Characterization Methods Research Articles

Zirconium-porphyrin-MOF-based oxidase-like nanozyme with oxygen vacancy for aflatoxin B1 colorimetric sensing.

In this study, a porous coordination network zirconium-porphyrin-based nanoparticle with oxygen vacancies (OVs) was prepared using acetic acid and benzoic acid as modulators via a simple hydrothermal method. The presence of OVs was confirmed by various characterization methods and was found to enhance oxygen uptake and activation. This resulted in the generation of more reactive peroxyl radicals (•O2 -) and led to an improved oxidase (OXD) mimetic activity. Additionally, it promoted 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) oxidation, with a low Km value of 0.07mM and a high Vmax of 1.47×10-7M·s-1. As aflatoxin B1 (AFB1) inhibits the Pt@PCN-222-ABTS nanozyme system, a colorimetric probe for AFB1 detection was constructed. The limit of detection (LOD)was 0.074µg·L-1. This research presents a novel approach for designing a nanozymatic-based colorimetric method to analyze trace AFB1 residues in food.

Ultrasensitive electrochemical detection of bile acids via ZIF-67-MOF-derived CoNi(OH)x/CeO2/COOH-MWCNTs composite electrodes

Fast and ultra-sensitive assays are essential for the assessment of the efficacy of traditional Chinese medicines. Here, an ultrasensitive and rapid electrochemical detection of bile acid in traditional Chinese medicine using composite electrodes is presented. Cobalt-nickel hydroxide and cerium dioxide (CoNi(OH)x/CeO2) nanomaterials were synthesized in situ by a two-step reflux method with cobalt-containing metal–organic framework (ZIF-67), as precursor. It was ultrasonically complexed with carboxylated carbon nanotubes (COOH-MWCNTs) to form CoNi(OH)x/CeO2/COOH-MWCNTs composites, for facile direct detection of bile acids in traditional Chinese medicine. Characterization methods were used to verify the successful creation of the composite CoNi(OH)x/CeO2/COOH-MWCNTs, a material which demonstrated excellent electrochemical properties. The experimental results showed that the electrode responded well when bile acids, nicotinamide adenine dinucleotide, and 3α hydroxysteroid dehydrogenase were simultaneously present in the solution, and that the peak current had a good linear relationship (R2 = 0.988) with the concentration of bile acids (0.05–10.0 µM). The sensor has an outstanding detection limit of 1.0 nM, 2–3 orders of magnitude more sensitive than the concentration. Therefore, it can be used for rapid on-site detection of bile acids in real traditional Chinese medicines.

Development and sensitivity analysis of MWCNTs coated D-shaped plastic optical fiber sensor for the detection of mercury

Heavy metal pollutants in rivers and water catchments are one of the problems faced by many developing countries as they may result in health issues among their people. A proper sensing mechanism is required to ensure the quality of water. In this research, we propose a simple, low cost, and highly sensitive D-shaped plastic optical fiber (POF) sensor layered with functionalized multi-walled carbon nanotubes (MWCNTs) for the detection of mercury in water. The sensor underwent interrogation across a range of mercury concentrations at room temperature. Numerous methods of characterization have been employed to explore the intricate structural attributes of the sensing layer to verify that the nanocomposite surface layer is functionalized with minimal disruption to the nanotubes. The experimental results revealed that the coated sensor displayed swift response and recovery time of 6.3 s and 13 s respectively when tested with the dynamic mercury concentration range (0 to 5 ppm). Moreover, it exhibited a relative absorbance of 7.33 %/ppm, which is approximately four times higher than the plain sensor and a limit of detection (LOD) of 0.1 ppm. The sensor has the potential to be transformed into an on-site, portable, real-time optical sensor for the detection of mercury ions in drinking water, offering high sensitivity and fast data acquisition.

