Physical Methods Research Articles

Preliminary Physical and Chemical Characterization of By-Products from Cuban Coffee Production

Coffee is one of the most consumed beverages worldwide. Its production generates a large amount of waste, and its use is of vital importance to prevent it from becoming a source of environmental pollution. Cuba is a country with a well-known coffee-growing tradition. Although coffee production has decreased, it is vitally important to use the waste generated in these productions to reduce environmental pollution. To know the possible use or application of coffee waste, it is necessary to know its composition. In this article, three Cuban Arabica coffee wastes (husk, parchment and spent coffee grounds) were characterized using chemical, physical and physicochemical methods. In the characterization of these wastes, SEM and EDX were used to determine their microscopic form and chemical composition. The Chesson–Datta method, ATR and TGA were used to determine whether these materials were lignocellulosic. Ash, pH and density of the waste were determined as characterization methods. The extractive content was determined and a phytochemical screening was performed to determine the groups of the secondary metabolites present.

Current insights into yeast application for reduction of patulin contamination in foods: A comprehensive review.

Patulin, a fungal secondary metabolite with multiple toxicities, is widely existed in a variety of fruits and their products. This not only causes significant economic losses to the agricultural and food industries but also poses a serious threat to human health. Conventional techniques mainly involved physical and chemical methods present several challenges include incomplete patulin degradation, high technical cost, and fruit quality decline. In comparison, removal of mycotoxin through biodegradation is regarded as a greener and safer strategy which has become popular research. Among them, yeast has a unique advantage in detoxification effect and application, which has attracted our attention. Therefore, this review provides a comprehensive account of the yeast species that can degrade patulin, degradation mechanism, current application status, and future challenges. Yeasts can efficiently convert patulin into nontoxic or low-toxic substances through biodegradation. Alternatively, it can use physical adsorption, which has the advantages of safety, high efficiency, and environmental friendliness. Nevertheless, due to the inherent complexity of the production environment, the sole utilization of yeast as a control agent remains inherently unstable and challenging to implement on a large scale in a practical manner. Integration control, enhancement of yeast resilience, improvement of yeast cell wall adsorption capacity, and research on additional patulin-degrading enzymes will facilitate the practical application of this approach. Furthermore, we analyzed the feasibility of the yeast commercial application in patulin reduction and provided suggestions on how to enhance its commercial value, which is of great significance for the control of mycotoxins in food products.

Enhanced Performance of Close-Spaced Sublimation Processed Antimony Sulfide Solar Cells via Seed-Mediated Growth.

Antimony sulfide (Sb2S3) has attracted much attention due to its great prospect to construct highly efficient, cost-effective, and environment-friendly solar cells. The scalable close-spaced sublimation (CSS) is a well-developed physical deposition method to fabricate thin films for photovoltaics. However, the CSS-processed absorber films typically involve small grain size with high-density grain boundaries (GBs), resulting in severe defects-induced charge-carrier nonradiative recombination and further large open-circuit voltage (VOC) losses. In this work, it is demonstrated that a chemical bath deposited-Sb2S3 seed layer can serve as crystal nuclei and mediate the growth of large-grained, highly compact CSS-processed Sb2S3 films. This seed-mediated Sb2S3 film affords reduced defect density and enhanced charge-carrier transport, which yields an improved power conversion efficiency (PCE) of 4.78% for planar Sb2S3 solar cells. Moreover, the VOC of 0.755V that is obtained is the highest reported thus far for vacuum-based evaporation and sublimation processed Sb2S3 devices. This work demonstrates an effective strategy to deposit high-quality low-defect-density Sb2S3 films via vacuum-based physical methods for optoelectronic applications.

Separation of iron and carbon concentrates from thermal power plant solid waste using physical methods

This research study examined the physical enrichment processes of coal fly ash (CFA) from the 2nd thermal power plant in Almaty. Magnetic separator and flotation enrichment methods were used to separate the magnetite and carbon parts of coal fly ash, respectively. In the study, a laboratory magnetic separator separated hematite content from 4.49 to 5.57% by mass from ash residues of different fractions. Cheap and available kerosene and flotol-b were used as flotation reagents for flotation enrichment. The particle size of coal ash is 63-100 μm, and the amount of carbon concentrate is ~16.3% by weight. The remaining mineral of coal ash is an essential raw material for building materials.

