Loss Of Raw Materials Research Articles

ZIFs@MIL-101/urea-derived magnetic FeCo nitrogen-rich carbon as an effective and stable catalyst for peroxymonosulfate activation

High efficiency and stability are key issues in heterogeneous metal catalytic materials/peroxymonosulfate (PMS) systems during wastewater degradation. However, catalytic materials that are difficult to recover and metal leaching can cause secondary contamination of water bodies. Herein, we designed the magnetic FeCo nitrogen-rich carbon (FeCo-NC) obtained by layer-by-layer encapsulation, followed by urea encapsulation of in situ grown MOF-in-MOF and carbonization. The CoFe2O4 crystalline nature of FeCo-NC was confirmed by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and selected angle electron diffraction (SAED) results, which is responsible for the magnetic properties of FeCo-NC. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) present that the material's morphology transforms from dodecahedral ZIF-67 to spindle-shaped ZIF-67@MIL-101 and then to octahedral FeCo-NC. Compared with FeCo-C and ZIF-67@MIL-101, the removal efficiency of FeCo-NC was maintained at 78.6 % after 10 consecutive cycles, with only a 17 % loss of raw material. The Fe and Co leaching amounts in the FeCo-NC/PMS system were approximately 0.6 and 0.1 mg/L, respectively, much lower than China's Fe and Co emission standards. FeCo-NC characterization and TC degradation results demonstrated that magnetic CoFe2O4 nanoparticles formed on the surface or inside the FeCo-NC could effectively inhibit metal (Fe and Co) loss and be easily regenerated in multiple degradation cycles. The mechanism and degradation routes in the FeCo-NC/PMS/ TC system, including the radical/nonradical pathways, Fe/Co valence change, and electron transfer, were further investigated by electron paramagnetic resonance experiments, electrochemical analyses, in situ Raman spectroscopy, and HPLC–MS experiments.

Expanding the Accessible Forest Areas by Improving Forest Road Standards and Utilizing Mobile Fire-fighting Teams

In Turkey, most of the roads (66%) in forests consist of Type-B secondary forest roads with limited technical standards. The lack of technical standards used on these roads and the lack of road structures and surface material limit the fire truck’s speed and increase the travel time of the firefighting team. Improving forest road standards will contribute to driving safety and increasing the design speed, thereby expanding the forest areas that can be reached within the critical response period, reducing possible wood raw material losses. There is no study in the national and international literature investigating the contribution of forest road standards improvement to firefighting activities and the effects on possible wood raw material losses due to forest fires. In this study, it was aimed to investigate the effects of improving forest road standards on expanding accessible forest areas within the critical response time, especially in forests with high fire risk, and thus reducing potential wood raw material losses. Antalya Forestry Regional Directorate, where forest fires are seen most frequently and the amount of burned area is the highest in Turkey, was selected as the study area as one of the forest regional directorates where forest fires are seen most frequently and the amount of burned area is the highest in Turkey. In the solution process, primarily the forest areas that can be reached by the firefighting team (including mobile teams used in emergencies) within the critical response time were determined by considering the existing road network in the study area. Then, the possible increase in the accessible forest areas was investigated when the road standards are improved. Within the scope of the study, the impact of mobile teams used in emergency situations on forest areas reached during the critical response period was also evaluated. According to the results, in the scenario where current road standards and stationary teams were evaluated, it was determined that only 59.54% of the forest areas could be reached by initial response teams during the critical response time, and if road standards were improved, this rate increased to 71.69%. On the other hand, in the scenario where current road standards and stationary and mobile teams were evaluated together, it was determined that 70.40% of the forest areas could be reached by initial response teams during the critical response time, and if road standards were improved, this rate increased to 78.17%. The results obtained have shown that improvements in road standards and the presence of mobile teams have a very effective role in combating forest fires.