Preparation of modified graphyne to detect genotoxic impurities in gefitinib: Effects of ionic liquid structures and carbon nanotube composite modes

Seven kinds of ionic liquids (ILs) modified oxidized hydrogen-substituted graphyne (O-HsGY) were prepared and combined with carbon nanotubes (CNTs) by covalent and non-covalent modes. The effects of the structure of ILs and two different CNTs composite modes on the structure and properties of the materials were investigated. A series of characterization methods were used to systematically study the physical and chemical properties of the materials. The genotoxic impurity 2-chloro-1-fluoro-4-nitrobenzene was extracted from gefitinib by the prepared adsorbent and quantitatively analyzed by high performance liquid chromatography. The experimental results showed that the longer the alkyl chain of the ILs, the greater the adsorption capacity of the modified material to the target. The composite mode of carbon nanotubes determined its distribution state, which in turn determined the strength of the interaction between the composite material and the target. Under the optimized conditions, 1-hexyl-3-methylimidazole hexafluorophosphate modified graphyne interacted more strongly with the target, with average recovery of 97.2–100.4% of the target substance. Because surface CNTs impeded ILs adsorption, the average recoveries of covalent and non-covalent composites fell to 96.1–99.5% and 95.9–101.6%, respectively. The above results showed that 1-hexyl-3-methylimidazolium hexafluorophosphate modified graphene had the strongest adsorption performance for the target, while the adsorption properties of the material decreased after composite CNTs.

Multispectral Holographic Intensity and Phase Imaging of Semitransparent Ultrathin Films.

In this paper, we demonstrate a novel optical characterization method for ultrathin semitransparent and absorbing materials through multispectral intensity and phase imaging. The method is based on a lateral-shearing interferometric microscopy (LIM) technique, where phase-shifting allows extraction of both the intensity and the phase of transmitted optical fields. To demonstrate the performance in characterizing semitransparent thin films, we fabricated and measured cupric oxide (CuO) seeded gold ultrathin metal films (UTMFs) with mass-equivalent thicknesses from 2 to 27 nm on fused silica substrates. The optical properties were modeled using multilayer thin film interference and a parametric model of their complex refractive indices. The UTMF samples were imaged in the spectral range from 475 to 750 nm using the proposed LIM technique, and the model parameters were fitted to the measured data in order to determine the respective complex refractive indices for varying thicknesses. Overall, by using the combined intensity and phase not only for imaging and quality control but also for determining the material properties, such as complex refractive indices, this technique demonstrates a high potential for the characterization of the optical properties, of (semi-) transparent thin films.

Advances in Understanding the Evolution Mechanism of Micropore Defects in Metal Materials under External Loads

Micropores are one of the critical factors affecting materials’ performance and service life. As the need for a deeper understanding of micropore evolution and damage mechanisms grows, assessing the mechanical properties of materials containing micropores and predicting the lifespan of related metal structural components becomes increasingly complex. This paper focuses on the evolution process, regularities, and research methods of micropores in metal materials. Based on recent research and practical applications, the key stages of micropore evolution are discussed, encompassing nucleation, growth, coalescence, collapse, interaction, and the influence of other microstructures. Firstly, the advantages and limitations of commonly used characterization methods such as scanning electron microscopy, transmission electron microscopy, and X-ray computed tomography are introduced in the study of micropore evolution. Subsequently, critical theoretical models for micropore evolution, such as the Gurson model and its extensions, are summarized. By using a multiscale approach combining the crystal plasticity finite element method, dislocation dynamics, and molecular dynamics, the factors influencing the micropore evolution, such as external stress conditions, internal microstructures, and micropore characteristics, are specifically elaborated, and the basic physical mechanisms of micropore evolution are analyzed. Finally, a comprehensive review and summary of current research trends and key findings are provided, and a forward-looking perspective on future research directions is presented.