Modulation of shape memory properties of trans-polyisoprene by sulfur

Abstract In this paper, TPI/S composites were prepared by a simple physical melt blending method, and the composites were hot-pressed and molded using a vulcanization system. The effect of cross-linking on the vulcanization properties, mechanical properties, crystalline properties, and shape memory properties of trans-1-4 polyisoprene (TPI) was investigated by varying the amount of sulfur (S). It was shown that with the increase of sulfur dosage, both TPI scorch time and orthoclave time were shortened and the mechanical properties decreased; The melting peak area and melting temperature of the crystalline region of TPI decreased with the increase of sulfur content, and the cross-linking density increased while the crystallinity tended to decrease and the heat resistance deteriorated; In addition, with the increase of sulfur content, the shape return rate of TPI/S composites was increasing and the shape fixation rate was decreasing. When the TPI/S composites were used as shape memory materials, the sulfur dosage of 1 phr had the best shape memory performance, at which time the shape fixation rate of the composites reached 96.9% and the shape recovery rate reached 86.2%. When the sulfur content was elevated to 2 phr, the shape memory fixation rate was significantly decreased, indicating that the shape memory properties were severely compromised. This study reveals that the quantity of sulfur exerts a significant influence on the application of TPI/S composites. An appropriate amount of sulfur can facilitate the preparation of thermoplastic elastomers for utilization in shape memory materials. Nevertheless, an excessive amount of sulfur will substantially enhance the internal cross-linked structure of the composite and deteriorate the shape memory performance.


Functional characteristics and molecular structural modification of plant proteins. Review

Protein preparations from plant raw materials are widely used in the food industry as improvers, replacers or enrichers for products. However, their functional properties, as a rule, are less pronounced than those of proteins of animal origin. The aim of the review is to analyze and summarize the results of investigations dedicated to studying and characterizing the main functional properties of plant proteins (hydration, solubility, water binding capacity, fat binding capacity and gel-forming capacity, stability of emulsions, foams, rheological properties, texturization) and their modification. The objects of the research were scientific publications, most of which were published in 2017–2024. Functional properties of proteins were characterized; their dependence on the nature and variety of crop, methods of extraction, technological factors of processing and methods of modification was revealed. The search and selection of papers were carried out in the bibliographic databases eLIBRARY.RU, RSCI, Google Scholar, Scopus, Web of Science, Elsevier, and PubMed. Data analysis was performed with their systematization, generalization, intermediate conclusions and general conclusion. The special attention was paid to chemical, physical, physico-chemical and enzymatic methods for modification of protein properties, their advantages and disadvantages, as well as the interrelation of structural and physico-chemical features of proteins with their functional properties. The main regularities were revealed for an effect of modification methods on the secondary and tertiary structures of proteins, surface hydrophobicity, the ratio from fractions, aggregation, denaturation and biological activity obtained by the modern methods of investigations (IR‑spectroscopy, fluorescent microscopy, SDS-PAGE, circular dichroism, spectrophotometry and so on). It has been concluded that it is necessary to carry out further investigations aimed to studying interrelation of molecular structural features of proteins with indicators of functionality and regularities of their behavior in food systems due to an increase in the production of protein preparations from alternative raw materials (pea, chickpea, sunflower, kidney bean, rice and others). Based on the revealed and newly obtained theoretical information, the targeted modification and regulation of properties of protein ingredients for production of high-quality foods are possible.

Recovery and purification of kish graphite from steelmaking dust by using acid leaching with physical auxiliary methods

Graphite has been a critical raw material in recent years due to its high economic importance and high risk of supply disruptions. The traditional source of graphite is natural graphite ores; however, the production of natural graphite ores is controlled by few countries. It is thus important to find an alternative source of graphite, and steelmaking byproducts, such as dust and slag, can be considered because of their high potential for the recovery of kish graphite. The original kish graphite normally has a low carbon content and large amounts of impurities, and purification is necessary before using kish graphite in industry. The purpose of this study was to recover kish graphite from steelmaking dust by combining multi-stage froth flotation and acid leaching processes. The conditions of acid leaching were examined, and physical auxiliary methods (heating, microwave irradiation, and ultrasonication) were studied. After the multi-stage froth flotation process, the carbon content of the kish graphite was approximately 84 wt%, and Fe, Ca, Al, Na, K, Si, and Mg were the major elements of impurities. The acid leaching process was useful for enhancing the carbon content of the kish graphite and removing the impurities, particularly when using HCl and HBF4. However, HCl should be a more appropriate selection for acid leaching when considering the price of acids. The carbon content of the kish graphite reached ~ 95 wt% when using 1.0 N HCl with ≥ 30 min of reaction time and a ≥ 5 L kg−1 liquid-to-solid ratio. The physical auxiliary methods can further increase the carbon content of the kish graphite. The kish graphite purified by heating 1.0 N HCl at 80 °C for 5 min had the highest carbon content of approximately 97 wt%. The purified kish graphite and the natural graphite had similar crystallinity and lamellar structures, but the purified kish graphite had more structural defects. The recovery of kish graphite from steelmaking dust can obtain valuable materials and should have benefits for the environment.