Efficient separation of coal gasification fine slag from Texaco gasifier and microstructures and elemental characteristics of separated components

ABSTRACT Coal gasification fine slag (CGFS) is one of the by-products of coal gasification process, which is mainly composed of inorganic minerals and residual carbon. The key to realize the high-value utilization of CGFS is separating the residual carbon and mineral in CGS effectively. Owing to irregular distribution of carbon in different size of CGFS, which could not be enriched by simple grinding and screening for component enrichment. In this paper, the enrichment of CGFS was carried out by the float-sink method, which is low-cost and does not result in the loss of raw materials. The carbon-rich particles (CRP, ash: 27.89%) and mineral-rich particles (MRP, ash: 78.01%) were obtained, where CRP contains a large amount of amorphous carbon with rich porous structure, while MRP is a heterogeneous material containing not only inorganic minerals but also organic carbon with low porosity. The mineral particles exist as aluminosilicates with a high degree of polymerization. The results of this paper will provide theoretical and technical support for the high-value utilization of CGFS.

Efficient production of activated carbon with well-developed pore structure based on fast pyrolysis-physical activation

As the most commonly used method for industrial activated carbon preparation, physical activation is usually accompanied by significant loss of raw materials, especially when the pore structure of activated carbon is well developed. This not only reduces yields, but also increases costs. To enhance both yield and pore structure of activated carbon, we proposed a facile and scalable method called "fast pyrolysis-physical activation". After fast pyrolysis, although the initial pore volume of the semi-coke decreases, the rapid release of volatiles promotes the increase of mesopore and macropore volumes and the development of micron-scale cracks, which is beneficial for CO2 mass transfer and reduces diffusion resistance. Therefore, compared to slow pyrolysis, the activated carbon produced through this method has a higher pore volume (increased by 25.9 %–30.0 %) and a larger SBET (increased by 26.7 %–38.3 %), while the yield remains almost unchanged. Consequently, due to the increase in pore volume and high yield of the activated carbon, the CO2 adsorption capacity (25 °C, 1 bar) of ACB-K700 increases from 2.02 mmol/g to 2.37 mmol/g compared to ACB-M700, and the total CO2 adsorption capacity of activated carbon prepared from the same mass of raw coal (1 g) increases from 1.07 mmol to 1.16 mmol. Due to the pre-formed pores inside the semi-coke, the gas activator molecules are able to penetrate deep into the particles, which not only reduces the ineffective etching that occurs on the surface, but also promotes the development of pore structure. In conclusion, this study provides a new pore development model for physical activation, and also provides a new method to produce activated carbon rapidly and massively, while the pore structure is well developed.

Feed Milling Industries Resilience amid COVID-19 in Ekiti State Nigeria

This study analyzed the resilience strategies for small-scale feed milling industries, learning from the COVID-19 pandemic in Ekiti State, Nigeria. 215 small scale feed mills industries were selected by multistage sampling procedure. Descriptive statistics, gross margin and regression analysis were used for the analysis of data collected. Results revealed that the mean age for the respondents was 40.45 year. In addition, 91.58% of the feed millers were married while 8.42% were single with a mean household size of 6. 13 years was the mean number of years spent in school. With respect to experience, the respondents had 11 years of feed milling experience. Gross margin results indicated that income after COVID-19 is more than during the COVID-19 showing an N168,330.00 significant (p<0.001) difference indicating that COVID-19 had great consequences on the income. The regression result revealed that sex (p<0.001), marital status (p<0.010), household size (p<0.001), education (p<0.001) and experience (p<0.005) were feed mill profitability determining factors in the study area. Constraints faced during COVID-19 are that lockdown due to COVID-19 hindered operational activities of feed mill (65.26%), COVID-19 causes a total increase in the price of inputs (66.32), reduction in the sales of feeds (69.29%), reduction in work force (65.26%), and loss of raw materials through spoilage (66.32%). The study recommended that feed millers should collaborate with local farmers for the supply of materials at lesser price, rather than buying highcost foreign materials.

Photoproduction of Hydroxyl Radicals Under Sunlight by Fe-Zn Oxides for Partial Oxidation Applications

Iron-zinc oxide (FZ) photocatalysts with activity in the visible region were designed for the partial oxidation of organic molecules with the least loss of raw material. The FZ materials were synthesized using the sol-gel method with citric acid as a stabilizing agent. From TGA results, 400 °C was observed as the minimum temperature for precursors degradation, then two thermal treatment times were assessed at 60 and 180 min. The powder photocatalysts were comprehensively characterized by TGA, DSC, FTIR, XRD, Raman, Mössbauer, XPS, UV-Vis, and SEM. The production of hydroxyl radicals (•OH) was followed by the fluorescence emission of 2-hydroxy-terephthalic acid (OHTA). The absorbance decrease of methylene blue (MB) and disodium terephthalate (NaTA) was measured by UV-Vis spectroscopy to calculate the total degradation degree. The photocatalytic activity of FZ materials was quantified after 2 h under simulated sunlight radiation at room temperature conditions. All FZ oxides treated for 60 min presented no •OH detection, in which photocatalytic blanks showed an adsorption phenomenon of the probe molecules. FZ7 and FZ8 materials showed the best •OH production and the least MB/NaTA degradation, making them the best candidates for partial oxidation applications.