Phase composition and numerical model of low-pressure pulse carburized layer in 15Cr14Co12Mo5Ni2W steel

Aerospace engine gear steel, 15Cr14Co12Mo5Ni2W steel, requires carburizing heat treatment to achieve operational performance. However, predicting the carbon concentration during the vacuum carburizing process poses significant challenges. This paper aims to design and establish a predictive model for the carbon concentration during the vacuum carburizing process of 15Cr14Co12Mo5Ni2W steel. Given the complex phase transformations during the vacuum carburizing process caused by the ultra-high alloy content of 15Cr14Co12Mo5Ni2W steel, vacuum short-term intense carburization and diffusion experiments were designed. Characterization methods such as XRD, scanning electron microscopy, electron probe microanalysis, EBSD, and FIB+TEM were used to study the microstructure, phase composition, phase constituents, and distribution of element concentrations during the vacuum carburizing process. Subsequently, a carbon concentration distribution calculation model considering carbide changes during the vacuum carburizing process of 15Cr14Co12Mo5Ni2W steel was established. Boundary conditions for carbon absorption during the intense carburization process of 15Cr14Co12Mo5Ni2W steel were proposed, and the relationship between surface carbon concentration and boundary conditions was determined through experiments. Using the method of forward calculation with least squares fitting of experimental data, the diffusion coefficient of carbon in the austenite of 15Cr14Co12Mo5Ni2W steel and the rate of carbon exchange between carbides and the matrix were derived, providing a more precise predictive tool for optimizing the vacuum carburizing process of 15Cr14Co12Mo5Ni2W steel.

Fabricating a Structured Single‐Atom Catalyst via High‐Resolution Photopolymerization 3D Printing

AbstractThis study introduces a novel solution to the design of structured catalysts, integrating single‐piece 3D printing with single‐atom catalysis. Structured catalysts are widely employed in industrial processes, as they provide optimal mass and heat transfer, leading to a more efficient use of catalytic materials. They are conventionally prepared using ceramic or metallic bodies, which are then washcoated and impregnated with catalytically active layers. However, this approach may lead to adhesion issues of the latter. By employing photopolymerization printing, a stable and active single‐atom catalyst is directly shaped into a stand‐alone, single‐piece structured material. The battery of characterization methods employed in the present study confirms the uniform distribution of catalytically active species and the structural integrity of the material. Computational fluid dynamics simulations are applied to demonstrate enhanced momentum transfer and light distribution within the structured body. The materials are finally evaluated in the continuous‐flow photocatalytic oxidation of benzyl alcohol to benzaldehyde, a relevant reaction to prepare biomass‐derived building blocks. The innovative approach reported herein to manufacture a structured single‐atom catalyst circumvents the complexities of traditional synthetic methods, offering scalability and efficiency improvements, and highlights the transformative role of 3D printing in catalysis engineering to revolutionize catalysts’ design.

Complexity upgrade and triggering mechanism of mixed-wettability: Comparative study of CO2 displacement in different phases

Complex pore structures and wettability affect CO2 storage in underground reservoirs. Revealing the flow law of CO2 in complex reservoirs is crucial for evaluating storage stability and security. Considering the complexity of the pore structure and wettability of rock, a complex mixed-wettability characterization method based on a complex pore structure is proposed. Matrix numerical models for two-dimensional heterogeneous complex mixed-wettability rock were developed to simulate CO2 displacement in different phases. A comparative study found that, under single-phase wettability, the weaker the wettability, the better the effect of gaseous CO2 displacement. Moreover, the stronger the wettability, the better the displacement effect of ScCO2. The wetting phase of CO2 was transformed from the non-wetting phase. At the late stage of gaseous CO2 displacement, when the contact angles were 30° and 60°, the displaced water phase was absorbed back into the matrix owing to imbibition, resulting in the formation of a peak in the displacement efficiency curve. Compared to that at a contact angle of 60°, the displacement efficiency at a contact angle of 30° decreased more significantly after the peaks, while the suck-back phenomenon did not occur when the contact angle was 90°. Under mixed-wettability conditions, the flow law of CO2 in different phases is directly affected by the contact angle of the pore walls. The displacement efficiencies of gaseous CO2 and ScCO2 increased by 9.58% and 17.96%, respectively, owing to the dual driving force caused by imbibition. The complexity of mixed-wettability is upgraded by providing pore walls with different proportions of contact angles (six types). The flow law of different phases of CO2 showed that, the higher the proportion of walls with small contact angles (3:2:1), the worse the displacement effect of gaseous CO2 and the better the displacement effect of ScCO2. Compared with single-phase wettability and mixed-wettability, the displacement efficiency of gaseous CO2 and ScCO2 under complex mixed-wettability decreased by 4.26%, 1.00% and 20.41%, 3.37%, respectively. Therefore, ignoring complex mixed-wettability often leads to a higher displacement efficiency.

