 ± 0.0001 - 0.024 ± 0.0002 mg/L, respectively. While lead had a value over the maximum contaminant level (MCL) of 0.01 mg/L, copper and manganese concentrations were below the maximum contaminant level of 1.0 mg/L and 0.05 mg/L, respectively. With the exception of sample E, which had a value of 0.102 ± 0.0003 mg/L and was higher than the maximum contaminant level (MCL) of 0.005 mg/L, cadmium was not found in any energy drink. The concentrations of sugar, aspartame, and caffeine were 1.11 mg/L to 2487.13 mg/L, 6.51 mg/L to 1491.19 mg/L, and 16.98 mg/L to 1686.73 mg/L, respectively. The amounts of aspartame and caffeine in each energy drink sample were less than the FDA's recommended levels of 400 mg/L and 3000 mg/L, respectively. It is crucial to keep an eye on the consumption pattern of these drinks in order to reduce the risk of consuming excessive amounts of dangerous ingredients and avoid the side effects that have been documented.

Effect of particle size on dissolution of different chemical components in Codonopsis pilosula.

Codonopsis pilosula (Franch.) Nannf. is a traditional herb for treating immunosuppression. C. pilosula boiling powder (CP-BP) contains particles of a small size made from C. pilosula decoction pieces (CP-DP). It is still unclear how changes in particle size during the decoction process affect the dissolution of various chemical components in C. pilosula. Herein, an ultra-high-performance liquid chromatography-quadrupole-Exactive Orbitrap mass spectrometry technique was established to characterize the components of CP-BP and CP-DP decoctions. The contents of the components were evaluated based on the relative peak area, extract yield, and alcohol solubility rate. A total of 71 compounds were finally identified, and their content in the CP-BP decoction was generally higher than that in the CP-DP decoction. Alkaloids had the highest average content, whereas terpenoids were the most affected by changes in particle size. In addition, immunosuppression was used as model to investigate whether these changes have practical significance. The results of network pharmacology suggested that the phosphoinositide 3-kinase (PI3K)-Akt pathway may be a potential pathway of C. pilosula for treating immunosuppression. The results of molecular docking indicated that compounds with large content variations have good docking affinity with key targets (epidermal growth factor receptor [EGFR], prostaglandin-endoperoxide synthase 2 [PTGS2], and peroxisome proliferator-activated receptor gamma [PPARG]). These results provide an important reference for further development and use of C. pilosula.

Quality Evaluation of Kidney Tea Granules From Different Origins Based on TLC, HPLC Fingerprinting, and Quantitative Analysis Combined With Chemical Pattern Recognition.

Kidney tea is an essential herbal medicine. It is widely used to treat conditions such as urinary stones, gallstones, and rheumatoid arthritis. There is currently no standardized or widely accepted research strategy for evaluating the quality of kidney tea granules (KTGs) after granulation. In this study, we aim to establish a comprehensive strategy for evaluating the quality of KTGs produced from different sources of kidney tea. A TLC combined with HPLC method was established to identify the chemical components in KTGs, and HPLC method was used to determine the contents of rosmarinic acid of KTGs. In order to distinguish samples and identify differential components, similarity analysis, hierarchical cluster analysis (HCA), principal component analysis (PCA), and orthogonal partial least squares discriminant analysis (OPLS-DA) were conducted. TLC and HPLC detection confirmed three chemical components of KTGs, which are rosmarinic acid, caffeic acid, and lithospermic acid. HPLC fingerprint analysis revealed a total of seven common peaks in 15 batches of KTGs. Similarity analysis showed that the similarity of all 15 batches of KTGs was greater than 0.969. The peak areas of the seven common peaks were identified by chemical pattern recognition, and the results showed that most of the KTGs from different origins were clustered together, with small differences between them. The PCA and OPLS-DA results showed that two principal components can represent 82.638% of the common peaks of KTGs, among which peak 5 represents rosmarinic acid, which is the main differential biomarker of KTGs from different regions. Quantitative analysis of rosmarinic acid in KTG samples was performed using HPLC fingerprint conditions and the content of rosmarinic acid in 15 batches of KTGs samples was measured to be between 8.01-14.61 mg/g. This study combines TLC, HPLC, and chemometrics to establish a stable and reliable method that can quickly and effectively identify the components of KTGs, accurately quantify known components in KTGs, and provide reference for the quality evaluation of KTGs.

Experimental and numerical study of light, fragile vent covers under vented gas explosions

In this study, the venting functions of autoclaved aerated concrete (AAC) and gypsum vent covers under gas explosion conditions were examined for the first time. Eleven sets of field tests were performed, data such as overpressuretime history and rupture pressure data were collected, and failure modes were recorded and analysed. The results show that the AAC and gypsum panels can substantially reduce the internal peak overpressure and duration, and the AAC panel is the venting component with the best performance. The dynamic rupture pressure of venting covers obviously differs from the internal peak overpressure and static failure overpressure, so the opening process and dynamic effect of venting covers should be considered in the design. A numerical model of the AAC panel was established in LS-DYNA. In a parametric study, the panel thickness, material strength, boundary conditions and rate of overpressure rise considerably affected the rupture pressure. On this basis, an empirical formula for the rupture pressure and its applicable range is presented.

Unified uniaxial compressive constitutive model for C20–C120 concrete based on stochastic damage theory

The concrete uniaxial compressive stress-strain model is essential for analyzing reinforced concrete members and structures. However, models applicable to C20–C120 concrete are still relatively rare. Moreover, the previous empirical model construction methods may not reflect the physical mechanisms and randomness of concrete failure well. To this end, the database was constructed by collecting and analyzing uniaxial compressive stress-strain curve test results from different scholars. The cubic compressive strength in the database ranges from 9.9 MPa to 137.3 MPa. The adaptability of the stochastic damage model was validated using the database of test curves. Subsequently, stochastic damage models for C20–C120 concrete were calibrated based on concrete compressive strength grouping curves, and practical analysis models were suggested. The results indicate that the calculated curves closely match the test curves when the plastic strain evolution parameters η1,c and η2,c in the stochastic models are taken as 0.001–0.30 and 0.19–0.25, respectively. The adaptability of the stochastic damage model is satisfactory, but the plastic strain evolution laws vary for different concrete compressive strengths, influenced by mix proportions and the probability of failure of each component on the meso-scale. When η1,c is calculated by the empirical formula proposed in this paper and η2,c is approximated as 0.22, the calculated curves for C20–C120 concrete are consistent with the mean values of the test curves. The proposed practical analysis models provide comparable accuracy to stochastic damage models, eliminating the need for iterative calculations, making them convenient for engineering applications.