Investigation of Zhenjiang Aromatic Vinegar Production Using a Novel Dry Gelatinization Process.

The traditional process of producing Zhenjiang aromatic vinegar faces challenges such as high water usage, wastewater generation, raw material losses, and limitations in mechanization and workshop conditions. This study introduces and evaluates a novel dry gelatinization process, focusing on fermentation efficiency and the vinegar flavor profile. The new process shows a 39.1% increase in alcohol conversion efficiency and a 14% higher yield than the traditional process. Vinegar produced through the dry gelatinization process has a stronger umami taste and a higher lactic acid concentration. Both processes detected 33 volatile substances, with the dry gelatinization process showing a notably higher concentration of 2-methylbutanal, which imparts a distinct fruity and chocolate aroma. These findings suggest that the dry gelatinization process outperforms the traditional process in several aspects.

Microwave device for heat treatment of meat by-products and waste

BACKGROUND: In the conditions of farms, there is a problem of neutralizing unpleasant odors during heat treatment of secondary meat raw materials to preserve the consumer properties of protein feed at low operating costs. AIM: Development of the device for heat treatment with disinfection and neutralization of the unpleasant odor of crushed secondary meat raw materials with the integral effect of an ultra−high frequency electromagnetic field, a bactericidal flow of UV rays and ozone in a continuous mode with electromagnetic safety ensured. METHODS: The raw materials are the stomach chambers of ruminants. The basic idea, principle of operation and design of the device are based on the propagation of microwave oscillations in a resonator with a spiral decelerating system. The microwave device contains a non-ferromagnetic cylinder with a perforated lower base, a coaxially arranged non-ferromagnetic spiral cylinder and an electrically driven fluoroplastic auger with a solid screw surface. The average perimeter of the annular volume, between the cylinder and the spiral cylinder forming the coaxial resonator, and its height are multiples of half-wavelength. Corona brushes are mounted to the annular base of the cylinder, under which electric gas discharge lamps powered by 1 kHz frequency generators are radially located, and a ceramic annular spherical surface is located under the lamps. Magnetrons are mounted along the perimeter of the outer cylinder with a shift of 120 degrees. The crackling is removed using a pneumatic conveyor. RESULTS: The feature of the coaxial resonator is that the inner core is formed as a spiral decelerating system. Therefore, the intrinsic Q-factor of the resonator is high, about 115000, therefore, the expected thermal efficiency is 0.7–0.75. The factor of dielectric losses of raw materials with a decrease in humidity from 76% to 30% is reduced by five times. Thus, while keeping the electric stress at the level of 1.2–2 kV/cm, the electromagnetic field power dissipated in a unit of the volume of the crackling decreases by five times, from 34 500 to 6800 W/cm3. CONCLUSIONS: A new design solution with a spiral coaxial resonator, the use of a ceramic reflector, and a number of physical factors made it possible to develop the design of the operation chamber for the heat treatment of ruminant slaughter waste with the neutralization of unpleasant odors with a capacity of 30–35 kg/h and specific energy costs of 0.16–0.19 kWh/kg.