Engineering of uniform dispersed Ni nanoparticles supported on carbon nanosheets for reduction of Nitroarenes to Aminoarenes

Facile synthesis of uniform supported metal catalysts is of great significance yet remains challenging for sustainable catalysis. Herein, a nanopore confinement strategy is developed to efficiently anchor metal ions in suitably sized polymer nanopores via strong coordinate bonds and ensure successful fabrication of uniform carbon-supported metal nanoparticles. Specifically, Ni2+-coordinated polydopamine (PDA) mesoporous layer was coated on GO nanosheets for the confinement of the nickel atoms (GO@PDA-Ni-x, x means pore size of PDA layer), resulting Ni@C-x nanosheets catalysts with uniformly dispersed Ni nanoparticles after pyrolysis in H2/Ar atmosphere. Characterization methods including SEM, TEM, and XPS reveal the intrinsic formation mechanism and physicochemical details. In the catalytic reaction of NaBH4-mediated hydrogenation of 4-nitrophenol (4-NP), the obtained Ni/C-10 exhibits exceptional catalytic performance with a rapid rate constant (0.686 min−1), outperforming many previously reported metal catalysts. Moreover, the catalytic activity remains almost unchanged after being recycled five times, proving the prominent stability. This work opens up an innovative avenue for rational design and synthesis of supported catalysts with controllable size for broad catalytic applications.

Low-Temperature Migration-Enhanced Epitaxial Growth of High-Quality (InAs)4(GaAs)3/Be-Doped InAlAs Quantum Wells for THz Applications

This investigation explores the structural and electronic properties of low-temperature-grown (InAs)4(GaAs)3/Be-doped InAlAs and InGaAs/Be-doped InAlAs multiple quantum wells (MQWs), utilizing migration-enhanced epitaxy (MEE) and conventional molecular beam epitaxy (MBE) growth mode. Through comprehensive characterization methods including transmission electron microscopy (TEM), Raman spectroscopy, atomic force microscopy (AFM), pump–probe transient reflectivity, and Hall effect measurements, the study reveals significant distinctions between the two types of MQWs. The (InAs)4(GaAs)3/Be-doped InAlAs MQWs grown via the MEE mode exhibit enhanced periodicity and interface quality over the InGaAs/Be-InAlAs MQWs grown through the conventional molecule beam epitaxy (MBE) mode, as evidenced by TEM. The AFM results indicate lower surface roughness for the (InAs)4(GaAs)3/Be-doped InAlAs MQWs by using the MEE mode. Raman spectroscopy reveals weaker disorder-activated modes in the (InAs)4(GaAs)3/Be-doped InAlAs MQWs by using the MEE mode. This originates from utilizing the (InAs)4(GaAs)3 short period superlattices rather than InGaAs, which suppresses the arbitrary distribution of Ga and In atoms during the InGaAs growth. Furthermore, pump–probe transient reflectivity measurements show shorter carrier lifetimes in the (InAs)4(GaAs)3/Be-doped InAlAs MQWs, attributed to a higher density of antisite defects. It is noteworthy that room temperature Hall measurements imply that the mobility of (InAs)4(GaAs)3/Be-doped InAlAs MQWs grown at a low temperature of 250 °C via the MEE mode is superior to that of InGaAs/Be-doped InAlAs MQWs grown in the conventional MBE growth mode, reaching 2230 cm2/V.s. The reason for the higher mobility of (InAs)4(GaAs)3/Be-doped InAlAs MQWs is that this short-period superlattice structure can effectively suppress alloy scattering caused by the arbitrary distribution of In and Ga atoms during the growth process of the InGaAs ternary alloy. These results exhibit the promise of the MEE growth approach for growing high-performance MQWs for advanced optoelectronic applications, notably for high-speed optoelectronic devices like THz photoconductive antennas.