Impacts of Waste Rubber Products on the Structure and Properties of Modified Asphalt Binder: Part II-Rubber Reclaim.

The issue of forming a reliable and stable structure of a crumb-rubber-modified binder is an important scientific and technical task. The authors supplemented existing concepts of the mechanism of effective interaction with rubber crumb by introducing a preliminary first stage: controlled partial physical destruction of rubber crumb-producing rubber reclaim. Proposed physical methods of rubber crumb destruction include high shear force (roll mills), high temperature, and a plasticizing medium. The controllability and degree of devulcanization of rubber were determined by acetone-chloroform extraction in different time intervals. The degree of devulcanization of rubber in the rubber reclaim was found to be 22 ± 0.24%, with stability over 14 days. It was found that the size of the particles of the rubber reclaim in the bitumen is less than 2 µm. The properties of the structure of the binder modified with rubber reclaim, characterizing the stability and sustainability, have been studied and established. The developed modified binders are stable in storage. Rheological parameters of the structure characterizing intermolecular interaction, such as shear stability for original and RTFOT-aged, modified bitumen, meet requirements of the state standard at test temperature 64 °C. The elastic structural component of the crumb-rubber-modified binder, as indicated by the relative irreversible deformation parameter J3,2, does not exceed 2.6 kPa (<4.5 kPa) at 64 °C. Additionally, it was determined that the rheological structural parameter for fatigue resistance, which characterizes the durability of road pavement under intensive operational conditions, does not exceed 4699 kPa (<5000 kPa) at 16 °C. The use of 10% rubber reclaim combined with waste frying oil provided the opportunity to obtain a modified binder with a stable and sustainable structure without the introduction of additional stabilizers and agents. Test results showed that the overall performance characteristics of the modified binder meet the 64(S)-40 grade standards.

Research Progress on Physical and Chemical Remediation Methods for the Removal of Cadmium from Soil

Research Progress on Physical and Chemical Remediation Methods for the Removal of Cadmium from Soil

Growth, Yield and Grain Quality of Cowpea (Vigna unguiculata (L.) Walp.) and Weed Flora as Affected by Physical and Chemical Methods of Weed Control

Growth, Yield and Grain Quality of Cowpea (<scp><i>Vigna unguiculata</i></scp> (L.) Walp.) and Weed Flora as Affected by Physical and Chemical Methods of Weed Control

Plant‐Based Biosynthesis of Metal and Metal Oxide Nanoparticles: An Update on Antimicrobial and Anticancer Activity

AbstractNanotechnology has changed and developed all the sectors and working fields. Nanoparticles are one of the important evolutionary materials that have application in almost all the working areas such as catalysis, bioengineering, photoelectricity, antibacterial, anticancer, and medical imaging due to their unique physical and chemical properties. Traditionally used chemical and physical method of synthesis of nanoparticles have several disadvantages like using different chemicals, high cost, and most importantly they are hazardous to the environment. Counter to these disadvantages, a more eco‐friendly, easy, and cost‐effective green synthesis method is widely employed nowadays. Various parts of a plant are used as a fuel for reducing the metal ion salt. Plant extracts act as reducing, stabilizing, and capping agents. Besides these advantages, photosynthesized nanoparticles are nontoxic, more stable, and more uniform in size than their counterparts prepared by the traditional method. In this present review, the synthesis of various plant extract‐mediated metal and metal oxide nanoparticles is discussed along with their different applications. This review provides a comprehensive overview of key findings in green synthesis of metal and metal oxide nanoparticles and attempts to determine their possible synthesis mechanism. This article also focuses on factors affecting their synthesis, characterization, potential applications, and prospects.

Synthesis of Pt-Rare Earth Metal Alloys and Their Applications.

The alloying of platinum (Pt) with rare earth (RE) metals has emerged as a highly promising strategy for enhancing both the activity and stability of catalysts. Consequently, the development of methods for the controlled synthesis of Pt-RE alloys has received growing attention. This review comprehensively explores diverse synthesis methodologies for Pt-RE alloys, including physical metallurgy method, chemical reduction method, electrodeposition method, and dealloying method. Additionally, this review summaries the applications of Pt-RE alloys in various fields. By providing a critical analysis of existing literature and highlighting key challenges and future directions, this review aims to offer valuable insights and serve as a springboard for further advancements in the controlled synthesis and diverse applications of Pt-RE alloys.