Improvement of the methods for determining ore losses when designing cement raw material deposit mining by surface miner combines

Relevance. The need to optimize production of cement raw materials and reduce the cost of processing raw materials. A surface miner combine allow high selective mining of a deposit, which helps to reduce moisture content of cement raw materials and reduce energy costs in a cement plant. In open-cast mining of cement raw materials deposits with the use of the surface miner combines, the increase in economic efficiency of mining operations can be achieved by determining the rational values of ore losses and dilution. Aim. To determine rational level of cement raw material losses during field development by surface miners. Objects. Cement industry quarries excavated with of the surface miner combines. Methods. Technical and economic analysis of the cement plant Beočin (Serbia), summation and synthesis of materials, sources and data available in the public domain, as well as calculations to determine the amount of loss and dilution of mineral resources at ore–rock contact for mining conditions of the quarry for extracting cement raw materials. Results. The main problems that arise during mining quarries for extracting cement raw materials have been identified. It concerns the determination of the volume of losses and dilution of mineral resources at the ore–rock contact for mining conditions of the quarry for extraction of cement raw materials. The authors present and substantiate conclusions about further effective application of optimal mining technology, with the use of the surface miner combines, which allows reducing the cost of production of minerals and specific operating costs of transporting carbonate rocks compared to the traditional technology of mining works at 50–60%.

Shelling and characterisation of the technical parameters of a shea nut (<i>Vitellaria paradoxa</i>) shelling machine in Cameroon

Producers of shea kernels encounter difficulties in processing the nuts. This leads to greater losses of raw material and a reduction in the yield of shea butter, as processing is generally done manually by smallholders, who produce more shea kernels in local areas. Added to this is the arduous work involved in shelling, due to the lack of a shelling machine adapted to their level of production. This study was, therefore, carried out to improve local shea butter production capacity. The huller was designed using data on the physical, gravimetric, geometric and frictional properties of shea nuts, before being built and tested. The hopper has an angle of inclination of 62.64°, a concave clearance of 3.6 cm and a winnowing air flow rate of 0.53 m3/s. The machine has an hourly capacity of 136 kg/h. The performance test showed that moisture content had a significant influence on hulling efficiency, cracking rate and machine output. The best cracking rate of 3.68±0.74% was obtained with a moisture content of 10.24%. The hulling efficiency obtained with the abovecontent is 92.43±1.05%, a cleaning efficiency of 78.30±0.55% and a machine yield of 88.83±0.38%. Water contents of < 10.24% are ideal for better shelling efficiency.

MnN4 embedded zeolite-templated carbon for methylamine and trimethylamine sensing: Insights from DFT study

From the perspective of raw material losses and human health, monitoring fish-based food quality has become more prominent. As a nondestructive technology, gas sensors have received extensive attention for evaluating the freshness of fish. In this study, the sensing and electronic properties of methylamine (MA) and trimethylamine (TMA) molecule adsorption on MnN4 embedded zeolite templated carbon (MnN4-C) were studied by density functional theory (DFT) method. The results show that the MnN4-C exhibits good structural stability, and displays high sensitivity toward MA and TMA gases by analysis of the interaction distance, adsorption energy, charge transfer and sensing response. It is worth noting that the ambient humidity has demonstrated no effect on the gas-sensing properties of MnN4-C for the studied gases. Meanwhile, applying a positive electric field can increase the adsorption energy and charge transfer, which enhances the MA and TMA gas sensitivity of MnN4-C. The recovery time reveals that MnN4-C can be an excellent reusability sensor for MA and TMA gases. This study provides theoretical direction for exploring the sensing application of MnN4-C in evaluating freshness of fish.

Predicting saturation for a new fabric using artificial intelligence (fuzzy logic): experimental part

Weaving saturation can have harmful consequences, such as problems with loom performance, accelerated wear of mechanical parts and loss of raw materials. To avoid these problems, when designing and creating new fabrics, the densities and yarn qualities must be carefully matched with the weaves to ensure successful testing. To facilitate this task, this study focuses on the development of a practical fuzzy logic model for predicting the saturation of new fabrics. An experimental part was carried out to validate this fuzzy model. The fabric samples used in this study came from three different types of weaves, namely plain, twill and satin. These samples also included five weft counts (Nm) and eight different densities. The results obtained using the fuzzy logic model developed were compared with experimental values. The prediction results were satisfactory and precise, demonstrating the effectiveness of the fuzzy logic model developed. The mean absolute error of the calculated fuzzy model was 1,97 %. It was therefore confirmed that this fuzzy model was both fast and reliable for predicting the saturation of new fabric

Impact of microgeometric parameters on the sliding cutting behavior of macaroni products

The primary objectives of the food industry sectors in the Republic of Uzbekistan are to intensify and optimize technological processes, adopt new progressive equipment for efficient processing modes, reduce energy costs and raw material losses, and improve product quality. Accordingly, this article presents a solution to one of the problems and provides an analysis of the cutting ability of the tool based on the investigated set of blade microgeometry parameters. The research aims to determine the numerical values of the microgeometry parameters for lamellar knife blades, obtained through various formation methods, and to identify the nature of their changes during operation. Additionally, the study explores the possibility of achieving such blade microgeometry parameters during sharpening, which were obtained through the optimization of the cutting ability objective function. The system described in the article has been implemented using the method of microscopic examination of lamellar knives, which allows for the photography of the blade surface and facets, contributing to the visual control of the cutting-edge condition immediately after its formation and during operation.