Bending deformation behavior and characterization method of flexural stiffness of composite tubes under four-point bending tests

The four-point bending test has inherent errors in measuring the flexural stiffness of tubes. The size of loading noses/supports could affect the response of equivalent bending moment on the tested tubes’ transverse section. The asymmetric axial strain distribution on the tested tubes’ transverse section depends on the tube’s thickness to diameter ratio. Based on the above phenomena, a four-point bending test with small-sized loading noses/supports and a characterization formula of tube’s flexural stiffness were proposed. The proposed methods were conducted on a thin-walled steel tube and a composite tube respectively. The errors between theoretical and experimental results were discussed.

Drought propagation and its driving forces in central Asia under climate change

Drought propagation time (PT) and threshold (TR) play crucial roles in real-time monitoring of drought progression and severity under climate change, for which there is currently no unified method or standard for quantitative characterization. Central Asia (CA), a prototypical arid region, is frequently plagued by droughts that profoundly impact its ecology and socioeconomic framework, leaving a lack of comprehension about the transition from meteorological to soil moisture drought as for the complex impact of ground-atmosphere interaction. Therefore, this study revealed high-resolution PT and TR across CA based on precipitation and soil moisture datasets by employing a Bayesian causal framework for drought propagation modeling, in which the sliding window with the random forest method was integrated to investigate the dynamic changes and driving factors of drought propagation over recent decades. The conclusions drawn are as follows: (1) in the southeastern hilly and eastern plateau, a prolonged PT (i.e., longer than 100 days) was experienced during the extremities of the growing season, while most areas had a shorter mid-season PT (i.e., less than 40 days), in which the soil moisture drought intensity was positively correlated with longer PTs; (2) from 1948 to 2022, the central and western regions in CA generally displayed lower TR values than those in the northeast, seldom exceeding 30 mm, reflecting the regional precipitation gradient and the positive relationship between TR and severe soil moisture droughts; and (3) the increase in vapor pressure deficit (VPD), the decrease in aridity index (AI) for the reduced precipitation, and the considerable impact of vegetation transpiration on soil moisture consumption contributed to accelerated drought propagation. Overall, this study reveals the complex dynamics and mechanisms of drought propagation amid environmental changes, laying the foundation for innovative drought early warning systems and emergency management approaches in CA.

Study on the mechanism of second phase formation in high-purity fused silica materials for semiconductor application

Gas bubble is a common defect in high-purity fused silica materials, but the formation of the second phase particles related to gas bubble and its mechanism remain unclear till now. In this work, we have presented a method for characterization of colored gas bubbles in high-purity fused silica crucibles for Czochralski silicon by the means of TEM and EDX. Based on it, the origin of the coloring of the gas bubbles is demonstrated to be induced by the gathering of Fe impurity and then, the formation of high-density second phase—ferric oxide (Fe2O3) crystals around the gas bubbles. Moreover, our results provide insight into the formation mechanism of second phase crystals which can be induced by stress field variations around gas bubbles during the cooling process that probably promoted by volume shrinkage effect and increasing solubility of gas from gas bubbles into fused silica substrate. The understanding of the second phase particle formation mechanism in high-purity fused silica materials is valuable for its further controlling.