Synthesis of ZnPc/BiVO4 Z-Scheme Heterojunction for Enhanced Photocatalytic Degradation of Tetracycline Under Visible Light Irradiation

The construction of semiconductor heterojunctions is an effective strategy to improve the photocatalytic degradation efficiency of organic pollutants. Herein, ZnPc/BiVO4 Z-scheme heterojunction was synthesized via a physical mixing method and was used for the photocatalytic degradation of tetracycline (TC) under visible light irradiation. Compared with BiVO4 and ZnPc, the 15ZnPc/BiVO4 sample exhibited improved light absorption capacity, and the electron-hole separation efficiency and redox capacity were enhanced due to the formation of the Z-scheme heterojunction. The 15ZnPc/BiVO4 composite exhibited an optimal TC degradation rate of 83.1% within 120 min. Additionally, 15ZnPc/BiVO4 exhibited excellent stability in cycling experiments, which maintained a high TC degradation rate of 79.5% after four cycles. Free radical trapping experiments indicated that superoxide radicals (O2−) were the main active substances in the photocatalytic degradation of TC.

Optimizing crucible geometry to improve the quality of AlN crystals by the physical vapor transport method

In the conventional crucible structure for AlN crystal growth by physical vapor transport, owing to the long molecular transport path of Al vapor and the disruption of the gas flow by the presence of a deflector, the Al vapor easily forms polycrystals in the growth domain. The result is increased internal stress in the crystals and increased difficulty in growing large-sized crystals. On this basis, with the help of finite element simulations, a novel crucible structure is designed. This crucible not only optimizes the gas transport but also increases the radial gradient of the AlN crystal surface, making the enhanced growth rate in the central region more obvious. The thermal stresses between the deflector and the crystal are also reduced. High-quality AlN crystals with an FWHM of 79 arcsec were successfully grown with this structure, verifying the accuracy of finite element simulation of the growth of AlN crystals. Our work has important guiding significance for the growth of high-quality AlN crystals.

Anomalous enhancement of humid CO2 capture by local surface bound water in polar carbon nanopores

Removal of confined space carbon dioxide (CO2) that is in low concentration and with coexisting water is necessary but challenging by physical adsorption method. To make the removal process effective, rendering the nanopore surface hydrophobic to resist water is the popular way. Instead of preventing water from occupying the nanopores, in this work, we propose to utilize the guest water for the spatially selective formation of local surface bound water and further induce the preferential CO2 capture. We observe an anomalous enhancement of CO2 capture performance under humid conditions over carbon nanopores with spatially selective polar sites. It is evidenced that the surface bound water is formed at non-CO2-selective areas of polar carbon nanopores, thus creating additional CO2 trapping sites. This work may inspire the design of environment tolerable materials for molecular separation and purification under harsh conditions.

Research Progress on Physical Preservation Technology of Fresh-Cut Fruits and Vegetables

Fresh-cut fruits and vegetables have become more popular among consumers because of their nutritional value and convenience. However, the lower shelf life of fresh-cut fruits and vegetables due to processing and mechanical damage is a critical factor affecting their market expansion, and advances in preservation technology are needed to prolong their shelf life. Some traditional chemical preservatives are disliked by health-seeking consumers because of worries about toxicity. Chemical preservation is inexpensive and highly efficient, but sometimes it carries risks for human health. Biological preservation methods are safer and more appealing, but they are not applicable to large-scale production. Physical fresh-keeping methods have been used for the storage and transportation of fresh-cut fruits and vegetables due to the ease of application. This review discusses current research in fresh-keeping technology for the preservation of fresh-cut fruits and vegetables. Preservation methods include low temperature, modified atmosphere packaging, cold plasma, pulsed light, ultrasonics, ultraviolet light, and ozonated water. As promising alternatives to chemical methods, these novel processes have been evaluated singly or combined with natural preservatives or other methods to extend the shelf life of fresh-cut fruits and vegetables and to provide references and assessments for further development and application of fresh-cut fruit and vegetable preservation technology.

Location of 5G base station antenna in substation taking into account path loss and RF radiation

Aiming at the engineering problem that 5G base station antenna is difficult to locate efficiently in complex electromagnetic environment, a two-stage positioning method of 5G base station antenna substation is proposed, which considers signal path loss and antenna RF radiation. Firstly, the path loss solution model of the 5G base station antenna signal in the substation is established, and the RF radiation solution model generated by the coupling excitation of 5G high-frequency electromagnetic wave and the metal shell of the electrical equipment is constructed based on the big element physical optics method. Secondly, combining the advantages of particle swarm optimization (PSO) and interior point algorithm, the antenna positioning method considering path loss and RF radiation is constructed. Among them, in the first stage, the minimum loss of 5G signal path in the substation is taken as the goal, and the antenna stations in the substation are searched globally to get the optimal pre-selected position. In the second stage, the antenna position is calibrated according to the pre-selected position, so that the interference of RF radiation is minimized, and the final position is output. Finally, a 500 kV 5G substation in Henan Province was taken as the simulation object. Compared with the original scheme, the simulation results ensured the minimum 5G path loss in the substation and took into account the electromagnetic compatibility of the equipment in the substation. The effectiveness of the location strategy for maintaining the safe operation of the substation is verified, and it can provide a reference for the 5G base station antenna positioning project of the substation.