INCREASING THE EFFICIENCY OF USING WOOD BIOMASS BY PROVIDING SPECIAL PROPERTIES

Background. The search for ways to use logging waste is a distinct scientific direction, due to the large number of their permanent formation. The importance of such studies is associated with the need to reduce the loss of valuable wood raw materials in the form of logging waste. One of the possible ways of using waste from logging industries is the production of wood chips using a mobile complex of machines with its further recycling into a wood-fiber semi-finished product. Wood-fiber semi-finished product is, as it is known nowadays, one of the environmentally friendly types of insulation and finishing materials. A significant limitation in the use of wood fiber in various types of production is low fire and bio-resistance. As a consequence, imparting specific properties to a wood-fiber semi-finished product in the form of fire and bio-resistance is an acute problem of the modern wood processing industry.
 Purpose. Synthesis of 4-azofunctionalized pyrazoles with perfluoroalkyl substituent by cyclocondensation of polyfluorinated beta-diketones to confer special properties to the wood-fiber semi-finished product.
 Materials and methods. The 1H, 13C NMR and 1H-13C HSQC spectra were registered at the Krasnoyarsk Regional Center for Collective Use of the FITC KNC SB RAS on a Bruker Avance III Fourier spectrometer with a frequency of 600 MHz equipped with sensitive helium probes with a diameter of 5 mm and 1.7 mm. TMS is used as an internal standard. Chromato-mass spectra were obtained using ISQ 7610 Single Quadrupole GC-MS and Shimadzu LC/MS-2020 instruments. Methyl alcohol was used as the mobile phase. IR spectra were recorded on the FT-801 (FT-801) SIMEX IR Fourier spectrometer with a spectral range from 450 to 5700 cm-1. UV spectra were recorded on a HELIOS OMEGA spectrophotometer equipped with a tungsten-halogen lamp in quartz cuvettes with a diameter of 1 cm at a concentration of 1·10-4 mol/l for 200-400 nm and a concentration of 1·10-2 mol/l for 400-800 nm in ethanol. Melting temperatures were determined in open capillaries on a PTP device (TU 25-11-1144-76).
 Results. 3 new compounds were synthesized: 3(5)-(thiophene-2-yl)-4-nitroso-5(3)-(trifluoromethyl)-1H-pyrazole, 3(5)-phenyl-4-nitroso-5(3)-(trifluoromethyl)-1H-pyrazole and 3(5)-(naphthalene-2-yl)-4-nitroso-5(3)-(trifluoromethyl)-1H-pyrazole.
 Conclusion. Thus, 3(5)-(thiophene-2-yl)-4-nitroso-5(3)-(trifluoromethyl)-1H-pyrazole, 3(5)-phenyl-4-nitroso-5(3)-(trifluoromethyl)-1H-pyrazole and 3(5)-(naphthalene-2-yl)-4-nitroso-5(3)-(trifluoromethyl)-1H-pyrazole. Complex separable mixtures of substances containing pyrazoline, β-diketone and target nitrosopyrazoles were formed by a single-reactor method. The two-stage method of production proposed by us increases the purity and yield of the target products.

Classification of Circular Knitting Fabric Defects Using MobileNetV2 Model

Fabric defects cause both labor and raw material losses and energy costs. These undesirable situations negatively affect the competitiveness of companies in the textile sector. Traditionally, human-oriented quality control also has important limitations such as lack of attention and fatigue. Robust and efficient defect detection systems can be developed with image processing and artificial intelligence methods. This study proposes a deep learning-based method to detect and classify common fabric defects in circular knitting fabrics. The proposed method adds a fine-tuned mechanism to the MobileNetV2 deep learning model. The added fine-tuned mechanism is optimized to classify fabric defects. The proposed model has been tested on a fabric dataset containing circular knitting fabric defects. Obtained results showed that the proposed method produced desired results in fabric defect detection and classification.