Inverse identification of thermal behaviour of a paraffin-based phase change material in complete and partial phase change cycles

From the macroscopic point of view, phase change hysteresis (PCH) means that a phase change process (e.g. solidification) does not follow the same temperature-enthalpy path as the opposite phase change process (melting). Although the PCH is observed in most phase change materials (PCMs), it is often neglected in computational models, resulting in discrepancies when compared to experimental data. The PCH can particularly be an issue in the modelling of latent heat thermal energy storage systems, where incomplete (partial) phase transitions are quite common. Lab-scale experimental methods for characterisation of PCMs, such as differential scanning calorimetry or the temperature-history method, employ only small PCM samples, and the obtained results are often insufficient for predicting the thermal behaviour of large volumes of PCMs. The present study explores numerical modelling approaches to the PCH, addressing both complete and partial melting-to-solidification cycles. A set of validation experiments was performed, focusing on phase transitions in a paraffin-based PCM enclosed in a rectangular cavity. An inverse identification method was used to minimise the root mean square error (RMSE) of temperatures in the PCM using the particle swarm optimisation method. A two-curve approach showed the highest accuracy in complete phase change cycles, with a 62% improvement in the RMSE when compared to the manufacturer data. As for cycles with partial phase changes, a curve-scale approach showed superior behaviour, reducing the RMSE as much as 99%. Conversely, another investigated approach – a curve-track model – exhibited inferior performance, making it less suitable for the modelling of partial phase changes.

Analysis of the adsorption and fixation process of ammonium nitrogen in arable soil by biochar based on molecular dynamics simulation

The ammonia nitrogen in arable land soil is susceptible to environmental and anthropogenic influences, leading to nutrient loss. This study utilized indoor soil column leaching experiments, combined with adsorption mathematical models, traditional characterization methods, and molecular dynamics simulation methods, to analyze the effects of biochar on changes in ammonium ions in different soil layers and leachate of arable land soil. The study found that applying biochar at a ratio of 10 % to arable land soil could effectively increase the ammonium ion content in the 0–10 cm soil layer by 1.57–2.36 times and reduce loss by 44.83–72.27 %. The adsorption and fixation process of biochar is controlled by electrostatic attraction and ion exchange processes. Interactions between molecules, electrostatic forces, and system internal energy also have certain effects on the process. Near the structure of C6H12O6, there are low-energy adsorption sites for ammonium ions, which can provide the energy required for electrostatic attraction. Structures such as C5H10O5, C-S-H, C-SO3, and C4H7NO4 respectively play roles in physical adsorption or chemical adsorption through displacement reactions, electron exchange, and other forms. The adsorption free energy is −394,590.84 kcal/mol, indicating stable adsorption and a process that tends to interact with the biochar surface. This study addresses issues such as the easy loss of ammonia nitrogen in arable land soil and the unclear adsorption mechanism of biochar on ammonium ions, providing a theoretical basis for the field of environmental science.

Chemical profiling and quantification of flavones in several Pseudognaphalium and Gnaphalium species of Mexican gordolobo using UHPLC/PDA/MS

The inflorescences of the Mexican gordolobo are used as a folk medicine to treat various respiratory diseases. Currently, the botanical species that bear the name Mexican gordolobo belong to the genera Gnaphalium and Pseudognaphalium. Despite a long history of traditional use, most Mexican gordolobo species have never been fully chemically characterized, and the range of constituents in the species has not been comprehensively reported. To establish a quality control and chemical characterization method, a total of 49 samples belonging to 18 species of Pseudognaphalium and four species of Gnaphalium were studied. Nine flavones were quantified using a UPLC-PDA method. The method was validated in terms of linearity (R2 > 0.99), precision (intra- and inter-day: 0.1–3.9%), accuracy (96–103%), detection limit (10 ng/mL), limit of quantification (25 ng/mL) and robustness. 3-Methylquercetin, luteolin, quercetin, 3,5-dihydroxy-6,7,8-trimethoxyflavone, apigenin and gnaphaliin A were present at relatively high levels in most of the samples analyzed. The samples of P. oxyphyllum and P. liebmannii showed the highest content of the 9 compounds analyzed. Whereas the samples of the 5 species of Gnaphalium showed the lowest levels, including non-detectable, of the 9 compounds quantified. This marks an important difference with Pseudognaphalium species. Furthermore, using UHPLC-ESI-QToF data with targeted and non-targeted approaches, 57 compounds, were identified in Mexican gordolobo samples. Flavonoids were the main group of compounds found in Mexican gordolobo.