Geochemical and Physical Methods for Estimating the Saturation of Natural Gas Hydrates in Sediments: A Review

The saturation of natural gas hydrates is a key parameter for characterizing hydrate reservoirs, estimating hydrate reserves, and developing hydrate as an energy resource. Several methods have been proposed to estimate hydrate saturation, although most of these studies rely on logging and seismic data. However, the methods for estimating hydrate saturation from recovered core sediments have not been thoroughly reviewed, which hinders a deeper understanding, proper application, and the use of these experimental data to integrate geophysical and numerical model results with the actual geological conditions. In this paper, the methods widely used for estimating natural gas hydrate saturation from core sediments, including those based on pore water chemistry (Cl− concentration, δD, and δ18O values), gas volumetric analysis, and temperature anomaly, have been summarized in terms of the principle, estimation strategy, and issues to be considered of each method. The applicability, advantages and disadvantages, and scope of application of each method are also compared and discussed. All methods for estimating gas hydrate saturation have certain limitations. A comprehensive application of results from multiple methods could lead to a better understanding of the amount of gas hydrate in sediments, although the chlorinity of pore water is the most commonly used method of estimation.

The unreliability of crackles: insights from a breath sound study using physicians and artificial intelligence

Background and introductionIn comparison to other physical assessment methods, the inconsistency in respiratory evaluations continues to pose a major issue and challenge.ObjectivesThis study aims to evaluate the difference in the identification ability of different breath sound.Methods/descriptionIn this prospective study, breath sounds from the Formosa Archive of Breath Sound were labeled by five physicians. Six artificial intelligence (AI) breath sound interpretation models were developed based on all labeled data and the labels from the five physicians, respectively. After labeling by AIs and physicians, labels with discrepancy were considered doubtful and relabeled by two additional physicians. The final labels were determined by a majority vote among the physicians. The capability of breath sound identification for humans and AI was evaluated using sensitivity, specificity and the area under the receiver-operating characteristic curve (AUROC).Results/outcomeA total of 11,532 breath sound files were labeled, with 579 doubtful labels identified. After relabeling and exclusion, there were 305 labels with gold standard. For wheezing, both human physicians and the AI model demonstrated good sensitivities (89.5% vs. 86.0%) and good specificities (96.4% vs. 95.2%). For crackles, both human physicians and the AI model showed good sensitivities (93.9% vs. 80.3%) but poor specificities (56.6% vs. 65.9%). Lower AUROC values were noted in crackles identification for both physicians and the AI model compared to wheezing.ConclusionEven with the assistance of artificial intelligence tools, accurately identifying crackles compared to wheezing remains challenging. Consequently, crackles are unreliable for medical decision-making, and further examination is warranted.

Dynamic analysis of high-rise residential structures through the cone method

In this article, to analyze the behavior of surface foundations based on reinforced soil, a simple physical method based on material resistance called (cone method) has been used. Which is used as an alternative to the exact solution methods that are based on the three-dimensional elastodynamic theory. The purpose of this research is to introduce a simple physical method and analytical tool to analyze the surface foundation based on geocell-reinforced soil. With the cone method, it is possible to examine the effects of layered soil. Obtaining the dynamic stiffness of the foundation based on reinforced soil using the cone method for the vertical degree of freedom and also investigating the effect of various parameters related to geocell reinforcement on the dynamic stiffness of the surface foundation are the goals of this research. In general, the longer the geocell cushion has, the smaller the holes, and the higher the modulus of elasticity, the better the results. By increasing the number of geocell layers, the amount of spring stiffness coefficient and damping coefficient and as a result the dynamic stiffness coefficient increases. On the other hand, the closer the geocell is placed to the soil surface, the higher the stiffness of the spring and the lower the damping coefficient. In general, among these two parameters related to dynamic stiffness, the role of the damping coefficient has been more prominent and decisive in the investigation of foundations based on reinforced soil. One of the most obvious characteristics of geosynthetic materials in the soil, regardless of the greater hardness it gives to the soil, is the damping percentage of its constituent materials.