Developing the quality of functional sausage products with the addition of local vegetable raw materials

In today's world, the issue of creating complete food products is relevant for the development of food technology. One of these areas is devoted to solving the problem of preventing iron deficiency conditions arising from iron deficiency in the diet. To enrich the diet with necessary nutrients and reduce the loss of valuable raw materials, it is relevant to justify innovative technologies of sausage products. The object of the study is the technology of blood sausages with the addition of eggplant powder and green buckwheat. In the process of modeling the recipe, eggplant powders for blood sausage were added in an amount of 5, 10, 15, 20 % by weight of unsalted raw materials. The optimum concentration was found to be 10 % powder. It was determined that the introduction of plant additives into the stuffing increases the pH value from 6.35 in the control to 6.52 in the experimental sample of the finished sausage. The introduction of the additive increases the moisture-retaining capacity of the stuffing proteins in the experimental samples by 6.28–6.87 % compared to the control. The research found that the introduction of unconventional ingredients positively affects the changes in pH (norm 6.5–6.8), which during 5 days of storage was within 6.5–6.52. The control sample on the day of preparation had a pH of 6.5. During storage, the pH decreased dramatically, which indicates increased acidity, accordingly affects the quality of the finished product and confirms the short storage duration. As a result of laboratory studies of microbiological safety indicators, only mesophilic aerobic and facultative anaerobic microorganisms were detected in the experimental samples, the number of which does not exceed the standards. No ochratoxin A (OTA) was found in the studied blood sausage samples, indicating the safety of the developed product

Consistency Analysis of Rendement and Quality of CPO (Crude Palm Oil) Palm Oil Processing at PT. Agricinal North Bengkulu

The yield and quality of CPO is influenced by the condition of unripe and overripe FFB (fresh fruit bunches), which can cause an increase in ALB, water content and dirt content. The quality of CPO is also influenced by FFB from the community. Analysis of the consistency of the yield and quality of CPO was carried out due to the age of the plants that were too old and the performance of the factory machines decreased due to the age of the machines. Analysis of yield consistency and quality was carried out using statistical quality control methods, namely quality control using a statistical approach using control charts and causal diagrams. This study uses secondary data on the yield and quality of CPO for the past year (July 2021-June 2022). The research results show, there are data that are outside the upper control limit, yield in July 2021, free fatty acid content in May 2022 and dirt content in October 2021. While the water content is statistically controlled (in statistical control). The yield and quality of ALB are influenced by type of raw material, production capacity and oil losses. Moisture content and dirt content are affected by treatment of production process and machine conditions.

Synthesis of nanocarbon by high-voltage breakdown of hydrocarbons

The object of research is the mechanisms of synthesis of nanocarbon structures in the process of electric high-voltage breakdown of hydrocarbons. The problem to be solved is the purposeful synthesis of various types of nanocarbon with small losses of raw materials. Mechanisms of nanocarbon formation in the process of high-voltage electric breakdown of hydrocarbons have been established. It is shown that a high-voltage breakdown leads to a cascade of chemical transformations. As a result of transformations, lower gaseous hydrocarbons are formed due to the destruction of molecules and higher ones – as a result of polymerization, and as a result of dehydrocyclization and polymerization with the participation of metal catalysts – various carbon nanostructures. The possibility of targeted synthesis of fullerene-like structures, nanotubes with diameters from 10 to 50 nm, nanofibers, and films is demonstrated. Experimental studies have confirmed that the qualitative and quantitative composition of nanocarbon can be varied in a wide range. With an increase in the number of carbon atoms or the number of C–C bonds in the raw material molecules, other things being equal, the practical yield of solid nanocarbon increases. It was determined that the synthesis of structured nanocarbon from a mixture of hydrocarbon gases, formed as a result of high-voltage breakdown of liquid hydrocarbons, actively occurs on the nickel-chromium catalytic surface. An increase in the area of the catalytic deposition surface leads to an increase in the yield of nanocarbon. The study of the ability of the obtained nanocarbon samples to absorb electromagnetic radiation confirmed the potential of the method of high-voltage breakdown of hydrocarbons for the synthesis of materials that weaken electromagnetic radiation at a frequency of 25 to 38 GHz. The greatest weakening is observed for samples consisting mainly of carbon nanotubes and nickel nanoparticles