Acoustic Emission in Ceramic Matrix Composites

Abstract The integration of ceramic matrix composites (CMCs) into safety-critical applications, such as turbine engines and aerospace structures, necessitates a sound understanding of their expected damage evolution under in-service conditions and real-time health-monitoring methods to assess their damage state. The measurement of acoustic emissions (AEs), the transient elastic waves emitted during damage formation, offers an enhanced capability for evaluating damage evolution and structural health in CMCs due to its high sensitivity, accurate temporal resolution, and relative ease of use compared to other nondestructive evaluation (NDE) techniques. Recent advances in numerical simulation methods and data-driven model development, in combination with improved multimodal experimental characterization methods and sensor hardware, are rapidly advancing AE to a mature technique for damage quantification. This review discusses the fundamental principles of acoustic emissions, provides practical guidelines on their experimental characterization and analysis, and offers perspectives on the current state-of-the-art.

Analytical Study of Polychrome Clay Sculptures in the Five-Dragon Taoist Palace of Wudang, China

During the Ming Dynasty, the Five-Dragon Palace functioned as a royal Taoist temple set atop one of China’s holiest Taoist mountains, Wudang Mountain. Two tower polychrome sculptures with exquisite craftsmanship have remained over the centuries. In this study, the painting materials and the techniques used to construct these sculptures were analyzed through multiple characterization methods, including optical microscope (OM) observations, micro-Raman spectroscopy, scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM−EDS), X-ray diffraction (XRD), micro-Fourier-transform infrared spectroscopy (μ−FTIR), and pyrolysis–gas chromatography/mass spectrometry (Py−GC/MS). The results revealed that the pigments used in these sculptures included red pigments, which were composed of mercury (II) sulfide (cinnabar or vermillion), minium (Pb3O4), and hematite (Fe2O3); green pigments, which included atacamite and botallackite (Cu2Cl(OH)3), and blue pigments, which comprised smalt (CoO·nSiO2) and azurite (Cu3(CO3)2(OH)2). The white base layer was composed of quartz and mica minerals combined with gypsum or plant fiber, and the gold foil was adhered to the surface using heated tung oil. In addition, a special multi−layer technique was applied, with red under the golden gilding, white under the blue layer, and gray and black under the green layer. Drying oil was used as a binder for lead-containing pigments. This study offers substantial proof of reliable techniques to use in the continuing conservation of these sculptures, and it also serves as a foundation to determine if they can be dated to the late Ming or early Qing Dynasty (17th century).

Micro/nano fillers for value‐added polymer composites: A comprehensive review

AbstractThe need for new sustainable engineering materials using polymer composites is evolving every day. Researchers are in a race to develop value‐added products from natural renewable sources and discarded waste materials. Studies indicate several hurdles while trying to provide ecologically friendly materials for product manufacturing over the years. Natural materials are more readily available, biodegradable, more affordable, have less processing health hazards, and are more environmentally friendly than synthetic materials. As the price of commercial polymers decreased, the incorporation of fillers became increasingly necessary for technical reasons.. The market for polymers can actually be expanded by appropriately combining fillers and polymers to produce a wide range of qualities in these two components. This review provides an overview on a variety of organic and inorganic fillers which were incorporated into the polymer composites and their influence on the physical, chemical, mechanical, thermal, and electrical properties of polymer composites by various characterization methods and their In fact, it is possible to achieve a wide range of qualities in these two components by appropriately combining polymers and fillers, which expands the market for which polymers may be employed.application scopes. This review aims to thoroughly examine and assess various polymer and filler combinations, with a particular emphasis on their potential suitability for a range of engineering and industrial applications. These encompass microelectronics, biomedical fields, flexible electronics, flame retardant uses, food packaging, automotive and aerospace sectors, as well as applications within the construction industry for structural and semi‐structural purposes.Highlights New polymer composite engineering materials with long‐term sustainability Value‐added product development from renewable resources and discarded waste materials. Provide information to select appropriate reinforcements for composite manufacturing. Diverse discussion on the application of fillers and their composites.