A convenient functionalization strategy of polyimide covalent organic frameworks for uranium-containing wastewater treatment and uranium recovery

The purpose of this research was to design and synthesize an adsorbent based on polyimide covalent organic frameworks (PICOFs) for uranium-containing wastewater treatment and uranium recovery. A modified solvothermal method was innovatively proposed to synthesize PICOFs with high specific surface area (1998.5 m2 g−1) and regular pore structure. Additionally, a convenient functionalization strategy of PICOFs was designed through polydopamine (PDA) and a well-dispersed polymer (MPC-co-AO) containing multiple functional groups, forming stable composite (PMCA-TPPICOFs) in which the hydrogen bonding and cation-π interactions between PDA and MPC-co-AO played a key role. The obtained PMCA-TPPICOFs as an adsorbent exhibited strong selectivity for uranyl ions (maximum adsorption capacity was 538 mg g−1). In simulated wastewater with low uranium concentrations, the removal rate reached 98.3%, and the concentration of treated simulated wastewater met discharge standards. Moreover, PMCA-TPPICOFs was suitable for fixed-bed column adsorption because of its favorable structure. According to the research about adsorption mechanism, the adsorption primarily relied on electrostatic interaction and complexation. In summary, PMCA-TPPICOFs exhibited good potential for uranium-containing wastewater treatment, expanding the application of PICOFs. And the proposed functionalization strategy and modified solvothermal method may promote research in the fields of material functionalization and COFs synthesis. Environmental ImplicationUranium is a raw material for nuclear energy applications, which is toxic and radioactive. If uranium is discharged with wastewater, it would not only pose a threat to the environmental protection and life safety, but also cause the loss of precious nuclear raw materials. Although adsorption was considered to be an effective way to remove uranium, many of the developed adsorbents were difficult to apply due to the harsh wastewater environment and complex preparation processes. This study reported a novel adsorbent and a new functionalization strategy, which was expected to solve the problem of uranium recovery in wastewater.

Fracture behavior of AZ31B magnesium alloy under high-temperature ultrasonic-assisted shearing with related ductile-brittle transformation mechanism

A wide width is one of the fundamental requirements for magnesium alloy sheets to fulfill the lightweight needs of the aerospace and rail transportation industries. Nevertheless, ensuring the dimensional integrity of wide-format magnesium alloy sheets is a challenge in most manufacturing facilities. Simultaneously, processing operations are susceptible to encountering production issues, including but not limited to significant loss of raw materials, elevated costs, environmental contamination, and safety risks. Therefore, to fulfill the operational demands of the hot rolling finishing line for wide sheets made of magnesium alloy, the present study employed ultrasonic-assisted shearing (UAS) to carry out a high-temperature shearing test investigation on the AZ31B magnesium alloy sheet. In this research, we employed scanning electron microscopy, optical microscopy, and a micro-hardness tester to investigate the relationship between ultrasonic amplitude and fracture behavior, deformation mechanism, and mechanical properties of magnesium alloy sheets following exposure to ultrasonic vibration. The fracture morphology of the sheet fracture demonstrates that the behavior of the magnesium alloy sheet fractures under ultrasonic vibration changes from ductile fracture under conventional shearing to brittle fracture under ultrasonic-assisted shearing. The primary cause of this transformation between ductile and brittle is the effect of ultrasonic vibration on the material's internal energy. High-energy ultrasonic amplitude action causes magnesium to absorb a significant amount of ultrasonic energy. This results in an increase in the number of dynamic re-crystallization grains in the material organization, a decrease in the number of twins, and significant refinement of the grains. The sheet's hardness also changes along the rolling and normal directions, with a uniform distribution. The magnesium alloy sheet's fracture quality is optimal when the ultrasonic amplitude is 10 μm in the UAS process. This treatment results in notable enhancements in the section's straightness and brightness. Our study aims to advance the mass manufacturing of wide-format magnesium alloy sheets by investigating a cost-effective and high-yield technique for shearing magnesium alloy sheets.